Patent Publication Number: US-2022217612-A1

Title: Cooperative communication for sidelink relay

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is filed under 35 U.S.C. § 111(a) and is based on and hereby claims priority under 35 U.S.C. § 120 and § 365(c) from International Application No. PCT/CN2019/120895, titled “Methods and Apparatus of Cooperative Communication for Sidelink Relay,” with an international filing date of Nov. 26, 2019. This application is a continuation of International Application No. PCT/CN2019/120895. International Application No. PCT/CN2019/120895 is pending as of the filing date of this application, and the United States is an elected state in International Application No. PCT/CN2019/120895. The disclosure of each of the foregoing documents is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The disclosed embodiments relate generally to wireless communication, and, more particularly, to cooperative communication for sidelink relay. 
     BACKGROUND 
     5G radio access technology will be a key component of the modern access network. It will address high traffic growth and increasing demand for high-bandwidth connectivity. Wireless relay in cellular networks provides extended coverage and improved transmission reliability. Long term evolution (LTE) network introduced 3GPP sidelink, the direct communication between two user equipment (UEs) without signal relay through a base station. In 3GPP New Radio (NR), sidelink continues evolving. With new functionalities supported, the sidelink offers low latency, high reliability and high throughout for device-to-device communications. Using sidelink for wireless relay provides a reliable and efficient way for traffic forwarding. For the early sidelink-based wireless relay services, such as the ProSe UE-to-Network relay, the traffic between the remote UE and the base station is forwarded at the IP layer by the relay UE. The relay operation was specified for LTE aiming at coverage expansion from the perspective of Layer-3 (L3) relay. The Layer-2 (L2) based relay using sidelink can improve the efficiency and flexibility. The sidelink relay is further supported by integrated address backhaul (IAB) for the NR network to support packet routing and radio bearer mapping. The single path sidelink relay provides flexibility for coverage extension. As the NR network grows, the packet routing seeks more flexibility and reliability with cooperative communication functionalities. 
     Improvements and enhancements are required to use cooperative communication for the sidelink relay in the NR network. 
     SUMMARY 
     Apparatus and methods are provided for cooperative communication for sidelink relay. In one embodiment, a plurality of sidelink relay paths are configured for an end-to-end communication path between two end nodes, a source node and a destination node, with one or more relay UEs. The source node or one or more intermediate relay node(s) within the sidelink relay path performs packet, segment, or radio bearer based cooperative communication at the ACP layer. The cooperative communication includes data duplication and data split depending on one or more factors including a QoS requirement, a radio signal strength measurement, a successful rate of packet transmission, a preconfigured rule, a status of flow control, packet feedback information, detecting of a topology change, and available radio resources. In one embodiment, at least one field is carried by the ACP layer comprising a sequence number (SN), a segment information (SI), and a segment offset (SO) when the cooperative communication is one selecting from packet-based split, packet-based duplication, packet-based split and duplication hybrid, segment-based split, segment-based duplication, and segment-based split and duplication hybrid. 
     In one embodiment, the cooperative communication is supported by the weigh value transmission from the sender to the receiver node within the sidelink relay network. The weight value is statically configured or preconfigured. In another embodiment, the weigh value is dynamically carried by an ACP control packet data unit (PDU). In one embodiment, the cooperative communication is supported by the redundant packets or segments removal at the intermediate relay node(s), and/or destination node. 
     This summary does not purport to define the invention. The invention is defined by the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, where like numerals indicate like components, illustrate embodiments of the invention. 
         FIG. 1  is a schematic system diagram illustrating an exemplary NR network with cooperative communication for the sidelink relay in accordance with embodiments of the current invention. 
         FIG. 2  illustrates an exemplary NR wireless system with centralized upper layers of the NR radio interface stacks in accordance with embodiments of the current invention. 
         FIG. 3  illustrates an exemplary diagram for the UE-to-Network relay with cooperative communication in accordance with embodiments of the current invention. 
         FIG. 4  illustrates an exemplary diagram for the UE-to-UE relay with cooperative communication in accordance with embodiments of the current invention. 
         FIG. 5  illustrates an exemplary diagram for the hybrid relay with cooperative communication in accordance with embodiments of the current invention. 
         FIG. 6A  illustrates an exemplary user plane protocol stacks for relay path between the source end node and the destination end node with multiple relay UEs in accordance with embodiments of the current invention. 
         FIG. 6B  illustrates an exemplary control plane protocol stacks for relay path between the source end node and the destination end node with multiple relay UEs in accordance with embodiments of the current invention. 
         FIG. 7  illustrates an exemplary ACP layer packet-based split for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. 
         FIG. 8  illustrates an exemplary ACP layer packet-based duplication for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. 
         FIG. 9  illustrates an exemplary ACP layer packet-based hybrid operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. 
