Communication device, terminal device, and communication method

Abstract

A communication device according to the present disclosure is one of a plurality of communication devices that communicate with a terminal device in a coordinated manner. The communication device comprises a communication unit and a control unit. The communication unit communicates with a terminal device. The control unit transmits, to a terminal device that has made a transmission request for a synchronization signal for initial connection, the synchronization signal in a state in which at least a portion of functions of the communication unit is disabled. The terminal device transmits the transmission request according to a setting signal for transmitting the transmission request.

Description

Communication device, terminal device, and communication method

[0001] The present disclosure relates to a communication device, a terminal device, and a communication method.

[0002] Radio access methods and radio networks for cellular mobile communications (hereinafter also referred to as "Long Term Evolution (LTE)," "LTE-Advanced (LTE-A)," "LTE-Advanced Pro (LTE-A Pro)," "New Radio (NR)," "New Radio Access Technology (NRAT)," "Evolved Universal Terrestrial Radio Access (EUTRA)," or "Further EUTRA (FEUTRA)") are being considered by the 3rd Generation Partnership Project (3GPP (registered trademark)).

[0003] In the following description, LTE includes LTE-A, LTE-A Pro, and EUTRA, and NR includes NRAT and FEUTRA. In LTE, a base station (base station device) is referred to as an eNodeB (evolved NodeB), in NR, a base station (base station device) is referred to as a gNodeB (gNB), and in LTE and NR, a terminal device (mobile station, mobile station device, terminal) is referred to as a UE (User Equipment). LTE and NR are cellular communication systems in which multiple areas covered by a base station are arranged in the form of cells. A single base station may manage multiple cells.

[0004] 5G NR is a next-generation radio access technology (RAT) different from LTE, and is a next-generation radio access method for LTE. NR is an access technology that can support various use cases, including eMBB (enhanced Mobile Broadband), mMTC (massive Machine Type Communications), and URLLC (Ultra Reliable and Low Latency Communications). NR has been standardized to support a technical framework that corresponds to the usage scenarios, requirements, and deployment scenarios of those use cases.

[0005] In recent years, discussions on next-generation wireless communication have been progressing. This next-generation wireless communication requires even higher speed communication than 5G NR, low-latency and highly reliable communication, large number of high-density communication, and simultaneous support of multiple of these.

[0006] To achieve these requirements, further improvements in frequency utilization efficiency are required. One technique for improving frequency utilization efficiency is to enable efficient communication with terminal devices by having multiple base stations cooperate to communicate with the terminal devices.

[0007] R1-2400176, “On-demand SSB SCell operation”, Ericsson, 3GPP RAN1 #116, February-March 2024.

[0008] As described above, by having multiple base stations cooperate to communicate with terminal devices, it is possible to further improve frequency utilization efficiency. However, this technology has the problem that power consumption on the network side increases because multiple base stations are operating.

[0009] Therefore, the present disclosure proposes a communication device, a terminal device, and a communication method that can further suppress an increase in power consumption.

[0010] It should be noted that the above problem or object is merely one of multiple problems or objects that can be solved or achieved by multiple embodiments disclosed in this specification.

[0011] A communication device according to the present disclosure is one of a plurality of communication devices that communicate with a terminal device in cooperation with each other. The communication device includes a communication unit and a control unit. The communication unit communicates with the terminal device. The control unit transmits a synchronization signal to the terminal device that has made a request to transmit the synchronization signal for initial connection, while at least some functions of the communication unit are stopped. The terminal device transmits the transmission request in response to a setting signal for transmitting the transmission request.

[0012] 1 is a diagram illustrating an example of an SS / PBCH block. FIG. 2 is a diagram illustrating an example of an arrangement of SS / PBCH blocks. FIG. 3 is a diagram illustrating an example of on-demand SSB. FIG. 4 is a diagram illustrating an example of communication by a base station. FIG. 5 is a diagram illustrating an example of a communication system according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating an overview of communication processing related to a proposed technique of an embodiment of the present disclosure. FIG. 7 is a diagram illustrating an example of a configuration of a base station according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example of a configuration of a terminal device according to an embodiment of the present disclosure. FIG. 9 is a diagram illustrating an example of a first deployment scenario according to an embodiment of the present disclosure. FIG. 10 is a sequence diagram illustrating an example of request processing executed in the first deployment scenario according to an embodiment of the present disclosure. FIG. 11 is a sequence diagram illustrating another example of request processing executed in the first deployment scenario according to an embodiment of the present disclosure. FIG. 12 is a diagram illustrating an example of a second deployment scenario according to an embodiment of the present disclosure. FIG. 13 is a sequence diagram illustrating an example of request processing executed in the second deployment scenario according to an embodiment of the present disclosure. FIG. 14 is a sequence diagram illustrating another example of request processing executed in the second deployment scenario according to an embodiment of the present disclosure. FIG. 15 is a diagram illustrating an example of a second deployment scenario according to an embodiment of the present disclosure.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] In this specification and drawings, similar components of the embodiments may be distinguished by adding at least one different alphabet and / or number after the same reference numeral. However, if there is no need to particularly distinguish between the similar components, only the same reference numeral will be used.

[0015] Furthermore, the base station in this specification and drawings may be a terrestrial base station, a satellite station, or a non-terrestrial base station that operates as a communication device, such as a drone, a balloon, or an airplane. Furthermore, the base station in this specification and drawings may be referred to as a distributed base station, gNB, BS, DU (Distributed Unit), RU (Radio Unit), TRP (Transmission and Reception Point), etc. Furthermore, the base station may be called by a name other than these.

[0016] Furthermore, the term "resource" in this specification and drawings refers to, for example, Frequency, Time, Resource Element (including REG, CCE, and CORESET), Resource Block, Bandwidth Part, Component Carrier, Symbol, Sub-Symbol, Slot, Mini-Slot, Subslot, Subframe, Frame, PRACH occasion, Occasion, Code, Multi-access physical resource, Multi-access signature, Subcarrier Spacing (Numerology), etc.

[0017] Furthermore, although specific numerical values ​​are given in the present specification and drawings, these values ​​are merely examples and different numerical values ​​may be applied.

[0018] One or more embodiments (including examples, modifications, and application examples) described below can be implemented independently. However, at least a portion of the embodiments described below may be implemented in appropriate combination with at least a portion of another embodiment. These embodiments may include novel features that are different from one another. Therefore, these embodiments may contribute to solving different purposes or problems and may produce different effects.

[0019] <<1. Introduction>> <1-1. Related Technology> <1-1-1. SS / PBCH Block> Fig. 1 is a diagram showing an example of an SS / PBCH block. The SS / PBCH block (SSB block) is composed of a PSS (Primary Synchronization Signal), an SSS (Secondary Synchronization Signal), a PBCH (Physical Broadcast Channel), and a DMRS (Demodulation Reference Signal) of the PBCH.

[0020] The PSS and SSS are composed of 127 sequences and are arranged in 127 REs. The PSS is arranged in the first symbol of the SS / PBCH block, and the SSS is arranged in the third symbol of the SS / PBCH block. The PBCH is arranged in the second to fourth symbols.

[0021] The second and fourth symbols of the PBCH are allocated to 20 PRBs (Physical Resource Blocks), and the third symbol is allocated to the four PRBs above and below the SS / PBCH block.

[0022] The MIB (Master Information Block) between SS / PBCH blocks with the same center frequency is the same, whereas the MIB between SS / PBCH blocks with different center frequencies may be different.

[0023] Furthermore, multiple SS / PBCH blocks are placed on the same center frequency, and each SS / PBCH block is assigned a different SS / PBCH block index.

[0024] The terminal device may assume that SS / PBCH blocks with the same block index located at the same center frequency are quasi-co-located (QCL).

[0025] On the other hand, the terminal device does not need to assume that there is QCL between SS / PBCH blocks placed at different center frequencies, or between SS / PBCH blocks placed at the same center frequency but with different block indices.

[0026] Figure 2 shows an example of the arrangement of SS / PBCH blocks. SS / PBCH is arranged as shown in Figure 2 as an example. One or more SS / PBCH blocks are arranged in a half frame (5 msec). Multiple SS / PBCH blocks in a half frame are also called an SS / PBCH block burst or SSB burst.

[0027] The maximum number of SS / PBCH blocks that can be placed in one half-frame is defined as Lmax, which is 4 for FR1 and 3 GHz or less, 8 for FR1 and 3 GHz or more, 10 for unlicensed bands and 15 kHz SCS, 20 for unlicensed bands and 30 kHz SCS, and 64 for FR2. In other words, the number of SSBs in one SSB burst may depend on the subcarrier spacing associated with the frequency band.

[0028] The first symbols of one or more SS / PBCH blocks are mapped to the following symbols: - Case A: {2,8}+14*n - Case B: {4,8,16,20}+28*n - Case C: {2,8}+14*n - Case D: {4,8,16,20}+28*n - Case E: {2,8}+14*n where n is any positive number.

[0029] The period of the SS / PBCH block burst can be set to any one of 5, 10, 20, 40, 80, and 160 msec. On the other hand, in initial cell selection, the terminal device 40 assumes that the period of the SS / PBCH block burst is 20 msec.

[0030] <1-1-2. On-demand SSB> SSB is a signal transmitted periodically and as an always-on signal. Therefore, the base station continues to transmit SSB regardless of whether there is a UE within its coverage area.

[0031] Such transmissions consume a lot of power, so a mechanism for controlling SSB transmission opportunities on demand (on-demand SSB) is being discussed as a standard.

[0032] When the base station receives a request to start on-demand SSB, it transmits the SSB. The base station continues transmitting the SSB until it receives a request to stop on-demand SSB or for a predetermined period of time.

[0033] 3 is a diagram showing an example of on-demand SSB. As shown in FIG. 3, the base station (gNB in ​​FIG. 3) does not transmit SSB (No SSB is transmitted) until it receives a request to start on-demand SSB (Activation of on-demand SSB). The base station starts transmitting SSB (SSB is transmitted) when it receives the request to start on-demand SSB.

