Methods for providing a radio access network for wireless communications

Abstract

In accordance with some implementations, a method is provided. The method includes receiving, by a first network device of an access network, a first message from a second network device of the access network. The first message can indicate a configuration of a packet data convergence protocol (PDCP) entity in the first network device. The method further includes transmitting, by the first network device, a second message to a terminal device. The second message can indicate a configuration of a data radio bearer (DRB) corresponding to the PDCP entity.

Description

METHODS FOR PROVIDING A RADIO ACCESS NETWORK FOR WIRELESS COMMUNICATIONSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This patent application claims priority to U.S. Provisional Application No. 63 / 758,878, filed on February 14, 2025, and entitled “Methods for Providing a Radio Access Network for Wireless Communications,” application of which is hereby incorporated by reference herein as if reproduced in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to wireless communications, and, in particular embodiments, to methods and apparatus for providing a radio access network for wireless communications.BACKGROUND

[0003] In a wireless communications system (e.g., a next general cellular system), a Node B (gNB) can provide user plane (UP) and control plane (CP) protocol terminations towards a user equipment (UE). Some gNBs can be interconnected with each other by means of the Xn interface. The gNBs can also be connected by means of the next generation (NG) interfaces to the fifth generation (5G) core network, more specifically to the access and mobility management function (AMF) by means of the NG-C interface (also referred to as the N2 interface) and to the user plane function (UPF) by means of the NG-U interface (also referred to as the N3 interface).SUMMARY

[0004] Technical advantages are generally achieved, by implementations of this disclosure which describe methods, apparatus, and system.

[0005] According to a first aspect, a method is provided. The method includes: receiving, by a first network device of an access network, a first message from a second network device of the access network, where the first message indicates a configuration of a packet data convergence protocol (PDCP) entity in the first network device; transmitting, by the first network device, a second message to a terminal device, where the second message indicates a configuration of a data radio bearer (DRB) corresponding to the PDCP entity; and communicating, by the first network device, data with the terminal device via the DRB.

[0006] With reference to the first aspect, in some implementations, communicating, by the first network device, data with the terminal device via the DRB comprises:FW 6000747PCT02 -1-communicating, by the first network device, lower layer control information via the DRB. The lower layer control information comprises one or more of: a downlink control information (DCI), a media access control (MAC) control element (CE), or a radio link control (RLC) control protocol data unit (PDU).

[0007] With reference to the first aspect, in some implementations, the one or more of the DCI, the MAC CE, or the RLC control PDU are designated to one or more corresponding lower layer protocol entities of the terminal device, respectively. The first message includes information indicating quality of service (QoS) flow identifier (ID) (QFI) values uniquely assigned to the one or more corresponding lower layer protocol entities, respectively. The method further comprises: adding, by the first network device, a PDU header to a first lower layer control message to produce a PDU, a QFI value included in the PDU header being equal to a QFI value assigned to a lower layer protocol entity of the one or more corresponding lower layer protocol entities that had generated the first lower layer control message; applying, by the first network device, integrity protection on the PDU to produce a protected PDU; and submitting, by the first network device, the protected PDU to lower layers for transmission of the first lower layer control message over the DRB to the terminal device.

[0008] With reference to the first aspect, in some implementations, the method further comprises: receiving, by the first network device, a second PDU carrying a second lower layer control message from the terminal device through the DRB; and selecting, by the first network device, a corresponding lower layer protocol entity of the first network device to further process the second lower layer control message based on the information in the first message indicating the QFI values uniquely assigned to the one or more corresponding lower layer protocol entities and based on the QFI value included in a second PDU header of the second PDU.

[0009] With reference to the first aspect, in some implementations, communicating, by the first network device, lower layer control information via the DRB comprises: performing at least one of ciphering or integrity protection, for the lower layer control information transmitted via the DRB.

[0010] With reference to the first aspect, in some implementations, the first network device comprises a distributed unit (DU) of a base station of the access network and a first centralized unit (CU) of the base station, and the second network device comprises a second CU of the base station.

[0011] With reference to the first aspect, in some implementations, the first message further indicates a configuration of a service data adaptation protocol (SDAP) entity inFW 6000747PCT02 -2-the first network device, and the second message further indicates at least one quality of service (QoS) flow mapped to the DRB.

[0012] With reference to the first aspect, in some implementations, the second message includes a valid protocol data unit (PDU) session identifier (ID) associated with the DRB, and the DRB is configured to carry user-plane data.

[0013] With reference to the first aspect, in some implementations, the second message excludes a valid PDU session ID associated with the DRB, and the DRB is configured to exclude user-plane data.

[0014] With reference to the first aspect, in some implementations, the second message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

[0015] With reference to the first aspect, in some implementations, the first network device comprises a first radio resource control (RRC) entity, and the first RRC entity is configured to process the lower layer control information transmitted via the DRB.

[0016] With reference to the first aspect, in some implementations, the second network device comprises a second RRC entity, and the second RRC entity is configured to perform one or more of: RRC connection control, an access stratum (AS) security function, or a non-access stratum (NAS) transmission function.

[0017] With reference to the first aspect, in some implementations, the first network device comprises a user plane function (UPF), and the UPF in the first network device is configured to forward user plane data carried by the DRB to a corresponding destination.

[0018] With reference to the first aspect, in some implementations, the method further includes transmitting, by the first network device, a third message to the second network device. The third message indicates a first CU of a base station of the access network, and the second network device comprises a second CU of the base station.

[0019] With reference to the first aspect, in some implementations, the method further includes: transmitting, by the first network device, a fourth message to the second network device, where the fourth message indicates support for a first CU of a base station of the access network, and the second network device comprises a second CU of the base station; and receiving, by the first network device, a fifth message from the second network device, where the fifth message indicates a configuration of the first CU in the first network device.FW 6000747PCT02 -3-

[0020] According to a second aspect, a method is provided. The method includes: receiving, by a terminal device, a message from a network device of an access network, where the network device comprises a DU of a base station of the access network and a first CU of the base station, the message indicates a configuration of a DRB corresponding to a PDCP entity in the first CU of the network device; and communicating, by the terminal device, data with the network device via the DRB.

[0021] With reference to the second aspect, in some implementations, communicating, by the terminal device, data with the network device via the DRB comprises: communicating, by the terminal device, lower layer control information via the DRB. The lower layer control information comprises one or more of: a DCI, a MAC- CE, or an RLC control PDU.

[0022] With reference to the second aspect, in some implementations, the message includes a valid PDU session ID associated with the DRB, and the DRB is configured to carry user-plane data.

[0023] With reference to the second aspect, in some implementations, the message excludes a valid PDU session ID associated with the DRB, and the DRB is configured to exclude user-plane data.

[0024] With reference to the second aspect, in some implementations, the message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

[0025] According to a third aspect, a method is provided. The method includes: transmitting, by a first network device of an access network, a first message to a second network device of the access network, where the first message indicates a configuration of a first CU of a base station of the access network in the second network device, and the first network device comprises a second CU of the base station; and transmitting, by the first network device, a second message to the second network device, where the second message indicates a configuration of a PDCP entity in the first CU in the second network device.

[0026] With reference to the third aspect, in some implementations, the second network device comprises a first RRC entity, the first network device comprises a second RRC entity, and the second RRC entity is configured to perform one or more of: RRC connection control, an AS security function, or a NAS transmission function.FW 6000747PCT02 -4-

[0027] According to a fourth aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the first aspect or one or more implementations of the first aspect.

[0028] According to a fifth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the first aspect or one or more implementations of the first aspect.

[0029] According to a sixth aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the second aspect or one or more implementations of the second aspect.

[0030] According to a seventh aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the second aspect or one or more implementations of the second aspect.

[0031] According to an eighth aspect, an apparatus is provided. The apparatus includes: at least one processor; and at least one memory coupled to the at least one processor, where the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to the third aspect or one or more implementations of the third aspect.

[0032] According to a ninth aspect, a non-transitory computer readable storage medium is provided. The non-transitory computer readable storage medium stores programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to the third aspect or one or more implementations of the third aspect.BRIEF DESCRIPTION OF THE DRAWINGS

[0033] For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:FW 6000747PCT02 -5-

[0034] FIG. 1 illustrates a radio access network (RAN), in accordance with some implementations of the present disclosure;

[0035] FIG. 2 illustrates a distributed unit (DU)- centralized unit (CU) split next generation Node B (gNB) architecture with separation of CU- control plane (CP) and CU- user plane (UP), in accordance with some implementations of the present disclosure;

[0036] FIG. 3A illustrates a communication system, in accordance with some implementations of the present disclosure;

[0037] FIG. 3B illustrates an example of a radio access network, where security protection on the control information of the protocol layers lower than the PDCP layer is absent;

[0038] FIG. 3C illustrates an example radio access network, in accordance with some implementations of the present disclosure;

[0039] FIG. 4 illustrates a communication system, in accordance with some implementations of the present disclosure;

[0040] FIGS. 5A-5C illustrate signaling exchanges for providing a local CU-UP, in accordance with some implementations of the present disclosure;

[0041] FIG. 6 illustrates a signaling flow for instantiating a DU-data radio bearer (DRB), in accordance with some implementations of the present disclosure;

[0042] FIG. 7 illustrates a flow diagram of example operations occurring in a user equipment (UE), in accordance with some implementations of the present disclosure;

[0043] FIG. 8 illustrates another flow diagram of example operations occurring in a UE, in accordance with some implementations of the present disclosure;

[0044] FIG. 9 illustrates a flow diagram of example operations occurring in a computing platform hosting a DU and a CU-UP of a gNB, in accordance with some implementations of the present disclosure;

[0045] FIG. 10 illustrates another flow diagram of example operations occurring in a computing platform hosting a DU and a CU-UP of a gNB, in accordance with some implementations of the present disclosure;

[0046] FIG. 11 illustrates a flow diagram of example operations occurring in a CU-CP of a gNB, in accordance with some implementations of the present disclosure;

[0047] FIG. 12 illustrates another flow diagram of example operations occurring in a CU-CP of a gNB, in accordance with some implementations of the present disclosure;FW 6000747PCT02 -6-

[0048] FIG. 13 illustrates a flow diagram of example operations occurring in a computing platform hosting a DU, in accordance with some implementations of the present disclosure a CU-UP of a gNB;

[0049] FIG. 14 illustrates an example communications system, in accordance with some implementations of the present disclosure;

[0050] FIG. 15 illustrates an example communication system, in accordance with some implementations of the present disclosure;

[0051] FIGS. 16A and 16B illustrate example devices that may implement the methods and teachings, in accordance with some implementations of the present disclosure; and

[0052] FIG. 17 illustrates a block diagram of a computing system that may be used for implementing the devices and methods, in accordance with some implementations of the present disclosure.

[0053] Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.DETAILED DESCRIPTIONS

[0054] The techniques described in this application provide methods and systems to support a local centralized unit (CU)-user plane (UP) hosted by or co-located with a distributed unit (DU). Thus, a data radio bearer (DRB) can be configured as if it is terminated at the DU. Specifically, by instantiating a local CU-UP and / or a local user plane function (UPF) on the same computing platform that also hosts the DU, and by establishing DRBs whose service data adaptation protocol (SDAP) and packet data convergence protocol (PDCP) processing are performed locally, traffic for the edge service or edge computing can avoid unnecessary back-and-forth traversal between the DU and a conventional remote CU-UP and UPF. This architecture can reduce round-trip delays, improve the responsiveness of edge services, and enable more efficient use of transport resources.

[0055] In some embodiments, radio resource control (RRC) entities can be divided into a higher part and a lower part. The higher part of the RRC entity is hosted by a CU- CP, like the conventional RRC entity. The lower part of the RRC entity (also referred to as the RRCLOW , RRC-light, RRCDU, or RRCL entity in various figures and example embodiments described subsequently) is hosted by or co-located with the DU. RRC procedures and signaling that are related to specific lower layer features can be movedFW 6000747PCT02 -7-into a media access control (MAC) layer and MAC control element (CE) to further reduce CP latency and to improve flexibility.

[0056] In addition, the present application provides a mechanism for secure transfer of lower layer control signaling without requiring a full redesign of PHY / MAC security frameworks. The disclosed signaling-DRB (S-DRB) can provide PDCP integrity protection and / or ciphering to secure these Layer i / Layer 2 control messages. The signaling-DRB may also be referred to as the security-DRB or special DRB. As a result, the techniques can jointly enhance latency, reliability, and robustness for both user plane edge services and time sensitive and operation critical control signaling.

[0057] FIG. 1 illustrates an overall architecture of a fifth generation (5G) radio access network (RAN) defined by the third generation partnership project (3GPP), upon which some inventive techniques of the present disclosure can be implemented. As shown in FIG. 1, a next generation Node B (gNB) provides user plane (UP) and control plane (CP) protocol terminations towards a user equipment (UE) (the UE is not shown in FIG. 1). Some gNBs can be interconnected with each other by means of the Xn interface. The gNBs are also connected by means of the NG interfaces to a 5G core network, more specifically to an access and mobility management function (AMF) by means of the NG-C interface (also referred to as the N2 interface) and to a user plane function (UPF) by means of the NG-U interface (also referred to as the N3 interface).

