Base station, communication device, and communication system

Abstract

In order to reduce load due to a beam search of a base station and a communication device, one aspect provides a base station characterized by comprising: a reception unit for receiving, from another base station, a signal including information about a reception beam that the other base station uses when receiving a signal from a first communication device; and a control unit that determines a candidate for a beam to be used for communication between the other base station and the second communication device according to information about a transmission beam used when transmitting a signal to the first communication device and the information about the reception beam.

Description

Base station, communication device, and communication system

[0001] The present invention relates to a base station, a communication device, and a communication system.

[0002] In recent years, there has been an increasing demand for uplink communication capacity in communication environments. Therefore, it has been proposed to deploy a large number of small cells within the cell range of an existing macrocell. Furthermore, in order to mitigate the increased costs and interference caused by deploying a large number of small cells, for example, small cells have been proposed that limit data signal communication with communication devices such as terminals to uplink communication only (see Non-Patent Document 1).

[0003] 3GPP TSG RAN #101 RP-232073

[0004] For example, when a base station and a communication device such as a terminal connect, the base station and the communication device each need to perform an exhaustive search of transmission beams and reception beams to set the beam to be used. However, for example, when performing an exhaustive search in base stations and communication devices that form small cells that are expected to be deployed in large numbers, the calculation cost can be high and the load for performing the initial connection can be heavy. Note that the above-mentioned issue is also a problem that can be considered for small cells other than small cells that limit the data signal communication function to only uplink communication.

[0005] The disclosed technology has been made in consideration of the above, and aims to reduce the load caused by beam search.

[0006] In one aspect, a base station is provided that is characterized by having: a receiving unit that receives a signal from another base station that includes information regarding a receiving beam that the other base station uses when receiving a signal from a first communication device; and a control unit that determines candidate beams to be used for communication between the other base station and a second communication device based on the information regarding the transmitting beam that is used when transmitting a signal to the first communication device and the information regarding the receiving beam.

[0007] The load caused by beam search can be reduced.

[0008] FIG. 1 is a diagram illustrating an example of a communication system according to a first embodiment. FIG. 2 is a diagram illustrating an example of a functional configuration diagram of a base station in the communication system according to the first embodiment. FIG. 3 is a diagram illustrating an example of a functional configuration diagram of a base station in the communication system according to the first embodiment. FIG. 4 is a diagram illustrating an example of a functional configuration diagram of a communication device in the communication system according to the first embodiment. FIG. 5 is a diagram illustrating an example of a procedure for initial connection between a base station and a communication device in the first embodiment. FIG. 6 is a diagram illustrating an example of a procedure for initial connection between a base station and a communication device in the first embodiment. FIG. 7 is a diagram illustrating an example of a procedure for initial connection between a base station and a communication device in the second embodiment. FIG. 8 is a diagram illustrating an example of a procedure for initial connection between a base station and a communication device in the third embodiment. FIG. 9 is a diagram illustrating an example of a procedure for initial connection between a base station and a communication device in the third embodiment. FIG. 10 is a diagram illustrating an example of a hardware configuration diagram of a base station in the communication system. FIG. 11 is a diagram illustrating an example of a hardware configuration diagram of a base station in the communication system. FIG. 12 is a diagram illustrating an example of a hardware configuration diagram of a communication device in the communication system.

[0009] The present embodiment will be described in detail below with reference to the drawings. The problems and embodiments in this specification are merely examples and do not limit the scope of the rights of the present application. In particular, even if the expressions used are different, the technology of the present application can be applied as long as they are technically equivalent, and do not limit the scope of the rights. Furthermore, each embodiment can be combined as appropriate within the scope of not causing any contradiction in the processing content.

[0010] Furthermore, the terms used and technical contents described in this specification may be the terms and technical contents described in specifications and contributions as standards related to communications, such as 3GPP (Third Generation Partnership Project, registered trademark).

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a communication device and a communication system disclosed in the present application will be described in detail below with reference to the accompanying drawings. Note that the disclosed technology is not limited to the following embodiments. First Embodiment

[0012] FIG. 1 shows an example of a communication system 1 according to a first embodiment. The communication system 1 includes a base station 100, a base station 200, a communication device 300A, and a communication device 300B. The base station 100 forms a cell C10, and the base station 200 forms a cell C20. When the communication device 300A and the communication device 300B are not distinguished from each other, they may be simply referred to as the communication device 300. The base station 200 is an example of another base station. The communication device 300A is an example of a first communication device, and the communication device 300B is an example of a second communication device. Although the communication system 1 shown in FIG. 1 includes two communication devices 300, this is not limiting and any number of communication devices greater than or equal to two may be used. This also applies to the following embodiments.

