Patent Description:
Aspects of the present disclosure generally relate to wireless communications, and more particularly to a distributed sidelink (SL) architecture and protocol stack.

Wireless communications systems are widely deployed to provide various telecommunications services such as telephony, video, data, messaging, and broadcasts. Typical wireless communications systems may employ multiple-access technologies capable of supporting communications with multiple users by sharing available system resources.

These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunications standard is fifth generation (<NUM>) new radio (NR). Some aspects of <NUM> NR may be based on the fourth generation (<NUM>) long term evolution (LTE) standard. These improvements may also be applicable to other multi-access technologies and the telecommunications standards that employ these technologies.

Wireless communications systems may include or provide support for various types of communications systems, such as vehicle related communications systems (e.g., vehicle-to-everything (V2X) communications systems). Vehicle related communications systems may be used by vehicles to increase safety and to help prevent collisions of vehicles. Information about inclement weather, nearby accidents, road conditions, and/or other information may be conveyed to a driver via the vehicle related communications system. In some cases, vehicles may communicate directly with each other or to the infrastructure using device-to-device (D2D) communications over a D2D wireless link.

As the demands for vehicle related communications increase, different V2X communications systems compete for the same wireless communications resources. Accordingly, there is a need to improve the sharing of wireless communications resources.

In one aspect of the present disclosure, a sidelink node includes a distributed processing architecture for wireless communications, as defined in claim <NUM>.

Additional features and advantages will be described. Characteristics of the concepts disclosed, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures.

Various aspects of the disclosure are described more fully below with reference to the accompanying drawings. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth. It should be understood that any aspect of the disclosure disclosed may be embodied by one or more elements of a claim.

Several aspects of telecommunications systems will now be presented with reference to various apparatuses and techniques.

It should be noted that while aspects may be described using terminology commonly associated with <NUM> and later wireless technologies, aspects of the present disclosure can be applied in other generation-based communications systems, such as and including <NUM> and/or <NUM> technologies.

In traditional cellular communications networks, wireless devices may communicate with each other via one or more network entities such as a base station or scheduling entity. Some networks may support device-to-device (D2D) communications that enable discovery of, and communications with nearby devices using a direct link between devices (e.g., without passing through a base station, relay, or another node). D2D communications can enable mesh networks and device-to-network relay functionality. Some examples of D2D technology include PC5 or direct communication mode, which is an air interface for device-to-device discovery and communications. D2D communications may also be referred to as sidelink communications.

Vehicle-to-everything or V2X describes communications between a vehicle and any other type of device. Information from sensors and other sources can be communicated between a vehicle and another device, such as a road side unit (RSU). New radio (NR) V2X is a type of <NUM> communications where the vehicles exchange information with RSUs (road side units) using NR V2X communications. In some cases, the RSUs may be connected to the backend server/network (such as a <NUM> network) and provide the information reported from vehicles to the server and vice versa.

RSUs are special nodes deployed to assist the vehicles by providing additional information. RSUs may be deployed at various locations to assist the vehicles. Each RSU may serve multiple V2X UEs. Under such deployment, the RSU appears like a base station or an access point providing connectivity for the vehicles to the network.

According to aspects of the present disclosure, when there are many RSUs deployed, a distributed processing architecture may be beneficial for the RSUs. That is, logical nodes may be defined for the RSU functionalities. Some of the logical nodes may be deployed in a cloud environment.

Cloud architecture/distributed processing for sidelink communications is also contemplated for non-V2X use cases. In this case, special nodes called sidelink assistance nodes (SLANs), similar to the RSUs, may assist the device-to-device communications. For example, gaming/interactive services may use SLANs to send and receive information from the backend server. According to the present disclosure, a cloud sidelink (SL) architecture refers to special nodes deployed with distributed processing for any sidelink use case.

The wireless communications system (also referred to as a wireless wide area network (WWAN)) includes base stations <NUM>, UEs <NUM>, an evolved packet core (EPC) <NUM>, and another core network <NUM> (e.g., a <NUM> core (5GC)). The base stations <NUM> may include macrocells (high power cellular base station) and/or small cells <NUM>' (low power cellular base station). The small cells <NUM>' include femtocells, picocells, and microcells.

