Wireless communication system, wireless communication device, and wireless communication method

Abstract

A wireless communication system has a first wireless communication device and a second wireless communication device. The first wireless communication device wirelessly communicates with the second wireless communication device through one or more first antennas. The second wireless communication device wirelessly communicates with the first wireless communication device through one or more second antennas. A control section of the wireless communication system controls to change either or both of the first antenna of the first wireless communication device that wirelessly communicates with the second wireless communication device among the first antennas of the first wireless communication device or the second antenna of the second wireless communication device that wirelessly communicates with the first wireless communication device among the second antennas of the second wireless communication device based on a communication quality between the first antenna and the second antenna at each time and maximizes the communication quality, the communication quality being calculated using movement scheduling information showing a position of the first wireless communication device at each time and a position of the second antenna.

Description

Technical Field

[0001] This invention relates to wireless communication systems, wireless communication devices, and wireless communication methods.

[0002] This application claims priority to PCT / JP2020 / 022650 filed on June 9, 2020, the contents of which are incorporated herein by reference. Background Technology

[0003] MIMO communication is a communication method that uses multiple antennas to achieve high-speed and high-reliability wireless communication. In MIMO communication, there are techniques that select a subset of receiving antennas based on CSI (Channel State Information) to maximize channel capacity (e.g., see Non-Patent Document 1). This allows for the determination of near-optimal transmission capacity at low cost. Furthermore, there are techniques that use the feedback CSI to select a subset of antennas from among the multiple antennas used in wireless communication (e.g., see Non-Patent Document 2).

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-patent literature 1: Alexei Gorokhov, Dhananjay A. Gore and Arogyaswami J. Paulraj, “Receive Antenna Selection for MIMO Spatial Multiplexing: Theory and Algorithms”, IEEE Transactions on Signal Processing, Vol. 5, No. 1, 2003, pp. 796-2807.

[0007] Non-patent literature 2: Shahab Sanayei and Aria Nosratinia, “Antenna Selection in MIMO Systems”, IEEE Communications magazine, Vol. 42, No. 10, 2004, pp. 68-73.

[0008] Non-patent document 3: C. Kato, M. Nakadai, D. Goto, H. Shibayama and F. Yamashita, "Channel Capacity Analysis of Satellite MIMO System Depending on the OrbitalAltitude", in 37th AIAA International Communication Satellite Systems Conference (ICSSC 2019), October 2019. Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] When a wireless communication device is mounted on a mobile body, the Communication Channel Index (CSI) changes as the device moves. In the technologies of Non-Patent Documents 1 and 2, in order to select a subset of antennas so that the mobile wireless communication device always communicates with optimal or near-optimal transmission capacity, the CSI must be estimated / obtained at high frequency. This not only increases the load on the wireless communication device, but also has the potential to lead to a decrease in communication efficiency when CSI feedback is required. Moreover, in the technology of Non-Patent Document 3, a communication path model considering the orbital conditions of the satellite as a mobile body is constructed, and the communication path capacity can be controlled according to the distance between transmitting antennas or the distance between receiving antennas through analytical derivation, thus showing that MIMO can be applied to satellites. However, there is a periodicity in the temporal variation of channel capacity in the satellite communication path, and due to the influence of periodicity, there are periods of complete signal interference, thus posing problems in terms of communication capacity reduction and communication line stability.

[0011] In view of the above, the object of the present invention is to provide a wireless communication system, wireless communication device, and wireless communication method that can suppress load and simultaneously conduct wireless communication with high communication quality even when the wireless communication device is in motion.

[0012] Solution for solving the problem

[0013] One aspect of the present invention is a wireless communication system having a first wireless communication device and a second wireless communication device. The first wireless communication device includes: one or more first antennas; and a first communication unit that communicates wirelessly with the second wireless communication device via the first antennas. The second wireless communication device includes: one or more second antennas; and a second communication unit that communicates wirelessly with the first wireless communication device via the second antennas. The wireless communication system includes a control unit that controls, based on the communication quality between the first antennas and the second antennas at each moment and to maximize the communication quality, to change either or both of the following antennas: the first antenna among the first antennas of each of the plurality of the first wireless communication devices that communicates wirelessly with the second wireless communication device; or the second antenna among the plurality of second antennas of the second wireless communication device that communicates wirelessly with the first wireless communication device. The communication quality is calculated using motion scheduling information showing the position of the first wireless communication device at each moment and the position of the second antenna.

[0014] One aspect of the present invention is a wireless communication device comprising: one or more antennas; a communication unit that wirelessly communicates with a communication destination device via the aforementioned antennas; and a control unit that controls, based on the communication quality between the aforementioned antennas and the antennas of the aforementioned communication destination devices at each moment and to maximize the communication quality, to change either or both of the following antennas: an antenna among the aforementioned antennas of each of the plurality of aforementioned communication destination devices that wirelessly communicates with its own device; or an antenna among the plurality of aforementioned antennas of its own device that wirelessly communicates with the aforementioned communication destination device, wherein the aforementioned communication quality is calculated using motion scheduling information indicating the position of the aforementioned communication destination device at each moment and the position of the aforementioned antennas.

[0015] One aspect of the present invention is a wireless communication device, which is the aforementioned wireless communication device in a wireless communication system having multiple wireless communication devices. The aforementioned wireless communication device includes: one or more antennas; a communication unit that performs wireless communication with a communication destination device through the aforementioned antennas; and a control unit that controls the aforementioned communication unit to transmit wireless signals to the aforementioned communication destination device at a time when, based on the communication quality between the respective antennas of the multiple wireless communication devices and the antenna of the aforementioned communication destination device at each moment and to maximize the communication quality, the aforementioned communication quality is calculated using motion scheduling information showing the position of each of the multiple wireless communication devices at each moment and the position of the antenna of the aforementioned communication destination device.

[0016] One aspect of the present invention is a wireless communication method performed by a wireless communication system having a first wireless communication device and a second wireless communication device. The wireless communication method comprises: a first communication step, wherein the first wireless communication device communicates wirelessly with the second wireless communication device via one or more first antennas; a second communication step, wherein the second wireless communication device communicates wirelessly with the first wireless communication device via one or more second antennas; and a control step, wherein a control unit controls, based on the communication quality at each moment between the first antenna and the second antenna, to change either or both of the following antennas to maximize the communication quality: the first antenna among the first antennas of each of the plurality of first wireless communication devices that communicates wirelessly with the second wireless communication device; or the second antenna among the plurality of second antennas of the second wireless communication device that communicates wirelessly with the first wireless communication device, wherein the communication quality is calculated using motion scheduling information showing the position of the first wireless communication device at each moment and the position of the second antenna.

[0017] One aspect of the present invention is a wireless communication method performed by a wireless communication device, the wireless communication method comprising: a communication step, wherein wireless communication is performed with a communication destination device via one or more antennas; and a control step, wherein the control is performed to maximize the communication quality between the antennas at each moment and the antennas of the communication destination device by changing either or both of the following antennas: an antenna among the antennas of each of the plurality of antennas ...

[0018] One aspect of the present invention is a wireless communication method performed by the aforementioned wireless communication devices in a wireless communication system having multiple wireless communication devices. The aforementioned wireless communication method includes: a communication step, wherein wireless communication is performed with a communication destination device via one or more antennas; and a control step, wherein the control is configured to: at a time when the aforementioned antenna of the device itself is selected as the communication destination of the aforementioned communication destination device based on the communication quality between the respective antennas of the multiple aforementioned wireless communication devices and the antenna of the aforementioned communication destination device at each moment, and to maximize the communication quality, transmit a wireless signal to the aforementioned communication destination device in the aforementioned communication step, wherein the aforementioned communication quality is calculated using motion scheduling information indicating the position of each of the multiple aforementioned wireless communication devices at each moment and the position of the antenna of the aforementioned communication destination device.

[0019] Invention Effects

[0020] This invention enables the suppression of load and simultaneous high-quality wireless communication, even when the wireless communication device is in motion. Attached Figure Description

[0021] Figure 1 This is a diagram illustrating an outline of a wireless communication system according to a first embodiment of the present invention.

[0022] Figure 2 This is a functional block diagram of a wireless communication system according to this embodiment.

[0023] Figure 3 This is a flowchart illustrating the processing of a wireless communication system according to this embodiment.

[0024] Figure 4 This is a functional block diagram of a mobile relay station and a base station according to this implementation method.

[0025] Figure 5 This is a flowchart illustrating the processing of a wireless communication system according to this embodiment.

[0026] Figure 6 This is a flowchart illustrating the processing of a base station according to the second embodiment.

[0027] Figure 7 This is a diagram showing an outline of a wireless communication system according to a third embodiment.

[0028] Figure 8 This is a configuration diagram of a wireless communication system according to the third embodiment.

[0029] Figure 9 This is a flowchart illustrating the processing of a wireless communication system according to this embodiment.

[0030] Figure 10 This is a functional block diagram of a mobile relay station and a base station according to this implementation method.

[0031] Figure 11 This is a diagram showing an outline of a wireless communication system according to the fourth embodiment.

[0032] Figure 12 This is a diagram illustrating an example of the configuration of an antenna at a mobile relay station.

[0033] Figure 13 This is a graph showing the analysis results of channel capacity when MIMO communication occurs between a mobile relay station and a base station.

[0034] Figure 14This is a graph showing the analysis results of the average time and channel capacity that each antenna can utilize for MIMO per cycle.

[0035] Figure 15 This is a flowchart illustrating the process by which a mobile relay station decides to utilize a combination of antennas.

[0036] Figure 16 This is a flowchart illustrating the process of transmitting base station downlink signals from a mobile relay station.

[0037] Figure 17 This is a flowchart illustrating the process by which a base station receives downlink signals from a mobile relay station.

[0038] Figure 18 This is a flowchart illustrating the process by which a mobile relay station decides to utilize a combination of antennas and transmits downlink signals from the base station.

[0039] Figure 19 This is a diagram showing an outline of a wireless communication system according to the sixth embodiment.

[0040] Figure 20 This is a flowchart illustrating the process by which the antenna number determination station decides on the combination of antennas to be used.

[0041] Figure 21 This is a flowchart illustrating the process by which the antenna number determination station decides on the combination of antennas to be used.

[0042] Figure 22 This is a flowchart illustrating the process of transmitting base station downlink signals from a mobile relay station.

[0043] Figure 23 This is a block diagram illustrating the configuration of a mobile relay station and a base station when the mobile relay station receives uplink signals from the base station.

[0044] Figure 24 This is a flowchart illustrating the process of transmitting base station uplink signals from the base station.

[0045] Figure 25 This is a flowchart illustrating the process by which a mobile relay station receives uplink signals from a base station.

[0046] Figure 26 This is a flowchart illustrating the process by which a base station selects the antenna station to use in real time and transmits the base station uplink signal.

[0047] Figure 27 This is a flowchart illustrating the process by which a mobile relay station decides to utilize a combination of antennas and receive uplink signals from a base station.

[0048] Figure 28This is a block diagram illustrating the configuration of a mobile relay station and a base station when the mobile relay station receives uplink signals from the base station.

[0049] Figure 29 This is a flowchart illustrating the process by which a mobile relay station receives uplink signals from a base station.

[0050] Figure 30 This is a diagram showing an outline of the wireless communication system according to the eighth embodiment.

[0051] Figure 31 This is a configuration diagram of the wireless communication system according to the eighth embodiment. Detailed Implementation

[0052] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0053] (First Implementation)

[0054] Figure 1 This is a diagram showing an outline of a wireless communication system 1 according to a first embodiment. The wireless communication system 1 includes a mobile relay station 2, a terminal station 3, and a base station 4. The number of each of the mobile relay station 2, terminal station 3, and base station 4 in the wireless communication system 1 is arbitrary, but it is assumed that the number of terminal stations 3 is many.

[0055] Mobile relay station 2 is an example of a wireless communication device mounted on a mobile body, and the area of ​​communication shifts over time. For example, a mobile relay station 2 could be located on a LEO (Low Earth Orbit) satellite. Terminal station 3 and base station 4 are located on Earth, either on land or at sea. Terminal station 3 is, for example, an IoT terminal. Terminal station 3 collects environmental data detected by sensors and transmits this data wirelessly to mobile relay station 2. Mobile relay station 2 moves over Earth and simultaneously receives data transmitted from multiple terminal stations 3 via wireless signals, then wirelessly transmits this received data to base station 4. Base station 4 receives the data collected by terminal stations 3 from mobile relay station 2.

[0056] As a mobile relay station, relay stations mounted on geostationary satellites or unmanned aerial vehicles (UAVs) such as drones or HAPS (High Altitude Platform Stations) are considered. However, with relay stations mounted on geostationary satellites, although the ground coverage area is wide, the link budget for IoT terminals located on Earth is very small due to the high altitude. On the other hand, with relay stations mounted on drones or HAPS, although the link budget is high, the coverage area is narrow. Moreover, drones require batteries, and HAPS require solar panels. In this embodiment, mobile relay station 2 is mounted on a LEO satellite. Therefore, in addition to the link budget falling within the limits, LEO satellites have no air resistance due to orbiting outside the atmosphere and consume less fuel. Furthermore, the coverage area is larger compared to the case of mounting the relay station on a drone or HAPS.

[0057] However, the mobile relay station 2 mounted on the LEO (Left-Oriented Loop) moves at high speed and communicates simultaneously, resulting in a smaller link budget compared to mounting the relay station on a drone or HAPS (Habitat-Assisted Relay). Therefore, in this embodiment, the base station 4 receives wireless signals from the mobile relay station 2 via multiple antenna stations 41. Figure 1 In this document, the four antenna stations 41 of base station 4 are referred to as antenna stations 41-1, 41-2, 41-3, and 41-4. By using multiple antenna stations 41, the diversity effect and beamforming effect of communication can be achieved, thereby improving communication quality and increasing transmission capacity.

[0058] The multiple antenna stations 41 of base station 4 are configured in mutually separated locations, which increases the difference in the angle of arrival of the signals from the multiple antennas of mobile relay station 2. By configuring the antenna stations 41 in separate locations, a phase difference is generated in the radio signals received by each antenna station 41 from mobile relay station 2. Thus, since the antenna stations 41 are set in geographically separated locations, the channel state between mobile relay station 2 and each antenna station 41 is different, and since mobile relay station 2 moves at high speed, its channel state changes with time.

