Method and apparatus for transmitting harq-ack feedback for sidelink communication

Abstract

The present disclosure relates to methods and apparatuses. According to some embodiments according to the present disclosure, a method for wireless communications performed by a first UE includes receiving, from a second UE, sidelink control information (SCI) on a first interlace over a carrier, wherein the SCI schedules a data transmission over the carrier and the first interlace comprises uniformly spaced resource blocks (RBs) in a frequency domain, and transmitting, from the first UE, hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource based on the SCI.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to wireless communication technology, and more particularly, to hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback transmission for sidelink communication over unlicensed spectrum. BACKGROUND

[0002] In a wireless communication system, a communication device (e.g., a user equipment (UE)) can communicate with another communication device via a data path supported by a network of an operator (e.g., a cellular or Wi-Fi network infrastructure). The data path supported by the network of the operator can include a base station (BS) and a plurality of gateways.

[0003] In sidelink communication, communication devices that are relatively close to each other can communicate directly with each other via a sidelink (SL), rather than through a BS link. The term “SL” can refer to a direct radio link established for communication between devices (e.g., UEs) rather than communication via cellular infrastructure (uplink and downlink) as discussed above. The “SL” can also be referred to as a sidelink communication link. The sidelink communication link can be used in any suitable telecommunication network according to various standards.

[0004] Sidelink communication can provide various advantages, e.g., relatively high transfer rate, relatively low latency, etc. Moreover, traffic concentrated at a base station can be distributed during sidelink communication. Furthermore, a UE supporting sidelink communication can be used as a relay node to extend the coverage of a base station.

[0005] A BS and a UE can operate in both licensed spectrum and unlicensed spectrum. There is a need to handle HARQ-ACK feedback transmission for sidelink communication over unlicensed spectrum. SUMMARY

[0006] Some embodiments of the present disclosure provide a method for wireless communication performed by a first user equipment (UE). The method can include receiving, from a second UE, sidelink control information (SCI) on a first interlace over a carrier, where the SCI can schedule a data transmission on the carrier, and the first interlace can include uniformly spaced resource blocks (RBs) in a frequency domain; and transmitting, from the first UE, hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource based on the SCI.

[0007] Some embodiments of the disclosure provide a method performed by a second user equipment (UE). The method can include transmitting sidelink control information (SCI) to a first UE on a first interlace on a carrier, where the SCI can schedule a data transmission on the carrier, and the first interlace can include uniformly spaced resource blocks (RBs) in a frequency domain; and receiving, from the first UE, hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource based on the SCI.

[0008] Some embodiments of the disclosure provide an apparatus. According to some embodiments of the disclosure, the apparatus can include at least one non-transitory computer- readable medium having computer-executable instructions stored thereon; at least one receiving circuitry; at least one transmitting circuitry; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry, and the at least one transmitting circuitry, wherein the computer-executable instructions cause the at least one processor to implement a method according to some embodiments of the disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] The description of the disclosure is presented to describe an embodiment of the disclosure as presently preferred, and will be presented in the context of specific embodiments of the disclosure. These drawings depict only exemplary embodiments of the disclosure and are therefore not to be considered limiting of its scope.

[0010] Figure 1 A diagram illustrating a wireless communication system according to some embodiments of the disclosure is described.

[0011] Figure 2 An example of interlace-based resource block configuration according to some embodiments of the disclosure is described.

[0012] Figure 3 A flowchart illustrating an exemplary procedure for sidelink transmission according to some embodiments of the disclosure is described.

[0013] Figure 4 An example mapping relationship between PSSCH transmission and PSFCH transmission according to some embodiments of the disclosure is described.

[0014] Figure 5 An example resource configuration in a slot according to embodiments of the disclosure is described.

[0015] Figure 6 A flowchart illustrating a method for wireless communication according to some embodiments of the disclosure is described.

[0016] Figure 7 A flowchart illustrating a method for wireless communication according to some embodiments of the disclosure is described.

[0017] Figure 8 A block diagram illustrating an exemplary apparatus according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0018] The detailed description of the accompanying drawings is intended as a description of the preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure can be practiced. It should be understood that the same or equivalent functions can be achieved by different embodiments intended to be included in the spirit and scope of the present disclosure.

[0019] Reference will now be made in detail to certain embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. To facilitate understanding, the embodiments are provided in the context of specific network architectures and new service scenarios, such as 3GPP 5G (NR) and 3GPP LTE Release 8. It is contemplated that as network architectures and new service scenarios evolve, all embodiments of the present disclosure will also be applicable to similar technical issues. Furthermore, the terminology used in this disclosure may vary without affecting the principles of the present disclosure.

[0020] Figure 1 A schematic diagram illustrating a wireless communication system 100 according to some embodiments of the present disclosure.

[0021] like Figure 1 As shown in , wireless communication system 100 may include a base station (e.g., BS 120) and some UEs 110 (e.g., UE 110a, UE 110b, and UE 110c). Figure 1 A specific number of UEs 110 and one BS 120 are depicted in FIG. 1 , but it is contemplated that the wireless communication system 100 may also include more BSs and more or fewer UEs within and outside the coverage of the BSs.

[0022] The UE and base station may support communications based on, for example, 3G, Long Term Evolution (LTE), LTE-Advanced (LTE-A), New Radio (NR), or other suitable protocols. For example, BS 120 may include an eNB or gNB. UE 110a, UE 110b, or UE 110c may include, for example, but not limited to, computing devices, wearable devices, mobile devices, IoT devices, vehicles, and the like. Those skilled in the art will appreciate that as technology develops and advances, the terminology used in this disclosure may change, but this should not affect or limit the principles and spirit of this disclosure.

[0023] BS 120 may define one or more cells, and each cell may have a coverage area 130. In exemplary wireless communication system 100, some UEs (e.g., UE 110a and UE 110b) are within the coverage area of ​​BS 120, which may not be within the coverage area of ​​BS 120. Figure 1The particular base station 120 shown in the middle, and can be any of the base stations 120 in the wireless communication system, and some UEs (e.g., UE 110c) are outside the coverage of the BS 120. For example, in the case that the wireless communication system includes two base stations 120, UE 110a being within the coverage of either of the two base stations means that UE 110a is within the coverage (i.e., in-coverage) of the base stations 120 in the wireless communication network; and UE 110a being outside the coverage of the two base stations 120 means that UE 110a is outside the coverage (i.e., out-of-coverage) of the base stations 120 in the wireless communication system.

[0024] Still referring to Figure 1 , the UE 110a and the UE 110b can communicate with the BS 120 via, for example, a Uu link (indicated by the dashed arrows in Figure 1 ). The UE 110a, the UE 110b, and the UE 110c can communicate with each other via a sidelink (indicated by the solid arrows in Figure 1 ), and can form a UE group. During sidelink communication, a transmitting UE (hereinafter referred to as “Tx UE”) can transmit signaling, data, or both, to a receiving UE (hereinafter referred to as “Rx UE”). For example, referring to Figure 1 , the Tx UE (e.g., the UE 110a) can transmit data to the Rx UE (e.g., the UE 110b or the UE 110c).

[0025] The BS (e.g., the BS 120 in Figure 1 ) and the UE (e.g., the UE 110a, the UE 110b, and the UE 110c in Figure 1 ) can operate in both licensed spectrum and unlicensed spectrum. For example, the unlicensed spectrum can be around 6 GHz or 60 GHz of carrier frequency. The NR-U (NR system access on unlicensed spectrum) operating bandwidth can be an integer multiple of 20 MHz. To achieve fair coexistence between the NR system (e.g., the NR-U system) and other wireless systems, a channel access procedure, also known as listen-before-talk (LBT) test, can be performed in 20 MHz units before communicating on the unlicensed spectrum. For a bandwidth larger than 20 MHz (e.g., 40 MHz, 60 MHz, 80 MHz, or 100 MHz), the carrier bandwidth can be divided into sub-bands, each of which has a bandwidth of 20 MHz, and can be indexed.

[0026] To perform an LBT test, an energy detection can be performed on a particular channel. If the received power of the channel is below a predefined threshold, the LBT test can be determined as successful and the channel can thus be considered as empty and can be used for transmission. Only when the LBT test is successful, a device (e.g., a UE) can start a transmission on the channel and occupy the channel until a maximum channel occupancy time (MCOT). Otherwise, i.e., if the LBT test fails, the device cannot start any transmission on the channel and can continue to perform another LBT test until a successful LBT test result. A BS or a UE can perform the above LBT test on each sub-band (e.g., every 20 MHz sub-band, also referred to as “LBT sub-band”), and can communicate on the available sub-band(s) if any.

