Managing serving cell changes in user equipment

Abstract

A user equipment (UE) communicates with a radio access network (RAN) according to a first configuration using a media access control (MAC) entity associated with a group of cells. The UE receiving a second configuration from the RAN for use after receiving the activation command; receiving an activation command from the RAN; and communicating with the RAN using a second configuration in response to the activation command. The UE determines whether to reset the MAC entity according to the 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 / 409,780, entitled “MANAGING A SERVING CELL CHANGE INA USER EQUIPMENT,” filed on September 24, 2022. The entire contents of the provisional application are hereby expressly incorporated herein by reference. Technical Field

[0003] The present disclosure relates to wireless communications, and more particularly to enabling fast serving cell change for a user equipment (UE) using control signaling at a protocol layer lower than a 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 referred to 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] The UE uses several types of SRBs and DRBs depending on the scenario. When operating in dual connectivity (DC), the cell associated with the base station operating as a master node (MN) defines a master cell group (MCG), and the cell associated with the base station operating as a secondary node (SN) defines a secondary cell group (SCG). SRB1 resources carry RRC messages including NAS messages on a dedicated control channel (DCCH) in some cases, and SRB2 resources support RRC messages including logged measurement information or NAS messages also on the DCCH but with a lower priority than SRB1 resources. More generally, SRB1 and SRB2 resources allow the UE and MN to exchange RRC messages related to the MN and embed RRC messages related to the SN, and may be referred to as MCG SRBs. SRB3 allows the UE and SN to exchange RRC messages related to the SN, and may be referred to as SCG SRBs. Separate 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., components of a base station or a distributed base station) interconnected by backhaul. When such network nodes support different radio access technologies (RATs), this type of connection is called multi-radio dual connection (MR-DC). When the UE operates in MR-DC, one base station operates as a master node (MN) covering a primary cell (PCell), and another base station operates as a secondary node (SN) covering a primary secondary cell (PSCell). The UE communicates with the MN (via the PCell) and 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 when the UE should establish a radio connection with another base station. For example, a base station determines to hand over the UE to a second base station and initiates a handover 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 a certain moment. 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 configured with synchronized reconfiguration (e.g., the RRC reconfiguration message includes a ReconfigurationWithSync IE) to change the serving cell (e.g., PCell or PSCell). In the 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 complete L2 (and L1) reset, resulting in longer latency, greater overhead, and longer interruption time. Therefore, it is expected to develop new mobility technologies 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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);

[0010] Figure 1B is included in Figure 1A A block diagram of an example base station of a centralized unit (CU) and a distributed unit (DU) operating in a system of FIG.

[0011] Figure 2 yes Figure 1A A block diagram of an example protocol stack according to which a UE communicates with a base station;

[0012] Figure 3 is a message passing diagram for an example scenario in which a base station configures a UE to perform lower layer procedures for a cell change operation;

[0013] Figure 4 is a message passing diagram for an example scenario in which a base station configures a UE to perform lower layer procedures for an inter-DU cell change operation;

[0014] Figure 5A is a message passing diagram of an example scenario in which a MN operates with a SN in a DC to perform lower layer procedures for a cell change operation;

[0015] 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;

[0016] 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;

[0017] 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;

[0018] Fig. 7A is with Figure 5A A message passing diagram of an example scenario similar to that of , but in which the base station operates as a MN (e.g., M-DU) and a SN (e.g., S-DU) to perform a cell change operation;

[0019] 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;

[0020] 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;

[0021] 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;

[0022] Fig. 9A is a flow chart depicting an example method implemented in a UE, wherein the UE receives an RRC message including a second configuration and including a MAC retention indication, and the UE refrains from resetting a MAC entity;

[0023] Fig. 9B It is depicted with Fig. 9A A flowchart of an example method similar to an example method of , but wherein the RRC message excludes the MAC retention indication and the UE resets the MAC entity;

[0024] Fig. 9C It is depicted with Fig. 9A A flowchart of an example method similar to the example method of , but wherein the UE resets the MAC entity;

[0025] Fig.9D It is depicted with Fig. 9B A flowchart of an example method similar to an example method of , but wherein the UE avoids resetting the MAC entity;

[0026] Fig.9E It is depicted with Fig. 9AA flowchart of an example method similar to an example method of , but wherein the RRC message includes a partial MAC reset indication and the UE partially resets the MAC entity;

[0027] Fig.9F It is depicted with Fig.9E A flowchart of an example method similar to an example method of , but wherein the RRC message excludes the partial MAC reset indication and the UE completely resets the MAC entity;

[0028] Figure 9G It is depicted with Fig. 9A A flowchart of an example method similar to the example method of , but wherein the UE receives a second configuration and partially resets the MAC entity;

[0029] Fig. 10A is a flowchart depicting an example method implemented in a UE, wherein the UE determines whether to perform based on whether the RRC message or the second configuration includes a MAC reservation indication Fig. 9A or Fig. 9B Actions;

[0030] Fig. 10B It is depicted with Fig. 10A A flowchart of an example method similar to an example method of the present invention, but wherein the UE determines whether to perform the MAC reset indication based on whether the RRC message or the second configuration includes a MAC reset indication. Fig. 9C still Fig.9D Actions;

[0031] Fig. 10C It is depicted with Fig. 10A A flowchart of an example method similar to an example method of the present invention, but wherein the UE determines whether to perform based on whether the RRC message or the second configuration includes a MAC retention indication or a MAC reset indication. Fig. 9A still Fig. 9C Actions;

[0032] Fig. 10D It is depicted with Fig. 10A A flowchart of an example method similar to an example method of the present invention, but wherein the UE determines whether to perform a MAC partial reset indication based on whether the RRC message or the second configuration includes a MAC partial reset indication. Fig.9E still Fig.9F Actions;

[0033] Fig.10E It is depicted with Fig. 10A A flowchart of an example method similar to the example method of the embodiment of the present invention, but wherein the UE determines whether to perform the configuration activation command based on whether the UE receives the configuration activation command. Figure 9G The action is still to perform a full reset;

[0034] Fig.11Ais a flow chart depicting an example method implemented in a DU, wherein the DU sends a second configuration including a MAC reservation indication to a CU;

[0035] Fig. 11B It is depicted with Fig.11A A flowchart of an example method similar to the example method of , but wherein the DU sends a message including a second configuration and a MAC retention indication;

[0036] Fig. 11C It is depicted with Fig.11A A flowchart of an example method similar to the example method of , but wherein the second configuration excludes the MAC reservation indication;

[0037] Fig.11D It is depicted with Fig. 11B A flowchart of an example method similar to an example method of, but wherein the message excludes a MAC reservation indication;

[0038] Fig.11E It is depicted with Fig.11A A flowchart of an example method similar to the example method of , but wherein the second configuration includes a MAC reset indication;

[0039] Fig.11F It is depicted with Fig. 11B A flowchart of an example method similar to the example method of , but wherein the message includes a MAC reset indication;

[0040] Fig.11G It is depicted with Fig. 11C A flowchart of an example method similar to the example method of, but wherein the second configuration excludes the MAC reset indication;

[0041] Fig.11H It is depicted with Fig.11D A flowchart of an example method similar to the example method of, but wherein the message excludes a MAC reset indication;

[0042] Fig.12 is a flow chart depicting an example method implemented in a DU, wherein the DU determines whether to perform a reset based on whether the DU configures the UE to reset the MAC entity Fig.11A , Fig. 11B , Fig.11G or Fig.11H The action is still Fig. 11C , Fig.11D , Fig.11E or Fig.11F Actions;

[0043] Fig.13A is a flow chart depicting an example method implemented in a CU, wherein the CU receives a message including a first configuration and a MAC reservation indication;

[0044] Fig. 13BIt is depicted with Fig.13A A flowchart of an example method similar to an example method of, but wherein the message excludes a MAC reservation indication;

[0045] Fig. 13C It is depicted with Fig.13A A flowchart of an example method similar to the example method of , but wherein the message includes a MAC reset indication;

[0046] Fig.13D It is depicted with Fig. 13C A flowchart of an example method similar to the example method of, but wherein the message excludes a MAC reset indication;

[0047] Fig.14A is a flow chart depicting an example method implemented in a CU, wherein the CU determines whether to send a MAC reservation indication to a UE based on whether a message includes a MAC reservation indication;

[0048] Fig. 14B It is depicted with Fig.14A A flowchart of an example method similar to the example method, but wherein the determination is about a MAC reset indication;

[0049] Fig. 14C It is depicted with Fig.14A A flowchart of an example method similar to the example method of, but wherein the determination is about a MAC retention indication and / or a MAC reset indication;

[0050] Fig.15A is a flow chart depicting an example method implemented in a DU, wherein the DU determines whether to reset a MAC entity based on whether a serving cell change is triggered by the DU or the CU; and

[0051] Fig. 15B It is depicted with Fig.15A An example method is similar to a flowchart of an example method, but wherein the determination is based on whether the DU configures the UE to reset the MAC entity. DETAILED DESCRIPTION

[0052] Figure 1A An example wireless communication system 100 is depicted in which a communication device may implement these techniques. The wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The UE 102 initially connects to the base station 104. In some scenarios, the base station 104 may perform an SN add to configure the UE 102 to operate in dual connectivity (DC) with the base station 104 and the base station 106. The base stations 104 and 106 operate as a MN and a SN, respectively, for the UE 102.

[0053] In various configurations of the wireless communication system 100, the base station 104 may be implemented as a master eNB (MeNB) or a master gNB (MgNB), and the base station 106 may be implemented as a secondary gNB (SgNB). The UE 102 may communicate with the base station 104 and the base station 106 via the same RAT such as EUTRA or NR or via different RATs. When the base station 104 is a MeNB and the base station 106 is an SgNB, the UE 102 may be in EUTRA-NR DC (EN-DC) with the MeNB and the SgNB.

[0054] 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.

[0055] In a scenario where UE 102 is handed over from base station 104 to base station 106, base stations 104 and 106 operate as a source base station (S-BS) and a target base station (T-BS), respectively. For example, before the handover, UE 102 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 single connection (SC). In this case, base stations 104 and 106 operate as a source MN (S-MN) and a target MN (T-MN), respectively.

[0056] 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 typically 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 typically 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.

[0057] like Figure 1A As illustrated, 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 in DC, where one of base stations 104 and 106 is a MN and the other is a SN. Base station 104 may support additional cells such as cells 124B and 124C, and base station 106 may support additional cells ( Figure 1A 124B and 124C may partially overlap so that the UE 102 may communicate with the base station 104 in carrier aggregation (CA). The base station 104 may operate the cells 124A, 124B, and 124C via one or more transmission and reception points (TRPs). More specifically, when the UE 102 is in DC with the base station 104 and the base station 106, one of the base stations 104 and 106 operates as a MeNB, Mng-eNB, or MgNB and the other operates as a SgNB or Sng-eNB.