[0034] The SSB is repeatedly transmitted at a predetermined interval until a request for deactivation of on-demand SSB is received. The base station stops transmitting the SSB when it receives the request for deactivation of on-demand SSB (No SSB is transmitted). Alternatively, the base station may transmit the SSB until a predetermined period has elapsed since it received the request for starting on-demand SSB.

[0035] In Rel-19, the above-mentioned on-demand SSB is applied only to SCell (Secondary Cell) operation, and application to Pcell (Primary Cell) or PSCell (Primary Secondary Cell or Primary SCG (Secondary Cell Group) Cell) is not considered.

[0036] <1-1-3. Cell-Based Communication> In conventional communication (hereinafter also referred to as cell-based communication), a base station forms a cell and communicates with a terminal device within the cell.

[0037] Fig. 4 is a diagram showing an example of communication by base stations. In Fig. 4, base stations 20_1 and 20_2 each form the same cell and communicate with a terminal device 40 in cell C1. Each of the base stations 20_1 and 20_2 has, for example, an antenna panel and forms at least one beam in cell C1. For example, in Fig. 4, the base station 20_2 forms a beam B1 and communicates with the terminal device 40.

[0038] <1-1-4. Distributed Antennas> On the other hand, there is a type of communication that is different from conventional cell-based communication, called communication based on distributed antennas. In communication based on distributed antennas, multiple distributed base stations cooperate to communicate with terminal devices. In this way, in communication based on distributed antennas (hereinafter also referred to as distributed antenna communication), terminal devices communicate in a distributed antenna environment formed by distributed base stations.

[0039] In conventional cell-based communication, the number of base stations that make up one communication is generally about one to four. On the other hand, in distributed antenna communication, the number of base stations that make up one communication is large. In other words, the number of base stations in distributed antenna communication is greater than the number of base stations in cell-based communication. Here, one communication is the number of base stations that can communicate with one terminal device.

[0040] In addition, in conventional cell-based communication, the areas (cells) in which communication services are provided are fixed for each area, whereas in distributed antenna communication, the areas in which communication services are provided can be variably set according to requests from terminal devices, for example.

[0041] For example, in distributed antenna communication, a base station that actually forms part of communication is selected from multiple distributed base stations in response to a request from a terminal device, etc. The terminal device communicates with the selected base station. Depending on which base station is selected, an area in which communication services are provided to the terminal device is arbitrarily set.

[0042] <1-2. Problems> As described above, in distributed antenna communication, a base station that configures communication is selected in response to a request from a terminal device, etc. In other words, in distributed antenna communication, a base station that communicates with a terminal device can be selected in response to a request from the terminal device, etc.

[0043] In conventional cell-based communications, even base stations that are not part of a communication network (base stations that do not communicate with terminal devices) are always in operation, or only some of their functions are stopped while the rest remain in operation.

[0044] On the other hand, in distributed antenna communication, it may be desirable for base stations that are not involved in communication to stop functioning partially or completely.

[0045] 5 is a diagram illustrating an example of a communication system according to an embodiment of the present disclosure. As shown in FIG. 5, the communication system according to the embodiment includes a plurality of base stations 20 and at least one terminal device 40.

[0046] The multiple base stations 20 include a macro base station (Macro-gNB) 20A that has a wide area for providing communication services (hereinafter also referred to as communication range), and multiple distributed base stations 20B1 to 20B14 that have narrower communication ranges.

[0047] The number of macro base stations 20A and distributed base stations 20B is not limited to the example in Fig. 5. The number of macro base stations 20A may be two or more. The number of distributed base stations 20B may be 13 or less, or 15 or more.

[0048] 5, the service area in which the macro base station 20A provides service, i.e., the range in which the terminal device 40 can receive radio waves emitted by the macro base station 20A, is shown by a solid line. The service area in which the distributed base station 20B provides service, i.e., the range in which the terminal device 40 can receive radio waves emitted by the distributed base station 20B, is shown by a dotted line.

[0049] The terminal device 40 communicates with, for example, at least a part of the distributed base station 20B. In the example of Fig. 5, the distributed base stations 20B1 to 20B4 communicate with the terminal device 40_1 in a coordinated manner. The distributed base stations 20B1 to 20B4 are also referred to as a CoMP (Coordinated Multi-Point Transmission and Reception) cluster CC1.

[0050] The distributed base stations 20B5 to 20B7 communicate with the terminal device 40_2 in a coordinated manner. The distributed base stations 20B5 to 20B7 are also referred to as a CoMP (Coordinated Multi-Point Transmission and Reception) cluster CC2.

[0051] Here, it is assumed that the distributed base stations 20B8 to 20B14 are not configured for communication, that is, are not communicating with the terminal device 40.

[0052] In this way, the multiple distributed base stations 20B may be divided into distributed base stations 20B1 to 20B7 that communicate with the terminal device 40 and distributed base stations 20B8 to 20B14 that do not communicate with the terminal device 40, depending on the location and communication requests of the terminal device 40, etc.

[0053] For example, the distributed base stations 20B may be divided according to the location of the terminal device 40. For example, a distributed base station 20B whose distance to the terminal device 40 is equal to or less than a predetermined value communicates with the terminal device 40. On the other hand, a distributed base station 20B whose distance to the terminal device 40 is greater than the predetermined value does not communicate with the terminal device 40.

[0054] Alternatively, the distributed base stations 20B may be divided according to the communication request of the terminal device 40. For example, depending on whether the communication request is for highly reliable communication and / or high-speed communication, the multiple distributed base stations 20B are divided into distributed base stations 20B that perform communication and distributed base stations 20B that do not perform communication. Note that which distributed base station 20B is selected as the distributed base station 20B that performs communication can be determined according to, for example, the performance and location of the distributed base station 20B, the number of distributed base stations 20B to be selected, etc.

[0055] As described above, in distributed antenna communication, the number of base stations 20 included in the communication system increases. Therefore, an increase in the power consumption of the base stations 20 becomes a problem. To solve this problem, it is desirable to shut down the transmission of the distributed base station 20B that is not communicating. Specifically, it is desirable to shut down the transmission circuit and / or the reception circuit of the distributed base station 20B that is not communicating.

[0056] In this embodiment, the suspension of transmission by the distributed base station 20B includes a complete suspension (complete suspension) in which the distributed base station 20B stops transmitting all signals, and a partial suspension (partial suspension) in which most signals are suspended except for a very small number of signals.

[0057] In a complete shutdown, as described above, it is preferable that the distributed base station 20B stop transmitting all signals. For example, when communication with the terminal device 40 is not performed (the terminal device 40 is not present in the communication range), the distributed base station 20B preferably stops transmitting synchronization signals and system information (e.g., MIB (Master Information Block), SIB (System Information Block) 1) required for cell search and initial access. In this case, it is also preferable that the distributed base station 20B stop transmitting CSI-RS required for TRP measurement and tracking.

[0058] For example, in Figure 5, distributed base stations 20B1 to 20B7 that communicate with terminal devices 40_1 and 40_2 are emitting radio waves, but distributed base stations 20B8 to 20B14 that are not communicating with terminal device 40 are not emitting radio waves and are in a stopped state.

[0059] In this way, by stopping the transmission of the distributed base station 20B that is not communicating with the terminal device 40, the communication system can suppress an increase in power consumption.

[0060] On the other hand, it is difficult for the terminal device 40 to discover a completely stopped distributed base station 20B. For example, even if the terminal device 40_3 in Fig. 5 wants to communicate with the distributed base station 20B, it is difficult for the terminal device 40_3 to discover the distributed base stations 20B9 and 20B10 in the vicinity because the distributed base stations 20B9 and 20B10 are not emitting radio waves.

[0061] Therefore, an efficient procedure is required for discovering a distributed base station 20B with which the terminal device 40_3 can communicate, while suppressing an increase in the power consumption of the distributed base station 20B.

[0062] <1-3. Overview of Proposed Technology> Fig. 6 is a diagram illustrating an overview of communication processing related to the proposed technology of an embodiment of the present disclosure. The communication processing of Fig. 6 is executed, for example, in the above-described communication system. As described above, the communication system includes a plurality of base stations 20 (an example of a communication device) that operate in coordination with each other, and a terminal device 40 that communicates with at least one of the plurality of base stations 20.

[0063] 6 illustrates only the base station 20 that communicates with the terminal device 40, and omits illustration of other base stations 20. Also, the base station 20 in FIG. 6 is assumed to have stopped signal transmission (partially stopped) except for transmission of some signals (for example, a setting signal, which will be described later).

[0064] The terminal device 40 receives a setting signal (WUS (WakeUp Signal) configuration in FIG. 6) for transmitting a request to transmit a synchronization signal for initial connection (step S1).

[0065] The terminal device 40 transmits a transmission request (WUS in FIG. 6) to the base station 20 in which at least a part of the communication function is stopped in response to the setting signal (step S2). As described above, the base station 20 in which at least a part of the communication function is stopped is partially stopped transmitting.

[0066] In response to the transmission request, the base station 20 transmits a synchronization signal (on-demand SS in FIG. 6) for initial connection to the terminal device (step S3).

[0067] This allows the terminal device 40 to use the synchronization signal to connect to some of the base stations 20 that are not transmitting. In this way, the communication system according to the proposed technology can find a base station 20 with which the terminal device 40 can communicate, while suppressing an increase in the power consumption of the base station 20.

[0068] Here, it has been assumed that the terminal device 40 receives the setting signal from the base station 20 that is the destination of the transmission request, but the source of the setting signal is not limited to the base station 20 that is the destination of the transmission request.

[0069] For example, the terminal device 40 may receive a setting signal from another base station 20 in the communication system. Alternatively, the terminal device 40 may receive a setting signal from a communication device (for example, a Wi-Fi (registered trademark) access point) that communicates in accordance with a RAT different from the RAT supported by the communication system.

