Patent Description:
The following abbreviations are herewith defined, at least some of which are referred to within the following description: Third Generation Partnership Project ("3GPP"), <NUM> QoS Indicator ("5QI"), Acknowledge Mode ("AM"), Backhaul ("BH"), Broadcast Multicast ("BM"), Buffer Occupancy ("BO"), Base Station ("BS"), Buffer Status Report ("BSR"), Bandwidth ("BW"), Bandwidth Part ("BWP"), Component Carrier ("CC"), Code Division Multiplexing ("CDM"), Control Element ("CE"), Coordinated Multipoint ("CoMP"), Categories of Requirements ("CoR"), Control Resource Set ("CORESET"), Cyclic Prefix ("CP"), Cyclic Prefix OFDM ("CP-OFDM"), CSI-RS Resource Indicator ("CRI"), Cell RNTI ("C-RNTI"), Channel State Information ("CSI"), CSI IM ("CSI-IM"), CSI RS ("CSI-RS"), Channel Quality Indicator ("CQI"), Central Unit ("CU"), Codeword ("CW"), Downlink Assignment Index ("DAI"), Downlink Control Information ("DCI"), Downlink ("DL"), Discrete Fourier Transform Spread OFDM ("DFT-s-OFDM"), Demodulation Reference Signal ("DMRS" or "DM-RS"), Data Radio Bearer ("DRB"), Dedicated Short-Range Communications ("DSRC"), Distributed Unit ("DU"), Enhanced Mobile Broadband ("eMBB"), Evolved Node B ("eNB"), Enhanced Subscriber Identification Module ("eSIM"), Enhanced ("E"), Frequency Division Duplex ("FDD"), Frequency Division Multiple Access ("FDMA"), Frequency Range ("FR"), <NUM> - <NUM> ("FR1"), <NUM> - <NUM> ("FR2"), Hybrid Automatic Repeat Request ("HARQ"), High-Definition Multimedia Interface ("HDMI"), Integrated Access Backhaul ("IAB"), Identity or Identifier or Identification ("ID"), Information Element ("IE"), Interference Measurement ("IM"), International Mobile Subscriber Identity ("IMSI"), Internet-of-Things ("IoT"), Internet Protocol ("IP"), Joint Transmission ("JT"), Level <NUM> ("L1"), L1 RSRP ("L1-RSRP"), L1 SINR ("L1-SINR"), Logical Channel ("LCH"), Logical Channel Group ("LCG"), Logical Channel ID ("LCID"), Logical Channel Prioritization ("LCP"), Layer Indicator ("LI"), Long Term Evolution ("LTE"), Levels of Automation ("LoA"), Medium Access Control ("MAC"), Modulation Coding Scheme ("MCS"), Multi DCI ("M-DCI"), Master Information Block ("MIB"), Multiple Input Multiple Output ("MIMO"), Mobile-Termination ("MT"), Machine Type Communication ("MTC"), Multi PDSCH ("Multi-PDSCH"), Multi TRP ("M-TRP"), Multi-User ("MU"), Multi-User MIMO ("MU-MIMO"), Minimum Mean Square Error ("MMSE"), Negative-Acknowledgment ("NACK") or ("NAK"), Next Generation ("NG"), Next Generation Node B ("gNB"), New Radio ("NR"), Non-Zero Power ("NZP"), NZP CSI-RS ("NZP-CSI-RS"), Orthogonal Frequency Division Multiplexing ("OFDM"), Peak-to-Average Power Ratio ("PAPR"), Physical Broadcast Channel ("PBCH"), Physical Downlink Control Channel ("PDCCH"), Physical Downlink Shared Channel ("PDSCH"), PDSCH Configuration ("PDSCH-Config"), Policy Control Function ("PCF"), Packet Data Convergence Protocol ("PDCP"), Packet Data Network ("PDN"), Protocol Data Unit ("PDU"), Public Land Mobile Network ("PLMN"), Precoding Matrix Indicator ("PMI"), ProSe Per Packet Priority ("PPPP"), ProSe Per Packet Reliability ("PPPR"), Physical Resource Block ("PRB"), Packet Switched ("PS"), Physical Sidelink Control Channel ("PSCCH"), Physical Sidelink Shared Channel ("PSSCH"), Phase Tracking RS ("PTRS" or "PT-RS"), Physical Uplink Control Channel ("PUCCH"), Physical Uplink Shared Channel ("PUSCH"), Quasi Co-Located ("QCL"), Quality of Service ("QoS"), Random Access Channel ("RACH"), Radio Access Network ("RAN"), Radio Access Technology ("RAT"), Resource Element ("RE"), Radio Frequency ("RF"), Rank Indicator ("RI"), Radio Link Control ("RLC"), Radio Link Failure ("RLF"), Radio Network Temporary Identifier ("RNTI"), Resource Pool ("RP"), Radio Resource Control ("RRC"), Reference Signal ("RS"), Reference Signal Received Power ("RSRP"), Reference Signal Received Quality ("RSRQ"), Receive ("RX"), Single Carrier Frequency Domain Spread Spectrum ("SC-FDSS"), Secondary Cell ("SCell"), Sub Carrier Spacing ("SCS"), Single DCI ("S-DCI"), Service Data Unit ("SDU"), Subscriber Identity Module ("SIM"), Signal-to-Interference Ratio ("SINR"), Sidelink ("SL"), Sequence Number ("SN"), Scheduling Request ("SR"), SRS Resource Indicator ("SRI"), Sounding Reference Signal ("SRS"), Synchronization Signal ("SS"), SS/PBCH Block ("SSB"), Transport Block ("TB"), Transmission Configuration Indicator ("TCI"), Time Division Duplex ("TDD"), Temporary Mobile Subscriber Identity ("TMSI"), Transmitted Precoding Matrix Indicator ("TPMI"), Transmission Reception Point ("TRP"), Technical Standard ("TS"), Transmit ("TX"), User Entity/Equipment (Mobile Terminal) ("UE"), Universal Integrated Circuit Card ("UICC"), Uplink ("UL"), Unacknowledged Mode ("UM"), Universal Mobile Telecommunications System ("UMTS"), LTE Radio Interface ("Uu interface"), User Plane ("UP"), Universal Subscriber Identity Module ("USIM"), Universal Terrestrial Radio Access Network ("UTRAN"), Vehicle to Everything ("V2X"), Voice Over IP ("VoIP"), Visited Public Land Mobile Network ("VPLMN"), Vehicle RNTI ("V-RNTI"), Worldwide Interoperability for Microwave Access ("WiMAX"), Zero Forcing ("ZF"), Zero Power ("ZP"), and ZP CSI-RS ("ZP-CSI-RS"). As used herein, "HARQ-ACK" may represent collectively the Positive Acknowledge ("ACK") and the Negative Acknowledge ("NAK"). ACK means that a TB is correctly received while NAK means a TB is erroneously received.