         FIG. 10  illustrates an exemplary ACP layer segment-based hybrid operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. 
         FIG. 11  illustrates an exemplary ACP layer radio bearer based split operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. 
         FIG. 12  illustrates exemplary diagrams for the detailed operations of the cooperative communication for the SL relay in accordance with embodiments of the current invention. 
         FIG. 13  illustrates an exemplary flow chart for the cooperative communication for the SL relay in accordance with embodiments of the current invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings. 
       FIG. 1  is a schematic system diagram illustrating an exemplary NR network with cooperative communication for the sidelink relay in accordance with embodiments of the current invention. Wireless system  100  includes one or more fixed base infrastructure units forming a network distributed over a geographical region. The base unit may also be referred to as an access point, an access terminal, a base station, a Node-B, an eNode-B (eNB), a gNB, or by other terminology used in the art. The network can be a homogeneous network or a heterogeneous network, which can be deployed with the same frequency or different frequency. gNB  101 , gNB  102  and gNB  103  are base stations in the NR network, the serving area of which may or may not overlap with each other. Backhaul connections such as  131 ,  132 , and  133 , connect the non-co-located receiving base units, such as gNB  101 ,  102  and  103 . These backhaul connections can be either ideal or non-ideal. gNB  101  is connected with gNB  102  via Xn interface  131  and is connected with gNB  103  via Xn interface  132 . gNB  102  is connected with gNB  103  via Xn interface  133 . 
     Wireless network  100  also includes multiple communication devices or mobile stations, such user equipments (UEs) such as UEs  111 ,  112 ,  113 ,  117 ,  118 ,  121 ,  122 ,  123 ,  125 ,  126 , and  128 . Communication devices or mobile stations in wireless network  100  may also refers to devices with wireless connectivity in a vehicle, such as mobile devices  118 ,  117  and  128 . The exemplary mobile devices in wireless network  100  have sidelink capabilities. The mobile devices can establish one or more connections with one or more base stations, such as gNB  101 ,  102 , and  103 . The mobile device may also be out of connection with the base stations with its access links but can transmit and receive data packets with another one or more other mobile stations or with one or more base stations through L2-based sidelink relay. 
     In one novel aspect, data packets are forwarded by one or more relay UEs with cooperative communication. A remote UE  111  and gNB  103  forms an end-to-end path  181  through a sidelink relay with cooperative communication with a relay UEs  121 ,  125 , and  126 . End-to-end path  181  between end nodes gNB  103  and remote UE  111  includes multiple relay paths. The first relay path includes an access link  135  between gNB  103  and relay UE  121 , a sidelink link  179  between relay UE  121  and relay UE  126 , and a sidelink  171  between remote UE  111  and relay UE  126 . The second relay path configured and established for the end-to-end path  181  includes an access link  138  between gNB  103  and relay UE  125  and a relay link  178  between relay UE  125  and end-node UE  111 . In another embodiment, the sidelink relay is a UE-to-Network multi-hop relay using sidelink configured. A remote UE  112  and gNB  102  forms an end-to-end path  182  through a sidelink relay with a relay UE  122  and another relay UE  123 . End-to-end path  182  includes an access link  136  between gNB  102  and relay UE  122 , sidelink  172  between relay UE  122  and relay UE  123 , and sidelink  173  between remote UE  112  and relay UE  123 . In yet another embodiment, a relay mobile device is configured with multiple remote mobile devices or multiple end node mobile devices. A relay UE  128 , with an access link  137  to gNB  101  is configured with two remote UEs  117  and  118  through sidelink  175  and  176 , respectively. In other embodiments, a relay mobile device can be configured for multiple UE-to-UE relay paths. Different links are established for the illustrated relay paths. An access link is a link between a base station, such as gNB and a mobile device, such as a UE. The UE can be a remote UE or a relay UE. The access link includes both the uplink (UL) and the downlink (DL) between the base station and the mobile device. The interface for the access link is an NR Uu interface. In one embodiment, the remote UE also establishes access link with a base station. A side link is a link between two mobile devices and uses PC5 interface. The sidelink can be a link between a remote UE/end-node UE and a relay UE or a link between two relay mobile devices/UEs for the multi-hop relay. The end-to-end link for a relay path can be a link between two end-node mobile devices for a UE-to-UE relay or a base station to mobile device for a UE-to-Network relay. An Xn link is the backhaul link between two base stations, such gNBs using the Xn interface. 
     In one novel aspect, a plurality of end-to-end relay paths are configured for a pair of end nodes including a source node and an end node UE. In one embodiment, the plurality of end-to-end relay paths include a plurality of relay links configured for a plurality of relay UE. The source node or the relay node performs packet or segment based cooperative communication at the ACP layer. The source node or the relay node UE performs cooperative communication to route data packets between the source node and the destination node UE, wherein cooperative communication includes an ACP layer function selecting from packet-based split, packet-based duplication, packet-based split and duplication hybrid, segment-based split, segment-based duplication, segment-based split and duplication hybrid, radio-bearer-based split, radio-bearer-based duplication, and radio-bearer-based split and duplication hybrid. 
