HARQ Feedback for NR Sidelink Communication in Unlicensed Spectrum

Abstract

Embodiments of the present disclosure relate to an apparatus, a method, a device, and a computer-readable storage medium for HARQ in NR sidelink communication in unlicensed spectrum. The method includes receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and a third device; and sending, on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen-before-talk procedure, the feedback message to the third device. In this way, additional code domain resources can provide more available time opportunities as backup resources for HARQ feedback for sidelink transmissions in an unlicensed band, which can increase the reliability of HARQ feedback transmissions for sidelink communication in unlicensed spectrum. Therefore, it can ultimately improve spectrum efficiency by avoiding unnecessary PSCCH / PSSCH retransmissions and can also reduce transmission latency at the same time.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of telecommunications, and more particularly to devices, methods, apparatuses, and computer-readable storage media for hybrid automatic repeat request (HARQ) for new radio (NR) sidelink communication in unlicensed spectrum. Background Art

[0002] In Release 16, the physical sidelink feedback channel (PSFCH) for sidelink communication is designated to carry HARQ feedback from a user equipment (UE) that is the intended recipient of a transmission over the physical sidelink shared channel (PSSCH) to the UE that performs the transmission, via the sidelink. The time resources of the PSFCH are (pre-)configured. The HARQ feedback resources can be derived from the resource locations of the physical sidelink control channel (PSCCH) / PSSCH.

[0003] Release 16 also introduced support for NR-based unlicensed spectrum access (NR-U). NR operation in the unlicensed band relies on the transmitting device sensing radio resources before starting transmission. This technique is called "Listen Before Talk" (LBT). Different types of LBT procedures (such as type 1 LBT, type 2A / 2B LBT, and type 2C LBT) have been defined for NR-based access to the unlicensed spectrum. Summary of the Invention

[0004] Generally, example embodiments of the present disclosure provide a HARQ solution for NR sidelink communication in unlicensed spectrum.

[0005] In a first aspect, a first device is provided. The first device includes 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, together with the at least one processor, cause the first device to at least receive an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and a third device from a second device; and send the feedback message to the third device on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen before talk procedure.

[0006] In a second aspect, a second device is provided. The second device includes 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, together with the at least one processor, cause the second device to at least generate an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and a third device; and send the indication to the first device and the third device.

[0007] In a third aspect, a third device is provided. The third device includes 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, together with the at least one processor, cause the third device to at least receive, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and receive, from the first device, the feedback message on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0008] In a fourth aspect, a method is provided. The method includes receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and sending, to the third device, the feedback message on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0009] In a fifth aspect, a method is provided. The method includes generating an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and sending the indication to the first device and the third device.

[0010] In a sixth aspect, a method is provided. The method includes receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and receiving, from the first device, the feedback message on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0011] In a seventh aspect, a device is provided. The device includes means for receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and means for sending, to the third device, the feedback message on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0012] In an eighth aspect, a device is provided. The device includes means for generating an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; and means for sending the indication to the first device and the third device.

[0013] In a ninth aspect, a device is provided, the device including means for receiving an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and a third device from a second device; and means for receiving a feedback message from the first device on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0014] In a tenth aspect, a computer-readable medium having a computer program stored thereon is provided, the computer program causing the device to perform the method according to the fourth aspect when executed by at least one processor of the device.

[0015] In an eleventh aspect, a computer-readable medium having a computer program stored thereon is provided, the computer program causing the device to perform the method according to the fifth aspect when executed by at least one processor of the device.

[0016] In a twelfth aspect, a computer-readable medium having a computer program stored thereon is provided, the computer program causing the device to perform the method according to the sixth aspect when executed by at least one processor of the device.

[0017] Other features and advantages of embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the present disclosure are presented in an illustrative sense, and their advantages will be explained in more detail below with reference to the accompanying drawings, in which

[0019] Figure 1 an example environment in which example embodiments of the present disclosure can be implemented is shown;

[0020] Figure 2 a signaling diagram illustrating a process of HARQ for NR sidelink communication in an unlicensed spectrum according to some example embodiments of the present disclosure is shown;

[0021] Figure 3 an example of resource mapping for HARQ feedback according to some example embodiments of the present disclosure is shown;

[0022] Figure 4 an example of time slot formats of PSCCH, PSSCH, and PSFCH according to some example embodiments of the present disclosure is shown;

[0023] Figure 5 a flowchart of an example method for HARQ for NR sidelink communication in an unlicensed spectrum according to some example embodiments of the present disclosure is shown;

[0024] Figure 6 A flowchart of an example method for HARQ for NR sidelink communication in unlicensed spectrum is shown, according to some example embodiments of the present disclosure;

[0025] Figure 7 A flowchart of an example method for HARQ for NR sidelink communication in unlicensed spectrum is shown, according to some example embodiments of the present disclosure;

[0026] Figure 8 A simplified block diagram of a device suitable for implementing example embodiments of the present disclosure is shown; and

[0027] Figure 9 A block diagram of an example computer-readable medium is shown, according to some embodiments of the present disclosure.

[0028] Throughout the drawings, the same or similar reference numerals denote the same or similar elements. Detailed Description

[0029] The principles of the present disclosure will now be described with reference to some example embodiments. It should be understood that the description of these embodiments is only for the purpose of illustration and to assist those skilled in the art in understanding and implementing the present disclosure, and does not represent any limitation on the scope of the present disclosure. The disclosure described herein can be implemented in various other ways than those described below.

