Patent Description:
The subject matter disclosed herein relates generally to wireless communications and more particularly relates to data and feedback relaying.

In certain wireless communications networks, relays may be used to transmit and/or receive data transmitted between UEs. Feedback transmissions may be made relating to data transmitted via relays.

<CIT> relates to a method and apparatus for wireless communication of a wireless node in a wireless communication system.

Methods for data and feedback relaying are disclosed. Apparatuses and systems also perform the functions of the methods. One method is as claimed in claim <NUM>.

One apparatus is as claimed in claim <NUM>.

<FIG> depicts an embodiment of a wireless communication system <NUM> for data and feedback relaying. 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), aerial vehicles, drones, or the like. The remote units <NUM> may communicate directly with one or more of the network units <NUM> via UL communication signals. In certain embodiments, 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 and/or may include one or more of an access point, an access terminal, a base, a base station, a location server, a core network ("CN"), a radio network entity, a Node-B, an evolved node-B ("eNB"), a <NUM> node-B ("gNB"), a Home Node-B, a relay node, a device, a core network, an aerial server, a radio access node, an access point ("AP"), new radio ("NR"), a network entity, an access and mobility management function ("AMF"), a unified data management ("UDM"), a unified data repository ("UDR"), a UDM/UDR, a policy control function ("PCF"), a radio access network ("RAN"), a network slice selection function ("NSSF"), an operations, administration, and management ("OAM"), a session management function ("SMF"), a user plane function ("UPF"), an application function, an authentication server function ("AUSF"), security anchor functionality ("SEAF"), trusted non-3GPP gateway function ("TNGF"), or by any other terminology used in the art.

In one implementation, the wireless communication system <NUM> is compliant with NR protocols standardized in third generation partnership project ("3GPP"), wherein the network unit <NUM> transmits using an OFDM modulation scheme on the downlink ("DL") and the remote units <NUM> transmit on the uplink ("UL") using a single-carrier frequency division multiple access ("SC-FDMA") scheme or an orthogonal frequency division multiplexing ("OFDM") scheme. More generally, however, the wireless communication system <NUM> may implement some other open or proprietary communication protocol, for example, WiMAX, institute of electrical and electronics engineers ("IEEE") <NUM> variants, global system for mobile communications ("GSM"), general packet radio service ("GPRS"), universal mobile telecommunications system ("UMTS"), long term evolution ("LTE") variants, code division multiple access <NUM> ("CDMA2000"), Bluetooth®, ZigBee, Sigfoxx, among other protocols.

In various embodiments, a remote unit <NUM> may receive, by a second sidelink user equipment, a first data packet from a first sidelink user equipment. In some embodiments, the remote unit <NUM> may receive a feedback request with the first data packet. In certain embodiments, the remote unit <NUM> may transmit, by the second sidelink user equipment, the first data packet to at least one third sidelink user equipment. In various embodiments, the remote unit <NUM> may receive, at the second sidelink user equipment, feedback about a decoding status of the first data packet from the at least one third sidelink user equipment. In some embodiments, the remote unit <NUM> may determine a result of the feedback request at the second sidelink user equipment based on the feedback. In certain embodiments, the remote unit <NUM> may transmit, from the second sidelink user equipment, the result of the feedback request to the first sidelink user equipment. Accordingly, the remote unit <NUM> may be used for data and feedback relaying.

<FIG> depicts one embodiment of an apparatus <NUM> that may be used for data and feedback relaying. 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>.

For example, the display <NUM> may include, but is not limited to, a liquid crystal display ("LCD"), a light emitting diode ("LED") display, an organic light emitting diode ("OLED") display, a projector, or similar display device capable of outputting images, text, or the like to a user.

In certain embodiments, the receiver <NUM>: receives a first data packet from a first sidelink user equipment; and receives a feedback request with the first data packet. In various embodiments, the transmitter <NUM> transmits, by the second sidelink user equipment, the first data packet to at least one third sidelink user equipment. In some embodiments, the receiver <NUM> receives, at the second sidelink user equipment, feedback about a decoding status of the first data packet from the at least one third sidelink user equipment; the processor <NUM> determines a result of the feedback request at the second sidelink user equipment based on the feedback; and the transmitter <NUM> transmits, from the second sidelink user equipment, the result of the feedback request to the first sidelink user equipment.

