Wireless communication system

Abstract

A first mobile terminal 102 detects identification information of a second base station 104 from a radio signal from the second base station 104 when the radio signal is received. A first base station 101 performs interference coordination with the second base station 104 via the Internet 100 in response to the detection of the identification information. The first base station 101 performs control so as to widen the angle between a first beam for the first mobile terminal 102 to communicate with the first base station 101 and a second beam directed in a direction in which the first mobile terminal 102 receives the radio signal from the second base station 104 within a range in which communication between the first mobile terminal 102 and the first base station 101 is possible.

Description

Wireless communication system

[0001] The present invention relates to wireless communication technology, and particularly to a wireless communication system including a plurality of base stations.

[0002] In wireless communication, interference suppression is required. To this end, a plurality of base stations or terminals observe interference waves from an interfering base station, and notify the interfering base station of the intensity of such interference via the Internet. The interfering base station calculates an interference area from the position and intensity of the interference, and controls radio wave output to optimize the interference area. Accordingly, the interfering base station can suppress interference to other stations while continuing its own communication (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Publication No. 2016-116007

[0004] As the frequency bands used for wireless communication become higher, the number of multi-antennas and the number of beams both increase enormously. At the same time, the communication area of each beam also becomes extremely narrow, making it difficult to statistically obtain the interference area for each beam.

[0005] The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for suppressing interference in a plurality of base stations using directional antennas.

[0006] In order to solve the above problem, a wireless communication system according to one aspect of the present embodiment includes: a first base station having a directional antenna; a first mobile terminal that communicates with the first base station and has a directional antenna; a second base station that communicates with the first mobile terminal via a network and performs wireless communication with a second mobile terminal using a signal including identification information; and a processing device that executes interference arbitration. When the first mobile terminal receives a wireless signal from the second base station, the first mobile terminal detects the identification information of the second base station from the wireless signal. In response to detection of the identification information, the processing device performs interference arbitration with the second base station via the network. The processing device performs control to widen an angle between a first beam for the first mobile terminal to communicate with the first base station and a second beam directed in a direction in which the first mobile terminal receives the wireless signal from the second base station, within a range where communication between the first mobile terminal and the first base station is possible.

[0007] Another embodiment of this embodiment is also a wireless communication system. This wireless communication system comprises a first base station having a directional antenna, a mobile terminal communicating with the first base station, and a second base station having a directional antenna but not communicating with the mobile terminal. When the mobile terminal receives a wireless signal from the second base station, it transmits an interference arbitration request to the first base station to request interference arbitration with the second base station. When the first base station receives the interference arbitration request from the mobile terminal, it transmits a beam evasion request to the second base station to request beam evasion. When the second base station receives the beam evasion request from the first base station, it performs arbitration to avoid a degradation of communication quality due to beam interference.

[0008] Furthermore, any combination of the above components, as well as conversions of the expressions of this embodiment between methods, apparatus, systems, recording media, computer programs, etc., are also valid as embodiments of this embodiment.

[0009] According to this embodiment, interference can be suppressed in multiple base stations using directional antennas.

[0010] Figure 1 shows the configuration of the wireless communication system according to Example 1. Figure 1 shows the configuration of the first mobile terminal. Figure 1 shows the configuration of the first base station. Figure 3 shows an overview of the beam that can be formed by the antenna array. Figure 1 is a sequence diagram showing the arbitration procedure by the wireless communication system. Figure 1 shows the radio wave propagation status in the wireless communication system. Figure 1 shows an overview of the arbitration process by the wireless communication system. Figure 1 shows an overview of the arbitration process at the second base station. Figure 1 shows an overview of the arbitration process at the first base station. Figure 1 is a flowchart showing the processing procedure by the first mobile terminal. Figure 1 shows a flowchart showing the processing procedure by the first base station. Figure 1 shows a flowchart showing the processing procedure by the second base station. Figure 2 shows the configuration of the first mobile terminal according to Example 2. Figure 3 shows a sequence diagram showing the arbitration procedure by the wireless communication system according to Example 2.