[0013] The base station 100 may be a radio base station such as a macro radio base station, and may be referred to as a macro cell, a base station forming the macro cell, a radio communication device, a communication device, a transmitting device, etc. The base station 200 may be a radio base station such as a small radio base station (including a micro radio base station, a femto radio base station, etc.) such as a pico radio base station, and may be referred to as a small cell, a base station forming the small cell, a radio communication device, a communication device, a receiving device, etc. The communication device 300 may be a radio terminal such as a mobile phone, a smartphone, a PDA (Personal Digital Assistant), a personal computer, a vehicle, an IoT (Internet of Things) device, or any other device or equipment (sensor device, etc.) having a radio communication function, and may be referred to as a radio communication device, a receiving device, a mobile station, etc.

[0014] The base station 100 is also connected to a network (not shown) such as a core network (higher-level device) via wired or wireless connection.

[0015] The base station 200 is a base station under the control of the base station 100 .

[0016] The base station 100 and the base station 200 may have a wireless communication function for performing wireless communication with the communication device 300 and a digital signal processing and control function, which may be separated into separate devices. In this case, the device having the wireless communication function may be called an RRH (Remote Radio Head), and the device having the digital signal processing and control function may be called a BBU (Base Band Unit). The RRHs are installed extending from the BBUs, and they may be connected by wire or wirelessly via optical fiber or the like. Instead of the RRHs and BBUs described above, the base station 100 and the base station 200 may be separated into, for example, a Central Unit (CU), a Distributed Unit (DU), and a Radio Unit (RU). The DU includes, for example, a MAC (Media Access Control) layer function. The DU may also have the functionality of, for example, an RLC (Radio Link Control) layer. The RU includes at least an RF wireless circuit. The DU and RU may also be integrated into one unit.

[0017] On the other hand, the communication device 300 communicates with the base station 100 and the base station 200 via wireless communication.

[0018] Next, the base station 100 will be described. Fig. 2 is an example of a functional configuration diagram of the base station 100 in the communication system 1 of the first embodiment. As shown in Fig. 2, the base station 100 includes a communication unit 110, a control unit 120, and a storage unit 130. These components are connected to each other so as to enable unidirectional or bidirectional input and output of signals and data. The communication unit 110 can be described as being divided into a transmission unit 111 and a reception unit 112.

[0019] The transmitter 111 transmits downlink signals, such as random access procedure signals, RRC layer signals, downlink data signals, and downlink control signals, to the communication device 300 .

[0020] The receiving unit 112 can receive uplink signals transmitted from the communication device 300, such as random access procedure signals, RRC layer signals, uplink data signals, and uplink control signals.

[0021] The communication unit 110 also connects to and communicates with network devices (for example, the base station 200, higher-level devices, and other communication devices) via wired or wireless connections.

[0022] The control unit 120 controls the base station 100. Specifically, the control unit 120 can control signal processing of signals received by the receiving unit 112, creation of transmission blocks (TBs), mapping of the transmission blocks to radio resources, and the like.

[0023] The storage unit 130 can store, for example, information relating to downlink data signals and beam search.

[0024] Next, the base station 200 will be described. FIG. 3 is an example of a functional configuration diagram of the base station 200 in the communication system 1 of the first embodiment. As shown in FIG. 3, the base station 200 includes a communication unit 210, a control unit 220, and a storage unit 230. These components are connected to enable unidirectional or bidirectional input and output of signals and data. The communication unit 210 can be described separately as a transmission unit 211 and a reception unit 212. The base station 200 does not necessarily have the function of transmitting a data signal to the communication device 300. The base station 200 is an example of another base station.

[0025] The transmitter 211 transmits downlink signals, such as random access procedure signals, RRC layer signals, and downlink control signals, to the communication device 300 .

[0026] The receiving unit 212 can receive uplink signals transmitted from the communication device 300, such as random access procedure signals, RRC layer signals, uplink data signals, and uplink control signals.

[0027] The communication unit 210 also connects to and communicates with network devices (for example, the base station 100, higher-level devices, and other communication devices) via wired or wireless connections.

[0028] The control unit 220 controls the base station 200. Specifically, the control unit 220 can control signal processing of signals received by the communication unit 210, and the like.

[0029] The storage unit 130 can store, for example, information relating to uplink data signals and beam search.

[0030] Next, the communication device 300 will be described. Fig. 4 is an example of a functional configuration diagram of the communication device 300 in the communication system 1 of the first embodiment. As shown in Fig. 4, the communication device 300 includes a communication unit 310, a control unit 320, and a storage unit 330. These components are connected to each other so as to enable input and output of signals and data in one direction or two directions. Note that the communication unit 310 can be described as being divided into a transmission unit 311 and a reception unit 312.

[0031] The transmitter 311 transmits, for example, data signals and control signals by wireless communication via an antenna. The antenna may be shared with the receiver 312. The transmitter 211 transmits, for example, upstream signals such as a random access procedure signal, an upstream data signal, and an upstream control signal.

[0032] The receiving unit 312 receives downlink signals, such as a random access procedure signal, a downlink data signal, a downlink control signal, etc., transmitted from the base station 100. The received signals may also include signals such as a reference signal (RS) used for channel estimation and demodulation.