[0070] When the terminal device 40 receives a setting signal from a communication device other than the base station 20 to which the transmission request is sent, the base station 20 to which the transmission request is sent can also stop sending the setting signal, thereby enabling the communication system to further reduce increases in power consumption.

[0071] The base stations 20 that are partially out of service are not limited to distributed base stations (for example, cell-free base stations), and may be cell-based base stations.

[0072] For example, when the base station 20 is configured to manage multiple cells (for example, a PCell, an SCell, or an SCell), signals may be stopped in at least one of the multiple cells. When the base station 20 manages (operates) multiple cells, the proposed technology of the present disclosure can be applied to allow the terminal device 40 to connect to the cell in which signals are stopped.

[0073] Alternatively, even when the base station 20 manages one cell (for example, PCell), there is a possibility that the base station 20 may stop transmitting signals. In this case, the proposed technology can be applied.

[0074] In the following, for the sake of simplicity, unless otherwise specified, the explanation will be given taking the case where the base station 20 is a distributed base station as an example, but the base station 20 may also be a cell-based base station that manages a cell (e.g., a PCell, an SCell, or an SCell).

[0075] <<2. Configuration Example of Communication System>> <2-1. Configuration Example of Base Station> The base station 20 is a communication device that provides wireless communication services to one or more terminal devices 40 located within its communication range in accordance with any wireless communication method such as LTE or NR. The base station 20 is connected to a core network (not shown). The core network is connected to a packet data network (PDN) (not shown) via a gateway device (not shown).

[0076] The base station 20 may be configured as a collection of multiple physical or logical devices. For example, in the embodiment of the present disclosure, the base station 20 may be divided into multiple devices, a baseband unit (BBU) and a radio unit (RU), and may be interpreted as a collection of these multiple devices.

[0077] Additionally or alternatively, in the embodiment of the present disclosure, the base station 20 may be either or both of a BBU and an RU. The BBU and the RU may be connected via a predetermined interface (e.g., eCPRI). Additionally or alternatively, the RU may be referred to as a Remote Radio Unit (RRU) or a Radio DoT (RD).

[0078] Additionally or alternatively, the RU may correspond to a gNB-DU, as described below. Additionally or alternatively, the BBU may correspond to a gNB-CU, as described below. Additionally or alternatively, the RU may be a device integrally formed with an antenna.

[0079] The antennas of the base station 20 (e.g., antennas integrally formed with the RUs) may employ an Advanced Antenna System and support MIMO (e.g., FD-MIMO) and beamforming. In the Advanced Antenna System, the antennas of the base station 20 (e.g., antennas integrally formed with the RUs) may include, for example, 64 transmitting antenna ports and 64 receiving antenna ports.

[0080] Furthermore, multiple base stations 20 may be connected to each other. One or more base stations 20 may be included in a radio access network (RAN). That is, the base station 20 may be simply referred to as a RAN, a RAN node, an AN (Access Network), or an AN node.

[0081] The RAN in LTE is called EUTRAN (Enhanced Universal Terrestrial RAN). The RAN in NR is called NGRAN. The RAN in W-CDMA (UMTS) is called UTRAN. The base station 20 in LTE is called eNodeB (Evolved Node B) or eNB. That is, the EUTRAN includes one or more eNodeBs (eNBs).

[0082] The NR base station 20 is also referred to as a gNodeB or gNB. That is, the NGRAN includes one or more gNBs. Furthermore, the EUTRAN may include a gNB (en-gNB) connected to the core network (EPC) in the LTE communication system (EPS).

[0083] Similarly, the NGRAN may include an ng-eNB connected to a core network 5GC in a 5G communication system (5GS). Additionally or alternatively, when the base station 20 is an eNB, a gNB, or the like, it may be referred to as 3GPP Access.

[0084] Additionally or alternatively, when the base station 20 is a wireless access point, it may be referred to as a non-3GPP access point. Additionally or alternatively, the base station 20 may be a radio device called an RRH (Remote Radio Head).

[0085] Additionally or alternatively, if the base station 20 is a gNB, the base station 20 may be referred to as a combination of the aforementioned gNB CU (Central Unit) and gNB DU (Distributed Unit), or any of these.

[0086] The gNB CU (Central Unit) hosts multiple upper layers (e.g., RRC, SDAP, PDCP) in the Access Stratum for communication with the UE, while the gNB-DU hosts multiple lower layers (e.g., RLC, MAC, PHY) in the Access Stratum.

[0087] That is, among the messages and information described below, RRC signaling (e.g., MIB, various SIBs including SIB1, RRC Setup message, RRC Reconfiguration message) is generated by the gNB CU, while DCI and various Physical Channels (e.g., PDCCH, PBCH) described below may be generated by the gNB-DU.

[0088] Alternatively, some configurations of the RRC signaling, such as IE:cellGroupConfig, may be generated by the gNB-DU, and the remaining configurations may be generated by the gNB-CU. These configurations may be transmitted and received over the F1 interface described below. The base station 20 may be configured to be able to communicate with other base stations 20.

[0089] For example, when multiple base stations 20 are eNBs or a combination of an eNB and an en-gNB, the base stations 20 may be connected to each other via an X2 interface. Additionally or alternatively, when multiple base stations 20 are gNBs or a combination of a gn-eNB and a gNB, the devices may be connected to each other via an Xn interface. Additionally or alternatively, when multiple base stations 20 are a combination of a gNB CU (Central Unit) and a gNB DU (Distributed Unit), the devices may be connected to each other via the above-mentioned F1 interface.

[0090] Messages and information (RRC signaling or DCI information, Physical Channel) described below may be communicated between multiple base stations 20 (e.g., via X2, Xn, and F1 interfaces).

[0091] Furthermore, the base station 20 may be configured to manage multiple cells. A cell provided by the base station 20 is called a serving cell. The serving cell includes a PCell (Primary Cell) and an SCell (Secondary Cell). When dual connectivity (e.g., EUTRA-EUTRA Dual Connectivity, EUTRA-NR Dual Connectivity (ENDC), EUTRA-NR Dual Connectivity with 5GC, NR-EUTRA Dual Connectivity (NEDC), NR-NR Dual Connectivity) is provided to a UE (e.g., a terminal device 40), the PCell and zero or more SCell(s) provided by a Master Node (MN) are called a Master Cell Group.

[0092] Furthermore, the serving cell may include a PSCell (Primary Secondary Cell or Primary SCG Cell). That is, when dual connectivity is provided to the UE, the PSCell and zero or more SCell(s) provided by a secondary node (SN) are referred to as a secondary cell group (SCG).

[0093] Unless special configuration (for example, PUCCH on SCell) is performed, the physical uplink control channel (PUCCH) is transmitted on the PCell and PSCell but not on the SCell. Also, radio link failure is detected on the PCell and PSCell but not on the SCell (it does not need to be detected). As such, the PCell and PSCell have special roles among the serving cell(s), and are therefore also called special cells (SpCells).

[0094] One cell may be associated with one Downlink Component Carrier and one Uplink Component Carrier. Furthermore, the system bandwidth corresponding to one cell may be divided into multiple Bandwidth Parts. In this case, one or multiple Bandwidth Parts (BWPs) may be configured for a UE, and one Bandwidth Part may be used by the UE as an Active BWP.

[0095] Furthermore, the radio resources (for example, frequency band, numerology (subcarrier spacing), slot format (Slot configuration)) that the terminal device 40 can use may differ for each cell, each component carrier, or each BWP.

[0096] 7 is a diagram illustrating a configuration example of a base station 20 according to an embodiment of the present disclosure. The base station 20 is a communication device (wireless system) that wirelessly communicates with a terminal device 40. The base station 20 is a type of information processing device.

[0097] The base station 20 includes a signal processing unit 21, a storage unit 22, a network communication unit 23, and a control unit 24. Note that the configuration shown in Fig. 7 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the base station 20 may be distributed and implemented in multiple physically separated devices.

[0098] The signal processing unit 21 is a wireless communication interface that performs wireless communication with other communication devices (for example, a terminal device 40 and another base station 20). The signal processing unit 21 operates under the control of the control unit 24. The signal processing unit 21 may be compatible with multiple wireless access methods. For example, the signal processing unit 21 may be compatible with both NR and LTE. The signal processing unit 21 may be compatible with other cellular communication methods such as W-CDMA and cdma2000. Furthermore, the signal processing unit 21 may be compatible with a wireless LAN communication method in addition to the cellular communication method. Of course, the signal processing unit 21 may only be compatible with one wireless access method.

[0099] The signal processing unit 21 includes a reception processing unit 211, a transmission processing unit 212, and an antenna 213. The signal processing unit 21 may include a plurality of reception processing units 211, a plurality of transmission processing units 212, and a plurality of antennas 213. When the signal processing unit 21 supports a plurality of radio access methods, each unit of the signal processing unit 21 may be configured individually for each radio access method. For example, when the base station 20 supports NR and LTE, the reception processing unit 211 and the transmission processing unit 212 may be configured individually for NR and LTE.

[0100] The reception processing unit 211 processes an uplink signal received via the antenna 213. The reception processing unit 211 includes a radio reception unit 211a, a demultiplexing unit 211b, a demodulation unit 211c, and a decoding unit 211d.

[0101] The radio receiving unit 211a performs down-conversion, removal of unnecessary frequency components, control of amplification level, quadrature demodulation, conversion to a digital signal, removal of guard intervals, extraction of frequency domain signals by fast Fourier transform, etc. on the uplink signal. For example, assume that the radio access method of the base station 20 is a cellular communication method such as LTE. In this case, the demultiplexing unit 211b separates uplink channels such as PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) and uplink reference signals from the signal output from the radio receiving unit 211a. The demodulating unit 211c demodulates the received signal using a modulation method such as BPSK (Binary Phase Shift Keying) or QPSK (Quadrature Phase Shift Keying) for the modulation symbols of the uplink channel. The modulation scheme used by the demodulator 211c may be multi-level QAM such as 16QAM (Quadrature Amplitude Modulation), 64QAM, or 256QAM. The decoder 211d performs decoding processing on the coded bits of the demodulated uplink channel. The decoded uplink data and uplink control information are output to the controller 24.

