Managing PDCP operations in serving cell change scenarios

Abstract

A node of a radio access network (RAN): transmits, to a user equipment (UE) in a first cell and communicating with the RAN using a radio bearer, a message including a configuration for performing a serving cell change to a second cell after an activation command, including avoiding including a packet data convergence protocol (PDCP) reestablishment indication in the message; and after the transmission of the message comprising the configuration, transmitting an activation command to the UE for performing a serving cell change to the second cell according to the configuration and without reestablishing a PDCP entity of the UE for the radio bearer.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of the filing date of provisional U.S. patent application No. 63 / 377,713, entitled “Managing PDCP Operation in a Serving Cell Change Scenario,” filed on September 29, 2022. The entire contents of the provisional application are hereby expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates to wireless communications, and more particularly, to managing data communications in a serving cell change of a user equipment (UE) and a decomposed base station. Background Art

[0004] This background description is provided for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors (to the extent that it is described in this background section) and aspects of this description that might not be identified as prior art at the time of filing are neither explicitly nor implicitly admitted to be prior art to the present disclosure.

[0005] In a telecommunications system, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as transmission, encryption, integrity protection, etc. of user plane data. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) radio interface (see 3GPP specification TS 36.323) and New Radio (NR) (see 3GPP specification TS 38.323) provides sequencing of protocol data units (PDUs) in the uplink direction (from a user device (also referred to as user equipment (UE)) to a base station) and in the downlink direction (from a base station to a UE). In addition, the PDCP sublayer provides signaling radio bearers (SRBs) and data radio bearers (DRBs) to the radio resource control (RRC) sublayer. Generally speaking, in some scenarios, the UE and the base station use SRBs to exchange RRC messages and non-access stratum (NAS) messages. In other scenarios, the UE and the base station use DRBs to transmit data on the user plane.

[0006] The UE uses several types of SRBs and DRBs depending on the scenario. When operating with dual connectivity (DC), the cell associated with the base station operating as a master node (MN) defines a master cell group (MCG), and the cell associated with the base station operating as a secondary node (SN) defines a secondary cell group (SCG). SRB1 resources carry RRC messages including NAS messages on a dedicated control channel (DCCH) in some cases, and SRB2 resources support RRC messages including logged measurement information or NAS messages also on the DCCH but with a lower priority than SRB1 resources. More generally, SRB1 and SRB2 resources allow the UE and MN to exchange RRC messages related to the MN and embed RRC messages related to the SN, and can be referred to as MCG SRBs. SRB3 resources allow the UE and SN to exchange RRC messages related to the SN, and can be referred to as SCG SRBs. Split SRBs allow the UE to exchange RRC messages directly with the MN via the lower layer resources of the MN and SN. In addition, a DRB using only the lower layer resources of the MN may be referred to as an MCG DRB, a DRB using only the lower layer resources of the SN may be referred to as an SCG DRB, and a DRB using the lower layer resources of both the MCG and SCG may be referred to as a split DRB.

[0007] In some scenarios, the UE concurrently utilizes the resources of multiple radio access network (RAN) nodes (e.g., components of a base station or a distributed base station) interconnected by backhaul. When such network nodes support different radio access technologies (RATs), this type of connectivity is referred to as multi-radio dual connectivity (MR-DC). When the UE operates with MR-DC, one base station operates as a master node (MN) covering a primary cell (PCell), and another base station operates as a secondary node (SN) covering a primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and with the SN (via the PSCell). In other scenarios, the UE utilizes the resources of one base station at a time. A base station and / or UE determines that the UE should establish a radio connection with another base station. For example, a base station determines to switch the UE to a second base station and initiates a switching process.

[0008] When a UE moves from the coverage area of ​​one cell in the RAN to another cell, at some point a serving cell change will be performed for the UE. To perform the serving cell change, the RAN configures the UE to send layer 3 (L3) measurement results. Based on the L3 measurement results received from the UE, the RAN sends an RRC reconfiguration message configured with synchronized reconfiguration (e.g., the RRC reconfiguration message includes a ReconfigurationWithSync IE) for a change in a serving cell (e.g., a PCell or a PSCell). In the case where the UE operates with carrier aggregation (CA) of at least one secondary cell (SCell) with a PCell or a PSCell, the RAN must release the at least one SCell due to the change of the PCell or the PSCell. The serving cell change involves a complete L2 (and L1) reset, resulting in longer latency, greater overhead, and longer interruption time. Therefore, it is expected that new mobile technologies will be developed to reduce the latency and overhead of fast serving cell changes. However, it is unclear how to develop and implement fast serving cell changes. Summary of the invention

[0009] An example embodiment of the technology of the present disclosure is a configuration method implemented in a node of a RAN. The method includes: sending a message including a configuration for performing a serving cell change to a second cell after an activation command to a UE in a first cell and communicating with the RAN using a radio bearer, including avoiding including a packet data convergence protocol (PDCP) reestablishment indication in the message; and after sending the message including the configuration, sending an activation command to the UE for performing a serving cell change to the second cell according to the configuration and without reestablishing the PDCP entity of the UE for the radio bearer.

[0010] Another example embodiment of the techniques is a node in a RAN, the node comprising processing hardware and configured to implement the above method.

[0011] Another example embodiment of the techniques is a method implemented in a UE. The method includes: communicating with a RAN in a first cell and using a radio bearer according to a first configuration; receiving a message from the RAN including a second configuration for performing a serving cell change to a second cell after an activation command; receiving an activation command from the RAN after receiving the configuration; refraining from performing a PDCP reestablishment for the radio bearer in response to the activation command and after determining that the RAN refrained from sending a PDCP reestablishment indication in the message; and communicating with the RAN using the second configuration and the radio bearer.

[0012] Yet another example embodiment of these techniques is a UE comprising a transceiver and processing hardware configured to implement the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A is a block diagram of an example system in which a radio access network (RAN) and a user device may implement the disclosed techniques for managing conditional procedures associated with a secondary node (SN);

[0014] Figure 1B Yes, you can Figure 1A A block diagram of an example base station including a centralized unit (CU) and a distributed unit (DU) operating in a system of FIG.

[0015] Figure 2 is a block diagram of an example protocol stack, Figure 1A The UE communicates with the base station according to the example protocol stack;

[0016] Figure 3 is a message transfer diagram for an example scenario in which a base station configures a UE to perform a lower layer procedure for a cell change operation;

[0017] Figure 4 is a message passing diagram for an example scenario in which a base station configures a UE to perform lower layer procedures for an inter-DU cell change operation;

[0018] Figure 5A is a message passing diagram of an example scenario in which a MN operates with a DC and a SN to perform lower layer procedures for a cell change operation;

[0019] Figure 5B is with Figure 5A A message passing diagram for an example scenario similar to that of , but in which the MN directly configures the UE;

[0020] Fig. 6A is with Figure 5A A message passing diagram of an example scenario similar to that of , but wherein the cell change operation is an inter-DU cell change operation;

[0021] Figure 6B is with Figure 5B A message passing diagram of an example scenario similar to that of , but wherein the cell change operation is an inter-DU cell change operation;

[0022] Fig. 7A is with Figure 5A A message passing diagram for an example scenario similar to that of , but where the base station operates as a MN (e.g., M-DU) and a SN (e.g., S-DU) to perform a cell change operation;

[0023] Figure 7B is with Fig. 7A A message passing diagram for an example scenario similar to that of , but in which the MN directly configures the UE;

[0024] Fig. 8A is with Fig. 7A A message passing diagram of an example scenario similar to that of , but wherein the cell change operation is an inter-DU cell change operation;

[0025] Figure 8B is with Figure 7B A message passing diagram of an example scenario similar to that of , but wherein the cell change operation is an inter-DU cell change operation;

[0026] Fig.9A is a flow chart depicting an example method implemented in a CU, wherein the CU generates an RRC message including a configuration for later activation and a PDCP resume indication;

[0027] Fig. 9B It is depicted with Fig.9A A flowchart of an example method similar to the example method of , but the CU generates an RRC message including a configuration and a PDCP reestablishment indication;

[0028] Fig. 10A is a flow chart depicting an example method implemented in a CU, wherein the CU determines whether to include a PDCP resume indication in an RRC message based on whether the DU is a first DU;

[0029] Fig. 10B It is depicted with Fig. 10A A flowchart of an example method similar to an example method of , but wherein the CU determines whether to include a PDCP re-establishment indication instead of a PDCP recovery indication;

[0030] Fig.11A is a flow chart depicting an example method implemented in a base station, wherein the base station determines whether to perform PDCP recovery based on whether the base station sends a configuration activation command to the UE;

[0031] Fig. 11B It is depicted with Fig.11A A flowchart of an example method similar to the example method of , but wherein the base station determines whether to perform PDCP re-establishment instead of PDCP recovery;

[0032] Fig. 12A is a flow chart depicting an example method implemented in a UE, wherein the UE determines whether to perform PDCP recovery based on whether an RRC message includes a PDCP recovery indication;

[0033] Fig. 12B It is depicted with Fig. 12A A flowchart of an example method similar to that of , but wherein the UE determines whether to perform PDCP re-establishment instead of PDCP recovery;

[0034] Fig.13A is a flow chart depicting an example method implemented in a UE, wherein the UE determines whether to perform PDCP recovery based on whether a received configuration is for later activation; and

[0035] Fig. 13B It is depicted with Fig.13A Flowchart of an example method similar to that of , but wherein the UE determines whether to perform PDCP re-establishment instead of PDCP recovery. DETAILED DESCRIPTION

[0036] Figure 1A An example wireless communication system 100 is depicted in which a communication device may implement these techniques. The wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The UE 102 initially connects to the base station 104. In some scenarios, the base station 104 may perform an SN add to configure the UE 102 to operate with dual connectivity (DC) with the base station 104 and the base station 106. The base stations 104 and 106 operate as a MN and a SN of the UE 102, respectively.

[0037] In various configurations of the wireless communication system 100, the base station 104 may be implemented as a master eNB (MeNB) or a master gNB (MgNB), and the base station 106 may be implemented as a secondary gNB (SgNB). The UE 102 may communicate with the base station 104 and the base station 106 via the same RAT such as EUTRA or NR or via different RATs. When the base station 104 is a MeNB and the base station 106 is an SgNB, the UE 102 may be in EUTRA-NR DC (EN-DC) with the MeNB and the SgNB.

[0038] In some cases, the MeNB or SeNB is implemented as an ng-eNB instead of an eNB. When the base station 104 is a master ng-eNB (Mng-eNB) and the base station 106 is an SgNB, the UE 102 can be in the next generation (NG) EUTRA-NRDC (NGEN-DC) with the Mng-eNB and the SgNB. When the base station 104 is a MgNB and the base station 106 is an SgNB, the UE 102 can be in NR-NR DC (NR-DC) with the MgNB and the SgNB. When the base station 104 is a MgNB and the base station 106 is a secondary ng-eNB (Sng-eNB), the UE 102 can be in NR-EUTRA DC (NE-DC) with the MgNB and the Sng-eNB.

[0039] In a scenario where UE 102 is handed over from base station 104 to base station 106, base stations 104 and 106 operate as a source base station (S-BS) and a target base station (T-BS), respectively. For example, before the handover, UE 102 is able to communicate with base station 104 and an additional base station ( Figure 1A After the handover is completed, UE 102 may continue to operate with base station 106 and the additional base station in DC, or operate with base station 106 in single connectivity (SC). In this case, base stations 104 and 106 operate as a source MN (S-MN) and a target MN (T-MN), respectively.

[0040] The core network (CN) 110 may be an evolved packet core (EPC) 111 or a fifth generation core (5GC) 160. Figure 1A 160. The base station 104 may be an eNB supporting an S1 interface for communicating with the EPC 111, an ng-eNB supporting an NG interface for communicating with the 5GC 160, or a gNB supporting an NR radio interface and an NG interface for communicating with the 5GC 160. In order to exchange messages directly with each other during the scenarios discussed below, the base stations 104 and 106 may support an X2 or Xn interface. Among other components, the EPC 111 may include a serving gateway (SGW) 112, a mobility management entity (MME) 114, and a packet data network gateway (PGW) 116. The SGW 112 is generally configured to transmit user plane packets related to audio calls, video calls, Internet services, etc., and the MME 114 is configured to manage authentication, registration, paging, and other related functions. The PGW 116 provides connectivity from the UE to one or more external packet data networks, such as an Internet network and / or an Internet Protocol (IP) Multimedia Subsystem (IMS) network. 5GC 160 includes a user plane function (UPF) 162 and an access and mobility management (AMF) 164, and / or a session management function (SMF) 166. UPF 162 is generally configured to transmit user plane packets related to audio calls, video calls, Internet traffic, etc., AMF 164 is configured to manage authentication, registration, paging and other related functions, and SMF 166 is configured to manage PDU sessions.

[0041] like Figure 1AAs shown, base station 104 supports cell 124A, and base station 106 supports cell 126. Cells 124A and 126 may partially overlap, enabling UE 102 to communicate with base station 104 and base station 106 in DC, where one of base stations 104 and 106 is a MN and the other is a SN. Base station 104 may support additional cells such as cells 124B and 124C, and base station 106 may support additional cells ( Figure 1A 124B and 124C may partially overlap, so that the UE 102 can communicate with the base station 104 in carrier aggregation (CA). The base station 104 may operate the cells 124A, 124B and 124C via one or more transmission and reception points (TRPs). More specifically, when the UE 102 is in DC with the base station 104 and the base station 106, one of the base stations 104 and 106 operates as a MeNB, Mng-eNB or MgNB, and the other base station operates as a SgNB or Sng-eNB.

[0042] In general, the wireless communication network 100 may include any suitable number of base stations supporting NR cells and / or EUTRA cells. More specifically, the EPC 111 or the 5GC 160 may be connected to any suitable number of base stations supporting NR cells and / or EUTRA cells. Although the examples below specifically refer to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques of the present disclosure may also be applied to other suitable radio access and / or core network technologies, such as sixth generation (6G) radio access and / or 6G core network or 5G NR-6G DC.

[0043] Continue to refer Figure 1A, the base station 104 is equipped with processing hardware 130, which may include one or more general-purpose processors (e.g., CPUs) and non-transitory computer-readable memory storing instructions, and the one or more general-purpose processors execute the instructions. Additionally or alternatively, the processing hardware 130 may include a dedicated processing unit. The processing hardware 130 may include a PHY controller 132, which is configured to send data and control signals on a physical downlink (DL) channel and a DL reference signal with one or more user devices (e.g., UE 102) via one or more cells (e.g., cells 124A, 124B, and / or 124C) and / or one or more TRPs. The PHY controller 132 is also configured to receive data and control signals on a physical uplink (UL) channel and / or a UL reference signal with one or more user devices via one or more cells (e.g., cells 124A, 124B, and / or 124C) and / or one or more TRPs. In an example implementation, the processing hardware 130 includes a MAC controller 134, which is configured to perform MAC functions with one or more user devices. MAC functions include random access (RA) procedures, managing UL timing advance of one or more user devices, and / or communicating UL / DL MAC PDUs with one or more user devices. Processing hardware 130 may also include an RRC controller 136, which is used to implement procedures and message delivery at the RRC sublayer of the protocol communication stack. For example, the RRC controller 132 may be configured to support RRC message delivery associated with a handover process, and / or support necessary operations when the base station 104 operates as a MN relative to the SN or as a SN relative to the MN. The base station 106 may include processing hardware 140 similar to the processing hardware 130. Specifically, components 142, 144, and 146 may be similar to components 132, 134, and 136, respectively.

[0044] UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors such as a CPU and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or a dedicated processing unit. The PHY controller 152 is also configured to receive data and control signals on a physical DL channel and / or DL ​​reference signal with the base station 104 or 106 via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs. The PHY controller 152 is also configured to send data and control signals on a physical UL channel and / or UL reference signal with the base station 104 or 106 via one or more cells (e.g., cells 124A, 124B, 124C, and / or 126) and / or one or more TRPs. In an example implementation, the processing hardware 150 includes a MAC controller 154, which is configured to perform MAC functions with the base station 104 or 106. For example, MAC functions include random access procedures, managing UL timing advance for one or more user devices, and communicating UL / DL MAC PDUs with base station 104 or 106. Processing hardware 150 may also include RRC controller 156 for implementing procedures and messaging at the RRC sublayer of the protocol communication stack.