[0033] The control unit 320 controls the communication device 300. Specifically, the control unit 320 can control signal processing of signals transmitted from the base station 100 and received by the receiving unit 312, creation of transmission blocks (TBs), mapping of the transmission blocks to radio resources, and the like.

[0034] The storage unit 330 can store, for example, uplink data signals. The storage unit 330 can also store configuration information (or setting information) related to wireless communication transmitted from the base station 100.

[0035] Next, a method for reducing the load due to beam search in the base station 100, the base station 200, and the communication device 300 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 and Fig. 6 are diagrams showing an example of a sequence for establishing an initial connection between the base station 100, the base station 200, and the communication device 300 in the first embodiment.

[0036] First, the base station 100 and the communication device 300 establish an initial connection for transmitting and receiving data signals between the base station 100 and the communication device 300 (step S500). At this time, the base station 100 and the communication device 300 perform a beam search. Furthermore, the communication device 300 determines a transmission beam for the base station 100 and a reception beam for the base station 100 according to the results of the beam search, and determines resources for the initial connection. Furthermore, the base station 100 determines a transmission beam for the communication device 300 and a reception beam for the communication device 300 according to the results of the beam search, and determines resources for the initial connection.

[0037] The transmitter 111 of the base station 100 transmits a signal including information requesting, for example, the device type of the communication device 300, the remaining battery level, etc. to the communication device 300 (step S501). Note that this signal is, for example, a signal of the RRC layer. Note that the information on the device type is information indicating what type of communication device the communication device 300 is, such as whether the communication device 300 is a mobile station, a communication device that is always connected to a stable power source, or a low-power terminal such as an IoT terminal. Also, the information on the device type is, for example, UE Capability.

[0038] In response to the signal request transmitted from the base station 100 in step S501, the transmitting unit 311 of the communication device 300 transmits a signal to the base station 100 including information indicating, for example, the device type of the communication device 300, the remaining battery level, etc. (step S502).

[0039] The control unit 120 of the base station 100 classifies the communication devices 300 based on, for example, information indicating the device type of the communication devices 300, remaining battery power, etc. (step S503). Examples of classification methods include classifying the communication devices into low-power consumption communication devices and other communication devices, or into communication devices with low remaining battery power and other communication devices. The number of classification types does not have to be two, and the communication devices 300 may be classified based on multiple factors. For the sake of explanation, it is assumed below that the communication device 300A is classified into a first group and the communication device 300B is classified into a second group.

[0040] Next, a method for establishing an initial connection for transmitting and receiving data signals between the base station 200 and the communication device 300A classified into the first group will be described with reference to FIG.

[0041] The transmitter 111 of the base station 100 transmits a signal including information on resource candidates to be used for the initial connection between the base station 200 and the communication device 300A to the base station 200 and the communication device 300A (steps S504 and S505).

[0042] The control unit 320 of the communication device 300A performs a beam search in accordance with the information on the resource candidates and determines a transmission beam for the base station 200 (step S506).

[0043] The control unit 220 of the base station 200 performs a beam search according to the information on the resource candidates, and determines a receiving beam for receiving an uplink signal from the communication device 300A and resources for initial connection (steps S507 and S508).

[0044] The transmitting unit 211 of the base station 200 transmits a signal including information on the resource determined in step S508 to the communication device 300A (step S509).

[0045] Through the above processing, the base station 200 and the communication device 300A can establish an initial connection between the base station 200 and the communication device 300A based on the determined resources and beams (step S510).

[0046] Furthermore, the transmitter 211 of the base station 200 transmits to the base station 100 a signal including beam information, such as the beam number of the reception beam, determined in step S508 (step S511). This processing may be performed after the reception beam is determined in step S508, and may be performed, for example, before the processing of step S509 or step S510. Furthermore, processing may be performed to transmit to the base station 100 a single signal including information on the beam numbers of the reception beams of other communication devices 300 in the first group (not shown).

[0047] Furthermore, the control unit 120 of the base station 100 uses the transmission beam information of the signal transmitted from the base station 100 to the communication device 300A, determined at the time of initial connection with the communication device 300A, and the reception beam information of the signal from the communication device 300A of the base station 200, to learn the correlation between the information of these two beams and generate a trained model (step S512). This trained model can, for example, estimate the reception beam information that the base station 200 receives from the communication device 300 from the transmission beam information that the base station 100 transmits to the communication device 300. Note that the reception beam information of the signal from the communication device 300A of the base station 200 is an example of information regarding the reception beam used when the base station 200 receives a signal from the communication device 300A. Note that this trained model may be configured to be updated as appropriate. This process may be performed using other methods, not just learning, as long as it is possible to estimate the reception beam information that the base station 200 receives from the communication device 300 from the transmission beam information that the base station 100 transmits to the communication device 300.

