Managing paging for user devices - Patent Application 20070122997

Abstract

A distributed unit (DU) of a distributed base station of a radio access network (RAN) can implement a method for paging a user equipment (UE) when a radio connection between the distributed base station and the UE is not active, the distributed base station including a DU and a central unit (CU). The method includes receiving a configuration for enhanced paging from the CU (1502) and paging the UE using the configuration (1504).

Description

[Technical Field]

[0001] The present disclosure relates generally to wireless communications, and more particularly to paging user equipment (UE) when the UE operates in an inactive or idle state associated with a protocol for controlling radio resources. [Background technology]

[0002] This background discussion is provided for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors, and aspects of the discussion that may not qualify as prior art at the time of filing, to the extent described in this background section, are not admitted expressly or implicitly as prior art to the present disclosure.

[0003] In telecommunications systems, the Packet Data Convergence Protocol (PDCP) sublayer of the radio protocol stack provides services such as user plane data transport, encryption, and integrity protection. For example, the PDCP layer defined for the Evolved Universal Terrestrial Radio Access (EUTRA) air interface (see 3GPP (registered trademark) standard TS36.323) and New Radio (NR) (see 3GPP standard TS38.323) provides protocol data unit (PDU) ordering in the uplink direction (from a user device, also known as user equipment (UE), to a base station) and in the downlink direction (from a base station to a UE). Furthermore, the PDCP sublayer provides services for signaling radio bearers (SRBs) to the Radio Resource Control (RRC) sublayer. The PDCP sublayer also provides services for data radio bearers (DRBs) to the Service Data Adaptation Protocol (SDAP) sublayer or to protocol layers such as the Internet Protocol (IP) layer, the Ethernet protocol layer, and the Internet Control Message Protocol (ICMP) layer. Generally, a UE and a base station may use SRBs to exchange RRC messages and non-access stratum (NAS) messages, and may use DRBs to transport data on the user plane.

[0004] The RRC sublayer designates an RRC_IDLE state, where the UE has no active radio connection with a base station, an RRC_CONNECTED state, where the UE has an active radio connection with a base station, and an RRC_INACTIVE state to allow the UE to transition more quickly back to the RRC_CONNECTED state for Radio Access Network (RAN)-level base station coordination and RAN paging procedures.

[0005] In some scenarios, the UE can operate in a state in which the radio resource control connection with the RAN is not active (e.g., RRC_IDLE or RRC_INACTIVE state) and subsequently transition to the connected state. Generally, in the inactive state, the radio connection between the UE and the radio access network (RAN) is suspended. Later, when the UE is triggered to send data (e.g., an outgoing call, a browser launch) or receives a paging message from the base station, the UE can then transition to the connected state. To make the transition, the base station can configure the UE to operate in the connected state, so that the UE can request that the base station establish a radio connection (e.g., by sending an RRC Setup Request message to the base station) or resume a suspended radio connection (e.g., by sending an RRC Resume Request message to the base station).

[0006] In some cases, a UE in RRC_IDLE or RRC_INACTIVE state has only one or a few relatively small packets to send, or a base station has only one or a few relatively small packets to send to a UE operating in RRC_IDLE or RRC_INACTIVE state. In these cases, a UE in RRC_IDLE or RRC_INACTIVE state can perform early data communication without transitioning to RRC_CONNECTED state, for example, by using techniques such as those specified in sections 7.3a-7.3d of 3GPP standard 36.300 v16.4.0.

[0007] Recently, 3GPP has discussed various paging enhancements for UE power conservation. For example, a base station can send a paging early indication (PEI) prior to a paging occasion. If a UE that supports PEI detection receives the PEI, the UE attempts to receive paging downlink control information (DCI) in a subsequent paging occasion. If the UE does not receive the PEI, the UE can save power by not monitoring subsequent paging occasions. As another example, a core network can configure a paging subgroup for a UE. A UE that supports paging subgroups can determine whether to receive a paging message according to the paging DCI based on whether the paging DCI indicates the UE's paging subgroup.

[0008] However, implementing paging extensions for UE power saving brings some challenges. For example, with regard to paging subgrouping, the core network can configure the UE with a paging subgroup, but it is not clear how a node in a radio access network (RAN) responsible for paging the UE obtains the paging subgroup configuration. If the RAN does not recognize the paging subgroup configuration, the RAN cannot send a paging subgroup indication to the UE, and the UE cannot utilize the paging subgroup paging extension to save power.

[0009] With regard to the PEI paging extension, because the RAN does not maintain UE capabilities for UEs operating in RRC_IDLE, the RAN does not know whether a UE operating in the RRC_IDLE state supports PEI. As a result, in some cases, the RAN refrains from transmitting PEI to the UE. If the RAN transmits paging DCI to a UE that supports PEI detection, when the UE does not detect the PEI (because the RAN does not send the PEI because it does not know that the UE supports PEI), then the UE will not attempt to receive the paging DCI. In other cases, the RAN may still transmit PEI to a UE even though it does not know whether the UE supports PEI. In such cases, the RAN may unnecessarily use radio resources to transmit PEI to a UE that does not support PEI. [Prior art documents] [Non-patent literature]

[0010] [Non-Patent Document 1] 3GPP standard TS36.323 [Non-patent document 2] 3GPP standard TS38.323 [Non-patent document 3] Sections 7.3a to 7.3d of 3GPP Standard 36.300 v16.4.0 [Non-patent document 4] 3GPP standard 38.413 [Non-Patent Document 5] 3GPP standard 36.413 [Non-patent document 6] 3GPP standard 38.331 [Non-Patent Document 7] 3GPP standard 38.423 [Non-patent document 8] 3GPP standard 36.423 [Non-Patent Document 9] 3GPP standard 24.501 [Non-Patent Document 10] 3GPP standard 38.473 or 37.473 [Non-Patent Document 11] 3GPP standard 38.304 [Non-Patent Document 12] 3GPP TS38.304 V16.4.0 Release 16 Section 7.1 Summary of the Invention [Means for solving the problem]

[0011] Network nodes in a radio access network (RAN) can use the techniques of this disclosure to manage paging. A central unit (CU) of a distributed base station can receive a configuration for extended paging from a core network (CN) or from another node in the RAN. The configuration indicates whether the UE supports extended paging features, such as detecting a paging early indication (PEI) or utilizing paging subgrouping. If the CU decides to page the UE, the CU sends the configuration to at least one distributed unit (DU) of the distributed base station to instruct the DU to page the UE using the configuration.

[0012] Based on the configuration, the DU determines how to page the UE. If the DU determines that the UE supports detecting a signal (e.g., a PEI) that notifies the UE to attempt to receive paging downlink control information (DCI), the DU pages the UE by transmitting the signal before transmitting the paging DCI. The DU then transmits a paging message to the UE according to the DCI.

[0013] Furthermore, if the DU determines, based on the configuration, that the UE supports paging subgrouping, the DU can send a paging subgroup indication to the UE when paging the UE. For example, the DU can include a paging subgroup identifier (e.g., a paging subgroup identity (ID) or a subgroup-specific paging radio network temporary identifier (P-RNTI)) in the paging DCI or can use the identifier to scramble a cyclic redundancy check (CRC) value for the paging DCI. If the UE supports both signaling detection and paging subgrouping, the DU can combine the techniques described above or can send a paging subgroup indication in the signal.

[0014] One exemplary embodiment of these techniques is a method implemented in a DU of a RAN for paging a UE when a radio connection between a distributed base station and the UE is inactive, the distributed base station including a DU and a CU. The method may be performed by processing hardware and includes receiving a configuration for enhanced paging from the CU and using the configuration to page the UE.

[0015] Another exemplary embodiment of these techniques is a method implemented in a CU of a distributed base station of a RAN for paging a UE when a radio connection between the distributed base station and the UE is inactive, the distributed base station including a CU and a DU. The method may be performed by processing hardware and includes receiving a configuration for enhanced paging, determining to page the UE, and, in response to the determination, sending the configuration to the DU to instruct the DU to page the UE using the configuration.

[0016] Yet another example embodiment of these techniques is a method, implemented in a base station, for paging a UE, where the base station operates one or more cells. The method may be implemented by processing hardware and includes receiving a first list of frequency bands supported by the UE, generating a second list of frequency bands that includes frequency bands of the first list of frequency bands that are supported by one or more cells, and paging the UE on cells of the one or more cells that support frequency bands of the second list of frequency bands.

[0017] A further exemplary embodiment of these techniques is a method for paging a UE, implemented in a CU of a distributed base station, the distributed base station including a CU and a DU. The method may be implemented by processing hardware and includes determining to page the UE, determining whether the UE is in an idle state associated with a protocol for controlling radio resources or an inactive state associated with the protocol, selecting a paging configuration based on whether the UE is in the idle state or the inactive state, and sending the paging configuration to the DU.

[0018] Another exemplary embodiment of these techniques is a node of a RAN, comprising processing hardware and configured to perform any one of the above methods. [Brief explanation of the drawings]

[0019] [Figure 1A] FIG. 1 is a block diagram of an example wireless communication system in which user devices and base stations of the present disclosure can implement the techniques of the present disclosure for managing enhanced paging. [Figure 1B] 1B is a block diagram of an exemplary base station including a central unit (CU) and a distributed unit (DU) capable of operating in the system of FIG. 1A. [Figure 2A]1B is a block diagram of an example protocol stack according to which the UE of FIG. 1A communicates with a base station. [Figure 2B] 1B is a block diagram of an example protocol stack according to which the UE of FIG. 1A communicates with the CU and DU. [Figure 3A] FIG. 10 is a diagram of an example message sequence in which the CU sends a configuration for enhanced paging to the DU, and the DU uses the configuration to page the UE when the UE operates in idle state. [Figure 3B] 1 is a diagram of an example message sequence in which a core network (CN) sends a configuration for enhanced paging to both a first base station and a second base station. [Figure 3C] FIG. 3B is a diagram of an example message sequence similar to that of FIG. 3A, but where the CU also sends a configuration for extended paging to a second DU. [Figure 4A] FIG. 3B is a diagram of an example message sequence similar to that of FIG. 3A, but where the DU pages the UE when the UE operates in an inactive state. [Figure 4B] FIG. 4B is a diagram of an example message sequence similar to that of FIG. 4A, but in which the DU pages the UE to perform early data communication with the UE. [Figure 4C] FIG. 10 is a diagram of an example message sequence in which the CU sends a configuration for enhanced paging to the DU and the second base station, where the second base station pages the UE when the UE operates in an inactive state. [Figure 4D] FIG. 4B is a diagram of an example message sequence similar to that of FIG. 4A, but where the CU also sends a configuration for extended paging to a second DU. [Figure 5] 1 is a flow diagram of an example method for determining whether to page a UE using enhanced paging or legacy paging that may be implemented by a DU. [Figure 6A]FIG. 10 is a flow diagram of an example method for delivering configuration for enhanced paging that may be implemented by a CU. [Figure 6B] FIG. 10 is a flow diagram of an example method for delivering configuration for enhanced paging that may be implemented by a CU. [Figure 7A] 10 is a flow diagram of an example method, which may be implemented by a CU, for sending a CU-to-DU message to a DU to instruct the DU to page a UE. [Figure 7B] 10 is a flow diagram of an example method for sending a CU-to-DU message to a DU to instruct the DU to page a UE, which may be implemented by a CU control plane node (CU-CP). [Figure 8] FIG. 10 is a flow diagram of an example method for determining a subset of cells on which to page a UE that may be implemented by a DU. [Figure 9] FIG. 10 is a flow diagram of an example method for determining a subset of cells on which to page a UE that may be implemented by a CU. [Figure 10] 10 is a flow diagram of an example method for determining a subset of cells on which to page a UE that may be implemented by a base station. [Figure 11] FIG. 10 is a flow diagram of an example method for determining a subset of cells on which to page a UE that may be implemented by a CN. [Figure 12A] FIG. 10 is a flow diagram of an example method for delivering UE paging capabilities that may be implemented by a CU. [Figure 12B] FIG. 10 is a flow diagram of an example method for delivering UE paging capabilities that may be implemented by a CU. [Figure 13] FIG. 10 is a flow diagram of an example method for determining a configuration to use for paging a UE that may be implemented by a DU. [Figure 14]FIG. 10 is a flow diagram for selecting a paging configuration based on a radio resource control (RRC) state of a UE, which may be implemented by a CU. [Figure 15] FIG. 10 is a flow diagram of an example method for paging a UE that may be implemented by a DU. [Figure 16] FIG. 10 is a flow diagram of an example method for paging a UE that may be implemented by a CU. [Figure 17] FIG. 10 is a flow diagram of an example method for selecting a cell on which to page a UE, which may be implemented by a CU or a DU. [Figure 18] FIG. 10 is a flow diagram of an example method for selecting a paging configuration to use to page a UE, which may be implemented by a CU. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1A , an exemplary wireless communication system 100 includes a UE 102, a base station (BS) 104, a base station 106, and a core network (CN) 110. The base stations 104 and 106 may operate in a radio access network (RAN) 105 connected to the core network (CN) 110. The CN 110 may be implemented, for example, as an evolved packet core (EPC) 111 or a fifth generation (5G) core (5GC) 160. The CN 110 may also be implemented as a sixth generation (6G) core, in another example.

