Managing radio link control protocol operations for fast serving cell changes

Abstract

A user equipment (UE) communicates with a radio access network (RAN) according to a first configuration, including using a radio link control (RLC) entity; receiving a second configuration from the RAN for use after receiving the activation command; receiving an activation command from the RAN; and in response to the activation command: communicating with the RAN using a second configuration, including determining whether to reconstruct the RLC entity according to an indication from the RAN.

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 / 409,683, entitled “MANAGING RADIO LINK CONTROL PROTOCOL OPERATION FOR A FASTSERVING CELL CHANGE,” filed on September 23, 2022. The entire contents of this provisional application are hereby expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates to wireless communications, and more particularly to enabling fast serving cell change of a user equipment (UE) using control signaling at protocol layers below the radio resource control (RRC) protocol layer. 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 may 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 user plane data delivery, encryption, integrity protection, etc. 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 known as user equipment (UE)) to a base station) and in the downlink direction (from a base station to a UE). Further, 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 further scenarios, the UE and the base station use DRBs to transmit data on the user plane.

[0006] Depending on the scenario, the UE uses several types of SRBs and DRBs. When operating under dual connectivity (DC), the cell associated with the base station acting as a master node (MN) defines a master cell group (MCG), and the cell associated with the base station acting 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, while SRB2 resources support RRC messages including logged measurement information or NAS messages also on the DCCH, but have 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. Further, 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 the 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., base stations, or components of distributed base stations) interconnected by backhaul. When such network nodes support different radio access technologies (RATs), this type of connection is called multi-radio dual connection (MR-DC). When the UE operates under MR-DC, one base station acts as a master node (MN) covering the primary cell (PCell), and another base station acts as a secondary node (SN) covering the primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and 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 the 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, a serving cell change will be performed for the UE at some point. In order 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 (e.g., the RRC reconfiguration message includes a ReconfigurationWithSync IE) that configures a reconfiguration with synchronization to change the serving cell (e.g., PCell or PSCell). In a case where the UE operates in carrier aggregation (CA) of at least one secondary cell (SCell) with a PCell or PSCell, the RAN must release at least one SCell due to the change of the PCell or PSCell. The serving cell change involves a full 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 not clear how to develop and implement fast serving cell changes. Summary of the invention

[0009] An example embodiment of these techniques is a method implemented in a user equipment (UE), the method comprising: communicating with a radio access network (RAN) according to a first configuration, including using a radio link control (RLC) entity; receiving a second configuration from the RAN for use after receiving an activation command; receiving the activation command from the RAN; and in response to the activation command: communicating with the RAN using the second configuration, including determining whether to reestablish the RLC entity based on an indication from the RAN.

[0010] Another example embodiment of the techniques is a method implemented in a radio access network (RAN) node, the method comprising: communicating with a user equipment (UE) according to a first configuration; when the second configuration is to be activated at the UE via a command from the RAN, generating a second configuration, including avoiding including a re-establishment indication for a radio link control (RLC) bearer in the second configuration; and sending the second configuration to the UE.

[0011] An example embodiment of the techniques is a method implemented in a RAN node for managing radio link control operations during a cell change. The method includes communicating with a UE at the RAN node according to a first configuration; generating a second configuration at the RAN node by avoiding including a reestablishment indication for a radio link control entity in the second configuration when the second configuration is to be activated at a later time; and sending the second configuration without the reestablishment indication from the RAN node.

[0012] Another example embodiment of these techniques is a method for managing radio link control operations during a cell change, the method being implemented in a RAN node. The method includes communicating with a user equipment (UE) at the RAN node according to a first configuration; and causing the UE at the RAN node to perform at least one of the following based on at least the timing of configuration activation of a second configuration for the cell change: performing a radio link control reestablishment operation, or avoiding performing a radio link control reestablishment operation.

[0013] Another example embodiment of these techniques is a method for managing radio link control operations during a cell change, the method being implemented in a UE. The method includes: communicating with a radio access network (RAN) node at the UE according to a first configuration; receiving a second configuration at the UE from the RAN node to be activated at a later time, and the second configuration excluding a reestablishment indication of a radio link control entity; and avoiding reestablishing the radio link control entity at the UE in response to receiving the second configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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);

[0015] 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.

[0016] Figure 2 yes Figure 1A A block diagram of an example protocol stack according to which a UE communicates with a base station;

[0017] Figure 3 is a message passing diagram for an example scenario of a lower layer procedure in which a base station configures a UE to perform a cell change operation;

[0018] Figure 4 is a message passing diagram for an example scenario of a lower layer procedure in which a base station configures a UE to perform an inter-DU cell change operation;

[0019] Figure 5A is a message passing diagram of an example scenario in which a MN and a SN operate under a DC to perform lower layer procedures for a cell change operation;

[0020] 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;

[0021] 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;

[0022] 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;

[0023] Fig. 7A is with Figure 5A A message passing diagram of an example scenario similar to that of , but in which the base station acts as a MN (e.g., M-DU) and a SN (e.g., S-DU) to perform a cell change operation;

[0024] 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;

[0025] 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;

[0026] 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;

[0027] Fig. 9 is a flow chart depicting an example method implemented in a DU, wherein the DU generates a second configuration for later activation and avoids including an indication to reestablish an RLC bearer in the second configuration;

[0028] Fig.10 is a flow chart depicting an example method implemented in a RAN, wherein the RAN determines whether to include an RLC re-establishment indication based on whether a second configuration is to be activated later;

[0029] Fig.11A is a flow chart depicting an example method implemented in a DU, wherein the DU determines whether to reestablish an RLC entity based on whether a cell change is triggered by an activation command;

[0030] Fig. 11B It is depicted with Fig.11A A flow chart of an example method similar to the example method of , but wherein the DU makes a determination based on whether the UE is configured to re-establish an RLC entity;

[0031] Fig.12is a flow chart depicting an example method implemented in a UE, wherein the UE determines whether to reestablish an RLC entity in response to an activation command based on whether the second configuration includes an RLC reestablishment indication; and

[0032] Fig.13 is a flow chart depicting an example method implemented in a UE, wherein the UE determines whether to re-establish an RLC entity based on whether an RRC message configures the UE such that a second configuration is to be activated by an activation command. DETAILED DESCRIPTION

[0033] Figure 1A An example wireless communication system 100 is depicted in which a communication device can 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 is initially connected to the base station 104. In some scenarios, the base station 104 can perform an SN addition to configure the UE 102 to operate in dual connectivity (DC) with the base station 104 and the base station 106. The base stations 104 and 106 act as a MN and a SN, respectively, for the UE 102.

[0034] 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 or a different RAT such as EUTRA or NR. 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.

[0035] 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.

[0036] In a scenario where UE 102 is handed over from base station 104 to base station 106, base stations 104 and 106 act as a source base station (S-BS) and a target base station (T-BS), respectively. For example, before the handover, UE 102 may 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 a single connection (SC). In this case, base stations 104 and 106 act as a source MN (S-MN) and a target MN (T-MN), respectively.

[0037] The core network (CN) 110 may be an evolved packet core (EPC) 111 or a fifth generation core (5GC) 160, both of which are Figure 1A . 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 deliver user plane packets associated with audio calls, video calls, Internet traffic, 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 (e.g., 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 deliver user plane packets associated with 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.

[0038] like Figure 1A As shown, base station 104 supports cell 124A, and base station 106 supports cell 126. Cells 124A and 126 may partially overlap, such that UE 102 may communicate with base station 104 and base station 106 under 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 1A124B and 124C may partially overlap so that UE 102 can communicate with base station 104 under carrier aggregation (CA). Base station 104 may operate cells 124A, 124B, and 124C via one or more transmission and reception points (TRPs). More specifically, when UE 102 operates with base station 104 and base station 106 under DC, one of base stations 104 and 106 acts as a MeNB, Mng-eNB, or MgNB, and the other acts as a SgNB or Sng-eNB.

[0039] 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 relate to specific CN types (EPC, 5GC) and RAT types (5G NR and EUTRA), in general, the techniques of the present disclosure may also be applicable 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.