[0058] 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.

[0059] 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 executed by the one or more general-purpose processors. Additionally or alternatively, the processing hardware 130 may include a dedicated processing unit. The processing hardware 130 may include a PHY controller 132, which is configured to send data and control signals on a physical downlink (DL) channel and 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 on a physical uplink (UL) channel and / or UL reference signals 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, which is configured to perform MAC functions with one or more user devices. MAC functions include random access (RA) procedures, managing UL timing advance of one or more user devices, and / or communicating UL / DL MAC PDUs with one or more user devices. Processing hardware 130 may further include an RRC controller 136 for implementing procedures and message delivery at the RRC sublayer of the protocol communication stack. For example, RRC controller 132 may be configured to support RRC message delivery associated with a handover process, and / or support necessary operations when base station 104 operates as a MN relative to a SN or as a SN relative to a MN. Base station 106 may include processing hardware 140 similar to processing hardware 130. In particular, components 142, 144, and 146 may be similar to components 132, 134, and 136, respectively.

[0060] UE 102 is equipped with processing hardware 150, 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. PHY controller 152 is also configured to receive data and control signals on physical DL channels and / or DL ​​reference signals with 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. PHY controller 152 is also configured to send data and control signals on physical UL channels and / or UL reference signals with 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, which is configured to perform MAC functions with 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 for implementing procedures and messaging at the RRC sublayer of the protocol communication stack.

[0061] 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.

[0062] Figure 1BAn example distributed implementation of a base station, such as base station 104 or 106, is depicted. In this implementation, the base station may include a centralized unit (CU) 172 and one or more distributed units (DUs) 174. CU 172 is equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or dedicated processing units. In one example, CU 172 is equipped with processing hardware 130. In another example, CU 172 is equipped with processing hardware 140. In an example implementation, processing hardware 140 includes an SN RRC controller 142, which is configured to manage or control one or more RRC configurations and / or RRC processes when base station 106 operates as an SN. DU 174 is also equipped with processing hardware, which may include one or more general-purpose processors (such as CPUs) and non-transitory computer-readable memory storing machine-readable instructions that can be executed on one or more general-purpose processors, and / or dedicated processing units. In some examples, in an example implementation, the processing hardware includes: a medium access control (MAC) controller configured to manage or control one or more MAC operations or procedures (e.g., a random access procedure); and a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures when the base station 106 operates as a MN or a SN. The processing hardware may further include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0063] Next, Figure 2 The radio protocol stack is illustrated 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.

[0064] The physical layer (PHY) 202A of EUTRA provides transport channels to the EUTRA medium access control (MAC) sublayer 204A, which in turn provides logical channels to the EUTRA radio link control (RLC) sublayer 206A, and the EUTRA RLC sublayer in turn provides RLC channels to the EUTRA PDCP sublayer 208, and in some cases 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 illustrated in A, UE 102 can support NR PDCP 210 layered on EUTRA RLC 206A.

[0065] 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.

[0066] On the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 provide SRBs to exchange, for example, 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.

[0067] When UE 102 operates in EUTRA / NR DC (EN-DC) in which base station 104 operates as a MeNB and base station 106 operates as an SgNB, the network may provide UE 102 with MN-terminated bearers using EUTRA PDCP 208, or MN-terminated bearers using NR PDCP 210. In various scenarios, the network may also provide UE 102 with SN-terminated bearers using only NR PDCP 210. The MN-terminated bearer may be an MCG bearer or a separated bearer. The SN-terminated bearer may be an SCG bearer or a separated bearer. The MN-terminated bearer may be an SRB (e.g., SRB1 or SRB2) or a DRB. The SN-terminated bearer may be an SRB (e.g., SRB1 or SRB2) or a DRB.

[0068] Next, several example scenarios, including Figure 1A A base station operating in the system sends a configuration to UE 102 and later activates the configuration for communication between UE 102 and the base station. Figures 3 to 7B Similar events in the same manner are labeled with similar reference numerals (e.g., event 316 is similar to Figure 4 A and Figure 4 B's event 416, Figure 5A Event 516, Figure 5B Event 517, Fig. 6A Event 616, Figure 6B Event 617, Fig. 7A Event 716 and Figure 7B Event 717), the 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 numerals in other figures.

[0069] 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 cells. In other implementations, UE 102 communicates with DU 174 only on cell 124A. In some implementations, UE 102 communicates with DU 174 on cell 124A and / or other cells via one or more TRPs. In some implementations, cell 124A is a PCell. In such cases, other cells include SCells and / or additional cells associated with PCell or SCell. In other implementations, cell 124A is an SCell, and one of the other cells is a PCell. In such cases, 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.

[0070] In some implementations, in event 302, UE 102 sends UL PDU and / or UL control signal to base station 104 via one or more TRPs on cell 124A and / or other cells. In some implementations, UE 102 communicates UL PDU and / or DL ​​PDU with base station 104 via a radio bearer, which includes SRB and / or DRB. In a further implementation, base station 104 configures the radio bearer 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 a further implementation, UE 102 receives DL PDU and / or DL ​​control signal from base station 104 on cell 124A and / or other cells via one or more TRPs. In some implementations, the DL control signal includes downlink control information (DCI) and reference signals (e.g., synchronization signal blocks, channel state information reference signals (CSI-RS) and / or tracking reference signals). In 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.

[0071] 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 configuration parameters in CSI-MeasConfig IE, MeasConfig IE, and / or RadioBearerConfig IE. In some implementations, UE 102 receives the configuration parameters from base station 104. In other implementations, UE 102 receives a portion of the configuration parameters from a base station other than base station 104, and receives the remaining portion of the configuration parameters from base station 104.

[0072] 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 L3 measurement report in the L3 measurement report, the DU 174 sends 306 a DU to CU message including the L3 measurement report to the CU 172. In some implementations, the DU to CU message of event 306 is an F1 application protocol (F1AP) message (e.g., an UL RRC messaging message). In some implementations, the UE 102 does not send or avoids sending the L1 measurement report to the CU 172. The at least one serving cell includes the cell 124A and / or other cells, and the at least one non-serving cell includes the cell 124B and / or the cell 124C. In some implementations, the first configuration includes at least one measurement configuration. In some implementations, 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, as described above. 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 38.331 v18.0.0 and / or later versions)). 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 for triggering UE 102 to send the new measurement report.If the UE 102 detects a triggering event, the UE 102 sends a new type of measurement report to the DU 174 .

[0073] In some implementations, the L1 measurement report includes at least one L1 measurement result. In some implementations, the at least one L1 measurement result includes at least one L1 reference signal received power (L1-RSRP) value and / or at least one L1 signal to interference and noise ratio (L1-SINR) value. In some implementations, for each L1 measurement report in the L1 measurement report, the UE 102 sends a PUCCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each L1 measurement report in the L1 measurement report to the DU 174 on the PUCCH. In other implementations, for each L1 measurement report in the L1 measurement report, the UE 102 sends a PUSCH transmission including the L1 measurement report to the DU 174. That is, the UE 102 sends each L1 measurement report in the L1 measurement report to the DU 174 on the PUSCH. In yet other implementations, the UE 102 sends a portion of the L1 measurement report on the PUCCH and sends the remainder of the L1 measurement report to the DU 174 on a physical UL shared channel (PUSCH). That is, for each of the portions 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 remainder of the L1 measurement report, the UE 102 sends a PUSCH transmission including the L1 measurement report to the DU 174. In some implementations, each of the L1 measurement reports in the L1 measurement report is a portion of channel state information (CSI) (i.e., a CSI component) or CSI. In some implementations, the UE 102 includes other CSI components in the above-mentioned PUCCH transmission and / or PUSCH transmission. In some implementations, other CSI components include components such as a channel quality indicator (CQI), a precoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), a synchronization signal (SS) / physical broadcast channel (PBCH) resource block indicator (SSBRI), a layer indicator (LI) and / or a rank indicator (RI).

[0074] In some implementations, each L3 measurement report in the L3 measurement report includes at least one L3 measurement result. In some implementations, at least one L3 measurement result includes at least one RSRP (value) and / or at least one SINR (value). In some implementations, the UE 102 sends each L3 measurement report in the L3 measurement report to the CU 172 via the DU 174 on the PUSCH. In some implementations, each L3 measurement report in the L3 measurement report is an RRC message (e.g., a MeasurementReport message). In some implementations, each L3 measurement configuration in the L3 measurement configuration includes a specific measurement identifier (e.g., measId), and each L3 measurement report in the L3 measurement report includes a specific measurement identifier in a specific L3 measurement configuration. In some implementations, when the CU 172 receives the L3 measurement report including the measurement identifier and the L3 measurement result from the UE 102 via the DU 174, the CU 172 determines that the L3 measurement report is associated with the L3 measurement configuration identified by the measurement identifier.

[0075] In some alternative implementations, for each measurement report in 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 MAC CEs in the MAC CE.

[0076] 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 on cell 124C and / or other cells.

[0077] 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 than (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 than (e.g., higher than) cell 124A, 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.

[0078] In some implementations, if CU 172 determines to prepare cell 124B, CU 172 sends 308 to DU 174 a first CU-to-DU message 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 to CU 172 a first DU-to-CU message including the second configuration. 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.

[0079] 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 then sends 322 a second DU-to-CU message including the RRC reconfiguration complete message to CU 172. In some implementations, CU 172 performs security protection (e.g., integrity protection and / or ciphering) on ​​the RRC reconfiguration message. For example, CU 172 generates 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).

[0080] 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 some cases for the UE context modification requirement message, CU 172 sends a UE context modification confirmation message to DU 174 in response to the UE context modification requirement message. 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 DU 174 sends a second DU to CU message (e.g., a UE context modification response message) to CU 172 in response to the second CU to DU message.

[0081] Events 308 and 310 in Figure 3 It is collectively referred to as the service cell preparation process 390.

[0082] In some implementations, CU 172 includes a field or IE in the RRC reconfiguration message of events 316 and 318 to indicate to UE 102 that configuration 1 is not applied immediately. In some implementations, the field or IE is currently defined (e.g., in 3GPP specification 38.331 v18.0.0 and / or later versions). In further implementations, the field or IE is newly defined (e.g., in 3GPP 6G specifications). In some implementations, the field or IE is an indicator. If the RRC reconfiguration message of event 318 includes 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, the UE 102 avoids applying the configuration immediately. Otherwise, if the configuration is not included in the container, the UE 102 applies the configuration immediately.