[0021] The base station 104 supports cell 124, and the base station 106 supports cell 126. Cells 124 and 126 may partially overlap, so that the UE 102 can select, reselect, or handover from one of the cells 124 or 126 to the other. If the base station 104 is a gNB, the cell 124 is a New Radio (NR) cell. If the base station 104 is an ng-eNB, the cell 124 is an Evolved Universal Terrestrial Radio Access (E-UTRA) cell. Similarly, if the base station 106 is a gNB, the cell 126 is an NR cell, and if the base station 106 is an ng-eNB, the cell 126 is an E-UTRA cell. The cells 124 and 126 may be in the same Radio Access Network Notification Area (RNA) or different RNAs. In general, the RAN 105 may include any number of base stations, each of which may cover one, two, three, or any other suitable number of cells. The UE 102 may support at least a 5G NR (or simply "NR"), or E-UTRA air interface for communicating with the base stations 104 and 106. Each of the base stations 104, 106 may be connected to the CN 110 via an interface (e.g., an S1 or NG interface). The base stations 104 and 106 may also be interconnected via an interface for interconnecting NG RAN nodes (e.g., an X2 or Xn interface). The base station 104 and the base station 106 may directly exchange messages or information over the X2 or Xn interface. In general, the CN 110 may be connected to any suitable number of base stations supporting NR and / or E-UTRA cells.

[0022] Among other components, the EPC 111 may include a Serving Gateway (SGW) 112, a Mobility Management Entity (MME) 114, and a Packet Data Network Gateway (PGW) 116. The SGW 112 is generally configured to forward user plane packets related to voice 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. The 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. Generally, the UPF 162 is configured to forward user plane packets related to voice calls, video calls, Internet traffic, etc., the AMF 164 is configured to manage authentication, registration, paging, and other related functions, and the SMF 166 is configured to manage PDU sessions.

[0023] The CN 110 may decide to page the UE 102 when the CN receives downlink (DL) data for the UE 102 when the radio connection between the UE and the RAN 105 is not active (e.g., when the UE operates in an idle or inactive state associated with a protocol for controlling radio resources, such as RRC_IDLE or RRC_INACTIVE).

[0024] When the UE operates in an idle state (e.g., RRC_IDLE or CM-IDLE), the CN 110 determines to page the UE 102 to send DL data to the UE 102. In response to the determination, the CN 110 can perform a paging operation together with the RAN 105 to page the UE 102 operating in the idle state. More specifically, the CN 110 can send a CN-to-BS paging message (e.g., an NG Application Protocol (NGAP) Paging message as defined in 3GPP standard 38.413 or an S1 Application Protocol (S1AP) Paging message as defined in 3GPP standard 36.413) to the RAN 105 and trigger the RAN 105 to send a UE paging message to the UE 102. The CN 110 includes the CN ID of the UE 102 in the NGAP paging message. For example, the CN ID may be an S-TMSI or an NG-5G-S-TMSI. In response to the paging message from the CN to the BS, the base station 104 of the RAN 105 generates a UE paging message (e.g., an RRC paging message defined in 3GPP standard 38.331) including the CN ID and sends the UE paging message via the cell 124 to page the UE 102. If the base station 104 has additional cells, the base station 104 may also send the UE paging message via the additional cells to page the UE 102. For example, in response to or after receiving the UE paging message from the base station 104 via the cell 124, the UE 102 in the idle state may perform an RRC connection establishment procedure with the base station 104 to establish an RRC connection (i.e., SRB1 and / or SRB2) with the base station 104 and send a Service Request message to the CN 110 via the base station 104 and the RRC connection (i.e., either SRB1 or SRB2).After receiving the Service Request message, the CN 110 can send a CN-to-BS message (e.g., a PDU Session Resources Setup Request message or an Initial Context Setup Request message) to the base station 104, requesting the base station 104 to allocate resources for the UE 102 to receive DL data. The CN 110 can include a PDU session ID and / or a Quality of Service (QoS) flow ID of the UE 102 in the CN-to-BS message to request the base station 104 to allocate resources for the PDU session and / or QoS flow identified by the PDU session ID and / or QoS flow ID, respectively. In response to or after receiving the CN-to-BS message, the base station 104 activates security protection for the UE 102 and sets up a DRB for the PDU session and / or QoS flow. The base station 104 may send a security mode command message to the UE 102 to activate security protection, and the UE 102 may respond by sending a security mode complete message to the base station 104. The base station 104 may send an RRC reconfiguration message to the UE 102 to configure DRBs for PDU sessions and / or QoS flows, and the UE 102 may respond by sending an RRC reconfiguration complete message to the base station 104.

[0025] When the UE 102 operates in an inactive state (e.g., an RRC_INACTIVE state), the CN 110 sends DL data to the RAN 105, e.g., via an NG-U connection or interface, without sending a CN-to-BS paging message for the UE 102 (e.g., an NGAP Paging message as defined in 3GPP standard 38.413 or an S1AP Paging message as defined in 3GPP standard 36.413) to the base station 104. After receiving or in response to receiving the DL data, the base station 104 generates a UE paging message (e.g., an RRC paging message as defined in 3GPP standard 38.331) including the RAN ID of the UE 102 and sends the UE paging message via the cell 124 to page the UE 102. If the base station 104 has additional cells, the base station 104 may also send the UE paging message via the additional cells to page the UE 102. For example, the RAN ID may be an Inactive Radio Network Temporary Identifier (I-RNTI) or a resume ID. In some scenarios and implementations, the base station 104 may send an inter-BS paging message (e.g., an Xn Paging message as defined in 3GPP standard 38.423 or an X2 Paging message as defined in 3GPP standard 36.423) including the RAN ID to the base station 106, triggering the base station 106 to page the UE 102. In response to or in accordance with the inter-BS paging message, the base station 106 generates a UE paging message including the RAN ID and transmits the UE paging message via the cell 126. If the base station 106 has additional cells, the base station 106 may also send the UE paging message via the additional cells to page the UE 102.In response to or after receiving a UE paging message from the base station 104, the UE 102 can perform an RRC connection resumption procedure with the base station 104 to transition from an inactive state to a connected state (e.g., an RRC_CONNECTED state). If the UE 102 is enabled for early data communication (also called small data transmission) by the RAN 105 and the UE paging message indicates that the UE 102 will perform early data communication (e.g., mobile-terminated early data transmission (EDT)), the UE 102 in the inactive state performs early data communication with the base station 104 without a state transition. During early data communication, the UE 102 can send a UL RRC message (e.g., an RRC Resume Request message) including a message authentication code for integrity (MAC-I) to the base station 104 in response to the UE paging message. In the UL RRC message, the UE 102 may include or have a value indicate that the UE is performing early data communication to prevent the base station 104 from transitioning the UE 102 to a connected state. After receiving the UL RRC message, the base station 104 may send DL data to the UE 102 operating in an inactive state.

[0026] 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 that stores instructions executed by the one or more general-purpose processors. Additionally or alternatively, the processing hardware 130 may include special-purpose processing units. The processing hardware 130 in one exemplary implementation includes a medium access control (MAC) controller 132 configured to perform random access procedures with one or more user devices, receive uplink MAC protocol data units (PDUs) from one or more user devices, and transmit downlink MAC PDUs to one or more user devices. The processing hardware 130 may also include a packet data convergence protocol (PDCP) controller 134, configured to transmit PDCP PDUs according to which the base station 104 can transmit data in the downlink direction in some scenarios and to receive PDCP PDUs according to which the base station 104 can receive data in the uplink direction in other scenarios. The processing hardware may further include an RRC controller 136 to implement procedures and messaging in the RRC sublayer of the protocol communications stack. The processing hardware 130 in one example implementation includes a paging controller 138 configured to manage paging operations with one or more UEs operating in an RRC_INACTIVE or RRC_IDLE state. The base station 106 may include processing hardware 140 that includes components generally similar to those of the processing hardware 130. In particular, components 140, 142, 144, 146, and 148 may be similar to components 130, 132, 134, 136, and 138, respectively.

[0027] The UE 102 is equipped with processing hardware 150, which may include one or more general-purpose processors, such as a CPU, and non-transitory computer-readable memory that stores machine-readable instructions executable on one or more general-purpose processors and / or dedicated processing units. In one exemplary implementation, the processing hardware 150 includes a paging controller 158 configured to manage paging operations when the UE 102 operates in an RRC_IDLE or RRC_INACTIVE state. In one exemplary implementation, the processing hardware 150 includes a medium access control (MAC) controller 152 configured to perform random access procedures with a base station, transmit uplink MAC protocol data units (PDUs) to the base station, and receive downlink MAC PDUs from the base station. The processing hardware 150 may also include a PDCP controller 154, configured to transmit PDCP PDUs according to which the UE 102 can transmit data in the uplink direction in some scenarios and receive PDCP PDUs according to which the UE 102 can receive data in the downlink direction in other scenarios. The processing hardware may further include an RRC controller 156 to implement procedures and messaging in the RRC sublayer of the protocol communications stack.

[0028] 1B illustrates an exemplary distributed or decomposed implementation of any one or more of the base stations 104, 106. In this implementation, the base station 104 or 106 includes a central unit (CU) 172 and one or more distributed units (DUs) 174. The CU 172 includes processing hardware, such as one or more general-purpose processors (e.g., CPUs) and computer-readable memory that stores machine-readable instructions executable on the general-purpose processors and / or special-purpose processing units. For example, the CU 172 may include a PDCP controller, an RRC controller, and / or a paging controller, such as the PDCP controllers 134, 144, the RRC controllers 136, 146, and / or the paging controllers 138, 148. In some implementations, the CU 172 may include a radio link control (RLC) controller configured to manage or control one or more RLC operations or procedures. In other implementations, the CU 172 does not include an RLC controller.

[0029] Each of the DUs 174 may also include processing hardware, which may include one or more general-purpose processors (e.g., CPUs) and computer-readable memory that stores machine-readable instructions executable on the one or more general-purpose processors and / or special-purpose processing units. For example, the processing hardware may include a MAC controller (e.g., MAC controllers 132, 142) configured to manage or control one or more MAC operations or procedures (e.g., random access procedures) and / or an RLC controller configured to manage or control one or more RLC operations or procedures. The processing hardware may also include a physical layer controller configured to manage or control one or more physical layer operations or procedures.