The base stations <NUM> configured for <NUM> LTE (collectively referred to as evolved universal mobile telecommunications system (UMTS) terrestrial radio access network (E-UTRAN)) may interface with the EPC <NUM> through backhaul links <NUM> (e.g., S1 interface). The base stations <NUM> configured for <NUM> NR (collectively referred to as next generation RAN (NG-RAN)) may interface with core network <NUM> through backhaul links <NUM>. The base stations <NUM> may communicate directly or indirectly (e.g., through the EPC <NUM> or core network <NUM>) with each other over backhaul links <NUM> (e.g., X2 interface).

Each of the base stations <NUM> may provide communications coverage for a respective geographic coverage area <NUM>. A heterogeneous network may also include home evolved Node Bs (eNBs) (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG). The communications links <NUM> between the base stations <NUM> and the UEs <NUM> may include uplink (UL) (also referred to as reverse link) transmissions from a UE <NUM> to a base station <NUM> and/or downlink (DL) (also referred to as forward link) transmissions from a base station <NUM> to a UE <NUM>. The communications links <NUM> may use multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communications links may be through one or more carriers. The base stations <NUM> / UEs <NUM> may use spectrum up to Y MHz (e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, etc., MHz) bandwidth per carrier allocated in a carrier aggregation of up to a total of Yx MHz (x component carriers) used for transmission in each direction.

Certain UEs <NUM> may communicate with each other using device-to-device (D2D) communications link <NUM>. The D2D communications link <NUM> may use the DL/UL WWAN spectrum. The D2D communications link <NUM> may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). D2D communications may be through a variety of wireless D2D communications systems, such as FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE <NUM> standard, LTE, or NR.

The wireless communications system may further include a Wi-Fi access point (AP) <NUM> in communication with Wi-Fi stations (STAs) <NUM> via communications links <NUM> in a <NUM> unlicensed frequency spectrum.

The EPC <NUM> may include a mobility management entity (MME) <NUM>, other MMEs <NUM>, a serving gateway <NUM>, a multimedia broadcast multicast service (MBMS) gateway <NUM>, a broadcast multicast service center (BM-SC) <NUM>, and a packet data network (PDN) gateway <NUM>. The MME <NUM> may be in communication with a home subscriber server (HSS) <NUM>. All user Internet protocol (IP) packets are transferred through the serving gateway <NUM>, which itself is connected to the PDN gateway <NUM>. The PDN gateway <NUM> provides UE IP address allocation as well as other functions. The PDN gateway <NUM> and the BM-SC <NUM> are connected to the IP services <NUM>. The IP services <NUM> may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and/or other IP services. The BM-SC <NUM> may serve as an entry point for content provider MBMS transmission, may be used to authorize and initiate MBMS bearer services within a public land mobile network (PLMN), and may be used to schedule MBMS transmissions. The MBMS gateway <NUM> may be used to distribute MBMS traffic to the base stations <NUM> belonging to a multicast broadcast single frequency network (MBSFN) area broadcasting a particular service, and may be responsible for session management (start/stop) and for collecting eMBMS related charging information.

The core network <NUM> may include an access and mobility management function (AMF) <NUM>, other AMFs <NUM>, a session management function (SMF) <NUM>, and a user plane function (UPF) <NUM>. The AMF <NUM> may be in communication with a unified data management (UDM) <NUM>. Generally, the AMF <NUM> provides quality of service (QoS) flow and session management. The UPF <NUM> is connected to the IP services <NUM>. The IP services <NUM> may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and/or other IP services.

The base station <NUM> may also be referred to as a gNB, Node B, evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit reception point (TRP), or some other suitable terminology. Some of the UEs <NUM> may be referred to as IoT devices (e.g., a parking meter, gas pump, toaster, vehicles, heart monitor, etc.).

Although the following description may be focused on <NUM> NR, the herein may be applicable to other similar areas, such as LTE, LTE-A, CDMA, GSM, and other wireless technologies.

