DE102016212714A1 - Direct access mechanisms for link-budget-limited devices - Google Patents

Abstract

Mechanisms that allow link-budget-limited (LBL) devices to more efficiently perform random access may include: (1) Physical Random Access Channel (PRACH) Configuration Index (PCI) transmission ) reserved for LBL devices; (2) configuring the LBL devices to use a PCI offset from the conventional PCI of a current cell; (3) configuring the LBL devices to transmit the PRACH messages using an alternative set of subframes that differs from the conventionally defined subframe set; (4) configuring the LBL devices to transmit PRACH messages on odd-numbered frames when the conventional PRACH configuration specifies even-numbered frames; (5) configuring LBL devices to generate and use additional PRACH preambles that are not used by non-LBL devices; (6) Configure LBL devices to use group B preambles. while non-LBL devices are configured to use group A preambles; and (7) increasing the performance of a random access response message after an nth random access error, the preamble corresponding to an LBL reserved preamble pattern.

Description

FIELD OF THE INVENTION

The present invention relates to radio communication, and more particularly to mechanisms configured to enhance the random access procedure for terminal devices that are link budget constrained.

DESCRIPTION OF THE RELATED TECHNIQUE

Wireless terminal equipment (UE) devices, such as smartphones and tablet computers, communicate with wireless networks to perform any of a wide variety of functions, such as telephone calls, internet browsing, e-mail, text messaging, social media updates Navigation with the global positioning system (GPS, Global Positioning System) etc.

In LTE, the random access procedure (referred to herein as "RACH", Random Access Procedure) is a procedure for synchronizing the Terminal Equipment (UE) device with the network (NW). RACH may be used for: the first access from the UE device to the network; to handover the terminal device from one cell to another; to rebuild RRC; the arrival of uplink (or uplink) and / or downlink (or downlink) data; Positioning on an RRC connection. RACH is a procedure to allow the terminal to access the network in order to synchronize the uplink signals from various terminal devices and to obtain orthogonal resources. Therefore it is important to ensure that the news of the RACH is successfully exchanged.

However, some radios may be Link Budget Limited (LBL) and thus experiencing difficulties in receiving messages transmitted by the base stations of the network. The base stations may also experience difficulties in receiving messages transmitted by the link budget limited devices. A device may be link budget limited for any of a variety of reasons, for example
the antenna system of the device has poor performance; or the antenna system of the device is adapted to fit in a housing that is too small for optimum transmission and / or reception performance in the desired band;
the device is too far away from the base station; or obstacles between the base station and the device (eg, when the device is in a building); or
the battery power of the device is limited.

A link budget limited terminal device may have the restricted RF range in a downlink (receive) direction and / or in the uplink (transmission) direction. Thus, there is a need for mechanisms designed to improve the ability of link-budget-limited devices and base stations to efficiently exchange messages. In particular, there is a need for mechanisms designed to improve the performance of the random access procedure for link-budget-limited terminal devices. For such mechanisms, it would be desirable to be compatible (and / or simply extendable) to the existing LTE network, for example, with minimal or no impact on the LTE network capacity and / or minimal or no impact on the physical layers of LTE to simplify the implementation.

OVERVIEW

In one set of embodiments, the base station may be configured to transmit an alternative PRACH configuration index for use by link budget dedicated devices, the alternative PRACH configuration index being different from a conventional PRACH configuration index of the cell. The link-budget-limited devices may be configured to transmit PRACH messages using the PRACH configuration determined by the alternate index, while non-LBL devices (and / or older devices) may be implemented by the conventional index use the identified PRACH configuration. (The alternate PRACH configuration index may be selected such that the corresponding PRACH configuration has an allowable amount of PRACH transmission temporary opportunities that is extraneous to the allowable amount of the conventional PRACH configuration.) The base station receives PRACH messages from the LBL devices based on the alternative PRACH configuration and receives PRACH messages from the non-LBL Devices (and / or older devices) based on the conventional PRACH configuration. Thus, when the base station receives a given PRACH message, the base station can easily determine whether or not the PRACH message has been transmitted from an LBL device. The alternate index may be signaled by the base station in a new system information block, for example, a new system information block created for the purpose of signaling the PRACH parameter (s) to the LBL devices.

In one set of embodiments, the LBL devices may apply an offset to the conventional PRACH configuration index of the cell to obtain an LBL-specific index. The LBL devices may transmit PRACH messages using the PRACH configuration determined by the LBL-specific index, while non-LBL devices (and / or legacy devices) utilize the PRACH configuration identified by the conventional index. (The offset may be determined so that the corresponding PRACH configuration corresponding to the LBL-specific index has an allowable amount of PRACH transmission temporary opportunities that is extraneous to the allowable amount of the conventional PRACH configuration.)

In a group of embodiments, LBL devices may transmit PRACH messages using a modified PRACH configuration having (a) the same PRACH format and set of frames (SFNs) as the conventional PRACH configuration of the cell, and (b) an allowable amount of subframes that is elementary to the allowable subframe set of the conventional PRACH configuration. (In the context of LTE, the traditional PRACH configuration of the cell is identified by the PRACH configuration index signaled in the Type 2 system information block.) Non-LBL devices (and / or legacy devices) may transmit the conventional PRACH configuration for transmission use their PRACH messages.

In one set of embodiments, the LBL devices may transmit PRACH messages in odd-numbered frames if the conventional PRACH configuration of the cell indicates the use of even-numbered frames. Non-LBL devices (and / or legacy devices) may consider the conventional PRACH configuration when transmitting PRACH messages, including the restriction to even frames. The base station can thus easily determine whether or not a particular PRACH message corresponds to an LBL device based on whether the PRACH message occurs in an odd frame or an even frame.

In one set of embodiments, an LBL device may be configured to generate an extended set of preambles, including additional preambles beyond a conventional preamble amount for the cell. The LBL device may select a preamble from the additional preambles instead of the conventional set (eg, direct selection). The selected preamble can then be used to transmit a PRACH message. The base station can thus easily determine whether the included preamble belongs to the additional preambles or the conventional preambles, whether or not a particular PRACH message corresponds to an LBL device.

In one set of embodiments, a conventional set of PRACH preambles (eg, the conventional set defined by an existing radio communication standard such as LTE) may be divided into two groups, i. H. Group A and Group B. The base station may configure the use of Groups A and B so that non-LBL devices (and / or legacy devices) select Group A preambles and LBL devices select Group B preambles. Thus, when the base station receives a particular PRACH message, the base station may simply determine whether or not the PRACH message has been transmitted from an LBL device by determining the group membership (A or B) of the preamble contained in the PRACH message becomes.

The base station may use any of the mechanisms described above to determine whether a particular PRACH message has been transmitted by an LBL device. In response to the determination that the PRACH message has been transmitted from an LBL device, the base station may employ any of various mechanisms to improve the likelihood of successful completion of the random access procedure. For example, the base station may increase the transmission power of the random access response (msg2) transmitted to the LBL device in response to the received PRACH message, ie, an increase in performance over the power that would be used for a non-LBL device. (In the context of LTE, the random access response may be transmitted with an RA-RNTI consistent with the RA-RNTI of the received PRACH message.) As another example, the base station may use a more complex decoding algorithm and / or beamforming to increase the likelihood of successfully decoding msg3 of the random access procedure. As yet another example, the base station may increase the power of the downlink transmissions to the terminal device upon completion of the random access procedure. As yet another example, the base station may instruct the terminal device to use a lower coding rate (higher redundancy) and / or a lower modulation order for uplink transmissions.

In a group of embodiments, the base station may count the number of failed random access attempts whose preambles are consistent with an LBL-specific pattern of preamble indexes or preamble index offsets. If the counter exceeds a certain threshold, the base station may increase the performance increase of msg2 (i.e., the random access response message) on any subsequent random access attempt whose preamble is consistent with the LBL-specific pattern.

The status of a device as link budget limited may be a persistent state or an alternate state. For example, some devices may be link-budget limited if they are far away from an active base station, but become non-link budget-constrained (non-LBL) when they are closer to the base station. Some devices may be left-budget limited due to design, for example due to a smaller antenna system or limited power due to lower battery capacity, etc.

When a terminal device is link budget limited (LBL) by design, the terminal device may perform any of the currently disclosed methods without an explicit determination step as to whether the terminal device is link budget limited (or classified as link budget limited ). For example, whenever one of the currently disclosed methods refers to a terminal device that performs an action (or a set of actions) "in response to a determination that the terminal device is link budget limited", a terminal device, which is due to the design LBL, perform this action (this set of actions) without a determination step of the LBL status. The knowledge of the LBL status may be built into the software and / or hardware that controls the terminal device.

It should be understood that the techniques described herein may be implemented and / or used in a variety of different types of devices including, but not limited to, base stations, access points, mobile phones, portable media players, tablet computers, portable devices, and various other computing devices.

This overview is intended to provide a brief overview of the subject matter described in this document. Accordingly, it should be understood that the features described above are only examples and should not be construed in any way that would in any way limit the scope or spirit of the subject matter described herein. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following detailed description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtained when the following detailed description of the embodiments is taken in conjunction with the following drawings.

1A FIG. 12 illustrates an example of a radio communication system according to some embodiments. FIG.

1B illustrates an example of the base station 102 in communication with three wireless devices 106 ₁ , 106 ₂ and 106 ₃ , according to some embodiments.

2 illustrates a base station 102 in radio communication with the radio devices 106A and 106B according to some embodiments.

3 FIG. 12 illustrates an example of a radio communication system according to some embodiments. FIG. [0023] 4 illustrates an example of a base station according to some embodiments. [0024] 5A illustrates a PRACH preamble transmitted as part of an uplink frame. (PRACH is the acronym for Physical Random Access Channel.)

5B illustrates the structure of a conventional PRACH according to a possible format.

6 illustrates a cyclic prefix (CP) and sequence region of a PRACH.

7 illustrates messages that may be exchanged between a terminal device and a base station (e.g., eNodeB) as part of a random access procedure.

8th is a copy of the PRACH configurations listed in Table 5.7.1-2 of 3GPP TS 36.211.

9 FIG. 12 illustrates a method that enables a link-budget-limited terminal device to transmit a PRACH message with an alternative PRACH configuration index that differs from a conventionally-signaled PRACH configuration index.

10 FIG. 12 illustrates a method that enables a link budget limited terminal device to transmit a PRACH message with a PRACH configuration index that differs from a conventionally signaled PRACH configuration index.

11 and 12 illustrate methods in accordance with some embodiments that enable a link budget limited terminal device to transmit a PRACH message using an allowable amount of subframes that is different from that identified by the conventionally signaled PRACH configuration index.

13 FIG. 12 illustrates a method that enables a link-budget-limited terminal device to transmit a PRACH message using an odd-numbered frame when the conventional PRACH configuration specifies even-numbered frames as the allowable amount of PRACH transmission frames.

14 13 illustrates a method according to some embodiments that allows a link-budget-limited terminal device to generate further preambles beyond a conventionally-defined preamble amount and to transmit a PRACH message using a selected one of the further preambles.

15 FIG. 12 illustrates a method according to some embodiments that allows a link-budget-limited terminal device to perform PRACH transmission using a preamble selected from a subset of a conventionally-defined preamble set, while the non-LBL device is another subset of the conventional ones defined amount used.

16A 13 illustrates a method according to some embodiments that enables a terminal device to signal its status as a link-budget-limited device (to a base station) with a particular sequence of PRACH preamble index offsets for consecutive PRACH transmissions until a current PRACH transmission for the random access procedure to success.

16B FIG. 12 illustrates a method according to some embodiments that enables a terminal device to signal its status as a link-budget-limited device using a sequence of PRACH preamble index offsets (to a base station).

17 FIG. 12 illustrates a method according to some embodiments that allows a base station to facilitate successful completion of the random access procedure by link-budget-limited devices when it is not known which PRACH-transmitting devices are link-budget-limited and which are not.

Although the features described herein may be embodied in various modifications and alternative forms, specific embodiments thereof are illustrated by way of example in the drawings and described in detail herein. It is to be understood, however, that the drawings and detailed description thereof are not intended to be limited to the particular form disclosed, but on the contrary are intended to cover all modifications, equivalents, and To cover alternatives that fall within the spirit and scope of the subject matter as defined in the appended claims.

DETAILED DESCRIPTION

ACRONYMS

BS:

Basisstation

DL:

Downlink (Abwärtsstrecke)

LBL:

Link-Budget-Limited (Link-Budget-beschränkt)

LTE:

Long Term Evolution

MIB:

Master-Informationsblock

NW:

Netzwerk

PDCCH:

Physical Downlink Control Channel (Physischer Downlink-Kontrollkanal)

PDSCH:

Physical Downlink Shared Channel (Physischer gemeinsamer Downlink-Kanal)

PRACH:

Physical Random Access Channel (Physischer Direktzugriffskanal)

PUCCH:

Physical Uplink Control Channel (Physischer Uplink-Kontrollkanal)

PUSCH:

Physical Uplink Shared Channel (Physischer gemeinsamer Uplink-Kanal)

RACH:

Random Access Procedure (Direktzugriffsprozedur) oder Random Access Channel (Direktzugriffskanal)

RAR:

Random Access Response (Direktzugriffsantwort)

RA-RNTI:

Random Access – Radio Network Temporary Identifier (Direktzugriff – Temporäre Kennung des Funknetzwerks)

RRC:

Radio Resource Control (Funkressourcensteuerung)

RRC IE:

RRC Information Element (RRC-Informationselement)

RX:

Empfang

SFN:

System Frame Number (System-Rahmennummer)

SIB:

System Information Block (Systeminformationsblock)

SIBn:

Systeminformationsblock vom Typ n

TTI:

Transmit Time Interval (Übertragungszeitintervall)

TX:

Transmission (Übertragung)

UE:

User Equipment (Endgerät)

UL:

Uplink (Aufwärtsstrecke)

UMTS:

Universal Mobile Telecommunication System

ZC-Sequenz:

Zadoff-Chu-Sequenz

3GPP:

Third Generation Partnership Project

Various acronyms are used in the present disclosure. Definitions of the most commonly used acronyms that can be used in the present disclosure are listed below:

BS:

base station

DL:

Downlink (downlink)

LBL:

Link Budget Limited (Link Budget Limited)

LTE:

Long Term Evolution

MIB:

Master Information Block

NW:

network

PDCCH:

Physical Downlink Control Channel (Physical Downlink Control Channel)

PDSCH:

Physical Downlink Shared Channel (Physical Downlink Shared Channel)

PRACH:

Physical Random Access Channel (Physical Random Access Channel)

PUCCH:

Physical Uplink Control Channel (Physical Uplink Control Channel)

PUSCH:

Physical Uplink Shared Channel (Physical Shared Uplink Channel)

RACH:

Random Access Procedure or Random Access Channel

RAR:

Random Access Response

RA-RNTI:

Random Access - Radio Network Temporary Identifier (Temporary Identifier - Radio Network Temporary Identifier)

RRC:

Radio Resource Control

RRC IE:

RRC information element (RRC information element)

RX:

reception

SFN:

System Frame Number

SIB:

System Information Block

SIBN:

System information block of type n

TTI:

Transmit Time Interval

TX:

Transmission

UE:

User Equipment (terminal)

UL:

Uplink

UMTS:

Universal Mobile Telecommunication System

ZC sequence:

Zadoff-Chu sequence

3GPP:

Third Generation Partnership Project

TERMINOLOGY

The following is a glossary of the terms used in this disclosure:
Storage Medium - Any of various types of non-volatile storage devices (memory devices) or storage devices. The term "storage medium" is intended to include an installation medium, for example a CD-ROM, floppy disks or a tape device; a computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc .; a non-volatile memory such as a flash memory, magnetic media, for example, a hard disk or optical memory; Registers or other similar types of storage elements, etc. The storage medium may include other types of non-volatile memory as well as combinations thereof. Moreover, the storage medium may reside in a first computer system in which the programs are executed, or it may reside in a second different computer system connected to a first computer system via a network, such as the Internet. In the latter case, the second computer system may provide program instructions to the first computer for execution. The term "storage medium" may include two or more storage media that may be located at different locations, for example, in different computer systems connected to each other via a network. The storage medium may store program instructions (embodied, for example, as computer programs) that may be executed by one or more processors.

