Communication device, base station, and communication method

Abstract

To provide a device capable of determining a paging subgroup.SOLUTION: In a mobile communication system, a communication device (100) includes: a receiving unit (112) that receives first information indicating the number of subgroups per paging occasion and second information on the setting of subgroups based on user equipment identity (UE_ID) from a network (10); and a control unit (120) that calculates the UE_ID using a predetermined formula based on the first information and the second information and calculates the subgroup identifier based on the UE_ID calculated using a predetermined formula. The receiving unit monitors paging opportunities based on the subgroup identifier.SELECTED DRAWING: Figure 6

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on and claims the benefit of priority from patent application serial number 2023-542438, filed August 18, 2022, the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a communication device, a base station, and a communication method used in a mobile communication system. [Background technology]

[0003] In 3GPP (registered trademark, hereinafter the same) (3rd Generation Partnership Project), a standardization project for mobile communication systems, discussions are underway to reduce power consumption for communication devices in an RRC (Radio Resource Control) idle state or an RRC inactive state (see Non-Patent Document 1). Specifically, they are considering introducing a mechanism to classify each of multiple communication devices assigned to the same paging occasion into one of multiple subgroups (hereinafter referred to as paging subgroups).

[0004] Before transmitting a paging message, the network notifies each communication device of the paging subgroup to which the communication device to which the paging message is to be sent belongs. Only when a communication device in an RRC idle state or an RRC inactive state determines that it belongs to the notified paging subgroup, does the communication device perform reception processing of the paging message (specifically, reception and decoding of the physical downlink shared channel) and determine whether its own unique identifier is included in the paging message. On the other hand, when a communication device determines that it does not belong to the notified paging subgroup, the communication device can skip reception processing of the paging message at the paging opportunity, thereby reducing power consumption.

[0005] As a method for determining a paging subgroup to which a communication device belongs, a method has been proposed in which the communication device determines the paging subgroup based on its own unique identifier (e.g., 5G-S-TMSI). Specifically, the communication device calculates a user equipment identity (UE identity: UE ID) from its own unique identifier, and calculates a paging subgroup to which the communication device belongs (specifically, a paging subgroup ID (UE subgroup ID)) from the calculated user equipment identity. As a formula for calculating a paging subgroup ID from the user equipment identity, the following formula has been proposed: UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg. N is the total number of paging frames (PFs) in a discontinuous reception (DRX) cycle of the communication device, Ns is the number of paging opportunities per PF, and Nsg is the number of paging subgroups (specifically, the maximum number of paging subgroups per paging opportunity in a cell).

[0006] Here, if the paging subgroup is calculated using the above formula from the user equipment identity calculated using the formula "UE_ID=5G-S-TMSI mod 1024" specified in the current 3GPP technical specifications, and the condition "N*Ns*Nsg > 1024" is satisfied, all communication devices assigned to the same paging occasion will belong to the same paging subgroup. Therefore, Non-Patent Document 2 describes calculating the user equipment identity using the formula "UE identity=5G-S-TMSI mod 1024*Nsg". [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] 3GPP contribution: RP-200938 [Non-patent document 2] 3GPP contribution: R2-2106999 Summary of the Invention

[0008] A communication device according to a first aspect includes a receiver that receives from a network first information indicating the number of subgroups per paging occasion and second information related to the configuration of the subgroups based on a user equipment identity (UE_ID), and a controller that calculates the UE_ID using a predetermined calculation formula based on the first information and the second information, and calculates a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula. The receiver monitors paging occasions based on the subgroup identifier.

[0009] A base station according to a second aspect includes a transmitter that transmits, to a communication device, first information indicating the number of subgroups per paging occasion and second information related to configuration of the subgroups based on a user equipment identity (UE_ID), and a controller that calculates the UE_ID using a predetermined calculation formula based on the first information and the second information, and calculates a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula. The transmitter transmits downlink control information on a physical link control channel at paging occasions based on the subgroup identifier.

[0010] A communication method according to a third aspect is a communication method executed by a communication device, and includes the steps of receiving, from a network, first information indicating a number of subgroups per paging occasion and second information related to configuration of the subgroups based on a user equipment identity (UE_ID), calculating the UE_ID using a predetermined calculation formula based on the first information and the second information, calculating a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula, and monitoring paging occasions based on the subgroup identifier. [Brief explanation of the drawings]

[0011] The objects, features, advantages, and other features of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a diagram showing a configuration of a mobile communication system according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a protocol stack in the mobile communication system according to the embodiment. [Figure 3] FIG. 3 is a diagram illustrating paging subgrouping. [Figure 4] FIG. 4 illustrates an example of operation for a UE in an RRC idle state or an RRC inactive state. [Figure 5] FIG. 5 is a diagram for explaining an example of formulas for calculating PF, PO, and SFN. [Figure 6] FIG. 6 is a diagram illustrating a configuration of a UE according to the embodiment. [Figure 7] FIG. 7 is a diagram illustrating a configuration of a base station according to the embodiment. [Figure 8] FIG. 8 is a sequence diagram illustrating a first operation example according to an embodiment. [Figure 9] FIG. 9 is a flowchart illustrating a first operation example according to an embodiment. [Figure 10] FIG. 10 is a diagram illustrating an example of a formula for calculating a user device identity in a first operation example according to an embodiment. [Figure 11] FIG. 11 is a flowchart for explaining a second operation example and a third operation example according to an embodiment. [Figure 12] FIG. 12 is a diagram illustrating an example of a formula for calculating a user equipment identity in the second operation example according to an embodiment. [Figure 13] FIG. 13 is a diagram illustrating an example of a formula for calculating a user equipment identity in the third operation example according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] A mobile communication system according to an embodiment will be described with reference to the drawings. In the description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

[0013] When calculating user equipment identities using the formula described in Non-Patent Document 2, the number of user equipment identities increases compared to the calculation method using the formula specified in the current 3GPP technical specifications, and therefore the number of bits required to represent the user equipment identities increases. As a result, for example, when transmitting user equipment identities between base stations, there is a problem that the amount of information of the user equipment identities increases. Therefore, one object of the present disclosure is to provide a communication device, a base station, and a communication method that can suppress the increase in the amount of information of user equipment identities in a mobile communication system in which each of multiple communication devices assigned to the same paging occasion can be classified into one of multiple paging subgroups.

