Terminal device, base station device, and control method

Abstract

The present invention improves the efficiency of power saving related to wireless communication between a terminal device and base station devices. The terminal device comprises a reception unit, a processing unit, and a transmission unit. The reception unit receives, from a first base station device, a request signal configuration for requesting that a second base station device perform on-demand transmission of first system information. When holding a request signal configuration corresponding to the second base station device and performing a control procedure accompanied by the acquisition of the first system information, the processing unit acquires, on the basis of the request signal configuration and from the request signal configuration or second system information pertaining to the second base station device, physical downlink control channel information necessary to acquire the first system information. On the basis of whether the acquisition of the first system information of the second base station device performed using the physical downlink control channel information is successful, the transmission unit transmits, to the second base station device, a physical random access channel pertaining to the control procedure.

Description

Terminal device, base station device, and control method

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

[0002] In the current network, traffic from mobile terminals (such as smartphones and feature phones) occupies most of the network resources. Also, the traffic used by mobile terminals tends to increase in the future.

[0003] Also, in addition to the traffic used by mobile terminals, for example, the deployment of IoT (Internet of Things) services (such as traffic systems, monitoring systems for smart meters and devices, etc.) is underway. Therefore, the network is required to support services with various requirement conditions. To support such diverse services, for example, in the communication standard of the fifth generation mobile communication (5G or NR (New Radio)), support for many use cases classified into eMBB (Enhanced Mobile BroadBand), Massive MTC (Machine Type Communications), and URLLC (Ultra-Reliable and Low Latency Communications) is assumed, and the standard has been established.

[0004] In the 3rd Generation Partnership Project (3GPP), which is an international standardization project, the extended technology of the above communication standard is still continuously studied and standardized.

[0005] In 3GPP, in order to reduce the power consumption of the network side (that is, base station devices and core network devices), the technology of NES (Network Energy Savings) is being studied (Non-Patent Document 1). Hereinafter, a cell (base station device) corresponding to the function of NES, that is, a cell supporting the function of NES is also called an NES cell.

[0006] 3GPP TR 38.864 V18.0.0 (2022-12) R2-2408294

[0007] Generally, base station equipment broadcasts system information (system information) within the cell as information commonly used by terminal devices within the cell. System information is also called broadcast information. In 3GPP, as one of the network power reduction technologies, a method is being considered to reduce the power consumption of base station equipment by introducing On-demand SIB1 (System Information Block Type 1), which is transmitted as needed (on-demand transmission) from the NES cell in response to requests from terminal devices, in addition to SIB1, which is one of the broadcast information transmitted periodically. For example, Non-Patent Document 2 discloses an example of a setting (SIB1 request configuration) for requesting On-demand SIB1 in a terminal device and a procedure for receiving On-demand SIB1.

[0008] Non-Patent Document 2 discloses that in the RRC Restabilization procedure after detecting a wireless link failure, an RRC restabilization procedure using SIB1 request setting information is performed for the NES cell. However, if the SIB1 request setting information is updated during the RRC restabilization procedure, the terminal device may not have acquired On-demand SIB1 (or SIB1), which can lead to an inappropriate uplink transmission to the NES cell. Non-Patent Document 2 does not appear to mention any solution to this problem.

[0009] One aspect of the present invention is to improve the efficiency of power saving related to wireless communication between terminal equipment and base station equipment when applying network power reduction technology 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, comprising: a receiving unit that receives a request signal setting from the first base station device requesting the second base station device to transmit first system information on demand; a processing unit that, if it has a request signal setting corresponding to the second base station device and is performing a control procedure involving the acquisition of first system information, acquires physical downlink control channel information necessary for acquiring first system information from the second system information of the second base station device or the request signal setting based on the request signal setting; and a transmitting unit that transmits a physical random access channel relating to the control procedure to the second base station device based on the success or failure of acquiring the first system information of the second base station device using the physical downlink control channel information.

[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 first system information and a second cell that transmits first system information on demand in response to a request from a terminal device, comprising: a transmitting unit that transmits a request signal setting from the first cell to the terminal device requesting on-demand transmission of first system information in the second cell; a processing unit that, when the terminal device has a request signal setting corresponding to the second cell and performs a control procedure involving the acquisition of first system information in the second cell, sets information that causes the terminal device to determine that physical downlink control channel information necessary for acquiring first system information can be acquired using second system information of the second cell or request signal setting; and a receiving unit that receives a physical random access channel relating to a control procedure transmitted to the second cell based on the success or failure of acquiring first system information in the second cell using physical downlink control channel information.

[0012] According to the above-described embodiment, when applying network power reduction technology, the efficiency of power saving related to wireless communication between terminal equipment and base station equipment can be improved.

[0013] This figure shows an example of the configuration of a wireless communication system related to the embodiment. This figure shows an example of the functional configuration of a terminal device related to the embodiment. This figure shows an example of the functional configuration of a base station device related to the embodiment. This figure shows an example of the On-demand SIB1 acquisition procedure. This figure shows an example of the UL-WUS transmission procedure. This figure shows an example of the RRC reconnection procedure for an On-demand SIB1 transmission cell. This figure shows an example of the hardware configuration of a terminal device. This figure shows an example of the hardware configuration of a base station device.

[0014] Embodiments of the present invention will be described in detail below with reference to the drawings. The problems and embodiments described herein are examples and do not limit the scope of the rights of this application. In particular, even if the wording of the description differs, the technology of this application is applicable as long as it is technically equivalent and does not limit the scope of the rights. Furthermore, each embodiment can be combined as appropriate, as long as there is no inconsistency in the processing content.

[0015] The wireless communication system according to embodiments of the present invention may utilize known technologies as appropriate. Applicable known technologies may include, for example, 5G (NR), Beyond 5G, 5G-Advanced, or other wireless communication methods, or future wireless communication methods such as 6G. The wireless communication system according to embodiments of the present invention targets NR, but is not limited thereto. For example, embodiments of the present invention are also applicable to LTE (Long Term Evolution) and LTE-Advanced. Furthermore, it is also applicable to wireless communication systems that use NR as part of the wireless communication system.

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

[0017] Hereinafter, embodiments of the base station equipment, terminal equipment, and wireless communication system disclosed in this application will be described with reference to the drawings. Note that the following embodiments are not intended to limit the disclosed technology.