<FIG> depicts one embodiment of an apparatus <NUM> that may be used for data and feedback relaying. 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 certain embodiments, such as in new radio ("NR") vehicle to everything ("V2X") communication, hybrid automatic repeat request ("HARQ") feedback may be used for groupcast and unicast communication to improve spectral efficiency. For communicating feedback made by receiver user equipments ("UEs") to a transmitter UE for a transmission made by the transmitter, the following options are available: <NUM>) in a first option, a negative acknowledgment ("NACK") only common feedback resource may be used - in this option all receivers that have failed to successfully decode a received physical sidelink shared channel ("PSSCH") data packet will send a HARQ NACK on a resource common to all the receivers - the HARQ NACK feedback may be subframe number ("SFN") combined over the air; and <NUM>) in a second option, receiver UE specific acknowledgement ("ACK") and/or NACK feedback resources - in this option every receiver that received a physical sidelink control channel ("PSCCH") transmission (e.g., sidelink control information ("SCI")) and attempted to decode a corresponding PSSCH transmission (e.g., data packet) may feedback HARQ ACK and/or NACK in resources depending on whether they were successful in decoding the data packet.

In some embodiments, there may be two types of relays: <NUM>) UE-to-network coverage extension: UE to network ("Uu") interface coverage reachability may be necessary for UEs to reach a server in a packet data network ("PDN") or counterpart UE out of a proximity area - various embodiments for UE-to-network relays may be limited to evolved universal terrestrial access ("EUTRA") based technologies, and may not be applied to an NR-based system (e.g., for both next generation ("NG") radio access network ("RAN") ("NG-RAN") and NR-based sidelink communications); and <NUM>) UE-to-UE coverage extension: current proximity reachability may be limited to a single-hop sidelink link either via EUTRA-based or NR-based sidelink technology - this may not be sufficient if there is no Uu coverage, considering a limited single-hop sidelink coverage.

In various embodiments, for both sidelink ("SL") relay types, a SL remote UE may discover and select a relay for transmissions to another SL remote UE. In certain embodiments, a reliability requirement for V2X communication may be up to <NUM>^-<NUM> (e.g., performance quality index ("PQI") <NUM>) and this may increase with for public safety and other applications. In some embodiments, HARQ feedback based transmission and/or retransmission may be used for communication using a sidelink relay.

It should be noted that the following terminology is used in this document: <NUM>) UE-to-network relay: N-relay; <NUM>) UE-to-UE relay: UE-relay; and <NUM>) Relay = either a UE-to-network relay or a UE-to-UE relay.

<FIG> is a schematic block diagram illustrating one embodiment of a system <NUM> for relay communications. The system <NUM> includes a UE1 <NUM> (e.g., TX-Remote-UE, first UE, one or more transmit ("TX") UEs), a UE2 <NUM> (e.g., relay UE, second UE), and a UE3 <NUM> (e.g., RX-Remote-UE, third UE, one or more RX UEs). The UE1 <NUM> communicates with the UE2 <NUM> over a first interface <NUM>, while the UE2 <NUM> communicates with the UE3 <NUM> over a second interface <NUM>.

The UE1 <NUM> is a UE that has some application data to be sent to another remote UE (UE3 <NUM>) via a relay (UE2 <NUM>). It should be noted that, the UE3 <NUM> may have data to send to the UE1 <NUM> via the UE2 <NUM> (in this context UE3 <NUM> would take the role of a transmitter UE). Accordingly, the terms and roles shown in <FIG> may be with respect to a particular data packet. In some embodiments, more than one relay is used (e.g., UE2a and UE2b), thus the UE2 <NUM> may be a generalized representation of one or more relay UEs. In various embodiments, UE3 <NUM> may act as a relay UE to another UE (e.g., UE4).

In a first embodiment, several different implementations may be encompassed for how to determine if a HARQ feedback is to be used on the two interfaces in <FIG>.

