Terminal device, base station device, control method for terminal device, and control method for base station device

Abstract

A terminal device according to the present invention includes a control unit, a transmission unit, and a reception unit. The control unit determines whether access to a second base station device is permitted on the basis of the type of the terminal device, setting information about a request signal for requesting the transmission of essential system information about the second base station device, information indicating access restrictions for a cell of the second base station device as acquired from a first base station device, and the reception quality obtained by measuring a signal of the second base station device. On the basis of the above determination, the transmission unit transmits the request signal to the second base station device corresponding to the setting information. The reception unit receives the essential system information, of the second base station device, transmitted in accordance with the request signal.

Description

Terminal device, base station device, terminal device control method, and base station device control method

[0001] The present invention relates to a terminal device, a base station device, and a control method.

[0002] In today's networks, traffic from mobile devices (such as smartphones and feature phones) accounts for the majority of network resources, and traffic from mobile devices is expected to continue to grow.

[0003] In addition to traffic used by mobile terminals, for example, IoT (Internet of Things) services (for example, monitoring systems for transportation systems, smart meters, and devices) are being deployed. Therefore, networks are required to support services with diverse requirements. In order to support such diverse services, for example, the communication standard for fifth-generation mobile communications (5G or NR (New Radio)) is designed to support many use cases classified as eMBB (Enhanced Mobile Broadband), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications).

[0004] In addition, in the 3rd Generation Partnership Project (3GPP), an international standardization project, extension technologies for the above communication standards are currently being continuously studied and standardized.

[0005] In 3GPP, NES (Network Energy Savings) technology is being studied to reduce power consumption on the network side (i.e., base station devices, core network devices) (Non-Patent Document 1). Hereinafter, a cell (base station device) corresponding to the NES function, i.e., a cell supporting the NES function, is also referred to as an NES cell.

[0006] 3GPP TR 38.864 V18.0.0 (2022-12) R1-2405106

[0007] Generally, a base station device broadcasts system information within a cell as information commonly used by terminal devices within the cell. The system information is also referred to as broadcast information. In 3GPP, as one of the network power reduction technologies, a method is being considered for reducing the power consumption of a base station device by introducing an on-demand SIB1 that is appropriately transmitted (on-demand transmitted) from an NES cell in response to a request from a terminal device, instead of SIB1 (System Information Block Type 1), which is a type of broadcast information that is periodically transmitted. For example, Non-Patent Document 2 discloses an example of parameter information applied to an uplink wake-up signal (UL-WUS) procedure used in a terminal device to request an on-demand SIB1.

[0008] However, in conventional communication systems, cell access restriction information (restriction information) is included in SIB1. Therefore, in the case of On-demand SIB1, which is transmitted appropriately in response to a request from a terminal device, uplink transmission to the NES cell occurs before acquiring the access restriction information. Therefore, the terminal device cannot determine whether access to the cell is restricted until it receives On-demand SIB1, resulting in a problem of requesting the base station device to transmit unnecessary On-demand SIB1. Furthermore, since the base station device cannot notify in advance using SIB1 whether a terminal device is subject to cell access restriction, it ends up transmitting On-demand SIB1 even to terminal devices whose access is actually restricted, resulting in a problem of reduced power saving efficiency. However, Non-Patent Document 2 does not mention any solutions to these problems.

[0009] An object of one aspect of the present invention is to improve the efficiency of power saving related to wireless communication between a terminal device and a base station device when applying a network power reduction technique that appropriately transmits system information (SIB1).

[0010] A terminal device according to one aspect of the present invention is a terminal device capable of communicating with a first base station device and a second base station device, and comprises: a control unit that determines whether access to the second base station device is permitted based on the type of the terminal device, configuration information for a request signal requesting the transmission of essential system information from the second base station device, information indicating access restrictions for the cell of the second base station device obtained from the first base station device, and the measured reception quality of the signal from the second base station device; a transmission unit that transmits a request signal to the second base station device corresponding to the configuration information based on the determination; and a reception unit that receives the essential system information of the second base station device transmitted in response to the request signal.

[0011] A base station device according to one aspect of the present invention is a base station device in a communication system including a first cell that periodically transmits essential system information and a second cell that transmits essential system information in response to a request from a terminal device, and includes: a receiving unit that receives from the second cell information indicating access restrictions of the second cell and configuration information for a request signal for essential system information of the second cell used by the terminal device; a control unit that sets the information indicating access restrictions of the second cell so that the terminal device can determine whether it can access the second cell based on the type of the terminal device, the configuration information for the request signal acquired by the terminal device from the first cell, information indicating access restrictions of the second cell acquired by the terminal device from the first cell, and the measured reception quality of the signal of the second base station device; and a transmitting unit that transmits the information indicating access restrictions and the configuration information for the request signal to the terminal device using the first cell.

[0012] According to the above-described aspect, when applying a network power reduction technique, the efficiency of power saving related to wireless communication between a terminal device and a base station device is improved.

[0013] Fig. 1 is a diagram showing an example of the configuration of a wireless communication system according to an embodiment. Fig. 2 is a diagram showing an example of the functional configuration of a terminal device according to an embodiment. Fig. 3 is a diagram showing an example of the functional configuration of a base station device according to an embodiment. Fig. 4 is a diagram showing an example of an On-demand SIB1 procedure. Fig. 5 is a diagram showing an example of cell access restriction information. Fig. 6 is a diagram showing an example of a method for notifying cell access restriction information. Fig. 7 is a diagram showing another example of an On-demand SIB1 procedure. Fig. 8 is a diagram showing an example of the hardware configuration of a terminal device. Fig. 9 is a diagram showing an example of the hardware configuration of a base station device.

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The problems and embodiments in this specification are merely examples and do not limit the scope of the present invention. In particular, even if the expressions used are different, the technology of the present invention can be applied as long as they are technically equivalent, and do not limit the scope of the present invention. Furthermore, each embodiment can be appropriately combined within the scope of the processing content. For example, an inactive period may be referred to as an inactive period.

[0015] Publicly known technologies may be used as appropriate in the wireless communication system according to the embodiment of the present invention. Applicable publicly known technologies may be, for example, 5G (NR), Beyond 5G, 5G-Advanced, or other wireless communication methods. The wireless communication system according to the embodiment of the present invention targets NR, but is not limited thereto. For example, the embodiment of the present invention can also be applied to LTE (Long Term Evolution) and LTE-Advanced. It can also be applied to a wireless communication system that uses NR as part of the wireless communication system.

[0016] Furthermore, the embodiments of the present invention are applicable to any wireless communication system including at least a terminal device and a base station device, and are also applicable to future wireless communication systems. In the following description, LTE and LTE-Advanced are also referred to as E-UTRA (Evolved Universal Terrestrial Radio Access), but the meaning is the same.

[0017] Hereinafter, embodiments of a base station apparatus, a terminal apparatus, and a wireless communication system disclosed in the present application will be described with reference to the drawings. Note that the disclosed technology is not limited to the following embodiments.

[0018] <Wireless Communication System> FIG. 1 is a diagram illustrating an example of the configuration of a wireless communication system 1 according to an embodiment of the present invention. The wireless communication system 1 according to the embodiment includes, for example, a terminal device 10, base station devices 20A and 20B, and a core network 30. Note that when there is no need to distinguish between the base station devices 20A and 20B, they are simply referred to as the base station device 20. There may also be multiple terminal devices 10. The wireless communication system 1 is, for example, a wireless communication system that supports NES, in other words, a wireless communication system that supports the NES function. The base station device 20A is a base station device 20 (first base station device) that transmits information for accessing the base station device 20B that supports the NES function. On the other hand, the base station device 20B is a base station device 20 (second base station device) that also supports the NES function, and access is attempted based on information from the base station device 20A.