Carrier Medium - A storage medium, as described above, as well as a physical transmission medium, such as a bus, network and / or other physical transmission media, that carry signals such as electrical, electromagnetic or digital signals.

Programmable Hardware Element - Includes various hardware devices having multiple programmable functional blocks connected together via a programmable interconnect. Examples include Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), Field Programmable Object Arrays (FPOAs), and complex PLDs (CPLDs). The programmable function blocks can range from levels of detail (combinational logic or lookup tables) to higher levels (arithmetic logic units or processor cores). A programmable hardware element may also be referred to as a "reconfigurable logic".

Computer System - Any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network application, Internet application, personal digital assistant (PDA), television system, grid computing System or other device or combinations of devices. In general, the term "computer system" can be broadly defined to encompass any device (or combination of devices) having at least one processor executing instructions from a storage medium.

UE (User Equipment) (or "UE Device") - Any of various types of computer system devices that are mobile or portable and perform radio communication. Examples of terminal devices include mobile phones or smartphones (eg, iPhone ^™ , Android ^™ -based phones, etc.), portable gaming devices (e.g., Nintendo DS ^™ , PlayStation Portable ^™ , Gameboy Advance ^™ , iPhone ^™ ), laptops , PDAs, portable internet devices, music players, data storage devices, other handheld devices, portable devices (such as smartwatches), etc. In general, the term "terminal" or "terminal device" can be broadly defined to encompass any electronic, computing, and / or telecommunications device (or combination of devices) that can be easily transported by a user and that are capable of radio communication.

Base Station - The term "base station" has the full scope of its normal meaning, and includes at least one radio communication station installed at a fixed location and used as part of a mobile telephone system or radio system for communication.

Processing Element - Refers to various elements or combinations of elements. The processing elements include, for example, circuits such as an Application Specific Integrated Circuit (ASIC), areas or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices such as Field Programmable Gate Arrays (FPGAs), and / or larger system areas with multiple processors.

Channel - A medium used to transmit information from a transmitter to a receiver. It should be emphasized that, since properties of the term "channel" may differ in different radio protocols, the term "channel" as used in the present document may be considered as being used in a manner consistent with the standard type of device with respect to which the term is used is used. In some standards, the channel widths may be variable (eg, depending on the performance of the device, belt conditions, etc.). For example, LTE can support scalable channel bandwidths from 1.4MHz to 20MHz. In contrast, WLAN channels can be 22 MHz wide, while Bluetooth channels can be 1 MHz wide. Other protocols and standards may have different channel definitions. In addition, some standards may define and use multiple types of channels, for example, different uplink or downlink channels and / or different channels for different uses such as data, control information, etc.

Band - The term "band" has the full scope of ordinary meaning thereof and includes at least one spectrum portion (eg, radio frequency spectrum) in which the channels are used or intended for the same purpose.

Link budget limited - Includes the full extent of normal meaning and includes at least one feature of a radio (a terminal) that is limited Has communication capabilities or limited performance compared to a device that is not limited in link budget, or in relation to devices for which a radio access technology (RAT) standard has been developed. A terminal that is limited in link budget may experience relatively limited reception and / or transmission capabilities, which may be due to one or more factors, such as device design, device size, battery size, size, or design the antenna, the transmission power, the reception power, the states of the current transmission medium and / or other factors. Such devices may be referred to herein as "link-budget-limited" (or "link-budget-limited") devices. An apparatus may inherently be link-budget limited due to its size, battery power, and / or transmit / receive power. For example, a smart watch that communicates with a base station via LTE or LTE-A may inherently be link-budget limited due to its reduced transmit / receive power and / or smaller antenna size. Alternatively, a device may not inherently be link-budget constrained, for example, have sufficient size, battery power, and / or transmission / reception performance for normal LTE or LTE-A communication, but may temporarily be left-link due to current communication conditions. Budget constrained, for example, when a smartphone is on the edge of a cell, etc. It should be noted that the term "link budget constrained" includes or refers to performance limitations, and thus a performance limited device as a link Budget-limited device can be considered.

Automatic - Refers to an action or process taken by a computer system (for example, software running on a computer system) or device (eg, circuit, programmable hardware elements, ASICs, etc.) without direct user input to specify or perform the action or operation. Thus, the term "automatic" is used in contrast to a manually performed or user-specified operation in which the user provides inputs to perform the operation directly. An automatic procedure can be started by user input, but the subsequent actions that are performed "automatically" are not specified by the user; H. they are not performed in a "manual" manner where the user indicates each action to be taken. For example, a user manually fills in an electronic form by selecting each field and specifying certain information (e.g., by entering information, selecting check boxes, and selecting buttons, etc.), even if the computer system forms the form Response to the user actions needs to update. The form may be automatically populated by the computer system, with the computer system (eg, software running on the computer system) parsing the fields of the form and filling the form without providing responses to the fields with a user input. As stated above, the user can invoke the automatic completion of the form, but is not involved in actually filling in the form (eg, the user does not enter responses manually in fields, but they are entered automatically instead). The present description includes various examples of operations that are automatically performed in response to user-initiated actions.

Fig. 1 - radio communication system

1A illustrates an embodiment of a radio communication system. It should be emphasized that the system of 1A is only one possibility of many, and features of the present disclosure may be implemented in any of various systems as desired.

As illustrated, the example wireless communication system may be a base station 102A comprising, via a transmission medium having one or more radio devices 106A . 106B etc. until 106N communicated. Radio devices may be user devices, which may be referred to herein as "User Equipment" or "User Equipment Devices". Some of the radios may be Link Budget Limited (LBL), while others of the devices may be non-LBL.

The base station 102 may be a base transceiver station (BTS) or a cell site, and may include hardware that provides radio communication with the terminal devices 106A to 106N allows. The base station 102 can also be designed to, among other various possibilities with a network 100 (eg a core network of a mobile services provider, a telecommunications network such as a Public Switched Telephone Network (PSTN) and / or the Internet 102 the communication between the terminal devices 106 and / or between the terminal devices 106 and the network 100 enable.

The communication area (or coverage area) of the base station 102 can be called a "cell". The base station 102 and the terminals 106 may be configured to communicate over the transmission medium using any of a variety of radio access technologies (RATs), or wireless communication technologies such as GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE-Advanced (LTE-A), HSPA, 3GPP2 CDMA2000 (e.g. B. 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-Fi, WiMAX and so on.

The base station 102 and other similar base stations (not shown) operating in accordance with one or more mobile communication technologies may thus be provided as a network of cells providing a consistent or near-end overlapping service to the terminal devices 106A Provide -N and similar devices over a larger geographical area via one or more mobile communication technologies.

Thus, while the base station 102 at this time as the "active cell" for the terminal devices 106A -N can act as in 1A represented, each terminal can 106 also be configured to receive signals from one or more other cells (eg, cells that may be provided by other base stations), which may be referred to as "neighbor cells." Such cells may be configured for communication between user devices and / or between user devices and the network 100 to enable.

1B illustrates an example of the base station 102 in communication with three wireless devices 106 ₁ , 106 ₂ and 106 ₃ according to some embodiments. The radio devices 106 ₁ , 106 ₂ and 106 ₃ may be implemented by any combination of radio devices described above and / or described below.

It should be noted that at least in some cases a terminal device 106 may be configured to communicate using a plurality of mobile communication technologies. For example, a terminal device 106 using one or more of GSM, UMTS, CDMA2000, WiMAX, LTE, LTE-A, WLAN, Bluetooth, one or more Global Navigation Satellite Systems (GNSS, eg GPS or GLONASS), one and / or several radio television transmission standards z. ATSC-M / H or DVB-H) and so on. Other combinations of radio communication technologies (including more than two radio communication technologies) are also possible. Likewise, in some cases, a terminal device 106 be adapted to communicate using only a single wireless communication technology.

2 illustrates a terminal device 106 (eg one of the devices 106A to 106N ) in communication with a base station 102 , The terminal device 106 may have a mobile communication capability, and as described above, a device such as a mobile phone, a hand-held device, a media player, a computer, a laptop or a tablet, a portable device (such as a smart watch), or virtually any type be from radio device.

The terminal device 106 may include a processor configured to execute program instructions stored in a memory. The terminal device 106 Any of the embodiments described herein may perform methods by executing such stored instructions. Alternatively or additionally, the terminal device 106 a programmable hardware element such as an FPGA (Field Programmable Gate Array) configured to perform any of the method embodiments described herein or any portion of any of the method embodiments described herein.

In some embodiments, the terminal device may 106 be configured to communicate with any one of a plurality of radio access technologies and / or radio communication protocols. For example, the terminal device 106 be configured to communicate by means of one or more of GSM, UMTS, CDMA2000, LTE, LTE-A, WLAN, Wi-Fi, WiMAX or GNSS. Other combinations of radio communication technologies are also possible.

The terminal device 106 may include one or more antennas for communication by means of one or more radio communication protocols or technologies. In one embodiment, the terminal device 106 be configured to communicate by means of a single common radio device. The common radio device may be connected to a single antenna or to multiple antennas for radio communication (eg for MIMO). Alternatively, the terminal device 106 contain two or more radio channels. For example, the terminal may 106 a common radio device for communication over either LTE or 1xRTT (or LTE or GSM) and separate radio devices for communication over each of WiFi and Bluetooth. Other configurations are possible as well.

Fig. 3 - Exemplary block diagram of a terminal

3 illustrates a possible block diagram of a terminal 106 , As shown, the user device 106 a system-on-chip (SOC) 300 which may have areas for different purposes. For example, the SOC 300 , as shown, processor (s) 302 contain the program instructions for the terminal 106 and the display circuit 304 who can do the graphics processing and display 340 Can provide display signals. The processor (s) 302 can also be used with the Memory Management Unit (MMU) 305 which may be configured to receive addresses from the processor (s) 302 and receive these addresses in memory locations (eg memory 306 and read-only memory (ROM) 350 , NAND flash memory 310 ) to translate. The MMU 305 may be configured to perform memory protection and page table translation or setup. In some embodiments, the MMU 305 Part of the processor (s) 302 be.

The terminal device 106 may also include other circuits or devices, such as the display circuit 304 , the radio device 330 , the connector interface 320 and / or the ad 340 ,

In the illustrated embodiment, the ROM 350 include a bootloader that is owned by the processor (s) 302 at boot time or initialization. As also shown, the SOC 300 with various other circuits of the terminal 106 be connected. For example, the terminal may 106 different types of memory (for example, NAND flash memory 310 ), a connector interface 320 (for example, to connect to a computer system), the display 340 and a radio communication circuit (eg, for communication by LTE, CDMA2000, Bluetooth, WiFi, GPS, etc.).

The terminal device 106 may comprise at least one antenna and, in some embodiments, a plurality of antennas for performing the radio communication with base stations and / or other devices. For example, the terminal device 106 an antenna 335 to perform the radio communication. As described above, in some embodiments, the terminal may be configured to communicate over the air using multiple radio communication standards.

As described here, the terminal may 106 Include hardware and software components for implementing any of the terminal-related method embodiments described herein.

The processor 302 the terminal device 106 may be configured to implement some or all of the methods described herein, for example, by executing program instructions stored on a storage medium (eg, a non-transitory computer-readable storage medium). In other embodiments, the processor 302 be designed as a programmable hardware element, such as a FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

Fig. 4 - base station

4 illustrates an embodiment of a base station 102 , It should be emphasized that the base station of 4 just an example of a possible base station. As shown, the base station 102 Processor (s) 404 contain the program instructions for the base station 102 To run. The processor (s) 404 can also use the Storage Management Unit (MMU) 440 which may be configured to receive addresses from the processor (s) 404 and receive these addresses in memory locations (eg memory 460 and read-only memory (ROM) 450 ) or to translate into other circuits or devices.

The base station 102 can at least one network port 470 exhibit. The network port 470 may be configured to be connected to a telephone network and a plurality of devices, such as terminal devices 106 to provide access to the telephone network as described above.

The network port 470 (or another network port) may also or alternatively be configured to connect to a cellular network, for example a core network of a cellular service provider. The core network may include mobility related services and / or other services for multiple devices, such as the terminal devices 106 , provide. In some cases, the network port 470 have a connection to a telephone network over the core network and / or the core network may provide a telephone network (eg between other terminal devices serviced by the mobile service provider).

The base station 102 can be a radio device 430 , a communication chain 432 and at least one antenna 434 contain. The base station may be configured to operate as a radio transceiver and may be further configured with terminal devices 106 via a radio device 430 , the communication chain 432 and the at least one antenna 434 to communicate. The communication chain 432 can be a chain of receipts, a transmission chain, or both. The radio device 430 may be configured to communicate over various radio access technologies, including, but not limited to, GSM, UMTS, LTE, WCDMA, CDMA2000, WiMAX, etc.