[0083] 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 a first container and includes the first container in a first DU to CU message. In some implementations, the first container is a first addition or modification list (e.g., ConfigToAddModList IE, CellConfigToAddModList IE, MobilityToAddModList IE, MobilityConfigToAddModListIE, or CellGroupConfigToAddModList IE). Base station 104 includes configuration 1 in a first element (referred to herein as element 1) of the first addition or modification list. For example, element 1 is an addition or modification IE (e.g., ConfigToAddMod IE, CellConfigToAddMod IE, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddMod IE). In some implementations, when UE 102 receives the first addition or modification list, UE 102 stores the first addition or modification list (eg, in a variable in random access memory (RAM)).

[0084] 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 for configuration 1. In other implementations, CU 172 receives ID 1 from DU 174 in a first DU-to-CU message, as described below.

[0085] 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 are described in detail below. Figure 3This is collectively referred to as the ID allocation process 392.

[0086] 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.

[0087] In some alternative implementations, DU 174 assigns ID 1 for identifying configuration 1. In some implementations, DU 174 includes ID 1 in the first DU to CU message. In 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.

[0088] In some implementations, configuration 1 includes multiple configurations for UE 102 to communicate with DU 174 on cell 124B. In some implementations, the multiple configurations include physical layer configuration parameters (e.g., PhysicalCellGroupConfig IE), MAC layer configuration parameters (e.g., MAC-CellGroupConfig IE), and / or RLC configuration parameters (e.g., RLC-BearerConfig IE). In some further implementations, the multiple configurations include special cell configurations (e.g., SpCellConfig IE) and / or one or more SCell configurations (e.g., SCellConfig IE).

[0089] 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 has not yet 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 has synchronized with the cell 124B in the UL, the DU 174 determines not to include the random access configuration in configuration 1. 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, as described below. Otherwise, if configuration 1 does not include a random access configuration, UE 102 skips the random access procedure of event 332 in response to configuration 1 excluding the random access configuration.

[0090] In some implementations, regardless of whether cells 124A and 124B are synchronized, DU 174 includes the random access configuration in configuration 1. In some implementations, if cell 124A and cell 124B are synchronized, DU 174 determines to include a first indication in configuration 1, which configures UE 102 not to perform a random access procedure on cell 124B. Otherwise, if cell 124A is not synchronized with cell 124B, DU 174 determines not to include the first indication in configuration 1. In other implementations, if DU 174 determines that UE 102 is synchronized with cell 124B in UL, DU 174 determines to include the first indication in configuration 1. Otherwise, if DU 174 determines that UE 102 is not synchronized with cell 124B in 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, UE 102 performs the random access procedure in event 332 according to the random access configuration in response to configuration 1 excluding the first indication, as described below.

[0091] In some implementations, DU 174 includes a reconfiguration configuration with synchronization (e.g., ReconfigurationWithSync IE) in Configuration 1 or a special cell configuration. In other implementations, DU 174 does not include a reconfiguration configuration with synchronization (e.g., ReconfigurationWithSync IE) in Configuration 1 or a special cell configuration. In some implementations, if cell 124A and cell 124B are not synchronized, base station 104 determines to include a reconfiguration configuration with synchronization in Configuration 1. Otherwise, if cell 124A and cell 124B are synchronized, DU 174 determines not to include a reconfiguration configuration with synchronization in Configuration 1. In other implementations, if DU 174 determines that UE 102 has not synchronized with cell 124B in UL, DU 174 determines to include a reconfiguration configuration with synchronization 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 the reconfiguration configuration with synchronization in configuration 1. In some implementations, if configuration 1 includes the reconfiguration configuration with synchronization, UE 102 performs the random access procedure in event 332 as described below in response to or according to the reconfiguration configuration with synchronization. Otherwise, if configuration 1 does not include the reconfiguration configuration with synchronization, UE 102 skips the random access procedure of event 332. In some implementations, DU 174 includes the 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.

[0092] 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 the 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 among the other cells is higher than a corresponding predetermined threshold and / or better than (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 higher than the first predetermined threshold and / or better than (e.g., higher than) the cell 124A, the DU 174 determines to prepare the particular cell for the UE 102. In some implementations, the corresponding predetermined threshold of the other cells is different from the first predetermined threshold. In further implementations, the corresponding predetermined threshold of the other cells is the same as the first predetermined threshold. In some implementations, the corresponding predetermined threshold of the other cells is the same as the first predetermined threshold. Alternatively, the base station 104 determines to prepare the other cells for the UE 102 regardless of whether the measurement report is received from the UE 102.

[0093] In some implementations, in response to a determination 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 of the at least one serving cell preparation process, which is similar to the first CU-to-DU message. 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 the CU-to-DU message of the serving cell preparation process, which is similar to the first CU-to-DU message. In the serving cell preparation process, DU 174 generates configurations 2, ..., N, each of which configures a specific cell in the other cells, and sends configurations 2, ..., N to CU 172, as described for configuration 1. "N" is an integer and is greater than one. For example, "N" is 2, 4, 6, 8, 10, 12, 14, or 16. The examples and implementations of Configuration 1 are applicable to Configuration 2, ..., N.

[0094] In other implementations, CU 172 determines to prepare other cells in process 390. In some such cases, CU 172 includes a cell ID of each of the other cells in the first CU to DU message, and DU 174 includes 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.

[0095] 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 in the RRC reconfiguration message for identifying configuration 2, ..., N, respectively. 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.

[0096] In some implementations, CU 172 assigns IDs 2, ..., N for configurations 2, ..., N. In other implementations, CU 172 receives IDs 2, ..., N from DU 174 in a first DU-to-CU message of process 390 or in a DU-to-CU message of at least one other serving cell preparation process or additional serving cell preparation processes.

[0097] 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 a case, DU 174 includes ID 2, ..., N in configurations 2, ..., N. In such a case, CU 172 does not include ID 2, ..., N in the RRC reconfiguration message, the first container, and / or elements 2, ..., N.

[0098] 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 configuration in configuration 2, ..., N in the RRC reconfiguration message, the first container, and / or element 1.

[0099] 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 a second container and includes the second container in a first DU to CU message or a DU to CU message of other serving cell preparation procedures. 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, 322. In some implementations, the second container is a second addition or modification list (e.g., ConfigToAddModList IE, CellConfigToAddModList IE, MobilityToAddModList IE, MobilityConfigToAddModList IE, or CellGroupConfigToAddModList IE), and each element in 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 UE 102 receives the second addition or modification list, UE 102 stores the second addition or modification list together with the first addition or modification list (e.g., in a variable in RAM).

[0100] In some implementations, the DU 174 includes the cell IDs 2, ..., N in the configurations 2, ..., N, respectively. The cell IDs 2, ..., N identify the 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.

[0101] In some implementations, each of Configuration 1, ..., N and / or Configuration 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.

[0102] In some implementations, CU 172 sends a release list to UE 102 via DU 174 to release one or more configurations in configurations 1, ..., N. For example, CU 172 sends an RRC reconfiguration message including the release list to UE 102 via DU 174. In response, UE 102 sends an RRC reconfiguration complete message to CU 172 via DU 174. In some implementations, base station 104 includes IDs of one or more configurations in the release list to indicate one or more configurations in the configurations to be released. UE 102 identifies one or more configurations in the configuration according to the ID, and releases one or more configurations in the configuration in response to the release list.

[0103] 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 configurations in 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 configurations in configurations 1, ..., N in response to the third addition or modification list.

[0104] In some implementations, the CU 172 determines to release one, more, or all of the configurations in configurations 1, ..., N, and sends a CU-to-DU message to the DU 174 to instruct the DU 174 to release one, more, or all of the configurations in configurations 1, ..., N. For example, the CU 172 includes one, more, or all of the IDs in IDs 1, ..., N in the CU-to-DU message to instruct the DU 174 to release one, more, or all of the configurations in 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, the DU 174 releases one, more, or all of the configurations in configurations 1, ..., N, and sends a DU-to-CU message to the CU 172. In other implementations, the DU 174 determines to release one, more, or all of the configurations in configurations 1, ..., N, and sends a DU-to-CU message including the IDs of one, more, or all of the configurations in configurations 1, ..., N to the 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, multiple, or all of configurations 1, ..., N.

[0105] 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, multiple, or all configurations of configuration 1, ..., N. In other implementations, DU 174 receives a CU to DU message including an ID of one, multiple, or all configurations of configuration 1, ..., N from CU 172 to indicate the release of one, multiple, or all configurations of configuration 1, ..., N.

[0106] Example Implementation 1

[0107]

[0108] 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 CellGroupConfigToAddMod IE2, ..., N, respectively. In some implementations, the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 1, and the second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE 2, ..., N. In a further implementation, the first CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IE1, ...,N.

[0109] 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.

[0110] Example Implementation 2

[0111] Example implementation 2 is similar to example implementation 1, except that CellGroupConfigToAddModIE does not include ConfigId.

[0112]

[0113] 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 order, then ID 1, ..., N has values ​​of X, X+1, ..., X+(N-1). In some implementations, if the base station 104 sends the second CellGroupConfigToAddModList IE to the UE 102, the UE 102 and the base station 104 replace the first CellGroupConfigToAddModList IE with the second CellGroupConfigToAddModList IE. The second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IEs 2, ..., N in order, then IDs 2, ..., N are values ​​X, X+1, ..., X+N-2. The second CellGroupConfigToAddModList IE includes CellGroupConfigToAddMod IEs 1, ..., N in order, then IDs 1, ..., N are values ​​X, X+1, ..., X+N-1. In some alternative implementations, IDs 1, ..., N are cell IDs 1, ..., N.

[0114] In some implementations, the base station 104 sends a CellGroupConfigToAddModList IE including zero CellGroupConfigToAddMod IEs to release all IEs in the CellGroupConfigToAddMod IEs 1, ...,N.

[0115] 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.

[0116] In other implementations, each of configurations 1, ..., N and / or configurations 2, ..., N is an RRCReconfiguration message. In such implementations, the following (ie, example implementations 3 to 6) are example structures of the first or second addition or modification list.

[0117] Example Implementation 3

[0118] In example implementation 3, the first or second add or modify list is a CondReconfigToAddModList-r16 IE (eg, as defined in 3GPP specification 38.331 from Release 16), and the CondReconfigToAddModIE is an element of the list.

[0119]

[0120] For example, the first addition or modification list is the first CondReconfigToAddModList-r16 IE and the second CondReconfigToAddModList-r16 IE. Element 1 is CondReconfigToAddMod-r16 IE 1, and elements 2, ..., N are CondReconfigToAddMod-r16 IE 2, ..., N, respectively. ID 1 and configuration 1 are CondReconfigId and RRCReconfiguration message in CondReconfigToAddMod IE 1, respectively. ID 2, ..., N and configuration 2, ..., N are CondReconfigId and RRCReconfiguration message in CondReconfigToAddMod IE 2, ..., N, respectively. In some implementations, the first CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 1, and the second CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 2, ..., N. In further implementations, the first CondReconfigToAddModList-r16 IE includes CondReconfigToAddMod-r16 IE 1, ..., N.