       FIG. 1  further illustrates simplified block diagrams of a base station and a mobile device/UE for adaptation handling for cooperative communication for the sidelink relay. gNB  103  has an antenna  156 , which transmits and receives radio signals. An RF transceiver circuit  153 , coupled with the antenna, receives RF signals from antenna  156 , converts them to baseband signals, and sends them to processor  152 . RF transceiver  153  also converts received baseband signals from processor  152 , converts them to RF signals, and sends out to antenna  156 . Processor  152  processes the received baseband signals and invokes different functional modules to perform features in gNB  103 . Memory  151  stores program instructions and data  154  to control the operations of gNB  103 . gNB  103  also includes a set of control modules  155  that carry out functional tasks to communicate with mobile stations. 
       FIG. 1  also includes simplified block diagrams of a UE, such as relay UE  121  or remote UE  111 . The UE has an antenna  165 , which transmits and receives radio signals. An RF transceiver circuit  163 , coupled with the antenna, receives RF signals from antenna  165 , converts them to baseband signals, and sends them to processor  162 . In one embodiment, the RF transceiver may comprise two RF modules (not shown). A first RF module is used for HF transmitting and receiving, and the other RF module is used for different frequency bands transmitting and receiving which is different from the HF transceiver. RF transceiver  163  also converts received baseband signals from processor  162 , converts them to RF signals, and sends out to antenna  165 . Processor  162  processes the received baseband signals and invokes different functional modules to perform features in THE UE. Memory  161  stores program instructions and data  164  to control the operations of the UE. Antenna  165  sends uplink transmission and receives downlink transmissions to/from antenna  156  of gNB  103 . 
     The UE also includes a set of control modules that carry out functional tasks. These control modules can be implemented by circuits, software, firmware, or a combination of them. A sidelink controller  191  establishes one or SL in the wireless network. An adaptation control plane (ACP) protocol  192  configures an ACP layer on top of a radio link control (RLC) layer, wherein the ACP layer performs functions comprising radio bearer mapping, packet routing, and flow control. A relay path module  193  configures one or more SL relay paths, wherein the one or more SL relay paths is part of a plurality of end-to-end relay paths between a source node and a destination node UE with the relay UE being a relay node. A cooperative communication module  194  performs cooperative communication to route data packets between the source node and the destination node UE, wherein cooperative communication includes at least one of protocol layer functions packet-based split, packet-based duplication, packet-based split and duplication hybrid, segment-based split, segment-based duplication, segment-based split and duplication hybrid, radio-bearer-based split, radio-bearer-based duplication, and radio-bearer-based split and duplication hybrid. 
       FIG. 2  illustrates an exemplary NR wireless system with centralized upper layers of the NR radio interface stacks in accordance with embodiments of the current invention. Different protocol split options between the central unit (CU) and the distributed unit (DU) of gNB nodes may be possible. The functional split between the CU and DU of gNB nodes may depend on the transport layer. Low performance transport between the CU and DU of gNB nodes can enable the higher protocol layers of the NR radio stacks to be supported in the CU, since the higher protocol layers have lower performance requirements on the transport layer in terms of bandwidth, delay, synchronization, and jitter. In one embodiment, SDAP and PDCP layer are located in the CU, while RLC, MAC and PHY layers are located in the DU. A core unit  201  is connected with one central unit  211  with gNB upper layer  252 . In one embodiment  250 , gNB upper layer  252  includes the PDCP layer and optionally the SDAP layer. Central unit  211  is connected with distributed units  221 ,  222 , and  221 . Distributed units  221 ,  222 , and  223  each corresponds to a cell  231 ,  232 , and  233 , respectively. The DUs, such as  221 ,  222  and  223  includes gNB lower layers  251 . In one embodiment, gNB lower layers  251  include the PHY, MAC and the RLC layers. In another embodiment  260 , each gNB has the protocol stacks  261 , including SDAP, PDCP, RLC, MAC and PHY layers. 