The processor (s) 404 the terminal device 102 may be configured to implement some or all of the methods described herein, for example, by executing program instructions stored on a storage medium (eg, a non-transitory computer-readable storage medium). Alternatively, the processor 404 be designed as a programmable hardware element such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) or as a combination thereof.

PRACH specifications in 3GPP

5A illustrates a preamble 500 in a physical random access channel (PRACH) according to existing LTE specifications. A terminal device transmits the PRACH preamble into an uplink frame 510 to initiate the random access procedure. (The uplink frame contains several subframes.) The temporal offset and the frequency offset of the PRACH preamble in the uplink frame can be determined by the higher layer signaling.

5B illustrates a particular implementation of the PRACH preamble according to existing LTE specifications. In frequency, the PRACH preamble (including the guard subcarriers at the beginning and at the end) spans 6 RBs = 1.08 MHz. In terms of time, the PRACH preamble spans an uplink subframe with the cyclic prefix (CP, Cylic Prefix) and the guard time (GT, Guard Time).

Formats 0 through 3 for the PRACH preamble each use a Zadoff Chu sequence of length 839, whereas format 4 uses a Zadoff Chu sequence of length 139.

The PRACH preamble occupies six resource blocks (RBs) in the uplink bandwidth (UL BW).

A PRACH subcarrier occupies 1.25 kHz, whereas a normal UL subcarrier occupies 15 kHz. The symbols of the Zadoff-Chu sequence are transmitted to corresponding ones of the PRACH subcarriers.

Regarding the PRACH preamble illustrated 6 a cyclic prefix (CP) of duration T _CP and a sequence range of duration T _SEQ . (The sequence area contains the Zadoff-Chu sequence.) Table 1 below shows the values of T _CP and T _SEQ in various formats of the PRACH preamble. Table 1: Direct Access Preamble Parameters preamble format T _CP T _SEQ 0 3168 * T _S 24576 * T _S 1 21024 * T _S 24576 * T _S 2 6240 * T _S 2 * 24576 * T _S 3 21024 * T _S 2 * 24576 * T _S 4 448 * T _S 4096 * T _S

Summary of the RACH procedure

The RACH procedure may include a series of messages sent between the user equipment and the base station, as in 7 shown.

In a first message (MSG1), the user equipment transmits the PRACH preamble to the base station (i.e., eNodeB in LTE's language usage). The PRACH preamble may be configured according to any of the formats discussed above or any other format.

In response to decoding the first message, eNodeB transmits a second message (MSG2). The second message may be referred to as Random Access Response (RAR). The PDSCH of the RAR message may include an uplink grant. The uplink grant can be identified by uplink resources in the PUSCH for the UE to transfer the uplink data.

In response to the decoding of the second message, the terminal may transmit a third message (MSG3). In the PUSCH of MSG3, the terminal can transmit uplink data. The content of the third message may vary in different contexts, for example, depending on the purpose for which the RACH procedure was invoked. For example, the third message may include an RRC Request, Scheduling Request (SR), etc.

In response to receiving the third message, the eNodeB may transmit a fourth message (MSG4), for example a message to resolve an access conflict.

Channels in LTE

LTE uses different channels so that data can be transported over the LTE radio interface. These channels separate different types of data and can be transmitted in an orderly manner over the radio access network. The various channels effectively provide interfaces for the higher layers in the LTE protocol structure and allow for an orderly and defined separation of the data.

There are the following three categories or types of LTE data channels.

Physical Channels: These are broadcast channels that contain user data and control messages.

Transport Channels: The transport channels provide information transfer for the Medium Access Control (MAC) layer and higher layers.

Logical Channels: Provide services for the Medium Access Control (MAC) layer in the LTE protocol tree.

LTE defines several physical downlink channels for transmitting information received from the MAC layer and higher layers. The LTE downlink comprises a physical downlink shared channel (PDSCH) and a physical downlink control channel (PDCCH). The PDSCH is the main data channel that is assigned to users on a dynamic and opportunistic basis. The PDCCH contains control information indicating how the resources in the PDSCH are available to user devices.

LTE random access configuration

There are many possible PRACH configurations in the direct access procedure of LTE. For each of the cells, the associated eNodeB signals one of the PRACH configurations (by sending the index of the PRACH configuration in SIB2) to be used by devices attempting random access in that cell. This PRACH configuration determines the preamble format and allowable time resources that devices in the cell can use in transmitting the PRACH. The allowable time resources may include System Frame Numbers (SFNs) and Subframe Numbers (SFNs). 8th shows the PRACH configurations defined in Table 5.7.1-2 of 3GPP TS 36.211. Each PRACH configuration has a corresponding index identifying the positions in the list of PRACH configurations.

LTE Direktzugriffspräambeln

In LTE, the terminals in a particular cell may initiate random access by transmitting preambles selected from a preamble set. (Each terminal may optionally select a preamble from the preamble set.) The terminal generates the preamble amount using a root sequence number provided by the eNodeB in SIB2. For a given cell, the preamble amount can be up to 64 preambles, and the 64 preambles are divided into two groups: group A and group B.

The eNodeB also sends (in SIB2) the following parameters for configuring the use of preamble sets: numberOfRA preambles is the number of unshared random access preambles available in the cell; messageSizeGroupA is the limit for preamble selection (in bits); sizeOfRA-PreamblesGroupA is the size (that is, the number) of random access preambles in group A. These parameters are included in RACH-ConfigCommon. The number of preambles in group B equals the difference 'numberOfRA-Preambles' - 'sizeOfRA-PreamblesGroupA'.

According to the LTE specifications, a terminal selects a group B preamble if the size of the UL message to be transmitted from the terminal is greater than messageSizeGroupA and the path loss is less than a path loss threshold.

The terminal may measure path loss based on RSCP. (RSCP is the abbreviation for Reference Signal Code Power.) The network can send the cell reference signal strength that has been transmitted to the eNodeB in system information blocks (SIBs). The terminal measures the received cell reference signal strength. The difference between the cell reference signal strength and the received value is the path loss.

The path loss limit can be determined based on the expression: PathLossThreshold = P _CMAX - preamblelnitialReceivedTargetPower - deltaPreambleMsg3 - messagePowerOffsetGroupB, in which
P _{CMAX is} the maximum transmission power of the terminal;
preamblelnitialReceivedTargetPower is the network expected received power for the first random access attempt (RACH preamble);
deltaPreambleMsg3 is the power offset between the power of the preamble and Msg3, and
messagePowerOffsetGroupB is the power offset for preambles in group B.

The following is the definition of the RACH ConfigCommon information element according to LTE:

Direct access - terminal identification in MSG1 (PRACH message)

In one set of embodiments, the link budget limited device may be configured to transmit PRACH messages having a different PRACH configuration than the non-LBL devices. (The non-LBL devices may use the conventionally signaled PRACH configuration.) Thus, based on whether the PRACH message corresponds to the other PRACH configuration or the conventionally signaled PRACH configuration, the base station is able to determine whether a received PRACH message corresponds to an LBL device or not. For a device that is designated as LBL, the base station may call one or more mechanisms to increase the likelihood of successfully completing the random access procedure for the LBL device. For example, the base station may increase the transmission power of the msg2 (i.e., the random access response message) for the LBL device.

In one embodiment, the eNodeB may send out an alternative PRACH configuration index for use with link-budget-limited devices that is different from the current PRACH configuration index of the current cell. (The alternative PRACH configuration index may also differ from the conventional PRACH configuration indices of neighbor cells.) When the LBL devices transmit the PRACH messages, they may use the PRACH configuration identified by the alternate PRACH configuration index. (The conventional PRACH configuration index is signaled in SIB 2. However, the alternate PRACH configuration index may be included in a special SIB for the LBL terminal device, ie, a new SIB that is created to facilitate the transmission of the RACH configuration information for the LBL devices On the other hand, when the non-LBL devices transmit PRACH messages, they use the PRACH configuration corresponding to the conventional PRACH configuration index.

In another embodiment, the LBL devices may be configured to utilize an alternative PRACH configuration index offset from the current PRACH configuration index of the current cell by a particular offset. The LBL devices in the cell can transmit PRACH messages according to the PRACH configuration identified by the alternative PRACH index, while the non-LBL devices in the cell transmit PRACH messages according to the PRACH configuration determined by the conventional PRACH configuration index , Each LBL device may receive the conventional PRACH configuration index from the base station (eg, from SIB2) and calculate the alternate index by adding the determined offset. The base station may determine whether or not a particular PRACH message corresponds to an LBL device by determining whether the PRACH format, the SFN, and the subframe number of the PRACH message are consistent with the alternative PRACH configuration or the conventional PRACH configuration are.

In yet another embodiment, the LBL devices may use the preamble format and SFNs defined by the conventionally-signaled PRACH configuration, but use a set of allowable subframes that is different from the allowable subframe set defined by the conventionally-signaled PRACH configuration. Thus, the LBL devices transmit PRACH messages in the same frame as non-LBL devices but in different subframes. For example, according to the PRACH configuration 6, only the subframes 1 and 6 are conventionally allowed for PRACH transmission. (See the table in 8th In this case, eNodeB may allow LBL devices to use subframes 0,2-5, 7-9 (or any subset of these subframes) to transmit PRACH messages. The one or subframes available for use by the LBL devices may be sent out in a special SIB.

In yet another embodiment, when the conventionally-signaled PRACH configuration of a particular cell involves the use of even-numbered SFNs (eg, configurations that use the Indices 0-2 and 15-18) for the transmission of PRACH messages, the LBL devices may instead use the odd SFNs, but take into account the preamble format and the allowable subframes defined by the conventionally signaled PRACH configuration. For example, if the conventionally signaled PRACH configuration index is 2, the LBL devices transmit their PRACH messages in odd-numbered frames, in sub-frame 7 and in preamble format 0.

In a group of embodiments, the set of available preambles in a cell may be extended to include further preambles beyond the conventional preamble amount. The further preambles may be used by the LBL devices to transmit the PRACH messages while the preambles of the conventional set are used by the non-LBL devices. For example, in one embodiment, an LBL device may generate an extended set of 128 preambles using the root sequence number provided by eNodeB. The extended set of 128 preambles may contain the 64 preambles of the conventional set and 64 more preambles. The LBL device may select a preamble from the 64 additional preambles (eg, random selection). Since the LBL devices and non-LBL devices use non-preamble sets of preambles to transmit their PRACH messages, the base station can easily determine whether or not a particular PRACH message corresponds to an LBL device by varying the quantity membership (conventional set or LBL-specific amount) of the preamble contained in the PRACH message. While the above discussion is cited with an example in which the number of further preambles is 64, it will be understood that this number may take on any of a variety of values, for example, depending on the expected or average number of LBL devices in FIG the cell. In some embodiments, the number of further preambles is dynamically configurable, for example, based on system information transmitted by the base station.

In a group of embodiments, at least a subset of the preambles of group B may be reserved for PRACH transmissions (or PRACH transmissions related to the establishment of connections) through link-budget-limited devices. (Compare the above discussion of groups A and B.) eNodeB can configure the cell so that the desired number of preambles is assigned to group B and can loosen the path loss threshold. (The path loss threshold may be relaxed by setting the path loss threshold to a value sufficiently large to ensure or increase the likelihood that the LBL terminal devices will pass the path loss test for the use of group B. It should be noted that the LBL Terminal devices typically have higher values for path loss than non-LBL devices.) Alternatively or additionally, the eNodeB may specify 'messageSizeGroupA' such that non-LBL devices do not use the group B preambles (or the group B- Rarely use preambles).

In some embodiments, the eNodeB may determine whether a received preamble (i.e., the preamble of a received PRACH message) belongs to group A or group B. If the preamble belongs to group B, eNodeB may identify the terminal device that has transmitted the preamble as LBL device and transmit to the terminal device a message with random access response that allocates sufficient uplink resources to the terminal device to establish a connection, although the allocated uplink resources in the total size may be smaller than the 'messageSizeGroupA'. Also, upon detecting that the preamble belongs to group B, the eNodeB may increase the power of the messages (MSG2 and subsequent messages) for the LBL device.

In a group of embodiments, a method 900 for operating a terminal (UE) device, as in 9 illustrated, performed. (The procedure 900 may also include any subset of the features, elements, and embodiments described above 1 - 8th and in the following reference 10 - 17 be described.) The procedure 900 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous.

While the procedure 900 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or several steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 910 For example, the processing _agent may receive an index I _LBL transmitted by a base station. The index I _LBL identifies a first configuration for transmitting a physical random access channel (PRACH) through link budget limited terminal devices in a cell corresponding to the base station. The index I _LBL differs from an index I _NLBL , which is also transmitted by the base station, ie the numerical value of index I _LBL is not equal to the index I _NLBL . The index I _NLBL identifies a second configuration for transmitting the PRACH through non-link budget limited terminal devices (and / or legacy devices) in the cell, the second configuration being different from the first configuration.

In 915 For example, in response to a determination that the terminal device has been classified as link budget restricted, the processing agent may transmit the PRACH to the base station, wherein the PRACH is transmitted in accordance with the first configuration. (In contrast, the terminal device may, in response to a determination - for example at a later time - that the terminal device has been classified as non-link budget restricted, perform the PRACH transfer according to the second configuration.)

In some embodiments, the base station may be configured to transmit a first system information block and a second system information block, wherein the first information _block includes the first index I _LBL and the second system information _block includes the second index I _NLBL . The link budget limited terminal device may read the first SIB to determine the index I _LBL . More generally, any terminal device that is limited in link budget can restore the index I _LBL from the first SIB. (In contrast, any terminal device that is non-link budget limited can recover the index I _LBL from the second SIB.)

In some embodiments, the second system information block is a type 2 system information block as defined in the LTI standard.

In some embodiments, the first configuration indicates a first set of allowable temporary opportunities (e.g., allowable subframes) for transferring the PRACH through link budget limited terminal devices, and the second configuration provides a second set of allowable temporary opportunities to transfer the PRACH PRACH by non-link budget limited terminal devices, where the first set and the second set are non-elemental sets.

In some embodiments, Index I _LBL identified the first configuration from a list of PRACH configurations defined by an existing mobile communication standard, and the index I _NLBL identifies the second configuration from the same list. (eg, the list of configurations may be the list of PRACH configurations given in 3GPP TS 36.211.) The terminal device may store a copy of the list and access the first configuration from the list based on the index I _LBL . If the terminal device is not link budget limited, for example at a later time, the terminal device may access the second configuration from the list based on the index I _NLBL and a PRACH transfer using the second configuration instead of using the first one Perform configuration.