In a first implementation of the first embodiment, a relay UE decides a transmission scheme (e.g., HARQ feedback ("HF") or blind) to use on the second interface <NUM>. For this purpose, the UE1 <NUM> sends at least PQI of a concerned bearer that the UE2 <NUM> has agreed to relay to UE3 <NUM>. If UE3 <NUM> is a part of a group and groupcast transmission needs to be made on the second interface <NUM>, the UE1 <NUM> sends a minimum communication range ("MCR") and group size information to the UE2 <NUM> if it has been received by the UE1 <NUM> from its upper layer. The relay (e.g., UE2 <NUM>) takes into account a packet delay budget ("PDB") corresponding to the PQI and calculates a remaining PDB. The remaining PDB is PDB minus an average link delay on the first interface <NUM>. The average link delay on the first interface <NUM> may be determined as an average delay over a period if the UE1 <NUM> was using a timestamp to mark the arrival of data in its layer <NUM> ("L2") buffers and sends this timestamp to the UE2 <NUM>. In the absence of this timestamp-based determination, a relay UE (e.g., UE2 <NUM>) may deduct a fixed time from the PDB. For example, the fixed time may be between <NUM> and <NUM>.

In another implementation of the first embodiment, a deduction from a PDB may be dependent on a timer 'T1' and atimer 'T2' used by UE1 <NUM> (e.g., UE1 <NUM> may signal used values to UE2 <NUM> when handshaking to add the bearer to the relay). Timers 'T1' and 'T2' may be predetermined and/or defined. The UE1 <NUM> can't use the entire PDB as 'T2' since the UE2 <NUM> may need finite time in attempting to transmit a transport block TB (e.g., received from UE1 <NUM>) to the UE3 <NUM>. Timer 'T2' may be apportioned beforehand (e.g., during handshake). A ratio may also be used. If the ratio is <NUM>%, then both the UE1 <NUM> and the UE2 <NUM> have half of the PDB to transmit the TB to their respective destination. In certain embodiments, the UE1 <NUM> may indicate a time value (e.g., 'x' ms) to UE2 <NUM> for the first interface <NUM>. The UE2 <NUM> may then deduct 'x' ms from the PDB to derive its remaining PDB (e.g., 'T2').

In one implementation of the first embodiment, if the UE1 <NUM> is unable to transmit a TB to the UE2 <NUM> in its part of a PDB, the TB is not transmitted and both the UE1 <NUM> and the UE2 <NUM> will give up on transmission of the TB, and clear their HARQ and/or soft buffers. In various embodiments, if there is another path (e.g., another relay), the UE1 <NUM> may try to transmit the TB using that path if the overall PDB may be met.

In another implementation of the first embodiment, a PDB is not a hard deadline and a TB may still be delivered beyond the PDB. This ability may be indicated by higher layer signaling to the UE1 <NUM>. In this implementation, even if the UE1 <NUM> is unable to transmit the TB to the UE2 <NUM> in UE1's <NUM> part of the PDB, the TB is still attempted to be transmitted until a maximum number of allowed retransmissions on the first interface <NUM>.

In certain embodiments, the UE1 <NUM> sends sl-HARQ-FeedbackEnabled as determined for an entire TB (e.g., enabled or disabled) along with the TB that is being transmitted to the UE2 <NUM>. The feedback enabled and/or disabled indication may be signaled in corresponding SCI (e.g., PSCCH). The relay may not pack data coming from different Tx-Remote-UEs for the same Rx-Remote-UE with different feedback configurations (e.g., a TB towards a particular Rx-Remote-UE may only contain data with either feedback enabled or feedback disabled, but not both).

In some embodiments, a relay UE may decide if it should transmit HARQ feedback or make blind retransmissions. Therefore, the relay UE may consider if PSFCH resources are available for at least one resource pool for mode <NUM> communication, or if a mode <NUM> grant has corresponding PSFCH resources (e.g., availability of physical uplink control channel ("PUCCH") resources may be taken as a proxy). As an example, the UE2 <NUM> may decide (e.g., for making blind retransmissions) if at least one of the following is true: <NUM>) required reliability is equal to higher than <NUM>^-<NUM>; <NUM>) remaining PDB is insufficient for HARQ based retransmission; <NUM>) physical sidelink feedback channel ("PSFCH") resource is not available; <NUM>) channel busy ratio ("CBR") (e.g., channel congestion) is higher than a threshold; and/or <NUM>) logical channel configuration (e.g., sl-HARQ-FeedbackEnabled set disabled): the logical channel configuration may be signaled to an N-relay UE from its serving gNB and a UE-relay may use the pre-configuration. The logical channel configuration may configure each logical channel towards the second interface <NUM> such that data from one or more remote UE1s <NUM> with a specific PQI (or a PQI range) may only be mapped to the logical channel. The configuration may set the sl-HARQ-FeedbackEnabled to "enabled" or "disabled". Otherwise, a HARQ feedback-based retransmission may be made.