[0030] In some implementations, the CU 172 may include a logical node CU-CP 172A that hosts the control plane portion of the PDCP protocol for the CU 172. The CU 172 may also include a logical node CU-UP 172B that hosts the user plane portion of the PDCP protocol and / or the Service Data Adaptation Protocol (SDAP) protocol for the CU 172. The CU-CP 172A may transmit control information (e.g., RRC messages, F1 application protocol messages), and the CU-UP 172B may transmit data packets (e.g., SDAP PDUs or Internet Protocol packets).

[0031] The CU-CP 172A may be connected to multiple CU-UPs 172B through an E1 interface. The CU-CP 172A selects an appropriate CU-UP 172B for a requested service for the UE 102. In some implementations, a single CU-UP 172B may be connected to multiple CU-CPs 172A through an E1 interface. If the CU-CP and DU belong to a gNB, the CU-CP 172A may be connected to one or more DUs 174 through an F1-C interface and / or an F1-U interface. If the CU-CP and DU belong to an ng-eNB, the CU-CP 172A may be connected to one or more DUs 174 through a W1-C interface and / or a W1-U interface. In some implementations, one DU 174 may be connected to multiple CU-UPs 172B under the control of the same CU-CP 172A. In such an implementation, connectivity between the CU-UP 172B and the DU 174 is established by the CU-CP 172A using a Bearer Context Management function.

[0032] FIG. 2A illustrates, in a simplified manner, an example protocol stack 200 according to which a UE 102 may communicate with an eNB / ng-eNB or gNB (e.g., one or more of the base stations 104, 106).

[0033] In the example stack 200, the EUTRA physical layer (PHY) 202A provides transport channels to the EUTRA MAC sublayer 204A, which in turn provides logical channels to the EUTRA RLC sublayer 206A. The EUTRA RLC sublayer 206A then provides RLC channels to the EUTRA PDCP sublayer 208 and, possibly, to the NR PDCP sublayer 210. Similarly, the NR PHY 202B provides transport channels to the NR MAC sublayer 204B, which in turn provides logical channels to the NR RLC sublayer 206B. The NR RLC sublayer 206B then provides data transfer services to the NR PDCP sublayer 210. The NR PDCP sublayer 210 can then provide data transfer services to a Service Data Adaptation Protocol (SDAP) 212, or to a Radio Resource Control (RRC) sublayer (not shown in FIG. 2A ). In some implementations, the UE 102 supports both EUTRA and NR stacks to support handover between EUTRA and NR base stations and / or support DC over the EUTRA and NR interfaces, as shown in Figure 2A. Additionally, as shown in Figure 2A, the UE 102 can support layering of the NR PDCP 210 over the EUTRA RLC 206A and the SDAP sublayer 212 over the NR PDCP sublayer 210.

[0034] The EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 receive packets sometimes 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 sometimes referred to as protocol data units (PDUs) (e.g., to the RLC layer 206A or 206B). Except where the distinction between SDUs and PDUs is important, this disclosure will refer to both SDUs and PDUs as "packets" for simplicity.

[0035] On the control plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 can provide a signaling radio bearer (SRB) or an RRC sublayer (not shown in FIG. 2A) to exchange, for example, RRC messages or non-access stratum (NAS) messages. On the user plane, the EUTRA PDCP sublayer 208 and the NR PDCP sublayer 210 can provide a data radio bearer (DRB) to support data exchange. The data exchanged on the NR PDCP sublayer 210 can be SDAP PDUs, Internet Protocol (IP) packets, or Ethernet packets.

[0036] 2B , the radio protocol stack can be functionally divided. The CU 172 in either base station 104 or 106 can retain all control and upper layer functionality (e.g., RRC 214, SDAP 212, NR PDCP 210), while lower layer operations (e.g., NR RLC 206B, NR MAC 204B, and NR PHY 202B) are delegated to the DU 174. To support connections to 5GC, the NR PDCP 210 provides SRBs to the RRC 214, which in turn provides DRBs to the SDAP 212 and SRBs to the RRC 214.

[0037] 3A-4D are message sequences for an example scenario in which a CU sends a paging extension configuration to a DU to enable the DU to page a UE using the paging extension configuration. Generally, events that are similar in FIGS. 3A-3C and 4A-4D are labeled with similar reference numbers (e.g., event 394 in FIG. 3A is similar to event 394 in FIGS. 3B-3C and event 494 in FIGS. 4A-4D), with differences as appropriate described below. Except for the differences shown in the figures and described below, any of the alternative implementations described with respect to particular events (e.g., for messaging and processing) may be applied to events labeled with similar reference numbers in other figures.

[0038] 3A , in a scenario 300A, the UE 102 initially operates in a connected state (e.g., RRC_CONNECTED) with the base station 104, which includes the CU 172 and the DU 174, at 302. While the UE 102 operates in the connected state, the UE 102 sends an uplink (UL) NAS message, at 304, to the DU 174, which includes capability and / or assistance information. The DU 174 then sends a DU-to-CU message, at 306, to the CU 172, which includes the UL NAS message. The CU 172 then sends a BS-to-CN message, at 308, to the CN 110 (e.g., the AMF 164 or the MME 114), which includes the UL NAS message. In some implementations, the UE 102 can indicate support for paging enhancement configuration in the capability and / or assistance information. After the CN 110 receives the capability and / or assistance information in the UL NAS message, the CN 110 can determine to generate a paging extension configuration in response to or in accordance with a support indication of the paging extension configuration in the capability and / or assistance information. If the UE 102 does not indicate any support for paging extension, the CN 110 does not create a paging extension configuration for the UE 102. The paging extension configuration, also referred to in this disclosure as a configuration for extended paging, enables the UE 102 to manage paging reception using the corresponding paging extension function. In response to the determination, the CN 110 generates a DL NAS message including the paging extension configuration and sends a first CN-to-BS message including the DL NAS message to the CU 172 at 310. Then, the CU 172 sends a first CU-to-DU message including the DL NAS message to the DU 174 at 312. The DU 174 then transmits the DL NAS message to the UE 102 at 314.

[0039] In some implementations, such as those shown, the CN 110 can generate, determine, or select the paging enhancement configuration according to or in response to the capability and / or assistance information. In other implementations, not shown, the CN 110 can obtain the paging enhancement configuration from the CU 172. For example, after receiving the capability and / or assistance information, the CN 110 can send an additional CN-to-BS message to the CU 172 requesting the CU 172 to provide the paging enhancement configuration, and in response, the CU 172 sends an additional BS-to-CN message including the paging enhancement configuration to the CN 110.

[0040] After a period of data inactivity for the UE 102, the CU 172 may determine that neither the CU 172 nor the UE 102 transmitted any data in the downlink or uplink direction, respectively, during the period. In some implementations, the DU 174 may send a DU-to-CU message (not shown) to the CU 172 indicating data inactivity of the UE 102 to aid in the determination. In response to the determination, the CU 172 sends a second CU-to-DU message including an RRC release message to the DU 174 at 316, which then transmits the RRC release message to the UE 102 at 318. The UE 102 transitions to an idle state (e.g., an RRC_IDLE state) and operates in the idle state in response to receiving the RRC release message at 320.

[0041] In some implementations, the UL NAS message and the DL NAS message may be a 5G Mobility Management (MM) message or a 5G Session Management (SM) message (e.g., as described in 3GPP standard 24.501). For example, the UL NAS message may be a Registration Request message or a Registration Complete message. In another example, the DL NAS message may be a Registration Accept message or a Configuration Update Command message. In some implementations, the messages from the DU to the CU, the messages from the first CU to the DU, and the messages from the second CU to the DU are F1 Application Protocol (F1AP) or W1 Application Protocol (W1AP) messages (e.g., as described in 3GPP standard 38.473 or 37.473). For example, the message from the DU to the CU, the message from the first CU to the DU, and the message from the second CU to the DU may be a UL RRC Message Transfer message, a DL RRC Message Transfer message, and a UE Context Release Command message, respectively. In some implementations, the message from the BS to the CN and the message from the first CN to the BS are NG Application Protocol (NGAP) messages. For example, the message from the BS to the CN is an Initial UE Message message or an Uplink NAS Transport message. In another example, the message from the first CN to the BS is an Initial Context Setup Request message or a Downlink NAS Transport message.

[0042] Events 304, 306, 308, 310, 312, 314, 316, 318, and 320 are collectively referred to as NAS paging extension enable procedure 392 in FIG. 3A.

[0043] Later, the CN 110 determines to page the UE 102 or send DL data to the UE 102, for example, for a mobile terminated call. In response to the determination, the CN 110 sends a second CN-to-BS message including a paging extension configuration to the CU 172 at 322. In the second CN-to-BS message, the CN 110 can include, in some implementations, a NAS ID of the UE 102, one or more capabilities of the UE 102 for paging, and / or paging assistance information for the UE 102. In some implementations, the NAS ID can be an S-TMSI or a 5G-S-TMSI. In one implementation, the CN 110 includes the NAS ID in the DL NAS message 310. In another implementation, the CN 110 sends a second DL NAS message including the NAS ID to the UE 102 via the CU 172 and DU 174, similar to events 310, 312, and 314, before sending the message from the second CN to the BS.

[0044] In some implementations, the one or more capabilities for paging are included in a UE paging capability IE (e.g., a UE Radio Paging Information IE), and the CN 110 includes the UE paging capability IE in a message from the second CN to the BS. In some implementations, the one or more capabilities are included in a UE overall capability IE (e.g., a UE-NR-Capability IE) of the UE 102. The UE overall capability IE includes other capabilities in addition to the one or more capabilities in the UE paging capability IE. In some implementations, the CN 110 can receive the UE paging capability IE and / or the UE overall capability IE from the RAN 105 (e.g., the CU 172, or another CU or base station). In other implementations, the CN 110 can pre-store the UE paging capability IE. In such implementations, the CN 110 can either pre-store the UE paging capability IE or dynamically generate the UE paging capability IE from the UE overall capability IE. In some implementations, the CN 110 may associate a capability ID with the UE overall capability IE and / or the UE paging capability.

[0045] In some implementations, the one or more capabilities include a frequency band list for paging (e.g., a supportedBandListNRForPaging field) that includes frequency bands supported by the UE 102. In some implementations, the UE all capabilities IE includes a full frequency band list (e.g., a supportedBandListNR field) that includes all frequency bands supported by the UE 102. The RAN 105 or the CN 110 can generate a frequency band list for paging from the full frequency band list. In some implementations, the RAN 105 or the CN 110 can include a subset of the full frequency bands in the frequency band list for paging. For example, the RAN 105 or the CN 110 can select frequency bands supported by the RAN 105 from the full frequency bands. In other implementations, the RAN 105 or the CN 110 can include all frequency bands in the frequency band list for paging.

[0046] In other implementations, the one or more capabilities include one or more downlink scheduling slot offset capabilities (e.g., dl-SchedulingOffset-PDSCH-TypeA-FDD-FR1-r15, dl-SchedulingOffset-PDSCH-TypeA-TDD-FR1-r15, dl-SchedulingOffset-PDSCH-TypeB-FDD-FR1-r15, and / or dl-SchedulingOffset-PDSCH-TypeB-TDD-FR1-r15) to indicate that the UE 102 supports cross-slot scheduling. In yet other implementations, the one or more capabilities include a single capability field / IE to indicate support for PEI signaling while the UE 102 operates in an idle state (e.g., RRC_IDLE) and / or an inactive state (e.g., RRC_INACTIVE). Alternatively, the one or more capabilities include a first capability field / IE and a second capability field / IE to indicate support for PEI signaling while the UE 102 operates in an idle state and support for PEI signaling while the UE 102 operates in an inactive state, respectively.