       FIG. 3  illustrates an exemplary diagram for the UE-to-Network relay with cooperative communication in accordance with embodiments of the current invention. In a NR network, a gNB  310  is connected with a core network  330 . An end node UE  320  is configured to establish a plurality of relay path with one or more sidelink with gNB  310 . gNB  310  is configured to be the relay node with additional mobile terminal functionality. In one novel aspect, cooperative communication is performed by one or mor relay nodes, such as UE  301 ,  302 ,  303 ,  304 , and  305 , configured with a plurality of end-to-end relay paths between the end nodes, which are gNB  310  and end node UE  320 . The plurality of end-to-end relay paths includes Uu link and sidelink. In one embodiment, one or more intermedia relay node UEs, such as UE  303 ,  304 , and  305 , may also have Uu direct links with a gNB in the NR network. In another embodiment, one or more intermedia relay node UEs, such as UE  303 ,  304 , and  305 , and/or the end node UE  320  are out-of-coverage UEs. The end-to-end UE-to-network communication path includes three relay paths. A first relay path includes a Uu link  331  between gNB  310  and relay UE  301 , a sidelink  361  between relay UE  301  and relay UE  303 , and a sidelink  364  between relay UE  303  and end node UE  320 . A second relay path includes a Uu link  331  between gNB  310  and relay UE  301 , a sidelink  362  between relay UE  301  and relay UE  304 , and a sidelink  365  between relay UE  304  and end node UE  320 . A third relay path includes a Uu link  332  between gNB  310  and relay UE  302 , a sidelink  363  between relay UE  302  and relay UE  305 , and a sidelink  366  between relay UE  305  and end node UE  320 . In one embodiment, the cooperative functions are performed at the ACP layer of the relay UE. In another embodiment, the cooperative functions are performed at the source node. 
       FIG. 4  illustrates an exemplary diagram for the UE-to-UE relay with cooperative communication in accordance with embodiments of the current invention. A destination node/end node UE  420  is configured to establish a plurality of relay path with one or more sidelink with source node UE  410 . In one novel aspect, cooperative communication is performed by one or mor relay nodes, such as UE  401 ,  402 ,  403 ,  404 , and  405 , configured with a plurality of end-to-end relay paths between the end nodes, which are source node UE  410  and destination node/end node UE  420 . In one embodiment, one or more intermedia relay node UEs, such as UE  401 ,  402 ,  403 ,  404 , and  405 , also have Uu direct links with a gNB in the NR network. In another embodiment, one or more intermedia relay node UEs, such as UE  401 ,  402 ,  403 ,  404 , and  405 , and/or the end nodes UE  410  and  420  are out-of-coverage UEs. The exemplary end-to-end UE-to-UE communication path includes three relay paths. A first relay path includes a relay link  431  between source node UE  410  and relay UE  401 , a sidelink  461  between relay UE  401  and relay UE  403 , and a sidelink  464  between relay UE  403  and end node UE  420 . A second relay path includes relay link  431  between source node UE  410  and relay UE  401 , a sidelink  462  between relay UE  401  and relay UE  404 , and a sidelink  465  between relay UE  404  and end node UE  420 . A third relay path includes a relay link  432  between source node UE  410  and relay UE  402 , a sidelink  463  between relay UE  402  and relay UE  405 , and a sidelink  466  between relay UE  405  and end node UE  420 . In one embodiment, the cooperative functions are performed at the ACP layer of the relay UE. In another embodiment, the cooperative functions are performed at the source node. 
       FIG. 5  illustrates an exemplary diagram for the hybrid relay with cooperative communication in accordance with embodiments of the current invention. In a NR network, a gNB  510  is connected with a core network  530 . A destination end node UE  520  is configured to establish a plurality of relay path with one or more sidelink with gNB  510 . gNB  510  is configured to be the relay node with additional mobile terminal functionality. The relay path is configured with the hybrid relay network with integration of both network relay with network relay nodes  551  and  552  connecting with gNB  510  through links  531  and  532 , respectively. The hybrid relay path also includes UE relay nodes such as UE  501 ,  502 ,  503 , and  504 . In one novel aspect, cooperative communication is performed by one or mor relay nodes, such as UE  501 ,  502 ,  503 , and  504 , configured with a plurality of end-to-end relay paths between the end nodes, which are gNB  510  and end node UE  520 . The plurality of end-to-end relay paths includes Uu link and sidelink. In one embodiment, one or more intermedia relay node UEs, such as UE  501 ,  502 ,  503 , and  504 , also have Uu direct links with a gNB in the NR network. In another embodiment, one or more intermedia relay node UEs, such as UE  501 ,  502 ,  503 , and  504 , and/or the end node UE  320  are out-of-coverage UEs. The end-to-end UE-to-network communication path includes three relay paths. A first relay path includes a link  531  between gNB  510  and network relay note  551 , a link  561  between network node  551  and relay UE  501 , a sidelink  563  between relay UE  501  and relay UE  503 , and a sidelink  565  between relay UE  503  and end node UE  520 . A second relay path includes a link  531  between gNB  510  and network relay note  551 , a link  561  between network node  551  and relay UE  501 , a sidelink  564  between relay UE  501  and relay UE  504 , and a sidelink  566  between relay UE  504  and end node UE  520 . A third relay path includes a link  532  between gNB  510  and network relay note  552 , a link  563  between network node  553  and relay UE  503 , a sidelink  567  between relay UE  502  and end node UE  520 . In one embodiment, the cooperative functions are performed at the ACP layer of the relay UE. In another embodiment, the cooperative functions are performed at the source node. 