[0045] In operation, a UE 102 in DC may use radio bearers (e.g., DRBs or SRBs) that terminate at different times at the MN 104 or the SN 106. The UE 102 may apply one or more security keys when communicating on the radio bearers in the uplink (UL) (from the UE 102 to the base station) and / or downlink (from the base station to the UE 102) directions.

[0046] Figure 1BAn example distributed implementation of a base station, such as base station 104 or 106, is depicted. In this implementation, the base station may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 is equipped with processing hardware, which may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or dedicated processing units. In one example, CU 172 is equipped with processing hardware 130. In another example, CU 172 is equipped with processing hardware 140. In an example implementation, processing hardware 140 includes an SN RRC controller 142, which is configured to manage or control one or more RRC configurations and / or RRC processes when base station 106 operates as an SN. DU 174 is also equipped with processing hardware, which may include one or more general-purpose processors such as CPUs and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or dedicated processing units. In some examples, in an example implementation, the processing hardware includes: a medium access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure); and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when the base station 106 operates as a MN or a SN. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0047] Next, Figure 2 The radio protocol stack is shown in a simplified manner, according to which the UE 102 can communicate with the eNB / ng-eNB or gNB. Each of the base stations 104 or 106 can be an eNB / ng-eNB or a gNB.

[0048] The physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA medium access control (MAC) sublayer 204A, which in turn provides logical channels to the EUTRA radio link control (RLC) sublayer 206A, and the EUTRA RLC sublayer in turn provides RLC channels to the EUTRA PDCP sublayer 208 and, in some cases, to the NR PDCP sublayer 210. Similarly, the PHY 202B of NR provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B, and the NR RLC sublayer 206B in turn provides RLC channels to the NR PDCP sublayer 210. In some implementations, the UE 102 supports both the EUTRA stack and the NR stack to support handover between EUTRA base stations and NR base stations and / or to support DC over the EUTRA interface and the NR interface. In addition, as Figure 2 As shown in A, UE 102 can support NR PDCP 210 layered on EUTRARLC 206A.

[0049] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets, which may be referred to as service data units (SDUs) (e.g., from an Internet Protocol (IP) layer layered directly or indirectly on the PDCP layer 208 or 210) and output packets, which may be referred to as protocol data units (PDUs) (e.g., to the RLC layer 206A or 206B). For simplicity, this disclosure refers to both SDUs and PDUs as "packets," except where the distinction between SDUs and PDUs is relevant.

[0050] For example, on the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 provide SRBs to exchange radio resource control (RRC) messages. On the user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 provide DRBs to support data exchange.

[0051] When the UE 102 operates in EUTRA / NR DC (EN-DC) with the base station 104 operating as a MeNB and the base station 106 operating as an SgNB, the network can provide the UE 102 with a bearer terminated at the MN using EUTRA PDCP 208 or a bearer terminated at the MN using NR PDCP 210. In various scenarios, the network can also provide the UE 102 with a bearer terminated at the SN using only NR PDCP 210. The bearer terminated at the MN can be an MCG bearer or a split bearer. The bearer terminated at the SN can be an SCG bearer or a split bearer. The bearer terminated at the MN can be an SRB (e.g., SRB1 or SRB2) or a DRB. The bearer terminated at the SN can be an SRB (e.g., SRB) or a DRB.

[0052] Next, in several example scenarios, Figure 1A A base station operating in the system sends a configuration to UE 102, and later activates the configuration for communication between UE 102 and the base station. Figures 3 to 7B Similar events in the same manner are labeled with similar reference numerals (e.g., event 316 is labeled with Figure 4 A and Figure 4 B's event 416, Figure 5A Event 516, Figure 5B Event 517, Fig. 6A Event 616, Figure 6B Event 617, Fig. 7A Event 716 and Figure 7B 717 of ), with differences discussed below where appropriate. In addition to the differences shown in the figures and discussed below, any of the alternative implementations discussed with respect to a particular event (e.g., for message delivery and processing) may apply to events labeled with similar reference numerals in other figures.

[0053] First reference Figure 3 In scenario 300, base station 104 includes CU 172 and DU 174, and DU 174 operates cell 124A. UE 102 initially communicates 302 with base station 104 on cell 124A using a first configuration. In some implementations, UE 102 communicates 306 with base station 104 using the first configuration on cell 124A and other cells (e.g., Figure 1A124D) is a cell not shown in the figure and communicates with DU 174 with carrier aggregation (CA). DU 174 operates other cells. In other implementations, UE 102 communicates with DU 174 only on cell 124A. In some implementations, UE 102 communicates with DU 174 on cell 124A and / or other cells via one or more TRPs. In some implementations, cell 124A is a PCell. In such cases, other cells include SCells and / or additional cells associated with PCell or SCell. In other implementations, cell 124A is an SCell, and one of the other cells is a PCell. In such cases, the remaining cells in the cell include SCells and / or additional cells associated with PCell or SCell. In the following description, base station 104 can be DU 174, CU 172, or DU 174 and CU 172.

[0054] In some implementations, in event 302, UE 102 sends UL PDU and / or UL control signal to base station 104 via one or more TRPs on cell 124A and / or other cells. In some implementations, UE 102 communicates UL PDU and / or DL ​​PDU with base station 104 via radio bearer, and in other implementations, the radio bearer includes SRB and / or DRB. In some implementations, base station 104 configures radio bearer to UE 102. In some implementations, UL control signal includes UL control information, channel state information, hybrid automatic repeat request (HARQ) confirmation (ACK), HARQ negative ACK, scheduling request and / or sounding reference signal. Similarly, in other implementations, UE 102 receives DL PDU and / or DL ​​control signal from base station 104 on cell 124A and / or other cells via one or more TRPs. In some implementations, the DL control signal includes downlink control information (DCI) and reference signals (e.g., synchronization signal blocks, channel state information reference signals (CSI-RS) and / or tracking reference signals). In other implementations, the base station 104 sends the DCI on a physical downlink control channel (PDCCH) monitored by the UE 102 on the cell 124A and / or other cells via one or more TRPs.

[0055] In some implementations, the first configuration includes physical layer configuration parameters, MAC configuration parameters, RLC configuration parameters, PDCP configuration parameters, measurement configuration parameters, and / or radio bearer configuration parameters. In some implementations, the first configuration includes CellGroupConfig IE (e.g., as defined in 3GPP specification 38.331) or configuration parameters in CellGroupConfig IE. In some implementations, the first configuration includes CSI-MeasConfig IE, MeasConfig IE, and / or RadioBearerConfig IE (e.g., as defined in 3GPP specification 38.331), or configuration parameters in CSI-MeasConfig IE, MeasConfig IE, and / or RadioBearerConfig IE. In some implementations, UE 102 receives the configuration parameters from base station 104. In other implementations, UE 102 receives a portion of the configuration parameters from a base station other than base station 104, and receives the remaining portion of the configuration parameters from base station 104.

[0056] When communicating with the base station 104, the UE 102 sends 304 at least one measurement report to the DU 174. In some implementations, the at least one measurement report includes a layer 1 (L1) measurement report and / or a layer 3 (L3) measurement report for at least one serving cell and / or at least one non-serving cell of the UE 102. For each L3 measurement report in the L3 measurement report, the DU 174 sends 306 a DU to CU message including the L3 measurement report to the CU 172. In some implementations, the DU to CU message of event 306 is an F1 application protocol (F1AP) message (e.g., an UL RRC messaging message). In some implementations, the UE 102 does not send or avoids sending the L1 measurement report to the CU 172. The at least one serving cell includes the cell 124A and / or other cells, and the at least one non-serving cell includes the cell 124B and / or the cell 124C. In some implementations, the first configuration includes at least one measurement configuration. In some implementations, in event 302, UE 102 receives one or more RRC messages (e.g., RRCReconfiguration messages) including at least one measurement configuration from CU 172 via DU 174. According to the at least one measurement configuration, UE 102 performs measurement and sends 304 at least one measurement report to DU 174. In some implementations, at least one measurement configuration includes an L3 measurement configuration (e.g., MeasConfig IE) and / or an L1 measurement configuration. For example, the L1 measurement configuration (e.g., CSI-MeasConfig IE) includes a CSI resource configuration (e.g., CSI-ResourceConfig IE) and / or a CSI report configuration (e.g., CSI-ReportConfig IE). UE 102 sends an L3 measurement report to CU 172 via DU 174 according to the L3 measurement configuration. UE 102 sends an L1 measurement report to DU 174 according to the L1 measurement configuration. In some implementations, at least one measurement configuration includes a new type of measurement configuration for fast serving cell change (e.g., a new RRC IE (e.g., as defined in 3GPP specification 38.331 v18.0.0 and / or later versions)). For example, the new type of measurement configuration includes a CSI resource configuration (e.g., CSI-ResourceConfig IE) and / or a new type of report configuration. In such implementations, at least one measurement report includes a new type of measurement report associated with the new type of measurement configuration. UE 102 sends the new type of measurement report to DU 174 according to the new type of measurement configuration. In some implementations, each of the new type of report configurations includes a trigger event configuration that configures a trigger event to trigger UE 102 to send the new type of measurement report.In case UE 102 detects a triggering event, UE 102 sends a new type measurement report to DU 174 .

[0057] In some implementations, the L1 measurement report includes at least one L1 measurement result. In some implementations, the at least one L1 measurement result includes at least one L1 reference signal received power (L1-RSRP) value and / or at least one L1 signal to interference and noise ratio (L1-SINR) value. In some implementations, for each L1 measurement report in the L1 measurement report, the UE 102 sends a PUCCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each L1 measurement report in the L1 measurement report to the DU 174 on the PUCCH. In other implementations, for each L1 measurement report in the L1 measurement report, the UE 102 sends a PUSCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each L1 measurement report in the L1 measurement report to the DU 174 on the PUSCH. In yet other implementations, the UE 102 sends a portion of the L1 measurement report to the DU 174 on a PUCCH and sends the remainder of the L1 measurement report to the DU on a physical UL shared channel (PUSCH). That is, for each L1 measurement report in the portion of the L1 measurement report, the UE 102 sends a PUCCH transmission including the L1 measurement report to the DU 174, and for each L1 measurement report in the remainder of the L1 measurement report, the UE 102 sends a PUSCH transmission including the L1 measurement report to the DU 174. In some implementations, each L1 measurement report in the L1 measurement report is a portion of channel state information (CSI) (i.e., a CSI component) or CSI. In some implementations, the UE 102 includes other CSI components in the above-mentioned PUCCH transmission and / or PUSCH transmission. In some implementations, other CSI components include components such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), a synchronization signal (SS) / physical broadcast channel (PBCH) resource block indicator (SSBRI), a layer indicator (LI) and / or a rank indicator (RI).

[0058] In some implementations, each L3 measurement report in the L3 measurement report includes at least one L3 measurement result. In some implementations, at least one L3 measurement result includes at least one RSRP value and / or at least one SINR value. In some implementations, the UE 102 sends each L3 measurement report in the L3 measurement report to the CU 172 on the PUSCH via the DU 174. In some implementations, each L3 measurement report in the L3 measurement report is an RRC message (e.g., a MeasurementReport message). In some implementations, each L3 measurement configuration in the L3 measurement configuration includes a specific measurement identifier (e.g., measId), and each L3 measurement report in the L3 measurement report includes a specific measurement identifier in a specific L3 measurement configuration. In some implementations, when the CU 172 receives the L3 measurement report including the measurement identifier and the L3 measurement result from the UE 102 via the DU 174, the CU 172 determines that the L3 measurement report is associated with the L3 measurement configuration identified by the measurement identifier.

[0059] In some alternative implementations, for each measurement report of at least one measurement report (e.g., an L1 measurement report and / or a new type measurement report), at event 304, the UE 102 sends a MAC control element (CE) including the measurement report to the DU 174. To send the MAC CE, at event 304, the UE 102 generates one or more MAC PDUs to the DU 174, each MAC PDU including one or more MAC CEs in the MAC CE.

[0060] In some implementations, the UE 102 performs measurements on one or more reference signals according to at least one measurement configuration. In another implementation, the one or more reference signals include one or more synchronization signals (SS) / physical broadcast channel (PBCH) resource blocks (SSBs) and / or one or more CSI-RS. The UE 102 obtains at least one L1 measurement result and / or at least one L3 measurement result from the measurement. The DU 174 transmits one or more reference signals on cells 124A and 124B and optionally cell 124C and / or other cells.

[0061] After receiving one or more of the at least one measurement report from the UE 102 (e.g., in response to receiving one or more of the at least one measurement report from the UE), the base station 104 (i.e., the CU 172 or the DU 174) determines to prepare the cell 124B for the UE 102. In some implementations, the base station 104 determines to prepare the cell 124B for the UE 102 because the at least one measurement report indicates that the cell 124B can be used by the base station 104 to communicate with the UE 102. In some implementations, the base station 104 determines to prepare the cell 124B for the UE 102 because the at least one measurement report indicates that the cell 124B is eligible for communication with the UE 102. In some implementations, the CU 172 determines to prepare the cell 124B for the UE 102 if the L3 measurement report indicates that the signal strength and / or quality of the cell 124B is above a first predetermined threshold and / or is better than the cell 124A. In other implementations, if the L1 measurement report or the new type measurement report indicates that the signal strength and / or quality of the cell 124B is above a first predetermined threshold and / or is better (e.g., higher) than the cell 124A, the DU 174 determines to prepare the cell 124B for the UE 102. Alternatively, the base station 104 determines to prepare the cell 124B for the UE 102 regardless of whether the measurement report is received from the UE 102.

[0062] In some implementations, if CU 172 determines to prepare cell 124B, CU 172 sends 308 a first CU-to-DU message to DU 174 to prepare cell 124B for UE 102. In some implementations, CU 172 includes a cell identifier (ID) of cell 124B in the first CU-to-DU message. For example, the cell ID is a cell global identifier (CGI). In another example, the cell ID is a physical cell ID (PCI). In response, DU 174 generates a second configuration (referred to herein as configuration 1) to configure cell 124B, and sends 310 a first DU-to-CU message including the second configuration to CU 172. In another implementation, if DU 174 determines to prepare cell 124B, DU 174 initiates transmission of the first DU-to-CU message to CU 172.

[0063] After receiving the first DU-to-CU message, CU 172 generates an RRC reconfiguration message (e.g., an RRCReconfiguration message) including configuration 1, and sends 316 a second CU-to-DU message including the RRC reconfiguration message to DU 174. In turn, DU 174 sends 318 the RRC reconfiguration message to UE 102. In response, UE 102 sends 320 an RRC reconfiguration complete message (e.g., an RRCReconfigurationComplete message) to DU 174, which in turn sends 322 a second DU-to-CU message including the RRC reconfiguration complete message to CU 172. In some implementations, CU 172 performs security protection (e.g., integrity protection and / or ciphering) on ​​the RRC reconfiguration message. For example, CU 172 generates a message integrity authentication code (MAC-I) for the RRC reconfiguration message, encrypts the RRC reconfiguration message and the MAC-I to obtain an encrypted RRC reconfiguration message and an encrypted MAC-I, and sends a PDCP PDU including the encrypted RRC reconfiguration message and the encrypted MAC-I to UE 102 via DU 174 in events 316 and 318. When UE 102 receives the PDCP PDU from CU 172 via DU 174 (i.e., events 316 and 318), UE 102 decrypts the encrypted RRC reconfiguration and the encrypted MAC-I to obtain the RRC reconfiguration message and the MAC-I, and verifies whether the MAC-I is valid. If UE 102 verifies that the MAC-I is invalid, UE 102 discards or ignores the RRC reconfiguration message. In some implementations, UE 102 performs an RRC connection reestablishment procedure in response to an invalid MAC-I. Otherwise, in another implementation, if UE 102 verifies that MAC-I is valid, UE 102 processes the RRC reconfiguration. UE 102 avoids applying (ie, executing) Configuration 1 until a configuration activation command is received to activate Configuration 1 (eg, event 330).