[0059] To ensure that mobile relay station 2 and base station 4 maintain communication with the highest possible transmission capacity even as the channel state changes with the movement of mobile relay station 2, the transmission capacity of each antenna of mobile relay station 2 and each antenna station 41 of base station 4 at each time point is pre-calculated in this embodiment. This transmission capacity at each time point is calculated based on the mobile scheduling information of mobile relay station 2, the location information of each antenna station 41, and the frequency of wireless communication. The mobile scheduling information shows the location, speed, and direction of movement of mobile relay station 2 at each time point. In this embodiment, the orbital information of the LEO satellite carrying mobile relay station 2 is used as the mobile scheduling information. The orbital information provides information such as the location, speed, and direction of movement of the LEO satellite at any given time. The slant range, representing the distance between the antennas, is calculated from the locations of the antennas of mobile relay station 2 and the antenna stations 41 of base station 4. The location of the antenna of mobile relay station 2 can be the location of the LEO satellite obtained from the orbital information, or it can be a location deviating from the location of the LEO satellite by a predetermined distance and direction. Furthermore, the Doppler frequency shift is calculated using the frequency and the speed of the LEO satellite. Regarding the channel between the LEO satellite and antenna station 41 of base station 4, a foreground environment is assumed. Therefore, the multipath fading caused by reflected waves due to obstacles can be ignored, and the direct wave becomes the dominant channel. Thus, it can be considered that the attenuation coefficient or phase difference (CSI) is the only data uniquely determined based on the slant range information between the LEO satellite and antenna station 41 of base station 4. Based on the above, the channel capacity between the transmitting and receiving antennas is calculated from the SNR and channel matrix using Shannon's theorem. The SNR is calculated based on the slant range and Doppler shift, and the channel matrix is ​​obtained based on the slant range between the antenna of mobile relay station 2 and antenna station 41.

[0060] Furthermore, the transmission capacity of each antenna station 41 at each time is pre-stored in the base station 4. The transmission capacity is the downlink channel capacity pre-calculated based on the above. At each time, the base station 4 uses a predetermined number of antenna stations 41 with high transmission capacity to process the data sequence of radio signals received from the mobile relay station 2 during reception processing. For example, at time t1, the base station 4 uses the radio signals received by antenna stations 41-1 and 41-2 for reception processing, and at time t2, it uses the radio signals received by antenna stations 41-3 and 41-4 for reception processing.

[0061] Explain the composition of each device. Figure 2 This is a functional block diagram of the wireless communication system 1 according to the first embodiment.

[0062] The mobile relay station 2 includes one or more antennas 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 24, and one or more antennas 25. In this embodiment, the example is described where the mobile relay station 2 has multiple antennas 25 and the mobile relay station 2 and the base station 4 communicate wirelessly via MIMO (Multiple Input Multiple Output).

[0063] The terminal communication unit 22 includes a receiving unit 221, a terminal signal receiving and processing unit 222, and a data recording unit 223. The receiving unit 221 receives terminal uplink signals transmitted by each terminal station 3 via antenna 21. The terminal signal receiving and processing unit 222 performs reception processing of the terminal uplink signals. During reception processing, the terminal uplink signals received by the receiving unit 221 are demodulated and decoded to obtain the terminal transmission data transmitted by the terminal station 3. The data recording unit 223 writes the terminal transmission data obtained through reception processing into the data storage unit 23.

[0064] The base station communication unit 24 transmits terminal data to the base station 4. The base station communication unit 24 includes a storage unit 241, a control unit 242, a data modulation unit 243, and a transmission unit 244.

[0065] Storage unit 241 pre-stores the transmission weights of the base station downlink signals transmitted from each antenna 25 at each transmission time. The transmission weights for each transmission time are calculated based on the orbital information of the LEO satellites and the positions of each antenna station 41. Alternatively, fixed transmission weights can be used regardless of the transmission time.

[0066] The control unit 242 instructs the transmission data modulation unit 243 to transmit data from the terminal. Additionally, the control unit 242 instructs the transmission unit 244 to assign transmission weights for each transmission moment read from the storage unit 241. The transmission data modulation unit 243 receives the instruction from the control unit 242 and reads the terminal's transmission data from the data storage unit 23 as the transmission data. The transmission data modulation unit 243 modulates the read transmission data after converting it into a parallel signal. The transmission unit 244 uses the transmission weights instructed by the control unit 242 to weight the modulated parallel signal, generating a base station downlink signal transmitted from each antenna 25. The transmission unit 244 transmits the generated base station downlink signal from the antennas 25 via MIMO.

[0067] Terminal station 3 includes a data storage unit 31, a transmission unit 32, and one or more antennas 33. The data storage unit 31 stores sensor data, etc. The transmission unit 32 reads the sensor data from the data storage unit 31 as terminal transmission data, and wirelessly transmits the terminal uplink signal obtained by configuring the read terminal transmission data from the antennas 33. The transmission unit 32 transmits signals, for example, via LPWA (Low Power Wide Area Network). Alternatively, the transmission unit 32 can also transmit via time-division multiplexing, OFDM (Orthogonal Frequency Division Multiplexing), MIMO, etc., with another terminal station 3.

[0068] Base station 4 includes multiple antenna stations 41, a receiving unit 42, and a base station signal receiving and processing unit 43. The antenna stations 41 convert the base station downlink signals received from mobile relay station 2 into electrical signals and output them to the receiving unit 42. The receiving unit 42 collects the base station downlink signals received from the multiple antenna stations 41. The receiving unit 42 includes a storage unit 421, a control unit 422, and an adder unit 423.

[0069] Storage unit 421 pre-stores transmission capacity information and reception weights for each reception time. The transmission capacity information shows the downlink transmission capacity of each antenna station 41 at each reception time. Based on the orbital information of the LEO satellite and the position of each antenna station 41, the reception weight for each reception time is calculated.

[0070] The control unit 422, referring to the transmission capacity information stored in the storage unit 421, selects a predetermined number of antenna stations 41 in descending order of transmission capacity at each reception time. The number of selected antenna stations 41 is smaller than the total number of antenna stations 41 possessed by the base station 4. The control unit 422 instructs the summing unit 423 as if adding the received signals of the selected antenna stations 41. Furthermore, the control unit 422 reads the reception weight of each received signal at each reception time from the storage unit 421 and instructs the summing unit 423 on the read reception weight.

[0071] The summing unit 423 multiplies the received signals of each antenna station 41 after summing by the control unit 422 by the receiving weights indicated by the control unit 422, and then sums the received signals after multiplying by the receiving weights. Alternatively, the same receiving weights can be used regardless of the receiving time.

[0072] The base station signal receiving and processing unit 43 demodulates and decodes the received signal after being added and synthesized by the adding unit 423 to obtain the terminal transmission data.

[0073] Explain the operation of wireless communication system 1.

[0074] Mobile relay station 2 stores the terminal transmission data received from each terminal station 3 in data storage unit 23. Specifically, each terminal station 3 continuously acquires data detected by sensors (not shown) located externally or internally on each terminal station 3 and writes it to data storage unit 31. Transmitting unit 32 reads sensor data from data storage unit 31 as terminal transmission data and wirelessly transmits the terminal uplink signal obtained after setting the read terminal transmission data from antenna 33. Receiving unit 221 of mobile relay station 2 receives the terminal uplink signals transmitted from each terminal station 3, and terminal signal receiving and processing unit 222 demodulates and decodes the terminal uplink signals received by receiving unit 221 to obtain the terminal transmission data. Data recording unit 223 writes the terminal transmission data to data storage unit 23.

[0075] Figure 3 This is a flowchart illustrating the processing of the wireless communication system 1 when transmitting a base station downlink signal from the mobile relay station 2. The control unit 242 of the base station communication unit 24 of the mobile relay station 2 reads the transmission weight corresponding to the current time from the storage unit 241 and instructs it to the transmission unit 244 (step S111). The transmission data modulation unit 243 receives the instruction from the control unit 242 and reads the terminal transmission data stored in the data storage unit 23 as the transmission data (step S112).

[0076] The transmission data modulation unit 243 encodes the read transmission data and modulates it after performing parallel conversion on the encoded transmission data. The transmission unit 244 uses the transmission weights indicated by the control unit 242 to weight the transmission data modulated by the transmission data modulation unit 243 to generate base station downlink signals as transmission signals transmitted from each antenna 25. The transmission unit 244 transmits the generated base station downlink signals from each antenna 25 via MIMO (step S113). The mobile relay station 2 repeats the processing from step S111. Alternatively, the mobile relay station 2 may perform the processing of step S111 after the processing of step S112.

[0077] Each antenna station 41 of base station 4 outputs a received signal obtained by converting the downlink signal received from mobile relay station 2 into an electrical signal to receiving unit 42 (step S121). Control unit 422 selects a predetermined number of antenna stations 41 with high transmission capacity at the current time as a subset, referring to the transmission capacity information stored in storage unit 421 (step S122). Control unit 422 instructs summing unit 423 as if receiving the received signal from the selected subset of antenna stations 41. Furthermore, control unit 422 reads the reception weight corresponding to the current time from storage unit 421 and instructs summing unit 423 on the read reception weight (step S123).

[0078] The summing unit 423 selects the received signals of each antenna station 41 as indicated by the control unit 422 in the reception process, and multiplies the selected received signals by the reception weights indicated by the control unit 422. The summing unit 423 adds the received signals after multiplying by the reception weights (step S124). The base station signal reception processing unit 43 demodulates the added received signals and decodes the demodulated received signals to obtain the terminal transmission data (step S125). The base station 4 repeats the processing from step S121.

[0079] Furthermore, if the mobile relay station 2 has only one antenna 25, the mobile relay station 2 does not perform the processing in step S111. Then, in step S113, the transmission data modulation unit 243 modulates the transmission data of the serial signal, and the transmission unit 244 transmits the base station downlink signal obtained by setting the modulated transmission data from the antenna 25.

[0080] Furthermore, in the above, the storage unit 421 of the base station 4 stores the pre-calculated transmission capacity information and reception weight, but the control unit 422 can also generate this information at any time and write it to the storage unit 421.

[0081] Alternatively, the storage unit 421 can store a subset of antenna stations 41 for each moment or time period instead of transmission capacity information. Based on the downlink transmission capacity of each antenna station 41 at each moment, a predetermined number of antenna stations 41 are selected as a subset in descending order of transmission capacity. In step S122, the control unit 422 reads the information of the subset of antenna stations 41 corresponding to the current moment from the storage unit 421.

[0082] Mobile relay station 2 can also receive uplink signals from base station 4. In this case, as described above, the uplink transmission capacity of each antenna and each antenna station 41 of mobile relay station 2 at each time is calculated in advance based on the mobile scheduling information of mobile relay station 2, the location information of each antenna station 41 of base station 4, and the frequency of wireless communication.

[0083] Figure 4 This is a block diagram showing the configuration of mobile relay station 2 and base station 4 when mobile relay station 2 receives uplink signals from base station 4. Figure 4 In this paper, only the functional parts related to the transmission and reception of uplink signals of the base station are shown.

[0084] Base station 4 includes a transmitting unit 44. The transmitting unit 44 includes a storage unit 441, a control unit 442, a transmission data modulation unit 443, and a weight multiplication unit 444.

[0085] Storage unit 441 pre-stores transmission capacity information and transmission weights for each transmission time. The transmission capacity information stored in storage unit 441 indicates the uplink transmission capacity between each antenna station 41 and the mobile relay station 2 at each transmission time. Based on the orbital information of the LEO satellite and the position of each antenna station 41, the transmission weight for each transmission time is calculated.

[0086] The control unit 442, referring to the transmission capacity information stored in the storage unit 441, selects a predetermined number of antenna stations 41 in descending order of uplink transmission capacity at each transmission time. The number of selected antenna stations 41 is smaller than the total number of antenna stations 41 possessed by the base station 4. The control unit 442 instructs the transmission data modulation unit 443 as if transmitting the terminal uplink signal using the antenna stations 41 selected at each transmission time. Furthermore, the control unit 442 reads the transmission weight of each antenna station 41 at each transmission time from the storage unit 441 and instructs the read transmission weight to the weight multiplication unit 444.

[0087] The transmission data modulation unit 443 encodes the transmission data sent to the mobile relay station 2. After converting the encoded transmission data into parallel signals transmitted from each antenna station 41 as instructed by the control unit 442, the transmission data modulation unit 443 modulates the signals. The weight multiplication unit 444 uses the transmission weights instructed by the control unit 442 to weight the modulated parallel signals, generating base station uplink signals transmitted from each antenna station 41. The weight multiplication unit 444 outputs the generated base station uplink signals to the corresponding antenna station 41. The antenna station 41 selected by the control unit 442 wirelessly transmits the base station uplink signals.

[0088] The base station communication unit 24 of the mobile relay station 2 includes a storage unit 241, a control unit 242, a receiving unit 245, and a receiving processing unit 246. The storage unit 241 pre-stores the reception weights of the base station uplink signals received by each antenna 25 at each reception time. The reception weights for each reception time are calculated based on the orbital information of the LEO satellite and the positions of each antenna station 41. Alternatively, fixed reception weights can be used regardless of the reception time.

[0089] The control unit 242 reads the reception weights of each antenna 25 at each reception time from the storage unit 241 and instructs the received unit 245 of the read reception weights. The received unit 245 receives the uplink signals of the base station through each antenna 25, and after weighting the received signals received by each antenna 25 using the reception weights indicated by the control unit 242, it performs summation. The receiving processing unit 246 demodulates and decodes the received signals after summation by the receiving unit 245 to obtain the transmitted data sent by the base station 4.

[0090] Figure 5This is a flowchart illustrating the processing of the wireless communication system 1 when transmitting uplink signals from base station 4. The control unit 442 of base station 4, referring to the transmission capacity information stored in the storage unit 441, selects a predetermined number of antenna stations 41 as a subset at the current time, in descending order of uplink transmission capacity (step S211). The control unit 442 instructs the transmission data modulation unit 443 as if transmitting terminal uplink signals through the subset of antenna stations 41. Furthermore, the control unit 442 reads the transmission weights of each antenna station 41 in the subset corresponding to the current time from the storage unit 441 and instructs the read transmission weights to the weight multiplication unit 444 (step S212).

[0091] The data modulation unit 443 encodes the transmission data sent to the mobile relay station 2, and modulates it after converting the encoded transmission data into parallel signals transmitted from each antenna station 41 of the subset. The weight multiplication unit 444 uses the transmission weights indicated by the control unit 442 to weight the modulated parallel signals and generate base station uplink signals transmitted from each antenna station 41 of the subset. The weight multiplication unit 444 outputs the generated base station uplink signals to the corresponding antenna stations 41. Each antenna station 41 of the subset wirelessly transmits the base station uplink signals (step S213).