[0027] In addition, wireless transmissions over unlicensed spectrum should meet the requirements of regulations administered by the country / region where the wireless communication device (e.g., a UE) is located. The design of uplink waveform for NR-U PUSCH (Physical Uplink Shared Channel) / PUCCH (Physical Uplink Control Channel) should meet these regulatory requirements on unlicensed spectrum. Similarly, the design of waveform for sidelink communication should also meet the above regulatory requirements on unlicensed spectrum.

[0028] The requirements mainly contain two aspects:

[0029] (1) Occupied Channel Bandwidth (OCB): the bandwidth containing 99% of the signal power should be between 80% and 100% of the declared nominal channel bandwidth; and

[0030] (2) Maximum Power Spectral Density (PSD) with 1 MHz resolution bandwidth (e.g., 10 dBm / MHz).

[0031] The above two requirements specify that due to the PSD and OCB constraints, a small portion of the occupied channel bandwidth cannot be transmitted at the maximum available power at the UE.

[0032] In Rel-14 LTE enhanced License Assisted Access (LTE eLAA), an interlace-based waveform is used as the uplink waveform for unlicensed spectrum. In LTE, the bandwidth of a carrier is 20 MHz. The 20 MHz bandwidth can contain 100 physical resource blocks (PRBs), which are divided into 10 interlaces. Each interlace can contain 10 PRBs and can be uniformly distributed within the entire bandwidth. In this way, each interlace spans over 80% of the system bandwidth, such that the regulatory requirement of OCB can be met. In addition, the 10 PRBs of one interlace are equally spaced in frequency, such that two adjacent PRBs of one interlace are separated by a distance of 1.8 MHz and thus power boosting of each PRB of one interlace can be achieved.

[0033] To achieve power boosting under PSD constraints and meet regulatory requirements for OCB in NR systems, staggered-based waveforms can be applied to uplink (UL) transmission as well as sidelink communication. As frequency resources, a stagger can be defined as a set of common resource blocks (CRBs), which can be uniformly spaced in the frequency domain. The number of stags in the frequency domain can depend on the subcarrier spacing.

[0034] For example, assuming there are M stags with indices 0, 1, …, M-1, a stag m, m e {0, 1, …, M-1}, can consist of CRBs {m, M+m, 2M+m, 3M+m, …}. The staggered resource blocks (IRBs) in a bandwidth part (BWP) i The relationship between a stagger m and a common resource block is given by the following equation: where is the common resource block where the bandwidth part i starts with respect to the common resource block 0; and μ indicates the subcarrier spacing (SCS). For example, “μ = 0” can indicate a SCS of 15 kHz, “μ = 1” can indicate a SCS of 30 kHz, “μ = 2” can indicate a SCS of 60 kHz, and “μ = 3” can indicate a SCS of 120 kHz. The index μ can be omitted when there is no risk of confusion.

[0035] In some embodiments of the present disclosure, the number of stags distributed within the bandwidth of a carrier can be based only on the subcarrier spacing, regardless of the bandwidth of the carrier. The subcarrier spacing of an NR system can be 15 x 2 n kHz, where n is an integer. For frequency range 1 (FR1), the subcarrier spacing can be 15 kHz, 30 kHz, or 60 kHz, and different subcarrier spacing values can support different maximum bandwidths. In some examples, for a carrier with a 15 kHz subcarrier spacing, there can be 10 stags on the carrier. In some examples, for a carrier with a 30 kHz subcarrier spacing, there can be 5 stags on the carrier. In some examples, for a carrier with a 60 kHz subcarrier spacing, there can be 2 or 3 stags on the carrier. It should be understood that the number of stags (e.g., 10 stags for a carrier with a 15 kHz subcarrier spacing, or 5 stags for a carrier with a 30 kHz subcarrier spacing) is for illustrative purposes only and should not be construed as limiting embodiments of the present disclosure.

[0036] Table 1 below shows examples of NR bandwidth configurations for different subcarrier spacings. According to Table 1, the maximum number of RBs (denoted as NRBin Table 1) can be determined based on the subcarrier spacing and the corresponding bandwidth. RB). For example, if the bandwidth is 20 MHz and the subcarrier spacing (SCS) is 15 kHz, then the maximum number of RBs can be 106; and if the bandwidth is 20 MHz and the SCS is 30 kHz, then the maximum number of RBs can be 51. It should be understood that Table 1 is for illustrative purposes only and should not be construed as limiting embodiments of the disclosure.

[0037] Table 1

[0038]

[0039] In some embodiments of the disclosure, the number of RBs per interlace on a carrier can depend on the bandwidth of the carrier. For example, with reference to Table 1, if the carrier bandwidth is 20 MHz and the subcarrier spacing is 15 kHz, then the maximum number of RBs included in the bandwidth can be 106. As mentioned above, for a carrier with a 15 kHz subcarrier spacing, there can be 10 interlaces on the carrier. In this scenario, each of the 10 interlaces includes 10 or 11 RBs (106 / 10 = 10.6). If the carrier bandwidth is 20 MHz and the subcarrier spacing is 30 kHz, then the maximum number of RBs included in the bandwidth can be 51. In this case, as mentioned above, for a carrier with a 30 kHz subcarrier spacing, there can be 5 interlaces on the carrier. In this scenario, each of the 5 interlaces includes 10 or 11 RBs (51 / 5 = 10.2).

[0040] In some embodiments of the disclosure, for carrier bandwidths greater than 20 MHz, the spacing between consecutive RBs in an interlace remains the same for all interlaces regardless of the carrier bandwidth. In other words, the number of RBs per interlace can depend on the carrier bandwidth. Keeping the same interlace spacing in case of increasing bandwidth is a straightforward and simple approach to extend the interlace design from 20 MHz to wider bandwidths.

[0041] For example, if the carrier bandwidth is 80 MHz and the subcarrier spacing is 30 kHz, then according to Table 1, the maximum number of RBs included in the bandwidth can be 217. Furthermore, since the subcarrier spacing is 30 kHz, there are 5 interlaces on the carrier. In this scenario, each of the 5 interlaces can include 43 or 44 RBs (217 / 5 = 43.4).

[0042] Figure 2 An example of an interlace-based resource block configuration 200 for 15 kHz subcarrier spacing is illustrated in accordance with some embodiments of the disclosure. It should be understood that the configuration 200 is for illustrative purposes only and should not be construed as limiting embodiments of the disclosure.

[0043] As shown in Figure 2 For illustrative purposes,Figure 2 only a portion of the RBs included in the carrier bandwidth (e.g., Figure 2 RBs) in FIG. 2. One of skill in the art can readily ascertain the number of RBs included in a particular carrier bandwidth by referring to, for example, Table 1 as shown above. For example, assuming a carrier bandwidth of 15 MHz, the carrier bandwidth can include 79 RBs; and assuming a carrier bandwidth of 20 MHz, the carrier bandwidth can include 106 RBs.

[0044] As mentioned above, the number of interlaces distributed within the bandwidth of a carrier can be based only on the subcarrier spacing, independent of the bandwidth of the carrier. In Figure 2 the example of FIG. 2, the RBs of a carrier bandwidth are divided into 10 interlaces (corresponding to a 15 kHz subcarrier spacing), which are denoted in FIG. 2 by reference numerals 210, 211, 212, 213, 214, 215, 216, 217, 218, and 219. Figure 2

[0045] Each of the 10 interlaces can include uniformly spaced RBs in the frequency domain. The number of RBs included in each of the 10 interlaces can depend on the carrier bandwidth. As shown in Figure 2 FIG. 2, interlace 210 can include RB 2000, RB 2010, RB 2020, RB 2030, etc.; interlace 211 can include RB 2001, RB 2011, RB 2021, RB 2031, etc.; and interlace 219 can include RB 2009, RB 2019, RB 2029, etc. The RBs 2000-2035 can be indexed from “0” to “35” along the frequency axis, and the interlaces 210-219 can be indexed from “0” to “9.”

[0046] Figure 3 A flowchart of an exemplary procedure 300 for sidelink transmission in accordance with some embodiments of the present disclosure is illustrated. The details described in all previous embodiments of the present disclosure are applicable to the Figure 3 embodiment illustrated in FIG. 3.