[0030] In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0031] In the present disclosure, references to "one embodiment", "embodiment", "example embodiment", etc. indicate that the described embodiment may include a particular feature, structure, or characteristic, but not every embodiment must include the particular feature, structure, or characteristic. Moreover, such phrases do not necessarily refer to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an example embodiment, those skilled in the art will recognize that, whether or not explicitly described, the combination of such feature, structure, or characteristic with other embodiments is within the knowledge of those skilled in the art.

[0032] It should be understood that although terms such as "first" and "second" may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish the functions of various elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed terms.

[0033] The terms used herein are for describing particular embodiments only and are not intended to limit the example embodiments. The singular forms "a", "an" and "the" used herein also include the plural forms unless the context clearly dictates otherwise. Further understood, the terms "comprises", "comprising", "has", "having", "includes" and / or "including" when used herein specify the presence of the 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.

[0034] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0035] (a) A pure hardware circuit implementation (such as an implementation using only analog and / or digital circuitry), and

[0036] (b) A combination of hardware circuitry and software, such as (where applicable):

[0037] (i) A combination of (multiple) analog and / or digital hardware circuitry and software / firmware, and

[0038] (ii) Any part of a (multiple) hardware processor(s) with software, including (multiple) digital signal processors, software, and (multiple) memories, which work together to cause a device (such as a mobile phone or a server) to perform various functions, and

[0039] (c) (Multiple) hardware circuitry and / or (multiple) processors, such as (multiple) microprocessors or a part of (multiple) microprocessors, which require software (e.g., firmware) to operate, but the software may not be present when not needed for operation.

[0040] This definition of circuitry is suitable for all uses of the term in this application, including in any claim. As another example, as used in this application, the term circuitry also encompasses an implementation of only hardware circuitry or a processor (or multiple processors) or a part of hardware circuitry or a processor and its accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also encompasses a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network devices.

[0041] As used herein, the term "communication network" refers to a network that complies with any suitable communication standard, such as a fifth-generation (5G) system, Long-Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High-Speed Packet Access (HSPA), NarrowBand Internet of Things (NB-IoT), etc. In addition, the communication between the terminal device and the network device in the communication network can be performed according to any suitable generation of communication protocol, including but not limited to the first generation (1G), second generation (2G), 2.5G, 2.75G, third generation (3G), fourth generation (4G), 4.5G, future fifth-generation (5G) New Radio (NR) communication protocol, and / or any other protocol currently known or to be developed in the future. Embodiments of the present disclosure can be applied to various communication systems. Considering the rapid development of communication, of course, there will also be future types of communication technologies and systems that can embody the present disclosure. The scope of the present disclosure should not be limited to the above systems.

[0042] As used herein, the term "network device" refers to a node in a communication network through which a terminal device accesses the network and receives services from the network. The network device can refer to a base station (BS) or an access point (AP), for example, Node B (NodeB or NB), evolved Node B (eNodeB or eNB), NR next-generation Node B (gNB), Remote Radio Unit (RRU), Radio Header (RH), Remote Radio Head (RRH), relay, low-power node (such as femto, pico), etc., depending on the terminology and technology applied. The RAN split architecture includes a gNB-CU (centralized unit that hosts RRC, SDAP, and PDCP) that controls multiple gNB-DUs (distributed units that host RLC, MAC, and PHY). The relay node can correspond to the DU part of the IAB node.

[0043] The term "terminal device" refers to any terminal device capable of wireless communication. By way of example and not limitation, a terminal device may also be referred to as a communication device, user equipment (UE), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Terminal devices may include, but are not limited to, mobile phones, cellular phones, smart phones, Voice over Internet Protocol (VoIP) phones, wireless local loop phones, tablets, wearable terminal devices, personal digital assistants (PDAs), portable computers, desktop computers, image capture terminal devices (such as digital cameras), game terminal devices, music storage and playback devices, in-vehicle wireless terminal devices, wireless endpoints, mobile stations, laptop embedded devices (LEE), laptop mobile devices (LME), USB dongles, smart devices, wireless customer premises equipment (CPE), Internet of Things (IoT) devices, watches or other wearable devices, head-mounted displays (HMD), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automation processing chain), consumer electronic devices, devices operating on commercial and / or industrial wireless networks, etc. A terminal device may also correspond to the mobile terminal (MT) part of an integrated access and backhaul (IAB) node (also known as a relay node). In the following description, the terms "terminal device", "communication device", "terminal", "user equipment", and "UE" may be used interchangeably.

[0044] Although the functions described herein may be performed in fixed and / or wireless network nodes in various example embodiments, in other example embodiments, the functions may be implemented in a user equipment device (such as a mobile phone or tablet, laptop or desktop computer, mobile IoT device or fixed IoT device). For example, the user equipment device may be suitably equipped with corresponding capabilities as described in connection with (one or more) fixed and / or wireless network nodes. The user equipment device may be a user equipment and / or a control device, such as a chipset or a processor, which is configured to control the user equipment when installed therein. Examples of such functions include a bootstrap server function and / or a home subscriber server, which may be implemented in the user equipment device by providing software to the user equipment device, the software being configured to cause the user equipment device to perform operations from the perspective of these functions / nodes.