[0092] The receiving unit 245 of mobile relay station 2 receives uplink signals from the base station through each antenna 25 (step S221). The control unit 242 reads the reception weights of each antenna 25 corresponding to the current time from the storage unit 241 and instructs the received weights to the receiving unit 245 (step S222). After weighting the received signals received by each antenna 25 using the reception weights indicated by the control unit 242, the receiving unit 245 performs summation (step S223). The receiving processing unit 246 demodulates and decodes the received signals summed by the receiving unit 245 to obtain the transmitted data sent by the base station 4 (step S224).

[0093] Furthermore, if the mobile relay station 2 has only one antenna 25, the mobile relay station 2 does not perform the processes in steps S222 and S223. In step S224, the receiving processing unit 246 demodulates and decodes the base station uplink signal received by the receiving unit 245 through the antenna 25.

[0094] Furthermore, in the above description, the storage unit 441 of base station 4 stores the pre-calculated transmission capacity information and transmission weights, but the control unit 442 can also generate this information at any time and write it to the storage unit 441. Additionally, base station 4 can also transmit the transmission weights and reception weights of each antenna 25 at each moment to mobile relay station 2 via the base station uplink signal.

[0095] Alternatively, the storage unit 441 can store a subset of antenna stations 41 for each time moment or each time period, instead of transmission capacity information. Based on the uplink transmission capacity of each antenna station 41 at each time moment, a predetermined number of antenna stations 41 are selected as a subset in descending order of transmission capacity. In step S211, the control unit 442 reads the information of the subset of antenna stations 41 corresponding to the current time from the storage unit 441.

[0096] According to the implementation described above, base station 4 can receive data collected from multiple terminal stations 3 from mobile relay station 2 with good quality through a subset of antenna stations 41. Furthermore, in this embodiment, a channel model is pre-specified, and the information or subset of antenna stations 41 used in transmission and reception is pre-calculated to select the receiving weight or transmitting weight associated with the movement of mobile relay station 2. Therefore, CSI feedback is not required, reducing the transmission and reception processing between mobile relay station 2 and base station 4. Additionally, the pre-calculated transmission capacity is stored in base station 4, and a subset of antenna stations 41 is selected based on the stored transmission capacity. Thus, even if the transmission capacity of the selected subset of antenna stations 41 decreases for some reason, other antenna stations 41 can be selected.

[0097] (Second Implementation)

[0098] In the first embodiment, all antenna stations of the base station receive data. In this embodiment, the data is switched to antenna stations with higher transmission capacity one by one. Hereinafter, this embodiment will be described focusing on the differences from the first embodiment.

[0099] The configuration of the wireless communication system in this embodiment and Figure 2 The wireless communication system 1 of the first embodiment shown is similar. Furthermore, in this embodiment, as in the first embodiment, the transmission capacity of the antenna 25 of the mobile relay station 2 and each antenna station 41 of the base station 4 at each time is calculated. Then, for each time, a predetermined number of antenna stations 41 are selected as a subset to maximize the downlink transmission capacity. The transmission weight for transmitting the base station downlink signal to the selected subset of antenna stations 41 for each time or time period is pre-stored in the storage unit 241 of the mobile relay station 2. Additionally, the reception weight and selected antenna information showing the selected subset of antenna stations 41 for each time or time period are pre-stored in the storage unit 421 of the base station 4, wherein the reception weight is multiplied by the received signal using the selected subset of antenna stations 41 for each time.

[0100] In this embodiment, base station 4 is replaced Figure 3 The process is carried out in steps S121 to S122 as shown. Figure 6 The processing is shown. Figure 6This is a flowchart illustrating the processing of base station 4 in this embodiment.

[0101] The control unit 422 of base station 4 reads the selected antenna information, which is stored in the storage unit 421, containing information about a subset of antenna stations 41 at the current time. It then instructs the antenna stations 41 in the subset indicated by the read selected antenna information, as if performing reception (step S311). The control unit 422 may further instruct antenna stations 41 not included in the subset to stop receiving. The antenna stations 41 instructed to perform reception receive the base station downlink signal from the mobile relay station 2 and output the received signal, obtained by converting the received base station downlink signal into an electrical signal, to the receiving unit 42.

[0102] The control unit 422 reads the reception weights of the received signals of each antenna station 41 in the subset from the storage unit 421 and instructs them to the summing unit 423 (step S312). The summing unit 423 multiplies each received signal input from the antenna station 41 of the subset by the reception weights instructed by the control unit 422. The summing unit 423 adds the received signals after multiplying the reception weights (step S313). The base station signal receiving processing unit 43 demodulates the summed received signals and decodes the demodulated received signals to obtain the terminal transmission data (step S314). The base station 4 repeats the processing from step S311.

[0103] Furthermore, the storage unit 421 can also store the same transmission capacity information as in the first embodiment. In step S311, the control unit 422, referring to the transmission capacity information, selects a predetermined number of antenna stations 41 with high transmission capacity at the current moment as a subset. Additionally, the control unit 422 can also generate information stored in the storage unit 421 of the base station 4 at any time.

[0104] In this embodiment, when mobile relay station 2 receives uplink signals from base station 4, mobile relay station 2 and base station 4 have Figure 4 The configuration of the first embodiment is shown. However, the storage unit 441 of the base station 4 pre-stores transmission weights and antenna selection information showing the subset of antenna stations 41 selected for each time or time period. The transmission weights are multiplied by the transmission signals transmitted from the subset of antenna stations 41 selected for each transmission time. The subset of antenna stations 41 is selected based on the uplink transmission capacity of the antenna 25 of the mobile relay station 2 and each antenna station 41 of the base station 4 at each time. In addition, the storage unit 241 of the mobile relay station 2 stores reception weights for receiving base station uplink signals from the subset of antenna stations 41 selected for each time or time period.

[0105] In this embodiment, the mobile relay station 2 and base station 4, in addition to the following aspects, perform communication with... Figure 5The same process applies to the first embodiment shown. That is, in step S211, the control unit 442 of the base station 4 reads the subset of antenna stations 41 at the current time from the selected antenna information stored in the storage unit 441, and instructs the read subset of antenna stations 41 as if to transmit. Moreover, the control unit 442 may also instruct antenna stations 41 not included in the subset to stop transmitting.

[0106] Furthermore, the storage unit 441 may also store the same transmission capacity information as in the first embodiment. The control unit 442, referring to the transmission capacity information, selects a subset of all antenna stations 41 that currently have high transmission capacity. Additionally, the control unit 442 may generate information stored in the storage unit 441 of the base station 4 at any time.

[0107] (Third Implementation)

[0108] In the first and second embodiments, as the mobile relay station moves, any one of a plurality of antenna stations using the base station is selected. In this embodiment, the mobile relay station that the base station communicates with is selected from the plurality of mobile relay stations. This embodiment will be described primarily with respect to the differences from the first embodiment.

[0109] Figure 7 This is a diagram showing an outline of the wireless communication system 1a according to this embodiment. The wireless communication system 1a includes a mobile relay station 2a, a terminal station 3, and a base station 4a. In this diagram, the terminal station 3 is omitted. Hereinafter, N mobile relay stations 2a (N is an integer of 2 or more) will be referred to as mobile relay stations 2a-1 to 2a-N. Figure 7 An example is shown with N=2.

[0110] In this embodiment, based on the orbital information of LEO satellites carrying mobile relay stations 2a-n (n is an integer greater than 1 and less than N), the location information of each antenna station 41, and the frequency of wireless communication, the transmission capacity Cn between the mobile relay stations 2a-n and the antenna stations 41 of the base station 4a at each time is calculated. Then, the transmission capacity Cn is selected at each time. n The largest mobile relay station 2a-n is used as the communication destination. Base station 4a pre-stores the communication destination relay station information of mobile relay station 2a-n, which is listed as the communication destination at each time. Base station 4a wirelessly communicates with mobile relay station 2a-n, which is recorded as the communication destination at the current time in the communication destination relay station information. For example, during a time period when transmission capacity C1 > transmission capacity C2, base station 4a communicates with mobile relay station 2a-1; when the timer changes to when transmission capacity C1 < transmission capacity C2, base station 4a switches the communication destination from mobile relay station 2a-1 to mobile relay station 2a-2.

[0111] Figure 8 This is a block diagram showing the configuration of the wireless communication system 1a according to this embodiment. In this figure, regarding... Figure 2 The same parts of the wireless communication system 1 of the first embodiment shown are marked with the same symbols and their descriptions are omitted.

[0112] Mobile relay station 2a includes one or more antennas 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 24a, and one or more antennas 25. In this embodiment, an example is provided where mobile relay station 2a has multiple antennas 25, and mobile relay station 2a and base station 4a communicate wirelessly via MIMO. Base station communication unit 24a includes a storage unit 241a, a control unit 242a, a data modulation unit 243, and a transmission unit 244.

[0113] Storage unit 241a stores communication destination base station information that associates a communication time period with a base station 4a whose communication destination is itself, the mobile relay station, during that communication time period. Control unit 242a controls transmission data modulation unit 243 and transmission unit 244 to enable communication between the communication time period set in the communication destination base station information and the base station 4a associated with that communication time period. Furthermore, storage unit 241a pre-stores the transmission weights for each transmission moment of the base station downlink signals transmitted from each antenna 25 to the communication destination base station 4a. The transmission weights for each transmission moment are calculated based on the orbital information of the LEO satellite and the position of the antenna station 41 of the communication destination base station 4a.

[0114] Base station 4a includes multiple antenna stations 41, a receiving unit 42a, and a base station signal receiving and processing unit 43. The receiving unit 42a includes a storage unit 421a, a control unit 422a, and an adder unit 423.

[0115] Storage unit 421a pre-stores communication destination relay station information and reception weights for each reception time. The communication destination relay station information indicates the mobile relay station 2a of the communication destination at each reception time or each communication period. The reception weight for each reception time is calculated based on the orbital information of the LEO satellite carrying the mobile relay station 2a of the communication destination at that reception time and the positions of each antenna station 41. By using the reception weights, a beam can be generated and downlink signals from the base station 2a of the communication destination can be selectively received. Control unit 422a reads the reception weights of the received signals obtained using each antenna station 41 at each reception time from storage unit 421a and indicates the read reception weights to summing unit 423.

[0116] Explain the operation of wireless communication system 1a.

[0117] Figure 9This is a flowchart illustrating the processing of the wireless communication system 1a when transmitting a base station downlink signal from mobile relay station 2a. If the control unit 242a of mobile relay station 2a detects that the current time is the start time of a communication period set in the communication destination base station information, it notifies the transmission data modulation unit 243 to designate the base station 4a associated with that communication period as the communication destination (step S411). The control unit 242a reads the transmission weight corresponding to the current time from the storage unit 241a and instructs it to the transmission unit 244 (step S412).

[0118] The transmission data modulation unit 243 reads the terminal transmission data destined for the base station 4a from the data storage unit 23 as transmission data (step S413). The transmission data modulation unit 243 encodes the read transmission data. After parallel conversion, the transmission data modulation unit 243 modulates the encoded transmission data. The transmission unit 244 uses the transmission weights indicated by the control unit 242a to weight the transmission data modulated by the transmission data modulation unit 243, generating base station downlink signals as transmission signals transmitted from each antenna 25. The transmission unit 244 transmits the generated base station downlink signals from the antennas 25 via MIMO (step S414).

[0119] Control unit 242a determines whether the current time has exceeded the communication time period detected in step S411 (step S415). If the control unit 242a determines that the time period has not been exceeded (step S415: No), it repeats the process from step S412; if the control unit determines that the time period has been exceeded (step S415: Yes), it ends the process. Furthermore, control unit 242a can also end the process if all terminal data to be sent to the mobile relay station 2a at the communication destination has been transmitted.

[0120] Each antenna station 41 of base station 4a converts the downlink signal received from mobile relay station 2a into an electrical signal, and outputs the received signal obtained after conversion to the receiving unit 42a (step S421). Control unit 422a instructs the summing unit 423 on the receiving weight corresponding to the current time (step S422). The summing unit 423 multiplies the received signal of each antenna station 41 by the receiving weight indicated by control unit 422a. The summing unit 423 adds the received signals after multiplication by the weights, and outputs the summed received signal to base station signal receiving processing unit 43 (step S423). Base station signal receiving processing unit 43 demodulates the received signal input from receiving unit 42a and decodes the demodulated received signal to obtain the terminal transmission data (step S424).

[0121] Furthermore, when mobile relay station 2a has only one antenna 25, mobile relay station 2a does not perform the processing in step S412. Then, in step S414, the transmission data modulation unit 243 modulates the transmission data of the serial signal, and the transmission unit 244 transmits the base station downlink signal obtained by setting the modulated transmission data from antenna 25. In addition, when base station 4a has only one antenna station 41, the receiving unit 42a does not perform the processing in steps S422 and S423, but outputs the received signal to the base station signal receiving and processing unit 43.

[0122] Additionally, mobile relay station 2a can also receive uplink signals from base station 4a. In this case, as described above, the overall transmission capacity between each mobile relay station 2a and the antenna station 41 of base station 4a is calculated, and the mobile relay station 2a with the largest uplink transmission capacity is selected as the communication destination at each time.

[0123] Figure 10 This is a block diagram showing the configuration of mobile relay station 2a and base station 4a when mobile relay station 2a receives uplink signals from base station 4a. Figure 10 In this paper, only the functional parts related to the transmission and reception of uplink signals of the base station are shown.

[0124] Base station 4a includes a transmitting unit 44a. The transmitting unit 44a includes a storage unit 441a, a control unit 442a, a transmitting data modulation unit 443, and a weight multiplication unit 444.

[0125] Storage unit 441a pre-stores the mobile relay station 2a of the communication destination and the transmission weight for each transmission time. The transmission weight for each transmission time is calculated based on the orbital information of the LEO satellite carrying the mobile relay station 2a of the communication destination and the position of each antenna station 41 at that transmission time.

[0126] The control unit 442a reads the transmission weights of the transmission signals obtained from each antenna station 41 at each transmission time from the storage unit 441a, and instructs the read transmission weights to the weight multiplication unit 444. The transmission data modulation unit 443 modulates the transmission data transmitted to the mobile relay station 2a into parallel signals transmitted from each antenna station 41. The weight multiplication unit 444 uses the transmission weights instructed by the control unit 442a to weight the modulated parallel signals, generating base station uplink signals transmitted from each antenna station 41. The weight multiplication unit 444 outputs the generated base station uplink signals to the corresponding antenna station 41. The antenna station 41 wirelessly transmits the base station uplink signals.