[0014] (Configuration of a mobile communication system) The configuration of a mobile communication system 1 according to an embodiment will be described with reference to Fig. 1. The mobile communication system 1 is, for example, a system that complies with the 3GPP Technical Specification (TS). In the following, the mobile communication system 1 will be described using as an example a 5th Generation System (5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio).

[0015] The mobile communication system 1 includes a network 10 and user equipment (UE) 100 that communicates with the network 10. The network 10 includes a next generation radio access network (NG-RAN) 20 that is a 5G radio access network, and a 5G core network (5GC) 30 that is a 5G core network.

[0016] UE 100 is an example of a communication device. UE 100 is an example of a communication device. UE 100 may be a mobile wireless communication device. UE 100 may be a device used by a user. UE 100 is a mobile device such as a mobile phone terminal such as a smartphone, a tablet terminal, a laptop PC, a communication module, or a communication card. UE 100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein (e.g., Vehicle UE). UE 100 may be a transport vehicle other than a vehicle (e.g., a ship, an airplane, an air vehicle, etc.) or a device provided therein. UE 100 may be a sensor or a device provided therein. UE 100 may be called by other names such as a mobile station, a mobile terminal, a mobile device, a mobile unit, a subscriber station, a subscriber terminal, a subscriber device, a subscriber unit, a wireless station, a wireless terminal, a wireless device, a wireless unit, a remote station, a remote terminal, a remote device, or a remote unit.

[0017] The NG-RAN 20 includes multiple base stations 200. Each base station 200 manages at least one cell. A cell constitutes the smallest unit of a communication area. For example, one cell belongs to one frequency (carrier frequency) and is composed of one component carrier. The term "cell" may refer to wireless communication resources or to a communication target of the UE 100. Each base station 200 can perform wireless communication with the UE 100 located in its own cell. The base station 200 communicates with the UE 100 using a RAN protocol stack. The base station 200 provides NR user plane and control plane protocol termination for the UE 100 and is connected to the 5GC 30 via an NG interface. Such an NR base station 200 is sometimes referred to as a gNodeB (gNB).

[0018] The 5GC 30 includes a core network device 300. The core network device 300 includes, for example, an Access and Mobility Management Function (AMF) and / or a User Plane Function (UPF). The AMF performs mobility management for the UE 100. The UPF provides functions specialized for user plane processing. The AMF and the UPF are connected to the base station 200 via an NG interface.

[0019] An example of the configuration of a protocol stack in the mobile communication system 1 according to the embodiment will be described with reference to FIG.

[0020] The protocol for the wireless section between UE 100 and base station 200 includes a physical (PHY) layer, a medium access control (MAC) layer, a radio link control (RLC) layer, a packet data convergence protocol (PDCP) layer, and a radio resource control (RRC) layer.

[0021] The PHY layer performs encoding / decoding, modulation / demodulation, antenna mapping / demapping, and resource mapping / demapping. Data and control information are transmitted between the PHY layer of the UE 100 and the PHY layer of the base station 200 via a physical channel.

[0022] A physical channel consists of multiple Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and multiple subcarriers in the frequency domain. One subframe consists of multiple OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple subcarriers. A frame can be configured for 10 ms and can include 10 subframes, each of which is 1 ms long. A subframe can include a number of slots depending on the subcarrier spacing.

[0023] Among the physical channels, the Physical Downlink Control Channel (PDCCH) plays a central role for purposes such as downlink scheduling assignment, uplink scheduling grant, and transmit power control.

[0024] In NR, the UE 100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). The base station 200 configures the UE 100 with a bandwidth portion (BWP) consisting of consecutive PRBs. The UE 100 transmits and receives data and control signals in the active BWP. For example, up to four BWPs can be configured for the UE 100. Each BWP may have a different subcarrier spacing or may overlap in frequency. When multiple BWPs are configured for the UE 100, the base station 200 can specify which BWP to activate by controlling the downlink. This allows the base station 200 to dynamically adjust the UE bandwidth according to the amount of data traffic of the UE 100, etc., and can reduce UE power consumption.

[0025] For example, base station 200 can configure up to three control resource sets (CORESETs) for each of up to four BWPs on the serving cell. A CORESET is a radio resource for control information to be received by UE 100. Up to 12 CORESETs can be configured for UE 100 on the serving cell. Each CORESET has an index of 0 to 11. For example, a CORESET consists of six resource blocks (PRBs) and one, two, or three consecutive OFDM symbols in the time domain.

[0026] The MAC layer performs data priority control, retransmission processing using Hybrid ARQ (HARQ), random access procedures, etc. Data and control information are transmitted between the MAC layer of UE 100 and the MAC layer of base station 200 via a transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the uplink and downlink transport format (transport block size, modulation and coding scheme (MCS)) and the resources to be allocated to UE 100.

[0027] The RLC layer transmits data to the RLC layer on the receiving side using the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of the UE 100 and the RLC layer of the base station 200 via logical channels.

[0028] The PDCP layer performs header compression / decompression and encryption / decryption.

