Method and system for performing hybrid automatic repeat request feedback

Abstract

The present invention provides a system and a method comprising: receiving configuration information for a physical side link feedback channel (PSFCH) resource by a first user equipment (UE); performing a first listen-before-speak (LBT) sensing of a first PSFCH resource in response to receiving the information; and determining that the first LBT sensing has failed, and in response, transmitting a signal via a second PSFCH resource of the PSFCH resource.

Description

Technical Field

[0001] This disclosure generally relates to unauthorized sidelink communication in New Radio (NR). More specifically, the subject matter disclosed herein relates to improvements in systems and methods for performing HARQ feedback for unauthorized sidelink communication.

[0002] This application claims the benefit of priority of U.S. Provisional Patent Application No. 63 / 276,951, filed on November 8, 2021, the disclosure of which is incorporated herein by reference in its entirety as if fully set forth herein.

Background Art

[0003] Up to Rel-17 in 5G NR, the 3GPP sidelink specifications relate to public safety and the vehicle-to-vehicle (V2V) band via the intelligent transport system (ITS). However, in a recently published white paper such as 3GPP TR 22.842, December 2019, "Study on Network Controlled Interactive Service in the 5G System", the entire content of which is incorporated herein by reference, interactive services such as interactive games, data sharing between various terminals such as mobile phones, virtual reality (VR) / artificial reality (AR) devices, and robots are being considered for sidelink use. Many of these interactive services occur locally and can benefit from the integration of cellular communication and sidelink communication. For network controlled interactive services (NCIS) such as those described in 3GPP TR 22.842, the data path and the control path can be deployed on either one of the cellular link (e.g., Uu link) or the sidelink (e.g., PC5 link). FIG. 1 shows an example of such a system architecture, where most of the control plane is transmitted via the network, while most of the data and some control information are transmitted on the sidelink.

[0004] The unlicensed bands in the 5 / 6 GHz band and 60 GHz band provide relatively large additional bandwidth and flexibility, enabling sidelink data transmission. Therefore, in future releases such as Rel-18, 3GPP may standardize sidelink communication in unlicensed bands. However, in order to legally enable proximity services (ProSe) in unlicensed bands, existing and / or future regulatory requirements must be met.

SUMMARY

[0005] One aspect relates to a method in which hybrid automatic repeat request (HARQ) feedback is sent from one user equipment (UE) to another UE. For example, in Rel-17 and prior, the UE transmits a data packet for a specified resource to the receiving UE to transmit an acknowledgement / negative-acknowledge (ACK / NAK) feedback. However, in unlicensed spectrum, the receiving UE that transmits the ACK / NACK needs to access certain channels to send the ACK / NACK feedback. Therefore, the existing Rel 16 / 17 procedures for sidelink ACK / NAK feedback may not be applied in the same way.

[0006] Accordingly, embodiments of the present disclosure relate to a method for sending HARQ in 5G NR SL unlicensed spectrum.

[0007] According to an embodiment of the present disclosure, a method may include: receiving, by a first user equipment (UE), configuration information for a physical sidelink feedback channel (PSFCH) resource; performing, by the first UE in response to the receiving, a first listen-before-talk (LBT) sensing of a first PSFCH resource of the PSFCH resources; and determining that the first LBT sensing fails, and in response, transmitting a signal via a second PSFCH resource of the PSFCH resources.

[0008] The method may further include determining, by the first UE, that a second UE will receive the signal from the first UE.

[0009] The signal may be a hybrid automatic repeat request (HARQ) feedback signal.

[0010] The first PSFCH resource and the second PSFCH resource are mapped to a single physical sidelink shared data channel (PSSCH).

[0011] The method may further include determining that one or more short control exemptions are available, and in response to determining that one or more short control exemptions are available, transmitting a signal via the second PSFCH resource without performing a second LBT sensing on the second PSFCH resource.

[0012] The method may further include performing, by a first UE, a second LBT sensing on a second PSFCH resource in response to determining that a first LBT sensing on the first PSFCH resource fails.

[0013] The second LBT sensing may be performed before transmitting a signal via the second PSFCH.

[0014] Transmitting a signal via the second PSFCH resource may be performed in response to determining that an LBT sensing for the second PSFCH resource is successful.

[0015] The signal may be performed during sidelink communication via an unlicensed band.

[0016] During a channel occupancy time (COT) shared by a first UE and a second UE for the second PSFCH resource, the method further includes transmitting, by the first UE, a signal on the shared COT.

[0017] Transmitting a signal via the second PSFCH resource may be performed without performing an LBT sensing on the second PSFCH resource.

[0018] The method may further include transmitting a signal on a sideline control information (SCI) channel in response to determining that the first LBT sensing fails.

[0019] According to another embodiment of the present disclosure, a system may include a first user equipment (UE). The UE may include: a radio; and a processing circuit, wherein the processing circuit is configured to: receive configuration information for a physical sidelink feedback channel (PSFCH) resource; perform a first listen-before-talk (LBT) sensing for a first PSFCH resource of the PSFCH resource in response to receiving the configuration information; and determine that the first LBT sensing fails, and in response, transmit a signal via a second PSFCH resource of the PSFCH resource.

[0020] The processing circuitry may be further configured to determine that a second UE will receive a signal from a first UE.

[0021] The signal may be a Hybrid Automatic Repeat reQuest (HARQ) feedback signal.

[0022] A first Physical Sidelink Feedback Channel (PSFCH) resource and a second PSFCH resource are mapped to a single Physical Sidelink Shared Channel (PSSCH).

[0023] The processing circuitry may be further configured to determine that one or more short control exemptions are available, and in response to determining that one or more short control exemptions are available, transmit a signal via the second PSFCH resource without performing a second Listen-Before-Talk (LBT) sensing on the second PSFCH resource.

[0024] In response to determining that a first LBT sensing on a first PSFCH resource fails, the processing circuitry is further configured to perform a second LBT sensing on a second PSFCH resource.

[0025] The processing circuitry may be further configured to perform a second LBT sensing before transmitting a signal via the second PSFCH.

[0026] In response to determining that the LBT sensing for the second PSFCH resource is successful, the processing circuitry may be further configured to transmit a signal via the second PSFCH resource.

[0027] The signal may be performed during sidelink communication via an unlicensed band.

[0028] The second PSFCH resource is within a Channel Occupation Time (COT) shared by a first UE and a second UE, and the processing circuitry is further configured to transmit a signal on the shared COT.

[0029] Transmitting a signal via the second PSFCH resource may be performed without performing an LBT sensing on the second PSFCH resource.

[0030] In response to determining that the first LBT sensing fails, the processing circuitry is further configured to transmit a signal on a Sidelink Control Information (SCI) channel.

Embodiments

[0032] In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, those of ordinary skill in the art will understand that the disclosed aspects may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to obscure the subject matter disclosed herein.

[0033] Throughout this specification, references to "one embodiment" or "an embodiment" mean that the particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment disclosed herein. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "according to one embodiment" (or other phrases with similar meaning) at various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In this regard, as used herein, the term "exemplary" means "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" should not be construed as necessarily being preferred or better than other embodiments. Additionally, the particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Moreover, depending on the context of the discussion herein, singular terms can include the corresponding plural forms, and plural terms can include the corresponding singular forms. Similarly, hyphenated terms (e.g., "two-dimensional," "pre-determined," "pixel-specific," etc.) can be used interchangeably with their corresponding non-hyphenated versions (e.g., "two dimensional," "predetermined," "pixel specific," etc.), and capitalized terms (e.g., "Counter Clock," "Row Select," "PIXOUT," etc.) can be used interchangeably with their corresponding non-capitalized versions (e.g., "counter clock," "row select," "pixout," etc.). Such occasional interchangeability should not be regarded as inconsistent with each other.