[0048] As a result, the base station 100 can use the trained model generated in step S512 to determine, for example, the receiving beam information that the base station 200 receives from the communication device 300 from the transmitting beam information that the base station 100 transmits to the communication device 300.

[0049] Next, a method for establishing an initial connection between a communication device 300 of the second group (e.g., communication device 300B) and the base station 200 will be described with reference to Fig. 6. Note that the following description will be given taking the initial connection between the communication device 300B and the base station 200 as an example. Note that portions of the process that are similar to the process for establishing an initial connection between the communication device 300A and the base station 200 described in Fig. 5 will be assigned the same step numbers, and descriptions thereof may be omitted.

[0050] The control unit 120 of the base station 100 uses the trained model trained in step S512 to estimate a receiving beam for the base station 200 to receive a signal from the communication device 300B based on the beam used for the signal transmitted by the base station 100 to the communication device 300B (the beam determined in step S500) (step S600). Note that the estimated receiving beam does not need to be uniquely determined, and multiple candidates may be provided.

[0051] The transmitter 111 of the base station 100 transmits information about the estimated reception beam to the base station 200. Note that the information about the reception beam may include, for example, not only the estimated reception beam but also information about multiple beams, such as beams adjacent to the reception beam (step S601).

[0052] The transmitting unit 111 of the base station 100 transmits to the base station 200 and the communication device 300B a signal including information about resource candidates to be used for the initial connection between the base station 200 and the communication device 300B (steps S602 and S603). Note that this processing may be performed before step S601. Also, the information about the resource candidates to be transmitted to the base station 200 may be included in the signal transmitted by the base station 100 in step S601 and transmitted to the base station 200.

[0053] The control unit 320 of the communication device 300B performs a beam search in accordance with the received information on the resource candidates, and determines a transmission beam for the base station 200 (step S604).

[0054] The control unit 220 of the base station 200 determines the receiving beam from the communication device 300B and resources for initial connection based on the information about the receiving beam received in step S601 (step S606). Note that if the information about the receiving beam includes multiple receiving beams (beam candidates), for example, a beam search is performed for those receiving beams (step S605) to determine the receiving beam from the communication device 300B (step S606).

[0055] The transmitting unit 211 of the base station 200 transmits a signal including information about the determined resource for initial connection to the communication device 300B (step S607).

[0056] Through the above series of processes, the base station 200 and the communication device 300B can establish an initial connection based on the determined resources and beams (step S608).

[0057] As a result, a beam to be used in communication between base station 200 and a communication device 300 of the second group (communication device 300B) can be selected according to the beam information selected in communication between base station 100 and base station 200 and a communication device 300 of the first group (communication device 300A).

[0058] The processes of steps S500 to S512 and steps S600 to S608 can be repeated. The order in which the base station 100 and the base station 200 establish initial connections with the communication devices 300 is not limited to the order of the communication devices 300 in the first group and the communication devices 300 in the second group. This also applies to the following embodiments.

[0059] Furthermore, the reception beam search (step S605) of the base station 200 during the initial connection between the base station 200 and the communication device 300B is unnecessary (or can be limited to reception beam candidates only). Therefore, compared to the reception beam search (step S506) of the base station 200 during the initial connection between the base station 200 and the communication device 300A, for example, the number of beam searches can be reduced, thereby reducing the power consumption of the base station 200. Therefore, the load on the base station 200 can be reduced.

[0060] In the above-described first embodiment, the base station 100 receives a signal including information about a reception beam with which the base station 200 receives a signal from the communication device 300A. The base station 100 then estimates information about a reception beam (or a candidate reception beam) with which the base station 200 receives a signal from the communication device 300B, using information about a reception beam with which the base station 200 receives a signal from the communication device 300A and information about a transmission beam with which the base station 100 transmits a signal to the communication device 300A. This reduces the load of the beam search on the base station 200. Embodiment 2

[0061] In the first embodiment, an example has been described in which the base station 100 estimates a receiving beam of the base station 200 for communication between the base station 200 and a communication device 300 of a second group by utilizing beam search for communication between the base station 200 and a communication device 300 of a first group. In the second embodiment, a method for reducing the load of beam search performed by the communication device 300 of the second group at the time of initial connection with the base station 200 will be described. Note that in the second embodiment, the communication system 1, the base station 100, the base station 200, and the communication device 300 are the same as in the first embodiment, and therefore description thereof will be omitted. Also, in the second embodiment, description of the same parts of the initial connection procedure performed by the base station 100, the base station 200, and the communication device 300 as in the first embodiment will be omitted.

[0062] A sequence for reducing the load of beam search performed by communication devices 300 of the second group at the time of initial connection with base station 200 in embodiment 2 will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of a control flow in embodiment 2. Note that processes similar to those described in Figs. 5 and 6 are given the same step numbers, and descriptions thereof may be omitted.