[0045] Figure 1 An example communication network 100 in which embodiments of the present disclosure may be implemented is shown. As Figure 1As shown, the communication network 100 includes a terminal device 110-1 (hereinafter also referred to as UE 110-1 or the first device 110-1) and another terminal device 110-2 (hereinafter also referred to as another UE 110-2 or the third device 110-2). The communication network 100 may include a network device 120 (hereinafter also referred to as gNB 120 or the second device 120). The network device 120 may communicate with the terminal device 110-1 and the terminal device 110-2. The terminal device 110-1 and the terminal device 110-2 may communicate with each other. It should be understood that the number of terminal devices and network devices is for illustrative purposes only and does not impose any limitation. The communication network 100 may include any suitable number of terminal devices adapted to implement the embodiments of the present disclosure.

[0046] The communication network 100 may be implemented in a SL communication scenario. In SL communication, communication between terminal devices (e.g., V2V, V2P, V2I communication) may be performed via a sidelink. For SL communication, information may be sent from a transmitting (TX) terminal device to one or more receiving (RX) terminal devices in a broadcast, multicast, or unicast manner.

[0047] Depending on the communication technology, the network 100 may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Access (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency Division Multiple Access (OFDMA) network, a Single-Carrier Frequency Division Multiple Access (SC-FDMA) network, etc. The communication discussed in the network 100 may conform to any suitable standard, including but not limited to New Radio Access (NR), Long-Term Evolution (LTE), LTE Evolution, Advanced LTE (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for Mobile Communications (GSM), etc. In addition, the communication may be performed according to any generation of communication protocol known currently or to be developed in the future. Examples of communication protocols include but are not limited to the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols. The techniques described herein may be used for the above-mentioned wireless networks and radio technologies as well as other wireless networks and radio technologies. For clarity, some aspects of these techniques are described below for LTE, and LTE terms are used in most of the following descriptions.

[0048] The PSFCH for sidelink communication is designated to carry HARQ feedback from a receiving UE (Rx UE) to a transmitting UE (Tx UE) performing PSSCH transmission via the sidelink. For example, the PSFCH may transmit a Zadoff-Chu sequence in one PRB, which is repeated over two OFDM symbols, where the first OFDM symbol may be used for automatic gain control (AGC), near the end of the sidelink resources in a slot. The Zadoff-Chu sequence as the basic sequence is (pre-)configured for each sidelink resource pool.

[0049] The time resources for the PSFCH are (pre-)configured. The HARQ feedback resources can be derived from the resource locations of the PSCCH / PSSCH. For PSSCH to HARQ timing, the gNB can configure the parameter K in units of slots. The time occasion of the PSFCH is determined by K. For a PSSCH transmission whose last symbol is in slot n, the HARQ feedback is in slot n+a, where a is the smallest integer greater than or equal to K, provided that slot n+a contains the PSFCH resources. In addition, the PSFCH resources for HARQ feedback for PSSCH transmissions with the same starting subchannel in different slots are FDM.

[0050] In the unlicensed band (U-band) below 7 GHz, coexistence with other systems' NR is ensured via the listen-before-talk (LBT) channel access mechanism. Therefore, a UE intending to perform SL transmission in the U-band first needs to successfully complete the LBT check before the SL transmission is initiated.

[0051] To pass the LBT check, it should be determined whether the channel is available for multiple consecutive clear channel assessment (CCA) slots. In the U-band below 7 GHz, the duration of these slots is 9 μs. If the measured power (i.e., the energy collected during the CCA slot) is below the specified threshold, the UE can determine that the channel is available during the CCA slot.

[0052] In the unlicensed spectrum, there are two types of shared channel access mechanisms, namely, load-based equipment (LBE) and frame-based equipment (FBE). For LBE, when a UE initiates communication, the UE can obtain the "right" to access the channel for a specific period of time, which can be called the channel occupancy time (COT), by applying an "extended" LBT process, in which the channel can be considered idle for the entire duration of the contention window (CW). This "extended" LBT process is usually referred to as LBT category 4 (LBT Cat.4) or LBT type 1. The durations of both COT and CW depend on the channel access priority class (CAPC) associated with the UE's traffic, as follows.

[0053] Table 1: Channel Access Priority Class (CAPC) of UL

[0054]

[0055] If the LBT type 1 (LBT Cat.4) is successfully completed, the UE may perform a transmission and obtain a COT with a duration associated with the corresponding CAPC. Even in the case where the initiating device pauses its transmission, the obtained COT may be valid. If the originating device intends to perform a new transmission (within the COT), a "reduced" LBT procedure still needs to be performed. This "reduced" LBT procedure is generally referred to as LBT category 2 (LBT Cat.2) or LBT category 1 (LBT Cat.1), and may also be referred to as LBT type 2. LBT type 2 may refer to different variants, such as LBT type 2A, LBT type 2B, and LBT type 2C.

[0056] The initiating device may share the obtained COT with its receiving device (responding device). For this purpose, the initiating device must explicitly inform (i.e., via control signaling) the responding device of the duration of the COT. The responding device may use this information to determine which category / type of LBT should be applied to perform a transmission to the initiating device. If the transmission from the responding device falls outside the COT, or the responding device intends to perform a transmission to a device other than the initiating device, the responding device may have to use LBT type 1 (LBT Cat.4) with an appropriate CAPC to obtain a new COT.