[0064] In some implementations, the first CU to DU message is a UE context modification request message, and the first DU to CU message is a UE context modification response message or a UE context modification required message. In some implementations, in the case where a UE context modification message is required, CU 172 sends a UE context modification confirmation message to DU 174 in response to the UE context modification message required. In some implementations, the second CU to DU message is a DL RRC message transmission message. In other implementations, the second CU to DU message is a UE context modification request message, and DU 174 sends a second DU to CU message (e.g., a UE context modification response message) to CU172 in response to the second CU to DU message.

[0065] Events 308 and 310 in Figure 3 It is collectively referred to as the service cell preparation process 390.

[0066] In some implementations, CU 172 includes a field or IE in the RRC reconfiguration message of events 316 and 318 to indicate to UE 102 that configuration 1 is not applied immediately. In some implementations, the field or IE is currently defined (e.g., in 3GPP specification 38.331 v18.0.0 and / or updated versions). In other implementations, the field or IE is newly defined (e.g., in 3GPP 6G specifications). In some implementations, the field or IE is an indicator. If the RRC reconfiguration message of event 318 includes an indicator, UE 102 avoids applying configuration 1 immediately. Otherwise, if the RRC reconfiguration message of event 318 does not include an indicator, UE 102 applies configuration 1 immediately. In other implementations, the field or IE is a container (e.g., a first container and / or a second container described below). For example, UE 102 receives an RRC reconfiguration message (e.g., an RRC reconfiguration message of event 318) including a configuration (e.g., configuration 1). If the configuration is included in the container, the UE 102 avoids applying the configuration immediately. Otherwise, if the configuration is not included in the container, the UE 102 applies the configuration immediately.

[0067] In some implementations, after receiving configuration 1 in event 310, CU 172 generates a first container including configuration 1, includes the first container in an RRC reconfiguration message, and sends the RRC reconfiguration message to UE 102 in event 316. Alternatively, DU 174 generates the first container and includes the first container in a first DU to CU message. In some implementations, the first container is a first addition or modification list (e.g., ConfigToAddModList IE, CellConfigToAddModList IE, MobilityToAddModList IE, MobilityConfigToAddModListIE, or CellGroupConfigToAddModList IE). Base station 104 includes configuration 1 in a first element (referred to herein as element 1) of the first addition or modification list. For example, element 1 is an addition or modification IE (e.g., ConfigToAddMod IE, CellConfigToAddMod IE, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddMod IE). In some implementations, when the UE 102 receives the first addition or modification list, the UE 102 stores the first addition or modification list (eg, in a variable in random access memory (RAM)).

[0068] In some implementations, CU 172 includes a first ID (referred to herein as ID 1) for identifying configuration 1 in the RRC reconfiguration message. In some implementations, CU 172 includes ID 1 in a first container or element 1. In some implementations, CU 172 assigns ID 1 to configuration 1. In other implementations, CU 172 receives ID 1 from DU 174 in a first DU-to-CU message, as described below.

[0069] In some implementations, CU 172 sends ID 1 to DU 174 so that DU 174 can associate ID 1 with configuration 1. In some implementations, CU 172 includes ID 1 in the first CU-to-DU message. In other implementations, CU 172 sends 312 a third CU-to-DU message including ID 1 to DU 174. In some such cases, CU 172 includes configuration 1 in the third CU-to-DU message to indicate the association between ID 1 and configuration 1. In other implementations, DU 174 sends 314 a third DU-to-CU message to CU 172 in response to the third CU-to-DU message. Events 312 and 314 are described in detail in detail below. Figure 3 This is collectively referred to as the ID allocation process 392.

[0070] In some implementations, in the event that CU 172 includes ID 1 in the first CU-to-DU message, DU 174 includes ID 1 in configuration 1. In such an event, CU 172 does not include ID 1 in the RRC reconfiguration message, the first container, and / or element 1.

[0071] In some alternative implementations, DU 174 assigns ID 1 for identifying configuration 1. In some implementations, DU 174 includes ID 1 in the first DU to CU message. In other implementations, CU 172 includes ID 1 in the RRC reconfiguration message. In other implementations, DU 174 includes ID 1 in configuration 1. Therefore, CU 172 does not include an ID identifying configuration 1 in the RRC reconfiguration message, the first container, and / or element 1.

[0072] In some implementations, configuration 1 includes multiple configurations for UE 102 to communicate with DU 174 on cell 124B. In some implementations, the multiple configurations include physical layer configuration parameters (e.g., PhysicalCellGroupConfig IE), MAC layer configuration parameters (e.g., MAC-CellGroupConfig IE), and / or RLC configuration parameters (e.g., RLC-BearerConfig IE). In some other implementations, the multiple configurations include special cell configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig IE).

[0073] In some implementations, DU 174 includes the random access configuration in configuration 1. In other implementations, DU 174 does not include the random access configuration in configuration 1. In some implementations, if cell 124A and cell 124B are not synchronized, DU 174 determines to include the random access configuration in configuration 1. Otherwise, if cell 124A and cell 124B are synchronized, DU 174 determines not to include the random access configuration in configuration 1. In other implementations, if DU 174 determines that UE 102 has not yet synchronized with cell 124B in the UL, DU 174 determines to include the random access configuration in configuration 1. Otherwise, if DU 174 determines that UE 102 has synchronized with cell 124B in the UL, DU 174 determines not to include the random access configuration in configuration 1. If configuration 1 includes the random access configuration, UE 102 performs a random access procedure according to the random access configuration at event 332, as described below. Otherwise, if configuration 1 does not include a random access configuration, UE 102 skips the random access procedure of event 332 in response to configuration 1 excluding the random access configuration.

[0074] In some implementations, regardless of whether cells 124A and 124B are synchronized, DU 174 includes the random access configuration in configuration 1. In some implementations, if cell 124A and cell 124B are synchronized, DU 174 determines to include a first indication in configuration 1, which configures UE 102 not to perform a random access procedure on cell 124B. Otherwise, if cell 124A and cell 124B are not synchronized, DU 174 determines not to include the first indication in configuration 1. In other implementations, if DU 174 determines that UE 102 has been synchronized with cell 124B in the UL, DU 174 determines to include the first indication in configuration 1. Otherwise, if DU 174 determines that UE 102 has not been synchronized with cell 124B in the UL, DU 174 determines not to include the first indication in configuration 1. If configuration 1 includes the first indication, UE 102 skips the random access procedure of event 332 based on or in response to the first indication. Otherwise, if configuration 1 does not include the first indication, then in response to configuration 1 excluding the first indication, UE 102 performs a random access procedure according to the random access procedure in event 332, as described below.

[0075] In some implementations, DU 174 includes a reconfiguration with synchronization configuration (e.g., ReconfigurationWithSync IE) in configuration 1 or special cell configuration. In other implementations, DU 174 does not include a reconfiguration with synchronization configuration (e.g., ReconfigurationWithSync IE) in configuration 1 or special cell configuration. In some implementations, if cell 124A and cell 124B are not synchronized, base station 104 determines to include a reconfiguration with synchronization configuration in configuration 1. Otherwise, if cell 124A and cell 124B are synchronized, DU 174 determines not to include a reconfiguration with synchronization configuration in configuration 1. In other implementations, if DU 174 determines that UE 102 has not yet synchronized with cell 124B in UL, DU 174 determines to include a reconfiguration with synchronization configuration in configuration 1. Otherwise, if DU 174 determines that UE 102 has synchronized with cell 124B in UL, DU 174 determines not to include a reconfiguration with synchronization configuration in configuration 1. In some implementations, if configuration 1 includes reconfiguration with a synchronization configuration, UE 102 performs a random access procedure in event 332, as described below, in response to or according to the reconfiguration with the synchronization configuration. Otherwise, if configuration 1 does not include reconfiguration with a synchronization configuration, UE 102 skips the random access procedure of event 332. In some implementations, DU 174 includes a cell ID (i.e., cell ID 1) of cell 1 (i.e., cell 124B) in configuration 1. In some implementations, cell ID 1 is a PCI. In other implementations, cell ID 1 is a CGI. In some other implementations, configuration 1 includes a cell index 1 (e.g., a serving cell index) that indexes cell ID 1 or cell 124B.

[0076] In some implementations, after receiving one or more measurement reports in at least one measurement report of event 304 (e.g., in response to receiving one or more measurement reports in at least one measurement report of the event), base station 104 (i.e., CU 172 or DU 174) determines to prepare other cells of base station 104 for UE 102. In some implementations, base station 104 determines to prepare other cells because at least one measurement report indicates that other cells can be used by base station 104 to communicate with UE 102. In another implementation, the other cells include cell 124C and / or cells other than cells 124A, 124B, and 124C. In some implementations, CU 172 determines to prepare the specific cell for UE 102 when the L3 measurement report indicates that the signal strength and / or quality of a specific cell in the other cells is higher than a corresponding predetermined threshold and / or is better (e.g., higher) than cell 124A. In other implementations, when the L1 measurement report or the new type measurement report indicates that the signal strength and / or quality of a specific cell among the other cells is higher than the first predetermined threshold and / or better (e.g., higher) than the cell 124A, the DU 174 determines to prepare the specific cell for the UE 102. In some implementations, the corresponding predetermined threshold of the other cells is different from the first predetermined threshold. In another implementation, the corresponding predetermined threshold of the other cells is the same as the first predetermined threshold. In some implementations, the corresponding predetermined threshold of the other cells is the same as the first predetermined threshold. Alternatively, the base station 104 determines to prepare the other cells for the UE 102 regardless of whether the measurement report is received from the UE 102.

[0077] In some implementations, in response to a determination about preparing other cells, CU 172 and DU 174 perform at least one other serving cell preparation process to prepare the other cells, wherein each of the at least one other serving cell preparation process is similar to process 390. In some implementations, CU 172 includes the cell ID of the other cells in at least one CU-to-DU message similar to the first CU-to-DU message of the at least one serving cell preparation process. In some implementations, CU 172 and DU 174 perform an additional serving cell preparation process similar to process 390 to prepare each of the other cells. In some such cases, CU 172 includes the cell ID of a specific cell in the other cells in a CU-to-DU message similar to the first CU-to-DU message of the serving cell preparation process. In the serving cell preparation process, DU 174 generates configurations 2, ..., N, each configuring a specific cell in the other cells, and sends configurations 2, ..., N to CU 172, as described for configuration 1. "N" is an integer and is greater than 1. For example, "N" is 2, 4, 6, 8, 10, 12, 14, or 16. The examples and implementations of Configuration 1 may be applied to Configuration 2, ..., N.

[0078] In other implementations, CU 172 determines to prepare other cells in process 390. In some such cases, CU 172 includes a cell ID of each of the other cells in the first CU to DU message, and DU 174 includes configurations 2, ..., N in the first DU to CU message. In still other implementations, DU 174 determines to prepare other cells in process 390 and includes configurations 2, ..., N in the first DU to CU message.

[0079] In some implementations, after receiving configurations 2, ..., N from DU 174, CU 172 includes configurations 2, ..., N in the first container. In some implementations, CU 172 includes configurations 2, ..., N in elements 2, ..., N, and includes elements 2, ..., N in the first container. In some implementations, CU 172 includes IDs 2, ..., N for identifying configurations 2, ..., N, respectively, in the RRC reconfiguration message. In some implementations, CU 172 includes IDs 2, ..., N in the first container. For example, CU 172 includes IDs 2, ..., N and configurations 2, ..., N in elements 2, ..., N in the first addition or modification list.

[0080] In some implementations, CU 172 assigns IDs 2, ..., N for configurations ..., N. In other implementations, CU 172 receives IDs 2, ..., N from DU 174 in a first DU to CU message of process 390 or in a DU to CU message of at least one other serving cell preparation process or additional serving cell preparation processes.

[0081] In some implementations, CU 172 performs an ID allocation process with DU 174 for each of configurations 2, ..., N, similar to process 392. In such cases, DU 174 includes ID 2, ..., N in configurations 2, ..., N. In such cases, CU 172 does not include ID 2, ..., N in the RRC reconfiguration message, the first container, and / or elements 2, ..., N.

[0082] In some alternative implementations, DU 174 assigns ID 2, ..., N in configuration 2, ..., N. In some implementations, DU 174 includes ID 2, ..., N in the first DU to CU message of process 390 or in a DU to CU message of at least one other serving cell preparation process or additional serving cell preparation process. In other implementations, CU 172 includes ID 2, ..., M in the RRC reconfiguration message. In other implementations, DU 174 includes ID 2, ..., N in configuration 2, ..., N. Therefore, CU 172 does not include an ID identifying each configuration in configuration 2, ..., N in the RRC reconfiguration message, the first container, and / or element 1.

[0083] In some alternative implementations, CU 172 generates a second container including configuration 2, ..., N or elements 2, ..., N without using the first container. Alternatively, DU 174 generates the second container and includes the second container in the first DU to CU message or in a DU to CU message of another serving cell preparation process. Then, CU 172 sends an additional RRC reconfiguration message including the second container to UE 102 via DU 174, similar to events 316 and 318. In response, UE 102 sends an additional RRC reconfiguration complete message to CU 172 via DU 174, similar to events 320 and 322. In some implementations, the second container is a second addition or modification list (e.g., ConfigToAddModList IE, CellConfigToAddModListIE, MobilityToAddModList IE, MobilityConfigToAddModList IE, or CellGroupConfigToAddModList IE), and in another implementation, each element in elements 2, ..., N is an addition or modification IE (e.g., ConfigToAddMod IE, ReconfigToAddMod IE, CellConfigToAddModIE, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddModIE). In some implementations, when UE 102 receives the second addition or modification list, UE 102 stores the second addition or modification list together with the first addition or modification list (e.g., in a variable in RAM).

[0084] In some implementations, the DU 174 includes cell IDs 2, ..., N in configurations 2, ..., N, respectively. The cell IDs 2, ..., N identify cells 2, ..., N, respectively. In some implementations, each of the cell IDs 2, ..., N is a PCI. In some other implementations, the configurations 2, ..., N include cell indexes 2, ..., N (e.g., serving cell indexes) that index the cell IDs 2, ..., N or the cells 2, ..., N, respectively.

[0085] In some implementations, each of configurations 1 and / or 2, ..., N is a CellGroupConfigIE. In such implementations, the following is an example structure of a first add or modify list or a second add or modify list (e.g., CellGroupConfigToAddModList IE), and the CellGroupConfigToAddMod IE is an element of the first add or modify list or the second add or modify list.

[0086] In some implementations, CU 172 sends a release list to UE 102 via DU 174 to release one or more configurations in configurations 1, ..., N. For example, CU 172 sends an RRC reconfiguration message including the release list to UE 102 via DU 174. In response, UE 102 sends an RRC reconfiguration complete message to CU 172 via DU 174. In some implementations, base station 104 includes one or more IDs of configurations in the release list to indicate one or more configurations in the configurations to be released. UE 102 identifies one or more configurations in the configuration according to the ID, and releases one or more configurations in the configuration in response to the release list.

[0087] In some implementations, the base station 104 sends a third addition or modification list to the UE 102 to release all configurations in configurations 1, ..., N, and the third addition or modification list is empty or does not include a configuration. In some implementations, the base station 104 sends an RRC reconfiguration message including the third addition or modification list to the UE 102. In response, the UE 102 sends an RRC reconfiguration complete message to the CU 172 via the DU 174. The UE 102 releases all configurations in configurations 1, ..., N in response to the third addition or modification list.