In certain wireless communications networks, HARQ-ACK may be used. In such networks, more resources may be allocated than are used.

<NPL>, and proposes that the RAN1 group should further discuss about the TX UE behavior on SL HARQ feedback reporting to gNB on PUCCH, if the SL HARQ feedback is not enabled by the TX UE.

<FIG> depicts an embodiment of a wireless communication system <NUM> for transmitting and/or receiving feedback for sidelink transmissions. In one embodiment, the wireless communication system <NUM> includes remote units <NUM> and network units <NUM>. Even though a specific number of remote units <NUM> and network units <NUM> are depicted in <FIG>, one of skill in the art will recognize that any number of remote units <NUM> and network units <NUM> may be included in the wireless communication system <NUM>.

In one embodiment, the remote units <NUM> may include computing devices, such as desktop computers, laptop computers, personal digital assistants ("PDAs"), tablet computers, smart phones, smart televisions (e.g., televisions connected to the Internet), set-top boxes, game consoles, security systems (including security cameras), vehicle on-board computers, network devices (e.g., routers, switches, modems), IoT devices, or the like. The remote units <NUM> may communicate directly with one or more of the network units <NUM> via UL communication signals and/or the remote units <NUM> may communicate directly with other remote units <NUM> via sidelink communication.

In certain embodiments, a network unit <NUM> may also be referred to as an access point, an access terminal, a base, a base station, a Node-B, an eNB, a gNB, a Home Node-B, a RAN, a relay node, a device, a network device, an IAB node, a donor IAB node, or by any other terminology used in the art.

In one implementation, the wireless communication system <NUM> is compliant with the <NUM> or NG (Next Generation) standard of the 3GPP protocol, wherein the network unit <NUM> transmits using NG RAN technology. More generally, however, the wireless communication system <NUM> may implement some other open or proprietary communication protocol, for example, WiMAX, among other protocols.

In various embodiments, a remote unit <NUM> may receive information from a network device (e.g., network unit <NUM>) indicating a plurality of resources for sidelink transmission and one or more resources for feedback. In certain embodiments, the remote unit <NUM> may transmit sidelink data using the plurality of resources for sidelink transmission. In various embodiments, the remote unit <NUM> may transmit feedback to the network device using the one or more resources for feedback based on the transmission of the sidelink data, wherein transmitting the feedback comprises: transmitting only a negative acknowledgment on a first at least one resource of the one or more resources for feedback in response to sidelink feedback not being used for the transmission of the sidelink data; transmitting only a positive acknowledgment or no acknowledgment on a second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the transmission of the sidelink data; or a combination thereof. Accordingly, a remote unit <NUM> may be used for transmitting feedback for sidelink transmissions.

In some embodiments, a network unit <NUM> may receive feedback for sidelink transmissions includes transmitting information from a network device (e.g., the network unit <NUM>) indicating a plurality of resources for sidelink transmission and one or more resources for feedback. In certain embodiments, the network unit <NUM> may receive feedback at the network device using the one or more resources for feedback, wherein receiving the feedback comprises: receiving only a negative acknowledgment on a first at least one resource of the one or more resources for feedback in response to sidelink feedback not being used for the sidelink transmission; receiving only a positive acknowledgment or no acknowledgment on a second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the sidelink transmission; or a combination thereof. Accordingly, a network unit <NUM> may be used for receiving feedback for sidelink transmissions.

<FIG> depicts one embodiment of an apparatus <NUM> that may be used for transmitting feedback for sidelink transmissions. The apparatus <NUM> includes one embodiment of the remote unit <NUM>. Furthermore, the remote unit <NUM> may include a processor <NUM>, a memory <NUM>, an input device <NUM>, a display <NUM>, a transmitter <NUM>, and a receiver <NUM>. In some embodiments, the input device <NUM> and the display <NUM> are combined into a single device, such as a touchscreen. In certain embodiments, the remote unit <NUM> may not include any input device <NUM> and/or display <NUM>. In various embodiments, the remote unit <NUM> may include one or more of the processor <NUM>, the memory <NUM>, the transmitter <NUM>, and the receiver <NUM>, and may not include the input device <NUM> and/or the display <NUM>.

In various embodiments, the receiver <NUM> receives information from a network device (e.g., the network unit <NUM>) indicating a plurality of resources for sidelink transmission and one or more resources for feedback. In some embodiments, the transmitter <NUM>: transmits sidelink data using the plurality of resources for sidelink transmission; and transmits feedback to the network device using the one or more resources for feedback based on the transmission of the sidelink data, wherein transmitting the feedback comprises: transmitting only a negative acknowledgment on a first at least one resource of the one or more resources for feedback in response to sidelink feedback not being used for the transmission of the sidelink data; transmitting only a positive acknowledgment or no acknowledgment on a second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the transmission of the sidelink data; or a combination thereof.

<FIG> depicts one embodiment of an apparatus <NUM> that may be used for receiving feedback for sidelink transmissions. The apparatus <NUM> includes one embodiment of the network unit <NUM>. Furthermore, the network unit <NUM> may include a processor <NUM>, a memory <NUM>, an input device <NUM>, a display <NUM>, a transmitter <NUM>, and a receiver <NUM>. As may be appreciated, the processor <NUM>, the memory <NUM>, the input device <NUM>, the display <NUM>, the transmitter <NUM>, and the receiver <NUM> may be substantially similar to the processor <NUM>, the memory <NUM>, the input device <NUM>, the display <NUM>, the transmitter <NUM>, and the receiver <NUM> of the remote unit <NUM>, respectively.