[0011] (Example 1) This example will be described below in the order of (1) basic configuration and (2) arbitration process for interference. (1) Basic Configuration Diagram 1 shows the configuration of the wireless communication system 1000. The wireless communication system 1000 includes the Internet 100, a first base station 101, a first mobile terminal 102, a second mobile terminal 103, and a second base station 104. The first base station 101 and the second base station 104 are collectively referred to as "base stations," and the first mobile terminal 102 and the second mobile terminal 103 are collectively referred to as "mobile terminals." The number of base stations included in the wireless communication system 1000 is not limited to "2," nor is the number of mobile terminals limited to "2."

[0012] The Internet 100 is a network for transferring data to remote devices. The first base station 101 has an array antenna and uses the array antenna for wireless communication. The first mobile terminal 102 communicates wirelessly with the first base station 101. The second mobile terminal 103 does not communicate wirelessly with the first base station 101, but communicates wirelessly with the second base station 104. The second base station 104 has an array antenna and uses the array antenna for wireless communication. For wireless communication between the first base station 101 and the first mobile terminal 102, the identification information of the first base station 101 and the identification information of the first mobile terminal 102 are used, and for wireless communication between the second mobile terminal 103 and the second base station 104, the identification information of the second mobile terminal 103 and the identification information of the second base station 104 are used. In addition, the second base station 104 and the first mobile terminal 102 can communicate via the Internet 100.

[0013] Figure 2 shows the configuration of the first mobile terminal 102. The first mobile terminal 102 includes an antenna 501, a receiving unit 502, a multiplexing and decompression unit 503, a demodulation unit 504, a decoding unit 505, an information processing unit 506, an encoding unit 507, a modulation unit 508, a multiplexing unit 509, a transmission unit 510, and a network interface 511. The second mobile terminal 103 has the same configuration.

[0014] Antenna 501 receives radio waves and converts the energy of the radio waves into electric current. It also converts the electric current into radio wave energy and transmits radio waves. Receiving unit 502 amplifies the electrical signal from antenna 501, extracts a signal in a predetermined frequency band, and converts it into digital received waveform data. Multiplexing and reconstruction unit 503 demodulates the OFDM (Orthogonal Frequency Division Multiplexing) modulation of the received waveform data from receiving unit 502 using FFT (Fast Fourier Transform) and converts it into received subcarrier data. Demodulation unit 504 digitally demodulates the received subcarrier data from multiplexing and reconstruction unit 503 and converts it into digital received stream data. Decoding unit 505 applies error correction to the received stream data from demodulation unit 504 and reconstructs the communication data.

[0015] The information processing unit 506 processes information based on the communication data from the decoding unit 505, creates transmission data, and outputs it to the encoding unit 507. The encoding unit 507 adds error correction codes to the transmission data from the information processing unit 506 and converts it into transmission stream data. The modulation unit 508 modulates the transmission stream data from the encoding unit 507 and converts it into transmission subcarrier data. The multiplexing unit 509 performs OFDM modulation on the transmission subcarrier data from the modulation unit 508 using IFFT (Inverse Fast Fourier Transform) and converts it into transmission waveform data. The transmission unit 510 frequency shifts the transmission waveform data from the multiplexing unit 509 to a predetermined frequency band and amplifies the resulting electrical signal. The network interface 511 communicates with the Internet 100.

[0016] Figure 3 shows the configuration of the first base station 101. The first base station 101 includes an antenna array 601, a receiving beamforming unit 602, a receiving unit 603, a multiplexing and decompression unit 604, a demodulation unit 605, a decoding unit 606, an information processing unit 607, an encoding unit 608, a modulation unit 609, a multiplexing unit 610, a transmitting unit 611, a transmitting beamforming unit 612, and a network interface 615. The second base station 104 has the same configuration.

[0017] The antenna array 601 is an array of antennas arranged at predetermined intervals, and corresponds to an array antenna. Each antenna converts radio waves and electric currents in the same way as antenna 501. Note that the antenna array 601 may be any other type of directional antenna. For example, the antenna array 601 may be a parabolic antenna, and the transmitting beam forming unit 612 and the receiving beam forming unit 602 may be replaced with an antenna rotating unit. The antenna rotating unit rotates the antenna in a specified direction. In other words, the antenna array 601 can be any directional antenna.

