WO2019183889A1

WO2019183889A1 - Method, devices and computer readable medium for uplink transmission in a wireless communication system

Info

Publication number: WO2019183889A1
Application number: PCT/CN2018/081127
Authority: WO
Inventors: Zhe LUO; Tao Tao; Jianguo Liu; Yan Meng; Jun Wang; Gang Shen
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy
Priority date: 2018-03-29
Filing date: 2018-03-29
Publication date: 2019-10-03
Also published as: CN111919481B; CN111919481A

Abstract

Embodiments of the present disclosure relate to methods, devices, and computer readable medium for communication. A network device comprises at least one processor, and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the network device at least to: transmit, to a terminal device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device; detect the transmission in the reserved first time interval; and detect the transmission in a second time interval not reserved for the transmission in response to failing to detect the transmission successfully in the first time interval.

Description

METHOD, DEVICES AND COMPUTER READABLE MEDIUM FOR UPLINK TRANSMISSION IN A WIRELESS COMMUNICATION SYSTEM

FIELD

Non-limiting and example embodiments of the present disclosure generally relate to a technical field of wireless communication, and specifically to methods, devices and computer readable medium for uplink transmission in a wireless communication system.

BACKGROUND

This section introduces aspects that may facilitate better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Currently a new fifth generation (5G) wireless communication technique is being studied in the third generation partnership project (3GPP) . An access technology called New Radio (NR) is to be adopted in 5G communication systems.

In 3GPP, a new study item named “Study on NR-based Access to Unlicensed Spectrum” has been agreed in March 2017, and details of the agreement may be found in Final Report v1.0.0 of 3GPP technical specification group (TSG) Random access network (RAN) work group 1 (WG1) #88 meeting which was held on 13th -17th February 2017 in Athens, Greece. This study item works on techniques which allow the operators to augment their service offering by utilizing unlicensed spectrum. Detailed descriptions of the study item may be found in a 3GPP document RP-170828.

The unlicensed spectrum may be utilized in a Licensed Assisted Access (LAA) mode or a standalone mode, and the latter is to be adopted in a future release (e.g., version 2.0) of the MulteFire (MF) technique.

In addition, the NR technique is supposed to support a plurality of types of services including, for example, enhanced mobile broadband (eMBB) , massive machine type communication (mMTC) and ultra-reliable and low latency communication (URLLC) . These services require different quality of service (QoS) in terms of delay, data rate and/or packet loss rate. For instance, the URLLC service requires low delay and/or high reliability.

SUMMARY

Various embodiments of the present disclosure mainly aim at improving communication in a wireless communication network.

In a first aspect of the disclosure, there is provided a network device. The network device comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the network device at least to: transmit to a terminal device a scheduling message indicating a first time interval reserved for a transmission from the terminal device; detect the transmission in the reserved first time interval; and detect the transmission in a second time interval not reserved for the transmission in response to failing to detect the transmission successfully in the first time interval.

In a second aspect of the disclosure, there is provided a terminal device. The terminal device comprises at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device at least to: receive, from a network device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device; determine availability of the first time interval for the transmission; determine availability of a second time interval not reserved for the transmission in response to the first time interval being unavailable; and perform the transmission in a second time interval not reserved for the transmission if the second time interval is available.

In a third aspect of the disclosure, there is provided a network device. The network device comprises means for transmitting to a terminal device a scheduling message indicating a first time interval reserved for a transmission from the terminal device; means for detecting the transmission in the reserved first time interval; and means for detecting the transmission in a second time interval not reserved for the transmission in response to failing to detect the transmission successfully in the first time interval.

In a fourth aspect of the disclosure, there is provided a terminal device. The terminal device comprises means for receiving from a network device a scheduling message indicating a first time interval reserved for a transmission from the terminal device; means for determining availability of the first time interval for the transmission; means for determining availability of a second time interval not reserved for the transmission in response to determining that the first time interval is unavailable; and means for performing the transmission in the second time interval in response to determining that the second time interval is available.

In a fifth aspect of the disclosure, there is provided a method performed by a network device. The method comprises: transmitting, to a terminal device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device; detecting the transmission in the reserved first time interval; and detecting the transmission in a second time interval not reserved for the transmission in response to failing to detect the transmission successfully in the first time interval.

In a sixth aspect of the disclosure, there is provided a method performed by a terminal device. The method comprises: receiving, from a network device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device; determining availability of the first time interval for the transmission; determining availability of a second time interval not reserved for the transmission ifthe first time interval is unavailable; and performing the transmission in the second time interval if the second time interval is available.

In a seventh aspect of the disclosure, there is provided a computer readable medium with a computer program stored thereon which, when executed by an apparatus, causes the apparatus to carry out the method of the fifth aspect of the present disclosure.

In an eighth aspect of the disclosure, there is provided a computer readable medium with a computer program stored thereon which, when executed by an apparatus, causes the apparatus to carry out the method of the sixth aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent from the following detailed description with reference to the accompanying drawings, in which like reference signs are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and are not necessarily drawn to scale, in which:

FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

FIG. 2 shows an example of an Message 3 (Msg3) transmission during an initial access procedure in an unlicensed spectrum;

FIG. 3 shows an example for multi-slot scheduling;

FIG. 4 shows a flow chart of a method in a network device for communication according to an embodiment of the present disclosure;

FIG. 5 show examples of scheduling and transmission according to some embodiments of the present disclosure;

FIG. 6 shows a flow chart of another method in a terminal device according to an embodiment of the present disclosure; and

FIG. 7 illustrates a simplified block diagram of an apparatus that may be embodied as or comprised in a terminal device or a network device according to embodiments of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. It should be understood that all these embodiments are given merely for one skilled in the art to better understand and further practice the present disclosure, but not for limiting the scope of the present disclosure. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. In the interest of clarity, not all features of an actual implementation are described in this specification.

References in the specification to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment.