[0102] The transmission processing unit 212 performs processing for transmitting downlink control information and downlink data, and includes an encoding unit 212a, a modulation unit 212b, a multiplexing unit 212c, and a radio transmission unit 212d.

[0103] The encoder 212a encodes the downlink control information and downlink data input from the controller 24 using a coding method such as block coding, convolutional coding, or turbo coding. The modulator 212b modulates the coded bits output from the encoder 212a using a predetermined modulation method such as BPSK, QPSK, 16QAM, 64QAM, or 256QAM. The multiplexer 212c multiplexes the modulation symbols of each channel and the downlink reference signal and allocates the multiplexed signals to predetermined resource elements. The radio transmitter 212d performs various signal processing on the signal from the multiplexer 212c. For example, the radio transmitter 212d performs processing such as conversion to the time domain using a fast Fourier transform, addition of a guard interval, generation of a baseband digital signal, conversion to an analog signal, quadrature modulation, up-conversion, removal of unnecessary frequency components, and power amplification. The signal generated by the transmission processor 212 is transmitted from the antenna 213.

[0104] The storage unit 22 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 22 functions as a storage means of the base station 20.

[0105] The network communication unit 23 is a communication interface for communicating with other devices (e.g., other base stations 20). For example, the network communication unit 23 is a LAN (Local Area Network) interface such as a NIC (Network Interface Card). The network communication unit 23 may be a USB (Universal Serial Bus) interface configured by a USB host controller, a USB port, etc. The network communication unit 23 may also be a wired interface or a wireless interface. The network communication unit 23 functions as a network communication means of the base station 20. The network communication unit 23 communicates with other devices under the control of the control unit 24.

[0106] The control unit 24 is a controller that controls each unit of the base station 20. The control unit 24 is realized by a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). For example, the control unit 24 is realized by a processor executing various programs stored in a storage device inside the base station 20 using a RAM (Random Access Memory) or the like as a working area. The control unit 24 may also be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU, MPU, ASIC, and FPGA can all be considered as controllers.

[0107] 8 is a diagram illustrating a configuration example of a terminal device 40 according to an embodiment of the present disclosure. The terminal device 40 is a communication device (wireless system) that performs wireless communication with the base station 20. The terminal device 40 is a type of information processing device.

[0108] The terminal device 40 includes a signal processing unit 41, a storage unit 42, an input / output unit 43, and a control unit 44. Note that the configuration shown in Fig. 8 is a functional configuration, and the hardware configuration may be different from this. Furthermore, the functions of the terminal device 40 may be distributed and implemented in multiple physically separated components.

[0109] The signal processing unit 41 is a wireless communication interface that performs wireless communication with other communication devices (for example, the base station 20 and other terminal devices 40). The signal processing unit 41 operates under the control of the control unit 44. The signal processing unit 41 supports one or more wireless access methods. For example, the signal processing unit 41 supports both NR and LTE. The signal processing unit 41 may also support other wireless access methods such as W-CDMA (registered trademark) and cdma2000 (registered trademark).

[0110] The signal processing unit 41 includes a reception processing unit 411, a transmission processing unit 412, and an antenna 413. The signal processing unit 41 may include a plurality of reception processing units 411, a transmission processing unit 412, and an antenna 413. When the signal processing unit 41 supports a plurality of radio access methods, each unit of the signal processing unit 41 may be configured individually for each radio access method. For example, the reception processing unit 411 and the transmission processing unit 412 may be configured individually for LTE and NR. The configurations of the reception processing unit 411 and the transmission processing unit 412 are similar to those of the reception processing unit 211 and the transmission processing unit 212 of the base station 20.

[0111] The storage unit 42 is a data readable / writable storage device such as a DRAM, an SRAM, a flash memory, a hard disk, etc. The storage unit 42 functions as a storage means of the terminal device 40.

[0112] The input / output unit 43 is a user interface for exchanging information with the user. For example, the input / output unit 43 is an operation device such as a keyboard, a mouse, operation keys, or a touch panel that allows the user to perform various operations. Alternatively, the input / output unit 43 is a display device such as a liquid crystal display (LCD) or an organic electroluminescence display (OLED). The input / output unit 43 may be an audio device such as a speaker or a buzzer. The input / output unit 43 may also be a lighting device such as an LED (Light Emitting Diode) lamp. The input / output unit 43 functions as input / output means (input means, output means, operation means, or notification means) of the terminal device 40.

[0113] The control unit 44 is a controller that controls each unit of the terminal device 40. The control unit 44 is realized by a processor such as a CPU or an MPU. For example, the control unit 44 is realized by the processor executing various programs stored in a storage device inside the terminal device 40 using RAM or the like as a work area. The control unit 44 may also be realized by an integrated circuit such as an ASIC or an FPGA. A CPU, an MPU, an ASIC, and an FPGA can all be considered as controllers.

[0114] <<3. Technical Features>> <3-1. Overview> A base station 20 according to an embodiment of the present disclosure transmits a synchronization signal (hereinafter also referred to as on-demand SS) used for initial connection and system information (hereinafter also referred to as on-demand minimum system information (MSI)) used for access in response to a request (WUS) from a terminal device 40.

[0115] On the other hand, the base station 20 does not transmit these signals and / or information (on-demand SS and / or MSI) until a request is received from the terminal device 40 .

[0116] The request (WUS) sent by the terminal device 40 to the base station 20 is sent based on setting information (e.g., WUS configuration, WUS config) acquired before receiving the SSB (or on-demand SS).

[0117] This setting information may be, for example, a signal different from SSB, and may be transmitted by being included in an always-on signal that is always transmitted from the base station 20. Alternatively, this setting information may be information that is pre-configured in the terminal device 40.

[0118] Alternatively, the terminal device 40 may acquire this setting information from another base station 20 having a communication range different from that of the base station 20 to which the transmission request is sent, or from another terminal device 40. The terminal device 40 may acquire this setting information, for example, from a communication device (for example, a Wi-Fi access point) of a RAT different from the RAT supported by the base station 20 to which the transmission request is sent.

[0119] Furthermore, the request process (procedure) in which the terminal device 40 requests the transmission of an on-demand SS can be executed before or as part of the random access procedure.

[0120] 3-2. Scenarios The request processing according to this embodiment is executed in several deployment scenarios. Here, the request processing according to this embodiment will be described using three scenarios as examples.

[0121] <3-2-1. First Scenario> First, request processing in the first deployment scenario in which on-demand SS and / or MSI are supported will be described.

[0122] (Scenario Example) Fig. 9 is a diagram illustrating an example of a first deployment scenario according to an embodiment of the present disclosure. In Fig. 9, a stand-alone deployment scenario is illustrated as the first deployment scenario.

[0123] In this scenario, the terminal device 40 receives a setting signal (WUS configuration in FIG. 9 ) from the base station 20 that transmits a transmission request (WUS in FIG. 9 ). Note that the base station 20 in this scenario may be the macro base station 20A or the distributed base station 20B. However, if it is desirable for the macro base station 20A to transmit signals at all times, the base station 20 in FIG. 9 is preferably the distributed base station 20B.

[0124] In this way, a scenario in which the base station 20 that transmits the configuration signal receives a transmission request is called, for example, a standalone deployment scenario. That is, in the standalone deployment scenario, the request processing is executed by one base station 20 and the terminal device 40.

[0125] As described above, the base station 20 in this scenario may be a distributed base station or a base station that provides a cell (for example, a PCell or a PSCell). Similarly, the base station 20 in this scenario may provide an SCell.

[0126] (Request Processing Example) Fig. 10 is a sequence diagram showing an example of request processing executed in a first deployment scenario according to an embodiment of the present disclosure. The request processing shown in Fig. 10 is executed by a communication system. For example, the request processing shown in Fig. 10 is executed when a terminal device 40 connects to a base station 20. Note that the processing indicated by the dotted arrows in Fig. 10 may be omitted.

[0127] As shown in Fig. 10, the base station 20 transmits a first synchronization signal (Always-on SS in Fig. 10) (step S101). The first synchronization signal is a synchronization signal that the base station 20 transmits continuously even when the base station 20 is partially stopped (e.g., in a standby state) until it receives a request signal (e.g., WUS) from the terminal device 40. The first synchronization signal differs from conventional SSB in that it does not include a cell ID.

[0128] The base station 20 transmits a setting signal (WUS config in FIG. 10 , hereinafter also referred to as a first setting signal) (step S102). The first setting signal is a setting signal that the base station 20 constantly transmits even when some of its signals are stopped, until it receives a request signal (e.g., WUS) from the terminal device 40. The first setting signal includes setting information that is not based on a cell ID. For example, the terminal device 40 may receive the first setting signal in response to a first synchronization signal.

[0129] Upon receiving the first setting signal, the terminal device 40 transmits a request signal (WUS in FIG. 10) requesting the transmission of a synchronization signal for initial connection (hereinafter also referred to as the second synchronization signal) (step S103).

[0130] Upon receiving the request signal, the base station 20 transmits a WUS response (Response to WUS) (step S104) and transmits a second synchronization signal (On-demand SS in FIG. 10) to the terminal device 40 (step S105). The second synchronization signal is a synchronization signal for initial connection and includes information equivalent to a conventional cell ID. Note that the transmission of the WUS response (Response to WUS) may be omitted.

[0131] Next, the base station 20 transmits a second configuration signal (in FIG. 10 , an On-demand MSI) including system information to the terminal device 40 (step S106). The second configuration signal includes system information (e.g., MSI) used for access. As described above, the second configuration signal includes system information for initial connection.

[0132] The terminal device 40 that has received the second setting signal transmits a PRACH (Physical Random Access Channel) to the base station 20 (step S107).

[0133] The base station 20 that has received the PRACH transmits a RAR (Random Access Response) to the terminal device 40 (step S108).

