Method and apparatus for performing sidelink communication in communication system

Abstract

The invention relates to a method and apparatus for performing sidelink communication in a communication system. In accordance with some embodiments of the present disclosure, a method of a first communication device includes receiving a first connection request from a second communication device, where the first connection request may include a first indication indicating that a first logical channel between the first communication device and the second communication device is associated with a third communication device.

Description

Method and apparatus for performing sidelink communication in a communication system

[0001] Information related to divisional application

[0002] This application is a divisional application of the invention patent application filed on August 5, 2019, with application number 201980098924.0 and entitled "Method and apparatus for performing sidelink communication in a communication system". Technical Field

[0003] This disclosure generally relates to wireless communication technologies, and more specifically to sidelink communication in wireless communication systems. Background Technology

[0004] 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 an operator's network (e.g., a cellular or Wi-Fi network infrastructure). The data path supported by the operator's network may include a base station (BS) and multiple gateways.

[0005] In sidelink communication, communication devices that are relatively close to each other can communicate directly via a sidelink (SL) instead of through a base station (BS) link. The term "SL" can refer to establishing a direct radio link for communication between devices (e.g., UEs), as opposed to communication via cellular infrastructure (uplink and downlink) as discussed above. "SL" can also be referred to as a sidelink communication link. Sidelink communication links can be used in any suitable telecommunications network according to various standards.

[0006] Sidelink communication offers various advantages, such as relatively high transmission rates and relatively low latency. Furthermore, during sidelink communication, services concentrated at the base station can be distributed. Additionally, UEs supporting sidelink communication can be used as relay nodes to extend the base station's coverage.

[0007] Sidelink communication needs to be executed effectively in the communication system. Summary of the Invention

[0008] Embodiments of this disclosure provide a method for a first communication device. The method may include receiving a first connection request from a second communication device, wherein the first connection request may include a first indication that a first logical channel between the first and second communication devices is associated with a third communication device.

[0009] In embodiments of this application, the method may include sending a second connection request to the third communication device, wherein the second connection request may include a second indication that a second logical channel between the first communication device and the third communication device is associated with the second communication device.

[0010] In embodiments of this application, the method may include: receiving first data corresponding to the first logical channel from the second communication device; and determining, based on the first indication, that the destination communication device of the first data is the third communication device. The first data may include first sidelink control information. The first sidelink control information may include a destination field indicating the identity of a relay communication device. The method may include: determining, based on the destination field of the first sidelink control information, whether to discard or relay the first data; and relaying the first data when the destination field of the first sidelink control information indicates the identity of the first communication device. The method may also include decoding the first data into a Media Access Control (MAC) Protocol Data Unit (PDU) when the destination field of the first sidelink control information indicates the identity of the first communication device, wherein the header of the MAC PDU may include a destination field indicating the identity of the relay communication device.

[0011] In embodiments of this application, the step of determining whether to discard or relay the first data may include determining whether to discard or relay the first data based on the destination field of the header of the MAC PDU. The step of relaying the first data may include relaying the first data to the destination communication device when the destination field of the header of the MAC PDU indicates the identity of the first communication device.

[0012] In embodiments of this application, the destination field of the first side link control information may contain a portion of the identity of the relay communication device, and the destination field of the header of the MAC PDU may contain the remaining portion of the identity of the relay communication device.

[0013] In an embodiment of this application, the method may include transmitting second data associated with the first data to the destination communication device when the destination communication device is not the first communication device.

[0014] In an embodiment of this application, the step of transmitting the second data may include multiplexing the first data and the third data into the second data, wherein the first data and the third data are received from different logical channels, and the destination communication device of the third data is the same as the destination communication device of the first data.

[0015] In another embodiment of this application, the step of transmitting the second data may include: encoding the first data into a MAC PDU, wherein the header of the MAC PDU may include a source field indicating the identity of the first communication device; and encoding the MAC PDU into the second data. The second data may include second sidelink control information. The second sidelink control information may include a source field indicating the identity of the first communication device. The source field of the second sidelink control information may include a portion of the identity of the first communication device. The source field of the header of the MAC PDU may include the remaining portion of the identity of the first communication device.

[0016] Another embodiment of this disclosure provides a method for a first communication device. The method may include receiving a first connection request from a second communication device, wherein the first connection request may include an indication of at least one destination communication device. The method may include: receiving first data from the second communication device; and decoding the first data into a first MAC PDU, wherein the header of the first MAC PDU may include a destination field indicating the identity of the destination communication device. The method may include transmitting second data associated with the first data to the destination communication device when the destination communication device is one of the at least one destination communication device.

[0017] In an embodiment of this application, transmitting the second data to the destination communication device may include: encoding the first data into a second MAC PDU, wherein the header of the second MAC PDU may include a source field indicating the identity of the second communication device; and encoding the second MAC PDU into the second data.

[0018] In embodiments of this application, the second data may include sidelink control information. The sidelink control information may include a source field indicating the identity of the first communication device. The source field of the sidelink control information may contain at least a portion of the identity of the first communication device.

[0019] Another embodiment of this disclosure provides a method for a first communication device. The method may include receiving first data from a second communication device, wherein the first data may include first sidelink control information, and the first sidelink control information may include a destination field indicating the identity of the first communication device.

[0020] In embodiments of this application, the method may include decoding the first data into a first MAC PDU, wherein the first MAC PDU may include at least one MAC sub-header and at least one MAC Service Data Unit (SDU), each MAC sub-header corresponding to a corresponding one of the at least one MAC SDU, and each MAC sub-header may include a source field and a destination field; wherein the source field indicates the identity of the source communication device corresponding to the MAC SDU, and the destination field indicates the identity of the destination communication device corresponding to the MAC SDU. In embodiments of this application, the source field may include at least a portion of the identity of the source communication device. The destination field may include at least a portion of the identity of the destination communication device. In another embodiment of this application, the first MAC PDU may include a first MAC SDU and a second MAC SDU. The destination communication device of the first MAC SDU is different from the destination communication device of the second MAC SDU. In yet another embodiment of this application, the first MAC PDU may include a first MAC SDU. The method may further include transmitting second data associated with the first data to the destination communication device of the first MAC SDU when the destination communication device of the first MAC SDU is not the first communication device.

[0021] In embodiments of this application, the step of transmitting the second data may include multiplexing the first data and the third data into the second data, wherein the first data and the third data are received from different logical channels, and the destination communication device of the third data is the same as the destination communication device of the first MAC SDU. The step of multiplexing the first data and the third data may include: encoding the first data into a second MAC SDU of a second MAC PDU, wherein the second MAC sub-header corresponding to the second MAC SDU may include a source field indicating the identity of the source communication device of the first data and a destination field indicating the identity of the destination communication device of the first data; and encoding the third data into a third MAC SDU of the second MAC PDU, wherein the third MAC sub-header corresponding to the second MAC SDU may include a source field indicating the identity of the source communication device of the third data and a destination field indicating the identity of the destination communication device of the first data. The source communication device of the first data is different from the source communication device of the third data.

[0022] In another embodiment of this application, the second data may include second sidelink control information, and the second sidelink control information may include a source field indicating the identity of the first communication device.

[0023] In another embodiment of this application, the method may include decoding the first data into a first MAC PDU, wherein the first MAC PDU may include a first MAC header containing a destination field indicating the identity of the first communication device.

[0024] In embodiments of this application, the destination field of the first side link control information may contain a portion of the identity of the first communication device, and the destination field of the first MAC header may contain the remaining portion of the identity of the first communication device.

[0025] In another embodiment of this application, the method may include decoding the first MAC PDU into a first ADAP PDU, wherein a first ADAP header of the first ADAP PDU may include a source field indicating the identity of the second communication device and a destination field indicating the identity of the destination communication device. The method may include transmitting second data associated with the first data to the destination communication device when the destination communication device is not the first communication device. The step of transmitting the second data may include multiplexing the first data and third data into the second data, wherein the destination communication device of the third data is the same as the destination communication device of the first ADAP PDU. The step of multiplexing the first data and the third data may include: encoding the first data into a second ADAP PDU, wherein a second ADAP header of the second ADAP PDU may include a source field indicating the identity of the second communication device and a destination field indicating the identity of the destination communication device; and encoding the third data into a third ADAP PDU, wherein a third ADAP header of the third ADAP PDU may include a source field indicating the identity of the third communication device and a destination field indicating the identity of the destination communication device.

[0026] In embodiments of this application, the third communication device is different from the second communication device.

[0027] In another embodiment of this application, the step of multiplexing the first data and the third data may include encoding the second ADAP PDU and the third ADAP PDU into a second MAC PDU, wherein the header of the second MAC PDU may include a source field indicating the identity of the first communication device. The step of transmitting the second data may include encoding the second MAC PDU into the second data, wherein the second data may include second sidelink control information, and the second sidelink control information may include a source field indicating the identity of the first communication device. The source field of the second sidelink control information may include at least a portion of the identity of the first communication device.

[0028] Another embodiment of this disclosure provides an apparatus. According to some embodiments of this disclosure, the apparatus includes: at least one non-transitory computer-readable medium having computer-executable instructions stored therein; at least one receiving circuitry system; at least one transmitting circuitry system; and at least one processor coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuitry system, and the at least one transmitting circuitry system, wherein the at least one non-transitory computer-readable medium and the computer-executable instructions are configured to use the at least one processor to cause the apparatus to perform a method according to some embodiments of this disclosure. Attached Figure Description

[0029] To illustrate the advantages and features of this disclosure, the description of the disclosure is presented with reference to specific embodiments illustrated in the accompanying drawings. These drawings depict only exemplary embodiments of the disclosure and should therefore not be construed as limiting its scope.

[0030] Figure 1A illustrates a schematic wireless communication system according to some embodiments of the present disclosure;

[0031] Figure 1B illustrates a schematic wireless communication system according to some embodiments of the present disclosure;

[0032] Figure 2A illustrates an example block diagram of a protocol stack for relay according to some embodiments of the present disclosure;

[0033] Figure 2B illustrates an example block diagram of a protocol stack for relay according to some embodiments of the present disclosure;

[0034] Figure 2C illustrates an example block diagram of a protocol stack for relay according to some embodiments of the present disclosure;

[0035] Figure 2D illustrates an example block diagram of a protocol stack for relay according to some embodiments of the present disclosure;

[0036] Figure 3A illustrates an exemplary MAC PDU according to some embodiments of the present disclosure;

[0037] Figure 3B illustrates an exemplary MAC PDU according to some embodiments of the present disclosure;

[0038] Figure 4 illustrates an exemplary MAC subheader according to some embodiments of the present disclosure;

[0039] Figure 5A is a flowchart illustrating an exemplary process for performing side-link communication according to some embodiments of the present disclosure;

[0040] Figure 5B is a flowchart illustrating an exemplary process for performing side-link communication according to some embodiments of the present disclosure;

[0041] Figure 5C is a flowchart illustrating an exemplary process for performing side-link communication according to some embodiments of the present disclosure;

[0042] Figure 5D is a flowchart illustrating an exemplary process for performing side-link communication according to some embodiments of the present disclosure;

[0043] Figure 5E is a flowchart illustrating an exemplary process for performing side-link communication according to some embodiments of the present disclosure; and

[0044] Figure 6 illustrates an example block diagram of a device according to some embodiments of the present disclosure. Detailed Implementation

[0045] The detailed description of the accompanying drawings is intended as a description of preferred embodiments of the present disclosure and is not intended to represent the only form in which the present disclosure may be practiced. It should be understood that the same or equivalent functionality may be achieved through different embodiments intended to be covered within the spirit and scope of the present disclosure.

