Wireless communication system, wireless communication method, and terminal device

Abstract

This wireless communication system comprises a plurality of terminal devices and a base station device that communicates wirelessly with the plurality of terminal devices. The base station device performs a beam search process by transmitting beams in a number of beam directions among a plurality of beam directions in which transmission is possible, said number being smaller than the plurality of beam directions in which transmission is possible. One of the plurality of terminal devices is a representative terminal of a group that has been set in advance or dynamically. The representative terminal comprises a reception unit that receives beams, an allocation unit that, in response to one of the beams transmitted from the base station device having been received and on the basis of a beam index and location information for the base station device, which are obtained through communication with the base station device, and location information for the other terminals belonging to the group which was set in advance or dynamically, determines a beam index to be used for communication with the base station device and other terminal devices belonging to the group, and a transmission unit that notifies the base station device and the other terminal devices of information regarding the determined beam index.　

Description

[Technical Field]

[0001] The present invention relates to a wireless communication system, a wireless communication method, and a terminal device. [Background technology]

[0002] In recent years, the use of millimeter waves has been widely studied to increase the speed and capacity of wireless communications. In particular, technologies such as massive MIMO (Multiple Input and Multiple Output) have been studied to increase the number of base station antennas and the number of beams (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] W. Hong, et.al., “Multibeam Antenna Technologies for5G Wireless Communications”, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL.65, NO.12, DECEMBER 2017. [Non-patent document 2] J. Zhang, et.al., “Cooperative Multi-Subarray Beam Training in Millimeter Wave Communication Systems”, Proc. of IEEE GLOBECOM 2017. Summary of the Invention [Problem to be solved by the invention]

[0004] As the number of terminal devices increases, the time and amount of calculation required for beam search also increases, so it is necessary to reduce the number of beam searches. Non-Patent Document 2 proposes a method of bundling multiple beams, searching them, and then performing a detailed beam search in order to reduce the overhead associated with beam searches. However, even with the method described in Non-Patent Document 2, there is a problem in that the number of beam searches increases depending on the number of terminal devices.

[0005] In view of the above circumstances, an object of the present invention is to provide a technique that can reduce the time and power consumption involved in beam search. [Means for solving the problem]

[0006] One aspect of the present invention is a wireless communication system comprising a plurality of terminal devices and a base station device that performs wireless communication between the plurality of terminal devices, wherein the base station device performs a beam search process by transmitting beams in a number of beam directions that are fewer than the plurality of beam directions that can be transmitted, out of a plurality of beam directions that can be transmitted, and one of the plurality of terminal devices is a representative terminal in a group that has been set in advance or dynamically, and the representative terminal comprises: a receiving unit that receives any of the beams transmitted from the base station device; an allocation unit that, in response to receiving any of the beams transmitted from the base station device, determines a beam index to be used for communication between the base station device and other terminal devices belonging to the group based on the position information and beam index of the base station device obtained through communication with the base station device and the position information of other terminal devices belonging to the group that has been set in advance or dynamically; and a transmitting unit that notifies the base station device and the other terminal devices of the determined beam index information.

[0007] One aspect of the present invention is a wireless communication method in a wireless communication system comprising a plurality of terminal devices and a base station device that performs wireless communication between the plurality of terminal devices, wherein the base station device performs a beam search process by transmitting beams in a number of beam directions that are fewer than the plurality of beam directions that can be transmitted, out of a plurality of beam directions that can be transmitted, and one of the plurality of terminal devices is a representative terminal in a group that has been set in advance or dynamically, and the representative terminal receives any of the beams transmitted from the base station device, and in response to receiving any of the beams transmitted from the base station device, determines a beam index to be used for communication between the base station device and other terminal devices belonging to the group based on the position information and beam index of the base station device obtained by communication with the base station device and the position information of other terminal devices belonging to the group that has been set in advance or dynamically, and notifies the base station device and the other terminal devices of the determined beam index information.