[0034] Moreover, depending on the context of the discussion herein, singular terms can include the corresponding plural forms, and plural terms can include the corresponding singular forms. It should be further noted that the various diagrams (including component diagrams) illustrated and discussed herein are for illustrative purposes only and are not drawn to scale. For example, for clarity, the dimensions of some components may be enlarged relative to other components. Additionally, where appropriate, reference numerals have been repeated in the figures to indicate corresponding and / or similar elements.

[0035] The terms used herein are for the purpose of describing some example embodiments only and are not intended to limit the claimed subject matter. As used herein, unless the context clearly indicates otherwise, the singular forms "a / an" and "the" are also intended to include the plural forms. It should be further understood that the term "comprises / comprising", when used in this specification, specifies the presence of the stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0036] It should be understood that when an element or layer is referred to as being on another element or layer, "connected to" or "coupled to" another element or layer, the element or layer can be directly on the other element or layer, directly connected to or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when a component is referred to as being "directly on" another component or layer, "directly connected to" or "directly coupled to" another component or layer, no intervening components or layers are present. The same reference numerals throughout the text refer to the same elements. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] The terms "first", "second", etc. as used herein are labels for the nouns that precede them and do not imply any type of ordering (e.g., spatial, temporal, logical, etc.), unless so specifically defined. In addition, the same reference numerals may be used throughout two or more figures to refer to parts, components, blocks, circuits, units, or modules having the same or similar functionality. However, this usage is for simplicity of illustration and ease of discussion only; it does not imply that the construction or architectural details of such components or units are the same across all embodiments, or that such commonly referred to parts / modules are the only way to implement some of the example embodiments disclosed herein.

[0038] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter belongs. It should be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless specifically so defined. As used herein, the term "module" refers to any combination of software, firmware, and / or hardware configured to provide the functionality described herein in connection with the module. For example, the software can be embodied as a software suite, code, and / or instruction set or instructions, and the term "hardware" as used in any of the embodiments described herein can include, alone or in any combination, for example, assemblies, hardwired circuits, programmable circuits, state machine circuits, and / or firmware that stores instructions executed by the programmable circuits. The modules can be embodied, jointly or individually, as circuitry that forms part of a larger system, such as, but not limited to, an integrated circuit (IC), a system on-a-chip (SoC), an assembly, etc.

[0040] The physical sidelink feedback channel is a physical channel in a 5G NR system for transmitting feedback information from a receiving (Rx) UE to a transmitting (Tx) UE. In some embodiments, it can be used for unicast and / or multicast option 1 and unicast and / or multicast option 2. In the case of unicast and multicast option 2, the PSFCH is used to transmit ACK / NACK, and in the case of multicast option 1, the PSFCH only carries NACK. For sidelink feedback, a sequence-based PSFCH format (e.g., PSFCH format 0) with one symbol (excluding the automatic gain control (AGC) training period) is supported.

[0041] In PSFCH format 0, the ACK / NACK bits can be transmitted via two Zadoff-Chu (ZC) sequences of length 12 (e.g., the same root but different cyclic shifts), where the presence of one sequence can indicate ACK and the presence of the other sequence can indicate NACK. Thus, these sequences can be used in a mutually exclusive manner. Therefore, since the sequences are used to transmit ACK / NACK to the Tx UE, feedback from multiple UEs can be multiplexed on the same physical resource block (PRB). Thus, in some embodiments, up to 6 ACK / NACKs from 6 UEs can be multiplexed on the same PRB (e.g., 12 subcarriers) by using different cyclic shifts. This number can be determined based on the resource pool configuration (such as numMuxCSPair). In this case, each UE can specify the same root sequence but two cyclic shifts (e.g., one for ACK and the other for NACK).

[0042] In some embodiments, the case attributable to multicast option 2 may use a format based on code division multiplexing (CDM), where multiple ACK / NACK feedbacks are expected from different UEs for each physical sidelink shared control channel (PSSCH) transmission. For multicast option 2, the ACK / NACK from different UEs may be transmitted on the same PRB by allocating two different sequences for each UE to be used for its ACK / NACK transmission. In this case, the sequences and PRBs used by each UE may depend on a unique ID. On the other hand, for multicast option 1, only NACK is required, and thus the cyclic shift corresponding to the ACK message may not be used, and all UEs included in the multicast may use the same sequence and PRB for the NACK.

[0043] In some embodiments, to support AGC, the resource elements for the PSFCH may be replicated in the immediately preceding orthogonal frequency division multiplexing (OFDM) symbol. Thus, two consecutive symbols may always be used for the transmission of PSFCH format 0. Subsequently, the first symbol may be used for AGC training after the Tx / Rx switch. In addition, as illustrated in FIG. 2, at least one symbol may be used for the gap after PSSCH transmission, and another symbol may be used after PSFCH transmission to allow for the Tx / Rx switch.

[0044] For a period of N time slots including the PSFCH resources, three values may be supported (e.g., N = 1, N = 2, and N = 4). These values define the periodicity of the PSFCH resources and subsequently define their associated burden. For a PSSCH transmission having the last symbol in time slot n, when the corresponding HARQ feedback is to be transmitted, it is expected to be in time slot n + a, where a is the smallest integer greater than or equal to K logical time slots (e.g., time slots within the PSSCH resource pool), provided that time slot n + a contains the PSFCH resources and K is equal to 2 or 3.

[0045] According to Rel-16 sidelink in TS 38.213, the UE may be scheduled to receive the PSSCH in one or more subchannels from multiple subchannels and transmit the sidelink control information (SCI) format of the PSFCH with HARQ-ACK information in response to the PSSCH reception. The UE provides HARQ-ACK information including ACK or NACK or only NACK.

[0046] The UE can be provided by sl-PSFCH-Period-r16 which corresponds to the number of time slots in the resource pool for the period of the PSFCH transmission time resource. If the number is zero, the PSFCH transmission from the UE in the resource pool can be disabled.

[0047] The UE expects that if, then the time slot) has a PSFCH transmission time resource, where is defined in TS 38.214, and according to TS 38.214, is the number of time slots belonging to the resource pool within 10240 milliseconds, and is provided by sl-PSFCH-Period-r16.

[0048] The UE can be indicated by the higher layer not to transmit the PSFCH in response to the PSSCH reception according to TS 38.321.

[0049] If the UE receives the PSSCH in the resource pool, and according to TS 38.212, the HARQ feedback enable / disable indicator field in the associated SCI format 2-A or SCI format 2-B has a value of 1, then the UE can provide HARQ-ACK information in the PSFCH transmission in the resource pool. The UE transmits the PSFCH in the first time slot, the first time slot contains the PSFCH resource, and is at least the number of time slots provided by sl-MinTimeGapPSFCH-r16 after the last time slot of the PSSCH reception in the resource pool.

[0050] The UE can be provided by sl-PSFCH-RB-Set-r16 for the set of PRBs in the resource pool for the PSFCH transmission in the resource pool. For the number of subchannels for the resource pool provided by sl-NumSubchannel and the number of PSSCH time slots less than or equal to associated with the PSFCH time slot, the UE allocates the PRBs from the PRBs to the time slots in the PSSCH time slots associated with the PSSCH time slot and the subchannels, where,,, and the allocation starts in the increasing order of and continues in the increasing order of. The UE expects to be a multiple of.

[0051] The UE can determine that the number of PSFCH resources available for multiplexing HARQ-ACK information in the PSFCH transmission is, where is the number of cyclic shift pairs for the resource pool, and based on the indication of the higher layer: and the PRB is associated with the starting subchannel of the corresponding PSSCH; and and the PRB is associated with one or more subchannels from the subchannels of the corresponding PSSCH.

[0052] The PSFCH resources can be indexed first from the PRB indices in the increasing order of the PRB indices, and then from the cyclic shift pair indices in the increasing order of the cyclic shift pair indices.

[0053] The UE may respond to the PSSCH reception to determine that the index of the PSFCH resource for PSFCH transmission is, where is the physical layer source ID provided by the SCI format 2-A or SCI format 2-B according to TS 38.212 that schedules the PSSCH reception, and is the identifier of the PSSCH received by the UE, as indicated by the higher layer. If the UE detects an SCI format 2-A with a casting indicator field value of "01"; otherwise, it is 0.