[0121] In this example implementation, the base station 104 includes the conditional configuration (i.e., condExecutionCond-r16) in at least one of the CondReconfigToAddMod-r16 IEs. In some implementations, if the UE 102 supports a conditional procedure (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 CondReconfigToAddMod-r16 IE are met, the UE 102 immediately applies the configuration in the RRCReconfiguration message in the CondReconfigToAddMod-r16 IE (e.g., as described in 3GPP specification 38.331). In some implementations, the base station 104 does not include the conditional configuration (i.e., condExecutionCond-r16) in any one or some of the CondReconfigToAddMod-r16 IEs. Thus, 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 conditions for a conditional procedure (e.g., conditional handover).

[0122] 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.

[0123] Example Implementation 4

[0124] 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 condRRCReconfig-r16 in the RRCReconfiguration message or 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.

[0125]

[0126] Example Implementation 5

[0127] Some of the example implementations 3 and 4 may involve the UE 102 supporting conditional procedures (e.g., conditional handover (CHO), conditional PSCell addition (CPA), and / or conditional PSCell change (CPC)). If the UE 102 does not support the conditional procedures, the base station 104 does not configure or enable fast serving cell change for the UE 102. Therefore, example implementation 5 is decoupled from the conditional procedures.

[0128]

[0129]

[0130] In some implementations, the first addition or modification list is a first ReconfigToAddModList IE, and the second addition or modification list is a second ReconfigToAddModList IE. Element 1 is ReconfigToAddMod IE 1, and elements 2, ..., N are ReconfigToAddMod IE 2, ..., N, respectively. ID 1 and configuration 1 are ConfigId and RRCReconfiguration IE in ReconfigToAddMod IE 1, respectively. ID 2, ..., N and configuration 2, ..., N are ConfigId and RRCReconfiguration IE in ReconfigToAddMod IE 2, ..., N, respectively. In some implementations, the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, and the second ReconfigToAddModList IE includes ReconfigToAddMod IE 2, ..., N. In further implementations, the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N.

[0131] 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 ReconfigToAddMod IEs are identified by one or more ConfigID IEs.

[0132] Example Implementation 6

[0133]

[0134] Example implementation 6 is similar to example implementation 5, except that the ReconfigToAddMod IE does not include ConfigId. In some implementations, ID 1, ..., N is implicitly indicated by the order of ReconfigToAddMod IE 1, ..., N in the first or second ReconfigToAddModList. For example, ReconfigToAddMod IE 1 is the first IE in the first ReconfigToAddModList IE, which implicitly indicates that ID 1 has a value of X. X can be zero or one. If the first ReconfigToAddModList IE includes ReconfigToAddMod IE 1, ..., N in order, then ID 1, ..., N has values ​​of X, X+1, ..., X+(N-1). In some implementations, if the base station 104 sends the second ReconfigToAddModList IE to the UE 102, the UE 102 and the base station 104 replace the first ReconfigToAddModList IE with the second ReconfigToAddModList IE. If the second ReconfigToAddModList IE includes ReconfigToAddMod IEs 2, ..., N in order, then IDs 2, ..., N have values ​​X, X+1, ..., X+N-2. If the second ReconfigToAddModList IE includes ReconfigToAddMod IEs 1, ..., N in order, then IDs 1, ..., N have values ​​X, X+1, ..., X+N-1. In some alternative implementations, IDs 1, ..., N are cell IDs 1, ..., N.

[0135] In some implementations, the base station 104 sends a ReconfigToAddModList IE including zero ReconfigToAddMod IEs to release all IEs in ReconfigToAddMod IEs 1, ...,N.

[0136] In example implementations 5 and 6, “ReconfigToAddModList,” “ReconfigToAddMod,” “configId,” “ConfigId,” “cellGroupConfig,” “ReconfigToReleaseList,” and “maxNrofConfigCells” are exemplary and should not limit the scope and application of the present invention.

[0137] Example Implementation 7

[0138] Example implementation 7 is a combination of example implementations 1 and 5, as shown below. Depending on the implementation, any of configurations 1, ..., N is a CellGroupConfig IE or an RRCReconfiguration message. The examples and implementations described for example implementations 1 and 5 are applicable to example implementation 7.

[0139]

[0140] 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 measurement report of the at least one measurement report of event 324 is not an RRC message.

[0141] 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 the measurement results. The CU 172 sends the at least one measurement configuration to the UE 102 via the DU 174. For example, after event 306 or 316, the CU 172 sends one or more RRC messages (e.g., RRCReconfiguration messages) including the at least one measurement configuration to the UE 102 via the DU 174. Depending on the implementation, the one or more RRC messages include or do not include the RRC reconfiguration message of event 316. According to the at least one measurement configuration, the UE 102 performs measurements on one or more reference signals. In some implementations, the one or more reference signals include one or more SSBs and / or one or more CSI-RSs. The UE 102 obtains at least one L1 measurement result and / or at least one L3 measurement result from the measurement, and includes the at least one L1 measurement result and / or at least one L3 measurement result in the measurement report of event 324. DU 174 transmits one or more reference signals on cells 124A and 124B and in some implementations 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.

[0142] 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).

[0143] 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.

[0144] In yet other implementations, DU 174 includes a bitmap in the first configuration activation command to activate configuration 1 instead of ID 1, cell ID 1, or cell index 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 further implementations, 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 (eg, configuration K) other than configuration 1, DU 174 sets the corresponding bit (eg, bit K or bit K-1) in the bitmap to a first value, where 1<=K<=N.

[0145] 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 for cell 124B. DU 174 determines to activate configuration 1 because at least one measurement result indicates that the signal strength or quality of cell 124B is higher than a second predetermined threshold. The second predetermined threshold is different from the first predetermined threshold. In some implementations, the second predetermined threshold is greater than the first predetermined threshold. In such implementations, at least one measurement report of event 324 indicates that the signal strength or quality of cell 124B is suitable for communication with UE 102. In 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 higher than the second predetermined threshold or the first predetermined threshold. This also indicates that cell 124B is suitable for communication with UE 102. Therefore, in response to determining that the signal strength or quality of cell 124B is higher than the second predetermined threshold, DU 174 determines to activate configuration 1 (i.e., a fast serving cell change to cell 124B).

[0146] In some implementations, at least one measurement report (e.g., L3 measurement report) of events 324 and 326 includes at least one measurement result for cell 124B. CU 172 determines to activate configuration 1 because at least one measurement result indicates that the signal strength or quality of cell 124B is higher than a second predetermined threshold. The second predetermined threshold is different from the first predetermined threshold. In some implementations, the second predetermined threshold is greater than the first predetermined threshold. In such implementations, at least one measurement report of event 326 indicates that the signal strength or quality of cell 124B is suitable for communication with UE 102. In 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, in response to determining that the signal strength or quality of cell 124B is higher than the second predetermined threshold, CU172 determines to activate configuration 1 (i.e., a fast serving cell change to cell 124B).

[0147] 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 a cell index 1 (e.g., a serving cell index) in the fourth CU-to-DU message. Therefore, DU 174 may 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 may 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 may 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 a UE context modification request message and a UE context modification response message, respectively. In other implementations, the fourth CU-to-DU message is a new interface message (e.g., an F1 Application Protocol (F1AP) message (e.g., defined in 3GPP specification 38.473 v18.0.0 and / or later versions)). In other implementations, the fourth DU-to-CU message is a new interface message (e.g., a new F1AP message (e.g., defined in 3GPP specification 38.473 v18.0.0 and / or later versions)).

[0148] In some implementations, the first configuration activation command is a MAC CE included in a MAC PDU received by UE 102 from DU 174 in event 330. In some implementations, the MAC CE is a new MAC CE (e.g., defined in 3GPP specification 38.321 v18.0.0 and / or later versions). In some implementations, DU 174 includes a subheader identifying the MAC CE in the MAC PDU, and UE 102 identifies the MAC CE in the MAC PDU based on the subheader. Depending on the implementation, the subheader includes a logical channel ID or an extended logical channel ID (e.g., defined in the 3GPP specification) to identify the MAC CE. For example, the logical channel ID or the extended logical channel ID is newly defined (e.g., in 3GPP specification 38.321 v18.0.0 and / or later versions). In other implementations, the first configuration activation command is a DCI received by UE 102 on the PDCCH in event 330. DU 174 generates a CRC for the DCI, scrambles the CRC using 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 later)).

[0149] 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 the 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.

[0150] 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., defined in 3GPP specification 38.321 v17.1.0). In another example, the MAC CE is a new MAC CE (e.g., defined in 3GPP specification 38.321 v18.0.0 and / or later versions). In yet other implementations, the acknowledgment is a PUCCH transmission.

[0151] 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 and second RRC reconfiguration messages are the same message (i.e., the same instance). In other implementations, the first and second RRC reconfiguration messages 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.

[0152] After receiving the first configuration activation command (e.g., in response thereto), 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, after receiving the first configuration activation command or sending an acknowledgement (e.g., in response thereto), the UE 102 disconnects from the cell 124A. In other words, after receiving 330 the first configuration activation command or sending 331 an acknowledgement (e.g., in response thereto), the UE 102 stops communicating on the cell 124A. In such a case, the UE 102 performs 332 a random access procedure after being disconnected from the cell 124A. In some implementations, the UE 102 determines whether to perform a random access procedure according to configuration 1. In some implementations, if configuration 1 configures UE 102 to perform a random access procedure, UE 102 performs a random access procedure in event 332. For example, configuration 1 includes a reconfiguration configuration with synchronization (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 configuration with synchronization, 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.

[0153] 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 and communicates with the CU 172 via the DU 174 using configuration 1 after successfully completing the random access procedure. For example, the UE 102 communicates UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104 in event 318. In such a case, when the UE 102 receives a contention resolution from the DU 174, the UE 102 successfully completes the random access procedure. In the case where the random access procedure is a four-step random access procedure, the UE 102 sends a message 3 including a UE identity to the DU 174 via the cell 124B during the random access procedure. In the case where the random access procedure is a two-step random access procedure, the UE 102 sends a message A including a UE identity to the DU 174 via the cell 124B during the random access procedure. In some implementations, if configuration 1 includes a second C-RNTI, the UE identity is the second C-RNTI of UE 102. Otherwise, if configuration 1 does not include a C-RNTI, the UE identity is the first C-RNTI. In the case where the random access procedure is a contention-free random access procedure, UE 102 sends a dedicated random access preamble to DU 174 via cell 124B. In such a case, configuration 1 includes a dedicated random access preamble.