[0029] An SDAP (Service Data Adaptation Protocol) layer may be provided above the PDCP layer, which maps IP flows, which are units for Quality of Service (QoS) control by the core network, to radio bearers, which are units for QoS control by the AS (Access Stratum).

[0030] The RRC layer controls logical channels, transport channels, and physical channels according to the establishment, re-establishment, and release of radio bearers. RRC signaling for various settings is transmitted between the RRC layer of the UE 100 and the RRC layer of the base station 200. When there is an RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC connected state. When there is no RRC connection between the RRC of the UE 100 and the RRC of the base station 200, the UE 100 is in an RRC idle state. When the RRC connection between the RRC of the UE 100 and the RRC of the base station 200 is suspended, the UE 100 is in an RRC inactive state.

[0031] The NAS layer located above the RRC layer performs session management and mobility management for the UE 100. NAS signaling is transmitted between the NAS layer of the UE 100 and the NAS layer of the core network device 300 (AMF). Note that the UE 100 has an application layer and the like in addition to a radio interface protocol.

[0032] (Assumed scenario) 3 to 5, a description will be given of an assumed scenario in the mobile communication system 1 according to the embodiment.

[0033] For paging reception, the paging message sent by the network 10 (base station 200) includes an identifier for each UE 100 that the network 10 pages.

[0034] In order to reduce power consumption, the UE 100 in the RRC idle state or the RRC inactive state intermittently monitors paging using discontinuous reception (DRX). Such a cycle of monitoring paging is called a DRX cycle. A frame in which the UE 100 should monitor paging is called a paging frame (PF), and a subframe in this PF in which the UE 100 should monitor paging is called a paging occasion (PO). In a PO, the UE 100 may receive a paging message.

[0035] The UE 100 in the RRC idle state or the RRC inactive state wakes up at the PO, monitors the paging message, and performs reception processing of the paging message (specifically, reception and decoding of the Physical Downlink Shared Channel (PDSCH)). After performing the reception processing, the UE 100 determines whether its own unique identifier is included in the paging message. If its own identifier is included in the paging message, the UE 100 considers that a call has been made, and performs an operation of transitioning to the RRC connected state, for example.

[0036] In this way, in the paging reception operation, all UEs 100 assigned the same PO wake up in the PO to monitor the paging and receive the paging message. A group of UEs assigned the same PO is called a paging group. Here, UEs 100 that are not actually called by the network 10 also wake up and perform the paging message reception process, resulting in extra power consumption.

[0037] Therefore, each of the multiple UEs 100 assigned to the same PO is classified (i.e., grouped) into one of multiple subgroups (hereinafter referred to as paging subgroups (PSGs)) that are smaller units than a paging group. Fig. 3 shows an example in which a paging group is divided into three paging subgroups with paging subgroup IDs "#1" to "#3". Although an example in which the number of UEs 100 belonging to each paging subgroup is three is shown, the number of UEs 100 belonging to each paging subgroup may be one or two, or may be four or more.

[0038] As methods for grouping UEs 100 assigned to the same PO, two grouping methods are being considered: a first grouping method (so-called CN-assigned subgrouping) in which the network 10 assigns a paging subgroup ID to each UE 100, and a second grouping method (so-called UE_ID based subgrouping) in which the UE 100 itself determines the paging subgroup.

[0039] In the first grouping method, the assignment of a paging subgroup ID to each UE 100 may be performed, for example, at the time of network registration of the UE 100. The network 10 assigns the paging subgroup ID depending on the characteristics of the UE 100 (e.g., paging probability, power consumption profile, and / or mobility state, etc.).

[0040] In the second grouping method, the UE 100 determines a paging subgroup based on its own unique identifier (for example, 5G-S-Temporary Mobile Subscriber Identifier (TMSI)). Specifically, the UE 100 calculates a user equipment identity (UE ID) from its own unique identifier, and calculates a paging subgroup to which the UE 100 belongs (specifically, a paging subgroup ID (UE subgroup ID)) from the calculated user equipment identity. As a formula for calculating a paging subgroup ID from a user equipment identity, the following formula has been proposed: "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg." N is the total number of PFs in a DRX cycle of the UE 100 in a cell, Ns is the number of POs per PF in the cell, and Nsg is the number of paging subgroups in the cell (specifically, the maximum number of paging subgroups per PO in the cell in which the UE 100 is located) (see FIG. 5). 5G-S-TMS is a temporary mobile subscription identifier.

[0041] Before transmitting a paging message, the network 10 (base station 200) notifies each UE 100 of the paging subgroup to which the UE 100 to which the paging message is to be transmitted belongs. For example, prior to a PO, the network 10 (base station 200) notifies each UE 100 of the paging subgroup ID to which the UE 100 to be called by the paging message transmitted in the PO belongs (so-called paging early indication). The network 10 notifies each UE 100 of the paging subgroup ID by using, for example, a reference signal / synchronization signal.

[0042] Each UE 100 in the RRC idle state or the RRC inactive state wakes up in the PO and performs paging monitoring only when it has been notified of the paging subgroup ID to which it belongs (i.e., it belongs to the notified paging subgroup). This means that UEs 100 that belong to some paging subgroups do not need to wake up in the PO, thereby suppressing unnecessary power consumption.

[0043] Furthermore, in order to notify each UE 100 of the paging subgroup to which the UE 100 to which a paging message is to be transmitted belongs, for example, the network 10 (base station 200) may transmit, via a PDCCH, downlink control information (DCI) including a paging subgroup ID to which the UE 100 to be called by the paging message transmitted via a PO belongs. The UE 100 receives (decodes) the DCI to which a CRC (Cyclic Redundancy Check) parity bit scrambled by a P-RNTI (Paging Radio Network Temporary Identifier) ​​is added, via the PDCCH. Here, the base station 200 may configure the P-RNTI for the UE 100. The DCI may also be in a DCI format used for scheduling a physical downlink shared channel (PDSCH). The DCI to which a CRC parity bit scrambled by the P-RNTI is added is also referred to as paging DCI.

