KR102571817B1 - Apparatus for transmitting and receiving data through unlicensed band - Google Patents

Abstract

It includes a processor, a memory, and a wireless communication unit, and the processor executes a program stored in the memory to generate an auxiliary synchronization signal in at least one remaining subframe other than subframe 0 or subframe 5 among a plurality of subframes included in the DMTC. An apparatus for receiving a signal through an unlicensed band is provided, performing the steps of receiving and detecting an auxiliary synchronization signal using the subframe number of subframe 0 or subframe 5.

Description

Receiving device and transmitting device for transmitting and receiving data through an unlicensed band {APPARATUS FOR TRANSMITTING AND RECEIVING DATA THROUGH UNLICENSED BAND}

The present disclosure relates to a transceiver for transmitting and receiving data through an unlicensed band.

As the number of mobile Internet users increases through mobile communication systems, mobile communication service providers are seeking efficient ways to increase the capacity of mobile communication systems. The most efficient and intuitive method is to increase the bandwidth by additionally securing licensed band frequencies for the mobile communication system. However, the licensed band frequency has the advantage of providing efficient mobile communication service through exclusive use of the frequency, while the license and use cost of the frequency is high, and the licensed band frequency allocated for the mobile communication system is limited. There is a downside to that. Accordingly, mobile communication operators and manufacturers use unlicensed band frequencies with relatively many available frequency bands and low cost, TV white space, and frequencies such as licensed/unlicensed bands shared between mobile communication system operators (hereinafter referred to as 'unlicensed band frequencies'). ) is being used to provide mobile communication services.

Communication systems installed in unlicensed band frequencies have the following limitations.

First, transmission power is limited to minimize the impact that may have on other systems sharing the unlicensed band frequency. Therefore, when the licensed band system and the unlicensed band system are installed in the same place, a coverage hole may occur.

In addition, for fair coexistence with adjacent unlicensed band systems, unlicensed band frequencies must be used discontinuously or opportunistically. Therefore, transmission reliability of the control channel and the common channel of the mobile communication system may be lowered.

In addition, it must comply with the frequency regulation of unlicensed bands. Systems using unlicensed band frequencies must operate based on Listen Before Talk (LBT) for data transmission. For example, a device (or system) using an unlicensed band frequency must perform clear channel assessment (CCA) and determine whether the channel is used according to the CCA result. At this time, even if the channel is occupied according to the CCA result, the channel occupancy time may be limited according to the frequency regulation, the channel cannot be occupied for a time exceeding the maximum channel occupancy time, and CCA must be additionally performed to reoccupy the channel. do.

Due to the limitations of the unlicensed band system as above, a scenario in which the licensed band system and the unlicensed band system are installed/operated in a complementary form is being reviewed rather than a standalone system that uses only the unlicensed band in providing mobile communication services. . In this scenario, control functions that require reliability, such as terminal control and mobility management, are performed through licensed band frequencies, and traffic functions, such as wireless transmission speed increase and wireless traffic load distribution, use unlicensed band systems to supplement the licensed band systems. It will work in the form of For example, a control function and a traffic function are performed through a carrier in a licensed band, and a traffic function is performed through a carrier in an unlicensed band.

The above operations of the licensed band carrier and the unlicensed band carrier may be implemented through carrier aggregation (CA) technology of 3GPP LTE. For example, a carrier aggregation method between an unlicensed band frequency division duplex (FDD) carrier and a licensed band carrier, or an unlicensed band time division duplex (TDD) carrier in which both uplink and downlink operate. There is a carrier aggregation method between a carrier and a licensed band carrier.

A cellular system using an unlicensed band can provide a mobile communication service with guaranteed service quality by utilizing low-cost, abundant frequency resources and advanced interference control technology. However, new coexistence technology and interference control technology are required to solve various regulations existing in the unlicensed band and coexistence problems with other unlicensed band systems and to secure the above advantages. In particular, due to the nature of the unlicensed band, a device operating in the unlicensed band can occupy and use the channel. In this case, when carrier aggregation is applied to solve problems due to coexistence with other devices in the unlicensed band and restrictions on operation in the unlicensed band, the characteristics of the licensed band and the unlicensed band must be considered at the same time. In addition, it should be possible to provide a reliable service equivalent to the existing cellular system by reflecting the limitations (characteristics) for device operation in the unlicensed band.

One embodiment provides an apparatus for receiving an auxiliary synchronization signal through an unlicensed band.

Another embodiment provides an apparatus for transmitting data or traffic over an unlicensed band.

According to one embodiment, a receiving device for receiving a signal through an unlicensed band is provided. The receiving apparatus includes a processor, a memory, and a wireless communication unit, and the processor executes a program stored in the memory to select at least one remaining subframe other than subframe 0 or subframe 5 among a plurality of subframes included in the DMTC. The step of receiving an auxiliary sync signal and the step of detecting the auxiliary sync signal using the subframe number of subframe 0 or subframe 5 are performed.

In the receiving device, the auxiliary synchronization signal is composed of a sequence of length 62 generated using the following equation,

[mathematical expression]

DMTC may include subframes 0, 1, 2, 3, 4 or subframes 5, 6, 7, 8, and 9.

In the receiving device, the processor may further perform a step of acquiring a cell ID based on a detection result of the auxiliary synchronization signal by executing a program stored in a memory.

In the receiving device, when the processor performs the step of receiving the auxiliary synchronization signal, the processor performs the step of receiving the auxiliary synchronization signal in the first subframe among at least one remaining subframe, and the processor executes a program stored in the memory to , a step of receiving data in a subframe next to the first subframe among the remaining subframes may be further performed.

When performing the step of receiving the auxiliary synchronization signal, the processor in the receiving device may perform the step of receiving the auxiliary synchronization signal, the primary synchronization signal, and the cell-specific reference signal in the first subframe among the remaining subframes.

In the receiving apparatus, the processor may further perform a step of receiving a channel state information-reference signal when performing the step of receiving the secondary synchronization signal, the primary synchronization signal, and the cell-specific reference signal.

In the receiving device, the secondary synchronization signal, the primary synchronization signal, and the cell-specific reference signal may be received within 12 OFDM symbols included in the first subframe.

In the receiving apparatus, the processor may execute a program stored in a memory and further perform a step of detecting a cell specific reference signal using a slot number of a slot included in the first subframe.

According to another embodiment, a transmission device for transmitting data through an unlicensed band is provided. The transmitting device includes a processor, a memory, and a wireless communication unit, and the processor executes a program stored in the memory to receive HARQ ACK / NACK corresponding to the PDSCH, the number of HARQ NACKs being ahead of the number of HARQ ACKs If the number is as high as the determined ratio, the step of increasing the contention window value of the contention window for channel access and the step of performing a channel access procedure based on the increased contention window value are performed.

In the transmitting device, the processor executes a program stored in memory, and if the number of HARQ ACKs is greater than the number of HARQ NACKs by a predetermined ratio, reducing the contention window value, and channel access procedure based on the reduced contention window value You can further perform the step of performing.

When performing the step of performing the channel access procedure based on the increased contention window value, the processor in the transmitting device may perform the step of performing CCA or extended CCA based on the increased contention window value.

When performing the step of receiving the HARQ ACK/NACK, the processor in the transmitter may perform the step of receiving the HARQ ACK/NACK corresponding to the PDSCH of the first subframe included in the COT for the channel.

In the transmitting device, the processor may execute a program stored in a memory and instruct the receiving device with an increased contention window value or a value for updating the contention window value.

According to another embodiment, a transmitting device for transmitting traffic through an unlicensed band is provided. The transmission device includes a processor, a memory, and a wireless communication unit, and the processor executes a program stored in the memory to transmit traffic corresponding to a second priority class lower than the first priority class used for channel access. and, after all traffic corresponding to the second priority class is transmitted, transmitting traffic corresponding to a third priority class higher than the first priority class.

In the transmitting device, energy detection thresholds respectively corresponding to the first priority class, the second priority class, and the third priority class may be different from each other.

In the transmitter, traffic corresponding to the second priority class may be a discovery reference signal or discovery signal, and traffic corresponding to the third priority class may be a PDSCH.

In the transmitting device, the first priority class, the second priority class, and the third priority class may be determined according to the type of traffic.

In the transmitting device, the processor executes a program stored in memory, and further performs channel access based on CCA parameters determined according to the first priority class, the second priority class, and the third priority class. can

In the transmitting device, different channel occupation times are set for the second priority class and the third priority class, and the processor executes a program stored in the memory to transmit traffic corresponding to the second priority class. Traffic may be transmitted during the channel occupation time corresponding to the second priority class.

In performing the extended CCA for efficiently using the unlicensed band, the contention window can be efficiently updated based on HARQ ACK/NACK.