In one embodiment of the first implementation of the first embodiment, a transmission scheme on the second interface <NUM> may be mixed (e.g., a fixed number of blind retransmissions followed by one or more feedback-based re-transmissions).

In a second implementation of the first embodiment, the UE1 <NUM> decides a transmission scheme (e.g., HF or blind) on the second interface <NUM> based on various principles including logical channel configuration (e.g., sl-HARQ-FeedbackEnabled), and signals the determined behavior to the UE2 <NUM> using SCI (e.g., PSCCH) on the first interface <NUM> or using UE to UE ("PC5") radio resource control ("RRC") signaling. In doing this, the remaining PDBs (e.g., UE <NUM> and UE2 <NUM>) may be calculated as described in other embodiments. The UE2 <NUM> will follow the decision signaled by the UE1 <NUM> and perform HARQ feedback-based retransmissions or blind retransmissions ("BRs") on the second interface <NUM> towards the UE3 <NUM>.

In a third implementation of the first embodiment, the UE1 <NUM> decides a transmission scheme (e.g., HARQ feedback-based retransmissions or BRs) on the first interface <NUM> like in other configurations except that a remaining PDB at the UE1 <NUM> may be calculated as described in other embodiments.

In a fourth implementation of the first embodiment, a transmission scheme on the first interface <NUM> is always fixed (e.g., fixed number of blind retransmissions). If the UE2 <NUM> receives a TB successfully, it may start the transmission of this TB towards the UE3 <NUM>.

In a fifth implementation of the first embodiment, a transmission scheme on the first interface <NUM> is mixed (e.g., fixed number of blind retransmissions followed by one or more feedback-based re-transmissions).

It should be noted that, in any implementation, if the UE1 <NUM> is unable to transmit a TB to the UE2 <NUM> in its part of the PDB, the TB is no longer retransmitted and both the UE1 <NUM> and the UE2 <NUM> will give up transmission of the TB and clear their HARQ and/or soft buffers. However, if there is another path (e.g., another relay), the UE1 <NUM> may still try to transmit the TB using that path if the overall PDB may still be met. In certain implementations of the first embodiment, a PDB is not a hard deadline and a TB may still be delivered beyond the PDB. This possibility may be indicated by a higher layer to the UE1 <NUM>. In such implementations, even if the UE1 <NUM> is unable to transmit the TB to the UE2 <NUM> in its part of the PDB, the TB is still attempted to be transmitted until a maximum number of allowed retransmissions on the first interface <NUM>.

In any implementation, the UE1 <NUM> may send sl-HARQ-FeedbackEnabled as determined for an entire TB (e.g., enabled or disabled) along with the TB that is being transmitted to the UE2 <NUM>. The feedback enabled and/or disabled indication may be signaled in a corresponding SCI (e.g., PSCCH). The relay may not pack data coming from different Tx-Remote-UEs towards the same Rx-Remote-UE with different feedback configuration (e.g., a TB towards a particular Rx-Remote-UE may only contain data with either feedback enabled or feedback disabled, but not both).

In a second embodiment, if using one or more relays, a relay behavior is described in relation to when and how it sends HARQ feedback to the UE1 <NUM> (e.g., on the first interface <NUM>). In the second embodiment, the UE2 <NUM> may send HARQ feedback on a PSFCH channel.

In one implementation of the second embodiment, the UE2 <NUM> sends HARQ feedback on a PSFCH channel. A HARQ ACK is transmitted if the relay UE can decode data (e.g., TB transmitted by the UE1 <NUM>) correctly, otherwise a NACK is sent. One of an ACK or NACK transmission may be discontinuous transmission ("DTX"). A HARQ buffer at the UE1 <NUM> and a soft buffer at the UE2 <NUM> may be flushed if a PDB (e.g., remaining PDB) is exceeded, a maximum number of HARQ retransmissions has been reached, or a packet (e.g., TB) was correctly decoded at the UE2 <NUM> (e.g., ACK received by the UE1 <NUM>).