[0018] The receiving beamforming unit 602 phase-shifts and adds the signals from each antenna so that only radio waves at a predetermined angle are detected. The receiving unit 603 to the transmitting unit 611 and the network interface 615 are the same as the receiving unit 502 to the transmitting unit 510 and the network interface 511 in Figure 2, so their explanation is omitted here. The transmitting beamforming unit 612 phase-shifts the signals to be transmitted to each antenna so that radio waves are emitted at a predetermined angle.

[0019] Figure 4 shows an overview of the beams that can be formed by the antenna array 601. This shows multiple beams that can be formed by the antenna array 601 while changing the horizontal direction (horizontal angle) and vertical direction (elevation angle) of the beam. Although "16" beams are shown here, the number of beams that can be formed by the antenna array 601 is not limited to "16". In addition, each beam is assigned an identifier (hereinafter referred to as "beam identifier") to identify the beam. Here, the horizontal angle and elevation angle in Figure 4 are shown with reference to the first mobile terminal 102.

[0020] The transmitting beamforming unit 612 of the first base station 101 transmits multiple beams in a switching manner before commencing communication with the first mobile terminal 102, and has the first mobile terminal 102 measure the received intensity for each beam. The first mobile terminal 102 transmits the measurement results of the received intensity for each beam to the first base station 101. The first base station 101 receives the measurement results of the received intensity for each beam from the first mobile terminal 102 and decides to use the beam with the highest received intensity for communication with the first mobile terminal 102. The first base station 101 also retains the measurement results of the received intensity for each beam.

[0021] When the first base station 101 communicates with the first mobile terminal 102, it includes a beam ID in the radio waves (signals) it transmits. The same process is carried out between the second base station 104 and the second mobile terminal 103.

[0022] (2) Arbitration process for interference Below, we will explain the case in which interference occurs when radio waves transmitted from the second base station 104 are received by the first mobile terminal 102, using Figure 5 as well. Figure 5 is a sequence diagram showing the arbitration procedure by the wireless communication system 1000. The radio waves (wireless signals) transmitted by the second base station 104 include the beam ID of the second base station 104. The beam ID is identification information for identifying the direction of the beam of the second base station 104, and is also identification information that allows the second base station 104 to be identified. In other words, the beam ID can be said to be identification information that allows the station itself to identify the beam angle.

[0023] The first mobile terminal 102 receives a radio signal from the second base station 104 and detects interference if the strength of the radio signal is above a certain value (S901). Specifically, the multiplexing and restoration unit 503 performs an inner product calculation on a plurality of received subcarrier data sequences obtained at a predetermined timing with each beam ID (a predetermined data sequence) assigned to the second base station 104, and interference is detected if the resulting value is above a certain value. The network interface 511 has acquired the predetermined data sequences in advance via the internet 100. Here, the first mobile terminal 102 extracts the beam ID from the radio signal. This is equivalent to extracting the identification information of the second base station 104.

[0024] The first mobile terminal 102 transmits an interference arbitration request to the first base station 101 to request interference arbitration with the second base station 104 (S902). The interference arbitration request includes identification information of the first mobile terminal 102, location information of the first mobile terminal 102, beam ID of the second base station 104, reception direction of the radio signal (interference wave) from the second base station 104, beam ID of the first base station 101, and reception direction of the radio signal (desired wave) from the first base station 101. The location information of the first mobile terminal 102 is obtained by a GNSS (Global Navigation Satellite System) positioning unit (not shown) in the first mobile terminal 102. Pre-set information in the first mobile terminal 102 is used for the reception direction of the interference wave and the reception direction of the desired wave. Furthermore, the direction of reception of the desired wave may be calculated from the location information of the first base station 101 and the location information of the first mobile terminal 102, and the direction of reception of the interference wave may be calculated from the location information of the second base station 104 and the location information of the first mobile terminal 102.