[0047] The exemplary procedure 300 illustrates a procedure for a UE (e.g., UE 310a) to communicate with another UE (e.g., UE 310b). In some instances, each of the UE 310a and the UE 310b can function as a UE 110a, UE 110b, or UE 110c in Figure 1 FIG. 1.

[0048] The details described in all previous embodiments of the present disclosure are applicable to the Figure 3 ​The order of operations in exemplary process 300 can be changed, and some of the operations in exemplary process 300 can be eliminated or modified, without departing from the spirit and scope of the disclosure. It is understood that those skilled in the art will be able to appreciate the changes and variations without departing from the essence of the exemplary process 300 as set forth in the embodiments described herein.

[0049] Referring to Figure 3 In operation 311, UE 310a can transmit sidelink control information (SCI) to UE 310b on a physical sidelink control channel (PSCCH). The SCI can schedule an associated data (e.g., physical sidelink shared channel (PSSCH)) transmission. In operation 313, UE 310a can transmit the associated data to UE 310b according to the SCI.

[0050] In some cases, the SCI and the associated data can be transmitted from UE 310a to UE 310b in a unicast transmission. In some other cases, the SCI and the associated data can be transmitted from UE 310a to a group of UEs including UE 310b in a groupcast transmission. In yet other cases, the SCI and the associated data can be transmitted from UE 310a to some UEs including UE 310b in a broadcast transmission.

[0051] In certain cases, a corresponding feedback (e.g., HARQ-ACK feedback) from the Rx UE (e.g., UE 310b) to the Tx UE (e.g., UE 310a) can be needed in response to receiving the associated data (e.g., PSSCH). The broadcast transmission can not need HARQ-ACK feedback. In some scenarios, the unicast transmission and the groupcast transmission can enable HARQ-ACK feedback.

[0052] For example, referring to Figure 3 If UE 310b fails to decode the PSSCH correctly, UE 310a can generate a negative acknowledgement (NACK); otherwise, UE 310b can generate a positive acknowledgement (ACK). In operation 315, UE 310b can transmit the HARQ-ACK feedback to UE 310a in response to the associated data (e.g., PSSCH). The HARQ-ACK feedback bit value 0 can represent NACK, and the HARQ-ACK feedback bit value 1 can represent ACK.

[0053] The HARQ-ACK feedback for PSSCH can be carried on a physical sidelink feedback channel (PSFCH). For unicast transmission, the Rx UE can respond with ACK or NACK on PSFCH. In this case, one feedback resource of PSFCH would be sufficient for a given PSSCH transmission.

[0054] For groupcast transmission, there are two feedback options. One option (Option 1) is to reserve only a common NACK resource for all group members (i.e., NACK-only feedback). In other words, when HARQ-ACK feedback for groupcast Option 1 is enabled, all Rx UEs in the group share one feedback resource (hereinafter also referred to as “PSFCH resource”) for PSFCH. When any Rx UE does not decode PSSCH correctly, any Rx UE can transmit NACK on the PSFCH resource, and when it decodes PSCCH correctly, it can not transmit anything (e.g., not perform transmission) on the PSFCH resource.

[0055] Another option (Option 2) is to reserve group member-specific ACK / NACK resources (i.e., ACK / NACK feedback). In other words, when HARQ-ACK feedback for groupcast Option 2 is enabled, each of the Rx UEs can have a separate PSFCH resource. When an Rx UE does not decode PSSCH correctly, the Rx UE can transmit NACK on the PSFCH resource, and when it decodes PSCCH correctly, it can transmit ACK on the PSFCH resource.

[0056] Thus, for groupcast Option 1, one PSFCH resource would be sufficient; and for groupcast Option 2, multiple feedback resources can be needed, depending on the number of Rx UEs in the group. For groupcast HARQ feedback, SCI can indicate whether the Rx UE is to use Option 1 or Option 2.

[0057] As mentioned above, staggered-based waveforms can be used in unlicensed spectrum to meet OCB and PSD regulatory requirements. In this scenario, there is a need to provide a solution for applying staggered-based waveforms for sidelink communications, such as PSCCH, PSSCH, and PSFCH transmissions over unlicensed spectrum.

[0058] Embodiments of the present disclosure provide a solution for applying staggered-based waveforms for sidelink communications over unlicensed spectrum in order to meet the above regulatory requirements. More details of embodiments of the present disclosure will be explained hereinafter in conjunction with the accompanying drawings.

[0059] In some embodiments of the present disclosure, SCI can be transmitted on a stagger (e.g., stagger 210 in Figure 2 , and can schedule data transmissions on the carrier. The data transmissions can be transmitted on one or more stags (e.g., stags 215 in Figure 2 . HARQ-ACK feedback corresponding to a particular data transmission can be transmitted on a stagger. In other words, when unlicensed spectrum is extended to transmit PSFCH carrying HARQ-ACK feedback, the unit for resource allocation can be a stagger.

[0060] Therefore, one interlace can be needed for unicast transmission or groupcast option 1 transmission to transmit PSFCH corresponding to a given PSSCH. For groupcast option 2 transmission, one or more interlaces can be needed to transmit PSFCH from one or more Rx UEs in a group. Therefore, there is a need to provide a solution for Rx UEs to determine which feedback resource (e.g., interlace) can be used to transmit HARQ-ACK feedback. The interlace used to transmit PSFCH or HARQ-ACK feedback can also be referred to as a PSFCH interlace.

[0061] However, there are some drawbacks for the above resource allocation schemes for wideband interlace structure. As mentioned above, the number of interlaces distributed within the bandwidth of a carrier can only be based on the subcarrier spacing, regardless of the bandwidth of the carrier. For example, for a carrier with 15 kHz subcarrier spacing, there can be 10 interlaces on the carrier; and for a carrier with 30 kHz subcarrier spacing, there can be 5 interlaces on the carrier. Referring to Table 1 above, if the carrier bandwidth is 20 MHz and the subcarrier spacing is 15 kHz, each of the 10 interlaces can contain 11 or 10 RBs. If the carrier bandwidth is 40 MHz and the subcarrier spacing is 15 kHz, each of the 10 interlaces can contain 22 or 21 RBs. If the carrier bandwidth is 80 MHz and the subcarrier spacing is 30 kHz, each of the 5 interlaces can contain 44 or 43 RBs. Obviously, since HARQ-ACK feedback indicating NACK or ACK can only occupy 1 bit, one interlace can provide too much resource for PSFCH transmission.

[0062] In addition, since one interlace only supports one HARQ-ACK feedback from a certain user, the user multiplexing capacity can also be relatively low. For example, for 15 kHz subcarrier spacing, there are 10 interlaces in total, which can support at most 10 PSFCH interlaces in one slot. For 30 kHz subcarrier spacing, there are 5 interlaces in total, which can support at most 5 PSFCH interlaces in one slot. There is a need to increase the user capacity.

[0063] To improve resource utilization efficiency, partial interlaces can be employed as the unit for resource allocation. For example, an interlace (hereinafter also referred to as a “full interlace”) can be divided into several partial interlaces, where each partial interlace is confined in an LBT subband (e.g., a 20 MHz subband). For example, if the carrier bandwidth is 80 MHz, a full interlace can be divided into 4 partial interlaces. In some embodiments of the present disclosure, PSFCH can be transmitted on a partial interlace instead of a full interlace.

[0064] By dividing a full interlace into several partial interlaces, resource utilization efficiency can be improved, as a full interlace can contain too many RBs for PSFCH transmission as mentioned above. In addition, the division of an interlace can not only satisfy the OCB requirement mentioned above, but also improve PSFCH capacity.

[0065] Another or further solution to improve resource utilization efficiency can be to explore PSFCH multiplexing in code domain. For example, cyclic shifts in time domain, frequency domain orthogonal cover code (OCC), or both, can be employed to enable PSFCH transmissions from multiple UEs on the same interlace or on the same partial interlace when one full interlace is divided into several partial interlaces. A UE can determine the corresponding cyclic shift, frequency domain OCC, or both, based on SCI and associated PSSCH transmission from another UE.

[0066] A sidelink resource pool containing resources for sidelink communication or sidelink resources can be assigned to a UE for sidelink operation. The sidelink resource pool can be scheduled by a base station or can be pre-configured at the UE, e.g., during manufacturing of the UE according to an industry standard. A PSFCH resource pool can be configured (or pre-configured) for every S consecutive slots. In other words, a PSSCH transmission in S consecutive slots can be acknowledged in one slot for PSFCH transmission. For example, a PSFCH resource pool can be configured in the fourth slot out of every 4 slots (i.e., S = 4).