[0088] In some implementations, CU 172 determines to release one, some, or all of configurations in configurations 1, ..., N, and in other implementations, sends a CU-to-DU message to DU 174 to instruct DU 174 to release one, some, or all of configurations in configurations 1, ..., N. For example, CU 172 includes one, some, or all of IDs 1, ..., N in the CU-to-DU message to instruct DU 174 to release one, some, or all of configurations in configurations 1, ..., N. Depending on the implementation, each of cell IDs 1, ..., N is a CGI or a PCI. In response, DU 174 releases one, some, or all of configurations in configurations 1, ..., N, and in some implementations, sends a DU-to-CU message to CU 172. In other implementations, DU 174 determines to release one, some, or all of configurations in configurations 1, ..., N, and sends a DU-to-CU message to CU 172, the DU-to-CU message including the IDs of one, some, or all of configurations in configurations 1, ..., N. After receiving the DU to CU message (eg, in response to receiving the DU to CU message), the CU 172 generates a release list or a third addition or modification list to release one, some, or all of configurations 1, . . . , N.

[0089] In some other implementations, DU 174 generates a release list or a third addition or modification list. In some such cases, DU 174 sends a DU to CU message to CU 172, which includes the release list or the third addition or modification list. In another implementation, in response, CU 172 sends a CU to DU message to DU 174. In some implementations, DU 174 determines to release one, some, or all of configurations in configuration 1, ..., N. In other implementations, DU 174 receives a CU to DU message from CU 172, which includes an ID of one, some, or all of configurations in configuration 1, ..., N to indicate that one, some, or all of configurations in configuration 1, ..., N are released.

[0090] Example Implementation 1

[0091]

[0092]

[0093] For example, the first addition or modification list is the first CellGroupConfigToAddModList IE, and the second addition or modification list is the second CellGroupConfigToAddModList IE. Element 1 is CellGroupConfigToAddMod IE 1, and elements 2, ..., N are CellGroupConfigToAddModIE 2, ..., N, respectively. ID 1 and configuration 1 are ConfigId and CellGroupConfig IE in CellGroupConfigToAddMod IE 1, respectively. ID 2, ..., N and configuration 2, ..., N are ConfigId and CellGroupConfig IE in CellGroupConfigToAddModIE 2, ..., N, respectively. In some implementations, the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 1, and the second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 2, ..., N. In another implementation, the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddModIE 1, . . . , N.

[0094] In some implementations, the release list is a CellGroupConfigToReleaseList IE. In other implementations, the base station 104 includes one or more ConfigID IEs in the CellGroupConfigToReleaseList IE to release one or more CellGroupConfigToAddMod IEs in CellGroupConfigToAddMod IEs 1, ..., N. The one or more CellGroupConfigToAddMod IEs are identified by one or more ConfigID IEs.

[0095] Example Implementation 2

[0096] Example implementation 2 is similar to example implementation 1, except that CellGroupConfigToAddModIE does not include ConfigId.

[0097]

[0098] In some implementations, ID 1, ..., N is implicitly indicated by the order of CellGroupConfigToAddMod IE 1, ..., N in the first or second CellGroupConfigToAddModList. For example, CellGroupConfigToAddMod IE 1 is the first IE in the first CellGroupConfigToAddModList IE, which implicitly indicates that ID 1 has a value of X. X can be 0 or 1. If the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 1, ..., N in order, then ID 1, ..., N has values ​​of X, X+1, ..., X+(N-1). In some implementations, if the base station 104 sends the second CellGroupConfigToAddModList IE to the UE 102, the UE 102 and the base station 104 replace the first CellGroupConfigToAddModList IE with the second CellGroupConfigToAddModList IE. If the second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IEs 2, ..., N in order, then ID 2, ..., N is a value of X, X+1, ..., X+N-2. If the second CellGroupConfigToAddModListIE includes CellGroupConfigToAddMod IEs 1, ..., N in order, then ID 1, ..., N is a value of X, X+1, ..., X+N-1. In some alternative implementations, ID 1, ..., N is a cell ID 1, ..., N.

[0099] In some implementations, the base station 104 sends a CellGroupConfigToAddModList IE including zero CellGroupConfigToAddMod IEs to release all of the CellGroupConfigToAddMod IEs 1, . . . , N.

[0100] In example implementations 1 and 2, "CellGroupConfigToAddModList", "CellGroupConfigToAddMod", "configId", "ConfigId", "cellGroupConfig", "CellGroupConfigToReleaseList" and "maxNrofConfigCells" are merely exemplary and should not be construed as limiting the scope and application of the present invention.

[0101] In other implementations, each of configurations 1 and / or 2, ..., N is an RRCReconfiguration message. In such implementations, the following (ie, example implementations 3-6) are example structures of the first addition or modification list or the second addition or modification list.

[0102] Example Implementation 3

[0103] In example implementation 3, the first add or modify list or the second add or modify list is a CondReconfigToAddModList-r16 IE (eg, as defined in 3GPP specification 38.331 from Release 16), and the CondReconfigToAddMod IE is an element of the list.

[0104]

[0105]

[0106] For example, the first addition or modification list is the first CondReconfigToAddModList-r16 IE and the second CondReconfigToAddModList-r16 IE. Element 1 is CondReconfigToAddMod-r16 IE 1, and elements 2, ..., N are CondReconfigToAddMod-r16 IE 2, ..., N, respectively. ID 1 and configuration 1 are CondReconfigId and RRCReconfiguration message in CondReconfigToAddMod IE 1, respectively. ID 2, ..., N and configuration 2, ..., N are CondReconfigId and RRCReconfiguration message in CondReconfigToAddMod IE 2, ..., N, respectively. In some implementations, the first CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 1, and the second CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 2, ..., N. In other implementations, the first CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 1, ..., N.

[0107] In this example implementation, the base station 104 includes a conditional configuration (i.e., condExecutionCond-r16) in at least one of the CondReconfigToAddMod-r16 IEs. In some implementations, if the UE 102 supports conditional procedures (e.g., conditional handover (CHO), conditional PSCell addition (CPA), or conditional PSCell change (CPC)), the UE 102 evaluates one or more conditions configured for the conditional procedure in the condExecutionCond-r16 field. If the UE 102 detects that at least one or all of the one or more conditions in the condExecutionCond-r16 field in a particular CondReconfigToAddMod-r16 IE are met, the UE 102 immediately applies the configuration in the RRCReconfiguration message in the CondReconfigToAddMod-r16 IE (e.g., as described in 3GPP specification 38.331). In some implementations, the base station 104 does not include the conditional configuration (i.e., condExecutionCond-r16) in any or some of the CondReconfigToAddMod-r16 IEs. Therefore, the UE 102 is not configured to perform or it does not perform any evaluation (i.e., detection or determination) of the condition of the conditional procedure (e.g., conditional handover) of the CondReconfigToAddMod-r16 IE that does not include the conditional configuration (i.e., condExecutionCond-r16).

[0108] In some implementations, the release list is a CondReconfigToRemoveList-r16 IE. In another implementation, the base station 104 includes one or more CondReconfigID IEs in the CondReconfigToRemoveList-r16 IE to release one or more CondReconfigToAddMod-r16 IEs in CondReconfigToAddMod-r16 IEs 1, ..., N. The one or more CondReconfigToAddMod-r16 IEs are identified by one or more CondReconfigID IEs.

[0109] Example Implementation 4

[0110] Example implementation 4 is similar to example implementation 3, except that, in some implementations, a new indicator (e.g., fastServingCellChange-r18 field) is optionally included in the CondReconfigToAddMod-r16 IE. In some implementations, the new indicator indicates that the CondReconfigToAddMod-r16 IE (i.e., the RRCReconfiguration message or condRRCReconfig-r16 in the IE) is configured for fast serving cell change (i.e., see the description for event 312). If the base station 104 does not include the new indicator in the CondReconfigToAddMod-r16 IE, the CondReconfigToAddMod-r16 IE is not configured for fast serving cell change.

[0111]

[0112] Example Implementation 5

[0113] Some of the example implementations 3 and 4 may involve the UE 102 supporting conditional procedures (e.g., conditional handover (CHO), conditional PSCell addition (CPA), and / or conditional PSCell change (CPC)). If the UE 102 does not support the conditional procedures, the base station 104 does not configure or enable fast serving cell change for the UE 102. Therefore, example implementation 5 is separate from the conditional procedures.

[0114]

[0115] In some implementations, the first addition or modification list is a first ReconfigToAddModList IE, and the second addition or modification list is a second ReconfigToAddModList IE. Element 1 is ReconfigToAddMod IE 1, and elements 2, ..., N are ReconfigToAddMod IE 2, ..., N, respectively. ID 1 and configuration 1 are ConfigId and RRCReconfiguration IE in ReconfigToAddMod IE 1, respectively. ID 2, ..., N and configuration 2, ..., N are ConfigId and RRCReconfiguration IE in ReconfigToAddMod IE 2, ..., N, respectively. In some implementations, the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, and the second ReconfigToAddModList IE includes ReconfigToAddMod IE 2, ..., N. In another implementation, the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N.

[0116] In some implementations, the release list is a ReconfigToReleaseList IE. In other implementations, the base station 104 includes one or more ConfigID IEs in the ReconfigToReleaseList IE to release one or more ReconfigToAddMod IEs in ReconfigToAddMod IEs 1, ..., N. The one or more ReconfigToAddMod IEs are identified by one or more ConfigID IEs.

[0117] Example Implementation 6

[0118]

[0119] Example implementation 6 is similar to example implementation 5, except that the ReconfigToAddMod IE does not include ConfigId. In some implementations, ID 1, ..., N is implicitly indicated by the order of ReconfigToAddMod IE 1, ..., N in the first or second ReconfigToAddModList. For example, ReconfigToAddMod IE 1 is the first IE in the first ReconfigToAddModList IE, which implicitly indicates that ID 1 has a value of X. X can be 0 or 1. If the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N in order, then ID 1, ..., N has values ​​of X, X+1, ..., X+(N-1). In some implementations, if the base station 104 sends a second ReconfigToAddModList IE to the UE 102, the UE 102 and the base station 104 replace the first ReconfigToAddModList IE with the second ReconfigToAddModList IE. If the second ReconfigToAddModList IE includes ReconfigToAddMod IEs 2, ..., N in order, then ID 2, ..., N is a value of X, X+1, ..., X+N-2. If the second ReconfigToAddModList IE includes ReconfigToAddMod IEs 1, ..., N in order, then ID 1, ..., N has a value of X, X+1, ..., X+N-1. In some alternative implementations, ID 1, ..., N is a cell ID 1, ..., N.

[0120] In some implementations, the base station 104 sends a ReconfigToAddModList IE including zero ReconfigToAddMod IEs to release all of the ReconfigToAddMod IEs 1, . . . , N.

[0121] In example implementations 5 and 6, “ReconfigToAddModList,” “ReconfigToAddMod,” “configId,” “ConfigId,” “cellGroupConfig,” “ReconfigToReleaseList,” and “maxNrofConfigCells” are exemplary and should not limit the scope and application of the present invention.

[0122] Example Implementation 7

[0123] Example implementation 7 is a combination of example implementations 1 and 5, as shown below. Depending on the implementation, any configuration in configurations 1, ..., N is a CellGroupConfig IE or an RRCReconfiguration message. The examples and implementations described for example implementations 1 and 5 can be applied to example implementation 7.

[0124]

[0125] After receiving the RRC reconfiguration in event 318 or sending the RRC reconfiguration complete message in event 320, the UE 102 sends 324 at least one measurement report to the DU 174, similar to event 304. In some implementations, the DU 174 sends 326 a DU-to-CU message including the at least one measurement report to the CU 172, similar to event 306. In other implementations, the DU 174 does not send the at least one measurement report to the CU 172. In some implementations, the at least one measurement report of event 324 includes an L1 measurement report, an L3 measurement report, and / or a new type measurement report, as described for event 304. In some implementations, the UE 102 sends 324 at least one measurement report to the DU 174 on the PUCCH and / or PUSCH, similar to event 304. In other implementations, the UE 102 sends 324 at least one MAC CE including the at least one measurement report to the DU 174, similar to event 304. In some implementations, each measurement report of the at least one measurement report of event 324 is not an RRC message.

[0126] In some implementations, the UE 102 sends 324 at least one measurement report to the DU 174 according to the at least one measurement configuration. The at least one measurement configuration configures the UE 102 to perform measurements and report measurement results. The CU 172 sends the at least one measurement configuration to the UE 102 via the DU 174. For example, after event 306 or 316, the CU 172 sends one or more RRC messages (e.g., RRCReconfiguration messages) including the at least one measurement configuration to the UE 102 via the DU 174. The one or more RRC messages may or may not include the RRC reconfiguration message of event 316. According to the at least one measurement configuration, the UE 102 performs measurements on one or more reference signals. In some implementations, the one or more reference signals include one or more SSBs and / or one or more CSI-RSs. The UE 102 obtains at least one L1 measurement result and / or at least one L3 measurement result from the measurement, and the UE 102 includes the at least one L1 measurement result and / or at least one L3 measurement result in the at least one measurement report of event 324. DU 174 transmits one or more reference signals on cells 124A and 124B, and in some implementations, transmits one or more reference signals on cell 124C and / or other cells. In some implementations, at least one measurement configuration includes an L3 measurement configuration (e.g., MeasConfig IE), an L1 measurement configuration (e.g., CSI-MeasConfig IE), and / or a new type measurement configuration, as described for event 304.

[0127] In some implementations, the new type of measurement configuration as described for events 304 and 324 is similar to an L3 measurement configuration. For example, the new type of measurement configuration includes a portion of the configuration parameters defined in the MeasConfig IE. In other implementations, the new type of measurement configuration as described for events 304 and 324 is similar to an L1 measurement configuration. For example, the new type of measurement configuration includes a portion of the configuration parameters defined in the CSI-MeasConfig IE (e.g., CSI-ResourceConfig IE and / or CSI-ReportConfig IE).

[0128] After receiving at least one measurement report in event 324 (e.g., in response to receiving at least one measurement report in the event), DU 174 sends 330 a first configuration activation command to UE 102 to activate configuration 1. For example, base station 104 sends the first configuration activation command on cell 124A. In another example, base station 104 sends the first configuration activation command on cell 124D. In some implementations, DU 174 includes ID 1 in the first configuration activation command. UE 102 determines and activates configuration 1 based on the first configuration activation command and ID 1. In other implementations, DU 174 includes cell index 1 (e.g., serving cell index) or cell ID 1 included in configuration 1 in the first configuration activation command. UE 102 determines and activates configuration 1 based on the first configuration activation command and cell index 1 or cell ID 1.

[0129] In yet other implementations, DU 174 includes a bitmap in the first configuration activation command to activate configuration 1, instead of including ID 1, cell ID 1, or cell index 1 (e.g., serving cell index). The number of bits in the bitmap is greater than or equal to "N". In some implementations, bits 1, ..., N correspond to configurations 1, ..., N, respectively, and DU 174 sets the corresponding bit in the bitmap (e.g., bit 1) to a first value to indicate ID 1 or configuration 1. In another implementation, bits 0, ..., N-1 correspond to configurations 1, ..., N, respectively, and DU 174 sets the corresponding bit in the bitmap (e.g., bit 0) to a first value to indicate ID 1 or configuration 1. Therefore, UE 102 can determine a specific ID or a specific configuration based on bit 1 or bit 0 set to the first value in the bitmap. In such implementations, DU 174 sets the remaining bits in the bitmap to a second value to indicate that the reset of configurations 1, ..., N is not activated. In some implementations, the first value is 1 and the second value is 0. In other implementations, the first value is 0 and the second value is 1. In some implementations, if DU 174 determines to activate another configuration (e.g., configuration K) in addition to configuration 1, DU 174 sets the corresponding bit in the bitmap (e.g., bit K or bit K-1) to the first value, where 1<=K<=N.