[0025] The first base station 101 receives an interference arbitration request from the first mobile terminal 102. The network interface 615 of the first base station 101 transmits a beam evacuation request to the second base station 104 via the internet 100 to request beam evacuation (S903). The beam evacuation request includes the location information of the first mobile terminal 102, the beam ID of the second base station 104, the direction of reception of the radio signal (interference wave) from the second base station 104, and the direction of reception of the radio signal (desired wave) from the first base station 101.

[0026] The network interface 615 of the second base station 104 receives a beam avoidance request from the first base station 101 via the internet 100. The second base station 104 performs arbitration, i.e., beam avoidance, to avoid a degradation of communication quality due to beam interference (S904). Figure 6 shows the propagation status of radio waves in the wireless communication system 1000. As in Figure 1, Figure 6 shows the first base station 101, the first mobile terminal 102, the second mobile terminal 103, and the second base station 104. As mentioned above, the first base station 101 and the first mobile terminal 102 are communicating, and the second base station 104 and the second mobile terminal 103 are communicating. Examples of propagation paths received by the first mobile terminal 102 are shown as beams "0", "3", and "4". When the first mobile terminal 102 is receiving a radio wave of beam "0" from the first base station 101, and then receives a radio wave of beam "0" from the second base station 104, interference occurs between the radio wave from the first base station 101 (desired wave) and the radio wave from the second base station 104 (interfering wave). Figure 7 shows the beams of radio waves that can be received by the first mobile terminal 102. This is shown in the same way as in Figure 4. As mentioned above, the beam in which the desired wave and the interfering wave interfere is shown as "0". Return to Figure 6.

[0027] Before receiving a beam avoidance request, the second base station 104 pre-measures the communication quality with the second mobile terminal 103, such as the received signal strength and SNR (Signal-to-Noise Ratio), while changing beams. When the second base station 104 receives a beam avoidance request, it extracts alternative candidate destinations that are at least above a minimum communication threshold (e.g., 5 dB) from the communication quality of each beam measured in advance. Figure 8 shows an overview of the arbitration process at the second base station 104. The beam number of the second base station 104, the communication quality with the second mobile terminal 103, and the separation angle from the interfering wave beam are shown, but the separation angle from the interfering wave beam has not been calculated at the time the beam avoidance request is received.

[0028] The second base station 104 selects beam "3," which has the highest communication quality. The second base station 104 simulates the propagation path of beam "3" in Figure 6, taking reflections and other factors into consideration, using the ray tracing method. The second base station 104 also simulates the propagation path of beam "0" in Figure 6, taking reflections and other factors into consideration, using the ray tracing method. The propagation path of beam "0" corresponds to the propagation path of the interference wave at the first mobile terminal 102. Based on the simulation results, the second base station 104 calculates the difference between the reception angle of beam "3" and the reception angle of beam "0" at the first mobile terminal 102 as the separation angle. If the separation angle is greater than or equal to the second threshold at which interference reduction is possible, the second base station 104 decides to use beam "3" as the evacuated beam. If the separation angle is less than the second threshold at which interference reduction is possible, the second base station 104 selects the beam with the next highest communication quality and repeats the same process as before.

[0029] The transmitting beamforming unit 612 of the second base station 104 performs the change to beam "3". In other words, when the second base station 104 receives a beam retraction request from the first base station 101, it uses the beam ID of the second base station 104 to retract the beam in a direction other than the beam direction indicated by the beam ID, among the beam directions that the second mobile terminal 103 can receive.

[0030] The network interface 615 of the second base station 104 transmits a beam evacuation report containing information about the direction of the beam after beam evacuation to the first base station 101 via the internet 100 (S905). The beam evacuation report includes the angle and distance of beam "3".