As stated above, the index I _LBL differs from the index I _NLBL . In some embodiments, the index I _LBL also differs from one or more other PRACH configuration indices, each sent from one or more neighboring base stations, wherein the one or more other PRACH configuration indices are restricted for use by non-link budget Terminal devices are transmitted in one or more further cells, each corresponding to the one or more other base stations. In some embodiments, each of the plurality of neighboring base stations may be configured to perform procedures 900 perform. The base stations may be configured so that each base station selects the index I _LBL thereof to be different from its index I _NLBL and different from the index I _LBL and the index I _NLBL transmitted by the other base stations.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 9 and below in terms of 10 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing _{agent can} send out an index I _LBL . The index I _LBL identifies a first configuration for transmitting a physical random access channel (PRACH) through link budget limited terminal devices in a cell corresponding to the base station. The index I _LBL differs from an index I _NLBL , which is also transmitted by the base station, ie the numerical value of the index I _{LBL is} not equal to the index I _NLBL . The index I _NLBL identifies a second configuration for transmitting the PRACH through non-link budget limited terminal devices (and / or legacy devices) in the cell, the second configuration being different from the first configuration.

The processing agent may receive a PRACH, i. H. a PRACH transmitted from a terminal device. The processing agent may determine whether the PRACH has been transmitted according to the first configuration or according to the second configuration. The first configuration and the second configuration may have different preamble formats and / or different allowable system frame numbers and / or different allowable subframe numbers. Any or all of these differences may be used as the basis for determining whether the PRACH has been transmitted according to the first configuration or according to the second configuration.

In response to the determination that the PRACH has been transmitted according to the first configuration, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the UE device.) On the other hand, if the processing agent determines that the PRACH has been transmitted according to the second configuration, the processing agent can not call the one or more communication optimization mechanisms.

In a group of embodiments, a method 1000 for operating a terminal device as in 10 illustrated, performed. (The procedure 1000 may also include any subset of the features, elements, and embodiments described above 1 - 9 and in the following reference 11 - 17 be described.) The procedure 1000 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1000 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1010 For example, the processing agent may receive a first index transmitted by a base station, the first index having a first configuration for transmitting a physical data Identify random access channel (PRACH) of non-link budget limited terminal devices in a cell of the base station. The first index may be the PRACH configuration index, conventionally signaled by the eNodeB of LTE. In other words, the first index may be a PRACH configuration index corresponding to the LTE radio communication standard, for example as defined in 3GPP TS 36.211.

In 1015 For example, the processing agent may add an offset (ie, an offset other than o) to the first index to obtain a second index, the second index identifying a second configuration for transmitting the PRACH through link-budget-limited devices in the cell. The second configuration is different from the first configuration.

In 1020 For example, in response to a determination that the terminal device has been classified as link budget constrained, the processing agent may transmit a PRACH to the base station, the PRACH being transmitted in accordance with the second configuration. (In contrast, in response to a determination - for example, at a later time - that the terminal device has been classified as non-link budget-limited, the terminal device may perform the PRACH transfer according to the first configuration, that is, through the In some embodiments, the first configuration indicates a first set of allowable temporary opportunities (e.g., allowable subframes) for transmitting the PRACH, and the second configuration gives a second set of allowable temporary opportunities to transmit the PRACH wherein the first amount and the second amount are non-elemental amounts.

In some embodiments, the base station is configured to transmit the first index as part of SIB2 (i.e., the Type 2 system information block) as defined by the specifications in 3GPP TS 36.331.

In some embodiments, the first index I _{LBL identifies} the first configuration from a list of PRACH configurations defined by an existing mobile communication standard, and the second index identifies the second configuration from the same list of PRACH configurations. (For example, the list of PRACH configurations may be the list defined in 3GPP TS 36.211.) In some embodiments, the addition of the offset described above is an addition of Modulo N _LIST , where N _{LIST is} the number of PRACH configurations in the list.

In some embodiments, the method comprises 1000 also: (a) receiving a third index transmitted by a second base station, the third index identifying a third configuration for transmitting the PRACH through non-link budget limited terminal devices in a second cell corresponding to the second base station; (b) adding the same offset (ie the offset from step 1015 ) to the third index to obtain a fourth index, the fourth index identifying a fourth configuration for transmitting the PRACH over link budget limited terminal devices in the second cell; and (c) transmitting the PRACH to the second base station, this PRACH being transmitted according to the fourth configuration.

In some embodiments, the offset may be used by a plurality of base stations including the said base station.

In some embodiments, each of the plurality of neighboring base stations may be the method 1000 To run. Different ones of the base stations may each transmit different values of the first index, but use the same offset to determine their corresponding values for the second index.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 10 and in the following reference 11 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to receive radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing _{agent may} send the index I _CONV , the index I _{CONV identifying} a first configuration for transferring a physical random access channel (PRACH) through non-link budget limited terminal devices (and / or legacy devices) in a cell of the base station. The index I _CONV may be the PRACH configuration index, which is conventionally signaled by LTE base stations. Non-link budget limited terminal devices and / or legacy terminal devices in the cell may receive the index I _CONV and perform the PRACH transmission with the first configuration. In contrast, link budget limited terminal devices in the cell may perform PRACH transmissions with a second configuration offset from the first configuration by a known distance in a list of allowable configurations, ie, a distance, the base station, and the link budget Restricted terminal devices is known. Compare for example 8th ,

After the index I _{CONV has been} sent out, the processing agent can receive a PRACH, ie a PRACH transmitted by a terminal device.

The processing agent may analyze the PRACH for determination as to whether it has been transmitted according to the first configuration or according to the second configuration. The first configuration and the second configuration may have different preamble formats and / or different allowable system frame numbers and / or different allowable subframe numbers. Any or all of these differences may be used as the basis for determining whether the PRACH has been transmitted according to the first configuration or according to the second configuration.

In response to determining that the PRACH has been transmitted in accordance with the second configuration, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the UE device.) In contrast, if the processing agent determines that the PRACH has been transmitted in accordance with the first configuration the processing agent does not call the one or more communication optimization mechanisms.

In a group of embodiments, a method 1100 for operating a terminal device as in 11 illustrated, performed. (The procedure 1100 may also include any subset of the features, elements, and embodiments described above 1 - 10 and in the following reference 12 - 17 be described.) The procedure 1100 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1100 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1110 For example, the processing agent may receive an index transmitted by a base station, the index identifying a physical direct access channel (PRACH) transmission configuration, the configuration having a conventionally defined set of allowable subframes for transmitting the PRACH. The conventionally defined amount can be used by PRACH transmissions Non-link budget limited terminal devices and / or older devices in a cell corresponding to the base station. The conventionally defined amount may be an amount of the allowable subframes defined by a radio communication standard such as LTE. For example, the conventionally defined amount may be the set of allowable subframes corresponding to a selected one of the PRACH configurations defined in 3GPP TS 36.211. (See Table 5.7.1-2 of this technical specification.) The index described above may be an index for Table 5.7.1-2 of 3GPP TS 36.211.

In 1115  For example, the processing agent may transmit the PRACH to the base station in response to a determination that the terminal device has been classified as link budget constrained. The PRACH can be transmitted in a subframe from an alternative set of allowable subframes, the alternative amount to the conventional set of allowable subframes being element alien. In some embodiments, the terminal device may optionally select a subframe from the alternative set. The alternative set of allowable subframes may be reserved for use by link budget limited terminal devices. The link budget limited terminal devices may be configured to use the alternative amount (as opposed to the conventionally defined amount) when selecting a subframe for PRACH transmission.

In some embodiments, the base station is configured to send system information identifying the alternative set of allowed subframes.

The base station may be configured to monitor the alternative set of allowed subframes for PRACH transmissions from link budget limited terminal devices, and the conventionally defined set of allowed subframes for PRACH transmissions from non-link budget restricted terminal devices and / or or older terminal devices. The ability for link-budget-limited terminal devices to perform PRACH transmissions using allowed subframes that are element alien to those subframes used by non-LBL devices and / or older devices allows the base station to receive PRACH messages. Transfers from the link budget limited terminal device (s) with less interference and thus decoding these PRACH transfers with a lower probability of error.

In some embodiments, the base station is configured to broadcast the index as part of the Type 2 system information block as defined in the LTE standard.

In some embodiments, the method 1100 Also, in response to a determination that the UE device has been classified as not having a link budget constraint, transmitting another PRACH to the base station, wherein the other PRACH is transmitted in a subframe from the conventionally defined set of allowed subframes.

In some embodiments, the PRACH transmission configuration also specifies a PRACH transmission format, for example, one of the PRACH formats defined in 3GPP TS 36.211. The PRACH described above (ie the PRACH of step 1115 ) can be transmitted according to the specified format.

In some embodiments, the configuration for transmitting the PRACH also indicates a condition for allowable frames, such as in 8th shown. The PRACH described above may be transmitted in a frame corresponding to the allowable frame condition.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 11 and in the following reference 12 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing agent may send out an index, the index identifying a configuration for transmitting a physical random access channel (PRACH). The configuration may have (conventionally) a conventionally defined set of allowable subframes for transmission of the PRACH. The conventionally defined amount may be used for PRACH transmission by non-link budget limited terminal devices (and / or legacy devices) in a cell corresponding to the base station. (The conventionally defined set may be the set of allowable subframes defined by a radio communication standard such as LTE.) In contrast, the link budget limited terminal devices may be configured to perform the PRACH transfers using an alternative set of allowable subframes, which are elementary to the conventionally defined amount.

In addition to a conventionally defined set of allowable subframes, the PRACH configuration may identify a preamble format and specify a condition for allowable frames for the PRACH transmission. (Compare for example 8th .) When performing PRACH transmissions, the link budget limited terminal devices may use the identified preamble format and use frames that conform to the allowed constraints.

After the index has been sent out, the processing agent can receive a PRACH, i. H. a PRACH transmitted from a terminal device. The processing agent may determine whether the PRACH has been transmitted in one of the subframes of the alternative set or a subframe of the conventionally defined set.

In response to determining that the PRACH has been transmitted in one of the alternate set subframes, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the UE device.) In contrast, if the processing agent determines that the PRACH is in one of the subframes of the conventionally defined set has been transferred, the processing agent can not call the one or more communication optimization mechanisms.

In a group of embodiments, a method 1200 for operating a terminal device as in 12 illustrated, performed. (The procedure 1200 may also include any subset of the features, elements, and embodiments described above 1 to 11 and in the following reference 13 to 17 be described.) The procedure 1200 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1200 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1210 For example, the processing agent may receive an index transmitted by a base station. The index identifies a first configuration from a list of physical random access channel (PRACH) transmission configurations. Each configuration in the list may include:
a corresponding conventionally defined set of allowable subframes for PRACH transmission by non-link budget limited terminal devices (and / or legacy devices) in a cell corresponding to the base station; and
a corresponding alternative set of allowed subframes for transmitting the PRACH over link budget limited terminal devices in the cell, the corresponding alternative set being element alien to the corresponding conventionally defined set.

The list of configurations may be stored in a memory of the terminal device.

In 1215 For example, the processing agent may transmit the PRACH to the base station in response to a determination that the terminal device has been classified as link budget constrained. The PRACH can be transmitted in one of the subframes from the alternative set of permissible subframes according to the index. If the status of the terminal device changes to non-link budget-limited, the terminal device may transmit a PRACH in one of the sub-frames of the conventionally-defined set.

In a group of embodiments, a method 1300 for operating a terminal device as in 13 illustrated, performed. (The procedure 1300 may also include any subset of the features, elements, and embodiments described above 1 to 12 and in the following reference 14 to 17 be described.) The procedure 1300 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1300 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1310 For example, the processing agent may receive an index transmitted by a base station. The index identifies a physical random access channel (PRACH) transmission configuration. The configuration may indicate that the transmission of the PRACH by non-link budget limited terminal devices (and / or legacy devices) is limited to even frames and a conventionally defined set of allowable subframes. (Uplink frames are numbered consecutively, for example with a system frame number.)

In 1315 For example, in response to a determination that the terminal device has been classified as link-budget-restricted, the processing agent may transmit the PRACH to the base station, wherein the PRACH is transferred in an odd frame and in one of the subframes from the conventionally defined set. By using an odd frame, the link budget limited terminal device avoids the even frames used by non-link budget limited terminal devices to PRACH transmissions. This strategy allows the base station to receive the PRACH transmission from the link budget limited terminal device without interference from the PRACH transmissions from non-LBL terminal devices (and / or older devices), and thus the decoding of the PRACH transmission by the link Budget-limited terminal device with a lower probability of error. The base station may be configured to monitor the even frames for PRACH transmissions from non-LBL terminal devices (and / or legacy devices) and to monitor the odd frames for PRACH transmissions from link budget limited terminal devices.

In some embodiments, the configuration also specifies a format for PRACH transmission, for example, one of the formats defined in the LTE standard and listed in the "Preamble Format" column of Table 5.7.1-2 of 3GPP TS 36.211. (A copy of this table is in 8th The transmission of the PRACH to the base station, ie the transmission in step 1315 , can be made according to this format. The index can be interpreted as the PRACH configuration index of the table. Each value of the PRACH configuration index may identify a corresponding PRACH configuration including one or more of the following: a corresponding preamble format value, a corresponding condition for the system frame number (eg, a selection of "even" or "any") and a corresponding one conventionally defined amount of allowable subframes.

In some embodiments, the method 1300 also, in response to a determination that the UE device has been classified as not having a non-link budget constraint, transmitting another PRACH to the base station, wherein the other PRACH is in an odd frame and in one of the subframes from the conventionally defined set is transmitted.

In some embodiments, the base station is configured to transmit the index as part of SIB2 (i.e., the Type 2 system information block) as defined in the LTE standard.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 12 and in the following reference 13 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing agent can send out an index. The index may identify a configuration for transmission of a physical random access channel (PRACH). The configuration may indicate (or indicate) that the transmission of the PRACH by non-link budget limited terminal devices (and / or legacy devices) is limited to even frames and a conventionally defined set of allowable subframes.

After the index has been sent out, the processing agent can receive a PRACH, i. H. a PRACH transmitted from a terminal device. The processing agent may determine whether the PRACH has been transmitted in an even frame or an odd frame. (The processing agent can maintain a system frame number that is incremented from one uplink frame to the next.)

In response to the determination that the PRACH has been transmitted in an odd-numbered frame, the processing agent may call one or more mechanisms for optimizing communication for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the UE device.) In contrast, if the processing agent determines that the PRACH has been transmitted in an odd frame, then the processing agent does not call the one or more communication optimization mechanisms.