     In one embodiment, the cooperative communication is performed by the ACP layer of the relay UE. The ACP layer performs one or more functions including data split and data duplication based on the relay path configuration. 
       FIG. 6A  illustrates an exemplary user plane protocol stacks for relay path between the source end node and the destination end node with multiple relay UEs in accordance with embodiments of the current invention. An exemplary relay path stack  610  includes stack of a source end node  601 , stack of a destination end node  604 , and stacks of two relay nodes  602  and  603 . The source end node  601  and the destination end node  604  are the origination and destination nodes of the relay path. The origination and the destination nodes are also called the end-nodes. The lower layer wireless channel  650  is established through the PHY, MAC, RLC and ADAPT layers of each node on the relay path. A first wireless link  651  is established between lower layer stack of source end node  601  and a first lower layer protocol stack of relay node  602 . A second wireless link  652  is established between the second lower layer protocol stack of relay node  602  and a first lower layer protocol stack of relay node  603 . A second lower layer protocol stack of relay node  603  establishes a third wireless link  653  with lower layer protocol stack of destination end node  604 . In one embodiment, for a UE-to-Network relay, the first wireless link  651  is an RLC wireless link through an Uu interface between relay node  602  and the source end node  601 . In another embodiment, for a UE-to-UE relay, the first wireless link  651  is an RLC wireless link through an PC5 interface between relay node  602  and the source end node  601 . The lower layer link between relay node  602  and  603  is a sidelink channel. The lower layer link between relay node  603  and destination end node  605  is a sidelink. On the user plane, end-to-end protocol connection  655  is established directly between the protocol stacks at the IP layer, the SDAP layer and the PDCP layer of source end node  601  and destination end node  604 . The ACP/ADAPT layer of each node is used for packet routing of the sidelink relay. In one embodiment, each relay node is configured with two ACP layer stacks. Relay node  602  has ADAPT  621  and  622 . Relay node  603  has ADAPT  631  and  632 . Each ACP stack of the one or more relay nodes is connected with an end-node ACP stack. ACP  621  of relay node  602  is connected with ACP  611  of end-node  601 . ACP  632  of relay node  603  is connected with ACP  641  of destination end-node  604 . In one novel aspect, the origination and relay nodes perform SN handling at the ACP layer. The relay nodes also perform bearer mappings at the ACP layer, such as ACP  621 ,  622 ,  631 , and  632 . Each ACP layer has an adaptation layer address (ALA). 
       FIG. 6B  illustrates an exemplary control plane protocol stacks for relay path between the source end node and the destination end node with multiple relay UEs in accordance with embodiments of the current invention. An exemplary relay path stack  620  includes stack of a source end node  606 , stack of a destination end node  609 , and stacks of two relay nodes  607  and  608 . The source end node  606  and the destination end node  609  are the origination and destination nodes of the relay path. The origination and the destination nodes are also called the end-nodes. The lower layer wireless channel  660  is established through the PHY, MAC, RLC and ADAPT layers of each node on the relay path. A first wireless link  656  is established between lower layer stack of source end node  606  and a first lower layer protocol stack of relay node  607 . A second wireless link  657  is established between the second lower layer protocol stack of relay node  607  and a first lower layer protocol stack of relay node  608 . A second lower layer protocol stack of relay node  608  establishes a third wireless link  658  with lower layer protocol stack of destination end node  609 . In one embodiment, for a UE-to-Network relay, the first wireless link  656  is an RLC wireless link through an Uu interface between relay node  607  and the source end node  606 . In another embodiment, for a UE-to-UE relay, the first wireless link  656  is an RLC wireless link through an PC5 interface between relay node  607  and the source end node  606 . The lower layer link between relay node  607  and  608  is a sidelink channel. The lower layer link between relay node  608  and destination end node  609  is a sidelink. On the control plane, end-to-end protocol connection  659  is established directly between the protocol stacks at the NAS layer, the RRC layer and the PDCP layer of source end node  606  and destination end node  609 . The ACP/ADAPT layer of each node is used for packet routing of the sidelink relay. In one embodiment, each relay node is configured with two ACP layer stacks. Relay node  607  has ADAPT  671  and  672 . Relay node  608  has ADAPT  681  and  682 . Each ACP stack of the one or more relay nodes is connected with an end-node ACP stack. ACP  671  of relay node  607  is connected with ACP  661  of end-node  606 . ACP  682  of relay node  608  is connected with ACP  691  of destination end-node  609 . In one novel aspect, the origination and relay nodes perform SN handling at the ACP layer. The relay nodes also perform bearer mappings at the ACP layer, such as ACP  671 ,  672 ,  681 , and  682 . Each ACP layer has an adaptation layer address (ALA). 