[0058] The gNB can host one or more of the following main functions: Functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in uplink, downlink and sidelink (scheduling); Upper layer protocol header compression / decompression, uplink data compression / decompression, encryption and integrity protection of data; Selection of an AMF at UE attachment when no routing to an AMF can be determined from the information provided by the UE; Routing of user plane data towards UPF(s); Routing of control plane information towards AMF; Connection setup and release; Scheduling and transmission of system broadcast information and paging messages; Measurement and measurement reporting configuration for mobility and scheduling; Quality of service (QoS) flow management and mapping to data radio bearers (DRBs); and Distribution function for non-access stratum (NAS) messages.

[0059] The AMF can host one or more of the following main functions: NAS signaling termination; NAS signaling security; Access stratum (AS) security control; Idle mode UE reachability (including control and execution of paging retransmission); Support of intra-FW 6000747PCT02 -8-system and inter-system mobility; Access authentication and authorization; and SMF selection.

[0060] The UPF can host one or more of the following main functions: Anchor point for Intra- / Inter-RAT mobility (when applicable); External protocol data unit (PDU) session point of interconnect to data network (DN); Packet routing and forwarding; Packet inspection and user plane part of policy rule enforcement; Uplink classifier to support routing traffic flows to a data network; QoS handling for user plane, e.g., packet filtering, gating, uplink / downlink rate enforcement; and Downlink packet buffering and downlink data notification triggering.

[0061] A session management function (SMF) can host one or more of the following main functions: Session management; UE internet protocol (IP) address allocation and management; Selection and control of UPF; Configures traffic steering at UPF to route traffic to proper destination; Control plane part of policy enforcement and QoS; and Downlink data notification.

[0062] A gNB can be split into one centralized unit (CU or gNB-CU) and one or more distributed units (DUs or gNB-DUs). A CU can be further divided into one CU-control plane (CU-CP or gNB-CU-CP) and one or more CUs-user planes (CU-UPs or gNB-CU- UPs). FIG. 2 illustrates a DU-CU split gNB architecture with separation of CU-CP and CU-UP, in accordance with some implementations of the present disclosure. As shown in FIG. 2, a gNB may include one CU-CP, multiple CU-UPs, and multiple DUs. The CU-CP can be connected to the DUs through the respective Fi-C interfaces. The CU-UP can be connected to the DUs through the respective Fi-U interfaces. The CU-CP can be connected to the CU-UPs through the respective El interfaces. In some embodiments, one DU can be connected to only one CU-CP at a time. In some embodiments, one CU- UP can be connected to only one CU-CP at a time.

[0063] In some embodiments, the CU-CP is connected to the AMF through the NG-C interface and hosts the radio resource control (RRC) layer and part of the packet data convergence protocol (PDCP) layer that supports the control plane. The CU-UP can be connected to the UPF through the NG-U interface and can host the service data adaptation protocol (SDAP) layer and part of the PDCP layer that supports the user plane. The DU can host the physical (PHY) layer entirely or at least the higher part of the PHY layer, the media access control (MAC) layer, and the radio link control (RLC) layer. In some implementations, the radio layer (and optionally the lower part of the PHY layer as well) may be hosted in a radio unit (RU) that is a separate RAN node from the DU andFW 6000747PCT02 -9-is connected to the DU through a fronthaul. In some embodiments, 3GPP standards may not specify the radio unit (RU), leaving it to implementation instead.

[0064] Some key functions performed at the RRC layer may include broadcast of system information, RRC connection control, access and mobility control, measurement configuration and reporting, transfer of dedicated NAS information, and transfer of UE radio capability information. Some key functions performed at the SDAP layer may include QoS flow to data radio bearer (DRB) mapping and marking QoS flow ID (QFI) on SDAP PDUs for packet routing purposes. Some key functions performed at the PDCP layer may include upper layer protocol header compression / decompression, integrity protection / verification, ciphering / deciphering, support of split bearers and duplication, duplicate detection and removal, and in-sequence delivery. Some key functions performed at the RLC layer may include error correction through automatic repeat request (ARQ) and service data unit (SDU) segmentation / reassembly. Some key functions performed at the MAC layer may include logical channel to transport channel mapping, multiplexing / de-multiplexing, error correction through hybrid ARQ (HARQ), logical channel prioritization, scheduling information reporting, radio resource selection, and support of the MAC layer control signaling through various MAC control elements (CEs). Some key functions performed at the PHY layer may include cyclic redundancy check (CRC), forward error correction (FEC) coding / decoding, rate matching, modulation / demodulation, modulation symbol to radio resource mapping, support of the PHY layer (i.e., Layer 1) control signaling through downlink control information (DCI) and uplink control information (UCI).

[0065] The making and using of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.

[0066] Detailed descriptions of some example principal solutions are provided below.

[0067] One objective of this disclosure is to provide means to reduce user plane latency for data originated from or designated to a service supported locally close to the DU, e.g., the service being supported by using an edge computing platform that either hosts the DU or is in the proximity of the DU. For example, the service may be an artificial intelligence (Al) as a service, data as a service, sensing as a service, or mediaFW 6000747PCT02 -10-rendering service. The service may collect data from the UEs, through the UEs, and / or from the DU. The service may use the collected data as inputs to inference, computing, or sensing algorithms to generate data to be sent to, or actions to be taken at, the UE and / or the DU. Many of these example services require ultra-low latency for transferring the data over the user plane. For such services, the conventional method is, for uplink data, to have the MAC layer and the RLC layer data processing performed at the DU first, then transfer the resulting data to the conventional CU-UP to have the PDCP layer and the SDAP layer data processing performed at the CU-UP, then transfer the resulting data to the conventional UPF for routing, which routes the data back to the service supported at the edge computing platform that hosts the DU or is in the proximity of the DU. For DL data, data originated at the local service and designated to the UE are routed to the conventional UPF first, then to the conventional CU-UP to have the SDAP layer and the PDCP layer data processing performed at the CU-UP, and then the CU-UP sends the resulting data to the DU for a transmission to the UE. Such a conventional method adds unnecessary round-trip delay as the data traverses back and forth between the DU and the UPF, as shown in FIG. 2, despite the fact that the local service and the DU are colocated or close to each other. The round-trip delay between the DU and the UPF may vary, depending on implementations, from several milliseconds (msec) to tens or hundreds of msecs, which may be fine for conventional data services but may be inadequate for new services, such as Al or sensing, which may require ultra-low latency.

[0068] FIG. 3A illustrates a communication system 300, in accordance with some example embodiments described herein. The communication system 300 can be used to avoid the round-trip delay as discussed above. As shown in FIG. 3A, communication system 300 includes a computing platform (denoted as DU+) 310, which hosts a DU 320, a locally configured CU-UP 340, and a locally configured UPF 330. Communication system 300 also includes a conventional CU-CP 380, a conventional UPF 390, an AMF 392, an SMF 394, and may further include a conventional CU-UP 370. According to one example embodiment, UPF 330 is locally configured at computing platform 310 that also hosts DU 320, as shown in FIG. 3A. According to an alternative example embodiment, UPF 330 is configured not at computing platform 310 but at an edge computing platform 360 that is close to DU 320. In both embodiments, a PDU session maybe established between a UE and UPF 330 for a service that is provided locally at edge computing platform 360, such as Al, data, sensing, or media rendering service, as described before. For example, after establishing a first PDU session (e.g., the default PDU session) with the convention UPF 390 and establishing a first DRB (e.g., the default DRB) with the conventional CU-UP 370 in association with the first PDU session, the UE obtains IPFW 6000747PCT02 -11-connectivity. Then, the UE may use its IP connectivity and a service discovery protocol, such as Domain Name System (DNS), DNS Service Discovery (DNS-SD), Bonjour, Dynamic Host Configuration Protocol (DHCP), Simple Service Discovery Protocol (SSDP), to name a few, to discover an application server that provides the desired service locally at edge computing platform 360. Based on the IP address of the application server discovered, SMF 394 may select UPF 330 to be the PDU Session Anchor (PSA) UPF (PSA-UPF) of a second PDU session of the UE and then configures the UE (e.g., through NAS session management messages) and UPF 330 (e.g., through N4 messages) to establish the second PDU session accordingly, the second PDU session being established for data of the UE-desired service that is provided locally at edge computing platform 360.

[0069] In some embodiments, having the second PDU session established is insufficient to avoid the round-trip delay between DU 320 and the conventional CU-UP 370. A second DRB may need to be established for the UE for the QoS flow(s) of the second PDU session and the second DRB needs to be terminated close to DU 320 on the gNB side. Therefore, in accordance with one example embodiment, SDAP entity 342 and PDCP entity 344 are instantiated (i.e., configured on-demand) for the second DRB of the UE at the locally configured CU-UP 340, which is also hosted at computing platform 310, so that the SDAP layer and the PDCP layer data processing at the gNB side for data on the second DRB can be performed locally close to DU 320. The second DRB may be referred to as the DU-DRB because it is configured as if being terminated at the DU. In other words, a termination point of the second DRB or the DU-DRB is at the DU 320. For data on the DU-DRB that are originated from the local service supported at edge computing platform 360 and to be transmitted to the UE, the local service can submit the data directly to UPF 330, and UPF 330 routes the data to SDAP entity 342 for a transmission over the DU-DRB to the UE without the round-trip between DU 320 and the conventional UPF 390. For data received on the DU-DRB from the UE that are designated to the local service, SDAP entity 342 can forward the resulting data to UPF 330, which then routes the data to the local service, without the round-trip between DU 320 and the conventional UPF 390.

[0070] Another objective of this disclosure is to overcome the issue of Layer 1 and / or Layer 2 control signaling being currently transmitted without security protection against malicious attacks, such as forgery or replay attacks. Layer 1 (i.e., the PHY layer) control signaling between the DU and the UE include various types of DCIs and UCIs. Layer 2 control signaling between the DU and the UE may include various types of MAC CEs in the MAC layer, RLC control PDUs in the RLC layer, and PDCP control PDUs in the PDCPFW 6000747PCT02 -12-layer. FIG. 3B shows an example of a 3GPP 5G NR radio access network, where security protection on the control information of the protocol layers lower than the PDCP layer is absent. The 3GPP 5G NR radio access network can include a UE and a gNB. In the 3GPP 5G NR radio access network, as illustrated in FIG. 3B, the access stratum security is provided through the PDCP layer (e.g., PDCP layers in the UE and PDCP layers in the gNB as shown in FIG. 3B) for data sent over the DRB and SRB. However, the Layer 1 and Layer 2 control signaling such as DCIs, UCIs, MAC CEs, RLC control PDUs, and PDCP control PDUs are not security protected. A recent trend in the standards is that MAC CEs (and DCIs to a lesser degree) are being used for signaling configuration of certain radio related features that are controlled by the DU or for signaling command that activates or deactivates such features. Some of these MAC CEs and DCIs are operation-critical and yet vulnerable to forgeiy or replay attacks due to a lack of integrity protection at the MAC or PHY layer to verify the authenticity of the source of, or the content in, the control signaling. As these lower layer control signaling tend to carry no sensitive information of the end user, the lack of cyphering (for protecting confidentiality) on these lower layer control information may be less critical. Nonetheless, extending the existing 3GPP security framework to the DU to provide the integrity protection on the lower layer control information (such as MAC CEs and DCIs) is non-trivial. In some embodiments, it requires a new set of security keys be introduced for the DU, along with the key generation method, signaling for key distribution and security activation, and means to counter replay attacks (e.g., introducing MAC sequence number to be carried in the MAC PDUs). A lot of time and efforts for study, standardization, and implementation are required.

[0071] According to example embodiments described herein, e.g., as shown in FIG. 3A, a modified DU-DRB, referred to as a signaling-DRB (S-DRB) 350, can be configured on a per UE basis with the SDAP entity 346 and the PDCP entity 348 of the S-DRB on the gNB side being instantiated at the locally configured CU-UP 340 hosted by computing platform 310. The signaling-DRB may also be referred to as the security-DRB or special DRB. The S-DRB 350 may be configured with no association with any PDU session ID of the UE (or with an association with a pre-defined Null PDU session ID) to differentiate from a regular DU-DRB, which is used for carrying user data, as described earlier. An El interface established between CU-UP 340 and CU-CP 380 can be used by CU-CP 380 for provisioning the security keys and security related configuration on PDCP entity 348 of the S-DRB, e.g., by using the Bearer Context Management procedures over the El interface. An RRC entity 382 configured in CU-CP 380 for the UE also sends the UE a dedicated RRC message, e.g., an RRCReconfiguration message, to configure the peerFW 6000747PCT02 -13-entities of SDAP entity 346 and PDCP entity 348 at the UE side, among other RRC configurations, to complete the establishment of the S-DRB 350 for the UE.