[0067] Figure 4 An example mapping relationship between PSSCH transmission and PSFCH transmission is shown. The details described in all the foregoing embodiments of the present disclosure are applicable to the embodiments shown in Figure 4 .

[0068] Referring to Figure 4 , a PSSCH transmission can be transmitted in S consecutive slots (e.g., slot 410-0, slot 410-1, …, slot 410-S-1) and can be acknowledged in a single slot (e.g., slot 410-S). In other words, the S consecutive slots contain slots with corresponding PSFCH transmissions in the same slot (hereinafter referred to as “PSFCH slots”). In Figure 4 , a PSFCH transmission can be transmitted in the last few symbols (e.g., the last two available symbols) of a PSFCH slot.

[0069] The S consecutive slots can be referred to as “set of slots for data transmission” or “set of slots for PSSCH transmission” hereinafter. Each slot of the S consecutive slots can be referred to as “slot for data transmission” or “slot for PSSCH transmission” hereinafter

[0070] Although in Figure 4In some embodiments, the PSSCH transmission is acknowledged in a slot different from the set of slots used for the PSSCH transmission (e.g., slot 410-S), but it is contemplated that the PSSCH transmission can also be acknowledged in a slot of the set of slots used for the PSSCH transmission (e.g., the last slot of the set of slots).

[0071] Figure 5 An example resource configuration in a slot according to embodiments of the disclosure is shown. The details described in all the foregoing embodiments of the disclosure are applicable to Figure 5 the embodiments shown in

[0072] In Figure 5 , the carrier bandwidth in slot 511 can be divided into PRBs. For illustrative purposes, Figure 5 only a portion of the PRBs included in the carrier bandwidth (e.g., Figure 5 the PRBs denoted with reference numerals 520-531 in ). One of ordinary skill in the art can readily know the number of PRBs included in a particular carrier bandwidth by referring to, for example, Table 1 as shown above. Assuming a subcarrier spacing of 15 kHz, and there are 10 interlaces indexed as “0” to “9” respectively on the carrier, interlace 0 can include PRB 520, PRB 530, etc.; interlace 1 can include PRB 521, PRB 531, etc.; and interlace 9 can include PRB 529, and so on.

[0073] In Figure 5 , both frequency-division multiplexing (FDM) based and time-division multiplexing (TDM) based transmissions are supported. It is contemplated that in some other embodiments of the disclosure, pure TDM based transmission or pure FDM based transmission can be supported.

[0074] Slot 511 can include 14 symbols (e.g., orthogonal frequency-division multiplexing (OFDM) symbols). The first symbol 513 within slot 511 can be used for automatic gain control (AGC), and symbols 515 and 518 can be reserved for LBT testing. PSCCH can be transmitted on interlace 0 in the first four symbols within slot 511, some of the remaining symbols within slot 512 on interlace 0 can be used to transmit PSSCH (i.e., TDM based transmission). PSSCH can also be transmitted on interlace 5 within slot 511 (i.e., FDM based transmission). PSFCH can be transmitted on interlace 0 in the last two available symbols (e.g., symbols 516 and 517 within slot 511, as symbols 515 and 518 are reserved for LBT testing).

[0075] As mentioned above, PSFCH multiplexing can be implemented in the frequency domain (e.g., partial interlaces), code domain (e.g., cyclic shifts, OCC, or both), or both. In these embodiments, in a given slot (e.g., symbols 516 and 517 within slot 511) within a PSFCH resource pool, there can be Z candidate PSFCH resources, where Z can be determined based on one or more of the following:

[0076] - the number of full interlaces (denoted as M) defined based on the subcarrier spacing of the carrier,

[0077] - the number of partial interlaces (denoted as N) per full interlace,

[0078] - the number of cyclic shifts (denoted as X) per full or partial interlace, and

[0079] - the number of frequency-domain OCCs (denoted as Y) per full or partial interlace.

[0080] The Z candidate PSFCH resources in a PSFCH resource pool can be indexed from “0” to “Z-1”. In some embodiments of the present disclosure, the number of PSFCH resources in a PSFCH resource pool (i.e., Z) can be determined according to Z = M x N x X x Y.

[0081] In some embodiments of the present disclosure, the number of PSFCH resources in a PSFCH resource pool (i.e., Z) can be the same as the number of full interlaces defined based on the subcarrier spacing of the carrier (i.e., Z = M). In these embodiments, HARQ-ACK feedback can be transmitted on a full interlace, which can be considered as a special case of PSFCH multiplexing. In the case of 10 interlaces (i.e., Z = M = 10) for a carrier with 15 kHz subcarrier spacing, the candidate PSFCH resources in a PSFCH resource pool can be indexed from “0” to “9”.

[0082] As will be described below, embodiments of the present disclosure provide solutions for determining a feedback resource to transmit HARQ-ACK feedback among multiple candidate PSFCH resources.

[0083] In some embodiments of the present disclosure, a joint PSFCH resource indication scheme can be employed to determine a feedback resource to transmit HARQ-ACK feedback.

[0084] As mentioned above, for unicast and groupcast Option 1 transmission, one feedback resource would be sufficient. In this case, in some embodiments of the present disclosure, the UE can transmit SCI indicating an index of a PSFCH resource out of multiple candidate PSFCH resources (e.g., Z candidate PSFCH resources) in a PSFCH resource pool. For example, the SCI can indicate a PSFCH resource n (n = 0, 1, …, or Z-1) as the feedback resource for transmitting HARQ-ACK feedback corresponding to data (e.g., PSSCH) scheduled by the SCI. The Rx UE can transmit the HARQ-ACK feedback on the PSFCH resource n based on the SCI. The value of the HARQ-ACK feedback can depend on the decoding result of the data.

[0085] In some embodiments of the present disclosure, the index of the PSFCH resource for transmitting the HARQ-ACK feedback can be determined implicitly according to certain criteria. The criteria can be configured by the BS or can be predefined according to, for example, industry standards. This is beneficial because it can save signaling overhead.

[0086] In some instances, a connection between the index of the PSFCH resource (denoted as z) and the slot index (denoted as i) and the interlace index (denoted as j) within a set of slots for data transmission can be established. The set of slots can include slots (e.g., slots 410-0 to 410-S-1 in FIG. 4B) that have corresponding PSFCH transmissions in the same slot. The value of j can be based on the interlace index for SCI transmission (e.g., interlace 0 in FIG. 4B), the interlace index for PSSCH transmission (e.g., interlace 0 or 5 in FIG. 4B), or a combination thereof (e.g., j = interlace index for SCI transmission + interlace index for PSSCH transmission). In the case where the SCI schedules multiple interlaces for PSSCH transmission (e.g., interlaces 0 and 5 in FIG. 4B), the interlace index for PSSCH transmission can be the lowest interlace index (e.g., interlace 0 in FIG. 4B), the highest interlace index (e.g., interlace 5 in FIG. 4B), or a preconfigured interlace index for the multiple interlaces for PSSCH transmission. Figure 4 Figure 5 Figure 5 Figure 5 Figure 5 Figure 5 In the above examples, PSFCH resource collision can be avoided because one interlace is typically used to transmit only one SCI in one slot.

[0087] ​​​​​The UE can determine the index of a PSFCH resource of the plurality of candidate PSFCH resources based on one or more of: M, i, and j. In some embodiments of the disclosure, the UE can determine the index of the PSFCH resource according to z = M x i + j. For example, assuming a PSSCH transmission is transmitted in the ith slot of the set of slots for the PSSCH transmission, where i >= 0, the UE can determine that the HARQ-ACK feedback corresponding to the PSSCH transmission will be transmitted on the PSFCH resource with index M x i + j.

[0088] In some cases, two or more Tx UEs in a UE group can simultaneously transmit SCI or PSSCH to the same Rx UE in the UE group on the same interlace. In this case, a PSFCH collision can occur due to the same slot and the same interlace. To resolve this potential collision, the ID of the Tx UE can be employed during the determination of the index of the PSFCH resource, e.g., the source ID of the Tx UE indicated in the associated SCI. For example, the index of the PSFCH resource can be determined according to z = (M x i + j + K1) mod Z, where K1 represents the source ID of the Tx UE, and Z represents the number of PSFCH resources in the PSFCH resource pool as described above. The source ID of a UE can include 16 bits, and can be indicated in the SCI from the UE.