[0047] In some implementations, the paging assistance information includes a paging discontinuous reception (DRX) configuration, a paging priority, a paging origin, and / or a tracking area identification (TAI) list for paging. The paging DRX information may include a paging DRX cycle value. In some implementations, the paging DRX cycle value may be 32, 64, 128, or 256 radio frames. In other implementations, the paging DRX cycle value may be 512 or 1024 radio frames. The paging DRX configuration may be paging discontinuous reception (DRX) information (e.g., a Paging DRX IE) or paging enhanced DRX (eDRX) information (e.g., a Paging eDRX Information IE). The paging eDRX information may include a paging eDRX cycle value (e.g., 0.5, 1, 2, 4, 6, 8, 10, 12, 14, 16, 32, 64, 128, 256 hyperframes) and / or a paging time window value.

[0048] In some implementations, the message from the second CN to the BS may be an NGAP Paging message as described in 3GPP standard 38.413. In some implementations, the CN 110 includes paging DRX information or paging eDRX information in the DL NAS message 310 or the second DL NAS message.

[0049] In response to or after receiving the second CN-to-BS message, the CU 172 extracts the paging extension configuration from the second CN-to-BS message and sends a third CU-to-DU message including the paging extension configuration to the DU 174 at 324. In some implementations, the CU 172 can extract the NAS ID from the second CN-to-BS message and include the NAS ID in the third CU-to-DU message. In some implementations, the CU 172 can extract the paging start point from the second CN-to-BS message and include the paging start point in the third CU-to-DU message.

[0050] In some implementations, the CU 172 can directly include the retrieved paging extension configuration in a message from the third CU to the DU without decoding the retrieved paging extension configuration into a type of data and then encoding the data into the paging extension configuration as an IE in the message from the third CU to the DU. An advantage of such an implementation is that the CU 172 does not need to process or include the paging extension configuration, i.e., the CU 172 is transparent to the paging extension configuration. In some implementations, the paging extension configuration can be an RRC information element (IE). In some implementations, the message from the third CU to the DU can be an F1AP Paging message as described in 3GPP standard 38.473. In other implementations, the message from the third CU to the DU can be a W1AP Paging message as described in 37.473.

[0051] In another implementation, the CU 172 decodes the retrieved paging extension configuration (i.e., an IE in the message from the second CN to the BS) into a type of data and then encodes the data into a paging extension configuration as an IE in the message from the third CU to the DU. An advantage of such an implementation is that the CU 172 can decide whether to augment or adjust configuration parameters of the retrieved paging extension configuration based on the conditions or implementation of the DU 174 and / or the CU 172. For example, the DU 174 may not support a particular configuration parameter in the retrieved paging extension configuration, so the CU 172 may decide to exclude the particular configuration parameter from the paging extension configuration of the message from the third CU to the DU. In another example, the DU 174 may not support a particular value of a configuration parameter in the retrieved paging extension configuration, so the CU 172 may change the particular value to another value supported by the DU 174. In some implementations, the retrieved paging extension configuration is an NGAP IE, and the paging extension configuration of the message from the third CU to the DU is an F1AP IE or a W1AP IE.

[0052] In some implementations, if the second CN-to-BS message includes one or more capabilities for paging, the CU 172 can include one or more capabilities for paging in a paging message from the third CU to the DU. For example, the second CN-to-BS message may include a UE paging capabilities IE, and the CU 172 can include the UE paging capabilities IE in the third CU-to-DU message. In other implementations, the second CN-to-BS message may include paging assistance information for the UE 102 in an IE of the second CN-to-BS message. For example, if the second CN-to-BS message is an NGAP message, the IE may be an NGAP IE. In such implementations, the CU 172 extracts the paging assistance information from an IE of the second CN-to-BS message and includes (a portion of) the paging assistance information in an IE of the third CU-to-DU message. In some implementations, the CU 172 can modify (a portion of) the paging assistance information and include (a portion of) the modified paging assistance information in a message from the third CU to the DU. In some scenarios and implementations, the paging assistance information in the message from the second CN to the BS includes paging DRX information that includes a paging DRX cycle value, i.e., 512 or 1024 radio frames. When one of the CU 172 and the DU 174 does not support 512 or 1024 radio frames, the CU 172 can set the paging DRX cycle value in the message from the third CU to the DU to 32, 64, 128, or 256 radio frames instead of 512 or 1024 radio frames. In some implementations, the CU 172 or the DU 174 does not support 512 or 1024 radio frames because the Paging Assistance Information IE of the message from the third CU to the DU does not support a Paging DRX Cycle value with either 512 or 1024 radio frames. In other implementations, extended Paging DRX Cycle values ​​(i.e., 512 and 1024 radio frames) may be included in a new format of the Paging Assistance Information IE of the message from the third CU to the DU.If the CU 172 and the DU 174 support the new format (i.e., support a paging DRX cycle with 512 or 1024 radio frames), the CU 172 can set the paging DRX cycle to 512 or 1024 radio frames in a message from the third CU to the DU. If the CU 172 supports the new format but the DU 174 does not support the new format, the CU 172 can set the paging DRX cycle value in a message from the third CU to the DU to 32, 64, 128, or 256 radio frames instead of 512 or 1024 radio frames.

[0053] In response to or after receiving the third CU-to-DU message, the DU 174 generates a paging message (e.g., an RRC paging message defined in 3GPP standard 38.331) for paging the UE 102 and configures 326 to page the UE 102 according to or taking into account the paging extension configuration, one or more capabilities for paging, and paging assistance information in the third CU-to-DU message. Configuring to page the UE 102 includes determining how to page the UE 102 in light of the paging extension configuration (e.g., determining whether to send a PEI before sending a paging DCI that schedules the paging message, determining whether to send a paging subgroup indication to the UE 102 when paging the UE 102, generating the paging DCI, etc.).

[0054] To configure paging the UE 102, the DU 174 generates a paging DCI that schedules and allocates radio resources for transmission of the paging message on the DU 174's cell (e.g., cell 124). If the CU 172 includes a paging cell list in the third CU-to-DU message 324, the DU 174 schedules and allocates radio resources for transmission of the paging message on the cells in the paging cell list. The DU 174 transmits the paging DCI at 327 and transmits the paging message on the cells at 328 to page the UE 102 according to the determination at event 326. In some implementations, the DU 174 can configure transmission of the paging DCI on the paging occasion at event 326, for example, according to 3GPP standard 38.304. In some implementations, the DU 174 determines a paging occasion during the on duration of a paging DRX cycle according to paging DRX information or paging eDRX information. The UE 102 attempts to receive paging DCI at the paging occasion according to, for example, 3GPP standard 38.304. In some implementations, the UE 102 determines a paging occasion during the on duration of a paging (e)DRX cycle according to paging DRX information or paging eDRX information. In some implementations, the DU 174 can determine to transmit a paging message multiple times on the same or different radio resources at event 326. In such implementations, the DU 174 transmits a paging DCI for each transmission of the paging message. The paging DCI for each transmission may be the same or different.

[0055] In some implementations, the UE 102 may indicate support for paging subgrouping in the UE capability and / or assistance information. As an example, the UE 102 may indicate support for paging subgrouping using a subgroup-specific paging radio network temporary identifier (P-RNTI) in the UE capability and / or assistance information. If the UE 102 supports paging subgrouping, the paging extension configuration at events 314, 324 includes an indication of a paging subgroup assigned to the UE 102 by the CN 110. For example, the paging extension configuration may include a paging subgroup configuration that configures the UE 102 paging subgroup (e.g., the paging extension configuration may include a paging subgroup identification (ID) or may include or indicate a subgroup-specific P-RNTI).

[0056] If the paging extension configuration indicates that the UE 102 supports paging subgrouping, the DU 174 may decide to send an indication of a paging subgroup to the UE 102 when paging the UE 102 at event 326. For example, the DU 174 may indicate the paging subgroup in a paging DCI. In some implementations, the DU 174 includes a paging subgroup ID in the paging DCI. In other implementations, the DU 174 sets a field to a value corresponding to the paging subgroup. If the paging DCI indicates a paging subgroup, the UE 102 attempts to receive a paging message according to the paging DCI. If the paging DCI does not indicate a paging subgroup, the UE 102 discards or ignores the paging DCI, or refrains from attempting to receive a paging message according to the paging DCI.

[0057] In other implementations, the DU 174 may indicate the paging subgroup by scrambling the CRC of the paging DCI with the subgroup-specific P-RNTI and transmit the paging DCI and scrambled CRC on the PDCCH, for example, at event 327. If the UE 102 receives the paging DCI and scrambled CRC on the PDCCH and identifies the paging DCI as directed to the UE 102 based on the scrambled CRC and the subgroup-specific P-RNTI, the UE 102 attempts to receive the paging message. If the UE 102 receives the paging DCI and scrambled CRC on the PDCCH and identifies the paging DCI as not directed to the UE 102 based on the scrambled CRC and the subgroup-specific P-RNTI, the UE 102 discards or ignores the paging DCI, or refrains from receiving the paging message according to the paging DCI. The UE 102 may obtain or derive the subgroup-specific P-RNTI from the paging extension configuration.

[0058] In some implementations, the UE 102 may indicate in the UE capability and / or assistance information whether the UE 102 supports detecting a paging early indication (PEI) signal. If the UE 102 supports detecting a PEI signal, the paging extension configuration includes a PEI configuration that configures the UE 102 to receive or detect a PEI signal before receiving a paging DCI and / or a paging message. If the UE 102 receives or detects a PEI signal, the UE 102 attempts to receive the paging DCI. In some implementations, the PEI signal may be a wake-up signal for paging (WUS). Thus, if the UE 102 supports detecting a PEI, the DU 174 determines, at event 326, to transmit a PEI signal before transmitting the paging DCI at 327.

[0059] In some implementations, the paging extension configuration indicates that the UE 102 supports both paging subgrouping and detecting PEI signals. For example, the UE 102 may indicate in the UE capabilities and / or assistance information that the UE 102 supports paging subgrouping and detecting PEI signals. Additionally or alternatively, the UE 102 may specifically indicate support for identifying paging subgrouping using PEI signals in the UE capabilities and / or assistance information. If the UE 102 supports both paging subgrouping and detecting PEI signals, the DU 174 may determine, at event 326, to indicate a paging subgroup in the PEI signal. For example, the DU 174 may generate a PEI signal including a specific sequence to indicate the paging subgroup. If the UE 102 receives or detects the PEI signal, the UE 102 attempts to receive paging DCI. If UE 102 receives or detects a PEI signal that includes a different sequence or does not receive or detect a PEI signal that includes a specific sequence for the paging subgroup, UE 102 does not attempt to receive paging DCI on UE 102's paging occasion.

[0060] If the CU 172 operates other DUs in addition to the DU 174, the CU 172 can send a CU-to-DU message similar to the third CU-to-DU message to each of the other DUs. See FIG. 3C . Similarly, the CU 172 can include a specific paging cell list in each CU-to-DU paging message. In response to the CU-to-DU message, the specific DU generates a paging DCI and a paging message (e.g., an RRC paging message defined in 3GPP standard 38.331) to page the UE 102 and configures transmission of the paging DCI and paging message, similar to event 326. In some implementations, the CU 172 can extract a TAI list or RNA for paging from the paging assistance information or an IE in the second CN-to-BS message and determine to request the DU 174 and / or other DUs to page the UE 102 according to the TAI list or RNA. That is, the DU 174 and / or other DUs belong to one or more paging areas identified by the TAI list or RNA. Furthermore, the DU 174 may control more than one cell. In such a case, the DU 174 can page the UE on multiple cells.

[0061] Events 324, 326, 327, and 328 are collectively referred to as extended paging procedure 394 in FIG. 3A.