[0054] The UE may use Table 1 to obtain the cyclic shift pair index corresponding to the PSFCH resource index and the value of for calculating the cyclic shift according to TS 38.211. Cyclic shift pair index 0 Cyclic shift pair index 1 Cyclic shift pair index 2 Cyclic shift pair index 3 Cyclic shift pair index 4 Cyclic shift pair index 5 1 0 - - - - - 2 0 3 - - - - 3 0 2 4 - - - 6 0 1 2 3 4 5 Table 1

[0055] If the UE detects an SCI format 2-A with a casting type indicator field value of "01" or "10", as in Table 2, or if the UE detects an SCI format 2-B or SCI format 2-A with a casting type indicator field value of "11", as in Table 3, the UE can determine the value for calculating the cyclic shift according to TS 38.211. The UE can apply one of the cyclic shifts from the cyclic shift pair according to TS 38.211 to the sequence for PSSCH transmission. HARQ-ACK value 0 (NACK) 1 (ACK) Sequence cyclic shift 0 6 Table 2 HARQ-ACK value 0 (NACK) 1 (ACK) Sequence cyclic shift 0 N / A Table 3

[0056] In some embodiments, NR Vehicle-to-X (V2X) supports ACK / NACK feedback for SL HARQ feedback in unicast. That is, if the Rx UE has successfully decoded the transport block (TB) carried in the PSSCH, the Rx UE sends an ACK; or if the Rx UE has not decoded the TB after decoding the first-stage SCI, the Rx UE sends a NACK. For multicast, two options (e.g., Option 1 and Option 2) can support SL HARQ feedback in NR V2X.

[0057] For Option 1, if the Rx UE has not successfully decoded the TB (after decoding the first-stage SCI) and if the relative distance from the Rx UE to the Tx UE (referred to as the TxRx distance) is less than or equal to the required communication range (e.g., as indicated in the second-stage SCI), the Rx UE transmits a NACK. Otherwise, the Rx UE does not transmit any HARQ feedback. Since the HARQ feedback for this option consists only of NACKs, Option 1 can be referred to as NACK-only feedback. Thus, in Option 1, the Rx UE does not transmit HARQ feedback because it has successfully decoded the TB or because it is outside the minimum required communication range (even if it has not successfully decoded the TB).

[0058] In some embodiments, Option 2 for multicast supports ACK / NACK feedback from all Rx UEs. That is, if an Rx UE has successfully decoded the TB, the Rx UE sends an ACK; or if the Rx UE has not decoded the TB after decoding the first-stage SCI, the Rx UE sends a NACK. For either unicast or multicast options, if the Rx UE has not decoded the first-stage SCI, the Rx UE does not send a reply. In the Option 1 case, the transmitting Rx UEs share resources for sending only NACK feedback, while in the Option 2 case, each Rx UE sends its ACK / NACK feedback on independent resources. Therefore, in the Option 1 case, the Tx UE cannot identify the Rx UE that sends a NACK. If the Tx UE receives at least one NACK for Option 1, the Tx UE realizes that at least one Rx UE within the required communication range has not correctly decoded the transmission. In addition, if the Tx UE does not receive a reply in the Option 1 case, it may not be able to distinguish whether the Rx UEs within the required communication range have successfully received the transmission or some have not successfully decoded the corresponding first-stage SCI. On the other hand, the Tx UE can distinguish the HARQ feedback of the Rx UEs in the Option 2 case. This enables the Tx UE to perform retransmissions suitable for specific Rx UEs. Therefore, in the Option 2 case, if the Tx UE does not receive a reply for the feedback resource corresponding to a given Rx UE, the Tx UE can realize that the Rx UE has not successfully decoded the corresponding first-stage SCI. Therefore, Option 2 achieves higher reliability for transmission. However, the advantage of Option 2 over Option 1 may come at the cost of more resources required for multicast HARQ feedback.

[0059] In NR V2X, the use of HARQ feedback and the choice of whether to use Option 1 or Option 2 for multicast HARQ feedback can be determined based on UE implementation. For multicast communication, the Tx UE indicates in the second-stage SCI whether only NACK feedback (Option 1) or ACK / NACK feedback (Option 2) should be used. Only NACK feedback can be considered for multicast services where the information provided may not be so relevant to Rx UEs outside the communication range. For multicast Option 1, the TxRx distance can be obtained at the Rx UE based on the location of the Tx UE. This location can be indicated by the area ID of the Tx UE carried in the second-stage SCI.

[0060] The TxRx distance can be derived at the Rx UE based on its own position and the center of the closest area to the indicated area ID. In some embodiments, the HARQ feedback of the TB sent on the PSSCH in the resource pool can be carried on the PSFCH in the same resource pool. To deactivate the HARQ feedback for all SL transmissions in the resource pool, resources not used for the PSFCH can be configured within the resource pool. The resources for the PSFCH can be configured or pre-configured periodically with a time slot period of N = 1, 2, or 4. That is, the PSCCH / PSSCH time slots with PSFCH symbols are available for every N time slots within the resource pool. Therefore, even if the resources for the PSFCH are configured or pre-configured, the stage 2 SCI can also indicate whether to enable the HARQ feedback for the TB sent in a given PSSCH.

[0061] In some embodiments, one PRB can be used for PSFCH transmission. In one PRB, NR V2X supports CDM between the PSFCH transmissions of multiple Rx UEs. Therefore, in the case of CDM, multiple transmissions share the same frequency resource simultaneously. Therefore, the transmissions can use signals with low cross-correlation (e.g., orthogonal). Therefore, this feature allows the receiver to distinguish between uncorrelated transmission signals sent on the same time and frequency resources. Signals with low cross-correlation can be generated from periodic roots or basic sequences with extremely high auto-correlation characteristics.

[0062] In some embodiments, a set of uncorrelated signals for CDM can be generated from a cyclically shifted version of the base sequence. Therefore, the base sequence for the PSFCH can be configured in NR V2X according to the resource pool, and it can correspond to the Zadoff-Chu sequence based on the format of the physical uplink control channel (PUCCH) in Rel 15 NR Uu. In the PRB for the PSFCH, the transmissions that can be multiplexed with CDM can correspond to the HARQ feedback from several Rx UEs. Therefore, CDM can also be used to distinguish the ACK or NACK feedback from the Rx UEs in the same PRB. Therefore, a pair of cyclic shifts (within the PRB) can be used to distinguish the ACK or NACK from the Rx UEs. The cyclic shift corresponding to ACK is not defined in the case of only NACK feedback (option 1) for multicast. Therefore, each PSFCH in NR V2X can be mapped to a time resource (PSFCH symbol), a frequency resource (one PRB), and a code resource (one of the cyclic shift pairs).

[0063] Listen-before-talk (LBT) is a method that requires the UE to listen for a response before utilizing a channel. For example, 3GPP has specified four LBT categories for NR-unlicensed single-channel access: Category 1 (Cat 1 LBT): Immediate transmission after a short switching gap of 16 microseconds. Category 2 (Cat 2 LBT): LBT without random backoff, where the CCA period is deterministic (e.g., fixed to 25 microseconds). Category 3 (Cat-3 LBT): LBT with random backoff having a contention window of fixed size, where the extended CCA period is drawn as a random number within the fixed contention window. Category 4 (Cat-4 LBT): LBT with random backoff having a contention window of variable size, where the extended CCA duration is drawn as a random number within the contention window, the size of which can vary dynamically based on the channel.

[0064] After successful LBT, the device can access the channel for up to the duration of the MCOT (e.g., 9 milliseconds in the 60 GHz band). Due to the digital scheme, small time slots, and flexible slot structure, the NR frame structure inherently allows NR unlicensed (NR-U) to transmit and receive more efficiently compared to LTE in unlicensed spectrum technologies. For example, the Channel Occupancy Time (COT) can be shared between the gNB and its UE to achieve higher spectral efficiency and faster response in two-way transmission.