[0072] Unlike a regular DU-DRB, the S-DRB 350 may not carry any data of any valid PDU sessions of the UE. Instead, it provides secured transport for the operation-critical Layer 1 and Layer 2 control signaling, such as MAC CEs and DCIs, between the UE and DU 320 by using the integrity protection and verification functions of PDCP entity 348 of the S-DRB 350. Because DU 320, and PDCP entity 348 and SDAP entity 346 of the S- DRB 350 are hosted on the same computing platform 310, DCIs, MAC CEs, or RLC control PDUs may be transferred between SDAP entity 346 and PHY entity 322, MAC entity 324, or the RLC entities through respective connections internally within computing platform 310 between SDAP entity 346 and PHY entity 322, MAC entity 324, or the RLC entities. SDAP entity 346 treats these DCIs, MAC CEs, or RLC control PDUs as SDAP SDUs. To determine whether a lower layer control message securely received over the S-DRB 350 should be forwarded to the PHY entity (for DCIs), to the MAC entity (for MAC CEs), or to an RLC entity (for RLC control PDUs) for further processing at the receiving side, specific QFI values may be pre-configured for indicating DCI (or PHY entity as the routing destination), MAC CE (or MAC entity as the routing destination), and RLC control PDU (or RLC entity as the routing destination), respectively. On the transmitting side, the SDAP entity of the S-DRB 350 (e.g., SDAP entity 346 for the DL direction or the peer entity of SDAP entity 346 on the UE side for the UL direction) can add a SDAP header to the SDAP SDU (i.e., the Li or L2 signaling payload that needs a secured transfer) received from the PHY, MAC, or RLC entity for a transmission, the QFI value in the SDAP header being selected based on the pre-configured QFI assignments and the entity (among the PHY, MAC, and RLC entities) that the SDAP SDU is received from for the transmission. For RLC control PDUs, the SDAP header may further include the logical channel ID (LCID) associated with the RLC entity that the RLC control PDU is received from to further differentiate between different RLC entities or different QFI values can be pre-specified for the different RLC entities to differentiate them. Then, on the receiving side, the SDAP entity of the S-DRB 350 (e.g., SDAP entity 346 for the UL direction or the peer entity of SDAP entity 346 on the UE side for the DL direction) can route the received SDAP SDU, along with an ID of the UE, to an entity among the PHY, MAC, or RLC entities in accordance with the QFI value in the SDAP header of the SDAP PDU, for further processing. For RLC control PDUs, the QFI and / or the LCID included in the SDAP header can be used for determining the RLC entity that the RLC control PDU is for. The QFI value assignments (for identifying DCI, MAC CE, and RLC control PDU) may be a part of the SDAP configuration for SDAP entity 346. In addition, a lack ofFW 6000747PCT02 -14-associated PDU Session ID in the SDAP configuration (or the PDU Session ID in the SDAP configuration being a pre-specified Null PDU Session ID) indicates that the DRB being configured is an S-DRB 350 that does not serve any data of any PDU sessions of the UE, and instead, is used for securely transferring Layer 1 and Layer 2 control signaling between the UE and the DU.

[0073] PDCP entity 348 may be configured by CU-CP 380 (e.g., through Bearer Context Management procedures over the El interface), and its peer PDCP entity on the UE side can be configured by RRC entity 382 (e.g., through dedicated RRC messages to the UE) to perform integrity protection and verification and to perform out-of-order delivery. PDCP entity 348 and its peer PDCP entity on the UE side may also be configured not to perform header compression or decompression or not to perform cyphering or deciphering for data on the S-DRB 350. In the example embodiments shown in FIGS. 3A, 3C, and 4, the SDAP entity (such as SDAP entities 346 and 446) and the PDCP entity (such as PDCP entities 348 and 448) are described as two distinct logical entities for handling the respective functions of the SDAP layer and the PDCP layer. In the future evolution of the 3GPP 5G NR standard, e.g., in the 3GPP sixth generation (6G) standard, it is possible that the SDAP layer and the PDCP layer may be merged into one layer, where the cyphering and integrity protection functions (similar to the ones provided by the PDCP layer in 5G NR) performed by the combined protocol layer and the pre-specified identifiers (similar to the pre-specified QFIs in the SDAP header in 5G NR) added in the header of the combined protocol layer can be used for allowing the S-DRB, which is similarly configured, to provide the secured transfer of the control signals of multiple Li or L2 protocol layers.

[0074] The method of configuring a DRB as secured transport for the various lower layer control signaling can be applied not only to gNBs that are referred to as the DU-CU- split gNBs, where the DU and the CU of the gNB are separated as shown in FIG. 3A, but also to gNBs that are referred to as the integrated gNB, where the DU and the CU functionalities of a same gNB are implemented in a same network device. FIG. 3C shows another example 3GPP 5G NR radio access network, in accordance with some implementations of the present disclosure. The 3GPP 5G NR radio access network in FIG. 3C includes a UE and a gNB (e.g., an integrated gNB). As shown in FIG. 3C, an S- DRB 352 (e.g., S-DRB 352a in the UE and S-DRB 352b in the gNB) is configured between the gNB and the UE as secured transport of lower layer control signaling, such as MAC CEs, RLC control PDUs, and PDCP control PDUs. On the transmitter side, regardless of whether the transmitter is the UE or the gNB, these lower-layer control signaling messages are submitted to the SDAP layer as input data, i.e., the SDAP SDU, for aFW 6000747PCT02 -15-transmission. In 6G, the SDAP layer may be combined with the PDCP layer into a new protocol layer, or the SDAP layer may be referred to with a different name. Then, the lower-layer control signaling message goes through various Layer 2 protocol layer processing, such as the SDAP layer processing, the PDCP layer processing, the RLC layer processing, and MAC processing, by the entities configured on the transmitter side, respectively, for the corresponding protocol layers. Hence, the transmitting PDCP entity configured for the S-DRB 352 performs the integrity protection and the cyphering on these lower layer control signaling messages.

[0075] On the receiver side, regardless of whether the receiver is the gNB or the UE, as the received PDUs traverse through the various Layer 2 protocol layers on the S-DRB 352 and arrive at the PDCP layer, the receiving PDCP entity configured for the S-DRB 352 can perform the deciphering and integrity verification. If the received PDCP PDU is integrity-verified successfully, the corresponding PDCP SDU is delivered to the SDAP entity (or the SDAP-PDCP combined protocol layer entity in 6G) configured for the S- DRB 352 on the receiver side for message routing based on the QFI indication and the pre-configured mapping of QFI values to MAC entity, RLC entities, and PDCP entities, as described before. In some embodiments, once routed to the corresponding protocol layer entity, the message is further processed in accordance with the protocols of that protocol layer.

[0076] Currently, some RRC messages sent to the UE can be triggered by conditions or events occurred at the DU. For example, the DU detects that a condition or event has occurred, and based thereon, sends an Ft application protocol (FiAP) message to notify the CU-CP. In response, the CU-CP generates a corresponding RRC message to be sent to the UE and sends a second FiAP message back to the DU, the second FiAP message encapsulating the RRC message for the UE. Then, the DU sends the RRC message to the UE. The round-trip delay between the DU and the CU-CP may vary from several msecs to tens of msecs, depending on implementations, and could be avoided if the DU can send the related control message to the UE directly. Therefore, yet another objective of this disclosure is to further reduce the control plane latency by partitioning some of the functions performed at the RRC layer today to a lower layer, e.g., to the MAC layer or to an RRCL (which may also be referred to as RRCLOW, RRC-light, or RRCDU) layer that is hosted locally with the DU, e.g., hosted at the same computing platform that hosts the DU, so that control signaling to the UE at the MAC layer or the RRCL layer can be initiated locally at the DU without going through the RRC entity (such as RRC entity 382) in the CU-CP (such as CU-CP 380). Example RRC functions and signaling messages that can be spun off the CU-CP, either to the MAC layer or to the new RRCL layer hosted withFW 6000747PCT02 -16-the DU, include but not limited to one or more of the following: for bandwidth part (BWP), faster and more secured BWP switching / adaptation; for CA, addition / modification / release of SCell(s) or (de)activation of pre-configured SCell(s); for radio configuration control, dynamic ARQ / HARQ configuration or SPS / CG configuration based on channel conditions, traffic conditions, and data reception / discarding results; for LCP, adjusting LCII priorities and prioritized bit rates (PBRs) based on data reception and BSR; for RACII optimization, RA Report in UEInfoResponse and ra-ReportReq in UEInfoRequest; or for network controlled repeater (NCR), configuration of side control information for NCR-node.

[0077] In some embodiments, the principle is to use the CU-CP and the conventional RRC signaling to pre-configure certain lower-layer related radio features, as listed above, as well as conditions for execution or de(activation) of the corresponding radio feature, and when the DU determines that the pre-set conditions are met, use the DU and new MAC CE or new RRCL signaling message, which is initiated at the DU, to signal the execution or (de)activation of the corresponding radio feature to the UE, and thereby avoiding the round-trip delay over the Fi-C interface, which is the case today for some conventional RRC signaling when they are triggered by certain FiAP message from the DU due to conditions occurred at the DU.

[0078] In one embodiment, one or more of the above RRC functions are performed at the MAC layer, and the related signaling messages are conveyed in the form of MAC CEs. Then, if any of these functions and signaling messages are operation-critical, the MAC CE defined for carrying the corresponding signaling message can be conveyed between the UE and the DU using the S-DRB 350, as illustrated in FIG. 3A and described above.

[0079] In an alternative embodiment, one or more of the above RRC functions are performed at the new RRCL layer that is hosted locally with the DU. This technique may be referred to as the split RRC. FIG. 4 illustrates a communication system 400, in accordance with some implementations of the present disclosure. As shown in FIG. 4, an RRCL entity 450 may be instantiated for a UE on a per UE basis at computing platform 410 that also hosts DU 420. RRCL entity 450 uses the secured transport service provided by an S-DRB 452 configured for the UE, as described before, the S-DRB 452 using SDAP entity 446 and PDCP entity 448 and their peer entities configured on the UE side, SDAP entity 446 and PDCP entity 448 being configured as a part of local CU-UP 440, which is also hosted at computing platform 410.

[0080] RRCL entity 450 performs the one or more functions related to lower layers, as listed before, and terminates the related RRC signaling with the UE using the securedFW 6000747PCT02 -17-transport service provided by the S-DRB 452, as described before. RRCL entity 450 also interfaces with RRC entity 482, which is configured for the UE in CU-CP 480, to obtain instruction and information of the pre-configured features and conditions for execution or (de)activation of them, and to report operation results and status, etc.

[0081] The Fi-C interface between CU-CP 480 and DU 420 can be enhanced for signaling exchanges between RRC entity 482 and RRCL entity 450. For example, RRC entity 482, after learning the UE’s capability of using the S-DRB to securely transport the RRCL message with the gNB (DU), may initiate a UE Context Modification procedure over the Fi-C interface to instantiate RRCL entity 450 for the UE at computing platform 410 that hosts DU 420. The UE Context Modification Request message sent may further encapsulate an RRCReconfiguration message to be sent to the UE by DU 420 to configure an S-DRB, if it is not established yet, and the peer RRCL entity on the UE side. A CU / DU RRC Information Transfer procedure and related FiAP message can be specified. For example, a CU-to-DU RRC Information Transfer message can be sent by RRC entity 482 to RRCL entity 450 over the Fi-C interface to provide instructions and information of the pre-configured lower layer features and conditions for execution or (de)activation of them, and a DU-to-CU RRC Information Transfer message can be sent by RRCL entity 450 to RRC entity 482 over the Fi-C interface to report operation results and status. Alternatively, contents in the two above messages can be encapsulated in the UE Context Modification Request and Response messages, respectively, e.g., in a new transparent container IE in the messages. Generally speaking, CU-CP 480 should not simultaneously use both RRC entity 482 (using the conventional RRC signaling messages sent over the conventional signal radio bearer 1 (SRBi)) and RRCL entity 450 (using the RRCL signaling messages sent over the S-DRB 452) to execute or (de)activate a feature with the UE to avoid the issue of racing condition and the need for arbitration between the two. If RRCL entity 450 is configured to execute or (de)activate a feature, RRC entity 482 is only responsible for configuring the UE and RRCL entity 450 for the feature, and RRCL entity 450 is responsible for executing or (de)activating the feature. RRCL entity 450 can report the operation results and status to RRC entity 482 to synchronize with RRC entity 482.

[0082] In one embodiment, when determining that the pre-set conditions for a preconfigured feature are met, RRCL entity 450 generates a corresponding RRCL message, e.g., for executing or (de)activating the feature at the UE, and then submits the RRCL message to SDAP entity 446 for a transmission to the UE over the S-DRB of the UE. In an alternative embodiment, RRC entity 482 prepares the content of signaling messages to be sent by RRCL entity 450 to the UE and provides the prepared messages, along withFW 6000747PCT02 -18-the respective conditions to be met for sending them, to RRCL entity 450 using the CU- to-DU RRC Information Transfer (or UE Context Modification Request) message, as described above. Then, when the pre-set conditions are met, RRCL entity 450 simply submits the provided message corresponding to the conditions met to SDAP entity 446 for a transmission to the UE over the S-DRB 452.

[0083] To differentiate RRCL messages from DCIs, MAC CEs, and RLC control PDUs for routing purpose at the receiving side, a unique QFI value is also assigned to the RRCL messages (or to indicate the RRCL entity as the routing destination). Such QFI assignment can be included in the SDAP configuration when configuring the S-DRB at the UE and at local CU-UP 340, respectively.

[0084] Some example methods for providing a local CU-UP are described in detail below.