[0018] <Wireless Communication System> Figure 1 is a diagram showing 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 consists of, for example, a terminal device 10, base station devices 20A and 20B, and a core network 30. The wireless communication system 1 is, for example, a wireless communication system that corresponds to NES, in other words, a wireless communication system that supports the functions of NES. Base station device 20A is a base station device 20 (first base station device) that notifies information for accessing base station device 20B which supports NES functions. On the other hand, base station device 20B is a base station device 20 (second base station device) which supports NES functions, and access is attempted based on information from base station device 20A. When base station devices 20A and 20B are not distinguished, they are simply referred to as base station device 20. In addition, there may be multiple terminal devices 10.

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

[0020] In the wireless communication system 1, the base station equipment 20 and the core network 30 provide wireless communication services to the terminal device 10. The core network 30 has functions such as managing service subscriber information, managing sessions for voice calls, and managing the 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 equipment 20.

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

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

[0023] The area (coverage area) formed by the base station device 20 is sometimes called a "cell." E-UTRA and 5G are cellular communication systems constructed from multiple cells. In the wireless communication system according to the embodiment of the present invention, either TDD (Time Division Duplex) or FDD (Frequency Division Duplex) may be applied, and different methods may be applied to each cell.

[0024] Hereinafter, a cell configured by the base station device 20A will also be referred to as a normal cell 20A-1 (first cell). A normal cell 20A-1 is, for example, a cell that does not support NES, or an NES cell (described later) to which power-saving technology has not been applied. 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 predetermined power-saving technology will also be referred to as an NES cell 20B-1 (second cell). In the sleep state, for example, the NES cell 20B-1 achieves power saving by stopping the transmission and reception of physical signals and physical channels other than predetermined ones, thereby cutting off or reducing the standby power of the wireless equipment inside the base station device 20B. The predetermined physical signals and physical channels are, for example, PDCCH and PDSCH related to On-demand SIB1.

[0025] The normal cell 20A-1 is an anchor cell that provides (transfers, notifies) the terminal device 10 with the information necessary for the terminal device 10 to access the NES cell 20B-1. The NES cell 20B-1 also provides the normal cell 20A-1 with at least control information used by the terminal device 10 to determine whether it can access the NES cell 20B-1, control information for receiving the On-demand SIB1 transmitted by the NES cell 20B-1, and uplink wake-up signal (UL-WUS (UL-Wake Up Signal)) setting information (described later) for requesting the On-demand SIB1 from the NES cell 20B-1. In the following description, unless otherwise specified, the above-mentioned SIB1 request setting information and UL-WUS setting information shall be treated as interchangeable and synonymous setting information.

[0026] In the example shown in Figure 1, a normal cell 20A-1 is illustrated as containing an NES cell 20B-1. However, the size and positional relationship of these two cells are merely illustrative, and other correspondences are possible. For example, the size of the normal cell 20A-1 and the NES cell 20B-1 may be the same, or the NES cell 20B-1 may be larger. A normal cell 20A-1 may contain multiple NES cells 20B-1.

[0027] The sleep state is a state in which, for example, 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 equipment related to transmission and reception is suppressed, and the base station device 20B does not transmit some messages, and does not transmit or receive corresponding physical signals or physical channels. Furthermore, when the sleep state of the NES cell 20B-1 is released (the application of a predetermined power saving technology is stopped), or when the sleep state is temporarily released, it enters a non-sleep state and transitions to a cell capable of normal wireless communication (for example, a normal cell 20A-1).

[0028] Terminal device 10 is a communication device that wirelessly connects to base station device 20A or base station device 20B and transmits and receives data. Furthermore, terminal device 10 is a communication device that corresponds to the functions of NES, that is, a communication device that supports the functions of NES.

[0029] Furthermore, the NES cell may include, for example, a base station device 20B that is in a sleep state, and a base station device 20B that may be in a sleep state. Also, the normal cell 20A-1 and the NES cell 20B-1 may each be, for example, cells under the same base station device 20, or cells under different base station devices 20.

[0030] The base station device 20 may be configured as, for example, a CU (Centralized Unit), a DU (Distributed Unit), and a RU (Radio Unit). The CU is connected to the 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 implemented, for example, by a front-haul interface (F1 interface). Multiple DUs may be connected to a single CU.

[0031] In the example shown in Figure 1, the 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 (transferred) from the base station device 20 to the terminal device 10.

[0032] The 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) at the Radio Resource Control (RRC) layer. Furthermore, the terminal device 10 and the base station device 20 transmit and receive MAC control elements (MAC CE) at the Medium Access Control (MAC) layer.

[0034] RRC messages are transmitted as RRC PDUs (Protocol Data Units) and mapped to logical channels (LCHs) such as the Common Control Channel (CCCH), Dedicated Control Channel (DCCH), Paging Control Channel (PCCH), Broadcast Control Channel (BCCH), or Multicast Control Channel (MCCH).

[0035] A 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 with, for example, 8 bits of header information added, and a MAC PDU contains one or more MAC subPDUs.

[0036] Next, as physical channels and physical signals related to the embodiment, there are at least the following: synchronization signals (Primary Synchronization Signal, Secondary Synchronization Signal), Physical Broadcast Channel (PBCH), Physical Random Access Channel (PRACH), Physical Downlink Control Channel (PDCCH), Channel State Information-Reference Signal (CSI-RS), Physical Uplink Control Channel (PUCCH), Physical Downlink Shared Channel (PDSCH), Physical Uplink Shared Channel (PUSCH), Scheduling Reference Signal (SRS), and Demodulation Reference Signal (DMRS), but a detailed explanation is omitted.

[0037] <Terminal Device> Figure 2 is a diagram showing an example of the functional configuration of a terminal device 10 related to the embodiment. As shown in Figure 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 is configured to include, for example, a wireless resource processing unit 111 and a control processing unit 113. Note that the functional configuration of the terminal device 10 shown in Figure 2 is merely an example, and the functional classifications and names of each functional block may differ as long as they can perform the operations related to the embodiment. In addition, there may be one or more blocks that realize other functions.

[0038] The processing unit 11 generates control information for controlling the receiving unit 15 and the transmitting unit 17, for example, and outputs it to the control unit 13. The processing unit 11 executes processing related to the wireless resource control layer, the Service Data Adaptation Protocol (SDAP) layer, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (RLC) layer, and the media access control layer, for example.

[0039] The wireless resource processing unit 111 manages various setting information (RRC parameters, information elements (IE)) of the terminal device 10. For example, the wireless resource processing unit 111 generates information to be placed on each channel of the physical uplink and outputs this information to the transmission unit 17. In addition, based on instructions from the base station device 20, the wireless resource processing unit 111 performs the following: measurement of in-service cells and surrounding cells, start and stop of transmission and reception processing, DL synchronization procedures (cell search, cell selection / cell reselection), UL synchronization procedures (random access procedures), UL-WUS transmission procedures, acquisition and reacquisition of system information, event evaluation related to handover, a series of processes related to handover, a series of processes related to On-demand SIB1 acquisition, and a series of processes related to RRC reconnection. Note that RRC reconnection may also be called RRC re-establishment.