Background to the conventional PRACH sequence set

wobei die Länge N_ZC der Root-Sequenz x_u durch die Tabelle 5.7.2.1 von TS 36.211 gegeben ist.3GPP TS 36.211 specifies a list of logical root sequence numbers and corresponding physical root sequence numbers for the physical random access channel (PRACH). Compare Table 5.7.2-4 of TS 36.211. The eNodeB signals a logical root sequence number in SIB2. A terminal generates a set of 64 Zadoff Chu sequences based on: Parameter Ncs (also signaled in SIB2); and physical root sequence numbers corresponding respectively to the consecutive logical root sequence numbers beginning at the signaled logical root sequence number. Specifically, the eNodeB generates a first subset of the Zadoff Chu sequences based on cyclic shifts of a first root sequence (corresponding to the first physical root sequence number) until the first root sequence is exhausted then generates a second subset of the zadoff chu sequences. Chu sequences based on cyclic shifts of a second root sequence (corresponding to the second physical root sequence). Sequence number) until the second root sequence is exhausted, and so on, until 64 sequences are generated. According to TS 36.211, the root sequence corresponding to the physical root sequence number u is represented by:

where the length N _{ZC of} the root sequence x _{u is given} by Table 5.7.2.1 of TS 36.211.

Special preambles for signaling the LBL status of the terminal device

In a group of embodiments, a method 1400 for operating a terminal device as in 14 illustrated, performed. (The procedure 1400 may also include any subset of the features, elements, and embodiments described above 1 - 13 and in the following reference 15 - 17 be described.) The procedure 1400 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1400 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1410 For example, the processing agent may receive a logical root sequence number transmitted by a base station.

In 1415 For example, the processing agent may generate a preamble amount based on data containing the logical root sequence number. (The data may also include the Ncs parameter described below.) The preamble set generation action may include determining a first physical root sequence number according to a conventional allocation of the logical root sequence numbers to root physical sequence numbers. (In the context of LTE, the traditional mapping may be the mapping defined in Table 5.7.2.1 of 3GPP TS 36.211.) The preamble set may include:
a first subset of preambles for transmitting a physical random access channel (PRACH) through non-link budget limited terminal devices; and
a second subset of preambles for transmitting the PRACH through link budget limited terminal devices, wherein the first subset and the second subset are non-subsets.

In some embodiments, the preamble amount may be generated by applying the sequence generation procedure of 3GPP TS 36.211 Section 5.7.2, but this procedure is extended to generate over 64 preambles. For example, the first 64 preambles may form the first subset, and the remaining preambles may form the second subset.

In 1420 For example, in response to a determination that the terminal device has been classified as link budget constrained, the processing agent may transmit the PRACH to the base station using one of the preambles from the second subset.

In some embodiments, the processing agent may generate only the second subset of preambles. For example, if the terminal device is limited link budget, it may omit only the action of generating the first subset of preambles.

The base station may be configured such that, upon receipt of a PRACH, the base station may determine whether the preamble contained in the received PRACH belongs to the first subset or the second subset, for example by performing a correlation of the received PRACH to preambles in the first subset and preambles in the second subset. The subset membership of the correlation maximizing preamble indicates whether the terminal equipment transmitting the PRACH has, link budget is limited or not. Thus, the terminal device of methods 1400 signal its link budget limited status to the base station by transmitting the PRACH using a preamble selected from the second subset, as opposed to a preamble from the first subset. If it is determined that the terminal device is link budget limited, the base station may call one or more optimization mechanisms to improve the reliability of uplink and / or downlink communication with the terminal device, for example mechanisms such as: using more complex decoding algorithms to decode uplink Transmissions from the terminal device; Transmission of downlink transmissions to the enhanced performance terminal device, etc. (A non-LBL terminal device may transmit the PRACH using a preamble selected from the first subset.) Thus, the base station can recognize that the device is not link budget constrained .)

In some embodiments, the base station may also be configured to transmit the logical root sequence number and a parameter Ncs as part of a system information broadcast.

In some embodiments, the first subset of the preambles is the set of preambles defined by the existing LTI specifications.

In some embodiments, the method 1400 also, in response to a determination that the UE device has been classified as non-link budget constrained, transmitting the PRACH to the base station using one of the preambles from the first subset. (The LBL status of the terminal device may vary as the terminal device moves in a cell, as the battery power of the terminal device is depleted over time or recharged when charging, as other objects in the physical environment of the terminal device will overflow change the time, etc.)

In some embodiments, the terminal device may optionally select the preamble from the second subset of preambles.

In some embodiments, the preamble amount may be generated by: (1) generating a sequence of root physical sequence numbers based on the received logical root sequence number; and (2) applying cyclic shifts to root sequences that correspond to the physical root sequence numbers of the sequence. The sequence of physical red sequence numbers may be generated by assigning successive logical root sequence numbers, starting from the signaled logical root sequence number to the respective physical root sequence number using a conventional mapping.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 14 and in the following reference 15 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing agent can send out a logical root sequence number. Non-link budget limited terminal devices (and / or legacy devices) may use the logical root sequence number to generate a first subset of preambles for PRACH transmission, for example according to a conventionally defined algorithm. In contrast, terminal devices, which are link-budget constrained, generate a second subset of preambles for PRACH transmission, the second subset and the first subset being element alien.

After the logical root sequence number has been sent out, the processing agent can receive a PRACH, i. H. a PRACH transmitted from a terminal device. The processing agent may determine whether the PRACH has been transmitted by means of one of the preambles of the first subset or one of the preambles of the second subset.

In response to the determination that the PRACH has been transmitted with one of the preambles of the second subset, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the UE device.) On the other hand, if the processing agent determines that the PRACH is transmitting the first subset using one of the preambles the processing agent can not invoke the one or more communication optimization mechanisms.

In a group of embodiments, a method 1500 for operating a terminal device as in 15 illustrated, performed. (The procedure 1500 may also include any subset of the features, elements, and embodiments described above 1 - 14 and in the following reference 16 - 17 be described.) The procedure 1500 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1500 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1510 For example, the processing agent may receive system information sent by a base station. The system information may include one or more of the following elements:
a logical root sequence number;
a total of n _TOTAL of preambles contained in a preamble set, the preamble set including a first group of preambles and a second group of one or more preambles, the first group and the second group being elementary (such as the subsets of the preamble set); and
the number n ₁ of preambles in the first set.

The number n ₂ is positive, but smaller than the number n _TOTAL : 0 <n ₁ <n _TOTAL .

In 1515 For example, the processing agent may generate a preamble amount based on data containing the logical root sequence number. The action of generating the preamble set may include generating the first group of preambles having a size equal to the number n ₁ and generating the second group of one or more preambles having a size equal to a difference between the number n _TOTAL and the number n ₁ , The first group of preambles may be reserved for physical random access channel (PRACH) transmissions by non-link budget limited terminal devices and / or legacy devices. The second group of one or more preambles may be used for PRACH transmissions through link budget limited terminal devices.

In 1520 For example, in response to a determination that the terminal device has been classified as link budget constrained, the processing agent may transmit the PRACH to the base station using one or more of the preambles from the second subset.

When the base station receives a PRACH, the base station may determine whether the preamble contained in the received PRACH belongs to the first group or to the second group, for example by Correlation of the received PRACH with preambles in the first group and with preambles in the second group. The group membership (first group or second group) indicates whether or not the terminal device that has transmitted the PRACH is left-budget limited. In response to determining that a particular terminal device is link-budget limited (based on group membership), the base station may invoke one or more mechanisms to optimize the communication to maintain the reliability of the uplink and / or downlink communication with the terminal device to improve.

In some embodiments, the system information described above may include a RACH ConfigCommon information element that conforms to the LTE standard. The RACH ConfigCommon message may include the number n _TOTAL , the number n _1, and a message size. The base station may be configured to set the message size equal to a value large enough to reduce a number of the non-link budget limited terminal devices that use preambles from the second group (or so as to reduce the likelihood of that non-link budget limited terminal devices use preambles of the second group).

In some embodiments, the system information may include a RACH ConfigCommon message that conforms to the LTE standard. The RACH ConfigCommon message may include the number n _TOTAL , the number n _1, and a power offset. The base station may be configured to set the power offset to a value that is sufficiently large to increase a number of link-budget-limited terminal devices that use preambles from the second group (or so as to increase the likelihood that Link Budget-limited terminal devices use preambles of the second group and not preambles of the first group).

In some embodiments, the system information may also include a parameter Ncs, where the data from step 1515 contain the parameter Ncs.

In some embodiments, the system information may include a RACH ConfigCommon message that conforms to the LTE standard. The RACH ConfigCommon message may include the number n _TOTAL , the number n ₁ , an indication of a power offset, and an indication of a message size limit. In these embodiments, the method 1500 Also, in response to a determination that the UE device has been classified as non-link budget constrained, the processing agent may perform operations such as:
Determining whether (a) a path loss measured by the terminal device is below a path loss threshold determined in part from the power offset, and (b) a magnitude of an uplink message to be transmitted to the terminal device is above the message size limit;
in response to the determination that (a) and (b) are true, selecting a preamble from the first group; and
Transmitting a PRACH containing the selected preamble.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 15 and in the following reference 16 - 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing agent can send out system information. The system information may include one or more of the following elements:
a logical root sequence number;
a total of n _TOTAL . the preamble contained in a preamble set, the group of preambles including a first group of preambles and a second group of one or more preambles, the first group and the second group being element alien; and
the number n ₁ of preambles in the first group.

The terminal device may generate a preamble amount based on data including the logical root sequence number. The action of generating the preamble set may include generating the first group of preambles having a size equal to the number n ₁ and generating the second group of one or more preambles having a size equal to a difference between the number n _TOTAL and the number n ₁ , The first subset of preambles may be reserved for physical random access channel (PRACH) transmissions by non-link budget limited terminal devices (and / or legacy devices). In contrast, link budget limited terminal devices may be configured to perform PRACH transmissions using the second group of the one or more preambles.

Upon transmission of the system information, the processing agent may receive a PRACH, i. H. a PRACH transmitted from a terminal device. The processing agent may determine whether the PRACH contains a preamble from the first group or a preamble from the second group.

In response to determining that the PRACH contains a preamble from the second group, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access reply message and / or increase the performance of the downlink traffic transmissions to the terminal device.) On the other hand, if the processing agent determines that the PRACH contains a preamble from the first group, the processing agent can not call the one or more communication optimization mechanisms.

Improve the reception of direct access MSG2 for link budget limited devices

According to the existing LTE specifications, for each random access attempt, the terminal may optionally select a preamble from a group of preambles and transmit the selected preamble in msg1 (i.e., the PRACH message). The PRACH message can be transmitted to the network (NW) via the base station. Then the terminal waits for msg2, d. H. the so-called message with the random access response from the base station. msg2 can be received in the PDCCH and PDSCH of a downlink subframe at a particular time slot related to the transmission time of msg1. If msg2 is not received in the timeslot, the terminal waits a certain amount of time and then optionally selects another preamble from the group and makes another random access attempt by transmitting another PRACH message (including the newly selected preamble).

Link budget limited terminal devices have a higher probability of missing msg2 (e.g., not successfully decoding) compared to terminal devices that are non-link budget constrained. If the eNodeB knows that a terminal device is link-budget constrained, the eNodeB may increase the power of msg2 to allow a more successful decoding of msg2 by the terminal device. However, in some situations, the base station may not be able to determine from msg1 whether the terminal is link budget constrained.

• 1) Die LBL-Vorrichtung kann wahlfrei eine Präambel aus der Gruppe von Präambeln gemäß den 3GPP-Spezifikationen auswählen und die Präambel in msg1 der Direktzugriffsprozedur übertragen. Diese Übertragung kann als die erste Präambelübertragung bezeichnet werden. Wenn msg2 innerhalb dem erwarteten Zeitfenster nach einer Übertragung von msg1 empfangen wird, kann die LBL-Vorrichtung msg3 der Direktzugriffsprozedur übertragen.
• 2) Wenn die LBL-Vorrichtung den Empfang von msg2 im erwarteten Zeitfenster nach einer Übertragung von msg1 verfehlt, kann ein weiterer Direktzugriffsversuch initiiert werden. Im Besonderen kann die LBL-Vorrichtung: eine gewisse Zeitspanne warten (Back off); und eine andere Übertragung von msg1 durchführen (unter Verwendung der gleichen Präambel wie bei der ersten Präambel-Übertragung oder alternativ einer nächsten Präambel in einer Präambelsequenz). „Back off” steht für das Warten für eine bestimmte Zeitspanne vor der Übertragung. Der Wartebetrag kann zum Beispiel bezüglich des RA(Random Access, Direktzugriffs-)Fensters nach der Übertragung von MSG1 definiert sein und kann fest oder wahlfrei sein. Zum Beispiel kann der Wartebetrag ein fester Wert für alle Präambelübertragungen nach der ersten Übertragung und/oder für alle LBL-Vorrichtungen in der Zelle sein.

In some embodiments, a Link Budget Limited (LBL) device may operate as follows.

• 1) The LBL device may optionally select a preamble from the group of preambles according to the 3GPP specifications and transmit the preamble in msg1 of the random access procedure. This transmission may be referred to as the first preamble transmission. If msg2 is received within the expected window of time after transmission of msg1, the LBL device msg3 may transmit the random access procedure.
• 2) If the LBL device fails to receive msg2 in the expected time window after transmission of msg1, another random access attempt may be initiated. In particular, the LBL device may: wait a certain amount of time (back off); and perform another transmission of msg1 (using the same preamble as in the first preamble transmission, or alternatively a next preamble in a preamble sequence). "Back off" stands for waiting for a certain period of time before the transmission. The waiting amount may be defined, for example, with respect to the RA (Random Access) window after transmission of MSG1, and may be fixed or random. For example, the wait amount may be a fixed value for all preamble transmissions after the first transmission and / or for all LBL devices in the cell.

Thus, the LBL device can repeatedly transmit msg1 until msg2 has been successfully received. Repeated transmissions of msg1 can use the same preamble. Alternatively, for the repetitive transmissions of msg1, a preamble sequence whose pattern is known to the eNodeB may be used. Successful transmissions of msg1 can use consecutive preambles from the sequence. (While the first preamble of the sequence can be randomly selected, the eNodeB can know the relationship between the successive preambles of the sequence.)