[0046] Figure 1A illustrates an illustrative wireless communication system 100A according to some embodiments of the present disclosure.

[0047] Referring to Figure 1A, the wireless communication system 100A may include a base station (e.g., BS 120) and several UEs (e.g., UE 110A, UE 110B, and UE 110C). Although only one BS 120 and three UEs are illustrated in Figure 1 for simplicity, it is considered that in some other embodiments of this disclosure, the wireless communication system 100A may also include more BS 120s and more or fewer UEs located within and outside the coverage area of ​​the BS 120.

[0048] The UE and base station may support communication 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 may include, for example, but not limited to, computing devices, wearable devices, mobile devices, IoT devices, etc. UE 110B and UE 110C may include devices that are the same as or similar to UE 110A. UE 110B and UE 110C may also include devices that are different from UE 110A. Those skilled in the art will understand that the terminology described in this disclosure may change as technology develops and advances, but this should not affect or limit the principles and spirit of this disclosure.

[0049] BS 120 may define one or more cells, and each cell may have a coverage area 130. In the exemplary wireless communication system 100A, UE 110A, UE 110B, and UE 110C are within the coverage area of ​​BS 120 (i.e., within the coverage area). BS 120 may not be the specific BS 120 shown in Figure 1A, and may be any of the BS 120s in the wireless communication system. For example, in the case where the wireless communication system includes two BS 120s with UE 110D (not shown in Figure 1), UE 110D being within the coverage area of ​​BS 120 in the wireless communication system means that UE 110D is within the coverage area of ​​either of the two BS 120s; and UE 110D being outside the coverage area of ​​BS 120 in the wireless communication system means that UE 110D is outside the coverage area of ​​either BS 120.

[0050] UE 110A, UE 110B, and UE 110C can communicate with BS 120 via, for example, a Uu link (not shown in Figure 1A), and can also communicate with each other via sidelinks (indicated by the dashed arrows in Figure 1A) (e.g., the PC5 interface as defined in 3GPP specification TS 23.303). During sidelink communication, a UE can act as a relay node (hereinafter referred to as a "relay UE"), relaying data from a transmitting UE (hereinafter referred to as a "Tx UE") to a receiving UE (hereinafter referred to as a "Rx UE"). For example, referring to Figure 1A, a Tx UE (e.g., UE 110B) can transmit data to an Rx UE (e.g., UE 110C) via a relay UE (e.g., UE 110A).

[0051] Figure 1B illustrates an illustrative wireless communication system 100B according to some embodiments of the present disclosure.

[0052] As shown in Figure 1B, the wireless communication system 100B may include a base station (e.g., BS 120') and several UEs (e.g., UE 110A', UE 110B', and UE 110C'). The above description of BS 120, UE 110A, UE 110B, and UE 110C in Figure 1A also applies to the wireless communication system 100B in Figure 1B, except that UE 110A' and UE 110C' are within the coverage area of ​​BS 120' (i.e., within coverage area) and UE 110B' is outside the coverage area of ​​BS 120' (i.e., outside coverage area). In this scenario, since UE 110B' is outside the coverage area of ​​BS 120', it cannot communicate with BS 120' via the Uu link. On the other hand, UE 110A' and UE 110C' can communicate with BS 120' via the Uu link (not shown in Figure 1B). UE 110A' and UE 110C' can also communicate with each other and with UE 110B' via a sidelink (indicated by the dashed arrow in Figure 1A) (e.g., the PC5 interface as defined in 3GPP specification TS23.303). During sidelink communication, the Tx UE (e.g., UE 110B') can transmit data to the Rx UE (e.g., UE 110C') via a relay UE (e.g., UE 110A').

[0053] Although for simplicity, Figure 1B only shows UE 110B' outside the coverage of BS 120', in some other embodiments of this disclosure, it is considered that one or both of UE 110A' and UE 110C' may also be outside the coverage of BS 120'.

[0054] Figures 2A to 2D illustrate example block diagrams of protocol stacking for Layer 2 relay according to embodiments of the present disclosure.

[0055] Figure 2A illustrates an example block diagram of a Layer 2 trunk user plane (UP) protocol stack 200A supporting Tx UE (e.g., UE 210B), trunk UE (e.g., UE 210A), and Rx UE (e.g., UE 210C) according to some embodiments of the present disclosure. Tx UE 210B may be connected to trunk UE 210A via a side link (e.g., PC5 interface 270a). Trunk UE 210A may be connected to Rx UE 210C via a side link (e.g., PC5 interface 270b).

[0056] The following describes the data flow of Protocol Stack 200A.

[0057] As illustrated in Figure 2A, the UE 210B protocol stack may include a Service Data Adaptation Protocol (SDAP) layer 220B, a Packet Data Convergence Protocol (PDCP) layer 230B, a Radio Link Control (RLC) layer 240B, a Media Access Control (MAC) layer 250B, and a Physical (PHY) layer 260B.

[0058] At UE 210B, a higher layer (e.g., the Internet Protocol (IP) layer, not shown in Figure 2A) can pass IP packets to SDAP layer 220B. SDAP layer 220B can add SDAP headers to SDAP SDUs received from higher layers to form SDAP Packet Data Units (PDUs), and can pass SDAP PDUs to lower layers (e.g., PDCP layer 230B). PDCP layer 230B can add PDCP headers to PDCP SDUs received from SDAP layer 220B, and can pass PDCP SDUs to lower layers (e.g., RLC layer 240B). RLC layer 240B can add RLC headers to RLC SDUs received from PDCP layer 230B, and can pass RLC SDUs to lower layers (e.g., MAC layer 250B). MAC layer 250B can add a MAC header to the MAC SDU received from RLC layer 240B to form a MAC PDU, and can pass the MAC PDU to a lower layer (e.g., PHY layer 260B). PHY layer 260B can add information such as Cyclic Redundancy Check (CRC) information to the transport block (TB) corresponding to the MAC PDU for transmission. It can also transmit control information corresponding to the TB, such as sidelink control information.

[0059] UE 210A may include a receive protocol stack and a transmit protocol stack. The receive protocol stack of UE 210A may include RLC layer 240A, MAC layer 250A, and PHY layer 260A. The transmit protocol stack of UE 210A may include RLC layer 240A', MAC layer 250A', and PHY layer 260A'.

[0060] UE 210A can receive data from UE 210B. For example, at the receive protocol stack of UE 210A, PHY layer 260A can receive and decode data from UE 210B, and can pass the TB decoded from the data to the upper layer (e.g., MAC layer 250A). MAC layer 250A can decode the MAC PDU corresponding to the TB, and can pass the MAC SDU to the upper layer (e.g., RLC layer 240A). RLC layer 240A can decode the RLC PDU received from MAC layer 250A, and can pass the decoded data (e.g., RLC SUD) to the transmit protocol stack of UE 210A.

[0061] The transmit protocol stack of UE 210A can receive decoded data from the receive protocol stack of UE 210A. For example, RLC layer 240A' can receive decoded data from the receive protocol stack of UE 210A and encode it into an RLC PDU for transmission to a lower layer (e.g., MAC layer 250A'). MAC layer 250A' can encode the MAC SDU from RLC layer 240A' into a MACPDU for transmission to a lower layer (e.g., PHY layer 260A'). PHY layer 260A' can add information such as CRC to the TB corresponding to the MAC PDU for transmission to the destination device (e.g., UE 210C). Control information corresponding to the TB, such as sidelink control information, can also be transmitted.

[0062] Similar to UE 210B, the protocol stack of UE 210C may include SDAP layer 220C, PDCP layer 230C, RLC layer 240C, MAC layer 250C and PHY layer 260C.

[0063] UE 210C can receive data from UE 210A. For example, PHY layer 260C can receive and decode data from UE 210A, and can pass the decoded TB to the upper layer (e.g., MAC layer 250C). MAC layer 250C can decode the MAC PDU corresponding to the TB, and can pass the MAC SDU to the upper layer (e.g., RLC layer 240C). RLC layer 240C can decode the RLC PDU and can pass the RLC SDU to the upper layer (e.g., PDCP layer 230C). PDCP layer 230C can decode the PDCP PDU and can pass the PDCP SDU to the upper layer (e.g., SDAP layer 220C). SDAP layer 220C can decode the SDAP PDU and can pass the SDAP SDU to the upper layer (e.g., IP layer, not shown in Figure 2A).

[0064] Figure 2B illustrates an example block diagram of an UP protocol stack 200B supporting Layer 2 relay at a Tx UE (e.g., UE 211B), a relay UE (e.g., UE 211A), and an Rx UE (e.g., UE 211C) according to some embodiments of the present disclosure. Tx UE 211B may be connected to relay UE 211A via a side link (e.g., PC5 interface 271a). Relay UE 211A may be connected to Rx UE 211C via a side link (e.g., PC5 interface 271b).

[0065] As shown in Figure 2B, the UE 211B protocol stack may include SDAP layer 221B, PDCP layer 231B, RLC layer 241B, MAC layer 251B, and PHY layer 261B. UE 211A may include a receive protocol stack and a transmit protocol stack. The receive protocol stack of UE 211A may include MAC layer 251A and PHY layer 261A. The transmit protocol stack of UE 211A may include MAC layer 251A' and PHY layer 261A'. The UE 211C protocol stack may include SDAP layer 221C, PDCP layer 231C, RLC layer 241C, MAC layer 251C, and PHY layer 261C.

[0066] The above description of the data flow of protocol stack 200A in Figure 2A can also be applied to protocol stack 200B in Figure 2B, except that the receive and transmit protocol stacks of UE 211A do not include an RLC layer. In this scenario, MAC layer 251A' can receive decoded data from the receive protocol stack of UE 211A and encode it into a MAC PDU for transmission to a lower layer (e.g., PHY layer 261A'). PHY layer 261A' can add, for example, CRC information to the TB corresponding to the MAC PDU for transmission to the destination device (e.g., UE 211C). It can also transmit control information corresponding to the TB, such as sidelink control information.

