Communication equipment, 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 Patent Application No. 2023-542438 filed on August 18, 2022, claims the benefit of its priority, and all the contents of that patent application are incorporated herein by reference.

Technical Field

[0002] This disclosure relates to a communication device, a base station, and a communication method used in a mobile communication system.

Background Art

[0003] In 3GPP (registered trademark; the same shall apply hereinafter) (3rd Generation Partnership Project), which is a standardization project for mobile communication systems, discussions have been carried out to reduce power consumption for communication devices in the RRC (Radio Resource Control) idle state or RRC inactive state (see Non-Patent Document 1). Specifically, it has been considered to introduce a mechanism for classifying each of a plurality of communication devices assigned to the same paging opportunity into any of a plurality of 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 that is the destination of the paging message belongs. A communication device in the RRC idle state or RRC inactive state performs the reception process of the paging message (specifically, reception and decoding of a physical downlink shared channel) and determines whether its own unique identifier is included in the paging message only when it determines that it belongs to the notified paging subgroup. On the other hand, when a communication device determines that it does not belong to the notified paging subgroup, it can skip the reception process of the paging message during the paging opportunity, thereby reducing power consumption.

[0005] One proposed method for determining the paging subgroup to which a communication device belongs is one 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 device identity (UE identity: UE ID) from its own unique identifier, and then calculates the paging subgroup to which it belongs (specifically, the paging subgroup ID (UE subgroup ID)) from the calculated user device identity. The formula proposed for calculating the paging subgroup identifier from the user device identity is "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg". N is the total number of paging frames (PFs) in the communication device's discontinuous receive (DRX) cycle, 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 we calculate the paging subgroup using the above formula from the user device identity calculated using the formula "UE_ID=5G-S-TMSI mod 1024" specified in the current 3GPP technical specifications, then if the condition "N*Ns*Nsg > 1024" is met, all communication devices assigned to the same paging opportunity will belong to the same paging subgroup. Therefore, Non-Patent Literature 2 describes calculating the user device 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 [Overview of the project]

[0008] A communication device according to the first embodiment includes a receiving unit that receives from a network first information indicating the number of subgroups per paging opportunity and second information relating to the setting of the subgroups based on a user device identity (UE_ID), and 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 receiving unit monitors paging opportunities based on the subgroup identifier.

[0009] A base station according to the second embodiment includes a transmitting unit that transmits to a communication device first information indicating the number of subgroups per paging opportunity and second information relating to the setting of the subgroups based on a user device identity (UE_ID), and 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 transmitting unit transmits downlink control information on a physical link control channel in a paging opportunity based on the subgroup identifier.

[0010] The third aspect of the communication method is a communication method performed by a communication device. The communication method includes the steps of: receiving from a network first information indicating the number of subgroups per paging opportunity and second information relating to the setting of the subgroups based on a user device 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 opportunities based on the subgroup identifier. [Brief explanation of the drawing]

[0011] The purpose, features, and advantages of this disclosure will become clearer with reference to the attached drawings and the detailed description below. [Figure 1] Figure 1 is a diagram showing the configuration of a mobile communication system according to an embodiment. [Figure 2] Figure 2 shows an example of the protocol stack configuration in a mobile communication system according to the embodiment. [Figure 3] Figure 3 shows paging subgrouping. [Figure 4] Figure 4 shows an example of operation for a UE in an RRC idle or RRC inactive state. [Figure 5] Figure 5 is a diagram illustrating an example of the formulas used to calculate PF, PO, and SFN. [Figure 6] Figure 6 shows the configuration of the UE according to the embodiment. [Figure 7] Figure 7 shows the configuration of a base station according to this embodiment. [Figure 8] Figure 8 is a sequence diagram illustrating a first operation example according to one embodiment. [Figure 9] Figure 9 is a flowchart illustrating a first operation example according to one embodiment. [Figure 10] Figure 10 is a diagram illustrating an example of a formula for calculating the user device identity in a first operation example according to one embodiment. [Figure 11] Figure 11 is a flowchart illustrating a second and third operation example according to one embodiment. [Figure 12] Figure 12 is a diagram illustrating an example of a formula for calculating the user device identity in a second operation example according to one embodiment. [Figure 13] Figure 13 is a diagram illustrating an example of a formula for calculating the user device identity in a third operation example according to one embodiment. [Modes for carrying out the invention]

[0012] A mobile communication system according to an embodiment will be described while referring 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 the user equipment identity by the formula described in Non-Patent Document 2, compared with the calculation method by the formula defined in the current 3GPP technical specification, the number of user equipment identities increases, so the number of bits required to indicate the user equipment identity increases. As a result, for example, when transmitting the user equipment identity between base stations, there is a problem that the amount of information of the user equipment identity increases. Therefore, one of the purposes of the present disclosure is to provide a communication device, a base station, and a communication method capable of suppressing an increase in the amount of information of the user equipment identity in a mobile communication system in which each of a plurality of communication devices assigned to the same paging opportunity can be classified into any of a plurality of paging subgroups.