1A, 1B, 2A, and 2B are conceptual diagrams illustrating a method of allocating uplink resources of an unlicensed band through a licensed band.
3 is a flowchart illustrating a method for accessing a channel of an unlicensed band according to an embodiment.
4A to 4C are layout views illustrating a mobile communication system in which UCC is set and operated.
5 is a conceptual diagram illustrating CCA by contention window adjustment according to an embodiment.
6 is a conceptual diagram illustrating a channel access method based on priorities according to an embodiment.
7 is a conceptual diagram illustrating a data transmission method according to CCA termination according to an embodiment.
8 is a conceptual diagram illustrating a channel access method of a multi-carrier network according to an embodiment.
9 is a conceptual diagram illustrating a channel access method of a multi-carrier network according to another embodiment.
10 to 12 are conceptual diagrams illustrating a channel access method of a multi-carrier network according to another embodiment.
13 is a conceptual diagram illustrating a multi-cell network according to an embodiment.
14 to 16 are conceptual diagrams illustrating a channel access method in a multi-cell network according to an embodiment.
17 is a conceptual diagram illustrating a channel access method when DRX is performed according to an embodiment.
18 is a conceptual diagram illustrating a channel access method when DRX is performed according to another embodiment.
19 is a block diagram illustrating a wireless communication system according to an embodiment.

Hereinafter, with reference to the accompanying drawings, embodiments of the present disclosure will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly explain the present description in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal includes a mobile station (MS), a mobile terminal (MT), an advanced mobile station (AMS), and a high reliability mobile station (HR-MS) ), subscriber station (SS), portable subscriber station (PSS), access terminal (AT), user equipment (UE), machine type communication device, MTC device), etc., and may include all or some functions of MT, MS, AMS, HR-MS, SS, PSS, AT, UE, etc.

In addition, a base station (BS) includes an advanced base station (ABS), a high reliability base station (HR-BS), a node B, an evolved node B, eNodeB), access point (AP), radio access station (RAS), base transceiver station (BTS), mobile multihop relay (MMR)-BS, relay that serves as a base station station (RS), relay node (RN) that serves as a base station, advanced relay station (ARS) that serves as a base station, and high reliability relay station (HR) that serves as a base station -RS), small base station [femto base station (femto BS), home node B (home node B, HNB), home eNodeB (HeNB), pico base station (pico BS), macro base station (macro BS), micro base station (micro BS ), etc.], and may include all or some functions of ABS, NodeB, eNodeB, AP, RAS, BTS, MMR-BS, RS, RN, ARS, HR-RS, small base station, etc. there is.

The method of adjusting the contention window and the method of applying the backoff according to the present disclosure may include a transmission device performing CCA accessing a channel for data transmission or a receiving device accessing a channel for data reception. It can be applied to all devices that perform CCA, such as cases. For example, CCA performed by the base station to transmit data to the terminal (transmission of downlink data), CCA performed by the base station to transmit data of the terminal (transmission of uplink data), performed when exchanging data between terminals or devices CCA, or CCA performed by the terminal to transmit data to the base station using the resource allocated by the base station.

1A, 1B, 2A, and 2B are conceptual diagrams illustrating a method of allocating uplink resources of an unlicensed band through a licensed band.

Frame based equipment (FBE) and load based equipment (LBE) of FIGS. 1a, 1b, 2a, and 2b are channel access methods defined in the ETSI standard and the 3GPP standard, and have basic operations The method specified in the standard is applied mutatis mutandis. In addition, channel occupancy time is assumed to be 4 ms when accessing a channel.

1A and 1B, the base station allocates resources to the terminal through cross-carrier scheduling (uplink grant, UL Grant). Then, the terminal transmits data to the base station At this time, the specific UEs (UE1 and UE3) can transmit data by occupying the channel, and the other UEs (UE2 and UE4) determine that the channel is occupied by another device as a result of the CCA and cannot transmit data. , The time point at which the UE transmits data to the base station is when 4 subframes have passed since the transmission of the reference uplink grant when the primary cell (PCell) is FDD, and when the PCell is TDD, uplink This is the time when 4 to 7 subframes have passed according to the link/downlink (UL/DL) configuration.

Referring to FIGS. 2A and 2B , the base station allocates resources to the terminal through self-scheduling. Even at this time, while specific UEs (UE1 and UE3) are transmitting data, UEs (UE2 and UE4) performing CCA determine that the channel is occupied by another device and cannot transmit data.

3 is a flowchart illustrating a method for accessing a channel of an unlicensed band according to an embodiment.

The channel access method of the unlicensed band shown in FIG. 3 is a method for allowing UEs such as UE2 and UE4 of FIGS. 1 and 2 to occupy a channel after CCA.

Referring to FIG. 3 , a communication device such as a base station or terminal to transmit data through a channel of an unlicensed band may occupy a channel of the unlicensed band by performing an initial CCA and an extended CCA.

First, the communication device determines whether a data transmission request has occurred (S301), and maintains an idle state when there is no data transmission request (S302). Afterwards, when a data transmission request occurs, initial CCA is performed (S303). If the channel is idle during the initial CCA period (BiCCA) (eg, 34us), data is transmitted (S304). Thereafter, the communication device determines whether additional data transmission has occurred (S305), and returns to the Idle state if there is no data to be additionally transmitted.

However, if there is additional data to be transmitted or if it is determined that the channel is busy or used or occupied during the initial CCA (hereinafter referred to as “BUSY”), the communication device performs extended CCA. To perform the extended CCA, the communication device generates a random counter N in a contention window q (ie, [0, q-1]) (S306). At this time, the contention window q may be updated through dynamic backoff or semi-static backoff between X and Y (S307). In addition, HARQ ACK/NACK may be used when updating the contention window.

Thereafter, the communication device determines whether the channel is idle during the extended CCA postponement period (DeCCA) (S308). If the channel is idle, the communication device determines whether the random counter N is 0 (S309). If the random counter N is 0, data is transmitted (S304). However, if the random counter N is not 0, the communication device senses the channel during one eCCA slot period (eg, 9us or 10us) (S310). Thereafter, when the communication device determines that the channel is not busy (S311), it decrements the random counter N by 1, and returns to step S308 when it is determined that the channel is busy (S312).

In FIG. 3 , a Defer Period (DP) is an additional sensing period including at least one CCA slot. In addition, a contention window (q) may be adjusted in a channel access/occupancy process according to whether previously transmitted data is successfully transmitted, and a backoff may be dynamically or quasi-statically applied. However, due to the problem of unclearly indicating whether data is successful (eg, ACK/NACK received from multiple devices, ACK/NACK received after several subframes (ie, several ms), etc.), adjustment of the contention window and Difficult to apply dynamic (quasi-static) backoff.

4A to 4C are layout views illustrating a mobile communication system in which UCC is set and operated.

Referring to FIG. 4A , indoor and outdoor low power cells in which LCC and UCC are operated in one cell are illustrated. In each case, the PCell may be a macro cell, and a secondary cell (SCell) may be co-located or non-co-located with the PCell.

Referring to FIG. 4B, a PCell in which LCC is operated and a (low power) SCell in which LCC and UCC are operated are illustrated. Each SCell where LCC and UCC operate can be deployed indoors or outdoors. The PCell may be a macro cell or a small cell, and the LCC-operated SCell and the UCC-operated SCell may be located at the same location or may not be located at the same location.

Referring to FIG. 4C , a PCell in which LCC is operated and a (low power) SCell in which UCC are operated are illustrated. The SCell in which UCC operates may be deployed indoors or outdoors, and the PCell in which LCC operates may be a macro cell or a small cell.

5 is a conceptual diagram illustrating CCA by contention window adjustment according to an embodiment.

In FIG. 5, the base station performs CCA to transmit data through UCC, and the terminal transmits HARQ ACK/NACK for data received from the base station to the base station through P-LCC. Referring to FIG. 5, the terminal transmits NACK to the base station for data transmitted in subframe n-2 and subframe n-1 (subframe n+2 and subframe n+3), and the base station responds to the NACK. data is retransmitted in subframe n+6 and subframe n+7. Thereafter, the terminal notifies NACK of the retransmitted data, and the base station retransmits the retransmitted data in subframes n+14 and n+18. At this time, the base station may perform extended CCA by selecting a CCA performance slot (N) before performing CCA. When a channel is occupied through CCA, channel occupancy time (channel occupancy time, COT) is assumed to be 4 ms.

In order to transmit data in subframe n-4, the base station performs initial CCA (or extended CCA) in subframe n-5, occupies the channel, and transmits an initial signal (IS) for data transmission do. In this case, N selected when the extended CCA is performed after the initial CCA may be randomly selected from the contention window (0 to q-1). If data transmission following the initial CCA is not successful (eg, HARQ NACK reception), the base station updates q in the previous subframe (subframe n + 5) of the subframe for data retransmission, and updated from 0 Perform extended CCA using N selected from q-1. If it is determined that there is more data to be transmitted at the time when the maximum COT expires (eg, subframe n + 10), the base station may perform a new CCA for data transmission, in which case the initial CCA may be omitted. there is. If the initial CCA is omitted, the transmitting device selects N by reapplying the contention window (0 to q-1) applied in the previous CCA. In addition, the COT interval includes initial data transmission, data retransmission corresponding to HARQ NACK, and new data transmission corresponding to HARQ ACK. The contention window may be updated according to Equation 1 below.