[0019] The terminal device 10 may be a wireless terminal such as a mobile phone, a smartphone, a PDA (Personal Digital Assistant), a tablet, a wearable device, a personal computer, a vehicle, or any other device or equipment (sensor device, etc.) having a wireless communication function. The terminal device 10 may also be referred to as a wireless communication device, a communication device, a receiving device, a mobile station, a UE (User Equipment), a user device, etc.

[0020] A wireless communication service is provided to a terminal device 10 by a base station device 20 and a core network 30 in a wireless communication system 1. The core network 30 has functions such as managing service subscriber information, managing sessions such as voice calls, and managing location registration of the terminal device 10. The core network 30 also transmits control data and / or user data to the terminal device 10 via the base station device 20.

[0021] The core network 30 may be a 5G Core (5GC) in 5G (NR) or an Evolved Packet Core (EPC) in 4G (E-UTRA). The connection method between the core network 30 and the base station device 20 may be a Non-Stand Alone (NSA) method or a Stand Alone (SA) method.

[0022] The 5G base station device 20 connected to the 5GC is a gNB, and the 4G base station device 20 connected to the EPC is an eNB. The 5G base station devices are physically or logically connected via an Xn interface. Similarly, the 4G base station devices are physically or logically connected via an X2 interface.

[0023] An area (coverage area) formed by a base station device 20 may be called a "cell." E-UTRA and 5G are cellular communication systems constructed by multiple cells. As a wireless communication system according to an embodiment of the present invention, either a time division duplex (TDD) or a frequency division duplex (FDD) method may be applied, and different methods may be applied to each cell.

[0024] Hereinafter, the cell configured by the base station device 20A is also referred to as a normal cell 20A-1 (first cell). The normal cell 20A-1 is, for example, a cell that does not support NES or an NES cell (described later) that does not apply power saving technology. Furthermore, a cell configured by the base station device 20B that can transition to a state (sleep state) in which power consumption can be reduced by applying a predetermined power saving technology is also referred to as a NES cell 20B-1 (second cell). For example, in the sleep state, the NES cell 20B-1 achieves power saving by halting transmission and reception of signals other than predetermined physical signals and physical channels and shutting down standby power for wireless devices within the base station device 20B. The predetermined physical signals and physical channels are, for example, the PDCCH and PDSCH related to the On-demand SIB1.

[0025] The normal cell 20A-1 is an anchor cell for providing (transferring, notifying) information necessary for the terminal device 10 to access the NES cell 20B-1 to the terminal device 10. In addition, the NES cell 20B-1 provides the normal cell 20A-1 with at least control information used to determine whether the terminal device 10 can access the NES cell 20B-1, and UL-WUS setting information (described later) for requesting an On-demand SIB1 from the NES cell 20B-1.

[0026] 1 illustrates a correspondence relationship in which the normal cell 20A-1 includes the NES cell 20B-1, but the size and positional relationship of these two cells is merely an example, and a correspondence relationship other than that shown in FIG. 1 may be used. For example, the normal cell 20A-1 and the NES cell 20B-1 may be the same size, or the NES cell 20B-1 may be larger. A configuration in which the normal cell 20A-1 includes multiple NES cells 20B-1 may also be used.

[0027] The sleep state is, for example, a state in which some of the functions related to transmission and reception of the base station device 20B (NES cell 20B-1) are stopped, and at the same time, power supply to internal devices related to transmission and reception is suppressed, and at least one of transmission and reception of some messages transmitted by the base station device 20B and corresponding physical signals and physical channels is not performed. Furthermore, for example, when the sleep state is released (application of a predetermined power saving technology is stopped) or when the sleep state is temporarily released, the NES cell 20B-1 enters a non-sleep state and transitions to a cell (for example, the normal cell 20A-1) in which normal wireless communication can be performed.

[0028] The terminal device 10 is a communication device that is wirelessly connected to the base station device 20A or the base station device 20B and transmits and receives data. The terminal device 10 is also a communication device that corresponds to the NES function, i.e., a communication device that supports the NES function.

[0029] The NES cell may include, for example, a base station device 20B that is transitioning to a sleep state and a base station device 20B that may transition to a sleep state. Furthermore, the normal cell 20A-1 and the NES cell 20B-1 may be cells under the control of the same base station device 20 or may be cells under the control of different base station devices 20.

[0030] The base station device 20 may be configured, for example, as being divided into a CU (Centralized Unit), a DU (Distributed Unit), and an RU (Radio Unit). The CU is connected to a core network. The DU is connected to the terminal device 10 via the RU, for example. The communication path between the CU and the DU is realized by, for example, a fronthaul interface (F1 interface). Multiple DUs may be connected to one CU.

[0031] In the example shown in Figure 1, data (DL data, downlink data) transmitted from the core network 30 to the terminal device 10 is transmitted from the core network 30 to the base station device 20, and then transmitted (forwarded) from the base station device 20 to the terminal device 10.

[0032] Data (UL data, uplink data) transmitted from the terminal device 10 to the core network 30 is transmitted from the terminal device 10 to the base station device 20 and then transmitted (transferred) from the base station device 20 to the core network 30 .

[0033] The terminal device 10 and the base station device 20 transmit and receive RRC messages (also called RRC signaling) in a Radio Resource Control (RRC) layer. Also, the terminal device 10 and the base station device 20 transmit and receive MAC control elements (MAC CEs) in a Medium Access Control (MAC) layer.

[0034] The RRC message is transmitted as an RRC Protocol Data Unit (PDU), and the logical channel (LCH) to which it is mapped may be a common control channel (CCCH), a dedicated control channel (DCCH), a paging control channel (PCCH), a broadcast control channel (BCCH), a multicast control channel (MCCH), or the like.

[0035] The MAC CE is transmitted as a MAC PDU (or MAC subPDU). A MAC subPDU is equivalent to a service data unit (SDU) in the MAC layer plus, for example, 8 bits of header information, and the MAC PDU includes one or more MAC subPDUs.

[0036] Next, as physical channels and physical signals related to the embodiment, there are at least a synchronization signal (Primary Synchronization Signal, Secondary Synchronization Signal), a physical broadcast channel (PBCH: Physical Broadcast Channel), a physical random access channel (PRACH: Physical Random Access Channel), a physical downlink control channel (PDCCH: Physical Downlink Control Channel), a channel state information reference signal (CSI-RS: Channel State Information-Reference Signal), a physical uplink control channel (PUCCH: Physical Uplink Control Channel), a physical downlink shared channel (PDSCH: Physical Downlink Shared Channel), a physical uplink shared channel (PUSCH: Physical Uplink Shared Channel), a scheduling reference signal (SRS: Scheduling Reference Signal), and a demodulation reference signal (DMRS), but detailed description thereof will be omitted.

[0037] <Terminal Device> Fig. 2 is a diagram showing an example of the functional configuration of a terminal device 10 according to an embodiment. As shown in Fig. 2, the terminal device 10 includes, for example, a processing unit 11, a control unit 13, a receiving unit 15, a transmitting unit 17, and a transmitting / receiving antenna unit 19. The processing unit 11 includes, for example, a radio resource processing unit 111 and a control processing unit 113. Note that the functional configuration of the terminal device 10 shown in Fig. 2 is merely an example, and the functional divisions and names of each functional block may be different as long as the operations according to the embodiment can be performed. Furthermore, one or more blocks that realize other functions may be present.