[0134] The terminal device 40 that has received the RAR transmits a message 3 (Msg3) to the base station 20 (step S109). The base station 20 that has received the message 3 transmits a message 4 (Msg4) to the terminal device 40 (step S110), thereby completing the initial access procedure (random access procedure) and establishing an RRC connection (step S111).

[0135] Here, as described above, if the terminal device 40 previously stores the setting information for transmitting a WUS (information included in the setting signal (e.g., WUS config)), the base station 20 may omit transmitting the setting signal. An example of the request processing in this case will be described.

[0136] 11 is a sequence diagram showing another example of a request process executed in the first deployment scenario according to an embodiment of the present disclosure. The request process shown in FIG. 11 is executed by the communication system. For example, the request process shown in FIG. 11 is executed when the terminal device 40 connects to the base station 20. Note that the process indicated by the dotted arrow in FIG. 11 may be omitted.

[0137] The request processing in Fig. 11 differs from the request processing in Fig. 10 in that the setting signal (WUS config in Fig. 10) is not transmitted. Also, in the request processing in Fig. 11, the base station 20 may omit transmitting the first synchronization signal (Always-on SS). Except for these points, the request processing in Fig. 11 is the same as the request processing in Fig. 10, and therefore a description thereof will be omitted.

[0138] In this way, the communication system can execute a request process in which the terminal device 40 requests the transmission of an on-demand SS as a prelude to the random access procedure.

[0139] The communication system may execute a request process in which the terminal device 40 requests transmission of an on-demand SS as part of the random access procedure.

[0140] 12 is a sequence diagram showing another example of request processing executed in the first deployment scenario according to an embodiment of the present disclosure. The request processing shown in FIG. 11 is executed by the communication system. For example, the request processing shown in FIG. 12 is executed when the terminal device 40 connects to the base station 20. In the request processing in FIG. 12, the same processes as those in the request processing in FIG. 10 are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0141] As shown in Figure 12, when the base station 20 receives a request signal (WUS in Figure 12) in step S103, it transmits a second synchronization signal (On-demand SS in Figure 12) without transmitting a response to the WUS (Response to WUS).

[0142] Furthermore, the base station 20, which transmitted the second setting signal (On-demand MSI in FIG. 12) to the terminal device 40 in step S106, transmits an RAR including a response to the WUS to the terminal device 40 (step S201).

[0143] In this way, the communication system can perform a request process in which the terminal device 40 requests the transmission of an on-demand SS as part of a random access procedure.

[0144] <3-2-2. Second Scenario> Next, request processing in the second deployment scenario in which on-demand SS and / or MSI are supported will be described.

[0145] (Scenario Example) Fig. 13 is a diagram illustrating an example of a second deployment scenario according to an embodiment of the present disclosure. In Fig. 13, a multi-cell deployment scenario is illustrated as the second deployment scenario.

[0146] In this scenario, the terminal device 40 receives a first setting signal (WUS configuration in FIG. 13) from a base station 20 (in FIG. 13, an adjacent base station 20N (an example of another communication device) adjacent to the base station 20) different from the base station 20 that transmits the transmission request (WUS in FIG. 13).

[0147] For example, a coverage area R1 (corresponding to a conventional cell, for example) of the base station 20 in FIG. 13 partially overlaps with a coverage area R2 of the adjacent base station 20N.

[0148] In this scenario, the base station 20 and / or the neighboring base station 20N may be the macro base station 20A or the distributed base station 20B. However, if it is desirable for the macro base station 20A to constantly transmit a signal, the base station 20 in Fig. 13 is desirably the distributed base station 20B.

[0149] In this way, a scenario in which the base station 20 (neighboring base station 20N in FIG. 13) that transmits the first configuration signal and the base station 20 that receives the transmission request are different is called, for example, a multi-cell deployment scenario. That is, in the multi-cell deployment scenario, the request processing is executed by two base stations 20 and the terminal device 40.

[0150] Note that the base station 20 and the neighboring base station 20N in this scenario may be distributed base stations as described above, or may be base stations that provide a cell (e.g., PCell).

[0151] (Request Processing Example) Fig. 14 is a sequence diagram showing an example of request processing executed in the second deployment scenario according to an embodiment of the present disclosure. The request processing shown in Fig. 14 is executed by the communication system. For example, the request processing shown in Fig. 14 is executed when the terminal device 40 connects to the base station 20.

[0152] Note that the processes indicated by dotted arrows may be omitted in Fig. 14. In the processes in Fig. 14, the same processes as those in the request process in Fig. 11 are denoted by the same reference numerals, and the description thereof will be omitted.

[0153] As shown in Fig. 14, the neighboring base station 20N transmits a synchronization signal (SSB in Fig. 14) (step S301). This synchronization signal is different from the first and second synchronization signals described above. This synchronization signal may be the same as a conventional cell-based synchronization signal. Alternatively, this synchronization signal may include information indicating the transmission position of the first setting signal. That is, the terminal device 40 receives the first setting signal in response to the SSB (an example of a reception signal).

[0154] Furthermore, the neighboring base station 20N transmits a first setting signal (WUS config in FIG. 14) (step S302). This first setting signal includes setting information for the terminal device 40 to transmit a transmission request to the base station 20. The first setting signal includes setting information that is not based on a cell ID.

[0155] The subsequent processing is the same as that in FIG.

[0156] In this way, the communication system can execute a request process in which the terminal device 40 requests the transmission of an on-demand SS as a prelude to the random access procedure.

[0157] The communication system may execute a request process in which the terminal device 40 requests transmission of an on-demand SS as part of a random access procedure. In this case, the process from step S105 onward in the request process in Fig. 12 is executed as the process following step S101 in Fig. 14 .

[0158] Also, although the case where the terminal device 40 directly transmits a request to transmit a second synchronization signal (e.g., On-demand SS) to the base station 20 has been described here, the terminal device 40 may also make this transmission request via an adjacent base station 20N.

[0159] 15 is a sequence diagram illustrating another example of a request process executed in the second deployment scenario according to an embodiment of the present disclosure. The request process illustrated in FIG. 15 is executed by the communication system. For example, the request process illustrated in FIG. 15 is executed when the terminal device 40 connects to the base station 20.

[0160] Note that the processes indicated by dotted arrows may be omitted in Fig. 15. In the processes in Fig. 15, the same processes as those in the request process in Fig. 14 are denoted by the same reference numerals, and the description thereof will be omitted.

[0161] The terminal device 40, which has received the first setting signal (WUS config) in step S302, transmits a request signal (for example, WUS) to the adjacent base station 20N (step S401).

[0162] The neighboring base station 20N that has received the request signal transmits a WUS response (Response to WUS) (step S402). The transmission of this WUS response (Response to WUS) may be omitted.

[0163] The neighboring base station 20N transmits a command ("On-demand SS activation command" in FIG. 15) to activate transmission of a second synchronization signal ("On-demand SS" in FIG. 15) to the base station 20 (step S403). The subsequent processing is the same as in FIG. 14.

[0164] As described above, in the second scenario, the neighboring base station 20N adjacent to the base station 20 transmits a first configuration signal (e.g., WUS config) for transmitting a request signal (e.g., WUS) to the base station 20. This eliminates the need for the base station 20 to transmit the first configuration signal, thereby enabling further reduction in power consumption of the base station 20.

[0165] Furthermore, when the base station 20 does not transmit the first synchronization signal in addition to the first setting signal, the base station 20 can completely stop transmitting signals (complete suspension of transmission).

[0166] <3-2-3. Third Scenario> Request processing in the third deployment scenario in which on-demand SS and / or MSI are supported will now be described.

[0167] (Scenario Example) Fig. 16 is a diagram illustrating an example of a second deployment scenario according to an embodiment of the present disclosure. Fig. 16 illustrates a heterogeneous deployment scenario as a third deployment scenario.

[0168] In this scenario, the terminal device 40 receives a first setting signal (WUS configuration in FIG. 16) from a base station 20 (in FIG. 16, an adjacent base station 20N (an example of another communication device) adjacent to the base station 20) different from the base station 20 that transmits the transmission request (WUS in FIG. 16). Note that the frequency at which the WUS is transmitted and the frequency at which the WUS configuration is transmitted may be the same or different.

[0169] 16, for example, most (e.g., more than half) of the communication range R1 (e.g., corresponding to a conventional cell) of the base station 20 is included in the communication range R2 of the neighboring base station 20N. In this respect, the third deployment scenario differs from the second deployment scenario. Note that the entire communication range R1 may be included in the communication range R2 of the neighboring base station 20N.

[0170] For example, in the second deployment scenario, a terminal device 40 outside the communication range R2 (e.g., cell) of a neighboring base station 20N cannot receive the first setting signal (e.g., WUS config) even if it is within the communication range R1 of the base station 20, and cannot send a request signal (e.g., WUS) to the base station 20.

[0171] On the other hand, in the third deployment scenario, if the terminal device 40 is located within the communication range R1 of the base station 20, it will be located almost within the communication range R2 of the neighboring base station 20N. Therefore, when the terminal device 40 receives the first setting signal, it can transmit a request signal to the base station 20 in response to this first setting signal.

[0172] In this scenario, the base station 20 and / or the neighboring base station 20N may be the macro base station 20A or the distributed base station 20B. However, since most of the communication range R1 of the base station 20 is included in the communication range R2 of the neighboring base station 20N, it is preferable that the neighboring base station 20N is the macro base station 20A and the base station 20 is the distributed base station 20B.

[0173] In this way, a scenario in which the base station 20 (neighboring base station 20N in FIG. 13) that transmits the first configuration signal and the base station 20 that receives the transmission request are different is called, for example, a heterogeneous deployment scenario. That is, in the heterogeneous deployment scenario, the request processing is executed by two base stations 20 and the terminal device 40.

[0174] The request processing executed in the third scenario is the same as the request processing executed in the second scenario (see FIGS. 14 and 15), and therefore will not be described here.