In Equation 1, q is a contention window for N for selecting an extended CCA interval (CCA slot) according to frequency regulation when operating an unlicensed band, and represents the maximum value of N values. k is an arbitrary value (k≥0), X is the minimum value of the contention window, and Y is the maximum value of the contention window. Y is greater than or equal to X (Y≥X).

q may change according to the COT. For example, q may be determined to satisfy Equation 2 below.

In Equation 2, COT is in ms. Alternatively, q may be determined as an arbitrary value independent of the COT, or may be determined as one of predetermined values (eg, one of 4, 8, and 16), and may be determined as a value between X and Y.

If k is greater than 1 (k>1), the contention window is updated to a value larger than the previous contention window. If k is less than 1 (k<1), the contention window is updated to a value smaller than the previous contention window. When k is 0 (k=0), the contention window is updated to the minimum value (i.e., k=X) or initialized. If k is 1 (k=1), the contention window is not updated and the previous contention window value is reused.

X may be determined according to Equation 3 below.

Alternatively, X may be the smallest natural number or any value among natural numbers greater than the minimum value (4 or 16, etc.) defined in the frequency regulation of the license-exempt band. Alternatively, X may be any number greater than the minimum value defined in the frequency regulation of the unlicensed band.

Y may be the largest natural number or any value among natural numbers smaller than the maximum value (32 or 1024, etc.) defined in the frequency regulation of the unlicensed band.

On the other hand, when X and Y are the same (X=Y), k is 1 (k=1), and Equation 4 below holds.

Renewing the contention window may follow one of the following methods or a combination of two or more. In the method of updating the contention window, k may be determined as an arbitrary value. Updating the contention window may include maintaining, increasing, decreasing, or resetting a previous contention window value to an initial value. Below, m represents the number of HARQ ACKs, and n represents the number of HARQ NACKs. The number of HARQ ACK/NACKs, m and n, are the number of HARQ ACK/NACKs received from a specific time to before CCA is performed.

- How to maintain the previous q regardless of HARQ ACK / NACK.

- How to update q in the next CCA regardless of HARQ ACK/NACK.

- How to update q when HARQ NACK is received.

- How to update q when HARQ ACK/NACK for data transmission is all HARQ NACK.

- If there are m and n HARQ ACK/NACKs for data transmission, the transmitting device may determine the update of q by comparing m and n. If k=1, the previous q is maintained, if k>1, q is increased, if 0<k<1, q is decreased, and if k=0, q may be reset to an initial value.

- When n = 0 (when all received HARQ ACK / NACK are HARQ ACKs), a method of updating q when m is greater than or less than a predetermined value.

- When m = 1 (when all received HARQ ACK/NACKs are HARQ NACKs), a method of updating q when n is greater than or less than a predetermined value.

- When m>n (when HARQ ACK is more than HARQ NACK), when the difference between m and n is greater than or equal to a predetermined value, or when the ratio of m and n is greater than or equal to a predetermined value How to update q (i.e. , since HARQ ACK is more than HARQ NACK, q is reduced).

- When m < n (when HARQ NACK is more than HARQ ACK), when the difference between m and n is greater than or equal to a predetermined value, or when the ratio of m and n is greater than or equal to a predetermined value How to update q (i.e. , since HARQ NACK is more than HARQ ACK, q is increased).

- When m = n (when the number of HARQ ACK and HARQ NACK is the same), how to update q

- A method of updating q when the ratio of HARQ ACK/NACK is greater than or less than a predetermined value, such as m/n, n/m, n/(m+n), m/(m+n), etc.

- A method of updating q when the number of m is greater than or equal to a predetermined value.

- A method of updating q when the number of n is greater than or equal to a predetermined value.

- A method of updating q when the numbers of m and n are equal to or greater than or equal to a predetermined value, respectively.

- A method of updating q when an HARQ NACK for data to which the lowest level MCS (most robust MCS) is applied is received.

In this case, if HARQ ACK is received after data to which the lowest level MCS is applied, the contention window value q may be maintained or decreased (or reset to an initial value), and if HARQ NACK is received, q value may be increased. At this time, it is possible to determine whether to update q according to the number of received HARQ ACKs, the number of HARQ NACKs, or the ratio of the number of HARQ ACKs/NACKs.

- A method of updating q according to HARQ ACK/NACK for data transmitted in a specific subframe located in the COT (eg, the first part or the last part of an occupied channel).

- A method of updating q when at least one HARQ NACK is received and performing only retransmission of data in a re-occupied channel.

In the present description, when HARQ ACK/NACK are mixed and reported from one receiving device, the HARQ ACK/NACK reported from the corresponding receiving device may not be used to determine whether to update the contention window. And, the HARQ ACK/NACK received after the update of q may not be used to determine whether to update the contention window. Even HARQ ACK/NACK reported before a specific time may not be used to determine whether to update the contention window.

When the terminal tries to transmit data to the base station through the uplink resource, the base station instructs the terminal to update q or a k value for updating q when allocating resources for data retransmission, so that the terminal receives the received q or q CCA can be performed based on the value of k for updating . Alternatively, contention window renewal for data retransmission of the terminal may be performed based on a value of q or k previously set between the terminal and the base station. Alternatively, the UE may determine renewal of the contention window according to whether the previously applied MCS is changed. For example, when the MCS is changed from a high-level MCS to a low-level MCS, or when the MCS is changed from a low-level MCS to a high-level MCS, the UE may renew the contention window. When two or more uplink resources are allocated to the terminal (eg, one uplink resource is dedicated to data retransmission and the other uplink resources are dedicated to initial data transmission), the contention window for each uplink resource Renewal may be determined separately. If there is a time equal to or longer than a predetermined time before the UE performs uplink data transmission after CCA (eg, after an uplink grant (UL grant) and before subframe k), the UE does nothing during that time. It may not perform an action (eg, contention window update).

Meanwhile, the contention window may be updated according to Equation 5 below.

When Equation 5 is applied, q may be updated (increased or decreased or maintained) to a value changed by k from the previous q. Alternatively, q may be updated according to channel access/occupancy or data transmission results, not based on HARQ ACK/NACK.

Below, a method of updating the contention window according to the channel state will be described in detail. In CCA performed for channel access/occupation, the q value of the contention window may be updated according to the measured channel state. For example, a parameter representing a channel state may be compared with a predetermined value, and renewal of the contention window may be determined based on a result of the comparison. Alternatively, renewal of the contention window may be determined based on the number of times the channel is occupied or the number of times the channel is not occupied after the CCA.

When the resource allocation method of the base station is self-scheduling (or self-carrier scheduling), indicated through a physical downlink control channel (PDCCH) (or EPDCCH) , resource allocation information for data transmission is included in the same carrier as data transmission. In this case, there may be a case where there is no HARQ ACK / NACK for (E) PDCCH, and since the terminal can receive data only when reception of (E) PDCCH is successful, the base station uses a contention window based on HARQ ACK / NACK is difficult to update. That is, if (E) PDCCH is not successfully received, there is a case where the terminal cannot receive data, so when updating the contention window, the terminal ignores the HARQ ACK/NACK transmission result for the corresponding data (i.e., not recognized as ACK or NACK), or always recognized as NACK. In self-scheduling, the transmitting device that has received feedback on the data from the receiving device determines that it is difficult for the data to be correctly transmitted due to the poor channel condition, and applies a lower level MCS (more robust MCS) or does not update the contention window. CCA may be performed by resetting to the initial contention window.

If the resource allocation method of the base station is cross-carrier scheduling, the base station may update the contention window based on HARQ ACK/NACK received as feedback from the receiver.

Meanwhile, the base station may add resource allocation for retransmission to HARQ ACK/NACK. And, information about the updated contention window may be included in resource allocation for data transmission or resource allocation for data retransmission. Thereafter, the base station may perform CCA for retransmission based on the updated contention window. On the other hand, the base station may not update the contention window or reset the contention window to an initial value when resources for retransmission are not allocated or resources for retransmission are not allocated. Alternatively, when the base station allocates resources, it informs the terminal of N selected within the contention window and configures the terminal to perform CCA during N CCA slots, so that the terminal can perform CCA during N CCA slots.

Below, a channel access method according to the priority of transmitted traffic will be described in detail. Priorities may be set for traffic transmitted on the unlicensed band channels according to characteristics or types of traffic, and channel access may be performed according to the set priorities. For example, ETSI's FBE and LBE options A/B or 3GPP's LBT categories 2, 3, and 4, etc. In this description, priorities may be set as follows according to the characteristics or types of traffic.

- Priority according to traffic types such as video, audio, and general traffic

- Priority according to whether it is a control channel or a data channel

- Priority according to specific channel types such as PDCCH, PDSCH, PUSCH, PUCCH

- Priority according to the purpose of transmitted data such as DRS and PDSCH

Depending on each priority, CCA parameters, channel access methods, etc. may be independently applied.