[0038] The processing unit 11 generates, for example, control information for controlling the receiving unit 15 and the transmitting unit 17, and outputs the control information to the control unit 13. The processing unit 11 executes processes related to, for example, a radio resource control layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control layer.

[0039] The radio resource processing unit 111 manages various setting information (RRC parameters, information elements (IEs)) of the terminal device 10. For example, the radio resource processing unit 111 generates information to be allocated to each channel of the physical uplink and outputs the information to the transmission unit 17. Furthermore, based on instructions from the base station device 20, the radio resource processing unit 111 performs measurements of the serving cell and surrounding cells, start and stop of transmission and reception processing, DL synchronization procedure (cell search), UL synchronization procedure (random access procedure), UL-WUS transmission procedure, acquisition and reacquisition of system information, event evaluation related to handover, a series of processes related to handover, and the like.

[0040] The control processing unit 113 acquires, classifies, and interprets information related to access restrictions, and executes control processing to determine whether or not the cell is accessible based on the type, supported functions, etc. of the terminal device 10. The control processing unit 113 also executes control processing to determine the setting value of the transmission power to be applied during UL-WUS transmission. The control processing unit 113 also executes control processing to determine whether or not UL-WUS transmission is necessary, based on instructions from the radio resource processing unit 111 or instructions from the base station device 20.

[0041] The control unit 13 performs various controls in the terminal device 10. For example, the control unit 13 generates control signals or control data for controlling the receiving unit 15 and the transmitting unit 17 based on control information from the processing unit 11. Furthermore, the control unit 13 controls uplink transmission to the base station device 20, scheduling request transmission, UL-WUS transmission, and downlink reception from the base station device 20 based on determination information related to transmission control from the control processing unit 113.

[0042] The receiving unit 15 separates, demodulates, and decodes various signals received from the base station device 20 via the transmitting / receiving antenna unit 19 based on a control signal provided by the control unit 13. The receiving unit 15 outputs the decoded information to the processing unit 11.

[0043] The transmitter 17 generates, for example, a physical uplink signal based on a control signal provided from the controller 13, and performs encoding and modulation on the physical uplink signal or the physical uplink channel provided from the processor 11. The transmitter 17 multiplexes various signals and transmits them to the base station device 20 via the transmitter-receiver antenna unit 19.

[0044] The processing unit 11 and the control unit 13 are realized, for example, by a processor system including a processor and a memory. In this case, the processor provides the functions of the processing unit 11 and the control unit 13 by executing a program that describes the operation of the terminal device 10, which will be described later. The processing unit 11 and the control unit 13 may be realized by a single processor system or by multiple processor systems. Alternatively, the processing unit 11 and the control unit 13 may be realized by a DSP (Digital Signal Processor), a hardware circuit, or the like.

[0045] <Base Station Device> Fig. 3 is a diagram illustrating an example of the functional configuration of a base station device 20 according to an embodiment. As illustrated in Fig. 3, the base station device 20 includes, for example, a processing unit 21, a control unit 23, a receiving unit 25, a transmitting unit 27, and a transmitting / receiving antenna unit 29. The processing unit 21 illustratively includes a radio resource processing unit 211 and an SIB1 control processing unit 213. Note that the functional configuration of the base station device 20 illustrated in Fig. 3 is merely an example, and the names of the functional divisions and functional blocks may be different as long as the operations according to the embodiment can be performed. Furthermore, one or more blocks that realize other functions may be present.

[0046] The processing unit 21 generates, for example, control information for controlling the receiving unit 25 and the transmitting unit 27, and outputs the control information to the control unit 23. The processing unit 21 executes processes relating to, for example, the radio resource control layer, the packet data integration protocol layer, the radio link control layer, and the medium access control layer.

[0047] The radio resource processing unit 211 generates, for example, downlink data, an RRC message, and a MAC control element to be allocated to the physical downlink shared channel PDSCH, and outputs these to the transmission unit 27. The radio resource processing unit 211 also generates a control signal or control data to be allocated to the physical downlink control channel PDCCH, and outputs this to the transmission unit 27. Furthermore, the radio resource processing unit 211 manages various setting information of the terminal device 10. Based on a signal from the terminal device 10 or a notification by an RRC message, the radio resource processing unit 211 executes operations such as starting and stopping transmission and reception processing, starting a UL synchronization procedure (random access procedure), updating system information, starting and stopping on-demand SIB1 transmission, adjusting the beam transmission angle, and generating parameters related to the UL-WUS transmission procedure.

[0048] The SIB1 control processing unit 213 performs a series of control processes related to on-demand SIB1 transmission. For example, the SIB1 control processing unit 213 executes a control process to determine whether on-demand SIB1 transmission is necessary based on an instruction from an upper layer or on reception of an UL-WUS transmitted from the terminal device 10.

[0049] The control unit 23 performs various controls in the base station device 20. For example, the control unit 23 generates a control signal or control data for controlling the receiving unit 25 and the transmitting unit 27 based on control information from the processing unit 21. Furthermore, the control unit 23 controls downlink transmission corresponding to the On-demand SIB1 to the terminal device 10 based on determination information related to the On-demand SIB1 transmission from the SIB1 control processing unit 213.

[0050] The receiving unit 25 separates, demodulates, and decodes various signals received from the terminal device 10 or the core network 30 via the transmitting / receiving antenna unit 29 based on a control signal provided by the control unit 23. The receiving unit 25 outputs the decoded information to the processing unit 21.

[0051] The transmitter 27 generates, for example, a downlink reference signal based on the control signal provided by the controller 23. The transmitter 27 encodes, modulates, multiplexes, and so on various pieces of information provided by the processor 21, and transmits the signal to the terminal device 10 via the transmitting / receiving antenna unit 29.

[0052] Furthermore, the transmitter 27 transmits data to the terminal device 10, another base station device 20, or the core network 30. The receiver 25 receives data from the terminal device 10, another base station device 20, or the core network 30.

[0053] The processing unit 21 and the control unit 23 are realized, for example, by a processor system including a processor and a memory. In this case, the processor provides the functions of the processing unit 21 and the control unit 23 by executing a program that describes the operation of the base station device 20, which will be described later. The processing unit 21 and the control unit 23 may be realized by a single processor system or by multiple processor systems. Alternatively, the processing unit 21 and the control unit 23 may be realized by a DSP, a hardware circuit, or the like.

[0054] <On-demand SIB1> On-demand SIB1 is one of the power-saving technologies applied to the base station device 20, and is a method of appropriately transmitting SIB1, which is one piece of periodically transmitted broadcast information, based on a request from the terminal device 10. The content included in On-demand SIB1 includes at least the setting information (radio connection information (cell-common resource information, cell selection criteria information, access restriction information, etc.)) notified in the conventional SIB1, and may further include UL-WUS setting information indicating the transmission setting of UL-WUS, which is a signal for requesting On-demand SIB1. The base station device 20B may be configured to similarly transmit system information other than On-demand SIB1 (SIB2, SIB3, ...) on demand. Note that access restriction information may be referred to by similar terms such as access restriction information, access control information, and access prohibition information.

[0055] To receive the on-demand SIB1 of the base station device 20B (NES cell 20B-1), the terminal device 10 detects and acquires the synchronization signal / physical broadcast channel block (SSB) of the base station device 20B and adjusts downlink synchronization using the SSB. The SSB includes a synchronization signal and a physical broadcast channel (PBCH). The synchronization signal is composed of a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).