[0175] As described above, the neighboring base station 20N in this scenario may be a distributed base station or a base station that provides a cell (e.g., a PCell or a PSCell). Also, the base station 20 in this scenario may be a distributed base station or a base station that provides a cell (e.g., an SCell).

[0176] <3-3. Signaling Example> Here, an example of signals exchanged between the base station 20 and the terminal device 40 in request processing in the communication system will be described.

[0177] (Second Synchronization Signal (On-Demand SS)) The second synchronization signal is transmitted from the base station 20, for example, in response to a request from the terminal device 40. For example, the base station 20 stops transmitting the second synchronization signal until it receives a request signal from the terminal device 40. Such a synchronization signal transmitted by the base station 20 in response to a request from the terminal device 40 is also referred to as a semi-persistent SS or an aperiodic SS.

[0178] When the base station 20 is transmitting the second synchronization signal and receives a stop request signal to stop transmission of the second synchronization signal from the terminal device 40, the base station 20 stops transmitting the second synchronization signal. Alternatively, the base station 20 may stop transmitting the second synchronization signal when a predetermined period has elapsed since the base station 20 started transmitting the second synchronization signal.

[0179] The second synchronization signal may be transmitted, for example, in bursts.

[0180] All of the second synchronization signals transmitted from the base station 20 may be transmitted / stopped in response to a request from the terminal device 40. Alternatively, some of the second synchronization signals transmitted from the base station 20 may be transmitted / stopped in response to a request from the terminal device 40.

[0181] For example, the base station 20 transmits / stops part of the second synchronization signal in association with the beam. For example, the base station 20 transmits / stops the second synchronization signal transmitted using the first beam in accordance with a request from the terminal device 40. On the other hand, the base station 20 transmits the second synchronization signal transmitted using the second beam, for example, at all times, regardless of a request from the terminal device 40.

[0182] Alternatively, the base station 20 may change the transmission method of the second synchronization signal in association with the beam. For example, the base station 20 changes the transmission interval of the second transmission signal transmitted using the second beam in accordance with a request from the terminal device 40.

[0183] The base station 20 may change the method of transmitting the secondary synchronization signal depending on, for example, the identification information (SSB index) of the beam that transmits the secondary synchronization signal.

[0184] For example, the base station 20 may transmit / stop part of the second synchronization signal in accordance with the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). For example, when the base station 20 transmits the second synchronization signal as a secondary synchronization signal, the base station 20 transmits / stops the second synchronization signal in accordance with a request from the terminal device 40.

[0185] On the other hand, when transmitting a second synchronization signal as a primary synchronization signal, the base station 20 always transmits the second synchronization signal regardless of a request from the terminal device 40. Alternatively, when transmitting a second synchronization signal as a primary synchronization signal, the base station 20 may change the transmission method of the second synchronization signal in accordance with a request from the terminal device 40. For example, the base station 20 changes the transmission interval of the second transmission signal transmitted as a primary synchronization signal in accordance with a request from the terminal device 40.

[0186] For example, the base station 20 may transmit / stop the second synchronization signal depending on the type of signal. For example, when the second synchronization signal is transmitted as a PBCH (Physical Broadcast Channel), the base station 20 transmits / stops the second synchronization signal in accordance with a request from the terminal device 40.

[0187] On the other hand, when transmitting the second synchronization signal as a PSS and / or SSS, the base station 20 always transmits the second synchronization signal regardless of a request from the terminal device 40. Alternatively, when transmitting the second synchronization signal as a PSS and / or SSS, the base station 20 may change the transmission method of the second synchronization signal in accordance with a request from the terminal device 40. For example, the base station 20 changes the transmission interval of the second transmission signal transmitted as a PSS and / or SSS in accordance with a request from the terminal device 40.

[0188] Here, it is stated that the base station 20 transmits / stops the second synchronization signal in accordance with a request from the terminal device 40, but the base station 20 may also change the method of transmitting the second synchronization signal in accordance with a request from the terminal device 40.

[0189] For example, in the above embodiment, the base station 20 transmits / stops the second synchronization signal in response to a request from the terminal device 40. However, the base station 20 may transmit the second synchronization signal by changing the parameters.

[0190] For example, the base station 20 transmits the second synchronization signal periodically, but changes the transmission parameters of the second synchronization signal in accordance with a request from the terminal device 40 .

[0191] For example, the base station 20 changes the periodicity of the second synchronization signal as a transmission parameter. For example, the base station 20 transmits the second synchronization signal at the first period until it receives a request signal (for example, a WUS) from the terminal device 40.

[0192] When the base station 20 receives a request signal (e.g., WUS) from the terminal device 40, it transmits a second synchronization signal at a second period that is shorter than the first period. When the base station 20 receives a stop request signal from the terminal device 40, it returns the period of the second synchronization signal from the second period to the first period.

[0193] For example, the base station 20 changes the bandwidth of the second synchronization signal as a transmission parameter. For example, the base station 20 transmits the second synchronization signal at the first bandwidth until it receives a request signal (e.g., WUS) from the terminal device 40.

[0194] The base station 20 transmits a second synchronization signal at a second bandwidth wider than the first bandwidth when it receives a request signal (e.g., WUS) from the terminal device 40. When it receives a stop request signal from the terminal device 40, the base station 20 returns the bandwidth of the second synchronization signal from the second bandwidth to the first bandwidth.

[0195] For example, when the second synchronization signal is transmitted in bursts, the base station 20 changes the number of second synchronization signals (the number of bursts) as a transmission parameter. For example, the base station 20 transmits the second synchronization signal with the first number of bursts until it receives a request signal (e.g., WUS) from the terminal device 40.

[0196] When the base station 20 receives a request signal (e.g., WUS) from the terminal device 40, it transmits a second synchronization signal with a second number of bursts that is greater than the first number of bursts. When the base station 20 receives a stop request signal from the terminal device 40, it returns the number of bursts of the second synchronization signal from the second number of bursts to the first number of bursts.

[0197] (Second Setting Signal (On-demand MSI)) The second setting signal is transmitted from the base station 20, for example, in response to a request from the terminal device 40. For example, the base station 20 stops transmitting the second setting signal until it receives a request signal from the terminal device 40.

[0198] When base station 20 is transmitting the second setting signal, it stops transmitting the second setting signal upon receiving a stop request signal to stop transmitting the second setting signal from terminal device 40. Alternatively, base station 20 may stop transmitting the second setting signal when a predetermined period has elapsed since it started transmitting the second setting signal.

[0199] All of the second setting signals transmitted from the base station 20 may be transmitted / stopped in accordance with a request from the terminal device 40. Alternatively, some of the second setting signals transmitted from the base station 20 may be transmitted / stopped in accordance with a request from the terminal device 40.

[0200] For example, the base station 20 transmits / stops transmitting the second setting signal including part of the system information in accordance with a request from the terminal device 40. On the other hand, the base station 20 transmits the second setting signal including the remaining system information, for example, at all times, regardless of a request from the terminal device 40.

[0201] (Request Signal (WUS)) The request signal is set by setting information (first setting information) that does not depend on information (e.g., a cell ID) that identifies the communication range (e.g., a cell) of the base station 20. Specifically, the request signal is transmitted without relying on a second synchronization signal (On-demand SS (SSB)). The terminal device 40 transmits a WUS before receiving the second synchronization signal, i.e., before acquiring information that identifies the communication range of the base station 20.

[0202] Here, the request signal being set without depending on information identifying the communication range of the base station 20 means that the request signal is set in common to all base stations 20 (more specifically, the communication ranges of all base stations 20). Alternatively, the request signal being set without depending on information identifying the communication range of the base station 20 means that the request signal is set as frequency-specific information.

[0203] As described above, the request signal is used by the terminal device 40 to request the base station 20 to transmit a second synchronization signal for initial connection. In other words, the request signal is used to resume operation of the base station 20 that has been partially or completely stopped transmitting (in standby mode).

[0204] Therefore, the transmission of a request signal does not affect the transmission of uplink signals between terminal devices 40. In other words, when a terminal device 40 transmits a request signal, the base station 20 is not communicating with another terminal device 40. Therefore, the transmission of a request signal by a terminal device 40 does not need to take into account uplink transmissions by the other terminal devices 40.

[0205] Therefore, the transmission of the request signal may be performed using the same uplink resources in all base stations 20 .

[0206] Alternatively, the terminal device 40 may transmit a request signal with different settings for each area. For example, when the terminal device 40 transmits a request signal including information other than a request to transmit a second synchronization signal for initial connection, the terminal device 40 may transmit the request signal with different settings for each area. In other words, the request signal may include information common to multiple base stations.

[0207] Here, the area refers to a range that collectively includes the communication ranges (for example, cells) of a plurality of base stations 20. The area here is wider than the communication range of a single base station 20.

[0208] This area is configured as a unit for setting uplink resources used to transmit a request signal. For example, if the area is different, the request signal is transmitted using different uplink resources. In other words, the setting of the request signal is linked to the area, which is defined as a unit of uplink resources.

[0209] In this way, when an area is configured as a unit for setting uplink resources, the area can be configured as a unit of uplink coverage.

[0210] The resource for transmitting the request signal is, for example, linked to the first synchronization signal. For example, the resource for transmitting the request signal is linked to the location of the first synchronization signal. Specifically, the first configuration information specifies an uplink resource for transmitting the request signal based on the location of the first synchronization signal.

[0211] (First Synchronization Signal (Always-on SS) / First Configuration Signal (WUS Configuration)) The first synchronization signal is a synchronization signal (SS for WUS) for transmitting a request signal. The first configuration signal is a configuration signal (System Information (SI) for WUS) for transmitting a request signal.

[0212] For example, in the first scenario described above, the request process is executed by one base station 20 and the terminal device 40. That is, the terminal device 40 does not receive the first synchronization signal and / or the first setting signal from another base station 20.

[0213] Therefore, the base station 20 always transmits a signal for the terminal device 40 to transmit a request signal. This always-transmitted signal is also referred to as an always-on signal. The first synchronization signal and / or the first setting signal is, for example, the always-on signal.