[0008] One aspect of the present invention is a terminal device comprising: a receiving unit that receives any of the beams transmitted in a number of beam directions that is fewer than the number of beam directions that a base station device can transmit, out of the number of beam directions that the base station device can transmit; an allocation unit that, in response to receiving any of the beams transmitted from the base station device, determines a beam index to be used for communication between the base station device and other terminal devices belonging to a group that has been set in advance or dynamically, based on the position information and beam index of the base station device obtained through communication with the base station device and the position information of other terminal devices belonging to the group; and a transmitting unit that notifies the base station device and the other terminal devices of the determined beam index information. [Effects of the Invention]

[0009] The present invention makes it possible to reduce the time and power consumption involved in beam search. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a diagram illustrating an example of the configuration of a wireless communication system 100 according to the present invention. [Figure 2] FIG. 1 is a diagram for explaining an overview of the present invention. [Figure 3] 1 is a diagram illustrating an example of the configuration of a base station device 10 according to an embodiment. [Figure 4] FIG. 2 is a diagram illustrating an example of the configuration of a terminal device 20 according to an embodiment. [Figure 5] FIG. 10 is a diagram for explaining a first method for determining a beam index of another terminal device 20. [Figure 6] FIG. 10 is a diagram for explaining a first method for determining a beam index of another terminal device 20. [Figure 7] 3 is a sequence diagram showing a processing flow of the wireless communication system 100 according to the embodiment. [Figure 8] FIG. 10 is a diagram illustrating a process for reorganizing groups. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a diagram showing an example of the configuration of a wireless communication system 100 according to the present invention. The wireless communication system 100 includes a base station device 10 and a plurality of terminal devices 20. Note that, according to the present invention, it is sufficient that there are a plurality of terminal devices 20.

[0012] The base station device 10 is a base station device in a RAN (Radio Access Network). The base station device 10 performs a beam search process by transmitting beams in a number of beam directions that are fewer than the number of beam directions that the base station device 10 can transmit. While FIG. 1 illustrates a configuration in which the base station device 10 can transmit beams in nine directions, the directions in which the base station device 10 can transmit beams are not particularly limited. If the base station device 10 is configured to transmit beams in nine directions, the base station device 10 performs a beam search process by thinning out some of the nine directions and transmitting beams in the remaining directions, rather than transmitting beams in all nine directions. For example, the base station device 10 transmits beams B1, B5, and B9, indicated by solid lines, by switching over time, and does not transmit beams B2, B3, B4, B6, B7, and B8, indicated by dashed lines. The base station device 10 may thin out the beams used in the beam search at equal intervals, or may thin out designated beams.

[0013] A terminal device 20 forms a group with one or more other terminal devices 20. The terminal devices 20 belonging to each group form a wireless PAN (Personal Area Network) link between the terminal devices 20 belonging to the same group, forming a wireless PAN network. A wireless PAN is a network formed between terminals located in close proximity, and is a network that uses less power than a RAN. FIG. 1 shows an example in which there are three groups G1, G2, and G3 in a wireless communication system 100, and three terminal devices 20 exist in each of the groups G1, G2, and G3.

[0014] The terminal devices 20 belonging to each of the groups G1, G2, and G3 will receive one of the beams B1, B5, and B9 transmitted from the base station device 10. The terminal device 20 that receives one of the beams transmitted from the base station device 10 sets itself as the representative terminal of the group to which it belongs (hereinafter referred to as "its group") and communicates with the base station device 10 on behalf of its group. Furthermore, the terminal device 20 that has become the representative terminal determines a beam index to be used for communication between the base station device 10 and other terminal devices 20 that belong to its group.

[0015] Next, an overview of the present invention will be explained using Fig. 2. Note that Fig. 2 shows an example focusing on one group in Fig. 1. The base station device 10 thins out the beams to be searched from among a large number of beams, for example, at equal intervals, and transmits a different preamble signal for each beam. The preamble signal is a known signal including the index of the beam to be used. The terminal device 20 that has received the preamble signal responds to the base station device 10 with a reception success notification indicating that it has successfully received the preamble signal. The terminal device 20 that has received the preamble signal sets itself as the representative terminal. In Fig. 2, it is assumed that the terminal device 20-1 is the representative terminal, and the terminal devices 20-2, 20-2 are the other terminal devices.