[0057] In FBE, the channel access process is different from that of LBE. In FBE, the UUT (Unit Under Test) performs LBT within the Clear Channel Assessment (CCA) interval during a fixed frame period of 1 ms to 10 ms to obtain a channel for the COT. The COT may occupy 95% of the fixed frame period while maintaining an idle period of at least 100 us. In the case where the LBT in the CCA finds that the channel is occupied, there is no transmission on the channel during the next fixed frame period.

[0058] For continuous transmissions during a COT that do not require an LBT process, the interval between two transmissions should be less than 16 us. In the case where the gap exceeds 16 us, if additional LBT does not detect a Radio Local Area Network (RLAN) transmission with a level higher than a predetermined threshold, the transmitting device may continue the transmission within the COT. The additional LBT is performed within this gap and in the observation time slots immediately before the transmission (which may be counted within the current COT).

[0059] In unlicensed spectrum, channel access relies on LBT to ensure fair coexistence of different wireless communication systems. The LBT uncertainty in unlicensed spectrum may significantly reduce the efficiency of sidelink communication. The reliable transmission of PSFCH is crucial because the retransmission of PSSCH consumes more resources than PSFCH. While PSSCH occupies multiple PRBs (usually more than 10 PRBs) of a time slot and most of the OFDM symbols, PSFCH only occupies one PRB and 2 OFDM symbols of a time slot. In unlicensed spectrum, due to LBT failures, the PSFCH transmission may not be initiated. This will result in more resources being consumed for the retransmission of PSSCH.

[0060] Therefore, the present disclosure provides a HARQ solution for NR sidelink communication in unlicensed spectrum. In this solution, at least two code domain resource sets are (pre-)configured from the gNB to the Rx-UE / Tx-UE for sidelink ACK / NACK feedback. When the Rx UE initiates a sidelink ACK / NACK feedback transmission on the PSFCH, the Rx can determine the transmission opportunity for sending the sidelink ACK / NACK feedback message based on the at least two pre-configured code domain resource sets. In this way, additional code domain resources can provide more available time opportunities as backup resources for HARQ feedback for sidelink transmission in unlicensed bands, which can increase the reliability of HARQ feedback transmission for sidelink communication in unlicensed spectrum. Therefore, it can ultimately improve the spectrum efficiency by avoiding unnecessary PSCCH / PSSCH retransmissions and, at the same time, can also reduce the transmission delay.

[0061] The principles and implementations of the present disclosure will be described in detail below with reference to Figure 2 which shows a schematic process of HARQ for NR sidelink communication in unlicensed spectrum. For the purpose of discussion, the process 200 will be described with reference to Figure 2 which shows a schematic process of HARQ for NR sidelink communication in unlicensed spectrum. For the purpose of discussion, the process 200 will be described with reference to Figure 1 to describe process 200. Process 200 may include UE 110-1, gNB 120, and another UE 110-2 as shown in Figure 1 which shows a schematic process of HARQ for NR sidelink communication in unlicensed spectrum. For the purpose of discussion, the process 200 will be described with reference to

[0062] As shown in Figure 2 gNB 120 may configure at least two code domain resource sets for sidelink ACK / NACK feedback transmission between sidelink UEs (e.g., UE 110-1 and 110-2).

[0063] In some example embodiments, the at least two code domains resources may be implemented by adopting different cyclic shifts of a base sequence. For example, the base sequence may include a Zadoff-Chu sequence.

[0064] Assume that a Zadoff-Chu sequence of length L is used for the PSFCH and N cyclic shifts are configured as a code domain resource set. For the first code domain resource set among at least two code domains, a cyclic shift set {0, L / N, 2L / N,..., (N - 1)L / N} with a distance of L / N can be configured. For the second code domain resource set among at least two code domains, a cyclic shift set {0 + L / 2N, L / N + L / 2N, (N - 1)L / N + L / 2N} with a distance of L / N can be configured.

[0065] For example, the PSFCH occupies one PRB, i.e., L = 12. The gNB 120 can configure the cyclic shifts {0, 6} as the first code domain resource set with an ACK using cyclic shift 0 and an NACK using cyclic shift 6. The gNB 120 can configure the cyclic shifts {3, 9} as the second code domain resource set with an ACK using cyclic shift 3 and an NACK using cyclic shift 9.

[0066] The gNB 120 can send an indication of at least two code domain resource sets to the UEs 110-1 and 110-2 respectively. In this case, the UE 11O-1 can be considered as the receiving UE for the sidelink transmission, while the UE 110-2 can be considered as the sending UE for the sidelink transmission. The sidelink ACK / NACK feedback message will be sent from the UE 110-1 to the UE 110-2.

[0067] Then, the UE 110-2 can select 204 the resources for the sidelink transmission and perform 206 the sidelink transmission to the UE 110-1 on the PSCCH / PSSCH between the UE 110-1 and the UE 110-2.