[0040] 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. In addition 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 send DL reference signals 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 and / or receive UL reference signals on a physical uplink (UL) channel 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. The processing hardware 130 in the example implementation includes a MAC controller 134 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 transmitting UL / DL MAC PDUs with one or more user devices. Processing hardware 130 may further include an RRC controller 136 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 RRC message delivery when the base station 104 acts as a MN relative to the SN or acts as a SN relative to the MN. The base station 106 may include processing hardware 140 similar to the processing hardware 130. In particular, components 142, 144, and 146 may be similar to components 132, 134, and 136, respectively.

[0041] 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 and / or receive DL reference signals on a physical DL channel 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 and / or send UL reference signals on a physical UL channel 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 processing hardware 150 in the example implementation includes a MAC controller 154 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 further include RRC controller 156 to implement procedures and messaging at the RRC sublayer of the protocol communication stack.

[0042] 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.

[0043] 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 acts 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 acts as a MN or SN. The processing hardware may further include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0044] 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.

[0045] The physical layer (PHY) layer 202 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 EUTRA and NR stacks to support handover between EUTRA and NR base stations and / or DC over the EUTRA and NR interfaces. Further, as Figure 2 As shown in A, UE 102 can support layering of NR PDCP 210 on EUTRA RLC 206A.

[0046] 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.

[0047] 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.

[0048] When the UE 102 operates under EUTRA / NR DC (EN-DC) with the base station 104 acting as a MeNB and the base station 106 acting as an SgNB, the network may 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 may also provide the UE 102 with a bearer terminated at the SN using only NR PDCP 210. The bearer terminated at the MN may be an MCG bearer or a split bearer. The bearer terminated at the SN may be an SCG bearer or a split bearer. The bearer terminated at the MN may be an SRB (e.g., SRB1 or SRB2) or a DRB. The bearer terminated at the SN may be an SRB (e.g., SRB) or a DRB.

[0049] Next, 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 file are marked with similar reference numbers (for example, event 316 is similar to Figure 4 Event 416 of A and 4B, Figure 5A Event 516, Figure 5B Event 517, Fig. 6A Event 616, Figure 6B Event 617, Fig. 7A Event 716 and Figure 7B Event 717 of FIG. 1 ), differences will be 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 numbers in other figures.

[0050] 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 in carrier aggregation (CA) uses the first configuration to communicate in cell 124A and other cells (e.g., Figure 1A124D) is used to communicate with DU 174. DU 174 operates other units. 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, other cells 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.

[0051] In some implementations, in event 302, UE 102 sends UL PDUs and / or UL control signals to base station 104 via one or more TRPs on cell 124A and / or other cells. In some implementations, UE 102 transmits UL PDUs and / or DL ​​PDUs with base station 104 via radio bearers including SRBs and / or DRBs. In further implementations, base station 104 configures radio bearers for UE 102. In some implementations, the UL control signal includes UL control information, channel state information, hybrid automatic repeat request (HARQ) acknowledgment (ACK), HARQ negative ACK, scheduling request, and / or sounding reference signal. Similarly, in further implementations, UE 102 receives DL PDUs and / or DL ​​control signals 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 some 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.

[0052] 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., 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., defined in 3GPP specification 38.331), or includes 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 remainder of the configuration parameters from base station 104.

[0053] While 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 of the L3 measurement reports, 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, the UE 102 receives one or more RRC messages (e.g., RRCReconfiguration messages) including at least one measurement configuration from the CU 172 via the DU 174 in event 302. According to the at least one measurement configuration, the UE 102 performs measurement and sends 304 at least one measurement report to the DU 174. In some implementations, the 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). The UE 102 sends the L3 measurement report to the CU 172 via the DU 174 according to the L3 measurement configuration. The UE 102 sends the L1 measurement report to the DU 174 according to the L1 measurement configuration. In some implementations, at least one measurement configuration includes a new measurement configuration for fast serving cell change (e.g., a new RRC IE (e.g., as defined in 3GPP specification 38.331v18.0.0 and / or higher)). For example, the new measurement configuration includes a CSI resource configuration (e.g., CSI-ResourceConfig IE) and / or a new report configuration. In such implementations, at least one measurement report includes a new measurement report associated with the new measurement configuration. UE 102 sends the new measurement report to DU 174 according to the new measurement configuration. In some implementations, each of the new report configurations includes a trigger event configuration that configures a trigger event to trigger UE 102 to send a new measurement report. If UE 102 detects a trigger event, UE 102 sends the new measurement report to DU 174.

[0054] 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 of the L1 measurement reports, the UE 102 sends a PUCCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each of the L1 measurement reports to the DU 174 on the PUCCH. In other implementations, for each of the L1 measurement reports, the UE 102 sends a PUSCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each of the L1 measurement reports 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 the PUCCH and sends the remainder of the L1 measurement report to the DU 174 on the physical UL shared channel (PUSCH). That is, for each part of the L1 measurement report, the UE 102 sends a PUCCH transmission including the L1 measurement report to the DU 174, and for each of the remaining parts 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 of the L1 measurement reports is a part 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, the 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).

[0055] In some implementations, each of the L3 measurement reports 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, UE 102 sends each of the L3 measurement reports to CU 172 on PUSCH via DU 174. In some implementations, each of the L3 measurement reports is an RRC message (e.g., a MeasurementReport message). In some implementations, each of the L3 measurement configurations includes a specific measurement identifier (e.g., measId), and each of the L3 measurement reports includes a specific measurement identifier in a specific L3 measurement configuration. In some implementations, when CU 172 receives the L3 measurement report including the measurement identifier and the L3 measurement result from UE 102 via DU 174, CU 172 determines that the L3 measurement report is associated with the L3 measurement configuration identified by the measurement identifier.

[0056] In some alternative implementations, for each of at least one measurement report (e.g., an L1 measurement report and / or a new type measurement report), the UE 102 sends a MAC control element (CE) including the measurement report to the DU 174 at event 304. To send the MAC CE, the UE 102 generates one or more MAC PDUs for the DU 174 at event 304, each MAC PDU including one or more of the MAC CEs.

[0057] In some implementations, the UE 102 performs measurements on one or more reference signals according to at least one measurement configuration. In further implementations, 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 in some implementations, transmits one or more reference signals on cell 124C and / or other cells.

[0058] After receiving one or some of the at least one measurement report from the UE 102 (e.g., in response thereto), 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 (e.g., higher) 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 cell 124B is above a first predetermined threshold and / or is better (e.g., higher) than cell 124A, then DU 174 determines to prepare cell 124B for UE 102. Alternatively, base station 104 determines to prepare cell 124B for UE 102 regardless of whether a measurement report is received from UE 102.

[0059] 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 a further implementation, if DU 174 determines to prepare cell 124B, DU 174 initiates transmission of the first DU-to-CU message to CU 172.

[0060] 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. DU 174 then 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 encryption) on the RRC reconfiguration message. For example, CU 172 generates an integrity message 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 UE 102 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 a further 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).

[0061] 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 requirement message. In the case of a UE context modification requirement message, in response to the UE context modification requirement message, CU 172 sends a UE context modification confirmation message to DU 174. In some implementations, the second CU to DU message is a DL RRC messaging message. In other implementations, the second CU to DU message is a UE context modification request message, and in response to the second CU to DU message, DU 174 sends a second DU to CU message (e.g., a UE context modification response message) to CU 172.

[0062] Events 308 and 310 in Figure 3 It is collectively referred to as the service cell preparation process 390.

[0063] In some implementations, CU 172 includes a field or IE in the RRC reconfiguration message of events 316 and 318 to indicate that UE 102 should not apply configuration 1 immediately. In some implementations, the field or IE is currently defined (e.g., defined in 3GPP specification 38.331v18.0.0 and / or higher). In further implementations, the field or IE is newly defined (e.g., defined in 3GPP 6G specifications). In some implementations, the field or IE is an indicator. If the RRC reconfiguration message of event 318 includes the indicator, UE 102 avoids applying configuration 1 immediately. Otherwise, if the RRC reconfiguration message of event 318 does not include the indicator, UE 102 applies configuration 1 immediately. In other implementations, the field or IE is a container (e.g., the first container and / or the 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, UE 102 avoids applying the configuration immediately. Otherwise, if the configuration is not included in the container, UE 102 applies the configuration immediately.