Channel access may be performed by setting an LBT priority class and determining a CCA parameter for each set class. Table 1 shows CCA parameters for channel access according to priority.

LBT Priority Class CW _min (X) CW _max (Y) n One 3 7 One 2 7 15 One 3 15 63 3 4 15 1023 7

Referring to Table 1, CW _min and CW _max are the minimum contention window size and the maximum contention window size, respectively, and n is the number of CCA slots included in the defer period (DP). For example, since CW _min , CW _max , and n of class 1 are smaller than those of other classes (class 2, 3, or 4), channel access is highly likely to succeed. Other parameters (eg, energy detection threshold, etc.) for CCA not shown in Table 1 may also be set differently for each class. In addition, the CCA parameter according to the priority class may be applied to CCA slot determination, re-determination, adjustment, etc. described above, and may also be applied to other CCA methods not described in the present disclosure. When traffic corresponding to a plurality of classes is transmitted, CCA parameters applied for each class may be used. However, when traffic corresponding to a plurality of classes is transmitted, a CCA parameter application method may be additionally required.

Hereinafter, a case in which traffic included in two or more classes is serviced based on priority through FIG. 6 will be described. In Figure 6, J and K represent the LBT priority class level (Quality Class Level, QCL) parameters. When K is greater than J (K>J), both initial CCA and extended CCA are performed, and when K is less than or equal to J (K≤J), only extended CCA without initial CCA can be performed. .

In the present description, the determination/use of parameters (eg, CCA parameters, channel occupation time, etc.) for data transmission through channel occupation/use depends on the transmission device (eg, base station or terminal) to transmit traffic. can be performed by Alternatively, when the base station determines parameters related to channel occupation or use for transmission of uplink traffic of the terminal and allocates uplink resources, the base station may transmit the parameters according to the type (or class) of the allocated traffic.

Thereafter, the terminal receiving parameters for channel occupation or use from the base station may perform CCA and transmit data using the received parameters. If the base station does not indicate some or all of the parameters for channel occupation or use, or if the terminal is not instructed to partially or all of the parameters, the method described below is applied, or the method described below is applied to some or all of the parameters not indicated Applicable only to all parameters. The transmitting device may transmit traffic through the occupied channel after performing CCA using a parameter related to channel occupancy corresponding to the traffic class. At this time, only traffic having the same class as the parameter class used when performing CCA is transmitted, or traffic having a class different from traffic having the same class as that of the parameter used when performing CCA is transmitted during the allowed occupied channel time. can

Referring to (a) of FIG. 6, only traffic of the same class is transmitted on a channel occupied after CCA. In this case, the channel occupation time for each class may be set differently, and data may be transmitted only during the channel occupation time corresponding to the class. When transmitting data, the transmitting device occupies a channel by performing CCA and transmits data through the occupied channel. If there is no traffic of the same class as the parameter class used for performing CCA within the allowed channel occupation time, the transmitting device either does not use the occupied channel or transmits data regardless of the traffic class during the remaining channel occupation time. can

Referring to (b) of FIG. 6, a traffic transmitting device (eg, a base station or a terminal) accesses/occupies a channel using a CCA corresponding to a relatively low priority class, and then returns the occupied channel. transmits different traffic of different classes through Alternatively, referring to (c) of FIG. 6, the transmitting device accesses/occupies a channel using a CCA corresponding to a relatively high priority class, and then transmits different traffic of different classes through the occupied channel. do.

For example, if the transmitting device transmits different traffic of priority class 1 and 3, the transmitting device accesses the channel using the CCA corresponding to priority class 1 and occupies the channel as much as the COT corresponding to class 1. After that, traffic corresponding to priority classes 1 and 3 may be transmitted through the occupied channel ((c) of FIG. 6). Alternatively, when the transmitting device transmits different traffic of priority classes 1 and 3, the transmitting device accesses the channel using CCA corresponding to priority class 3, occupies the channel by the COT corresponding to class 3, Traffic corresponding to priority classes 1 and 3 may be transmitted through the occupied channel ((b) of FIG. 6).

At this time, when data is transmitted over at least one TTI, the class of data transmitted in a predetermined TTI (eg, the first TTI, some earlier TTIs, some last TTIs, all TTIs, or some TTIs), All may be set to 1 or the number or ratio of data classes transmitted in a predetermined TTI may be predetermined. That is, in the COT of the occupied channel, the transmitting device preferentially transmits data corresponding to the priority class applied for channel occupancy. Thereafter, if there is no data corresponding to the priority class applied for channel occupation (when all data corresponding to the priority class is transmitted), traffic corresponding to the same TTI within the allowed COT or a different priority class in subsequent TTIs this can be transmitted.

If re-determination or adjustment (for example, HARQ ACK/NACK-based update) of the previous CCA slot is required, CCA parameters for each priority used in the most recent CCA as well as CCA parameters corresponding to other priorities The most recent CCA slot re-determination or adjustment method may also be applied to slot re-determination or adjustment. Alternatively, channel access may be attempted using the CCA parameter so that only traffic having the same priority as that of previously transmitted traffic is transmitted. In this case, traffic having the same priority may be transmitted in all occupied channels or traffic having the same priority may be transmitted in some TTIs of the occupied channels. Alternatively, traffic having the same priority may be transmitted only in the first TTI, or each TTI may include at least one traffic having the same priority. That is, traffic corresponding to the same priority is transmitted first, and (when there is no more data corresponding to the corresponding priority class), traffic corresponding to a different priority is transmitted in the same TTI or later TTI within the allowed COT. It can be.

In order to simultaneously service (or exchange) different traffics having different priorities in a channel occupied through a new channel occupation attempt, the transmitting device uses parameters of the class with the highest priority or the class with the lowest priority. CCA can be performed.

When the transmitting device performs CCA using a parameter corresponding to a class with the highest priority, a predetermined number or a predetermined ratio or more in a predetermined TTI (the first TTI in the COT, some TTIs in the beginning, or all TTIs, etc.) , data of the highest class can be serviced. That is, data of a higher class may be served first in the allowed COT (when data corresponding to the priority class no longer remains), and data of a lower class may be sequentially serviced in the same TTI or subsequent TTIs. At this time, when the transmitting device performs CCA using parameters corresponding to the class having the highest priority, the transmitting device performs initial CCA and extended CCA, and the transmitting device performs CCA using parameters corresponding to the remaining classes. When performing, the transmitting device may perform only extended CCA.

When the transmitting device performs CCA using a parameter corresponding to a class with a relatively low priority, the transmitting device occupies a channel determined to be idle and correlates with the priority within the COT corresponding to the class with a relatively low priority. traffic can be transmitted without In addition, when the transmitting device determines that the channel is “busy” while performing CCA using a parameter corresponding to a class with a relatively low priority and the CCA slot is frozen, the transmitting device has the highest priority. CCA can be performed by applying parameters corresponding to the class. Then, when the transmitting device occupies the channel again, the transmitting device 1) reuses the frozen CCA slot, 2) performs only the extended CCA (at this time, the CCA slot, etc. are determined again), or assigns to a class with a lower priority. Initial CCA and extended CCA may be performed using the corresponding parameters (at this time, the CCA slot and the like are determined again).

Meanwhile, a channel access method may vary depending on the purpose of traffic (eg, data for service control, data corresponding to a service, etc.). For example, transmitted data may include a discovery reference signal (DRS), PUCCH, PUSCH, PDSCH, or PDCCH. PDSCH is a channel used when a base station transmits data to a terminal, PUSCH is a channel used when a terminal transmits data to a base station, and PDCCH transmits downlink resource allocation information and uplink resource allocation information from a base station to a terminal. It is a channel for delivering control information including The DRS is a channel including control information for cell identification, channel quality measurement, and the like, and is also referred to as a discovery signal (DS). In general, PDCCH may be transmitted in the same occupied period as PDSCH through a channel occupied after CCA. The CCA for the PDCCH may include a CCA for uplink grant transmission and a CCA for uplink data transmission. DRS may be transmitted through independent CCA without PDCCH/PDSCH/PUSCH, and CCA may be performed even in this case. Table 2 shows an example of a channel access method according to the traffic purpose, and in this description, the base station may apply one of the channel access methods according to the traffic purpose described below or a combination of two or more. In Table 2, it is assumed that the order of priority of the channel access method is 1>2>3.

purpose Channel approach typical example service control 1 One DRS service control 2 2 PDCCH data transmission 3 PDSCH, PUSCH

- When the first traffic to which channel access method 1 is applied and the second traffic to which channel access method 2 or 3 is applied are simultaneously transmitted, channel access may be attempted using channel access method 1 with the highest channel access probability. there is. When data is transmitted through at least one TTI included in a channel occupied after CCA, the first traffic may be included in a predetermined number or ratio or more in a predetermined TTI (such as an initial TTI or an earlier partial TTI).