In some embodiments, the transmitter <NUM> transmits information from the apparatus <NUM> indicating a plurality of resources for sidelink transmission and one or more resources for feedback. In various embodiments, the receiver <NUM> receives feedback at the apparatus using the one or more resources for feedback, wherein receiving the feedback comprises: receiving only a negative acknowledgment on a first at least one resource of the one or more resources for feedback in response to sidelink feedback not being used for the sidelink transmission; receiving only a positive acknowledgment or no acknowledgment on a second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the sidelink transmission; or a combination thereof. Although only one transmitter <NUM> and one receiver <NUM> are illustrated, the network unit <NUM> may have any suitable number of transmitters <NUM> and receivers <NUM>.

In a first embodiment, a TX UE selects a TB and performs sidelink transmissions on allocated resources.

In a first step of the first embodiment, a gNB transmits DCI (e.g., including a sidelink grant) to a TX UE. The DCI allocates one or more resources (e.g., one or more PSSCH resources) for sidelink transmission of a TB from the TX UE, and the DCI allocates one or more resources (e.g., one or more PUCCH resources) for a SL HARQ report to be transmitted to the gNB from the TX UE over a Uu interface. As may be appreciated, the PUCCH resource is for ACK/NACK feedback transmitted from the TX UE to the gNB.

In a second step of the first embodiment, the TX UE selects the TB and performs a sidelink transmission on the allocated one or more resources (e.g., one or more PSSCH resources). The TX UE may select the TB to be transmitted using broadcast, unicast, or groupcast (e.g., multicast). As used herein, broadcast may refer to a transmission from one source to all possible destinations (e.g., one-to-all), unicast may refer to a transmission from one source to one destination (e.g., one-to-one), and groupcast (e.g., or multicast) may refer to a transmission from one source to multiple destinations (e.g., multiple selected or grouped destinations, one-to-many).

If the TB is transmitted using broadcast, then there will be no SL HARQ feedback transmitted from SL devices to the TX UE. However, if the TB is unicast or groupcast, the TX UE may decide if the SL HARQ feedback transmitted from SL devices to the TX UE is enabled or disabled.

If the SL HARQ feedback transmitted from SL devices to the TX UE is disabled by TX UE or the TB is broadcast (e.g., there will be no SL HARQ feedback transmitted from SL devices to the TX UE), then: <NUM>) on all configured PUCCH resources except the last configured PUCCH resource, the TX UE transmits NACK to the gNB to avoid the gNB releasing the allocated one or more resources (e.g., one or more PSSCH resources and/or one or more PUCCH resources); and <NUM>) on the last configured PUCCH resource, the TX UE transmits ACK to the gNB.

In a third step of the first embodiment, the gNB detects the SL HARQ feedback on the allocated one or more resources (e.g., one or more PUCCH resources) transmitted from the TX UE. If ACK is received on a PUCCH resource before the last PUCCH resource, the gNB may reallocate remaining resources (e.g., PSSCH resources, PUCCH resources) for other purposes. If NACK is received on a PUCCH resource before the last PUCCH resource, then no action may be performed by the gNB in relation to the remaining resources. If the gNB doesn't detect ACK or NACK on the first PUCCH resource, the gNB may assume that the TX UE hasn't received the DCI (e.g., including the sidelink grant) and the gNB may reallocate the remaining resources (e.g., PSSCH resources, PUCCH resources) for other purposes. If ACK is received on the last PUCCH resource, the gNB assumes that the SL transmissions are successful. If NACK is received on the last PUCCH resource, the gNB assumes the SL transmissions are unsuccessful. If the gNB doesn't detect ACK or NACK on the last PUCCH resource, the gNB assumes that the TX UE hasn't received the DCI (e.g., including the sidelink grant).

<FIG> illustrate examples of a TX UE's transmissions if the TX UE determines that there is no SL HARQ feedback to be received from SL devices, but DCI allocates PUCCH resources for transmission of SL HARQ feedback from the TX UE to the gNB.

<FIG> is a schematic block diagram illustrating one embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first feedback transmission <NUM> on a first PUCCH resource, a second feedback transmission <NUM> on a second PUCCH resource, a third feedback transmission <NUM> on a third PUCCH resource, and a fourth feedback transmission <NUM> on a fourth PUCCH resource.