[0056] Next, the terminal device 10 acquires PDCCH transmission resource information, SSB subcarrier offset information (ssb-SubcarrierOffset), etc. acquired from the MIB (Master Information Block) transmitted in the SSB (PBCH). Then, the terminal device 10 monitors the PDCCH in the acquired transmission resource and acquires the PDSCH (On-demand SIB1) indicated by the DCI of the detected PDCCH. The MIB and SIB1 (On-demand SIB1) are essential system information (Essential System Information). Furthermore, the MIB and SIB1 (On-demand SIB1) may be described as first system information. Furthermore, system information other than the MIB and SIB1 (On-demand SIB1) (for example, SIB2) may be described as second system information.

[0057] The terminal device 10 also calculates cell quality (reception quality) for each cell by measuring SSB or a channel state information reference signal (CSI-RS). The cell quality can be expressed using any of RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), SINR (Signal to Interference plus Noise Ratio), and path loss.

[0058] <UL-WUS Setting Information> The UL-WUS setting information includes some or all of the following information: cell information identifying a cell transmitting UL-WUS (such as a physical cell identifier (PCI) and downlink frequency information); information related to UL-WUS transmission (such as PRACH resource information, SSB reception power threshold, TDD UL / DL slot setting, and uplink frequency); information related to SIB1 reception (such as SSB subcarrier offset information and PDCCH resource information); and information related to PRACH response reception (such as a reception window length and reception start offset information). The terminal device 10 may further include cell selection criteria information (such as an RSRP threshold and a cell-specific offset value). Based on the cell information, the terminal device 10 may determine whether the base station device 20 is a normal cell 20A-1 or an NES cell 20B-1.

[0059] Taking the above into consideration, the following embodiments of the present invention will be described with reference to the drawings. Note that in the description of the embodiments of the present invention, if a specific description of well-known functions or configurations related to the embodiments of the present invention makes the gist of the embodiments of the present invention unclear, the detailed description will be omitted.

[0060] First Embodiment FIG. 4 is an example of a sequence diagram showing an On-demand SIB1 procedure between a terminal device 10 and a base station device 20 according to a first embodiment.

[0061] The terminal device 10 in Fig. 4 is a terminal device 10 that supports the NES function, and the base station device 20A (normal cell 20A-1) provides configuration information (NES cell access information) required for the terminal device 10 to request an On-demand SIB1 from the NES cell. The method by which the base station device 20A provides the configuration information to the terminal device 10 may involve including the information in system information and transmitting it periodically or on-demand within the cell, or notifying the information using an individual RRC message. The individual RRC message is, for example, an RRCReconfiguration message or an RRCRelease message.

[0062] 4 transmits On-demand SIB1 when it receives UL-WUS from the terminal device 10 or when it determines that the base station device 20B is necessary (for example, when the contents of SIB1 are updated). Similarly, when it determines that the base station device 20B is not necessary (for example, when a predetermined time has passed since the transmission of SIB1), it stops transmitting On-demand SIB1.

[0063] The base station device 20B provides the base station device 20A with NES cell access information via a transmission path between the base station devices 20 (step S100). The NES cell access information includes at least NES cell information (e.g., a combination of a physical cell identifier (PID) and downlink frequency information) that uniquely identifies the NES cell, and setting information related to UL-WUS (UL-WUS setting information).

[0064] The base station device 20B may further include access restriction information indicating access restrictions for the NES cell in the NES cell access information. The base station device 20A transmits (transfers, notifies) to the cell that is accessible from the base station device 20A and includes at least one piece of NES cell access information received from the base station device 20B (step S101). The terminal device 10 performs an access determination as to whether to transmit UL-WUS to the base station device 20B (NES cell 20B-1) using the NES cell access information received from the base station device 20A (step S102).

[0065] Here, the terminal device 10 compares the reception quality of the base station device 20A (normal cell 20A-1), which is the serving cell, with the reception quality of one or more base station devices 20B (NES cell 20B-1), which are cell reselection (cell reselection) candidates, and performs an access judgment on whether to transmit UL-WUS to the cell with the best reception quality. Note that if the terminal device 10 has not been notified (or does not hold) the same NES cell information as the cell detected by cell search, the terminal device 10 does not need to consider the detected cell as a target cell for cell reselection. Also, the terminal device 10 may consider the NES cell 20B-1 as a cell reselection candidate only when the moving speed of the terminal device 10 itself is low.

[0066] Furthermore, the terminal device 10 may monitor the downlink control channel PDCCH from the base station device 20A (normal cell 20A-1), which is the serving cell, and may perform access determination if downlink control information (DCI), which is bit information included in the PDCCH, indicates permission for UL-WUS transmission to the base station device 20B (NES cell 20B-1). The base station device 20A may include downlink resource information indicating the transmission position of the PDCCH that notifies permission for UL-WUS transmission in the NES cell access information. If downlink resource information indicating the transmission position of the PDCCH that notifies permission for UL-WUS transmission is not included in the NES cell access information, or if the downlink control information (DCI) does not indicate permission for UL-WUS transmission to the base station device 20B (NES cell 20B-1), the terminal device 10 may determine not to perform access determination (i.e., not to perform UL-WUS transmission and not to perform a cell reselection procedure).

[0067] The process related to the access determination of the terminal device 10 in step S102 will be described. The terminal device 10 determines whether access to the base station device 20B is possible based on the NES cell access information acquired in step S101. In other words, the terminal device 10 uses the NES cell access information to determine whether the base station device 20B is a suitable cell for cell reselection. More specifically, the terminal device 10 determines whether access to the base station device 20B is possible based on the access restriction information included in the NES cell access information. Note that the access restriction information and the UL-WUS setting information may be in a format in which a link with the corresponding NES cell information is notified, or in which the access restriction information is notified as part of the UL-WUS setting information.

[0068] The terminal device 10 determines whether the NES cell 20B-1 is accessible (access is permitted) or not (access is not permitted) based on the access restriction information shown in Fig. 5, for example. Fig. 5 is a diagram showing an example of cell access restriction information. Each piece of access restriction information shown in Fig. 5 indicates access restrictions corresponding to the type or supported functions of the terminal device 10. The access restriction information may be notified on a cell-by-cell basis as information elements (parameters) of the MIB or SIB1. Each piece of access restriction information will be described below.

[0069] The cellBarred is access restriction information used to instruct the terminal device 10 whether or not to prohibit access to the cell. If the value of cellBarred indicates "not barred," the terminal device 10 determines that access to the cell is permitted. That is, if the value of cellBarred indicates "barred," the terminal device 10 determines that access to the cell is not permitted. Note that, as described below, each of the following terminal devices 10 may ignore the value of cellBarred and determine whether the cell can be accessed in accordance with another access control identifier related to the supported function: (1) a terminal device 10 with two antennas and XR function, (2) a terminal device 10 with RedCap or eRedCap function, and (3) a terminal device 10 with Cell DTX / DRX function.

[0070] cellBarred2RxXR is access restriction information used to instruct a terminal device 10 (2Rx XR UE) that supports the XR (Extended Reality or Cross Reality) function provided by the wireless communication system 1 but has only two receive antennas (2Rx) whether to prohibit access to the cell. A terminal device 10 that supports XR and has two receive antennas determines that access is permitted even in a frequency band that requires four receive antennas if cellBarred2RxXR is not set. In other words, a terminal device 10 that supports XR and has two receive antennas determines that access is not permitted in a frequency band that requires four receive antennas if cellBarred2RxXR is set.