[0064] 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., ConfigToA ddModList 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., ConfigToA ddMod IE, CellConfigToAddMod IE, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddMod IE). In some implementations, when UE 102 receives the first list of additions or modifications, UE 102 stores the first list of additions or modifications (eg, in a variable in random access memory (RAM)).

[0065] 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, as described below, CU 172 receives ID 1 in a first DU-to-CU message from DU 174.

[0066] In some implementations, CU 172 sends ID 1 to DU 174 so that DU 174 associates ID 1 with Configuration 1. In some implementations, CU 172 includes ID 1 in the first CU-to-DU message. In further 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 further 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 occur at Figure 3It is collectively referred to as the ID allocation process 392.

[0067] In some implementations, in the case where CU 172 includes ID 1 in the first CU-to-DU message, DU 174 includes ID 1 in configuration 1. In such a case, CU 172 does not include ID 1 in the RRC reconfiguration message, the first container, and / or element 1.

[0068] In some alternative implementations, DU 174 assigns ID 1 to identify configuration 1. In some implementations, DU 174 includes ID 1 in the first DU to CU message. In further implementations, CU 172 includes ID 1 in the RRC reconfiguration message. In other implementations, DU 174 includes ID 1 in configuration 1. Thus, CU 172 does not include an ID identifying configuration 1 in the RRC reconfiguration message, the first container, and / or element 1.

[0069] 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 configuration parameters (e.g., MAC-CellGroupConfig IE), and / or RLC configuration parameters (e.g., RLC-BearerConfig IE). In some further implementations, the multiple configurations include special cell configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig IE).

[0070] In some implementations, the DU 174 includes the random access configuration in configuration 1. In other implementations, the DU 174 does not include the random access configuration in configuration 1. In some implementations, if the cell 124A and the cell 124B are not synchronized, the DU 174 determines to include the random access configuration in configuration 1. Otherwise, if the cell 124A and the cell 124B are synchronized, the DU 174 determines not to include the random access configuration in configuration 1. In other implementations, if the DU 174 determines that the UE 102 is not synchronized with the cell 124B in the UL, the DU 174 determines to include the random access configuration in configuration 1. Otherwise, if the DU 174 determines that the UE 102 is synchronized with the cell 124B in the UL, the DU 174 determines not to include the random access configuration in configuration 1. As described below, if configuration 1 includes the random access configuration, the UE 102 performs the random access procedure in event 332 according to the random access configuration. 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.

[0071] In some implementations, DU 174 includes the random access configuration in configuration 1 regardless of whether cells 124A and 124B are synchronized. 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.

[0072] In some implementations, the DU 174 includes the reconfiguration with synchronization configuration (e.g., ReconfigurationWithSync IE) in Configuration 1 or the special cell configuration. In other implementations, the DU 174 does not include the reconfiguration with synchronization configuration (e.g., ReconfigurationWithSync IE) in Configuration 1 or the special cell configuration. In some implementations, if the cell 124A and the cell 124B are not synchronized, the base station 104 determines to include the reconfiguration with synchronization configuration in Configuration 1. Otherwise, if the cell 124A and the cell 124B are synchronized, the DU 174 determines not to include the reconfiguration with synchronization configuration in Configuration 1. In other implementations, if the DU 174 determines that the UE 102 has not synchronized with the cell 124B in the UL, the DU 174 determines to include the reconfiguration with synchronization configuration in Configuration 1. Otherwise, if DU 174 determines that UE 102 is already synchronized with cell 124B in the UL, DU 174 determines not to include reconfiguration with synchronization configuration in configuration 1. In some implementations, if configuration 1 includes reconfiguration with synchronization configuration, UE 102 performs a random access procedure in event 332 in response to or according to reconfiguration with synchronization configuration, as described below. Otherwise, if configuration 1 does not include reconfiguration with 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 further implementations, cell ID 1 is a CGI. In some further implementations, configuration 1 includes a cell index 1 (e.g., a serving cell index) indexing cell ID 1 or cell 124B.

[0073] In some implementations, after receiving one or some of the at least one measurement report of event 304 (e.g., in response thereto), the base station 104 (i.e., the CU 172 or the DU 174) determines to prepare other cells of the base station 104 for the UE 102. In some implementations, the base station 104 determines to prepare other cells because the at least one measurement report indicates that other cells can be used by the base station 104 to communicate with the UE 102. In some implementations, the other cells include the cell 124C and / or cells other than the cells 124A, 124B, and 124C. In some implementations, if the L3 measurement report indicates that the signal strength and / or quality of a specific cell in the other cells is higher than the corresponding predetermined threshold and / or better (e.g., higher) than the cell 124A, the CU 172 determines to prepare the specific cell for the UE 102. In other implementations, if the L1 measurement report or the new measurement report indicates that the signal strength and / or quality of a particular cell among the other cells is above the first predetermined threshold and / or is better (e.g., higher) than cell 124A, DU 174 determines to prepare the particular cell for UE 102. In some implementations, the corresponding predetermined threshold for the other cells is different from the first predetermined threshold. In further implementations, the corresponding predetermined threshold for the other cells is the same as the first predetermined threshold. In some implementations, the corresponding predetermined threshold for the other cells is the same as the first predetermined threshold. Alternatively, base station 104 determines to prepare the other cells for UE 102 regardless of whether a measurement report is received from UE 102.

[0074] In some implementations, in response to determining to prepare 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 further 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 additional serving cell preparation processes to prepare each of the other cells, similar to process 390. 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 configuration 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 greater than one. For example, "N" is 2, 4, 6, 8, 10, 12, 14, or 16. The examples and implementations of Configuration 1 may be applicable to Configuration 2, ..., N.

[0075] In other implementations, CU 172 determines to prepare other cells in process 390. In some such cases, CU 172 includes a cell ID for each of the other cells in the first CU to DU message, and DU 174 includes configuration 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 configuration 2, ..., N in the first DU to CU message.

[0076] In some implementations, after receiving configuration 2, ..., N from DU 174, CU 172 includes configuration 2, ..., N in the first container. In some implementations, CU 172 includes configuration 2, ..., N in element 2, ..., N, and includes element 2, ..., N in the first container. In some implementations, CU 172 includes ID 2, ..., N for identifying configuration 2, ..., N respectively in the RRC reconfiguration message. In some implementations, CU 172 includes ID 2, ..., N in the first container. For example, CU 172 includes ID 2, ..., N and configuration 2, ..., N in element 2, ..., N in the first addition or modification list.

[0077] 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 process.

[0078] 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.

[0079] 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. 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 of configuration 2, ..., N in the RRC reconfiguration message, the first container, and / or element 1.

[0080] In some alternative implementations, CU 172 generates a second container including configuration 2, ..., N or elements 2, ..., N instead of using the first container. Alternatively, DU 174 generates the second container and includes the second container in the first DU to CU message or 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, CellConfigToAddModList IE, MobilityToAddModList IE, MobilityConfig ToAddModList IE, or CellGroupConfigToAddModList IE), and each of the elements 2, ..., N is an addition or modification IE (e.g., ConfigToAddMod IE, ReconfigToAddMod IE, CellConfigToAddMod IE, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddMod IE). In some implementations, when the UE 102 receives the second addition or modification list, the UE 102 stores the second addition or modification list with the first addition or modification list (e.g., in a variable in RAM).

[0081] 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 further 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.

[0082] In some implementations, each of configurations 1 and / or 2, ..., N is a CellGroupConfig IE. In such implementations, the following is an example structure of a first or second add or modify list (e.g., CellGroupConfigToAddModList IE), and the CellGroupConfigToAddMod IE is an element of the first or second add or modify list.

[0083] In some implementations, CU 172 sends a release list to UE 102 via DU 174 to release one or more configurations in configuration 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 IDs of one or more configurations in the release list to indicate one or more of the configurations to be released. UE 102 identifies one or more of the configurations according to the IDs, and releases one or more of the configurations in response to the release list.

[0084] In some implementations, the base station 104 sends a third addition or modification list that is empty or does not include a configuration to the UE 102 to release all of the configurations 1, ..., N. 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 of the configurations 1, ..., N in response to the third addition or modification list.