[0044] When UE 100 receives (decodes) the PDCCH, if the paging subgroup ID included in the DCI indicates the paging subgroup to which UE 100 belongs, UE 100 determines that UE 100 belongs to the notified paging subgroup. UE 100 performs reception processing of the paging message (specifically, receives and decodes the PDSCH) only if UE 100 belongs to the notified paging subgroup, and determines whether its own unique identifier is included in the paging message. When UE 100 determines that UE 100 does not belong to the notified paging subgroup, UE 100 can skip reception processing of the paging message at the paging occasion, thereby reducing power consumption.

[0045] 4 shows an example of operation when UE 100 in an RRC idle state or an RRC inactive state determines a paging subgroup (the second grouping method described above). UE 100 is located in a cell managed by base station 200. This cell may be a cell selected by UE 100 through cell (re)selection, and may also be referred to as a camped-on cell.

[0046] In step S11, the UE 100 in an RRC idle state or an RRC inactive state determines a user equipment identity (UE identity: UE_ID) based on its own unique identifier.

[0047] In step S12, the UE 100 calculates (determines) a paging frame, a paging occasion, and a paging subgroup.

[0048] As shown in Figure 5, the UE 100 calculates a paging frame (specifically, a system frame number (SFN) that is a paging frame) based on the calculated user equipment identity using equation E11. The UE 100 calculates a paging occasion (specifically, a paging occasion index (i_s)) based on the calculated user equipment identity using equation E12. The UE 100 calculates a paging subgroup (PSG) based on the calculated user equipment identity using equation E13. The calculated paging subgroup is the paging subgroup to which the UE 100 belongs.

[0049] In step S13, before transmitting a paging message, the network 10 (base station 200) notifies each UE 100 of the paging subgroup ID to which the UE 100 to which the paging message is to be transmitted belongs. The UE 100 receives the paging subgroup ID from the base station 200 in the cell in which the UE 100 is located.

[0050] The UE 100 determines whether or not it belongs to the notified paging subgroup. Specifically, if the calculated paging subgroup matches the notified paging subgroup ID, the UE 100 determines whether or not it belongs to the notified paging subgroup. If not, the UE 100 determines that it does not belong to the notified paging subgroup. The UE 100 performs the following process only if it belongs to the notified paging subgroup. Therefore, the UE 100 maintains a wake-up state to receive a paging message from the base station 200. On the other hand, if the UE 100 does not belong to the notified paging subgroup, the UE 100 may transition to a sleep state in which the following process is not performed.

[0051] In step S14, the network 10 (base station 200) transmits a paging message. The UE 100 receives the paging message from the base station 200 in its cell. The UE 100 determines whether or not its own unique identifier is included in the paging message. If its own unique identifier is included in the paging message, the UE 100 assumes that a call has been made and performs an operation to transition to, for example, an RRC connected state. On the other hand, if its own unique identifier is not included in the paging message, the UE 100 may transition to, for example, a sleep state.

[0052] Now, assume a case where, in the above-mentioned step S11, a paging subgroup is calculated using formula E13 from the UE_ID calculated using the formula "UE_ID=5G-S-TMSI mod 1024" specified in the current 3GPP technical specifications. Here, the maximum values ​​of N, Ns, and Nsg that can be set as N specified in the current 3GPP technical specifications are 256, 4, and 8, respectively. Therefore, there is a possibility that the condition "N*Ns*Nsg>1024" is satisfied. If this condition is satisfied, for example, when N is 256 and Ns is 4, all user equipments assigned to the same paging occasion will belong to the same paging subgroup, and an appropriate paging subgroup ID cannot be assigned to each UE 100.

[0053] Furthermore, when the UE_ID is calculated using the formula "UE_ID=5G-S-TMSI mod 1024*Nsg," the number of UE_IDs increases compared to the calculation method using "UE_ID=5G-S-TMSI mod 1024" defined in the current 3GPP technical specifications, and therefore the number of bits required to represent the UE_ID increases. As a result, for example, when transmitting the UE_ID between base stations, there is a problem in that the amount of information in the UE_ID increases. In one embodiment described below, an operation for making it possible to suppress the increase in the amount of information in the UE_ID will be described.

[0054] (Configuration of user device) The configuration of the UE 100 according to the embodiment will be described with reference to Fig. 6. The UE 100 includes a communication unit 110 and a control unit 120.

[0055] The communication unit 110 performs wireless communication with the base station 200 by transmitting and receiving radio signals to and from the base station 200. The communication unit 110 has at least one transmission unit 111 and at least one reception unit 112. The transmission unit 111 and the reception unit 112 may be configured to include multiple antennas and RF circuits. The antenna converts a signal into radio waves and radiates the radio waves into space. The antenna also receives radio waves in space and converts the radio waves into a signal. The RF circuit performs analog processing of the signal transmitted and received via the antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0056] The control unit 120 performs various controls in the UE 100. The control unit 120 controls communication with the base station 200 via the communication unit 110. The operations of the UE 100 described above and below may be controlled by the control unit 120. The control unit 120 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 120. The control unit 120 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. The memory may include at least one of a read-only memory (ROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), a random access memory (RAM), and a flash memory. All or a part of the memory may be included in the processor.