[0065] In some embodiments, different categories can be used for different transmissions in the COT and for various channels and / or signals to be transmitted. Thus, as in license assisted access (LAA), Cat 4 LBT can be used by the gNB or UE to initiate the COT for data transmission, while the gNB can use Cat 2 LBT for specific signaling, such as sounding reference signals. In some embodiments, the rules for sharing the COT have also been defined for NR-U. For the gNB initiating the COT, if there is a gap of less than 16 microseconds between downlink (DL) and uplink (UL) transmissions, the responding device is allowed to transmit without performing a CCA check (e.g., Cat 1 LBT). For a gap greater than 16 microseconds but less than 25 microseconds, within the COT, only short sensing (e.g., Cat 2 LBT) is required at the responding device. Otherwise, if the gap is longer than 25 microseconds, a regular LBT (e.g., Cat 4 LBT for data) must be completed at the responding device. Additionally, unlike LAA that supports a single DL / UL handover point within the COT, NR-U supports multiple DL / UL handover points within the COT.

[0066] As provided in section 4.2.7.3.3 of chapter 4 of ETSI EN 301 V2.1.1 regarding the short control signaling transmission status of frame-based devices and load-based devices in general, the regulation on short control signaling may have short control signaling transmission on the operating channel, with the limitation that such transmissions comply with the requirements in item 4.2.7.3.3. The adaptive device may not need to implement short control signaling transmission. Short control signaling transmission is a transmission used by the device to send management and control frames without the need for a presence sensing channel for other signals. The use of short control signaling transmission is restricted to an observation period of 50 milliseconds. The number of short control signaling transmissions performed by the device should be equal to or less than 50, and the total duration of the device's short control signaling transmission within the observation period should be less than two 500 microseconds.

[0067] Embodiments of the present disclosure relate to the support of sidelink on unlicensed spectrum for both mode 1 and mode 2, where the operation of mode 1 may be restricted to licensed spectrum. The embodiments also relate to an evaluation method for sidelink operation on unlicensed spectrum, a sidelink channel access mechanism for unlicensed spectrum based on regional regulation requirements and using the existing channel success process from NR-U as a starting point by reusing the Rel-16 resource allocation mechanism as much as possible, changes in the NR sidelink physical channel structure, and procedures for operating on unlicensed spectrum without specifically optimizing existing NR SL features. The unlicensed spectrum bands in FR1 are 5 GHz and 6 GHz, and the unlicensed spectrum in FR2 is not specifically optimized.

[0068] Therefore, in NR SL communication technology, at least HARQ ACK / NACK is sent on the PSFCH to the source UE (e.g., the Tx UE and also referred to as UE A in this document). The PSFCH is sent on some time slots after data transmission and a symbol protection time. However, in unlicensed spectrum, the Rx UE needs to perform LBT before accessing the PSFCH. But if the LBT fails, the Rx UE cannot send ACK / NACK on the PSFCH.

[0069] Figure 3 is an illustration of an example SL HARQ in an unlicensed band, where UE A communicates with UE B. As shown, UE B must perform LBT during the indication interval before it can access the PSFCH.

[0070] According to the Rel-16 NR SL design, there is a one-to-one mapping between PSSCH transmission and PSFCH transmission. Therefore, if LBT fails before PSFCH transmission, UE B does not have another opportunity to provide HARQ ACK / NACK to the transmitter. Although the transmitter (e.g., UE A) can assume HARQ NACK when it does not receive anything on the PSFCH, this is very inefficient and significantly reduces throughput. Therefore, there is a need to develop a new HARQ feedback procedure in the unlicensed spectrum. Accordingly, various embodiments of the present disclosure provide techniques to improve the efficiency of NR SL HARQ ACK / NACK transmission via the unlicensed spectrum, e.g., in the unlicensed spectrum FR1 of NR SL. Thus, more reliable HARQ feedback can be provided to the source UE (e.g., Tx UE or UE A).

[0071] According to an embodiment of the present disclosure, multiple resources (e.g., two PSFCH resources) may be provided instead of providing one PSFCH resource for ACK / NAK feedback. The Rx UE that sends the ACK / NACK feedback may first attempt to access the channel using LBT for the first PSFCH resource. If access is successfully obtained, the Rx UE may send the HARQ feedback on this first PSFCH resource. If access is not successfully obtained, the Rx UE may perform LBT again and attempt to access the second subsequent PSFCH resource, and so on, continuing if this is not successful again. For the purposes of the present disclosure, two PSFCH resources are used to describe the technique according to this embodiment. However, it should be noted that these techniques are not limited to only two resources, but there may be more than two PSFCH resources suitable, in which case a similar process may be followed for each subsequent available PSFCH resource.

[0072] FIG. 4 is a flowchart of a procedure for providing HARQ feedback ACK / NACK according to various embodiments of the present disclosure. At step 401, the Rx UE first obtains a HARQ feedback configuration. The configuration may include information such as how and when to send HARQ feedback. Thus, according to an embodiment of the present disclosure, the configuration may include at least two PSFCH resources. The PSFCH configuration of the first (primary) PSFCH resource may indicate where to send the HARQ feedback for the resource pool, and the PSFCH configuration of the second (secondary) PSFCH resource and / or subsequent PSFCH resources may indicate where to send the HARQ feedback if the first PSFCH resource is not available (e.g., due to LBT failure). In some embodiments, the HARQ feedback configuration may also include any other information according to the Rel-16 / 17 procedure, which will not be described in detail here. This information may be sent using RRC signaling, MAC CE signaling, physical layer signaling SCI, etc. In some embodiments, the configuration information may already be pre-configured, e.g., during the manufacturing of the UE. But in some embodiments, the Tx UE may also obtain a HARQ feedback configuration that contains the same information as that obtained by the Rx UE as described above.

[0073] At step 402, the Rx UE monitors the PSCCH and receives an indication that the Rx UE will receive a data packet from the Tx UE, which will require sending HARQ feedback using the PSFCH resource according to the Rel-16 / 17 procedure.

[0074] At step 403, LBT is performed before the first PSFCH resource. Based on the data packet dispatch, the Rx UE determines which resources it should use to send the HARQ feedback on the first (primary) PSFCH resource, and then determines where to perform LBT. The Rx UE may perform Cat 4 LBT in the gap symbol before the first PSFCH transmission.

[0075] At step 404, the Rx UE performs LBT and determines whether LBT is successfully completed in time. In some embodiments, the acceptable time length may be determined by the configuration from step 401. For example, the time may be a threshold time limit within which the LBT is performed, and if the LBT is successfully completed within that time limit, the LBT may be considered successful.

[0076] If the LBT is successfully completed in a timely manner, then at step 405, the Rx UE then transmits HARQ feedback on the first PSFCH resource. On the other hand, if the LBT is not successfully completed in a timely manner, then at step 406, the Rx UE determines other resources on the secondary PSFCH resource and then determines where to perform the LBT. The Rx UE can then perform, for example, Cat 4 LBT in the gap symbol before the first PSFCH transmission, and if the LBT is successfully completed in a timely manner on the second PSFCH resource, the Rx UE can again determine at step 407. If the LBT is successfully completed in a timely manner, then at step 408, the HARQ feedback can be transmitted to the Tx UE on the second PSFCH resource. On the other hand, if the second LBT is not successful (e.g., the second LBT fails), then at step 409, the Rx UE does not transmit anything on the PSFCH. Therefore, the Tx UE on the other side of the link (i.e., the source UE) assumes that the data packet transmission has failed. If there are additional PSFCH resources, steps 406 to 409 can be repeated again until the LBT is successfully performed and then the HARQ feedback can be transmitted to the Tx UE on the PSFCH. Therefore, by providing multiple PSFCH resources for HARQ feedback configuration, the probability of successful LBT is increased, and thus the probability of transmitting the HARQ feedback to the Tx UE is increased.