[0031] The network interface 615 of the first base station 101 receives a beam evasion report from the second base station 104 via the internet 100. Upon receiving the beam evasion report, the first base station 101 performs beam evasion based on the beam information contained in the report. Before receiving the beam evasion report, the first base station 101 pre-measures the communication quality with the first mobile terminal 102, such as received signal strength and SNR, while changing the beam. Upon receiving the beam evasion report, the first base station 101 extracts alternative candidate destinations that are at least above a minimum communication threshold (e.g., 5 dB) from the communication quality of each beam measured in advance. The first base station 101 simulates the propagation path of each extracted beam, taking reflections into consideration, using the ray tracing method. Figure 9 shows an overview of the arbitration process at the first base station 101. The beam number of the first base station 101, the communication quality with the first mobile terminal 102, and the separation angle from the retracted beam are shown, respectively. However, at the time the beam retraction report is received, the separation angle from the retracted beam has not been calculated.

[0032] The first base station 101 simulates the propagation path of beam "3" in Figure 6, taking reflections into account, using the ray tracing method. The propagation path of beam "3" corresponds to the propagation path of the interference wave after the second base station 104 has moved away at the first mobile terminal 102. Based on the simulation results, the first base station 101 calculates the difference between the reception angle of each beam and the reception angle of beam "3" as the separation angle. The first base station 101 determines the beam with the largest separation angle, in this case beam "4", as the evacuation destination. In Figure 7, at the first mobile terminal 102, beam "4" is angularly separated from beam "3", which is the evacuation destination of the second base station 104. When the beam is angularly separated, the possibility of interference is reduced. The transmitting beamforming unit 612 of the first base station 101 executes the change to beam "4" (S906).

[0033] In other words, the first base station 101 controls the beam used by the first mobile terminal 102 to communicate with the first base station 101 (hereinafter referred to as the "first beam") and the beam directed in the direction in which the first mobile terminal 102 receives radio signals from the second base station 104 (hereinafter referred to as the "second beam") to widen the angle between them, within the range in which communication between the first mobile terminal 102 and the first base station 101 is possible. Furthermore, the first base station 101 selects the first beam according to the communication quality with the first base station 101 for each beam received by the first mobile terminal 102 and the angle between each beam and the second beam.

[0034] This configuration can be implemented in hardware terms using at least one CPU, memory, and other LSIs of any computer, and in software terms using programs loaded into memory, etc., but here we are depicting functional blocks that are realized through the cooperation of these components. Therefore, it will be understood by those skilled in the art that these functional blocks can be realized in various ways using hardware alone, software alone, or a combination of both.

[0035] Figure 10 is a flowchart showing the processing procedure by the first mobile terminal 102. If the first mobile terminal 102 detects an interference wave (Y in S201), it generates an interference arbitration request (S202). The transmitting unit 510 transmits the interference arbitration request (S203). If no interference wave is detected (N in S201), steps S202 and S203 are skipped.

[0036] Figure 11 is a flowchart showing the processing procedure by the first base station 101. When the receiving unit 603 receives an interference arbitration request (Y in S301), the network interface 615 sends a beam evacuation request (S302). If the network interface 615 does not receive a beam evacuation report (N in S303), it waits. When the network interface 615 receives a beam evacuation report (Y in S303), the transmitting beamforming unit 612 performs beam evacuation (S304). If the receiving unit 603 does not receive an interference arbitration request (N in S301), steps S302 to S304 are skipped.

[0037] Figure 12 is a flowchart showing the processing procedure by the second base station 104. When the network interface 615 receives a beam evacuation request (Y in S401), the transmitting beamforming unit 612 performs beam evacuation (S402). The network interface 615 transmits a beam evacuation report (S403). If the network interface 615 does not receive a beam evacuation request (N in S401), steps S402 and S403 are skipped.

[0038] According to this embodiment, when a first mobile terminal that communicates with the first base station but not with the second base station detects interference from the second base station, it sends an interference arbitration request to the first base station, the first base station sends a beam evacuation request to the second base station, and the second base station performs interference arbitration, thereby suppressing interference at multiple base stations using array antennas. Furthermore, since the second base station evacuates to a beam that moves away from the interfering wave, and the first base station evacuates to a beam that moves away from the evacuated beam of the second base station, interference can be suppressed at multiple base stations using array antennas. In addition, even when the first and second base stations change beams, the changes are made in a way that maintains the communication quality between the first base station and the first mobile terminal, and between the second base station and the second mobile terminal, thus reducing the impact of beam changes on communication.