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be liming of example embodiments. As used herein, the singular forms “a” , “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “wireless communication network” refers to a network following any suitable wireless communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , and so on. The “wireless communication network” may also be referred to as a “wireless communication system. ” Furthermore, communications between network devices, between a network device and a terminal device, or between terminal devices in the wireless communication network may be performed according to any suitable communication protocol, including, but not limited to, Global System for Mobile Communications (GSM) , Universal Mobile Telecommunications System (UMTS) , LTE, LTE-A, NR, wireless local area network (WLAN) standards, such as the IEEE 802.11 standards, and/or any other appropriate wireless communication standard either currently known or to be developed in the future.

As used herein, the term “network device” refers to a device in a wireless communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation Node B (gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto NB, a pico NB, and so forth, depending on the applied terminology and technology.

The term “terminal device” refers to any end device capable of accessing a wireless communication network and receiving services therefrom. By way of example and not limitation, a terminal device may be referred to as user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, wearable terminal devices, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As one example, a terminal device may represent a UE configured to communicate in accordance with one or more communication standards promulgated by the 3GPP, such as 3GPP’s GSM, UMTS, LTE, 5G, and/or MulteFire standards. As used herein, a “user equipment” or “UE” may not necessarily have a “user” in the sense of a human user who owns and/or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and/or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the wireless communication network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

As another example, in an Internet of Things (IOT) scenario, a terminal device may represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another terminal device and/or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearable devices such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment capable of monitoring and/or reporting on its operational status or other functions associated with its operation.

FIG. 1 illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. As shown, the communication network 100 may include one or more network devices, for example network device 101, which may be in a form of an eNB or gNB. It will be appreciated that the network device 101 could also be in a form of a Node B, BTS (Base Transceiver Station) , and/or BSS (Base Station Subsystem) , access point (AP) and the like. The network device 101 provides radio connectivity to a set of terminal devices, for example terminal devices 102-1, 102-2 and 102-3 which are collectively referred to as “terminal device (s) 102” . Though only three terminal devices are shown in FIG. 1 for simplicity, it should be appreciated that more or less terminal devices may be included in the communication network in practice.

The network device 101 serves the terminal devices 102 through a licensed or unlicensed frequency band, and services provided to different terminal devices by the network device 101 may be different. For example, terminal device 102-1 may receive an eMBB service from the network device 101, while terminal device 102-3 may receive an URLLC service. These services may require different transmitting/receiving performance in terms of delay, data rate and/or packet loss rate.

For instance, as an important application to be supported in NR, the URLLC service requires low delay and/or high reliability. For example, a high reliability probability of 10 ^-5 transport block error rate, a delay of 1 ms and a user plane latency of 0.5 ms may be required for uplink/downlink of URLLC traffic. As used herein, a downlink (DL) transmission refers to a transmission from a network device to a terminal device, and an uplink (UL) transmission refers to a transmission in an opposite direction.

For a terminal device in a radio resource control (RRC) -idle or a disconnected mode, most of its transmission delay/latency is contributed by an initial access procedure which is a contention based random access procedure to be performed by the terminal device to (re) connect to the network device (e.g., a gNB) before a normal traffic transmission. In NR and LTE, the initial access procedure consists of the following four steps:

Step 1: UE transmits a preamble on a Physical Random Access Channel (PRACH) ;

Step 2: gNB/eNB transmits a random access response (RAR) message to the UE;

Step 3: UE transmits a Message 3 (Msg3) based on an UL grant included in the received RAR; and

Step 4: gNB/eNB transmits a Message 4 (Msg4) to acknowledge receiving of the Msg3 from the UE.

In order to support a delay-sensitive application, latency of the above steps shall be reduced. Furthermore, it is also important to reduce latency for communications in an unlicensed band, since the network device may need to provide serves, for example a delay-sensitive application, to one or more terminal devices in its coverage through the unlicensed band.

Since an unlicensed spectrum is shared by a plurality of communication systems/devices, a listen before talk (LBT) mechanism has been introduced into communications in the unlicensed band by regulations in order to avoid interference between different systems/devices. However, the LBT mechanism leads to a large latency, since a transmission may be blocked by an LBT failure, e.g., a channel for the transmission may be occupied by other devices. As a result, latency of the initial access procedure becomes much larger in the unlicensed spectrum, compared with that in a licensed band.

FIG. 2 shows an example of an Msg3 transmission during an initial access procedure in an unlicensed spectrum. As shown in FIG. 2, a RAR from a network device at DL slot 201 schedules the first Msg3 transmission opportunity at a slot 202 outside a transmission burst 210. A length of the transmission burst 210 may be limited by a regulation for the unlicensed band which requires that a device should not transmit continuously using the unlicensed band for a time interval longer than a predefined maximum transmission time, for example, 8ms. In the example shown in FIG. 2, the first Msg3 transmission is blocked due to LBT failure, i.e., the channel at slot 202 is occupied by another device (e.g., a WiFi device) . Then, the network device transmits a downlink control indication (DCI) at a DL slot 203 for scheduling a retransmission of the Msg3 at slot 204. Such a DCI is also referred to as a “DCI of retransmission” herein. Although the scheduled second Msg3 transmission opportunity at slot 204 is within a transmission burst 220, the second Msg3 transmission is still blocked due to LBT failure. Then the network device transmits a further DCI of retransmission at slot 205 for scheduling the Msg3 again. The Msg3 transmission finally succeeds at the third time at slot 206. In this example, the latency of Msg3 transmission extends from 4 ms to 18 ms, compared with a normal Msg3 transmission in a licensed band.

As can be observed from FIG. 2, an Msg3 transmission in an unlicensed spectrum may have a large latency since a scheduled Msg3 transmission opportunity may be blocked and one or more retransmissions may be required. Therefore, there is a need for enhancing Msg3 transmission in the unlicensed band; however, no solution for solving the above problem has been proposed till now.