[0077] FIG. 5 is an illustration of an example of an SL PSSCH and PSFCH resource mapping process for type 2 multicast including two Rx UEs. One aspect of an embodiment of the present disclosure is directed to mapping one HARQ feedback to multiple PSFCH times / resources. Thus, when only one PSFCH time is mapped to one PSSCH transmission, there is a one-to-one mapping between the PSSCH resource and the PSFCH time / resource, as shown in FIG. 5. When two PSFCH times / resources are possible, a one-to-two mapping can be obtained by extending the one-to-one mapping of a single PSFCH in a direct manner. In the present disclosure, "mapping" the PSSCH resource to the PSFCH resource can be defined as aligning or allocating the PSSCH resource to the corresponding PSFCH resource so that other UEs will not select the same PSFCH resource that will cause a conflict. Therefore, each UE can find the corresponding PSFCH resource for a given PSSCH resource so that data transmission can be performed.

[0078] In particular, FIG. 5 illustrates the frequency and time resource allocation for Rel-16 SL PSSCH and PSFCH resource mapping for type 2 multicast with at most two Rx UEs, where the vertical grid corresponds to the frequency resources in terms of sub-channels and the horizontal grid corresponds to the time resources in terms of time slots. The PSFCH moment periodicity is configurable as N. According to the Rel-16 PSFCH configuration mapping, each of the indexed PSSCH transmissions from 1 to 12 can be respectively mapped to one corresponding PSFCH resource that includes two PRBs indexed in the grid. For example, PSSCH 7 has two corresponding indexed PRBs of the PSFCH resource, and each PRB is allocated for one of the two Rx UEs.

[0079] FIG. 6 is an illustration of an example of SL PSSCH and PSFCH resource mapping for type 2 multicast with one Rx UE, where the vertical grid corresponds to the frequency resources in terms of sub-channels, and the horizontal grid corresponds to the time resources in terms of time slots. The PSFCH moment periodicity is configurable as N. Thus, each of the indexed PSSCH transmissions from 1 to 12 can be respectively mapped to two corresponding PSFCH resources that include one PRB indexed in one of the two PSFCH moments. For example, PSSCH 7 has two corresponding PRBs of the PSFCH resource in the two PSFCH moments, and each of the PSFCH resources is allocated for the same Rx UE to cope with the case of LBT performance failure.

[0080] More specifically, embodiments of the present disclosure relate to configuring "1" to "m" mappings between one PSSCH transmission and m candidate PSFCH transmissions in "m" consecutive PSFCH moments as illustrated in FIG. 7.

[0081] FIG. 7 is an illustration of an example of SL PSSCH and PSFCH resource mapping for type 2 multicast including m Rx UEs. Thus, the mapping is configured such that if LBT is successful, the receiver UE sends ACK / NACK to the Tx UE. Otherwise, the Rx UE enters the backoff procedure of the Cat 4 LBT procedure and does not send ACK / NACK to the Tx Ue. The Rx UE can then try Cat 4 LBT again, and if LBT is successful this time, it sends ACK / NACK in the next PSFCH moment. Otherwise, the Rx UE enters the backoff procedure again. Thus, the Rx UE can continue to try Cat 4 LBT again and try again in the next m candidate PSFCH moments. If LBT is successful at the Rx UE in one candidate PSFCH moment, the Rx UE sends ACK / NACK to the Tx UE and no longer needs to try the remaining candidate PSFCH moments.

[0082] In some cases, even at the current PFSCH time, the Rx UE may not complete the fallback procedure for the previous PFSCH time. In this case, the Rx UE may continue to execute the fallback procedure for the previous PSFCH time instead of performing a new Cat 4 LBT at the current PSFCH time. Therefore, the design of SL-U HARQ can be enabled by configuring "1" to "m" mappings between one PSSCH transmission and m candidate PSFCH transmissions in "m" consecutive PSFCH times of NAND.

[0083] In some embodiments, the UE may be provided by a set of sl-PSFCH-RB-Set-r16 of PRBs in the resource pool for PSFCH transmission in the PRBs of the resource pool. For the number of subchannels of the resource pool provided by sl-NumSubchannel and the number of PSSCH timeslots less than or equal to associated with the first PSFCH timeslot, the UE allocates the PRBs from the PRBs to the timeslots in the PSSCH timeslots associated with the PSSCH timeslot and the subchannel, where,,, and the allocation starts in ascending order of and continues in ascending order of. The UE expects to be a multiple of.

[0084] In the second PSFCH timeslot after the first PSFCH timeslot, the UE allocates the PRBs from the PRBs to the timeslots in the PSSCH timeslots associated with the PSSCH timeslot and the subchannel, where,,, and the allocation starts in ascending order of and continues in ascending order of. The UE expects to be a multiple of.

[0085] In the Kth PSFCH timeslot after the first PSFCH timeslot, the UE may also allocate, where.

[0086] In some embodiments, in the case of multicast option 2, especially when PSFCH periodicity > 1, the PSFCH resources may be restricted by the resource pool configuration. For example, assuming there are PSFCH resources per subchannel / timeslot currently, the number of UEs (e.g., the maximum number of UEs) that can be adjusted by multicast option 2 can be reduced from N to N / K. According to another embodiment, a difference can be imposed opportunistically. For example, the second or third PSFCH repetition scenario can start in the second PRB in the first subchannel occupied by unicast transmission because, in the case of multicast option 2, these resources are not utilized by default. In yet another embodiment, the number of receivers (e.g., the maximum number of receivers) in multicast option 2 can be restricted or reduced by the resource pool configuration so that there are sufficient PSFCH resources to support multicast option 2.

[0087] According to another embodiment of the present disclosure, short control exemptions can be utilized to send HARQ feedback. As described above, if the LBT of the Rx UE fails, the HARQ ACK / NACK can be sent by utilizing the short control exemption without LBT.

[0088] More specifically, the mapping of "1" to "m" between one PSSCH transmission and m candidate PSFCH transmissions among "m" consecutive PSFCH moments can be supplemented by p short control exemption PSFCH transmission attempts of a given Rx UE for every X total SL transmissions, including PSSCH transmission, PSCCH transmission, PSBCH transmission, and PSFCH transmission.

[0089] In some embodiments, the second possible limit may be that the number of short control signaling transmissions that can be performed by the Rx UE within an observation period of 50 milliseconds is equal to or less than 50, and the total duration of the Rx UE short control signaling transmissions within the observation period is less than 50 milliseconds. Therefore, the Rx UE can first attempt to send the HARQ ACK / NACK via m candidate PSFCH moments by performing LBT channel access. If the LBT for all available m PSFCH moments is not successful, the Rx UE can then check whether any remaining short control exemption PSFCH transmission opportunities are reserved. In other words, p short control exemption transmissions for every X total SL transmissions at the Rx UE or as described above under the second possible limit. If any short control exemption PSFCH transmission opportunities are reserved, if the priority of the corresponding TB transmitted in the PSSCH is greater than a predefined threshold value, the short control exemption can be utilized to transmit the HARQ ACK / NACK at m + 1 PSFCH moments without LBT. In some embodiments, the Rx UE can apply the short control signaling exemption at the PSFCH moment before the m PSFCH moments to transmit the HARQ ACK / NACK, so as to maintain the delay budget of a given TB with a strict delay requirement.

[0090] In some embodiments, the methods described above may be reversed. In other words, the Rx UE may start with "p" LBT-free attempts (if the above two restrictions regarding short control signaling transmission are met), followed by "m" LBT-based attempts. This technique may allow for faster access to PSFCH resources. This method may be used for higher priority UEs with a restricted latency budget (e.g., URLLC traffic). In some embodiments, this technique may also be used by all UEs, but the number of LBT-free attempts "p" may depend on the traffic priority. The LBT-free "p" may be considered a subset of the "m" PSFCH attempts from the perspective of the NR system. In particular, the UE may be able to access "m" PSFCH resources within each PSSCH transmission, in which the UE applies LBT in the subset "p".