[0014] (Configuration of Mobile Communication System) Referring to FIG. 1, the configuration of the mobile communication system 1 according to the embodiment will be described. The mobile communication system 1 is a system compliant with, for example, the 3GPP technical specification (Technical Specification: TS). Hereinafter, as the mobile communication system 1, a 5th generation system (5th Generation System: 5GS) of the 3GPP standard, that is, a mobile communication system based on NR (New Radio) will be described as an example.

[0015] The mobile communication system 1 includes a network 10 and a user equipment (UE) 100 that communicates with the network 10. The network 10 includes an NG-RAN (Next Generation Radio Access Network) 20 that is a 5G radio access network and a 5GC (5G Core Network) 30 that is a 5G core network.

[0016] UE100 is an example of a communication device. It is an example of a communication device. UE100 may be a mobile wireless communication device. UE100 may be a device used by a user. UE100 is a movable device such as, for example, a mobile phone terminal such as a smartphone, a tablet terminal, a notebook PC, a communication module, or a communication card. UE100 may be a vehicle (e.g., a car, a train, etc.) or a device provided therein (e.g., a Vehicle UE). UE100 may be a transport aircraft other than a vehicle (e.g., a ship, an airplane, a flying object, etc.) or a device provided therein. UE100 may be a sensor or a device provided therein. Note that UE100 may be called by another name 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] NG-RAN20 includes a plurality of base stations 200. Each base station 200 manages at least one cell. A cell constitutes the minimum 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 represent a wireless communication resource and may also represent a communication target of UE100. Each base station 200 can perform wireless communication with UE100 located in its cell. The base station 200 communicates with UE100 using the RAN protocol stack. The base station 200 provides an NR user plane and control plane protocol termination towards UE100 and is connected to 5GC30 via the NG interface. Such an NR base station 200 may be referred to as a gNodeB (gNB).

[0018] 5GC30 includes a core network device 300. The core network device 300 includes, for example, an AMF (Access and Mobility Management Function) and / or a UPF (User Plane Function). The AMF manages the mobility of the UE100. The UPF provides functions specifically for user plane processing. The AMF and UPF are connected to the base station 200 via an NG interface.

[0019] Referring to Figure 2, an example of the protocol stack configuration in the mobile communication system 1 according to this embodiment will be described.

[0020] The protocol for the radio section between UE100 and base station 200 has a physical (PHY) layer, a MAC (Medium Access Control) layer, an RLC (Radio Link Control) layer, a PDCP (Packet Data Convergence Protocol) layer, and an RRC (Radio Resource Control) layer.

[0021] The PHY layer performs coding and decoding, modulation and demodulation, antenna mapping and demapping, and resource mapping and demapping. Data and control information are transmitted between the PHY layer of UE100 and the PHY layer of base station 200 via a physical channel.

[0022] A physical channel consists of multiple OFDM (Orthogonal Frequency Division Multiplexing) symbols in the time domain and multiple subcarriers in the frequency domain. A single 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 consist of 10ms and may contain 10 subframes, each consisting of 1ms. A subframe may contain a number of slots corresponding to the subcarrier spacing.

[0023] Within the physical channels, the physical downlink control channel (PDCCH) plays a central role for purposes such as downlink scheduling allocation, uplink scheduling grant, and transmit power control.

[0024] In NR, UE100 can use a bandwidth narrower than the system bandwidth (i.e., the cell bandwidth). Base station 200 configures UE100 with a bandwidth portion (BWP) consisting of consecutive PRBs. UE100 transmits and receives data and control signals in the active BWP. Up to four BWPs can be configured for UE100, for example. Each BWP may have a different subcarrier spacing, and their frequencies may overlap. If multiple BWPs are configured for UE100, base station 200 can specify which BWP to activate by downlink control. This allows base station 200 to dynamically adjust the UE bandwidth according to the amount of data traffic on UE100, potentially reducing UE power consumption.

[0025] The base station 200 can configure, for example, up to three control resource sets (CORESETs) for each of up to four BWPs on a serving cell. A CORESET is a radio resource for control information that the UE 100 should receive. The UE 100 may have up to 12 CORESETs configured on a serving cell. Each CORESET has an index from 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), and random access procedures. Data and control information are transmitted between the MAC layer of UE100 and the MAC layer of base station 200 via the transport channel. The MAC layer of base station 200 includes a scheduler. The scheduler determines the transport format for the uplink and downlink (transport block size, modulation coding scheme (MCS)) and the resources to be allocated to UE100.

[0027] The RLC layer transmits data to the receiving RLC layer by utilizing the functions of the MAC layer and PHY layer. Data and control information are transmitted between the RLC layer of UE100 and the RLC layer of base station 200 via a logical channel.