[0016] If there are multiple representative terminals in a group, the terminal device 20 that has received the beam with the highest reception sensitivity is designated as the representative terminal, and the other terminal devices 20 renounce their representation rights and stop future beam searches. Beam searches from the base station device 10 are performed periodically, but it is not necessary to perform searches using the same beam index every time; switching may be performed. Also, when a change condition is met, such as when the reception power of the beam used by the representative terminal falls below a certain value, the representative terminal may transfer the representation right to another terminal device 20 in its own group that has stronger reception power. For example, when a change condition is met, the representative terminal may acquire reception power information from the other terminal devices 20 in its own group and transfer the representation right to the terminal device 20 with the highest reception power among the acquired reception power information.

[0017] The terminal device 20-1 communicates with the base station device 10 and selects, for example, the beam received at maximum power. The base station device 10 notifies the terminal device 20-1, which is the representative terminal, of the location information of the base station device 10, and the terminal device 20-1 maintains the location relationship between the base station device 10 and the terminal device 20-1. Furthermore, the base station device 10 notifies the terminal device 20-1 of the index and beam spacing (e.g., angle) of the relevant beam. The other terminal devices 20-2 and 20-3 notify the terminal device 20-1 of their location information using a PAN or the like.

[0018] The terminal device 20-1 (representative terminal) determines the beam indexes of the other terminal devices 20-2 and 20-3 based on the beam index information, beam interval, direction of arrival, and position information of the other terminal devices 20-2 and 20-3. The terminal device 20-1 (representative terminal) notifies the base station device 10 and the other terminal devices 20-2 and 20-3 of the determined beam index information of the other terminal devices 20-2 and 20-3. This makes it possible to reduce the number of terminals performing beam search.

[0019] 3 is a diagram showing an example of the configuration of a base station device 10 according to an embodiment. The base station device 10 includes an antenna 11, a transmitter 12, a receiver 13, and a controller 14.

[0020] The antenna 11 receives radio waves transmitted from the terminal device 20 (for example, a representative terminal), converts the received radio waves into electrical signals, and outputs them to the receiving unit 13. The antenna 11 converts the electrical signals output from the transmitting unit 12 into radio waves and transmits them to the terminal device 20 (for example, a representative terminal).

[0021] The transmitting unit 12 is composed of a preamble generating unit 121 and a beam control unit 122. The preamble generating unit 121 generates preamble signals equal to the number of beams for which beam search is to be performed in response to an instruction to perform beam search processing from the control unit 14. Information on the number of beams for which beam search is to be performed may be stored in advance in the preamble generating unit 121, or may be notified from the control unit 14.

[0022] The beam control unit 122 superimposes preamble signals, the number of which is equal to the number of beams generated by the preamble generation unit 121, on each transmission beam and transmits them in the direction in which beam search is to be performed from the antenna 11. At this time, the beam control unit 122 transmits from the antenna 11 in a number of beam directions that is fewer than the number of beam directions that the base station device 10 can transmit from among the multiple beam directions that the base station device 10 can transmit.

[0023] The receiving unit 13 is composed of a receiving processing unit 131. The receiving processing unit 131 demodulates the electrical signal output from the antenna 11. For example, the receiving unit 13 demodulates the electrical signal to obtain a reception success response and information on the beam index of the terminal device 20. The receiving unit 13 outputs the obtained information to the control unit 14.

[0024] The control unit 14 controls the overall functions of the base station device 10. The control unit 14 instructs the transmission unit 12 to execute the beam search process at the timing when the beam search process is to be executed.

[0025] 4 is a diagram showing an example of the configuration of the terminal device 20 according to the embodiment. The terminal device 20 includes a RAN communication unit 21, a PAN communication unit 22, and a control unit .

[0026] The RAN communication unit 21 is a radio interface for the RAN and is composed of a RAN antenna 211, a RAN receiver 212, and a RAN transmitter 213.

[0027] The RAN antenna 211 receives radio waves transmitted from the base station device 10, converts the received radio waves into electrical signals, and outputs them to the RAN receiver 212. The RAN antenna 211 converts electrical signals output from the RAN transmitter 213 into radio waves and transmits them to the base station device 10.