[0127] The base station communication unit 24a of mobile relay station 2a includes a storage unit 241a, a control unit 242a, a receiving unit 245, and a receiving processing unit 246. As described above, the storage unit 241a stores communication destination base station information that associates a communication time period with a base station 4a whose communication destination is itself, the mobile relay station, during that communication time period. Furthermore, the storage unit 241a stores the reception weight of the base station uplink signal received by each antenna 25 from the communication destination base station 4a at each reception time. The reception weight at each reception time is calculated based on the orbital information of the LEO satellite and the positions of each antenna station 41 of the communication destination base station 4a.

[0128] The control unit 242a reads the reception weights of each antenna 25 at each reception time from the storage unit 241a and instructs the receiving unit 245 on the read reception weights. The receiving unit 245 receives the uplink signals of the base station through each antenna 25, and performs summation after multiplying the received signals received by each antenna 25 by the reception weights instructed by the control unit 242a. The receiving processing unit 246 demodulates and decodes the received signals summed by the receiving unit 245 to obtain the transmitted data sent by the base station 4a.

[0129] In addition to the following aspects, the processing of wireless communication system 1a in the case of transmitting base station uplink signals from base station 4a is also related to... Figure 5 The processing of the first embodiment shown is the same. That is, the base station 4a does not perform the processing of step S211, but selects all antenna stations 41 instead of the subset of antenna stations 41.

[0130] Furthermore, when base station 4a has only one antenna station 41, base station 4a does not perform steps S221 and S222. The transmission data modulation unit 443 modulates the encoded transmission data and outputs the base station uplink signal obtained after setting the modulated transmission data to antenna station 41. Additionally, when mobile relay station 2a has only one antenna 25, mobile relay station 2a does not perform steps S222 and S223. Then, in step S224, the receiving processing unit 246 demodulates and decodes the base station uplink signal received by the receiving unit 245 through antenna 25.

[0131] Furthermore, the control unit 442a can also generate information stored in the storage unit 421a of the base station 4a at any time. Additionally, the base station 4a can also transmit the information stored in the storage unit 241a of the base station 4a to the mobile relay station 2a via the base station uplink signal.

[0132] Alternatively, the processing of the first or second implementation method can be performed between the base station 4a and the mobile relay station 2a at the communication destination.

[0133] (Fourth Implementation)

[0134] In the first and second embodiments described above, the selection or switching of the receiving antenna station is performed in the base station. In this embodiment, in addition to the selection or switching of the receiving antenna station in the base station, the selection or switching of the transmitting antenna is also performed in the mobile relay station. Hereinafter, this embodiment will be described focusing on the differences from the first embodiment.

[0135] Figure 11 This is a diagram showing an outline of a wireless communication system 1b according to a fourth embodiment. The wireless communication system 1b includes a mobile relay station 2b, a terminal station 3, and a base station 4b. The number of each of the mobile relay station 2b, terminal station 3, and base station 4b in the wireless communication system 1b is arbitrary, but it is envisioned that the number of terminal stations 3 is many.

[0136] Mobile relay station 2b includes one or more antennas 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 24, and multiple antennas 25. In this embodiment, the example described is the case where mobile relay station 2b has three or more antennas 25, and antenna selection and switching are performed when mobile relay station 2b and base station 4b conduct wireless communication via MIMO. For example, when mobile relay station 2b uses two antennas 25 for wireless communication with base station 4b via MIMO, two antennas 25 are selected from the three or more antennas 25 provided by mobile relay station 2b. The antennas 25 are switched within mobile relay station 2b so that communication is performed using the selected two antennas 25.

[0137] The base station communication unit 24b transmits data to the base station 4b via a transmitting terminal. The base station communication unit 24b includes a storage unit 241b, a control unit 242b, a data transmission modulation unit 243, and a transmission unit 244.

[0138] The storage unit 241b pre-stores the transmission weight of the base station downlink signal transmitted from each antenna 25 at each transmission time. Furthermore, the storage unit 241b stores information about the antennas 25 used at each time (hereinafter referred to as "mobile relay station antenna utilization information"). The mobile relay station antenna utilization information is information that associates, for example, the number of antennas 25 used with the time.

[0139] Based on the channel capacity (transmission capacity) between the mobile relay station 2b and the base station 4b, the control unit 242b determines at each time the combination (hereinafter referred to as "the combination of antennas used") of the antennas 25 provided by the mobile relay station 2b and the antenna stations 41 provided by the base station 4b used in the communication between the mobile relay station 2b and the base station 4b. The combination of antennas used here refers to the combination of the number of antennas 25 and antenna stations 41 used in the communication between the mobile relay station 2b and the base station 4b. More specifically, the combination of antennas used is the combination of the number of antennas 25 and the number of antenna stations 41 used at each time.

[0140] The control unit 242b selects the antenna 25 from the antennas 25 of the mobile relay station 2b for communication with the base station 4b, based on the determined combination of antennas to be used at each time. The control unit 242b switches between multiple antennas 25 to enable communication using the selected antenna 25. A switch can also be used during antenna 25 switching. The control unit 242b instructs the data modulation unit 243 to transmit data. The control unit 242b instructs the transmission unit 244 to specify the transmission weight for each transmission time read from the storage unit 241.

[0141] Base station 4b includes multiple antenna stations 41, a receiving unit 42b, and a base station signal receiving and processing unit 43. The receiving unit 42b aggregates base station downlink signals received from the multiple antenna stations 41. For example, the receiving unit 42b aggregates base station downlink signals received using a number of antenna stations 41 pre-notified by mobile relay station 2b. The receiving unit 42b includes a storage unit 421b, a control unit 422b, and an adder unit 423.

[0142] Storage unit 421b pre-stores information on the antenna station 41 used at each time (hereinafter referred to as "base station antenna information"), transmission capacity information, and reception weight for each reception time. Base station antenna information is information that associates, for example, the number of antenna stations 41 used with time.

[0143] Based on the base station antenna information and transmission capacity information notified by the mobile relay station 2b, the control unit 422b selects the antenna station 41 used in communication with the mobile relay station 2b from the antenna stations 41 possessed by the base station 4b. For example, at each reception time, the control unit 422b selects the number of antenna stations 41 included in the base station antenna information in descending order of transmission capacity.

[0144] The control unit 422b instructs the summing unit 423 as if summing the received signals of the selected antenna station 41. Furthermore, the control unit 422b reads the reception weight of each received signal at each reception time from the storage unit 421 and instructs the summing unit 423 on the read reception weight.

[0145] Figure 12 This is a diagram showing an example of the configuration of antenna 25 configured in mobile relay station 2b.

[0146] exist Figure 12 In this context, M represents the total number of antennas 25 configured in mobile relay station 2b, and N represents the number of antennas 25 used in mobile relay station 2b for communication with base station 4b. Furthermore, in Figure 12 In the diagram, the antenna 25 used in communication with base station 4b is designated as 25-1, and the antenna 25 not used in communication with base station 4b is designated as 25-2.

[0147] Figure 12 (A) shows the configuration of the antennas 25 when the total number of antennas 25 configured in the mobile relay station 2b is 2 and the number of antennas 25 used in the mobile relay station 2b is 2. Figure 12 (B) shows the configuration of the antennas 25 when the total number of antennas 25 configured in the mobile relay station 2b is 3 and the number of antennas 25 used in the mobile relay station 2b is 2. Figure 12 (C) shows the configuration of the antennas 25 when the total number of antennas 25 configured in the mobile relay station 2b is 4 and the number of antennas 25 used in the mobile relay station 2b is 2. Figure 12 (D) shows the configuration of the antennas 25 when the total number of antennas 25 configured in the mobile relay station 2b is 6 and the number of antennas 25 used in the mobile relay station 2b is 2.

[0148] like Figure 12 As shown, the antennas 25 are arranged at intervals of 2π / M. Furthermore, M is the total number of antennas 25.

[0149] Figure 13 This represents the analysis results of channel capacity when MIMO communication occurred between mobile relay station 2b and base station 4b. Figure 13 In the diagram, the horizontal axis represents time, and the vertical axis represents channel capacity. Figure 13 (A) indicates that in Figure 12 Analysis results of channel capacity under the antenna 25 configuration shown in (A). Figure 13 (B) indicates that in Figure 12 (B) shows the channel capacity analysis results for the antenna 25 configuration. Figure 13 (C) indicates that in Figure 12 Analysis results of channel capacity under the antenna 25 configuration shown in (C).

[0150] like Figure 13 As shown, as the total number of antennas M of antenna 25 increases, the result is obtained that "the channel capacity (C_MIMO) when MIMO is applied gradually approaches the maximum value (C3) = the interference time decreases".

[0151] The following shows Figure 13 Details of the general example shown.

[0152] C_MIMO: Channel capacity when MIMO is applied (after combinatorial optimization)

[0153] C1: Channel capacity when signals are completely separated (channel matrix includes only diagonal components)

[0154] C2: Minimum channel capacity (channel correlation 0)

[0155] C3: Maximum channel capacity (channel correlation 1)

[0156] C_MIMO_AB: Channel capacity when antennas A and B are selected (refer to...) Figure 13 (D)

[0157] C_MIMO_BC: Channel capacity when antennas B and C are selected (refer to...) Figure 13 (D)

[0158] C_MIMO_CD: Channel capacity when antennas C and D are selected (refer to...) Figure 13 (D)

[0159] C_MIMO_DA: Channel capacity when antennas D and A are selected (refer to...) Figure 13 (D)

[0160] C_MIMO_AC, C_MIMO_CA: Channel capacity when antennas A and C are selected (refer to...) Figure 13 (D)

[0161] C_MIMO_BD: Channel capacity when antennas B and D are selected (refer to...) Figure 13 (D)

[0162] Figure 14 This is a graph showing the analysis results of the average time and channel capacity that each antenna can utilize for MIMO per cycle.

[0163] exist Figure 14 In the middle, Figure 13The time period exceeding the "channel capacity (C1) when the signal is completely separated" is defined as the time when MIMO is applicable. SISO is set to transmit via one antenna, and MIMO is set to transmit via two antennas, with the transmission power of one antenna fixed. For example... Figure 14 As shown, we can obtain the result that "as the total number of antennas M increases, the applicable MIMO time and average channel capacity increase, while the interference time decreases."

[0164] The following shows Figure 14 Details of the general example shown.

[0165] T_MIMO: The total number of time periods during the entire visible time of the week where C_MIMO > C1.

[0166] T_total: The total of all visible time throughout the week.

[0167] C_MIMO_Ave.: The average channel capacity across all visible paths during a cycle when MIMO (transmitted from two antennas) is implemented.

[0168] C_SISO_Ave.: The average channel capacity across all visible paths during one week of SISO (when transmitted from a single antenna).

[0169] Explain the operation of wireless communication system 1b.

[0170] Figure 15 This is a flowchart illustrating the process by which mobile relay station 2b determines the combination of antennas to utilize. Furthermore, in Figure 15 The following processing is explained: Before mobile relay station 2b begins communication to send data obtained from terminal station 3 to base station 4b, mobile relay station 2b determines the antenna combination to be used in accordance with the visibility time. The visibility time can be calculated based on the track information of mobile relay station 2b and the location information of base station 4b, or it can be predetermined.

[0171] The control unit 242b first derives the total number of antenna combinations X based on the following formula (1) (step S501).

[0172] [Number 1]

[0173]

[0174] In equation (1), M s M represents the number of mobile relay stations 2b. t M represents the number of antennas (e.g., antenna 25) used in transmission. rThis indicates the number of antennas (e.g., antenna station 41) used in reception, and N represents the stream number (N=2 in the case of 2×2 MIMO). In the example of this embodiment, there is one mobile relay station 2b, therefore M s The number becomes 1. However, in the case where the wireless communication system 1b has multiple mobile relay stations 2b, the number of mobile relay stations 2b becomes M. s The value of .

[0175] Next, the control unit 242b assigns a number to each combination utilizing antennas (step S502). For example, the control unit 242b sequentially assigns numbers to each combination utilizing antennas as x=1, 2, ..., X. As an example, the combination of the number of mobile relay stations 2b "1", the number of antennas 25 "2", and the number of antenna stations 41 "2" is sequentially assigned as "1". The control unit 242b may also store the combinations utilizing antennas in association with their numbers in the storage unit 241b.

[0176] Next, the control unit 242b sets the initial value of the visible time t to 1 (step S503). Here, the visible time t represents the time when the mobile relay station 2b and the base station 4b can communicate. The control unit 242b predicts the channel matrix (H) and the received SNR (γ) from the track information of the mobile relay station 2b at time t (step S504). The control unit 242b uses the predicted channel matrix (H) and the received SNR (γ) to determine the number x(t) of the combination of antennas that will maximize the channel capacity Cx at time t (step S505). For example, the control unit 242b sets the channel capacity Cx as... x An example of optimization is to determine the channel capacity C according to the following equation (2). x The combination of antennas is numbered x(t) to maximize utilization. The parameter used as an indicator can also be any value other than channel capacity. Furthermore, in this specification (and in this embodiment and other embodiments), channel capacity C is used... x An example of optimization is illustrated by using equation (2). The control unit 242b stores information about the number of antennas (e.g., antenna 25) used in transmission in the combination of antennas associated with the determined number x(t) in the storage unit 241b as mobile relay station antenna information.

[0177] [Number 2]

[0178]

[0179] In equation (2), I NThis represents an N×N identity matrix. The control unit 242b selects the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) (step S506). The control unit 242b stores the information of the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) in the storage unit 241b.

[0180] The control unit 242b determines whether t=T (step S507). T represents the end time of the visible time. If t is not t=T (step S507 - No), the control unit 242b adds 1 to the value of t and repeats the processing after step S504 (step S508). In this way, the control unit 242b determines the combination of antennas used for each visible time.

[0181] On the other hand, when t=T (step S507-Yes), the control unit 242b obtains information on the number of receiving antennas (e.g., the number of antenna stations 41) in the combination of antennas used at each visible time. The control unit 242b summarizes the information on the number of receiving antennas (e.g., the number of antenna stations 41) during the obtained visible time (t=1 to T) and notifies the base station 4b via antenna 25 (step S509).