[0067] Figure 2C illustrates an example block diagram of an UP protocol stack 200C supporting Layer 2 relay at a Tx UE (e.g., UE 212B), a relay UE (e.g., UE 212A), and an Rx UE (e.g., UE 212C) according to some embodiments of the present disclosure. Tx UE 212B may be connected to relay UE 212A via a side link (e.g., PC5 interface 272a). Relay UE 212A may be connected to Rx UE 212C via a side link (e.g., PC5 interface 272b).

[0068] As shown in Figure 2C, the UE 212B protocol stack may include SDAP layer 222B, PDCP layer 232B, ADAP layer 282B, RLC layer 242B, MAC layer 252B, and PHY layer 262B. UE 212A may include a receive protocol stack and a transmit protocol stack. The receive protocol stack of UE 212A may include ADAP layer 282A, RLC layer 242A, MAC layer 252A, and PHY layer 262A. The transmit protocol stack of UE 212A may include ADAP layer 282A', RLC layer 242A', MAC layer 252A', and PHY layer 262A'. The UE 212C protocol stack may include SDAP layer 222C, PDCP layer 232C, ADAP layer 282C, RLC layer 242C, MAC layer 252C, and PHY layer 262C.

[0069] The above description of the data flow of protocol stack 200A in Figure 2A can also be applied to protocol stack 200C in Figure 2C, except that the protocol stacks of UE 212A, UE 212B, and UE 212C include the corresponding ADAP layers (e.g., ADAP layers 282A, 282A', 282B, and 282C) above the corresponding RLC layers (e.g., RLC layers 242A, 242A', 242B, and 242C). In this scenario, at UE 212B, PDCP layer 232B can pass PDCP PDUs to ADAP layer 282B, and ADAP layer 282B can pass ADAPPDUs to RLC layer 242B. At UE 212C, RLC layer 242C can pass RLC SDUs to ADAP layer 282C, and ADAP layer 282C can pass ADAP SDUs to PDCP layer 232C.

[0070] Similarly, at the receive protocol stack of UE 212A, ADAP layer 282A can receive ADAP PDUs from RLC layer 242A and can pass decoded data (e.g., ADAP SDUs) to the transmit protocol stack of UE 212A. At the transmit protocol stack of UE 212A, ADAP layer 282A' can receive decoded data from the receive protocol stack of UE 212A and can pass ADAPPDUs to RLC layer 242A'.

[0071] Figure 2D illustrates an example block diagram of an UP protocol stack 200D supporting Layer 2 relay at a Tx UE (e.g., UE 213B), a relay UE (e.g., UE 213A), and an Rx UE (e.g., UE 213C) according to some embodiments of the present disclosure. Tx UE 213B may be connected to relay UE 213A via a side link (e.g., PC5 interface 273a). Relay UE 213A may be connected to Rx UE 213C via a side link (e.g., PC5 interface 273b).

[0072] As shown in Figure 2D, the UE 213B protocol stack may include SDAP layer 223B, PDCP layer 233B, RLC layer 243B, ADAP layer 283B, MAC layer 253B, and PHY layer 263B. UE 213A may include a receive protocol stack and a transmit protocol stack. The receive protocol stack of UE 213A may include RLC layer 243A, ADAP layer 283A, MAC layer 253A, and PHY layer 263A. The transmit protocol stack of UE 213A may include RLC layer 243A', ADAP layer 283A', MAC layer 253A', and PHY layer 263A'. The UE 213C protocol stack may include SDAP layer 223C, PDCP layer 233C, RLC layer 243C, ADAP layer 283C, MAC layer 253C, and PHY layer 263C.

[0073] The above description of the data flow of protocol stack 200C in Figure 2C can also be applied to protocol stack 200D in Figure 2D, except that ADAP layers 283B, 283A, 283A' and 283C in Figure 2D are below the corresponding RLC layers (e.g., RLC layers 243A, 243A', 243B and 243C) and above the corresponding MAC layers (e.g., MAC layers 253A, 253A', 253B and 253C).

[0074] In this scenario, at UE 213B, RLC layer 242B can pass the RLC PDU to ADAP layer 283B, and ADAP layer 283B can pass the ADAP PDU to MAC layer 253B. At UE 213C, MAC layer 253C can pass the MAC SDU to ADAP layer 283C, and ADAP layer 283C can pass the ADAP SDU to RLC layer 243C. Similarly, at the receive protocol stack of UE 213A, ADAP layer 283A can decode the ADAP PDU from MAC layer 253A and pass the ADAP SDU to RLC layer 243A. At the transmit protocol stack of UE 213A, ADAP layer 282A' can receive the ADAP SDU from RLC layer 243A' and pass the ADAP PDU to MAC layer 253A'.

[0075] Figures 3A and 3B illustrate exemplary formats of MAC PDUs according to embodiments of the present disclosure.

[0076] Figure 3A illustrates an exemplary MAC PDU 300A structure according to some embodiments of the present disclosure. As shown in Figure 3A, the MAC PDU 300A structure may include a MAC header and at least one MAC SDU. In some embodiments, the MAC PDU 300A structure may include, for example, padding at the end of the MAC PDU. The MAC header may include a Side Link Shared Channel (SL-SCH) sub-header and at least one MAC sub-header corresponding to at least one MAC SDU. In some embodiments, the MAC header may include a padding sub-header corresponding to, for example, padding located at the end of the MAC header. At least one MAC SDU and padding (if any) may be referred to as the MAC payload.

[0077] The SL-SCH subheader can contain seven header fields: V / R / R / R / R / SRC / DST. The MAC subheader can contain six header fields: R / R / E / LCID / F / L, while the padding subheader can contain four fields: R / R / E / LCID. The meanings of these fields are listed below:

[0078] -V: The MAC PDU format version number field indicates the version of the SL-SCH subheader used. The V field can have 4 digits and can be set to "0001", "0010", or "0011".

[0079] -R: Reserved fields can be reserved for future use and can have 1 bit set to "0".

[0080] -SRC: The Source ID field indicates the identity of the source.

[0081] -DST: The Destination ID field indicates the identity of the destination.

[0082] -E: Extended Fields indicates whether there are additional fields in the MAC header, and can have 1 bit.

[0083] -LCID: The Logical Channel ID (LCID) field identifies the logical channel instance of the corresponding MAC SDU or the corresponding MAC control element or the type of padding.

[0084] -L: The length field can indicate the length of the corresponding MAC SDU in bytes.

[0085] -F: The format field can indicate the size of the length field. The F field can have 1 bit and can be set to "0" to indicate that the length field is 8 bits, or it can be set to "1" to indicate that the length field is 16 bits.

[0086] The specific definitions of the MAC header and the fields in the MAC header are defined in 3GPP specifications TS 36.321 and TS 38.321.

[0087] Figure 3B illustrates an exemplary MAC PDU 300B structure according to some embodiments of the present disclosure. The MAC PDU 300B structure may be referred to as an interleaved format of the MAC PDU.

[0088] As shown in Figure 3B, the MAC PDU 300B structure may include at least one MAC sub-header and at least one MAC SDU. Each of the at least one MAC sub-header corresponds to a corresponding one of the at least one MAC SDU. For example, a MAC PDU may begin with a MAC sub-header followed immediately by a corresponding MAC SDU. Another MAC sub-header may follow the MAC SDU, and another corresponding MAC SDU may follow the other MAC sub-header. In some embodiments, the MAC PDU 300B structure may include a filler and a filler sub-header immediately following the filler located, for example, at the end of the MAC PDU. In some embodiments, a MAC PDU may begin with an SL-SCH sub-header, followed by a MAC sub-header and a MAC SDU in sequence.

[0089] In some embodiments of this disclosure, the specific definitions of the MAC subheader and MAC SDU in the MAC PDU 300B structure, as well as the specific definitions of the padding, padding subheader, and SL-SCH subheader (if any), are the same as those described with respect to FIG3A.

[0090] In some embodiments of this disclosure, the MAC subheader may have a new structure, which will be described in detail below with reference to the accompanying drawings.

[0091] Figure 4 illustrates an exemplary MAC subheader 400 structure according to some embodiments of the present disclosure. The MAC subheader 400 structure can be applied to the MAC subheader field shown in Figure 3B.

[0092] As shown in Figure 4, the MAC subheader 400 structure can be octet aligned. The MAC subheader 400 can contain 6 bytes, referred to in Figure 4 as "Oct 1", "Oct 2", "Oct 3", "Oct 4", "Oct 5", and "Oct 6", respectively. It is worth noting that the MAC subheader 400 can have a different structure than that illustrated in Figure 4. For example, according to some other embodiments of the invention, "Oct 1" shown in Figure 4 can contain more or fewer bits.

[0093] The MAC subheader 400 structure may contain fields 401, 402, 403, 404, 405, and 406. Fields 401, 402, 403, 404, 405, and 406 may be the R field, F field, LCID field, L field, SRC field, and DST field, respectively. These fields may have the same definitions as the corresponding fields described above with respect to Figure 3A.

[0094] For example, field 405 can be a source ID field, and can be used to indicate the identity of the source communication device from which it transmits data in the corresponding MAC SDU. Field 406 can be a destination ID field, and can be used to indicate the identity of the destination communication device to which the data in the corresponding MAC SDU is transmitted.

[0095] Although for simplicity, Figure 4 shows that fields 401, 402, 403, 404, 405, and 406 contain 1 bit, 1 bit, 6 bits, 8 bits, 16 bits, and 16 bits, respectively, it is worth considering that in some other embodiments of this disclosure, these fields may each contain more or fewer bits. For example, fields 405 and 406 may contain 24 bits.

[0096] During the discovery process, communication device A can discover communication device B, and communication device B can discover communication device C. Communication device B can establish sidelink communication with communication device A, and communication device A can establish sidelink communication with communication device C. In this case, even if communication device B is located far from communication device C, communication device B can still perform sidelink communication with communication device C via communication device A. In this case, communication device A can act as a relay node, relaying data from communication device B to communication device C, and vice versa. Further details regarding the process of performing sidelink communication will be described in detail below with reference to the accompanying drawings.

[0097] The following procedures can be applied to communication devices within the coverage area of ​​a base station and to communication devices outside the coverage area of ​​a base station.

[0098] Figure 5A illustrates a flowchart of an exemplary process 500A for performing sidelink communication according to some embodiments of the present disclosure.

[0099] In some instances, communication device 510A can be used as communication device 110A in FIG1A, communication device 110A' in FIG1B, UE 210A in FIG2A, or UE 211A in FIG2B. Communication device 510B can be used as communication device 110B in FIG1A, communication device 110B' in FIG1B, UE 210B in FIG2A, or UE 211B in FIG2B. Communication device 510C can be used as communication device 110C in FIG1A, communication device 110C' in FIG1B, UE 210C in FIG2A, or UE 211C in FIG2B.