In another implementation of the second embodiment, after having received a TB successfully (and sending a HARQ ACK to the UE1 <NUM> if HARQ feedback based transmission is on the first interface <NUM>), a feedback is transmitted only if data (e.g., from the TB received on the first interface <NUM>) to each Rx-remote-UEs is transmitted successfully. This can be done using a packet data convergence protocol ("PDCP") status reporting for layer <NUM> ("L3") based relaying or using radio link control ("RLC") status reporting on the first interface <NUM> if an RLC ACK is transmitted if a corresponding TB on the second interface <NUM> was successfully transmitted.

In another variation of the second embodiment, instead of transmitting the PDCP and/or RLC status reporting for each TB received at the UE2 <NUM> from the UE1 <NUM>, the UE2 <NUM> may accumulate reports for multiple TBs and send together, either periodically or for a certain number of TBs. In some embodiments, the UE1 <NUM> may be able to poll the UE2 <NUM> to seek a status report.

In another implementation of the second embodiment, after having received a TB successfully (and sending HARQ ACK to the UE1 <NUM> for HARQ feedback based transmission on the first interface <NUM>), both HARQ ACK and NACK feedback received from the UE3 <NUM> at the UE2 <NUM> may be forwarded by the UE2 <NUM> back to the UE1 <NUM> if the TX remote UE <NUM><NUM> multiplexes sidelink data towards more than one receive ("RX") remote UE (e.g., multiple UE3 <NUM>) served by the same relay UE2 <NUM> into a TB and if transmission on the second interface <NUM> is successful for some receiver remote UEs but not for others. This may be done using a PSFCH resource except that a member ID of the UE3 <NUM> may be based on an appearance of a sidelink ("SL") shared channel ("SCH") ("SL-SCH") subheader. A first SL-SCH subheader may appear at a leftmost side of a received medium access control ("MAC") protocol data unit ("PDU") on the first interface <NUM> and may be allocated a member ID of <NUM>, a next SL-SCH subheader amy be allocated a member ID of <NUM>, and so forth. If a configuration goes beyond the UE2's <NUM> capability to transmit individual PSFCHs simultaneously, feedback (e.g., ACK and/or NACK) multiplexing may be used (e.g., by using various techniques). In one example, <NUM> different reference signals may be used if <NUM> different UE3's <NUM> data was multiplexed in a TB transmitted on the first interface <NUM>.

In certain embodiments, a new MAC control element ("CE") (e.g., with a reserved logical channel identifier ("LCID") value) may be used by the UE1 <NUM> to request the UE2 <NUM> to send specific feedback for transmission on the second interface <NUM> to UE3s <NUM>. The specific feedback implies that the UE1 <NUM> seeks feedback only about particular Rx-remote-UEs (and not other Rx-remote-UEs) or even about a particular logical channel of a particular UE3 <NUM>. One way to implement this may be by including two bitmaps of a fixed length (e.g., <NUM> bits each), the first bitmap indicating the Rx-remote-UEs - the first bit = first Rx-remote-UE appearing in the TB from left; next bit = next Rx-remote-UE appearing in the TB from left, and so forth. The second bitmap contains a request for each logical channel ("LCH") of the Rx-remote-UEs indicated using the first bitmap. If there is more than one bit set (e.g., to TRUE) in the first bitmap, there may be as many second bitmaps required. There may be another signaling structure possible to achieve the same. The MAC CE may contain an integer Request_identifier field. The UE2 <NUM> may use the Request_identifier field for a response containing feedback of a requested transmission.

In some embodiments, a HARQ TX buffer at the UE1 <NUM> may be flushed if: <NUM>) all ACKs are received on the first interface <NUM>; and <NUM>) a highest PDB among all of the receiver remote UEs is exceeded or a maximum number of HARQ retransmissions has been reached.

In various embodiments, HARQ TX buffers at the UE2 <NUM> may be flushed if: <NUM>) a corresponding ACK for a particular UE3 <NUM> is received on the second interface <NUM>; and <NUM>) a corresponding PDB or a maximum number of HARQ retransmissions has been reached for a corresponding UE3 <NUM>.