[0057] In the UE 100 configured as described above, the control unit 120 calculates a PO at which the UE 100 may receive a paging message, based on the UE_ID, when the UE 100 is in an RRC idle state or an RRC inactive state. The receiving unit 112 receives a paging message in a cell in which the UE 100 is located from the base station 200 that manages the cell, using the calculated PO. The control unit 120 selects one of a first calculation formula or a second calculation formula based on whether a paging subgroup to which some of the multiple UEs 100 assigned to the same paging occasion belong is set for the UE 100, and calculates the UE_ID using the selected calculation formula. The number of bits required to represent the UE_ID calculated using the second calculation formula is shorter than the number of bits required to represent the UE_ID calculated using the first calculation formula. As a result, when the UE 100 (control unit 120) selects the second calculation formula, the number of bits required to transmit the UE_ID is smaller than when the first calculation formula is selected, and an increase in the amount of UE_ID information can be suppressed.

[0058] (Base station configuration) The configuration of the base station 200 according to the embodiment will be described with reference to Fig. 7. The base station 200 includes a communication unit 210, a network interface 220, and a control unit 230.

[0059] The communication unit 210 receives a radio signal from the UE 100 and transmits the radio signal to the UE 100, for example. The communication unit 210 has at least one transmission unit 211 and at least one reception unit 212. The transmission unit 211 and the reception unit 212 may be configured to include an RF circuit. The RF circuit performs analog processing of a signal transmitted and received via an antenna. The RF circuit may include a high-frequency filter, an amplifier, a modulator, a low-pass filter, etc.

[0060] The network interface 220 transmits and receives signals to and from the network. For example, the network interface 220 receives signals from adjacent base stations connected via an Xn interface, which is an interface between base stations, and transmits signals to the adjacent base stations. The network interface 220 also receives signals from the core network device 300 connected via an NG interface, and transmits signals to the core network device 300.

[0061] The control unit 230 performs various controls in the base station 200. The control unit 230 controls, for example, communication with the UE 100 via the communication unit 210. The control unit 230 also controls, for example, communication with a node (e.g., a neighboring base station, the core network device 300) via the network interface 220. The operations of the base station 200 described above and below may be operations controlled by the control unit 230. The control unit 230 may include at least one processor capable of executing a program and a memory that stores the program. The processor may execute the program to perform the operations of the control unit 230. The control unit 230 may include a digital signal processor that performs digital processing of signals transmitted and received via the antenna and the RF circuit. The digital processing includes processing of a protocol stack of the RAN. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. All or a part of the memory may be included in the processor.

[0062] The base station 200 configured as described above manages a cell in which the UE 100 is located. When the UE 100 is in an RRC idle state or an RRC inactive state, the control unit 230 calculates a PO at which the UE 100 may receive a paging message, based on the UE_ID. The transmission unit 211 transmits a paging message to the UE 100 in the cell using the calculated PO. The control unit 230 selects one of a first calculation formula or a second calculation formula based on whether a paging subgroup to which some of the multiple UEs 100 assigned to the same PO belong is set for the UE 100, and calculates the UE_ID using the selected calculation formula. The number of bits required to represent the UE_ID calculated using the second calculation formula is shorter than the number of bits required to represent the UE_ID calculated using the first calculation formula. As a result, when the second calculation formula is selected, the number of bits required to transmit the UE_ID is smaller than when the first calculation formula is selected, and an increase in the amount of UE_ID information can be suppressed.

[0063] The UE_ID is transmitted, for example, from the base station 200 where the RAN paging is triggered to another base station 200 by a RAN paging message via the Xn interface.

[0064] (Mobile communication system operation) (1) First operation example A first operation example of the mobile communication system 1 will be described with reference to Figures 8 to 10. Differences from the above operation examples will be mainly described.

[0065] 8, in step S101, the base station 200 (transmitter 211) transmits Nsg information indicating the number of paging subgroups (Nsg) in a cell managed by the base station 200. The base station 200 (transmitter 211) may transmit, for example, a system information block (SIB) including the Nsg. The UE 100 (receiver 112) receives the Nsg information in the cell in which the UE 100 is located.

[0066] In step S102, the UE 100 (control unit 120) calculates a user equipment identity (UE_ID). Specifically, the UE 100 (control unit 120) selects one of a first calculation formula and a second calculation formula, which will be described later, based on whether a paging subgroup to which some of the multiple UEs 100 assigned to the same PO belong is set for the UE 100. The UE 100 (control unit 120) calculates the UE_ID using the selected calculation formula. FIG. 9 shows an example of the operation of the UE 100.

[0067] As shown in Fig. 9, in step S121, UE 100 (control unit 120) determines whether a paging subgroup (PSG) has been set for UE 100. UE 100 (control unit 120) may determine that a PSG has been set for UE 100 in at least one of the following cases. Note that the setting of the paging subgroup may be a setting for UE 100 (control unit 120) to monitor PDCCH monitoring opportunities (i.e., monitor paging) (see Fig. 10).

[0068] First, when the network 10 (base station 200) notifies the UE 100 of the Nsg, the UE 100 (control unit 120) may determine that the PSG has been set in the UE 100. Therefore, when the UE 100 (control unit 120) receives the Nsg information in the cell in which the UE 100 is located, the UE 100 (control unit 120) may determine that the PSG has been set in the UE 100.

[0069] Second, when the UE 100 (control unit 120) receives information regarding the setting of a paging subgroup from the network 10 (base station 200), the UE 100 (control unit 120) may determine that a PSG has been set in the UE 100. For example, when the UE 100 (control unit 120) receives information indicating that a paging subgroup is determined by the second grouping method, the UE 100 (control unit 120) may determine that a PSG has been set in the UE 100.

[0070] When the UE 100 (control unit 120) determines that the PSG is set in the UE 100, the UE 100 executes the process of step S122. On the other hand, when the UE 100 (control unit 120) determines that the PSG is not set in the UE 100, the UE 100 executes the process of step S123.