[0214] In this respect, the first synchronization signal and / or the first setting signal differ from the second synchronization signal (On-demand SS) and / or the second setting signal (On-demand MSI), which are transmitted / stopped according to a request from the terminal device 40.

[0215] That is, the base station 20 stops transmitting signals other than the continuous transmission signal (e.g., the first synchronization signal and / or the first setting signal) until it receives a request signal from the terminal device 40.

[0216] In the second and third scenarios, the request process is executed by two base stations 20 and the terminal device 40. At this time, the terminal device 40 acquires, for example, setting information for transmitting a request signal from the adjacent base station 20N.

[0217] In the above example, the terminal device 40 acquires the setting information from the first setting signal transmitted by the adjacent base station 20N, but the terminal device 40 may acquire the setting information from a signal other than the first setting signal.

[0218] For example, if the terminal device 40 is already connected to the neighboring base station 20N, the terminal device 40 may acquire configuration information for transmitting a request signal via RRC signaling. In this case, the neighboring base station 20N may omit transmitting the first synchronization signal and / or the first configuration signal.

[0219] (Details of the First Synchronization Signal (Always-on SS)) The first synchronization signal is preferably transmitted from the base station 20 with lower power consumption than conventional synchronization signals. For example, the first synchronization signal is preferably transmitted with a longer periodicity than conventional synchronization signals (e.g., SSB). This allows the base station 20 to stop signal transmission (stop transmission) for a longer period of time, thereby reducing the power consumption of the base station 20.

[0220] Specifically, for example, the periodicity of the SSB used for initial access is 20 msec, and it is preferable that the first synchronization signal be transmitted at a period longer than 20 msec (for example, 80 msec).

[0221] For example, it is preferable that the first synchronization signal be transmitted with a narrower bandwidth than a conventional synchronization signal (e.g., SSB), which allows the base station 20 to concentrate the power of the first synchronization signal and ensure sufficient coverage with less transmission power.

[0222] Specifically, for example, the bandwidth of the SSB used for initial access is 20 PRBs. The bandwidth of the primary synchronization signal is preferably narrower than that. For example, the bandwidth of the primary synchronization signal may be 15 PRBs, which can support up to 30 MHz.

[0223] For example, the first synchronization signal preferably contains less information than a conventional synchronization signal (e.g., SSB). For example, PSS carries three cell IDs, while SSS carries 336 cell IDs. Therefore, SSB carries 3*336=1008 cell IDs.

[0224] On the other hand, the first synchronization signal does not carry a cell ID (or information that identifies the communication range of the base station 20, which corresponds to a cell ID). Note that the first synchronization signal may carry information about the area (e.g., area identification information). That is, the first synchronization signal may include information common to multiple base stations. Here, the area is a range wider than the communication range of the base station 20, as described above, and is, for example, a range that combines the communication ranges of multiple base stations 20.

[0225] For example, conventional synchronization signals (e.g., SSB) are used for various purposes such as cell detection, cell ID notification, frame synchronization, frequency synchronization, PBCH decoding, and RSRP measurement. On the other hand, the first synchronization signal according to this embodiment is used for receiving at least a first configuration signal. Specifically, the first synchronization signal is used for time and / or frequency synchronization and decoding of the first configuration signal.

[0226] The first synchronization signal may be used auxiliary to the conventional synchronization signal. For example, the first synchronization signal may also be used for frame synchronization. This allows the terminal device 40 to recognize a radio frame and identify a transmission resource for a request signal (e.g., a WUS) within the radio frame.

[0227] The first synchronization signal does not need to be defined separately as a synchronization signal (SS), but may be defined as a DMRS of the first configuration signal.

[0228] The first synchronization signal may be designed (configured) as part of a conventional synchronization signal. For example, the PSS may be the first synchronization signal and the SSS may be the second synchronization signal. Alternatively, the first synchronization signal may be configured differently from the conventional synchronization signal.

[0229] (Details of the First Configuration Signal (WUS Configuration)) It is preferable that the first configuration signal be transmitted from the base station 20 with lower power consumption than a conventional configuration signal (system information (SI)).

[0230] The first configuration signal may be received and decoded independently of the first synchronization signal. For example, the terminal device 40 may receive and decode the first configuration signal using preconfigured information. In this case, transmission of the first synchronization signal may be omitted.

[0231] Alternatively, the first setting signal may be received or decoded based on the first synchronization signal. For example, the first synchronization signal may include information for receiving and / or decoding the first setting signal. Alternatively, the first synchronization signal may include information indicating the location of the information for receiving and / or decoding the first setting signal.

[0232] The periodicity of the first setting signal is preferably the same as or longer than the periodicity of the first synchronization signal.

[0233] The first configuration signal preferably includes less information than a conventional configuration signal (SI). For example, the conventional SI notifies detailed information specific to a cell. On the other hand, the first configuration signal does not carry information dependent on the cell (the communication range of the base station 20). The first configuration signal includes information that is not dependent on identification information (e.g., information equivalent to a cell ID) that identifies the communication range of the base station 20.

[0234] The first setting signal may carry information about the area (e.g., area-specific information). Here, the area is a range wider than the communication range of the base station 20 as described above, for example, a range that aggregates the communication ranges (cells) of multiple base stations 20. In other words, the first setting signal may include information about settings common to multiple base stations.

[0235] Furthermore, the first configuration signal may not include information related to synchronization (e.g., SSB). For example, the first configuration signal may be configured not to include information related to the first synchronization signal and / or the second synchronization signal.

[0236] While the conventional SI is transmitted to notify detailed settings related to a cell, the first setting signal according to the present embodiment is used to notify settings for at least transmitting a request signal (e.g., WUS).

[0237] For example, when the base station 20 receives a WUS and transmits system information (e.g., second setting information) in response to the WUS, the base station 20 notifies the terminal device 40 of information that was not notified in the first setting information as the second setting information. This second setting information does not have to include the information included in the first setting information.

[0238] Alternatively, if the information contained in the first setting information is also included in the second setting information, the terminal device 40 may discard the information received later (the same information as the first setting information contained in the second setting information).

[0239] In this case, the second setting information may include the same information as the conventional SI. Even in this case, the present embodiment differs from the conventional SI in that the second setting information is notified by the base station 20 in response to a request (WUS) from the terminal device 40.

[0240] The first setting information may be designed (configured) as part of conventional setting information (e.g., SI). For example, the first setting information may be configured as CORESET#0 and the second setting information may be configured as SIB1. Alternatively, the first setting information may be configured as SIB1 and the second setting information may be configured as CORESET#0.

[0241] Alternatively, the first configuration information may be designed (configured) as information different from the conventional configuration information. For example, SI for the first configuration information may be independently defined. In this case, the SI for the first configuration information may include, for example, information on at least time and / or frequency resources, power, and coding for transmitting a request signal.

[0242] <<4. Hardware Configuration Example>> Information devices such as the base station 20 and the terminal device 40 according to the above-described embodiments are realized by, for example, a computer 1000 configured as shown in Fig. 17. Fig. 17 is a hardware configuration diagram showing an example of the computer 1000. The computer 1000 includes a CPU 1100, a RAM 1200, a ROM (Read Only Memory) 1300, an SSD (Solid State Drive) 1400, a communication interface 1500, and an input / output interface 1600. The components of the computer 1000 are connected by a bus 1050.

[0243] The CPU 1100 operates and controls each component based on programs stored in the ROM 1300 or the SSD 1400. For example, the CPU 1100 loads the programs stored in the ROM 1300 or the SSD 1400 into the RAM 1200 and executes processing corresponding to the various programs.

[0244] The ROM 1300 stores boot programs such as a Basic Input Output System (BIOS) that is executed by the CPU 1100 when the computer 1000 is started, and programs that depend on the hardware of the computer 1000 .

[0245] The SSD 1400 is a computer-readable recording medium that non-temporarily records programs executed by the CPU 1100 and data used by such programs. Specifically, the SSD 1400 is a recording medium that records a communication program according to the present disclosure, which is an example of the program data 1450. The SSD 1400 may be another non-temporary recording medium, such as a hard disk drive (HDD).

[0246] The communication interface 1500 is an interface for connecting the computer 1000 to an external network 1550 (e.g., the Internet). For example, the CPU 1100 receives data from other devices and transmits data generated by the CPU 1100 to other devices via the communication interface 1500.

[0247] The input / output interface 1600 is an interface for connecting the input / output device 1650 and the computer 1000. For example, the CPU 1100 receives data from input devices such as a touch panel, keyboard, mouse, microphone, and camera via the input / output interface 1600. The CPU 1100 also transmits data to output devices such as a display, speaker, and printer via the input / output interface 1600. The input / output interface 1600 may also function as a media interface for reading programs and the like recorded on a predetermined recording medium. Examples of media include optical recording media such as DVDs (Digital Versatile Discs) and PDs (Phase Change Rewritable Discs), magneto-optical recording media such as MOs (Magneto-Optical Disks), tape media, magnetic recording media, and semiconductor memories.

[0248] For example, when the computer 1000 functions as the base station 20 or the terminal device 40 according to the embodiment, the CPU 1100 of the computer 1000 executes a communication program loaded onto the RAM 1200 to realize the functions of the control unit 24 or the control unit 44, etc. The communication program according to the present disclosure and data in the RAM 1200 are stored in the SSD 1400. The CPU 1100 reads and executes the program data 1450 from the SSD 1400, but as another example, the CPU 1100 may obtain these programs from another device via an external network 1550.

[0249] <<5. Other Embodiments>> The processing according to the above-described embodiment may be implemented in various different forms other than the above embodiment.

[0250] For example, the control device that controls the base station 20 and the terminal device 40 in the above-described embodiment may be realized by a dedicated computer system or a general-purpose computer system.