[0040] The control processing unit 113 executes a control process to determine whether the cell is an NES cell based on the UL-WUS settings. The control processing unit 113 also executes a control process to determine how to receive the On-demand SIB1 based on the UL-WUS settings and the information in the NES cell's Master Information Block (MIB). Furthermore, the control processing unit 113 executes a control process to determine whether UL-WUS transmission is necessary based on instructions from the radio resource processing unit 111 or from the base station device 20.

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

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

[0043] The transmitting unit 17 generates, for example, a physical uplink signal based on the control signal given from the control unit 13, and performs encoding, modulation, etc. on the physical uplink signal or the physical uplink channel given from the processing unit 11. The transmitting unit 17 multiplexes various signals and transmits them to the base station device 20 via the transceiver antenna unit 19.

[0044] Note that 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 described later. Also, the processing unit 11 and the control unit 13 may be realized by one processor system or by a plurality of processor systems. Alternatively, the processing unit 11 and the control unit 13 may be realized by a DSP (Digital Signal Processor) or a hardware circuit or the like.

[0045] <Base Station Device>FIG. 3 is a diagram showing an example of the functional configuration of the base station device 20 according to the embodiment. As shown 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 is configured to include, for example, a radio resource processing unit 211 and a SIB1 control processing unit 213. Note that the functional configuration of the base station device 20 shown in FIG. 3 is merely an example, and the functional classification and the names of the functional blocks may be different as long as the operations related to the embodiment can be executed. Also, one or more blocks for realizing other functions may exist.

[0046] The processing unit 21 generates, for example, control information for controlling the receiving unit 25 and the transmitting unit 27, and outputs it to the control unit 23. The processing unit 21 executes processes related to, for example, the radio resource control layer, the service data application protocol layer, the packet data convergence 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, RRC messages, and MAC control elements arranged in the physical downlink shared channel PDSCH, and outputs them to the transmitting unit 27. Also, the radio resource processing unit 211 generates control signals or control data arranged in the physical downlink control channel PDCCH, and outputs them to the transmitting unit 27. Further, the radio resource processing unit 211 manages various setting information of the terminal device 10. Based on signals from the terminal device 10 or notifications by RRC messages, the radio resource processing unit 211 executes start and stop of transmission / reception processing, start of UL synchronization procedures (random access procedures), update of system information, start and stop of On-demand SIB1 transmission, adjustment of the transmission angle of the beam, generation of parameters related to UL-WUS transmission procedures, etc.

[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 for determining the necessity of On-demand SIB1 transmission based on an instruction from an upper layer or reception of UL-WUS transmitted from the terminal device 10.

[0049] The control unit 23 performs various controls on the base station device 20. For example, the control unit 23 generates control signals or control data to control the receiving unit 25 and the transmitting unit 27 based on control information from the processing unit 21. The control unit 23 also controls downlink transmission to the terminal device 10 corresponding to On-demand SIB1 based on decision information regarding 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 core network 30 via the transmitting / receiving antenna unit 29, based on control signals provided by the control unit 23. The receiving unit 25 outputs the decoded information to the processing unit 21.

[0051] The transmitting unit 27 generates, for example, a downlink reference signal based on a control signal provided by the control unit 23. The transmitting unit 27 transmits a signal to the terminal device 10 via the transmitting / receiving antenna unit 29 by encoding, modulating, and multiplexing various information provided by the processing unit 21.

[0052] Furthermore, the transmitting unit 27 transmits data to the terminal device 10, another base station device 20, or the core network 30. The receiving unit 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 implemented, for example, by a processor system including a processor and 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 implemented by a single processor system or by multiple processor systems. Alternatively, the processing unit 21 and the control unit 23 may be implemented by a DSP or hardware circuit, etc.

[0054] <On-demand SIB1> On-demand SIB1 is one of the power saving technologies applied to the base station equipment 20, and is a method of appropriately transmitting SIB1, which is one of the periodically transmitted notification information, based on a request from the terminal equipment 10. The contents of On-demand SIB1 include at least the setting information notified by conventional SIB1 (wireless connection information (cell common resource information, cell selection criterion information, access restriction information, etc.)), and may also include UL-WUS setting information indicating the transmission setting of UL-WUS, which is a signal for requesting On-demand SIB1.

[0055] The base station device 20B may also be configured to transmit system information other than On-demand SIB1 (SIB2, SIB3, ...) on demand. Access restriction information may also be referred to by similar terms such as access restriction information, access control information, or access prohibition information. Similarly, On-demand SIB1 may be referred to by similar terms such as OD-SIB1, Non-periodic SIB1, or it may continue to be referred to as SIB1, but the description may indicate that it is transmitted on demand from the surrounding text.

[0056] The terminal device 10 receives the On-demand SIB1 from the base station device 20B (NES cell 20B-1), detects and acquires the synchronization signal / physical broadcast channel block (SSB) from the base station device 20B, and uses the SSB to adjust the synchronization of the downlink. 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).

[0057] Next, the terminal device 10 acquires the transmission resource information of the PDCCH and the SSB subcarrier offset information (ssb-SubcarrierOffset) obtained from the MIB (Master Information Block) transmitted in SSB (PBCH). The transmission resource information of the PDCCH (pdcch-ConfigSIB) is information that specifies the area in which the PDCCH that instructs the scheduling information of On-demand SIB1 (or SIB1) may be transmitted (also called the common search area or common search space). This common search space may also be called the Type Zero Search Space / Control Resource Set Zero (Type0 SS / CORESET0). The SSB subcarrier offset information is a parameter that indicates the frequency offset of the SSB transmission position in subcarrier units. The base station device 20B may be configured to indicate that the cell is an NES cell 20B-1 (i.e., an SIB1 non-transmitting cell) by setting a predetermined value in the SSB subcarrier offset information. Furthermore, the base station device 20B does not need to include the PDCCH transmit resource information in the MIB.

[0058] Terminal device 10 monitors the PDCCH that schedules SIB1 based on the acquired transmission resource information, and acquires the PDSCH (On-demand SIB1) indicated by the Downlink Control Information (DCI) contained in the detected PDCCH. Base station device 20 scrambles the PDCCH that schedules SIB1 with System Information-Radio Network Temporary Identifier (SI-RNTI), which is composed of a known bit sequence, and transmits it. In the area where terminal device 10 monitors the PDCCH, it may attempt to reverse scramble the PDCCH using SI-RNTI, and if the PDCCH is decoded correctly, it may then acquire the On-demand SIB1 based on the DCI. Here, MIB and SIB1 (On-demand SIB1) are both Essential System Information.