Furthermore, similar latency issues also exist in other communication scenarios, for example, handover and dual connectivity. For instance, during a handover procedure, a terminal device performs a non-contention based random access. After receiving a RAR from a network device, the terminal device needs to transmit a RRC signal (e.g., a RRCConnectionReconfigurationComplete message) to the network device, and the RRC signal transmission may be blocked. As another example, in dual connectivity, a terminal device needs to establish a RRC connection with both a primary cell (PCell) and a Primary Secondary cell (PSCell) , and the signaling for establishing the RRC connection may be blocked. Therefore, similar problem of large latency described with reference to FIG. 2 also exists in handover and dual connectivity.

In order to increase UL transmission opportunities, multi-slot scheduling may be used for unlicensed spectrum. For multi-slot scheduling, a single UL grant schedules transmissions of multiple slots, and a transmission in each slot is independent of others. In other words, a UL grant of multi-slot scheduling contains scheduling information for multiple legacy UL grants. Multi-slot scheduling may provide many UL transmission opportunities for UEs to overcome a LBT failure; however, it cannot be applied to an Msg3 transmission directly, since an Msg3 is required to be transmitted only once.

As another option of multi-slot scheduling, a network device may schedule multiple slots via a UL grant but the UE only transmits at one of those scheduled slots depending on a result of UL LBT. An example for this option of multi-slot scheduling is shown in FIG. 3. In this example, the network device schedules two Msg3 transmission occasions at slots n+2 and n+3 for a terminal device via a single grant at slot n, but the terminal device only transmits the Msg3 using one of the slots n+2 and n+3. It can be observed that this scheme requires the network device to reserve a plurality of transmission resources at the scheduled slots for a single UL transmission in order to avoid collision. It leads to a large overhead, since the over-reserved resources cannot be reused for other use and are wasted. Therefore, the number of slots scheduled for an Msg3 transmission should be kept small to avoid a large overhead.

In present disclosure, methods, apparatuses and computer readable medium have been proposed to enable an efficient UL transmission. Though embodiments of the present disclosure may be used for an Msg3 transmission in an unlicensed band, it should be appreciated that embodiments of the present disclosure are not limited to such a specific communication scenario, but could be applied to any communication scenario where similar problem exists. That is, the proposed methods, apparatuses and computer readable medium may also be used for transmission of other signals in a licensed or unlicensed band.

FIG. 4 shows a flow chart of a method 400 in a wireless communication system, e.g., the communication system 100 in FIG. 1. The method may be implemented by, for example, the network device 101 shown in FIG. 1. For ease of discussion, the method 400 will be described below with reference to the network device 101 and the communication system 100 illustrated in FIG. 1. However, embodiments of the present disclosure are not limited thereto.

As shown in FIG. 4, at block 410, the network device 101 transmits a scheduling message to a terminal device, e.g., the terminal device 102 in FIG. 1. The scheduling message indicates a first time interval reserved for a transmission (for example but not limited to a Msg3 transmission) from the terminal device 102.

As an example rather than limitation, the scheduling message may be transmitted via a RAR signal, or a physical downlink control channel (PDCCH) signal, e.g., in a Common Physical Downlink Control Channel (CPDCCH) . However, it should be appreciated that embodiments are not limited to any specific signaling or format for carrying the scheduling message.

In some embodiments, the reserved first time interval may provide a plurality of transmission occasions for the transmission from the terminal device 102. Some examples of the scheduling and transmitting of an Msg3 are shown in FIG. 5. In an example, the network device 101 transmits a scheduling message to the terminal device 102 at a DL slot n, and the scheduling message indicates a time interval 510 consisting of slots n+2, n+3 and n+4 reserved for a transmission from the terminal device 102.

Now referring back to FIG. 4. At block 420, the network device 101 detects the transmission in the reserved first time interval (e.g., the time interval 510 in FIG. 5) . In some embodiments, in order to make full of the scheduled first time interval, the terminal device 102 may transmit a plurality of signals using a plurality of transmission occasions included in the first time interval. In these embodiments, at block 420, the network device 101 may detect a first signal (e.g., a Msg3 501 shown in Example 1 of FIG. 5) from the terminal device 102 in a first available transmission occasion (e.g., at slot n+2 in FIG. 5) of the plurality of transmission occasions, and detect a second different signal (e.g., a sounding reference signal (SRS) 502 and/or 503 shown in Example 1 of FIG. 5) from the terminal device 102 in a further transmission occasion (e.g., at slots n+3 and n+4) of the plurality of transmission occasions.

As shown in Example 2 of FIG. 5, in some embodiments, some of the transmission occasions included in the reserved first time interval may be unavailable for the transmission from the terminal device 102. In this case, at block 420 of FIG. 4, the network device 101 may detect only one transmission (e.g., Msg 504 at slot n+3 in FIG. 5) during the first time interval 510.

In some embodiments, all of the transmission occasions included in the reserved first time interval may be unavailable for the transmission from the terminal device 102, as shown in Example 3 of FIG. 5. In this case, at block 420 of FIG. 4, the network device 101 fails to detect the transmission in the first time interval.

Now still referring to FIG. 4. At block 430, the network device 101 determines whether the detection in the first time interval succeeds. If the detection is successful, the network device 101 may end the detection at block 450; however, embodiments are not limited thereto. The network device 101 may continue its detection in this case in some embodiments.

If the detection is determined as unsuccessful at block 430 (e.g., due to LBT failure shown in Example 3 of FIG. 5) , at block 440, the network device 101 continues to detect the transmission in a second time interval (e.g., the time interval 520 in FIG. 5) which is not reserved for the transmission from the terminal device 102 using the scheduling message. In the Example 3 of FIG. 5, the network device 101 detects an Msg3 505 at slot n+5 in the unreserved second time interval 520.