[0154] 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.

[0155] 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 yet 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.

[0156] In some cases where the UE 102 skips the random access procedure, the UE 102 communicates 336 directly with the base station 104 on the cell 124B according to configuration 1 after (e.g., in response to) receiving the first configuration activation command. For example, the UE 102 communicates UL PDUs, DL PDUs, and / or physical layer signals (e.g., PUCCH transmissions and PDCCH transmissions) with the base station 104 in event 318. In some such cases, the UE 102 sends 336 at least one PUCCH transmission to the DU 174 on the cell 124B according to configuration 1 after (e.g., in response to) receiving the first configuration activation command. 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 sends at least one PUCCH or PUSCH transmission regardless of whether DCI is received 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.

[0157] 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. Thus, 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.

[0158] In some implementations, upon determining that the UE 102 is connected to the cell 124B, sending 330 a first configuration activation command, or receiving 331 an acknowledgement, the DU 174 stops communicating with the UE 102 on the cell 124A. In some implementations, upon determining that the UE 102 is connected to the cell 124B, sending 330 a first configuration activation command, or receiving 331 an acknowledgement, the DU 174 releases resources of the cell 124A configured for the UE 102.

[0159] 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.

[0160] In some implementations, DU 174 generates configuration 1 and / or configuration 2, ..., N as a full configuration, thereby replacing the first configuration or a specific configuration in the first configuration. In some implementations, if configuration 1 is a full 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 full configuration in configuration 1. In other implementations, the RRC reconfiguration message of events 316, 318 includes an indication that configuration 1 is a full configuration. In yet other implementations, the first container includes an indication that configuration 1 is a full configuration. In yet other implementations, element 1 (e.g., ConfigToAddMod IE, CellGroupConfigToAddMod, MobilityToAddMod IE, MobilityConfigToAddMod IE, or CellGroupConfigToAddMod IE) includes an indication that configuration 1 is a full configuration. In some implementations, UE 102 determines that configuration 1 is a full configuration based on the indication that configuration 1 is a full configuration. In some implementations, configuration 1 is an indication different from the fullConfig field (e.g., defined in current 3GPP specifications). In other implementations, configuration 1 is an indication of the fullConfig field (e.g., defined in current 3GPP specifications) in the RRCReconfiguration message.

[0161] In other implementations, DU 174 generates configuration 1 and / or configuration 2, ..., N as an incremental configuration that expands 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 utilize configuration 1 to expand at least a portion of the first configuration. Therefore, UE 102 and base station 104 communicate 336 with each other based on configuration 1 and the unexpanded 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.

[0162] In some implementations, if configuration 1 is a full configuration, after receiving 330 a first configuration activation command, sending 331 an acknowledgement, successfully performing 332 a random access procedure, or receiving a first DCI on a PDCCH addressed to a UE identity of UE 102 on cell 124B (e.g., in response thereto), UE 102 releases the first configuration or a specific configuration in the first configuration. In some implementations, if configuration 1 is a full configuration, after sending 330 a first configuration activation command, receiving 331 an acknowledgement, successfully performing 332 a random access procedure, or receiving a specific transmission from UE 102 on cell 124B (e.g., in response thereto), DU 174 releases the first configuration or a specific configuration in the first configuration. In some implementations, the specific transmission is a PUCCH transmission. In further implementations, the transmission is a PUSCH transmission. In a further implementation, after sending the first configuration activation command, DU 174 generates a DCI and a CRC for the DCI, scrambles the CRC using the UE identity of UE 102, and sends the DCI and the scrambled CRC on a PDCCH on cell 124B. When UE 102 receives the DCI and the scrambled CRC and verifies that the scrambled CRC is valid using the UE identity, UE 102 sends a PUSCH transmission to DU 174 on cell 124B.

[0163] 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.

[0164] 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, upon receiving the first configuration activation command, the UE 102 resets the UE MAC entity in response to the MAC reset indication.

[0165] Otherwise, if configuration 1 or element 1 does not include a MAC reset indication, the UE 102 avoids resetting the UE MAC entity upon or when receiving the first configuration activation command. 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 upon or when 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 upon or when receiving 330 the first configuration activation command.

[0166] In some implementations, the base station 104 (e.g., DU 174 or CU 172) uses a DU MAC entity (e.g., NRMAC 204B) to communicate with the UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If the base station 104 includes a MAC reset indication in configuration 1 or element 1, then after sending 330 a first configuration activation command, receiving 331 an acknowledgement, or determining in events 332 or 336 that the UE 102 is connected to the cell 124B, the DU 174 resets the DU MAC entity in response to the MAC reset indication.

[0167] 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.

[0168] 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.

[0169] In some implementations, if configuration 1 or element 1 does not include a MAC reset indication and includes an indication that configuration 1 is a full configuration, then after sending 330 the first configuration activation command, receiving 331 an acknowledgement, or determining in event 332 or 336 that UE 102 is connected to cell 124B, DU 174 resets the DU MAC entity. 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, then DU 174 avoids resetting the DU MAC entity after (e.g., in response to) sending 330 the first configuration activation command.

[0170] 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, upon receiving a configuration activation command (e.g., a first configuration activation command), the UE 102 avoids resetting the UE MAC entity in response to the MAC retention indication. Otherwise, if the configuration or element does not include the MAC retention indication, the UE 102 resets the UE MAC entity at or when the configuration activation command is received.

[0171] DU 174 uses the DU MAC entity (e.g., NR MAC 204B) to communicate with UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If base station 104 includes a MAC retention indication in a configuration or element (e.g., configuration 1 or element 1), then after sending a configuration activation command (e.g., a first configuration activation command) to UE 102, DU 174 avoids resetting the DU MAC entity in response to the MAC retention indication. Therefore, after sending 330 the first configuration activation command, receiving 331 an acknowledgment, or determining at events 332 or 336 that UE 102 is connected to cell 124B, DU 174 continues to use the retained (i.e., non-reset) DU MAC entity to communicate with UE 102.

[0172] 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.

[0173] 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.

[0174] In some implementations, the base station 104 includes or does not include an indication that configuration 1 is a full configuration. If the base station 104 includes an indication that configuration 1 is a full 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 full configuration in configuration 1 or element 1, the base station 104 includes a MAC reservation indication in configuration 1 or element 1.

[0175] 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.

[0176] If the base station 104 includes a MAC partial reset indication in a configuration or element (e.g., configuration 1 or element 1), then after sending a configuration activation command (e.g., a first configuration activation command) to the UE 102, the DU 174 partially resets the DU MAC entity in response to the MAC partial reset indication.

[0177] 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.

[0178] Otherwise, if configuration 1 or element 1 does not include a MAC partial reset indication, the DU 174 completely resets the DU MAC entity after (e.g., in response to) sending 330 the first configuration activation command. In some implementations, the base station 104 includes or does not include an indication that configuration 1 is a full configuration. In some implementations, if the base station 104 includes an indication that configuration 1 is a full 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 full 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 full configuration in configuration 1 or element 1, the base station 104 includes a MAC partial reset indication.

[0179] 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.

[0180] In some implementations, when the UE 102 determines to reset the UE MAC entity or 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 procedure (e.g., event 332) in a configuration (e.g., configuration 1), then timeAlignmentTimer is considered expired; (iv) a new data indicator (NDI) for the UL HARQ process is set to a value of 0; (v) the NDI for the HARQ process ID is set to a value of 0 for monitoring the PDCCH in sidelink resource allocation mode 1; (vi) the Msg3 buffer is flushed; (vii) the MSGA buffer is flushed; (viii) the triggered scheduling request procedure is canceled (if any); (ix) the triggered buffer status report procedure is canceled (if any); (x) the triggered power headroom report procedure is canceled (if any); (xi) the triggered consistent L BT failure; (xii) cancel (if any) triggered BFR; (xiii) cancel (if any) triggered sidelink buffer status report process; (xiv) cancel (if any) triggered preemption buffer status report process; (xv) cancel (if any) triggered timing advance reporting process; (xvi) cancel (if any) triggered recommended bit rate query process; (xvii) cancel (if any) triggered configured uplink grant confirmation; (xviii) cancel (if any) triggered configured sidelink grant confirmation; (xix) cancel (if any) triggered expected protection symbol query; (xx) cancel (if any) triggered positioning measurement gap activation / deactivation request process; (xxi) refresh the DL soft buffer for the HARQ process; (xxii) for each DL HARQ process in the DL HARQ process, 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.

[0181] In some implementations, when DU 174 resets the DU MAC entity, DU 174 performs at least one of the following actions for the DU MAC entity (i.e., a DU MAC reset or a full DU MAC reset): (i) stop one or more timers; (ii) if UE 102 is configured in a configuration (e.g., configuration 1) to perform a random access process (e.g., event 332), then the timeAlignmentTimer started and / or maintained by DU 174 for UE 102 is considered expired; (iii) the NDI for the DL HARQ process is set to a value of 0; (iv) the soft buffer for the UL HARQ process is refreshed; (v) for each UL HARQ process in the UL HARQ process, the next received transmission of the TB is considered the first transmission; (vi) one or more counters (e.g., BFI_COUNTER / or LBT_COUNTER) are reset; (vii) and the like.

[0182] 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 the complete UE MAC reset.

[0183] In some implementations, the partial UE MAC reset includes at least one of the following actions: (i) if UE 102 is configured in a configuration (e.g., configuration 1) to perform a random access procedure (e.g., event 332), then the timeAlignmentTimer of UE 102 is considered expired; (ii) flushing the Msg3 buffer; (iii) flushing the MSGA buffer; (iv) releasing (if any) the temporary C-RNTI; and / or (v) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0184] 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 preemption 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.

[0185] 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 a soft buffer for the DL HARQ process; and / or (v) for each DL HARQ process in the DL HARQ process, treating the next received transmission of the TB as the first transmission.

[0186] 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.

[0187] 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 in a configuration (e.g., configuration 1) to perform a random access procedure (e.g., event 332), then the timeAlignmentTimer started and / or maintained by DU 174 for UE 102 is considered expired; and / or (ii) resetting one or more counters (e.g., BFI_COUNTER and / or LBT_COUNTER).

[0188] In some implementations, a partial DU MAC reset includes at least one of the following actions for the MAC entity (i.e., a 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 the soft buffer for the UL HARQ process; (iv) for each UL HARQ process in the UL HARQ process, 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).