[0063] First, an initial connection is established between the base station 100 and the communication devices 300 of the first group in the same manner as in the first embodiment (steps S500 to S510).

[0064] Next, the control unit 120 of the base station 100 generates a trained model as in embodiment 1, and uses the trained model generated in step S512 to enable, for example, the base station 200 to determine the receiving beam information that it receives from the communication device 300 from the transmitting beam information that the base station 100 transmits to the communication device 300 (steps S511 and S512).

[0065] Next, a method for establishing an initial connection between a communication device 300 in the second group (e.g., communication device 300B) and the base station 200 will be described with reference to Fig. 7. Note that the following description will be given taking the initial connection between the communication device 300B and the base station 200 as an example.

[0066] The control unit 120 of the base station 100 uses the trained model trained in step S512 to estimate a receiving beam for the base station 200 to receive a signal from the communication device 300B based on the beam used for the signal transmitted by the base station 100 to the communication device 300B (the beam determined in step S500) (step S600). Note that the estimated receiving beam does not need to be uniquely determined, and multiple candidates may be provided.

[0067] Next, the control unit 120 of the base station 100 estimates the directional difference between the base station 100 and the base station 200 from the communication device 300B using the direction of the receiving beam through which the base station 200 receives a signal from the communication device 300B estimated in step S600, the direction of the transmitting beam that the base station 100 transmits to the communication device 300B, the location information of the base station 100, and the location information of the base station 200 (step S700).

[0068] The transmitting unit 111 of the base station 100 transmits a signal including information about the directional difference estimated in step S700 to the communication device 300B (step S701).

[0069] The transmitter 111 of the base station 100 transmits a signal including information on candidates for resources to be used for the initial connection between the base station 200 and the communication device 300B to the base station 200 and the communication device 300B (steps S602 and S603). Note that the information to be transmitted to the communication device 300B may be transmitted as part of the signal transmitted by the base station 100 to the communication device 300B in step S701.

[0070] The control unit 320 of the communication device 300B determines a transmission beam for transmitting a signal to the base station 200 based on the transmission beam for the signal to be transmitted to the base station 100 determined by the communication device 300B, for example, in accordance with the received information on the directional difference, the received information on the candidate resources, and the attitude information of the communication device 300B (step S702). Note that instead of determining a single transmission beam, for example, multiple candidates may be determined (step S702), and a beam search may be performed among those candidates (step S703) to determine the transmission beam for the base station 200.

[0071] The control unit 220 of the base station 200 performs a beam search and determines a receiving beam for the communication device 300B (step S704).

[0072] The control unit 220 of the base station 200 determines the resource to be used for the initial connection in accordance with the received information on the resource candidates (step S705).

[0073] The transmitting unit 211 of the base station 200 transmits a signal including information about the determined resource for initial connection to the communication device 300B (step S706).

[0074] Through the above series of processes, the base station 200 and the communication device 300B can establish an initial connection based on the determined resources and beams (step S608).

[0075] Therefore, as a result of the above, it is possible to select a beam to be used in communication between base station 200 and a communication device 300 of the second group (communication device 300B) depending on the information of the beam selected in communication between base station 100 and base station 200 and a communication device 300 of the first group (communication device 300A).

[0076] Furthermore, since the transmission beam search (step S703) of the communication device 300B is unnecessary (or can be limited to only transmission beam candidates) during the initial connection between the base station 200 and the communication device 300B, the number of beam searches can be reduced compared to, for example, the transmission beam search (step S506) of the base station 200 during the initial connection between the base station 200 and the communication device 300A, thereby reducing the power consumption of the base station 200. As a result, the load on the communication device 300B can be reduced.

[0077] In the above-described second embodiment, the base station 100 receives a signal including information about a reception beam with which the base station 200 receives a signal from the communication device 300A. The base station 100 then estimates information about a transmission beam (or a candidate transmission beam) of a signal that the communication device 300B transmits to the base station 200, using information about a reception beam with which the base station 200 receives a signal from the communication device 300A and information about a transmission beam of a signal that the base station 100 transmits to the communication device 300A. This reduces the load of the communication device 300B due to beam search.

[0078] Note that embodiment 2 and embodiment 1 can also be combined and employed. In this case, base station 100 transmits a signal including information about the reception beam estimated by base station 100 in step S600 to base station 200, and transmits a signal including information about the estimated directional difference to communication device 300B in step S700. Thereafter, as with base station 200 in embodiment 1, base station 200 determines a reception beam based on the received information about the reception beam, and communication device 300B determines a transmission beam for base station 200. This makes it possible to reduce the beam search load at base station 200 and communication device 300B. Embodiment 3

[0079] In the first embodiment, an example has been described in which the base station 100 estimates a receiving beam of the base station 200 for communication between the base station 200 and a communication device 300 of a second group by utilizing beam search for communication between the base station 200 and the communication device 300 of a first group. Furthermore, in the second embodiment, an example has been described in which the load of beam search performed by the communication device 300 of the second group at the time of initial connection with the base station 200 is reduced. In the third embodiment, an example of a method, different from that of the second embodiment, for reducing the load of beam search performed by the communication device 300 of the second group at the time of initial connection with the base station 200 will be described. In the third embodiment, the communication system 1, the base station 100, the base station 200, and the communication device 300 are the same as those in the first and second embodiments, and therefore description thereof will be omitted. In the third embodiment, description of the same parts of the procedure for initial connection with a communication partner performed by the base station 100, the base station 200, and the communication device 300 as those in the first and second embodiments will be omitted.