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

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

[0030] The RRC layer controls the logical channel, transport channel, and physical channel in response to the establishment, re-establishment, and release of the radio bearer. RRC signaling for various settings is transmitted between the RRC layer of UE100 and the RRC layer of base station 200. If there is an RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC connected state. If there is no RRC connection between the RRC of UE100 and the RRC of base station 200, UE100 is in the RRC idle state. If the RRC connection between the RRC of UE100 and the RRC of base station 200 is suspended, UE100 is in the RRC inactive state.

[0031] The NAS layer, located above the RRC layer, handles session management and mobility management for the UE100. NAS signaling is transmitted between the UE100's NAS layer and the core network device 300 (AMF)'s NAS layer. The UE100 also has application layers and other components in addition to its wireless interface protocol.

[0032] (Assumed scenario) A hypothetical scenario in the mobile communication system 1 according to this embodiment will be described with reference to Figures 3 to 5.

[0033] Regarding paging reception, the paging message transmitted by network 10 (base station 200) includes the identifier of each UE 100 invoked by network 10.

[0034] When UE100 is in an RRC idle or RRC inactive state, it intermittently monitors paging using Discontinuous Reception (DRX) to reduce power consumption. The period during which such paging is monitored is called the DRX cycle. The frame that UE100 should monitor for paging is called a paging frame (PF), and the subframe within this PF that UE100 should monitor for paging is called a paging opportunity (PO). In a PO, UE100 may receive a paging message.

[0035] UE100 in the RRC idle or RRC inactive state wakes up at PO to monitor paging messages and performs paging message reception processing (specifically, receiving and decoding the physical downlink shared channel (PDSCH)). After performing reception processing, UE100 determines whether its own unique identifier is included in the paging message. If its identifier is included in the paging message, UE100 considers it to have received a call and performs an action such as transitioning to the RRC connected state.

[0036] In this way, during paging reception, all UE100s assigned the same PO wake up at that PO to monitor paging and process the reception of paging messages. A group of UEs assigned the same PO is called a paging group. Here, however, UE100s that are not actually called from network 10 also wake up and process the reception of paging messages, resulting in extra power consumption.

[0037] Therefore, each of the multiple UE100s assigned to the same PO is classified (i.e., grouped) into one of several subgroups smaller than the paging group (hereinafter referred to as paging subgroups (PSGs)). Figure 3 shows an example in which a paging group is divided into three paging subgroups with paging subgroup IDs "#1" to "#3". While this example shows three UE100s belonging to each paging subgroup, the number of UE100s belonging to each paging subgroup may be one, two, or four or more.

[0038] Two methods are being considered for grouping each UE100 assigned to the same PO: a first grouping method in which network 10 assigns a paging subgroup ID to each UE100 (so-called CN-assigned subgrouping), and a second grouping method in which the UE100 itself determines the paging subgroup (so-called UE_ID based subgrouping).

[0039] In the first grouping method, the assignment of a paging subgroup ID to each UE100 may be performed, for example, when the UE100 is registered with the network. The network 10 assigns the paging subgroup ID according to the characteristics of the UE100 (e.g., paging probability, power consumption profile, and / or mobility status).

[0040] In the second grouping method, UE100 determines the paging subgroup based on its own unique identifier (e.g., 5G-S-TMSI (Temporary Mobile Subscriber Identifier)). Specifically, UE100 calculates the user device identity (UE identity: UE ID) from its own unique identifier, and then calculates the paging subgroup to which it belongs (specifically, the paging subgroup ID (UE subgroup ID)) from the calculated user device identity. The formula proposed for calculating the paging subgroup identifier from the user device identity is "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg". N is the total number of PFs in the DRX cycle of UE100 in the 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 where UE100 is located) (see Figure 5). Note that 5G-S-TMS is a temporary mobile subscription identifier.

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

[0042] Each UE100 in an RRC idle or RRC inactive state will wake up at the PO and perform paging monitoring only if it is notified of the paging subgroup ID to which it belongs (i.e., it belongs to the notified paging subgroup). This prevents some UE100s belonging to paging subgroups from having to wake up at the PO, thereby suppressing unnecessary power consumption.

[0043] Furthermore, in order to notify each UE100 of the paging subgroup to which the recipient UE100 of the paging message belongs, network 10 (base station 200) may, for example, transmit downlink control information (DCI) via PDCCH that includes the paging subgroup ID to which the UE100 invoked in the paging message transmitted via PO belongs. UE100 receives (decodes) the DCI, which has been scrambled by P-RNTI (Paging Radio Network Temporary Identifier) ​​and has been supplemented with CRC (Cyclic Redundancy Check) parity bits, via PDCCH. Here, base station 200 may set P-RNTI for UE100. The DCI may also be in the DCI format used for scheduling physical downlink shared channels (PDSCH). The DCI with the CRC parity bits scrambled by P-RNTI is also called paging DCI.