The <NUM> NR frame structure may be frequency division duplex (FDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for either DL or UL, or may be time division duplex (TDD) in which for a particular set of subcarriers (carrier system bandwidth), subframes within the set of subcarriers are dedicated for both DL and UL. In the examples provided by <FIG>, the <NUM> NR frame structure is assumed to be TDD, with subframe <NUM> being configured with slot format <NUM> (with mostly DL), where D is DL, U is UL, and X is flexible for use between DL/UL, and subframe <NUM> being configured with slot format <NUM> (with mostly UL).

Other wireless communications technologies may have a different frame structure and/or different channels. The symbols on UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-S-OFDM) symbols (also referred to as single carrier frequency-division multiple access (SC-FDMA) symbols) (for power limited scenarios; limited to a single stream transmission). Accordingly, for slot configuration <NUM> and numerology µ, there are <NUM> symbols/slot and 2µ slots/subframe. The subcarrier spacing may be equal to <NUM>^µ*<NUM>, where µ is the numerology <NUM> to <NUM>. The subcarrier spacing is <NUM> and symbol duration is approximately <NUM>.

A resource grid may represent the frame structure.

Each stream may then be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream.

The RX processor <NUM> then converts the OFDM symbol stream from the time-domain to the frequency domain using a fast Fourier transform (FFT).

<FIG> is a diagram of a device-to-device (D2D) communications system <NUM>, including vehicle-to-everything (V2X) communications, in accordance with various aspects of the present disclosure. For example, the D2D communications system <NUM> may include V2X communications, (e.g., a first UE <NUM> communicating with a second UE <NUM>). In some aspects, the first UE <NUM> and/or the second UE <NUM> may be configured to communicate in a licensed radio frequency spectrum and/or a shared radio frequency spectrum. The shared radio frequency spectrum may be unlicensed, and therefore multiple different technologies may use the shared radio frequency spectrum for communications, including new radio (NR), LTE, LTE-Advanced, licensed assisted access (LAA), dedicated short range communications (DSRC), MuLTEFire, <NUM>, and the like. The foregoing list of technologies is to be regarded as illustrative, and is not meant to be exhaustive.

The D2D communications system <NUM> may use NR radio access technology. Of course, other radio access technologies, such as LTE radio access technology, may be used. In D2D communications (e.g., V2X communications or vehicle-to-vehicle (V2V) communications), the UEs <NUM>, <NUM> may be on networks of different mobile network operators (MNOs). Each of the networks may operate in its own radio frequency spectrum. For example, the air interface to a first UE <NUM> (e.g., Uu interface) may be on one or more frequency bands different from the air interface of the second UE <NUM>. The first UE <NUM> and the second UE <NUM> may communicate via a sidelink component carrier, for example, via the PC5 interface. In some examples, the MNOs may schedule sidelink communications between or among the UEs <NUM>, <NUM> in licensed radio frequency spectrum and/or a shared radio frequency spectrum (e.g., <NUM> radio spectrum bands).

The shared radio frequency spectrum may be unlicensed, and therefore different technologies may use the shared radio frequency spectrum for communications. In some aspects, a D2D communications (e.g., sidelink communications) between or among UEs <NUM>, <NUM> is not scheduled by MNOs. The D2D communications system <NUM> may further include a third UE <NUM>.

The third UE <NUM> may operate on a first network <NUM> (e.g., of the first MNO) or another network, for example. The third UE <NUM> may be in D2D communications with the first UE <NUM> and/or second UE <NUM>. A first road side unit (RSU) <NUM> may communicate with the third UE <NUM> via sidelink carriers <NUM>, <NUM>. The first network <NUM> operates in a first frequency spectrum and includes the first RSU <NUM> (e.g., communicating at least with the first UE <NUM>, for example, as described in <FIG>. ) The first RSU <NUM> may communicate with the first UE <NUM> via sidelink carriers <NUM>, <NUM>.