- When the first traffic to which channel access method 1 is applied and the second traffic to which channel access method 2 or 3 is applied are simultaneously transmitted, channel access is attempted using channel access method 2 or 3 having a relatively low channel access probability. It can be. When channel access method 3 is used, all traffic corresponding to channel access methods 1, 2, and 3 can be transmitted within the allowed COT corresponding to channel access method 3. When channel access method 2 is used, traffic corresponding to channel access methods 1 and 2 may be transmitted. At this time, if channel occupancy fails (channel is in use, etc.) or traffic transmission fails (transmission failure due to collision, etc.), data corresponding to the low-probability channel access method is suspended (or postponed) and transmitted , channel access may be retried using a high-probability channel access method. For example, the channel is occupied by applying the channel access method 1, and transmission of the first traffic may be guaranteed. For example, different channel access methods may be used each time DRS and PDSCH (and/or PDCCH) are transmitted. For example, channel access method 1 may be used when only DRS is transmitted, and channel access method 2 or 3 may be used when only PDSCH is transmitted. When channel access method 2 is used, PDCCH and PDSCH may be transmitted, and when channel access method 3 is used, only PDSCH may be transmitted. Even when DRS and PDSCH are simultaneously transmitted, channel access method 2 or 3 may be used. Even in this case, if channel access method 2 is used, PDCCH and PDSCH may be transmitted together, and if channel access method 3 is used, only PDSCH may be transmitted. And, if channel occupation fails and remaining CCA slots occur, 1) the channel is re-occupied by re-performing CCA during the remaining CCA slots, or 2) a channel access method with high probability (eg, channel access method 1) can be used

- At this time, traffic to which different channel access methods are applied may be restricted so that they are not simultaneously transmitted.

- When the CCA slot is re-determined or adjusted, the contention window value of the previous CCA slot can be reused regardless of the channel access method corresponding to the traffic transmitted after the latest CCA. Alternatively, only traffic corresponding to the same channel access method as that of previously transmitted traffic may be transmitted. After channel occupation is newly attempted, traffic corresponding to a plurality of channel access methods may be transmitted after a CCA performed by applying a channel access method having the highest priority or the lowest priority.

On the other hand, when the transmitting device performs CCA for channel occupation, the channel may not be occupied at the time required for data transmission (ie, the time at which the channel should be occupied). To this end, data can be transmitted from the point of channel occupation, but in 3GPP LTE, data is transmitted in units of subframes or slots or orthogonal frequency division multiplex (OFDM) symbols, so subframes or slots in the occupied channel Alternatively, data may not be transmitted in the OFDM symbol.

7 is a conceptual diagram illustrating a data transmission method according to CCA termination according to an embodiment.

Referring to FIG. 7, a DRS that occurs periodically is used as an example of traffic transmitted after CCA, but is not limited thereto (ie, the data transmission method according to CCA termination described based on FIG. It can be applied to all data transmitted according to timing such as transmitted PUSCH, subframe, slot, OFDM symbol, etc.).

Referring to FIG. 7, a base station may transmit DRS according to a predetermined period and perform CCA before transmitting DRS. As a result of CCA, when the channel is determined to be occupied ("Idle"), the base station transmits DRS, and when the channel is determined to be occupied ("busy" or "occupied"), the base station attempts CCA again. When it is determined that the channel can be occupied after the retried CCA, the base station may transmit traffic. In FIG. 7 , the base station may perform CCA according to the DRS measurement timing configuration (DMTC) and transmit the DRS to the terminal. That is, the base station may transmit DRS in a DMTC period period, the base station adjusts the DMTC offset before transmitting the DRS, transmits the DRS during the DRS occasion duration, and the DRS occasion The period is included within the DRS measurement duration (or DMTC window, hereafter referred to as "DMTC window"). Since the base station performs CCA, it can implement LBT. The base station may perform at least one DRS transmission in the DMTC window of the occupied channel. If the base station cannot transmit the DRS within the DMTC window due to channel conditions (eg, CCA execution time, maximum channel occupancy time, etc.) (ie, when the DMTC window ends before DRS transmission, etc.), can be extended

Referring to (a) of FIG. 7, a base station that fails to occupy a channel in the initial CCA performs CCA again and transmits a DRS when the channel is determined to be idle. At this time, re-execution of CCA may be limited within the DMTC window or the number of re-executions may be limited.

Referring to (b) of FIG. 7, since the channel is occupied after CCA, the base station attempts CCA again, and the base station can slightly advance the next CCA time point compared to (a) of FIG. For example, the base station may arbitrarily select a CCA performance time point according to a predetermined CCA performance time point, and the channel occupancy probability may increase. In addition, the base station can prevent other devices from occupying the channel by transmitting the "R" signal (R≥0) before transmitting data after CCA (LBT earlier & transmit "R"). At this time, if the maximum size (or maximum time) of the "R" signal is limited, the transmitting device adjusts the CCA execution time so that the "R" signal can be transmitted before data transmission, or the transmission of the "R" signal is terminated. Thereafter, CCA may be additionally performed.

In the present description, the transmitting device may determine the CCA start time point (T _s ) in consideration of the time available for performing the CCA (T _c ) so that the CCA can be completed before the data transmission time point (T _d ). The relationship between data transmission time (T _d ), CCA execution time (T _c ), and CCA start time (T _s ) is shown in Equation 6 below.

On the other hand, if the transmitting device does not terminate the CCA until the data transmission time, the transmission device cannot transmit data at the data transmission time. Referring to (c) of FIG. 7 , when the CCA result determines that the channel is idle, the transmitting device may occupy the channel until the next _Td and then transmit data at the next Td. CCA may be omitted until the next T _d (LBT & shift the DRS till next DRS occasion). In the case of (c) of FIG. 7, the channel occupancy of the base station may be limited within the DMTC window or the number of times may be limited. At this time, the base station may transmit the "R" signal until the next T _d . Alternatively, if CCA is not terminated at the time of DRS transmission, the base station may skip transmission of the corresponding DRS and perform CCA again before transmission of the next DRS.

Referring to (d) of FIG. 7, the base station may move the data transmission time point T _d . At this time, the shift of data transmission time may be limited within the DMTC window or the number of times may be limited.

Meanwhile, DRS may be transmitted in any subframe (including subframe 0 or subframe 5) within the DMTC. Hereinafter, a method of generating a sequence of signals constituting a DRS, such as PSS, SSS, CRS, and CSI-RS, and a method of indicating information about a data burst of an occupied channel will be described in detail.

The primary synchronization signal (PSS) required for data transmission between the base station and the terminal is transmitted in subframe 0 in FDD and subframes 1 and 6 in TDD, and the secondary synchronization signal (SSS) is transmitted in subframe 0 and 5. A cell-specific reference signal (CRS) is transmitted in each downlink subframe, and a channel state information reference signal (CSI-RS) is transmitted in a predetermined subframe. However, PSS, SSS, CRS, and CSI-RS may be transmitted in other subframes due to diversity of channel occupancy according to CCA performed for operation in an unlicensed band or DRS transmission within a DMTC window.

Accordingly, when the SSS included in the DRS is transmitted in subframes other than subframes 0 and 5, 1) the SSS sequence transmitted in subframes 0 and 5 is used, or 2) the SSS is newly generated for the purpose of DRS. can The two SSS generation methods described below can be combined with each other. In each method, the SSS consists of a sequence of length 62.

- SSS sequence generation method 1: A method of generating a sequence constituting an SSS transmitted in subframes other than subframes 0 and 5 based on Equation 7.

That is, in SSS sequence generation method 1, the SSS may be generated according to a sequence generation method defined for each subframe 0 or subframe 5. Therefore, upon receiving the SSS, the UE can detect the SSS through the SSS detection method corresponding to subframe 0 or 5 when detecting the SSS, and obtain a cell identification (Cell ID) based on the SSS detection result. can

- SSS sequence generation method 2: A method of independently generating an SSS sequence transmitted in subframes other than subframes 0 and 5 for each subframe number of another subframe in which the SSS is transmitted.

According to SSS sequence generation method 2, a DRS or an initial signal transmitted in an unlicensed band (e.g., a signal transmitted before a transmission device successfully occupies a channel after CCA and transmits data) is a subframe It may be transmitted in subframes other than 0 and 5.

When SSS is transmitted in subframes other than subframes 0 and 5, transmission of CRS, CSI-RS, DM-RS, etc. may occur simultaneously with transmission of SSS. That is, in subframe 0 or subframe 5 and other subframes, SSS, PSS, CRS, CSI-RS, and DM-RS may be transmitted. In this case, the CSI-RS may be transmitted when preset through higher layer signaling, and the DM-RS may be included in the PDSCH and transmitted when the PDSCH is transmitted. That is, DM-RS is not transmitted in a subframe in which only DRS is transmitted without PDSCH.

Sequences such as CRS, CSI-RS, and DM-RS may be generated through one or a combination of two or more of the methods described below.

- Method 1: This is a method of generating CRS, CSI-RS, and DM-RS based on the slot number included in subframe 0 or subframe 5.

- Method 2: Unlike SSS, this is a method of generating CRS, CSI-RS, and DM-RS based on slot numbers included in subframes in which CRS, CSI-RS, and DM-RS are transmitted.