[0100] During the discovery process, communication device 510A can discover communication device 510B, and communication device 510B can discover communication device 510C. As mentioned above, even if communication device 510B is located away from communication device 510C, communication device 510B can still establish sidelink communication with communication device 510C via communication device 510A. After establishing such communication, communication device 510B can transmit data to communication device 510C via communication device 510A. In this case, communication device 510B can be the source communication device for the data, communication device 510C can be the destination communication device for the data, and communication device 510A can be a relay communication device.

[0101] The exemplary process 500A demonstrates the process by which a source communication device (e.g., communication device 510B) communicates with a destination communication device (e.g., communication device 510C) via a relay communication device (e.g., communication device 510A).

[0102] Referring to FIG5A, in operation 511, communication device 510B may transmit a connection request to communication device 510A. In some embodiments of this disclosure, the connection request to communication device 510A may be transmitted via an Access Layer (AS) message. In operation 513, communication device 510A may transmit a connection request to communication device 510C. In some embodiments of this disclosure, the connection request to communication device 510C may be transmitted via an AS message.

[0103] In some embodiments of this disclosure, a connection request between two communication devices may include an indication of an association between a logical channel and another different communication device. In some embodiments, such an association may be configured by a base station. In some other embodiments, such an association may be pre-configured.

[0104] For example, in some embodiments of this disclosure, a connection request from a source communication device (e.g., communication device 510B) to a relay communication device (e.g., communication device 510A) may include an indication that a logical channel between the source communication device (e.g., communication device 510B) and the relay communication device (e.g., communication device 510A) is associated with a destination communication device (e.g., communication device 510C). In this way, at least a portion of the logical channel between the source communication device (e.g., communication device 510B) and the relay communication device (e.g., communication device 510A) may be configured to be associated with a corresponding destination communication device. Through such an indication, the relay communication device can identify the destination communication device of the data to be transmitted on the logical channel.

[0105] In some embodiments, the source communication device may be located within the coverage area of ​​the base station. In these embodiments, the association between the logical channel and the destination device may be configured by the base station or may be pre-configured at the source communication device. In some embodiments, the source communication device may be located outside the coverage area of ​​the base station. In these embodiments, the association between the logical channel and the destination device may be pre-configured at the source communication device.

[0106] In some embodiments of this disclosure, a connection request from a relay communication device (e.g., communication device 510A) to a destination device (e.g., communication device 510C) may include an indication that the logical channel between the relay communication device (e.g., communication device 510A) and the destination communication device (e.g., communication device 510C) is associated with a source communication device (e.g., communication device 510B). In this way, at least a portion of the logical channel between the relay communication device (e.g., communication device 510A) and the destination communication device (e.g., communication device 510C) may be configured to be associated with a corresponding source communication device. Through such an indication, the destination communication device can identify the source communication device from which data to be received on the logical channel.

[0107] In some embodiments, the relay communication device may be located within the coverage area of ​​the base station. In these embodiments, the association between the logical channel and the source device may be configured by the base station or may be pre-configured at the relay communication device. In some embodiments, the relay communication device may be located outside the coverage area of ​​the base station. In these embodiments, the association between the logical channel and the source device may be pre-configured at the relay communication device.

[0108] Referring again to Figure 5A, in operation 515, communication device 510C may send an acknowledgment to communication device 510A in response to receiving a connection request from communication device 510A. In operation 517, communication device 510A may send an acknowledgment to communication device 510B in response to receiving an acknowledgment from communication device 510C.

[0109] Following the above process, communication device 510B and communication device 510C can communicate with each other via communication device 510A. In some embodiments of this disclosure, communication device 510D (not shown in FIG. 5A) can establish sidelink communication with communication device 510C or a different communication device (e.g., communication device 511E, not shown in FIG. 5A) via communication device 510A by performing operations similar to operations 511 to 517.

[0110] After establishing communication with communication device 510C via communication device 510A, communication device 510B can transmit data to communication device 510C via communication device 510A.

[0111] Communication device 510B can encode data to be transmitted to communication device 514C via communication device 514A. For example, in some embodiments of this disclosure, at the MAC layer, communication device 510B can encode SDUs from an upper layer (e.g., RLC layer) into a MAC PDU. The MAC PDU can adopt the MAC PDU 300A structure in FIG3A or the MAC PDU 300B structure in FIG3B.

[0112] In some embodiments of this disclosure, the header of the MAC PDU may include a destination field indicating the identity of a relay communication device (e.g., communication device 510A). In some embodiments, the destination field may include at least a portion of the identity of the relay communication device. The header of the MAC PDU may include a source field indicating the identity of the source communication device (e.g., communication device 510B) of the data. In some embodiments, the source field may include at least a portion of the identity of the source communication device. The header of the MAC PDU may be the SL-SCH subheader as described above with respect to Figures 3A and 3B.

[0113] In some embodiments of this disclosure, the communication device 510B can transmit a MAC PDU to the PHY layer. The PHY layer can receive a TB corresponding to the MAC PDU. In some embodiments, sidelink control information can be transmitted along with the TB. For example, the communication device 510B can transmit the sidelink control information before the transmission of the TB. The sidelink control information can indicate the time-frequency position of the corresponding sidelink data transmission (e.g., the transmission of the TB).

[0114] In some embodiments, sidelink control information may indicate the identity of a relay communication device (e.g., communication device 510A). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may contain at least a portion of the identity of the relay communication device, which may be combined with the destination field of the header of the MAC PDU to form the complete identity of the relay communication device. For example, the identity of the relay communication device may be a 24-bit UE ID. The sidelink control information may contain 8 bits or all 24 bits of the 24-bit UE ID. The destination field of the header of the MAC PDU may contain the remaining 16 bits or all 24 bits of the 24-bit UE ID.

[0115] In some embodiments, the sidelink control information may include a source field indicating the identity of a source communication device (e.g., communication device 510B). The source field of the sidelink control information may include at least a portion of the identity of the source communication device.

[0116] Following the encoding process described above, in operation 519, communication device 510B can transmit the encoded data to communication device 510A. Communication device 510A can receive data on the logical channel between communication device 510A and communication device 510B.

[0117] In operation 521, communication device 510A can decode the received data. For example, communication device 510A can determine whether to discard, relay, or accept data without relaying. Accepting data by communication device 510A means that the data was not relayed by communication device 510A.

[0118] In some embodiments of this disclosure, the data may include sidelink control information. Communication device 510A may determine whether to discard the data or pass it to an upper layer (e.g., the MAC layer) based on the sidelink control information. For example, communication device 510A may determine whether the sidelink control information indicates the identity of communication device 510A. When it is determined that the sidelink control information indicates the identity of communication device 510A, communication device 510A may pass the data to the MAC layer to determine whether to relay the data to the destination communication device. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 510A, communication device 510A may discard the received data.

[0119] In some embodiments of this disclosure, the communication device 510A may decode the received data into a MAC PDU. For example, when it is determined that sidelink control information indicates the identity of the communication device 510A, the communication device 510A may decode the received data into a MAC PDU. The communication device 510A may determine whether to discard data or pass data to an upper layer (e.g., the RLC layer) based on the header of the MAC PDU. The header of the MAC PDU may be the SL-SCH sub-header as described above with respect to Figures 3A and 3B.

[0120] For example, the destination field in the header of the MAC PDU can indicate the identity of the relay communication device. When the destination field in the header of the MAC PDU does not indicate the identity of the communication device 510A, the communication device 510A can discard the MAC PDU. Otherwise, when the destination field in the header of the MAC PDU indicates the identity of the communication device 510A, depending on the structure of the protocol stack of the communication device 510A, the communication device 510A can pass the MAC SDU of the MAC PDU to the RLC layer or the transmission protocol stack of the communication device 510A.

[0121] For example, in some embodiments, referring to FIG2A, after receiving data from UE 210B, UE 210A may decode it into a MAC PDU, and when it is determined that the destination field of the MAC PDU header indicates the identity of UE 210A, UE 210A may pass the MAC SDU to RLC layer 240A. RLC layer 240A may decode the RLC PDU and may pass the decoded data from the receive protocol stack to the transmit protocol stack of UE 210A. In some embodiments, referring to FIG2B, after receiving data from UE 211B, UE 211A may decode it into a MAC PDU, and when it is determined that the destination field of the MAC PDU header indicates the identity of UE 211A, UE 211A may pass the MAC SDU from the receive protocol stack to the transmit protocol stack of UE 211A.

[0122] In some embodiments of this disclosure, the sidelink control information may include at least a portion of the identity of the relay communication device, and the destination field of the header of the MAC PDU may include the remaining portion of the identity of the relay communication device or all bits of the identity of the relay communication device.

[0123] Referring back to FIG5A, in some embodiments of this disclosure, communication device 510A may determine the destination communication device of data received from communication device 510B. As mentioned above, an indication indicating the association between a logical channel and a destination device may be transmitted from communication device 510B to communication device 510A during a connection request process (e.g., in operation 511). Communication device 510A may determine the destination communication device of data from communication device 510B based on the indication.

[0124] For example, as mentioned above, communication device 510A can decode the received data into a MAC PDU. Communication device 510A can further decode a MAC SDU and its corresponding MAC sub-header from the MAC PDU. The MAC sub-header may contain an LCID field. The definition of this field is described above with reference to Figure 3A. Communication device 510A can then identify the logical channel corresponding to the received data based on the LCID field. Communication device 510A can determine that communication device 510C is the destination communication device for the data based on the identified logical channel corresponding to the received data, as indicated by the indication associated with communication device 510C.

[0125] In some embodiments of this disclosure, communication device 510A may encode data received from communication device 510B before transmitting it to a destination communication device (e.g., communication device 510C).

[0126] For example, in some embodiments of this disclosure, communication device 510A may encode data into a MAC PDU. The header of the MAC PDU may include a source field indicating the identity of the relay communication device (e.g., communication device 510A) from which the data is transmitted. In some embodiments, the source field may include at least a portion of the identity of the relay communication device. The header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 510C) from which the data is transmitted. In some embodiments, the destination field may include at least a portion of the identity of the destination communication device. The MAC PDU may adopt the structure of MAC PDU 300A in FIG. 3A or the structure of MAC PDU 300B in FIG. 3B.

[0127] In some embodiments of this disclosure, the MAC PDU may include a MAC SDU and a corresponding MAC subheader. The MAC subheader may include an LCID field. The definition of this field is described above with reference to FIG3A. As mentioned above, an indication indicating the association between a logical channel and a source device may be transmitted from communication device 510A to communication device 510C during a connection request process (e.g., in operation 513). Communication device 510A may determine the value of the LCID field based on the indication. For example, assuming that LCH#C between communication device 510A and communication device 510C is associated with communication device 510B, communication device 510A may set the LCID field of the MAC subheader to the LCID of LCH#C.