[0068] For the sidelink transmission sent from the UE 110-2, the UE 110-1 can send a sidelink ACK / NACK feedback message to the UE 110-2. In some example embodiments, the UE 110-1 can determine a first transmission opportunity for sending the feedback message on a first candidate code domain resource set selected from among at least two candidate code domain resource sets. Then, the UE 110-1 can perform 208 a listen-before-talk process before the first transmission opportunity. If the listen-before-talk process is successfully performed, the UE 110-1 can send 210 the feedback message on the first candidate code domain resource set at the first transmission opportunity. The UE 110-2 can also determine the first transmission opportunity for sending the feedback message on the first candidate code domain resource set and receive the sidelink ACK / NACK feedback message on the first candidate code domain resource set at the first transmission opportunity.

[0069] The first code domain resource set is used to generate a first PSFCH, which will be transmitted in a first transmission occasion relative to the PSCCH / PSSCH transmission. For PSSCH to HARQ timing, the gNB can configure the parameter K in units of time slots. The first transmission occasion of the PSFCH is determined by K. For a PSSCH transmission whose last symbol is in time slot n, the HARQ feedback is in time slot n+a, where a is the smallest integer greater than or equal to K, provided that time slot n+a contains PSFCH resources.

[0070] Figure 3 An example of resource mapping for HARQ feedback according to some example embodiments of the present disclosure is shown. For example, as Figure 3 shown, when K is configured to 1. For the PSSCH transmitted in the second time slot 302 and the third time slot 303, the first transmission occasion of the PSFCH 311 is in the fourth time slot 304.

[0071] Figure 4 An example of the time slot formats of the PSCCH, PSSCH, and PSFCH according to some example embodiments of the present disclosure is shown. The listen-before-talk process performed by the UE 110-1 in the guard symbol 401 before the PSFCH symbol 402 in the time domain is used for 25 us LBT (Cat.2 single transmit LBT) in the COT sharing scenario.

[0072] Referring again to Figure 2 , if the sidelink ACK / NACK feedback message in the first transmission occasion is not sent due to an LBT failure in the unlicensed spectrum, the UE 110-1 can determine a second transmission occasion for sending the feedback message on a second candidate code domain resource set selected from at least two candidate code domain resource sets. Then, the UE 110-1 can perform an additional listen-before-talk process 212 before the second transmission occasion. The second transmission occasion is after the first transmission occasion.

[0073] If the listen-before-talk process is successfully performed, the UE 110-1 can send 214 the feedback message on the second candidate code domain resource set in the second transmission occasion. The UE 110-2 can also determine a second transmission occasion for sending the feedback message on the second candidate code domain resource set, and receive the sidelink ACK / NACK feedback message on the second candidate code domain resource set in the second transmission occasion.

[0074] The second code domain resource set is used to generate a second PSFCH, which will be transmitted at a second timing instance relative to the same PSCCH / PSSCH transmission. The gNB may configure a (fixed) delay from the PSCCH / PSSCH transmission to the second transmission timing instance. Alternatively, the gNB may configure a (fixed) delay from the first transmission timing instance to the second transmission timing instance.

[0075] Referring again to Figure 3 , for example, the delay between the two transmission timing instances is configured to be 2 time slots. For the PSSCH transmitted in the second time slot 302 and the third time slot 303, the second timing instance of the PSFCH 312 is in the sixth time slot 306.

[0076] In some example embodiments, the first PSFCH 311 and the second PSFCH 312 contain the same ACK / NACK information corresponding to the same PSCCH / PSSCH transmission. As Figure 3 shown, the first PSFCH transmitted in the fourth time slot 304 with cyclic shifts {0, 6} and the second PSFCH transmitted in the sixth time slot 306 with cyclic shifts {3, 9} contain the same ACK / NACK information corresponding to the same PSCCH / PSSCH transmission transmitted in the second time slot 302 and the third time slot 303.

[0077] In some example embodiments, there is no overlap between the first code domain resource set and the second code domain resource set. As Figure 3 shown, in the 4th time slot 304, the PSFCH 311 cannot be transmitted due to a LBT failure in the unlicensed spectrum. In the sixth time slot 306, the first PSFCH transmitted with cyclic shifts {0, 6} corresponds to the PSCCH / PSSCH transmission in the fourth time slot 304 and the fifth time slot 305, and the second PSFCH transmitted with cyclic shifts {3, 9} corresponds to the PSCCH / PSSCH transmitted in the second time slot 302 and the third time slot 303. Since there is no overlap between the first code domain resource set and the second code domain resource set, the transmitting UE can distinguish the HARQ feedback corresponding to the PSCCH / PSSCH transmitted in two (fixed) delay time slots.

[0078] At the UE 110-2, if an ACK is received, the sidelink transmission from the UE 110-2 to the UE 110-1 is completed. If a NACK is received, the UE 110-2 may perform resource reselection for retransmission.

[0079] In this way, the additional code domain resource can provide more available time instances as backup resources for HARQ feedback for sidelink transmissions in the license-free band, which can increase the reliability of HARQ feedback transmissions for sidelink communications in the license-free spectrum. Therefore, it can ultimately improve the spectrum efficiency by avoiding unnecessary PSCCH / PSSCH retransmissions and at the same time can also reduce the transmission delay.

[0080] Figure 5 FIG. 500 is a flowchart of an example method for HARQ for NR sidelink communications in a license-free spectrum according to some example embodiments of the present disclosure. Method 500 may be implemented at a first device 110-1 as shown in Figure 1 For purposes of discussion, method 500 will be described with reference to Figure 1 FIG.

[0081] At 510, the first device receives an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and a third device from a second device.