In method 2, CRS, CSI-RS, and DM-RS and PSS and SSS are transmitted in the same subframe (ie, a subframe other than subframe 0 or subframe 5), but SSS is transmitted in subframe 0 or subframe It is generated through a formula based on the subframe number of 5, and the CRS, CSI-RS, and DM-RS are generated based on the slot number included in the subframe number in which the CRS, CSI-RS, and DM-RS are transmitted. do. In this case, the SSS, CRS, CSI-RS, and DM-RS may be transmitted through some OFDM symbols (ie, partial subframes) among a plurality of OFDM symbols included in one subframe. For example, DRS may be transmitted through 12 OFDM symbols included in one subframe.

DRS may be transmitted in at least one subframe other than subframe 0 or subframe 5 in the DRS occasion, and data may be transmitted in subframes other than the subframe in which the DRS is transmitted. For example, if the base station occupies a channel through CCA in subframe 1 in the DRS occasion, the base station transmits DRS in subframe 2, and the remaining subframes included in the DRS occasion (subframe 3 and subframe 4) ), data can be transmitted, or DRS can be (re)transmitted.

When channel occupancy is limited according to frequency operation regulations, the transmitting device may instruct the receiving device or the receiving device the time length of the occupied channel as follows and exchange data.

First, a receiving device of a sequence may determine a channel occupation time through a sequence generated based on limited channel occupation. Table 3 shows a method of expressing the channel occupancy time in units of slots, and Table 4 shows a method of expressing the channel occupancy time in units of subframes (or TTI units).

Referring to Tables 3 and 4, information on channel occupancy time is obtained by a pseudo-random sequence generator that generates a reference signal (CRS, CSI-RS, DM-RS, etc.) It can be included in the initial value (C _init ) of the random sequence. Accordingly, the receiving device receiving the reference signal may identify the channel occupation time through the initial value of the random sequence. Table 5 shows a method of expressing channel occupancy time in units of slots when DRS+PDSCH is transmitted, and Table 6 shows a method of expressing channel occupancy time in units of subframes (or TTI) when DRS+PDSCH is transmitted. .

first
slot second
slot third
slot 4th slot ... n-1st
slot nth
slot note Method S1 k k-1 k-2 k-3 ... k-(n-2) k-(n-1) current slot is the number of the slot in the COT Method S2 F(=01) I(=10) I(=10) I(=10) ... I(=10) L(=11) Determined by whether the slot is first (F), middle (I), or last (L) Method S3 L(=0) L(=0) L(=0) L(=0) ... L(=0) L(=1) Determined by if the slot is last Method S4 P(=0) P(=0) P(=0) P(=0) ... P(=1) P(=1) Determined by whether the slot is a partial slot

first
serve
frame second
serve
frame third
serve
frame fourth
serve
frame ... (n-1)th
serve
frame Nth
serve
frame note Method T1 k k-1 k-2 k-3 k-(n-2) k-(n-1) Current subframe is the subframe number in COT Method T2 F(=01) I(=10) I(=10) I(=10) I(=10) L(=11) Determined by whether the subframe is first (F), middle (I), or last (L) Method T3 L(=0) L(=0) L(=0) L(=0) L(=0) L(=1) Determined by whether the subframe is last Method T4 P(=0) P(=0) P(=0) P(=0) P(=0) P(=1) Determined by whether a subframe is a partial slot

DRS note first
slot second
slot third
slot 4th slot ... n-1st
slot nth
slot Method S11 k k-1 k-2 k-3 ... k-(n-2) k-(n-1) current slot is the number of the slot in the COT Method S12 F(=01) I(=10) I(=10) I(=10) ... I(=10) L(=11) Determined by whether the slot is first (F), middle (I), or last (L) Method S13 L(=0) L(=0) L(=0) L(=0) ... L(=0) L(=1) Determined by if the slot is last Method S14 P(=0) P(=0) P(=0) P(=0) ... P(=0) P(=1) Determined by whether the slot is a partial slot

first
serve
frame second
serve
frame third
serve
frame
(DRS) fourth
serve
frame ... (n-1)th
serve
frame Nth
serve
frame note Method T11 k k-1 k-2 k-3 ... k-(n-2) k-(n-1) Current subframe is the subframe number in COT Method T12 F(=01) I(=10) I(=10) I(=10) ... I(=10) L(=11) Determined by whether the subframe is first (F), middle (I), or last (L) Method T13 L(=0) L(=0) L(=0) L(=0) ... L(=0) L(=1) Determined by whether the subframe is last Method T14 P(=0) P(=0) P(=0) P(=0) ... P(=0) P(=1) Determined by whether a subframe is a partial slot

Referring to Tables 3 to 6, the reference signal reception device may determine the channel occupancy time based on the current slot or subframe.

- In methods S1, S11, T1, and T11, when the channel occupancy time after CCA is n [ms] (n TTIs, n subframes, 2n slots, etc.), n _s of the first slot is k, two n _s of the first slot may be set to k-1, n _s of the third slot may be set to k-2, and n _s of the last slot may be set to kn. Or, by setting n _s to an existing slot number index (or subframe number index) and corresponding one of k-1, k-2, ..., kn to each slot separately from n _s , a channel already occupied A channel occupancy time of or a channel occupancy time of a channel to be occupied in the future may be indicated. In this case, k may be set to a maximum occupancy time, an occupancy time n for transmitting current data, or an arbitrary number. If k = n, it may be possible to predict a subframe/slot to be transmitted later after the current subframe/slot.

-In methods S2, S12, T2, and T12, information indicating which slot or subframe of the channel occupied by the current slot or subframe corresponds to (ie, the beginning / middle / of the channel occupied by the current slot or subframe) information indicating the last slot or subframe), n _s may be replaced, or the above information may be included in C _init separately from n _s .

- In methods S3, S13, T3, and T13, n _s is replaced with information indicating that the current slot or subframe is the last slot or subframe of the channel occupied, or the above information is provided to C _init separately from n _s can be included

- When DRS or a signal similar to DRS (eg, SSS) is transmitted, Method 1 and Method 2 described above may be applied. For example, when DRS or a signal similar to DRS is included, a sequence of each slot included in the corresponding subframe is generated using n _s (=0, 1) (or n _s =0) of C _init , The sequence generation method described above may be applied to other subframes and slots.

Alternatively, a sequence generated based on limited channel occupancy or a sequence generated based on the same sequence may be mapped to a resource element (RE) through Equation 8 below. According to Equation 8 below, each sequence mapped to a resource element can be distinguished for each slot and subframe.

Meanwhile, in one embodiment, when the last subframe of the occupied channel is a partial subframe, the communication device may inform the counterpart communication device of information about the partial subframe through the following method.

The length of the partial subframe may be set through a radio resource control (RRC) message or preset between communication devices. At this time, a value indicating the length of the partial subframe may be additionally defined. For example, a subframe indicated by P=1 as in methods S4, S14, T4, and T14 is indicated as a partial subframe, and the communication device may use the indicated partial subframe. A subframe indicated by P=0 may be indicated as a normal subframe.

When two or more partial subframes are used, a value indicating the length of the partial subframe may be added. For example, when four partial subframes are used, 00, 01, 10, and 11 may be used as values capable of expressing the length of the partial subframe, and may be used in the form of “P+length value”. By using such a partial subframe, "P=0" can be expressed even when a channel is occupied and usable. And in the case of “P=0”, the length of the partial subframe may be ignored.

Information on whether to use the partial subframe and the length value of the partial subframe may be included in the above-described sequence or may be included in a previously defined channel (eg, PCFICH, DCI (in PDCCH), PHICH, etc.) . When information on whether to use partial subframes and the length value of partial subframes are included in a physical hybrid ARQ indicator channel (PHICH), they may be included instead of HARQ ACK/NACK.

When the information on whether to use partial subframes and the length value of partial subframes are included in the physical control format indicator channel (PCFICH), the part representing the OFDM symbol length of the PDCCH is RRC signaling. It may be replaced or expressed right before the part indicating the starting position of the PDSCH and the EPDCCH. In addition, information on whether to use partial subframes and a length value of partial subframes may be included in the PCFICH only when applied to all subframes or when partial subframes are included. In addition, the part related to the PDCCH in the PCFICH may be limited to 1 or 2 OFDM symbols. In this case, when the part related to the PDCCH is limited to 1 or 2 OFDM symbols, the PHICH period of the extended PHICH period of the PHICH duration may be set to 1 or 2 or 3. When the PHICH period is 3, the UE may be instructed to recognize 2 PHICH periods by the UE. This is similar to the configuration of DwPTS.

When the information on whether to use partial subframes and the length value of partial subframes are included in the PDCCH, the information on whether to use partial subframes and the length value of partial subframes are commonly received by all terminals. It may be included as common downlink control information (DCI) in a common search space.

Meanwhile, in the partial subframe, the DRS may be transmitted only in the partial subframe configured when the DRS is longer than the predetermined length, or the DRS may not be transmitted in the partial subframe.