[0251] For example, a communication program for executing the above-described operations is stored on a computer-readable recording medium such as an optical disk, a semiconductor memory, a magnetic tape, or a flexible disk and distributed. Then, for example, the program is installed on a computer and the above-described processing is executed to configure a control device. In this case, the control device may be a device external to the base station 20 and the terminal device 40 (for example, a personal computer). Alternatively, the control device may be a device internal to the base station 20 and the terminal device 40 (for example, the control units 24 and 45).

[0252] The communication program may also be stored in a disk device provided in a server device on a network such as the Internet, and may be downloaded to a computer. The above-described functions may also be realized by a combination of an operating system (OS) and application software. In this case, the components other than the OS may be stored on a medium and distributed, or may be stored in a server device and downloaded to a computer.

[0253] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically using a known method. In addition, the information including the processing procedures, specific names, various data, and parameters shown in the above documents and drawings can be changed as desired unless otherwise specified. For example, the various information shown in each drawing is not limited to the information shown in the drawings.

[0254] Furthermore, the components of each device shown in the figure are conceptual functional components and do not necessarily have to be physically configured as shown in the figure. In other words, the specific form of distribution and integration of each device is not limited to that shown in the figure, and all or part of them can be functionally or physically distributed and integrated in any unit depending on various loads, usage conditions, etc.

[0255] Furthermore, the above-described embodiments can be combined as appropriate within the scope of not causing any contradiction in the processing content.

[0256] Furthermore, the effects described in this specification are merely examples and are not limiting, and other effects may also be present.

[0257] Furthermore, for example, each embodiment can be implemented as any configuration that constitutes an apparatus or system, such as a processor as a system LSI (Large Scale Integration), a module using multiple processors, a unit using multiple modules, a set in which other functions are added to a unit, or the like (i.e., a configuration of a part of an apparatus).

[0258] In the embodiments, a system refers to a collection of multiple components (devices, modules (components), etc.), regardless of whether all the components are in the same housing. Therefore, multiple devices housed in separate housings and connected via a network, and a single device housed in a single housing with multiple modules, are both systems.

[0259] Furthermore, for example, the embodiment may have a cloud computing configuration in which a single function is shared and processed jointly by a plurality of devices via a network.

[0260] <<6. Conclusion>> Although the embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present disclosure. Furthermore, components of different embodiments and modifications may be combined as appropriate.

[0261] Furthermore, the effects of the embodiments described in this specification are merely examples and are not limiting, and other effects may also be obtained.

[0262] The present technology may also be configured as follows. (1) A communication device, one of a plurality of communication devices that communicate with a terminal device in a cooperative manner, comprising: a communication unit that communicates with the terminal device; and a control unit that transmits a synchronization signal to the terminal device that has made a request to transmit the synchronization signal for initial connection while at least some functions of the communication unit are stopped, wherein the terminal device transmits the transmission request in response to a setting signal for transmitting the transmission request. (2) The communication device according to (1), in which the control unit transmits the setting signal to the terminal device. (3) The communication device according to (1), in which the terminal device receives the setting signal from another communication device. (4) The communication device according to (3), in which a communication range of the communication unit partially overlaps with a communication range of the other communication device. (5) The communication device according to (3), in which the communication range of the communication unit is included in the communication range of the other communication device. (6) The communication device according to any one of (1) to (5), in which the control unit transmits system information for the initial connection to the terminal device in response to the transmission request. (7) The communication device according to any one of (1) to (6), wherein the setting signal includes setting information independent of identification information that identifies a communication range of the communication device. (8) The communication device according to any one of (1) to (7), wherein the setting signal does not include information related to a synchronization signal. (9) The communication device according to any one of (1) to (8), wherein the setting signal includes information related to a setting common to a plurality of the communication devices. (10) The communication device according to any one of (1) to (9), wherein the terminal device receives the setting signal in response to a signal for reception for receiving the setting signal. (11) The communication device according to (10), wherein the control unit transmits the signal for reception to the terminal device. (12) The communication device according to (11), wherein the communication unit stops transmitting signals other than the signal for reception and / or the setting signal while transmitting the signal for reception and / or the setting signal until the transmission request is received. (13) The communication device according to (10), wherein the terminal device receives the reception signal from another communication device.(14) The communication device according to (13), wherein the other communication device transmits the reception signal including the reception signal via RRC signaling. (15) The communication device according to any one of (10) to (14), wherein power consumption when transmitting the reception signal is lower than power consumption when transmitting the synchronization signal. (16) The communication device according to (15), wherein the reception signal differs from the synchronization signal in at least one of a transmission interval, a bandwidth, and information to be transmitted. (17) The communication device according to any one of (1) to (16), wherein power consumption when transmitting the setting signal is lower than power consumption when transmitting system information. (18) A terminal device comprising: a communication unit that communicates with a plurality of communication devices operating in coordination; and a control unit that receives a setting signal for transmitting a transmission request for a synchronization signal for initial connection, makes the transmission request in response to the setting signal to the communication device in which at least a portion of communication functions is stopped, and receives the synchronization signal from the communication device. (19) A communication method in one of a plurality of communication devices that communicate with a terminal device in a coordinated manner, comprising: communicating with the terminal device via a communication unit; and transmitting a synchronization signal to the terminal device that has made a transmission request of a synchronization signal for an initial connection in a state in which at least a portion of the functions of the communication unit are stopped, wherein the terminal device transmits the transmission request in response to a setting signal for transmitting the transmission request. (20) A communication method comprising: communicating with at least one of a plurality of communication devices that operate in a coordinated manner, receiving a setting signal for transmitting a transmission request of a synchronization signal for an initial connection, making the transmission request in response to the setting signal to the communication device in which at least a portion of the communication functions are stopped, and receiving the synchronization signal from the communication device.(21) A communication program causing a computer to function as one of a plurality of communication devices that communicate with a terminal device in cooperation with the computer, and further causing the computer to function as a communication unit that communicates with the terminal device, and a control unit that transmits a synchronization signal to the terminal device that has made a request to transmit the synchronization signal for initial connection in a state where at least a portion of the functions of the communication unit are stopped, the terminal device transmitting the transmission request in response to a setting signal for transmitting the transmission request. (22) A communication program causing a computer to function as a communication unit that communicates with at least one of a plurality of communication devices that operate in cooperation with the computer, and a control unit that receives a setting signal for transmitting a synchronization signal for initial connection, makes the transmission request in response to the setting signal to the communication device whose communication functions are at least partially stopped, and receives the synchronization signal from the communication device. (23) A communication system comprising: a plurality of communication devices operating in coordination; and a terminal device communicating with at least one of the plurality of communication devices, wherein the terminal device receives a setting signal for transmitting a request to transmit a synchronization signal for initial connection, and makes the transmission request to the communication device in which at least a portion of the communication function is stopped in response to the setting signal, and the communication device transmits the synchronization signal to the terminal device in response to the transmission request.

[0263] 20 Base station 21, 41 Signal processing unit 22, 42 Storage unit 23 Network communication unit 24, 44 Control unit 40 Terminal device 43 Input / output unit

Claims

1. A communication device, one of a plurality of communication devices that communicate with a terminal device in cooperation, comprising: a communication unit that communicates with the terminal device; and a control unit that transmits a synchronization signal to the terminal device that has made a request to transmit the synchronization signal for initial connection while at least some of the functions of the communication unit are stopped, wherein the terminal device transmits the transmission request in response to a setting signal for transmitting the transmission request.

2. The communication device according to claim 1, wherein the control unit transmits the setting signal to the terminal device.

3. The communication device according to claim 1, wherein the terminal device receives the setting signal from another communication device.

4. The communication device according to claim 3, wherein a portion of the communication range of said communication unit overlaps with a portion of the communication range of said other communication device.

5. The communication device according to claim 3, wherein the communication range of said communication unit is included in the communication range of said other communication device.

6. The communication device according to claim 1, wherein the control unit transmits system information for the initial connection to the terminal device in response to the transmission request.

7. The communication device according to claim 1, wherein the setting signal includes setting information that is not dependent on identification information that identifies the communication range of the communication device.

8. The communication device according to claim 1, wherein the setting signal does not include information regarding a synchronization signal.

9. The communication device according to claim 1, wherein the setting signal includes information regarding settings common to a plurality of the communication devices.

10. The communication device according to claim 1, wherein the terminal device receives the setting signal in response to a signal for receiving the setting signal.

11. The communication device according to claim 10, wherein the control unit transmits the reception signal to the terminal device.

12. A communication device as described in claim 11, wherein the communication unit stops transmitting signals other than the reception signal and / or the setting signal while transmitting the reception signal and / or the setting signal until the transmission request is received.

13. The communication device according to claim 10, wherein the terminal device receives the signal to be received from another communication device.

14. The communication device according to claim 13, wherein the other communication device transmits the signal to be received via RRC signaling.

15. The communication device according to claim 10, wherein the power consumption when transmitting the reception signal is less than the power consumption when transmitting the synchronization signal.

16. The communication device according to claim 15, wherein the receiving signal differs from the synchronization signal in at least one of the transmission interval, bandwidth, and transmitted information.

17. The communication device according to claim 1, wherein the power consumption when transmitting the setting signal is less than the power consumption when transmitting the system information.

18. A terminal device comprising: a communication unit that communicates with multiple communication devices that operate in coordination; and a control unit that receives a setting signal for transmitting a request to transmit a synchronization signal for initial connection, makes the transmission request in response to the setting signal to the communication device whose communication function is at least partially stopped, and receives the synchronization signal from the communication device.

19. A communication method in one of a plurality of communication devices that communicate with a terminal device in cooperation, comprising: communicating with the terminal device via a communication unit; and transmitting a synchronization signal to the terminal device that has made a request to transmit the synchronization signal for initial connection while at least some functions of the communication unit are stopped; wherein the terminal device transmits the transmission request in response to a setting signal for transmitting the transmission request.

20. A communication method including: communicating with at least one of a plurality of communication devices operating in coordination; receiving a setting signal for transmitting a request to transmit a synchronization signal for initial connection; making the transmission request in response to the setting signal to the communication device in which at least a portion of the communication function is stopped; and receiving the synchronization signal from the communication device.

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