[0059] Furthermore, the terminal device 10 calculates the cell quality (reception quality) for each cell by measuring SSB or the channel status information reference signal (CSI-RS). Cell quality can be expressed using one of the following: RSRP (Reference Signal Received Power), RSRQ (Reference Signal Received Quality), RSSI (Received Signal Strength Indicator), SINR (Signal to Interference plus Noise Ratio), or path loss.

[0060] <UL-WUS Configuration Information> The UL-WUS configuration information includes some or all of the following information: cell information that identifies the cell transmitting UL-WUS (physical cell identifier (PCI), downlink frequency information, etc.), information related to UL-WUS transmission (PRACH resource information, SSB receive power threshold, TDD UL / DL slot setting, uplink frequency, etc.), information related to SIB1 reception (SSB subcarrier offset information, PDCCH transmission resource information, etc.), and information related to PRACH response reception (reception window length, reception start offset information, etc.). Furthermore, it may also include cell selection criteria information (RSRP threshold, cell-specific offset value, etc.). The terminal device 10 may determine, based on the cell information, whether the cell belonging to the base station device 20 is a normal cell 20A-1 or an NES cell 20B-1. Furthermore, the base station device 20B may include the SSB subcarrier offset information and PDCCH transmission resource information (PDCCH transmission resource information) used for receiving SIB1 in the NES cell 20B-1 in the corresponding UL-WUS configuration information instead of the MIB.

[0061] Taking the above points into consideration, embodiments of the present invention will be described with reference to the drawings. In the description of embodiments of the present invention, if a specific explanation of known functions or configurations related to embodiments of the present invention would obscure the gist of the embodiments of the present invention, such detailed explanation will be omitted.

[0062] <First Embodiment> Figure 4 is an example of a sequence diagram showing the On-demand SIB1 acquisition procedure (On-demand SIB1 control procedure) of the terminal device 10 and base station device 20 related to the first embodiment. Here, On-demand SIB1 (or simply SIB1) is the first system information, and MIB is the second system information. Also, base station device 20A is the first base station device (first cell), and base station device 20B is the second base station device (second cell).

[0063] The terminal device 10 in Figure 4 is a terminal device 10 that supports NES functionality, and the base station device 20A (normal cell 20A-1) provides the information necessary for the terminal device 10 to request On-demand SIB1 from the NES cell, and the configuration information (UL-WUS configuration information) necessary for receiving On-demand SIB1. The method by which the base station device 20A provides configuration information to the terminal device 10 may be to periodically or on-demand within the cell using existing system information or dedicated system information, or it may be notified using individual RRC messages. Individual RRC messages are, for example, RRCReconfiguration messages and RRCRelease messages.

[0064] Furthermore, the base station device 20B (NES cell 20B-1) in Figure 4 transmits On-demand SIB1 when it receives UL-WUS from the terminal device 10, or when the base station device 20B determines that it is necessary (for example, to update the contents of SIB1). Similarly, when the base station device 20B determines that it is not necessary (for example, when a predetermined time has elapsed since the start time of SIB1 transmission), it stops transmitting On-demand SIB1.

[0065] Base station device 20B provides UL-WUS configuration information to base station device 20A via the transmission path between base station devices 20 (step S100). The UL-WUS configuration information includes at least NES cell information that uniquely identifies the NES cell (e.g., a combination of physical cell identifier (PID) and downlink frequency information), information regarding SIB1 reception, information regarding UL-WUS transmission, and information regarding PRACH response reception.

[0066] The base station device 20A transmits (forwards, notifies) within the cell, including at least one piece of UL-WUS configuration information received from the base station device 20B (step S101). It is preferable for the base station device 20A to transmit the received UL-WUS configuration information as a System Information message. The base station device 20B also periodically transmits MIBs corresponding to the On-demand SIB1 cell to the NES cell 20B-1 (step S102). The terminal device 10 receives the MIBs transmitted by the base station device 20B and holds that information. Then, the terminal device 10 uses the UL-WUS configuration information received from the base station device 20A and the MIB information received from the base station device 20B to perform an SIB1 acquisition determination to determine whether or not to receive the SIB1 (On-demand SIB1) of the base station device 20B (NES cell 20B-1) (step S103).

[0067] Here, the terminal device 10 compares the reception quality of the base station device 20A (normal cell 20A-1), which is a cell in the service area, with the reception quality of one or more base station devices 20B (NES cell 20B-1), which are candidates for cell reselection, and makes a decision to acquire SIB1 for the cell that satisfies the cell selection criteria and has the best reception quality. However, if the NES cell information corresponding to the cell detected by the terminal device 10 through cell search (i.e., the cell from which the MIB was received in step S102) is not included in the UL-WUS setting information (or does not possess (hold) valid UL-WUS setting information itself), and the terminal device 10 determines that SIB1 has not been transmitted in that cell based on the setting value of the MIB's SSB subcarrier offset information, then the detected cell does not have to be considered a target cell for SIB1 acquisition determination.

[0068] When making an SIB1 acquisition decision for base station equipment 20B (NES cell 20B-1), that is, when it possesses NES cell information corresponding to the cell (the NES cell information is included in valid UL-WUS configuration information), terminal equipment 10 may determine that SIB1 can be acquired using the PDCCH transmission resource information (pdcch-ConfigSIB) (first PDCCH transmission resource information) included in the MIB if the setting value of the SSB subcarrier offset information of the MIB acquired in step S102 is a value indicating the "SSB frequency offset" (for example, 23 or less in frequency range 1, and 11 or less in frequency range 2).

[0069] Furthermore, if the setting value of the MIB's SSB subcarrier offset information is a value indicating "no SIB1" (for example, 24 to 31 in frequency range 1, and 12 to 14 in frequency range 2), the terminal device 10 may ignore the first PDCCH transmission resource information and determine that SIB1 can be obtained using the PDCCH transmission resource information (second PDCCH transmission resource information) set in the UL-WUS setting information held by the terminal device 10.

[0070] The terminal device 10 may also determine that SIB1 is obtainable by referring to other bit information included in the MIB. For example, if the setting value of the SSB subcarrier offset information of the MIB obtained in step S102 is a specific reserved value (for example, 30 in frequency range 1, 14 in frequency range 2), the terminal device 10 may not interpret the bit sequence shown in the first PDCCH transmission resource information as existing information indicating a common search area of ​​the PDCCH, but rather consider it as setting information indicating at least whether SIB1 is being transmitted in that cell, and may determine whether SIB1 is obtainable based on that bit sequence.