In this way, the terminal device 102 is allowed to transmit in the scheduled first time interval and an unscheduled second time interval. It increases the transmission opportunities for the terminal device 102. In addition, since an additional unreserved resource is allowed to be used for the transmission from the terminal device 102, there is no need to reserve a large transmission resource via scheduling. As a result, waste of resource due to reservation is reduced.

In some embodiment, the second time interval not reserved for the transmission may include a time interval for contention based transmission. That is, during the second time interval, the terminal device 102 may obtain a transmission occasion in a contention based manner, e.g., by performing LBT.

In some embodiments, the scheduling message transmitted by the network device 101 at block 410 may further indicates a transmission format (e.g., MCS) for the transmission and/or a frequency resource for the transmission. In some further embodiments, the transmission format and/or frequency resource indicated in the scheduling message may apply to the transmission in both the reserved first time interval and the unreserved second time interval. Alternatively, the transmission format and/or frequency resource indicated in the scheduling message may apply to the transmission in the reserved first time interval directly, while the transmission format and/or frequency resource for a transmission in the unreserved second time interval may be derived implicitly based on the scheduling message. It should be appreciated that in some embodiments, the transmission format and/or frequency resource for the transmission from the terminal device 102 may be predefined, and in this case, the indication for the transmission format and/or frequency resource may be omitted from the scheduling message.

As an example rather than limitation, the method 400 may be performed by the network device 101 in an unlicensed frequency band. In this case, unavailability of a transmission occasion in the first time interval and the second time interval may be caused by a LBT failure in the unlicensed band.

In some embodiments, method 400 may be used for providing an enhanced transmission scheme of an Msg3 on unlicensed spectrum. In this scheme, multiple Msg3 transmission occasions are allocated via the scheduling message transmitted at block 410 by the network device 101. However, not all resources for the Msg3 transmission are reserved by the scheduling message. Instead, a concept of reserving window (i.e., the first time interval) may be introduced, and resources for Msg3 transmission occasions within the reserving window are reserved. In the reserving window, the terminal device 102 transmits an Msg3 based on the scheduling. In contrast, resources for Msg3 transmission occasions outside of the reserving window are not reserved, and in the resource outside of the reserving window the terminal device 102 transmits the Msg3 based on UE contention. With this scheme, the terminal device 102 may transmit an Msg3 at the first Msg3 transmission occasion with successful LBT based on network device scheduling or UE contention, depending on whether the obtained transmission occasion is within or outside of the reserving window.

For some unlicensed band, there may be regulations on maximum transmission time. For example, a device may not be allowed to transmit continuously in an unlicensed band for more than 8 ms. Therefore, in some embodiments, method 400 may further comprise a block 405, where the network device 101 determines a transmission burst time window (e.g., a time window 530 shown in FIG. 5) for transmitting and receiving at the network device. In these embodiments, at block 410 of FIG. 4, the network device 101 transmits the scheduling message during the determined transmission burst time window 530.

In some embodiments, the first time interval allocated by the scheduling message may be within the transmission burst time window, and the unreserved second time interval may be outside of the transmission burst time window. As shown in FIG. 5, in another embodiment, the first time interval (denoted as 510 in FIG. 5) provides at least a first transmission occasion (at slots n+2 and n+3) within the transmission burst time window 530 and at least a second transmission occasion (at slot n+4) outside of the transmission burst time window 530.

Alternatively or in addition, in an embodiment, the second time interval (denoted as 520 in FIG. 5) may be between the transmission burst time window 530 and next transmission burst time window 540, as shown in FIG. 5.

In the example shown in FIG. 5, at slot n within the transmission burst time window 530, the network device 101 schedules multiple occasions for a Msg3 transmission within the reserving window 510 via, for example a UL grant in a RAR or a DCI of retransmission. In some embodiments, the reserving window 510 may be defined as UL slots within the transmission burst time window 530. Alternatively, the network device 101 may inform the terminal device 102 of an UL duration and an offset for determining the reserving window 510 via a CPDCCH signaling or a RAR.

For the scheduled Msg3 occasions within the reserving window 510, the network device 101 reserves the allocated resources to avoid collisions. In some embodiments, to reuse the over-reserved resources, the terminal device 102 may transmit reference signals (e.g., SRS) for training of multiple transmitting beams of the terminal device, using reserved resources (with successful LBT) following the Msg3 transmission within the reserving window 510, as shown in Example 1 of FIG. 5.

Outside the reserving window 510, the terminal device 102 can obtain Msg3 occasions based on UE contention instead of scheduling by the network device 101. In some embodiments, the terminal device 102 may regards all slots outside the reserving window 510 as potential Msg3 occasions until the start of the next transmission burst 540. If all transmission occasions in the reserving window 510 are unavailable and the terminal device is unable to transmit an Msg3 within the reserving window 510, the terminal device 102 transmits the Msg3 at the first occasion with successful LBT outside the reserving window (i.e., in the second time interval 520) , as shown in Example 3 of FIG. 5. The transmission outside of the reserving window may be performed by reusing some scheduling information (e.g., modulation and coding schemes (MCS) and/or frequency domain resource assignment) indicated in the UL grant which is transmitted by the network device 101 at block 410 in a RAR or a DCI of retransmission, regardless of slot configuration. Note that, the network device 101 may transmit a DCI of retransmission at the next transmission burst 540 if an Msg3 has not been received till the start of the next transmission burst 540.

It should be appreciate that embodiments are not limited to any specific signaling format for the scheduling message or scheduling information included in an UL grant from the network device 101. Just for illustration rather than limitation, the scheduling information may include information fields shown in Table 1.

Table 1. Scheduling information in an UL grant

Frequency domain resource assignment 4 bits
Time domain resource assignment 4 bits
Start slot offset 3 bits
Duration
3 bits

In the example shown in FIG. 5, the network device 101 transmits a RAR to the terminal device 102, and the UL grant in RAR schedules an Msg3 transmission in three slots within the reserving window 510. That is, the length of the reserving window 510 is three slots, among which two slots are within the transmission burst time window 530 and one slot is outside the transmission burst time window. In some embodiments, the length of the reserving window 510 may be informed in a CPDCCH.