[0089] For groupcast Option 2 transmissions, multiple feedback resources can be needed. In this case, in some embodiments of the disclosure, multiple sets of feedback resources for accommodating feedback from multiple UE groups can be configured by radio resource control (RRC) signaling from the BS to the UE. The feedback resources in the multiple sets of feedback resources can be from the multiple candidate PSFCH resources (Z candidate PSFCH resources in the PSFCH resource pool). In some instances, the number of feedback resources in the multiple sets of feedback resources can be different in order to provide different PSFCH resources for UE groups of different group sizes. In some instances, the number of feedback resources in the multiple sets of feedback resources can be the same.

[0090] From the perspective of a Tx UE transmitting an SCI, the Tx UE may select a feedback resource set from multiple feedback resource sets based on, for example, the number of member UEs in a UE group. The Tx UE may then indicate the selected feedback resource set in the SCI to be transmitted. From the perspective of an Rx UE intended to receive the SCI and associated data, the Rx UE may determine the corresponding feedback resource set based on the SCI. The Rx UE may implicitly determine the feedback resources in the determined feedback resource set for the corresponding PSFCH transmission based on a specific criterion. For example, the Rx UE may determine the feedback resources based on the result of modulo the number of feedback resources in the feedback resource set modulo the ID of the Rx UE in the UE group. That is, the feedback resources in the determined feedback resource set may be indexed from 0 to q-1, where q is the number of feedback resources in the determined feedback resource set; and the index of the determined feedback resource in the determined feedback resource set is the result of the above modulo operation. The Rx UE may then transmit HARQ-ACK feedback (e.g., ACK or NACK) on the determined feedback resources. The ID of the Rx UE in the UE group is configured by the Tx UE or the BS via higher layer (eg, RRC layer) signaling.

[0091] In some embodiments of the present disclosure, the index of the PSFCH resource used to transmit HARQ-ACK feedback can be implicitly determined based on specific criteria. The criteria can be configured by the base station or the Tx UE, or can be predefined according to, for example, an industry standard. This is beneficial because it can save signaling overhead.

[0092] In some examples, a link may be established between the index of the PSFCH resource (denoted as z) and the ID of the Rx UE receiving the multicast option 2 transmission (denoted as K2). For example, the UE may determine the index of the PSFCH resource for transmitting HARQ-ACK feedback among multiple candidate PSFCH resources based on one or more of the following:

[0093] - the number of slots (e.g., S) within a slot set used for PSSCH transmission, where the slot set contains slots that have corresponding PSFCH transmissions in the same slot; and

[0094] - Source ID of the Tx UE indicated in the SCI or the ID of the Tx UE in the UE group (e.g., K1);

[0095] - ID of the Rx UE in the UE group (e.g. K2); and

[0096] - The number of full interlaces (eg, M) defined based on the subcarrier spacing of the carrier.

[0097] In some embodiments of the disclosure, a UE can determine an index of a PSFCH resource according to z = (M x S + K1 + K2) mod Z, where Z represents a number of candidate PSFCH resources in a PSFCH resource pool, as stated above. In these embodiments, a first M x S candidate PSFCH resources of the Z candidate PSFCH resources in the PSFCH resource pool can be reserved for unicast transmission and groupcast option 1 transmission, and the remaining candidate PSFCH resources can be used for groupcast option 2 transmission.

[0098] In some embodiments of the disclosure, a separate PSFCH resource indication scheme can be used to determine the feedback resource to transmit HARQ-ACK feedback.

[0099] A separate PSFCH resource indication scheme can include one or more of the following steps: (1) slot determination; (2) full interlace determination or partial interlace determination; and (3) cyclic shift determination, OCC determination, or both. For example, a UE can determine a slot (i.e., time domain) in which to transmit HARQ-ACK feedback, determine a full interlace or partial interlace (i.e., frequency domain) on which to transmit HARQ-ACK feedback, and determine a cyclic shift, OCC, or both (i.e., code domain) used to generate HARQ-ACK feedback.

[0100] In some embodiments of the disclosure, slot determination can be based on resource pool (e.g., PSFCH resource pool) configuration. In some embodiments of the disclosure, slot determination can be based on received SCI. For example, SCI can indicate a slot-level offset between a slot of a data (e.g., PSSCH) transmission and a slot for a corresponding HARQ-ACK feedback (e.g., PSFCH) transmission. In some embodiments, a resource pool for PSFCH can be configured via a slot-based bitmap, e.g., using bits 0 or 1 indicating whether a corresponding slot is within the PSFCH resource pool. In this case, the aforementioned slot-level offset between PSSCH and PSFCH can not have to be included in the SCI.

[0101] In some embodiments of the disclosure, the unit for feedback resource allocation can be a full interlace. In these embodiments, in some instances, SCI can indicate an index of the full interlace. HARQ-ACK feedback corresponding to a data transmission scheduled by the SCI can be transmitted on the indicated full interlace.

[0102] In some other examples, the index of the slot for the feedback transmission can be determined implicitly. For example, the index of the slot for the PSFCH transmission can be the same as the index of the slot in which the SCI is detected. In other words, the HARQ-ACK feedback corresponding to the data transmission scheduled by the SCI can be transmitted on the same slot in which the SCI is detected. In another example, the index of the slot for the PSFCH transmission can be the same as the index of the slot on which the scheduled PSSCH is transmitted. In case the PSSCH transmission scheduled by the SCI is transmitted on multiple slots, the index of the slot for the PSFCH transmission can be the slot among the multiple slots for the PSSCH transmission that has the lowest slot index, the highest slot index, or a preconfigured slot index.

[0103] In some embodiments of the disclosure, the unit for feedback resource allocation can be a partial slot. In these embodiments, in some examples, the SCI can indicate the index of the full slot of the carrier and the index of the subband (e.g., LBT subband or RB set configured by RRC signaling). The HARQ-ACK feedback corresponding to the data transmission scheduled by the SCI can be transmitted on the partial slot of the full slot corresponding to the index of the subband of the carrier.

[0104] In some other examples, the SCI can only indicate the index of the subband of the carrier, but not the index of the full slot that can be determined implicitly. For example, the index of the full slot for the PSFCH transmission can be the same as the index of the full slot in which the SCI is detected. In another example, the index of the full slot for the PSFCH transmission can be the same as the index of the slot on which the scheduled PSSCH is transmitted. In case the PSSCH transmission scheduled by the SCI is transmitted on multiple slots, the index of the slot for the PSFCH transmission can be the slot among the multiple slots for the PSSCH transmission that has the lowest slot index, the highest slot index, or a preconfigured slot index.

[0105] In some other examples, the SCI can indicate the index of the partial slot. The HARQ-ACK feedback corresponding to the data transmission scheduled by the SCI can be transmitted on the indicated partial slot. For example, in case there are 10 slots for a certain carrier, and each slot is divided into 4 partial slots (e.g., a carrier with 15 kHz subcarrier spacing and 80 MHz bandwidth), the partial slots of the carrier can be jointly indexed from “0” to “39”. In this scenario, the partial slots can be identified by their indices.

[0106] In some embodiments of the disclosure, the SCI can indicate the cyclic shift, OCC, or both to be used for generating the HARQ-ACK feedback. In some embodiments of the disclosure, the cyclic shift, OCC, or both can be determined implicitly. For example, assume that the HARQ-ACK feedback is to be transmitted in one or more symbols (e.g., symbols 0-3) within a slot, and the SCI is detected in symbol 0 of the slot. In this case, the cyclic shift, OCC, or both for the HARQ-ACK feedback can be the same as the cyclic shift, OCC, or both used for the SCI. Figure 5If the cyclic shift is transmitted in time slots 516 and 517 in time slots 516 and 517, the cyclic shift, the OCC, or both may be determined based on at least one of the following:

[0107] - the index of the time slot within the radio frame;

[0108] - one or more symbols within a time slot (e.g. Figure 5 516 and 517 in the time slots); and

[0109] - one or more symbols relative to the first symbol of one or more symbols in the time domain (e.g., Figure 5 The index of the time slot 516 in .

[0110] HARQ-ACK feedback may be transmitted in a sequence, for example, one sequence indicating "ACK" and another sequence indicating "NACK." This sequence may be generated based on at least one of a cyclic shift and other information, such as a slot index or an OFDM symbol index. OCCs in the time or frequency domain may be used to multiplex multiple UEs in the same PRB used for PSFCH transmission. The index of the OCC in the time or frequency domain may be configured or implicitly indicated by higher-layer (e.g., RRC layer) signaling.