[0085] In some implementations, CU 172 determines to release one, multiple or all of configurations 1, ..., N, and sends a CU-to-DU message to DU 174 to instruct DU 174 to release one, multiple or all of configurations 1, ..., N. For example, CU 172 includes one, multiple or all of IDs 1, ..., N in the CU-to-DU message to instruct DU 174 to release one, multiple or all of configurations 1, ..., N. Depending on the implementation, each of the cell IDs 1, ..., N is a CGI or a PCI. In some implementations, in response, DU 174 releases one, multiple or all of configurations 1, ..., N, and sends a DU-to-CU message to CU 172. In other implementations, DU 174 determines to release one, multiple or all of configurations 1, ..., N, and sends a DU-to-CU message including the IDs of one, multiple or all of configurations 1, ..., N to CU 172. After receiving the DU to CU message (eg, in response thereto), the CU 172 generates a release list or a third addition or modification list to release one, more, or all of configurations 1, . . . , N.

[0086] In yet 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 including the release list or the third addition or modification list to CU 172. In some implementations, in response, CU 172 sends a CU to DU message to DU 174. In some implementations, DU 174 determines to release one, more, or all of configurations 1, ..., N. In other implementations, DU 174 receives a CU to DU message including an ID of one, more, or all of configurations 1, ..., N from CU 172 to indicate the release of one, more, or all of configurations 1, ..., N.

[0087] Example Implementation 1

[0088]

[0089] 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 CellGroupConfigToAddMod IE2, ..., 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 CellGroupConfigToAddModL ist IE includes CellGroupConfigToAddMod IE 2, ..., N. In a further implementation, the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddModIE 1, . . . , N.

[0090] In some implementations, the release list is a CellGroupConfigToReleaseList IE. In further implementations, the base station 104 includes one or more ConfigID IEs in the CellGroupConfigToReleaseListIE 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.

[0091] Example Implementation 2

[0092] Example implementation 2 is similar to example implementation 1, except that CellGroupConfigToAddModIE does not include ConfigId.

[0093]

[0094] 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 zero or one. If the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 1, ..., N in sequence, then ID 1, ..., N has values ​​of X, X+1, ..., X+(N-1). In some implementations, if the base station 104 sends a 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 CellGroupConfigToAddMod List IE includes CellGroupConfigToAddMod IE 2, ..., N in sequence, then ID2, ..., N is a value of X, X+1, ..., X+N-2. If the second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 1, ..., N in sequence, 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.

[0095] In some implementations, the base station 104 sends a CellGroupConfigToAddModList IE including zero CellGroupConfigToAddMod IEs to release all of the CellGroupConfigToAddMod IEs 1, . . . , N.

[0096] 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.

[0097] 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 or second addition or modification lists.

[0098] Example Implementation 3

[0099] In example implementation 3, the first or second addition or modification list is a CondReconfigToAddModList-r16 IE (eg, as defined by Release 16 in 3GPP specification 38.331), and the CondReconfigToAddMod IE is an element of the list.

[0100]

[0101] 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 CondReconfig igToAddMod-r16 IE 2, ..., N, respectively. ID 1 and configuration 1 are CondReconfigId and RRCReconfiguration message in CondReconfig igToAddMod 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 Cond ReconfigToAddMod-r16 IE 1, and the second CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 2, ..., N. In further implementations, the first CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 1, ..., N.

[0102] In this example implementation, the base station 104 includes the conditional configuration (i.e., condExecution Cond-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 in the condExecutionCond-r16 field for the conditional procedure. 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 CondReconfigToAdd Mod-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., cond ExecutionCond-r16) in any one or some of the CondReconfigToAddMod-r16 IEs. Therefore, for the CondReconfigToAddMod-r16 IE that does not include the conditional configuration (i.e., condExecutionCond-r16), the UE 102 is not configured to perform or does not perform any evaluation (i.e., detection or determination) of the condition of the conditional procedure (e.g., conditional handover).

[0103] In some implementations, the release list is a CondReconfigToRemoveList-r16 IE. In further implementations, 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.

[0104] Example Implementation 4

[0105] 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.

[0106]

[0107] Example Implementation 5

[0108] 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.

[0109] Equation 5 is decoupled from the conditional process.

[0110]

[0111] In some implementations, the first addition or modification list is a first ReconfigToAdd ModList IE, and the second addition or modification list is a second ReconfigToAddModList IE. Element 1 is ReconfigToAddMod IE1, and elements 2, ..., N are ReconfigToAddMod IE 2, ..., N, respectively. ID 1 and configuration 1 are the ConfigId and RRCReconfiguration IE in ReconfigToAddMod IE 1. ID(s) 2, ..., N and configuration(s) 2, ..., N are the ConfigId and RRC Reconfiguration IE in ReconfigToAddMod IE(s) 2, ..., N, respectively. In some implementations, the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, and the second ReconfigToAddModList IE includes ReconfigToAddMod IE(s) 2, ..., N. In a further implementation, the first ReconfigToAddModList IE includes ReconfigToAddMod IEs 1, . . . , N.

[0112] In some implementations, the release list is a ReconfigToReleaseList IE. In further 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 ReconfigToAdd Mod IEs are identified by one or more ConfigID IEs.

[0113] Example Implementation 6

[0114]

[0115] Example implementation 6 is similar to example implementation 5, except that the Reconfig ToAddMod 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 zero or one. If the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N in sequence, then ID 1, ..., N has values ​​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 IE 2, ..., N in sequence, then ID 2, ..., N is a value of X, X+1, ..., X+N-2. If the second ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N in sequence, 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.

[0116] In some implementations, the base station 104 sends a ReconfigToAddModList IE including zero ReconfigToAddMod IEs to release all ReconfigToAddMod IEs 1, . . . , N.

[0117] In example implementations 5 and 6, "ReconfigToAddModList", "Reconfig ToAddMod", "configId", "ConfigId", "cellGroupConfig", "ReconfigT oReleaseList" and "maxNrofConfigCells" are exemplary and should not limit the scope and application of the present invention.

[0118] Example Implementation 7

[0119] Example implementation 7 is a combination of example implementations 1 and 5, as shown below. Depending on the implementation, any one of 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.

[0120]

[0121] After receiving the RRC reconfiguration message 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 of the at least one measurement report of event 324 is not an RRC message.

[0122] 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, 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 after the event 306 or 316. Depending on the implementation, the one or more RRC messages include or do not include the RRC reconfiguration message of the 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 includes the at least one L1 measurement result and / or at least one L3 measurement result in the measurement report of the 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, the measurement configuration includes an L3 measurement configuration (e.g., MeasConfig IE), an L1 measurement configuration (e.g., CSI-MeasConfig IE), and / or a new measurement configuration, as described for event 304.

[0123] In some implementations, the new measurement configuration as described for events 304 and 324 is similar to an L3 measurement configuration. For example, the new measurement configuration includes a portion of the configuration parameters defined in the MeasConfig IE. In other implementations, the new measurement configuration as described for events 304 and 324 is similar to an L1 measurement configuration. For example, the new 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).

[0124] After receiving at least one measurement report in event 324 (e.g., in response thereto), 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.

[0125] In yet other implementations, DU 174 includes a bitmap in the first configuration activation command instead of ID 1, cell ID 1, or cell index 1 to activate configuration 1. 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 a further 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 one and the second value is zero. In other implementations, the first value is zero and the second value is one. 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 a first value, where 1<=K<=N.

[0126] In some implementations, at least one measurement report (e.g., L1 measurement report or new measurement report) of event 324 includes at least one measurement result of 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 above 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 further implementations, 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 above the second predetermined threshold or the first predetermined threshold. This also indicates that cell 124B is suitable for communication with UE 102. Therefore, DU 174 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 above the second predetermined threshold.

[0127] In some implementations, at least one measurement report (e.g., L3 measurement report) of events 324 and 326 includes at least one measurement result of 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 a further implementation, the second predetermined threshold is equal to the first predetermined threshold. In an implementation, 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. This 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.

[0128] 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 optionally sends a fourth DU to CU message to CU 172. In some implementations, CU 172 includes cell index 1 (e.g., serving cell index) in the fourth CU to DU message. Therefore, DU 174 can determine to activate configuration 1 based on (serving) cell index 1. In other implementations, CU 172 includes cell ID 1 in the fourth CU to DU message. Therefore, DU 174 can determine to activate configuration 1 based on the cell ID. In yet other implementations, CU 172 includes ID 1 in the fourth CU to DU message. Therefore, DU 174 can determine 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 UE context modification request messages and UE context modification response messages, 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)).