Alternatively or in addition, the reserving window and frequency resource for the Msg3 transmission may be indicated via the scheduling information shown in Table 1. The information field of “Frequency domain resource assignment” allocates frequency domain resources (e.g., physical resource blocks (PRBs) for the Msg3 transmission, and this information field may apply to all Msg3 transmission occasions. The information field of “Start slot offset” indicates the first slot at which the Msg3 can be transmitted. In the embodiment shown in FIG. 5, the RAR carrying the UL grant is transmitted at slot n, and if the “Start slot offset” indicates 2 slots, the first slot at which the Msg3 can be transmitted is slot n+2. The information field of “Duration” indicates a length of multiple scheduled Msg3 occasions, i.e., a length of the reserving window 510. In this embodiment, the duration is 3 slots, i.e., slots n+2, n+3 and n+4 are scheduled as Msg3 transmission occasions. The frequency resources (e.g., allocated PRBs) indicated by “Frequency domain resource assignment” at the three scheduled slots are reserved for Msg3 transmission with respect to multiplexing. The information field of “Time domain resource assignment” allocates symbols (e.g., Orthogonal Frequency Division Multiplexing (OFDM) symbols in a slot) for an Msg3 transmission occasion. For instance, an Msg3 transmission occasion may occupy one slot (which may correspond to 14 OFDM symbols) , and then the three scheduled slots contain three Msg3 occasions in this embodiment. In another embodiment, an Msg3 transmission occasion may occupy half a slot (which may correspond to 7 OFDM symbols) , and in this case, the three scheduled slots provides six Msg3 transmission occasions. Note that the information field of “Duration” may indicate the length of the reserving window by indicating the number of slots for the reserving window, or, the number of transmission occasions included in the reserving window.

From various embodiments described above, it can be observed that the proposed scheme provides more opportunities for transmitting a signal (for example but not limited to an Msg3) by utilizing resources outside a reserving window based on UE contention instead of network scheduling. In some embodiments, the proposed scheme may reduce the number of retransmission caused by LBT failure significantly, and/or reduce the latency of UL transmission (e.g., an initial access on unlicensed spectrum) .

Reference is now made to FIG. 6 which shows a flow chart of a method 600 for UL transmission in a wireless communication network. The method may be implemented by, for example, terminal device 102 shown in FIG. 1. For ease of discussion, the method 600 will be described below with reference to terminal device 102 and the communication network 100 illustrated in FIG. 1. However, embodiments of the present disclosure are not limited thereto.

As shown in FIG. 6, at block 610, terminal device 102 receives a scheduling message from a network device, for example the network device 101 shown in FIG. 1. The scheduling message indicates a first time interval reserved for a transmission from the terminal device. In some embodiments, the scheduling message received by the terminal device 102 at block 610 may be same as that transmitted by the network device 101 at block 410 of FIG. 4. Therefore, descriptions with respect to the scheduling message provided with reference to method 400, FIG. 4, Table 1, and FIG. 5 also apply here, and details will not be repeated.

At block 620, the terminal device 102 determines availability of the first time interval for the transmission. An example of the first time interval may be the reserving window 510 containing slots n+2, n+3 and n+4 in FIG. 5. As shown in FIG. 5, the first time interval may provide a plurality of transmission occasions for the transmission from the terminal device. In the example shown in FIG. 5, the first time interval provides 3 transmission occasions if each transmission occasion occupies one slot, and 6 transmission occasions if each transmission occasion only occupies half a slot.

In some embodiments, the terminal device 102 determines the availability of the first time interval via LBT. For example, a Clear Channel Assessment (CCA) technique or channel sensing technique may be used for the determining. If none of the transmission occasions in the first time interval is detected as available, then the first time interval is determined as unavailable.

At block 630, the terminal device 102 determines availability of a second time interval (e.g., time interval 520 shown in FIG. 5) not reserved for the transmission ifthe first time interval (e.g., the reserving window 510 in FIG. 5) is determined as unavailable. In some embodiments, the second time interval may include a time interval for contention based transmission.

At block 640, the terminal device 102 performs the transmission in the second time interval if the second time interval is determined as available. As shown in FIG. 5, in some embodiments, the second time interval 520 may include a plurality of transmission occasions, and at block 640, the terminal device 102 may transmit using the first available transmission occasion. In some embodiments, at block 640, the terminal device 102 may transmit an Msg3 to the network device 101; however, embodiments are not limited thereto.

In the Example 3 shown in FIG. 5, if the LBT performed by the terminal device 102 at the Msg3 transmission occasions within the reserving window 510 fails, the terminal device 102 continues to perform the LBT outside the reserving window 510. The terminal device 102 is allowed to transmit the Msg3 using one of the transmission occasions outside of the reserving window 510 prior to the start of the next transmission burst 540 based on UE contention. In this example, if the terminal device 102 succeeds in its LBT at slot n+5, it may transmit the Msg3 505 at this slot on a frequency resource indicated by the scheduling message or predefined. In some embodiments, the frequency resource may be indicated in an UL grant using an information field of “Frequency domain resource assignment” as shown in Table 1. In some embodiments, some scheduling information (e.g., MCS) in the UL grant for a transmission in the reserved first time interval (e.g., the reserving window 510) may be reused for the Msg3 transmission in the unreserved second time interval 520 outside the reserving window 510.

It should be appreciated that the method 600 may or may not be performed in an unlicensed band. In some embodiments, the transmission at block 640 may be performed in the unlicensed band, but the scheduling message may be received at block 610 in a licensed band. Alternatively, in some embodiments, both the receiving of the scheduling message and the transmitting are performed in the unlicensed band.