[0091] According to another embodiment of the present disclosure, HARQ feedback may utilize COT sharing. According to this technique, assume that UE A (e.g., the Tx UE) expects HARQ feedback from UE B (e.g., the Rx UE). After the data transmission by UE A, the UE A COT shares resources with UE B. UE B transmits the PSFCH without LBT or with one LBT attempt. Therefore, UE A assumes that UE B will send ACK / NACK in the same time slot, where UE A sends data transmission after receiving the PSSCH. Therefore, it is required that UE B immediately processes the PSSCH and provides a separate PSFCH with only one symbol.

[0092] Therefore, when the Rx UE has the ability to quickly process PSCCH / PSSCH and is able to send HARQ feedback within the same time slot of the Tx UE, and if the PSFCH resources are configured within the same time slot of the PSSCH transmission, then the Rx UE may transmit HARQ feedback in the PSFCH resources of the same time slot without performing LBT channel access, or if the gap symbol between the PSSCH and the AGC symbol is less than a set or predetermined threshold value, then the Rx UE may transmit HARQ feedback in the PSFCH resources of the same time slot without performing Cat 2 LBT channel access. When the gap symbol is greater than the threshold value, the Rx UE may optionally use the extended cyclic prefix for transmitting the AGC in the last part of the gap symbol in advance, so that the gap in the gap symbol becomes lower than the threshold value.

[0093] In some embodiments, if the Tx UE in the above description intends to transmit to another different Rx UE, the different Rx UE may still execute the above procedures, with the limiting conditions being: 1) the Tx UE explicitly indicates in the SCI or the medium access control control element (MAC CE) that a set of Rx UE IDs or group IDs may use a shared COT for transmitting their HARQ feedback; 2) the Tx UE explicitly indicates in the SCI or the MAC CE that any Rx UE may use a shared COT for transmitting their HARQ feedback; and 3) implicitly all Rx UEs are pre-configured to be able to use a shared COT from any Tx UE for transmitting their HARQ feedback. In some embodiments, there may be a bit field in the SCI or the MAC CE to indicate COT-sharing for PSFCH at the Tx UE by the Rx UE.

[0094] In some embodiments, if no other SL UE is reserved for the following / target time slot, UE B (e.g., the Rx UE) may be allowed to send a reservation signal. In this case, in a time slot later than the time slot in which the PSSCH is received, UE B may send a HARQ ACK / NACK after decoding the PSSCH. If another UE C reserves the following / target time slot in which UE B intends to send a HARQ ACK / NACK, UE B may share the COT from UE C and occupy the PSFCH for transmitting its ACK / NACK without LBT. Additionally, when UE B cannot perform COT sharing from other UEs, UE B may start LBT earlier at the beginning of the time slot to increase the chance of channel acquisition, where once UE B acquires a channel for transmitting a HARQ ACK / NACK, a reservation signal will be required to maintain the channel.

[0095] According to another embodiment of the present disclosure, HARQ feedback can be sent in the SCI. For example, UE B (e.g., Rx UE) can send ACK / NACK in the SCI addressed to UE A (e.g., Tx UE). The SCI can be used to send HARQ feedback alone (e.g., by using an independent SCI), or when UE A sends data. Fields in the second-stage SCI can be added to transmit ACK / NACK. In some embodiments, one or more ACK / NACK can be sent, and feedback can be sent for one or more HARQ process numbers. In some embodiments, UE B can send HARQ feedback for all HARQ processes simultaneously, where feedback for unused HARQ processes is ignored (e.g., similar to Type 1 HARQ codebook). In this case, the SCI feedback size can be fixed. According to yet another embodiment, HARQ feedback can be sent only for the HARQ processes being used. In this case, the SCI size can be variable, but is known to UE B (assuming no transmissions have been missed). To avoid any size mismatch, a Downlink Assignment Index (DAI)-type field can be included.

[0096] Therefore, UE B does not require a specific LBT for sending HARQ feedback, but can apply this technique only when the UE has data to transmit. Therefore, this technique can be most suitable for more symmetric or more asymmetric traffic. In some embodiments, the ACK / NACK can also be carried as a MAC CE in the PSSCH. This can be particularly applicable (but not limited to) the case where UE A is the target UE for another TB transmission. In this case, the MAC CE can indicate the specific HARQ process information for which UE B provides the ACK or NACK. This MAC CE can also be sent together with the SCI indication to notify UE A of the existence of the HARQ feedback. In another embodiment, the HARQ feedback can be multiplexed with the data in a manner similar to the SCI. This may require a flag in the SCI to indicate the existence of the HARQ feedback multiplexed with the data.

[0097] It should be noted that the above techniques can be utilized independently or they can be combined with any one or more of the above techniques to strive for improved efficiency and reliability. For example, the Rx UE can be configured as a first PSFCH and a second PSFCH, and the Rx UE can attempt to perform LBT before the first PSFCH. If LBT is successful, the primary PSFCH can be used to send HARQ feedback. If LBT fails, and if the Rx UE must transmit data and can meet the latency for sending HARQ feedback, the Rx UE can send the HARQ feedback in the SCI and skip LBT before the second PSFCH. Additionally, if short control exemption can be used, the Rx UE can transmit HARQ feedback even if LBT fails.

[0098] FIG. 8 is a flowchart of a method for providing HARQ feedback during unauthorized sidelink communication. Thus, at step 802, the first UE can first determine that the first UE will receive configuration information for PSFCH resources. Here, the configuration information can include information that can be used to map the PSSCH to multiple PSFCH resources (such as mapping PSSCH 7 to a first PSFCH 7 resource and a second PSFCH 7 resource), as described above with reference to FIG. 6. In some embodiments, at step 803, the first UE can determine that the second UE will receive a signal (e.g., HARQ feedback) from the first UE. In other words, the first UE can be configured to determine whether a signal such as HARQ feedback is expected before the second UE will start transmitting a data file or data packet to the first UE. Subsequently, at step 804, in response to determining that the first UE will receive the configuration information, the first UE can perform a first LBT sensing on the first PSFCH from among the multiple PSFCH resources. At step 806, the first UE determines whether the first LBT sensing is timely successful or fails. In response to determining that the first LBT fails, the first UE can then transmit a signal, such as the HARQ feedback expected by the second UE, via the second PSFCH resource. As previously described, the HARQ feedback can be ACK / NACK. In some embodiments, the transmitted signal can be some other type of signal, such as an inter-UE coordination (IUC) signal. In some embodiments, if the first LBT sensing fails, the first UE can perform a second LBT sensing on the second PSFCH resource before transmitting the HARQ feedback via the PSFCH resource.

[0099] FIG. 9 is a block diagram of an electronic device in a network environment 900 according to an embodiment. Referring to FIG. 9, the electronic device 901 in the network environment 900 may communicate with the electronic device 902 via a first network 998 (e.g., a short-range wireless communication network), or communicate with the electronic device 904 or the server 908 via a second network 999 (e.g., a long-range wireless communication network). The electronic device 901 may communicate with the electronic device 904 via the server 908. The electronic device 901 may include a processor 920, a memory 930, an input device 940, a sound output device 955, a display device 960, an audio module 970, a sensor module 976, an interface 977, a haptic module 979, a camera module 980, a power management module 988, a battery 989, a communication module 990, a subscriber identification module (SIM) card 996, or an antenna module 994. In one embodiment, at least one of the components (e.g., the display device 960 or the camera module 980) may be omitted from the electronic device 901, or one or more other components may be added to the electronic device 901. Some of the components may be implemented as a single integrated circuit (IC). For example, the sensor module 976 (e.g., a fingerprint sensor, an iris sensor, or an illuminance sensor) may be embedded in the display device 960 (e.g., a display).

[0100] The processor 920 may execute software (e.g., a program 940) to control at least one other component (e.g., a hardware or software component) of the electronic device 901 coupled to the processor 920, and may perform various data processing or calculations.