[0071] The cellBarredATG is access restriction information used to instruct a terminal device 10 supporting an ATG (Air-to-Ground) communication function whether or not to prohibit access to the cell for the purpose of ATG communication. A terminal device 10 supporting the ATG communication function determines that access to the cell for the purpose of ATG communication is permitted when the value of cellBarredATG indicates "not prohibited (not barred)." In other words, a terminal device 10 supporting the ATG communication function determines that access to the cell for the purpose of ATG communication is not permitted when the value of cellBarredATG indicates "prohibited (barred)" and cellBarredATG is not set (notified).

[0072] cellBarredNTN is access restriction information used to instruct a terminal device 10 supporting an NTN (Non-Terrestrial Network) communication function whether or not to prohibit access to the cell for the purpose of NTN communication. A terminal device 10 supporting the NTN communication function determines that access to the cell for the purpose of NTN communication is permitted when the value of cellBarredNTN indicates "not prohibited (not barred)." In other words, a terminal device 10 supporting the NTN communication function determines that access to the cell for the purpose of NTN communication is not permitted when the value of cellBarredNTN indicates "prohibited (barred)" or when cellBarredNTN is not set (notified).

[0073] cellBarredFixedVSAT is access restriction information used to instruct a terminal device 10 that performs NTN communication using a fixed-type small satellite earth station (Fixed VSAT (Very Small Aperture Terminal)) whether or not to prohibit access to the cell. If the value of cellBarredFixedVSAT indicates "not prohibited (not barred)", the terminal device 10 that is a fixed-type small satellite earth station determines that access to the cell for the purpose of NTN communication is permitted. In other words, if the value of cellBarredFixedVSAT indicates "prohibited (barred)" or if cellBarredFixedVSAT is not set (notified), the terminal device 10 that is a fixed-type small satellite earth station determines that access to the cell for the purpose of NTN communication is not permitted.

[0074] cellBarredMobileVSAT is access restriction information used to instruct a terminal device 10 that performs NTN communication using a portable small satellite earth station (Mobile VSAT) whether to prohibit access to the cell. If the value of cellBarredMobileVSAT indicates "not barred," the terminal device 10, which is a portable small satellite earth station, determines that access to the cell for the purpose of NTN communication is permitted. In other words, if the value of cellBarredMobileVSAT indicates "barred" or if cellBarredMobileVSAT is not set (notified), the terminal device 10, which is a portable small satellite earth station, determines that access to the cell for the purpose of NTN communication is not permitted.

[0075] cellBarredRedCap1Rx is access restriction information used to instruct a terminal device 10 that has reduced capability (RedCap) for IoT applications, particularly a RedCap terminal (RedCap UE) that has reduced the number of receiving antennas to one (1Rx), whether to prohibit access to the cell. A terminal device 10 with a 1Rx RedCap determines that access to the cell is permitted when the value of cellBarredRedCap1Rx indicates "not prohibited (not barred)." In other words, a terminal device 10 with a 1Rx RedCap determines that access to the cell is not permitted when the value of cellBarredRedCap1Rx indicates "prohibited (barred)."

[0076] cellBarredRedCap2Rx is access restriction information used to instruct a terminal device 10 that has reduced (RedCap) unnecessary capabilities (functions) for IoT applications, particularly a RedCap terminal (RedCap UE) that has reduced the number of receiving antennas to two (2Rx), whether to prohibit access to the cell. A terminal device 10 with a 2Rx RedCap determines that access to the cell is permitted when the value of cellBarredRedCap2Rx indicates "not prohibited (not barred)." In other words, a terminal device 10 with a 2Rx RedCap determines that access to the cell is not permitted when the value of cellBarredRedCap2Rx indicates "prohibited (barred)."

[0077] cellBarred-eRedCap1Rx is access restriction information used to instruct a terminal device 10 (enhanced RedCap: eRedCap) that has fewer support functions than a RedCap terminal, making it simpler and less costly, and in particular an eRedCap terminal (eRedCap UE) with a single receiving antenna (1Rx), whether to prohibit access to the cell. A terminal device 10 with 1Rx eRedCap determines that access to the cell is permitted if the value of cellBarred-eRedCap1Rx indicates "not prohibited (not barred)." In other words, a terminal device 10 with 1Rx eRedCap determines that access to the cell is not permitted if the value of cellBarred-eRedCap1Rx indicates "prohibited (barred)."

[0078] cellBarred-eRedCap2Rx is access restriction information used to instruct a terminal device 10, which has fewer support functions than a RedCap terminal and is simpler and less expensive, particularly an eRedCap terminal (eRedCap UE) with the number of receiving antennas reduced to two (2Rx), whether to prohibit access to the cell. A terminal device 10 with 2Rx eRedCap determines that access to the cell is permitted if the value of cellBarred-eRedCap2Rx indicates "not prohibited (not barred)." In other words, a terminal device 10 with 2Rx eRedCap determines that access to the cell is not permitted if the value of cellBarred-eRedCap2Rx indicates "prohibited (barred)."

[0079] "halfDuplexRedCapAllowed" is access restriction information used to instruct a RedCap terminal that supports only FDD half-duplex communication whether to prohibit access to the cell. A RedCap terminal device 10 that supports only FDD half-duplex communication determines that access to the cell is permitted if the value of "halfDuplexRedCapAllowed" indicates "true." In other words, a RedCap terminal device 10 that supports only FDD half-duplex communication determines that access to the cell is not permitted if "halfDuplexRedCapAllowed" is not set (notified).

[0080] The cellBarredNES is access restriction information used to instruct a terminal device 10 (Cell DTX / DRX UE) that supports cell-based discontinuous reception / discontinuous transmission (Cell-DTX / DRX), which is one of the NES functions, whether to prohibit access to the cell. A terminal device 10 that supports Cell-DTX / DRX determines that access to the cell is permitted if the cellBarred in the MIB is "barred" and the value of cellBarredNES indicates "not barred." In other words, a terminal device 10 that supports Cell-DTX / DRX determines that access to the cell is not permitted if the cellBarred in the MIB is "barred" and the cellBarredNES is not set (notified).

[0081] cellReservedForFutureUse is an identifier indicating that the cell is reserved for future functions. If the value of cellReservedForFutureUse indicates "true," the terminal device 10 determines that access to the cell is permitted. In other words, if cellReservedForFutureUse is not set (notified), the terminal device 10 determines that access to the cell is not permitted.

[0082] cellReservedForOtherUse is an identifier indicating that the cell has been reserved by a telecommunications carrier (operator) for other purposes. Other purposes include, for example, cells reserved for a non-public network (NPN). A terminal device 10 supporting the NPN function determines that access to the cell is permitted if the value of cellReservedForOtherUse of the cell indicates "true" and the cell belongs to an NPN network supported by the terminal device 10 itself. In other words, a terminal device 10 supporting the NPN function determines that access to the cell is not permitted if cellReservedForOtherUse is not set (notified).

[0083] cellReservedForOperatorUse is an identifier indicating that the cell is reserved by a telecommunications carrier for any purpose. If the value of cellReservedForOperatorUse indicates "not reserved," the terminal device 10 determines that access to the cell is permitted. In other words, if the value of cellReservedForOperatorUse indicates "reserved," the terminal device 10 determines that access to the cell is not permitted.