[0082] In some example embodiments, the indication at least includes a reference sequence for configuring a reference resource set for sending the feedback message and a set of cyclic shift values for indicating the feedback message.

[0083] At 520, the first device sends the feedback message to the third device on a target code domain resource set determined based on a listen-before-talk procedure from the at least two candidate code domain resource sets.

[0084] In some example embodiments, the first device may determine a first transmission opportunity for sending the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets and perform a listen-before-talk procedure before the first transmission opportunity. If the first device determines that the LBT is successful, the first device may send the feedback message on the first candidate code domain resource set in the first transmission opportunity.

[0085] In some example embodiments, if the first device determines that the LBT fails, the first device may determine a second transmission opportunity for sending the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets, the second candidate code domain resource set being different from the first candidate code domain resource set, and the first device may perform an additional listen-before-talk procedure before the second transmission opportunity. If the first device determines that the additional LBT is successful, the first device may send the feedback message on the second candidate code domain resource set in the second transmission opportunity.

[0086] Figure 6The flowchart of an example method 600 for HARQ in NR sidelink communication in unlicensed spectrum according to some example embodiments of the present disclosure is shown. Method 600 may be implemented at a second device 120 as shown in Figure 1 For discussion purposes, method 600 will be described with reference to Figure 1 .

[0087] At 610, the second device generates an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and the third device.

[0088] At 620, the second device sends the indication to the first device and the third device.

[0089] Figure 7 The flowchart of an example method 700 for HARQ in NR sidelink communication in unlicensed spectrum according to some example embodiments of the present disclosure is shown. Method 700 may be implemented at a third device 110-2 as shown in Figure 1 For the purpose of discussion, method 700 will be described with reference to Figure 1 .

[0090] At 710, the third device receives from the second device an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and the third device.

[0091] At 720, the third device receives a feedback message from the first device on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk procedure.

[0092] In some example embodiments, the third device may perform a sidelink transmission to the first device. The third device may also determine a first transmission opportunity for sending a feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets, and detect whether the feedback message is sent from the first device on the first candidate code domain resource set during the first transmission opportunity. If the third device determines that the feedback message sent from the first device is detected, the third device receives the feedback message.

[0093] If the third device determines that the feedback message sent from the first device is not detected, the third device may determine a second transmission opportunity for sending a feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets, where the second candidate code domain resource set is different from the first candidate code domain resource set. If the third device determines that the feedback message sent from the first device is detected during the second transmission opportunity, the third device receives the feedback message.

[0094] In some example embodiments, an apparatus (e.g., implemented at UE 110-1) capable of performing method 500 may include components for performing the corresponding steps of method 500. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0095] In some example embodiments, the apparatus includes components for receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and a third device; and components for sending, on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen-before-talk procedure, the feedback message to the third device.

[0096] In some example embodiments, an apparatus (e.g., implemented at gNB 120) capable of performing method 600 may include components for performing the corresponding steps of method 600. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0097] In some example embodiments, the apparatus includes components for generating an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and a third device; and components for sending the indication to the first device and the third device.

[0098] In some example embodiments, an apparatus (e.g., implemented at another UE 110-2) capable of performing method 700 may include components for performing the corresponding steps of method 700. The components may be implemented in any suitable form. For example, the components may be implemented in circuitry or software modules.

[0099] In some example embodiments, the apparatus includes components for receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and a third device; and components for receiving, on a target code domain resource set determined from the at least two candidate code domain resource sets by the first device based on a listen-before-talk procedure, the feedback message from the first device.

[0100] Figure 8 is a simplified block diagram of a device 800 suitable for implementing embodiments of the present disclosure. The device 800 may be provided to implement a communication device, e.g., Figure 1 UE 110-1, gNB 120, and another UE 110-2 as shown. As shown, the device 800 includes one or more processors 810, one or more memories 840 coupled to the processors 810, and one or more transmitters and / or receivers (TX / RX) 840 coupled to the processors 810.

[0101] The TX / RX 840 is for two-way communication. The TX / RX 840 has at least one antenna to facilitate communication. The communication interface can represent any interface necessary for communicating with other network elements.

[0102] The processor 810 can be of any type suitable for the local technical network and, by way of non-limiting example, can include one or more of the following: general-purpose computer, special-purpose computer, microprocessor, digital signal processor (DSP), and a processor based on a multi-core processor architecture. The device 800 can have multiple processors, such as an application-specific integrated circuit chip that is subordinate in time to a clock synchronized with the main processor.

[0103] The memory 820 can include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, read-only memory (ROM) 824, electrically programmable read-only memory (EPROM), flash memory, hard disk, compact disc (CD), digital video disc (DVD), and other magnetic storage and / or optical storage. Examples of volatile memories include, but are not limited to, random access memory (RAM) 822 and other volatile memories that do not persist during a power outage.

[0104] The computer program 830 includes computer-executable instructions executed by the associated processor 810. The program 830 can be stored in the ROM 820. The processor 810 can perform any suitable actions and processes by loading the program 830 into the RAM 822.

[0105] Embodiments of the present disclosure can be implemented by the program 830 such that the device 800 can execute any process of the present disclosure referred to Figures 2 to 7 in the discussion. Embodiments of the present disclosure can also be implemented by hardware or by a combination of software and hardware.