As described in the first embodiment, if SL HARQ feedback is not enabled or used (e.g., the TX UE does not receive SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, the TX UE will transmit NACK in the first feedback transmission <NUM>, the second feedback transmission <NUM>, and the third feedback transmission <NUM>. In the fourth feedback transmission <NUM>, the TX UE will transmit ACK.

<FIG> is a schematic block diagram illustrating another embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first feedback transmission <NUM> on a first PUCCH resource.

As described in the first embodiment, if SL HARQ feedback is not enabled or used (e.g., the TX UE does not receive SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, the TX UE will transmit ACK in the first feedback transmission <NUM>.

<FIG> is a schematic block diagram illustrating a further embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first feedback transmission <NUM> on a first PUCCH resource and a second feedback transmission <NUM> on a second PUCCH resource.

As described in the first embodiment, if SL HARQ feedback is not enabled or used (e.g., the TX UE does not receive SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, the TX UE will transmit NACK in the first feedback transmission <NUM>. In the second feedback transmission <NUM>, the TX UE will transmit ACK.

In a second embodiment, a TX UE selects a TB (e.g., with a restriction of PUCCH resources allocated) and performs sidelink transmission on allocated resources. A restriction of PUCCH resources allocated may mean that the gNB may decide whether to allocate PUCCH resources to the TX UE. If the gNB allocates PUCCH resources to the TX UE, the TX UE should select unicast or groupcast transmission and enable HARQ feedback on the SL. If the gNB doesn't allocate PUCCH resources to the TX UE, the TX UE may select broadcast, unicast, or groupcast transmission. Therefore, the presence of whether PUCCH resources are allocated may restrict a type of transmission used by the TX UE.

In a first step of the second embodiment, a gNB transmits DCI (e.g., including a sidelink grant) to a TX UE. The DCI allocates one or more resources (e.g., one or more PSSCH resources) for sidelink transmission of a TB from the TX UE, and the DCI allocates one or more resources (e.g., one or more PUCCH resources) for a SL HARQ report to be transmitted to the gNB from the TX UE over a Uu interface. The first PUCCH resource is for ACK/NACK feedback, and the remaining resources are for only ACK feedback. In certain embodiments, an invalid value in the DCI may be used to indicate that there no PUCCH resource allocation. For example, DCI may indicate that there are no PUCCH resources allocated using an invalid value such as '<NUM>' in a field used to indicate PUCCH resources (e.g., frequency domain, time domain, and/or code domain resources). As another example, DCI may indicate that there are PUCCH resources allocated using a valid value in the field used to indicate PUCCH resources.

In a second step of the second embodiment, the TX UE selects the TB and performs a sidelink transmission on the allocated one or more resources (e.g., one or more PSSCH resources).

If the DCI allocates PUCCH resources for the TX UE to transmit the SL HARQ report to the gNB: <NUM>) the TX UE may only select a TB to be transmitted using unicast or groupcast, and the TX UE should enable SL HARQ feedback to be transmitted from SL devices to the TX UE; and <NUM>) the TX UE transmits SL HARQ feedback to the gNB on the allocated PUCCH resources as follows: a) for the first PUCCH resource: i) if the TX UE detects DCI successfully and the SL transmission on the first allocated resource is successful, the TX UE transmits ACK to the gNB on the first PUCCH resource; ii) if the TX UE detects DCI successfully and the SL transmission on the first allocated resource is unsuccessful, the TX UE transmits NACK to the gNB on the first PUCCH resource; and iii) if the TX UE detects DCI unsuccessfully, nothing will be transmitted on the first PUCCH resource; b) for the other PUCCH resources (e.g., other than the first PUCCH resource): i) if the corresponding SL transmission is successful, the TX UE transmits ACK to the gNB on the corresponding PUCCH resource; and ii) if the corresponding SL transmission is unsuccessful, nothing will be transmitted (e.g., no transmission) on the corresponding PUCCH resource.