[0028] The RAN receiver 212 demodulates the electrical signal output from the RAN antenna 211. For example, the RAN receiver 212 acquires a preamble signal by demodulating the electrical signal. The RAN receiver 212 outputs the acquired preamble signal to the control unit 23. When the RAN receiver 212 is a representative terminal, the RAN receiver 212 acquires location information, beam index information, and beam spacing information of the base station device 10 by demodulating the electrical signal. The RAN receiver 212 outputs the acquired location information, beam index information, and beam spacing information of the base station device 10 to the control unit 23.

[0029] The RAN transmitter 213 transmits transmission data to the base station device 10 via the RAN antenna 211 in accordance with instructions from the control unit 23. The transmission data transmitted by the RAN transmitter 213 is, for example, a reception success notification, information on the beam index of another terminal device 20, etc.

[0030] The PAN communication unit 22 is a wireless interface for the PAN and is made up of a PAN antenna 221, a PAN receiver 222, and a PAN transmitter 223.

[0031] The PAN antenna 221 receives radio waves transmitted from other terminal devices 20 (terminal devices 20 constituting the PAN), converts the received radio waves into electrical signals, and outputs them to the PAN receiver 222. The PAN antenna 221 converts the electrical signals output from the PAN transmitter 223 into radio waves and transmits them to the other terminal devices 20.

[0032] The PAN receiver 222 demodulates the electrical signal output from the PAN antenna 221. For example, if the PAN receiver 222 is not the representative terminal, it demodulates the electrical signal to obtain beam index information to be used for communication with the base station device 10. For example, if the PAN receiver 222 is the representative terminal, it demodulates the electrical signal to obtain location information of the other terminal devices 20. The PAN receiver 222 outputs the obtained beam index information and location information of the other terminal devices 20 to the control unit 23.

[0033] The PAN transmitter 223 transmits transmission data to other terminal devices 20 via the PAN antenna 221 in accordance with instructions from the control unit 23. The transmission data transmitted by the PAN transmitter 223 includes, for example, a reference signal, location information, a reception success notification, beam index information, etc. The reference signal is a preamble signal that includes an ID for identifying the device, the reception power of the base station beam, the presence or absence of representation rights, etc.

[0034] If the frequency bands are close to each other, the RAN antenna 211 and the PAN antenna 221 may be shared.

[0035] The control unit 23 controls the entire terminal device 20. The control unit 23 is configured using one or more processors such as a CPU (Central Processing Unit) and one or more memories. The control unit 23 realizes the functions of a location information acquisition unit 231, a notification signal generation unit 232, an allocation unit 233, and a management unit 234 by the one or more processors executing programs.

[0036] The location information acquisition unit 231 acquires location information of the terminal device 20. For example, the location information acquisition unit 231 acquires location information by a global positioning system (GPS). Note that the location information acquisition unit 231 may acquire location information by other methods as long as the location information of the terminal device 20 can be acquired.

[0037] The notification signal generation unit 232 generates a notification signal for notifying information to the base station device 10 or other terminal devices 20. For example, when the own device is a representative terminal, the notification signal generation unit 232 generates a notification signal indicating that a preamble signal has been received for the base station device 10. For example, when the own device is a representative terminal, the notification signal generation unit 232 generates a notification signal for notifying the base station device 10 and other terminal devices 20 of beam index information. For example, when the own device is not a representative terminal, the notification signal generation unit 232 generates a notification signal for notifying the representative terminal of the location information acquired by the location information acquisition unit 231.

[0038] The allocation unit 233 is a functional unit that functions when the base station device 10 is the representative terminal. The allocation unit 233 determines a beam index to be used for communication between the base station device 10 and the other terminal devices 20 belonging to the group, based on the position information, beam index, and beam spacing information of the base station device 10 obtained from the base station device 10, and the position information of the other terminal devices 20 belonging to the group.

[0039] The management unit 234 manages various types of information. For example, the management unit 234 manages information (such as MAC (Media Access Control) addresses) of the terminal devices 20 belonging to its own group. For example, if its own device is not the representative terminal, the management unit 234 holds information on the beam index notified from the representative terminal.