In some aspects, the second UE <NUM> may be on a different network from the first UE <NUM>. In some aspects, the second UE <NUM> may be on a second network <NUM> (e.g., of the second MNO). The second network <NUM> may operate in a second frequency spectrum (e.g., a second frequency spectrum different from the first frequency spectrum) and may include a second RSU <NUM> communicating with the second UE <NUM>, for example, as described in <FIG>. The second RSU <NUM> may communicate with the second UE <NUM> via sidelink carriers <NUM>, <NUM>. The RSUs <NUM>, <NUM> may be incorporated with traffic infrastructure (e.g., a traffic light, light pole, etc.) For example, the RSUs <NUM>, <NUM> can be a traffic signal positioned at a side of a road. Additionally or alternatively, the RSUs <NUM>, <NUM> may be stand-alone units.

The D2D communications (e.g., V2X communications and/or V2V communications) may also be carried out via one or more sidelink carriers <NUM>, <NUM>. The sidelink carriers <NUM>, <NUM> may include one or more channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH), for example. In some examples, the sidelink carriers <NUM>, <NUM> may operate using the PC5 interface. The first UE <NUM> may transmit to one or more (e.g., multiple) devices, including to the second UE <NUM> and the RSU <NUM> via a sidelink carrier (e.g., <NUM>, <NUM>). The second UE <NUM> may transmit to one or more (e.g., multiple) devices, including to the first UE <NUM> or the RSU <NUM> via a sidelink carrier (e.g., <NUM>, <NUM>). The RSUs <NUM>, <NUM> may forward data received from the transmitter UE <NUM>, <NUM> to a cellular network (e.g., a gNB of a <NUM> network) (not shown) via an UL transmission. The <NUM> network (e.g., gNB) may transmit the data received from the RSUs <NUM>, <NUM> to other UEs <NUM>, <NUM> via a DL transmission.

In some aspects, the UL sidelink carrier <NUM> and the first sidelink carrier <NUM> may be aggregated to increase bandwidth. In some aspects, the first sidelink carrier <NUM> and/or the second sidelink carrier <NUM> may share the first frequency spectrum (with the first network <NUM>) and/or share the second frequency spectrum (with the second network <NUM>). In some aspects, the sidelink carriers <NUM>, <NUM> may operate in an unlicensed/shared radio frequency spectrum.

In some aspects, sidelink communications on a sidelink carrier may occur between the first UE <NUM> and the second UE <NUM>. In an aspect, the first UE <NUM> may perform sidelink communications with one or more (e.g., multiple) devices, including the second UE <NUM> via the first sidelink carrier <NUM>. For example, the first UE <NUM> may transmit a broadcast transmission via the first sidelink carrier <NUM> to the multiple devices (e.g., the second and third UEs <NUM>, <NUM>). The second UE <NUM> (e.g., among other UEs) may receive such broadcast transmission. Additionally or alternatively, the first UE <NUM> may transmit a multicast transmission via the first sidelink carrier <NUM> to the multiple devices (e.g., the second and third UEs <NUM>, <NUM>). The second UE <NUM> and/or the third UE <NUM> (e.g., among other UEs) may receive such multicast transmission. The multicast transmissions may be connectionless or connection-oriented. A multicast transmission may also be referred to as a groupcast transmission.

Furthermore, the first UE <NUM> may transmit a unicast transmission via the first sidelink carrier <NUM> to a device, such as the second UE <NUM>. The second UE <NUM> (e.g., among other UEs) may receive such unicast transmission. Additionally or alternatively, the second UE <NUM> may perform sidelink communications with one or more (e.g., multiple) devices, including the first UE <NUM> via the second sidelink carrier <NUM>. For example, the second UE <NUM> may transmit a broadcast transmission via the second sidelink carrier <NUM> to the multiple devices. The first UE <NUM> (e.g., among other UEs) may receive such broadcast transmission.

In another example, the second UE <NUM> may transmit a multicast transmission via the second sidelink carrier <NUM> to the multiple devices (e.g., the first and third UEs <NUM>, <NUM>). The first UE <NUM> and/or the third UE <NUM> (e.g., among other UEs) may receive such multicast transmission. Further, the second UE <NUM> may transmit a unicast transmission via the second sidelink carrier <NUM> to a device, such as the first UE <NUM>. The first UE <NUM> (e.g., among other UEs) may receive such unicast transmission. The third UE <NUM> may communicate in a similar manner.