In some embodiments, to avoid a potential collision between the Msg3 transmission from the terminal device 102 and a DL transmission from the network device 101, the terminal device 102 may start its Msg3 transmission later (e.g., by postponing the Msg3 transmission for one or more OFDM symbols) in a transmission occasion outside the reserving window 510. That is, the terminal device 102 may postpone its transmission for a predefined time offset (e.g., 1 OFDM symbol) in an available transmission occasion in the second time interval prior to performing the transmission in the available transmission occasion.

Method 600 allows the terminal device 102 to transmit using an unreserved/unallocated resource if the reserved resource in unavailable. In this way, transmission opportunities of the terminal device 102 are increased without increasing resource reservation, and transmission latency may be reduced.

In some embodiments, in response to determining at block 620 that the first time interval is available, the terminal device 102 performs the transmission in the first time interval at block 625. Note that in some embodiments, the first time interval may include a plurality of transmission occasions and the terminal device 102 is allowed to transmit at any of the plurality of scheduled transmission occasions in the first time interval, as long as the terminal device 102 performs LBT successfully for the transmission occasion. Note that, in some embodiments, each transmission occasion occupies one slot; however, embodiments are not limited thereto. For example, a transmission occasion may occupy half or more than one slot in another embodiment.

In order to reuse the over-reserved resources, in some embodiments, the terminal device 102 may transmit more than one signal in the first time interval by using more than one transmission occasion. For instance, as shown in Example 1 of FIG. 5, the terminal device 102 may transmit a first signal (e.g., an Msg3 501) using the first available transmission occasion (e.g., at slot n+2 with successful LBT in FIG. 5) , and transmit a second different signal (e.g., a SRS 502 and/or 503) using a further transmission occasion (e.g., at slot n+3 and/or n+4 in FIG. 5) . In some embodiments, the terminal device 102 may transmit SRS of multiple transmission beams at the resources of the second and third available Msg3 transmission occasions. It should be appreciated that embodiments are not limited to any specific configuration of the SRS. As an example, the configuration of the SRS may be pre-defined (e.g., in a technical specification) , or informed via a RAR.

In some embodiments, the terminal device 102 may fail to transmit an Msg3 at the first Msg3 transmission occasion in the reserving window 510 shown in FIG. 5 due to LBT failure, and then it transmits the Msg3 at the second Msg3 transmission occasion with successful LBT. In some embodiments, no SRS is transmitted after the Msg3 transmission, since the LBT performed by the terminal device 102 at the third Msg3 transmission occasion (e.g., at slot n+4 in FIG. 5) outside the transmission burst time window 530 may fail, as shown in Example 2 of FIG. 5.

Note that in some embodiments, the further transmission occasion (e.g., n+4 in FIG. 5) for transmitting the second different signal (e.g., SRS) in the reserved first time interval may be outside of a transmission burst time window, and in this case, a new LBT shall be performed before transmitting using the third Msg3 occasion (at slot n+4 in FIG. 5) . That is, the terminal device 102 transmits the second different signal using the further transmission occasion in response to determining that the further transmission occasion is available.

In some embodiments, the further transmission occasion (e.g., slot n+3 in FIG. 5) follows the first available transmission occasion (e.g., slot n+2 in FIG. 5) and is within the transmission burst time window 530, and in this case, the terminal device 102 may transmit the second different signal (e.g., SRS) using the further transmission occasion without determining availability of the further transmission occasion via LBT, depending on regulations for the unlicensed band.

Note that, the scheduling message received at block 610 may further indicate a transmission format (e.g., MCS) for the transmission and/or a frequency resource for the transmission. In some embodiments, the frequency resource for the transmission may be indicated using an information field of “Frequency domain resource assignment” shown in Table 1.

In some embodiments, the transmission format (e.g., MCS) and/or the frequency resource for the transmission indicated in the scheduling message apply to transmissions in both the first time interval and the second time interval.

Note that in some embodiments, the method 600 may be used for transmitting an Msg3. The Msg3 may be prepared at the terminal device 102 before actual transmission, and scrambling of the Msg3 may be independent of the slot number/index where the Msg3 is transmitted. That is, no matter at which slot the Msg3 is transmitted, same scrambling is applied in order to simplify generation of the Msg3 and avoid preparing multiple versions of the Msg3.

In some embodiments, optionally, at block 605, the terminal device 102 may receive configuration information for a transmission burst time window (e.g., the transmission burst time window 530 in FIG. 5) from the network device 101. Descriptions with respect to the transmission burst time window provided with reference to method 400, FIG. 4 and FIG. 5 also apply here. For example, the scheduling message may be received by the terminal device 102 during the transmission burst time window. Alternatively or in addition, the reserved first time interval may be within the transmission burst time window, while the unreserved second time interval may be outside of the transmission burst time window. In some embodiments, the first time interval may include at least a first transmission occasion within the transmission burst time window and at least a second transmission occasion outside of the transmission burst time window. In some other embodiments, the unreserved second time interval may be between the transmission burst time window 530 and next transmission burst time window 540, as shown in FIG. 5.

Some embodiments of the present disclosure provide a network device, e.g., the network device 101 in FIG. 1. The network device 101 comprise means for transmitting a scheduling message to a terminal device, wherein the scheduling message indicates a first time interval reserved for a transmission from the terminal device; and means for detecting the transmission from the terminal device in the reserved first time interval and a second time interval not reserved for the transmission. In some embodiments, the network device 101 may further comprise means for determining a transmission burst time window for transmitting and receiving at the network device 101. Note that, descriptions with respect to the scheduling message, the first and second time intervals provided with reference to

method

400 and 600 also apply here and details will not be repeated.

Some embodiments of the present disclosure provide a terminal device, e.g., the terminal device 102 in FIG. 1. The terminal device 102 comprise means for receiving a scheduling message from a network device, wherein the scheduling message indicates a first time interval reserved for a transmission from the terminal device; means for determining availability of the first time interval for the transmission; and means for determining availability of a second time interval not reserved for the transmission in response to determining that the first time interval is unavailable; and means for performing the transmission in the second time interval in response to determining that the second time interval is available. In some embodiments, the terminal device 102 may further comprise means for performing the transmission in the first time interval in response to determining that the first time interval is available. In a further embodiment, the terminal device 102 may comprise means for receiving configuration information for a transmission burst time window from the network device 101. Descriptions with respect to the scheduling message, the first time interval and the second time interval provided with reference to

method

400 and 600 also apply here and details will not be repeated.