[0071] In step S122, the UE 100 (control unit 120) selects a first calculation formula, and calculates the UE_ID using the selected first calculation formula.

[0072] For example, the first calculation formula is "UE_ID = user equipment unique identifier mod Y". The unique identifier of the user equipment is, for example, 5G-S-TMSI. Y may be a fixed value obtained by multiplying 1024 by the maximum number of configurable PSGs specified in the technical specifications of the mobile communication system 1. In the current technical specifications of 3GPP, the maximum number of configurable PSGs is 8. For example, as shown in FIG. 10 , the UE 100 (control unit 120) calculates the UE_ID using formula E21A as the first calculation formula. In formula E21A, the fixed value is 8192 (=1024×8). Note that the fixed value may be any value greater than N*Ns*Nsg.

[0073] In step S123, the UE 100 (control unit 120) selects the second calculation formula, and calculates the UE_ID using the selected second calculation formula.

[0074] For example, as shown in FIG. 10, the second calculation formula is formula E21B, which is "UE_ID = 5G-S-TMSI mod 1024" defined in the current 3GPP technical specifications.

[0075] The number of bits required to represent the UE_ID calculated by the second calculation formula is shorter than the number of bits required to represent the UE_ID calculated by the first calculation formula. In this operation example, the UE_ID calculated by the second calculation formula is represented by 10 bits (=log2(1024)), whereas the UE_ID calculated by the first calculation formula is represented by 13 bits (=log2(8192)).

[0076] 8, in step S103, UE 100 (control unit 120) calculates PF, PO, and PSG. For example, UE 100 (control unit 120) calculates PF using equation E11, calculates PO using equation E12, and calculates PSG using equation E13.

[0077] Steps S104 and S105 are the same as steps S13 and S14. Note that base station 200 (control unit 230) calculates UE_ID, PF, PO, and PSG in the same way as UE 100. Base station 200 (control unit 230, transmission unit 211) performs a paging transmission operation based on the calculated UE_ID, PF, PO, and PSG.

[0078] Specifically, when paging addressed to a UE 100 is triggered, the base station 200 (control unit 230) calculates the UE_ID of the UE 100 and calculates a PSG (paging subgroup ID) based on the calculated UE_ID. Before transmitting a paging message, the base station 200 (transmission unit 211) notifies each UE 100 of the calculated paging subgroup ID. Thereafter, the base station 200 (transmission unit 211) transmits a paging message including a unique identifier of the UE 100.

[0079] As described above, UE100 (control unit 120) calculates UE_ID using equation E21A (UE_ID = 5G-S-TMSI mod 8192), and therefore, even if the equation "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from UE_ID, all UE100 assigned to the same paging occasion do not belong to the same PSG, and therefore an appropriate paging subgroup ID is assigned to each UE100.

[0080] When PSG is not set in UE100, UE100 (control unit 120) selects the second calculation formula, so the number of bits required to transmit the UE_ID is smaller than when the first calculation formula is selected, and the increase in the amount of information for the UE_ID can be suppressed.

[0081] Furthermore, the first calculation formula is "UE_ID = user equipment unique identifier mod Y", where Y is a fixed value obtained by multiplying 1024 by the maximum number of PSGs that can be set, as defined in the technical specifications of the mobile communication system 1. This simplifies the process for calculating the UE_ID, as the UE 100 (control unit 120) can omit, for example, management of the variable value, compared to when Y is a variable value (e.g., Nsg) that can be changed for each cell.

[0082] (2) Second operation example The second operation example will be described, mainly focusing on differences from the above-described operation example, with reference to Figures 11 and 12. In the second operation example, the UE 100 selects the first calculation formula when the condition "N*Ns*Nsg > threshold" is satisfied, and selects the second calculation formula when the condition is not satisfied.

[0083] 11, step S221 is the same as step S121. When UE 100 (control unit 120) determines that a PSG has been set in UE 100, it executes the process of step S222. On the other hand, when UE 100 (control unit 120) determines that a PSG has not been set in UE 100, it executes the process of step S223.

[0084] In step S222, the UE 100 (control unit 120) determines whether or not the condition "N*Ns*Nsg>threshold" is satisfied.

[0085] The threshold is a value obtained by multiplying the maximum value of the total PF that can be set as N, as defined in the technical specifications of the mobile communication system 1, by the maximum value of PO that can be set as Ns, as defined in the technical specifications of the mobile communication system 1. In the current 3GPP technical specifications, the maximum value of the total PF that can be set as N is 256, and the maximum value of PO that can be set as Ns is 4. Therefore, as shown in FIG. 12, the threshold is 1024 (=256×4), and the condition is "N*Ns*Nsg>1024."

[0086] If the condition is satisfied, the UE 100 (control unit 120) executes the process of step S223. On the other hand, if the condition is not satisfied, the UE 100 (control unit 120) executes the process of step S224.

[0087] In step S223, the UE 100 (control unit 120) selects, for example, formula E22A as the first calculation formula, as shown in Fig. 12. In this operation example, formula E22A is the same as formula E21A.

[0088] In step S224, the UE 100 (control unit 120) selects, for example, formula E22B as the second calculation formula, as shown in Fig. 12. In this operation example, formula E22B is the same as formula E21B.

[0089] As described above, when the condition "N*Ns*Nsg > 1024" is satisfied, UE100 (control unit 120) calculates the UE_ID using formula E22A (UE_ID = 5G-S-TMSI mod 8192), and even if the formula "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from the UE_ID, all UE100 assigned to the same paging occasion do not belong to the same PSG, so an appropriate paging subgroup ID is assigned to each UE100.