In certain embodiments, only an ACK is indicated by the UE2 <NUM> if the relay would like the Tx-remote-UE to stop retransmitting on the first interface <NUM>, irrespective of an actual status of transmission on the second interface <NUM>. This may be done in configurations in which a HARQ buffer is emptied in the UE2 <NUM> due to no HARQ process identifier ("HPID") being available for a higher priority data, one or more data not transmitted on a second interface <NUM> due to pre-emption, and so forth. All HARQ related buffers may be flushed at this point.

In a third embodiment), if L3 relaying is used and a PDCP entity is present in a relay protocol stack, the UE1 <NUM> sends a PDCP discard to the UE2 <NUM> if a discard timer in the UE1 <NUM> expires. If the UE2 <NUM> did not start transmission of a corresponding PDCP PDU at the UE2 <NUM> (e.g., RLC sequence number ("SN") not assigned), the PDCP PDU may not be transmitted anymore by the UE2 <NUM>.

In a fourth embodiment, if L3 relaying is used, PDCP discard timers may be partitioned and signaled between the UE1 <NUM> and the UE2 <NUM> in a manner like other embodiments for partitioning 'T2'.

In a fifth embodiment, sidelink radio bearers ("SLRB") may be configured using RRC signaling from a serving gNB. The SLRB configurations may be independently sent to each remote and relay UE. A relay UE may receive a configuration restricting it to multiplex data from only certain logical channels of one or more Tx-remote-UEs from the first interface <NUM> in the same TB towards a Rx-remote-UE. The restriction may configure that on a particular logical channel on the second interface <NUM>, only LCHs from the first interface <NUM> with a given sl-Priority (e.g., '<NUM>') or with a given range of sl-Priority (e.g., `<NUM> to <NUM>') may be multiplexed. In the absence of RRC signaling from a serving gNB, a sidelink UE may use an SLRB configuration based on a pre-configuration. The logical channel restrictions and/or SLRB restrictions may be used at a particular sidelink UE only and not percolated from a remote UE to relay UE or vice-versa.

<FIG> is a communication diagram illustrating one embodiment of a system <NUM> for communications including data and feedback relaying. The system <NUM> includes a TX UE <NUM> (e.g., one or more TX UEs), a relay UE <NUM> (e.g., one or more relay UEs), and an RX UE <NUM> (e.g., one or more RX UEs). Each of the communications shown may include one or more messages.

In a first communication <NUM> transmitted from the TX UE <NUM> to the relay UE <NUM>, the TX UE <NUM> transmits a data packet to the relay UE <NUM>. The TX UE <NUM> may also transmit a feedback request with the data packet to the relay UE <NUM>. In a second communication <NUM> transmitted from the relay UE <NUM> to the RX UE <NUM>, the relay UE <NUM> transmits the data packet to the RX UE <NUM>. In a third communication <NUM> transmitted from the RX UE <NUM> to the relay UE <NUM>, the RX UE <NUM> may transmit feedback corresponding to the data packet to the relay UE <NUM>. In a fourth communication <NUM> transmitted from the relay UE <NUM> to the TX UE <NUM>, the relay UE <NUM> may transmit the feedback corresponding to the data packet to the TX UE <NUM>.

<FIG> is a flow chart diagram illustrating one embodiment of a method <NUM> for data and feedback relaying. 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.

In various embodiments, the method <NUM> includes receiving <NUM>, by a second sidelink user equipment, a first data packet from a first sidelink user equipment. In some embodiments, the method <NUM> includes receiving <NUM> a feedback request with the first data packet. In certain embodiments, the method <NUM> includes transmitting <NUM>, by the second sidelink user equipment, the first data packet to at least one third sidelink user equipment. In various embodiments, the method <NUM> includes receiving <NUM>, at the second sidelink user equipment, feedback about a decoding status of the first data packet from the at least one third sidelink user equipment. In some embodiments, the method <NUM> includes determining <NUM> a result of the feedback request at the second sidelink user equipment based on the feedback. In certain embodiments, the method <NUM> includes transmitting <NUM>, from the second sidelink user equipment, the result of the feedback request to the first sidelink user equipment.

The method <NUM> further comprises receiving a quality of service indicator corresponding to an interface used for transmitting the first data packet to the at least one third sidelink user equipment. The method <NUM> further comprises calculating a remaining packet delay budget based on a packet delay budget corresponding to the quality of service indicator. In various embodiments, the remaining packet delay budget comprises a packet delay budget minus an average link delay.