[0189] In some implementations, configuration 1 includes or does not include one or more RLC reestablishment indications (e.g., reestablishRLC fields) that configure the UE 102 to reestablish one or more RLC entities (e.g., RLC 206B) that the UE 102 uses to communicate with the DU 174 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331). If configuration 1 includes an RLC reestablishment indication that configures the UE 102 to reestablish an RLC entity (e.g., RLC 206B) that the UE 102 uses to communicate RLC PDUs with the base station 104 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331), the UE 102 reestablishes the RLC entity in response to the RLC reestablishment indication. In some implementations, the UE 102 reestablishes the RLC entity before performing 332 a random access procedure or communicating 336 with the base station 104 via the cell 124B. In other implementations, the UE 102 reestablishes the RLC entity when 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., in 3GPP specification 38.322).

[0190] 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 upon or when the first configuration activation command is received. In other words, the UE 102 avoids performing actions for re-establishing the RLC entity of the UE 102 upon or when the first configuration activation command is received. 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 upon or when the first configuration activation command is received. 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 upon or when the first configuration activation command is received.

[0191] Similarly, DU 174 reestablishes the RLC entity (e.g., NR RLC 206B) that DU 174 uses to communicate with the RLC entity of UE 102 (e.g., events 302, 304, 318, 320, 324, 330, and / or 331) in response to the RLC reestablishment indication. In some implementations, DU 174 reestablishes the RLC entity after sending the first configuration activation command, receiving an acknowledgment for the first configuration activation command from UE 102, or determining that UE 102 is connected to cell 124B. In some implementations, the acknowledgment is a HARQ ACK. In other implementations, the acknowledgment is a MAC CE. In yet other implementations, the acknowledgment is a PUCCH transmission. In some implementations, when the base station 104 reestablishes the RLC entity, the DU 174 performs at least one of the following actions for the RLC entity: (i) discarding the RLC SDU, RLC SDU 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., in 3GPP specification 38.322).

[0192] In some implementations, the above description for configuration 1 also applies to configurations 2, ..., N.

[0193] 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 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 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 occur at the same time. Figure 3 The process is collectively referred to as process 394 (e.g., UE context modification process).

[0194] Next reference Figure 4In scenario 400, base station 104 includes CU 172, source DU (S-DU) 174A, and target DU (T-DU) 174B. S-DU 174A operates cell 124A, and in some implementations operates cell 124B, while T-DU 174B operates cell 124C. Scenario 400 is similar to scenario 300. Therefore, the description for scenario 300 is generally applicable to scenario 400. In particular, the description for cell 124B in scenario 300 is applicable to cell 124C. Further, it will be understood that some descriptions about scenario 300 are applicable 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.).

[0195] 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.

[0196] Next reference Figure 5A, in scenario 500A, base station 106 operates as a MN and base station 104 operates as a SN. SN 104 includes CU 172 and DU 174. Scenario 500A is similar to scenario 300, except that scenario 500A is a DC scenario 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 communicates 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.

[0197] UE 102 in DC communicates 502 UL PDUs and / or DL ​​PDUs with SN 104 on an SCG that SN 104 configures for communicating with UE 102. UE 102 in DC communicates 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 serving 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 serving 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 (e.g., via MN 106) receives the configuration parameters in one or more RRC messages from SN 104 or on an SRB (e.g., SRB3) configured by MN 106 or SN 104 for exchanging RRC messages between UE 102 and SN 104.

[0198] In some implementations, while communicating with MN 106 and SN 104 in DC, MN 106 performs 580 a fast serving cell configuration procedure with UE 102, similar to process 380. In some implementations, while 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, while 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 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.

[0199] 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 3 Events 590, 592, 516, 518, 520, 522, 524, 526, 528, 530, 531, 532, 534, 536, and 594 are similar to events 390, 392, 316, 318, 320, 322, 324, 326, 328, 330, 331, 332, 334, 336, and 394, respectively. After receiving the first configuration activation command, sending an acknowledgment, or determining that UE 102 is connected to cell 124B, UE 102 operating with MN 106 and SN 104 in DC communicates 536 with SN 104 on cell 124B according to configuration 1, similar to event 336.

[0200] Next reference Figure 5B, scenario 500B is generally similar to scenario 500A, except that SN 104 sends 517, 519 RRC reconfiguration messages to UE 102 via MN 106 and receives 521, 523 RRC reconfiguration complete messages from UE 102 via MN 106. In some implementations, SN 104 generates a first SN message (e.g., an SN modification required message, an SN modification required message, or an RRC transfer message) including an RRC reconfiguration message, and sends the first SN message to MN 106 at event 517. In some implementations, MN 106 generates a second SN message (e.g., an SN reconfiguration complete message or an RRC transfer message) including an RRC reconfiguration complete message, and sends the second SN message to SN 104 at event 523.

[0201] Next reference Fig. 6A In scenario 600A, base station 106 operates as a MN and base station 104 operates as a SN, similar to scenarios 300-500B. SN 104 includes CU 172, S-DU 174A, and T-DU 174B, similar to base station 104 in scenario 400. 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.).

[0202] Next reference Figure 6B , scenario 600B is similar to scenarios 300 - 500B and 600A, except that SN 104 sends 617 , 619 an RRC reconfiguration message to UE 102 via MN 106 and receives 621 , 623 an RRC reconfiguration complete message from UE 102 via MN 106 .

[0203] Next reference Fig. 7A In scenario 700A, base station 104 operates as a MN and a SN, similar to scenarios 300-600B. Base station 104 includes CU 172, a master DU (M-DU) 174A, and a secondary DU (S-DU) 174B. CU 172 operates with M-DU 174A as a MN, similar to Figure 3 Base station 104 or FIG. 5A to FIG. 6B MN 106 in the MN, and CU 172 operates with S-DU 174B as SN, similar to FIG. 5A to FIG. 6B SN 104 in.

[0204] 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 and communicates with CU 172 via S-DU 174B using a first configuration. 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.

[0205] Next reference Figure 7B , scenario 700B is similar to scenarios 300-600B and 700A, except that CU 172 sends 717, 719 an RRC reconfiguration message to UE 102 via M-DU 174A and receives 721, 723 an RRC reconfiguration complete message from UE 102 via M-DU 174A.

[0206] Next reference Fig. 8A In scenario 800A, base station 104 operates as a MN and a SN, similar to scenarios 300-700B. Base station 104 includes CU 172, master DU (M-DU) 174A, secondary DU (S-DU) 174B, and T-DU 174C. CU 172 operates with M-DU 174A as a MN and operates with S-DU 174B as a SN. 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.).

[0207] Next reference Figure 8B , scenario 800B is similar to scenarios 300-700B and 800A, except that CU 172 sends 817, 819 an RRC reconfiguration message to UE 102 via M-DU 174A and receives 821, 823 an RRC reconfiguration complete message from UE 102 via M-DU 174A.

[0208] Next, refer to 9A to 10E Several example methods that may be implemented in a UE to support MAC protocol operation when activating a configuration are discussed. Figures 3 to 8B The examples and implementations described may be applicable to 9A to 10E .

[0209] Fig. 9A A method 900A is illustrated that may be implemented by a UE (eg, UE 102) for configuring and activating a configuration with a RAN (eg, base station 104 / 106 or DU 174).

[0210] Method 900A begins at block 902, where the UE communicates with the RAN using a first configuration and a MAC entity (e.g., events 302, 380, 402, 480, 502, 580, 602, 680, 702, 780, 802, 880). At block 904A, the UE receives an RRC message from the RAN including a second configuration and including a MAC retention 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 box 906, 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 box 908A, the UE avoids resetting the MAC entity in response to the MAC retention indication. In some implementations, at box 910, the UE performs a random access procedure with the RAN (e.g., events 332, 432, 532, 632, 732, 832). At box 912, the UE communicates with the RAN using the second configuration and the MAC entity (e.g., events 336, 436, 536, 636, 736, 836). In other words, the UE continues to use the MAC entity to communicate with the RAN after receiving the configuration activation command or performing the random access procedure without resetting the MAC entity.

[0211] Fig. 9B 900B is a flow chart of an example method 900B similar to method 900A, except that method 900B includes blocks 904B and 908B instead of blocks 904A and 908A. At block 904B, the UE receives an RRC message from the RAN that includes a second configuration and excludes the MAC retention indication to configure the MAC entity to reset (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 908B, the UE resets the MAC entity in response to the RRC message excluding the MAC retention indication. Therefore, at block 912, the UE communicates with the RAN using the second configuration and the MAC entity after resetting the MAC.

[0212] Fig. 9C 900A, except that method 900C includes blocks 904C and 908C instead of blocks 904A and 908A. At block 904C, the UE receives an RRC message including a second configuration and including a MAC reset indication 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 908C, the UE resets the MAC entity in response to the MAC reset indication.

[0213] Fig.9D 900D is a flow chart of an example method 900D similar to method 900A, except that method 900D includes blocks 904D and 908D instead of blocks 904A and 908A. At block 904D, the UE receives an RRC message from the RAN that includes a second configuration and excludes a MAC reset indication to configure the MAC entity to not reset (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 908D, the UE avoids resetting the MAC entity in response to the RRC message excluding the MAC reset indication.

[0214] Fig.9E 900E is a flow chart of an example method 900E similar to method 900A, except that method 900E includes blocks 904E and 908E instead of blocks 904A and 908A. At block 904E, the UE receives an RRC message from the RAN including a second configuration and a MAC partial reset indication to configure the MAC entity to be partially reset (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 908E, the UE partially resets the MAC entity in response to the MAC partial reset indication.

[0215] Fig.9F900F is a flow chart of an example method 900F similar to method 900A, except that method 900F includes blocks 904F and 908F instead of blocks 904A and 908A. At block 904F, the UE receives an RRC message from the RAN including a second configuration and excluding a MAC partial reset indication to configure the MAC entity to be fully reset (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 908F, the UE fully resets the MAC entity in response to the RRC message excluding the MAC partial reset indication.

[0216] Figure 9G 900A, except that method 900G includes blocks 904G and 908G instead of blocks 904A and 908A. At block 904G, 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 908G, the UE partially resets the MAC entity in response to the configuration activation command.

[0217] Fig. 10A A method 1000A is illustrated that may be implemented by a UE (eg, UE 102) for configuring and activating a configuration with a RAN (eg, base station 104 / 106 or DU 174).

[0218] Method 1000A begins at block 1002, where the UE communicates with the RAN using a first configuration and a MAC entity (e.g., events 302, 402, 502, 602, 702, 802). At block 1004, 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). In some implementations, at block 1006, 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 box 1008A, the UE determines whether the RRC message or the second configuration includes a MAC reservation indication. If the UE determines that the RRC message or the second configuration includes a MAC reservation indication, the process proceeds to box 1010A. At box 1010A, the UE performs the actions described above with respect to box 908A. Otherwise, if the RAN node determines that the RRC message or the second configuration does not include a MAC reservation indication, the process proceeds to box 1012A. At box 1012A, the UE performs the actions described above with respect to box 908B. The process proceeds from box 1010 and from box 1012A to box 1014. In some implementations, at box 1014, the UE performs a random access procedure with the RAN. At box 1016, the UE communicates with the RAN using the second configuration and the MAC entity.