[0128] In some embodiments of this disclosure, communication device 510A may pass a MAC PDU to the PHY layer. The PHY layer may encode a TB corresponding to the MAC PDU for transmission to a destination communication device (e.g., communication device 510C). In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 510A may transmit the sidelink control information before the transmission of the TB.

[0129] In some embodiments, sidelink control information may indicate the identity of a relay communication device (e.g., communication device 510A). For example, the sidelink control information may include a source field. The source field of the sidelink control information may contain at least a portion of the identity of the relay communication device, which may be combined with the source field of the header of the MAC PDU to form the complete identity of the relay communication device. For example, the identity of the relay communication device may be a 24-bit UE ID. The sidelink control information may contain 8 bits or all 24 bits of the 24-bit UE ID. The destination field of the header of the MAC PDU may contain the remaining 16 bits or all 24 bits of the 24-bit UE ID.

[0130] In some embodiments, the sidelink control information may include a destination field that indicates the identity of the destination communication device (e.g., communication device 510C).

[0131] In some embodiments of this disclosure, in addition to receiving data on a logical channel between communication device 510A and communication device 510B, communication device 510A may also receive other data on a different logical channel from communication device 510B or a different communication device (e.g., communication device 510D, not shown in FIG. 5A). When the destination communication device of the other data is the same as the destination communication device of the data, communication device 510A may multiplex the other data and the data for transmission to the destination communication device. The method for determining the destination communication device of the other data is similar to the method for determining the destination communication device of the data as described above, and therefore is omitted here.

[0132] For example, when it is determined that both the other data and the data are destined for communication device 510C, communication device 510A can multiplex the other data and the data into the same MAC PDU. The header of the MAC PDU may include a source field indicating the identity of the communication device 510A (i.e., the relay communication device) and a destination field indicating the identity of the communication device 510C (i.e., the destination communication device). The definition of the MAC PDU header has been described above and is therefore omitted here.

[0133] In some embodiments of this disclosure, communication device 510A may encode the other data and the data into different or the same MAC SDU of the MAC PDU. As mentioned above, the value of the field of the MAC subheader corresponding to the MAC SDU may be determined based on the association between the logical channel and the source communication device. Communication device 510A may encode the other data and the data in a similar manner as described above, and therefore this is omitted here.

[0134] In some embodiments of this disclosure, the communication device 510A may pass the MAC PDU to the PHY layer. At the PHY layer, the communication device 510A may encode the TB corresponding to the MAC PDU in a similar manner as described above, and therefore this is omitted here.

[0135] In operation 523, communication device 510A can transmit encoded data to a destination communication device (e.g., communication device 510C). In operation 525, communication device 510C can decode the received data. The decoding process in operation 525 is similar to the decoding process described above with respect to operation 521.

[0136] For example, data from communication device 510A may contain sidelink control information. Communication device 510C may determine whether to discard the data or pass it to an upper layer (e.g., the MAC layer) based on the sidelink control information. The definition of sidelink control information is described above with respect to operation 521. For example, when it is determined that the sidelink control information indicates the identity of communication device 510C, communication device 510C may pass the data to the MAC layer. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 510C, communication device 510C may discard the received data.

[0137] In some embodiments of this disclosure, the communication device 510C can decode received data into a MAC PDU. The communication device 510C can determine whether to discard the data or pass it to an upper layer (e.g., the RLC layer) based on the header of the MAC PDU. For example, when the destination field of the MAC PDU header does not indicate the identity of the communication device 510C, the communication device 510C can discard the MAC PDU. Otherwise, when the destination field of the MAC PDU header indicates the identity of the communication device 510C, the communication device 510C can pass the MAC SDU of the MAC PDU to an upper layer (e.g., the RLC layer). The header of the MAC PDU can be the SL-SCH sub-header as described above with respect to Figures 3A and 3B.

[0138] In some embodiments of this disclosure, communication device 510C can determine that communication device 510C is the destination device for data. Communication device 510C can determine the source communication device for data from communication device 510A. As mentioned above, an indication indicating the association between a logical channel and a source device may be transmitted from communication device 510A to communication device 510C during a connection request process (e.g., in operation 513). Communication device 510C can determine the source communication device for data from communication device 510A based on the indication.

[0139] For example, communication device 510C can decode received data into a MAC PDU. Communication device 510C can further decode a MAC SDU and its corresponding MAC sub-header from the MAC PDU. The MAC sub-header may contain an LCID field. Then, communication device 510C can identify the logical channel corresponding to the data based on the LCID field. Communication device 510C can determine that communication device 510B is the source communication device of the data based on the identified logical channel corresponding to the data, as indicated by the indication associated with communication device 510B.

[0140] Figure 5B illustrates a flowchart of an exemplary process 500B for performing sidelink communication according to some embodiments of the present disclosure.

[0141] In some instances, communication device 511A can be used as communication device 110A in FIG1A, communication device 110A' in FIG1B, UE 210A in FIG2A, or UE 211A in FIG2B. Communication device 511B can be used as communication device 110B in FIG1A, communication device 110B' in FIG1B, UE 210B in FIG2A, or UE 211B in FIG2B. Communication device 511C can be used as communication device 110C in FIG1A, communication device 110C' in FIG1B, UE 210C in FIG2A, or UE 211C in FIG2B.

[0142] Similar to Figure 5A, exemplary process 500B illustrates the process by which a source communication device (e.g., communication device 511B) communicates with a destination communication device (e.g., communication device 511C) via a relay communication device (e.g., communication device 511A).

[0143] Referring to FIG5B, in operation 531, the source communication device (e.g., communication device 511B) may transmit a connection request to the relay communication device (e.g., communication device 511A). In some embodiments of this disclosure, the connection request to communication device 511A may be transmitted via AS layer messages.

[0144] In some embodiments of this disclosure, a connection request to a relay communication device (e.g., communication device 511A) may include an indication to at least one destination communication device (e.g., communication device 511C). Such an indication allows the relay communication device to know whether data to be transmitted to it should be forwarded or relayed to the destination device.

[0145] In operation 533, communication device 511A may transmit a connection request to communication device 511C. In some embodiments of this disclosure, the connection request to communication device 511C may be transmitted via access layer (AS) messages.

[0146] In operation 535, communication device 511C may send an acknowledgment to communication device 511A in response to receiving a connection request from communication device 511A. In operation 537, communication device 511A may send an acknowledgment to communication device 511B in response to receiving an acknowledgment from communication device 511C.

[0147] Following the above process, communication device 511B and communication device 511C can communicate with each other via communication device 511A. In some embodiments of this disclosure, communication device 511D (not shown in FIG. 5B) can establish sidelink communication with communication device 511C or a different communication device (e.g., communication device 511E, not shown in FIG. 5B) via communication device 511A by performing operations similar to operations 531 to 537.

[0148] After establishing communication with communication device 511C via communication device 511A, communication device 511B can transmit data to communication device 511C via communication device 511A.

[0149] In some embodiments of this disclosure, at the MAC layer, communication device 511B may encode the SDU from an upper layer (e.g., the RLC layer) into a MAC PDU. The header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 511C). In some embodiments, the destination field may include at least a portion of the identity of the destination communication device. The header of the MAC PDU may include a source field indicating the identity of the source communication device (e.g., communication device 511B). In some embodiments, the source field may include at least a portion of the identity of the source communication device. The header of the MAC PDU may be an SL-SCH subheader as described above with respect to Figures 3A and 3B.

[0150] Communication device 511B can transmit a MAC PDU to the PHY layer. The PHY layer can receive a TB corresponding to the MAC PDU for transmission. In some embodiments, sidelink control information can be transmitted along with the TB. For example, communication device 511B can transmit the sidelink control information before the transmission of the TB. The sidelink control information can indicate the time-frequency location of the corresponding sidelink data transmission (e.g., the transmission of the TB). In some embodiments, the sidelink control information can indicate the identity of a relay communication device (e.g., communication device 511A). For example, the sidelink control information can include a destination field. The destination field of the sidelink control information can include at least a portion of the identity of the relay communication device. For example, the identity of the relay communication device can be a 24-bit UE ID. The sidelink control information can include 8 bits or all 24 bits of the 24-bit UE ID. In some embodiments, the sidelink control information can include a source field indicating the identity of a source communication device (e.g., communication device 511B).

[0151] Following the encoding process described above, in operation 539, communication device 511B can transmit data to communication device 511A. In operation 541, communication device 511A can decode the received data. For example, communication device 511A can determine whether to discard, relay, or accept the data.

[0152] In some embodiments of this disclosure, the data may include sidelink control information. Communication device 511A may determine whether to discard the data or pass it to an upper layer (e.g., the MAC layer) based on the sidelink control information. For example, communication device 511A may determine whether the sidelink control information indicates the identity of communication device 511A. When it is determined that the sidelink control information indicates the identity of communication device 511A, communication device 511A may pass the data to the MAC layer. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 511A, communication device 511A may discard the received data.

[0153] In some embodiments of this disclosure, when the sidelink control information indicates the identity of communication device 511A, communication device 511A can decode the received data into a MAC PDU and pass it to the MAC layer. The MAC PDU can adopt the MAC PDU 300A structure in FIG3A or the MAC PDU 300B structure in FIG3B. Communication device 511A can determine whether to relay or receive data based on the header of the MAC PDU. The header of the MAC PDU can be the SL-SCH sub-header as described above with respect to FIG3A and 3B.

[0154] As mentioned above, an indication of at least one destination communication device may be transmitted from communication device 511B to communication device 511A during the connection request process (e.g., in operation 531). Communication device 511A may determine the destination communication device of the data from communication device 511B based on the indication.

[0155] For example, the destination field of the header of the MAC PDU decoded from data received from communication device 511B can indicate the identity of the destination communication device. When the destination field of the MAC PDU header indicates the identity of communication device 511A, it means that communication device 511A is the destination communication device for the data and that communication device 511A can accept the MAC PDU. When the destination field of the MAC PDU header indicates one of at least one of the destination communication devices indicated by the indications mentioned above, communication device 511A can relay the data to the communication device indicated in the destination field of the MAC PDU header. For example, communication device 511A can pass the MAC SDU of the MAC PDU to an upper layer (e.g., RLC layer) or transmission protocol stack of communication device 511A.

[0156] For example, in some embodiments, referring to FIG2A, after receiving data from UE 210B, UE 210A may decode it into a MAC PDU, and when it is determined that UE 210C is indicated in the aforementioned indication, UE 210A may pass the MAC SDU to RLC layer 240A. RLC layer 240A may decode the SDU and may pass the decoded data from the receive protocol stack to the transmit protocol stack of UE 210A. In some embodiments, referring to FIG2B, after receiving data from UE 211B, UE 211A may decode it into a MAC PDU, and when it is determined that UE 210C is indicated in the aforementioned indication, the MAC SDU may be passed from the receive protocol stack to the transmit protocol stack of UE 211A.