• 1) eNodeB kann zählen wie oft: msg1 mit der gleichen Präambel empfangen wurde und die zugehörige msg2-Prozedur gescheitert ist. Anders ausgedrückt, für die bestimmte Präambel kann eNodeB zählen, wie oft eNodeB: msg1 empfängt und msg1 die betreffende Präambel enthält; und msg2 sendet, aber vom Endgerät keine msg3 empfangen wird.
• 2) Wenn die Anzahl der Male einen Grenzwert N (z. B. N = 2, 3, 4, 5 oder 6) erreicht (oder alternativ übersteigt), dann kann der eNodeB die Übertragungsleistung von msg2 in Reaktion auf eine oder mehrere folgende Instanzen von msg1, die die bestimmte Präambel enthalten, erhöhen. Zum Beispiel kann die Leistungsstärke für PDCCH und/oder PDSCH von msg2 erhöht werden.

In some embodiments, the eNodeB may perform the following operations.

• 1) eNodeB can count how many times: msg1 was received with the same preamble and the associated msg2 procedure failed. In other words, for the particular preamble, eNodeB can count how many times eNodeB: receives msg1 and msg1 contains the preamble in question; and msg2 sends, but no msg3 is received from the terminal.
• 2) If the number of times reaches (or alternatively exceeds) a threshold N (eg, N = 2, 3, 4, 5, or 6), then the eNodeB may transmit the transmit power of msg2 in response to one or more subsequent instances of msg1 that contain the particular preamble. For example, the power level for PDCCH and / or PDSCH may be increased by msg2.

The above "same preamble" is based on the case where the type LBL user equipment uses the same preamble (as in the first preamble transmission) for new transmissions of msg1. Alternatively, if the LBL-type terminal uses a preamble sequence for msg1 transmissions, the eNodeB may follow the same preamble sequence. Thus, eNodeB can count how many times eNodeB:
msg1 receives and msg1 contains a preamble consistent with a preamble sequence; and
msg2 sends, but no msg3 is received from the terminal.

In some embodiments, an LBL device may be configured to add a special MAC control element (CE) as an additional MAC PDU header in msg3 to indicate to the network that it is link-budget constrained. When the base station receives msg3, the base station may determine whether or not the terminal that transmitted the msg3 is link budget limited by determining whether the particular MAC control is present in the msg3.

• (a) einen entsprechenden Index-Offset von der ausgewählten Sequenz der Index-Offsets; und
• (b) den Index I_o der ersten Präambel.

In one set of embodiments, an LBL device may transmit a first PRACH message using a first preamble that is randomly selected from an available preamble set. If the random access attempt corresponding to a previous PRACH message (eg, the first PRACH message) is not successfully completed, the LBL device may transmit another PRACH message. Thus, the LBL device may transmit a sequence of PRACH messages until the random access completes successfully. The sequence of PRACH messages may have preambles corresponding to a sequence of preamble index offsets. (The LBL device may randomly select the sequence of preamble index offsets from a particular set of offset sequences.) The particular set of offset sequences is known to the eNodeB.) Each PRACH message after the first PRACH message may contain a corresponding preamble, which is determined by:

• (a) a corresponding index offset from the selected sequence of index offsets; and
• (b) the index I _{o of} the first preamble.

For example, after the first PRACH message, the kth PRACH message may include the preamble determined by the index I _o + offset (k), where offset (k) is the kth offset in the selected sequence of index offsets.

In some embodiments, the direct selection from the particular set may be based on the cell identifier of the eNodeB such that the LBL devices in different cells select different index offset sequences from the particular set.

The LBL devices may use index offset sequences selected from the particular set of offset sequences. In contrast, when a non-LBL device (and / or an older one Device) experiences an error for any given random access attempt (e.g., by missing msg2), it may optionally select another preamble from the available preamble set, and transmit another PRACH message based on the randomly selected preamble. Thus, successful PRACH transmissions from a non-LBL device are generally not consistent with any of the sequences of the particular set. (The probability that a non-LBL device will randomly select a preamble sequence that is consistent with any of the sequences of the particular set is very small.)

The eNodeB can count the number of failed RACH attempts whose preambles are consistent with a particular index offset sequence. Increasing the counter increases the likelihood that the RACH attempts will belong to an LBL device. When the eNodeB receives a current PRACH message consistent with a particular index offset sequence, the eNodeB may determine whether the counter has reached (or is greater than) a threshold N, as the case may be. If so, the eNodeB can transmit the Direct Access Response message (ie, random access msg2) with increased performance (or performance) power used for the first N transmissions of msg2. In some embodiments, the first N transmissions at a certain power level P _o can be transmitted and any transfer of msg2 after the first N transfers may at a power level (or power levels) can be greater than P _o transmitted. In one embodiment, successive transmissions of msg2 are transmitted after the Nth transmission with increasingly higher power.

In a group of embodiments, a method 1600 for operating a terminal device as in 16A illustrated, performed. (The procedure 1600 may also include any subset of the features, elements, and embodiments described above 1 - 15 and in the following reference 17 be described.) The procedure 1600 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent. The processing agent may be implemented by one or more processors executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1600 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1610 For example, the processing agent may perform one or more iterations for a set of operations until a termination condition is met. The group of operations can do the operations 1615 to 1620 which are described below.

In 1615 For example, the processing agent may generate a preamble for a PRACH message.

In 1620 For example, the processing agent may transmit the PRACH message to a base station, the PRACH message containing the preamble. The termination condition may be the condition that the terminal device successfully receives a message with a random access response (RAR) that is a response to the PRACH message.

The one or more preambles in the one or more respective transmissions of the PRACH message may be generated based on:
a sequence of preamble index offsets, the sequence being configured (or reserved) for use by link budget limited terminal devices; and
a first index of the first preamble generated for a first one of the one or more transmissions of the PRACH message.

In some embodiments, the method 1600 also include selecting the sequence of preamble index offsets from a particular set of preamble index offset sequences, wherein the particular set is configured (or reserved) for use by link budget limited terminal devices.

In some embodiments, the select action from the particular group is a direct selection based on a cell identifier of the base station.

In some embodiments, the terminal device is link budget limited. A terminal device that is link budget limited may require more than one iteration by the amount of operations to obtain the termination condition.

In some embodiments, for each iteration after a first of the iterations, the set of operations may also include waiting for a certain amount of time before a next one of the PRACH message transmissions.

In a group of embodiments, a method of operating a base station may be performed as described below. (The method may also include any subset of the features, elements, and embodiments described above 1 - 16 and in the following reference 16B and 17 The method may be performed by a base station to facilitate a random access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be implemented by one or more processors executing / executing program instructions, by one or more programmable hardware elements such as FPGAs, by one or more dedicated hardware devices such as ASICs, or by any combination of the previous. The processing agent may be configured to transmit radio signals via a transmitter of the base station and to receive radio signals via a receiver of the base station, as described above in various places.

While the method will be described below in a series of steps, it should be understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

The processing agent may receive a current PRACH message, for example from a terminal device in the cell. A link-budget-limited type terminal device may be configured to repeatedly transmit a PRACH message using preambles corresponding to a known pattern until the random access procedure is successfully completed. In contrast, the non-LBL type terminal device (and / or older devices) may be configured to selectively select a preamble for each transmission of a PRACH message.

The processing agent may increase an error counter in response to a determination that the current PRACH message results in a random access error and that the preamble in the current PRACH message and one or more preceding PRACH message preambles are consistent with a preamble pattern common to terminal devices of the PRACH message LBL type is reserved.

In response to determining that the error counter exceeds (or alternatively reaches) a threshold, the processing agent may invoke one or more communication optimization mechanisms for transmission to and / or reception from the terminal device that transmitted the PRACH. (For example, the processing agent may increase the performance of the random access response message and / or increase the performance of the downlink traffic transmissions to the terminal device.) On the other hand, if the processing agent determines that the error counter is less than or equal to (or alternatively less than) the threshold is, the processing agent can not call the one or more mechanisms to optimize communication.

In a group of embodiments, a method 1650 for operating a terminal (UE) device, as in 16B illustrated, performed. (The procedure 1650 may also include any subset of the features, elements, and embodiments described above 1 to 16 and in the following reference 17 be described.) The procedure 1650 can be performed by a link budget limited terminal device to simplify a random access procedure. The method may be implemented by a processing agent of the terminal device. The processing agent may be implemented by one or more processors executing / executing program instructions through a programmable or multiple programmable hardware device. Elements, by one or more dedicated hardware elements, such as ASICS, or by any combination of the foregoing.

While the procedure 1650 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

In 1660 For example, in response to a determination that a message with a random access response (RAR) was not received after transmission of a previous PRACH message, the processing agent may perform a group of operations, including the operations described below 1665 and 1670 , (The processing agent may monitor an expected RAR message time window, ie, an expected time window after the previous PRACH transmission.)

In 1665 For example, the processing agent may generate a preamble based at least in part on a current offset in a sequence of preamble index offsets as described in various places above. The sequence of preamble index offsets may be configured (or dedicated) for use by link budget limited terminal devices.

In 1670 For example, the processing agent may transmit a current PRACH message including the generated preamble.

In some embodiments, the preamble described above may be generated based on a current offset and a first index, as described in various places above. The first index may be an index of a first preamble used in a first transmission of the PRACH message.

In some embodiments, the method 1650 also include selecting the sequence of preamble index offsets from a particular set of preamble index offset sequences, wherein the particular set is configured (or reserved) for use by link budget limited terminal devices.

In some embodiments, the select action from the particular group is a direct selection based on a cell identifier of the base station.

In some embodiments, the sequence of preamble index offsets may be an alternating sequence, i. H. alternating between two different offset values.

In some embodiments, the sequence of preamble index offsets may be a cyclic sequence, ie, a cyclic sweep through n _CYC offset values, where n _{CYC is} greater than or equal to 2.

In some embodiments, the sequence of preamble index offsets may be a sequence of values other than o, or a sequence of positive values, or a sequence containing two or more nonzero values, as well as one or more nulls.

In some embodiments, the sequence of preamble index offsets may be a sequence of zero values.

In some embodiments, the terminal device is link budget limited.

In some embodiments, the set of operations also includes waiting a certain amount of time before transmitting the current PRACH message.

In a group of embodiments, a method 1700 for operating a base station, as in 17 represented, performed. (The procedure 1700 may also include any subset of the features, elements, and embodiments described above 1 to 16B described.) The procedure 1700 can be performed to simplify a direct access procedure for a link budget limited terminal device. The method may be implemented by a processing agent of the base station. The processing agent may be replaced by one or more Processors executing / executing program instructions, by one or more programmable hardware elements, by one or more dedicated hardware elements such as ASICS, or by any combination of the foregoing.

While the procedure 1700 will be described below in a series of steps, it is understood that in various embodiments: one or more of the steps may be omitted; two or more of the steps may be performed at least partially in parallel; one or more steps can be added, if desired; and the steps may be performed in sequences other than those described.

• (a) weisen entsprechende Präambeln auf, die einer Sequenz von Präambelindexoffsets entsprechen, wobei die Sequenz der Präambelindexoffsets zur Verwendung durch Link-Budget-beschränkte Endgerätevorrichtungen konfiguriert (oder dediziert ausgestaltet) ist und
• (b) zu einem Direktzugriffsfehler geführt haben.

In 1710 For example, the processing agent may receive a current PRACH message after receiving several previous PRACH messages. The previous PRACH news:

• (a) have corresponding preambles corresponding to a sequence of preamble index offsets, the sequence of preamble index offsets being configured (or dedicated) for use by link budget limited terminal devices, and
• (b) resulted in a random access error.

A memory of the base stations may store a counter of the previous PRACH messages.

In 1715 For example, in response to receiving the current PRACH message, the processing agent may transmit a message with a random access response (RAR). A transmission power of the RAR message may be less than or equal to a first power level when a current value of the counter is less than or equal to a threshold value N, where N is an integer value greater than one. Alternatively, the transmission power of the RAR message may be above a power level if the current value of the counter is greater than the threshold N.

• (1) eine Präambel der aktuellen PRACH-Nachricht mit einer erwarteten Präambel basierend auf einem Präambelindex einer ersten der vorhergehenden PRACH-Nachrichten und einem nächsten Präambelindexoffset der Sequenz der Präambelindexoffsets übereinstimmt; und
• (2) eine dritte Direktzugriffsnachricht in Reaktion auf eine RAR-Nachricht nicht von der Basisstation empfangen wird.

In some embodiments, the method 1700 also increase the counter in response to the determination that:

• (1) a preamble of the current PRACH message matches an expected preamble based on a preamble index of a first of the previous PRACH messages and a next preamble index offset of the sequence of preamble index offsets; and
• (2) a third random access message is not received from the base station in response to a RAR message.

In some embodiments, the particular sequence of preamble index offsets may be a sequence of zero values.

In some embodiments, a first of the link budget limited terminal device is configured to randomly select the sequence of preamble index offsets from a particular group of preamble index offsets and to generate preambles for consecutive random access attempts using the selected sequence of preamble index offsets.