     In one novel aspect, the cooperative communication is performed for the sidelink relay. The relay UE performs cooperative communication to route data packets between the source node and the destination node UE. The cooperative communication includes an ACP layer function selecting from packet-based split, packet-based duplication, packet-based split and duplication hybrid, segment-based split, segment-based duplication, segment-based split and duplication hybrid, radio-bearer-based split, radio-bearer-based duplication, and radio-bearer-based split and duplication hybrid. 
       FIG. 7  to  FIG. 11  illustrate exemplary scenarios for the ACP layer functions for the cooperative communication.  FIG. 7  illustrates an exemplary ACP layer packet-based split for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. In one embodiment, the ACP layer packet-based split is the SAP, also dentated as sidelink relay adaptation protocol (SRAP) layer packet-based split. Packet-based split is a specific mode of cooperative communication between the nodes within the relay network. The sequence number is inserted into the ACP header before the packet-based split at ACP layer for the same radio bearer. A plurality of relay paths is configured for relay communication path between the source node  710  and the destination end node UE  720  with relay UE  702 ,  703 ,  704 ,  705 , and  706 . Source node  710  has data packet  730  including #100 to #109. Source node packets  730  are split into packets  731  and  732 . Packets  731  including #100, #101, #103, #106 and #107 are transmitted to relay UE  702  via the communication path between source end node UE  710  and relay UE  702 . Packets  732  including #102, #104, #105, #108 and #109 are transmitted to relay UE  703  via the communication path between source end node  701  and relay UE  703 . Relay UE  702  performs packet-based split upon receiving packets  731 . Packet  731  is split into packets  735  and packets  734 . Packets  735  including #103, #106 and #107 are transmitted to relay UE  704  via the communication path between relay UE  702  and relay UE  704 . Packets  734  includes #100 and #101 are transmitted to relay UE  705  via the communication path between relay UE  702  and relay UE  705 . 
       FIG. 8  illustrates an exemplary ACP layer packet-based duplication for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. In one embodiment, the ACP layer packet-based duplication is the SRAP layer packet-based duplication. Packet based duplication is a specific mode of cooperative communication between the nodes within the relay network. The sequence number (SN) is inserted into the ACP header before the packet-based duplication at ACP layer for the same radio bearer. A plurality of relay paths is configured for relay communication path between the source node  810  and the destination end node UE  820  with relay UE  802 ,  803 ,  804 ,  805 , and  806 . Source node  810  has data packets  830  including #100 to #104. Source node packets  830  are duplicated into packets  831  and  832  to send to different communication paths in a duplication manner. Packets  831  including #100, #101, #102, #103 and #104 are transmitted to both relay UE  802  and relay UE  803  from source end node  810  via different communication paths in a duplication manner. Relay UE  802  upon receiving packets  831  sends duplicated packets  835  and  834  to next hops. Packets  834  and  835  both includes #100, #102, #103 and #104, and are transmitted to both relay UE  804  and relay UE  805  from relay UE  802  via different communication paths in a duplication manner. As an example, packet #101 is lost over the communication path from source node  810  to relay UE  802 . 
       FIG. 9  illustrates an exemplary ACP layer packet-based hybrid operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. In one embodiment, the ACP layer packet-based hybrid operation is SRAP layer packet-based hybrid operation. Packet based hybrid operation is a specific mode of cooperative communication between the nodes within relay network. The ACP layer packet-based hybrid operation includes both packet-based duplication and packet-based split. Some of the packets are duplicated and some of the packets are split in the different communication path depending on the need. The SN is inserted into the ACP header before the packet-based hybrid operation at ACP layer for the same radio bearer. A plurality of relay paths is configured for relay communication path between the source node  910  and the destination end node UE  920  with relay UE  902 ,  903 ,  904 ,  905 , and  906 . Source node  910  has data packets  930  including #100 to #104. Source node  910  performs hybrid packet-based operation for packets  930 . Packets  930  is partially duplicated and split into packets  931  and  932 . Packets  931  including #100, #101, #102, and #103 are transmitted to relay UE  902  via the communication paths from source end node  910  and relay UE  902 . Packets  932 , including #102 #103 and #104 are transmitted to relay UE  902  via relay path between source end node  910  and relay UE  903 . As an example, packets  102  and  103  are duplicated. Relay UE  902  upon receiving packets, performs packet-based hybrid operation, and sends packets  935  and  934 . Packets  935  including #100, #102, and #103, are transmitted to relay UE  904  via the communication paths from relay UE  902  to relay UE  904 . Packets  934 , including #100 and #101, are transmitted to relay UE  905  via the communication paths from relay UE  902  to relay UE  905 . As an example, packet #100 Is duplicated. 