[0157] In some embodiments of this disclosure, communication device 511A may encode data from communication device 511B before it is transmitted to the destination communication device (e.g., communication device 511C).

[0158] For example, communication device 511A may encode data into a MAC PDU. The MAC PDU may adopt the MAC PDU 300A structure in FIG. 3A or the MAC PDU 300B structure in FIG. 3B. The header of the MAC PDU may include a source field indicating the identity of the source communication device (e.g., communication device 511B) of the data. In some embodiments, the source field may include at least a portion of the identity of the source communication device. The header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 511C) of the data. In some embodiments, the destination field may include at least a portion of the identity of the destination communication device. The header of the MAC PDU may be an SL-SCH subheader as described above with respect to FIG. 3A and 3B.

[0159] In some embodiments of this disclosure, communication device 511A may pass a MAC PDU to the PHY layer. The PHY layer may encode a TB corresponding to the MAC PDU for transmission to a destination communication device (e.g., communication device 511C). In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 511A may transmit the sidelink control information before the transmission of the TB. In some embodiments, the sidelink control information may indicate the identity of a relay communication device (e.g., communication device 511A). For example, the sidelink control information may include a source field. The source field of the sidelink control information may include at least a portion of the identity of the relay communication device. For example, the identity of the relay communication device may be a 24-bit UE ID. The sidelink control information may include 8 bits or all 24 bits of the 24-bit UE ID. In some embodiments, the sidelink control information may include a destination field indicating the identity of a destination communication device (e.g., communication device 511C).

[0160] In operation 543, communication device 511A can transmit encoded data to a destination communication device (e.g., communication device 511C). In operation 545, communication device 511C can decode the received data. The decoding process in operation 525 is similar to the decoding process described above with respect to operation 541.

[0161] For example, communication device 511C may determine whether to discard or accept data from communication device 511A. In some embodiments of this disclosure, at the PHY layer, communication device 511C may determine whether to discard data or pass data to an upper layer (e.g., the MAC layer) based on sidelink control information. The definition of sidelink control information was described above with respect to operation 541 and is therefore omitted here. For example, when it is determined that the sidelink control information indicates the identity of communication device 511C, communication device 511C may pass data to the MAC layer. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 511C, communication device 511C may discard the received data.

[0162] In some embodiments of this disclosure, at the MAC layer, communication device 511C can determine the destination and source communication device of the data based on the header of the MAC PDU decoded from the received data. The definition of the MAC PDU header is described above with respect to operation 521 and is therefore omitted here. The MAC PDU header can be the SL-SCH sub-header as described above with respect to Figures 3A and 3B. For example, communication device 511B can be identified as the source communication device of the data based on the source field of the MAC PDU header indicating the identity of communication device 511B. Communication device 511C can be identified as the destination communication device of the data based on the destination field of the MAC PDU header indicating the identity of communication device 511C. Communication device 511C can then accept data and can pass the MAC PDU to an upper layer (e.g., the RLC layer) for further decoding.

[0163] Figure 5C illustrates a flowchart of an exemplary process 500C for performing sidelink communication according to some embodiments of the present disclosure.

[0164] In some instances, communication device 512A can be used as communication device 110A in FIG1A, communication device 110A' in FIG1B, UE 210A in FIG2A, or UE 211A in FIG2B. Communication device 512B can be used as communication device 110B in FIG1A, communication device 110B' in FIG1B, UE 210B in FIG2A, or UE 211B in FIG2B. Communication device 512C can be used as communication device 110C in FIG1A, communication device 110C' in FIG1B, UE 210C in FIG2A, or UE 211C in FIG2B.

[0165] Similar to Figures 5A and 5B, exemplary process 500C illustrates the process by which a source communication device (e.g., communication device 512B) communicates with a destination communication device (e.g., communication device 512C) via a relay communication device (e.g., communication device 512A).

[0166] In operation 551, communication device 512B (i.e., the source communication device) may encode data to be transmitted to communication device 512C via communication device 512A.

[0167] For example, in some embodiments of this disclosure, at the MAC layer, the communication device 512B may encode the SDU from an upper layer (e.g., the RLC layer) into a MAC PDU. The MAC PDU may have an interleaved format as described above with respect to FIG3B. That is, the MAC PDU may include at least one MAC subheader and at least one MAC SDU, and each of the at least one MAC subheader corresponds to a corresponding one of the at least one MAC SDU.

[0168] In some embodiments of this disclosure, each of at least one MAC sub-header may include a source field and a destination field. The destination field may include at least a portion of the identity of the destination communication device. The source field may include at least a portion of the identity of the source communication device. For example, the identity of the communication device may be a 24-bit UE ID. The destination field and source field of the MAC sub-header may include 16 bits or all 24 bits of the 24-bit UE ID of the corresponding communication device.

[0169] For example, a MAC PDU may contain two MAC SDUs (SDU#1 and SDU#2) and two corresponding MAC subheaders (Subheader #1 and Subheader #2). A MAC PDU may begin with Subheader #1, followed by SDU#1, Subheader #2, and Subheader #3. Subheader #1 may contain a source field indicating the source communication device of SDU#1 and a destination field indicating the destination communication device of SDU#1. Subheader #2 may contain a source field indicating the source communication device of SDU#2 and a destination field indicating the destination communication device of SDU#2. The destination field of Subheader #1 may be the same as or different from the destination field of Subheader #2. In other words, data destined for different devices can be multiplexed within the same MAC PDU. In some instances, a MAC PDU may contain fewer or more MAC SDUs and corresponding MAC subheaders.

[0170] In some embodiments of this disclosure, the MAC subheader 400 structure described above with respect to FIG4 may be applied to each of at least one MAC subheader of a MAC PDU.

[0171] In some embodiments of this disclosure, communication device 512B may pass a MAC PDU to the PHY layer. The PHY layer may receive a TB corresponding to the MAC PDU for transmission. In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 512B may transmit the sidelink control information before the transmission of the TB. In some embodiments, the sidelink control information may indicate the identity of a relay communication device (e.g., communication device 512A). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may include at least a portion of the identity of the relay communication device. For example, the identity of the relay communication device may be a 24-bit UE ID. The sidelink control information may include 8 bits or all 24 bits of the 24-bit UE ID.

[0172] In operation 553, communication device 512B can transmit data to communication device 512A. In operation 555, communication device 512A can decode the received data.

[0173] In some embodiments of this disclosure, the data may include sidelink control information. Communication device 512A may determine whether to discard the data or pass it to an upper layer (e.g., the MAC layer) based on the sidelink control information. For example, communication device 512A may determine whether the sidelink control information indicates the identity of communication device 512A. When it is determined that the sidelink control information indicates the identity of communication device 512A, communication device 512A may pass the data to the MAC layer. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 512A, communication device 512A may discard the received data.

[0174] In some embodiments of this disclosure, communication device 512A can decode received data into a MAC PDU. For example, when it is determined that sidelink control information indicates the identity of communication device 512A, communication device 512A can decode received data into a MAC PDU. As mentioned above, the MAC PDU may have an interleaved format as described above with respect to FIG3B. Communication device 512A can decode or demultiplex the MAC PDU into at least one MAC SDU and at least one MAC subheader corresponding to the at least one MAC SDU. The MAC subheader may have the MAC subheader 400 structure shown in FIG4. Therefore, communication device 512A can determine the corresponding source communication device and the corresponding destination communication device of at least one MAC SDU. Communication device 512A can encode or multiplex two or more MAC SDUs having the same destination communication device into the same MAC PDU. The two or more MAC SDUs may be received on the same or different logical channels. For example, the LCID fields of the MAC subheaders corresponding to the two or more MAC SDUs may be different.

[0175] In some embodiments of this disclosure, communication device 512D (not shown in FIG. 5C) can also establish sidelink communication with communication device 512C via communication device 512A. In addition to receiving data from communication device 512B, communication device 512A can also receive additional data from communication device 512D for relay to communication device 512C. Similar to decoding data from communication device 512B, communication device 512A can decode additional data from communication device 512D. In some embodiments, communication device 512A can determine that the destination communication device of the MAC SDU of the data is the same as that of another MAC SDU of the other data. Communication device 512A can encode or multiplex MAC SDUs received on different logical channels and another MAC SDU into the same MACPDU.

[0176] In some embodiments of this disclosure, communication device 512A may encode the MAC PDU according to the interleaved format as described above with respect to FIG. 3B. The MAC subheader of the MAC PDU may have the MAC subheader 400 structure shown in FIG. 4. For example, communication device 512A may encode the MAC PDU in a similar manner to that described above with respect to operation 551.

[0177] In some embodiments of this disclosure, communication device 512A may pass a MAC PDU to the PHY layer. The PHY layer may receive a TB corresponding to the MAC PDU for transmission. In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 512A may transmit the sidelink control information before the transmission of the TB. In some embodiments, the sidelink control information may indicate the identity of a relay communication device (e.g., communication device 512A).

[0178] Such indications in the sidelink control information can be used for retransmission combination. For example, if communication device 512C fails to decode previous data, communication device 512A can retransmit the data to communication device 512C. Using the indications in the sidelink control information, communication device 512C can identify that the retransmitted data and the previous data come from the same communication device (e.g., communication device 512A). Communication device 512C can combine the retransmitted data with the previous data to decode the data. Retransmission combination can advantageously improve the decoding success rate.

[0179] In some embodiments, the sidelink control information may include a source field. The source field of the sidelink control information may include at least a portion of the identity of the relay communication device. For example, the identity of the relay communication device may be a 24-bit UE ID. The sidelink control information may include 8 bits or all 24 bits of the 24-bit UE ID. In some embodiments, the sidelink control information may include a destination field indicating the identity of the destination communication device (e.g., communication device 512C).

[0180] In operation 557, communication device 512A can transmit encoded data to a destination communication device (e.g., communication device 512C).

[0181] In operation 559, communication device 512C can decode the received data. The decoding process in operation 559 is similar to the decoding process described above with respect to operation 555. For example, communication device 512C can determine the corresponding source communication device and the corresponding destination communication device of the MAC SDU in the MAC PDU based on the destination field and source field in the corresponding MAC subheader.

[0182] Figures 5D and 5E illustrate exemplary processes for performing sidelink communication according to embodiments of the present disclosure. The protocol stack of the communication apparatus in Figures 5D and 5E may include an ADAP layer above the RLC layer (as shown in Figure 2C) or between the MAC layer and the RLC layer (as shown in Figure 2D). The exemplary processes in Figures 5D and 5E are based on the assumption that the ADAP layer is located above the RLC layer. However, corresponding modifications to the exemplary processes in Figures 5D and 5E will be apparent to those skilled in the art to serve the condition that the ADAP layer is located between the MAC layer and the RLC layer.

[0183] Figure 5D illustrates a flowchart of an exemplary process 500D for performing sidelink communication according to some embodiments of the present disclosure.