[0182] Figure 16 This is a flowchart illustrating the process of transmitting base station downlink signals from mobile relay station 2b. Furthermore, Figure 16 The processing is performed when it becomes possible to communicate with base station 4b (visible time t=1).

[0183] The control unit 242b of the mobile relay station 2b selects the antenna 25 to be used in transmission by referring to the mobile relay station antenna information stored in the storage unit 241b (step S601). For example, if the total number of antennas 25 used in transmission at time t is 2, and this information is stored in the storage unit 241b as mobile relay station antenna information, the control unit 242b selects 2 antennas 25 from the plurality of antennas 25. The selected antennas 25 can also be based on, for example... Figure 11 The selection is based on the relationship shown. For example, if the total number of antennas 25 used in transmission at time t is 2, then... Figure 11 (A) In this way, the control unit 242b can also select two antennas 25 such that the angle of the two antennas 25 is π. Furthermore, when there are multiple combinations of antennas 25 such that the angle of the two antennas 25 is π, the control unit 242b can also randomly select one combination of antennas 25 from the multiple combinations. The control unit 242b switches the antennas 25 so that the selected antenna 25 is used to transmit the base station downlink signal.

[0184] The control unit 242b reads the transmission weight corresponding to the current time t from the storage unit 241b and instructs it to the transmission unit 244 (step S602). The transmission data modulation unit 243 receives the instruction from the control unit 242b and reads the terminal transmission data stored in the data storage unit 23 as the transmission data (step S603).

[0185] The transmission data modulation unit 243 encodes the read transmission data at the error correction coding rate at time t, and after performing parallel conversion on the encoded transmission data, modulates it using the modulation scheme at time t. The error correction coding rate and modulation scheme at each time are stored in the control unit 242b. The transmission unit 244 uses the transmission weights indicated by the control unit 242 to weight the transmission data modulated by the transmission data modulation unit 243, generating a base station downlink signal as a transmission signal transmitted from the selected antenna 25. The transmission unit 244 transmits the generated base station downlink signals from the selected antenna 25 via MIMO (step S604).

[0186] Control unit 242b determines whether the current time t becomes time T (step S605). If the current time t becomes time T (step S605 - Yes), mobile relay station 2b terminates. Figure 16 The processing.

[0187] On the other hand, if the current time t has not become time T (step S605 - No), the control unit 242b re-references the time to select the antenna 25 used in transmission that corresponds to the current time (step S606).

[0188] As time gradually passes, the time after mobile relay station 2b transmits the base station downlink signal to base station 4b becomes different from the time when antenna 25 was last selected. Therefore, control unit 242b takes the time after the base station downlink signal transmission as the current time and selects antenna 25 again for transmission. Here, the time after the base station downlink signal transmission could also be the time when the processing in step S604 has ended. Furthermore, if the same antenna 25 is selected as before, control unit 242b does not need to switch antenna 25. Afterwards, mobile relay station 2b executes the processing after step S602.

[0189] Figure 17 This is a flowchart illustrating the process by which base station 4b receives downlink signals from mobile relay station 2b. Furthermore, Figure 17 The processing is performed when communication with mobile relay station 2b becomes possible (visible time t=1). It is configured as follows: In Figure 17 When the processing begins, the base station 4b's storage unit 421b stores the base station's antenna information from time t to T.

[0190] Each antenna station 41 of base station 4b outputs a received signal obtained by converting the downlink signal received from mobile relay station 2b into an electrical signal to receiving unit 42b (step S611). Control unit 422b, referring to the base station antenna information and transmission capacity information stored in storage unit 421b, selects a subset of all antenna stations 41 that are being used in reception at the current time t (step S612). Control unit 422b instructs summing unit 423 as if the received signal from the selected subset of antenna stations 41 were being used in reception. Furthermore, control unit 422b reads the reception weight corresponding to the current time t from storage unit 421 and instructs summing unit 423 of the read reception weight (step S613).

[0191] The summing unit 423 selects the received signals of each antenna station 41 as indicated by the control unit 422b during reception, and multiplies the selected received signals by the reception weights indicated by the control unit 422b. The summing unit 423 adds the received signals after multiplying by the reception weights (step S614). The base station signal receiving processing unit 43 demodulates the added received signals and decodes the demodulated received signals to obtain the terminal transmission data (step S615).

[0192] Control unit 422b determines whether the current time t becomes time T (step S616). If the current time t becomes time T (step S616 - Yes), base station 4b ends. Figure 17 The processing.

[0193] On the other hand, if the current time t does not become time T (step S616 - No), the control unit 422b re-references the time to select the antenna 25 used in reception corresponding to the current time (step S617).

[0194] As time gradually passes, the time after base station 4b receives the downlink signal is different from the time when antenna station 41 was selected last time. Therefore, control unit 422b uses the time after receiving the downlink signal as the current time and selects antenna station 41 again for reception. Here, "after receiving the downlink signal" could be the time when the processing in step S611 has ended, or it could be the time when the processing in step S615 has ended. Furthermore, if the same antenna station 41 is selected as before, control unit 422b does not need to instruct the summing unit 423. Afterwards, base station 4b executes the processing after step S611.

[0195] According to the embodiments described above, based on the transmission capacity between mobile relay station 2b and base station 4b, the number of antennas 41 used in receiving at base station 4b is determined, as well as the number of antennas 25 used in transmitting via mobile relay station 2b. This allows for the determination of antenna combinations with higher transmission capacity. As a result, more efficient communication is possible than in the embodiments described above.

[0196] (A variation of the fourth embodiment)

[0197] The control unit 242b can also be configured to select the antenna 25 used in communication with the base station 4b using transmission capacity information. In this configuration, the transmission capacity information is further stored in the storage unit 241b. The transmission capacity information stored in the storage unit 241b shows the downlink transmission capacity of each antenna 25 at each transmission time. The control unit 242b refers to the transmission capacity information stored in the storage unit 241b and selects a determined number of antennas 25 in descending order of transmission capacity at each transmission time.

[0198] In the fourth embodiment, reception is performed by all antenna stations 41 of base station 4b. In contrast, it can also be configured such that antenna stations 41 switch to receive one at a time according to the time. Hereinafter, the differences from the fourth embodiment will be described in detail.

[0199] The storage unit 421b of base station 4b stores the antenna information used by the base station. Therefore, the control unit 422b replaces... Figure 17 The following processing is performed in accordance with steps S611 and S612. Specifically, the control unit 422b reads information from the storage unit 421b indicating the number of antenna stations 41 currently in use, referring to the base station antenna information. Based on the information indicating the read number of antenna stations 41, the control unit 422b selects antenna stations 41 to be used in reception from the antenna stations 41 possessed by the base station 4b. For example, the control unit 422b refers to the transmission capacity information and selects antenna stations 41 with the number of antennas included in the base station antenna information in descending order of transmission capacity at the current time. The control unit 422b instructs the selected antenna station 41 as if receiving. The control unit 422b may also further instruct unselected antenna stations 41 to stop receiving. The antenna station 41 instructed as if receiving receives receives the base station downlink signal from the mobile relay station 2b and outputs the received signal obtained by converting the received base station downlink signal into an electrical signal to the receiving unit 42b.

[0200] By configuring it as described above, it is not a problem to operate the antenna station 41 that is not needed during reception, thus suppressing power consumption.

[0201] (Fifth Implementation)

[0202] In the fourth embodiment, the mobile relay station determines the combination of antennas to be used in accordance with the available time before communication begins for transmitting data obtained from the terminal station to the base station. In this embodiment, the configuration in which the mobile relay station determines the combination of antennas to be used at any time during (real-time) communication for transmitting data obtained from the terminal station to the base station will be described. Hereinafter, this embodiment will be described focusing on the differences from the fourth embodiment.

[0203] The configuration of the wireless communication system in this embodiment and Figure 10 The wireless communication system 1b of the fourth embodiment shown is similar. As a difference between this embodiment and the fourth embodiment, in the fourth embodiment, the mobile relay station 2b summarizes and determines the combination of antennas corresponding to the visible time before communication begins; in contrast, in this embodiment, the mobile relay station 2b determines the combination of antennas at different timings after communication begins. Furthermore, the mobile relay station 2b performs [further steps] in advance. Figure 15 The processing results of steps S501 and S502 shown are stored in the storage unit 241b in advance.

[0204] Figure 18 This is a flowchart illustrating the process by which mobile relay station 2b decides to utilize a combination of antennas and transmit the base station downlink signal. Furthermore, Figure 18 The processing is performed when it becomes possible to communicate with base station 4b (visible time t=1).

[0205] Control unit 242b predicts the channel matrix (H) and received SNR (γ) from the track information of mobile relay station 2b at time t (e.g., t=1) (step S701). Based on the above equation (2) and the number of each combination of utilized antennas stored in storage unit 241b, control unit 242b determines the channel capacity C at time t. x The combination of antennas that maximizes utilization is determined by the number x(t) (step S702). The control unit 242b stores the information of the number of antennas (e.g., antenna 25) used in transmission in the combination of antennas associated with the determined number x(t) in the storage unit 241b as mobile relay station utilization antenna information.

[0206] Control unit 242b selects the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) (step S703). Control unit 242b stores the information of the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) in storage unit 241b. Control unit 242b notifies base station 4b of the number of receiving antennas at time t via antenna 25 (step S704).

[0207] Subsequently, the control unit 242b, referring to the mobile relay station antenna information stored in the storage unit 241b, selects the antenna 25 to be used in transmission at time t (step S705). The control unit 242b reads the transmission weight corresponding to the current time t from the storage unit 241b and instructs it to the transmission unit 244 (step S706). The transmission data modulation unit 243 receives the instruction from the control unit 242b and reads the terminal transmission data stored in the data storage unit 23 as the transmission data (step S707).

[0208] The transmission data modulation unit 243 encodes the read transmission data at an error correction coding rate at time t, and after performing parallel conversion on the encoded transmission data, modulates it using the modulation scheme at time t. The transmission unit 244 uses the transmission weights indicated by the control unit 242 to weight the transmission data modulated by the transmission data modulation unit 243 to generate a base station downlink signal as a transmission signal transmitted from the selected antenna 25. The transmission unit 244 transmits the generated base station downlink signals from the selected antenna 25 via MIMO (step S708).

[0209] Control unit 242b determines whether the current time t becomes time T (step S709). If the current time t becomes time T (step S709 - Yes), mobile relay station 2b terminates. Figure 18 The processing.

[0210] On the other hand, if the current time t has not become time T (step S709 - No), the control unit 242b re-references the time to confirm the current time t (step S710). Afterwards, the mobile relay station 2b executes the processing after step S701.

[0211] As described above, in the fifth embodiment, the mobile relay station 2b selects the antenna 25 used in transmission in real time and notifies the base station 4b of the number of antenna stations 41 used in reception.

[0212] Furthermore, the processing of base station 4b is the same as in the fourth embodiment, except that it is notified by mobile relay station 2b of the number of antenna stations 41 used in reception and selects the antenna stations 41 used in reception based on the notified information.

[0213] According to the embodiments described above, the mobile relay station 2b can determine in real time the number of antenna stations 41 used in receiving at the base station 4b and the number of antennas 25 used in transmitting via the mobile relay station 2b. Therefore, compared to the case in the fourth embodiment where the mobile relay station 2b predetermines the combination of antennas used corresponding to the visible time, it can determine the combination of antennas used more in response to changes in the communication environment. Thus, in a constantly changing communication environment, it is possible to determine a combination of antennas with higher transmission capacity.

[0214] (A variation of the fifth embodiment)

[0215] In the fifth embodiment, the control unit 242b can also be configured to select the antenna 25 used in communication with the base station 4b using transmission capacity information. In this configuration, the transmission capacity information is further stored in the storage unit 241b. The control unit 242b refers to the transmission capacity information stored in the storage unit 241b and selects a determined number of antennas 25 in descending order of transmission capacity at each transmission time.

[0216] In the fifth embodiment, reception is performed by all antenna stations of base station 4b. In contrast, it can also be configured such that antenna stations 41 switch to receive one by one according to time. Hereinafter, the differences from the fifth embodiment will be described in detail.

[0217] Base station 4b stores information on the number of receiving antennas (e.g., the number of antenna stations 41) at time t, which is notified in real time by mobile relay station 2b, as antenna information used by the base station. Therefore, whenever mobile relay station 2b notifies the number of receiving antennas at any given time, control unit 422b selects an antenna station 41 from the antenna stations 41 possessed by base station 4b for use in reception, based on the information indicating the number of antenna stations 41 included in the notified information. Control unit 422b instructs the selected antenna station 41 as if performing reception. Control unit 422b may also further instruct unselected antenna stations 41 to stop receiving. The antenna station 41 instructed as if performing reception receives the base station downlink signal from mobile relay station 2b and outputs the received signal obtained by converting the received base station downlink signal into an electrical signal to receiving unit 42b.

[0218] By configuring it as described above, even in real-time communication, it is not a problem to operate the antenna station 41, which is not needed in receiving, thus suppressing power consumption.

[0219] (Sixth Implementation Method)

[0220] In the fourth embodiment described above, the mobile relay station determines the combination of antennas used for each visible time. In this embodiment, a device installed on the ground determines the combination of antennas used for each visible time. Hereinafter, this embodiment will be described focusing on the differences from the fourth embodiment.

[0221] Figure 19 This is a diagram showing an outline of a wireless communication system 1c according to a sixth embodiment. The wireless communication system 1c includes a mobile relay station 2c, a terminal station 3, a base station 4b, and an antenna number-determining station 5. The number of each of the mobile relay station 2c, terminal station 3, and base station 4b in the wireless communication system 1c is arbitrary, but it is envisioned that the number of terminal stations 3 is many.

[0222] The antenna number determining station 5 determines the combination of antennas to be used at each visible time. The antenna number determining station 5 includes a storage unit 51, a control unit 52, a transmission unit 53, and antennas 54.

[0223] The storage unit 51 pre-stores track information and the location information of base station 4b.

[0224] The control unit 52 determines the combination of antennas to be used at each time based on the channel capacity (transmission capacity) between the mobile relay station 2c and the base station 4b. Furthermore, the control unit 52 selects information on the modulation scheme and error correction coding rate of the antenna combination to be used.

[0225] The control unit 52 can also obtain channel capacity information from the mobile relay station 2c. In addition, the control unit 52 can also calculate the overall transmission capacity between the mobile relay station 2c and the antenna stations 41 of the base station 4b at each time based on the track information of the mobile relay station 2c and the wireless communication frequency of each antenna station 41.