[0080] A sequence for reducing the load of beam search performed by the communication device 300 of the second group at the time of initial connection with the base station 200 in the third embodiment will be described with reference to Figures 8 and 9. Figures 8 and 9 are diagrams showing an example of a processing sequence in the third embodiment. Note that the same processes as those described in Figures 5 and 6 are given the same step numbers, and descriptions thereof may be omitted.

[0081] First, an initial connection is established between the base station 100, the base station 200 and the communication device 300 of the first group in the same manner as in the first embodiment (steps S500 to S510).

[0082] Next, the transmitter 211 of the base station 200 transmits a signal including beam information, such as the beam number of the receiving beam, determined in step S507 to the base station 100 (step S511). This processing may be performed after the receiving beam is determined in step S507, and may be performed, for example, before the processing of step S509 or step S510. Furthermore, processing may be performed to transmit a single signal to the base station 100 together with beam information of the receiving beams of other communication devices 300 in the first group (not shown).

[0083] Furthermore, the control unit 320 of the communication device 300 in the first group (for example, the communication device 300A) determines the difference in direction between the transmission beam for the base station 100 and the transmission beam for the base station 200 (step S800).

[0084] The transmitter 311 of the communication device 300 in the first group transmits a signal including information on the determined directional difference and attitude information of the communication device 300 itself to the base station 100 (step S801). Note that the processing of this step S801 and the above step S800 may be performed between step S506 and step S511.

[0085] Next, the control unit 120 of the base station 100 uses the transmission beam information when transmitting a signal to the communication devices 300 of the first group, the reception beam information when the base station 200 receives a signal from the communication devices 300 of the first group, and the information on the directional difference received from the corresponding communication device 300 in step S801 and the attitude information of the communication device 300 to learn the correlation between these pieces of information and generate a trained model (step S802). This trained model can, for example, estimate the directional difference between the transmission beam transmitted by the communication device 300 to the base station 100 and the transmission beam transmitted by the communication device 300 to the base station 200 from the transmission beam information transmitted by the communication device 300 to the base station 100. Note that the reception beam information when the base station 200 receives a signal from the communication devices 300 of the first group, and the information on the directional difference received from the corresponding communication device 300 in step S801 and the attitude information of the communication device 300 may be collectively expressed as information on the reception beam used by the base station 200 when receiving a signal from the communication devices 300 of the first group. The trained model may be configured to be updated as needed. This process may be performed using any method other than learning, as long as it is possible to estimate the directional difference between the transmission beam transmitted from the communication device 300 to the base station 100 and the transmission beam transmitted from the communication device 300 to the base station 200 from the transmission beam information transmitted from the base station 100 to the communication device 300.

[0086] Next, a method for establishing an initial connection between a communication device 300 in the second group (e.g., communication device 300B) and the base station 200 will be described with reference to Fig. 9. Note that the following description will be given taking the initial connection between the communication device 300B and the base station 200 as an example.

[0087] The control unit 120 of the base station 100 transmits a signal including information requesting attitude information (tilt) of the communication device 300B to the communication device 300B (step S900).

[0088] The transmitter 311 of the communication device 300B transmits a signal including the attitude information of the communication device 300B to the base station 100 (step S901).

[0089] Based on the received attitude information of the communication device 300B and the transmission beam information for the communication device 300B, the control unit 120 of the base station 100 uses the trained model generated in step S802 to estimate directional difference information between the transmission beam transmitted by the communication device 300B to the base station 100 and the transmission beam transmitted by the communication device 300B to the base station 200 (step S902). Note that the directional difference information between the transmission beam transmitted by the communication device 300B to the base station 200 is an example of information on candidate beams used for communication between the communication device 300B and the base station 200.

[0090] The transmitting unit 111 of the base station 100 transmits a signal including information relating to the estimated directional difference information to the communication device 300B (step S903).

[0091] The transmitter 111 of the base station 100 transmits a signal including information about resource candidates to be used for the initial connection between the base station 200 and the communication device 300B to the base station 200 and the communication device 300B (steps S904 and S905). Note that the information to be transmitted to the communication device 300B may be transmitted as part of the signal transmitted by the base station 100 to the communication device 300B in step S903.