[0184] In some instances, communication device 513A may be used as communication device 110A in FIG1A, communication device 110A' in FIG1B, UE 212A in FIG2C, or UE 213A in FIG2D. Communication device 513B may be used as communication device 110B in FIG1A, communication device 110B' in FIG1B, UE 212B in FIG2C, or UE 213B in FIG2D. Communication device 513C may be used as communication device 110C in FIG1A, communication device 110C' in FIG1B, UE 212C in FIG2C, or UE 213C in FIG2D.

[0185] Similar to Figures 5A to 5C, exemplary process 500D illustrates the process by which a source communication device (e.g., communication device 513B) communicates with a destination communication device (e.g., communication device 513C) via a relay communication device (e.g., communication device 513A).

[0186] In operation 561, communication device 513B (i.e., the source communication device) may encode data to be transmitted to communication device 513C via communication device 513A.

[0187] For example, in some embodiments of this disclosure, at the ADAP layer, communication device 513B can encode an SDU from an upper layer (e.g., the PDCP layer) into a MAC PDU. The header of the ADAP PDU may include a source field indicating the identity of the source communication device (e.g., communication device 513B) and a destination field indicating the identity of the destination communication device (e.g., communication device 513C). The ADAP SDU of the ADAP PDU may contain data to be transmitted from the source communication device to the destination communication device. Communication device 513B can pass at least one ADAP PDU to a lower layer (e.g., the RLC layer).

[0188] In some embodiments of this disclosure, at the RLC layer, the communication device 513B can encode SDUs from an upper layer (e.g., the ADAP layer) into an RLC PDU, and can pass at least one RLC PDU to a lower layer (e.g., the MAC layer).

[0189] In some embodiments of this disclosure, at the MAC layer, communication device 513B can encode the SDU from an upper layer (e.g., the RLC layer) into a MAC PDU. The header of the MAC PDU may include a destination field indicating the identity of a relay communication device (e.g., communication device 513A). In some embodiments, the destination field may include at least a portion of the identity of the relay communication device. The header of the MAC PDU may include a source field indicating the identity of a source communication device (e.g., communication device 513B). In some embodiments, the source field may include at least a portion of the identity of the source communication device. The header of the MAC PDU may be an SL-SCH subheader as described above with respect to Figures 3A and 3B. Communication device 513B can pass the MAC PDU to a lower layer (e.g., the PHY layer).

[0190] In some embodiments of this disclosure, at the PHY layer, communication device 513B may encode a TB corresponding to a MAC PDU for transmission. In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 513B may transmit the sidelink control information prior to the transmission of the TB. In some embodiments, the sidelink control information may indicate the identity of a relay communication device (e.g., communication device 513A). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may contain at least a portion of the identity of the relay communication device, which may be combined with the destination field of the header of the MAC PDU to form the complete identity of the relay communication device.

[0191] For example, the identity of a relay communication device can be a 24-bit UE ID. Sidelink control information can contain 8 bits of the 24-bit UE ID or all 24 bits. The destination field of the MAC PDU header can contain the remaining 16 bits of the 24-bit UE ID or all 24 bits.

[0192] In some embodiments, the side link control information may include a source field that indicates the identity of the source communication device (e.g., communication device 513B).

[0193] Following the encoding process described above, in operation 563, communication device 513B can transmit the encoded data to communication device 513A. In operation 565, communication device 513A can decode the received data.

[0194] In some embodiments of this disclosure, the data may include sidelink control information. Communication device 513A may determine whether to discard the data or pass it to an upper layer (e.g., the MAC layer) based on the sidelink control information. For example, communication device 513A may determine whether the sidelink control information indicates the identity of communication device 513A. When it is determined that the sidelink control information indicates the identity of communication device 513A, communication device 513A may pass the data to the MAC layer. Otherwise, when it is determined that the sidelink control information does not indicate the identity of communication device 513A, communication device 513A may discard the received data.

[0195] In some embodiments of this disclosure, communication device 513A may decode received data into a MAC PDU. For example, when it is determined that sidelink control information indicates the identity of communication device 513A, communication device 513A may decode received data into a MAC PDU. The MAC PDU may adopt the MAC PDU 300A structure in FIG3A or the MAC PDU 300B structure in FIG3B. Communication device 513A may determine whether to discard the MAC PDU or pass it to an upper layer (e.g., the RLC layer) based on the MAC PDU header. The MAC PDU header may be the SL-SCH sub-header as described above with respect to FIG3A and 3B.

[0196] For example, communication device 513A can determine whether the destination field in the header of the MAC PDU indicates the identity of communication device 513A. When it is determined that the destination field indicates the identity of communication device 513A, communication device 513A can pass the data to the RLC layer. Otherwise, when it is determined that the destination field does not indicate the identity of communication device 513A, communication device 513A can discard the received data.

[0197] In some embodiments of this disclosure, communication device 513A can decode received data into an ADAP PDU. For example, communication device 513A can decode a MAC PDU into an RLC PDU and an RLC PDU into an ADAP PDU. As mentioned above regarding operation 561, the header of the ADAP PDU may include a source field indicating the identity of the source communication device (e.g., communication device 513B) and a destination field indicating the identity of the destination communication device (e.g., communication device 513C). Therefore, communication device 513A can determine the destination communication device of the ADAP SDU in the ADAP PDU based on the destination field in the header of the ADAP PDU and can relay the received data to the destination communication device.

[0198] For example, communication device 513A can determine that the destination of data received from communication device 513B is communication device 513C based on the header of ADAP PDU, and can relay the received data to communication device 513C.

[0199] In some embodiments of this disclosure, communication device 513A may encode data from communication device 513B before transmission to a destination communication device (e.g., communication device 513C). Communication device 513A may encode data in a manner similar to that described above with respect to operation 561, with at least one of the following exceptions:

[0200] The header of a MAC PDU may include a source field indicating the identity of a relay communication device (e.g., communication device 513A). In some embodiments, the source field may include at least a portion of the identity of the relay communication device.

[0201] The header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 513C). In some embodiments, the destination field may include at least a portion of the identity of the relay communication device.

[0202] Side link control information can indicate the identity of a relay communication device (e.g., communication device 513A), which can be used for retransmission recombining. For example, the side link control information may include a source field. The source field of the side link control information may contain at least a portion of the identity of the relay communication device.

[0203] Sidelink control information may indicate the identity of the destination communication device (e.g., communication device 513C). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may contain at least a portion of the identity of the destination communication device (e.g., communication device 513C).

[0204] In some embodiments of this disclosure, communication device 513D (not shown in FIG. 5D) can also establish sidelink communication with communication device 513C via communication device 513A. In addition to receiving data from communication device 513B, communication device 513A can also receive additional data from communication device 513D for relay to communication device 513C. Similar to decoding data from communication device 513B, communication device 513A can decode additional data from communication device 513D. In some embodiments, communication device 513A can determine that the destination communication device of the ADAP SDU of the data is the same as that of another ADAP SDU of the other data. Communication device 513A can encode or multiplex the ADAP SDU and another ADAP SDU into different ADAP PDUs, which can be encoded into the same MAC PDU.

[0205] For example, in some embodiments of this disclosure, an ADAP SDU may be encoded into ADAP PDU #1. The header of ADAP PDU #1 may include a source field indicating the identity of communication device 513B and a destination field indicating the identity of communication device 513C. Another ADAP SDU may be encoded into ADAP PDU #2. The header of ADAP PDU #2 may include a source field indicating the identity of communication device 513D and a destination field indicating the identity of communication device 513C. ADAP PDU #1 and ADAP PDU #2 may be encoded into the same MAC PDU. The header of the MAC PDU may include a source field indicating the identity of a relay communication device (e.g., communication device 513A) and a destination field indicating the identity of a destination communication device (e.g., communication device 513C).

[0206] In operation 567, communication device 513A may transmit encoded data to a destination communication device (e.g., communication device 513C).

[0207] In operation 569, communication device 513C can decode the received data. The decoding process in operation 569 is similar to the decoding process described above with respect to operation 565. Communication device 513C can determine the source communication device and the destination communication device of the data at the ADAP layer. For example, communication device 513C can determine the corresponding source communication device and the corresponding destination communication device of the ADAP SDU in the ADAP PDU based on the destination field and the source field in the header of the ADAP PDU.

[0208] Figure 5E illustrates a flowchart of an exemplary process 500E for performing sidelink communication according to some embodiments of the present disclosure.

[0209] In some instances, communication device 514A may be used as communication device 110A in FIG1A, communication device 110A' in FIG1B, UE 212A in FIG2C, or UE 213A in FIG2D. Communication device 514B may be used as communication device 110B in FIG1A, communication device 110B' in FIG1B, UE 212B in FIG2C, or UE 213B in FIG2D. Communication device 514C may be used as communication device 110C in FIG1A, communication device 110C' in FIG1B, UE 212C in FIG2C, or UE 213C in FIG2D.

[0210] Similar to Figures 5A to 5D, exemplary process 500E illustrates the process by which a source communication device (e.g., communication device 514B) communicates with a destination communication device (e.g., communication device 514C) via a relay communication device (e.g., communication device 514A).

[0211] In operation 571, communication device 514B (i.e., the source communication device) may encode data to be transmitted to communication device 514C via communication device 514A.

[0212] For example, in some embodiments of this disclosure, at the ADAP layer, communication device 514B can encode an SDU from an upper layer (e.g., the PDCP layer) into a MAC PDU. The header of the ADAP PDU may include a field indicating the identity of a relay communication device (e.g., communication device 514A). The field may contain at least a portion of the relay communication device's identity. Communication device 514B can pass at least one ADAP PDU to a lower layer (e.g., the RLC layer).

[0213] In some embodiments of this disclosure, at the RLC layer, the communication device 514B can encode SDUs from an upper layer (e.g., the ADAP layer) into an RLC PDU, and can pass at least one RLC PDU to a lower layer (e.g., the MAC layer).

[0214] In some embodiments of this disclosure, at the MAC layer, communication device 514B can encode the SDU from an upper layer (e.g., the RLC layer) into a MAC PDU. The header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 514C). In some embodiments, the destination field may include at least a portion of the identity of the destination communication device. The header of the MAC PDU may include a source field indicating the identity of the source communication device (e.g., communication device 514B). In some embodiments, the source field may include at least a portion of the identity of the source communication device. The header of the MAC PDU may be an SL-SCH subheader as described above with respect to Figures 3A and 3B. Communication device 514B can pass the MAC PDU to a lower layer (e.g., the PHY layer).

[0215] In some embodiments of this disclosure, at the PHY layer, communication device 514B may encode a TB corresponding to a MAC PDU for transmission. In some embodiments, sidelink control information may be transmitted along with the TB. For example, communication device 514B may transmit the sidelink control information prior to the transmission of the TB. In some embodiments, the sidelink control information may indicate the identity of a relay communication device (e.g., communication device 514A). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may contain at least a portion of the identity of the relay communication device.