[0044] Upon receiving (decoding) the PDCCH, UE100 determines that it belongs to the notified paging subgroup if the paging subgroup ID included in the DCI indicates the paging subgroup to which it belongs. Only if UE100 belongs to the notified paging subgroup does it perform the reception processing of the paging message (specifically, receiving and decoding the PDSCH) and determine whether its unique identifier is included in the paging message. If UE100 determines that it does not belong to the notified paging subgroup, it can skip the reception processing of the paging message during the paging opportunity, thereby reducing power consumption.

[0045] Figure 4 shows an example of the operation when UE100, which is in an RRC idle or RRC inactive state, determines a paging subgroup (the second grouping method described above). UE100 is located in a cell managed by base station 200. This cell may be one selected by UE100 through cell (re)selection and may be referred to as a camp-on cell.

[0046] In step S11, a UE100 that is in an RRC idle state or RRC inactive state determines its user device identity (UE identity: UE_ID) based on its own unique identifier.

[0047] In step S12, UE100 calculates (determines) the paging frame, paging opportunity, and paging subgroup.

[0048] As shown in Figure 5, UE100 calculates a paging frame (specifically, a system frame number (SFN) which is a paging frame) based on the calculated user device identity using equation E11. UE100 calculates a paging opportunity (specifically, an index of paging opportunities (i_s)) based on the calculated user device identity using equation E12. UE100 calculates a paging subgroup (PSG) based on the calculated user device identity using equation E13. The calculated paging subgroup is the paging subgroup to which UE100 belongs.

[0049] In step S13, before sending the 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 sent belongs. The UE 100 receives the paging subgroup ID from the base station 200 in the cell where the UE 100 is located.

[0050] UE100 determines whether it belongs to the notified paging subgroup. Specifically, UE100 determines whether it belongs to the notified paging subgroup if the calculated paging subgroup matches the notified paging subgroup ID. Otherwise, UE100 determines that it does not belong to the notified paging subgroup. UE100 performs the following processing only if it belongs to the notified paging subgroup. Therefore, UE100 maintains a wake-up state to receive paging messages from base station 200. On the other hand, if UE100 does not belong to the notified paging subgroup, it may transition to a sleep state without performing the following processing.

[0051] In step S14, network 10 (base station 200) sends a paging message. UE100 receives the paging message from base station 200 in the cell. UE100 determines whether its unique identifier is included in the paging message. If UE100 finds its unique identifier in the paging message, it considers a call to have been made and performs an action such as transitioning to the RRC connected state. On the other hand, if UE100 does not find its unique identifier in the paging message, it may transition to a sleep state, for example.

[0052] Incidentally, in step S11 described above, let's consider a case where the paging subgroup is calculated using formula E13 from the UE_ID calculated using the formula "UE_ID=5G-S-TMSI mod 1024" as defined in the current 3GPP technical specifications. Here, the maximum values ​​of N, Ns, and Nsg that can be set as N as defined in the current 3GPP technical specifications are 256, 4, and 8, respectively. Therefore, the condition "N*Ns*Nsg > 1024" may be met. If this condition is met, for example, if N is 256 and Ns is 4, all user devices assigned to the same paging opportunity will belong to the same paging subgroup, and it will not be possible to assign an appropriate paging subgroup ID to each UE100.

[0053] Furthermore, when calculating the UE_ID 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" specified in the current 3GPP technical specifications. As a result, the number of bits required to represent the UE_ID increases. Consequently, for example, when transmitting the UE_ID between base stations, there is a problem of increased information volume in the UE_ID. In one embodiment described later, an operation to suppress the increase in the amount of information volume in the UE_ID will be explained.

[0054] (User device configuration) Referring to Figure 6, the configuration of the UE100 according to this embodiment will be described. The UE100 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 transmitting unit 111 and at least one receiving unit 112. The transmitting unit 111 and the receiving unit 112 may be configured to include a plurality of antennas and RF circuits. The antennas convert signals into radio waves and radiate the radio waves into space. The antennas also receive radio waves in space and convert the radio waves into signals. The RF circuits perform analog processing of the signals transmitted and received via the antennas. The RF circuits may include high-frequency filters, amplifiers, modulators, and low-pass filters, etc.

[0056] The control unit 120 performs various controls on 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 operations controlled by the control unit 120. The control unit 120 may include at least one program-executable processor and memory for storing 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 RF circuit. This digital processing includes processing of the RAN protocol stack. The memory stores the program executed by the processor, parameters related to the program, and data related to the program. The memory may include at least one of ROM (Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), RAM (Random Access Memory), and flash memory. All or part of the memory may be contained within the processor.