[0129] 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 higher). 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 based on the subheader. Depending on the implementation, the subheader includes a logical channel ID (e.g., defined in the 3GPP specification) or an extended logical channel ID to identify the MAC CE. For example, the logical channel ID or the extended logical channel ID is newly defined (e.g., defined in 3GPP specification 38.321 v18.0.0 and / or higher). 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 further 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 higher)).

[0130] In some implementations, DU 174 does not perform security protection (e.g., integrity protection and / or encryption) on the first configuration activation command. This 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.

[0131] In some implementations, after receiving the first configuration activation command, the UE 102 sends 331 an acknowledgment to the DU 174 on the cell 124A or the cell 124D to indicate that the UE 102 received the first configuration activation command. In some implementations, the acknowledgment is a HARQ ACK. In other implementations, the acknowledgment is a MAC CE. For example, the MAC CE is an existing MAC CE (e.g., as defined in 3GPP specification 38.321 v17.1.0). In another implementation, the MAC CE is a new MAC CE (e.g., as defined in 3GPP specification 38.321 v18.0.0 and / or higher). In yet other implementations, the acknowledgment is a PUCCH transmission.

[0132] 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 further 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 further 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.

[0133] After receiving the first configuration activation command (e.g., in response to this), the UE 102 identifies a specific configuration (e.g., configuration 1) according to a specific ID (e.g., ID1) 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, the UE 102 disconnects from the cell 124A after receiving the first configuration activation command or sending an acknowledgment (e.g., in response to this). In other words, the UE 102 stops communicating on the cell 124A (e.g., in response to) receiving 330 the first configuration activation command or sending 331 an acknowledgment. In such a case, the UE 102 performs 332 a random access procedure after disconnecting 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 the UE 102 to perform a random access procedure, the UE 102 performs a random access procedure in event 332. For example, configuration 1 includes a reconfiguration with a synchronization configuration (e.g., ReconfigurationWithSync IE) 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 upon 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.

[0134] 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, the UE 102 transmits UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104 in event 318. In such a case, when the UE 102 receives 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.

[0135] DU 174 identifies or determines that UE 102 is connected to cell 124B when receiving a UE identification or a dedicated preamble from UE 102 during a random access procedure.

[0136] 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 instruct the UE 102 to apply configuration 1. In some implementations, the UE 102 includes the RRC message in message 3. In further implementations, the UE 102 includes the RRC message in message A. In further 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 yet other implementations, the UE 102 avoids sending the RRC message to the base station 104 in response to applying configuration 1 or receiving the first configuration activation command.

[0137] In some cases where the UE 102 skips the random access procedure, the UE 102, after receiving the first configuration activation command (e.g., in response thereto), directly communicates 336 with the base station 104 on the cell 124B according to configuration 1. For example, the UE 102 transmits UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104 at event 318. In some such cases, after receiving the first configuration activation command (e.g., in response thereto), 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, 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 after sending the first configuration activation command. The DU 174 identifies or determines that the UE 102 is connected to the cell 124B upon receiving the PUCCH or PUSCH transmission. In other implementations, the UE 102 transmits at least one PUCCH or PUSCH transmission regardless of receiving DCI on the PDCCH on the cell 124B. The DU 174 identifies or determines that the UE 102 is connected to the cell 124B upon receiving the PUCCH or PUSCH transmission. 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 applies configuration 1. The CU 172 identifies or determines that the UE 102 is connected to the cell 124B upon receiving the RRC message. 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 yet other implementations, UE 102 refrains from sending RRC messages to base station 104 in response to applying configuration 1 or receiving a first configuration activation command.

[0138] In some implementations, when DU 174 determines in event 332 or 336 that UE 102 is successfully connected to cell 124B, 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. The cell ID may be a PCI or a CGI. Therefore, CU 172 determines that UE 102 is connected to cell 124B upon receiving the DU to CU message of event 334. In further implementations, when DU 174 determines in event 332 or 336 that UE 102 is successfully connected to cell 124B, DU 174 sends a DL data delivery status message or frame to CU 172.

[0139] In some implementations, when it is determined that the UE 102 is connected to the cell 124B, the first configuration activation command is sent 330, or the confirmation 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, the first configuration activation command is sent 330, or the confirmation is received 331, the DU 174 releases the resources of the cell 124A that are configured for the UE 102.

[0140] Events 304, 306, 390, 392, 316, 318, 320, 322, 324, 326, 328, 330, 331, 332, 334, 336, 394 Figure 3 It is collectively referred to as the fast service cell configuration process 380.

[0141] 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 yet other implementations, the first container includes an indication that configuration 1 is a complete configuration. In yet other implementations, element 1 (e.g., ConfigToAddMod IE, CellGroupConfigToAddMod, MobilityToAddMod IE, MobilityConfigToAddMo d 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, configuration 1 is an indication different from the fullConfig field (e.g., defined in the current 3GPP specification). In other implementations, configuration 1 is an indication of the fullConfig field (e.g., defined in the current 3GPP specification) in the RRCReconfiguration message.

[0142] 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 a further implementation, UE 102 determines that configuration 1 is an incremental configuration based on excluding the indication in configuration 1, first container or element 1.

[0143] In some implementations, if configuration 1 is a full configuration, the UE 102 releases the first configuration or a specific configuration in the first configuration after (e.g., in response to) 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 the UE 102 on the cell 124B. In some implementations, if configuration 1 is a full configuration, the DU 174 releases the first configuration or a specific configuration in the first configuration after (e.g., in response to) sending 330 a first configuration activation command, receiving 331 an acknowledgement, successfully performing 332 a random access procedure, or receiving a specific transmission from the UE 102 on the cell 124B. In some implementations, the specific transmission is a PUCCH transmission. In further implementations, the transmission is a PUSCH transmission. In some implementations, after sending the first configuration activation command, the DU 174 generates a DCI and a CRC for the DCI, scrambles the CRC with the UE identity of the UE 102, and sends the DCI and the scrambled CRC on the PDCCH on the cell 124B. When the UE 102 receives the DCI and the scrambled CRC and verifies that the scrambled CRC is valid using the UE identity, the UE 102 sends a PUSCH transmission to the DU 174 on the cell 124B.

[0144] 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.

[0145] 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 upon 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 the base station 104 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, the UE 102 resets the UE MAC entity in response to the MAC reset indication upon receiving the first configuration activation command.

[0146] Otherwise, if configuration 1 or element 1 does not include a MAC reset indication, the UE 102 avoids resetting the UE MAC entity after or upon receiving the first configuration activation command if the configuration 1 or element 1 does not include a MAC reset indication. 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, the UE 102 resets the UE MAC entity after or upon receiving 330 the first configuration activation command. Otherwise, if configuration 1 or element 1 does not include a MAC reset indication and an indication that the configuration is a full configuration, the UE 102 avoids resetting the UE MAC entity after or upon receiving 330 the first configuration activation command if the configuration 1 or element 1 does not include a MAC reset indication and an indication that the configuration is a full configuration.

[0147] 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, the DU 174 resets the DU MAC entity in response to the MAC reset indication 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.

[0148] Otherwise, if configuration 1 or element 1 does not include a MAC reset indication, DU 174 avoids resetting the DU MAC entity after (e.g., in response to) sending 330 the first configuration activation command. Thus, 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.

[0149] In some implementations, the DU 174 includes the MAC reset indication in a MAC-CellGroupConfig IE (e.g., CellGroupConfig IE) in Configuration 1. In other implementations, the DU 174 includes the MAC reset indication in the CellGroupConfig IE and outside the MAC-CellGroupConfig IE. In still other implementations, the DU 174 includes the MAC reset indication in Element 1 and outside Configuration 1.

[0150] 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, DU 174 resets the DU MAC entity 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. Alternatively, DU 174 releases the DU MAC entity and establishes a new DU MAC entity for communicating 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, DU 174 avoids resetting the DU MAC entity after (e.g., in response to) sending 330 the first configuration activation command.