[0062] When the UE 102 receives the paging message via the cell 124 at 328, the UE 102 identifies (e.g., confirms or verifies) that the NAS ID addresses the UE 102. In response to the identification, the UE 102 may initiate a paging response procedure (e.g., a service request procedure) to respond to the paging message. In response to the initiation, the UE 102 performs an RRC connection establishment procedure with the CU 172 via the DU 174 and the cell 124 at 330. To perform the RRC connection establishment procedure, the UE 102 may send an RRC request message (e.g., an RRCConnectionRequest or RRCSetupRequest message) to the CU 172 via the DU 174. In response, the CU 172 may send an RRC response message (e.g., an RRCConnectionSetup or RRCSetup message) to the UE 102 via the DU 174. The UE 102 may send an RRC completion message (e.g., an RRCConnectionSetupComplete or RRCSetupComplete message) to the CU 172 via the DU 174. The UE 102 transitions to a connected state (e.g., an RRC_CONNECTED state) in response to the RRC response message, at 372. The UE 102 may send a Service Request message to the CN 110 via the DU 174 and the CU 172 in response to the Paging message. After the UE 102 transitions to the connected state, the CU 172 may perform a security mode procedure with the UE 102 via the DU 174 to activate security (e.g., integrity protection and / or ciphering) for data communication between the UE 102 and the CU 172, at 332. After activating security, the CU 172 may perform at least one RRC reconfiguration procedure with the UE 102 via the DU 174 to configure a signaling radio bearer (SRB) and / or a data radio bearer (DRB) at 334.The UE 102 then communicates (e.g., transmits and / or receives) data with the CN 110 via the CU 172 and the DU 174, at 336. The data may include user plane data packets (e.g., IP packets) and / or control plane messages (e.g., NAS messages). In some implementations, the UE 102 can communicate user plane data packets over DRBs with the CU 172 via the DU 174, at 336, where the CU 172 communicates user plane data packets with the CN 110. In other implementations, the UE 102 can communicate control plane messages over SRBs with the CU 172 via the DU 174, at 336, where the CU 172 communicates control plane messages with the CN 110.

[0063] 3B , scenario 300B is generally similar to scenario 300A, except that the CN 110 also sends a paging extension configuration to the base station 106 to further extend the reach of the extended paging procedure. After the CN 110 performs a NAS paging extension activation procedure with the UE 102 via the CU 172A and DU 174A of the base station 106 at 392, the CN 110 decides to page the UE 102, which is operating in an idle state. The CN 110 sends a CN-to-BS message including the paging extension configuration to the CU 172A at 338, similar to event 322. The CU 172A then sends the paging extension configuration to the DU 174A in a CU-to-DU message at 340, similar to event 324. The DU 174A uses the paging extension configuration to decide how to page the UE 102 at 342, similar to event 326.

[0064] In contrast to the successful extended paging procedure 394 shown in FIG. 3A , when the DU 174A transmits a paging DCI at 343 and / or transmits a paging message at 344, the paging DCI and / or the paging message do not reach the UE 102. For example, after transitioning to an idle state, the UE 102 may have moved from the cell 126 served by the base station 106 to the cell 124 served by the base station 104. As a result, the base station 106 does not successfully page the UE 102. However, the CN 110 may transmit a CN-to-BS message including a paging extended configuration for the UE 102 to other base stations. For example, the CN 110 may transmit such a CN-to-BS message to base stations within the paging area of ​​the UE 102, where the paging area may be based on the RNA or TAI list for the UE 102. Accordingly, the CN 110 also sends a CN-to-BS message, at 322, to the CU 172B of the base station 104 to initiate an extended paging procedure 394 at the additional distributed base station. The CU 172B performs the extended paging procedure with the UE 102, at 394, via the DU 174B of the base station 104, to successfully page the UE 102. In some implementations, rather than receiving the extended paging configuration from the CN 110, at 322, the CU 172B may receive the extended paging configuration from the CU 172A (e.g., via a BS-to-BS message). The CU 172A may determine to send the extended paging configuration to the CU 172B based on the paging area of ​​the UE 102.

[0065] Referring to FIG. 3C, scenario 300C is initially similar to scenario 300B. However, base station 104 includes CU 172 and two DUs, DU 174A and DU 174B. Initially, CN 110 initiates paging of UE 102 by sending a CN-to-BS message including a paging extension configuration to CU 172 at 338. Similar to FIG. 3B, in which CU 172A of base station 106 attempts to page UE 102 via DU 174A of base station 106, CU 172 attempts to page UE 102 via DU 174B. The paging message sent by DU 174B at 344 does not reach UE 102. However, via an extended paging procedure 394, CU 172 also sends a paging extension configuration to DU 174A in a CU-to-DU message, and DU 174A successfully pages UE 102. The CU 172 may send the paging extension configuration to multiple DUs based on the paging area of ​​the UE 102.

[0066] 3A-3C illustrate a scenario in which a base station pages a UE when the UE operates in an idle state. In contrast, FIG. 4A-4D illustrate a scenario in which a base station pages a UE when the UE operates in an inactive state.

[0067] 4A , in a scenario 400A, the UE 102 initially operates in a connected state (e.g., RRC_CONNECTED) at 402 with the base station 104, which includes the CU 172 and the DU 174. While the UE 102 operates in the connected state, the UE 102 communicates data with the CN 110 via the CU 172 and the DU 174 at 403. While communicating with the CN 110 at 403, the UE 102 may send capability and / or assistance information to the CN 110 (e.g., via the CU 172 and the DU 174, similar to events 304, 306, and 308 during the NAS paging extension activation procedure 392). Based on the capability and / or assistance information, the CN 110 may generate a paging extension configuration. The CN 110 may send the paging extension configuration to the UE 102 (e.g., via the CU 172 and the DU 174, similar to events 310, 312, and 314 during the NAS paging extension enablement procedure 392). Further, after generating the paging extension configuration, the CN 110 may send 415 a CN-to-BS message including the paging extension configuration to the CU 172. In some implementations, the CN-to-BS message may be an Initial Context Setup Request message, a Handover Request message, a Path Switch Request Acknowledge message, or a UE Context Modification Request message.

[0068] After a period of data inactivity for the UE 102, the CU 172 may determine that neither the CU 172 nor the UE 102 transmitted any data in the downlink or uplink direction, respectively, during the period of time. In response to the determination, the CU 172 sends 416 a CU-to-DU message including an RRC release message to the DU 174, which then sends 418 an RRC release message to the UE 102. In response to the RRC release message, the UE 102 transitions 421 to an inactive state (e.g., RRC_INACTIVE) and operates in the inactive state.

[0069] Later, the CN 110 detects DL data for the UE 102. In response, the CN 110 transmits the DL data to the CU 172 at 423. In response to receiving the DL data at 423, the CU 172 transmits a paging extension configuration to the DU 174 in a CU-to-DU message at 424 to cause the DU 174 to page the UE 102. The DU 174 configures paging of the UE 102 at 426 based on the paging extension configuration, similar to event 326. To configure paging of the UE 102 at 426, the DU 174 determines how to page the UE 102 based on the paging extension configuration. The DU 174 then pages the UE 102 according to the determination at event 426. More specifically, the DU 174 transmits a paging DCI to the UE 102 at 427 to schedule a paging message, and transmits the paging message to the UE 102 at 428. For example, based on the determination at event 426, the DU 174 may determine whether to transmit a PEI and / or whether to indicate a paging subgrouping to the UE 102 when paging the UE 102 prior to transmitting the paging DCI at 427. Events 424, 426, 427, and 428 are collectively referred to in this disclosure as an enhanced paging procedure 494.

[0070] In response to the paging message, the UE 102 transitions to a connected state (e.g., RRC_CONNECTED) and initiates an RRC resumption procedure to receive DL data. The UE 102 sends an RRC resumption request message (e.g., an RRCResumeRequest message) to the DU 174 at 446, which then sends a DU-to-CU message containing the RRC resumption request message to the CU 172 at 448. In response, the CU 172 sends a CU-to-DU message containing an RRC resumption message (e.g., an RRCResume message) to the DU 174 at 450, which then sends an RRC resumption message to the UE 102 at 452. In response to the RRC resumption message, the UE 102 transitions to a connected state at 430 and operates in the connected state. After transitioning to the connected state, the UE 102 sends an RRC resume complete message (e.g., an RRC ResumeComplete message) to the DU 174 at 454, which then sends a DU-to-CU message including the RRC resume complete message to the CU 172 at 456. The UE 102 can then communicate data with the CN 110 via the CU 172 and DU 174 at 458. In particular, the CU 172 can send DL data to the UE 102. Events 446, 448, 450, 452, 430, 454, 456, and 458 are collectively referred to in this disclosure as a data communication procedure 496.

[0071] 4B, scenario 400B is generally similar to scenario 400A, except that the base station 104 performs early data communication with the UE 102 to receive DL data without the UE 102 transitioning to a connected state. The UE 102 transitions to an inactive state at 421, similar to FIG. 4A. After receiving the DL data for the UE 102 at 423, the CU 172 pages the UE 102 via the DU 174 using an enhanced paging procedure 494. The CU 172 may include an indication that the UE 102 will perform early data communication in a CU-to-DU message that the CU 172 sends to the DU 174 during the enhanced paging procedure 494. Therefore, the DU174 may include in a paging message that the DU174 sends to the UE102 an indication that the UE102 will perform early data communication (for example, the DU174 may include an indication that the DU174 receives from the CU172 or that the DU174 generates).

[0072] After receiving the paging message, the UE 102 sends an RRC Resume Request message to the DU 174 at 446, which then sends the RRC Resume Request message to the CU 172 in a DU-to-CU message at 448. The RRC Resume Request message may include an indication that the UE 102 is initiating early data communication. In contrast to the data communication procedure 496, the CU 172 can then transmit DL data to the UE 102 without transitioning the UE 102 to a connected state. The CU 172 transmits DL data to the DU 174 at 451, which then transmits DL data to the UE 102 at 453. In some implementations, after initiating early data communication, the UE 102 can also transmit UL data to the DU 174 at 455, which then transmits UL data to the CU 172 at 457. The CU 172 can then forward the UL data to the CN 110 at 459. After transmitting the DL data at 451 (and, in some implementations, receiving the UL data), the CU 172 transmits a CU-to-DU message at 460 to the DU 174, which then transmits an RRC release message 462 to the UE 102 to terminate the early data communication at 462. Events 446, 448, 451, 453, 455, 457, 459, 460, and 462 are collectively referred to in this disclosure as a data communication procedure 497.

[0073] 4C , scenario 400C is generally similar to scenarios 400A or 400B, except that the base station 104 receives a paging enhancement configuration from another base station 106. The UE 102 initially communicates with the CN 110 via the base station 106 at 403 and later transitions to an inactive state at 421. The CN 110 then detects DL data for the UE 102 and transmits the DL data at 439 to the CU 172A of the base station 106, which last served the UE 102 before the UE 102 transitioned to the inactive state. The CU 172A then attempts to page the UE 102 via the DU 174A. 3B, when the DU 174A transmits a paging DCI at 443 and / or transmits a paging message at 444, the paging DCI and / or the paging message do not reach the UE 102. Therefore, the DU 174A does not successfully page the UE 102.

[0074] CU 172A also sends 470 a paging extension configuration to CU 172B of base station 104 in an inter-BS message. CU 172A may decide to send 470 a paging extension configuration to another base station because base station 104 is within the paging area of ​​UE 102 (e.g., based on the UE 102's TAI list or RNA). CU 172B can then page UE 102 via DU 174B using an extended paging procedure 494. After paging UE 102, UE 102 receives DL data from DU 174B using either data communication procedure 496 or 497 (i.e., by transitioning to a connected state or by performing early data communication). CU 172B can receive DL data from CU 172A.

[0075] Referring to FIG. 4D, scenario 400D is initially similar to scenario 400C. However, the base station 104 includes a CU 172 and two DUs, DU 174A and DU 174B, similar to the base station 104 in FIG. 3C. Initially, the CN 110 initiates paging the UE 102 by sending DL data to the CU 172 at 421. The CU 172 attempts to page the UE 102 via the DU 174B, but the paging message that the DU 174B sends at 444 does not reach the UE 102. However, the CU 172 also sends a paging extension configuration to the DU 174A in a CU-to-DU message, and the DU 174A successfully pages the UE 102 via an extended paging procedure 494. The CU 172 may send the paging configuration to multiple DUs based on the paging area of ​​the UE 102.