[0111] For example, the sequence x(n) should be calculated according to Generate, where n is the index of each element of the sequence and depends on the length of the sequence. The cyclic shift α varies with the number of symbols and time slots. l is the number of OFDM symbols in the PSFCH transmission, where l = 0 corresponds to the first OFDM symbol of the PSFCH transmission; l' is the index of the OFDM symbol in the time slot corresponding to the first OFDM symbol of the PSFCH transmission in the time slot; m0 is given by the index of the cyclic shift pair; m cs Determined based on ACK or NACK; and if PUCCH should use interleaved mapping, then m int By PUCCH format 0 and 1 Given, where is the number of resource blocks in the interleave, otherwise m int = 0. Function n cs (n c ,l)by Given, where c(i) is a pseudo-random sequence. The pseudo-random sequence generator should be initialized to c init =n ID , where if configured, then n ID Given by the higher layer parameter Hopping ID, otherwise The above parameters for determining cyclic shift and OCC are defined in 3GPP specifications TS 38.211 and TS 38.213.

[0112] Figure 6 A flowchart illustrating an exemplary procedure 600 for wireless communication in accordance with some embodiments of the present disclosure is shown.

[0113] Exemplary procedure 600 shows a procedure for a UE (e.g., UE 310b in Figure 3 ) to communicate with another UE (e.g., UE 310a in Figure 3 ). The details described in all the foregoing embodiments of the present disclosure apply to the embodiments shown in Figure 6 .

[0114] Referring to Figure 6 , in operation 611, a UE (e.g., UE 310b in Figure 3 ) can receive sidelink control information (SCI) from another UE (e.g., UE 310a in Figure 3 ) on a stagger on a carrier. The SCI can be transmitted in a unicast transmission or a groupcast transmission (option 1 or option 2). The SCI can schedule a data transmission (e.g., PSSCH) on the carrier. The stagger on which the SCI is detected can include uniformly spaced resource blocks (RBs) in the frequency domain. The UE can receive the data transmission (e.g., PSSCH) from the other UE according to the SCI (not shown in Figure 6 ). In operation 613, the UE (e.g., UE 310b in Figure 3 ) can transmit HARQ-ACK feedback corresponding to the data transmission on a feedback resource to the other UE (e.g., UE 310a in Figure 3 ) based on the SCI.

[0115] In some embodiments of the present disclosure, the feedback resource can be from a plurality of feedback resources, e.g., Z candidate PSFCH resources in a PSFCH resource pool as described above with respect to Figures 2 to 5 . In some embodiments of the present disclosure, the SCI can indicate an index of the feedback resource from the plurality of feedback resources. In some embodiments of the present disclosure, the UE can implicitly determine the index of the feedback resource from the plurality of feedback resources as described above with respect to Figures 2 to 5 . For example, the index of the feedback resource can be determined based on the equation z = M x i + j, z = (M x i + j + K1) mod Z, or z = (M x S + K1 + K2) mod Z.

[0116] In some embodiments of the present disclosure, the UE can further receive radio resource control (RRC) signaling. The RRC signaling can indicate a plurality of sets of feedback resources for accommodating feedback from a plurality of groups of UEs as described above with respect to Figures 2 to 5 . In these embodiments, the received SCI can include an index of a set of feedback resources from the plurality of sets of feedback resources. The UE can transmit the HARQ-ACK feedback according to the set of feedback resources as described above with respect to Figures 2 to 5The described method determines a feedback resource from the indicated set of feedback resources. For example, the UE can determine an index of a feedback resource in the indicated set of feedback resources based on a result of the UE’s ID modulo a number of feedback resources in the indicated set of feedback resources.

[0117] In some embodiments of the disclosure, the UE can further determine a slot for transmission of the HARQ-ACK feedback based on a resource pool configuration or received SCI. The received SCI can indicate a slot-level offset between a slot for data transmission and a slot for corresponding HARQ-ACK feedback transmission. The UE can also determine one or more symbols within the slot for transmission of the HARQ-ACK feedback.

[0118] In these embodiments, the UE can further determine a full interlace or a partial interlace for transmission of the HARQ-ACK feedback based on the received SCI, as described above with respect to Figures 2 to 5 For example, the SCI can indicate an index of a full interlace on which to transmit the HARK-ACK feedback.

[0119] In these embodiments, the UE can further generate the HARQ-ACK feedback using a cyclic shift, an orthogonal cover code (OCC), or both. As described above with respect to Figures 2 to 5 The index of the cyclic shift or the index of the OCC or both can be indicated in the received SCI or can be determined implicitly, as described above with respect to

[0120] Those skilled in the art will appreciate that the order of the operations in the exemplary process 600 can be changed, and that some of the operations in the exemplary process 600 can be eliminated or modified, without departing from the spirit and scope of the disclosure.

[0121] Figure 7 A flowchart illustrating an exemplary process 700 for wireless communication in accordance with some embodiments of the disclosure is shown.

[0122] The exemplary process 700 shows a process by which a UE (e.g., the UE 310a in Figure 3 communicates with another UE (e.g., the UE 310b in Figure 3 The details described in all the preceding embodiments of the disclosure are applicable to the embodiments shown in Figure 7 .

[0123] Referring to Figure 7 , in operation 711, a UE (e.g., the UE 310a in Figure 3 may transmit sidelink control information (SCI) to another UE (e.g., the UE 310b in Figure 3SCI can be transmitted in a unicast transmission or a groupcast transmission (Option 1 or Option 2). The SCI can schedule a data transmission (e.g., PSSCH) on a carrier. The interlace on which the SCI is transmitted can contain uniformly spaced resource blocks (RBs) in the frequency domain. The UE can transmit a data transmission (e.g., PSSCH) to another UE according to the SCI (e.g., as shown in FIG. 6B). Figure 7 In operation 713, the UE (e.g., UE 310a in FIG. 6B) can receive a HARQ-ACK feedback from the other UE (e.g., UE 310b in FIG. 6B) corresponding to the data transmission on the feedback resource. Figure 3 In operation 713, the UE (e.g., UE 310a in FIG. 6B) can receive a HARQ-ACK feedback from the other UE (e.g., UE 310b in FIG. 6B) corresponding to the data transmission on the feedback resource. Figure 3 In operation 713, the UE (e.g., UE 310a in FIG. 6B) can receive a HARQ-ACK feedback from the other UE (e.g., UE 310b in FIG. 6B) corresponding to the data transmission on the feedback resource.

[0124] In some embodiments of the disclosure, the feedback resource can be from a plurality of feedback resources, e.g., Z candidate PSFCH resources in a PSFCH resource pool as described above with respect to Figures 2 to 5 In some embodiments of the disclosure, the SCI can indicate an index of the feedback resource from the plurality of feedback resources. In some embodiments of the disclosure, the index of the feedback resource from the plurality of feedback resources can be determined according to a method as described above with respect to Figures 2 to 5 For example, the index of the feedback resource can be determined based on the equation z = M x i + j, z = (M x i + j + K1) mod Z, or z = (M x S + K1 + K2) mod Z.

[0125] In some embodiments of the disclosure, the UE can further receive a radio resource control (RRC) signaling. The RRC signaling can indicate a plurality of feedback resource sets for accommodating feedback from a plurality of UE groups as described above with respect to Figures 2 to 5 In these embodiments, the UE can select a feedback resource set from the plurality of feedback resource sets according to a method as described above with respect to Figures 2 to 5 In some embodiments of the disclosure, the SCI can indicate an index of the feedback resource from the plurality of feedback resources. In some embodiments of the disclosure, the index of the feedback resource from the plurality of feedback resources can be determined according to a method as described above with respect to Figures 2 to 5 For example, the UE can determine the index of the feedback resource from the indicated feedback resource set based on a result of taking a modulo of a number of feedback resources in the indicated feedback resource set with an ID of the UE in the UE group.

[0126] In some embodiments of the disclosure, the configured or preconfigured resource pool configuration or the SCI can indicate a slot-level offset between a slot for a data transmission and a slot for a corresponding HARQ-ACK feedback transmission. Based on this, the UE can determine the slot for the HARQ-ACK feedback. The UE can also determine one or more symbols within the slot for the HARQ-ACK feedback.

[0127] In these embodiments, in some instances, the SCI transmitted by the UE can further indicate information related to full or partial interlacing for HARQ-ACK feedback, as described above with respect to Figures 2 to 5 In some other instances, full or partial interlacing for HARQ-ACK feedback can be determined implicitly, as described above with respect to Figures 2 to 5 For example, the index of the interlace for HARQ-ACK feedback can be the same as the index of the interlace on which the SCI is transmitted or the index of the interlace on which the scheduled PSSCH is transmitted.