8 is a conceptual diagram illustrating a channel access method of a multi-carrier network according to an embodiment.

In FIG. 8, a transmitting device accesses a channel operated by multiple carriers for data transmission. Referring to FIG. 8 , the transmitting device performs CCA through the first SCell. And the transmitting device performs the CCA and then simultaneously transmits at a predetermined time (eg, point coordination function inter-frame space (PIFS), or LBT synchronization boundary (LSB)) During (time until synchronous transmission boundary, STB), a channel may be additionally sensed and data may be transmitted in the first SCell and the second SCell. Referring to FIG. 8, the channels of the third SCell and the fourth SCell are occupied by other devices (eg, WiFi band devices) operating in the unlicensed band, and are not used for data transmission of mobile communication. In this case, the transmitting device may perform CCA only on one channel and simultaneously use other channels such as the channel of the second SCell through additional sensing. Another device may use the channels of the third SCell and the fourth SCell because the transmitting device does not perform CCA on another channel such as the channels of the third and fourth SCells. That is, the transmitting device performs CCA on only one channel, and can determine occupancy for other channels through additional sensing after CCA. Below, a transmitting device accesses/occupies a channel to transmit data, and a receiving device accesses/occupies a channel to receive data. Below, a case in which the transmitting device performs CCA will be described, and may also be applied to the case in which the receiving device performs CCA, but is not limited thereto.

9 is a conceptual diagram illustrating a channel access method of a multi-carrier network according to another embodiment.

Referring to FIG. 9 , the communication device may perform CCA for each carrier and exchange (transmit and receive) data through multiple channels according to the CCA result. At this time, the communication device performs channel sensing for a predetermined time (for example, a time of 'Self-deferral + 1 CCA slot' in FIG. can wait for the end of the CCA.

Referring to (a) of FIG. 9, the CCAs of the first SCell and the second SCell are terminated before the CCAs of the third and fourth SCells. Accordingly, the communication device performs channel sensing after the CCA is terminated before the data transmission time point so that the data transmission time points of the first to fourth SCells can be matched.

Referring to (b) of FIG. 9, while the CCAs of the first SCell and the second SCell are terminated and the communication device performs channel sensing until the data transmission time, the carrier in which the CCA is not terminated before the LSB (the third SCell ) or a carrier (fourth SCell) determined to be unable to occupy a channel may occur without CCA being terminated. In this case, the communication device may not use the first SCell and the second SCell for data transmission either. At this time, when the channel interval between the second SCell and the third SCell is smaller than a predetermined interval (eg, MHz unit), the communication device terminates the CCA of the third SCell and terminates or terminates the occupation of the channel for the second SCell If so, CCA can be performed again. However, when the time from the CCA end point for the first SCell and the second SCell to the LSB (or STB) is relatively long, other unlicensed band devices may use carriers of the first SCell and the second SCell.

As in the third SCell in (b) of FIG. 9, if another unlicensed band device occupies the channel during CCA, and even after channel occupation by another unlicensed band device, CCA is not terminated before the STB time (i.e., channel of other unlicensed band device) If the CCA is not terminated even during the PIFS interval (eg, self-differential + 1 CCA slot (20us)) after the occupation is terminated, the communication device may operate only the first SCell and the second SCell as multi-carriers That is, the communication device may not use the third SCell as a data transmission carrier.

On the other hand, when the CCA end points of the first SCell and the second SCell are earlier than the CCA end points of the third and fourth SCells, the additional channel sensing period of the communication device is longer than the predetermined time, preventing the communication device from occupying the channel. can At this time, the predetermined time may be a defer period (DP), and the DP may be “defer duration (DD) + 1 CCA slot or PIFS. In this case, DP and PIFS are DP≥PIFS≥ 0 or PIFS≥DP≥0.

10 to 12 are conceptual diagrams illustrating a channel access method of a multi-carrier network according to another embodiment.

Referring to FIG. 10, the communication device does not sense a channel for a time period from terminating the CCA for the 1st SCell and the 2nd SCell to terminating the CCA for the 3rd SCell and the 4th SCell, and other unlicensed bands. In order to prevent the first SCell and the second SCell from being occupied by the device, the first SCell and the second SCell transmit a special signal R(R≥0). Thereafter, the communication device may sense the channel during DP in the first to fourth SCells, and then start data transmission at the STB time point.

Referring to FIG. 11, the communication device senses a channel during DP after terminating the CCA for the first to fourth SCells, and transmits a special signal R from the first SCell and the second SCell that terminated the CCA first. . That is, in FIGS. 10 and 11, the communication device may match the data transmission timing of each carrier through transmission of the special signal R.

Referring to FIG. 12, the CCAs for the third SCell and the fourth SCell are not terminated even during DP for the first SCell and the second SCell. In this case, the communication device transmits data using carriers of the first SCell and the second SCell when sensing of the additional channels of the first SCell and the second SCell is terminated. Thereafter, when the channel occupation times for the first SCell and the second SCell have not expired, the communication device uses the carriers of the first to fourth SCells at the point when the DPs for the third SCell and the fourth SCell are terminated. data can be transmitted.

Below, an unlicensed band channel access method for multi-cell operation will be described through FIGS. 13 to 16.

13 is a conceptual diagram illustrating a multi-cell network according to an embodiment.

Referring to FIG. 13, when a plurality of base stations or access points (APs) included in a multi-cell network access a channel of an unlicensed band and transmit data by occupying the channel, each communication device performs CCA. In this case, applied CCA parameters (eg, CCA slot, energy detection level, DP, etc.) may be the same. However, due to spatial differences in sensing areas in which each communication device performs CCA, channel energy may be measured differently. In this case, only some devices access the channel and occupy the channel, and other devices may determine that the channel is in use, and count down of the CCA slot may be stopped (CCA slot freeze). In this case, another device that fails to access the channel measures the energy of the channel again and checks whether the channel is occupied. That is, although a plurality of communication devices perform CCA by applying the same parameters, they cannot simultaneously perform channel access with other unlicensed band devices due to the performance of CCA. Hereinafter, a method for simultaneously performing channel access by a plurality of communication devices performing CCA using the same CCA parameter will be described.

If it is before performing CCA, by applying the same CCA parameter and performing CCA, each communication device can simultaneously perform channel access.

14 to 16 are conceptual diagrams illustrating a channel access method in a multi-cell network according to an embodiment.

Referring to (a) of FIG. 14, after completing the CCA, the first base station (LAA eNB 1) and the second base station (LAA eNB 2) transmit information about CCA termination, such as the fact of CCA termination or the timing of CCA termination, to other It is transmitted to the base station (the third base station (LAA eNB 3) and the fourth base station (LAA eNB 4)). Thereafter, the base station (base station 1 and base station 2) that has terminated the CCA performs additional sensing during a predetermined self-differential period. In addition, the base station (base station 3 and base station 4) receiving the information on the CCA termination performs additional sensing after terminating the CCA in the self-differential interval. At the same time, when information on a point in time (STB) for starting service is preset and shared between base stations, each base station may perform self-differential up to STB. At this time, at least one CCA slot may be included after the self-differential, or at least one CCA slot may be included in the self-differential. In the case of the first base station and the second base station, since the self-differential period is formed longer than DP, the first base station and the second base station transmit the special signal R as shown in (a) and (b) of FIG. 15, and the third base station and simultaneous channel access with the fourth base station. In (a) of FIG. 15, the first base station and the second base station transmit R before DD, and in (b) of FIG. 15, the first base station and the second base station transmit R after DD.

Referring to (b) of FIG. 14, the third base station and the fourth base station could not complete CCA due to other unlicensed band devices. While the third base station is performing CCA, another unlicensed band device uses the channel, and another unlicensed band device uses the channel while the CCA of the fourth base station is not terminated. At this time, the base station (base station 3 and base station 4) that did not terminate the CCA may transmit information about the CCA slot frozen during CCA to other base stations (base station 1 and base station 2). At this time, information about the frozen CCA slot may be transmitted to another base station at the time of being frozen or at the time of restarting the count down. When the time length of the remaining CCA slot is longer than the self-differential period, the third base station and the fourth base station may perform CCA separately from the first base station and the second base station and occupy the channel. That is, in this case, simultaneous channel access is performed only for the first base station and the second base station.

Referring to FIG. 16 , a plurality of STBs may be configured. If the CCA of some base stations (base station 3 and base station 4) is terminated after the first STB, all base stations (base station 1, base station 2, base station 3, and base station 4) may terminate CCA and some base stations may terminate CCA. After occupying the channel, data can be transmitted simultaneously. That is, data can be simultaneously transmitted from the next STB. In this case, the next STB may be located after the additional sensing period of the third and fourth base stations, and the DP located after the CCA of the third and fourth base stations is a period for synchronizing data transmission (eg, CCA slot, etc.) may be included.

Meanwhile, in the case of discontinuous reception (DRX), a communication device may access a channel in a plurality of different ways. 17 is a conceptual diagram illustrating a channel access method when DRX is performed according to an embodiment.