[0101] As at least part of data processing or computing, the processor 920 may load commands or data received from another component (e.g., the sensor module 976 or the communication module 990) in the volatile memory 932, process the commands or data stored in the volatile memory 932, and store the resulting data in the non-volatile memory 934. The processor 920 may include a main processor 921 (e.g., a central processing unit (CPU) or an application processor (AP)) and an auxiliary processor 923 (e.g., a graphics processing unit (GPU), an image signal processor (ISP), a sensor hub processor, or a communication processor (CP)), and the auxiliary processor 923 may operate independently of the main processor 921 or in combination with the main processor. Additionally or alternatively, the auxiliary processor 923 may be adapted to consume less power than the main processor 921 or perform specific functions. The auxiliary processor 923 may be implemented as separate from the main processor 921 or as part of the main processor 921.

[0102] The auxiliary processor 923 may control at least some of the functions or states related to at least one of the components of the electronic device 901 (e.g., the display device 960, the sensor module 976, or the communication module 990) instead of the main processor 921 when the main processor 921 is in a non-active (e.g., sleep) state or together with the main processor 921 when the main processor 921 is in an active state (e.g., executing an application). The auxiliary processor 923 (e.g., an image signal processor or a communication processor) may be implemented as part of another component (e.g., the camera module 980 or the communication module 990) that is functionally related to the auxiliary processor 923.

[0103] The memory 930 may store various data used by at least one component of the electronic device 901 (e.g., the processor 920 or the sensor module 976). The various data may include, for example, software (e.g., the program 940) and input data or output data for commands related thereto. The memory 930 may include the volatile memory 932 or the non-volatile memory 934.

[0104] The program 940 may be stored in the memory 930 as software and may include, for example, an operating system (OS) 942, middleware 944, or an application 946.

[0105] The input device 950 can receive commands or data to be used by another component (e.g., the processor 920) of the electronic device 901 from the outside of the electronic device 901 (e.g., a user). The input device 950 can include, for example, a microphone, a mouse, or a keyboard.

[0106] The sound output device 955 can output a sound signal to the outside of the electronic device 901. The sound output device 955 can include, for example, a speaker or a receiver. The speaker can be used for general purposes, such as playing multimedia or recording, and the receiver can be used for receiving incoming calls. The receiver can be implemented as separate from the speaker or as part of the speaker.

[0107] The display device 960 can visually provide information to the outside of the electronic device 901 (e.g., a user). The display device 960 can include, for example, a display, a holographic device, or a projector, and control circuitry for controlling the corresponding one of the display, the holographic device, and the projector. The display device 960 can include a touch circuit suitable for detecting a touch or a sensor circuit (e.g., a pressure sensor) suitable for measuring the intensity of a force caused by the touch.

[0108] The audio module 970 can convert sound into an electrical signal and vice versa. The audio module 970 can obtain sound via the input device 950 or output sound via the sound output device 955 or headphones of an external electronic device 902 that is directly (e.g., wired) or wirelessly coupled to the electronic device 901.

[0109] The sensor module 976 can detect the operating state of the electronic device 901 (e.g., power or temperature) or the environmental state outside the electronic device 901 (e.g., the state of a user), and then generate an electrical signal or data value corresponding to the detected state. The sensor module 976 can include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor.

[0110] The interface 977 can support one or more specified protocols for an electronic device 901 that is to be used for direct (e.g., wired) or wireless coupling to an external electronic device 902. The interface 977 can include, for example, a high definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.

[0111] The connection terminal 978 can include a connector through which the electronic device 901 can be physically connected to the external electronic device 902. The connection terminal 978 can include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).

[0112] The tactile module 979 can convert an electrical signal into a mechanical stimulus (e.g., vibration or movement) or an electrical stimulus that can be recognized by the user via touch or kinesthesia. The tactile module 979 can include, for example, a motor, a piezoelectric element, or an electrical stimulator.

[0113] The camera module 980 can capture still images or moving images. The camera module 980 can include one or more lenses, an image sensor, an image signal processor, or a flash. The power management module 988 can manage the power supplied to the electronic device 901. The power management module 988 can be implemented as at least part of, for example, a power management integrated circuit (PMIC).

[0114] The battery 989 can supply power to at least one component of the electronic device 901. The battery 989 can include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

[0115] The communication module 990 can support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device 901 and an external electronic device (e.g., the electronic device 902, the electronic device 904, or the server 908), and performing communication via the established communication channel. The communication module 990 can include one or more communication processors, and the one or more communication processors can operate independently of the processor 920 (e.g., the AP) and support direct (e.g., wired) communication or wireless communication. The communication module 990 can include a wireless communication module 992 (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module 994 (e.g., a local area network (LAN) communication module or a power line communication (PLC) module). A corresponding one of these communication modules can communicate with the external electronic device via the first network 998 (e.g., a short-range communication network, such as the BluetoothTM, wireless-fidelity (Wi-Fi) direct, or Infrared Data Association (IrDA) standard) or the second network 999 (e.g., a long-range communication network, such as a cellular network, the Internet, or a computer network (e.g., a LAN or a wide area network (WAN))). These various types of communication modules can be implemented as a single component (e.g., a single IC), or can be implemented as multiple separate components (e.g., multiple ICs). The wireless communication module 992 can use the user information (e.g., the international mobile subscriber identity (IMSI)) stored in the user identification module 996 to identify and authenticate the electronic device 901 in a communication network (such as the first network 998 or the second network 999).

[0116] The antenna module 997 can transmit signals or power to the outside of the electronic device 901 (e.g., an external electronic device) or receive signals or power from the outside of the electronic device 901. The antenna module 997 can include one or more antennas, and the communication module 990 (e.g., the wireless communication module 992) can select, for example, at least one antenna suitable for the communication scheme used in the communication network (such as the first network 998 or the second network 999) from the antenna module. Subsequently, signals or power can be transmitted or received between the communication module 990 and the external electronic device via the selected at least one antenna.

[0117] Commands or data can be transmitted or received between the electronic device 901 and the external electronic device 904 via the server 908 coupled to the second network 999. For example, according to the various example embodiments described above, the electronic device 902 can be UE A, and the electronic device 901 can be UE B. Each of the electronic device 902 and the electronic device 904 can be a device of the same type or a different type from the electronic device 901. All or some of the operations to be performed at the electronic device 901 can be performed at one or more of the external electronic device 902, the external electronic device 904, or the external electronic device 908. For example, if the electronic device 901 is to automatically perform a function or service or perform a function or service in response to a request from a user or another device, then instead of performing the function or service or in addition to performing the function or service, the electronic device 901 can request one or more external electronic devices to perform at least part of the function or service. The one or more external electronic devices receiving the request can perform at least part of the requested function or service or additional functions or additional services related to the request, and transmit the result of the execution to the electronic device 901. The electronic device 901 can provide the result as at least part of a reply to the request with or without further processing the result. For this purpose, technologies such as cloud computing, distributed computing, or master-slave computing can be used.

[0118] FIG. 10 illustrates a system including a UE 1005 and a gNB 1010 communicating with each other. The UE can include a radio 1015 and a processing circuit (or components for processing) 1020, which can perform the various methods disclosed herein, for example, the method shown in FIG. 1. For example, the processing circuit 920 can receive a transmission from the network node (gNB) 1010 via the radio 1015, and the processing circuit 1020 can transmit a signal to the gNB 1010 via the radio 1015. [

[0119] ]The embodiments of the subject matter and the operations described in this specification can be implemented in digital electronic circuitry or in computer software, firmware, or hardware (including the structures disclosed in this specification and their structural equivalents) or in a combination of one or more of them. Embodiments of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions encoded on a computer storage medium for execution by, or to control the operation of, a data processing apparatus. Alternatively or additionally, the program instructions can be encoded on an artificially generated propagated signal (e.g., a machine-generated electrical, optical, or electromagnetic signal) that is generated to encode information for transmission to a suitable receiver apparatus for execution by the data processing apparatus. The computer storage medium can be or be included in a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination thereof. Further, when the computer storage medium is not a propagated signal, the computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be one or more individual physical components or media (e.g., multiple CDs, disks, or other storage devices) or be included in one or more individual physical components or media. Additionally, the operations described in this specification can be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources. [

[0120] ]Although this specification may contain many specific implementation details, the implementation details should not be construed as limitations on the scope of any claimed subject matter but rather as descriptions of features specific to particular embodiments. Certain features that are described in the context of separate embodiments in this specification can also be implemented in combination in a single embodiment. Conversely, the various features described in the context of a single embodiment can also be implemented separately in multiple embodiments or in any suitable subcombination. Moreover, although the 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 deleted from the combination, and the claimed combination can be directed to a subcombination or variation of a subcombination. [

[0121] ]Similarly, although the operations are depicted in the drawings in a particular order, this should not be understood as requiring that the operations be performed in the particular order shown or in a sequential order, or that all of the illustrated operations be performed to achieve a desirable result. In some cases, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0122] Thus, specific embodiments of the subject matter have been described herein. Other embodiments are within the scope of the following claims. In some cases, the acts recited in the claims can be performed in a different order and still achieve a desirable result. Additionally, the processes depicted in the accompanying figures need not be in the particular order or sequential order shown to achieve a desirable result. In certain embodiments, multitasking and parallel processing may be advantageous.