• 1. Verfahren zum Betreiben einer Endgerätevorrichtung, wobei das Verfahren beinhaltet: Empfangen eines ersten Index, der von einer Basisstation ausgesendet wurde, wobei der erste Index eine erste Konfiguration zur Übertragung eines physischen Direktzugriffkanals (PRACH) durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen in einer Zelle der Basisstation identifiziert; Hinzufügen eines Offsets zum ersten Index, um einen zweiten Index zu erhalten, wobei der zweite Index eine zweite Konfiguration zur Übertragung des PRACH durch Link-Budget-beschränkte Vorrichtungen in der Zelle identifiziert; In Reaktion auf die Bestimmung, dass die Endgerätevorrichtung als Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation, wobei der PRACH gemäß der zweiten Konfiguration übertragen wird.
• 2. Verfahren nach Absatz 1, wobei die Basisstation dazu konfiguriert, den ersten Index als Teil eines Typ 2-Systeminformationsblocks zu übertragen, wie im LTE-Standard definiert.
• 3. Verfahren nach Absatz 1, wobei der erste Index die erste Konfiguration aus einer Liste von PRACH-Konfigurationen identifiziert, die durch einen bestehenden Funkkommunikationsstandard definiert sind, wobei der zweite Index die zweite Konfiguration aus der Liste der PRACH-Konfigurationen identifiziert.
• 4. Verfahren nach Absatz 1, das weiterhin aufweist: Empfangen eines dritten Index, der von einer zweiten Basisstation ausgesendet wurde, wobei der dritte Index eine dritte Konfiguration zur Übertragung des PRACH durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen in einer zweiten Zelle, die der zweiten Basisstation entspricht, identifiziert; Hinzufügen des gleichen Offsets zum dritten Index, um einen vierten Index zu erhalten, wobei der vierte Index eine vierte Konfiguration zur Übertragung des PRACH durch Link-Budget-beschränkte Endgerätevorrichtungen in der zweiten Zelle identifiziert; Übertragen des PRACH an die zweite Basisstation, wobei der PRACH gemäß der vierten Konfiguration übertragen wird.
• 5. Verfahren nach Absatz 1, wobei der Offset von mehreren Basenstationen einschließlich der besagten Basisstation verwendet wird.
• 6. Verfahren zum Betreiben einer Endgerätevorrichtung, wobei das Verfahren beinhaltet: Empfangen eines ersten Index, der von einer Basisstation ausgesendet wurde, wobei der erste Index eine erste Konfiguration zur Übertragung eines physischen Direktzugriffkanals (PRACH) identifiziert, wobei die erste Konfiguration eine herkömmlich definierte Menge von zulässigen Teilrahmen zur Übertragung des PRACH durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen in einer Zelle, die der Basisstation entspricht, aufweist; In Reaktion auf eine Bestimmung, dass die Endgerätevorrichtung als Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation, wobei der PRACH in einem Teilrahmen aus einer alternativen Menge von zulässigen Teilrahmen übertragen wird, wobei die alternative Menge zu der herkömmlich definierten Menge von zulässigen Teilrahmen elementfremd ist.
• 7. Verfahren nach Absatz 6, wobei die Basisstation dazu konfiguriert ist, Systeminformationen auszusenden, die die alternative Menge von zulässigen Teilrahmen angibt.
• 8. Verfahren nach Absatz 6, wobei die Basisstation dazu konfiguriert ist, den ersten Index als Teil eines Typ 2-Systeminformationsblocks zu übertragen, wie im LTE-Standard definiert.
• 9. Verfahren nach Absatz 6, das weiterhin aufweist: in Reaktion auf eine Bestimmung, dass die Endgerätevorrichtung als nicht Nicht-Link-Budget-beschränkt klassifiziert wurde, Übertragen eines anderen PRACH an die Basisstation, wobei der andere PRACH in einem Teilrahmen aus der herkömmlich definierten Menge der zulässigen Teilrahmen übertragen wird.
• 10. Verfahren nach Absatz 6, wobei die erste Konfiguration auch ein Format zur Übertragung des PRACH angibt, wobei der PRACH gemäß dem angegebenen Format übertragen wird.
• 11. Verfahren zum Betreiben einer Endgerätevorrichtung, wobei das Verfahren beinhaltet: Empfangen eines ersten Index, der von einer Basisstation ausgesendet wurde, wobei der erste Index eine erste Konfiguration zur Übertragung eines physischen Direktzugriffkanals (PRACH) identifiziert, wobei die erste Konfiguration angibt, dass die Übertragung des PRACH durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen auf ungeradzahlige Rahmen und auf eine herkömmlich definierte Menge von zulässigen Teilrahmen beschränkt ist; In Reaktion auf eine Bestimmung, dass die Endgerätevorrichtung als Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation, wobei der PRACH in einem ungeradzahligen Rahmen und in einem der Teilrahmen aus der herkömmlich definierten Menge übertragen wird.
• 12. Verfahren nach Absatz 11, wobei die erste Konfiguration auch ein Format zur PRACH-Übertragung angibt, wobei der PRACH gemäß diesem Format an die Basisstation übertragen wird.
• 13. Verfahren nach Absatz 11, das weiterhin aufweist: in Reaktion auf eine Bestimmung, dass die Endgerätevorrichtung als nicht Nicht-Link-Budget-beschränkt klassifiziert wurde, Übertragen eines anderen PRACH an die Basisstation, wobei der andere PRACH in einem geradzahligen Rahmen und in einem der Teilrahmen aus der herkömmlich definierten Menge übertragen wird.
• 14. Verfahren nach Absatz 11, wobei die Basisstation dazu konfiguriert, den ersten Index als Teil eines Typ 2-Systeminformationsblocks zu übertragen, wie im LTE-Standard definiert.
• 15. Verfahren zum Betreiben einer Endgerätevorrichtung, wobei das Verfahren beinhaltet: Empfangen einer logischen Root-Sequenznummer, die von einer Basisstation ausgesendet wurde; Generieren einer Präambelmenge basierend auf Daten, die die logische Root-Sequenznummer enthalten, wobei das Generieren die Bestimmung einer ersten physischen Root-Sequenznummer gemäß einer herkömmlichen Zuordnung der logischen Root-Sequenznummern an physische Root-Sequenznummern aufweist, wobei die Präambelmenge aufweist: eine erste Teilmenge von Präambeln zur Übertragung eines physischen Direktzugriffkanals (PRACH) durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen; und eine zweite Teilmenge von Präambeln zur Übertragung des PRACH durch Link-Budget-beschränkte Endgerätevorrichtungen, wobei die erste Teilmenge und die zweite Teilmenge elementfremde Teilmengen sind; In Reaktion auf die Bestimmung, dass die Endgerätevorrichtung als Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation unter Verwendung von einer der Präambeln aus der zweiten Teilmenge.
• 16. Verfahren nach Anspruch 15, wobei die Basisstation auch dazu konfiguriert ist, die logische Root-Sequenznummer und einen Parameter Ncs als Teil einer Systeminformationsaussendung auszusenden, wobei die Daten auch den Parameter Ncs enthalten.
• 17. Verfahren nach Absatz 15, wobei die erste Teilmenge der Präambeln einer Präambelmenge gemäß der Definition des LTE-Standards entspricht.
• 18. Verfahren nach Absatz 15, das weiterhin aufweist: in Reaktion auf die Bestimmung, dass die Endgerätevorrichtung als Nicht-Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation unter Verwendung einer der Präambeln aus der ersten Teilmenge.
• 19. Verfahren nach Absatz 15, wobei das Endgerät wahlfrei die Präambel aus der zweiten Teilmenge von Präambeln auswählt.
• 20. Verfahren nach Absatz 15, wobei die Präambelmenge generiert wird durch: Generieren einer Sequenz von physischen Root-Sequenznummern basierend auf der empfangenen logischen Root-Sequenznummer; und Anwenden von zyklischen Verschiebungen auf Root-Sequenzen, die den physischen Root-Sequenznummern der Sequenz entsprechen.
• 21. Verfahren zum Betreiben einer Endgerätevorrichtung, wobei das Verfahren beinhaltet: Empfangen von Systeminformationen, die von einer Basisstation ausgesendet wurden, wobei die Systeminformationen enthalten: eine logische Root-Sequenznummer; eine Gesamtzahl von in einer Präambelmenge enthaltenen Präambeln, wobei die Präambelmenge eine erste Gruppe von Präambeln und eine zweite Gruppe von einer oder mehreren Präambeln enthält, wobei die erste Gruppe und die zweite Gruppe elementfremd sind; eine erste Anzahl von Präambeln in der ersten Gruppe, wobei die erste Anzahl positiv aber kleiner als die Gesamtzahl ist; Generieren der Präambelmenge basierend auf Daten, die die logische Root-Sequenznummer enthalten, wobei das Generieren beinhaltet das Generieren der ersten Gruppe von Präambeln mit einer Größe gleich der ersten Anzahl und das Generieren der zweiten Gruppe von einer oder mehreren Präambeln mit einer Größe gleich einer Differenz zwischen der Gesamtzahl und der ersten Anzahl, wobei die erste Gruppe von Präambeln für physische Direktzugriffskanal-(PRACH-)Übertragungen durch Nicht-Link-Budget-beschränkte Endgerätevorrichtungen reserviert ist, wobei die zweite Gruppe der einen oder mehreren Präambeln für PRACH-Übertragungen durch Link-Budget-beschränkte Endgerätevorrichtungen verwendet wird; In Reaktion auf die Bestimmung, dass die Endgerätevorrichtung als Link-Budget-beschränkt klassifiziert wurde, Übertragen des PRACH an die Basisstation unter Verwendung einer von der einen oder den mehreren Präambeln aus der zweiten Gruppe.
• 22. Verfahren nach Absatz 21, wobei die Systeminformationen eine RACH-ConfigCommon-Nachricht aufweisen, die dem LTE-Standard entspricht, wobei die RACH-ConfigCommon-Nachricht die Gesamtzahl, die erste Zahl und eine Nachrichtengröße enthält, wobei die Basisstation dazu ausgestaltet ist, die Nachrichtengröße auf einen Wert festzulegen, der ausreichend groß ist, um eine Anzahl von Nicht-Link-Budget-beschränkten Endgerätevorrichtungen zu verringern, die Präambeln aus der zweiten Gruppe verwenden.
• 23. Verfahren nach Absatz 21, wobei die Systeminformationen eine RACH-ConfigCommon-Nachricht aufweisen, die dem LTE-Standard entspricht, wobei die RACH-ConfigCommon-Nachricht die Gesamtzahl, die erste Zahl und eine Nachrichtengröße enthält, wobei die Basisstation dazu ausgestaltet ist, den Leistungsoffset auf einen Wert festzulegen, der ausreichend groß ist, um eine Anzahl von Link-Budget-beschränkten Endgerätevorrichtungen zu erhöhen, die Präambeln aus der zweiten Gruppe verwenden.
• 24. Verfahren nach Absatz 21, wobei die Systeminformationen auch einen Parameter Ncs enthalten, wobei die Daten den Parameter Ncs enthalten.
• 25. Verfahren nach Absatz 21, wobei die Systeminformationen eine dem LTE-Standard entsprechende RACH-ConfigCommon-Nachricht enthalten, wobei die RACH-ConfigCommon-Nachricht die Gesamtzahl, die erste Zahl, eine Angabe des Leistungsoffsets und eine Angabe des Grenzwerts der Nachrichtengröße enthält, wobei das Verfahren weiterhin aufweist in Reaktion auf eine Bestimmung, dass die Endgerätevorrichtung als nicht Link-Budget-beschränkt klassifiziert wurde, Operationen durchführt, die umfassen: Bestimmen, ob (a) ein von der Endgerätevorrichtung gemessener Pfadverlust unter einem Pfadverlustgrenzwert liegt, der teils aus dem Leistungsoffset bestimmt wurde und (b) eine Größe einer an die Endgerätevorrichtung zu übertragenden Uplink-Nachricht über dem Nachrichtengrößengrenzwert liegt; in Reaktion auf die Bestimmung, dass (a) und (b) wahr sind, Auswählen einer Präambel aus der ersten Gruppe; und Übertragen eines PRACH, der die ausgewählte Präambel enthält.
• 26. Verfahren zum Betreiben einer Endgerätevorrichtung zum Vereinfachen des Direktzugriffs auf ein Funkkommunikationsnetzwerk, wobei das Verfahren beinhaltet: In Reaktion auf eine Bestimmung, dass eine Nachricht mit einer Direktzugriffsantwort (RAR) nicht empfangen wurde, nachdem eine vorhergehende PRACH-Nachricht übertragen wurde, Durchführen einer Menge von Operationen, die umfassen: Generieren einer Präambel basierend auf wenigstens teilweise einem aktuellen Offset in einer Sequenz von Präambelindexoffsets, wobei die Sequenz zur Verwendung durch Link-Budget-beschränkte Endgerätevorrichtungen ausgestaltet ist; und Übertragen einer aktuellen PRACH-Nachricht, die die generierte Präambel enthält.
• 27. Verfahren nach Absatz 26, wobei die Präambel basierend auf dem aktuellen Offset und einem ersten Index generiert wird, wobei der erste Index ein Index einer bei einer ersten Übertragung der PRACH-Nachricht verwendeten ersten Präambel ist.
• 28. Verfahren nach Absatz 26, das weiterhin aufweist: Auswählen der Sequenz der Präambelindexoffsets aus einer bestimmten Menge von Präambelindexoffset-Sequenzen, wobei die bestimmte Menge zur Verwendung durch Link-Budget-beschränkte Endgerätevorrichtungen konfiguriert ist.
• 29. Verfahren von Absatz 28, wobei die Auswahl aus der bestimmten Menge eine Direktauswahl basierend auf einer Zellenkennung der Basisstation ist.
• 30. Verfahren nach Absatz 26, wobei die Sequenz der Präambelindexoffsets eine Sequenz von Nullwerten ist.
• 31. Verfahren nach Absatz 26, wobei die Menge der Operationen auch das Warten eine bestimmte Zeitspanne vor der Übertragung der aktuellen PRACH-Nachricht enthält.
• 32. Verfahren zum Betreiben einer Basisstation, wobei das Verfahren aufweist: Empfangen einer aktuellen PRACH-Nachricht, nachdem mehrere vorhergehende PRACH-Nachrichten empfangen wurden, wobei die vorhergehenden PRACH-Nachrichten (a) jeweilige Präambeln haben, die mit einer Sequenz von Präambelindexoffsets übereinstimmen, die zur Verwendung durch Link-Budget-beschränkte Endgerätevorrichtungen konfiguriert sind, und (b) zu einem Direktzugriffsfehler geführt haben, wobei der Speicher der Basisstationen einen Zähler der vorhergehenden PRACH-Nachrichten speichert; In Reaktion auf den Empfang der aktuellen PRACH-Nachricht Übertragen einer Nachricht mit einer Direktzugriffsantwort (RAR), wobei eine Übertragungsleistung der RAR-Nachricht kleiner oder gleich einem ersten Leistungslevel ist, wenn ein aktueller Wert des Zählers kleiner oder gleich einem Grenzwert N ist, wobei die Übertragungsleistung der RAR-Nachricht größer als der erste Leistungslevel ist, wenn der aktuelle Wert des Zählers größer als der Grenzwert N ist.
• 33. Verfahren nach Absatz 32, das weiterhin das Erhöhen des Zählers in Reaktion auf eine Bestimmung aufweist, dass: eine Präambel der aktuellen Nachricht mit einer erwarteten Präambel basierend auf einem Präambelindex einer ersten der vorhergehenden PRACH-Nachrichten und einem nächsten Präambelindexoffset der Sequenz der Präambelindexoffsets übereinstimmt; und keine dritte Direktzugriffsnachricht in Reaktion auf die RAR-Nachricht von der Basisstation empfangen wird.
• 34. Verfahren nach Absatz 32, wobei die bestimmte Sequenz von Präambelindexoffsets eine Sequenz von Nullwerten ist.
• 35. Verfahren nach Absatz 32, wobei eine erste von Link-Budget-beschränkten Endgerätevorrichtungen dazu ausgestaltet ist, die Sequenz von Präambelindexoffsets aus einer bestimmten Gruppe von Präambelindexoffsets wahlfrei auszuwählen und Präambeln für aufeinanderfolgende Direktzugriffsversuche unter Verwendung der ausgewählten Sequenz von Präambelindexoffsets zu generieren.

Other embodiments are disclosed in the following numbered sections.