[0085] In some example embodiments, a local CU-UP (such as CU-UP 340 and 440) is already configured, e.g., by operations, administration, and maintenance (OAM), at the same computing platform (such as computing platform 310 and 410) that hosts a DU (such as DU 320 and 420). In this situation, in accordance with one example embodiment, the DU informs a CU-CP (such as CU-CP 380 and 480) that it is co-located with the CU-UP, e.g., during Ft Setup procedure or gNB-DU Configuration Update procedure. FIG. 5A illustrates the signaling exchanges in accordance with this example embodiment. As shown in FIG. 5A, in step 501, the DU initiates an Fl Setup (or gNB-DU Configuration Update) procedure by sending an Ft Setup Request (or gNB-DU Configuration Update) message to the CU-CP. The Ft Setup Request (or the gNB-DU Configuration Update) message may include information about the local CU-UP (e.g., the gNB-CU-UP ID of the local CU-UP), explicitly or implicitly indicating that the DU is colocated with this CU-UP. The Fl Setup Request message can also include the gNB-DU ID of the DU, among other information about the DU. In step 502, the CU-CP sends back an Ft Setup Response (or gNB-DU Configuration Update Acknowledge) message including information needed for the DU and the CU-CP to correctly interoperate on the Fi-C interface. In step 503, the CU-CP initiates a gNB-CU-CP El Setup procedure by sending a gNB-CU-CP Ei Setup Request message to the local CU-UP. The gNB-CU-CP El Setup Request message may include the gNB-CU-CP name of the CU-CP, among other information about the CU-CP. In step 504, the local CU-UP sends back a gNB-CU-CP El Setup Response message to the CU-CP. The gNB-CU-CP Ei Setup Response message may include the gNB-CU-UP ID of the local CU-UP, among other information about the local CU-UP.FW 6000747PCT02 -19-[oo86] In accordance with an alternative example embodiment, after the local CU-UP (such as CU-UP 340 and 440) is configured, e.g., by OAM, at the same computing platform (such as computing platform 310 and 410) that hosts the DU (such as DU 320 and 420) and after the DU has established the Fi-C interface with the CU-CP (such as CU-CP 380 and 480), the local CU-UP informs the CU-CP that it is co-located with the DU, e.g., during a gNB-CU-UP El Setup procedure. FIG. 5B illustrates the signaling exchanges in accordance with this alternative example embodiment. As shown in FIG. 5B, the DU and the CU-CP can establish the Ft interface between them in steps 511 and 512, which may occur either before or after the local CU-UP is configured. For example, in step 511, the CU-CP obtains the gNB-DU ID of the DU. Then, in step 513, the local CU- UP initiates a gNB-CU-UP El Setup procedure by sending a gNB-CU-UP El Setup Request message to the CU-CP. The gNB-CU-UP El Setup Request message may include information about the co-located DU (e.g., the gNB-DU ID of the co-located DU), explicitly or implicitly indicating that the local CU-UP is co-located with this DU. The gNB-CU-UP Ei Setup Request message may also include the gNB-CU-UP ID of the CU- UP, among other information about the CU-UP. In step 514, the CU-CP sends back a gNB-CU-UP Ei Setup Response message to the local CU-UP. The gNB-CU-UP Ei Setup Response message may include the gNB-CU-CP name of the CU-CP, among other information about the CU-CP.

[0087] In yet another alternative example embodiment, the local CU-UP is not configured at the computing platform (such as computing platform 310 and 410) that hosts the DU (such as DU 320 and 420) yet. In this situation, the CU-CP indicates to the DU to set up a local CU-UP via Fl Setup (or gNB-DU Configuration Update) procedure after learning the DU’s capability of supporting the local CU-UP. FIG. 5C illustrates the signaling exchanges in accordance with this example embodiment. As shown in FIG. 5C, in step 521, the DU initiates an Fl Setup (or gNB-DU Configuration Update) procedure by sending an Fl Setup Request (or gNB-DU Configuration Update) message to the CU- CP. The Fi Setup Request (or the gNB-DU Configuration Update) message may include information indicating that the DU is capable of supporting a local CU-UP. The Fi Setup Request message also includes the gNB-DU ID of the DU, among other information about the DU. In step 522, the CU-CP sends back an Fi Setup Response (or gNB-DU Configuration Update Acknowledge) message including information instructing the DU to configure a local CU-UP. The instruction may include information about the local CU- UP to be configured, e.g., the gNB-CU-UP ID (or gNB-CU-UP name) of the local CU-UP. Then, the computing platform that hosts the DU may instantiate a local CU-UP followingFW 6000747PCT02 -20-the instruction from the CU-CP. After that, steps 523 and 524 in FIG. 5C may be similar to, or the same as steps 513 and 514 described in FIG. 5B.

[0088] In all three embodiments described above, the El interface is established between the local CU-UP and the CU-CP after the fourth step (e.g., steps 504, 514, or 524), through which interface the CU-CP can send El application protocol (EiAP) Bearer Context Management related signaling messages to the local CU-UP to instantiate one or more DU-DRBs on the local CU-UP for the UE. For example, one of the DU-DRBs can be the S-DRB used for securely transferring the DCIs, MAC CEs, and / or RLC control PDUs between the DU and the UE, as described before. For another example, one or more of the DU-DRBs can be used for transferring data originated from or destinated to a local service supported at an edge computing platform (such as edge computing platform 360 and 460) that is close to the DU or is the same computing platform that hosts the DU, as described before.

[0089] Detailed descriptions of some example methods for instantiating a DU-DRB are provided below.

[0090] FIG. 6 illustrates an example signaling flow for instantiating a DU-DRB. As shown in FIG. 6, after the Fi-C interface is set up between the DU and the CU-CP in step 601 and the El interface is set up between the local CU-UP and the CU-CP in step 602, which steps are similar to, or the same as steps described in details in FIGS. 5A-5C, the CU-CP determines a need to set up a DU-DRB between the local CU-UP and the UE in step 603. For example, the CU-CP may have received, from the AMF over the NG-C interface, a PDU Session Resource Setup Request message to assign resources over the radio interface and the NG-U interface for a PDU session of the UE. The PDU Session Resource Setup Request message may include information indicating that the PDU session is to be anchored at a local UPF (such as UPF 330 and 430) that is hosted by the same computing platform (such as computing platform 310 and 410) that hosts the DU (such as DU 320 and 420), e.g., the PDU Session Resource Setup Request message may include the gNB-DU ID of the DU or the UPF ID of the local UPF, which may cause the CU-CP to select the local CU-UP (such as CU-UP 340 and 440) that co-locates with the DU to handle the DRBs (which are DU-DRBs) of this PDU session of the UE from the gNB side.

[0091] In another example, the CU-CP may have decided to configure one instance of an S-DRB, as described before, to securely transfer the DCIs, MAC CEs, and / or RLC control PDUs to (or from) the UE, e.g., for at least those that are operation-critical. In this situation, the SDAP entities on the S-DRB are to be configured (on the UE side andFW 6000747PCT02 -21-the local CU-UP side through the SDAP configuration information) without association with any valid PDU session of the UE, e.g., by the absence of a PDU session ID of the UE or by the presence of a pre-specified Null PDU session ID in the SDAP configuration. The PDCP entities on the S-DRB are to be configured (on the UE side and the local CU-UP side through the PDCP configuration information) to perform the integrity protection and verification, to perform out-of-order deliveiy, not to perform header compression and decompression, and / or not to perform cyphering and deciphering for the data (which carries the DCIs, MAC CEs, and / or RLC control PDUs) on the S-DRB.

[0092] The CU-CP then initiates a Bearer Context Setup procedure in step 604, by sending a Bearer Context Setup Request message to, and receiving a Bearer Context Setup Response message from, the local CU-UP over the El interface between the CU-CP and the local CU-UP. The Bearer Context Setup Request message includes the SDAP configuration information and the PDCP configuration information, as described before. The CU-CP may also initiate a UE Context Setup procedure by sending a UE Context Setup Request message to the DU in step 605. The UE Context Setup Request message may include information about the lower layer configuration on the gNB side for the DU- DRBs and the S-DRB to be established, such as information of the RLC entities to be configured respectively for the DU-DRBs and the S-DRB to be established. The UE Context Setup Request message also includes an RRC container, which carries the RRC message referred to as the RRCReconfiguration message. The RRCReconfiguration message is to be sent by the DU to the UE to configure the SDAP, PDCP, RLC, and MAC entities on the UE side for the DU-DRBs and the S-DRB to be established. Then, in step 606, the DU sends the RRCReconfiguration message to the UE over the radio interface. The UE configures the various protocol entities on the UE side for the DU-DRBs and the S-DRB accordingly. In step 607, the UE sends back the RRCReconfigurationComplete message to the DU over the radio interface. In step 608, the DU sends a UE Context Setup Response message back to the CU-CP, indicating the readiness of the DU-DRBs and the S-DRB from the DU side. The UE Context Setup Response message also encapsulates the RRCReconfigurationComplete message from the UE in the RRC container, the RRCReconfigurationComplete message indicating the readiness of the DU-DRBs and the S-DRB from the UE side. Then, for DU-DRBs configured for the local service used by the UE, data transfer between the UE and the local CU-UP, and through the local CU-UP and the local UPF, to / from the local service provided at the edge computing platform (such as edge computing platform 360 and 460) may begin in step 609. For the S-DRB configured as the secured transport for DCIs, MAC CEs, and / or RLC control PDUs, the corresponding protocol entities may begin to submit DCIs, MAC CEs,FW 6000747PCT02 -22-and RLC control PDUs, respectively, as if they are data (i.e., SDAP SDUs), to the SDAP entity configured for the S-DRB for a secured transfer to their respective peer entity in step 609.

[0093] The various techniques described in this disclosure can be used for enhancing the 5G RAN or for defining the 6G RAN, which is currently being studied for standardization .

[0094] Detailed descriptions of some example operation flows of the UE for using a DU-DRB are provided below.

[0095] FIG. 7 illustrates a flow diagram of example operations 700 occurring in a UE. Operations 700 may be indicative of operations occurring in a UE, as the UE uses a DU- DRB for exchanging data with a DU of a gNB. The DU can serve the UE. The DU-DRB can be a DRB that is terminated at the same computing platform that hosts the DU, hence as if being terminated at the DU.

[0096] Operations 700 begin with the UE indicating to the CU-CP (such as CU-CP 380) of the gNB that the UE is capable of supporting DU-DRBs that terminate at a CU- UP (such as CU-UP 340) of the gNB, the CU-UP being co-located with a DU (such as DU 320) of the gNB, the DU serving the UE, in operation 710. The UE may indicate such capability when it initially gains the RRC connection with the gNB. Alternatively, the UE may indicate such capability after it discovers a need for using DU-DRBs that terminate at the CU-UP co-located with the DU. For example, after gaining the RRC connection and thereafter a first (and default) PDU session with a PSA-UPF (such as UPF 390), the UE may use its newly gained IP connectivity to discover a service that is provided by an application server in the proximity of the DU, e.g., an Al service provided on the same computing platform (such as computing platform 310) hosting the DU (such as DU 320) or on an edge computing platform (such as edge computing platform 360) that is in the proximity of the DU. As the UE sends a request for this local service, it may be instructed to establish a second PDU session with a local UPF (such as UPF 330) for the local service. Therefore, the UE may indicate its capability to the CU-CP so that a DU-DRB can be configured for the second PDU session.

[0097] The UE then receives an RRC message (such as an RRCReconfiguration message) from the CU-CP (such as CU-CP 380) instructing the UE to establish a DU- DRB with the CU-UP co-located with the DU for the second PDU session, in operation 720. The RRC message may instruct the UE to establish more than one DU-DRBs for the second PDU session. The RRC message includes information to configure a SDAP entity, a PDCP entity, and an RLC entity for each DU-DRB to be established. The UE establishesFW 6000747PCT02 -23-the DU-DRB(s) in accordance with the RRC message, in operation 730. Then, the UE starts to use the DU-DRB(s) to exchange data with the CU-UP co-located with the DU, and through the CU-UP and the co-located UPF, with the application server that provides the local service, in operation 740. Then, operations 700 may end.

[0098] Detailed descriptions of some operation flows of the UE for using S-DRB to securely transfer lower layer control messages with the DU are provided below.

[0099] FIG. 8 illustrates a flow diagram of example operations 800 occurring in a UE. Operations 800 maybe indicative of operations occurring in a UE, as the UE uses a signaling-DRB (S-DRB) for securely exchanging lower layer control messages, such as DCIs, MAC CEs, RLC control PDUs, and / or RRCL messages, with a DU of a gNB, the DU serving the UE, the S-DRB being a DRB that is terminated at the same computing platform that hosts the DU.

[0100] Operations 800 begin with the UE indicating to the CU-CP (such as CU-CP 480) of the gNB serving the UE that the UE is capable of supporting S-DRB that terminates at a CU-UP (such as CU-UP 440) of the gNB, the CU-UP being co-located with a DU (such as DU 420) of the gNB, the DU serving the UE, in operation 810. The UE may indicate such capability when it initially gains the RRC connection with the gNB. Alternatively, the UE may implicitly indicate such capability by requesting the CU-CP, after the UE gaining the initial RRC connection, to configure an S-DRB for the UE. For example, the UE may request the S-DRB due to a need for securely transferring some DCIs, MAC CEs, RLC control PDUs, and / or RRCL messages that are operation-critical with the DU.