[0071] Alternatively, the base station device 20 may set a specific reserved value in the SSB subcarrier offset information (for example, 30 in frequency range 1 and 14 in frequency range 2), and instead of the bit sequence indicating the conventional PDCCH transmission resource information, it may transmit setting information that allows the terminal device 10 to determine that SIB1 can be acquired in that cell.

[0072] The terminal device 10 and the base station device 20 may use MIB information other than SSB subcarrier offset information, provided that the terminal device 10 can determine whether or not SIB1 can be obtained by referring to the information. For example, reserved bits of the MIB may be used.

[0073] The terminal device 10 attempts to acquire the SIB1 of the base station device 20B (NES cell 20B-1) using the first and second PDCCH transmission resource information (step S104). In Figure 4, the (On-demand) SIB1 in step S104 may not actually be transmitted. If the terminal device 10 is able to acquire the SIB1, it decides that it may retain the acquired SIB1 information, apply the necessary settings, and continue with the cell reselection procedure to camp in that cell.

[0074] If the terminal device 10 determines, based on the acquired SIB1 information, that it is possible to camp at the base station device 20B (NES cell 20B-1) (for example, if it determines that it is not a barred cell), it determines that the cell is a suitable cell for cell reselection, performs camping, and terminates the On-demand SIB1 acquisition procedure (On-demand SIB1 control procedure).

[0075] The terminal device 10 may set the trial time for acquiring the (On-demand) SIB1 as follows: (1) it may depend on the implementation of the terminal device 10; (2) it may be a predetermined time (e.g., 160 milliseconds); (3) it may be a time or number of times set by the base station device 20; or (4) it may be the same as the time until receiving the RAR (described later) assuming that UL-WUS has been transmitted. When the base station device 20 sets the time or number of times, it may transmit the set information using system information, UL-WUS setting information, or other individual RRC messages.

[0076] Here, if the terminal device 10 possesses NES cell information corresponding to base station device 20B (NES cell 20B-1), and attempts to acquire SIB1 using the first PDCCH transmission resource information based on the SSB subcarrier offset information, but fails to acquire SIB1, the terminal device 10 may (1) attempt to acquire SIB1 again using the second PDCCH transmission resource information, (2) transmit UL-WUS based on UL-WUS setting information, or (3) consider NES cell 20B-1 to be an access-restricted cell.

[0077] In case (1), the terminal device 10 discards the first PDCCH transmission resource information and attempts to acquire SIB1 again using the second PDCCH transmission resource information. At this time, the time and number of times the terminal device 10 attempts to acquire (On-demand) SIB1 can be the same as in step S104, so the explanation is omitted.

[0078] The procedure in case (2) is explained in Figure 5 below. In case (3), the terminal device 10 temporarily (for example, for 300 seconds) considers the NES cell 20B-1 to be a barred cell and continues the cell reselection procedure for a different cell of the same frequency (if intraFreqReselection is allowed) or the cell reselection procedure for a cell of a different frequency (if intraFreqReselection is not allowed) according to the cell selection / cell reselection control information (intraFreqReselection) included in the MIB. The base station device 20 may instruct the terminal device 10 to perform any of the above procedures (1) to (3) using system information. Note that, considering the possibility that the procedure in (1) is implementation-dependent on the terminal device 10, the base station device 20 may instruct either the above procedure (2) or (3).

[0079] Figure 5 is an example of a sequence diagram showing the UL-WUS transmission procedure of the terminal device 10 and the base station device 20 in the case where SIB1 could not be acquired (or it was determined that SIB1 was not transmitted) as shown in Figure 4.

[0080] The terminal device 10 and base station device 20B (NES cell 20B-1) in Figure 5 are the same as in Figure 4, so a detailed explanation is omitted. The terminal device 10 performs a UL-WUS transmission determination to determine whether or not to transmit UL-WUS to the base station device 20B (NES cell 20B-1) (step S200).

[0081] If the terminal device 10 determines in the UL-WUS transmission determination that it will transmit UL-WUS, it will also perform the processes in the following steps S201 to S203. On the other hand, if the terminal device 10 determines in the UL-WUS transmission determination that it will not transmit UL-WUS, it does not need to perform the following steps S201 to S203.

[0082] The terminal device 10 may also include whether or not it has acquired (On-demand) SIB1 in step S104 of Figure 4 as one of its criteria for determining whether to transmit UL-WUS. That is, if the terminal device 10 has acquired (On-demand) SIB1 in step S104, it may decide not to transmit (suppress) UL-WUS. On the other hand, if the terminal device 10 has not acquired (On-demand) SIB1 in step S104 (or has failed to acquire SIB1), it may decide to transmit UL-WUS.

[0083] When terminal device 10 determines to transmit UL-WUS, it transmits UL-WUS to base station device 20B (NES cell 20B-1) based on the corresponding UL-WUS configuration information (step S201). UL-WUS is transmitted by applying individual transmission resources in the physical random access channel. Individual transmission resources are, for example, random access preambles reserved for UL-WUS. Terminal device 10 determines the target transmission power for UL-WUS, the random access sequence to be used, the transmission time position, etc., using a procedure similar to that of conventional random access procedures.

[0084] The terminal device 10 that transmitted the UL-WUS expects a UL-WUS response (UL-WUS response, Random Access Response (RAR)) to be transmitted from the base station device 20B, and attempts to receive (monitor) the UL-WUS response (RAR) for a predetermined window length (Random Access window) (step S202). Information for receiving the UL-WUS response (RA-RNTI (Random Access-Radio Network Temporary Identifier), window length, etc.) is determined using the same procedure as for the random access procedure. The base station device 20B may include the setting information necessary for receiving the UL-WUS response in the UL-WUS setting information and transmit it. If the UL-WUS response is not detected, the terminal device 10 may retransmit the UL-WUS. The terminal device 10 may use the same procedure as the conventional random access procedure (setting the maximum number of retransmissions, power ramping, etc.) as the method for retransmitting UL-WUS. The base station device 20B may include the setting information necessary for UL-WUS retransmission in the UL-WUS setting information and transmit it.