In some aspects, for example, such sidelink communications on a sidelink carrier may occur without having MNOs allocating resources (e.g., one or more portions of a resource block (RB), slot, frequency band, and/or channel associated with a sidelink carrier <NUM>, <NUM>) for such communications and/or without scheduling such communications. Sidelink communications may include traffic communications (e.g., data communications, control communications, paging communications and/or system information communications). Further, sidelink communications may include sidelink feedback communications associated with traffic communications (e.g., a transmission of feedback information for previously-received traffic communications). Sidelink communications may employ at least one sidelink communications structure having at least one feedback symbol. The feedback symbol of the sidelink communications structure may allot for any sidelink feedback information that may be communicated in the device-to-device (D2D) communications system <NUM> between devices (e.g., a first RSU <NUM>, a second RSU <NUM>, a first UE <NUM>, a second UE <NUM>, and/or a third UE <NUM>).

In some aspects, the RSU <NUM>, <NUM>, or another device, may include means for communicating, means for establishing, means for performing, means for sidelink transmitting and receiving, means for selecting, and means for managing. Such means may include one or more components of the UE <NUM> or base station <NUM> described in connection with <FIG>.

In certain aspects, a device, such as the RSUs <NUM>, <NUM>, may have a distributed processing architecture. The sidelink architecture may be enhanced to support a cloud-like environment. <FIG> are diagrams illustrating use cases for distributed sidelink processing, in accordance with various aspects of the present disclosure. For example, as seen in <FIG>, an enterprise or factory may deploy sidelink assistance nodes (SLANs) supporting PC5 (licensed or unlicensed spectrum for PC5). Each SLAN may interface between a data nework <NUM> and a UE <NUM>, <NUM> or a factory/enterprise component <NUM>, <NUM>, <NUM>. The interface between SLANs may be a PC5 link, as may be the interface between factory components <NUM>, <NUM>, <NUM> and UEs <NUM>, <NUM>.

<FIG> is a diagram illustrating an in-vehicle networking use case, in accordance with various aspects of the present disclosure. With in-vehicle networking (e.g., V2X), a distributed PC5 implementation is deployed in the vehicle for logical distribution of the processing within the vehicle. As seen in <FIG>, a central unit (CU), distributed units (DUs), and radio units (RUs) support PC5 with other information sources (e.g., sensors, electronic units, etc.) to provide a coordinated multipoint (CoMP) like coverage in the car.

<FIG> is a block diagram illustrating an example of a distributed architecture, in accordance with various aspects of the present disclosure. An RSU/SLAN <NUM> is shown communicating with a data network <NUM>. The RSU/SLAN <NUM> functionalities may be split into logical nodes. For example, a central unit (CU) <NUM> is a logical node that includes all RSU/SLAN functions except the functions allocated exclusively to the distributed units (DUs) <NUM>. The central unit <NUM> controls the operation of the DUs <NUM>.

Each distributed unit (DU) <NUM> is a logical node that includes, depending on a functional split option (discussed below), a subset of the RSU/SLAN functions. Each DU <NUM> connects to only one central unit <NUM>. For the control plane, the SLF1-C (sidelink F1-control) interface is supported to communicate between the DUs <NUM> and the central unit <NUM>. For the user plane, the SLF1-U (sidelink F1-user) interface may be supported to communicate between the DUs <NUM> and the central unit <NUM>.

A radio unit (RU) <NUM> includes the radio transceiver unit for sidelink transmission and reception. Multiple RUs <NUM> may be controlled by one distributed unit <NUM>. Each RU <NUM> is controlled by only one distributed unit <NUM>. A sidelink fronthaul interface (SLFI) may be used to communicate between the distributed units <NUM> and the RUs <NUM>. The RUs <NUM> may be deployed closer to the sidelink UE. The distributed unit <NUM> and central unit <NUM> may be deployed in the cloud.