[0057] In the UE100 configured in this way, the control unit 120 calculates a PO (Point of Presence) that the UE100 may receive a paging message from, based on the UE_ID, when the UE100 is in an RRC idle or RRC inactive state. The receiving unit 112 receives the paging message from the base station 200 managing the cell in which the UE100 is located, based on the calculated PO. The control unit 120 selects one of the first or second calculation formulas based on whether a paging subgroup to which some of the multiple UE100s assigned to the same paging opportunity belong is set for the UE100, and calculates the UE_ID using the selected formula. 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. As a result, when the UE100 (control unit 120) selects the second calculation formula, the number of bits required to transmit the UE_ID is smaller compared to when the first calculation formula is selected, and the increase in the amount of information in the UE_ID can be suppressed.

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

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

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

[0061] The control unit 230 performs various controls on the base station 200. For example, the control unit 230 controls communication with the UE 100 via the communication unit 210. The control unit 230 also controls communication with nodes (e.g., adjacent base stations, core network equipment 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 programs and a memory for storing programs. The processor may execute programs 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 RF circuit. This digital processing includes processing of the RAN protocol stack. The memory stores programs executed by the processor, parameters related to the programs, and data related to the programs. All or part of the memory may be contained within the processor.

[0062] The base station 200 configured in this way manages the cell in which the UE100 is located. The control unit 230 calculates the PO (Point of Presence) to which the UE100 may receive a paging message based on the UE_ID when the UE100 is in an RRC idle or RRC inactive state. The transmission unit 211 transmits a paging message to the UE100 in the cell using the calculated PO. The control unit 230 selects one of the first or second calculation formulas based on whether a paging subgroup to which some of the multiple UE100s assigned to the same PO belong is set for the UE100, and calculates the UE_ID using the selected formula. 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. As a result, when the second calculation formula is selected, the number of bits required to transmit the UE_ID is smaller compared to when the first calculation formula is selected, and the increase in the amount of information in the UE_ID can be suppressed.

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

[0064] (Operation of mobile communication systems) (1) First example of operation Referring to Figures 8 to 10, a first example of operation of the mobile communication system 1 will be described. The main points to be explained are the differences from the operation example described above.

[0065] As shown in Figure 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, for example, transmit a system information block (SIB) containing the Nsg. The UE 100 (receiver 112) receives the Nsg information in the cell where the UE 100 is located.

[0066] In step S102, the UE100 (control unit 120) calculates the user device identity (UE_ID). Specifically, the UE100 (control unit 120) selects one of the first or second calculation formulas described later, based on whether or not a paging subgroup to which some of the multiple UE100s assigned to the same PO belong is set for the UE100. The UE100 (control unit 120) calculates the UE_ID using the selected calculation formula. Figure 9 shows an example of the operation of the UE100.

[0067] As shown in Figure 9, in step S121, the UE100 (control unit 120) determines whether a paging subgroup (PSG) has been set to the UE100. The UE100 (control unit 120) may determine that a PSG has been set to the UE100 in at least one of the following cases. Note that the setting of the paging subgroup may be a setting for the UE100 (control unit 120) to monitor PDCCH monitoring opportunities (i.e., to monitor paging) (see Figure 10).

[0068] Firstly, UE100 (control unit 120) may determine that PSG has been set to UE100 when Nsg is notified from network 10 (base station 200). Therefore, UE100 (control unit 120) may determine that PSG has been set to UE100 when it receives Nsg information in the cell where UE100 is located.

[0069] Secondly, the UE100 (control unit 120) may determine that the PSG has been set to UE100 when it receives information from the network 10 (base station 200) regarding the setting of paging subgroups. For example, the UE100 (control unit 120) may determine that the PSG has been set to UE100 when it receives information indicating that paging subgroups are determined by the second grouping method.

[0070] If UE100 (control unit 120) determines that the PSG is set to UE100, it executes the process in step S122. On the other hand, if UE100 (control unit 120) determines that the PSG is not set to UE100, it executes the process in step S123.

[0071] In step S122, UE100 (control unit 120) selects a first calculation formula. Using the selected first calculation formula, UE100 (control unit 120) calculates the UE_ID.

[0072] For example, the first calculation formula is "UE_ID = unique identifier of user device mod Y". The unique identifier of user device 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 mobile communication system 1. In the current 3GPP technical specifications, the maximum number of configurable PSGs is 8. For example, as shown in Figure 10, UE100 (control unit 120) calculates 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 only needs to be greater than N*Ns*Nsg.

[0073] In step S123, UE100 (control unit 120) selects a second calculation formula. UE100 (control unit 120) uses the selected second calculation formula to calculate the UE_ID.

[0074] For example, as shown in Figure 10, the second calculation formula is E21B, which is "UE_ID = 5G-S-TMSI mod 1024" as 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 example, the UE_ID calculated by the second calculation formula is represented by 10 bits (=log2(1024)), while the UE_ID calculated by the first calculation formula is represented by 13 bits (=log2(8192)).