[0039] (Example 2) Next, Example 2 will be described. Example 2 relates to a wireless communication system 1000 similar to that of Example 1. In Example 1, the first mobile terminal 102 does not perform beamforming. On the other hand, in Example 2, the first mobile terminal 102 performs beamforming. The wireless communication system 1000 and the first base station 101 according to Example 2 are of the same type as those shown in Figures 1 and 3. Here, the differences from Example 1 will be explained in detail.

[0040] Figure 13 shows the configuration of the first mobile terminal 102. Compared to Figure 2, the first mobile terminal 102 includes an antenna array 520 instead of the antenna 501, and further includes a receiving beam forming unit 522 and a transmitting beam forming unit 524. The antenna array 520 is an array in which antennas are arranged at predetermined intervals, and corresponds to an array antenna. Each antenna converts radio waves and electric currents in the same way as the antenna 501. Note that the antenna array 520 may be any other type of directional antenna. For example, the antenna array 520 may be a parabolic antenna, and the transmitting beam forming unit 524 and the receiving beam forming unit 522 may be replaced with an antenna rotating unit. The antenna rotating unit rotates the antenna in a specified direction. In other words, the antenna array 520 can be any type of directional antenna.

[0041] The receiving beamforming unit 522 phase-shifts and adds the signals from each antenna so that only radio waves at a predetermined angle are detected. The transmitting beamforming unit 524 phase-shifts the signals to be transmitted to each antenna so that radio waves are emitted at a predetermined angle.

[0042] Figure 14 is a sequence diagram showing the arbitration procedure by the wireless communication system 1000. Steps 951 to 956 are the same as steps 901 to 906 in Figure 5, so their explanation is omitted. The first base station 101 transmits a beam evasion report containing information on the direction of the first beam to the first mobile terminal 102 (S957). The beam evasion report may also include the location information of the first base station 101. This beam evasion report corresponds to an instruction to change the direction of the beam of the first mobile terminal 102 to a direction in which the first beam can be received.

[0043] The first mobile terminal 102 receives a beam evacuation report from the first base station 101. The first mobile terminal 102 performs beamforming to select a beam that can receive the first beam in accordance with the beam evacuation report from the first base station 101 (S958). In other words, the first mobile terminal 102 changes the direction of the beam in accordance with the instructions from the first base station 101.

[0044] The wireless communication system 1000 may subsequently perform the following processing. If the first mobile terminal 102 detects interference as in step 951 even after changing the beam direction, that is, if the interference has not been eliminated, the first mobile terminal 102 determines the beam direction by searching for a beam direction that can reduce interference. Since a known technique may be used for determining such a beam direction, a description is omitted here. The first mobile terminal 102 transmits to the first base station 101 a change request signal for requesting to use a beam in a direction different from the direction instructed by the first base station 101. The change request signal includes information on the determined beam direction.

[0045] The first base station 101 receives the change request signal from the first mobile terminal 102. If the beam direction included in the change request signal is not used by another mobile terminal, the first base station 101 permits the use of the beam direction included in the change request signal. The first base station 101 transmits to the first mobile terminal 102 a permission signal for notifying of permission to use the beam direction included in the change request signal. The first base station 101 changes the beam direction according to the beam direction included in the change request signal. When the first mobile terminal 102 receives the permission signal from the first base station 101, the first mobile terminal 102 changes the beam direction.

[0046] According to the present embodiment, in addition to changing the beam direction of the interfering second base station, the first mobile terminal experiencing interference also changes the beam direction. Therefore, compared to the case where only the beam direction of the second base station is changed, the influence of interference can be further suppressed. Further, if interference is not improved even when the beam is directed in the direction instructed by the first base station, the first mobile terminal determines the beam direction by itself, so that the influence of interference can be reduced.

[0047] Heretofore, the present invention has been described based on the embodiments. It should be understood by those skilled in the art that the embodiments are illustrative, that various modifications can be made to the combinations of the respective constituent elements and processing processes, and that such modifications are also within the scope of the present invention.