[0040] Next, a method for determining the beam index of the other terminal devices 20 by the representative terminal will be described. There are two methods for determining the beam index of the other terminal devices 20. Figs. 5 and 6 are diagrams for explaining the first method for determining the beam index of the other terminal devices 20. As shown in Fig. 5, the location information of the base station device 10, the location information of the representative terminal, and the location information of the other terminal devices 20 are expressed in a two-dimensional coordinate system. Here, the location information of the base station device 10 is expressed as (x B ,y B ), the location information of the representative device (x U1 ,y U1 ) and the location information of the other terminal device 20 (x U2 ,y U2 ) may be a three-dimensional coordinate system that takes into account the height of the terminal device 20. The allocation unit 233 calculates the angle d 12 Calculate.

[0041] As shown in FIG. 6, the interval between beams radiated by the base station device 10 is ΔD. The beam index used by the representative terminal is k. Here, the beam with beam index k+1 is directed to a location ΔD degrees away from the beam used by the representative terminal. The allocation unit 233 calculates the distance (nΔD-d 12 ) is the smallest n min and the beam index used by the other terminal device 20 is k+n min It is decided that:

[0042] Next, a second method for determining the beam index of the other terminal devices 20 will be described. The second method is a method that takes into account the fact that the other terminal devices 20 are located near the terminal device 20 that has become the representative terminal. The allocation unit 233 randomly allocates to the other terminal devices 20 the beam index of a beam adjacent to the beam index used by the representative terminal. For example, when the representative terminal uses a beam with beam index k, the allocation unit 233 randomly selects from among beam indexes of k±2 and allocates the selected beam index to the other terminal devices 20.

[0043] FIG. 7 is a sequence diagram showing the flow of processing in the wireless communication system 100 according to the embodiment. When it is time to execute the beam search process, the control unit 14 of the base station device 10 performs the beam search process by instructing the transmission unit 12 to execute the beam search process (step S101). The preamble generation unit 121 of the transmission unit 12 generates preamble signals for the number of beams for which the beam search is to be performed, in response to the instruction to execute the beam search process from the control unit 14. The preamble generation unit 121 outputs the generated preamble signals for the number of beams to the beam control unit 122.

[0044] The beam control unit 122 superimposes preamble signals, the number of which is equal to the number of beams generated by the preamble generation unit 121, onto each transmission beam, and transmits the superimposed preamble signals from the antenna 11 in a number of beam directions that is fewer than the plurality of beam directions that the base station device 10 can transmit in. In this way, during beam search processing, the base station device 10 thins out the beams used for beam search and switches the beams over time for transmission. It is assumed that the beam transmitted from the base station device 10 is received by the terminal device 20-1 but not received by the terminal device 20-2.

[0045] The RAN antenna 211 of the terminal device 20-1 receives a beam transmitted from the base station device 10. The RAN antenna 211 converts the received beam into an electrical signal and outputs it to the RAN receiver 212. The RAN receiver 212 acquires a preamble signal by demodulating the electrical signal output from the RAN antenna 211. The RAN receiver 212 outputs the acquired preamble signal to the control unit 23.

[0046] If the RAN receiver 212 can correctly demodulate the signal, the RAN transmitter 213 of the RAN communication unit 21 transmits a reception success notification to the base station device 10 (step S101). The reception success notification includes information for identifying the received beam. The management unit 234 of the control unit 23 sets its own device as the representative terminal (step S103). The representative terminal transmits a reference signal to the surrounding terminal devices 20 via the PAN transmitter 223 and the PAN antenna 221 to notify that it is the representative terminal. Here, if multiple terminal devices 20 set their own device as the representative terminal, each representative terminal compares the other terminal reception power included in the reference signal received from the other terminal devices 20 with its own reception power, and if its reception power is the maximum, it maintains its representation right, while the other terminal devices 20 abandon their representation right. The other terminal reception power represents the reception power of the other terminal devices 20.

[0047] When the control unit 14 of the base station device 10 receives a reception success notification transmitted from the terminal device 20-1, it controls the transmission unit 12 to transmit base station information to the terminal device 20-1 using the beam indicated by the beam identifying information included in the reception success notification. The base station information is information related to the base station device 10, and includes, for example, beam index information, beam spacing, and position information of the base station device 10. The beam spacing is the spacing between beams that the base station device 10 can transmit. In other words, the beam spacing is not the beam spacing after thinning.