[0151] 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 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, the UE 102 avoids resetting the UE MAC entity in response to the MAC retention indication when receiving a configuration activation command (e.g., a first configuration activation command). Otherwise, if the configuration or element does not include the MAC retention indication, the UE 102 resets the UE MAC entity after or when receiving the configuration activation command.

[0152] 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), DU 174 avoids resetting the DU MAC entity in response to the MAC retention indication after sending a configuration activation command (e.g., a first configuration activation command) to UE 102. Therefore, after sending 330 the first configuration activation command, receiving 331 an acknowledgment, or determining at 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.

[0153] In some implementations, the DU 174 includes the MAC reservation indication in a MAC-CellGroupConfig IE (e.g., CellGroupConfig IE) in Configuration 1. 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.

[0154] Otherwise, if configuration 1 or element 1 does not include a MAC retention indication, the DU 174 resets the DU MAC entity after (eg, in response to) sending 330 the first configuration activation command.

[0155] 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 that configuration 1 is a complete configuration in configuration 1 or element 1, the base station 104 avoids including a MAC reservation indication in configuration 1 or element 1. Otherwise, if the base station 104 does not include an indication that configuration 1 is a complete configuration in configuration 1 or element 1, the base station 104 includes a MAC reservation indication in configuration 1 or element 1.

[0156] In an alternative implementation, 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 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, the UE 102 partially resets the UE MAC entity upon receiving a configuration activation command (e.g., a first configuration activation command). Otherwise, if the configuration or element does not include the MAC partial reset indication, the UE 102 completely resets the UE MAC entity after receiving the configuration activation command (e.g., in response thereto). In some implementations, when the UE partially resets the UE MAC entity, the UE 102 retains (e.g., maintains or keeps) the operating state of the UE MAC entity, or omits one or more actions performed by the UE 102 when the UE 102 completely resets the UE MAC entity.

[0157] If the base station 104 includes a MAC partial reset indication in a configuration or element (e.g., configuration 1 or element 1), the DU 174 partially resets the DU MAC entity in response to the MAC partial reset indication after sending a configuration activation command (e.g., a first configuration activation command) to the UE 102.

[0158] In some implementations, the DU 174 includes the MAC partial reset indication in a MAC-CellGroupConfig IE (e.g., CellGroupConfig IE) in Configuration 1. 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.

[0159] Otherwise, if Configuration 1 or Element 1 does not include a MAC partial reset indication, then DU 174 completely resets the DU MAC entity after (eg, in response to) sending 330 the first configuration activation command.

[0160] 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 that configuration 1 is a complete configuration in configuration 1 or element 1, the base station 104 avoids including a MAC partial reset indication in configuration 1 or element 1. Otherwise, in further implementations, if the base station 104 does not include an indication that configuration 1 is a complete configuration in configuration 1 or element 1, 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 that configuration 1 is a complete configuration in configuration 1 or element 1, the base station 104 includes a MAC partial reset indication.

[0161] 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 (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.

[0162] In some implementations, when the UE 102 determines to reset the UE MAC entity as described above or the UE 102 resets 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) initialize Bj of the configured logical channel to zero; (ii) stop one or more timers; (iii) if the UE 102 is configured to perform a random access process (e.g., event 332) in a configuration (e.g., configuration 1), then timeAlignmentTimer is considered to have expired; (iv) a 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 refreshed; (vii) the MSGA buffer is refreshed; (viii) the triggered scheduling request process is canceled (if any); (ix) the triggered buffer status report process is canceled (if any); (x) the triggered power headroom report process is canceled (if any); (xi) the triggered consistent LBT is canceled (if any) Failure; (xii) cancel (if any) the triggered BFR; (xiii) cancel (if any) the triggered sidelink buffer status report process; (xiv) cancel (if any) the triggered preemptive buffer status report process; (xv) cancel (if any) the triggered timing advance report process; (xvi) cancel (if any) the triggered recommended bit rate query process; (xvii) cancel (if any) the triggered configured uplink grant confirmation; (xviii) cancel (if any) the triggered configured sidelink grant confirmation; (xix) cancel (if any) the triggered expected protection symbol query; (xx) cancel (if any) the triggered positioning measurement gap activation / deactivation request process; (xxi) refresh the DL soft buffer for the HARQ process; (xxii) for each of the DL HARQ processes, treat the next received transmission of the TB as the first transmission; (xxiii) release (if any) the temporary C-RNTI; (xiv) reset one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER); (xxv) and so on.

[0163] 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) stops one or more timers; (ii) if UE 102 is configured to perform a random access process (e.g., event 332) in a configuration (e.g., configuration 1), considers that the timeAlignmentTimer started and / or maintained by DU 174 for UE 102 has expired; (iii) sets the NDI of the DL HARQ process to a value of 0; (iv) refreshes the soft buffer of the UL HAR Q process; (v) for each of the UL HARQ processes, considers the next received transmission of the TB to be the first transmission; (vi) resets one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER); (vii) and the like.

[0164] 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 portion of some or all of the actions in a complete UE MAC reset.

[0165] 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), then the timeAlignmentTimer of UE 102 is considered expired; (ii) flushing the Msg3 buffer; (iii) flushing the MSGA buffer; (iv) releasing any temporary C-RNTI; and / or (v) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0166] In some implementations, the partial UE MAC reset further includes at least one of the following actions: (i) cancelling (if any) the triggered scheduling request process; (ii) cancelling (if any) the triggered buffer status reporting process; (iii) cancelling (if any) the triggered power headroom reporting process; (iv) cancelling (if any) the triggered consistent LBT failure; (v) cancelling (if any) the triggered BFR; (vi) cancelling (if any) the triggered sidelink buffer status reporting process; (vii) cancelling (if any) the triggered pre-empted buffer status reporting process; (viii) cancelling (if any) the triggered timing advance reporting process; (ix) cancelling (if any) the triggered recommended bit rate query process; (x) cancelling (if any) the triggered configured uplink grant confirmation; (xi) cancelling (if any) the triggered configured sidelink grant confirmation; (xii) cancelling (if any) the triggered expected protection symbol query; and / or (xiii) cancelling (if any) the triggered positioning measurement gap activation / deactivation request process.

[0167] In some implementations, the partial UE MAC reset further 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 DL ​​HARQ processes; and / or (v) for each of the DL HARQ processes, treating the next received transmission of the TB as the first transmission.

[0168] 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 portion of some or all of the actions in a complete DU MAC reset.

[0169] 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 DU 174 is considered to have expired a timeAlignmentTimer started and / or maintained by UE 102; and / or (ii) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0170] 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 for the DL HARQ process to a value of 0; (iii) flushing soft buffers for the UL HARQ processes; (iv) for each of the UL HARQ processes, treating the next received transmission of the TB as the first transmission; and / or (v) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0171] In some implementations, configuration 1 includes or does not include one or more RLC reestablishment indications (e.g., reestablishRLC fields) that configure UE 102 to reestablish one or more RLC entities (e.g., RLC 206B) that UE 102 uses to communicate with DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If configuration 1 includes an RLC reestablishment indication that configures UE 102 to reestablish an RLC entity (e.g., RLC 206B) that UE 102 uses to transmit RLC PDUs with base station 104 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331), UE 102 reestablishes the RLC entity in response to the RLC reestablishment indication. In some implementations, UE 102 reestablishes the RLC entity before performing 332 a random access procedure or communicating 336 with base station 104 via cell 124B. In other implementations, the UE 102 reestablishes the RLC entity while or after performing the random access procedure 332. 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 segment, 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., as defined in 3GPP specification 38.322).

[0172] Otherwise, if configuration 1 does not include an RLC re-establishment indication for the RLC entity, the UE 102 avoids re-establishing the RLC entity after receiving the first configuration activation command or upon receiving the first configuration activation command. In other words, the UE 102 avoids performing actions for re-establishing the RLC entity of the UE 102 after receiving the first configuration activation command or upon receiving the first configuration activation command. 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 full configuration, the UE 102 re-establishes the RLC entity of the UE 102 after receiving the first configuration activation command or upon receiving the first configuration activation command. Otherwise, if configuration 1 or element 1 does not include an RLC re-establishment indication and an indication that configuration 1 is a full configuration, the UE 102 avoids re-establishing the RLC entity after receiving the first configuration activation command or upon receiving the first configuration activation command.