[0130] In some implementations, at least one measurement report (e.g., L1 measurement report or new type measurement report) of event 324 includes at least one measurement result for cell 124B. DU 174 determines to activate configuration 1 because at least one measurement result indicates that the signal strength or quality of cell 124B is higher than a second predetermined threshold. The second predetermined threshold is different from the first predetermined threshold. In some implementations, the second predetermined threshold is greater than the first predetermined threshold. In such implementations, at least one measurement report of event 324 indicates that the signal strength or quality of cell 124B is suitable for communication with UE 102. In another implementation, the second predetermined threshold is equal to the first predetermined threshold. In such implementations, at least one measurement report of event 324 indicates that the signal strength or quality of cell 124B has been continuously higher than the second predetermined threshold or the first predetermined threshold. This also indicates that cell 124B is suitable for communication with UE 102. Therefore, in response to the signal strength or quality of cell 124B being higher than the second predetermined threshold, DU 174 determines to activate configuration 1 (i.e., a fast serving cell change to cell 124B).

[0131] In some implementations, at least one measurement report (e.g., L3 measurement report) of events 324 and 326 includes at least one measurement result for cell 124B. CU 172 determines to activate configuration 1 because at least one measurement result indicates that the signal strength or quality of cell 124B is higher than a second predetermined threshold. The second predetermined threshold is different from the first predetermined threshold. In some implementations, the second predetermined threshold is greater than the first predetermined threshold. In such implementations, at least one measurement report of event 326 indicates that the signal strength or quality of cell 124B is suitable for communication with UE 102. In another implementation, the second predetermined threshold is equal to the first predetermined threshold. In such implementations, at least one measurement report of event 326 indicates that the signal strength or quality of cell 124B has been continuously higher than the second predetermined threshold or the first predetermined threshold. At least one measurement report also indicates that cell 124B is suitable for communication with UE 102. Therefore, CU 172 determines to activate configuration 1 (i.e., a fast serving cell change to cell 124B) in response to determining that the signal strength or quality of cell 124B is higher than the second predetermined threshold.

[0132] In response to the determination, CU 172 sends 328 a fourth CU-to-DU message to DU 174 to activate configuration 1. In response to the fourth CU-to-DU message, DU 174 sends 330 a first configuration activation command to UE 102, and in some implementations, sends a fourth DU-to-CU message to CU 172. In some implementations, CU 172 includes a cell index 1 (e.g., a serving cell index) in the fourth CU-to-DU message. Thus, in some such implementations, DU 174 determines to activate configuration 1 based on cell index 1. In other implementations, CU 172 includes cell ID 1 in the fourth CU-to-DU message. Thus, in some such implementations, DU 174 determines to activate configuration 1 based on cell ID. In yet other implementations, CU 172 includes ID 1 in the fourth CU-to-DU message. Thus, in some such implementations, DU 174 determines to activate configuration 1 based on ID 1. In some implementations, the fourth CU to DU message and the fourth DU to CU message are a UE context modification request message and a UE context modification response message, respectively. In other implementations, the fourth CU to DU message is a new interface message (e.g., an F1 application protocol (F1AP) message (e.g., defined in 3GPP specification 38.473 v18.0.0 and / or later versions)). In other implementations, the fourth DU to CU message is a new interface message (e.g., a new F1AP message (e.g., defined in 3GPP specification 38.473 v18.0.0 and / or later versions)).

[0133] In some implementations, when DU 174 determines to activate configuration 1 or sends a first configuration activation command as described above, DU 174 sends 329 a fifth DU to CU message to CU 172. In some implementations, CU 172 suspends or stops DL data transmission of UE 102 in response to the fifth DU to CU message. In another implementation, when suspending or stopping DL data transmission of UE 102, CU 172 buffers DL data of UE 102, and in another implementation, CU 172 receives the DL data from the core network or edge server. In some implementations, in the fifth DU to CU message, DU 174 indicates that a serving cell change has occurred (e.g., a serving cell change from cell 124A to cell 124B). In other implementations, in the fifth DU to CU message, DU 174 indicates that DL transmission of UE 102 is suspended or stopped.

[0134] In some implementations, the fifth DU to CU message is an existing F1AP message (e.g., defined in 3GPP specification 38.473). In other implementations, the fifth DU to CU message is a new F1AP message (e.g., defined in 3GPP specification 38.473 v18.0.0 and / or later). In still other implementations, the fifth DU to CU message is an existing frame (e.g., defined in 3GPP specification 38.474). In still other implementations, the fifth DU to CU message is a new frame (e.g., defined in 3GPP specification 38.474 v18.0.0 and / or later).

[0135] In some implementations, the first configuration activation command is a MAC CE included in a MAC PDU received by UE 102 from DU 174 in event 330. In some implementations, the MAC CE is a new MAC CE (e.g., defined in 3GPP specification 38.321 v18.0.0 and / or later versions). In some implementations, DU 174 includes a subheader identifying the MAC CE in the MAC PDU, and UE 102 identifies the MAC CE in the MAC PDU according to the subheader. In another implementation, the subheader includes a logical channel ID or an extended logical channel ID (e.g., defined in a 3GPP specification) for identifying the MAC CE. For example, the logical channel ID or the extended logical channel ID is newly defined (e.g., in 3GPP specification 38.321 v18.0.0 and / or later versions). In other implementations, the first configuration activation command is a DCI received by UE 102 on the PDCCH in event 330. DU 174 generates a CRC for the DCI, scrambles the CRC with the first C-RNTI of UE 102, and sends the DCI and the scrambled CRC on the PDCCH at event 330. In some implementations, the format of the DCI is an existing DCI format (e.g., defined in a 3GPP specification (e.g., 38.212)). In other implementations, the format of the DCI is a new DCI format (e.g., defined in a 3GPP specification (e.g., 38.212 v18.0.0 or later)).

[0136] In some implementations, DU 174 does not perform security protection (e.g., integrity protection and / or encryption) on the first configuration activation command. Avoiding performing such operations speeds up processing of the first configuration activation command in UE 102 because UE 102 does not spend time performing security checks (e.g., decryption and / or integrity checks) on the first configuration activation command.

[0137] In some implementations, after receiving the first configuration activation command, UE 102 sends 331 confirmation to DU 174 on cell 124A or cell 124D to indicate that UE 102 received the first configuration activation command. In some implementations, the confirmation is a HARQ ACK. In other implementations, the confirmation is a MAC CE. For example, the MAC CE is an existing MAC CE (e.g., defined in 3GPP specification 38.321 v17.1.0). In another example, the MAC CE is a new MAC CE (e.g., defined in 3GPP specification 38.321 v18.0.0 and / or later versions). In some other implementations, the confirmation is a PUCCH transmission.

[0138] In some implementations, CU 172 sends 316 an RRC reconfiguration message in response to the L3 measurement report for cell 124B received by CU 172 in event 306. In other implementations, CU 172 sends a first RRC reconfiguration message including a MeasConfig IE to UE 102 to configure UE 102 to send the L3 measurement report. In some implementations, DU 174 sends 330 a first configuration activation command in response to the L1 measurement report for cell 124B received by DU 174 in event 324. In other implementations, CU 172 sends a second RRC reconfiguration message including a CSI-MeasConfig IE to UE 102 to configure UE 102 to send the L1 measurement report. In some implementations, the first RRC reconfiguration message and the second RRC reconfiguration message are the same message (i.e., the same instance). In other implementations, the first RRC reconfiguration message and the second RRC reconfiguration message are different messages. In some implementations, the second RRC reconfiguration message is the RRC reconfiguration message of event 316. In other implementations, the second RRC reconfiguration message is different from the RRC reconfiguration message of event 316.

[0139] After receiving the first configuration activation command (e.g., in response to receiving the first configuration activation command), the UE 102 identifies a specific configuration (e.g., configuration 1) according to a specific ID (e.g., ID 1) and immediately applies configuration 1. In some implementations, the UE 102 performs 332 a random access procedure with the DU 174 on the cell 124B in response to applying configuration 1. In some implementations, after receiving the first configuration activation command or sending an acknowledgment (e.g., in response to receiving the first configuration activation command or sending an acknowledgment), the UE 102 disconnects from the cell 124A. In other words, after receiving 330 the first configuration activation command or sending 331 an acknowledgment (e.g., in response to receiving the first configuration activation command or sending an acknowledgment), the UE 102 stops communicating on the cell 124A. In such a case, the UE 102 performs 332 a random access procedure after being disconnected from the cell 124A. In some implementations, the UE 102 determines whether to perform a random access procedure according to configuration 1. In some implementations, if configuration 1 configures UE 102 to perform a random access procedure, UE 102 performs a random access procedure in event 332. For example, configuration 1 includes a reconfiguration with a synchronization configuration (e.g., ReconfigurationWithSyncIE) to configure UE 102 to perform a random access procedure. Otherwise, if configuration 1 does not configure UE 102 to perform a random access procedure or configures UE 102 to skip a random access procedure, UE 102 avoids performing a random access procedure with DU 174 after receiving the first configuration activation command. In such a case, UE 102 skips event 316. For example, if configuration 1 excludes a reconfiguration with a synchronization configuration, configuration 1 configures UE 102 not to perform a random access procedure. In some implementations, the random access procedure is a four-step random access procedure. In other implementations, the random access procedure is a two-step random access procedure. In some implementations, the random access procedure is a contention-free random access procedure. In other implementations, the random access procedure is a contention-based random access procedure.

[0140] In the case where the UE 102 performs 332 a random access procedure, the UE 102 communicates 336 with the DU 174 on the cell 124B using configuration 1, and communicates with the CU 172 via the DU 174 after successfully completing the random access procedure. For example, in event 318, the UE 102 communicates UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104. In such a case, when the UE 102 receives a contention resolution from the DU 174, the UE 102 successfully completes the random access procedure. In the case where the random access procedure is a four-step random access procedure, the UE 102 sends a message 3 including a UE identity to the DU 174 via the cell 124B during the random access procedure. In the case where the random access procedure is a two-step random access procedure, the UE 102 sends a message A including a UE identity to the DU 174 via the cell 124B during the random access procedure. In some implementations, if configuration 1 includes a second C-RNTI, the UE identity is the second C-RNTI of UE 102. Otherwise, if configuration 1 does not include a C-RNTI, the UE identity is the first C-RNTI. In the case where the random access procedure is a contention-free random access procedure, UE 102 sends a dedicated random access preamble to DU 174 via cell 124B. In such a case, configuration 1 includes a dedicated random access preamble.

[0141] Upon receiving the UE identification or dedicated preamble from the UE 102 during the random access procedure, the DU 174 identifies or determines that the UE 102 is connected to the cell 124B.

[0142] In some implementations, the UE 102 sends an RRC message (e.g., an RRC reconfiguration complete message) to the CU 172 via the DU 174 and the cell 124B to indicate that the UE 102 has applied configuration 1. In some implementations, the UE 102 includes the RRC message in message 3. In other implementations, the UE 102 includes the RRC message in message A. In still other implementations, the UE 102 sends the RRC message after completing the random access procedure. In other implementations, if the UE 102 maintains communication with the base station 104 on the cell 124A (i.e., the UE 102 is not disconnected from the cell 124A), the UE 102 sends the RRC message to the base station 104 via the cell 124A. In still other implementations, the UE 102 avoids sending an RRC message to the base station 104 in response to applying configuration 1 or receiving the first configuration activation command.

[0143] In some cases where the UE 102 skips the random access procedure, after receiving the first configuration activation command (e.g., in response to receiving the first configuration activation command), the UE 102 communicates 336 directly with the base station 104 on the cell 124B according to configuration 1. For example, in event 318, the UE 102 communicates UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104. In some such cases, after receiving the first configuration activation command (e.g., in response to receiving the first configuration activation command), the UE 102 sends 336 at least one PUCCH transmission to the DU 174 on the cell 124B according to configuration 1. In some implementations, after sending the first configuration activation command, the DU 174 sends at least one DCI on the PDCCH on the cell 124B to the UE 102 to command the UE 102 to send at least one PUCCH or PUSCH transmission. Upon receiving the PUCCH or PUSCH transmission, the DU 174 identifies or determines that the UE 102 is connected to the cell 124B. In other implementations, the UE 102 sends at least one PUCCH or PUSCH transmission regardless of whether a DCI is received on the PDCCH on the cell 124B. Upon receiving the PUCCH or PUSCH transmission, the DU 174 identifies or determines that the UE 102 is connected to the cell 124B. In some implementations, the UE 102 sends an RRC message (e.g., an RRC reconfiguration complete message) to the CU 172 via the DU 174 and the cell 124B to indicate that the UE 102 has applied configuration 1. Upon receiving the RRC message, the CU 172 identifies or determines that the UE 102 is connected to the cell 124B. In other implementations, if UE 102 maintains communication with base station 104 on cell 124A (i.e., UE 102 is not disconnected from cell 124A), UE 102 sends an RRC message to base station 104 via cell 124A. In still other implementations, UE 102 avoids sending an RRC message to base station 104 in response to applying configuration 1 or receiving a first configuration activation command.

[0144] In some implementations, when DU 174 determines that UE 102 is successfully connected to cell 124B in event 332 or 336, DU 174 sends 334 a DU to CU message (e.g., an access success message) to CU 172. In some implementations, DU 174 includes the cell ID of cell 124B in the DU to CU message of event 334. Depending on the implementation, the cell ID is a PCI or a CGI. Therefore, upon receiving the DU to CU message of event 334, CU 172 determines that UE 102 is connected to cell 124B. In another implementation, when DU 174 determines that UE 102 is successfully connected to cell 124B in event 332 or 336, DU 174 sends a DL data delivery status message or frame to CU 172. In some implementations, when CU 172 receives 334 the DU to CU message, CU 172 resumes or continues DL data transmission of UE 102. In another implementation, after resuming or continuing DL data transmission of UE 102 (e.g., in response to resuming or continuing DL data transmission of the UE), CU 172 sends the DL data of UE 102 to DU 174, which in turn sends the DL data to UE 102 at event 336.

[0145] In some implementations, when it is determined that the UE 102 is connected to the cell 124B, a first configuration activation command is sent 330, or an acknowledgement is received 331, the DU 174 stops communicating with the UE 102 on the cell 124A. In some implementations, when it is determined that the UE 102 is connected to the cell 124B, a first configuration activation command is sent 330, or an acknowledgement is received 331, the DU 174 releases the resources of the cell 124A configured for the UE 102.

[0146] Events 304, 306, 390, 392, 316, 318, 320, 322 Figure 3 The process 380 is collectively referred to as the serving cell configuration process. Events 324, 326, 328, 330, 331, 332, 334, 336, 394 are Figure 3 It is collectively referred to as the service cell change process 382.

[0147] In some implementations, DU 174 generates configuration 1 and / or configuration 2, ..., N as a complete configuration that replaces the first configuration or a specific configuration in the first configuration. In some implementations, if configuration 1 is a complete configuration, UE 102 and DU 174 communicate 336 with each other according to configuration 1 instead of the first configuration or the specific configuration. In some implementations, DU 174 includes an indication that configuration 1 is a complete configuration in configuration 1. In other implementations, the RRC reconfiguration message of events 316, 318 includes an indication that configuration 1 is a complete configuration. In some other implementations, the first container includes an indication that configuration 1 is a complete configuration. In some other implementations, element 1 (e.g., ConfigToAddMod IE, CellGroupConfigToAddMod, MobilityToAddMod IE, MobilityConfigToAddMod IE or CellGroupConfigToAddMod IE) includes an indication that configuration 1 is a complete configuration. In some implementations, UE 102 determines that configuration 1 is a complete configuration based on the indication that configuration 1 is a complete configuration. In some implementations, the indication of configuration 1 is different from the fullConfig field (e.g., defined in the current 3GPP specification). In other implementations, the indication of configuration 1 is the fullConfig field (e.g., defined in the current 3GPP specification) in the RRCReconfiguration message.