[0226] The transmitting unit 53 transmits transmission information to the mobile relay station 2c via the antenna station 54. The transmission information includes, in accordance with the visible time, information on the combination of antennas determined by the control unit 52, as well as information on the modulation scheme and error correction coding rate in the combination of antennas.

[0227] The mobile relay station 2c includes one or more antennas 21, a terminal communication unit 22c, a data storage unit 23, a base station communication unit 24c, and multiple antennas 25. In this embodiment, the example is described as follows: the mobile relay station 2c has three or more antennas 25, and the antennas 25 are switched when the mobile relay station 2c and the base station 4b are communicating wirelessly via MIMO.

[0228] The terminal communication unit 22c includes a receiving unit 221c, a terminal signal receiving and processing unit 222c, and a data recording unit 223. The receiving unit 221c receives terminal uplink signals transmitted by each terminal station 3 via antenna 21. Furthermore, the receiving unit 221c receives transmission information transmitted from the antenna number determining station 5.

[0229] The terminal signal receiving and processing unit 222c performs uplink signal receiving and processing. The terminal signal receiving and processing unit 222c outputs the transmission information received by the receiving unit 221c to the base station communication unit 24c.

[0230] The base station communication unit 24c transmits data to the base station 4b via a transmitting terminal. The base station communication unit 24c includes a storage unit 241c, a control unit 242c, a data modulation unit 243, and a transmitting unit 244.

[0231] The storage unit 241c pre-stores the transmission weights of the base station downlink signals transmitted from each antenna 25 at each transmission time. Furthermore, the storage unit 241c stores information about the antenna combinations included in the transmission information, as well as information about the modulation scheme and error correction coding rate within the antenna combinations.

[0232] Based on information about the combinations of antennas used at each moment stored in the storage unit 241c, the control unit 242c selects the antenna 25 to be used in communication with the base station 4b from the antennas 25 of the mobile relay station 2c. The control unit 242c switches between the multiple antennas 25 so that communication is performed using the selected antenna 25. The control unit 242c instructs the transmission data modulation unit 243 to send data from the terminal.

[0233] The control unit 242c instructs the transmission unit 244 on the transmission weight for each transmission moment read from the storage unit 241c. Furthermore, the control unit 242c notifies the base station 4b of the number of antenna stations 41 used in reception, from the information on the combination of antennas used for each transmission moment determined by the number of antennas at station 5.

[0234] The transmission data modulation unit 243 receives an instruction from the control unit 242c and reads the terminal transmission data stored in the data storage unit 23 as transmission data. The transmission data modulation unit 243 encodes the read transmission data at an error correction coding rate at time t, performs parallel conversion on the encoded transmission data, and then modulates it using a modulation scheme at time t.

[0235] Explain the operation of wireless communication system 1c.

[0236] Figure 20 This is a flowchart illustrating the process by which the number of antennas is determined at station 5, and the combination of antennas to be used is determined. Furthermore, in Figure 20The process of determining the number of antennas at station 5 and the corresponding combination of antennas to utilize before communication begins between mobile relay station 2c and base station 4b is explained.

[0237] The control unit 52, which determines the number of antennas at station 5, first derives the total number of antenna combinations X based on the above formula (1) (step S801). Next, the control unit 52 assigns a number to each antenna combination (step S802). The control unit 52 may also store the antenna combinations in the storage unit 51 in association with their numbers. Next, the control unit 52 sets the initial value of the visible time t to 1 (step S803).

[0238] The control unit 52 uses the track information of the mobile relay station 2b at time t stored in the storage unit 51 to predict the channel matrix (H) and the received SNR (γ) (step S804). Based on the above equation (2), the control unit 52 determines the channel capacity C at time t. x Maximize the use of the antenna combination numbered x(t) (step S805).

[0239] The control unit 52 selects the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) (step S806). The control unit 52 stores the information of the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) in the storage unit 51.

[0240] The control unit 52 determines whether t=T (step S807). If t is not T (step S807 - No), the control unit 52 adds 1 to the value of t and repeats the processing after step S804 (step S808). In this way, the control unit 52 determines the combination of antennas used for each visible time.

[0241] On the other hand, when t=T (step S807-Yes), the control unit 52 notifies the mobile relay station 2c via the antenna 54 of the information on the combination of antennas used during the visible time (t=1 to T) as well as the information on the modulation scheme and error correction coding rate in the combination of antennas used (step S809).

[0242] According to the implementation described above, the antenna number determining station 5, based on the communication capacity between mobile relay station 2c and base station 4b, selects antenna station 41 used for receiving in base station 4b, and also determines antenna 25 used by mobile relay station 2c for transmitting. Antenna number determining station 5 notifies mobile relay station 2c of the determined combination of antennas used at each time. Therefore, it is unnecessary to determine the combination of antennas used within mobile relay station 2c. Thus, the processing load on mobile relay station 2c can be reduced.

[0243] Furthermore, in mobile relay station 2c, the number of antennas 25 used in transmission is determined based on information about the combination of antennas used, which is determined by the number of antennas. Mobile relay station 2c notifies base station 4b of the information about the antenna station 41 used in reception. Thus, communication between mobile relay station 2c and base station 4b can be achieved through a combination of antennas with higher transmission capacity. As a result, efficient communication is possible.

[0244] (A variation of the sixth embodiment)

[0245] The mobile relay station 2c in the sixth embodiment can also be modified in the same way as the mobile relay station 2b in the fourth embodiment.

[0246] The base station 4b in the sixth embodiment can also be configured in the same way as the base station 4b in the fourth embodiment, so that antenna station 41 other than antenna station 41 used in reception stops receiving.

[0247] (Seventh Implementation)

[0248] In the sixth embodiment, the number of antennas is determined before communication between the mobile relay station and the base station begins, and the combination of antennas used is determined accordingly to the visible time. In this embodiment, the configuration in which the number of antennas is determined at any time during the period (real-time) of communication between the mobile relay station and the base station will be described. Hereinafter, this embodiment will be described focusing on the differences from the sixth embodiment.

[0249] The configuration of the wireless communication system in this embodiment and Figure 19 The wireless communication system 1c of the sixth embodiment shown is similar. As a difference between this embodiment and the sixth embodiment, in the sixth embodiment, the antenna number determining station 5 summarizes and determines the combination of antennas corresponding to the visible time before communication begins. In contrast, in this embodiment, the antenna number determining station 5 determines the combination of antennas at different timings after communication begins. Furthermore, the antenna number determining station 5 performs this process in advance... Figure 20 The processing results of steps S801 and S802 shown are stored in the storage unit 51 in advance.

[0250] Figure 21 This is a flowchart illustrating the process by which station 5 determines the combination of antennas to be used in order to decide the number of antennas. Furthermore, Figure 21 The processing is performed when mobile relay station 2c becomes capable of communicating with base station 4b (visible time t=1).

[0251] Control unit 52 predicts the channel matrix (H) and received SNR (γ) from the track information of mobile relay station 2c at time t (e.g., t=1) stored in storage unit 51 (step S901). Based on the above equation (2) and the number of each combination of utilization antennas stored in storage unit 51, control unit 52 determines the channel capacity C at time t. x The combination of antennas is maximized (step S902). Therefore, the control unit 52 determines at time t the combination of the number of antennas 25 used by the mobile relay station 2c in transmission and the number of antennas 41 used by the base station 4b in reception.

[0252] Control unit 52 selects the modulation scheme and error correction coding rate in the antenna combination associated with the determined number x(t) (step S903). Control unit 52 notifies mobile relay station 2c of transmission information including information on the antenna combination at time t and information on the modulation scheme and error correction coding rate in the antenna combination via antenna 54 (step S904).

[0253] Control unit 52 determines whether the current time t becomes time T (step S909). If the current time t becomes time T (step S905 - Yes), the antenna quantity determination station 5 ends. Figure 21 The processing.

[0254] On the other hand, if the current time t has not become time T (step S905 - No), the control unit 52 re-references the time to confirm the current time t (step S906). Afterwards, the antenna quantity determination station 5 executes the processing after step S901.

[0255] As described above, in the seventh embodiment, the antenna quantity determining station 5 notifies the mobile relay station 2c in real time of the combination of the antennas used in transmission in the mobile relay station 2c and the antenna stations used in reception in the base station 4b.

[0256] Figure 22 This is a flowchart illustrating the process of transmitting base station downlink signals from mobile relay station 2c. Furthermore, Figure 22 The processing is performed when it becomes possible to communicate with base station 4b (visible time t=1).

[0257] Terminal communication unit 22c receives transmission information at time t (e.g., t=1) from antenna number determining station 5 (step S911). Terminal communication unit 22c outputs the received transmission information to base station communication unit 24c. Control unit 242c of base station communication unit 24c stores information on the combination of antennas used, as well as the modulation scheme and error correction coding rate in the combination of antennas used, included in the received transmission information in storage unit 241c. Control unit 242c notifies base station 4b via antenna 25 of the information on the number of antennas used in reception at time t in the information on the combination of antennas used (step S912).

[0258] The control unit 242c selects antenna 25 for transmission at time t based on the obtained information on the combination of antennas used (step S913). The control unit 242c reads the transmission weight corresponding to the current time t from the storage unit 241b and instructs it to the transmission unit 244 (step S914). The transmission data modulation unit 243 receives the instruction from the control unit 242c and reads the terminal transmission data stored in the data storage unit 23 as the transmission data (step S915).

[0259] The transmission data modulation unit 243 encodes the read transmission data at an error correction coding rate at time t, and after performing parallel conversion on the encoded transmission data, modulates it using the modulation scheme at time t. The transmission unit 244 uses the transmission weights indicated by the control unit 242 to weight the transmission data modulated by the transmission data modulation unit 243 to generate a base station downlink signal as a transmission signal transmitted from the selected antenna 25. The transmission unit 244 transmits the generated base station downlink signals from the selected antenna 25 via MIMO (step S916).

[0260] Control unit 242c determines whether the current time t becomes time T (step S917). If the current time t becomes time T (step S917 - Yes), mobile relay station 2c terminates. Figure 22 The processing.

[0261] On the other hand, if the current time t has not become time T (step S917 - No), the mobile relay station 2c performs the processing after step S911.

[0262] As described above, in the seventh embodiment, the mobile relay station 2c selects the antenna 25 used in transmission in real time based on information from the antenna number determining station 5, and notifies the base station 4b of the number of antenna stations 41 used in reception.

[0263] Furthermore, the processing of base station 4b is the same as in the sixth embodiment, except that it is notified by mobile relay station 2c of the number of antenna stations 41 used in reception and selects the antenna stations 41 used in reception based on the notified information.

[0264] According to the embodiments described above, the antenna quantity determining station 5 can determine in real time the number of antenna stations 41 used in reception at base station 4b and the number of antennas 25 used in transmission via mobile relay station 2c. Therefore, compared to the case where, as in the sixth embodiment, the antenna quantity determining station 5 predetermines the combination of antennas used corresponding to the visible time, it can determine the combination of antennas used more in response to changes in the communication environment. Thus, in a constantly changing communication environment, it is possible to determine a combination of antennas with higher transmission capacity.

[0265] (A variation of the seventh embodiment)

[0266] The mobile relay station 2c in the seventh embodiment can also be modified in the same way as the mobile relay station 2b in the fifth embodiment.

[0267] The base station 4b in the seventh embodiment can also be configured in the same way as the base station 4b in the fifth embodiment, so that antenna station 41 other than antenna station 41 used in reception stops receiving.

[0268] In the fourth to seventh embodiments described above, the transmission of base station downlink signals from the mobile relay station to the base station is mainly explained. In the fourth to seventh embodiments, the mobile relay station can also receive base station uplink signals transmitted from the base station. In this case, the configuration is as follows: the uplink transmission capacity of each antenna 25 and each antenna station 41 of the mobile relay station at each time is calculated in advance. The method for calculating the uplink transmission capacity is omitted since it has already been described in the first embodiment. Hereinafter, the configuration of the mobile relay station receiving base station uplink signals in each of the fourth to seventh embodiments will be described.

[0269] (The configuration of the base station uplink signal reception in the fourth embodiment)

[0270] Figure 23 This is a block diagram showing the configuration of mobile relay station 2b and base station 4b when mobile relay station 2b receives uplink signals from base station 4b. Figure 23 In this paper, only the functional parts related to the transmission and reception of uplink signals of the base station are shown.

[0271] Base station 4b includes a transmitting unit 44b. The transmitting unit 44b includes a storage unit 441b, a control unit 442b, a transmission data modulation unit 443, and a weight multiplication unit 444.

[0272] Storage unit 441b pre-stores transmission capacity information and transmission weights for each transmission time. Furthermore, storage unit 441b stores base station antenna information. It is configured such that the base station antenna information stored in storage unit 441b is pre-transmitted from mobile relay station 2b to base station 4b using the method shown in the fourth embodiment.

[0273] Based on the base station antenna information and transmission capacity information stored in the storage unit 441b, the control unit 442b selects the antenna station 41 used in communication with the mobile relay station 2b from the antenna stations 41 possessed by the base station 4b. For example, at each transmission time, the control unit 422b selects the number of antenna stations 41 included in the base station antenna information in descending order of uplink transmission capacity.

[0274] The control unit 442b instructs the transmission data modulation unit 443 as if transmitting the terminal uplink signal through the antenna station 41 selected at each transmission time. Furthermore, the control unit 442b reads the transmission weight of each antenna station 41 at each transmission time from the storage unit 441b and instructs the read transmission weight to the weight multiplication unit 444.

[0275] The transmission data modulation unit 443 encodes the transmission data sent to the mobile relay station 2b. The transmission data modulation unit 443 modulates the encoded transmission data after converting it into parallel signals transmitted from each antenna station 41 as instructed by the control unit 442b. Furthermore, the configuration is such that the error correction coding rate used in encoding and the modulation scheme used in modulation are determined by the mobile relay station 2b and notified to the base station 4b.

[0276] The weight multiplication unit 444 uses the transmission weights instructed by the control unit 442b to weight the modulated parallel signals, generating base station uplink signals transmitted from each antenna station 41. The weight multiplication unit 444 outputs the generated base station uplink signals to the antenna station 41 selected by the control unit 442b. The antenna station 41 selected by the control unit 442b then wirelessly transmits the base station uplink signals.

[0277] The mobile relay station 2b includes a base station communication unit 24b. The base station communication unit 24b includes a storage unit 241b, a control unit 242b, a receiving unit 245, and a receiving and processing unit 246.