[0048] The RAN antenna 211 of the terminal device 20-1 receives a beam transmitted from the base station device 10. The RAN antenna 211 converts the received beam into an electrical signal and outputs it to the RAN receiver 212. The RAN receiver 212 acquires base station information by demodulating the electrical signal output from the RAN antenna 211. The RAN receiver 212 outputs the acquired base station information to the control unit 23.

[0049] The management unit 234 of the control unit 23 holds the obtained base station information. The management unit 234 controls the PAN communication unit 22 to transmit a reference signal. The PAN communication unit 22 transmits the reference signal in accordance with the control of the management unit 234 (step S105). The reference signal transmitted from the terminal device 20-1 is received by a terminal device 20 (for example, terminal device 20-2) located close to the terminal device 20-1. In response to receiving the reference signal, the terminal device 20-2 transmits a reception success notification to the terminal device 20-1 indicating that the reference signal has been successfully received (step S106).

[0050] The PAN communication unit 22 of the terminal device 20-1 receives the reference signal transmitted from the terminal device 20-2. In response to receiving the reference signal, the management unit 234 of the terminal device 20-1 adds the terminal device 20-1 to its own group (step S107). Note that if the terminal device 20-1 does not add the terminal device 20 to its own group, the processes from step S105 to step S107 may be omitted.

[0051] A terminal device 20 (here, terminal device 20-2) belonging to the own group transmits its own location information to terminal device 20-1 (step S108). When terminal device 20 (here, terminal device 20-2) is newly added to the group, it may transmit its own location information to terminal device 20-1, which is the representative terminal, in response to a request from terminal device 20-1, which is the representative terminal, or may notify terminal device 20-1, which is the representative terminal, at periodic timing.

[0052] It is desirable that the terminal device 20-1, which is the representative terminal, acquires location information of all terminal devices 20 belonging to its own group before assigning beam indices. The allocation unit 233 of the terminal device 20-1 assigns beam indices to all terminal devices 20 belonging to its own group using either the first method or the second method described above, based on the base station information and the location information of all terminal devices 20 belonging to its own group (step S109). After assigning beam indices to all terminal devices 20 belonging to its own group, the allocation unit 233 controls the RAN communication unit 21 and the PAN communication unit 22 to notify the base station device 10 and other terminal devices 20 of information on the assigned beam indices (step S110).

[0053] Specifically, the allocation unit 233 associates information about the assigned beam index with identification information of the terminal device 20. The allocation unit 233 controls the RAN communication unit 21 to transmit association information between the beam index information and the identification information of the terminal device 20 to the base station device 10. The RAN communication unit 21 transmits the association information to the base station device 10 in accordance with an instruction from the allocation unit 233. Furthermore, the allocation unit 233 controls the PAN communication unit 22 to transmit information about the assigned beam index to each terminal device 20. The PAN communication unit 22 transmits the beam index information to the terminal device 20 in accordance with an instruction from the allocation unit 233. This allows the terminal device 20-2 to acquire information about the assigned beam index.

[0054] According to the wireless communication system 100 configured as described above, the base station device 10 performs beam search processing by transmitting beams in a number of beam directions that are fewer than the number of beam directions that can be transmitted, out of the number of beam directions that can be transmitted, and one of the number of terminal devices 20 is a representative terminal in the group, and the representative terminal device 20 is equipped with a RAN receiver 212 that receives any of the beams transmitted from the base station device 10, an allocation unit 233 that, in response to receiving any of the beams transmitted from the base station device 10, determines a beam index to be used for communication between the base station device 10 and other terminal devices 20 belonging to the group based on the position information and beam index of the base station device 10 obtained through communication with the base station device 10 and the position information of the other terminal devices 20 belonging to the group, and a transmission unit (e.g., a RAN transmitter 213 and a PAN transmitter 223) that notifies the base station device 10 and the terminal device 20 of information on the determined beam index.

[0055] As described above, in the wireless communication system 100, during beam search processing, the base station device 10 does not transmit beams in all possible beam directions, but transmits beams in some directions. The terminal device 20 that has become the representative terminal communicates with the base station device 10 and determines the beam indexes of the other terminal devices 20 that belong to its own group. As a result, even if the number of terminal devices 20 increases, the representative terminal determines the beam indexes of the other terminal devices 20 on behalf of the other terminal devices 20, so the number of beam searches by the base station device 10 does not increase. This makes it possible to reduce the time and power consumption associated with beam searches.