[0148] In other implementations, DU 174 generates configuration 1 and / or configuration 2, ..., N as an incremental configuration that enhances at least a portion of the first configuration. In other words, DU 174 generates configuration 1, ..., N on top of the first configuration. For example, if configuration 1 is an incremental configuration, UE 102 and DU 174 enhance at least a portion of the first configuration with configuration 1. Therefore, UE 102 and base station 104 communicate 336 with each other based on configuration 1 and the unenhanced portion of the first configuration. In some implementations, configuration 1 includes an indication that configuration 1 is an incremental configuration. In other implementations, the first container includes an indication that configuration 1 is an incremental configuration. In yet other implementations, element 1 includes an indication that configuration 1 is an incremental configuration. In some implementations, UE 102 determines that configuration 1 is a full configuration based on the indication that configuration 1 is an incremental configuration. In some alternative implementations, configuration 1, the first container, or element 1 excludes the indication that configuration 1 is a full configuration to indicate that configuration 1 is an incremental configuration. In another implementation, UE 102 determines that configuration 1 is an incremental configuration based on determining that the indication is excluded in configuration 1, the first container, or element 1.

[0149] In some implementations, if configuration 1 is a full configuration, after receiving 330 a first configuration activation command, sending 331 an acknowledgement, successfully performing 332 a random access procedure, or receiving a first DCI on a PDCCH addressed to a UE identity of UE 102 on cell 124B (e.g., in response to receiving a first configuration activation command, sending an acknowledgement, successfully performing a random access procedure, or receiving a first DCI on a PDCCH addressed to a UE identity of the UE on the cell), UE 102 releases the first configuration or a specific configuration in the first configuration. In some implementations, if configuration 1 is a full configuration, after sending 330 a first configuration activation command, receiving 331 an acknowledgement, successfully performing 332 a random access procedure, or receiving a specific transmission from UE 102 on cell 124B (e.g., in response to sending a first configuration activation command, receiving an acknowledgement, successfully performing a random access procedure, or receiving a specific transmission from the UE on the cell), DU 174 releases the first configuration or a specific configuration in the first configuration. In some implementations, the specific transmission is a PUCCH transmission. In other implementations, the transmission is a PUSCH transmission. In some implementations, after sending the first configuration activation command, DU 174 generates a DCI and a CRC for the DCI, scrambles the CRC with the UE identity of UE 102, and sends the DCI and the scrambled CRC on the PDCCH on cell 124B. When UE 102 receives the DCI and the scrambled CRC and verifies that the scrambled CRC is valid using the UE identity, UE 102 sends a PUSCH transmission to DU 174 on cell 124B.

[0150] In some implementations, the first configuration or the specific configuration is a first CellGroupConfig IE (ie, the first configuration includes configuration parameters defined in the first CellGroupConfig IE), and Configuration 1 is a second CellGroupConfig IE.

[0151] In some implementations, the UE 102 uses a UE MAC entity (e.g., MAC 204B) to communicate with the DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). In some implementations, the base station 104 configures whether the UE 102 resets the UE MAC entity after receiving the first configuration activation command. In some implementations, the base station 104 includes a MAC reset indication in configuration 1 or element 1 to configure the UE 102 to reset the UE MAC entity, and excludes the MAC reset indication in configuration 1 or element 1 to configure the UE 102 not to reset the UE MAC entity. If configuration 1 or element 1 includes a MAC reset indication, after receiving the first configuration activation command, the UE 102 resets the UE MAC entity in response to the MAC reset indication.

[0152] Otherwise, if configuration 1 or element 1 does not include a MAC reset indication, then upon receiving the first configuration activation command or upon receiving the first configuration activation command, the UE 102 avoids resetting the UE MAC entity. In some implementations, if configuration 1 or element 1 does not include a MAC reset indication and includes an indication that the configuration is a full configuration, then upon receiving 330 the first configuration activation command or upon receiving the first configuration activation command, the UE 102 resets the UE MAC entity. Otherwise, if configuration 1 or element 1 does not include a MAC reset indication and an indication that the configuration is a full configuration, then upon receiving 330 the first configuration activation command or upon receiving the first configuration activation command, the UE 102 avoids resetting the UE MAC entity.

[0153] In some implementations, the base station 104 (e.g., DU 174 or CU 172) uses a DU MAC entity (e.g., NRMAC 204B) to communicate with the UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If the base station 104 includes a MAC reset indication in configuration 1 or element 1, then after sending 330 a first configuration activation command, receiving 331 an acknowledgement, or determining in events 332 or 336 that the UE 102 is connected to the cell 124B, the DU 174 resets the DU MAC entity in response to the MAC reset indication.

[0154] Otherwise, if configuration 1 or element 1 does not include a MAC reset indication, then after sending 330 the first configuration activation command (e.g., in response to sending the first configuration activation command), DU 174 avoids resetting the DU MAC entity. Therefore, after sending 330 the first configuration activation command, receiving 331 an acknowledgement, or determining in event 332 or 336 that UE 102 is connected to cell 124B, DU 174 continues to communicate with UE 102 using the retained (i.e., non-reset) DU MAC entity.

[0155] In some implementations, the DU 174 includes a MAC reset indication in a MAC-CellGroupConfig IE in Configuration 1 (e.g., CellGroupConfig IE). In other implementations, the DU 174 includes a MAC reset indication in the CellGroupConfig IE and outside the MAC-CellGroupConfig IE. In still other implementations, the DU 174 includes a MAC reset indication in Element 1 and outside Configuration 1.

[0156] In some implementations, if configuration 1 or element 1 does not include a MAC reset indication and includes an indication that configuration 1 is a full configuration, then after sending 330 the first configuration activation command, receiving 331 an acknowledgement, or determining that UE 102 is connected to cell 124B in event 332 or 336, DU 174 resets the DU MAC entity. Alternatively, DU 174 releases the DU MAC entity and establishes a new DU MAC entity to communicate with UE 102 via cell 124B, rather than resetting the DU MAC entity. Otherwise, if configuration 1 or element 1 does not include a MAC reset indication and an indication that configuration 1 is a full configuration, then after sending 330 the first configuration activation command (e.g., in response to sending the first configuration activation command), DU 174 avoids resetting the DU MAC entity.

[0157] In an alternative implementation, the base station 104 (e.g., DU 174 or CU 172) includes a MAC retention indication in a configuration or element (e.g., configuration 1 or element 1) to configure the UE 102 not to reset the UE MAC entity, and the base station 104 excludes the MAC retention indication in the configuration or element to configure the UE 102 to reset the UE MAC entity. If the configuration or element includes the MAC retention indication, upon receiving a configuration activation command (e.g., a first configuration activation command), the UE 102 avoids resetting the UE MAC entity in response to the MAC retention indication. Otherwise, if the configuration or element does not include the MAC retention indication, upon receiving the configuration activation command or upon receiving the configuration activation command, the UE 102 resets the UE MAC entity.

[0158] DU 174 uses a DU MAC entity (e.g., NR MAC 204B) to communicate with UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If base station 104 includes a MAC retention indication in a configuration or element (e.g., configuration 1 or element 1), then after sending a configuration activation command (e.g., a first configuration activation command) to UE 102, DU 174 avoids resetting the DU MAC entity in response to the MAC retention indication. Therefore, after sending 330 the first configuration activation command, receiving 331 an acknowledgment, or determining at events 332 or 336 that UE 102 is connected to cell 124B, DU 174 continues to use the retained (i.e., non-reset) DU MAC entity to communicate with UE 102.

[0159] In some implementations, the DU 174 includes the MAC reservation indication in the MAC-CellGroupConfig IE in Configuration 1 (e.g., CellGroupConfig IE). In other implementations, the DU 174 includes the MAC reservation indication in the CellGroupConfig IE and outside the MAC-CellGroupConfig IE. In still other implementations, the DU 174 includes the MAC reservation indication in Element 1 and outside Configuration 1.

[0160] Otherwise, if configuration 1 or element 1 does not include a MAC retention indication, then after sending 330 the first configuration activation command (eg, in response to sending the first configuration activation command), the DU 174 resets the DU MAC entity.

[0161] In some implementations, the base station 104 includes or does not include an indication that configuration 1 is a complete configuration. If the base station 104 includes an indication in configuration 1 or element 1 that configuration 1 is a complete configuration, the base station 104 avoids including a MAC reservation indication in configuration 1 or element 1. Otherwise, in another implementation, if the base station 104 does not include an indication in configuration 1 or element 1 that configuration 1 is a complete configuration, the base station 104 includes a MAC reservation indication in configuration 1 or element 1.

[0162] In some alternative implementations, the base station 104 (e.g., DU 174 or CU 172) includes a MAC partial reset indication in a configuration or element (e.g., configuration 1 or element 1) to configure the UE 102 to partially reset the UE MAC entity, and the base station 104 excludes the MAC partial reset indication in the configuration or element to configure the UE 102 to completely reset the UE MAC entity. If the configuration or element includes the MAC partial reset indication, then after receiving a configuration activation command (e.g., a first configuration activation command), the UE 102 partially resets the UE MAC entity. Otherwise, if the configuration or element does not include the MAC partial reset indication, then after receiving the configuration activation command (e.g., in response to receiving the configuration activation command), the UE 102 completely resets the UE MAC entity. In some implementations, when the UE partially resets the UE MAC entity, the UE 102 retains (e.g., maintains or preserves) the operational state of the UE MAC entity, or in some implementations, omits one or more actions performed by the UE 102 when the UE 102 fully resets the UE MAC entity.

[0163] If the base station 104 includes a MAC partial reset indication in a configuration or element (e.g., configuration 1 or element 1), then after sending a configuration activation command (e.g., a first configuration activation command) to the UE 102, the DU 174 partially resets the DU MAC entity in response to the MAC partial reset indication.

[0164] In some implementations, the DU 174 includes the MAC partial reset indication in the MAC-CellGroupConfig IE in Configuration 1 (e.g., CellGroupConfig IE). In other implementations, the DU 174 includes the MAC partial reset indication in the CellGroupConfig IE and outside the MAC-CellGroupConfig IE. In still other implementations, the DU 174 includes the MAC partial reset indication in Element 1 and outside Configuration 1.

[0165] Otherwise, if Configuration 1 or Element 1 does not include a MAC partial reset indication, then after sending 330 the first configuration activation command (eg, in response to sending the first configuration activation command), the DU 174 completely resets the DU MAC entity.

[0166] In some implementations, the base station 104 includes or does not include an indication that configuration 1 is a complete configuration. In some implementations, if the base station 104 includes an indication in configuration 1 or element 1 that configuration 1 is a complete configuration, the base station 104 avoids including a MAC partial reset indication in configuration 1 or element 1. Otherwise, in another implementation, if the base station 104 does not include an indication in configuration 1 or element 1 that configuration 1 is a complete configuration, the base station 104 includes a MAC partial reset indication in configuration 1 or element 1. In some alternative implementations, in the case where the base station 104 includes an indication in configuration 1 or element 1 that configuration 1 is a complete configuration, the base station 104 includes a MAC partial reset indication.

[0167] In some implementations, the base station 104 (e.g., DU 174 or CU 172) does not include an indication related to resetting the UE MAC entity in a configuration or element (e.g., configuration 1 or element 1) or an RRC message (e.g., events 316, 318) including the configuration or element. In such a case, the UE 102 partially resets the UE MAC entity after receiving the first configuration activation command (e.g., in response to receiving the first configuration activation command). In such a case, the DU 174 partially resets the DU MAC entity after sending the first configuration activation command, receiving 331 an acknowledgment, performing 336 a random access procedure with the UE 102, or determining that the UE 102 is connected to the cell 124B.

[0168] In some implementations, when the UE 102 resets or determines to reset the UE MAC entity as described above, the UE 102 resets the UE MAC entity before performing 332 a random access procedure or communicating 336 with the base station 104 via the cell 124B. In some implementations, when the UE 102 resets the UE MAC entity, the UE 102 performs at least one of the following actions for the UE MAC entity (i.e., a UE MAC reset or a complete UE MAC reset): (i) initializes Bj of the configured logical channel to zero; (ii) stops one or more timers; (iii) if the UE is configured in a configuration (e.g., configuration 1), the UE 102 resets the UE MAC entity. 102 is configured to perform a random access procedure (e.g., event 332), then the timeAlignmentTimer is considered to have expired; (iv) the new data indicator (NDI) of the UL HARQ process is set to a value of 0; (v) the NDI of the HARQ process ID is set to a value of 0 for monitoring the PDCCH in sidelink resource allocation mode 1; (vi) the Msg3 buffer is flushed; (vii) the MSGA buffer is flushed; (viii) the triggered scheduling request procedure (if any) is canceled; (ix) the triggered buffer status report procedure (if any) is canceled; (x) the triggered power headroom report procedure (if any) is canceled; (xi) the triggered consistent LBT failure (if any) is canceled; (x ii) cancel the triggered BFR (if any); (xiii) cancel the triggered sidelink buffer status report process (if any); (xiv) cancel the triggered preemptive buffer status report process (if any); (xv) cancel the triggered timing advance reporting process (if any); (xvi) cancel the triggered recommended bit rate query process (if any); (xvii) cancel the triggered configured uplink grant confirmation (if any); (xviii) cancel the triggered configured sidelink grant confirmation (if any); (xix) cancel the triggered expected protection symbol query (if any); (xx) cancel the triggered positioning measurement gap activation / deactivation request process (if any); (xxi) refresh DL soft buffer of the HARQ process; (xxii) for each DL HARQ process in the DL HARQ process, treat the next received transmission of the TB as the initial transmission; (xxiii) release the temporary C-RNTI (if any); (xiv) reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER); (xxv), etc.

[0169] In some implementations, when DU 174 resets the DU MAC entity, DU 174 performs at least one of the following actions for the DU MAC entity (i.e., a DU MAC reset or a full DU MAC reset): (i) stop one or more timers; (ii) if UE 102 is configured to perform a random access process (e.g., event 332) in the configuration (e.g., configuration 1), consider the timeAlignmentTimer started and / or maintained by DU 174 for UE 102 to have expired; (iii) set the NDI of the DL HARQ process to a value of 0; (iv) refresh the soft buffer of the UL HARQ process; (v) for each UL HARQ process in the UL HARQ process, treat the next received transmission of the TB as the initial transmission; (vi) reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER); (vii), etc.

[0170] Depending on the implementation, the UE 102 determines to partially or completely reset the UE MAC entity. In some implementations, when the UE 102 resets the UE MAC entity as described above, the UE 102 completely resets the UE MAC entity (i.e., a complete UE MAC reset). In a complete UE MAC reset, the UE 102 performs some or all of the above actions. In other implementations, when the UE 102 resets the UE MAC entity as described above, the UE 102 partially resets the UE MAC entity (i.e., a partial UE MAC reset). In a partial UE MAC reset, the UE 102 performs a subset or a portion of some or all of the actions in the complete UE MAC reset.

[0171] In some implementations, the partial UE MAC reset includes at least one of the following actions: (i) if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), the timeAlignmentTimer of UE 102 is considered expired; (ii) the Msg3 buffer is flushed; (iii) the MSGA buffer is flushed; (iv) the temporary C-RNTI (if any) is released; and / or (v) one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER) are reset.

[0172] In some implementations, the partial UE MAC reset also includes at least one of the following actions: (i) cancelling the triggered scheduling request process (if any); (ii) cancelling the triggered buffer status reporting process (if any); (iii) cancelling the triggered power headroom reporting process (if any); (iv) cancelling the triggered consistent LBT failure (if any); (v) cancelling the triggered BFR (if any); (vi) cancelling the triggered sidelink buffer status reporting process (if any); (vii) cancelling the triggered preemptive buffer status reporting process (if any); (viii) cancelling the triggered timing advance reporting process (if any); (ix) cancelling the triggered recommended bit rate query process (if any); (x) cancelling the triggered configured uplink grant confirmation (if any); (xi) cancelling the triggered configured sidelink grant confirmation (if any); (xii) cancelling the triggered expected protection symbol query (if any); and / or (xiii) cancelling the triggered positioning measurement gap activation / deactivation request process (if any).

[0173] In some implementations, the partial UE MAC reset also includes at least one of the following actions: (i) stopping a first portion of one or more timers and retaining the remainder of one or more timers; (ii) setting a new data indicator (NDI) for the UL HARQ process to a value of 0; (iii) setting the NDI for the HARQ process ID to a value of 0 for monitoring the PDCCH in sidelink resource allocation mode 1; (iv) flushing soft buffers for the DL HARQ processes; and / or (v) for each DL HARQ process in the DL HARQ processes, treating the next received transmission of the TB as the initial transmission.