[0219] Fig. 10B 1000A, except that method 1000B includes blocks 1008B, 1010B, and 1012B instead of blocks 1008A, 1010A, and 1012A. At block 1008B, the UE determines whether the RRC message or the second configuration includes a MAC reset indication. If the UE determines that the RRC message or the second configuration includes a MAC reset indication, the process proceeds to block 1010B. At block 1010B, the UE performs the actions described above with respect to block 908C. Otherwise, if the UE determines that the RRC message or the second configuration does not include a MAC reset indication, the process proceeds to block 1012B. At block 1012B, the UE performs the actions described above with respect to block 908D.

[0220] Fig. 10C1000A and 1000B, except that method 1000C includes block 1008C instead of blocks 1008A and 1008B. At block 1008C, the UE determines whether the RRC message or the second configuration includes a MAC retention indication or a MAC reset indication. If the UE determines that the RRC message or the second configuration includes a MAC retention indication, the flow proceeds to block 1010A. Otherwise, if the UE determines that the RRC message or the second configuration includes a MAC reset indication, the flow proceeds to block 1010B.

[0221] Fig. 10D 1000A, except that method 1000D includes blocks 1008D, 1010D, and 1012D instead of blocks 1008A, 1010A, and 1012A. At block 1008D, the UE determines whether the RRC message or the second configuration includes a MAC partial reset indication. If the UE determines that the RRC message or the second configuration includes a MAC partial reset indication, the process proceeds to block 1010D. At block 1010D, the UE performs the actions described above with respect to block 908E. Otherwise, if the UE determines that the RRC message or the second configuration does not include a MAC partial reset indication, the process proceeds to block 1012D. At block 1012D, the UE performs the actions described above with respect to block 908F.

[0222] Fig.10E 1000A, except that method 1000E includes blocks 1007, 1008E, 1010E, and 1012E instead of blocks 1006, 1008A, 1010A, and 1012A. At block 1007, the UE applies the second configuration. At block 1008E, the UE determines whether the UE receives a configuration activation command from the RAN to activate the second configuration. If the UE determines that the UE receives a configuration activation command from the RAN to activate the second configuration, the flow proceeds to block 1010E. At block 1010E, the UE performs the actions described above with respect to block 908G. Otherwise, if the UE does not receive a configuration activation command from the RAN to activate the second configuration, the flow proceeds to block 1012E. At block 1012E, the UE completely resets the MAC entity in response to the RRC message.

[0223] Next, refer to FIG. 11A to FIG. 15B Several example methods that may be implemented in one or more RAN nodes, such as a base station, DU, or CU, or in the RAN to support MAC protocol operations involving configuration activation are discussed. Figures 3 to 8B The examples and implementations described may be applicable to FIG. 11A to FIG. 15B .

[0224] Fig.11A A method 1100A is illustrated that may be implemented by a DU (eg, DU 174) for configuring and activating a serving cell configuration for a UE (eg, UE 102).

[0225] In some implementations, method 1100A begins at block 1102, where the DU communicates with the UE using a first configuration (e.g., events 302, 380, 502, 580, 702, 780). In further implementations, at block 1104, the DU receives a first CU-to-DU message from the CU to request a configuration for the UE (e.g., events 308, 390, 380, 408, 490, 508, 590, 580, 608, 690, 680, 708, 790, 780, 808, 890, 880). At block 1106A, the DU sends a first DU-to-CU message including a second configuration to the CU, wherein the second configuration includes a MAC retention indication for configuring the MAC entity to not reset (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). In some implementations, at block 1108, the DU sends the second configuration to the UE (e.g., events 316, 318, 380, 516, 517, 519, 518, 580, 716, 718, 717, 719, 780). In further implementations, at block 1110, 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 1112, the DU communicates with the UE in accordance with the second configuration and the MAC reservation indication (e.g., events 332, 336, 380, 432, 436, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880). Blocks 1106A, 1108, 1110, and 1112 are Fig.11A Collectively referred to as box 1150A.

[0226] Where DU is the target DU (e.g., Figure 4 A. Figure 4 B. Fig. 6A or Figure 6B T-DU 174B in, or Fig. 8A or Figure 8BIn the case of T-DU 174C in FIG. 174B ), blocks 1102, 1108, and 1110 are omitted. In some implementations, the DU at block 1102 communicates with the UE via a first cell (i.e., a serving cell) identified by a first cell ID. In some implementations, the first CU to DU message includes a second cell ID identifying a second cell (i.e., a target serving cell), and the DU generates a second configuration for the UE to communicate with the DU via the second cell. In some implementations, the second cell ID is an NR CGI. In some implementations, the second configuration includes a third cell ID (e.g., PCI) of the second cell.

[0227] In some implementations, in a case where the DU receives a first CU-to-DU message, the DU sends a first DU-to-CU message to the CU in response to the first CU-to-DU message. In other implementations, the DU proactively sends the first DU-to-CU message to the CU. In some implementations, the first CU-to-DU message is a UE context modification request message. In some implementations, the first DU-to-CU message is a UE context modification response message or a UE context modification requirement message. In other implementations, the first CU-to-DU message and the first DU-to-CU message are a UE context establishment request message and a UE context establishment response message, respectively.

[0228] Fig. 11B is a flow chart of an example method 1100B that is similar to method 1100A, except that method 1100B includes boxes 1106B and 1109 instead of boxes 1106A and 1108. At box 1106B, the DU sends a first DU-to-CU message to the CU including a second configuration and a MAC retention indication for configuring the MAC entity to not reset (e.g., events 310, 390, 380, 510, 590, 580, 710, 790, 780). In other words, the MAC retention indication is not included in the second configuration. In some implementations, at box 1109, the DU sends a second configuration and a MAC retention indication to the UE (e.g., events 316, 318, 380, 516, 518, 517, 519, 580, 716, 718, 717, 719, 780). Boxes 1106B, 1109, 1110, and 1112 are Fig. 11B 1150B. In which DU is the target DU (e.g., Figure 4 A. Figure 4 B. Fig. 6A or Figure 6B T-DU 174B in, or Fig. 8A or Figure 8B In the case of T-DU 174C in FIG. 174B , box 1109 is omitted.

[0229] Fig. 11C is a flow chart of an example method 1100C similar to methods 1100A and / or 1100B, except that method 1100C includes blocks 1106C and 1111 instead of blocks 1106A and 1112. At block 1106C, the DU sends a first DU-to-CU message including a second configuration to the CU, wherein the second configuration excludes a MAC reservation indication to reset the MAC entity (e.g., events 310, 390, 380, 410, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). In some implementations, the DU generates the second configuration excluding the MAC reservation indication. At block 1111, the DU communicates with the UE according to the second configuration (e.g., events 332, 336, 380, 432, 426, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880). Blocks 1106C, 1108, 1110, and 1111 are Fig. 11C Collectively referred to as box 1150C.

[0230] Fig.11D is a flow chart of an example method 1100D that is similar to methods 1100A-C, except that method 1100D includes block 1106D instead of block 1106C. At block 1106D, the DU sends a first DU-to-CU message to the CU that includes the second configuration and excludes the MAC reservation indication to reset the MAC entity (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). In some implementations, the DU generates the first DU-to-CU message that excludes the MAC reservation indication. Blocks 1106D, 1108, 1110, and 1111 are described in detail in detail. Fig.11D The collective term is frame 1150D.

[0231] Fig.11Eis a flow chart of an example method 1100E similar to methods 1100A-D, except that method 1100E includes blocks 1106E and 1113 instead of blocks 1106A and 1112. At block 1106E, the DU sends a first DU-to-CU message including a second configuration to the CU, wherein the second configuration includes a MAC reset indication to reset the MAC entity (e.g., events 310, 390, 380, 410, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). In some implementations, the DU generates the second configuration including the MAC reset indication. At block 1113, the DU communicates with the UE in accordance with the second configuration and the MAC reset indication (e.g., events 332, 336, 380, 432, 426, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880). Blocks 1106E, 1108, 1110, and 1113 are Fig.11E Collectively referred to as box 1150E.

[0232] In some implementations, the MAC reset indication is a MAC partial reset indication indicating a partial MAC reset as described above. In other implementations, the MAC reset indication indicates a full MAC reset as described above.

[0233] Fig.11F is a flow chart of an example method 1100F that is similar to methods 1100A-E, except that method 1100F includes blocks 1106F and 1107 instead of blocks 1106E and 1108. At block 1106F, the DU sends a first DU-to-CU message to the CU that includes the second configuration and includes a MAC reset indication to reset the MAC entity (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). In some implementations, the DU generates the first DU-to-CU message that includes the MAC reset indication. In some implementations, at block 1107, the DU sends a second configuration and MAC reset indication to the UE (e.g., events 316, 318, 380, 516, 518, 517, 519, 580, 716, 718, 717, 719, 780). Blocks 1106F, 1107, 1110, and 1113 are Fig.11F 1150F. In which DU is the target DU (e.g., Figure 4 A. Figure 4 B. Fig. 6A or Figure 6B T-DU 174B in, or Fig. 8A or Figure 8B In the case of T-DU 174C in FIG. 1104 , box 1107 is omitted.

[0234] In some implementations, the MAC reset indication is a MAC partial reset indication that configures a partial MAC reset as described above. In other implementations, the MAC reset indication configures a full MAC reset as described above.

[0235] Fig.11G 1100G, except that method 1100G includes block 1106G instead of block 1106C. At block 1106G, the DU sends a first DU-to-CU message to the CU including a second configuration, wherein the second configuration excludes a MAC reset indication to configure the MAC entity to not reset (e.g., events 310, 390, 380, 510, 590, 580, 710, 790, 780). In some implementations, the DU generates the second configuration excluding the MAC reset indication. Blocks 1106G, 1108, 1110, and 1111 are Fig.11G They are collectively referred to as frame 1150G.

[0236] Fig.11H 1100A-G, except that method 1100H includes block 1106H instead of block 1106C. At block 1106H, the DU sends a first DU-to-CU message to the CU including the second configuration and excluding the MAC reset indication to configure the MAC entity to not reset (e.g., events 310, 390, 380, 510, 590, 580, 710, 790, 780). In some implementations, the DU generates the first DU-to-CU message excluding the MAC reset indication. Blocks 1106H, 1108, 1110, and 1111 are described in detail in detail. Fig.11H They are collectively referred to as frame 1150H.