FIG. 7 illustrates a simplified block diagram of an apparatus 700 that may be embodied as or comprised in a communication device, for example, a terminal device 102 or a network device 101 shown in FIG. 1.

The apparatus 700 comprises at least one processor 711, such as a data processor (DP) and at least one memory (MEM) 712 coupled to the processor 711. The apparatus 700 may further include a transmitter TX and receiver RX 713 coupled to the processor 711, which may be operable to communicatively connect to other apparatuses. The MEM 712 stores a program or computer program code 714. The at least one memory 712 and the computer program code 714 are configured to, with the at least one processor 711, cause the apparatus 700 at least to perform in accordance with embodiments of the present disclosure, for

example method

400 or 600.

A combination of the at least one processor 711 and the at least one MEM 712 may form processing means 715 configured to implement various embodiments of the present disclosure.

Various embodiments of the present disclosure may be implemented by computer program executable by the processor 711, software, firmware, hardware or in a combination thereof.

The MEM 712 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples.

The processor 711 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples.

In addition, the present disclosure may also provide a carrier containing the computer program as mentioned above. The carrier includes a computer readable storage medium and a transmission medium. The computer readable storage medium may include, for example, an optical compact disk or an electronic memory device like a RAM (random access memory) , a ROM (read only memory) , Flash memory, magnetic tape, CD-ROM, DVD, Blue-ray disc and the like. The transmission medium may include, for example, electrical, optical, radio, acoustical or other form of propagated signals, such as carrier waves, infrared signals, and the like.

The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (e.g., circuit or a processor) , firmware, software, or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

Some example embodiments herein have been described above with reference to block diagrams and flowchart illustrations of methods and apparatuses. It will be understood that each block of the block diagrams and flowchart illustrations, and combinations of blocks in the block diagrams and flowchart illustrations, respectively, may be implemented by various means including computer program instructions. These computer program instructions may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions which execute on the computer or other programmable data processing apparatus create means for implementing the functions specified in the flowchart block or blocks.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any implementation or of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular implementations. Certain features that are described in this specification in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept may be implemented in various ways. The above described embodiments are given for describing rather than limiting the disclosure, and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the disclosure as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the disclosure and the appended claims. The protection scope of the disclosure is defined by the accompanying claims.

Some abbreviations used in the present disclosure and their corresponding expressions are list below:

CPDCCH Common Physical Downlink Control Channel

DL Downlink

DMRS Demodulation Reference Signal

gNB Next Generation Node B

LBT Listen Before Talk

LTE Long Term Evolution

MCS Modulation and coding scheme

MF MuLTEFire

Msg Message

NR New Radio

OFDM Orthogonal frequency-division multiplexing

PCell Primary Cell

PRACH Physical Random Access Channel

PRB Physical Resource Block

PSCell Primary Secondary Cell

RACH Random Access Channel

RAR Random Access Response

RE Resource Element

RRC Radio Resource Control

RS Reference Signal

SCS Subcarrier Spacing

SRS Sounding Reference Signal

UE User Equipment

UL Uplink

URLLC Ultra-Reliable and Low Latency Communications

Claims

A network device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code are configured to, with the at least one processor, cause the network device at least to:

transmit, to a terminal device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

detect the transmission in the reserved first time interval; and

in response to failing to detect the transmission successfully in the first time interval, detect the transmission in a second time interval not reserved for the transmission.
The network device of Claim 1, wherein the reserved first time interval provides a plurality of transmission occasions for the transmission from the terminal device.
The network device of Claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said network device to detect the transmission in the first time interval by:

detecting a first signal from the terminal device in a first available transmission occasion of the plurality of transmission occasions; and

detecting a second different signal from the terminal device in a further transmission occasion of the plurality of transmission occasions.
The network device of Claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said network device to detect the transmission in an unlicensed frequency band.
The network device of Claim 1, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said network device to:

determine a transmission burst time window for transmitting and receiving at the network device, and

transmit the scheduling message during the determined transmission burst time window.
The network device of Claim 5, wherein the first time interval is within the transmission burst time window, and the second time interval is outside of the transmission burst time window.
The network device of Claim 5, wherein the first time interval provides at least a first transmission occasion within the transmission burst time window and at least a second transmission occasion outside of the transmission burst time window.
The network device of Claim 5, wherein the second time interval is between the transmission burst time window and next transmission burst time window.
The network device of Claim 1, wherein the scheduling message further indicates at least one of:

a transmission format for the transmission, and

a frequency resource for the transmission.
The network device of any of Claims 1 to 9, wherein the transmission includes a transmission of a Message 3 for random access.
A terminal device, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code are configured to, with the at least one processor, cause the terminal device at least to:

receive, from a network device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

determine availability of the first time interval for the transmission;

in response to the first time interval being unavailable, determine availability of a second time interval not reserved for the transmission; and

in response to the second time interval being available, perform the transmission in a second time interval not reserved for the transmission.
The terminal device of Claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to perform the transmission in an unlicensed band.
The terminal device of Claim 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to:

in response to determining that the first time interval is available, perform the transmission in the first time interval.
The terminal device of Claim 13, wherein the first time interval provides a plurality of transmission occasions for the transmission from the terminal device.
The terminal device of Claim 14, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to perform the transmission in the first time interval by:

transmitting a first signal using the first available transmission occasion of the plurality of transmission occasions; and

transmitting a second different signal using a further transmission occasion of the plurality of transmission occasions.
The terminal device of Claim 15, wherein the first signal includes a Message 3, and the second signal includes a reference signal.
The terminal device of Claim 15, wherein the further transmission occasion is outside of a transmission burst time window, and