[0106] In some embodiments, the program 830 can be tangibly embodied in a computer-readable medium, which can be included in the device 800 (such as in the memory 820) or in other storage devices accessible by the device 800. The device 800 can load the program 830 from the computer-readable medium into the RAM 822 for execution. The computer-readable medium can include any type of tangible non-volatile memory, such as ROM, EPROM, flash memory, hard disk, CD, DVD, etc. Figure 9 An example of a computer-readable medium 900 that can be in the form of a CD or DVD is shown. The program 830 is stored on the computer-readable medium.

[0107] In general, the various embodiments of the present disclosure can be implemented using hardware or dedicated circuits, software, logic, or any combination thereof. Some aspects can be implemented using hardware, while other aspects can be implemented using firmware or software that can be executed by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other graphical representation, it should be understood that, by way of non-limiting example, the blocks, devices, systems, techniques, or methods described herein can be implemented using hardware, software, firmware, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0108] The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as the instructions included in program modules, which are executed in a device on a target real or virtual processor to perform the methods 500-700 referenced above Figures 5 - 7 Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform specific tasks or implement specific abstract data types. In various embodiments, the functions of program modules can be combined or split as needed among program modules. The machine-executable instructions of program modules can be executed within local or distributed devices. In a distributed device, program modules can be located in both local and remote storage media.

[0109] The program code for performing the methods of the present disclosure can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general-purpose computer, a dedicated computer, or other programmable data processing device such that the program code, when executed by the processor or controller, causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0110] In the context of the present disclosure, the computer program code or related data can be carried by any suitable carrier such that a device, apparatus, or processor can perform the various processes and operations as described above. Examples of carriers include signals, computer-readable media, etc.

[0111] A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a computer-readable storage medium would include an electrical connection having one or more wires, a portable computer floppy disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0112] Moreover, although the operations are described in a particular order, this should not be understood as requiring that the operations be performed in the particular order shown or in sequential order, or that all of the illustrated operations be performed to obtain the desired result. In some cases, multitasking and parallel processing may be advantageous. Also, although several specific implementation details are included in the foregoing discussion, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments can 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 separately or in any suitable sub-combination in multiple embodiments.

[0113] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it is to be understood that the disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the above specific features and acts are disclosed as example forms of implementing the claims.

Claims

1. A first device for communication, 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, together with the at least one processor, cause the first device to at least: Receive, from a second device, an indication of at least two candidate code domain resource sets for the first device to send a feedback message for a sidelink transmission between the first device and a third device; And Send the feedback message to the third device on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen-before-talk process; Wherein the first device is caused to send the feedback message by: Determining a first transmission opportunity for sending the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; Performing the listen-before-talk process before the first transmission opportunity, wherein the listen-before-talk process determines that the channel is available for a plurality of consecutive clear channel assessment (CCA) time slots by determining that the measured power of each CCA time slot for idle channel assessment is lower than a preset threshold; According to a successful determination of the listen-before-talk process, sending the feedback message on the first candidate code domain resource set at the first transmission opportunity; According to a failed determination of the listen-before-talk process, determining a second transmission opportunity for sending the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets, the second candidate code domain resource set being different from the first candidate code domain resource set; Performing an additional listen-before-talk process before the second transmission opportunity; And According to a successful determination of the additional listen-before-talk process, sending the feedback message on the second candidate code domain resource set at the second transmission opportunity.

2. The first device according to claim 1, wherein the indication at least includes: A reference sequence for configuring a reference resource set for sending the feedback message, and A set of cyclic shift values for indicating the feedback message.

3. The first device according to claim 1, wherein the first device includes a terminal device in sidelink communication, the second device includes a network device, and the third device includes another terminal device in the sidelink communication.

4. A third device for communication, 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, together with the at least one processor, cause the third device to at least: Receive, from a second device, an indication of at least two candidate code domain resource sets for a first device to send a feedback message for a sidelink transmission between the first device and the third device; And Receive the feedback message from the first device on a target code domain resource set determined from the at least two candidate code domain resource sets by the first device based on a listen-before-talk process, wherein the listen-before-talk process determines that the channel is available for a plurality of consecutive clear channel assessment (CCA) time slots by determining that the measured power of each CCA time slot for idle channel assessment is lower than a preset threshold; wherein the third device is caused to receive the feedback message by: performing the sidelink transmission to the first device; determining a first transmission opportunity for transmitting the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; detecting whether the feedback message is transmitted from the first device on the first candidate code domain resource set at the first transmission opportunity; receiving the feedback message according to a determination that the feedback message transmitted from the first device is detected; determining a second transmission opportunity for transmitting the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets according to a determination that the feedback message transmitted from the first device is not detected, the second candidate code domain resource set being different from the first candidate code domain resource set; and receiving the feedback message according to a determination that the feedback message transmitted from the first device is detected on the second candidate code domain resource set at the second transmission opportunity.

5. The third device according to claim 4, wherein the indication at least includes: a reference sequence for configuring a reference resource set for transmitting the feedback message, and a set of cyclic shift values for indicating the feedback message.

6. The third device according to claim 5, wherein the first device includes a terminal device in sidelink communication, the second device includes a network device, and the third device includes another terminal device in the sidelink communication.