• A method of operating a terminal device, the method comprising: receiving a first index transmitted by a base station, the first index having a first configuration for transmitting a physical random access channel (PRACH) through non-link budget limited terminal devices in FIG a cell of the base station identified; Adding an offset to the first index to obtain a second index, the second index identifying a second configuration for transmitting the PRACH through link budget limited devices in the cell; In response to determining that the terminal device has been classified as link-budget constrained, transmitting the PRACH to the base station, wherein the PRACH is transmitted according to the second configuration.
• 2. The method of paragraph 1, wherein the base station is configured to transmit the first index as part of a type 2 system information block as defined in the LTE standard.
• 3. The method of paragraph 1, wherein the first index identifies the first configuration from a list of PRACH configurations defined by an existing wireless communication standard, the second index identifying the second configuration from the list of PRACH configurations.
• 4. The method of paragraph 1, further comprising: Receiving a third index sent by a second base station, the third index identifying a third configuration for transmitting the PRACH through non-link budget limited terminal devices in a second cell corresponding to the second base station; Adding the same offset to the third index to obtain a fourth index, the fourth index identifying a fourth configuration for transmitting the PRACH through link budget limited terminal devices in the second cell; Transmitting the PRACH to the second base station, wherein the PRACH is transmitted according to the fourth configuration.
• 5. The method of paragraph 1, wherein the offset is used by a plurality of base stations including said base station.
• 6. A method of operating a terminal device, the method comprising: receiving a first index transmitted by a base station, wherein the first index identifies a first physical random access channel (PRACH) transmission configuration, wherein the first configuration is a conventionally defined amount allowable subframes for transmitting the PRACH through non-link budget limited terminal devices in a cell corresponding to the base station; In response to a determination that the terminal device has been classified as link budget constrained, transmitting the PRACH to the base station, wherein the PRACH is transmitted in a subframe from an alternative set of allowable subframes, the alternative amount to the conventionally defined amount is elementary of permissible subframe.
• 7. The method of paragraph 6, wherein the base station is configured to send system information indicating the alternative set of allowable subframes.
• 8. The method of paragraph 6, wherein the base station is configured to transmit the first index as part of a type 2 system information block as defined in the LTE standard.
• 9. The method of paragraph 6, further comprising: in response to a determination that the UE device has been classified as non-link budget constrained, transmitting another PRACH to the base station, wherein the other PRACH is conventional in a subframe defined amount of permissible subframes is transmitted.
• 10. The method of paragraph 6, wherein the first configuration also specifies a format for transmitting the PRACH, the PRACH being transmitted according to the specified format.
• 11. A method of operating a terminal device, the method comprising: receiving a first index transmitted by a base station, wherein the first index identifies a first physical random access channel (PRACH) transmission configuration, wherein the first configuration indicates that the Transmission of the PRACH is restricted to odd-numbered frames by non-link-budget-limited terminal devices and to a conventionally-defined set of allowable sub-frames; In response to a determination that the UE device has been classified as link budget constrained, transmitting the PRACH to the base station, wherein the PRACH is transmitted in an odd frame and in one of the subframes from the conventionally defined set.
• 12. The method of paragraph 11, wherein the first configuration also specifies a format for PRACH transmission, wherein the PRACH is transmitted to the base station according to this format.
• 13. The method of paragraph 11, further comprising: in response to a determination that the UE device has been classified as non-link budget constrained, transmitting another PRACH to the base station, wherein the other PRACH is in an even frame and in one of the subframes is transferred from the conventionally defined amount.
• 14. The method of paragraph 11, wherein the base station is configured to transmit the first index as part of a type 2 system information block as defined in the LTE standard.
• 15. A method of operating a terminal device, the method comprising: receiving a logical root sequence number transmitted by a base station; Generating a preamble set based on data containing the logical root sequence number, wherein the generating comprises determining a first physical root sequence number according to a conventional allocation of the logical root sequence numbers to the physical root sequence numbers, the preamble set comprising: a first subset preambles for transmitting a physical random access channel (PRACH) through non-link budget limited terminal devices; and a second subset of preambles for transmitting the PRACH through link-budget-limited terminal devices, wherein the first subset and the second subset are non-elementary subsets; In response to the determination that the terminal device has been classified as link-budget constrained, transmitting the PRACH to the base station using one of the preambles from the second subset.
• The method of claim 15, wherein the base station is also configured to transmit the root logical sequence number and a parameter Ncs as part of a system information broadcast, the data also including the parameter Ncs.
• 17. The method of paragraph 15, wherein the first subset of preambles corresponds to a preamble amount as defined by the LTE standard.
• 18. The method of clause 15, further comprising: in response to determining that the UE device has been classified as non-link budget constrained, transmitting the PRACH to the base station using one of the preambles from the first subset.
• 19. The method of paragraph 15, wherein the terminal optionally selects the preamble from the second subset of preambles.
• 20. The method of clause 15, wherein the preamble set is generated by: generating a sequence of physical root sequence numbers based on the received logical root sequence number; and applying cyclic shifts to root sequences that correspond to the physical root sequence numbers of the sequence.
• 21. A method of operating a terminal device, the method comprising: receiving system information transmitted by a base station, the system information including: a logical root sequence number; a total number of preambles contained in a preamble set, the preamble set including a first group of preambles and a second group of one or more preambles, the first group and the second group being element alien; a first number of preambles in the first group, the first number being positive but less than the total number; Generating the preamble set based on data containing the logical root sequence number, wherein generating includes generating the first group of preambles having a size equal to the first number and generating the second group of one or more preambles having a size equal to a difference between the total number and the first number, wherein the first group of preambles for physical random access channel (PRACH) transmissions is reserved by non-link budget limited terminal devices, the second group of the one or more preambles for PRACH transmissions by link Budget-limited terminal devices is used; In response to the determination that the terminal device has been classified as link budget constrained, transmitting the PRACH to the base station using one of the one or more preambles from the second group.
• 22. The method of paragraph 21, wherein the system information comprises a RACH ConfigCommon message conforming to the LTE standard, the RACH ConfigCommon message including the total number, the first number, and a message size, the base station configured to set the message size to a value large enough to reduce a number of non-link budget limited terminal devices using preambles from the second group.
• 23. The method of paragraph 21, wherein the system information comprises a RACH ConfigCommon message conforming to the LTE standard, the RACH ConfigCommon message including the total number, the first number, and a message size, the base station configured to set the power offset to a value large enough to increase a number of link-budget-limited terminal devices using preambles from the second group.
• 24. The method of paragraph 21, wherein the system information also includes a parameter Ncs, the data including the parameter Ncs.
• 25. The method of paragraph 21, wherein the system information includes an LTE standard RACH ConfigCommon message, the RACH ConfigCommon message including the total number, the first number, an indication of the power offset, and an indication of the message size limit, the method further comprising performing, in response to a determination that the terminal device was classified as non-link budget constrained, performing operations comprising: determining whether (a) a path loss measured by the terminal device is below a path loss threshold that is partly and (b) a size of an uplink message to be transmitted to the terminal device is above the message size limit; in response to the determination that (a) and (b) are true, selecting a preamble from the first group; and transmitting a PRACH containing the selected preamble.
• 26. A method of operating a terminal device to facilitate random access to a radio communication network, the method comprising: in response to a determination that a message with a random access response (RAR) has not been received after a previous PRACH message has been transmitted, performing a Set of operations that include: Generating a preamble based at least in part on a current offset in a sequence of preamble index offsets, the sequence configured for use by link budget limited terminal devices; and transmitting a current PRACH message containing the generated preamble.
• 27. The method of paragraph 26, wherein the preamble is generated based on the current offset and a first index, the first index being an index of a first preamble used in a first transmission of the PRACH message.
• 28. The method of clause 26, further comprising: selecting the sequence of preamble index offsets from a particular set of preamble index offset sequences, wherein the determined amount is configured for use by link budget limited terminal devices.
• 29. The method of paragraph 28, wherein the selected one of the determined amount is a direct selection based on a cell identifier of the base station.
• 30. The method of paragraph 26, wherein the sequence of preamble index offsets is a sequence of zero values.
• 31. The method of paragraph 26, wherein the set of operations also includes waiting a certain amount of time before transmitting the current PRACH message.
• 32. A method of operating a base station, the method comprising: receiving a current PRACH message after a plurality of previous PRACH messages have been received, the previous PRACH messages (a) having respective preambles that correspond to a sequence of preamble index offsets, which are configured for use by link-budget-limited terminal devices, and (b) have resulted in a random access error, the memory of the base stations storing a counter of the preceding PRACH messages; In response to receiving the current PRACH message, transmitting a message with a random access response (RAR), wherein a transmission power of the RAR message is less than or equal to a first power level when a current value of the counter is less than or equal to a threshold N, wherein the transmission power of the RAR message is greater than the first power level when the current value of the counter is greater than the threshold value N.
• 33. The method of paragraph 32, further comprising incrementing the counter in response to a determination that: a preamble of the current message having an expected preamble based on a preamble index of a first of the preceding PRACH messages and a next preamble index offset of the sequence of preamble index offsets matches; and no third random access message is received from the base station in response to the RAR message.
• 34. The method of paragraph 32, wherein the particular sequence of preamble index offsets is a sequence of null values.
• 35. The method of paragraph 32, wherein a first of link budget limited terminal devices is configured to randomly select the sequence of preamble index offsets from a particular group of preamble index offsets and to generate preambles for successive random access attempts using the selected sequence of preamble index offsets.

Embodiments of the present disclosure may be embodied in any of various forms. For example, some embodiments may be embodied as a method implemented in a computer, as a computer-readable storage medium, or as a computer system. Other embodiments may be implemented using one or more customized hardware devices, such as ASICs. Yet other embodiments may be implemented using one or more programmable hardware elements, such as FPGAs.

In some embodiments, a non-transitory computer-readable storage medium may be configured to store program instructions and / or data, the program instructions, when executed by a computer system, causing the computer system to perform a method, such as any of the method embodiments described herein or any one Combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets.

In some embodiments, a device (eg, a terminal 106 ) to contain a processor (or a group of processors) and a storage medium, the storage medium storing program instructions, the processor being configured to read and execute the program instructions from the storage medium, the program instructions being executable to implement a method, e.g. Any of the method embodiments described herein (or any combination of the method embodiments described herein, or any subset of any of the method embodiments described herein, or any combination of such subsets). The device can be realized in various forms.

Although the embodiments have been described in detail in detail, various modifications and variations will become apparent to those skilled in the art after the full disclosure of the above disclosure. It is intended that the following claims be interpreted to embrace all variations and modifications.

Claims (15)

A method of operating a UE (User Equipment) device, the method including: Receiving a first index transmitted by a base station, the first index identifying a first configuration for transmission of a first physical random access channel (PRACH) through link budget limited terminal devices in a cell corresponding to the base station, wherein the first index from a second index also broadcast by the base station, the second index identifying a second configuration for transmitting the PRACH through non-link budget limited terminal devices in the cell; in response to determining that the terminal device has been classified as link budget constrained, transmitting the PRACH to the base station, wherein the PRACH is transmitted according to the first configuration. The method of claim 1, wherein the base station is configured to transmit a first system information block and a second system information block, the first information block including the first index, the second system information block including the second index. The method of claim 2, wherein the second system information block is a type 2 system information block as defined by the LTE standard. The method of claim 1, wherein the first configuration indicates a first set of allowable temporary opportunities for transferring the PRACH through link budget limited terminal devices, the second configuration providing a second set of allowable temporary opportunities for transferring the PRACH through non-link budget indicates limited terminal devices, wherein the first amount and the second amount are elementary. The method of claim 1, wherein the first index identifies the first configuration from a list of PRACH configurations defined by an existing wireless communication standard, the second index identifying the second configuration from the list of PRACH configurations. The method of claim 1, wherein the first index also differs from one or more other PRACH configuration indices, each transmitted by one or more adjacent base stations, wherein the one or more further PRACH configuration indices are for use by non-link Budget-limited terminal devices are sent in one or more other cells, each corresponding to one or more other base stations. A terminal device comprising: a processor; and Memory that stores program instructions, the program instructions, when executed by the processor, causing the processor to: receive a first index transmitted by a base station, the first index identifying a first configuration for transmission of a physical random access channel (PRACH) by link budget limited terminal devices in a cell corresponding to the base station, the first index being from a also distinguishes second index sent by the base station, the second index identifying a second configuration for transmitting the PRACH through non-link budget limited terminal devices in the cell; and in response to a determination that the terminal device has been classified as link-budget restricted, transmitting the PRACH to the base station, wherein the PRACH is transmitted according to the first configuration. The terminal device of claim 7, wherein the base station is configured to transmit a first system information block and a second system information block, the first information block including the first index, the second system information block including the second index. The terminal device of claim 8, wherein the second system information block is a Type 2 system information block as defined by the LTE standard. The terminal device of claim 7, wherein the first configuration indicates a first set of allowable temporary opportunities for transmission of the PRACH by link budget limited terminal devices, the second configuration a second set of allowable temporary opportunities for transmission of the PRACH through non-link budget indicates limited terminal devices, wherein the first amount and the second amount are elementary. The terminal device of claim 7, wherein the first index identifies the first configuration from a list of PRACH configurations defined by an existing wireless communication standard, the second index identifying the second configuration from the list of PRACH configurations. The terminal device of claim 7, wherein the first index also differs from one or more other PRACH configuration indices, each transmitted by one or more adjacent base stations, wherein the one or more further PRACH configuration indices are for use by non-link Budget-limited terminal equipment in one or more other cells, each corresponding to one or more other base stations. A non-volatile storage medium for operating a terminal device, the storage medium storing program instructions, the program instructions, when executed by a processor, causing the processor to implement: receiving a first index transmitted by a base station, the first index identifying a first configuration for transmitting a first physical random access channel (PRACH) through link budget limited terminal devices in a cell corresponding to the base station, the first index being from a second index also broadcast by the base station, the second index identifying a second configuration for transmitting the PRACH through non-link budget limited terminal devices in the cell; in response to a determination that the terminal device has been classified as link-budget-limited, transmitting the PRACH to the base station, wherein the PRACH is transmitted according to the first configuration. The storage medium of claim 13, wherein the base station is configured to transmit a first system information block and a second system information block, the first information block including the first index, the second system information block including the second index. The storage medium of claim 13, wherein the first configuration indicates a first set of allowable temporary opportunities for transferring the PRACH through link budget limited terminal devices, the second configuration providing a second set of allowable temporary opportunities for transferring the PRACH through non-link budget indicates limited terminal devices, wherein the first amount and the second amount are elementary.

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