[0101] The UE receives an RRC message (such as an RRCReconfiguration message) from the CU-CP, the RRC message instructing the UE to establish an S-DRB with the CU-UP co-located with the DU, in operation 820. The RRC message includes information for configuring a SDAP entity, a PDCP entity, and an RLC entity for the S-DRB to be established. For example, the information for configuring the SDAP entity for the S-DRB may include information indicating the S-DRB being associated with no valid PDU session of the UE, e.g., by not including any PDU session ID at all or by including a predefined null PDU session ID in the SDAP-config information element (IE) in the RRC message. For another example, the information for configuring the SDAP entity for the S- DRB may include information indicating the QFI values assigned to DCIs (or the PHY entity as their source or destination), MAC CEs (or the MAC entity as their source or destination), RLC control PDUs (or the RLC entity as their source or destination), and RRCL messages (or the RRCL entity as their source or destination), respectively. For yetFW 6000747PCT02 -24-another example, the information for configuring the PDCP entity for the S-DRB may configure the PDCP entity to enable integrity protection. For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to enable out-of-order delivery. For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to not to perform cyphering, e.g., by configuring a null cyphering algorithm such as NEAo (where “o” as zero). For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to disable header compression. For yet another example, the information for configuring the RLC entity for the S-DRB may include information configuring the RLC entity to operate at the acknowledged mode (AM). The RLC entity operating at the AM supports error correction through ARQ, thereby making the transfer of those operation-critical lower layer control messages more reliable.

[0102] The UE can establish the S-DRB in accordance with the RRC message, in operation 830. The UE can generate a first lower layer control message to be sent to the DU securely, in operation 840. For example, the first lower layer control message may include a DCI, a MAC CE, an RLC control PDU, or an RRCL message that is operation- critical. The UE then sends the first lower layer control message to the DU through the S- DRB, in operation 850. For example, after the first lower layer control message (as a SDAP SDU) arrives from a corresponding lower layer protocol entity, the SDAP entity configured on the S-DRB treats it as a SDAP SDU and adds a SDAP header to the SDAP SDU to produce a SDAP PDU, the QFI value included in the SDAP header being the QFI value assigned to the lower layer protocol entity that has submitted the lower layer control message to the SDAP entity for the transmission. The SDAP entity then submits the produced SDAP PDU to the PDCP entity configured for the S-DRB, as a PDCP SDU. The PDCP entity adds integrity protection to the PDCP SDU to produce the PDCP PDU and submits the PDCP PDU to the RLC entity configured for the S-DRB for the transmission over the S-DRB.

[0103] The UE may receive a second lower layer control message from the DU through the S-DRB, in operation 860. For example, the PDCP entity configured for the S- DRB may receive a PDCP PDU carrying the second lower layer control message, perform integrity verification on the PDCP PDU to produce a PDCP SDU, and consider the PDCP SDU being received successfully and being authentic and then forward the PDCP SDU (as a SDAP PDU) to the SDAP entity configured for the S-DRB only if the integrity verification is successful. The SDAP entity of the UE can forward the second lower layer control message to a corresponding lower layer protocol entity for further processing, inFW 6000747PCT02 -25-operation 870. For example, after the PDCP SDU arrives at the SDAP entity as a SDAP PDU, the SDAP entity removes the SDAP header from the SDAP PDU to produce a SDAP SDU, which is the second lower layer control message, and forwards the second lower layer control message to a lower layer protocol entity corresponding to the QFI value in the SDAP header of the SDAP PDU received, for further processing. Then, operations 800 may end.

[0104] Detailed descriptions of some example operation flows of the computing platform DU are provided below. In some embodiments, the computing platform DU can use a DU-DRB.

[0105] FIG. 9 illustrates a flow diagram of example operations 900 occurring in a computing platform hosting a DU of a gNB and a CU-UP of the gNB. Operations 900 may be indicative of operations occurring in a computing platform hosting a DU of a gNB and a CU-UP of the gNB, as it uses a DU-DRB for exchanging data with a UE served by the DU, the DU-DRB being a DRB that is terminated at the CU-UP co-located with the DU on the same computing platform, hence as if being terminated at the DU.

[0106] Operations 900 begin with the DU (such as DU 320) indicating, to the CU-CP (such as CU-CP 380) of the gNB, its capability of supporting DU-DRBs that terminate locally at a CU-UP (such as CU-UP 340) of the gNB that is co-located with the DU on the same computing platform, in operation 910. For example, the DU may indicate such capability during an Fl Setup procedure with the CU-CP, as illustrated in FIG. 5C and described before. For another example, the DU may implicitly indicate such capability during an Ft Setup procedure with the CU-CP by indicating the co-located CU-UP, as illustrated in FIG. 5A and described before. For yet another example, the CU-UP colocated with the DU may implicitly indicate such capability of the DU during an El Setup procedure with the CU-CP by indicating that it is co-located with the DU, as illustrated in FIG. 5B and described before.

[0107] The DU and the co-located CU-UP receives an FiAP and an EiAP message, respectively, from the CU-CP for establishing a DU-DRB for a UE served by the DU, in operation 920. The FiAP message and the EiAP message from the CU-CP may request the establishment of more than one DU-DRBs for the UE. For example, the DU may receive a UE Context Setup Request message, which is an FiAP message, from the CU- CP, the UE Context Setup Request message requesting the DU to configure an RLC entity for each DU-DRB to be established for the UE. For another example, the CU-UP colocated with the DU may receive a Bearer Context Setup Request message, which is an EiAP message, from the CU-CP, the Bearer Context Setup Request message requestingFW 6000747PCT02 -26-the CU-UP to configure a SDAP entity and a PDCP entity for each DU-DRB to be established for the UE.

[0108] The DU configures the RLC entity for the DU-DRB of the UE in accordance with the FiAP message, in operation 930. The co-located CU-UP configures the SDAP entity and the PDCP entity for the DU-DRB of the UE in accordance with the E1AP message, in operation 940. Then, the DU and the co-located CU-UP may use the DU- DRB(s) established for the UE to exchange data with the UE, in operation 950. Then, operations 900 may end.

[0109] Detailed descriptions of some other example operation flows of the computing platform DU are provided below. In some embodiments, the computing platform DU can use a S-DRB of a UE to securely transfer lower layer control messages with the UE.

[0110] FIG. 10 illustrates a flow diagram of example operations 1000 occurring in a computing platform hosting a DU of a gNB and a CU-UP of the gNB. Operations 1000 may be indicative of operations occurring in a computing platform hosting a DU of a gNB and a CU-UP of the gNB, as the computing platform uses a signaling-DRB (S-DRB) to securely transfer lower layer control messages, such as DCIs, MAC CEs, RLC control PDUs, and / or RRCL messages, with a UE served by the DU, the S-DRB being a DRB terminated at the CU-UP that is co-located with the DU on the same computing platform.

[0111] Operations 1000 begin with the DU (such as DU 420) indicating, to the CU-CP (such as CU-CP 480) of the gNB, its capability of supporting S-DRBs that terminate locally at the CU-UP (such as CU-UP 440) of the gNB, the CU-UP being co-located with the DU on the same computing platform, in operation 1010. For example, the DU may indicate such capability during an Fl Setup procedure with the CU-CP, as illustrated in FIG. 5C and described before. For another example, the DU may implicitly indicate such capability during an Fl Setup procedure with the CU-CP by indicating the co-located CU- UP, as illustrated in FIG. 5A and described before. For yet another example, the CU-UP co-located with the DU may implicitly indicate such capability of the DU during an El Setup procedure with the CU-CP by indicating that it is co-located with the DU, as illustrated in FIG. 5B and described before.

[0112] The DU and the co-located CU-UP can receive an FiAP and an EiAP message, respectively, from the CU-CP for establishing an S-DRB for a UE served by the DU, in operation 1020. For example, the DU may receive a UE Context Setup Request message, which is an FiAP message, from the CU-CP, the UE Context Setup Request message requesting the DU to configure an RLC entity for the S-DRB to be established for the UE. The RLC entity may be configured to operate at the AM to make the transfer of lowerFW 6000747PCT02 -27-layer control messages more reliable, as described before. For another example, the CU- UP co-located with the DU may receive a Bearer Context Setup Request message, which is an EtAP message, from the CU-CP, the Bearer Context Setup Request message requesting the CU-UP to configure a SDAP entity (such as SDAP entity 446) and a PDCP entity (such as PDCP entity 448) for the S-DRB to be established for the UE. For example, information included in the Bearer Context Setup Request message for configuring the SDAP entity for the S-DRB may include information indicating the S- DRB being associated with no valid PDU session of the UE, e.g., by not including any PDU session ID at all or by including a pre-defined null PDU session ID in the SDAP- config information element (IE) in the Bearer Context Setup Request message. For another example, the information included in the Bearer Context Setup Request message for configuring the SDAP entity for the S-DRB may include information indicating the QFI values assigned to DCIs (or the PHY entity as their source or destination), MAC CEs (or the MAC entity as their source or destination), RLC control PDUs (or the RLC entity as their source or destination), and RRCL messages (or the RRCL entity as their source or destination), respectively. For yet another example, information included in the Bearer Context Setup Request message for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to enable integrity protection. For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to enable out-of-order delivery. For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity not to perform cyphering, e.g., by configuring a null cyphering algorithm such as NEAo. For yet another example, the information for configuring the PDCP entity for the S-DRB may include information to configure the PDCP entity to disable header compression.

[0113] The DU can configure the RLC entity for the S-DRB of the UE in accordance with the FiAP message, in operation 1030. The co-located CU-UP can configure the SDAP entity and the PDCP entity for the S-DRB of the UE in accordance with the E1AP message, in operation 1040. The DU can generate a first lower layer control message to be sent to the UE securely, in operation 1050. For example, the first lower layer control message may include a DCI, a MAC CE, a RLC control PDU, or an RRCL message that is operation-critical. The DU then sends the first lower layer control message to the UE through the S-DRB, in operation 1060. For example, after the first lower layer control message (as a SDAP SDU) arrives from a corresponding lower layer protocol entity, SDAP entity 446 configured on CU-UP 340 for the S-DRB of the UE treats it as a SDAP SDU and adds a SDAP header to the SDAP SDU to produce a SDAP PDU, the QFI valueFW 6000747PCT02 -28-included in the SDAP header being the QFI value assigned to the lower layer protocol entity that has submitted the lower layer control message to SDAP entity 446 for the transmission. SDAP entity 446 then submits the produced SDAP PDU to PDCP entity 448 configured for the S-DRB, as a PDCP SDU. In some embodiments, PDCP entity 448 adds integrity protection to the PDCP SDU to produce the PDCP PDU and submits the PDCP PDU to the RLC entity configured for the S-DRB for the transmission over the S- DRB.

[0114] The CU-UP co-located with the DU can receive a second lower layer control message from the UE through the S-DRB, in operation 1070. For example, PDCP entity 448 configured on CU-UP 440 for the S-DRB of the UE may receive a PDCP PDU carrying the second lower layer control message, perform integrity verification on the PDCP PDU to produce a PDCP SDU, and consider the PDCP SDU being received successfully and being authentic and then forward the PDCP SDU to the SDAP entity configured for the S-DRB only if the integrity verification is successful. The SDAP entity configured on the CU-UP for the S-DRB of the UE can forward the second lower layer control message to a corresponding lower layer protocol entity for further processing, in operation 1080. For example, after the PDCP SDU arrives at SDAP entity 446 as a SDAP PDU, SDAP entity 446 removes the SDAP header from the SDAP PDU to produce a SDAP SDU, which is the second lower layer control message, and forwards the second lower layer control message to a lower layer protocol entity corresponding to the QFI value in the SDAP header of the SDAP PDU received, for further processing. Then, operations 1000 may end.

[0115] Detailed descriptions of some example operation flows of the CU-CP for configuring a DU-DRB are provided below.

[0116] FIG. 11 illustrates a flow diagram of example operations 1100 occurring in a CU-CP of a gNB. Operations 1100 may be indicative of operations occurring in a CU-CP of a gNB, as the CU-CP configures a DU-DRB between a UE served by a DU of the gNB and a CU-UP of the gNB that is co-located with the DU, the DU-DRB being a DRB that terminates at the CU-UP co-located with the DU, hence as if terminated at the DU.

[0117] Operations 1100 begin with a CU-CP (such as CU-CP 380 and 480) of a gNB receiving information indicating a DU (such as DU 320 and 420) of the gNB being capable of supporting DU-DRBs that terminate at a CU-UP (such as CU-UP 340) of the gNB, the CU-UP being co-located with the DU, in operation 1110. For example, the CU- CP may receive such indication during an Ft Setup procedure with the DU, as illustrated in FIG. 5C and described before. For another example, the CU-CP may receiveFW 6000747PCT02 -29-information indicating the co-located CU-UP during an Fl Setup procedure with the DU, as illustrated in FIG. 5A and described before, implicitly indicating such capability of the DU. For yet another example, the CU-CP may receive information indicating the colocated DU during an El Setup procedure with the CU-UP, as illustrated in FIG. 5B and described before, implicitly indicating such capability of the DU.