[0076] 5-18 are flow diagrams illustrating example methods that a node of a RAN (e.g., RAN 105) may perform to manage paging of a UE (e.g., UE 102).

[0077] 5 is a flow diagram of a method 500 that may be implemented by a DU (e.g., DU 174) for determining whether to page a UE using enhanced paging or legacy paging. In block 502, the DU receives a CU-to-DU message from a CU (e.g., CU 172) instructing the DU to page the UE (e.g., UE 102) (e.g., events 324, 340, 424, 440, or similar events in procedures 394, 494). In response to the CU-to-DU message, in block 504, the DU generates a paging message that includes the UE's identification information (e.g., NAS ID). The DU also determines whether the DU has a paging enhancement configuration for the UE in block 506. The DU may receive the paging enhancement configuration in the CU-to-DU message that the DU receives in block 502, or may have previously received a paging enhancement configuration for the UE.

[0078] If the DU has a paging extension configuration, the flow proceeds to block 508. In block 508, the DU transmits a paging message to the UE via one or more cells using the paging extension configuration to page the UE (e.g., events 326, 327, 328). For example, based on the paging extension configuration indicating UE support for detecting a PEI, the DU may determine to transmit a PEI to the UE prior to transmitting a paging DCI that schedules the paging message. As another example, as described above with reference to FIG. 3A, the DU may include in or with the DCI an indication of the UE's paging subgroup based on the paging subgroup identified in the paging extension configuration.

[0079] If the DU does not have a paging extension configuration, the flow proceeds to block 510, where the DU sends a paging message to the UE via one or more cells using a predetermined paging configuration to page the UE. Paging the UE using a predetermined paging configuration corresponds to the legacy method of paging a UE, as described in 3GPP TS38.304 V16.4.0 Release 16 Section 7.1.

[0080] 6A-6B are flow diagrams of methods 600A and 600B, respectively, for delivering a configuration for enhanced paging that may be implemented by a CU (e.g., CU 172). Starting in FIG. 6A, in block 602, the CU receives a CN-to-BS message from a CN (e.g., CN 110) that includes a paging enhancement configuration for paging a UE (e.g., UE 102) (e.g., events 322, 338, 415, 465). In response to or after receiving the CN-to-BS message, in block 604, the CU sends a CU-to-DU message including the paging enhancement configuration to one or more DUs to page the UE (e.g., events 324, 340, 424, 440, or similar events in procedures 394, 494). As previously described, the CU may send the paging enhancement configuration to multiple DUs within the UE's paging area. In some implementations, the CU sends an inter-BS message including the paging extension configuration to one or more base stations (e.g., event 470) in block 606. The CU may send the paging extension configuration to multiple base stations within the paging area of ​​the UE.

[0081] 6B, method 600B is generally similar to method 600A. However, in block 603, the CU receives a paging extension configuration from a RAN node rather than from a CN as in block 602. The CU receives a first inter-BS message from a RAN node (e.g., a second base station, or a CU or DU of the second base station) including a paging extension configuration for paging the UE (e.g., event 470). In response to or after receiving the first inter-BS message, in block 605, the CU sends a CU-to-DU message including the paging extension configuration to one or more DUs to page the UE, similar to block 604. In some implementations, in block 607, the CU sends a second inter-BS message including the paging extension configuration to one or more base stations, similar to block 606.

[0082] In some implementations, the inter-BS message in block 606, 603, or 607 is a RAN paging message for paging the UE. In other implementations, the inter-BS message in block 606, 603, or 607 is a Handover Request message. For example, in block 603, a CU (i.e., a target CU) may receive a Handover Request message from a RAN node (e.g., a source CU or a source base station) in a handover preparation procedure for a UE operating in a connected state. In this example, the CU may send a Handover Request Acknowledge message to the RAN node in response to the Handover Request message. In still other implementations, the inter-BS message in block 606, 603, or 607 is a Retrieve UE Context Response message. For example, as a subroutine (not shown) within block 603, the CU (i.e., the new CU) sends a Retrieve UE Context Request message to a RAN node (e.g., the old CU or the old base station) for a UE operating in an inactive or idle state. In this example, the CU can receive a Retrieve UE Context Response message from the RAN node in response to the Retrieve UE Context Request message.

[0083] 7A-7B are flow diagrams of methods 700A and 700B, respectively, for sending a CU-to-DU message to a DU to instruct the DU to page the UE, which may be implemented by a CU (e.g., CU 172) and a CU-CP. Referring first to FIG. 7A, in block 702, the CU determines to send a CU-to-DU message to a DU (e.g., DU 174) to page the UE. In block 704, the CU determines whether the CU has a paging extension configuration for the UE. If so, flow proceeds to block 706, where the CU includes the paging extension configuration in the CU-to-DU message. In block 708, the CU sends the CU-to-DU message to one or more DUs (e.g., events 324, 340, 424, 440, or similar events in procedures 394, 494). If the CU does not have a paging configuration for the UE, flow proceeds directly from block 704 to block 708, where the CU sends a CU-to-DU message to one or more DUs, excluding the paging extension configuration.

[0084] Referring to FIG. 7B, method 700B is generally similar to method 700A. However, method 700B is performed by a CU-CP. In block 701, the CU-CP receives a DL data notification for a UE from a CU-UP. In block 703, in response to receiving the DL data notification, the CU-CP determines to send a CU-to-DU message to the DU to page the UE. In block 704, the CU-CP determines whether the CU has a paging extension configuration for the UE. If so, the CU-CP includes the paging extension configuration in the CU-to-DU message before sending the CU-to-DU message to one or more DUs in block 708.

[0085] 8-11 are flow diagrams of methods 800, 900, 1000, and 1100, respectively, for determining a subset of cells on which to page a UE (e.g., UE 102), which may be implemented by a DU (e.g., DU 174), a CU (e.g., CU 172), a base station (e.g., base station 104 or 106), and a CN (e.g., CN 110). After determining the subset of cells using any of methods 800-1100, the RAN can page the UE on the subset of cells using an enhanced paging mechanism described in this disclosure or using a legacy paging mechanism (e.g., a legacy paging mechanism as discussed in 3GPP TS38.304 V16.4.0 Release 16 Section 7.1).

[0086] Referring first to FIG. 8 , in block 802, the DU operates one or more cells, each supporting a frequency band. Each cell operated by the DU may support a different frequency band, or some of the one or more cells may support the same frequency band. In block 804, the DU receives a frequency band list from the CU, including frequency bands supported by the UE. As described with reference to FIG. 3 , the one or more frequency band lists may be included in the capabilities IE from the UE during the NAS paging enhancement activation procedure 392. In block 806, the DU receives a CU-to-DU message from the CU instructing the DU to page the UE. Prior to paging the UE, the DU determines, in block 808, a cell operated within a frequency band supported by both the UE and the DU based on the frequency band list and the frequency bands operated by the DU. For example, in block 808, the DU generates a second list of frequency bands that includes frequency bands in the frequency band list that are also supported by one or more cells operated by the DU. Thus, the second list of frequency bands is the intersection of the frequency band list (i.e., the frequency bands supported by the UE) and the frequency bands supported by the DU. The DU can then determine, among one or more cells operated by the DU, cells that support the frequency bands in the second list of frequency bands. In block 810, the DU sends a paging message to the UE on those cells (i.e., the cells determined in block 808). Thus, the DU pages the UE on cells that support the frequency bands supported by both the DU and the UE.

[0087] Referring now to FIG. 9, method 900 is similar to method 800, except that the CU, rather than the DU, determines the cell on which the DU should page the UE. In block 902, the CU receives a frequency band list from the CN, base station, or UE, including frequency bands supported by the UE. In block 904, the CU determines (cells supporting) frequency bands supported by both the UE and the DU based on the frequency band list and the frequency bands operated by the DU. Thus, similar to the DU in block 808, the CU determines a second list of frequency bands including frequency bands in the frequency band list that are also supported by one or more cells operated by the DU. The CU can then determine cells, among the one or more cells operated by the DU, that support frequency bands in the second list of frequency bands. In block 906, to page the UE, the CU sends a CU-to-DU message to the DU, including a list of cells and / or a list of frequency bands corresponding to those cells (i.e., the second list of frequency bands).

[0088] Referring to FIG. 10, method 1000 may be implemented by a CU or a base station. For brevity, the description of FIG. 10 refers to the base station as performing method 1000. In block 1002, the base station receives a frequency band list from a CN or UE, including frequency bands supported by the UE. In block 1004, the base station determines a frequency band to utilize for paging based on the frequency band list and the frequency bands operated by the RAN. Thus, similar to FIGS. 8-9, the base station determines the intersection of the frequency bands supported by the UE and the frequency bands supported by the RAN. In block 1006, the base station sends a BS-to-CN message to the CN, including the list of frequency bands determined in block 1006.

[0089] Referring to FIG. 11, method 1100 is performed by a CN. In block 1102, the CN performs a registration procedure with a UE via a RAN. In block 1204, the CN determines a frequency band to utilize for paging based on a frequency band list indicating frequency bands supported by the UE and frequency bands operated by the RAN. Thus, the CN determines the intersection of the frequency bands supported by the UE and the frequency bands supported by the RAN. In block 1206, the CN sends a CN-to-BS message to the RAN, including the list of frequency bands determined in block 1204, whereupon the RAN pages the UE using the list of frequency bands.

[0090] 12A-12B are flow diagrams of methods 1200A and 1200B, respectively, for delivering UE paging capabilities that may be implemented by a CU (e.g., CU 172). Referring initially to FIG. 12A, in block 1202, the CU receives a CN-to-BS message from the CN that includes one or more capabilities of the UE for paging. After or in response to receiving the CN-to-BS message, in block 1204, the CU sends a CU-to-DU message including the one or more capabilities to one or more DUs to page the UE. In some implementations, in block 1206, the CU also sends a BS-to-BS message including the one or more capabilities to one or more base stations to page the UE. The CU may send the one or more capabilities to one or more DUs, and in some implementations, one or more base stations, based on the paging area of ​​the UE.

[0091] 12B, method 1200B is generally similar to method 1200A. However, in block 1203, the CU receives one or more capabilities of the UE for paging from the BS rather than the CN. The CU receives the capabilities in a first inter-BS message. In response to or after receiving the first inter-BS message, in block 1205, the CU sends a CU-to-DU message including the one or more capabilities to one or more DUs to page the UE. In some implementations, the CU also sends a second inter-BS message including the one or more capabilities to one or more base stations in block 1207. The CU may send the one or more capabilities to one or more DUs, and in some implementations, one or more base stations, based on the paging area of ​​the UE.

[0092] In some implementations, the inter-BS message in block 1206, 1203, or 1207 is a RAN paging message for paging the UE. In other implementations, the inter-BS message in block 1206, 1203, or 1207 is a Handover Request message. For example, in block 1203, a CU (i.e., a target CU) may receive a Handover Request message from a RAN node (e.g., a source CU or a source base station) in a handover preparation procedure for a UE operating in a connected state. In this example, the CU may send a Handover Request Acknowledge message to the RAN node in response to the Handover Request message. In still other implementations, the inter-BS message in block 1206, 1203, or 1207 is a Retrieve UE Context Response message. For example, a CU (i.e., a new CU) may send a Retrieve UE Context Request message to a RAN node (e.g., an old CU or an old base station) for a UE operating in an inactive or idle state. In this example, the CU may receive a Retrieve UE Context Response message from the RAN node in response to the Retrieve UE Context Request message.