In one embodiment, the average link delay is determined based on a delay between the first sidelink user equipment transmitting a plurality of data packets and the second sidelink user equipment receiving the plurality of data packet. In certain embodiments, the remaining packet delay budget comprises a packet delay budget minus a fixed time. In some embodiments, the remaining packet delay budget comprises a packet delay budget minus a variable time determined based on at least one timer.

In various embodiments, the at least one timer comprises a first timer T1 and a second timer T2. In one embodiment, the method <NUM> further comprises receiving a minimum communication range and group size information in response to the at least one third sidelink user equipment being part of a group. In certain embodiments, the method <NUM> further comprises receiving a second data packet from a fourth sidelink user equipment.

In some embodiments, the method <NUM> further comprises transmitting the second data packet with the first data packet to the at least one third sidelink user equipment in response to the fourth sidelink user equipment having a feedback configuration that matches a feedback configuration for the first sidelink user equipment. In various embodiments, the result of the feedback request comprises a sidelink shared channel subheader corresponding to each third sidelink user equipment of the at least one third sidelink user equipment. In one embodiment, each sidelink shared channel subheader comprises a member identifier corresponding to a third sidelink user equipment of the at least one third sidelink user equipment.

In certain embodiments, the method <NUM> further comprises flushing a feedback buffer in response to receiving an acknowledgment for a corresponding third sidelink user equipment of the at least one third sidelink user equipment. In some embodiments, the method <NUM> further comprises flushing a feedback buffer in response to a corresponding packet delay budget being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment. In various embodiments, the method <NUM> further comprises flushing a feedback buffer in response to a maximum number of hybrid automatic repeat request retransmissions being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In one embodiment, the method <NUM> further comprises receiving a packet data convergence protocol discard message in response to a corresponding discard timer expiring at the first sidelink user equipment. In certain embodiments, the method <NUM> further comprises, in response to transmission of a packet data convergence protocol protocol data unit not having started at a time at which the packet data convergence protocol discard message is received, not transmitting the packet data convergence protocol protocol data unit. In some embodiments, the method <NUM> further comprises not transmitting a packet data convergence protocol protocol data unit based on at least one timer.

In one embodiment, a method comprises: receiving, by a second sidelink user equipment, a first data packet from a first sidelink user equipment; receiving a feedback request with the first data packet; transmitting, by the second sidelink user equipment, the first data packet to at least one third sidelink user equipment; receiving, at the second sidelink user equipment, feedback about a decoding status of the first data packet from the at least one third sidelink user equipment; determining a result of the feedback request at the second sidelink user equipment based on the feedback; and transmitting, from the second sidelink user equipment, the result of the feedback request to the first sidelink user equipment.

In certain embodiments, the method further comprises receiving a quality of service indicator corresponding to an interface used for transmitting the first data packet to the at least one third sidelink user equipment.

In some embodiments, the method further comprises calculating a remaining packet delay budget based on a packet delay budget corresponding to the quality of service indicator.

In various embodiments, the remaining packet delay budget comprises a packet delay budget minus an average link delay.

In one embodiment, the average link delay is determined based on a delay between the first sidelink user equipment transmitting a plurality of data packets and the second sidelink user equipment receiving the plurality of data packet.

In certain embodiments, the remaining packet delay budget comprises a packet delay budget minus a fixed time.

In some embodiments, the remaining packet delay budget comprises a packet delay budget minus a variable time determined based on at least one timer.

In various embodiments, the at least one timer comprises a first timer T1 and a second timer T2.

In one embodiment, the method further comprises receiving a minimum communication range and group size information in response to the at least one third sidelink user equipment being part of a group.

In certain embodiments, the method further comprises receiving a second data packet from a fourth sidelink user equipment.

In some embodiments, the method further comprises transmitting the second data packet with the first data packet to the at least one third sidelink user equipment in response to the fourth sidelink user equipment having a feedback configuration that matches a feedback configuration for the first sidelink user equipment.

In various embodiments, the result of the feedback request comprises a sidelink shared channel subheader corresponding to each third sidelink user equipment of the at least one third sidelink user equipment.

In one embodiment, each sidelink shared channel subheader comprises a member identifier corresponding to a third sidelink user equipment of the at least one third sidelink user equipment.