[0118] The CU-CP can receive UE capability information indicating a UE served by the gNB being capable of supporting DU-DRBs that terminate at the CU-UP co-located with the DU, the DU serving the UE, in operation 1120. For example, the CU-CP may receive the UE capability information when the UE establishes an RRC connection with the gNB. The CU-CP can send an EiAP message to the CU-UP co-located with the DU, sends an FiAP message to the DU, and sends an RRC message to the UE, to establish a DU-DRB for the UE, in operation 1130. For example, the EiAP message sent to the CU- UP may be a Bearer Context Setup Request message. The EiAP message may include information to configure a first SDAP entity and a first PDCP entity for the DU-DRB of the UE. For another example, the FiAP message sent to the DU may be a UE Context Setup Request message. The FiAP message may include information to configure a first RLC entity for the DU-DRB of the UE. For yet another example, the RRC message sent to the UE may be an RRCReconfiguration message. The RRC message may include information to configure a second SDAP entity, a second PDCP entity, and a second RLC entity at the UE for the DU-DRB, the second SDAP entity, the second PDCP entity, and the second RLC entity being the peer entities of the first SDAP entity, the first PDCP entity, and the first RLC entity, respectively. The RRC message sent to the UE may be encapsulated in the FiAP message sent to the DU and then is transmitted to the UE by the DU. Then, operations 1100 may end.

[0119] Detailed descriptions of some example operation flows of the CU-CP for supporting split RRC are provided below.

[0120] FIG. 12 illustrates a flow diagram of example operations 1200 occurring in a CU-CP of a gNB. Operations 1200 may be indicative of operations occurring in a CU-CP of a gNB, as the CU-CP supports split RRC, as described before.

[0121] Operations 1200 begin with the CU-CP (such as CU-CP 480) receiving information from a DU (such as DU 420) of the gNB indicating that the DU supports RRCL and S-DRBs that terminate locally at a CU-UP (such as CU-UP 440) co-located with the DU, in operation 1210. For example, the CU-CP may receive such information during the FiAP Setup procedure with the DU, as illustrated in FIG. 5A and described before. The CU-CP can receive UE capability information indicating that a UE served byFW 6000747PCT02 -30-the DU supports RRCL and an S-DRB that terminates at the CU-UP co-located with the DU, in operation 1220. For example, the CU-CP may receive the UE capability information from the UE in response to sending an RRC message, referred to as the UECapabilityEnquiry message, to the UE. For another example, the CU-CP may receive the UE capability information of the UE from the AMF in response to sending an NG application protocol (NGAP) message, referred to as the UE Radio Capability ID Mapping Request message, to the AMF, the NGAP message including a UE Radio Capability ID provided by the UE. The AMF may retrieve the UE capability information of the UE from a UE radio Capability Management Function (UCMF) with the UE Radio Capability ID of the UE provided by the CU-CP. The UCMF is a network function used for storing a directory of operator-assigned or manufacturer-assigned UE Radio Capability IDs and the corresponding UE capability information.

[0122] The CU-CP can send an EtAP message, e.g., a Bearer Context Setup Request message, to the CU-UP co-located with the DU to instruct the CU-UP to configure a first SDAP entity and a first PDCP entity for the S-DRB of the UE, in operation 1230. The CU- CP can send an FiAP message, e.g., a UE Context Setup Request message, to the DU to instruct the DU to configure a first RLC entity for the S-DRB of the UE and to configure a first RRCL entity for the UE, in operation 1240. The CU-CP sends an RRC message, e.g., an RRCReconfiguration message, to the UE to instruct the UE to configure a second SDAP entity, a second PDCP entity, and a second RLC entity at the UE to support the S- DRB of the UE and to configure a second RRCL entity at the UE to support split RRC, in operation 1250. The second SDAP entity, the second PDCP entity, the second RLC entity, and the second RRCL entity are the peer entities of the first SDAP entity, the first PDCP entity, the first RLC entity, and the first RRCL entity, respectively. The RRC message sent to the UE may be encapsulated in the FiAP message sent to the DU and then transmitted to the UE by the DU.

[0123] The CU-CP can send a fourth message to the first RRCL entity to configure a feature for the UE and conditions for executing the feature, in operation 1260. For example, the fourth message may be a new FiAP message, referred to as the CU-to-DU RRC Information Transfer message, as described before. When the DU receives the CU- to-DU RRC Information Transfer message over the Fi-C interface connecting to the CU- CP, it simply forwards the message to the co-located RRCL entity (such as RRCL entity 450) for further processing. For another example, the fourth message may be a UE Context Setup Request or a UE Context Modification Request message with a transparent container IE carrying the information designated to the RRCL entity for configuring the feature and the conditions for executing the feature. When the DUFW 6000747PCT02 -31-receives the UE Context Setup Request or UE Context Modification Request message over the Fi-C interface, it simply forwards the content in the transparent container IE to the co-located RRCL entity for further processing.

[0124] The CU-CP can receive a fifth message from the DU, the fifth message indicating an operation result or a status, in operation 1270. For example, the fifth message may be a new FiAP message, referred to as the DU-to-CU RRC Information Transfer message, as described before. For another example, the fifth message maybe a UE Context Setup Response or a UE Context Modification Response message with a transparent container IE carrying information indicating the operation result or the status. The operation result may be a result of executing the feature. The status may be a status of the DU, of the CU-UP co-located with the DU, or of the RRCL entity co-located with the DU. Then, operations 1200 may end.

[0125] Detailed descriptions of some example operation flows of the computing platform DU are provided below. In some embodiments, the computing platform DU can support split RRC.

[0126] FIG. 13 illustrates a flow diagram of example operations 1300 occurring in a computing platform hosting a DU of a gNB and a CU-UP of the gNB. Operations 1300 maybe indicative of operations occurring in a computing platform DU+ hosting a DU of a gNB and a CU-UP of the gNB, as the computing platform DU+ supports split RRC.

[0127] Operations 1300 begin with the DU (such as DU420) hosted at the computing platform (such as computing platform 410) indicating, to the CU-CP (such as CU-CP 480) of the gNB, its capabilities of supporting split RRC and supporting S-DRBs that terminate at a CU-UP (such as CU-UP 440) of the gNB, the CU-UP co-located with the DU on the same computing platform, in operation 1310. For example, the DU may indicate such capabilities to the CU-CP during the FiAP Setup procedure with the CU- CP, as illustrated in FIG. 5A and described before. The CU-UP co-located with the DU receives an EiAP message, e.g., a Bearer Context Setup Request message, from the CU- CP, the EiAP message instructing the CU-UP to configure a SDAP entity and a PDCP entity for the S-DRB of the UE, in operation 1320. The DU receives an FiAP message, e.g., a UE Context Setup Request message, from the CU-CP, the FiAP message instructing the DU to configure an RLC entity for the S-DRB of the UE and to configure an RRCL entity for the UE, in operation 1330.

[0128] The CU-UP co-located with the DU configures the SDAP entity (such as SDAP entity 446) and the PDCP entity (such as PDCP entity 448) for the S-DRB of the UE in accordance with the EiAP message, and the DU configures the RLC entity for the S-DRBFW 6000747PCT02 -32-of the UE and the RRCL entity (such as RRCL entity 450) for the UE in accordance with the FiAP message, in operation 1340. The DU receives a third message from the CU-CP, the third message including information to configure a feature for the UE and conditions for executing the feature, in operation 1350. For example, the third message may be a new FiAP message, referred to as the CU-to-DU RRC Information Transfer message, as described before. When the DU receives the CU-to-DU RRC Information Transfer message over the Fi-C interface connecting to the CU-CP, it simply forwards the message to the co-located RRCL entity (such as RRCL entity 450) for further processing. For another example, the third message may be a UE Context Setup Request or a UE Context Modification Request message with a transparent container IE carrying the information designated to the RRCL entity for configuring the feature and the conditions for executing the feature. When the DU receives the UE Context Setup Request or UE Context Modification Request message over the Fi-C interface, it simply forwards the content in the transparent container IE to the co-located RRCL entity for further processing.

[0129] The DU can send a fourth message to the UE through the S-DRB to execute the feature in response to the conditions for executing the feature being met, in operation 1360. For example, the DU may detect that the conditions for executing the feature are met based on radio measurements reported by the UE, radio measurements taken by the DU, a mobility event such as a handover of the UE, etc. For example, the fourth message sent to the UE may be an RRCL message generated by the DU in response to the conditions for executing the feature being met. For another example, the fourth message sent to the UE may be an RRC message generated by the RRC entity (such as RRC entity 482) in the CU-CP and provided to the RRCL entity in the third message received during operation 1350.

[0130] The DU can send a fifth message to the CU-CP, the fifth message indicating an operation result or a status, in operation 1370. For example, the fifth message maybe a new FiAP message, referred to as the DU-to-CU RRC Information Transfer message, as described before. For another example, the fifth message may be a UE Context Setup Response or a UE Context Modification Response message with a transparent container IE carrying information indicating the operation result or the status. The operation result may be a result of executing the feature. The status may be a status of the DU, of the CU- UP co-located with the DU, or of the RRCL entity co-located with the DU. Then, operations 1300 may end.

[0131] It is understood that steps or operations shown in the methods, the signaling exchange diagrams, or the flow diagrams described in this disclosure (e.g., as described with respect to FIGS. 5A-5C and 6-13) are not exhaustive and that other operations canFW 6000747PCT02 -33-be performed as well before, after, or between any of the illustrated operations. Further, some of the steps or operations may be omitted, performed simultaneously, or in a different order than shown in those figures.

[0132] According to some aspects of this application, a method is provided. The method includes receiving, by a first network device (e.g., the computing platform 310 in FIG. 3A or the computing platform 410 in FIG. 4) of an access network, a first message (e.g., the Bearer Context Setup Request message described in step 604 of FIG. 6) from a second network device (e.g., the CU-CP 380 in FIG. 3A, the CU-CP 480 in FIG. 4, or the CU-CP in FIGS. 5A-5C and 6) of the access network. The first message can indicate a configuration (e.g., the PDCP configuration information described in step 604 of FIG. 6) of a PDCP entity in the first network device.

[0133] The method further includes transmitting, by the first network device, a second message (e.g., the RRCReconfiguration message described in step 606 of FIG. 6) to a terminal device (e.g., the UE in FIG. 6). The second message can indicate a configuration of a DRB (e.g., a DU-DRB or a S-DRB), and the PDCP entity in the first network device can be configured to perform PDCP processing for the DRB.

[0134] The method further includes communicating, by the first network device, data with the terminal device via the DRB (e.g., as described with reference to step 609 in FIG. 6).[Q135] In some embodiments, communicating, by the first network device, data with the terminal device via the DRB includes: communicating, by the first network device, lower layer control information via the DRB. For example, the lower layer control information can include one or more of: a DCI, a MAC-CE, or an RLC control PDU.

[0136] In some embodiments, communicating, by the first network device, lower layer control information via the DRB includes: performing at least one of ciphering or integrity protection, for the lower layer control information transmitted via the DRB.

[0137] In some embodiments, the first network device includes a DU (e.g., the DU 320 in FIG. 3A, the DU 420 in FIG. 4, or the DU in FIGS. 5A-5C and 6) of a base station of the access network and a first CU (e.g., the CU-UP 340 in FIG. 3A, the CU-UP 440 in FIG. 4, or the local CU-UP in FIGS. 5A-5C and 6) of the base station. The second network device can include a second CU (e.g., the CU-CP 380 in FIG. 3A, the CU-CP 480 in FIG.4, or the CU-CP in FIGS. 5A-5C and 6) of the base station.

[0138] In some embodiments, the first message further indicates a configuration (e.g., the SDAP configuration information described in step 604 of FIG. 6) of a SDAPFW 6000747PCT02 -34-entity in the first network device, and the second message further indicates at least one QoS flow mapped to the DRB.

[0139] In some embodiments, the second message includes a valid PDU session identifier (ID) associated with the DRB, and the DRB (e.g., the DU-DRB described in operations 700 of FIG. 7) is configured to carry user-plane data.

[0140] In some embodiments, the second message excludes a valid PDU session ID associated with the DRB, and the DRB (e.g., the S-DRB described in operations 800 of FIG. 8) is configured to exclude user-plane data.

[0141] In some embodiments, the second message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

[0142] In some embodiments, the first network device includes a first RRC entity (e.g., RRCL entity 450 in FIG. 4), and the first RRC entity is configured to process the lower layer control information transmitted via the DRB.

[0143] In some embodiments, the second network device includes a second RRC entity (e.g., RRC entity 482 in FIG. 4), and the second RRC entity is configured to perform one or more of: RRC connection control, an AS security function, or a NAS transmission function.

[0144] In some embodiments, the first network device includes a UPF (e.g., UPF 330 in FIG. 3A or UPF 430 in FIG. 4), and the UPF in the first network device is configured to forward user plane data carried by the DRB to a corresponding destination.

[0145] In some embodiments, the method further includes transmitting, by the first network device, a third message (e.g., the Fl Setup Request message or gNB-DU Configuration Update message in FIG. 5A or the gNB-CU-UP El Setup Request message in FIG. 5B) to the second network device. The third message can indicate a first CU of a base station of the access network, and the second network device includes a second CU of the base station.

[0146] In some embodiments, the method further includes transmitting, by the first network device, a fourth message (e.g., the Ft Setup Request message or the gNB-DU Configuration Update message in step 521 of FIG. 5C) to the second network device. The fourth message can indicate support for a first CU of a base station of the access network, and the second network device can include a second CU of the base station. The method can further include receiving, by the first network device, a fifth message (e.g., the Fl Setup Response message or the gNB-DU Configuration Update Acknowledge message inFW 6000747PCT02 -35-step 522 of FIG. 5C) from the second network device. The fifth message can indicate a configuration of the first CU in the first network device.