       FIG. 10  illustrates an exemplary ACP layer segment-based hybrid operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. In one embodiment, the ACP layer segment-based hybrid operation is SRAP segment-based hybrid operation. Segment based hybrid operation is a specific mode of cooperative communication between the nodes within the relay network. The ACP layer segment-based hybrid operation includes both segment duplication and segment split. It means some of the segments are duplicated and some of the segments are split in the different communication path. The SN is inserted into the ACP segment header before the segment-based hybrid operation at ACP layer for the same radio bearer. A plurality of relay paths is configured for relay communication path between the source node  1010  and the destination end node UE  1020  with relay UE  1002 ,  1003 ,  1004 ,  1005 , and  1006 . Source node  1010  has data segments 1.1, 1.2, 1.3, 1.4, and 1.5 for data packet #1. Source node packets  1030  performs segment-based hybrid operation and sends packets  1031  and  1032 . Packets  1031  includes segments 1.1, 1.2, 1.3, 1.4 and 1.5 (segmented from ACP packet #1) and are transmitted to relay UE  1002  via the communication paths from source end node  1010  and relay UE  1002 . Packets  1032  includes segments 1.2, 1.3 and 1.5 (segmented from ACP packet #1) and are transmitted to relay UE  1003  via the communication paths from source end node  1010  and relay UE  1003 . In this hop of transmission, only segments 1.2, 1.3 and 1.5 are duplicated. Relay UE  1002  performs segment-based hybrid operation and sends packets  1035  and  1034 , which includes segments 1.1, 1.2, 1.3, and 1.4. Segments 1.1, 1.2, 1.3 and 1.4 are duplicated before they are transmitted to both relay UE  1004  and relay UE  1005  via different communication paths. As an example, segment 1.5 is lost over the communication path from source end node  1010  to relay UE  1002 . In one embodiment, when segmentation applies to an ACP packet, the SI field is inserted into the header of the ACP segment to indicate whether the data packet contains a complete ACP service data unit (SDU) or the first, middle, last segment of an ACP SDU. When segmentation applies to an ACP packet, the SO field is inserted the header of the ACP segment to indicate the position of the RLC SDU segment in bytes within the original RLC SDU. The segmentation-based cooperative communication also includes segment-based data split only and segment-based data duplication only operations similar to those shown for the packet-based operations. 
       FIG. 11  illustrates an exemplary ACP layer radio bearer based split operation for the communication path between one UE node and one peer UE node in accordance with embodiments of the current invention. In one embodiment, the ACP layer radio bearer based split operation is SRAP radio bearer based split operation. Radio bearer-based hybrid operation is a specific mode of communication between the nodes within the relay network. ACP layer radio bearer-based operation includes both radio bearer split and radio bearer duplication. The radio bearer duplication is not shown. A plurality of relay paths is configured for relay communication path between the source node  1110  and the destination end node UE  1120  with relay UE  1102 ,  1103 ,  1104 ,  1105 , and  1106 . Source node  1110  has data packets  1130  including #100 to #104 from radio bearer #1 and data packets  1131  including #105 to #109 from radio bearer #2. The packets of a particular radio bearer can be duplicated in different communication path. In case of packet-based split, the granularity is per radio bearer, which means only the packets belong to different radio bearers can be split into a plural of data flows, with one corresponding to one communication path. Packets  1111 , including #100 to #104 of the first radio bear are transmitted to relay UE  1102  from source end node  1110 . Packets  1112  including #105 to #109 of the second radio bear are transmitted to relay UE  1103  from source end node  1110 . The packets of first radio bearer are split in the second hop of the transmission. Relay UE  1102  splits the packets into packets  1135  and  1134 . Packets  1135  includes #102, #103 and #104 of the first radio bear and are transmitted from relay UE  1102  to relay UE  1104 . Packets  1134  includes #100 and #101 of the first radio bear and are transmitted from relay UE  1102  to relay UE  1105 . Packets of the second radio bearer are transmitted from relay UE  1103  through relay UE  1106  to UE  1120 . 
       FIG. 12  illustrates exemplary diagrams for the detailed operations of the cooperative communication for the SL relay in accordance with embodiments of the current invention. The source node and/or the relay node performs the data split, data duplication or hybrid operation for the relay data. The determination of the type of cooperative functions to perform, at step  1201 , is based on one or more factors including a QoS requirement, a radio signal strength measurement, a successful rate of packet transmission, a preconfigured rule, a status of flow control, packet feedback information, detecting of a topology change, and available radio resources. 