[0084] The above-described access restriction information may be set based on the type of terminal device 10 to which access restriction is applied, similar to the information included in the conventional SIB1. Furthermore, the access restriction information may be set by grouping the terminal devices 10 to which access restriction is applied. For example, supported functions may be grouped, such as RedCap and NTN, and access restriction may be performed on a group basis. As an example of a group, restriction may be performed using a RedCap group identifier that groups cellBarredRedCap1Rx, cellBarredRedCap2Rx, cellBarred-eRedCap1Rx, cellBarred-eRedCap2Rx, and halfDuplexRedCapAllowed, or using an NTN group identifier that groups cellBarredATG, cellBarredNTN, cellBarredFixedVSAT, and cellBarredMobileVSAT.

[0085] The access restriction information may be notified in a bitmap format (for example, 0 indicates "restricted" and 1 indicates "unrestricted." The meaning of the bits may be reversed) or in a list format. In addition, the access restriction information may be notified for each cell or for each group of multiple cells. When notified for each group of multiple cells, the information may be notified for each PLMN (Public Land Mobile Network). The base station device 20 may notify the information including part of the access restriction information shown in FIG. 5.

[0086] Alternatively, the base station device 20A may transmit, instead of the access restriction information, information indicating the type of the NES cell of the base station device 20B to the terminal device 10. The cell type is information indicating that the cell supports a specific function, such as an NTN cell or a RedCap cell, and is set for each NES cell information or for each cell group.

[0087] If the terminal device 10 determines that access to the cell is not permitted based on the NES cell access information (access restriction information) notified from the base station device 20A, the terminal device 10 regards the base station device 20B (NES cell 20B-1) as a barred cell until a predetermined time (e.g., 300 seconds) has elapsed, and does not regard the base station device 20B (NES cell 20B-1) as a target for cell reselection. In other words, the terminal device 10 determines that the base station device 20B (NES cell 20B-1) is not to be considered as an appropriate cell on which camping can be performed, or as a target cell for UL-WUS transmission.

[0088] The terminal device 10 that has deemed the base station device 20B (NES cell 20B-1) a barred cell may temporarily apply an offset value to the base station device 20B (NES cell 20B-1), or to all NES cells on the same frequency as the base station device 20B (NES cell 20B-1), or to each NES cell identified by the NES cell information, to prevent the NES cells from becoming candidate cells for new cell reselection. The time for applying the offset value may be, for example, a predefined fixed value (e.g., 300 seconds), or a value notified by the base station device 20 via an RRC message. The base station device 20 may notify the terminal device 10 using an RRC message as to whether or not to apply the offset value. When the terminal device 10 reacquires NES cell access information corresponding to the NES cell 20B-1 that it has deemed a barred cell, it may cancel (cancel, reset) its determination of the barred cell.

[0089] Furthermore, the terminal device 10 that regards the base station device 20B (NES cell 20B-1) as a barred cell may temporarily regard the priority of the frequency of the base station device 20B (NES cell 20B-1) as the lowest priority. The time period for regarding the frequency as the lowest priority may be, for example, a predefined fixed value (e.g., 300 seconds) or a value notified by the base station device 20 via an RRC message.

[0090] Furthermore, the terminal device 10 may determine a target cell for cell reselection based on a situation in which it is determined that access is not permitted, with respect to whether or not the cell is to be considered as a target for cell reselection. For example, in the following cases, the terminal device 10 may target either (a) only the base station device 20B (NES cell 20B-1), or (b) all NES cells on the same frequency as the base station device 20B (NES cell 20B-1), or NES cells identified by the NES cell information, in the following cases: (1) when the random access procedure fails because the number of UL-WUS transmissions reaches a set maximum number of transmissions, (2) when it is determined that access is not permitted based on access restriction information, (3) when the PLMN ID received from the On-demand SIB1 is different from an accessible registered network, or (4) when a random access procedure other than UL-WUS has failed.

[0091] That is, when the terminal device 10 detects (1) to (4), it may determine that either cell (a) or (b) is an appropriate cell on which it can camp, or that it does not consider it as a target cell for UL-WUS transmission. Which cell is the target cell in each of the above-mentioned situations may be defined in advance, or the base station device 20 may set it in the terminal device 10 using an RRC message. Note that for (1) and (4), which are likely to be problems on the terminal device 10 side, it is preferable to use (a), in which the target cell is limited, and for (2) and (3), which are likely to be problems on the network side, it is preferable to use (b), in which the range of target cells is wide, but this combination is not limiting.

[0092] 5 may be notified for each cell, or the required bit amount may be reduced using the following method. For example, the base station device 20A may compare the access restriction information of the base station device 20A and the base station device 20B and notify the terminal device 10 of only the difference information. Furthermore, when the access restriction information of the base station device 20A and the base station device 20B is the same, the base station device 20A may notify the terminal device 10 of a 1-bit identifier for each NES cell 20B-1 indicating that the access restriction information of the base station device 20B (NES cell 20B-1) is the same as that of the base station device 20A (normal cell 20A-1).

[0093] As shown in Fig. 6, the base station device 20A may group one or more NES cells (NES cell information) for each piece of access restriction information and notify them. Fig. 6 is a diagram showing an example of a method for notifying cell access restriction information. Fig. 6 shows that 1 to m (m is a natural number) pieces of access restriction information are associated with 1 to n (n is a natural number) pieces of NES cell information, respectively.

[0094] In the example of Fig. 6, the NES cells to which access restriction information 1 applies are the NES cell 20-B uniquely identified by the NES cell information 1 and another NES cell 20-B uniquely identified by the NES cell information 2. Similarly, the NES cells to which access restriction information 2 applies are the NES cell 20-B uniquely identified by the NES cell information 2 and the NES cell information 4. The access restriction information in Fig. 6 may be information that directly indicates information elements included in a conventional MIB or SIB1 (e.g., cellBarred and cellBarred2RxXR), or may be information divided into groups according to the functions to be supported.

[0095] Returning to Figure 4, if the terminal device 10 determines (judges, decides) that access to the cell is permitted as a result of the access judgment in step S102, it transmits UL-WUS to the base station device 20B based on the UL-WUS setting information (step S103).

[0096] The base station device 20B (NES cell 20B-1) receives the UL-WUS transmitted from the terminal device 10 and determines whether to transmit an On-demand SIB1. If it determines that transmission of the On-demand SIB1 is necessary, the base station device 20B transmits a Random Access Response (RAR) using downlink resources corresponding to the UL-WUS (step S104). The terminal device 10 that transmitted the UL-WUS starts monitoring the corresponding PDCCH (RA-RNTI) in a predetermined interval (reception window length) and attempts to detect the Random Access Response from the base station device 20B. If the terminal device 10 successfully receives the Random Access Response and the response contains preamble ID information (RAPID: Random Access Preamble ID) of the UL-WUS (or PRACH) transmitted by the terminal device 10, the On-demand SIB1 request is deemed successful.

[0097] Next, the base station device 20B (NES cell 20B-1) schedules the On-demand SIB1 and starts transmission within the cell (step S105). The terminal device 10 starts monitoring the PDCCH related to the scheduling of the On-demand SIB1 set in the MIB or the random access response, and attempts to acquire the On-demand SIB1. The terminal device 10 receives the On-demand SIB1, applies the acquired cell common information, camps on the cell (cell reselection), and ends the On-demand SIB1 procedure.

[0098] Note that the terminal device 10 may check (monitor) whether the cell is transmitting On-demand SIB1 before transmitting UL-WUS, and may add a decision to transmit UL-WUS only if the cell has not transmitted On-demand SIB1.