[0056] The terminal device 20 that has become the representative terminal estimates the relative positional relationship between the base station device 10, the terminal device 20 that has become the representative terminal, and the other terminal devices 20 based on the position information of the other terminal devices 20 obtained within the group, and estimates the beam pointed in the direction of the other terminal devices 20 from the estimated relative positional relationship. Then, the terminal device 20 that has become the representative terminal determines the beam index of the other terminal devices 20 by assigning the index of the beam that is estimated to be pointed in the direction of the other terminal devices 20 to the other terminal devices 20. This makes it possible to accurately determine the beam index of the other terminal devices 20.

[0057] The terminal device 20 that has become the representative terminal determines the beam indexes of the other terminal devices 20 that belong to its own group by randomly assigning the index of a beam adjacent to the beam used by the terminal device 20 that has become the representative terminal to the other terminal devices 20 that belong to its own group. Belonging to its own group (a group that makes up a PAN) means that the other terminal devices 20 are located in a position close in distance to the terminal device 20 that has become the representative terminal. Therefore, it is sufficient to assign the index of a beam adjacent to the beam used by the terminal device 20 that has become the representative terminal. This makes it possible to determine the beam index of the other terminal devices 20 more simply than the first method.

[0058] (Variation) In the above-described embodiment, the groups may be reorganized based on the beam index. FIG. 8 is a diagram illustrating the process for reorganizing the groups. As shown in FIG. 8, it is assumed that there are two groups G1 and G2, and the above-described beam search process has been completed within each of the groups G1 and G2. The representative terminal in each of the groups G1 and G2 notifies the base station device 10 of information on the beam index used by each terminal device 20 belonging to the group. As a result, the base station device 10 is aware of information on the beam index in each of the groups G1 and G2. Therefore, the base station device 10 performs reorganization based on information on the beam index obtained from each of the multiple groups so that terminal devices with similar beam indices belong to the same group.

[0059] For example, the control unit 14 of the base station device 10 compares the difference between the beam index of the representative terminal of a group G (e.g., group G2) to which a certain terminal device 20 currently belongs and the beam index of the certain terminal device 20 (e.g., terminal device 20-3) with the difference between the beam index of the representative terminal of an adjacent group G (e.g., group G2) and the beam index of the certain terminal device 20 (e.g., terminal device 20-3). If the comparison result shows that the difference is smaller in another group G (e.g., group G1) than in the group G (e.g., group G2) to which the certain terminal device 20 (e.g., terminal device 20-3) currently belongs, the control unit 14 determines that group G1 is a better group to which the certain terminal device 20 (e.g., terminal device 20-3) belongs. The base station device 10 notifies each of groups G1 and G2 of this fact, and the representative terminals of each of groups G1 and G2 reorganize the groups in accordance with the instruction from the base station device 10. In this way, the base station device 10 performs reorganization in such a way that the terminal devices 20 other than the representative terminal are included in the group with the smallest difference value.

[0060] 8 shows an example in which the terminal device 20 that belonged to group G2 is reorganized to belong to group G1. With this configuration, the terminal devices 20 that have beam indices close to the representative terminal are considered to be located at angles close to each other as seen from the base station device 10, and by grouping terminals that are close to the representative terminal into the same user group, it is possible to reduce the power involved in communication between terminals that share a beam index, for example.

[0061] The base station device 10 and terminal device 20 described above may be implemented by a computer. In this case, a program for implementing the functions may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be loaded into a computer system and executed to implement the functions. Note that the term "computer system" here includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system.