[0093] FIG. 13 is a flow diagram of a method 1300 for determining a configuration to use to page a UE, which may be implemented by a DU (e.g., DU 174). In block 1302, the DU receives a CU-to-DU message for paging the UE from a CU. In block 1304, in response to the CU-to-DU message, the DU generates a paging message including identification information of the UE. In block 1306, the DU determines whether the DU has paging capability for the UE. If so, flow proceeds to block 1308. In block 1308, the DU uses the paging capability to determine a first paging configuration for the UE. For example, if the paging capability indicates that the UE supports extended paging features such as PEI detection or paging subgrouping, the DU may decide to apply the extended paging configuration for the UE. The DU may have previously received the extended paging configuration (e.g., from the CU in a CU-to-DU message) or may have received the extended paging configuration in a CU-to-DU message in block 1302.

[0094] If the DU does not have paging capability for the UE, flow proceeds from block 1306 to block 1312, where the DU transmits a paging message to page the UE via one or more cells using a second paging configuration. The second paging configuration is a paging configuration that does not include extended paging functionality because the DU does not know whether the UE supports extended paging functionality. For example, the second paging configuration may be a pre-defined paging configuration such as that described in 3GPP TS38.304 V16.4.0 Release 16 Section 7.1.

[0095] FIG. 14 is a flow diagram of a method 1400 for selecting a paging configuration based on a radio resource control (RRC) state of a UE, which may be implemented by a CU (e.g., CU 172). In block 1402, the CU determines to page the UE. In block 1404, the CU determines whether the UE is operating in an idle state (e.g., RRC_IDLE) or an inactive state (e.g., RRC_INACTIVE). Based on whether the UE is in the idle state or the inactive state, the CU selects a paging configuration with which to page the UE. If the UE is in the idle state, in block 1406, the CU sends a first CU-to-DU message including a first paging DRX configuration to one or more DUs to page the UE. If the UE is in the inactive state, in block 1408, the CU sends a second CU-to-DU message including a second paging DRX configuration to one or more DUs to page the UE.

[0096] Each of the first and second paging DRX configurations may be a paging DRX IE or a paging eDRX information IE. The first and second paging DRX configurations may be different. For example, the second paging DRX configuration may have a shorter paging (e)DRX cycle or paging time window than the first paging DRX configuration. Furthermore, the first and second paging DRX configurations may originate from different sources. In some implementations, the CU receives the first paging DRX configuration from the CN. In some implementations, the CU determines the second paging DRX configuration by itself.

[0097] 15 is a flow diagram of a method 1500 that may be performed by a DU (e.g., DU 174) of a distributed base station (e.g., base station 104 or 106), where the distributed base station includes a DU and a CU (e.g., CU 172). The DU can perform the method 1500 to page a UE (e.g., UE 102) when a radio connection between the distributed base station and the UE is not active (e.g., when the UE operates in an idle or inactive state).

[0098] In block 1502, the DU receives a configuration for enhanced paging (i.e., a paging enhanced configuration) from the CU (e.g., events 324, 340, 424, 440). In block 1504, the DU pages the UE using the configuration (e.g., events 326, 327, 328, 426, 427, 428).

[0099] In some implementations, based on the configuration, the DU determines that the UE supports detecting a signal (e.g., a PEI signal) that informs the UE to attempt to receive a paging DCI at a paging occasion. In such implementations, paging the UE includes transmitting the signal and, after transmitting the signal, transmitting a paging DCI at the paging occasion. The DU can then transmit a paging message in accordance with the paging DCI. If the DU determines, based on the configuration, that the UE does not support such a signal, the DU can refrain from transmitting the signal prior to transmitting the paging DCI.

[0100] In some implementations, based on a configuration, the DU determines that the UE supports paging subgrouping. For example, the DU may determine a paging subgroup for the UE based on the configuration. Paging the UE may then include sending a paging subgroup indication to the UE based on the paging subgroup determination. The DU may send the indication by including a paging subgroup identifier (e.g., a paging subgroup ID or a subgroup-specific P-RNTI) in the paging DCI and sending the DCI to the UE. Alternatively, the DU may send the indication by scrambling the CRC value of the paging DCI with the paging subgroup identifier and sending the scrambled CRC value along with the paging DCI to the UE. If the DU determines that the UE does not support paging subgrouping or that the UE does not belong to a paging subgroup, the DU may send a paging DCI that omits the paging subgroup indication.

[0101] Furthermore, in some implementations, the DU determines, based on the configuration, (i) the UE supports detecting a signal (e.g., a PEI signal) that informs the UE to attempt to receive paging DCI on the paging occasion, and (ii) the paging subgroup of the UE. The DU can then page the UE by including an indication of the paging subgroup in the signal and sending the signal to the UE prior to sending the paging DCI.

[0102] The DU may page the UE when the UE operates in an idle or inactive state associated with a protocol for controlling radio resources (e.g., RRC_IDLE or RRC_INACTIVE). When the UE operates in an inactive state, the DU may page the UE by sending a paging message including an indication that the UE will initiate a procedure for receiving data without transitioning to a connected state (e.g., an instruction to perform early data communication). Depending on the implementation, the DU may receive the configuration as an IE defined by a protocol adapted for signaling between the CU and the DU (e.g., W1AP or FIAP) or as an IE defined by a protocol for controlling radio resources (e.g., the RRC protocol).

[0103] 16 is a flow diagram of a method 1600 that may be performed by a CU (e.g., CU 172) of a distributed base station (e.g., base station 104 or 106), where the distributed base station includes a CU and a DU (e.g., DU 174). The CU can perform the method 1600 to page a UE (e.g., UE 102) when a radio connection between the distributed base station and the UE is not active (e.g., when the UE operates in an idle or inactive state).

[0104] In block 1602, the CU receives a configuration for enhanced paging (e.g., events 322, 338, 415, 465). In block 1604, the CU decides to page the UE. In response to the decision to page the UE, the CU sends a configuration to the DU instructing the DU to page the UE using the configuration (e.g., events 324, 340, 424, 440) in block 1606.

[0105] In some implementations, the CU receives a configuration as a first IE defined by a protocol (e.g., NGAP) to which signaling between the CN and the CU conforms. The CU can decode the configuration from the first IE, encode the configuration as a second IE defined by a protocol (e.g., F1AP or W1AP) to which signaling between the CU and the DU conforms, and transmit the configuration to the DU as the second IE. In some implementations, after decoding the configuration, the CU determines that the DU does not support a parameter included in the configuration. The CU can modify the configuration by changing the parameter or excluding the parameter from the configuration and encode the modified configuration as the second IE.

[0106] In some implementations, the CU transmits the configuration to a second node of the RAN, such as a second DU of a distributed base station, or to a second base station. The CU may receive an indication of a paging area (e.g., a tracking area or RNA) of the UE and transmit the configuration to the second node based on the paging area. For example, the CU may transmit the configuration to a node within the paging area of ​​the UE.

[0107] The CU may decide to page the UE, for example, in response to receiving a message from the CN instructing the CU to page the UE, or in response to receiving data addressed to the UE from the CN. Depending on the implementation, the CU may receive the configuration from the core network, the second base station (or the CU or DU of the second base station), or the DU.

[0108] FIG. 17 is a flow diagram of a method 1700 for selecting a cell on which to page a UE (e.g., UE 102), which may be performed by a base station (e.g., base station 104 or 106) operating one or more cells. More specifically, method 1700 may be performed by a CU (e.g., CU 172) or DU (e.g., DU 174) of the base station. In block 1702, the base station receives a first list of frequency bands supported by the UE. In block 1704, the base station generates a second list of frequency bands that includes frequency bands of the first list of frequency bands that are supported by one or more cells. In block 1706, the base station pages the UE on a cell of the one or more cells that supports frequency bands of the second list of frequency bands. If method 1700 is performed by a DU, paging the UE includes sending a paging message on a cell of the one or more cells. When method 1700 is performed by a CU, paging the UE may include sending a second list of frequency bands or a list of cells of the one or more cells to the DU of the base station to cause the DU to page the UE on a cell of the one or more cells.

[0109] 18 is a flow diagram of a method 1800 for paging a UE (e.g., UE 102) that may be implemented by a CU (e.g., CU 172) of a distributed base station, the distributed base station including a CU and a DU (e.g., DU 174). In block 1802, the CU determines to page the UE. In block 1804, the CU determines whether the UE is in an idle state associated with a protocol for controlling radio resources or an inactive state associated with the protocol. In block 1806, the CU selects a paging configuration based on whether the UE is in an idle state or an inactive state. In block 1808, the CU transmits the selected paging configuration to the DU.

[0110] The following explanations may be applied to the above explanations.

[0111] In some implementations, "message" may be used and replaced by "information element (IE)". In some implementations, "IE" may be used and replaced by "field". In some implementations, "configuration" may be replaced by "configurations" or configuration parameters. In some implementations, "early data communication" may be replaced by "small data communication", and "early data transmission" may be replaced by "small data transmission".

[0112] When a cell is operated in a time division duplex (TDD) mode or on a TDD carrier frequency, the DL BWP and UL BWP (i.e., associated with the DL BWP) of the cell may be the same BWP. When a cell is operated in a frequency division duplex (FDD) mode or on a pair of FDD carrier frequencies (i.e., a UL carrier frequency and a DL carrier frequency), the DL BWP and UL BWP (i.e., associated with the DL BWP) of the cell are different BWPs. In this case, the DL BWP is the BWP of the DL carrier frequency, and the UL BWP is the BWP of the UL carrier frequency. In some implementations, one of the UL BWPs of a cell may partially overlap with another or have no overlap with the other. In other implementations, one of the UL BWPs may be completely interior to another. In some implementations, one of the DL BWPs of a cell may partially overlap with another or have no overlap with the other. In other implementations, one of the DL BWPs may be completely interior to another.

[0113] A user device (e.g., UE 102) in which the techniques of this disclosure may be implemented may be any suitable device capable of wireless communication, such as a smartphone, a tablet computer, a laptop computer, a mobile gaming 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 smartwatch, a wireless hotspot, a femtocell, or a broadband router. Furthermore, a user device may in some cases be embedded in an electronic system such as a vehicle head unit or an advanced driver assistance system (ADAS). Still further, a user device may operate as an Internet of Things (IoT) device or a mobile internet device (MID). Depending on the type, a user device may include one or more general-purpose processors, computer-readable memory, a user interface, one or more network interfaces, one or more sensors, etc.

[0114] Some embodiments are described in this disclosure as including logic or several components or modules. A module may be a software module (e.g., code or machine-readable instructions stored on a non-transitory machine-readable medium) or a hardware module. A hardware module is a tangible unit capable of performing several operations and may be configured or arranged in a certain manner. A hardware module may comprise dedicated circuitry or logic that is permanently configured (e.g., as a dedicated processor such as a field programmable gate array (FPGA) or application-specific integrated circuit (ASIC), a digital signal processor (DSP), etc.) to perform several operations. A hardware module may also comprise programmable logic or circuitry that is temporarily configured by software (e.g., as contained within a general-purpose processor or other programmable processor) to perform several operations. The decision whether to implement a hardware module in dedicated, permanently configured circuitry or in temporarily configured circuitry (e.g., configured by software) may be determined by cost and time considerations.

[0115] 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.

[0116] The following list of examples reflects various embodiments expressly contemplated by this disclosure.

[0117] Example 1. A method in a distributed unit (DU) of a distributed base station of a radio access network (RAN) for paging a user equipment (UE) when a radio connection between the distributed base station and the UE is not active, the distributed base station including a DU and a central unit (CU), the method including: receiving, by processing hardware of the DU, a configuration for enhanced paging from the CU; and paging the UE using the configuration, by the processing hardware.

[0118] Example 2. The method of Example 1, wherein the method further includes determining, by the processing hardware, based on the configuration, that the UE supports detecting a signal informing the UE to attempt to receive paging downlink control information (DCI) at the paging occasion, and wherein paging the UE includes, based on the determination, transmitting the signal, and after transmitting the signal, transmitting paging DCI at the paging occasion.

[0119] Example 3. The method of Example 1, wherein the method further includes determining, by the processing hardware, based on the configuration, that the UE does not support detecting a signal that informs the UE to attempt to receive paging downlink control information (DCI) on the paging occasion, and wherein paging the UE includes refraining from transmitting the signal based on the determination.