[0174] Depending on the implementation, DU 174 determines to partially or completely reset the DU MAC entity. In some implementations, when DU 174 resets the DU MAC entity as described above, DU 174 completely resets the DU MAC entity (i.e., a complete DU MAC reset). In a complete DU MAC reset, DU 174 performs some or all of the above actions. In other implementations, when DU 174 resets the DU MAC entity as described above, DU 174 partially resets the DU MAC entity (i.e., a partial DU MAC reset). In a partial DU MAC reset, DU 174 performs a subset or a portion of some or all of the actions in a complete DU MAC reset.

[0175] In some implementations, the partial DU MAC reset includes at least one of the following actions in the partial MAC reset: (i) if UE 102 is configured to perform a random access procedure (e.g., event 332) in a configuration (e.g., configuration 1), then the timeAlignmentTimer started and / or maintained by DU 174 for UE 102 is deemed to have expired; and / or (ii) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0176] In some implementations, the partial DU MAC reset includes at least one of the following actions for the MAC entity (i.e., the DU MAC reset): (i) stopping a first portion of one or more timers and retaining the remainder of one or more timers; (ii) setting the NDI of the DL HARQ process to a value of 0; (iii) flushing the soft buffers of the UL HARQ processes; (iv) for each UL HARQ process in the UL HARQ processes, treating the next received transmission of the TB as the initial transmission; and / or (v) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0177] In some implementations, configuration 1 includes or does not include one or more RLC reestablishment indications (e.g., reestablishRLC fields) that configure the UE 102 to reestablish one or more RLC entities (e.g., RLC 206B) that the UE 102 uses to communicate with the DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If configuration 1 includes an RLC reestablishment indication that configures the UE 102 to reestablish the RLC entity (e.g., RLC 206B) that the UE 102 uses to communicate the RLC PDU (e.g., events 302, 304, 318, 320, 324, 330, and / or 331) with the base station 104, the UE 102 reestablishes the RLC entity in response to the RLC reestablishment indication. In some implementations, the UE 102 reestablishes the RLC entity before performing 332 a random access procedure or communicating 336 with the base station 104 via the cell 124B. In other implementations, upon or after performing 332 the random access procedure, the UE 102 reestablishes the RLC entity. In some implementations, when the UE 102 reestablishes the RLC entity, the UE 102 performs at least one of the following actions for the RLC entity: (i) discarding the RLC SDU, RLC SDU fragment, and RLC PDU (if any); (ii) stopping and resetting the timer (if running); (iii) resetting the state variable to an initial value. In some implementations, the state variables and timers are currently defined (e.g., in 3GPP specification 38.322).

[0178] Otherwise, if configuration 1 does not include an RLC re-establishment indication for the RLC entity, upon or upon receiving the first configuration activation command, the UE 102 refrains from re-establishing the RLC entity. In other words, upon or upon receiving the first configuration activation command, the UE 102 refrains from performing actions for re-establishing the RLC entity of the UE 102. In some implementations, if configuration 1 or element 1 does not include an RLC re-establishment indication and includes an indication that configuration 1 is a complete configuration, upon or upon receiving the first configuration activation command, the UE 102 re-establishes the RLC entity of the UE 102. Otherwise, if configuration 1 or element 1 does not include an RLC re-establishment indication and an indication that configuration 1 is a complete configuration, upon or upon receiving the first configuration activation command, the UE 102 refrains from re-establishing the RLC entity.

[0179] Similarly, DU 174 reestablishes the RLC entity (e.g., NR RLC 206B) used by DU 174 to communicate with the RLC entity of UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331) in response to the RLC reestablishment indication. In some implementations, DU 174 reestablishes the RLC entity after sending the first configuration activation command, receiving an acknowledgment for the first configuration activation command from UE 102, or determining that UE 102 is connected to cell 124B. In some implementations, the acknowledgment is a HARQ ACK. In other implementations, the acknowledgment is a MAC CE. In yet other implementations, the acknowledgment is a PUCCH transmission. In some implementations, when the base station 104 reestablishes the RLC entity, the DU 174 performs at least one of the following actions for the RLC entity: (i) discarding the RLC SDU, RLC SDU fragment, and RLC PDU (if any); (ii) stopping and resetting the timer (if running); and / or (iii) resetting the state variables to initial values. In some implementations, the state variables and timers are currently defined (e.g., in 3GPP specification 38.322).

[0180] In some implementations, the description above for Configuration 1 also applies to Configuration 2, ..., N.

[0181] In some implementations, after determining that UE 102 is connected to cell 124B (e.g., in response to determining that the UE is connected to the cell), CU 172 sends 338 a CU-to-DU message (e.g., a UE context modification request message) to DU 174 to instruct DU 174 to cease communicating with UE 102 and / or release or suspend resources of cell 124A configured for UE 102. In other implementations, in response, DU 174 ceases communicating with UE 102 on cell 124A, releases or suspends resources of cell 124A configured for UE 102, and / or sends 340 a DU-to-CU message (e.g., a UE context modification response message) to CU 172. Events 338 and 340 are described in detail below. Figure 3 The process is collectively referred to as process 394 (e.g., UE context modification process).

[0182] Next reference Figure 4In scenario 400, base station 104 includes CU 172, source DU (S-DU) 174A, and target DU (T-DU) 174B. S-DU 174A operates cell 124A, and in some implementations, operates cell 124B, while T-DU 174B operates cell 124C. Scenario 400 is similar to scenario 300. Therefore, the description of scenario 300 can generally apply to scenario 400. Specifically, the description of cell 124B in scenario 300 can be applied to cell 124C. Events 404, 406, 490, 492, 416, 418, 420, 422 are described in detail in FIG. Figure 4 The process 480 is collectively referred to as the serving cell configuration process. Events 424, 426, 428, 430, 431, 432, 434, 436, 494 are Figure 4 It is collectively referred to as the service cell change process 482.

[0183] In some implementations, after determining that the UE 102 is connected to the cell 124C (e.g., in response to determining that the UE is connected to the cell), the CU 172 sends 438 a CU-to-DU message (e.g., a UE context release command message) to the S-DU 174A to release the UE context of the UE 102. In response, the S-DU 174A releases the UE context of the UE 102 and sends 440 a DU-to-CU message (e.g., a UE context release complete message) to the CU-172. Alternatively, the CU 172 sends 438 a CU-to-DU message (e.g., a UE context modification request message) to the S-DU 174A to instruct the S-DU 174A to stop communicating with the UE 102 and / or to release or suspend resources of the cell 124A configured for the UE 102. In some such implementations, in response, the S-DU 174A ceases communicating with the UE 102 on the cell 124A, releases or suspends resources of the cell 124A configured for the UE 102, and / or sends 440 a DU to CU message (e.g., a UE Context Modification Response message) to the CU-172.

[0184] Next reference Figure 5A, in scenario 500A, base station 106 operates as a MN and base station 104 operates as a SN. SN 104 includes CU 172 and DU 174. Scenario 500A is similar to scenario 300, except that scenario 500A is a DC scenario, while scenario 300 is a single connectivity (SC) scenario. Initially, UE 102 communicates with MN 106 and SN 104 in DC. In event 502, UE 102 communicates with DU 174 on cell 124A using a first configuration, and communicates with CU 172 via DU 174, similar to event 302. In some implementations, UE 102 communicates 502 UL PDUs and / or DL ​​PDUs with MN 106 and / or SN 104 in DC via a radio bearer, which in some other implementations includes SRBs and / or DRBs. In another implementation, the MN 106 and / or the SN 104 configure a radio bearer to the UE 102. The UE 102 communicates 502 UL PDUs and / or DL ​​PDUs with the SN 104 in DC over the SCG that the SN 104 configures for communication with the UE 102. The UE 102 communicates UL PDUs and / or DL ​​PDUs with the MN 106 in DC over the MCG according to the MN configuration (i.e., the MCG configuration). In some implementations, the first configuration is the SN configuration (i.e., the SCG configuration). In the MN configuration, the MN 106 configures an MCG that includes at least one serving cell (e.g., cell 126 and / or other cells) operated by the MN 106. In the first configuration, the SN 106A configures an SCG that includes at least one serving cell (e.g., cell 124A and / or other cells) operated by the SN 104. In some implementations, the MN configuration includes a plurality of configuration parameters, and UE 102 receives the configuration parameters in one or more RRC messages from MN 106. In other implementations, the first configuration includes a plurality of configuration parameters, and UE 102 receives the configuration parameters in one or more RRC messages from SN 104 (e.g., via MN 106), or receives the configuration parameters on an SRB (e.g., SRB3) configured by MN 106 or SN 104 for exchanging RRC messages between UE 102 and SN 104.

[0185] In some implementations, when communicating with MN 106 and SN 104 in DC, MN 106 performs 580 a fast serving cell configuration procedure with UE 102, similar to process 380. In some implementations, when communicating with MN 106 and SN 104 in DC, UE 102 sends at least one measurement report to CU 172 via DU 174 and cell 124A in events 504 and 506, similar to events 304 and 306, respectively. In other implementations, when communicating with MN 106 and SN 104 in DC, UE 102 sends 505 at least one measurement report to MN 106 via cell 126. MN 106 in turn sends 507 at least one measurement report to CU 172. In some implementations, MN 106 generates at least one SN message including at least one measurement report, and sends at least one SN message to CU 172 in event 507. In some implementations, the at least one SN message includes an RRC transfer message and / or an SN modification request message.

[0186] After receiving at least one measurement report (e.g., in response to receiving at least one measurement report) or while base station 104 is communicating with UE 102, base station 104 determines to prepare cell 124B for UE 102, such as for Figure 3 Events 590, 592, 516, 518, 520, 522, 524, 526, 528, 530, 531, 532, 534, 536, and 594 are similar to events 390, 392, 316, 318, 320, 322, 324, 326, 328, 330, 331, 332, 334, 336, and 394, respectively. After receiving the first configuration activation command, sending an acknowledgment, or determining that UE 102 is connected to cell 124B, UE 102 operating with MN 106 and SN 104 in DC communicates 536 with SN 104 on cell 124B according to configuration 1, similar to event 336.

[0187] Events 504, 506, 505, 507, 590, 592, 516, 518, 520, 522 Figure 5A Events 524, 526, 528, 530, 531, 532, 534, 536, 594 are collectively referred to as serving cell configuration process 581A. Figure 5A This is collectively referred to as the service cell change process 583.

[0188] Next reference Figure 5BScenario 500B is substantially similar to scenario 500A, except that SN 104 sends 517, 519 RRC reconfiguration messages to UE 102 via MN 106, and receives 521, 523 RRC reconfiguration complete messages from UE 102 via MN 106. In some implementations, SN 104 generates a first SN message (e.g., an SN modification required message, an SN modification required message, or an RRC transfer message) including an RRC reconfiguration message, and sends the first SN message to MN 106 at event 517. In some implementations, MN 106 generates a second SN message (e.g., an SN reconfiguration complete message or an RRC transfer message) including an RRC reconfiguration complete message, and sends the second SN message to SN 104 at event 523.

[0189] Events 504, 506, 505, 507, 590, 592, 517, 519, 521, 523 Figure 5B It is collectively referred to as the service cell configuration process 581B.

[0190] Next reference Fig. 6A In scenario 600A, base station 106 operates as a MN and base station 104 operates as a SN, similar to scenarios 300-500B. SN 104 includes CU 172, S-DU 174A, and T-DU 174B, similar to base station 104 in scenario 400. Events 604, 606, 605, 607, 690, 692, 616, 618, 620, 622 are Fig. 6A Events 624, 626, 628, 630, 631, 632, 634, 636, and 694 are collectively referred to as serving cell configuration process 681A. Fig. 6A The serving cell change process is collectively referred to as 683. In addition, it should be understood that some of the descriptions regarding scenarios 300-500B may apply to scenario 600A, but apply to one or both of S-DU 174A or T-DU 174B (e.g., events 608, 610, 632, 634, etc.).

[0191] Next reference Figure 6B Scenario 600B is similar to scenarios 300-500B and 600A, except that SN 104 sends 617, 619 RRC reconfiguration messages to UE 102 via MN 106, and receives 621, 623 RRC reconfiguration complete messages from UE 102 via MN 106. Events 604, 606, 605, 607, 690, 692, 617, 619, 621, 623 are Figure 6B This is collectively referred to as the service cell configuration process 681B.

[0192] Next reference Fig. 7A In scenario 700A, base station 104 operates as a MN and a SN, similar to scenarios 300-600B. Base station 104 includes CU 172, a master DU (M-DU) 174A, and a secondary DU (S-DU) 174B. CU 172 and M-DU 174A operate together as a MN, similar to Figure 3 Base station 104 or FIG. 5A to FIG. 6B MN 106 in, and CU 172 operates together with S-DU 174B as a SN, similar to FIG. 5A to FIG. 6B SN 104 in.

[0193] In scenario 700A, UE 102 initially communicates 702 with M-DU 174A and S-DU 174B in DC, and communicates 702 with CU 172 via M-DU 174A and S-DU 174B. At event 702, UE 102 communicates with S-DU 174B on cell 124A using the first configuration, and communicates with CU 172 via S-DU 174B. Events 704 and 706 are similar to events 304 and 306. In some implementations, UE 102 sends 705 at least one measurement report to M-DU 174A, similar to event 304. M-DU 174A, in turn, sends 707 at least one DU-to-CU message including at least one measurement report to CU 172, similar to event 306.

[0194] Events 704, 706, 705, 707, 790, 792, 716, 718, 720, 722 Fig. 7A Events 724, 726, 728, 730, 731, 732, 734, 736, 794 are collectively referred to as serving cell configuration process 781A. Fig. 7A It is collectively referred to as the service cell change process 783.

[0195] Next reference Figure 7B Scenario 700B is similar to scenarios 300-600B and 700A, except that CU 172 sends 717, 719 RRC reconfiguration messages to UE 102 via M-DU 174A, and receives 721, 723 RRC reconfiguration complete messages from UE 102 via M-DU 174A. Events 704, 706, 705, 707, 790, 792, 717, 719, 721, 723 are Figure 7B It is collectively referred to as the service cell configuration process 781B.

[0196] Next reference Fig. 8AIn scenario 800A, base station 104 operates as a MN and a SN, similar to scenarios 300-700B. Base station 104 includes CU 172, master DU (M-DU) 174A, secondary DU (S-DU) 174B, and T-DU 174C. CU 172 operates as a MN with M-DU 174A, and operates as a SN with S-DU 174B. Events 804, 806, 805, 807, 890, 892, 816, 818, 820, 822 are described in detail in detail. Fig. 8A Events 824, 826, 828, 830, 831, 832, 834, 836, 894 are collectively referred to as the serving cell configuration process 881A. Fig. 8A The process is collectively referred to as the serving cell change process 883. In addition, it should be understood that some of the descriptions about scenarios 300-700B can be applied to scenario 800A, but applied to one, some or all of the M-DU 174A, S-DU 174B or T-DU 174C (e.g., events 808, 810, 832, 834, etc.).

[0197] Next reference Figure 8B Scenario 800B is similar to scenarios 300-700B and 800A, except that CU 172 sends 817, 819 RRC reconfiguration messages to UE 102 via M-DU 174A, and receives 821, 823 RRC reconfiguration complete messages from UE 102 via M-DU 174A. Events 804, 806, 805, 807, 890, 892, 817, 819, 821, 823 are Fig. 8A It is collectively referred to as the service cell configuration process 881B.

[0198] Next, refer to 9A to 13B Several example methods that may be implemented in a UE (e.g., UE 102) or a RAN node (e.g., base station 104 / 106 or DU 174) to handle PDCP operations in a serving cell change are discussed. Figures 3 to 8B The examples and implementations described can be applied to 9A to 13B .

[0199] Fig.9A A method 900A is shown that can be implemented by a CU (e.g., CU 172) for managing PDCP operations in a serving cell change with a UE (e.g., UE 102).