[0099] Furthermore, the base station device 20 may determine the terminal devices 10 that are subject to access restriction in the NES cell by setting and notifying PRACH resource information (e.g., preamble information) corresponding to the access restriction information included in the UL-WUS setting information. For example, if a PRACH resource corresponding to a terminal device 10 with a RedCap of 1Rx is set, the terminal device 10 with a RedCap of 1Rx may interpret that cellBarredRedCap1Rx is set as "not prohibited." In other words, if a PRACH resource corresponding to a terminal device 10 with a RedCap of 1Rx is not set, the terminal device 10 with a RedCap of 1Rx may interpret that cellBarredRedCap1Rx is set as "prohibited."

[0100] As described above, according to the first embodiment, the base station device 20 can notify the terminal device 10 of access restriction information indicating whether or not the cell is access-restricted via another base station device 20. The terminal device 10 can determine in advance whether or not access is restricted for a cell that transmits system information (SIB1) as appropriate for power saving, and can therefore suppress unnecessary SIB1 transmission requests to the base station device 20. As a result, the power saving efficiency of the base station device 20 can be improved.

[0101] Second Embodiment A second embodiment will be described. Note that a description of configurations, functions, or procedures common to the first and second embodiments will be omitted. In other words, the following mainly describes the differences from the first embodiment.

[0102] FIG. 7 is an example of a sequence diagram showing an On-demand SIB1 procedure between the terminal device 10 and the base station device 20 according to the second embodiment.

[0103] 7 may be the terminal device 10 or base station device 20 having the same functions as those in FIG. 4, and therefore details thereof will be omitted. However, the base station device 20 (20A, 20B) does not have to include the access restriction information exemplified in FIG. 5 in the NES cell access information.

[0104] The base station device 20B provides the base station device 20A with NES cell access information via a transmission path between the base station devices 20 (step S200). The NES cell access information includes at least NES cell information that uniquely identifies the NES cell (for example, a combination of a physical cell identifier (PID) and downlink frequency information) and setting information related to UL-WUS (UL-WUS setting information).

[0105] The base station device 20A transmits (transfers, notifies) to the cell in which it can access the base station device 20A and includes at least one piece of NES cell access information received from the base station device 20B (step S201). The terminal device 10 uses the received NES cell access information to make an access decision (first access decision) as to whether or not to transmit UL-WUS to the base station device 20B (NES cell 20B-1) (step S202).

[0106] Here, the terminal device 10 compares the reception quality of the base station device 20A (normal cell 20A-1) which is the serving cell with the reception quality of one or more base station devices 20B (NES cell 20B-1) which are candidates for cell reselection (cell reselection), and performs an access judgment on whether to transmit UL-WUS to the cell with the best reception quality. Note that if the terminal device 10 has not been notified (or does not hold) the same NES cell information as the cell detected by cell search, the terminal device 10 does not need to consider the detected cell as a target cell for cell reselection.

[0107] The process of the terminal device 10 in step S202 regarding the access determination will be described. The terminal device 10 measures the reception quality of the base station device 20B and simultaneously acquires MIB information from the SSB. The terminal device 10 then determines whether the cell is accessible based on the access restriction information notified in the MIB. In other words, the terminal device 10 uses the MIB information to determine whether the base station device 20B is a suitable cell for cell reselection. For example, the terminal device 10 interprets the SSB subcarrier offset value (Kssb) included in the MIB of the NES cell as information indicating access restriction, thereby determining whether the base station device 20B is accessible.

[0108] More specifically, the SSB subcarrier offset value (Kssb) ranges from 0 to 23 if the operating frequency is in the first frequency range (FR1) up to 7125 MHz, and from 0 to 11 if the operating frequency is in the second frequency range (FR2) from 24.25 GHz to 71 GHz. However, the base station device 20B can notify the terminal device 10 of access restriction information by setting a value outside the above range as the Kssb value. For example, specifying a value of "25" in FR1 may mean that access for NTN and 2RX XR is restricted in the cell. The combination of the Kssb value and the type of restricted terminal device 10 (type or restricted supported functions) can also be any other combination. These combinations are assumed to be predetermined and shared between the base station device 20 and the terminal device 10.

[0109] Furthermore, the terminal device 10 may ignore the value of cellBarred included in the MIB of the NES cell that matches the NES cell information acquired in step S201 (i.e., the cell whose downlink frequency and PCI match).

[0110] The terminal device 10 receives the MIB of the NES cell 20B-1 corresponding to the NES cell information, and if either the value of the SSB subcarrier offset (Kssb) or the value of the PDCCH setting information for receiving SIB1 is an unspecified value (reserved bit), it may determine that access to the NES cell 20B-1 is not permitted.

[0111] When the terminal device 10 receives a PDCCH for receiving SIB1 and the value of a specified DCI of the PDCCH indicates that (on-demand) SIB1 transmission will not be performed, the terminal device 10 may determine that access to the NES cell 20B-1 is not permitted.

[0112] 7, if the terminal device 10 determines (judges, decides) that access to the cell is permitted as a result of the access judgment in step S202, it transmits a UL-WUS to the base station device 20B based on the UL-WUS setting information (step S203). Note that the base station device 20 may have notified the terminal device 10 of the PRACH resource (transmission resource information) based on the access restriction information of the base station device 20B as the UL-WUS setting information in step S201.

[0113] The base station device 20B (NES cell 20B-1) that has received the UL-WUS transmitted from the terminal device 10 determines whether to transmit an On-demand SIB1. If it determines that transmission of the On-demand SIB1 is necessary, the base station device 20B transmits a Random Access Response (RAR) using downlink resources corresponding to the UL-WUS (step S204). The terminal device 10 that transmitted the UL-WUS starts monitoring the corresponding PDCCH (RA-RNTI) in a predetermined section (reception window length) and attempts to detect a random access response from the base station device 20B.

[0114] When the terminal device 10 detects a random access response, it performs another process (second access determination) related to access determination (step S205). If the terminal device 10 successfully receives the random access response and the response contains preamble ID information (RAPID: Random Access Preamble ID) of the UL-WUS (or PRACH) transmitted by the terminal device 10, the terminal device 10 considers the On-demand SIB1 request to be successful. The base station device 20B (NES cell 20B-1) schedules the On-demand SIB1 and starts transmission within the cell (not shown). The terminal device 10 starts monitoring the MIB or the PDCCH corresponding to the On-demand SIB1 set in the random access response, and attempts to acquire the On-demand SIB1. The terminal device 10 receives the On-demand SIB1, applies the acquired cell common information, camps on the cell (cell reselection), and ends the On-demand SIB1 procedure.

[0115] On the other hand, when the base station device 20B receives the UL-WUS and determines that it is necessary to transmit access restriction information, it transmits a random access response (RAR) to the terminal device 10 using downlink resources corresponding to the UL-WUS (step S204). At this time, the base station device 20B may transmit a random access response including some or all of the access restriction information. The access restriction information included in the random access response may be in bitmap format or list format. It may also be information indicating a group of terminal devices 10 that are restricted, or information indicating the type of NES cell that is restricted. The base station device 20B may also transmit the random access response including, as access restriction information, information indicating that it is not necessary to transmit a UL-WUS.

[0116] If the random access response includes access restriction information, the terminal device 10 uses the access restriction information to determine whether access to the base station device 20B (NES cell 20B-1) is possible. If, as a result of the access determination in step S205, the terminal device 10 determines (determines, decides) that access to the cell is permitted, the terminal device 10 transmits a UL-WUS to the base station device 20B based on the UL-WUS setting information (not shown). If, as a result of the access determination in step S205, the terminal device 10 determines that access to the cell is not permitted, the terminal device 10 stops transmitting the UL-WUS and considers the base station device 20B (NES cell 20B-1) a barred cell until a predetermined time (e.g., 300 seconds) has elapsed, and does not consider it a target for cell reselection. In other words, the terminal device 10 determines that the base station device 20B (NES cell 20B-1) is not to be considered as a suitable cell on which to camp or as a target cell for transmitting a UL-WUS.