[0120] Example 4. The method of any one of Examples 1 to 3, wherein the method further includes determining, by processing hardware, a paging subgroup for the UE based on the configuration, and wherein paging the UE includes sending an indication of the paging subgroup to the UE based on the determination.

[0121] Example 5. The method of Example 4, wherein the DU sends the indication by including a paging subgroup identifier in a paging downlink control information (DCI) and sending the paging DCI to the UE.

[0122] Example 6. The method of Example 4, wherein the DU sends the indication by scrambling a cyclic redundancy check (CRC) value of a paging downlink control information (DCI) using a paging subgroup identifier and sending the scrambled CRC value along with the paging DCI to the UE.

[0123] Example 7. The method of any one of Examples 1 to 3, wherein the method further includes determining, based on the configuration, that the UE does not belong to a paging subgroup, and wherein paging the UE includes, based on the determination, generating paging downlink control information (DCI) that omits the indication of the paging subgroup, and transmitting the paging DCI to the UE.

[0124] Example 8. The method of Example 1, wherein the method further includes, by the processing hardware, supporting the UE based on the configuration: (i) detecting a signal informing the UE to attempt to receive paging downlink control information (DCI) at the paging occasion; and (ii) determining a paging subgroup of the UE, wherein paging the UE includes, in response to the determination, including an indication of the paging subgroup in the signal; transmitting the signal to the UE; and, after transmitting the signal, transmitting the paging DCI at the paging occasion.

[0125] Example 9. The method of any one of the preceding examples, wherein paging the UE includes paging the UE when the UE operates in an idle state associated with a protocol for controlling radio resources.

[0126] Example 10. The method of any one of Examples 1 to 8, wherein paging the UE includes paging the UE when the UE operates in an inactive state associated with a protocol for controlling radio resources.

[0127] Example 11. The method of Example 10, wherein the step of paging the UE includes the step of transmitting a paging message including an indication that the UE is to initiate a procedure for receiving data without transitioning to a connected state.

[0128] Example 12. The method of any one of the preceding examples, wherein the DU receives the configuration as an information element (IE) defined by a protocol that conforms to signaling between the CU and the DU.

[0129] Example 13. The method of any one of Examples 1 to 11, wherein the DU receives the configuration as an information element (IE) defined by a protocol for controlling radio resources.

[0130] Example 14. A method in a central unit (CU) of a distributed base station of a radio access network (RAN) for paging a user equipment (UE) when a radio connection between the distributed base station and the UE is not active, the distributed base station including a CU and a distributed unit (DU), the method including: receiving, by processing hardware of the CU, a configuration for enhanced paging; determining, by the processing hardware, to page the UE; and, in response to the determination, sending, by the processing hardware, the configuration to the DU to instruct the DU to page the UE using the configuration.

[0131] Example 15. The method of Example 14, wherein the CU receives the configuration as a first information element (IE) defined by a protocol to which signaling between the core network and the CU conforms, the method further comprising: decoding, by processing hardware, the configuration from the first IE; and encoding, by processing hardware, the configuration as a second IE defined by a protocol to which signaling between the CU and the DU conforms, and the CU transmits the configuration to the DU as the second IE.

[0132] Example 16. The method of Example 15, wherein the method further includes, after decoding the configuration, determining, by the processing hardware, that the DU does not support a parameter included in the configuration, and modifying, by the processing hardware, the configuration by changing the parameter or excluding the parameter from the configuration, and wherein the CU encodes the modified configuration as a second IE.

[0133] Example 17. The method of any one of Examples 14 to 16, further comprising transmitting, by the processing hardware, the configuration to a second node of the RAN in response to the determination.

[0134] Example 18. The method of Example 17, wherein the DU is a first DU of a distributed base station and the second node is a second DU of the distributed base station.

[0135] Example 19. The method of example 17, wherein the distributed base station is a first base station and the second node is a second base station.

[0136] Example 20. The method of any one of Examples 17 to 19, wherein the method further includes receiving, by processing hardware, an indication of a paging area of ​​the UE, and wherein transmitting the configuration to the second node includes transmitting the configuration to the second node based on the paging area.

[0137] Example 21. The method of any one of Examples 14 to 20, wherein the CU receives a configuration for the UE in a message from the core network instructing the CU to page the UE, and the CU determines to page the UE in response to receiving the message.

[0138] Example 22. The method of any one of Examples 14 to 20, wherein the method further includes receiving data addressed to the UE from the core network, and wherein the CU, in response to receiving the data, determines to page the UE.

[0139] Example 23. The method of any one of Examples 14 to 20, wherein the CU receives a configuration from a core network.

[0140] Example 24. The method of any one of Examples 14 to 20, wherein the CU receives the configuration from the second base station.

[0141] Example 25. The method of Example 24, wherein the CU receives a configuration from the DU of the second base station.

[0142] Example 26. The method of any one of Examples 14 to 20, wherein the CU receives a configuration from the DU.

[0143] Example 27. A method in a base station for paging a user equipment (UE), wherein the base station operates one or more cells, the method including: receiving, by processing hardware of the base station, a first list of frequency bands supported by the UE; generating, by the processing hardware, a second list of frequency bands that includes frequency bands of the first list of frequency bands that are supported by one or more cells; and paging, by the processing hardware, the UE on a cell of the one or more cells that supports frequency bands of the second list of frequency bands.

[0144] Example 28. The method of example 27, wherein the method is performed by a distributed unit (DU) of a base station.

[0145] Example 29. The method of Example 28, wherein paging the UE includes sending a paging message on a cell of the one or more cells.

[0146] Example 30. The method of example 27, wherein the method is performed by a central unit (CU) of a base station.

[0147] Example 31. The method of Example 30, wherein the step of paging the UE includes sending a second list of frequency bands to the DU of the base station to cause the DU to page the UE on a cell of the one or more cells.

[0148] Example 32. The method of Example 30, wherein the step of paging the UE includes generating a list of cells of the one or more cells and sending the list of cells to a DU of the base station to cause the DU to page the UE on the cells.

[0149] Example 33. A method in a central unit (CU) of a distributed base station for paging a user equipment (UE), the distributed base station including a CU and a distributed unit (DU), the method including: determining, by processing hardware of the CU, to page the UE; determining, by the processing hardware, whether the UE is in an idle state associated with a protocol for controlling radio resources or an inactive state associated with the protocol; selecting, by the processing hardware, a paging configuration based on whether the UE is in the idle state or the inactive state; and transmitting, by the processing hardware, the paging configuration to the DU.

[0150] Example 34. A node of a radio access network (RAN) comprising processing hardware and configured to implement a method according to any one of the above examples. [Explanation of symbols]

[0151] 100 Exemplary Wireless Communication System 102UE 104 base station (BS), base station 105 Radio Access Network (RAN), RAN 106 Base Station 110 Core Network (CN), CN 111 Evolved Packet Core (EPC), EPC 112 Serving Gateway (SGW), SGW 114 Mobility Management Entity (MME), MME 116 Packet Data Network Gateway (PGW), PGW 124, 126 cells 130, 140 Processing hardware, components 132 Medium Access Control (MAC) Controller, Component 134 Packet Data Convergence Protocol (PDCP) Controller, Component, PDCP Controller 136, 146 RRC controller, components 138, 148 Paging controller, components 142 Component, MAC Controller 144 Components, PDCP Controller 150 Processing Hardware 152 Medium Access Control (MAC) Controller 154 PDCP Controller 156 RRC Controller 158 Paging Controller 160 5th Generation (5G) Core (5GC), 5GC 162 User Plane Function (UPF), UPF 164 Access and Mobility Management (AMF), AMF 166 Session Management Facility (SMF), SMF 172 Central Unit (CU), CU 172A Logical nodes CU-CP, CU-CP, CU 172B Logical nodes CU-UP, CU-UP, CU 174 Distributed Unit (DU), DU 174A, 174B DU 200 Exemplary Protocol Stack, Exemplary Stack 202A Physical Layer (PHY) 202B NR PHY 204A EUTRA MAC Sublayer 204B NR MAC sublayer, NR MAC 206A EUTRA RLC sublayer, EUTRA RLC, RLC layer 206B NR RLC sublayer, RLC layer, NR RLC 208 EUTRA PDCP sublayer, PDCP layer 210 NR PDCP sublayer, NR PDCP, PDCP layer 212 Service Data Adaptation Protocol (SDAP), SDAP sublayer, SDAP 214 RRC 250 Wireless Protocol Stack 300A, 300B, 300C, 400A, 400B, 400C, 400D scenarios 304, 306, 308, 312, 314, 316, 318, 320, 322, 326, 327, 328, 338, 340, 343, 344, 415, 424, 426, 427, 428, 430, 440, 446, 448, 450, 451, 452, 453, 454, 455, 456, 457, 458, 459, 460, 465, 470 Events 310 Events, DL NAS Messages 324 Third CU to DU Message, Event 392 NAS Paging Enhancement Activation Procedure 394 Event, Extended Paging Procedure, Successful Extended Paging Procedure, Procedure 462 RRC Release Message, Event 494 Events, Extended Paging Procedures, Procedures 496, 497 Data communication procedures

Claims

1. 1. A method for paging a user equipment (UE) in a distributed unit (DU) of a distributed base station of a radio access network (RAN) when a radio connection between the distributed base station and the UE is inactive, the distributed base station including the DU and a central unit (CU), the method comprising: receiving, by the DU, from the CU, a paging message indicating whether the UE supports paging subgrouping; paging the UE by the DU according to whether the UE supports paging subgrouping; A method comprising:

2. receiving the paging message, receiving the paging message including a paging subgroup identification information of the UE; 2. The method of claim 1, comprising:

3. receiving the paging message, receiving the paging message defined by a protocol adapted for signaling between the CU and the DU; 2. The method of claim 1, comprising:

4. 2. The method of claim 1, wherein receiving the paging message comprises receiving a UE capability information element (IE) included in the paging message.

5. The method of claim 4 , wherein the UE capability IE indicates whether the UE supports paging subgrouping.

6. The method of claim 4 , wherein the UE capability IE indicates whether the UE supports detecting a paging early indication (PEI).

7. The method of claim 1 , wherein the paging message further indicates whether the UE supports detecting a paging early indication (PEI).

8. 1. A method in a central unit (CU) of a distributed base station of a radio access network (RAN) for paging a user equipment (UE) when a radio connection between the distributed base station and the UE is inactive, the distributed base station including the CU and a distributed unit (DU), the method comprising: determining, by the CU, to page the UE; In response to the determination, sending a paging message to the DU to instruct the DU to page the UE, the paging message indicating whether the UE supports paging subgrouping; A method comprising:

9. the step of transmitting the paging message comprises: transmitting the paging message including a paging subgroup identity of the UE; 9. The method of claim 8, comprising:

10. the step of transmitting the paging message comprises: transmitting the paging message defined by a protocol adapted for signaling between the CU and the DU; 9. The method of claim 8, comprising:

11. 9. The method of claim 8, wherein transmitting the paging message comprises transmitting a UE capability information element (IE) included in the paging message, the UE capability IE indicating whether the UE supports paging subgrouping.

12. The method of claim 8 , wherein the paging message further indicates whether the UE supports detecting a paging early indication.

13. the paging message is a first paging message, and the method comprises: sending a second paging message to a second node of the RAN in response to the determination, the second paging message indicating whether the UE supports paging subgrouping.

9. The method of claim 8, further comprising:

14. The method comprises: receiving a message from a core network instructing the CU to page the UE prior to determining to page the UE, the message indicating whether the UE supports paging subgrouping; further comprising The method of claim 8 , wherein the CU determines to page the UE in response to receiving the message.

15. A node of a Radio Access Network (RAN) comprising processing hardware and configured to perform the method of any one of claims 1 to 14.

Images