7. A method for communication, performed by a first device, includes: receiving, from a second device, an indication of at least two candidate code domain resource sets for the first device to transmit a feedback message for a sidelink transmission between the first device and a third device; and transmitting the feedback message to the third device on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen-before-talk process; wherein transmitting the feedback message includes: determining a first transmission opportunity for transmitting the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; performing the listen-before-talk process before the first transmission opportunity, wherein the listen-before-talk process determines that the channel is available for a plurality of consecutive clear channel assessment (CCA) time slots by determining that the measured power of each idle CCA time slot is lower than a preset threshold; transmitting the feedback message on the first candidate code domain resource set at the first transmission opportunity according to a determination that the listen-before-talk process is successful; determining a second transmission opportunity for transmitting the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets according to a determination that the listen-before-talk process fails, the second candidate code domain resource set being different from the first candidate code domain resource set; performing another listen-before-talk process before the second transmission opportunity; and transmitting the feedback message on the second candidate code domain resource set at the second transmission opportunity according to a determination that the another listen-before-talk process is successful.

8. The method according to claim 7, wherein the indication at least includes: a reference sequence for configuring a reference resource set for transmitting the feedback message, and a set of cyclic shift values for indicating the feedback message.

9. The method according to claim 7, wherein the first device includes a terminal device in sidelink communication, the second device includes a network device, and the third device includes another terminal device in the sidelink communication.

10. A method for communication, performed by a third device, comprising: receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to transmit a feedback message for a sidelink transmission between the first device and the third device; and receiving, from the first device, the feedback message on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk process, wherein the listen-before-talk process determines that a channel is available for a plurality of consecutive clear channel assessment (CCA) time slots by determining that a measured power of each idle CCA time slot is lower than a preset threshold; wherein receiving the feedback message includes: performing the sidelink transmission to the first device; determining a first transmission opportunity for transmitting the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; detecting whether the feedback message is transmitted from the first device on the first candidate code domain resource set at the first transmission opportunity; receiving the feedback message according to a determination that the feedback message transmitted from the first device is detected; according to a determination that the feedback message transmitted from the first device is not detected, determining a second transmission opportunity for transmitting the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets, the second candidate code domain resource set being different from the first candidate code domain resource set; and receiving the feedback message according to a determination that the feedback message transmitted from the first device is detected on the second candidate code domain resource set at the second transmission opportunity.

11. The method according to claim 10, wherein the indication at least includes: a reference sequence for configuring a reference resource set for transmitting the feedback message, and a set of cyclic shift values for indicating the feedback message.

12. The method according to claim 10, wherein the first device includes a terminal device in sidelink communication, the second device includes a network device, and the third device includes another terminal device in the sidelink communication.

13. A device for communication, comprising: means for receiving, from a second device, an indication of at least two candidate code domain resource sets for a first device to transmit a feedback message for a sidelink transmission between the first device and a third device; and means for transmitting, to the third device, the feedback message on a target code domain resource set determined from the at least two candidate code domain resource sets based on a listen-before-talk process, wherein the means transmits the feedback message by: Determine a first transmission opportunity for transmitting the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; Perform the listen-before-talk process before the first transmission opportunity, wherein the listen-before-talk process determines that the channel is available for a plurality of consecutive clear channel assessment (CCA) time slots by determining that the measured power of each idle channel assessment CCA time slot is lower than a preset threshold; Transmit the feedback message on the first candidate code domain resource set at the first transmission opportunity according to the successful determination of the listen-before-talk process; Determine a second transmission opportunity for transmitting the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets according to the failure determination of the listen-before-talk process, the second candidate code domain resource set being different from the first candidate code domain resource set; Perform an additional listen-before-talk process before the second transmission opportunity; And Transmit the feedback message on the second candidate code domain resource set at the second transmission opportunity according to the successful determination of the additional listen-before-talk process.

14. An apparatus for communication, comprising: Means for receiving an indication of at least two candidate code domain resource sets for a first device to transmit a feedback message for a sidelink transmission between the first device and a third device from a second device; And Means for receiving the feedback message from the first device on a target code domain resource set determined by the first device from the at least two candidate code domain resource sets based on a listen-before-talk process, wherein the listen-before-talk process determines that the channel is available for a plurality of consecutive CCA time slots by determining that the measured power of each idle channel assessment CCA time slot is lower than a preset threshold, and wherein the means receives the feedback message by: Performing the sidelink transmission to the first device; Determining a first transmission opportunity for transmitting the feedback message on a first candidate code domain resource set selected from the at least two candidate code domain resource sets; Detecting whether the feedback message is transmitted from the first device on the first candidate code domain resource set at the first transmission opportunity; Receiving the feedback message according to the determination that the feedback message transmitted from the first device is detected; Determining a second transmission opportunity for transmitting the feedback message on a second candidate code domain resource set selected from the at least two candidate code domain resource sets according to the determination that the feedback message transmitted from the first device is not detected, the second candidate code domain resource set being different from the first candidate code domain resource set; And Receiving the feedback message according to the determination that the feedback message transmitted from the first device is detected on the second candidate code domain resource set at the second transmission opportunity.

15. A non-transitory computer-readable medium, comprising program instructions for causing a device to perform at least the method according to any one of claims 7 to 9.

16. A non-transitory computer-readable medium, comprising program instructions for causing a device to perform at least the method according to any one of claims 10 to 12.

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