[0128] In these embodiments, the UE can further decode the received HARQ-ACK feedback using a cyclic shift, an orthogonal cover code (OCC), or both. As described above with respect to Figures 2 to 5 The index of the cyclic shift or the index of the OCC, or both, can be indicated in the SCI or can be determined implicitly, as described above with respect to

[0129] Those skilled in the art will appreciate that the order of the operations of exemplary process 700 can be changed, and that some of the operations of exemplary process 700 can be eliminated or modified, without departing from the spirit and scope of the disclosure.

[0130] Figure 8 An example block diagram of a device 800 according to some embodiments of the disclosure is illustrated. The details described in all the foregoing embodiments of the disclosure are applicable to Figure 8 the embodiments shown in

[0131] As shown in Figure 8 device 800 can include at least one non-transitory computer-readable medium (not shown in Figure 8 ), at least one receiving circuitry 802, at least one transmitting circuitry 804, and at least one processor 806 coupled to the non-transitory computer-readable medium (not shown in Figure 8 ), at least one receiving circuitry 802, and at least one transmitting circuitry 804. Device 800 can be a UE.

[0132] Although in this figure elements such as the at least one processor 806, the transmitting circuitry 804, and the receiving circuitry 802 are described with a singular, it is contemplated that a plural is intended unless specifically stated to the contrary. In some embodiments of the disclosure, the receiving circuitry 802 and the transmitting circuitry 804 are combined into a single device, such as a transceiver. In certain embodiments of the disclosure, the device 800 can further include an input device, a memory, and / or other components.

[0133] In some embodiments of the disclosure, a non-transitory computer- readable medium can have stored thereon computer-executable instructions to cause a processor to implement operations for a UE as described above. For example, when executed, the computer-executable instructions cause the processor 806 to interact with the reception circuitry 802 and the transmission circuitry 804 to perform operations for a UE as described above with respect to Figures 1 to 7 In some embodiments of the disclosure, a non-transitory computer- readable medium can have stored thereon computer-executable instructions to cause a processor to implement operations for a UE as described above. For example, when executed, the computer-executable instructions cause the processor 806 to interact with the reception circuitry 802 and the transmission circuitry 804 to perform operations for a UE as described above with respect to

[0134] In some examples, the reception circuitry 802 can receive sidelink control information (SCI) on a interlace on a carrier. The SCI can schedule a data transmission on the carrier. The interlace can include uniformly spaced resource blocks (RBs) in the frequency domain. The transmission circuitry 804 can transmit, on a feedback resource, HARQ-ACK feedback corresponding to the data transmission based on the SCI. In some embodiments of the disclosure, the processor 806 can determine the feedback resource in accordance with one of the methods described above with respect to Figures 1 to 7 In some examples, the reception circuitry 802 can receive sidelink control information (SCI) on a interlace on a carrier. The SCI can schedule a data transmission on the carrier. The interlace can include uniformly spaced resource blocks (RBs) in the frequency domain. The transmission circuitry 804 can transmit, on a feedback resource, HARQ-ACK feedback corresponding to the data transmission based on the SCI. In some embodiments of the disclosure, the processor 806 can determine the feedback resource in accordance with one of the methods described above with respect to

[0135] In some examples, the transmission circuitry 804 can transmit sidelink control information (SCI) on a interlace on a carrier. The SCI can schedule a data transmission on the carrier. The interlace can include uniformly spaced resource blocks (RBs) in the frequency domain. The reception circuitry 802 can receive, on a feedback resource, HARQ-ACK feedback corresponding to the data transmission based on the SCI. In some embodiments of the disclosure, the processor 806 can determine the feedback resource in accordance with one of the methods described above with respect to Figures 1 to 7 In some examples, the transmission circuitry 804 can transmit sidelink control information (SCI) on a interlace on a carrier. The SCI can schedule a data transmission on the carrier. The interlace can include uniformly spaced resource blocks (RBs) in the frequency domain. The reception circuitry 802 can receive, on a feedback resource, HARQ-ACK feedback corresponding to the data transmission based on the SCI. In some embodiments of the disclosure, the processor 806 can determine the feedback resource in accordance with one of the methods described above with respect to

[0136] One of ordinary skill in the art will appreciate that the steps of the methods described in connection with the aspects disclosed herein can be embodied directly in hardware, in software executed by a processor, or in a combination of the two. Software modules can reside in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, a removable media, a CD-ROM, or any other form of storage medium known in the art. Furthermore, in some aspects, the steps of the methods can reside in one or any combination or set of codes and / or instructions that can be resident on a non-transitory computer-readable medium, which can be incorporated into a computer program product.

[0137] While the present disclosure has been described with reference to specific embodiments thereof, it is evident that many alternatives, modifications and variations can be apparent to those skilled in the art. For instance, various components of the embodiments can be interchanged, added, or removed in other embodiments. Additionally, not all of the elements of each figure are necessary for operation of the disclosed embodiments. For example, one of ordinary skill in the art of the disclosed embodiments will be able to construct and use the teachings of this disclosure with merely a simple application of the elements of the independent claims. Accordingly, the embodiments of the present disclosure as set forth herein are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the present disclosure.

[0138] In this document, the terms“includes / including” or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by“a” or“an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus including the recited element. Additionally, the term“another” is defined as at least a second or more. The terms“has” and“having,” among others, are defined as“including.”

Claims

1. A method for wireless communication performed by a first user equipment (UE), comprising: receiving, from a second UE, a sidelink control information (SCI) on a first interlace on a carrier, wherein the SCI schedules a data transmission on the carrier, and the first interlace comprises uniformly spaced resource blocks (RBs) in a frequency domain; and transmitting, from the first UE, a hybrid automatic repeat request-acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource based on the SCI, wherein the first feedback resource is from a plurality of feedback resources, and a number of feedback resources in the plurality of feedback resources is determined based on a number of interlaces and a number of cyclic shifts that depend on a subcarrier spacing of the carrier.

2. The method of claim 1, wherein each interlace is divided into the number of partial interlaces based on a subband of the carrier.

3. The method of claim 1, wherein the SCI indicates an index of the first feedback resource in the plurality of feedback resources.

4. The method of claim 1, further comprising determining an index of the first feedback resource in the plurality of feedback resources based on one or more of: a number of interlaces that depend on a subcarrier spacing of the carrier; a slot index of a slot for the data transmission within a set of slots, wherein the set of slots includes slots with corresponding physical sidelink feedback channel (PSFCH) transmissions in a same slot; and an interlace index, wherein the interlace index is based on an index of the first interlace, an index of an interlace for the data transmission, or a combination thereof.

5. The method of claim 4, wherein the index of the first feedback resource is determined by M x i + j, where M represents the number of interlaces that depend on a subcarrier spacing of the carrier, i represents the slot index, and j represents the interlace index.

6. The method of claim 4, wherein the first UE and the second UE are from a group of UEs, and the index of the first feedback resource is further determined based on an ID of the second UE in the group of UEs.

7. The method of claim 1, further comprising: receiving radio resource control (RRC) signaling, wherein the RRC signaling indicates a plurality of sets of feedback resources for accommodating feedback from a plurality of groups of UEs.

8. The method of claim 7, wherein the SCI indicates an index of a first set of feedback resources in the plurality of sets of feedback resources.

9. The method of claim 8, further comprising: determining the first feedback resource from the first set of feedback resources in the plurality of sets of feedback resources.

10. The method of claim 9, wherein the first UE and the second UE are from a group of UEs, and determining the first feedback resource comprises: determining the index of the first feedback resource in the first set of feedback resources based on a result of a modulo operation on a number of feedback resources in the first set of feedback resources based on an ID of the first UE in the group of UEs.

11. The method of claim 1, wherein the first UE and the second UE are from a group of UEs, and the method further comprises: determining an index of the first feedback resource of the plurality of feedback resources based on one or more of: a number of slots within a set of slots, wherein the set of slots includes slots having corresponding physical sidelink feedback channel, PSFCH, transmissions in a same slot; an ID of the first UE in the group of UEs; an ID of the second UE in the group of UEs; and a number of interlaces of a subcarrier spacing of the carrier.

12. The method of claim 11, wherein the index of the first feedback resource is determined by (M*S+K1+K2) mod Z, where S represents the number of slots within the set of slots, M represents the number of interlaces, K1 represents the ID of the second UE, K2 represents the ID of the first UE, and Z represents a number of feedback resources in the plurality of feedback resources.