[0123] As those skilled in the art will recognize, the novel concepts described herein can be modified and varied across a wide range of applications. Accordingly, the scope of the claimed subject matter should not be limited to any of the particular illustrative teachings discussed above, but is rather defined by the following claims.

[0124] Abbreviation List

[0125] SL-U Unauthorized Sidelink

[0126] GP Guard Period

[0127] CP Cyclic Prefix

[0128] LBT Listen Before Talk

[0129] V2V Vehicle-to-Vehicle

[0130] ITS Intelligent Transport System

[0131] COT Channel Occupancy Time

[0132] SL Sidelink

[0133] UE User Equipment

[0134] SCI Sidelink Control Information

[0135] PSCCH Sidelink Shared Control Channel

[0136] PSSCH Sidelink Shared Data Channel

[0137] AGC Automatic Gain Control

[0138] TB Transport Block

[0139] HARQ Hybrid Automatic Repeat Request

[0140] MAC CE Media Access Control Control Element

[0141] PSFCH Sidelink Feedback Channel

[0142] PRB Physical Resource Block

Brief Description of Drawings

[0031] In the following sections, aspects of the subject matter disclosed herein will be described with reference to the exemplary embodiments shown in the drawings. FIG. 1 is an example system including a User Equipment (UE) and a network node (gNB) according to various embodiments of the present disclosure, where information may be transmitted via sidelink between UEs or may be transmitted via the gNB. FIG. 2 is an illustration of PSFCH symbol patterns in time slots in a resource pool according to various embodiments of the present disclosure. FIG. 3 is a graphical illustration of an example SL HARQ in an unlicensed band where UE A communicates with UE B according to various embodiments of the present disclosure. FIG. 4 is a flowchart of a procedure for providing HARQ feedback ACK / NACK according to various embodiments of the present disclosure. FIG. 5 is a graphical illustration of an example of an SL PSSCH and PSFCH resource mapping procedure for type 2 multicast including two Rx UEs according to various embodiments of the present disclosure. FIG. 6 is a graphical illustration of an example of an SL PSSCH and PSFCH resource mapping for type 2 multicast with one Rx UE according to various embodiments of the present disclosure. FIG. 7 is a graphical illustration of an example of an SL PSSCH and PSFCH resource mapping for type 2 multicast with m Rx UEs according to various embodiments of the present disclosure. FIG. 8 is a flowchart of a method for providing HARQ feedback during unlicensed sidelink communication according to various embodiments of the present disclosure. FIG. 9 is a block diagram of an electronic device in a network environment according to various embodiments of the present disclosure. FIG. 10 is an example system including a UE and a gNB communicating with each other according to various embodiments of the present disclosure.

Claims

1. A method for performing Hybrid Automatic Repeat Request (HARQ) feedback, comprising: The first user equipment (UE) receives configuration information for physical-side line feedback channel (PSFCH) resources; The first UE responds to the receipt by performing a first Listen-Before-Speak (LBT) sensing of the first PSFCH resource of the PSFCH resource; and determines that the first LBT sensing has failed, and in response, transmits a signal via the second PSFCH resource of the PSFCH resource, and transmits the signal on the Sideline Control Information (SCI) channel.

2. The method as described in claim 1 further includes the first UE determining that the second UE will receive the signal from the first UE.

3. The method as described in claim 2, wherein the signal is a Hybrid Automatic Repeat Request (HARQ) feedback signal.

4. The method as described in claim 2, wherein the first PSFCH resource and the second PSFCH resource are mapped to a single entity-side crosslink shared data channel (PSSCH).

5. The method of claim 4 further includes determining that one or more short control exemptions are available, and wherein, in response to the determination that one or more short control exemptions are available without performing a second LBT sensing on the second PSFCH resource, the signal is transmitted via the second PSFCH resource.

6. The method as described in claim 2 further includes, in response to the determination that the first LBT sensing of the first PSFCH resource has failed, the first UE performing a second LBT sensing of the second PSFCH resource.

7. The method of claim 6, wherein the second LBT sensing is performed before the signal is transmitted via the second PSFCH resource.

8. The method of claim 6, wherein in response to the determination that the second LBT sensing of the second PSFCH resource is successful, the signal is transmitted via the second PSFCH resource.

9. The method of claim 1, wherein the signal is executed during side link communication via an unlicensed frequency band.

10. The method of claim 2, wherein the second PSFCH resource is used during a channel occupancy time (COT) shared by the first UE and the second UE, the method further comprising the first UE transmitting the signal on the shared COT.

11. The method of claim 10, wherein the signal is transmitted via the second PSFCH resource without performing LBT sensing on the second PSFCH resource.

12. A system for performing Hybrid Automatic Repeat Request (HARQ) feedback, comprising: A first user equipment (UE), the first UE comprising: a radio; and processing circuitry, wherein the processing circuitry is configured to: receive configuration information for a physical side link feedback channel (PSFCH) resource; in response to receiving the configuration information, perform a first listen-before-speak (LBT) sensing of a first PSFCH resource of the PSFCH resource; determine that the first LBT sensing has failed, and in response, transmit a signal via a second PSFCH resource of the PSFCH resource; and in response to the determination that the first LBT sensing has failed, transmit the signal on a sideline control information (SCI) channel.

13. The system of claim 12, wherein the processing circuitry is further configured to determine that the second UE will receive the signal from the first UE.

14. The system as described in claim 12, wherein the signal is a Hybrid Automatic Repeat Request (HARQ) feedback signal.

15. The system as described in claim 12, wherein the first PSFCH resource and the second PSFCH resource are mapped to a single entity-side crosslink shared data channel (PSSCH).

16. The system of claim 15, wherein the processing circuitry is further configured to determine that one or more short control exemptions are available, and wherein, in response to the determination that one or more short control exemptions are available without performing a second LBT sensing on the second PSFCH resource, the signal is transmitted via the second PSFCH resource.

17. The system of claim 12, wherein in response to the determination that the first LBT sensing of the first PSFCH resource has failed, the processing circuitry is further configured to perform a second LBT sensing of the second PSFCH resource.

18. The system of claim 17, wherein the processing circuitry is further configured to perform the second LBT sensing prior to transmitting the signal via the second PSFCH resource.

19. The system of claim 17, wherein in response to the determination that the second LBT sensing of the second PSFCH resource is successful, the processing circuitry is further configured to transmit the signal via the second PSFCH resource.

20. The system as claimed in claim 12, wherein the signal is executed during side link communication via an unlicensed frequency band.

21. The system of claim 13, wherein the second PSFCH resource is used during a channel occupancy time (COT) shared by the first UE and the second UE, and the processing circuitry is further configured to transmit the signal over the shared COT.

22. The system of claim 16, wherein the signal is transmitted via the second PSFCH resource without performing second LBT sensing on the second PSFCH resource.

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