[0092] The control unit 320 of the communication device 300B determines a transmission beam for a signal to be transmitted to the base station 200 according to the received information on the directional difference (step S906). Note that instead of determining a single transmission beam, for example, multiple candidates may be determined (step S906), and a beam search may be performed among those candidates (step S907) to determine a transmission beam for the base station 200.

[0093] The control unit 220 of the base station 200 performs a beam search and determines a reception beam for the communication device 300B (step S908).

[0094] The control unit 220 of the base station 200 determines the resource to be used for the initial connection in accordance with the received information on the resource candidates (step S909).

[0095] The transmitting unit 211 of the base station 200 transmits a signal including information about the determined resource for initial connection to the communication device 300B (step S910).

[0096] Through the above processing, the base station 200 and the communication device 300B can establish an initial connection based on the determined resources and beams (step S608).

[0097] Therefore, a beam to be used in communication between base station 200 and a communication device 300 of the second group (communication device 300B) can be selected according to the beam information selected in communication between base station 100 and base station 200 and a communication device 300 of the first group (communication device 300A).

[0098] Furthermore, since the transmission beam search (step S907) of the communication device 300B is unnecessary (or can be limited to only transmission beam candidates) during the initial connection between the base station 200 and the communication device 300B, the number of beam searches can be reduced compared to, for example, the transmission beam search (step S506) of the base station 200 during the initial connection between the base station 200 and the communication device 300A, thereby reducing the power consumption of the base station 200. As a result, the load on the communication device 300B can be reduced.

[0099] In the above-described third embodiment, the base station 100 receives a signal including information about the reception beam used by the base station 200 when receiving a signal from the communication device 300A. The base station 100 then estimates information about the transmission beam (or a candidate transmission beam) of a signal that the communication device 300B will transmit to the base station 200, using the information about the reception beam used by the base station 200 when receiving a signal from the communication device 300A and the information about the transmission beam of a signal that the base station 100 will transmit to the communication device 300A. This reduces the load of the communication device 300B due to beam search.

[0100] It should be noted that the third embodiment and the first embodiment may be combined. The trained model generated by the base station 100 may be, for example, two separate models for the first embodiment and the third embodiment, or one model capable of outputting each of the first and third embodiments may be generated. Hardware configuration of each device in each embodiment

[0101] The hardware configuration of each device in the communication system 1 of each embodiment will be described with reference to FIGS.

[0102] Fig. 10 is a diagram showing an example of the hardware configuration of base station 100. As shown in Fig. 10, base station 100 has, as hardware components, for example, an RF (Radio Frequency) circuit 420 equipped with an antenna 410, a CPU (Central Processing Unit) 430, a DSP (Digital Signal Processor) 440, a memory 450, and a network IF (Interface) 460. CPU 430 is connected via a bus so as to enable input and output of various signals and data signals. The memory 450 includes at least one of a RAM (Random Access Memory) such as an SDRAM (Synchronous Dynamic Random Access Memory), a ROM (Read Only Memory), and a flash memory, and stores programs, control information, and data signals.

[0103] The correspondence between the functional configuration of the base station 100 shown in Fig. 2 and the hardware configuration of the base station 100 shown in Fig. 10 will be described. The transmitter 111 and receiver 112 (or communication unit 110) are realized by, for example, an RF circuit 420, or an antenna 410 and an RF circuit 420. The control unit 120 is realized by, for example, a CPU 430, a DSP 440, a memory 450, a digital electronic circuit (not shown), etc. Examples of digital electronic circuits include an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), and an LSI (Large Scale Integration). The storage unit 130 is realized by, for example, the memory 450. The communication unit 110 is realized by the network IF 460, for example.

[0104] It should be noted that base station 100 can generate a plurality of data signals to be transmitted in a plurality of subbands, and the filters for generating these signals may be configured independently for each subband.

[0105] Fig. 11 is a diagram showing an example of the hardware configuration of base station 200. As shown in Fig. 11, base station 200 has, as hardware components, for example, an RF (Radio Frequency) circuit 520 equipped with an antenna 510, a CPU (Central Processing Unit) 530, a DSP (Digital Signal Processor) 540, a memory 550, and a network IF (Interface) 560. CPU 530 is connected via a bus so as to enable input and output of various signals and data signals. The memory 550 includes at least one of a RAM (Random Access Memory) such as an SDRAM (Synchronous Dynamic Random Access Memory), a ROM (Read Only Memory), and a flash memory, and stores programs, control information, and data signals.

[0106] The correspondence between the functional configuration of the base station 200 shown in Fig. 3 and the hardware configuration of the base station 200 shown in Fig. 11 will be described. The transmitter 211 and receiver 212 (or communication unit 210) are realized by, for example, an RF circuit 520, or an antenna 510 and an RF circuit 520. The control unit 220 is realized by, for example, a CPU 530, a DSP 540, a memory 550, a digital electronic circuit (not shown), etc. Examples of the digital electronic circuit include an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), and an LSI (Large Scale Integration). The storage unit 230 is realized by, for example, a memory 350. The communication unit 210 is realized by the network IF 560, for example.