[0076] Returning to Figure 8, in step S103, UE100 (control unit 120) calculates PF, PO, and PSG. For example, UE100 (control unit 120) calculates PF using equation E11, PO using equation E12, and PSG using equation E13.

[0077] Steps S104 and S105 are the same as steps S13 and S14. The base station 200 (control unit 230) calculates the UE_ID, PF, PO, and PSG, similar to the UE100. The base station 200 (control unit 230, transmission unit 211) performs paging transmission based on the calculated UE_ID, PF, PO, and PSG.

[0078] Specifically, when paging is triggered for a UE100, the base station 200 (control unit 230) calculates the UE_ID of the UE100 and calculates a PSG (Paging Subgroup ID) based on the calculated UE_ID. Before transmitting a paging message, the base station 200 (transmitter 211) notifies each UE100 of the calculated paging subgroup ID. Subsequently, the base station 200 (transmitter 211) transmits a paging message containing the unique identifier of the UE100.

[0079] As described above, the UE100 (control unit 120) calculates the UE_ID using formula E21A (UE_ID = 5G-S-TMSI mod 8192). Even when the formula "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from the UE_ID, each UE100 is assigned an appropriate paging subgroup ID because not all UE100s assigned to the same paging opportunity belong to the same PSG.

[0080] If the PSG is not set to UE100, UE100 (control unit 120) selects the second calculation formula. Compared to the case where the first calculation formula is selected, this reduces the number of bits required to transmit the UE_ID, thereby suppressing an increase in the amount of information in the UE_ID.

[0081] Furthermore, the first calculation formula is "UE_ID = unique identifier of user device mod Y", where Y is a fixed value obtained by multiplying 1024 by the maximum value of the configurable PSG number specified in the technical specifications of the mobile communication system 1. This simplifies the process for calculating UE_ID, as the UE100 (control unit 120) can omit, for example, managing variable values, compared to the case where Y is a variable value that can be changed for each cell (e.g., Nsg).

[0082] (2) Second example of operation Referring to Figures 11 and 12, the second operational example will be explained, primarily focusing on the differences from the operational example described above. In the second operational example, UE100 selects the first calculation formula when the condition "N*Ns*Nsg > threshold" is met, and selects the second calculation formula when this condition is not met.

[0083] As shown in Figure 11, step S221 is the same as step S121. If UE100 (control unit 120) determines that the PSG is set to UE100, it executes the process in step S222. On the other hand, if UE100 (control unit 120) determines that the PSG is not set to UE100, it executes the process in step S223.

[0084] In step S222, the UE100 (control unit 120) determines whether the condition "N*Ns*Nsg > threshold" is met.

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

[0086] If the condition is met, the UE100 (control unit 120) executes the process in step S223. On the other hand, if the condition is not met, the UE100 (control unit 120) executes the process in step S224.

[0087] In step S223, the UE100 (control unit 120) selects equation E22A as the first calculation equation, for example, as shown in Figure 12. In this example, equation E22A is the same as equation E21A.

[0088] In step S224, UE100 (control unit 120) selects equation E22B as the second calculation equation, for example, as shown in Figure 12. In this example, equation E22B is the same as equation E21B.

[0089] As described above, when the condition "N*Ns*Nsg > 1024" is met, the UE100 (control unit 120) calculates the UE_ID using formula E22A (UE_ID = 5G-S-TMSI mod 8192). Even when the formula "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from the UE_ID, each UE100 is assigned an appropriate paging subgroup ID because not all UE100s assigned to the same paging opportunity belong to the same PSG.

[0090] Furthermore, if the condition "N*Ns*Nsg > 1024" is not met, UE100 (control unit 120) will select the second calculation formula even if PSG is set to UE100. This reduces the number of bits required to transmit the UE_ID compared to when the first calculation formula is selected, thus suppressing an increase in the amount of information in the UE_ID.

[0091] (3) Third example of operation Referring to Figure 13, the differences between the third operation example and the operation example described above will be explained. In the third operation example, UE100 (control unit 120) selects a different formula as the first calculation formula compared to the operation example described above. The flowchart for UE100 (control unit 120) in this operation example is the same as that for the second operation example.

[0092] In step S223, the UE100 (control unit 120) selects equation E23A as the first calculation equation, for example, as shown in Figure 13. In this example, equation E23A is "UE_ID = unique identifier of user device mod Z", where Z is the value obtained by multiplying 1024 by Nsg.

[0093] In step S224, UE100 (control unit 120) selects equation E23B as the second calculation equation, for example, as shown in Figure 13. In this example, equation E23B is the same as equation E21B.