In certain embodiments, the method further comprises flushing a feedback buffer in response to receiving an acknowledgment for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In some embodiments, the method further comprises flushing a feedback buffer in response to a corresponding packet delay budget being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In various embodiments, the method further comprises flushing a feedback buffer in response to a maximum number of hybrid automatic repeat request retransmissions being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In one embodiment, the method further comprises receiving a packet data convergence protocol discard message in response to a corresponding discard timer expiring at the first sidelink user equipment.

In certain embodiments, the method further comprises, in response to transmission of a packet data convergence protocol protocol data unit not having started at a time at which the packet data convergence protocol discard message is received, not transmitting the packet data convergence protocol protocol data unit.

In some embodiments, the method further comprises not transmitting a packet data convergence protocol protocol data unit based on at least one timer.

In one embodiment, an apparatus comprises a second sidelink user equipment. The apparatus further comprises: a receiver that: receives a first data packet from a first sidelink user equipment; and receives a feedback request with the first data packet; a transmitter that transmits, by the second sidelink user equipment, the first data packet to at least one third sidelink user equipment; and a processor, wherein: the receiver receives, at the second sidelink user equipment, feedback about a decoding status of the first data packet from the at least one third sidelink user equipment; the processor determines a result of the feedback request at the second sidelink user equipment based on the feedback; and the transmitter transmits, from the second sidelink user equipment, the result of the feedback request to the first sidelink user equipment.

In certain embodiments, the receiver receives a quality of service indicator corresponding to an interface used for transmitting the first data packet to the at least one third sidelink user equipment.

In some embodiments, the processor calculates a remaining packet delay budget based on a packet delay budget corresponding to the quality of service indicator.

In one embodiment, the receiver receives a minimum communication range and group size information in response to the at least one third sidelink user equipment being part of a group.

In certain embodiments, the receiver receives a second data packet from a fourth sidelink user equipment.

In some embodiments, the transmitter transmits the second data packet with the first data packet to the at least one third sidelink user equipment in response to the fourth sidelink user equipment having a feedback configuration that matches a feedback configuration for the first sidelink user equipment.

In certain embodiments, the processor flushes a feedback buffer in response to receiving an acknowledgment for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In some embodiments, the processor flushes a feedback buffer in response to a corresponding packet delay budget being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In various embodiments, the processor flushes a feedback buffer in response to a maximum number of hybrid automatic repeat request retransmissions being reached for a corresponding third sidelink user equipment of the at least one third sidelink user equipment.

In one embodiment, the receiver receives a packet data convergence protocol discard message in response to a corresponding discard timer expiring at the first sidelink user equipment.

In certain embodiments, the processor, in response to transmission of a packet data convergence protocol protocol data unit not having started at a time at which the packet data convergence protocol discard message is received, does not transmit the packet data convergence protocol protocol data unit.

In some embodiments, the processor does not transmit a packet data convergence protocol protocol data unit based on at least one timer.

Claim 1:
An apparatus (<NUM>) comprising a second sidelink user equipment (<NUM>), the apparatus (<NUM>) further comprising:
a receiver (<NUM>) that is configured to:
receive (<NUM>) a first data packet from a first sidelink user equipment (<NUM>); and
receive (<NUM>) a feedback request with the first data packet;
a transmitter (<NUM>) that is configured to transmit (<NUM>), by the second sidelink user
equipment (<NUM>), the first data packet to at least one third sidelink user equipment; (<NUM>) and
a processor (<NUM>), wherein:
the receiver (<NUM>) is configured to receive (<NUM>), at the second sidelink user equipment (<NUM>), feedback about a decoding status of the first data packet from the at least one third sidelink user equipment (<NUM>);
the processor (<NUM>) is configured to determine (<NUM>) a result of the feedback request at the second sidelink user equipment (<NUM>) based on the feedback; and
the transmitter (<NUM>) is configured to transmit (<NUM>), from the second sidelink user equipment (<NUM>), the result of the feedback request to the first sidelink user equipment (<NUM>),
wherein the receiver (<NUM>) is configured to receive a quality of service indicator corresponding to an interface used for transmitting the first data packet to the at least one third sidelink user equipment (<NUM>), and
characterized in that
the processor (<NUM>) is configured to calculate a remaining packet delay budget based on a packet delay budget corresponding to the quality of service indicator.