[0173] 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 of 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 segment, and RLC PDU (if any); (ii) stopping and resetting the timer (if running); and / or (iii) resetting the state variable to an initial value. In some implementations, the state variables and timers are currently defined (e.g., as defined in 3GPP specification 38.322).

[0174] In some implementations, the above description of configuration 1 also applies to configuration 2, ..., N.

[0175] In some implementations, after determining that UE 102 is connected to cell 124B (e.g., in response thereto), 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 that are configured for UE 102. In response, in some implementations, DU 174 ceases communicating with UE 102 on cell 124A and / or releases or suspends resources of cell 124A that are configured for UE 102 and 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 in detail in FIG. Figure 3 are collectively referred to as process 394 (e.g., UE context modification process).

[0176] Next reference Figure 4 , in 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 for scenario 300 may generally apply to scenario 400. In particular, the description for cell 124B in scenario 300 may apply to cell 124C. Further, it will be understood that some of the descriptions about scenario 300 may apply to scenario 400, but apply to one or both of S-DU 174A or T-DU 174B (e.g., events 408, 410, 432, 434, etc.).

[0177] In some implementations, after determining that the UE 102 is connected to the cell 124B (e.g., in response thereto), 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 response, in a further implementation, the S-DU 174A ceases communicating with the UE 102 on the cell 124A and / or releases or suspends resources of the cell 124A configured for the UE 102, and sends 440 a DU to CU message (e.g., a UE context modification response message) to the CU-172.

[0178] Next reference Figure 5A , in scenario 500A, base station 106 acts as a MN and base station 104 acts 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 and scenario 300 is a single connection (SC) scenario. Initially, UE 102 in DC communicates with MN 106 and SN 104. 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 in DC transmits 502 UL PDUs and / or DL ​​PDUs with MN 106 and / or SN 104 via radio bearers including SRBs and / or DRBs. In some implementations, MN 106 and / or SN 104 configure radio bearers for UE 102.

[0179] UE 102 in DC transmits 502 UL PDUs and / or DL ​​PDUs with SN 104 on an SCG that SN 104 configures for communication with UE 102. UE 102 in DC transmits UL PDUs and / or DL ​​PDUs with MN 106 on an MCG according to a MN configuration (i.e., an MCG configuration). In some implementations, the first configuration is an SN configuration (i.e., an SCG configuration). In the MN configuration, MN 106 configures an MCG that includes at least one service cell (e.g., cell 126 and / or other cells) operated by MN 106. In the first configuration, SN 106A configures an SCG that includes at least one service cell (e.g., cell 124A and / or other cells) operated by 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 multiple configuration parameters, and UE 102 receives the configuration parameters in one or more RRC messages from SN 104 (e.g., via MN 106) or on an SRB (e.g., SRB3) configured by MN 106 or SN 104 to exchange RRC messages between UE 102 and SN 104.

[0180] 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 procedure 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 then 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 the 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.

[0181] After receiving at least one measurement report (e.g., in response thereto) 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 3Events 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. After receiving the first configuration activation command, sending an acknowledgment, or determining that UE 102 is connected to cell 124B, UE 102 operating in DC with MN 106 and SN 104 communicates 536 with SN 104 on cell 124B according to configuration 1, similar to event 336.

[0182] Next reference Figure 5B , scenario 500B is generally similar to scenario 500A, except that SN 104 sends 517, 519 an RRC reconfiguration message to UE 102 via MN 106, and receives 521, 523 an RRC reconfiguration complete message 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.

[0183] Next reference Fig. 6A In scenario 600A, base station 106 acts as a MN and base station 104 acts 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. Further, it will be understood that some descriptions about 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.).

[0184] 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 .

[0185] Next reference Fig. 7AIn scenario 700A, base station 104 acts 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 act as a MN together, similar to Figure 3 Base station 104 or FIG. 5A to FIG. 6B MN 106 in, and CU 172 together with S-DU 174B acts as SN, similar to FIG. 5A to FIG. 6B SN 104 in.

[0186] In scenario 700A, UE 102 initially communicates 702 with M-DU 174A and S-DU 174B in DC, and UE 102 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 a 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 then sends 707 at least one DU-to-CU message including at least one measurement report to CU 172, similar to event 306.

[0187] 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.

[0188] Next reference Fig. 8A In scenario 800A, base station 104 acts as both MN and 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 acts as MN together with M-DU 174A, and acts as SN together with S-DU 174B. Further, it will be understood that some descriptions about scenarios 300-700B may apply to scenario 800A, but apply to one or both of S-DU 174A or T-DU 174B (e.g., events 808, 810, 832, 834, etc.).

[0189] 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.

[0190] Next, refer to Figures 9 to 13 Several example methods that may be implemented in a UE (e.g., UE 102) or a RAN node (e.g., base station 104 or 106, or DU 174) to support RLC protocol operations involving configuration activation are discussed. Figures 3 to 8B The examples and implementations described can be applied to Figures 9 to 13 .

[0191] Fig. 9 A method 900 is shown that may be implemented by a DU (eg, DU 174) for preventing an RLC re-establishment indication from being included to a UE (eg, UE 102).

[0192] Method 900 begins at block 902, where the DU communicates with the UE using an RLC bearer and a first configuration (e.g., events 302, 380, 502, 580, 702, 780). At block 904, the DU generates a second configuration for later activation and avoids including an RLC reestablishment indication for the RLC bearer in the second configuration; at block 906, the DU sends a first DU-to-CU message including the second configuration to the CU (e.g., events 310, 390, 380, 510, 590, 580, 710, 790, 780). At block 908, the DU sends the second configuration to the UE (e.g., events 316, 380, 516, 517, 580, 716, 717, 780). At block 910, the DU sends a configuration activation command to the UE to activate the second configuration (e.g., events 330, 380, 530, 580, 730, 780). At block 912, the DU communicates with the UE using the RLC bearer and the second configuration (e.g., events 332, 336, 380, 532, 536, 580, 732, 736, 780).

[0193] Fig.10 A method 1000 is shown that may be implemented by a RAN (eg, base station 104 / 106 or DU 174) for configuring and activating configuration for a UE (eg, UE 102).

[0194] Method 1000 begins at block 1002, where a RAN node communicates with a UE using an RLC bearer and a first configuration (e.g., events 302, 380, 402, 480, 502, 580, 602, 680, 702, 780, 802, 880). At block 1004, the RAN node generates a second configuration for a serving cell change for the UE. At block 1006, the RAN node determines whether to activate the second configuration later. If the RAN node determines to activate the second configuration later, the flow proceeds to block 1008. At block 1008, the RAN node avoids including an RLC reestablishment indication for the RLC bearer in the second configuration. Otherwise, if the RAN node determines not to activate the second configuration later, the flow proceeds to block 1010. That is, when the UE receives the second configuration, the RAN node determines that the UE will immediately apply the second configuration. At block 1010, the RAN node includes an RLC reestablishment indication for the RLC bearer in the second configuration. Flow proceeds from block 1010 and from block 1008 to block 1012. In some implementations, at block 1012, the RAN node (e.g., DU) sends a first DU-to-CU message including the second configuration to the CU. At block 1014, the RAN node sends the second configuration to the UE (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 616, 618, 617, 619, 716, 718, 717, 719, 780). At block 1016, the RAN node communicates with the UE according to the second configuration and the RLC bearer (e.g., events 332, 336, 380, 432, 436, 480, 532, 536, 580, 532, 636, 732, 736, 780, 832, 836, 880).

[0195] Fig.11A A method 1100A is shown that may be implemented by a DU (eg, DU 174) for reestablishing an RLC entity of a UE (eg, UE 102).