[0237] Fig.12 A method 1200 is illustrated that may be implemented by a DU (eg, DU 174) for configuring and activating a serving cell configuration for a UE (eg, UE 102).

[0238] Method 1200 begins at block 1202, where the DU communicates with the UE using a first configuration (e.g., events 302, 380, 502, 580, 702, 780). At block 1204, the DU receives a first CU-to-DU message from the CU to request a configuration for the UE (e.g., events 308, 390, 380, 408, 490, 480, 508, 590, 580, 608, 690, 680, 708, 790, 780, 808, 890, 880). At block 1206, the DU determines whether to configure the UE to reset the MAC entity. If the DU determines not to configure the UE to reset the MAC entity, the process proceeds to block 1210. At block 1210, the DU performs the actions described above with respect to blocks 1150A, 1150B, 1150G, or 1150H. Otherwise, if the DU determines to configure the UE to reset the MAC entity, the flow proceeds to block 1212. At block 1212, the DU performs the actions described above with respect to blocks 1150C, 1150D, 1150E, or 1150F.

[0239] Where DU is the target DU (e.g., Figure 4 A. Figure 4 B. Fig. 6A or Figure 6B T-DU 174B in, or Fig. 8A or Figure 8B In the case of T-DU 174C in FIG. 1204 , box 1202 is omitted.

[0240] Fig.13A Illustrated is a method 1300A that may be implemented by a CU (e.g., CU 172) for configuring a serving cell configuration for a UE (e.g., UE 102).

[0241] The method 1300A begins at block 1302, where a CU communicates with a UE (e.g., 302, 380, 402, 502, 580, 602, 680, 702, 780, 802, 880). In some implementations, at block 1304, the CU sends a first CU-to-DU message to a first DU to request a configuration for the UE (e.g., events 308, 390, 380, 408, 490, 480, 508, 590, 580, 608, 690, 680, 708, 790, 780, 808, 890, 880). At block 1306A, the CU receives a first DU-to-CU message (e.g., 310, 390, 380, 410, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880) from the first DU including the first configuration and including a MAC retention indication to configure the MAC entity to not reset. At block 1309, the CU sends the first configuration and the MAC retention indication to the UE (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 616, 618, 617, 619, 680, 716, 718, 717, 719, 780, 816, 818, 817, 819, 880).

[0242] In some implementations, the CU at block 1302 communicates with the UE via the first DU and / or the second DU. In some implementations, the CU at block 1309 sends the first configuration and the MAC reservation indication to the UE via the first DU or the second DU.

[0243] Fig. 13B is a flow chart of an example method 1300B that is similar to method 1300A, except that method 1300B includes blocks 1306B and 1308 instead of blocks 1306A and 1309. At block 1306B, the CU receives a first DU-to-CU message from the DU that includes a first configuration and excludes a MAC retention indication to configure the MAC entity to reset (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). At block 1308, the CU sends a first configuration to the UE (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 616, 618, 617, 619, 680, 716, 718, 717, 719, 780, 816, 818, 817, 819, 880). In some implementations, the CU at block 1308 sends the first configuration to the UE via the first DU or the second DU.

[0244] Fig. 13C is a flow chart of an example method 1300C that is similar to method 1300A, except that method 1300C includes blocks 1306C and 1307 instead of blocks 1306A and 1309. At block 1306C, the CU receives a first DU-to-CU message from the DU that includes a first configuration and includes a MAC reset indication to configure the MAC entity to reset (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). At block 1307, the CU sends a first configuration and a MAC reset indication to the UE (e.g., events 316, 318, 380, 416, 418, 480, 516, 518, 517, 519, 580, 616, 618, 617, 619, 680, 716, 718, 717, 719, 780, 816, 818, 817, 819, 880). In some implementations, the CU at block 1307 sends the first configuration and the MAC reset indication to the UE via the first DU or the second DU.

[0245] In some implementations, the MAC reset indication is a MAC partial reset indication that configures a partial MAC reset as described above. In other implementations, the MAC reset indication configures a full MAC reset as described above.

[0246] Fig.13D 1300B, except that method 1300D includes block 1306D instead of block 1306B. At block 1306D, the CU receives a first DU-to-CU message (e.g., 310, 390, 380, 410, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880) from the DU including a first configuration and excluding a MAC reset indication to configure the MAC entity to not reset.

[0247] Fig.14A Illustrated is a method 1400A that may be implemented by a CU (e.g., CU 172) for configuring a serving cell configuration for a UE (e.g., UE 102).

[0248] The method 1400A begins at block 1402, where a CU communicates with a UE (e.g., 302, 380, 402, 480, 502, 580, 602, 680, 702, 780, 802, 880). In some implementations, at block 1404, the CU sends a first CU-to-DU message to a first DU to request a configuration for the UE (e.g., events 308, 390, 380, 408, 490, 480, 508, 590, 580, 608, 690, 680, 708, 790, 780, 808, 890, 880). At block 1406, the CU receives a first DU-to-CU message including a first configuration from the first DU (e.g., events 310, 390, 380, 410, 490, 480, 510, 590, 580, 610, 690, 680, 710, 790, 780, 810, 890, 880). At block 1408, the CU determines whether the first DU-to-CU message includes a MAC reservation indication. If the CU determines that the first DU-to-CU message includes a MAC reservation indication, the flow proceeds to block 1410. At block 1410, the CU performs the actions described above with respect to block 1309. Otherwise, if the CU determines that the first DU-to-CU message does not include a MAC reservation indication, the flow proceeds to block 1412. At block 1412, the CU performs the actions described above with respect to block 1308.

[0249] Fig. 14B 14 is a flow chart of an example method 1400B that is similar to method 1400A, except that method 1400B includes block 1407 instead of block 1408. At block 1407, the CU determines whether the first DU to CU message includes a MAC reset indication. If the CU determines that the first DU to CU message includes a MAC reset indication, the flow proceeds to block 1410. At block 1410, the CU performs the actions described above with respect to block 1307. Otherwise, if the CU determines that the first DU to CU message does not include a MAC reset indication, the flow proceeds to block 1412. At block 1412, the CU performs the actions described above with respect to block 1308.

[0250] Fig. 14Cis a flow chart of an example method 1400C similar to method 1400A and / or 1400B, except that method 1400C includes box 1409 instead of box 1408. At box 1409, the CU determines whether the first DU to CU message includes a MAC reservation indication or a MAC reset indication. If the CU determines that the first DU to CU message includes a MAC reservation indication, the process proceeds to box 1410. At box 1410, the CU performs the actions described above with respect to box 1309. Otherwise, if the CU determines that the first DU to CU message includes a MAC reset indication, the process proceeds to box 1412. At box 1412, the CU performs the actions described above with respect to box 1307.

[0251] Fig.15A Illustrated is a method 1500A that may be implemented by a DU (eg, DU 174) for configuring and activating a serving cell configuration for a UE (eg, UE 102).

[0252] Method 1500A begins at block 1502, where the DU communicates with the UE on a first serving cell using a MAC entity (e.g., events 302, 380, 502, 580, 702, 780). At block 1504, the DU performs a serving cell change with the UE from the first serving cell to a second serving cell (e.g., events 332, 336, 380, 432, 436, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880). At block 1506, the DU determines whether the serving cell change is triggered by the DU or the CU. If the DU determines that the serving cell change is triggered by the DU, the process proceeds to block 1508. At block 1508, the DU avoids resetting the MAC entity. At block 1510, the DU communicates with the UE on the second serving cell using the MAC entity (e.g., events 332, 336, 380, 432, 436, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880). Otherwise, if the DU determines that the serving cell change is triggered by the CU, the process proceeds to block 1512. At block 1512, the DU resets the MAC entity. At block 1514, the DU communicates with the UE on the second serving cell using the reset MAC entity (e.g., events 332, 336, 380, 432, 436, 480, 532, 536, 580, 632, 636, 680, 732, 736, 780, 832, 836, 880).

[0253] Fig. 15B1500B is a flow chart of an example method 1500B that is similar to method 1500A, except that method 1500B includes block 1507 instead of block 1506. At block 1507, the DU determines whether to configure the UE to reset the MAC entity. If the DU determines that the UE is configured not to reset the MAC entity, the process proceeds to block 1508. Otherwise, if the CU determines that the UE is configured to reset the MAC entity, the process proceeds to block 1512.

[0254] The following description is applicable to the above description.

[0255] In general, the description of one of the figures in the above-mentioned figures may apply to another figure in the above-mentioned figures. If there is no conflict, the above-mentioned examples, implementations and methods may be combined. The above-mentioned events or boxes may be optional or omitted. For example, the events or boxes with dashed lines in the figures may be optional. In some implementations, "message" is used and "information element (IE)" can be replaced with "message", and vice versa. In some implementations, "IE" is used and "field" can be replaced with "IE", and vice versa. In some implementations, "configuration" or "configuration parameter" can be replaced with "configuration", and vice versa. In some implementations, "service cell change command", "layer 1 / layer 2 handover command", "lower layer handover command" or "lower layer service cell change command" can be replaced with "configuration activation command". "Fast service cell configuration process" can be replaced with "fast service cell change process".

[0256] The user device (e.g., UE 102) in which the technology of the present disclosure may be implemented may 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 may be embedded in an electronic system such as a head unit of a vehicle or an advanced driver assistance system (ADAS). Further, the user device may operate 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.

[0257] Certain embodiments are described in the present disclosure as including logic or multiple components or modules. A module may be a software module (e.g., a code or machine-readable instruction stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit that is capable of performing certain operations and may be configured or arranged in a particular manner. A hardware module may include a dedicated circuit system (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) may be driven by cost and time considerations.

[0258] When implemented in software, the techniques may be provided as part of an operating system, a library used by multiple applications, a specific software application, etc. The software may be executed by one or more general-purpose processors or one or more special-purpose processors.

[0259] 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: According to the first configuration, including communicating with a radio access network RAN ​​using a medium access control MAC entity associated with the cell group; 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 reset the MAC entity based on a MAC retention indication from the RAN.

2. The method of claim 1, wherein determining whether to reestablish the RLC entity is 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 according to the second configuration before performing a random access procedure.

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

5. The method according to claim 1 or 2, further comprising: Reestablishing the RLC entity comprises 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: Re-establishment of the RLC entity is avoided by omitting the RLC re-establishment indication in response to determining that the second configuration.

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: Communicate with a user equipment UE according to a first configuration; generating a second configuration, comprising avoiding including a re-establishment indication for a Radio Link Control (RLC) bearer in the second configuration when the second configuration is to be activated at the UE via a command from the RAN; as well as Sending the second configuration to the UE.

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

14. The method according to 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 the method according to any one of the preceding claims.

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