If the DCI doesn't allocate PUCCH resources for the TX UE to transmit the SL HARQ report to the gNB: the TX UE may select the TB to be transmitted using broadcast, unicast, or groupcast, and for unicast or groupcast transmissions, the TX UE may decide if the SL HARQ feedback transmitted from SL devices to the TX UE is enabled or disabled.

In a third step of the second embodiment, if DCI allocates PUCCH resources for SL HARQ feedback to be transmitted from the TX UE to the gNB, the gNB detects the SL HARQ feedback on the allocated PUCCH resources. For all the PUCCH resources, if ACK is received by the gNB, the gNB may release the reallocate remaining resources (e.g., PSSCH resources, PUCCH resources) for other purposes. For the first PUCCH resource, if nothing is detected by the gNB, the gNB assumes that the TX UE has missed reception of the DCI and the gNB may re-allocate the remaining resources (e.g., PSSCH resources, PUCCH resources) besides the first ones for other purposes. If NACK is received by the gNB, the gNB may monitor the next PUCCH resource.

<FIG> illustrate examples of a TX UE's transmissions if the TX UE determines that there is SL HARQ feedback to be received from SL devices and DCI allocates PUCCH resources for transmission of SL HARQ feedback from the TX UE to the gNB.

<FIG> is a schematic block diagram illustrating yet another embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first SL feedback transmission <NUM> received on a first PSFCH resource from SL devices, a second SL feedback transmission <NUM> received on a second PSFCH resource from SL devices, a third SL feedback transmission <NUM> received on a third PSFCH resource from SL devices, and a fourth SL feedback transmission <NUM> received on a fourth PSFCH resource from SL devices. The TX UE's transmissions <NUM> further include a first feedback transmission <NUM> on a first PUCCH resource, a second feedback transmission <NUM> on a second PUCCH resource, a third feedback transmission <NUM> on a third PUCCH resource, and a fourth feedback transmission <NUM> on a fourth PUCCH resource.

As described in the second embodiment, if SL HARQ feedback is enabled (e.g., the TX UE receives SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, the TX UE will transmit ACK/NACK in the first feedback transmission <NUM> (e.g., ACK if the corresponding SL transmission was successful, and NACK if the corresponding SL transmission was unsuccessful). In the second feedback transmission <NUM>, the third feedback transmission <NUM>, and the fourth feedback transmission <NUM>, the TX UE will transmit ACK or no transmission (e.g., ACK if the corresponding SL transmission was successful, and no transmission if the corresponding SL transmission was unsuccessful).

<FIG> is a schematic block diagram illustrating an additional embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first SL feedback transmission <NUM> received on a first PSFCH resource from SL devices, a second SL feedback transmission <NUM> received on a second PSFCH resource from SL devices, a third SL feedback transmission <NUM> received on a third PSFCH resource from SL devices, and a fourth SL feedback transmission <NUM> received on a fourth PSFCH resource from SL devices. The TX UE's transmissions <NUM> further include a first feedback transmission <NUM> on a first PUCCH resource.

As described in the second embodiment, if SL HARQ feedback is enabled (e.g., the TX UE receives SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, in the first feedback transmission <NUM>, the TX UE will transmit ACK or no transmission (e.g., ACK if the corresponding SL transmissions were successful, and no transmission if the corresponding SL transmissions were unsuccessful).

<FIG> is a schematic block diagram illustrating yet a further embodiment of a TX UE's transmissions <NUM>. The TX UE's transmissions <NUM> include a first SL transmission <NUM> on a first PSSCH resource, a second SL transmission <NUM> on a second PSSCH resource, a third SL transmission <NUM> on a third PSSCH resource, and a fourth SL transmission <NUM> on a fourth PSSCH resource. All of the illustrated TX UE's transmissions <NUM> occur over a time period <NUM>. The TX UE's transmissions <NUM> also include a first SL feedback transmission <NUM> received on a first PSFCH resource from SL devices, a second SL feedback transmission <NUM> received on a second PSFCH resource from SL devices, a third SL feedback transmission <NUM> received on a third PSFCH resource from SL devices, and a fourth SL feedback transmission <NUM> received on a fourth PSFCH resource from SL devices. The TX UE's transmissions <NUM> further include a first feedback transmission <NUM> on a first PUCCH resource and a second feedback transmission <NUM> on a second PUCCH resource.