[0107] In addition, base station 100 and base station 200 can generate multiple data signals to be transmitted in multiple subbands, and the filters that generate these signals can be configured independently for each subband.

[0108] 12 is a diagram showing an example of the hardware configuration of communication device 300. As shown in FIG. 12, communication device 300 has, as hardware components, an RF circuit 620 including an antenna 610, a CPU 630, and a memory 640. Communication device 300 may further have a display device such as an LCD (Liquid Crystal Display) connected to CPU 630. Memory 640 includes at least one of a RAM such as an SDRAM, a ROM, and a flash memory, and stores programs, control information, and data signals.

[0109] The correspondence between the functional configuration of the communication device 300 shown in Fig. 4 and the hardware configuration of the communication device 300 shown in Fig. 12 will be described. The transmitter 311 and receiver 312 (or communication unit 310) are realized by, for example, an RF circuit 620, or an antenna 610 and an RF circuit 620. The control unit 320 is realized by, for example, a CPU 630, a memory 640, a digital electronic circuit (not shown), etc. Examples of digital electronic circuits include an ASIC, an FPGA, and an LSI. The storage unit 330 is realized by, for example, the memory 640. Symbol Explanation

[0110] 1 Communication system 100 200 Base station 110 Communication unit 111 Transmission unit 112 Reception unit 120 Control unit 130 Memory unit 210 Communication unit 211 Transmission unit 212 Reception unit 220 Control unit 230 Memory unit C10 C20 Cell 300A 300B Communication device 310 Communication unit 311 Transmission unit 312 Reception unit 320 Control unit 330 Memory unit 410 Antenna 420 RF circuit 430 CPU 440 DSP 450 Memory 460 Network IF 510 Antenna 520 RF circuit 530 CPU 540 DSP 550 Memory 560 Network IF 610 Antenna 620 RF circuit 630 CPU 640 Memory

Claims

1. A base station characterized by having: a receiving unit that receives a signal from another base station including information about a receiving beam used by the other base station when receiving a signal from a first communication device; and a control unit that estimates information about candidate beams to be used for communication between the other base station and a second communication device based on information about a transmitting beam used when transmitting a signal to the first communication device and information about the receiving beam.

2. The base station according to claim 1, characterized in that the receiving unit receives a signal including information about the receiving beam from the other base station under the control of the base station, and the control unit estimates information about the candidate beam to be used for communication between the other base station under the control of the base station and the second communication device.

3. The base station according to claim 2, characterized in that the receiving unit receives a signal including information about the receiving beam from the other base station, and the control unit estimates information about the candidate beam to be used for communication between the other base station, which only receives data signals from the first communication device and the second communication device, and the second communication device.

4. The base station described in claim 1, characterized in that the control unit estimates information regarding the candidate beams to be used for communication between the other base station and the second communication device by learning the relationship between information regarding the transmission beam used when transmitting a signal to the first communication device and information regarding the reception beam.

5. The base station according to claim 4, characterized in that the control unit estimates information regarding the candidate beams used by the other base station in communication between the other base station and the second communication device, and has a transmission unit that transmits a signal including information regarding the estimated candidate beams to the other base station.

6. The base station according to claim 4, characterized in that the control unit estimates information regarding the candidate beams used by the second communication device in communication between the other base station and the second communication device, and has a transmission unit that transmits a signal including information regarding the estimated candidate beams to the second communication device.

7. The base station according to claim 1, wherein the control unit estimates information about one beam candidate.

8. The base station according to claim 1, characterized in that the information regarding the candidate beams used for communication between the other base station and the second communication device includes information regarding the difference in direction between the beams used for communication between the base station and the second communication device and the beams used for communication between the other base station and the second communication device.

9. A base station comprising: a transmitting unit that transmits to another base station a signal containing information regarding a receiving beam to be used by the other base station when receiving a signal from a first communication device; a receiving unit that receives from the other base station a signal containing information regarding a candidate receiving beam to be used for communication with a second communication device; and a receiving beam that is determined for communication with the second communication device according to the information regarding the candidate beam.

10. The base station according to claim 9, wherein the base station is a base station under the control of the other base station.

11. The base station according to claim 10, wherein the base station only receives data signals in communication with the first communication device and the second communication device.

12. A communication device comprising: a receiving unit that receives a signal from another base station including information regarding candidates for transmission beams to be used for communication with the base station; and a communication device that determines a transmission beam to be used for communication with the base station according to the information regarding the candidate beams.

13. A communication system having a base station, another base station, a first communication device, and a second communication device, wherein the base station receives a signal from the other base station including information about a receiving beam used when receiving a signal from the first communication device, and estimates information about candidate beams to be used for communication between the other base station and the second communication device based on the information about the transmitting beam used when the first communication device transmits a signal and the information about the receiving beam.

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