[0090] Furthermore, if the condition "N*Ns*Nsg > 1024" is not satisfied, UE100 (control unit 120) selects the second calculation formula even if a PSG is set in UE100. Therefore, compared to when the first calculation formula is selected, the number of bits required to transmit the UE_ID is smaller, and the increase in the amount of information for the UE_ID can be suppressed.

[0091] (3) Third operation example With reference to Fig. 13, the third operation example will be described, focusing on differences from the above-mentioned operation examples. In the third operation example, UE 100 (control unit 120) selects a first calculation formula different from that in the above-mentioned operation examples. The flowchart of UE 100 (control unit 120) in this operation example is the same as that in the second operation example.

[0092] In step S223, the UE 100 (control unit 120) selects, for example, formula E23A as the first calculation formula, as shown in Fig. 13. In this operation example, formula E23A is "UE_ID = unique identifier of user equipment mod Z", where Z is a value obtained by multiplying 1024 by Nsg.

[0093] In step S224, the UE 100 (control unit 120) selects, for example, formula E23B as the second calculation formula, as shown in Fig. 13. In this operation example, formula E23B is the same as formula E21B.

[0094] As described above, when the condition "N*Ns*Nsg > 1024" is satisfied, UE100 (control unit 120) calculates the UE_ID using equation E23A, and even if the equation "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from the UE_ID, all UE100 assigned to the same paging occasion do not belong to the same PSG, so an appropriate paging subgroup ID is assigned to each UE100.

[0095] Furthermore, by calculating the UE_ID using equation E23A, when Nsg is smaller than 8, UE100 (control unit 120) reduces the number of bits required to transmit the UE_ID compared to when equation 21A or equation 22A is used, thereby suppressing an increase in the amount of information in the UE_ID.

[0096] Furthermore, if the condition "N*Ns*Nsg > 1024" is not satisfied, UE100 (control unit 120) selects the second calculation formula even if a PSG is set in UE100. Therefore, compared to when the first calculation formula is selected, the number of bits required to transmit the UE_ID is smaller, and the increase in the amount of information for the UE_ID can be suppressed.

[0097] (Other embodiments) In the above-described embodiment, the second calculation formula is "UE_ID = 5G-S-TMSI mod 1024" defined in the current 3GPP technical specifications, but may be another calculation formula.

[0098] The operational sequences (and operational flows) in the above-described embodiments do not necessarily have to be executed in chronological order according to the order depicted in the flow diagrams or sequence diagrams. For example, the steps in the operations may be executed in an order different from that depicted in the flow diagrams or sequence diagrams, or may be executed in parallel. Some of the steps in the operations may be deleted, or additional steps may be added to the processing. The operational sequences (and operational flows) in the above-described embodiments may be executed independently, or two or more operational sequences (and operational flows) may be executed in combination. For example, some steps in one operational flow may be added to another operational flow, or some steps in one operational flow may be replaced with some steps in another operational flow.

[0099] In the above-described embodiment, an NR-based mobile communication system has been described as an example of the mobile communication system 1. However, the mobile communication system 1 is not limited to this example. The mobile communication system 1 may be a system compliant with a TS of any of LTE (Long Term Evolution) or other generation systems (e.g., 6th generation) of the 3GPP standard. The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol termination for the UE 100 in LTE. The mobile communication system 1 may be a system compliant with a TS of a standard other than the 3GPP standard. The base station 200 may be an IAB (Integrated Access and Backhaul) donor or an IAB node.

[0100] A program may be provided that causes a computer to execute each process performed by UE 100 or base station 200. The program may be recorded in a computer-readable medium. Using the computer-readable medium, the program can be installed in a computer. Here, the computer-readable medium on which the program is recorded may be a non-transitory recording medium. The non-transitory recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disk Read Only Memory). Furthermore, circuits that execute each process performed by UE 100 or base station 200 may be integrated, and at least a part of UE 100 or base station 200 may be configured as a semiconductor integrated circuit (chip set, SoC (System On Chip)).

[0101] In the above embodiments, "transmit" may mean processing at least one layer in a protocol stack used for transmission, or may mean physically transmitting a signal wirelessly or via a wired connection. Alternatively, "transmit" may mean a combination of processing at least one layer and physically transmitting a signal wirelessly or via a wired connection. Similarly, "receive" may mean processing at least one layer in a protocol stack used for reception, or may mean physically receiving a signal wirelessly or via a wired connection. Alternatively, "receive" may mean a combination of processing at least one layer and physically receiving a signal wirelessly or via a wired connection. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from another node, or obtaining information by generating information. Similarly, the terms "based on" and "depending on / in response to" do not mean "based only on" or "depending only on," unless otherwise specified. The phrase "based on" means both "based only on" and "based at least in part on." Similarly, the phrase "depending on" means both "depending only on" and "depending at least in part on." Similarly, "include" and "comprise" do not mean including only the listed items, but may mean including only the listed items or may include additional items in addition to the listed items. Similarly, in this disclosure, "or" does not mean an exclusive or, but does mean a logical or. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not generally limit the quantity or order of those elements. These designations may be used in this disclosure as a convenient method of distinguishing between two or more elements.Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall include the plural unless the context clearly indicates otherwise.

[0102] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0103] (Addendum) The following additional notes are about the features of the above-described embodiment.

[0104] (Appendix 1) a receiving unit configured to receive from a network first information indicating a number of subgroups per paging occasion and second information regarding configuration of the subgroups based on a user equipment identity (UE_ID); a control unit that calculates the UE_ID using a predetermined calculation formula based on the first information and the second information, and calculates a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula, The receiver monitors paging occasions based on the subgroup identifier. Communication equipment.

[0105] (Appendix 2) The predetermined calculation formula is a formula based on a temporary mobile subscription identifier 5G-S-TMSI. 2. The communication device of claim 1.