     At step  1202 , the sender of the data packets performs weight value operation as in  1221 . The relay UE obtains a weight value configuration that includes a bitmap for each packet or segment flow to next hops in different relay paths, wherein the cooperative communication is performed based on the weight value. Within the relay communication path when one sender node decides the cooperative communication operation of the ACP packet or segment flow, such as, duplication or split. The sender codes the bitmap for each of the packet or segment flow in the different relay path. The bitmap is equivalent to the coding vector or weight value in network coding based cooperative communication in the art. For example, as shown in  FIG. 11 , there are five packets (i.e., #100, #101, #102, #103 and #104) at relay UE  1102  to be transmitted to the next hop. The weight value of the packets going to relay UE  1104  is W1=[0, 0, 1, 1, 1]; and the weight value of the packets going to relay UE  1105  is W2=[1, 1, 0, 0, 0]. The sender node sends the weigh value of a particular communication path to the receiver node within the relay network to allow the receiver node to adjust its receiving window for the particular data flow, such as packet flow, or segment flow. The receiver node slides the receiving window when receiving the packets or segments expected. In case there is a plural of receiving paths for a particular packet or segment flow, receiver node slides the receiving window when the expected packet or segment has already arrived at the receiving window. The receiver node does not wait for the duplicated packets or segments still flying. When the receiver node slides the receiving window, the receiver node can decide his cooperative communication operation on the packets or segments in the window (e.g., duplication or split) for its inferior hop transmission within the relay path. In one embodiment  1223 , the weight value of the packet or segment flow for a particular relay path is transmitted by the sender of the packet flow via ACP layer control PDU to the receiver node of the packet flow. The ACP layer control PDU is used to enable dynamic transmission of the weight information (i.e., code vector). In one embodiment  1222 , the weight information (i.e., code vector) is statically configured or pre-configured. 
     In one embodiment, the sender of the packet or segment flow relies on the receiver&#39;s acknowledgement and/or non-acknowledgement of the reception of ACP packets or segments to decide the need of retransmission. The receiver&#39;s acknowledgement and/or non-acknowledgement of a particular packet or segment is based on all of the available communication paths. This means if one packet or segment was correctly received by at least one the available communication path, the receiver feedbacks positive acknowledgement of the packet or segment to all of the senders per request. 
     At step  1203 , the relay UE on the receiving side is configured with options of receiving window  1231 , timer-based operation  1232 , and removing redundant duplication operation  1233 . In one embodiment  1231 , the intermediate relay node runs a receiving window for the ACP layer data reception. In one embodiment, the window length is configured and is less than the half of the maximum of ACP layer SN. When all of the ACP packets or segments correctly arrive at the window, these ACP packets or segments is subject to further operation in the intermediate relay node (i.e., duplication or split) for its inferior hop transmission within the relay path. In one embodiment  1232 , the intermediate relay node runs a timer for each packet or segment expected to receive. When the timer expires, the intermediate relay node gives up the packet or segment and performs its inferior hop transmission within the relay path for the packet flow when in-order packet forward is enabled at the intermediate relay node. In one embodiment  1233 , the relay UE determines whether to remove the redundant duplicates. In one embodiment, the relay UE keeps redundant ACP layer packets or segments. The destination node UE removes redundant ACP layer packets or segments before delivering data packets to an upper layer of the destination node UE. In another embodiment, the relay UE removes redundant ACP layer packets or segments. 
     In one embodiment, the cooperative communication including both duplication and split based operation only occurs at the source node, and the intermediate Relay nodes supports transparent data forwarding. In this case, no duplication or split is performed for the received packet or segment flow in intermediate Relay nodes. The data flow is assembled at the destination node. 
     Though ACP layer operation for the cooperative communication of the SL relay is described, the same operation is performed at the RLC layer in other embodiments. the cooperative communication including both duplication and split based operation is performed at RLC layer of the source node or intermediate Relay Node. In this case, the data flow is RLC layer packets or RLC layer segments flow. Depending on the size of the MAC layer transmission block (i.e., TB) allocated for the inferior paths, the RLC packets can be segmented and put into different MAC entities of the inferior paths, with one segment mapped to a particular inferior path. The segmented RLC layer packets can be assembled at the intermediate Relay Node or at the destination node. 
       FIG. 13  illustrates an exemplary flow chart for the cooperative communication for the SL relay in accordance with embodiments of the current invention. At step  1301 , the relay UE establishes one or more sidelink in the wireless network. At step  1302 , the relay UE configures an adaptation control plane (ACP) layer on top of a radio link control (RLC) layer, wherein the ACP layer performs functions comprising radio bearer mapping, packet routing, and flow control. At step  1303 , the relay UE configures one or more SL relay paths, wherein the one or more SL relay paths is part of a plurality of end-to-end relay paths between a source node and a destination node UE with the relay UE being a relay node. At step  1304 , the relay UE performs cooperative communication to route data packets between the source node and the destination node UE, wherein cooperative communication includes an ACP layer function selecting from packet-based split, packet-based duplication, packet-based split and duplication hybrid, segment-based split, segment-based duplication, segment-based split and duplication hybrid, radio-bearer-based split, radio-bearer-based duplication, and radio-bearer-based split and duplication hybrid. 
     Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.