[0216] Following the encoding process described above, in operation 573, communication device 514B can transmit the encoded data to communication device 514A. In operation 565, communication device 514A can decode the received data.

[0217] In some embodiments of this disclosure, the data may include sidelink control information. The communication device 514A may determine whether to discard data or pass data to an upper layer (e.g., the MAC layer) based on the sidelink control information.

[0218] In some embodiments of this disclosure, communication device 514A may decode received data into a MAC PDU. As mentioned above with respect to operation 571, the header of the MAC PDU may include a destination field indicating the identity of the destination communication device (e.g., communication device 514C) and a source field indicating the identity of the source communication device (e.g., communication device 514B).

[0219] In some embodiments of this disclosure, communication device 514A may decode received data into an ADAP PDU. As mentioned above regarding operation 571, the header of the ADAP PDU may include a field indicating the identity of the relay communication device (e.g., communication device 514A). Communication device 514A may determine whether to discard or relay data based on the fields in the ADAP PDU header. For example, communication device 514A may determine whether the aforementioned field indicates the identity of communication device 514A. When it is determined that the aforementioned field indicates the identity of communication device 514A, communication device 514A may pass the data to an upper layer (e.g., the MAC layer). Otherwise, when it is determined that the aforementioned field does not indicate the identity of communication device 514A, communication device 514A may discard the received data.

[0220] In some embodiments of this disclosure, communication device 514A may encode data from communication device 514B before transmission to a destination communication device (e.g., communication device 514C). Communication device 514A may encode data in a manner similar to that described above with respect to operation 571, with at least one of the following exceptions:

[0221] Side link control information can indicate the identity of a relay communication device (e.g., communication device 514A), which can be used for retransmission combinations. For example, the side link control information may include a source field. The source field of the side link control information may contain at least a portion of the identity of the relay communication device.

[0222] Sidelink control information may indicate the identity of the destination communication device (e.g., communication device 514C). For example, the sidelink control information may include a destination field. The destination field of the sidelink control information may contain at least a portion of the identity of the destination communication device (e.g., communication device 514C).

[0223] - The ADAP layer configuration described above regarding operation 571 may not be applied.

[0224] In operation 577, communication device 514A can transmit encoded data to a destination communication device (e.g., communication device 514C).

[0225] In operation 579, communication device 514C can decode the received data. The decoding process in operation 579 is similar to the decoding process described above with respect to operation 575. Communication device 514C can determine the source communication device and destination communication device of the data at the MAC layer. For example, communication device 514C can determine the source communication device and destination communication device of the MAC SDU in the MAC PDU based on the destination field and source field in the header of the MAC PDU.

[0226] Those skilled in the art will understand that some of the operations in exemplary procedures 500A to 500E can be eliminated without departing from the spirit and scope of this disclosure.

[0227] Figure 6 illustrates an example block diagram of a device 600 according to some embodiments of the present disclosure.

[0228] As shown in Figure 6, device 600 may include at least one non-transitory computer-readable medium (not shown in Figure 6), a receiving circuit system 602, a transmitting circuit system 604, and a processor 606 coupled to the non-transitory computer-readable medium (not shown in Figure 6), the receiving circuit system 602, and the transmitting circuit system 604. Device 600 may be a communication device (e.g., UE).

[0229] Although elements such as processor 606, transmitting circuitry system 604, and receiving circuitry system 602 are described in the singular in this figure, plural forms may be considered unless explicitly stated otherwise. In some embodiments of this disclosure, receiving circuitry system 602 and transmitting circuitry system 604 are combined into a single device, such as a transceiver. In some embodiments of this disclosure, device 600 may further include input devices, memory, and / or other components.

[0230] In some embodiments of this disclosure, a non-transitory computer-readable medium may have computer-executable instructions stored thereon to cause a processor to implement methods relating to a communication apparatus as described above. For example, when executed, the computer-executable instructions cause processor 606 to interact with receiver circuitry 602 and transmitter circuitry 604 to perform steps relating to the communication apparatus or UE depicted in Figures 1A-1B, 2A-2D, and 5A-5E.

[0231] Those skilled in the art will understand that the steps of the methods described in connection with the aspects disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or a combination of both. The software module can reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. Furthermore, in some aspects, the steps of the method can reside as one or any combination or set of code and / or instructions on a non-transitory computer-readable medium that can be incorporated into a computer program product.

[0232] While this disclosure has been described with reference to specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations may be readily apparent. For example, various components of the embodiments may be interchanged, added, or substituted in other embodiments. Furthermore, not all elements of each figure are essential for the operation of the disclosed embodiments. For example, those skilled in the art to which the disclosed embodiments pertain will be able to make and use the teachings of this disclosure by simply employing the elements of the independent claims. Therefore, the embodiments of this disclosure as described herein are intended to be illustrative and not restrictive. Various changes may be made without departing from the spirit and scope of this disclosure.

[0233] In this document, the terms “includes” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements may include not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus. Unless otherwise specified, an element beginning with “a” or the like does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the term “another” is defined as at least a second or more. As used herein, the terms “having” and the like are defined as “includes”.

Claims

1. A method (500A) executed by a first communication device (510A), comprising: Receive (519) first data from the second communication device (510B), wherein the first data includes first side link control information and the first side link control information includes a destination field indicating the identity of the first communication device (510A); decode (521) the first data into a first media access control (MAC) protocol data unit (PDU), wherein the first MAC PDU includes at least one MAC subheader and at least one MAC service data unit (SDU), each of the at least one MAC subheader corresponds to a corresponding one of the at least one MAC SDU, and each MAC subheader includes a source field and a destination field; wherein the source field indicates the identity of the source communication device of the corresponding MAC SDU, and the destination field indicates the identity of the destination communication device (510C) of the corresponding MAC SDU.

2. The method (500A) of claim 1, wherein the source field includes at least a portion of the identity of the source communication device, and wherein the destination field includes at least a portion of the identity of the destination communication device (510C).

3. The method (500A) according to claim 1, wherein the first MAC PDU includes a first MAC SDU and a second MAC SDU, and the destination communication device (510C) of the first MAC SDU is different from the destination communication device (510C) of the second MAC SDU.

4. The method (500A) of claim 1, wherein the first MAC PDU comprises a first MAC SDU, and the method (500A) further comprises: When the destination communication device (510C) of the first MAC SDU is not the first communication device (510A), the second data associated with the first data is transmitted (523) to the destination communication device (510C) of the first MAC SDU. Optionally, the step of transmitting (523) the second data includes: multiplexing the first data and the third data into the second data, wherein the first data and the third data are received from different logical channels, and the destination communication device (510C) of the third data is the same as the destination communication device (510C) of the first MAC SDU.

5. The method (500A) according to claim 4, wherein the step of multiplexing the first data and the third data includes: The first data is encoded into a second MAC SDU of a second MAC PDU, wherein the second MAC subheader corresponding to the second MAC SDU includes a source field indicating the identity of the source communication device of the first data and a destination field indicating the identity of the destination communication device (510C) of the first data; and the third data is encoded into a third MAC SDU of the second MAC PDU, wherein the third MAC subheader corresponding to the second MAC SDU includes a source field indicating the identity of the source communication device of the third data and a destination field indicating the identity of the destination communication device (510C) of the first data; and optionally, wherein the source communication device of the first data is different from the source communication device of the third data.

6. The method (500A) of claim 4, wherein the second data includes second side link control information, and the second side link control information includes a source field indicating the identity of the first communication device (510A).

7. The method of claim 1 (500A), further comprising: The first data is decoded into a first Media Access Control (MAC) Protocol Data Unit (PDU), wherein the first MAC PDU includes a first MAC header containing a destination field indicating the identity of the first communication device (510A).

8. The method (500A) of claim 7, wherein the destination field of the first side link control information includes a portion of the identity of the first communication device (510A), and the destination field of the first MAC header includes the remainder of the identity of the first communication device (510A).

9. The method of claim 7 (500A), further comprising: The first MAC PDU is decoded into a first adaptive ADAP PDU, wherein the first ADAP header of the first ADAP PDU includes a source field indicating the identity of the second communication device (510B) and a destination field indicating the identity of the destination communication device (510C); and when the destination communication device (510C) is not the first communication device (510A), the second data associated with the first data is transmitted to the destination communication device (510C).

10. The method of claim 9 (500A), wherein the step of transmitting the second data comprises: The first data and the third data are multiplexed into the second data, wherein the destination communication device (510C) of the third data is the same as the destination communication device (510C) of the first ADAP PDU.

11. The method (500A) of claim 10, wherein the step of multiplexing the first data and the third data comprises: The first data is encoded into a second ADAP PDU, wherein the second ADAP header of the second ADAP PDU includes a source field indicating the identity of the second communication device (510B) and a destination field indicating the identity of the destination communication device (510C); and the third data is encoded into a third ADAP PDU, wherein the third ADAP header of the third ADAP PDU includes a source field indicating the identity of the third communication device and a destination field indicating the identity of the destination communication device (510C).

12. The method (500A) according to claim 11, wherein the step of multiplexing the first data and the third data includes: The second ADAP PDU and the third ADAP PDU are encoded into a second MAC PDU, wherein the header of the second MAC PDU includes a source field indicating the identity of the first communication device (510A); as well as The step of transmitting the second data includes: encoding the second MAC PDU into the second data, wherein the second data includes second side link control information, and the second side link control information includes a source field indicating the identity of the first communication device (510A).

13. The method (500A) of claim 12, wherein the source field of the second side link control information includes at least a portion of the identity of the first communication device (510A).

14. An apparatus (600) comprising: At least one non-transitory computer-readable medium having computer-executable instructions stored thereon; At least one receiving circuit system (602); At least one transmitting circuit system (604); and at least one processor (606) coupled to the at least one non-transitory computer-readable medium, the at least one receiving circuit system (602), and the at least one transmitting circuit system (604), wherein the at least one non-transitory computer-readable medium and the computer-executable instructions are configured to use the at least one processor (606) to cause the device (600) to perform the method according to any one of claims 1-13.

15. A processor (606) for wireless communication, comprising: At least one controller coupled to at least one memory and configured such that the processor (606): receives (519) first data from a second communication device (510B), wherein the first data includes first sidelink control information and the first sidelink control information includes a destination field indicating the identity of a first communication device (510A); decodes (521) the first data into a first Media Access Control (MAC) Protocol Data Unit (PDU), wherein the first MAC PDU includes at least one MAC subheader and at least one MAC Service Data Unit (SDU), each of the at least one MAC subheader corresponding to a corresponding one of the at least one MAC SDU, and each MAC subheader includes a source field and a destination field; wherein the source field indicates the identity of the source communication device of the corresponding MAC SDU, and the destination field indicates the identity of the destination communication device (510C) of the corresponding MAC SDU.

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