Referring to FIG. 17 , DRX performed by a communication device includes an on duration and an off duration (eg, opportunity for DRX). In the off period, the UE monitors the (E)PDCCH. And, in the on period, the base station and the terminal may perform a procedure for transmitting and receiving data. For example, the terminal may receive (E)PDCCH for data transmission and reception in the on period. The base station needs to perform CCA to transmit the (E)PDCCH through the unlicensed band, and the terminal needs to perform CCA to transmit and receive data according to the reception result of the (E)PDCCH. That is, in the channel access method according to DRX described below, a transmitting device (e.g., a downlink terminal, an uplink base station, and a receiving side in the case of data exchange between devices) trying to transmit data to a receiving device. For example, it can be applied to a downlink base station, an uplink terminal, and a transmitting side in case of data exchange between devices), and can also be applied to a receiving device that receives data from a transmitting device.

(a), (b), (c), (d), (e), (f), and (g) of FIG. 17 show a channel access method near the on-period start point, and FIG. 17 (w ), (x), (y), and (z) represent channel access methods near the end of the on-period. At the start of the on-period, the base station can transmit and receive data with the terminal corresponding to the on-period when the channel is occupied, and performs CCA for channel occupancy when the channel is not occupied. If it is a time point earlier by a predetermined time (one or two OFDM symbols, one slot, one subframe, etc.) from the start of the on-period, the communication device performs CCA, and the start of the on-period after the end of the CCA Additional sensing may be performed up to , or a special signal R may be transmitted ((a), (b), (c), (d), (e) of FIG. 17).

At this time, the special signal R is transmitted within the on period, and may be for synchronization for data exchange and prevention of access of other unlicensed band devices (FIG. 17 (a), (b)). Alternatively, the special signal R may be transmitted before the on period and used for time synchronization until the on period ((c), (d) of FIG. 17).

Referring to (f) of FIG. 17, when the communication device does not perform LBT before the on period, CCA is performed after the on period, and the special signal R instructs the receiving device to set the method, thereby helping to receive data. can give

Referring to (g) of FIG. 17, when the unlicensed band is occupied and used by other unlicensed band devices (serving base station, WiFi device, etc.) when transitioning from the on period to the off period, the base station 1) uses the unlicensed band Assuming that data exchange will be difficult until the point of availability and data exchange at the time of transition from the off period to the on period is not expected, or 2) for data exchange at the time of transition from the on period to the off period, a special signal R is applied to each sub It can be added to a frame (or TTI).

On the other hand, when the time from CCA to data exchange is included in the off period, the base station 1) performs additional sensing (DP), or 2) transmits a special signal R, or 3) another terminal corresponding to the on period can exchange data with When the base station exchanges data with other terminals corresponding to the on period, it is possible to transmit (E)PDCCH for data exchange and exchange data only during the on period of a specific terminal according to a DRX cycle set for each terminal.

When the maximum channel occupancy time according to the license-exempt band frequency operation regulation expires during the on-period, CCA for channel access may be additionally performed. As shown in (w), (x), (y), and (z) of FIG. 17, the time when the on period ends and the off period (opportunity for DRX) starts (the time of transition from the on period to the off period) is determined by the UE. may be set in advance), one or a combination of two or more of the following methods may be instructed to the receiving device.

- It may be restricted so that CCA for channel access is not performed at the time of transition from the on period to the off period (FIG. 17 (z)).

- If the CCA for channel access is terminated within a predetermined time before the transition point, the channel occupation may be extended as an off period by the channel occupation time determined through the CCA (FIG. 17(y)).

- If the channel is occupied through CCA in the on period and the start time of the off period arrives before the maximum channel occupancy time is reached, 1) data transmission is stopped according to the end of the on period ((x) in FIG. 17) Alternatively, 2) the on period may be extended by the increased time for the maximum channel occupancy time, and the transition point to the off period may be delayed (FIG. 17(w)). When the transition to the off period is delayed, the DRX cycle may be readjusted so that the next on period is also delayed by the delay in the start of the off period. Alternatively, the DRX cycle may be maintained at the original setting regardless of the delay in transition to the off period.

18 is a conceptual diagram illustrating a channel access method when DRX is performed according to another embodiment.

18 shows a method of operating unlicensed multiple carriers within an on-period. Referring to FIG. 18 , DRX performed by a communication device includes an on duration and an off duration (eg, opportunity for DRX). In the on period, the base station and the terminal may perform a procedure for transmitting and receiving data. For example, the terminal may receive (E)PDCCH for data transmission and reception in the on period. The base station needs to perform CCA to transmit the (E)PDCCH through the unlicensed band, and the terminal needs to perform CCA to transmit and receive data according to the reception result of the (E)PDCCH. Additionally, in order to operate multi-carriers for the DRX cycle, one or a combination of two or more of the multi-carrier operation methods in the unlicensed band described with reference to FIG. 17 may be applied to each carrier. In this case, the DRX cycle may also be independently operated for each carrier or commonly operated for multiple carriers.

When a common DRX cycle is operated, power of the terminal can be saved by performing CCA within the on period or immediately before the start of the on period when the off period is changed from the on period to the on period as shown in FIG. 18 (a). there is. If the on-period after CCA corresponds to the off-period of the terminal, the base station may perform additional sensing until the on-period of the terminal or transmit a special signal R, such as DP (or self-differential, PIFS, etc.). At this time, data exchange after CCA may be performed in the on period.

19 is a block diagram illustrating a wireless communication system according to an embodiment.

Referring to FIG. 19 , a wireless communication system according to an embodiment includes a base station 1910 and a terminal 1920.

The base station 1910 includes a processor 1911, a memory 1912, and a radio frequency unit (RF unit) 1913. The memory 1912 is connected to the processor 1911 and may store various information for driving the processor 1911 or at least one program executed by the processor 1911 . The wireless communication unit 1913 may be connected to the processor 1911 to transmit and receive wireless signals. The processor 1911 may implement a function, process, or method proposed in an embodiment of the present disclosure. In this case, in the wireless communication system according to an embodiment of the present disclosure, the air interface protocol layer may be implemented by the processor 1911. An operation of the base station 1910 according to an embodiment may be implemented by the processor 1911.

The terminal 1920 includes a processor 1921, a memory 1922, and a wireless communication unit 1923. The memory 1922 is connected to the processor 1921 and may store various information for driving the processor 1921 or at least one program executed by the processor 1921 . The wireless communication unit 1923 may be connected to the processor 1921 to transmit and receive wireless signals. The processor 1921 may implement functions, steps, or methods proposed in the embodiments of the present disclosure. In this case, in the wireless communication system according to an embodiment of the present disclosure, the air interface protocol layer may be implemented by the processor 1921. Operations of the terminal 1920 according to an embodiment may be implemented by the processor 1921.

In an embodiment of the present description, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various known means. Memory is a volatile or non-volatile storage medium in various forms, and may include, for example, read-only memory (ROM) or random access memory (RAM).

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims are also included in the scope of the present invention. that fall within the scope of the right.

Claims (19)

A receiving device for receiving a signal through an unlicensed band,
It includes a processor, a memory, and a wireless communication unit,
The processor executes the program stored in the memory,
A secondary synchronization signal (SSS) in at least one remaining subframe other than subframe 0 or subframe 5 among a plurality of subframes included in the discovery signal measurement timing configuration (DMTC) receiving a, and
Detecting the auxiliary synchronization signal using the subframe number of the subframe 0 or the subframe 5
A receiving device that performs In paragraph 1,
The auxiliary synchronization signal is composed of a sequence of length 62 generated using the following equation,
[mathematical expression]

The DMTC includes the subframes 0, 1, 2, 3, 4 or the subframes 5, 6, 7, 8, and 9. In paragraph 1,
The processor executes the program stored in the memory,
Acquiring a cell identification (Cell ID) based on a detection result of the auxiliary synchronization signal
Further, the receiving device. In paragraph 1,
When the processor performs the step of receiving the auxiliary synchronization signal,
Receiving the auxiliary synchronization signal in a first subframe among the at least one remaining subframe
do,
The processor executes the program stored in the memory,
Receiving data in a subframe next to the first subframe among the remaining subframes
Further, the receiving device. In paragraph 1,
When the processor performs the step of receiving the auxiliary synchronization signal,
Receiving the auxiliary synchronization signal, a primary synchronization signal (PSS), and a cell-specific reference signal (CRS) in a first subframe among the remaining subframes
To perform, the receiving device. In paragraph 5,
When the processor performs the step of receiving the secondary synchronization signal, the primary synchronization signal, and the cell-specific reference signal,
Receiving a channel state information-reference signal (CSI-RS)
Further, the receiving device. In paragraph 5,
The auxiliary synchronization signal, the primary synchronization signal, and the cell-specific reference signal are received within 12 orthogonal frequency division multiplex (OFDM) symbols included in the first subframe. In paragraph 5,
The processor executes the program stored in the memory,
Detecting the cell-specific reference signal using a slot number of a slot included in the first subframe
Further, the receiving device. delete delete delete delete delete delete delete delete delete delete delete

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