[0085] The base station device 20B indicates the transmission resource location of the UL-WUS response (RAR) using a PDCCH scrambled with RA-RNTI calculated in accordance with the transmission resources used by the terminal device 10. In other words, the base station device 20B transmits the UL-WUS response (RAR) to the terminal device 10 using the PDSCH indicated by the DCI of the PDCCH. The base station device 20B also transmits the received random access preamble information in the UL-WUS response (RAR). The UL-WUS response may be transmitted in a format that consists only of header information including at least random access preamble information, and does not include scheduling information for user data. The base station device 20B may use a common RA-RNTI prepared for UL-WUS applications as the RA-RNTI, or it may use a different RA-RNTI (WUS-RNTI) calculated using a different formula.

[0086] If the terminal device 10 determines that it has successfully received the corresponding UL-WUS response (RAR) in step S202 and that On-demand SIB1 will be transmitted, or if it determines that the UL-WUS transmission procedure has been completed, it attempts to receive On-demand SIB1 (step S203).

[0087] From a power saving perspective, it is desirable that On-demand SIB1 be transmitted only temporarily within a predetermined time window (SIB1 Time Window), rather than periodically as in the conventional method. The base station device 20B may specify the predetermined time window on a per-NES cell 20B-1 basis using UL-WUS configuration information or system information, or on a per-terminal device 10 basis using UL-WUS response (RAR). Alternatively, the base station device 20B may specify information indicating the interval (time offset) from the receipt of the UL-WUS response (RAR) to the predetermined time window on a per-terminal device 10 basis using UL-WUS response (RAR). The terminal device 10 attempts to acquire On-demand SIB1 within the predetermined time window determined using one of the methods described above. If the terminal device 10 obtains an On-demand SIB1, it retains the information of the obtained (On-demand) SIB1, applies the necessary settings, and continues the cell reselection procedure.

[0088] Figure 6 shows an example of a sequence diagram when a Radio Link Failure (RLF) is detected in terminal device 10 in connected mode, and an RRC Restabilization procedure (RRC restabilization control procedure) is performed, and a cell of base station device 20B (NES cell 20B-1) is selected as a candidate cell for RRC restabilization. It is assumed that terminal device 10 has received the necessary UL-WUS configuration information from base station device 20A (or base station device 20B).

[0089] In step S300, the terminal device 10 detects that the wireless quality between it and the base station device 20 has deteriorated and that a radio link failure (RLF) has occurred. Here, the method for detecting the RLF is not specifically defined, but the terminal device 10 can detect the radio link failure (RLF) using, for example, any of the conventional methods (detection of deterioration in wireless quality exceeding a timer time, failure of a random access procedure, or occurrence of RLC retransmission errors exceeding a predetermined number of times).

[0090] If a wireless link failure (RLF) is detected, the terminal device 10 starts timing an RRC timer (reconnection timer (also referred to as Timer T311)) that indicates the maximum time to attempt the RRC reconnection procedure, and also autonomously releases RRC settings that are not necessary for the RRC reconnection procedure and starts the cell selection procedure (not shown). The terminal device 10 may determine whether or not the RRC reconnection procedure is being performed based on whether or not the reconnection timer (Timer T311) is timing.

[0091] Figure 6 shows an example where terminal device 10 selects base station device 20B (NES cell 20B-1) as a candidate cell during cell selection associated with the RRC reconnection procedure. In other words, base station device 20B periodically transmits MIBs corresponding to the On-demand SIB1 cell to NES cell 20B-1 (step S301). Terminal device 10 receives the MIBs transmitted by base station device 20B and stores the information. Then, terminal device 10 uses the UL-WUS configuration information it possessed before the radio link failure (RLF) detection and the MIB information received from base station device 20B to make a decision on whether or not to receive SIB1 (On-demand SIB1) from base station device 20B (step S302).

[0092] However, if the NES cell information corresponding to a cell detected by the terminal device 10 through cell search (i.e., the cell from which the MIB was received in step S301) is not included in the UL-WUS configuration information (or does not possess (hold) valid UL-WUS configuration information itself), and the terminal device 10 determines that SIB1 has not been transmitted in that cell based on the setting value of the MIB's SSB subcarrier offset information, then the detected cell does not need to be considered a target cell (candidate cell) for the RRC reconnection procedure.

[0093] In step S302, the terminal device 10 can determine whether it is possible to acquire SIB1 from the base station device 20B (NES cell 20B-1) using the same criteria as in step S103 of Figure 4, so a detailed explanation is omitted.

[0094] The terminal device 10 attempts to acquire the SIB1 of the base station device 20B (NES cell 20B-1) using the first and second PDCCH transmission resource information (step S303). If the terminal device 10 is able to acquire the SIB1 of the base station device 20B (NES cell 20B-1), it decides that it may retain the acquired SIB1 information, apply the necessary settings, and continue the RRC reconnection procedure for the cell.

[0095] On the other hand, if the terminal device 10 fails to acquire SIB1 in step S303, it may decide not to transmit UL-WUS even if it possesses UL-WUS setting information corresponding to that cell. The terminal device 10 may also decide whether or not to transmit UL-WUS based on a reconnection timer (timer T311). That is, the terminal device 10 decides to transmit UL-WUS if the reconnection timer is running, and not to transmit UL-WUS if the reconnection timer is not running.

[0096] Furthermore, the terminal device 10 may consider the NES cell 20B-1, from which SIB1 could not be obtained, to be a barred cell. The terminal device 10 may decide not to consider the cell in question as a target cell (candidate cell) for the RRC reconnection procedure and not to continue the RRC reconnection procedure. The terminal device 10 may release the UL-WUS configuration information corresponding to the cell in question, or it may decide that it is invalid.

[0097] If the RRC reconnection procedure for the cell in question is to be continued, the terminal device 10 also performs the subsequent steps S304 to S306 for the base station device 20B (NES cell 20B-1). On the other hand, if it is determined that the RRC reconnection procedure for the cell in question is not to be continued, the terminal device 10 does not need to perform the subsequent steps S304 to S306. If the RRC reconnection procedure is not to be continued, the terminal device 10 may ignore the cell selection / cell reselection control information (intraFreqReselection) included in the received MIB and decide to perform a new cell selection procedure for another cell of the same frequency.

[0098] Steps S304 to S306 can reuse the conventional RRC reconnection procedure. In summary, the terminal device 10 transmits a physical random access channel based on the SIB1 information received from the candidate cell (step S304).

[0099] Upon receiving a physical random access channel, the base station device 20B adjusts its transmission timing to receive a random access response (RAR) within a pre-set window length (Random access window) and transmits it to the terminal device 10 (step S305). The random access response may be transmitted in a format that includes header information containing at least random access preamble information, an uplink grant (uplink resource allocation information) to be assigned to the terminal device 10, and uplink timing adjustment information (Timing Advance Command). The terminal device 10 monitors the physical downlink control channel PDCCH within the window length (Random access window) and attempts to receive a random access response (RAR).