13. The method of claim 1, wherein the SCI indicates an index of a second interlace, and the first feedback resource is transmitted on the second interlace.

14. The method of claim 1, wherein the SCI indicates an index of a second interlace and an index of a subband of the carrier, and the first feedback resource is transmitted on a partial interlace of the second interlace corresponding to the index of the subband of the carrier.

15. The method of claim 1, wherein the SCI indicates an index of a partial interlace, and the first feedback resource is transmitted on the partial interlace.

16. The method of claim 1, wherein the first feedback resource is transmitted on the first interlace.

17. The method of claim 1, wherein the SCI indicates an index of a subband of the carrier, and the first feedback resource is transmitted on a partial interlace of the first interlace corresponding to the index of the subband of the carrier.

18. The method of claim 1, wherein the first feedback resource is transmitted on an interlace for the data transmission.

19. The method of claim 1, wherein the SCI indicates an index of a subband of the carrier, and the first feedback resource is transmitted on a partial interlace of an interlace for the data transmission corresponding to the index of the subband of the carrier.

20. The method of any one of claims 4, 18, or 19, wherein the interlace for the data transmission is an interlace having a lowest or highest interlace index among a plurality of interlaces for the data transmission scheduled by the SCI.

21. The method of any one of claims 13-19, wherein the HARQ-ACK feedback is transmitted in one or more symbols within a slot, and the method further comprises: generating the HARQ-ACK feedback using a cyclic shift, an orthogonal cover code, OCC, or both, ​ wherein an index of the cyclic shift or an index of the OCC, or both, are indicated in the SCI; or at least one of the index of the cyclic shift and the index of the OCC is determined based on one or more of: an index of the slot within a radio frame, an index of the one or more symbols within the slot, and an index of the one or more symbols relative to a first symbol of the one or more symbols in time domain.

22. The method of claim 21, further comprising: determining the slot for transmitting the HARQ-ACK feedback based on a resource pool configuration or based on the SCI, wherein the SCI indicates a slot-level offset between a slot for data transmission and a slot for corresponding HARQ-ACK feedback transmission.

23. A method performed by a second user equipment (UE), comprising: transmitting, to a first UE, a sidelink control information (SCI) on a first interlace on a carrier, wherein the SCI schedules a data transmission on the carrier and the first interlace comprises uniformly spaced resource blocks (RBs) in a frequency domain; and receiving, from the first UE, a hybrid automatic repeat request-acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource based on the SCI, wherein the first feedback resource is from a plurality of feedback resources and a number of feedback resources in the plurality of feedback resources is determined based on a number of interlaces and a number of cyclic shifts that depend on a subcarrier spacing of the carrier.

24. The method of claim 23, wherein each interlace is divided into the number of partial interlaces based on a subband of the carrier.

25. The method of claim 23, wherein the SCI indicates an index of the first feedback resource in the plurality of feedback resources.

26. The method of claim 23, wherein an index of the first feedback resource in the plurality of feedback resources is based on one or more of: a number of interlaces that depend on a subcarrier spacing of the carrier; a slot index of a slot for the data transmission within a set of slots, wherein the set of slots includes slots having corresponding physical sidelink feedback channel (PSFCH) transmissions in a same slot; and an interlace index, wherein the interlace index is based on an index of the first interlace, an index of an interlace for the data transmission, or a combination thereof.

27. The method of claim 26, wherein the index of the first feedback resource is determined by M x i + j, where M represents the number of interlaces that depend on a subcarrier spacing of the carrier, i represents the slot index, and j represents the interlace index.

28. The method of claim 26, wherein the first UE and the second UE are from a group of UEs, and the index of the first feedback resource is further based on an ID of the second UE in the group of UEs.

29. The method of claim 23, further comprising: receiving radio resource control (RRC) signaling, wherein the RRC signaling indicates a plurality of sets of feedback resources for accommodating feedback from a plurality of groups of UEs.

30. The method of claim 29, wherein the SCI indicates an index of a first set of feedback resources of the plurality of sets of feedback resources.

31. The method of claim 30, further comprising: determining the first feedback resource from the first set of feedback resources of the plurality of sets of feedback resources.

32. The method of claim 31, wherein the first UE and the second UE are from a group of UEs, and determining the first feedback resource comprises: determining the index of the first feedback resource of the first set of feedback resources based on a result of a modulo operation on a number of feedback resources in the first set of feedback resources based on an ID of the first UE in the group of UEs.

33. The method of claim 23, wherein the first UE and the second UE are from a group of UEs, and the method further comprises: determining an index of the first feedback resource of the plurality of feedback resources based on one or more of: a number of slots within a set of slots, wherein the set of slots includes slots having corresponding physical sidelink feedback channel, PSFCH, transmissions in a same slot; an ID of the first UE in the group of UEs; an ID of the second UE in the group of UEs; and a number of interlaces dependent on a subcarrier spacing of the carrier.

34. The method of claim 33, wherein the index of the first feedback resource is determined by (M*S+K1+K2) mod Z, where S represents the number of slots within the set of slots, M represents the number of interlaces, K1 represents the ID of the second UE, K2 represents the ID of the first UE, and Z represents a number of the feedback resources of the plurality of feedback resources.

35. The method of claim 23, wherein the SCI indicates an index of a second interlace, and the first feedback resource is received on the second interlace.

36. The method of claim 23, wherein the SCI indicates an index of a second interlace and an index of a subband of the carrier, and the first feedback resource is received on a partial interlace of the second interlace corresponding to the index of the subband of the carrier.

37. The method of claim 23, wherein the SCI indicates an index of a partial interlace, and the first feedback resource is received on the partial interlace.

38. The method of claim 23, wherein the first feedback resource is received on the first interlace.

39. The method of claim 23, wherein the SCI indicates an index of a subband of the carrier, and the first feedback resource is received on a partial interlace of the first interlace corresponding to the index of the subband of the carrier.

40. The method of claim 23, wherein the first feedback resource is received on an interlace for the data transmission.

41. The method of claim 23, wherein the SCI indicates an index of a subband of the carrier, and the first feedback resource is received on a partial interlace of an interlace for the data transmission corresponding to the index of the subband of the carrier.

42. The method of any one of claims 26, 40, or 41, wherein the interlace for the data transmission is an interlace having a lowest or highest interlace index among a plurality of interlaces for the data transmission scheduled by the SCI.

43. The method of any one of claims 35-41, wherein the HARQ-ACK feedback is received in one or more symbols within a slot, and the method further comprises: decoding the HARQ-ACK feedback using a cyclic shift, an orthogonal cover code (OCC), or both, wherein an index of the cyclic shift or an index of the OCC, or both, are indicated in the SCI; or at least one of the index of the cyclic shift and the index of the OCC is determined based on one or more of: an index of the slot within a radio frame, an index of the one or more symbols within the slot, and an index of the one or more symbols relative to a first symbol among the one or more symbols in the time domain.

44. The method of claim 43, wherein the slot is determined according to a resource pool configuration or according to a slot-level offset between a slot for a data transmission and a slot for a corresponding HARQ-ACK feedback transmission, and the SCI indicates the slot-level offset.

45. A first user equipment (UE) comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the first UE to: receive, from a second UE, sidelink control information (SCI) on a first interlace on a carrier, wherein the SCI schedules a data transmission on the carrier, and the first interlace comprises uniformly spaced resource blocks (RBs) in a frequency domain; and transmit, based on the SCI, hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource, wherein the first feedback resource is from a plurality of feedback resources, and a number of feedback resources in the plurality of feedback resources is determined based on a number of interlaces and a number of cyclic shifts that depend on a subcarrier spacing of the carrier.

46. A second user equipment (UE) comprising: at least one memory; and at least one processor coupled with the at least one memory and configured to cause the second UE to: transmit, to a first UE, sidelink control information (SCI) on a first interlace on a carrier, wherein the SCI schedules a data transmission on the carrier, and the first interlace comprises uniformly spaced resource blocks (RBs) in a frequency domain; and receive, from the first UE, based on the SCI, hybrid automatic repeat request acknowledgement (HARQ-ACK) feedback corresponding to the data transmission on a first feedback resource, wherein the first feedback resource is from a plurality of feedback resources, and a number of feedback resources in the plurality of feedback resources is determined based on a number of interlaces and a number of cyclic shifts that depend on a subcarrier spacing of the carrier.

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