[0106] (Appendix 3) the predetermined calculation formula is a first calculation formula, The control unit calculating the UE_ID using a second calculation formula different from the first calculation formula based on the fact that the second information has not been received; monitoring paging occasions based on the UE_ID calculated using the second calculation formula; 3. The communication device according to claim 1 or 2.

[0107] (Appendix 4) The second calculation formula is based on a temporary mobile subscription identifier (5G-S-TMSI). 4. The communications device of claim 3.

[0108] (Appendix 5) a transmitter configured to transmit to a communication device first information indicating a number of subgroups per paging occasion and second information regarding configuration of the subgroups based on a user equipment identity (UE_ID); a control unit that calculates the UE_ID using a predetermined calculation formula based on the first information and the second information, and calculates a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula, The transmitter transmits downlink control information on a physical link control channel at a paging occasion based on the subgroup identifier. Base station.

[0109] (Appendix 6) 1. A communication method performed in a communication device, comprising: receiving from a network first information indicating a number of subgroups per paging occasion and second information regarding configuration of the subgroups based on a user equipment identity (UE_ID); calculating the UE_ID using a predetermined calculation formula based on the first information and the second information, and calculating a subgroup identifier based on the UE_ID calculated using the predetermined calculation formula; and monitoring paging occasions based on the subgroup identifier. Communication method.

Claims

1. A communication device (100), a receiver (112) for receiving a paging message from a base station (200) at a paging occasion; a control unit (120) for calculating a user equipment identity (UE_ID); The control unit (120) calculating a first UE_ID as the UE_ID using a first equation that modifies a unique identifier of the communication device by a first value based on the communication device receiving first information indicating a number of subgroups per paging occasion and second information for configuring UE_ID-based subgrouping, and monitoring the paging occasions based on the first UE_ID calculated using the first equation; calculating a second UE_ID as the UE_ID using a second equation that modulates a unique identifier of the communication device by a second value based on the communication device not receiving the second information, and monitoring the paging occasions based on the second UE_ID calculated using the second equation; The first value is greater than the second value. A communication device (100).

2. The receiver receives information associated with a subgroup identifier of the paging occasion from the base station; the control unit monitors the paging occasion based on a subgroup identifier based on the first UE_ID calculated using the first equation and information associated with the subgroup identifier, based on the communication device receiving the first information and the second information. The communication device according to claim 1 .

3. The unique identifier of the communication device is a 5G-S-TMSI (Temporary Mobile Subscriber Identifier), The subgroup identifier based on the UE_ID calculated using the first equation is based on the number of subgroups per paging occasion, the number of paging occasions relative to a paging frame, and the total number of paging frames within a discontinuous reception (DRX) cycle of the communication device. The communication device according to claim 2 .

4. the first value is 8192; The second value is 1024 3. The communication device according to claim 1.

5. A base station (200), a transmitter (211) for transmitting a paging message to a communication device at a paging occasion; a control unit (230) for calculating a user equipment identity (UE_ID); The control unit (230) based on the base station transmitting to the communication device first information for indicating the number of subgroups per paging occasion and second information for configuring UE_ID-based subgrouping, controlling the communication device to monitor the paging occasions based on a first UE_ID calculated as the UE_ID using a first equation modulating a unique identifier of the communication device by a first value; based on the base station not transmitting the second information to the communication device, controlling the communication device to monitor the paging occasions according to a second UE_ID calculated as the UE_ID using a second equation modulating a unique identifier of the communication device by a second value; The first value is greater than the second value. Base station.

6. The method of claim 1, wherein the transmitting unit transmits information associated with a subgroup identifier of the paging occasion to the communication device; the control unit controls the communication device to monitor the paging occasion based on a subgroup identifier based on the first UE_ID calculated using the first equation and information associated with the subgroup identifier, based on the communication device receiving the first information and the second information. The base station according to claim 5.

7. The unique identifier of the communication device is a 5G-S-TMSI (Temporary Mobile Subscriber Identifier), The subgroup identifier based on the first UE_ID calculated using the first formula is based on the number of subgroups per paging occasion, the number of paging occasions for a paging frame, and the total number of paging frames within a discontinuous reception (DRX) cycle of the communication device. The base station of claim 6.

8. the first value is 8192; The second value is 1024 The base station according to claim 5 or claim 6.

9. A communication method executed by a communication device (100), comprising: receiving a paging message from a base station (200) at a paging occasion; calculating a first User Equipment Identity (UE_ID) as a UE_ID using a first formula modulating a unique identifier of the communication device by a first value based on the communication device receiving first information indicating a number of subgroups per paging occasion and second information for configuring UE_ID-based subgrouping, and monitoring the paging occasions based on the first UE_ID calculated using the first formula; calculating a second UE_ID as the UE_ID using a second equation that modulates a unique identifier of the communication device by a second value based on the communication device not receiving the second information, and monitoring the paging occasion based on the second UE_ID calculated using the second equation; The first value is greater than the second value. Communication method.

10. The method of claim 1, further comprising: receiving information associated with a subgroup identifier of the paging occasion from the base station; and monitoring the paging occasion based on a subgroup identifier based on the first UE_ID calculated using the first formula and information associated with the subgroup identifier, based on the communication device receiving the first information and the second information. The communication method according to claim 9.

11. The unique identifier of the communication device is a 5G-S-TMSI (Temporary Mobile Subscriber Identifier), The subgroup identifier based on the first UE_ID calculated using the first formula is based on the number of subgroups per paging occasion, the number of paging occasions for a paging frame, and the total number of paging frames within a discontinuous reception (DRX) cycle of the communication device. The communication method according to claim 10.

12. The method of claim 1, wherein the first value is 8192; The second value is 1024 The communication method according to claim 9 or 10.

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