[0100] Upon successfully receiving a Random Access Response (RAR), terminal device 10 generates an RRC Restabilization Request message and sends it to base station device 20B using the uplink resource specified in the uplink grant (step S306). Base station device 20B monitors the specified uplink resource and detects that terminal device 10 has sent the RRC Restabilization Request message.

[0101] If the SIB1 of base station device 20B (NES cell 20B-1) is acquired (step S303), the terminal device 10 may check whether the UL-WUS configuration information (the SIB that transmits the UL-WUS configuration information (hereinafter referred to as SIB-X)) contained in SIB1 has been updated. Specifically, the terminal device 10 checks whether the value of the tag (value tag) corresponding to SIB-X is different. When base station device 20B changes (updates) the information of SIB-X, it is necessary to increment the value of the tag corresponding to SIB-X contained in SIB1 when transmitting the changed SIB-X.

[0102] The terminal device 10 compares the tag value of the SIB-X it possessed before the wireless link failure (RLF) occurred with the tag value of the SIB-X reacquired during the RRC reconnection procedure. If the values ​​are different, it determines that the SIB-X was updated after the wireless link failure (RLF) occurred. At this time, the terminal device 10 may immediately determine that the possessed SIB-X (UL-WUS configuration information) is invalid, or it may determine that it is invalid after the RRC reconnection procedure is successful. The terminal device 10 may also release the information of the invalidated SIB-X.

[0103] On the other hand, if the tag value is the same, the terminal device 10 determines that an SIB-X containing the same information as before the wireless link failure (RLF) occurred has been transmitted. At this time, the terminal device 10 may immediately determine that the SIB-X (UL-WUS configuration information) it possesses is valid, or it may determine that it is valid after the RRC reconnection procedure is successful.

[0104] Furthermore, even if the terminal device 10 selects base station device 20B (NES cell 20B-1) as a candidate cell during cell selection following a recovery from out-of-coverage, the procedure in Figure 6 can be reused. However, the difference is that the terminal device 10 initiates the RRC setup procedure (also called RRC Connection Establishment) instead of the RRC reconnection procedure. That is, in step S306 of Figure 6, the terminal device 10 sends an RRC Setup Request message to base station device 20B (NES cell 20B-1) instead of an RRC Restabilization Request message.

[0105] Thus, according to the first embodiment, the base station device 20 can notify a cell that appropriately transmits system information (SIB1) for power saving purposes, with information that allows the terminal device 10 to determine whether or not it can receive SIB1. Based on this information, the terminal device 10 can determine whether or not it can receive SIB1, and can decide whether or not to continue the RRC reconnection procedure, or to suppress unnecessary SIB1 transmission requests (UL-WUS) to the base station device 20. As a result, the power saving efficiency of the base station device 20 can be improved.

[0106] <Second Embodiment> The second embodiment is described below. Note that the configurations, functions, or procedures common to both the first and second embodiments will not be explained. In other words, the following will mainly describe the differences from the first embodiment.

[0107] The RRC reconnection procedure is performed to recover from a temporary interruption of wireless connectivity due to quality degradation, and from the perspective of service continuity, the shorter the interruption time, the better. Therefore, if base station equipment 20B (NES cell 20B-1) is selected as a candidate cell and SIB1 is not being transmitted, it is necessary to search for another candidate cell again, which may take longer than usual to determine which cell to perform the RRC reconnection procedure on.

[0108] Therefore, in the second embodiment, a method for excluding the base station device 20B (NES cell 20B-1) from the candidate cells for the RRC reconnection procedure is shown.

[0109] Even if the terminal device 10 possesses NES cell information corresponding to a cell detected by cell search associated with the RRC reconnection procedure (i.e., the cell that received the MIB in step S301 of Figure 6) (the NES cell information is included in the valid UL-WUS configuration information), if the terminal device 10 determines that SIB1 has not been transmitted in that cell based on the setting value of the MIB's SSB subcarrier offset information, it does not need to consider the detected cell as a target cell (candidate cell) for the RRC reconnection procedure.

[0110] For example, even if terminal device 10 possesses NES cell information for a detected cell, if the setting value of the acquired MIB's SSB subcarrier offset information indicates "no SIB1" (for example, 24 to 31 in frequency range 1, and 12 to 14 in frequency range 2), it does not need to consider the detected cell as a target cell (candidate cell) for the RRC reconnection procedure.

[0111] In this case, the terminal device 10 may ignore the cell selection / cell reselection control information (intraFreqReselection) included in the MIB and perform a new cell selection procedure on another cell of the same frequency.

[0112] Furthermore, if the terminal device 10 possesses NES cell information for the detected cell, and the setting value of the acquired MIB's SSB subcarrier offset information is a value indicating the "SSB frequency offset" (for example, 23 or less in frequency range 1, and 11 or less in frequency range 2), the terminal device 10 may consider the detected cell as a target cell (candidate cell) for the RRC reconnection procedure and attempt to determine if SIB1 can be acquired using the PDCCH transmission resource information (pdcch-ConfigSIB) (first PDCCH transmission resource information) included in the MIB.

[0113] Furthermore, if the terminal device 10 possesses NES cell information corresponding to the detected cell, it may decide whether or not to include the detected cell as a target cell for the RRC reconnection procedure based on instructions (configuration information) from the base station device 20. The base station device 20 may specify this configuration information for each NES cell information included in the system information or UL-WUS configuration information. For example, the configuration information may be information indicating either (1) {allowed, not allowed}, or (2) optional information which, if set, is interpreted as the cell being included as a target cell, but if omitted (absent), it is interpreted as not being included as a target cell.

[0114] Furthermore, the terminal device 10 does not have to consider the detected cell as a target cell (candidate cell) for the RRC reconnection procedure based on the reconnection timer (timer T311) and UL-WUS setting information. In other words, the terminal device 10 does not have to consider the detected cell as a target cell (candidate cell) for the RRC reconnection procedure when the reconnection timer is running.

[0115] Thus, according to the second embodiment, the base station device 20 can notify the terminal device 10 of information that allows it to determine whether or not it can receive system information (SIB1) in a cell that appropriately transmits system information (SIB1) for power saving purposes. Based on this information, the terminal device 10 can determine whether or not to designate the cell as a candidate cell for the RRC reconnection procedure before continuing to acquire SIB1. As a result, the RRC reconnection procedure can be optimized, and the power saving efficiency of the base station device 20 can be improved.