[0278] The storage unit 241b pre-stores the reception weights of the base station uplink signals received by each antenna 25 at each reception time. The reception weights for each reception time are calculated based on the LEO satellite's orbital information and the positions of each antenna station 41. Alternatively, fixed reception weights can be used regardless of the reception time. Furthermore, the storage unit 241b stores antenna information used by the mobile relay station.

[0279] The control unit 242b determines the combination of antennas to be used at each time based on the channel capacity (transmission capacity) between the mobile relay station 2b and the base station 4b. The method for determining the combination of antennas to be used when the mobile relay station 2b receives uplink signals from the base station differs in part from the fourth embodiment. Specifically, in the fourth embodiment, in equation (1) used to derive the total number of antenna combinations X, M... t Let M be the number of antennas 25 used in transmission. r Let M be the number of antenna stations 41 used in the reception. In contrast, in the configuration of mobile relay station 2b receiving the uplink signal from the base station, M in equation (1) is... t Let M be the number of antenna stations 41 used in transmission, such that M r This becomes the number of antennas 25 used in reception.

[0280] The control unit 242b reads the reception weights of each antenna 25 at each reception time from the storage unit 241b and instructs the receiving unit 245 of the read reception weights. The receiving unit 245 receives the uplink signals of the base station through each antenna 25, and after weighting the received signals received by each antenna 25 using the reception weights indicated by the control unit 242b, it performs summation. The receiving processing unit 246 demodulates and decodes the received signals after summation by the receiving unit 245 to obtain the transmission data sent by the base station 4b.

[0281] Figure 24 This is a flowchart illustrating the process of transmitting base station uplink signals from base station 4b. Furthermore, Figure 24 The processing is performed when communication with mobile relay station 2b becomes possible (visible time t=1). It is configured as follows: In Figure 24 When the processing begins, the base station 4b's storage unit 441b stores the base station's antenna information from time t to T.

[0282] The control unit 442b of base station 4b refers to the base station antenna information and transmission capacity information stored in the storage unit 441b, and selects the antenna stations 41 that are being used in transmission at the current time t as a subset (step S621). For example, the control unit 442b selects the number of antenna stations 41 indicated by the base station antenna information as a subset in descending order of uplink transmission capacity.

[0283] The control unit 442b instructs the transmission data modulation unit 443 to transmit the terminal uplink signal through the antenna stations 41 of the subset. Furthermore, the control unit 442b reads the transmission weights of each antenna station 41 of the subset corresponding to the current time from the storage unit 441b and instructs the read transmission weights to the weight multiplication unit 444 (step S622).

[0284] The data modulation unit 443 encodes the data transmitted to the mobile relay station 2b at an error correction coding rate at time t. After converting the encoded data into parallel signals transmitted from each antenna station 41 of the subset, it modulates the data using the modulation scheme at time t.

[0285] The weight multiplication unit 444 uses the transmission weights indicated by the control unit 442b to weight the modulated parallel signals, generating base station uplink signals transmitted from each antenna station 41 of the subset. The weight multiplication unit 444 outputs the generated base station uplink signals to the corresponding antenna station 41. Each antenna station 41 of the subset wirelessly transmits the base station uplink signals (step S623).

[0286] Control unit 442b determines whether the current time t becomes time T (step S624). If the current time t becomes time T (step S624 - Yes), base station 4b ends. Figure 24 The processing.

[0287] On the other hand, if the current time t has not become time T (step S624 - No), the control unit 442b re-references the time to select the antenna station 41 used in transmission corresponding to the current time (step S625). Furthermore, if the same antenna station 41 as last time is selected, the control unit 442b does not perform a switch of antenna station 41. Afterwards, the base station 4b executes the processing from step S622 onwards.

[0288] Figure 25 This is a flowchart illustrating the process by which mobile relay station 2b receives uplink signals from base station 4b. Furthermore, Figure 25 The processing is performed when communication with base station 4b becomes possible (visible time t=1). It is configured as follows: In Figure 25 When the processing begins, the storage unit 241b of the control unit 242b stores the mobile relay station antenna information from time t to T.

[0289] The control unit 242b of the mobile relay station 2b refers to the mobile relay station antenna information stored in the storage unit 241b and selects the antenna 25 to be used in reception (step S631). The control unit 242b switches the antenna 25 so that the selected antenna 25 is used to receive the base station uplink signal.

[0290] The receiving unit 245 of the mobile relay station 2b receives the uplink signal from the base station through the antenna 25 selected by the control unit 242b (step S632). The control unit 242b reads the reception weight of each antenna 25 corresponding to the current time from the storage unit 241b and indicates the read reception weight to the receiving unit 245 (step S633).

[0291] After the receiving unit 245 weights the received signal received by the antenna 25 selected by the control unit 242b using the receiving weights indicated by the control unit 242b, it performs summation (step S634). The receiving processing unit 246 demodulates and decodes the received signal summed by the receiving unit 245 to obtain the transmitted data sent by the base station 4b (step S635).

[0292] Control unit 242b determines whether the current time t becomes time T (step S636). If the current time t becomes time T (step S636 - Yes), mobile relay station 2b terminates. Figure 25 The processing.

[0293] On the other hand, if the current time t has not become time T (step S636 - No), the control unit 242b re-references the time to select the antenna 25 used in reception corresponding to the current time (step S637). Furthermore, if the same antenna 25 as last time is selected, the control unit 242b does not need to switch the antenna 25. Afterwards, the mobile relay station 2b executes the processing after step S632.

[0294] Based on the implementation method described above, efficient communication can also be achieved in the transmission and reception of uplink signals at the base station, just like in the fourth implementation method.

[0295] The control unit 242b can also be configured to select the antenna 25 used in communication with the base station 4b using transmission capacity information. In this configuration, the transmission capacity information is further stored in the storage unit 241b. In this case, the transmission capacity information stored in the storage unit 241b shows the uplink transmission capacity of each antenna 25 at each reception time. The control unit 242b refers to the transmission capacity information stored in the storage unit 241b and selects a determined number of antennas 25 in descending order of transmission capacity at each reception time.

[0296] (The configuration of the base station uplink signal reception in the fifth embodiment)

[0297] The configuration of the wireless communication system in this embodiment and Figure 22 The configuration shown is the same. This embodiment is similar to... Figure 22 The differences in the processing of the configuration shown are as follows: For Figure 22 As shown in the configuration, mobile relay station 2b determines the antenna combination used in real time to receive uplink signals from the base station. Furthermore, mobile relay station 2b performs pre-programming... Figure 15 The processing results of steps S501 and S502 shown are stored in the storage unit 241b in advance.

[0298] Figure 26 This is a flowchart illustrating the process by which base station 4b selects the antenna station to be used in real time and transmits the base station uplink signal. Furthermore, Figure 26 The processing is performed when communication with mobile relay station 2b becomes possible (visible time t=1). Figure 26 In the middle, to and Figure 24 The same processing mark and Figure 24 The same symbols are used, but the explanations are omitted.

[0299] Each antenna station 41 of base station 4b receives information about the transmitting antenna at time t from mobile relay station 2b (step S721). Here, the transmitting antenna information at time t indicates the number of antenna stations 41 used by base station 4b in transmitting uplink signals at time t. Control unit 442b selects a subset of all antenna stations 41 that are used in transmission at time t, referring to the transmitting antenna information received via antenna stations 41 and the transmission capacity information (step S722). Thereafter, base station 4b executes the processing after step S622. Thus, base station 4b continuously receives transmitting antenna information at each time and selects antenna stations 41 based on the latest transmitting antenna information.

[0300] Figure 27 This is a flowchart illustrating the process by which mobile relay station 2b decides to utilize a combination of antennas and receive uplink signals from the base station. Furthermore, Figure 27 The processing is performed when it becomes possible to communicate with base station 4b (visible time t=1).

[0301] The control unit 242b predicts the channel matrix (H) and receives the SNR (γ) from the track information of the mobile relay station 2b at time t (e.g., t=1) (step S731).

[0302] Based on the above equation (2) and the number of each combination of utilizing antennas stored in the storage unit 241b, the control unit 242b determines the channel capacity C at time t. x The combination of antennas is maximized using the number x(t) (step S732). The control unit 242b stores the information of the number of antennas 25 in the combination of antennas used associated with the determined number x(t) as mobile relay station antenna information in the storage unit 241b.

[0303] Control unit 242b selects the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) (step S733). Control unit 242b stores the information of the modulation scheme and error correction coding rate of the antenna combination associated with the determined number x(t) in storage unit 241b. Control unit 242b notifies base station 4b of the information of the transmitting antenna at time t via antenna 25 (step S734).

[0304] Subsequently, the control unit 242b refers to the mobile relay station antenna information stored in the storage unit 241b and selects the antenna 25 to be used in reception at time t (step S735). The control unit 242b switches the antenna 25 so that the selected antenna 25 is used to receive the base station uplink signal.

[0305] The receiving unit 245 of the mobile relay station 2b receives the uplink signal from the base station through the antenna 25 selected by the control unit 242b (step S736). The control unit 242b reads the reception weight of each antenna 25 corresponding to the current time from the storage unit 241b and indicates the read reception weight to the receiving unit 245 (step S637).

[0306] After the receiving unit 245 weights the received signal received by the antenna 25 selected by the control unit 242b using the receiving weights indicated by the control unit 242b, it performs summation (step S738). The receiving processing unit 246 demodulates and decodes the received signal summed by the receiving unit 245 to obtain the transmitted data sent by the base station 4b (step S739).

[0307] Control unit 242b determines whether the current time t becomes time T (step S740). If the current time t becomes time T (step S740 - Yes), mobile relay station 2b terminates. Figure 27 The processing.

[0308] On the other hand, if the current time t has not become time T (step S740 - No), the control unit 242b re-references the time to confirm the current time t (step S741). Afterwards, the mobile relay station 2b executes the processing after step S731.

[0309] Based on the implementation method described above, efficient communication can also be achieved in the transmission and reception of uplink signals at the base station, just like in the fifth implementation method.

[0310] The control unit 242b can also be configured to select the antenna 25 used in communication with the base station 4b using transmission capacity information. In this configuration, the transmission capacity information is further stored in the storage unit 241b. The control unit 242b refers to the transmission capacity information stored in the storage unit 241b and selects the determined number of antennas 25 in descending order of transmission capacity at each reception time.

[0311] (The configuration for receiving uplink signals from the base station in the sixth embodiment)

[0312] Figure 28 This is a block diagram showing the configuration of mobile relay station 2c and base station 4b when mobile relay station 2c receives uplink signals from base station 4b. Furthermore, for... Figure 28 The number of antennas shown determines station 5, and the processing shown in the sixth embodiment is performed. Figure 28 In this paper, only the functional parts related to the transmission and reception of uplink signals of the base station are shown.

[0313] exist Figure 28 In the configuration shown, Figure 20 The process of determining the combination of antennas shown is performed by antenna number-determining station 5. Mobile relay station 2c and base station 4b respectively store information on antenna usage corresponding to the visible time. In this case, the processing when base station 4b transmits the base station uplink signal is the same as... Figure 24 Similarly, the processing of mobile relay station 2c receiving uplink signals from base station 4b is the same as... Figure 25 same.

[0314] Based on the implementation method described above, efficient communication can also be achieved in the transmission and reception of uplink signals at the base station, just like in the sixth implementation method.

[0315] (The configuration for receiving uplink signals from the base station in the seventh embodiment)

[0316] The configuration of the wireless communication system in this embodiment and Figure 27 The configuration shown is the same. This embodiment is similar to... Figure 27 The differences in the processing of the configuration shown are as follows: For Figure 27 The configuration shown indicates that the number of antennas determined by station 5 is determined in real time, and the combination of antennas used is also determined in advance by station 5. Figure 20 The processing results of steps S801 and S802 shown are stored in the storage unit 51 in advance.

[0317] Figure 29 This is a flowchart illustrating the process of mobile relay station 2c receiving uplink signals from the base station. Furthermore, Figure 29The processing is performed when communication with base station 4b becomes possible (visible time t=1). Figure 29 In the middle, to and Figure 27 The same processing mark and Figure 27 The same symbols are used, but the explanations are omitted.

[0318] Terminal communication unit 22c receives transmission information at time t (e.g., t=1) from antenna number determining station 5 (step S921). Terminal communication unit 22c outputs the received transmission information to base station communication unit 24c. Control unit 242c of base station communication unit 24c stores information on the combination of antennas used, as well as the modulation scheme and error correction coding rate in the combination of antennas used, included in the received transmission information in storage unit 241c. Control unit 242c notifies base station 4b via antenna 25 of the information on the number of antennas used in reception at time t in the information on the combination of antennas used (step S922). Thereafter, mobile relay station 2c executes the processing after step S735.

[0319] Processing of base station 4b and Figure 26 same.

[0320] Based on the implementation method described above, efficient communication can also be achieved in the transmission and reception of uplink signals at the base station, just like in the seventh implementation method.

[0321] (Eighth Implementation)

[0322] In the fourth to seventh embodiments described above, the case of having only one mobile relay station was explained. In this embodiment, the configuration in the case where the wireless communication system has multiple mobile relay stations will be described. That is, in the eighth embodiment, as a candidate for a combination of antennas, it includes antennas provided by each of the multiple mobile relay stations. Hereinafter, this embodiment will be described focusing on the differences from the fourth embodiment.

[0323] Figure 30 This is a diagram showing an outline of the wireless communication system 1d according to the eighth embodiment. The wireless communication system 1d has N mobile relay stations 2d (N is an integer of 2 or more), terminal stations 3, and base stations 4d. In this diagram, the terminal stations 3 are omitted. Hereinafter, the N mobile relay stations 2d will be referred to as mobile relay stations 2d-1 to 2d-N. Figure 30 An example is shown with N=2.

[0324] In this embodiment, mobile relay stations 2d-n calculate the transmission capacity between the antennas 25 of each mobile relay station 2d-n and the antenna station 41 of the base station 4b at each time. That is, a mobile relay station 2d-n calculates the transmission capacity of the combination of all antennas 25 of all mobile relay stations 2d-n. The transmission capacity is calculated based on the orbital information of the LEO satellite carrying the mobile relay station 2d-n, the location information of each antenna station 41, and the frequency of wireless communication. At least one of the multiple mobile relay stations 2d-n determines the combination of antennas to be used at each time based on the channel capacity (transmission capacity) between the mobile relay station 2d-n and the base station 4d. The information on the combination of antennas to be used at each time is shared among the mobile relay stations 2d-n. Each mobile relay station 2d-n uses the number of antennas 25 included in the information on the combination of antennas to communicate with the base station 4b.