[0200] Method 900A begins at block 902, where the CU communicates with the UE and the first DU (e.g., events 302, 380, 402, 480, 502, 580, 582, 581A, 581B, 602, 680, 682, 681A, 681B, 702, 780, 782, 781A, 781B, 802, 880, 882, 881A, 881B). At block 904, the CU receives a configuration for later activation from the second DU (e.g., events 310, 380, 410, 480, 510, 580, 581A, 581B, 610, 680, 681A, 681B, 710, 780, 781A, 781B, 810, 880, 881A, 881B). At block 906, the CU generates an RRC message including a configuration for later activation and a PDCP resume indication for PDCP resumption. At block 908, the CU sends an RRC message to the UE (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 581A, 581B, 616, 618, 617, 619, 680, 681A, 681B, 716, 718, 717, 719, 780, 781A, 781B, 816, 818, 817, 819, 880, 881A, 881B).

[0201] In some implementations, the first DU and the second DU are the same DU. In other implementations, the first DU and the second DU are different DUs. In some implementations, the CU sends a configuration for later activation to the second DU (e.g., events 412, 482, 612, 683, 682, 812, 883, 882). In some implementations, the RRC message is an RRC reconfiguration message. In some implementations, the CU generates a container including a PDCP recovery indication and a configuration for later activation, and includes the container in the RRC message. Examples and implementations of the container are similar to those for Figure 3 The examples and implementations described are similar.

[0202] Fig. 9B 9 is a flow chart of an example method 900B similar to method 900A, except that method 900B includes block 907 instead of block 906. At block 907, the CU generates an RRC message including a configuration for later activation and a PDCP reestablishment indication for PDCP reestablishment. In some implementations, the CU generates a container including the PDCP reestablishment indication and the configuration for later activation, and includes the container in the RRC message.

[0203] Fig. 10AA method 1000A is shown that can be implemented by a CU (e.g., CU 172) for managing PDCP operations in a serving cell change with a UE (e.g., UE 102).

[0204] Method 1000A begins at box 1002, in which the CU communicates with the UE via a first DU and a first cell using a PDCP entity for a radio bearer (e.g., events 302, 380, 402, 480, 502, 580, 582, 581A, 581B, 602, 680, 682, 681A, 681B, 702, 780, 782, 781A, 781B, 802, 880, 882, 881A, 881B). At block 1004, the CU receives a configuration for later activation from the DU (e.g., events 310, 380, 410, 480, 510, 580, 581A, 581B, 610, 680, 681A, 681B, 710, 780, 781A, 781B, 810, 880, 881A, 881B). At block 1006, the CU includes the configuration for later activation in the RRC message. At block 1008, the CU determines whether the DU is the first DU. If the CU determines at block 1008 that the DU is the first DU, the process proceeds to block 1010. At block 1010, the CU includes a PDCP resume indication in the RRC message, wherein the PDCP resume indication configures the UE to resume PDCP for the radio bearer. Otherwise, if the CU determines at block 1008 that the DU is not the first DU (e.g., the DU is the second DU), the process proceeds to block 1012. At block 1012, the CU avoids including a PDCP resume indication in an RRC message. At block 1014, the CU sends an RRC message including a configuration for later activation (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 581A, 581B, 616, 618, 617, 619, 680, 681A, 681B, 716, 718, 717, 719, 780, 781A, 781B, 816, 818, 817, 819, 880, 881A, 881B). Flow proceeds from block 1012 and from block 1010 to block 1014.

[0205] Fig. 10B 1 is a flow chart of an example method 1000B similar to method 1000A, except that method 1000B includes blocks 1011 and 1013 instead of blocks 1010 and 1012. At block 1011, the CU includes a PDCP reestablishment indication in an RRC message, wherein the PDCP reestablishment indication configures the UE to reestablish PDCP for the radio bearer. At block 1013, the CU avoids including the PDCP reestablishment indication in the RRC message.

[0206] against Fig.9A and Fig. 9B The examples and implementations described can be applied to Fig. 10A and Fig. 10B .

[0207] Fig.11A A method 1100A is shown that may be implemented by a base station (eg, base station 104 or 106) for managing PDCP operations in a serving cell change with a UE (eg, UE 102).

[0208] Method 1100A begins at box 1102, in which the base station communicates data with the UE via a first cell and a radio bearer (e.g., events 302, 380, 402, 480, 502, 580, 582, 581A, 581B, 602, 680, 682, 681A, 681B, 702, 780, 782, 781A, 781B, 802, 880, 882, 881A, 881B). At block 1104, the base station sends a configuration to the UE for later activation (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 581A, 581B, 616, 618, 617, 619, 680, 681A, 681B, 716, 718, 717, 719, 780, 781A, 781B, 816, 818, 817, 819, 880, 881A, 881B). At block 1106, the base station determines whether the base station has sent a configuration activation command to the UE to activate the configuration. If the base station determines that the base station has sent a configuration activation command to the UE to activate the configuration, the flow proceeds to block 1108. At block 1108, the base station performs PDCP recovery for the radio bearer. Otherwise, if the base station determines that the base station has not sent a configuration activation command to the UE to activate the configuration, the flow proceeds to block 1110. At block 1110, the base station refrains from performing PDCP recovery for the radio bearer.

[0209] Fig. 11B is a flow chart of an example method 1100B similar to method 1100A, except that method 1100B includes blocks 1109 and 1111 instead of blocks 1108 and 1110. At block 1109, the base station performs PDCP reestablishment for the radio bearer. At block 1111, the base station avoids performing PDCP reestablishment for the radio bearer.

[0210] against Fig.9A and Fig. 9B The examples and implementations described can be applied to Fig.11A and Fig. 11B .

[0211] Fig. 12A A method 1200A is shown that can be implemented by a UE (e.g., UE 102) for managing PDCP operations in a serving cell change with a RAN (e.g., base station 104 / 106, CU 172, or RAN 105).

[0212] Method 1200A begins at box 1202, in which the UE communicates with the RAN via a first cell and radio bearer using a first configuration (e.g., events 302, 380, 402, 480, 502, 580, 582, 581A, 581B, 602, 680, 682, 681A, 681B, 702, 780, 782, 781A, 781B, 802, 880, 882, 881A, 881B). At box 1204, the UE receives an RRC message including a second configuration from the RAN (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 581A, 581B, 616, 618, 617, 619, 680, 681A, 681B, 716, 718, 717, 719, 780, 781A, 781B, 816, 818, 817, 819, 880, 881A, 881B). At block 1206, the UE receives a configuration activation command from the RAN to activate the second configuration (e.g., events 330, 382, ​​430, 482, 530, 582, 583, 630, 682, 683, 730, 782, 783, 830, 882, 883). At block 1207, the UE activates the second configuration in response to the configuration activation command. At block 1208, the UE determines whether the RRC message includes a PDCP resume indication for the radio bearer. If the UE determines at block 1208 that the RRC message includes a PDCP resume indication for the radio bearer, the process proceeds to block 1210. At block 1210, the UE performs PDCP resume for the radio bearer in response to the configuration activation command and the PDCP resume indication. Otherwise, if the UE determines at block 1208 that the RRC message does not include a PDCP resume indication for the radio bearer, the process proceeds to block 1212. At block 1212, the UE refrains from performing PDCP recovery for the radio bearer in response to the configuration activation command. Flow proceeds from block 1212 and from block 1210 to block 1214. At block 1214, the UE performs a random access procedure with the RAN. At block 1216, the UE communicates with the RAN using the second configuration and the radio bearer.

[0213] Fig. 12Bis a flow chart of an example method 1200B similar to method 1200A, except that method 1200B includes blocks 1209, 1211, and 1213 instead of blocks 1208, 1210, and 1212. At block 1209, the UE determines whether the RRC message includes a PDCP re-establishment indication for the PDCP entity. If the UE determines at block 1209 that the RRC message includes a PDCP re-establishment indication for the radio bearer, the process proceeds to block 1211. At block 1211, the UE performs PDCP re-establishment for the radio bearer in response to the configuration activation command and the PDCP re-establishment indication. Otherwise, if the UE determines at block 1209 that the RRC message does not include a PDCP re-establishment indication for the radio bearer, the process proceeds to block 1213. At block 1213, the UE avoids performing PDCP re-establishment for the radio bearer in response to the configuration activation command. The process proceeds from block 1211 and from block 1213 to block 1214.

[0214] against Fig.9A and Fig. 9B The examples and implementations described can be applied to Fig. 12A and Fig. 12B .

[0215] Fig.13A A method 1300A is shown that can be implemented by a UE (e.g., UE 102) for managing PDCP operations in a serving cell change with a RAN (e.g., base station 104 / 106, CU 172, or RAN 105).

[0216] Method 1300A begins at box 1302, in which the UE communicates data with the RAN via a first cell and radio bearer using a first configuration (e.g., events 302, 380, 402, 480, 502, 580, 582, 581A, 581B, 602, 680, 682, 681A, 681B, 702, 780, 782, 781A, 781B, 802, 880, 882, 881A, 881B). At block 1304, the UE receives an RRC message including a second configuration and a PDCP resume indication from the RAN (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 581A, 581B, 616, 618, 617, 619, 680, 681A, 681B, 716, 718, 717, 719, 780, 781A, 781B, 816, 818, 817, 819, 880, 881A, 881B). At block 1306, the UE determines whether the second configuration is for later activation. If at block 1306 the UE determines that the second configuration is for later activation, the flow proceeds to block 1308. At block 1308, the UE avoids performing PDCP resumption for the radio bearer. In some implementations, at block 1310, the UE receives a configuration activation command from the RAN to activate the second configuration (e.g., events 330, 382, ​​430, 482, 530, 582, 583, 630, 682, 683, 730, 782, 783, 830, 882, 883). At block 1312, the UE performs PDCP recovery for the radio bearer in response to the configuration activation command and the PDCP recovery indication. Otherwise, if at block 1306 the UE determines that the second configuration is not for later activation, the flow proceeds to block 1314. At block 1314, the UE performs PDCP recovery for the radio bearer in response to the PDCP recovery indication.

[0217] Fig. 13B is a flow chart of an example method 1300B similar to method 1300A, except that method 1300B includes blocks 1305, 1309, 1313, and 1315 instead of blocks 1304, 1308, 1312, and 1314. At block 1305, the UE receives an RRC message including a second configuration and a PDCP reestablishment indication from the RAN. At block 1309, the UE refrains from performing PDCP reestablishment for the radio bearer. At block 1313, the UE performs PDCP reestablishment for the radio bearer in response to the configuration activation command and the PDCP reestablishment indication. At block 1315, the UE performs PDCP reestablishment for the radio bearer in response to the PDCP reestablishment indication.

[0218] against Fig.9A and Fig. 9B The examples and implementations described can be applied to Fig.13A and Fig. 13B .

[0219] The following description can be applied to the above description.

[0220] In general, the description of one of the above figures may be applied to another of the above figures. If there is no conflict, the above examples, implementations and methods may be combined. The events or boxes described above may be optional or omitted. For example, the events or boxes with dashed lines in the figures may be optional. In some implementations, "message" is used and "information element (IE)" can be replaced with "message", and vice versa. In some implementations, "IE" is used and "field" can be replaced with "IE", and vice versa. In some implementations, "configuration" or "configuration parameter" can be replaced with "configuration", and vice versa. In some implementations, "configuration activation command" can be replaced by "serving cell change command", "layer 1 / layer 2 switching command", "lower layer switching command" or "lower layer serving cell change command". "Fast serving cell configuration process" can be replaced by "fast serving cell change process".

[0221] The user device (e.g., UE 102) in which the technology of the present disclosure can be implemented can be any suitable device capable of wireless communication, such as a smart phone, a tablet computer, a laptop computer, a mobile game console, a point of sale (POS) terminal, a health monitoring device, a drone, a camera, a media streaming dongle or another personal media device, a wearable device such as a smart watch, a wireless hotspot, a femtocell or a broadband router. Further, in some cases, the user device can be embedded in an electronic system, such as a head unit (head unit) or an advanced driver assistance system (ADAS) of a vehicle. Further, the user device can be operated as an Internet of Things (IoT) device or a mobile Internet device (MID). Depending on the type, the user device may include one or more general-purpose processors, a computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0222] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., a code or machine-readable instruction stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a particular manner. A hardware module may include a dedicated circuit system or logic that is permanently configured to perform certain operations (e.g., as a dedicated processor, such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.). A hardware module may also include programmable logic or circuit systems that are temporarily configured by software to perform certain operations (e.g., as contained in a general-purpose processor or other programmable processor). The decision to implement a hardware module with a dedicated and permanently configured circuit system or with a temporarily configured circuit system (e.g., configured by software) may be driven by cost and time considerations.

[0223] When implemented in software, the techniques may be provided as part of an operating system, as a library used by multiple applications, as a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

Claims

1. A configuration method implemented in a node of a radio access network (RAN), the method comprising: sending a message including a configuration for performing a serving cell change to a second cell following an activation command to a user equipment (UE) in a first cell and communicating with the RAN using a radio bearer, including avoiding including a Packet Data Convergence Protocol (PDCP) re-establishment indication in the message; and After said sending of said message including said configuration, an activation command is sent to a UE for performing said serving cell change to said second cell according to said configuration and without re-establishing a PDCP entity of said UE for said radio bearer.

2. The method according to claim 1, further comprising: including in the message an identifier assigned to the configuration; as well as The identifier is included in the activation command.

3. The method of claim 1, wherein the message is a radio resource control (RRC) message.

4. The method of any preceding claim, wherein the sending of the activation command is in response to receiving a layer 1 (L1) measurement report from the UE.

5. The method according to any one of the preceding claims, wherein the node of the RAN is a Centralized Unit (CU) of a distributed base station further comprising a Distributed Unit (DU), the method further comprising: Prior to the sending of the message including the configuration, communicating with the UE via the DU using a PDCP entity of the CU for the radio bearer.

6. The method according to claim 4, wherein: The DU is the first DU, and The distributed base station includes a second DU; The method further comprises: receiving the configuration from the second DU; and In response to determining that the configuration is received from the second DU, avoiding including the re-establishment indication in the message.

7. The method according to claim 6, wherein: said sending of said configuration and refraining from including said reestablishment indication in said message occurs in a first instance; The method further includes, in a second example: receiving, from the first DU, a second configuration for performing the serving cell change, In response to determining that the configuration is received from the first DU, including the PDCP re-establishment indication in a second message; as well as Sending the second message to the UE.

8. A node in a Radio Access Network (RAN), the node comprising processing hardware and configured to implement the method according to any one of the preceding claims.

9. A method implemented in a user equipment (UE), the method comprising: communicating with a radio access network (RAN) in a first cell and using a radio bearer according to a first configuration; receiving a message from the RAN including a second configuration for performing a serving cell change to a second cell after the activation command; receiving, after said receiving of said configuration, said activation command from said RAN; refraining from performing PDCP re-establishment for the radio bearer in response to the activation command and upon determining that the RAN refrains from sending a PDCP re-establishment indication in the message; as well as Communicate with the RAN using the second configuration and the radio bearer.

10. The method according to claim 9, further comprising: receiving in the message an identifier assigned to the configuration; as well as The identifier assigned to the configuration is received in the activation command.

11. The method according to claim 9 or 10, further comprising: subsequent to said receiving of said second configuration, sending a layer 1 (L1) measurement report to said RAN; Wherein said receiving of said activation command is in response to an L1 measurement report.

12. The method according to claim 11, further comprising: receiving an L1 measurement configuration together with the second configuration; as well as The L1 measurement report is generated according to the L1 measurement configuration.

13. The method according to any one of claims 9 to 12, wherein the message is a Radio Resource Control (RRC) message.

14. The method according to any one of claims 9 to 13, further comprising: In response to the activation command, a random access procedure is performed on the second cell.

15. A user equipment (UE), comprising: Transceiver; as well as Processing hardware configured to implement the method according to any one of claims 9 to 14.

Images