Each RSU/SLAN <NUM> communicates with other RSU/SLANs <NUM> for mobility handling of remote UEs. Mobility handling includes the case where a UE moves from coverage of one RSU/SLAN <NUM> to another RSU/SLAN <NUM>. There are at least two options for the inter-node communications. Option one employs enhancements to PC5 (e.g., PC5-S or PC5-RRC) to support remote UE mobility handling and data forwarding during mobility. Option two includes a new sidelink-to-everything (SLXn) interface to support inter-RSU communications. SLXn-AP (application protocol), SLXn-UP (user plane) procedures may be defined to support the mobility handling of remote UEs. In option two, the underlying physical transport may remain as PC5 with a new protocol layer defined over PC5, in one exemplary configuration.

<FIG> is a block diagram illustrating a control plane/user plane split, in accordance with various aspects of the present disclosure. An RSU/SLAN <NUM> is shown communicating with a data network <NUM>. The RSU/SLAN architecture <NUM> in the central unit may be logically split into a control plane and multiple user plane handling entities. A central unit control plane (CU-CP) entity <NUM> may be connected to distributed units (DUs) <NUM> through the SLF1-C (sidelink F <NUM>-control) interface, for example. One distributed unit <NUM> is connected to only one CU-CP <NUM>. Each central unit user plane (CU-UP) <NUM> may support user plane functionality for only certain types of services and bearers. The CU-CP <NUM> selects the appropriate CU-UP(s) <NUM> for the requested services for a UE.

The central unit user plane (CU-UP) <NUM> is for data forwarding, data routing, encryption, security handling, and other user plane functions. The CU-UP <NUM> communicates with the CU-CP <NUM> through the SLE1 interface, for example. The communications define the context for the user, including any control signaling exchange over the SLE1 interface to set up the user plane context for user plane functionality management (e.g., bearer management). The CU-UP <NUM> is connected to the distributed units <NUM> through the SLF1-U (sidelink F1-user) interface, for example. Each CU-UP <NUM> is connected to only one CU-CP <NUM>.

Each distributed unit <NUM> may be connected to multiple CU-UPs <NUM> under the control of the same CU-CP <NUM>. One CU-UP <NUM> may be connected to multiple distributed units <NUM> under control of the same CU-CP <NUM>. The CU-CP <NUM> may transmit to one distributed unit <NUM> or multiple distributed units <NUM> depending on where the context is managed by the CU-CP <NUM>. In other words, connectivity between a CU-UP <NUM> and a distributed unit <NUM> is established by the CU-CP <NUM> using bearer context management functions. Each distributed unit <NUM> communicates with at least one radio unit <NUM> via the SLFI (sidelink fronthaul interface), for example.

<FIG> is a block diagram illustrating a protocol stack split, in accordance with various aspects of the present disclosure. Referring to <FIG>, an exemplary PC5 protocol stack split will be discussed. The PC5 stack and functionalities of an RSU/SLAN <NUM> may be distributed into logical nodes including a central unit (e.g., CU-CP <NUM> and CU-UP <NUM>), distributed unit <NUM>, and radio unit <NUM>. According to this aspect of the present disclosure, the radio unit <NUM> handles the PC5 lower physical layer functions. The radio unit <NUM> communicates with the distributed unit <NUM> via the SLF1 interface, for example. The distributed unit <NUM> manages the radio link control (PC5-RLC) channels, medium access control (PC5-MAC) layer, and upper physical layer functions for the PC5 link.

The CU-CP <NUM> is responsible for control plane handling of the PC5 link between the RSU/SLAN <NUM> and sidelink UEs. The CU-CP <NUM> handles PC5-S signaling for connection setup (PC5-S), radio resource control (PC5-RRC) for access stratum configuration and capability exchange, and packet data convergence protocol (PC5-PDCP) functions to support the control plane traffic of the sidelink UE. The CU-UP <NUM> manages the user plane connections between the RSU/SLAN <NUM> and sidelink UEs. The CU-UP <NUM> handles service data adaptation protocol (PC5-SDAP) and the packet data convergence protocol (PC5-PDCP) functions to support the user plane traffic of the sidelink UE.