[0147] According to some aspects of this application, a method is provided. The method includes receiving, by a terminal device (e.g., the UE in FIG. 6), a message (e.g., the RRCReconfiguration message described in step 606 of FIG. 6) from a network device (e.g., the computing platform 310 in FIG. 3A or the computing platform 410 in FIG. 4) of an access network. The network device can include a DU (e.g., the DU 320 in FIG. 3A, the DU 420 in FIG. 4, or the DU in FIGS. 5A-5C and 6) of a base station of the access network and a first CU (e.g., the CU-UP 340 in FIG. 3A, the CU-UP 440 in FIG. 4, or the local CU-UP in FIGS. 5A-5C and 6) of the base station. The message can indicate a configuration of a DRB (e.g., a DU-DRB or a S-DRB). The DRB can be configured to be processed by a PDCP entity in the first CU of the network device. The method further includes communicating, by the terminal device, data with the network device via the DRB.

[0148] In some embodiments, communicating, by the terminal device, data with the network device via the DRB includes communicating, by the terminal device, lower layer control information via the DRB. For example, the lower layer control information can include one or more of: a DCI, a MAC-CE, or an RLC control PDU.

[0149] In some embodiments, the message includes a valid PDU session ID associated with the DRB, and the DRB (e.g., the DU-DRB described in operations 700 of FIG. 7) is configured to carry user-plane data.

[0150] In some embodiments, the message excludes a valid PDU session ID associated with the DRB, and the DRB (e.g., the S-DRB described in operations 800 of FIG. 8) is configured to exclude user-plane data.

[0151] In some embodiments, the message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

[0152] According to some aspects of this application, a method is provided. The method includes transmitting, by a first network device (e.g., the CU-CP 380 in FIG. 3A, the CU-CP 480 in FIG. 4, or the CU-CP in FIGS. 5A-5C and 6) of an access network, a first message (e.g., the Fl Setup Response message or the gNB-DU Configuration Update Acknowledge message in step 522 of FIG. 5C) to a second network device (e.g., the computing platform 310 in FIG. 3A or the computing platform 410 in FIG. 4) of the access network. The first message can indicate a configuration of a first CU (e.g., the CU- UP 340 in FIG. 3A, the CU-UP 440 in FIG. 4, or the local CU-UP in FIGS. 5A-5C and 6)FW 6000747PCT02 -36-of a base station of the access network in the second network device. The first network device can include a second CU (e.g., the CU-UP 370 or the CU-CP 380 in FIG. 3A, the CU-UP 470 or the CU-CP 480 in FIG. 4, or the CU-CP in FIGS. 5A-5C and 6) of the base station.[o t53] The method further includes transmitting, by the first network device, a second message (e.g., the Bearer Context Setup Request message described in step 604 of FIG. 6) to the second network device. The second message can indicate a configuration (e.g., the PDCP configuration information described in step 604 of FIG. 6) of a PDCP entity in the first CU in the second network device.

[0154] In some embodiments, the second network device includes a first RRC entity (e.g., RRCL entity 450 in FIG. 4).

[0155] In some embodiments, the first network device includes a second RRC entity (e.g., RRC entity 482 in FIG. 4), and the second RRC entity is configured to perform one or more of: RRC connection control, an AS security function, or a NAS transmission function.

[0156] According to some aspects of this application, a method is provided. The method can be implemented by a communication device. The method includes: receiving, by the communication device, a first message from a CU-CP of a gNB, the first message instructing the communication device to establish a DRB with a CU-UP of the gNB, the CU-UP being co-located with a DU of the gNB, the communication device being served by the DU; establishing, by the communication device, the DRB with the CU-UP co-located with the DU in accordance with the first message; and using, by the communication device, the DRB for securely transferring SDUs with the CU-UP.

[0157] In some embodiments, the first message includes no valid PDU session ID to be associated with the DRB. The method further includes: generating, by the communication device, a first lower layer control message to be sent to the DU securely; and transmitting, by the communication device, the first lower layer control message, as an SDU of the SDUs, over the DRB to the DU.

[0158] In some embodiments, the first lower layer control message includes one of a DCI, a MAC-CE, or an RLC control PDU.

[0159] In some embodiments, the first message includes information indicating QoS flow ID (QFI) values uniquely assigned to lower layer protocol entities, respectively. The method further includes: adding, by the communication device, a PDU header (e.g., a SDAP header or a PDCP header) to the first lower layer control message to produce aFW 6000747PCT02 -37-PDU (e.g., a SDAP PDU or a PDCP PDU), a QFI value included in the PDU header being equal to a QFI value assigned to a lower layer protocol entity of the lower layer protocol entities that had generated the first low layer control message; applying, by the communication device, integrity protection on the PDU to produce a protected PDU; and submitting, by the communication device, the protected PDU to lower layers for transmission of the first lower layer control message over the DRB to the DU.

[0160] In some embodiments, the method further includes: receiving, by the communication device, a second PDU carrying a second lower layer control message from the DU through the DRB; and forwarding, by the communication device, the second lower layer control message to a corresponding lower layer protocol entity for further processing based on the information in the first message indicating the QFI values uniquely assigned to the lower layer protocol entities and based on the QFI value included in a second PDU header of the second PDU.

[0161] In some embodiments, the second lower layer control message includes one of a second DCI, a second MAC CE, or a second RLC control PDU.

[0162] In some embodiments, the first message further includes information instructing the communication device to enable an integrity protection function on the DRB. The method further includes enabling, by the communication device, the integrity protection function on the DRB in accordance with the first message.

[0163] In some embodiments, the first message further includes information instructing the communication device to disable a cyphering function on the DRB. The method further includes disabling, by the communication device, the cyphering function on the DRB in accordance with the first message.

[0164] In some embodiments, the information instructs the communication device to disable the cyphering function on the DRB by indicating a null cyphering algorithm.

[0165] In some embodiments, the first message further includes information instructing the communication device to disable a header compression function on the DRB. The method further includes disabling, by the communication device, the header compression function on the DRB in accordance with the first message.

[0166] In some embodiments, the information instructs the communication device to disable the header compression function on the DRB by indicating a null header compression algorithm.

[0167] FIG. 14 illustrates an example communications system 1400. Communications system 1400 includes an access node 1410 serving user equipments (UEs) with coverageFW 6000747PCT02 -38-1401, such as UEs 1420. In a first operating mode, communications to and from a UE passes through access node 1410 with a coverage area 1401. The access node 1410 is connected to a backhaul network 1415 for connecting to the internet, operations and management, and so forth. In a second operating mode, communications to and from a UE do not pass through access node 1410. However, access node 1410 typically allocates resources used by the UE to communicate when specific conditions are met. Communications between a pair of UEs 1420 can use a sidelink connection (shown as two separate one-way connections 1425). In FIG. 14, the sideline communication is occurring between two UEs operating inside of coverage area 1401. However, sidelink communications, in general, can occur when UEs 1420 are both outside coverage area 1401, both inside coverage area 1401, or one inside and the other outside coverage area 1401. Communication between a UE and access node pair occur over uni-directional communication links, where the communication links between the UE and the access node are referred to as uplinks 1430, and the communication links between the access node and the UE is referred to as downlinks 1435.

[0168] Access nodes may also be commonly referred to as Node Bs, evolved Node Bs (eNBs), next generation (NG) Node Bs (gNBs), master eNBs (MeNBs), secondary eNBs (SeNBs), master gNBs (MgNBs), secondary gNBs (SgNBs), network controllers, control nodes, base stations, access points, transmission points (TPs), transmission-reception points (TRPs), cells, carriers, macro cells, femtocells, pico cells, and so on, while UEs may also be commonly referred to as mobile stations, mobiles, terminals, users, subscribers, stations, and the like. Access nodes may provide wireless access in accordance with one or more wireless communication protocols, e.g., the Third Generation Partnership Project (3GPP) long term evolution (LTE), LTE advanced (LTE- A), 5G, 5G LTE, 5G NR, sixth generation (6G), High Speed Packet Access (HSPA), the IEEE 802.11 family of standards, such as 802.na / b / g / n / ac / ad / ax / ay / be, etc. While it is understood that communications systems may employ multiple access nodes capable of communicating with a number of UEs, only one access node and two UEs are illustrated for simplicity.

[0169] FIG. 15 illustrates an example communication system 1500. In general, the system 1500 enables multiple wireless or wired users to transmit and receive data and other content. The system 1500 may implement one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FD A (OFDMA), single-carrier FDMA (SC-FDMA), or non-orthogonal multiple access (NOMA).FW 6000747PCT02 -39-

[0170] In this example, the communication system 1500 includes electronic devices (ED) 15103-15100, radio access networks (RANs) 15203-1520!), a core network 1530, a public switched telephone network (PSTN) 1540, the Internet 1550, and other networks 1560. While certain numbers of these components or elements are shown in FIG. 15, any number of these components or elements may be included in the system 1500.

[0171] The EDs 15103-15100 are configured to operate or communicate in the system 1500. For example, the EDs 15103-15100 are configured to transmit or receive via wireless or wired communication channels. Each ED 15103-15100 represents any suitable end user device and may include such devices (or may be referred to) as a user equipment or device (UE), wireless transmit or receive unit (WTRU), mobile station, fixed or mobile subscriber unit, cellular telephone, personal digital assistant (PDA), smartphone, laptop, computer, touchpad, wireless sensor, or consumer electronics device.

[0172] The RANs 15203-1520!) here include base stations I57oa-i57ob, respectively. Each base station 15703-1570]) is configured to wirelessly interface with one or more of the EDs 15103-15100 to enable access to the core network 1530, the PSTN 1540, the Internet 1550, or the other networks 1560. For example, the base stations 15703-1570!) may include (or be) one or more of several well-known devices, such as a base transceiver station (BTS), a Node-B (NodeB), an evolved NodeB (eNB), a Next Generation (NG) NodeB (gNB), a gNB centralized unit (gNB-CU), a gNB distributed unit (gNB-DU), a Home NodeB, a Home eNodeB, a site controller, an access point (AP), or a wireless router. The EDs 15103-15100 are configured to interface and communicate with the Internet 1550 and may access the core network 1530, the PSTN 1540, or the other networks 1560.

[0173] In the embodiment shown in FIG. 15, the base station 1570a forms part of the RAN 1520a, which may include other base stations, elements, or devices. Also, the base station 1570b forms part of the RAN 1520b, which may include other base stations, elements, or devices. Each base station I57oa-i57ob operates to transmit or receive wireless signals within a particular geographic region or area, sometimes referred to as a “cell.” In some embodiments, multiple-input multiple-output (MIMO) technology may be employed having multiple transceivers for each cell.

[0174] The base stations i57oa-i57ob communicate with one or more of the EDs 15103-15100 over one or more air interfaces 1590 using wireless communication links. The air interfaces 1590 may utilize any suitable radio access technology.FW 6000747PCT02 -40-

[0175] It is contemplated that the system 1500 may use multiple channel access functionality, including such schemes as described above. In particular embodiments, the base stations and EDs implement 5G New Radio (NR), LTE, LTE-A, or LTE-B. Of course, other multiple access schemes and wireless protocols may be utilized.

[0176] The RANs I52oa-i52ob are in communication with the core network 1530 to provide the EDs 1510a- 1510c with voice, data, application, Voice over Internet Protocol (VoIP), or other services. Understandably, the RANs I52oa-i52ob or the core network 1530 may be in direct or indirect communication with one or more other RANs (not shown). The core network 1530 may also serve as a gateway access for other networks (such as the PSTN 1540, the Internet 1550, and the other networks 1560). In addition, some or all of the EDs I5ioa-i5ioc may include functionality for communicating with different wireless networks over different wireless links using different wireless technologies or protocols. Instead of wireless communication (or in addition thereto), the EDs may communicate via wired communication channels to a service provider or switch (not shown), and to the Internet 1550.

[0177] Although FIG. 15 illustrates one example of a communication system, various changes maybe made to FIG. 15. For example, the communication system 1500 could include any number of EDs, base stations, networks, or other components in any suitable configuration.

[0178] FIGS. 16A and 16B illustrate example devices that may implement the methods and teachings according to this disclosure. In particular, FIG. 16A illustrates an example ED 1610, and FIG. 16B illustrates an example base station 1670. These components could be used in the system 1500 or in any other suitable system.

[0179] As shown in FIG. 16A, the ED 1610 includes at least one processing unit 1600. The processing unit 1600 implements various processing operations of the ED 1610. For example, the processing unit 1600 could perform signal coding, data processing, power control, input / output processing, or any other functionality enabling the ED 1610 to operate in the system 1500. The processing unit 1600 also supports the methods and teachings described in more detail above. Each processing unit 1600 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1600 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.

[0180] The ED 1610 also includes at least one transceiver 1602. The transceiver 1602 is configured to modulate data or other content for transmission by at least one antennaFW 6000747PCT02 -41-or NIC (Network Interface Controller) 1604. The transceiver 1602 is also configured to demodulate data or other content received by the at least one antenna 1604. Each transceiver 1602 includes any suitable structure for generating signals for wireless or wired transmission or processing signals received wirelessly or by wire. Each antenna 1604 includes any suitable structure for transmitting or receiving wireless or wired signals. One or multiple transceivers 1602 could be used in the ED 1610, and one or multiple antennas 1604 could be used in the ED 1610. Although shown as a single functional unit, a transceiver 1602 could also be implemented using at least one transmitter and at least one separate receiver.