[0062] Furthermore, the term "computer-readable recording medium" may include a medium that dynamically stores a program for a short period of time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, or a medium that stores a program for a fixed period of time, such as a volatile memory within a computer system that serves as a server or client in such a case. The program may also be one that realizes part of the above-mentioned functions, or may be one that can realize the above-mentioned functions in combination with a program already stored in the computer system, or may be one that is realized using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0063] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention. [Industrial Applicability]

[0064] The present invention is applicable to wireless access networks. [Explanation of symbols]

[0065] 10...base station device, 11...antenna, 12...transmitter, 13...receiver, 14...controller, 20, 20-1 to 20-3...terminal device, 21...RAN communication unit, 22...PAN communication unit, 23...controller, 100...wireless communication system, 121...preamble generator, 122...beam controller, 131...reception processor, 211...RAN antenna, 212...RAN receiver, 213...RAN transmitter, 221...PAN antenna, 222...PAN receiver, 223...PAN transmitter, 231...location information acquirer, 232...notification signal generator, 233...allocation unit, 234...management unit

Claims

1. A wireless communication system including a plurality of terminal devices and a base station device that performs wireless communication between the plurality of terminal devices, The base station device performing a beam search process by transmitting beams in a number of beam directions that is less than the plurality of transmittable beam directions among the plurality of transmittable beam directions; Any one of the plurality of terminal devices A representative terminal in a group that is set in advance or dynamically, The representative terminal is a receiving unit that receives any one of the beams transmitted from the base station device; an allocation unit that, in response to receiving any beam transmitted from the base station device, determines a beam index to be used for communication between the base station device and other terminal devices belonging to the group based on location information and beam index of the base station device obtained through communication with the base station device and location information of other terminal devices belonging to a group that is set in advance or dynamically; a transmitting unit that notifies the base station device and the other terminal device of information about the determined beam index; A wireless communication system comprising:

2. The allocation unit determining a beam index to be used for communication between the other terminal device and the base station device by randomly assigning an index of an adjacent beam of the beam used by the representative terminal to the other terminal device; 10. The wireless communication system of claim 1.

3. The allocation unit based on the position information of the other terminal devices obtained within the group, estimate the relative positional relationship between the base station device, the representative terminal, and the other terminal devices, and determine the beam index to be used for communication between the other terminal devices and the base station device by assigning the index of the beam directed in the direction of the other terminal devices to the other terminal devices; 10. The wireless communication system of claim 1.

4. the plurality of terminal devices form a personal area network capable of communicating with low power, The other terminal devices notify the representative terminal of their location information within the configured personal area network. A wireless communication system according to any one of claims 1 to 3.

5. Any one of the plurality of terminal devices further includes a management unit that sets the own device as the representative terminal upon receiving any one of the beams transmitted from the base station device, When there are a plurality of representative terminals in the group, the terminal device having the highest reception sensitivity among the plurality of terminal devices set as the representative terminal is finally set as the representative terminal, and the other terminal devices set as the representative terminal are not set as the representative terminal. A wireless communication system according to any one of claims 1 to 3.

6. The base station device Based on beam index information obtained from each of the plurality of groups, reorganization is performed so that terminal devices having similar beam indices belong to the same group. A wireless communication system according to any one of claims 1 to 3.

7. A wireless communication method in a wireless communication system including a plurality of terminal devices and a base station device that performs wireless communication between the plurality of terminal devices, the base station device performs a beam search process by transmitting beams in a number of beam directions that is less than the plurality of beam directions that can be transmitted, among a plurality of beam directions that can be transmitted; any one of the plurality of terminal devices is a representative terminal in a group that is set in advance or dynamically, The representative terminal receiving any beam transmitted from the base station device; In response to receiving any of the beams transmitted from the base station device, determine a beam index to be used for communication between the base station device and other terminal devices belonging to the group based on the position information and beam index of the base station device obtained through communication with the base station device and the position information of other terminal devices belonging to a group that has been set in advance or dynamically; A wireless communication method for notifying the base station device and the other terminal device of information about the determined beam index.

8. a receiving unit that receives any beam transmitted in a number of beam directions that is less than the number of beam directions that the base station device can transmit, among a plurality of beam directions that the base station device can transmit; an allocation unit that, in response to receiving any beam transmitted from the base station device, determines a beam index to be used for communication between the base station device and other terminal devices belonging to the group based on location information and beam index of the base station device obtained through communication with the base station device and location information of other terminal devices belonging to a group that is set in advance or dynamically; a transmitting unit that notifies the base station device and the other terminal device of information about the determined beam index; A terminal device comprising:

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