<FIG> is a block diagram illustrating exemplary functional splits between a central unit and a distributed unit, in accordance with various aspects of the present disclosure. Although a particular protocol stack split has been described, the RSU/SLAN may be deployed with other protocol stack split options between the distributed unit and central unit, as seen for example in <FIG> and described in 3GPP TR <NUM>, section <NUM> "RAN logical architecture for NR,".

<FIG> is a block diagram illustrating a control plane protocol stack, in accordance with various aspects of the present disclosure. Referring to <FIG>, communications between a sidelink UE (SL UE) <NUM> and an RSU/SLAN control plane <NUM> having a distributed processing architecture is now discussed. The sidelink UE's PC5-S, PC5-RRC, and PC5-PDCP layers communicate with the corresponding layers in the central unit of the RSU/SLAN <NUM>. Control information within the sidelink UE <NUM> also passes from the PC5-RLC (radio link control) layer to the PC5-MAC (media access control) layer to the PC5-PHY (physical) layer. From there, the control information passes to the radio unit PC5-lower PHY layer. The radio unit communicates the information to the PC5-upper PHY layer in the distributed unit, which then processes the information up through the PC5-MAC and PC5-RLC layers to the SLF1 application protocol (SLF1-AP), for example. The SLF1 application protocol, which performs UE context management, generates messages for transport to the central unit. These messages may be transported via SCTP (stream control transfer protocol), IP, L2 (layer <NUM>), and L1 (layer <NUM>) through a wired network, for example. These SCTP messages are not managed by PC5.

<FIG> is a block diagram illustrating a user plane protocol stack, in accordance with various aspects of the present disclosure. <FIG> shows user plane communications between a sidelink UE (SL UE) <NUM> and an RSU/SLAN control plane <NUM> with the distributed processing architecture. After the control plane signaling is completed, the user plane signaling may route the data. For example, the sidelink UE <NUM> processes the user application data down through the PC5 stack to the PC5-PHY layer. The data is then sent to the radio unit PC5-lower PHY layer, which passes the data to the distributed unit PC5-upper PHY layer. The distributed unit processes the data up to the PC5-RLC layer, which communicates with the GTP-U (general packet radio service (GPRS) tunneling protocol-user plane) for tunneling the user plane packets to the central unit.

<FIG> is a flow diagram illustrating an example method of wireless communications, performed by a sidelink node, in accordance with various aspects of the present invention. A process <NUM> is an example of communications with distributed sidelink (SL) architecture and protocol stack.

As shown in <FIG>, in some aspects, the process <NUM> may include communicating control plane messages from a central unit control plane entity to another sidelink node or a sidelink user equipment (SL UE) via at least one distributed unit and at least on radio unit (block <NUM>). For example, the UE (e.g., using the antenna <NUM>, RX/TX <NUM>, TX processor <NUM>, RX processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) or the base station (e.g., using the antenna <NUM>, RX/TX <NUM>, TX processor <NUM>, RX processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may communicate control plane messages.

As shown in <FIG>, in some aspects, the process <NUM> may include communicating user plane messages from a central unit user plane entity to the other sidelink node or the SL UE via the at least one distributed unit and the at least one radio unit (block <NUM>). For example, the UE (e.g., using the antenna <NUM>, RX/TX <NUM>, TX processor <NUM>, RX processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) or the base station (e.g., using the antenna <NUM>, RX/TX <NUM>, TX processor <NUM>, RX processor <NUM>, controller/processor <NUM>, memory <NUM> and or the like) may communicate user plane messages.

Claim 1:
A sidelink node having a distributed processing architecture for wireless communications, the sidelink node comprising:
a central unit (<NUM>) configured to perform sidelink node functions;
a plurality of distributed units (<NUM>) comprising a first distributed unit and a second distributed unit, each distributed unit coupled to the central unit and controlled by the central unit, each distributed unit configured to perform a subset of the sidelink node functions; and
a plurality of radio units (<NUM>) comprising a first set of radio units coupled to and controlled by the first distribution unit and a second set of radio units coupled to and controlled by the second distribution unit, each radio unit configured for sidelink transmission and reception;
in which the sidelink node comprises a road side unit, RSU, (<NUM>) and/or a sidelink assistance node, SLAN (<NUM>) that interfaces to a data network.