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to transmit the second different signal using the further transmission occasion by:

determining availability of the further transmission occasion via listen before talk; and

in response to determining that the further transmission occasion is available, transmitting the second different signal using the further transmission occasion.
The terminal device of Claim 15, wherein the further transmission occasion follows the first available transmission occasion and is within a transmission burst time window, and

wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to perform the transmission in the second time interval by:

postponing the transmission for a predefined time offset in an available transmission occasion in the second time interval prior to performing the transmission in the available transmission occasion.
The terminal device of any of Claims 11 to 18, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said terminal device to:

receive configuration information for a transmission burst time window from the network device.
The terminal device of Claim 19, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause said network device to receive the scheduling message during the transmission burst time window.
The terminal device of Claim 19, wherein the first time interval is within the transmission burst time window, and the second time interval is outside of the transmission burst time window.
The terminal device of Claim 19, wherein the first time interval provides at least a first transmission occasion within the transmission burst time window and at least a second transmission occasion outside of the transmission burst time window.
The terminal device of Claim 19, wherein the second time interval is between the transmission burst time window and next transmission burst time window.
The terminal device of any of Claims 11 to 18, wherein the scheduling message further indicates at least one of:

a transmission format for the transmission, and

a frequency resource for the transmission.
A network device, comprising:

means for transmitting, to a terminal device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

means for detecting the transmission in the reserved first time interval; and

means for detecting the transmission in a second time interval not reserved for the transmission in response to failing to detect the transmission successfully in the first time interval.
A terminal device, comprising:

means for receiving, from a network device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

means for determining availability of the first time interval for the transmission; and

means for determining availability of a second time interval not reserved for the transmission in response to determining that the first time interval is unavailable; and

means for performing the transmission in the second time interval in response to determining that the second time interval is available.
A method in a network device, comprising:

Transmitting, to a terminal device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

detecting the transmission in the reserved first time interval; and

in response to failing to detect the transmission successfully in the first time interval, detecting the transmission in a second time interval not reserved for the transmission.
The method of Claim 27, wherein the reserved first time interval provides a plurality of transmission occasions for the transmission from the terminal device.
The method of Claim 28, wherein detecting the transmission in the reserved first time interval comprises:

detecting a first signal from the terminal device in a first available transmission occasion of the plurality of transmission occasions; and

detecting a second different signal from the terminal device in a further transmission occasion of the plurality of transmission occasions.
The method of Claim 27, wherein the method is performed in an unlicensed frequency band.
The method of Claim 27, further comprising:

determining a transmission burst time window for transmitting and receiving at the network device, and

wherein transmitting the scheduling message comprises transmitting the scheduling message during the determined transmission burst time window.
The method of Claim 31, wherein the first time interval is within the transmission burst time window, and the second time interval is outside of the transmission burst time window.
The method of Claim 31, wherein the first time interval provides at least a first transmission occasion within the transmission burst time window and at least a second transmission occasion outside of the transmission burst time window.
The method of Claim 31, wherein the second time interval is between the transmission burst time window and next transmission burst time window.
The method of Claim 27, wherein the scheduling message further indicates at least one of:

a transmission format for the transmission, and

a frequency resource for the transmission.
The method of any of Claims 27 to 35, wherein the transmission includes a transmission of a Message 3 for random access.
A method in a terminal device, comprising:

receiving, from a network device, a scheduling message indicating a first time interval reserved for a transmission from the terminal device;

determining availability of the first time interval for the transmission;

in response to determining that the first time interval is unavailable, determining availability of a second time interval not reserved for the transmission; and

in response to determining that the second time interval is available, performing the transmission in the second time interval.
The method of Claim 37, wherein performing the transmission comprises performing the transmission in an unlicensed band.
The method of Claim 37, further comprises:

in response to determining that the first time interval is available, performing the transmission in the first time interval.
The method of Claim 39, wherein the first time interval provides a plurality of transmission occasions for the transmission from the terminal device.
The method of Claim 40, wherein performing the transmission in the first time interval comprises:

transmitting a first signal using the first available transmission occasion of the plurality of transmission occasions; and

transmitting a second different signal using a further transmission occasion of the plurality of transmission occasions.
The method of Claim 41, wherein the first signal includes a Message 3 for random access, and the second signal includes a reference signal.
The method of Claim 41, wherein the further transmission occasion is outside of a transmission burst time window, and

wherein transmitting the second different signal using the further transmission occasion comprises:

determining availability of the further transmission occasion via listen before talk; and

in response to determining that the further transmission occasion is available, transmitting the second different signal using the further transmission occasion.
The method of Claim 37, wherein performing the transmission in the second time interval comprises:

postponing the transmission for a predefined time offset in an available transmission occasion in the second time interval prior to performing the transmission in the available transmission occasion.
The method of any of Claims 37 to 44, further comprising:

receiving configuration information for a transmission burst time window from the network device.
The method of Claim 45, wherein receiving the scheduling message comprises receiving the scheduling message during the transmission burst time window.
The method of Claim 45, wherein the first time interval is within the transmission burst time window, and the second time interval is outside of the transmission burst time window.
The method of Claim 45, wherein the first time interval provides at least a first transmission occasion within the transmission burst time window and at least a second transmission occasion outside of the transmission burst time window.
The method of Claim 45, wherein the second time interval is between the transmission burst time window and next transmission burst time window.
The method of Claim any of Claims 37 to 44, wherein the scheduling message further indicates at least one of:

a transmission format for the transmission, and

a frequency resource for the transmission.
A computer readable medium with a computer program stored thereon which, when executed by an apparatus, causes the apparatus to perform a method of any of claims 27-36.
A computer readable medium with a computer program stored thereon which, when executed by an apparatus, causes the apparatus to perform a method of any of claims 37-50.