[0117] As described above, according to the second embodiment, the base station device 20 can notify the terminal device 10 of access restriction information indicating whether or not the cell is access-restricted, without transmitting the SIB1 of the base station device 20. The terminal device 10 can determine in advance whether or not access is restricted for a cell that transmits system information (SIB1) as appropriate for power saving, without acquiring the SIB1 of the base station device 20. As a result, the power saving efficiency of the base station device 20 can be improved.

[0118] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and the present invention also includes equivalents. Furthermore, the aspects / embodiments described in this specification may be used alone, in combination, or switched depending on the implementation. For example, the base station device 20 may notify information indicating access permission instead of information indicating access denial.

[0119] <Hardware Configuration of Each Device in Each Embodiment> The hardware configuration of each device in the wireless communication system of each embodiment will be described with reference to FIGS. 8 and 9. FIG.

[0120] 8 is a diagram illustrating an example of the hardware configuration of the terminal device 10. As illustrated in FIG. 8, the terminal device 10 includes, as hardware components, a radio frequency (RF) circuit 32 including an antenna 31, a central processing unit (CPU) 33, and a memory 34. The terminal device 10 may further include a display device such as a liquid crystal display (LCD) connected to the CPU 33. The memory 34 includes at least one of a random access memory (RAM) such as a synchronous dynamic random access memory (SDRAM), a read only memory (ROM), and a flash memory, and stores programs, control information, and data signals.

[0121] The correspondence between the functional configuration of the terminal device 10 shown in Fig. 2 and the hardware configuration of the terminal device 10 shown in Fig. 8 will be described. The transmitting / receiving antenna unit 19, the transmitter unit 17, and the receiver unit 15 are realized by, for example, an RF circuit 32, or an antenna 31 and an RF circuit 32. The control unit 13 and the processing unit 11 are realized by, for example, a CPU 33, a memory 34, a digital electronic circuit (not shown), etc. Examples of the digital electronic circuit include an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), and a large scale integration (LSI).

[0122] 9 is a diagram illustrating an example of the hardware configuration of the base station device 20. As shown in FIG. 9, the base station device 20 includes, as hardware components, an RF circuit 42 equipped with an antenna 41, a CPU 43, a DSP 44, a memory 45, and a network IF (Interface) 46. The CPU 43 is connected via a bus to enable input and output of various signals and data signals. The memory 45 includes at least one of a RAM such as an SDRAM, a ROM, and a flash memory, and stores programs, control information, and data signals.

[0123] The correspondence between the functional configuration of the base station device 20 shown in Fig. 3 and the hardware configuration of the base station device 20 shown in Fig. 9 will be described. The transmitting / receiving antenna unit 29, the transmitter 27, and the receiver 25 are realized by, for example, an RF circuit 42, or an antenna 41 and an RF circuit 42. The control unit 23 and the processing unit 21 are realized by, for example, a CPU 43, a DSP 44, a memory 45, a digital electronic circuit (not shown), etc. Examples of the digital electronic circuit include an ASIC, an FPGA, and an LSI.

[0124] 1 Wireless communication system 10 Terminal device 20, 20A, 20B Base station device 20A-1 Normal cell 20B-1 NES cell 30 Core network 11, 21 Processing unit 13, 23 Control unit 15, 25 Receiving unit 17, 27 Transmitting unit 19, 29 Transmitting and receiving antenna unit 31, 41 Antenna 32, 42 RF circuit 33, 43 CPU 34, 45 Memory 44 DSP 46 Network IF 111, 211 Radio resource processing unit 113 Control processing unit 213 SIB1 control processing unit

Claims

1. A terminal device capable of communicating with a first base station device and a second base station device, comprising: a control unit that determines whether access to the second base station device is permitted based on the type of the terminal device, configuration information of a request signal requesting the transmission of essential system information of the second base station device, information indicating access restrictions for the cell of the second base station device obtained from the first base station device, and measured reception quality of the signal of the second base station device; a transmission unit that transmits the request signal to the second base station device corresponding to the configuration information based on the determination; and a reception unit that receives the essential system information of the second base station device transmitted in response to the request signal.

2. The terminal device according to claim 1, wherein the essential system information of the second base station device requested in the request signal is System Information Block Type 1 (SIB1).

3. The terminal device described in claim 2, characterized in that if it determines that access to the second base station device is permitted based on the information indicating the access restriction, it starts transmitting the request signal to the second base station device, but if it determines that access is not permitted, it does not transmit the request signal to the second base station device.

4. The terminal device according to claim 3, wherein the information indicating the access restriction is access restriction information corresponding to the type of the terminal device.

5. The terminal device according to claim 3, wherein the information indicating the access restriction is transmission resource information for the request signal corresponding to the type of the terminal device.

6. The terminal device described in claim 3, characterized in that if it determines that access to the cell of the second base station device is not permitted, it determines that access to the cells of all of the second base station devices indicated in the request signal is not permitted.

7. A base station device in a communication system including a first cell that periodically transmits essential system information and a second cell that transmits the essential system information in response to a request from a terminal device, comprising: a receiver that receives information indicating access restriction of the second cell and configuration information for a request signal for essential system information of the second cell used by the terminal device; a controller that sets the information indicating access restriction of the second cell to allow the terminal device to determine whether the second cell is accessible based on the type of the terminal device, the configuration information for the request signal acquired by the terminal device from the first cell, the information indicating access restriction of the second cell acquired by the terminal device from the first cell, and measured reception quality of a signal from a second base station device; and a transmitter that transmits the information indicating the access restriction and the configuration information for the request signal to the terminal device using the first cell.

8. The base station device according to claim 7, wherein the essential system information of the second base station device requested in the request signal is System Information Block Type 1 (SIB1).

9. The base station device according to claim 8, wherein the information indicating the access restriction is access restriction information corresponding to the type of the terminal device.

10. The base station device according to claim 8, wherein the information indicating the access restriction is transmission resource information for the request signal corresponding to the type of the terminal device.

11. A control method for a terminal device capable of communicating with a first base station device and a second base station device, comprising: a control means for determining whether access to the second base station device is permitted based on the type of the terminal device, setting information of a request signal requesting transmission of essential system information of the second base station device, information indicating access restrictions for the cell of the second base station device obtained from the first base station device, and measured reception quality of the signal of the second base station device; a transmission means for transmitting the request signal to the second base station device corresponding to the setting information based on the determination; and a reception means for receiving the essential system information of the second base station device transmitted in response to the request signal.

12. A method for controlling a base station device in a communication system including a first cell that periodically transmits essential system information and a second cell that transmits the essential system information in response to a request from a terminal device, the method comprising: a receiving means for receiving from the second cell information indicating access restriction of the second cell and configuration information for a request signal for essential system information of the second cell used by the terminal device; a control means for setting the information indicating access restriction of the second cell to allow the terminal device to determine whether or not the second cell is accessible based on the type of the terminal device, the configuration information for the request signal acquired by the terminal device from the first cell, the information indicating access restriction of the second cell acquired by the terminal device from the first cell, and measured reception quality of a signal from the second base station device; and a transmitting means for transmitting the information indicating the access restriction and the configuration information for the request signal to the terminal device using the first cell.

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