[0094] As described above, when the condition "N*Ns*Nsg > 1024" is met, the UE100 (control unit 120) calculates the UE_ID using formula E23A. Even when the formula "UE subgroup ID = floor(UE_ID / (N*Ns)) mod Nsg" is used to calculate the paging subgroup ID from the UE_ID, each UE100 is assigned an appropriate paging subgroup ID because not all UE100s assigned to the same paging opportunity belong to the same PSG.

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

[0096] Furthermore, if the condition "N*Ns*Nsg > 1024" is not met, UE100 (control unit 120) will select the second calculation formula even if PSG is set to UE100. This reduces the number of bits required to transmit the UE_ID compared to when the first calculation formula is selected, thus suppressing an increase in the amount of information in the UE_ID.

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

[0098] The operation sequences (and operation flows) in the above-described embodiments do not necessarily have to be executed chronologically in the order shown in the flowchart or sequence diagram. For example, the steps in the operation may be executed in a different order than that shown in the flowchart or sequence diagram, or they may be executed in parallel. Also, some steps in the operation may be deleted, or further steps may be added to the process. Furthermore, the operation sequences (and operation flows) in the above-described embodiments may be implemented separately and independently, or two or more operation sequences (and operation flows) may be combined and implemented. For example, some steps of one operation flow may be added to another operation flow, or some steps of one operation flow may be replaced with some steps of another operation flow.

[0099] In the embodiments described above, a mobile communication system based on NR was used as an example for 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 either LTE (Long Term Evolution) or another generation system of the 3GPP standard (e.g., 6th generation). The base station 200 may be an eNB that provides E-UTRA user plane and control plane protocol terminations directed to the UE100 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 IAB node.

[0100] A program may be provided that causes a computer to execute each process performed by the UE100 or base station 200. The program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be a recording medium such as a CD-ROM (Compact Disk Read Only Memory) or a DVD-ROM (Digital Versatile Disc Read Only Memory). Alternatively, the circuits that execute each process performed by the UE100 or base station 200 may be integrated, and at least a part of the UE100 or base station 200 may be configured as a semiconductor integrated circuit (chipset, SoC (System On Chip)).

[0101] In the embodiments described above, "transmit" may mean processing at least one layer in the protocol stack used for transmission, or it may mean physically transmitting a signal wirelessly or via a wire. Alternatively, "transmit" may mean a combination of processing at least one layer and physically transmitting a signal wirelessly or via a wire. Similarly, "receive" may mean processing at least one layer in the protocol stack used for reception, or it may mean physically receiving a signal wirelessly or via a wire. Alternatively, "receive" may mean a combination of processing at least one layer and physically receiving a signal wirelessly or via a wire. Similarly, "obtain / acquire" may mean obtaining information from stored information, obtaining information from information received from other nodes, or obtaining information by generating it. Similarly, the phrases "based on" and "depending on / in response to" do not mean "based solely on" or "depending solely on" unless otherwise specified. The phrase "based on" means both "based solely on" and "based at least partially on." Similarly, the phrase "according to" means both "according solely to" and "according at least partially to." Likewise, "include" and "comprise" do not mean to include only the listed items, but may include only the listed items or may include additional items in addition to the listed items. Similarly, in this disclosure, "or" does not mean exclusive OR, but means logical OR. Furthermore, any reference to elements using designations such as "first," "second," etc., as used in this disclosure does not limit the quantity or order of those elements in general. These designations may be used in this disclosure as a convenient way to distinguish between two or more elements.Therefore, references to the first and second elements do not imply that only two elements may be adopted therein, or that the first element must precede the second element in any way. In this disclosure, where articles are added by translation, such as a, an, and the in English, these articles shall be plural unless it is clearly indicated by the context that they are not.

[0102] This disclosure is described in accordance with the embodiments, but it is understood that this disclosure is not limited to such embodiments or structures. This disclosure also includes various modifications and variations within the equivalence. In addition, various combinations and forms, as well as other combinations and forms that include only one, more, or fewer of those elements, fall within the scope and concept of this disclosure.

[0103] (Note) The features of the above-described embodiment are noted below.

[0104] (Note 1) A receiving unit that receives from the network first information indicating the number of subgroups per paging opportunity, and second information regarding the setting of the subgroups based on the user device identity (UE_ID), The system comprises 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 receiving unit monitors paging opportunities based on the subgroup identifier. Communication device.

[0105] (Note 2) The aforementioned predetermined calculation formula is an expression based on 5G-S-TMSI, which is a temporary mobile subscription identifier. The communication device described in Appendix 1.

[0106] (Note 3) The aforementioned predetermined calculation formula is the first calculation formula, The control unit, Based on the fact that the second information has not been received, the UE_ID is calculated using a second calculation formula different from the first calculation formula. Based on the UE_ID calculated using the second calculation formula described above, monitor paging opportunities. Communication device as described in Appendix 1 or 2.