[0196] Method 1100A begins at block 1102, where the DU communicates with the UE on a first cell using an RLC entity (e.g., events 302, 380, 502, 580, 702, 780). At block 1104, the DU performs a serving cell change with the UE from the first cell to a second cell (e.g., events 332, 336, 380, 532, 536, 580, 732, 736, 780). In block 1106, the DU determines whether the serving cell change is triggered by a configuration activation command. If the DU determines at block 1106 that the serving cell change is not triggered by a configuration activation command, the process proceeds to block 1108. At block 1108, the DU reestablishes the RLC entity. At block 1110, the DU communicates with the UE on a second serving cell using the RLC entity (e.g., events 332, 336, 380, 532, 536, 580, 732, 736, 780). In some implementations, at block 1112, the DU indicates to the CU that the RLC entity is reestablished (ie, RLC reestablishment occurs for the radio bearers with which the RLC entity is associated). In some implementations, the DU sends a DU to CU message to the CU to indicate that the RLC entity is reestablished.

[0197] Otherwise, if the DU determines at block 1106 that the serving cell change is triggered by a configuration activation command, the flow proceeds to block 1114. At block 1114, the DU reestablishes the RLC entity. At block 1116, the DU communicates with the UE on the second serving cell using the RLC entity after reestablishing the RLC entity (e.g., events 332, 336, 380, 532, 536, 580, 732, 736, 780).

[0198] Fig. 11B 1 is a flow chart of an example method 1100B that is similar to method 1100A, except that method 1100B includes block 1107 instead of block 1106. In block 1107, the DU determines whether the UE is configured to reestablish an RLC entity. If the DU determines that the UE is configured to reestablish an RLC entity, the flow proceeds to block 1108. Otherwise, if the DU determines that the UE is not configured to reestablish an RLC entity, the flow proceeds to block 1114.

[0199] Fig.12 A method 1200 is shown that may be implemented by a UE (eg, UE 102) for reestablishing an RLC entity for communicating with a RAN (eg, DU 174, CU 172, base station 104 or 106, or RAN 105).

[0200] Method 1200 begins at block 1202, where the UE communicates with the RAN using a first configuration and an RLC entity (e.g., events 302, 402, 502, 602, 702, 802). At block 1204, the UE receives an RRC message including a second configuration from the RAN (e.g., events 316, 318, 416, 418, 516, 518, 517, 519, 616, 618, 617, 619, 716, 718, 717, 719, 816, 818, 817, 819). At block 1206, the UE receives a configuration activation command from the RAN to activate the second configuration (e.g., events 330, 380, 430, 530, 580, 630, 680, 730, 780, 830, 880). At block 1208, the UE determines whether the second configuration includes an RLC re-establishment indication for the RLC entity. If the UE determines that the second configuration includes an RLC re-establishment indication for the RLC entity, the flow proceeds to block 1210. At block 1210, the UE re-establishes the RLC entity in response to the configuration activation command. Otherwise, if the UE determines that the second configuration does not include an RLC re-establishment indication for the RLC entity, the flow proceeds to block 1212. At block 1212, the UE avoids re-establishing the RLC entity in response to the configuration activation command. The flow proceeds from block 1210 and from block 1112 to block 1214. In some implementations, 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 RLC entity.

[0201] Fig.13 A method 1300 is shown that may be implemented by a UE (eg, UE 102) for reestablishing an RLC entity for communicating with a RAN (eg, DU 174, CU 172, base station 104 or 106, or RAN 105).

[0202] Method 1300 begins at block 1302, where the UE communicates with the RAN using a first configuration and an RLC entity (e.g., events 302, 402, 502, 602, 702, 802). At block 1304, the UE receives an RRC message from the RAN including a second configuration, where the second configuration includes an RLC reestablishment indication (e.g., events 316, 318, 416, 418, 516, 518, 517, 519, 616, 618, 617, 619, 716, 718, 717, 719, 816, 818, 817, 819). At block 1306, the UE determines whether the RRC message is configured such that the second configuration will be activated by a configuration activation command. If the UE determines at block 1308 that the RRC message is configured such that the second configuration will be activated by a configuration activation command, the flow proceeds to block 1308. At block 1308, the UE avoids reestablishing the RLC entity in response to the RRC message. 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, 380, 430, 480, 530, 580, 630, 680, 730, 780, 830, 880). In some implementations, at block 1312, the UE reestablishes the RLC entity in response to the configuration activation command. Otherwise, if the UE determines at block 1308 that the RRC message configuration is such that the second configuration is not activated by the configuration activation command (i.e., the RRC message activates the second configuration), the flow proceeds to block 1314. At block 1314, the UE reestablishes the RLC entity in response to the RRC message.

[0203] The following description can be applied to the above description.

[0204] In general, the description of one of the figures in the above drawings may apply to another figure in the above drawings. 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 used to replace "message", and vice versa. In some implementations, "IE" is used and "field" can be used to replace "IE", and vice versa. In some implementations, "configuration" or "configuration parameters" can be used to replace "configuration", and vice versa. In some implementations, "serving cell change command", "layer 1 / layer 2 exchange command", "lower layer exchange command" or "lower layer serving cell change command" can be used to replace "configuration activation command". "Fast serving cell configuration process" can be replaced with "fast serving cell change process".

[0205] 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 (headunit) or an advanced driver assistance system (ADAS) of a vehicle. Further, the user device can act 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.

[0206] 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-temporary machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and can be configured or arranged in a particular manner. A hardware module may include a dedicated circuit system (circuitry) 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 (e.g., as contained in a general-purpose processor or other programmable processor) that are temporarily configured by software to perform certain operations. 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) can be driven by cost and time considerations.

[0207] 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.

[0208] After reading this disclosure, those skilled in the art will understand additional and alternative structural and functional designs for handling mobility between base stations through the principles disclosed herein. Therefore, although specific embodiments and applications have been shown and described, it should be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations that will be apparent to those of ordinary skill in the art may be made to the arrangement, operation and details of the methods and apparatus disclosed herein without departing from the spirit and scope defined in the appended claims.

Claims

1. A method implemented in a user equipment UE, the method comprising: communicating with a radio access network, RAN, according to a first configuration, including using a radio link control, RLC, entity; receiving a second configuration from the RAN for use after receiving an activation command; receiving the activation command from the RAN; as well as In response to the activation command: Communicating with the RAN using the second configuration includes determining whether to re-establish the RLC entity based on an instruction from the RAN.

2. The method of claim 1, wherein determining whether to reestablish the RLC entity comprises determining whether the second configuration includes an RLC reestablishment indication based on whether the second configuration includes an RLC reestablishment indication.

3. The method according to claim 1 or 2, further comprising: The RLC entity is reestablished before performing a random access procedure according to the second configuration.

4. The method according to claim 1 or 2, further comprising: The RLC entity is reestablished after performing a random access procedure according to the second configuration.

5. The method according to claim 1 or 2, further comprising: Reestablishing the RLC entity includes discarding one or more of the following: RLC service data unit SDU, RLC SDU segment, or RLC protocol data unit PDU.

6. The method of claim 1, 2 or 5, further comprising: A timer associated with the RLC entity is reset.

7. The method of claim 1, 2 or 5, further comprising: State variables associated with the RLC entity are reset to initial values.

8. The method of claim 2, further comprising: Reestablishing the RLC entity is avoided in response to determining that the second configuration omits the RLC reestablishment indication.

9. The method of any preceding claim, wherein determining whether to re-establish the RLC entity is further based on whether the UE is configured to re-establish the RLC entity.

10. A method as claimed in any one of the preceding claims, wherein: The second configuration includes a fast serving cell configuration, and The activation command is based on a lower layer measurement report from the UE.

11. A user equipment UE, comprising: Transceiver; as well as Processing hardware configured to implement a method as claimed in any one of the preceding claims.

12. A method implemented in a Radio Access Network (RAN) node, the method comprising: communicating with a user equipment UE according to a first configuration; generating a second configuration, comprising: when the second configuration is to be activated at the UE via a command from the RAN, avoiding including a reestablishment indication for a radio link control (RLC) bearer in the second configuration; as well as Sending the second configuration to the UE.

13. The method of claim 12, further comprising: after said sending of said second configuration, sending an activation command to said UE; as well as Communicate with the UE according to the second configuration and using the RLC bearer.

14. The method of any one of claims 12 or 13, wherein: The RAN node is a distributed unit DU of a distributed base station; The method further comprises: sending the second configuration to the CU; and A radio resource control (RRC) message addressed to the UE is received from the CU, the RRC message including the second configuration.

15. A network node comprising processing hardware configured to implement a method according to any preceding claim.

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