[0181] The ED 1610 further includes one or more input / output devices 1606 or interfaces (such as a wired interface to the Internet 1550). The input / output devices 1606 facilitate interaction with a user or other devices (network communications) in the network. Each input / output device 1606 includes any suitable structure for providing information to or receiving information from a user, such as a speaker, microphone, keypad, keyboard, display, or touch screen, including network interface communications.

[0182] In addition, the ED 1610 includes at least one memory 1608. The memory 1608 stores instructions and data used, generated, or collected by the ED 1610. For example, the memory 1608 could store software or firmware instructions executed by the processing unit(s) 1600 and data used to reduce or eliminate interference in incoming signals. Each memory 1608 includes any suitable volatile or non-volatile storage and retrieval device(s). Any suitable type of memory may be used, such as random access memory (RAM), read only memory (ROM), hard disk, optical disc, subscriber identity module (SIM) card, memory stick, secure digital (SD) memory card, and the like.

[0183] As shown in FIG. 16B, the base station 1670 includes at least one processing unit 1650, at least one transceiver 1652, which includes functionality for a transmitter and a receiver, one or more antennas 1656, at least one memory 1658, and one or more input / output devices or interfaces 1666. A scheduler, which would be understood by one skilled in the art, is coupled to the processing unit 1650. The scheduler could be included within or operated separately from the base station 1670. The processing unit 1650 implements various processing operations of the base station 1670, such as signal coding, data processing, power control, input / output processing, or any other functionality. The processing unit 1650 can also support the methods and teachings described in more detail above. Each processing unit 1650 includes any suitable processing or computing device configured to perform one or more operations. Each processing unit 1650 could, for example, include a microprocessor, microcontroller, digital signal processor, field programmable gate array, or application specific integrated circuit.FW 6000747PCT02 -42-

[0184] Each transceiver 1652 includes any suitable structure for generating signals for wireless or wired transmission to one or more EDs or other devices. Each transceiver 1652 further includes any suitable structure for processing signals received wirelessly or by wire from one or more EDs or other devices. Although shown combined as a transceiver 1652, a transmitter and a receiver could be separate components. Each antenna 1656 includes any suitable structure for transmitting or receiving wireless or wired signals. While a common antenna 1656 is shown here as being coupled to the transceiver 1652, one or more antennas 1656 could be coupled to the transceiver(s) 1652, allowing separate antennas 1656 to be coupled to the transmitter and the receiver if equipped as separate components. Each memory 1658 includes any suitable volatile or non-volatile storage and retrieval device(s). Each input / output device 1666 facilitates interaction with a user or other devices (network communications) in the network. Each input / output device 1666 includes any suitable structure for providing information to or receiving / providing information from a user, including network interface communications.

[0185] FIG. 17 is a block diagram of a computing system 1700 that maybe used for implementing the devices and methods disclosed herein. For example, the computing system can be any entity of UE, access network (AN), mobility management (MM), session management (SM), user plane gateway (UPGW), or access stratum (AS). Specific devices may utilize all of the components shown or only a subset of the components, and levels of integration may vary from device to device. Furthermore, a device may contain multiple instances of a component, such as multiple processing units, processors, memories, transmitters, receivers, etc. The computing system 1700 includes a processing unit 1702. The processing unit includes a central processing unit (CPU) 1714, memory 1708, and may further include a mass storage device 1704, a video adapter 1710, and an I / O interface 1712 connected to a bus 1720.

[0186] The bus 1720 may be one or more of any type of several bus architectures including a memory bus or memory controller, a peripheral bus, or a video bus. The CPU 1714 may comprise any type of electronic data processor. The memory 1708 may comprise any type of non-transitory system memory such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous DRAM (SDRAM), read-only memory (ROM), or a combination thereof. In an embodiment, the memory 1708 may include ROM for use at boot-up, and DRAM for program and data storage for use while executing programs.

[0187] The mass storage 1704 may comprise any type of non-transitory storage device configured to store data, programs, and other information and to make the data,FW 6000747PCT02 -43-programs, and other information accessible via the bus 1720. The mass storage 1704 may comprise, for example, one or more of a solid state drive, hard disk drive, a magnetic disk drive, or an optical disk drive.

[0188] The video adapter 1710 and the I / O interface 1712 provide interfaces to couple external input and output devices to the processing unit 1702. As illustrated, examples of input and output devices include a display 1718 coupled to the video adapter 1710 and a mouse, keyboard, or printer 1716 coupled to the I / O interface 1712. Other devices may be coupled to the processing unit 1702, and additional or fewer interface cards may be utilized. For example, a serial interface such as Universal Serial Bus (USB) (not shown) may be used to provide an interface for an external device.

[0189] The processing unit 1702 also includes one or more network interfaces 1706, which may comprise wired links, such as an Ethernet cable, or wireless links to access nodes or different networks. The network interfaces 1706 allow the processing unit 1702 to communicate with remote units via the networks. For example, the network interfaces 1706 may provide wireless communication via one or more transmitters / transmit antennas and one or more receivers / receive antennas. In an embodiment, the processing unit 1702 is coupled to a local-area network 1722 or a wide-area network for data processing and communications with remote devices, such as other processing units, the Internet, or remote storage facilities.

[0190] It should be appreciated that one or more steps of the embodiment methods provided herein maybe performed by corresponding units or modules. For example, a signal may be transmitted by a transmitting unit or a transmitting module. A signal may be received by a receiving unit or a receiving module. A signal may be processed by a processing unit or a processing module. Other steps may be performed by a performing unit or module, a generating unit or module, an obtaining unit or module, a setting unit or module, an adjusting unit or module, an increasing unit or module, a decreasing unit or module, a determining unit or module, a modifying unit or module, a reducing unit or module, a removing unit or module, or a selecting unit or module. The respective units or modules may be hardware, software, or a combination thereof. For instance, one or more of the units or modules may be an integrated circuit, such as field programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0191] Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodimentsFW 6000747PCT02 -44-described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

[0192] Features disclosed herein in the context of any particular embodiments may also or instead be implemented in other embodiments. Method embodiments, for example, may also or instead be implemented in apparatus, system, and / or computer program product embodiments. In addition, although embodiments are described primarily in the context of methods and apparatus, other implementations are also contemplated, for example, as instructions stored on one or more non-transitory computer-readable media. Such media could store programming or instructions to perform any of various methods consistent with the present disclosure.FW 6000747PCT02 -45-

Claims

WHAT IS CLAIMED IS:

1. A method comprising: receiving, by a first network device of an access network, a first message from a second network device of the access network, wherein the first message indicates a configuration of a packet data convergence protocol (PDCP) entity in the first network device; transmitting, by the first network device, a second message to a terminal device, wherein the second message indicates a configuration of a data radio bearer (DRB) corresponding to the PDCP entity; and communicating, by the first network device, data with the terminal device via the DRB.

2. The method of claim 1, wherein communicating, by the first network device, data with the terminal device via the DRB comprises: communicating, by the first network device, lower layer control information via the DRB, wherein the lower layer control information comprises one or more of: a downlink control information (DCI), a media access control (MAC) control element (CE), or a radio link control (RLC) control protocol data unit (PDU).

3. The method of claim 2, wherein the one or more of the DCI, the MAC CE, or the RLC control PDU are designated to one or more corresponding lower layer protocol entities of the terminal device, respectively, wherein the first message includes information indicating quality of service (QoS) flow identifier (ID) (QFI) values uniquely assigned to the one or more corresponding lower layer protocol entities, respectively, and wherein the method further comprises: adding, by the first network device, a PDU header to a first lower layer control message to produce a PDU, a QFI value included in the PDU header being equal to a QFI value assigned to a lower layer protocol entity of the one or more corresponding lower layer protocol entities that had generated the first lower layer control message; applying, by the first network device, integrity protection on the PDU to produce a protected PDU; and submitting, by the first network device, the protected PDU to lower layers for transmission of the first lower layer control message over the DRB to the terminal device.

4. The method of claim 3, further comprising: receiving, by the first network device, a second PDU carrying a second lower layer control message from the terminal device through the DRB; and selecting, by the first network device, a corresponding lower layer protocol entityFW 6000747PCT02 -46-of the first network device to further process the second lower layer control message to based on the information in the first message indicating the QFI values uniquely assigned to the one or more corresponding lower layer protocol entities and based on the QFI value included in a second PDU header of the second PDU.

5. The method of claim 2, wherein communicating, by the first network device, lower layer control information via the DRB comprises: performing at least one of ciphering or integrity protection, for the lower layer control information transmitted via the DRB.

6. The method of any of claims 1 to 5, wherein the first network device comprises a distributed unit (DU) of a base station of the access network and a first centralized unit (CU) of the base station, and the second network device comprises a second CU of the base station.

7. The method of any of claims 1 to 6, wherein the first message further indicates a configuration of a service data adaptation protocol (SDAP) entity in the first network device, and the second message further indicates at least one quality of service (QoS) flow mapped to the DRB.

8. The method of any of claims 1 to 7, wherein the second message includes a valid protocol data unit (PDU) session identifier (ID) associated with the DRB, and the DRB is configured to carry user-plane data.

9. The method of any of claims 1 to 7, wherein the second message excludes a valid protocol data unit (PDU) session identifier (ID) associated with the DRB, and the DRB is configured to exclude user-plane data.

10. The method of any of claims 1 to 9, wherein the second message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

11. The method of claim 2, wherein the first network device comprises a first radio resource control (RRC) entity, and the first RRC entity is configured to process the lower layer control information transmitted via the DRB.

12. The method of claim 11, wherein the second network device comprises a second RRC entity, and the second RRC entity is configured to perform one or more of: RRCFW 6000747PCT02 -47-connection control, an access stratum (AS) security function, or a non-access stratum (NAS) transmission function.

13. The method of any of claims 1 to 12, wherein the first network device comprises a user plane function (UPF), and the UPF in the first network device is configured to forward user plane data carried by the DRB to a corresponding destination.

14. The method of any of claims 1 to 13, further comprising: transmitting, by the first network device, a third message to the second network device, wherein the third message indicates a first centralized unit (CU) of a base station of the access network, and the second network device comprises a second CU of the base station.

15. The method of any of claims 1 to 13, further comprising: transmitting, by the first network device, a fourth message to the second network device, wherein the fourth message indicates support for a first centralized unit (CU) of a base station of the access network, and the second network device comprises a second CU of the base station; and receiving, by the first network device, a fifth message from the second network device, wherein the fifth message indicates a configuration of the first CU in the first network device.

16. A method comprising: receiving, by a terminal device, a message from a network device of an access network, wherein the network device comprises a distributed unit (DU) of a base station of the access network and a first centralized unit (CU) of the base station, the message indicates a configuration of a data radio bearer (DRB) corresponding to a packet data convergence protocol (PDCP) entity in the first CU of the network device; and communicating, by the terminal device, data with the network device via the DRB.

17. The method of claim 16, wherein communicating, by the terminal device, data with the network device via the DRB comprises: communicating, by the terminal device, lower layer control information via the DRB, wherein the lower layer control information comprises one or more of: a downlink control information (DCI), a media access control (MAC) control element (CE), or a radio link control (RLC) control protocol data unit (PDU).FW 6000747PCT02 -48-18. The method of any of claims 16 to 17, wherein the message includes a valid protocol data unit (PDU) session identifier (ID) associated with the DRB, and the DRB is configured to carry user-plane data.

19. The method of any of claims 16 to 17, wherein the message excludes a valid protocol data unit (PDU) session identifier (ID) associated with the DRB, and the DRB is configured to exclude user-plane data.

20. The method of any of claims 16 to 19, wherein the message instructs the terminal device to enable or disable one or more of: an integrity protection function on the DRB, a ciphering function on the DRB, or a header compression function on the DRB.

21. A method comprising: transmitting, by a first network device of an access network, a first message to a second network device of the access network, wherein the first message indicates a configuration of a first centralized unit (CU) of a base station of the access network in the second network device, and the first network device comprises a second CU of the base station; and transmitting, by the first network device, a second message to the second network device, wherein the second message indicates a configuration of a packet data convergence protocol (PDCP) entity in the first CU in the second network device.

22. The method of claim 21, wherein the second network device comprises a first radio resource control (RRC) entity, the first network device comprises a second RRC entity, and the second RRC entity is configured to perform one or more of: RRC connection control, an access stratum (AS) security function, or a non-access stratum (NAS) transmission function.

23. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 1 to 15.

24. A non -transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 1 to 15.FW 6000747PCT02 -49-25. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 16 to 20.

26. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 16 to 20.

27. An apparatus, comprising: at least one processor; and at least one memory coupled to the at least one processor, wherein the at least one memory stores programming instructions that, when executed by the at least one processor, cause the apparatus to perform a method according to any of claims 21 to 22.

28. A non-transitory computer readable storage medium storing programming instructions that, when executed by at least one processor, cause an apparatus to perform a method according to any of claims 21 to 22.FW 6000747PCT02 -SO-

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