[0107] (Note 4) The second calculation formula described above is based on the 5G-S-TMSI, which is a temporary mobile subscription identifier. The communication device described in Appendix 3.

[0108] (Note 5) A transmitting unit transmits to a communication device first information indicating the number of subgroups per paging opportunity, and second information regarding the setting of the subgroups based on the user device identity (UE_ID), The system comprises 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 transmitting unit transmits downlink control information on the physical link control channel during paging opportunities based on the subgroup identifier. Base station.

[0109] (Note 6) A communication method performed by a communication device, The steps include receiving from the network first information indicating the number of subgroups per paging opportunity, and second information regarding the configuration of the subgroups based on the user device identity (UE_ID), The steps include: 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; The step of monitoring paging opportunities based on the aforementioned subgroup identifiers is included. Communication method.

Claims

1. A communication device (100), A receiving unit (112) that receives paging messages from a base station (200) during a paging opportunity, The system includes a control unit (120) that calculates a user device identity (UE_ID), The control unit (120) Based on the fact that the communication device has received first information for indicating the number of subgroups per paging opportunity and second information for setting UE_ID-based subgrouping, a first UE_ID is calculated as the UE_ID using a first formula that modulates the unique identifier of the communication device by a first value, and the paging opportunity is monitored based on the first UE_ID calculated using the first formula. Based on the fact that the communication device has not received the second information, a second UE_ID is calculated as the UE_ID using a second formula that modulates the unique identifier of the communication device by the second value, and the paging opportunity is monitored based on the second UE_ID calculated using the second formula. The first value is greater than the second value. Communication device (100).

2. The receiving unit receives information associated with the subgroup identifier of the paging opportunity from the base station, Based on the fact that the communication device has received the first information and the second information, the control unit monitors the paging opportunity based on the subgroup identifier based on the first UE_ID calculated using the first formula and the information associated with the subgroup identifier. The communication device according to claim 1.

3. The unique identifier of the communication device is 5G-S-TMSI (Temporary Mobile Subscriber Identifier), The subgroup identifier based on the UE_ID calculated using the first formula is based on the number of subgroups per paging opportunity, the number of paging opportunities per paging frame, and the total number of paging frames in the 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. A communication device according to claim 1 or claim 2.

5. A base station (200), A transmitting unit (211) that transmits a paging message to a communication device during a paging process, The system includes a control unit (230) that calculates a user device identity (UE_ID), The control unit (230) Based on the fact that the base station has transmitted to the communication device first information for indicating the number of subgroups per paging opportunity and second information for setting UE_ID-based subgrouping, the communication device is controlled to monitor the paging opportunity based on a first UE_ID calculated as the UE_ID using a first expression that modulo the unique identifier of the communication device by a first value. Based on the fact that the base station does not transmit the second information to the communication device, the communication device is controlled to monitor the paging opportunity according to the second UE_ID calculated as the UE_ID using a second expression that modulates the unique identifier of the communication device by the second value. The first value is greater than the second value. Base station.

6. The transmitting unit transmits information associated with the subgroup identifier of the paging opportunity to the communication device, The control unit, based on the fact that the communication device has received the first information and the second information, controls the device to monitor the paging opportunity based on the subgroup identifier based on the first UE_ID calculated using the first formula and the information associated with the subgroup identifier. The base station according to claim 5.

7. The unique identifier of the communication device is 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 opportunity, the number of paging opportunities per paging frame, and the total number of paging frames in the discontinuous reception (DRX) cycle of the communication device. The base station according to 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 performed by a communication device (100), The steps include receiving a paging message from the base station (200) during a paging opportunity, Based on the fact that the communication device has received first information for indicating the number of subgroups per paging opportunity and second information for setting up user device identity (UE_ID) based subgrouping, the steps include: calculating a first UE_ID as the UE_ID using a first formula that modulates the unique identifier of the communication device by a first value; and monitoring the paging opportunity based on the first UE_ID calculated using the first formula; The process includes the steps of: calculating a second UE_ID as the UE_ID using a second formula that modulates the unique identifier of the communication device by a second value, based on the fact that the communication device has not received the second information; and monitoring the paging opportunity based on the second UE_ID calculated using the second formula. The first value is greater than the second value. Communication method.

10. The steps of receiving information associated with the subgroup identifier of the paging opportunity from the base station, The communication device has received the first information and the second information, and the step of monitoring the paging opportunity based on a subgroup identifier based on the first UE_ID calculated using the first formula and information associated with the subgroup identifier. The communication method according to claim 9.

11. The unique identifier of the communication device is 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 opportunity, the number of paging opportunities per paging frame, and the total number of paging frames in the discontinuous reception (DRX) cycle of the communication device. The communication method according to claim 10.

12. The first value is 8192, The second value is 1024. The communication method according to claim 9 or claim 10.

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