[0048] The wireless communication system 1000 according to the present embodiment targets mobile communication. However, the present invention is not limited thereto, and for example, the wireless communication system 1000 may be applied to local communication. According to this modification, the scope of application of the present embodiment can be expanded.

[0049] The wireless communication system 1000 according to the present embodiment targets communication using radio waves. However, the present invention is not limited thereto, and for example, the wireless communication system 1000 may be applied to communication using sound waves. According to this modification, the scope of application of the present embodiment can be expanded.

[0050] In the wireless communication system 1000 according to the present embodiment, after the second base station 104 determines a beam direction for avoiding interference, the first base station 101 determines a beam direction in accordance with the beam direction changed by the second base station 104. However, the present invention is not limited thereto, and for example, the first base station 101, the first mobile terminal 102, the second mobile terminal 103, and the second base station 104 are connected to at least one server (processing device) connected to the Internet 100, and the server may collectively execute the processing of the first base station 101 and the processing of the second base station 104. According to this modification, the degree of freedom in configuration can be expanded. On the other hand, in Embodiments 1 and 2, it can be said that at least one of the first base station 101 and the second base station 104 includes a processing device.

[0051] According to the present invention, interference can be suppressed in a plurality of base stations using directional antennas.

[0052] 100 Internet, 101 First base station, 102 First mobile terminal, 103 Second mobile terminal, 104 Second base station, 501 Antenna, 502 Receiving unit, 503 Multiplexing and restoration unit, 504 Demodulation unit, 505 Decoding unit, 506 Information processing unit, 507 Encoding unit, 508 Modulation unit, 509 Multiplexing unit, 510 Transmitting unit, 511 Network interface, 520 Antenna array, 522 Receiving beamforming unit, 524 Transmitting beamforming unit, 601 Antenna array, 602 Receiving beamforming unit, 603 Receiving unit, 604 Multiplexing and restoration unit, 605 Demodulation unit, 606 Decoding unit, 607 Information processing unit, 608 Encoding unit, 609 Modulation unit, 610 Multiplexing unit, 611 Transmitter, 612 Transmitting beamforming unit, 615 Network interface, 1000 Wireless communication system.

Claims

1. A wireless communication system comprising: a first base station having a directional antenna; a first mobile terminal communicating with the first base station and having a directional antenna; a second base station communicating with the first mobile terminal via a network and performing wireless communication with a second mobile terminal using a signal containing identification information; and a processing device that performs interference arbitration, wherein when the first mobile terminal receives a radio signal from the second base station, it detects the identification information of the second base station from the radio signal; the processing device performs interference arbitration with the second base station via the network in response to the detection of the identification information; and the processing device controls the angle between a first beam for the first mobile terminal to communicate with the first base station and a second beam directed in the direction in which the first mobile terminal receives the radio signal from the second base station, within the range in which communication between the first mobile terminal and the first base station is possible.

2. The wireless communication system according to claim 1, wherein the processing device selects the first beam according to the communication quality with the first base station in each beam of the first mobile terminal and the angle between each beam and the second beam.

3. The wireless communication system according to claim 2, wherein the angle of the second beam is determined by simulation.

4. The wireless communication system according to claim 1, wherein the first mobile terminal selects a beam capable of receiving the first beam in accordance with instructions from the processing device.

5. The wireless communication system according to claim 4, wherein the first mobile terminal transmits to the first base station that it wishes to use a beam in a direction different from the direction instructed by the processing device, and the first base station grants permission to the first mobile terminal to use it.

6. A wireless communication system comprising: a first base station having a directional antenna; a mobile terminal communicating with the first base station; and a second base station having a directional antenna but not communicating with the mobile terminal, wherein the mobile terminal, upon receiving a radio signal from the second base station, transmits an interference arbitration request to the first base station to request interference arbitration with the second base station; the first base station, upon receiving the interference arbitration request from the mobile terminal, transmits a beam evacuation request to the second base station to request beam evacuation; and the second base station, upon receiving the beam evacuation request from the first base station, performs arbitration to avoid a degradation of communication quality due to beam interference.

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