[0116] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its scope. The present invention can be modified or improved without departing from its spirit, and includes equivalents thereof. Furthermore, the embodiments described herein may be used individually, in combination, or switched between as needed during execution.

[0117] <Hardware Configuration of Each Device in Each Embodiment> Based on Figures 7 and 8, the hardware configuration of each device in the wireless communication system of each embodiment will be described.

[0118] Figure 7 shows an example of the hardware configuration of the terminal device 10. As shown in Figure 7, the terminal device 10 has, as hardware components, an RF (Radio Frequency) circuit 32 equipped with an antenna 31, a CPU (Central Processing Unit) 33, and a memory 34. Furthermore, the terminal device 10 may have a display device such as an LCD (Liquid Crystal Display) connected to the CPU 33. The memory 34 includes, for example, at least one of RAM (Random Access Memory) such as SDRAM (Synchronous Dynamic Random Access Memory), ROM (Read Only Memory), and flash memory, and stores programs, control information, and data signals.

[0119] The correspondence between the functional configuration of the terminal device 10 shown in Figure 2 and the hardware configuration of the terminal device 10 shown in Figure 7 will be explained. The transmitting / receiving antenna unit 19, the transmitting unit 17, and the receiving 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, memory 34, and a digital electronic circuit (not shown). Examples of digital electronic circuits include ASIC (Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), and LSI (Large Scale Integration).

[0120] Figure 8 shows an example of the hardware configuration of the base station device 20. As shown in Figure 8, the base station device 20 has, 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, for example, RAM such as SDRAM, ROM, and flash memory, and stores programs, control information, and data signals.

[0121] The correspondence between the functional configuration of the base station device 20 shown in Figure 3 and the hardware configuration of the base station device 20 shown in Figure 8 will be explained. The transmitting / receiving antenna unit 29, the transmitting unit 27, and the receiving unit 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, and a digital electronic circuit (not shown). Examples of digital electronic circuits include ASICs, FPGAs, and LSIs.

[0122] 1 Wireless Communication System 10 Terminal Devices 20A, 20B Base Station Device 20A-1 Normal Cell 20B-1 NES Cell 30 Core Network 11, 21 Processing Units 13, 23 Control Units 15, 25 Receiving Units 17, 27 Transmitting Units 19, 29 Transmitting / Receiving Antenna Units 31, 41 Antennas 32, 42 RF Circuits 33, 43 CPU 34, 45 Memory 44 DSP 46 Network IF 111, 211 Wireless 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 receiving unit that receives a request signal setting from the first base station device requesting the second base station device to transmit first system information on demand; a processing unit that, if it possesses the request signal setting and performs a control procedure involving the acquisition of the first system information, acquires physical downlink control channel information necessary for acquiring the first system information from the second system information of the second base station device or the request signal setting based on the request signal setting; and a transmitting unit that transmits a physical random access channel related to the control procedure to the second base station device based on the success or failure of the acquisition of the first system information of the second base station device using the physical downlink control channel information.

2. The terminal device according to claim 1, wherein the first system information is SIB1 and the second system information is MIB.

3. The terminal device according to claim 2, which, when it obtains information from the second system information of the second base station device indicating that the second base station device has not transmitted the first system information, determines that it is necessary to obtain the first system information of the second base station device using the physical downlink control channel information of the request signal setting.

4. The terminal device according to claim 3, wherein the control procedure is an On-demand SIB1 acquisition procedure, and if the acquisition of the first system information of the second base station device is successful, the control procedure is terminated by selecting the second base station device as the cell selection destination without transmitting the physical random access channel, and if the acquisition of the first system information of the second base station device fails, the physical random access channel based on the request signal setting is transmitted to the second base station device.

5. The terminal device according to claim 3, wherein the control procedure is an RRC reconnection procedure, and if the acquisition of the first system information by the second base station device is successful, the physical random access channel based on the first system information of the second base station device is transmitted to the second base station device.

6. The terminal device according to claim 5, wherein if the acquisition of the first system information by the second base station device fails, the second base station device is considered to be an access-restricted cell.

7. A base station device in a communication system including a first cell that periodically transmits first system information and a second cell that transmits the first system information on demand in response to a request from a terminal device, the base station device comprising: a transmitting unit that transmits a request signal setting from the first cell to the terminal device requesting on-demand transmission of the first system information from the second cell; a processing unit that, when the terminal device possesses the request signal setting and performs a control procedure involving the acquisition of the first system information from the second cell, sets information that causes the terminal device to determine that the physical downlink control channel information necessary for acquiring the first system information can be acquired using the second system information of the second cell or the request signal setting; and a receiving unit that receives a physical random access channel relating to the control procedure transmitted to the second cell based on the success or failure of acquiring the first system information from the second cell using the physical downlink control channel information.

8. The base station device according to claim 7, wherein the first system information is SIB1 and the second system information is MIB.

9. The base station device according to claim 8, wherein the control procedure is an On-demand SIB1 acquisition procedure, and the request signal setting includes information for causing the terminal device to transmit the physical random access channel to the second cell if the acquisition of the first system information of the second cell fails.

10. The base station device according to claim 8, wherein the control procedure is an RRC reconnection procedure, and the first system information of the second cell includes information for causing the terminal device to transmit the physical random access channel to the second cell when the acquisition of the first system information of the second cell is successful.

11. A control method for a terminal device capable of communicating with a first base station device and a second base station device, comprising: receiving means for receiving a request signal setting from the first base station device for requesting first system information on demand from the second base station device; processing means for acquiring physical downlink control channel information necessary for acquiring the first system information, based on the request signal setting, from the second system information of the second base station device or the request signal setting, when the request signal setting is possessed and a control procedure involving the acquisition of the first system information is performed; and transmitting means for transmitting a physical random access channel relating to the control procedure to the second base station device based on the success or failure of the acquisition of the first system information by the second base station device using the physical downlink control channel information.

12. A method for controlling a base station device in a communication system including a first cell that periodically transmits first system information and a second cell that transmits the first system information on demand in response to a request from a terminal device, comprising: a transmitting means that transmits a request signal setting from the first cell to the terminal device requesting on-demand transmission of the first system information in the second cell; a processing means that, when the terminal device possesses the request signal setting and performs a control procedure involving the acquisition of the first system information of the second cell, causes the terminal device to determine that physical downlink control channel information necessary for acquiring the first system information can be acquired using the second system information of the second cell or the request signal setting; and a receiving means that receives a physical random access channel relating to the control procedure transmitted to the second cell based on the success or failure of acquiring the first system information of the second cell using the physical downlink control channel information.

Images