As described in the second embodiment, if SL HARQ feedback is enabled (e.g., the TX UE receives SL HARQ feedback from SL devices), in the embodiment illustrated in <FIG>, the TX UE will transmit ACK/NACK in the first feedback transmission <NUM> (e.g., ACK if the corresponding SL transmissions were successful, and NACK if the corresponding SL transmissions were unsuccessful). In the second feedback transmission <NUM> the TX UE will transmit ACK or no transmission (e.g., ACK if the corresponding SL transmissions were successful, and no transmission if the corresponding SL transmissions were unsuccessful). As may be appreciated, the embodiments described herein may reduce overhead of resources by reallocated resources when they are no longer needed.

<FIG> is a schematic flow chart diagram illustrating one embodiment of a method <NUM> for transmitting feedback for sidelink transmissions. In some embodiments, the method <NUM> is performed by an apparatus, such as the remote unit <NUM>. In certain embodiments, the method <NUM> may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

The method <NUM> may include receiving <NUM> information from a network device indicating a plurality of resources for sidelink transmission and one or more resources for feedback. In certain embodiments, the method <NUM> includes transmitting <NUM> sidelink data using the plurality of resources for sidelink transmission. In various embodiments, the method <NUM> includes transmitting <NUM> feedback to the network device using the one or more resources for feedback based on the transmission of the sidelink data, wherein transmitting the feedback comprises: transmitting only a negative acknowledgment on a first at least one resource of the one or more resources for feedback in response to sidelink feedback not being used for the transmission of the sidelink data; transmitting only a positive acknowledgment or no acknowledgment on a second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the transmission of the sidelink data; or a combination thereof.

In certain embodiments, in response to the sidelink feedback being used for the transmission of the sidelink data, transmitting the feedback comprises transmitting any of the positive acknowledgment, the negative acknowledgment, or the no acknowledgment on at most a single resource of the one or more resources for feedback. In some embodiments, the single resource is a first resource in time of the one or more resources for feedback. In various embodiments, the second at least one resource of the one or more resources comprises all resources of the one or more resources except the first resource in time.

In one embodiment, transmitting only the positive acknowledgment or the no acknowledgment on the second at least one resource of the one or more resources for feedback in response to the sidelink feedback being used for the transmission of the sidelink data comprises transmitting the positive acknowledgment in response to a successful transmission of the sidelink data and transmitting the no acknowledgment in response to an unsuccessful transmission of the sidelink data. In certain embodiments, in response to the sidelink feedback not being used for the transmission of the sidelink data, transmitting the feedback comprises transmitting the positive acknowledgment on at most a single resource of the one or more resources for feedback.

In some embodiments, the single resource is a last resource in time of the one or more resources for feedback. In various embodiments, the first at least one resource of the one or more resources comprises all resources of the one or more resources except the last resource in time.

<FIG> is a schematic flow chart diagram illustrating one embodiment of a method <NUM> for receiving feedback for sidelink transmissions. In some embodiments, the method <NUM> is performed by an apparatus, such as the network unit <NUM>. In certain embodiments, the method <NUM> may be performed by a processor executing program code, for example, a microcontroller, a microprocessor, a CPU, a GPU, an auxiliary processing unit, a FPGA, or the like.

Claim 1:
A method (<NUM>) performed by a transmitting user equipment, TX UE, the method (<NUM>) comprising:
receiving (<NUM>) information from a network device indicating a plurality of resources for sidelink transmission and a plurality of resources for feedback;
transmitting (<NUM>) sidelink data using the plurality of resources for sidelink transmission; and
transmitting (<NUM>) feedback to the network device using the plurality of resources for feedback based on the transmission of the sidelink data, wherein transmitting the feedback comprises:
in response to the TX UE determining that sidelink feedback is not being used for the transmission of the sidelink data, transmitting only a negative acknowledgment on a first at least one resource of the plurality of resources for feedback except a last resource in time; and
in response to the TX UE determining that sidelink feedback is being used for the transmission of the sidelink data, transmitting only a positive acknowledgment or no acknowledgment on a second at least one resource of the plurality of resources for feedback except a first resource in time.