[0325] As described above, in the case of multiple mobile relay stations 2d-n that can communicate with base station 4d, it is envisioned that base station 4d and the multiple mobile relay stations 2d-n communicate through either of the following two modes.

[0326] The first mode is as follows: Figure 7 This involves switching the communication between mobile relay station 2d-n and base station 4b based on the time of day. In the first mode, firstly, mobile relay station 2d-n with the highest received power is selected as the communication destination for base station 4b. Next, among the antennas 25 possessed by the selected mobile relay station 2d-n, the combination of antennas 25 with the highest transmission capacity is selected. Then, the selected mobile relay station 2d-n uses the selected antennas 25 to communicate with base station 4d.

[0327] The second mode is a mode that uses antennas 25 of multiple mobile relay stations 2d-n to communicate with base station 4b. In the second mode, transmission occurs simultaneously from multiple mobile relay stations 2d-n to base station 4b. As an example, consider selecting... Figure 30 The two antennas shown, one antenna 25 of mobile relay station 2d-1 and one antenna 25 of mobile relay station 2d-2, are used as transmitting antennas.

[0328] Figure 31 This is a block diagram illustrating the configuration of the wireless communication system 1d according to the eighth embodiment. In this diagram, [the following is a description of the configuration of the wireless communication system 1d according to the eighth embodiment]. Figure 11 The same parts of the wireless communication system 1b of the fourth embodiment shown are marked with the same symbols and their descriptions are omitted.

[0329] The mobile relay station 2d includes one or more antennas 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 24d, one or more antennas 25, and a mobile relay station communication unit 26. The base station communication unit 24d has the same configuration as in the fourth embodiment.

[0330] The base station communication unit 24d transmits data to the base station 4b via a transmitting terminal. The base station communication unit 24d includes a storage unit 241d, a control unit 242d, a data modulation unit 243, and a transmitting unit 244.

[0331] The storage unit 241d pre-stores the transmission weights of the base station downlink signals transmitted from each antenna 25 at each transmission time. Furthermore, the storage unit 241d stores the mobile relay station's antenna information at each time.

[0332] The control unit 242d determines the combination of antennas to be used at each time based on the channel capacity (transmission capacity) between the multiple mobile relay stations 2d-n and the base station 4b. In the eighth embodiment, the control unit 242d determines the combination of the number of antennas 25 of each mobile relay station 2d-n and the number of antenna stations 41 of the base station 4b at each time. Based on the combination of antennas to be used at each time, the control unit 242d selects the antennas 25 used in communication with the base station 4b from the antennas 25 possessed by the mobile relay station 2d.

[0333] The mobile relay station communication unit 26 communicates with other mobile relay stations 2d-n. For example, the mobile relay station communication unit 26 transmits information about the antenna combination determined by the control unit 242d to other mobile relay stations 2d-n. Thus, information about the antenna combination can be shared among multiple mobile relay stations 2d-n (for example, between mobile relay stations 2d-1 and 2d-2).

[0334] use Figure 15 The flowchart shown illustrates the operation of the wireless communication system 1d. Furthermore, it is configured as follows: the mobile relay station 2d-1 determines the combination of antennas used.

[0335] In step S501, the control unit 242d of the mobile relay station 2d-1 derives the total number of antenna combinations X based on the above-described equation (1). In this embodiment, M in equation (1) s It is "2", M t It is the number of antennas (25) of two mobile relay stations (2d-n). M r The number of antenna stations 41 of base station 4b is determined. Afterwards, processing from step S502 to step S507 is performed.

[0336] In step S507, when t=T (step S507-Yes), control unit 242d performs the following processing as in step S509. Specifically, control unit 242d summarizes the information on the number of receiving antennas (e.g., the number of antenna stations 41) during the visible time (t=1 to T) and notifies the base station 4b via antenna 25. Furthermore, control unit 242d transmits information on the combination of antennas used during the visible time (t=1 to T) to mobile relay stations 2d-2 via mobile relay station communication unit 26.

[0337] Mobile relay stations 2d-1 and 2d-2 select the antenna 25 to be used in transmission at each time based on information about the combination of antennas used. For example, if the information about the combination of antennas used includes information about using one antenna 25 of mobile relay station 2d-1 and one antenna 25 of mobile relay station 2d-2 at time t, mobile relay stations 2d-1 and 2d-2 each select one antenna 25 from a plurality of antennas 25 at time t. Then, mobile relay stations 2d-1 and 2d-2 use the selected antenna 25 at time t to transmit base station downlink signals to mobile relay station 2b.

[0338] The implementation method described above can also be applied to situations where multiple mobile relay stations 2d exist. Therefore, when the transmission capacity is higher than when there is only one mobile relay station 2d, multiple mobile relay stations 2d can be used to communicate with the base station 4b. As a result, more efficient communication is possible.

[0339] Furthermore, the configuration in the eighth embodiment, which includes multiple mobile relay stations 2d, can also be applied to the configuration where mobile relay stations 2d receive base station uplink signals transmitted from base station 4b.

[0340] The configuration in the eighth embodiment, which includes multiple mobile relay stations 2d, can also be applied to the fifth to seventh embodiments. Hereinafter, it will be described in detail.

[0341] (The configuration of having multiple mobile relay stations 2d in the eighth embodiment is applied to the fifth embodiment.)

[0342] In this case, for Figure 18In step S704, one mobile relay station 2d notifies the base station 4b of the number of receiving antennas at time t via antenna 25. Furthermore, the control unit 242d transmits information about the combination of antennas used at time t to other mobile relay stations 2d via the mobile relay station communication unit 26. Thus, in one process, the control unit 242d transmits information about the combination of antennas used at a certain time t to other mobile relay stations 2d via the mobile relay station communication unit 26. Then, as time progresses, the control unit 242d transmits information about the combination of antennas used corresponding to that time to other mobile relay stations 2d via the mobile relay station communication unit 26.

[0343] Mobile relay stations 2d-1 and 2d-2 select the antenna 25 to use during transmission at time t based on information about the combination of antennas used. At time t, mobile relay stations 2d-1 and 2d-2 respectively use the selected antenna 25 to transmit base station downlink signals to mobile relay station 2b.

[0344] Furthermore, the above configuration can also be applied to the configuration of mobile relay station 2d receiving base station uplink signals transmitted from base station 4b.

[0345] (The configuration of having multiple mobile relay stations 2d in the eighth embodiment is applied to the sixth embodiment.)

[0346] In this scenario, antenna number determining station 5, instead of mobile relay station 2d, determines the combination of antennas to be used at each moment based on the channel capacity (transmission capacity) between multiple mobile relay stations 2d-n and base station 4b. Antenna number determining station 5 transmits information to one mobile relay station 2d (e.g., mobile relay station 2d-1), the transmitted information including information on the combination of antennas used corresponding to the visible time, as well as information on the modulation scheme and error correction coding rate in the combination of antennas used. Furthermore, if communication with multiple mobile relay stations 2d is possible, antenna number determining station 5 can also transmit information to multiple mobile relay stations 2d.

[0347] Mobile relay station 2d-1 transmits the received transmission information to other mobile relay stations 2d-2 via mobile relay station communication unit 26. Mobile relay stations 2d-1 and 2d-2 select the antenna 25 to use during transmission at each time based on information about the combination of antennas used. Then, mobile relay stations 2d-1 and 2d-2 respectively use the selected antenna 25 to transmit base station downlink signals to mobile relay station 2b at each time.

[0348] Furthermore, the above configuration can also be applied to the configuration of mobile relay station 2d receiving base station uplink signals transmitted from base station 4b.

[0349] (The configuration of having multiple mobile relay stations 2d in the eighth embodiment is applied to the seventh embodiment.)

[0350] In this scenario, antenna number determining station 5, instead of mobile relay station 2d, determines the combination of antennas to be used at each time step based on the channel capacity (transmission capacity) between multiple mobile relay stations 2d-n and base station 4b. Antenna number determining station 5 transmits transmission information, including information on the combination of antennas used at time t, as well as information on the modulation scheme and error correction coding rate in the antenna combination, to one mobile relay station 2d (e.g., mobile relay station 2d-1). Thus, in one processing step, antenna number determining station 5 will transmit transmission information at a certain time t to mobile relay station 2d.

[0351] Mobile relay station 2d-1 transmits the received transmission information to other mobile relay stations 2d-2 via mobile relay station communication unit 26. Mobile relay stations 2d-1 and 2d-2 select the antenna 25 to use in transmission at time t based on information about the combination of antennas used. Then, mobile relay stations 2d-1 and 2d-2 respectively use the selected antenna 25 at time t to transmit base station downlink signals to mobile relay station 2b.

[0352] Furthermore, the above configuration can also be applied to the configuration of mobile relay station 2d receiving base station uplink signals transmitted from base station 4b.

[0353] The above embodiments describe a scenario where the mobile entity carrying the mobile relay station is a LEO satellite, but it could also be another flying entity such as a drone or HAPS. In cases where the communication characteristics, like those of a LEO satellite, tend to be periodic over time, antenna selection with good CSI characteristics can be set over time. On the other hand, when the mobile entity carrying the mobile relay station is an unmanned aerial vehicle (UAV), the communication characteristics may not be periodic. Even in such cases, by using information such as the position, orientation, and attitude of the mobile entity carrying the mobile relay station at each moment as mobility scheduling information, the transmission capacity of the antennas of the mobile relay station and the base station can be calculated. Therefore, a mobile relay station is capable of changing the antenna selection mode or the communication destination of the base station as the mobile relay station moves.

[0354] According to this embodiment, even when the wireless communication environment changes over time due to the movement of mobile relay stations, it is possible to select either the receiving antenna or the transmitting antenna used in wireless communication in a manner that suppresses load while simultaneously increasing transmission capacity. In the first and second embodiments, the antenna to be selected is the antenna station provided by the base station; in the third embodiment, the antenna is the antenna of each mobile relay station.

[0355] According to the above-described embodiments, the wireless communication system includes a first wireless communication device and a second wireless communication device. For example, a low-orbit satellite or other flying object has a first wireless communication device, and a second wireless communication device is installed on Earth. For example, the first wireless communication device is the mobile relay stations 2 and 2a in the embodiments, and the second wireless communication device is the base station 4 and 4a in the embodiments.

[0356] The first wireless communication device includes: one or more first antennas; and a first communication unit that communicates wirelessly with a second wireless communication device via the first antennas. For example, the first antenna is antenna 25 in this embodiment, and the first communication unit is a transmitting unit 244 and a receiving unit 245 in this embodiment. The second wireless communication device includes: one or more second antennas; and a second communication unit that communicates wirelessly with the first wireless communication device via the second antennas. For example, the second antenna is antenna station 41 in this embodiment, and the second communication unit is a receiving unit 42, 42a, and a transmitting unit 44, 44a in this embodiment. The first wireless communication device and the second wireless communication device can also communicate via MIMO. The wireless communication system includes a control unit. The control unit controls itself to: change the first antenna communicating with the second wireless communication device among the first antennas of the plurality of first wireless communication devices, or the second antenna communicating with the first wireless communication device among the plurality of second antennas of the second wireless communication device, based on the transmission capacity at each time between the first antenna and the second antenna, wherein the transmission capacity is calculated using mobility scheduling information showing the position of the first wireless communication device at each time and the position of the second antenna. For example, the control unit is the control unit 242, 242a, 422, 422a, 442, 442a in the embodiment.

[0357] For example, the control unit controls which combination of a predetermined number of secondary antennas among a plurality of secondary antennas to receive the wireless signal transmitted from the first antenna of the first wireless communication device, based on the transmission capacity at each moment.

[0358] Additionally, for example, the control unit controls which wireless signal is transmitted from the first antenna of one of the multiple first wireless communication devices, based on the transmission capacity at each moment, via the second antenna of the second wireless communication device.

[0359] Additionally, for example, the control unit controls the first communication unit of the first wireless communication device to transmit wireless signals at the time when the first antenna of the first wireless communication device is selected as the communication destination of the second wireless communication device based on the communication quality at each moment.

[0360] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the specific configuration is not limited to these embodiments, and also includes designs that do not depart from the spirit of the present invention.

[0361] Symbol Explanation

[0362] 1, 1a, 1b, 1c... wireless communication systems,

[0363] 2, 2a, 2b, 2c, 2d... mobile relay stations,

[0364] 3...Terminal station,

[0365] 4, 4a, 4b... base stations,

[0366] 5... The number of antennas determines the number of stations.

[0367] 21... antenna,

[0368] 22, 22c... Terminal Communication Department,

[0369] 23...Data Storage Department

[0370] 24, 24a, 24b, 24c, 24d... Base station communication department,

[0371] 25... antenna,

[0372] 26...Mobile Relay Station Communications Department,

[0373] 31...Data Storage Department

[0374] 32……Sending Department,

[0375] 33... antenna,

[0376] Antenna stations 41, 41-1 to 41-4...

[0377] 42, 42a, 42b... Receiving section,

[0378] 43...Base station signal receiving and processing unit,

[0379] 44...Sending Department,

[0380] 51... Storage Department

[0381] 52...Control Department

[0382] 53...Sending Department

[0383] 54... antennas

[0384] 221... Receiving Department

[0385] 222, 222c... Terminal signal receiving and processing unit,

[0386] 223... Data Recording Department

[0387] Storage units 241, 241a, 241b, 241c, 241d...

[0388] 242, 242a, 242b, 242c, 242d... Control Department,

[0389] 243……Transmitting data modulation unit,

[0390] 244……Sending Department,

[0391] 245… Receiving Department,

[0392] 246……Receiving and Processing Department,

[0393] 421, 421a, 421b... Storage section,

[0394] 422, 422a, 422b... Control Department

[0395] 423……Addition section,

[0396] 441, 441a, 441b... Storage section,

[0397] 442, 442a, 442b... Control Department

[0398] 443……Transmitting data modulation unit,

[0399] 444……Weighted multiplication part.

Claims

1. A wireless communication system that is a wireless communication system having a first wireless communication device and a second wireless communication device, the first wireless communication device includes: one or more first antennas; and a first communication section that performs wireless communication with the second wireless communication device via the first antennas, the second wireless communication device includes: one or more second antennas; and a second communication section that performs wireless communication with the first wireless communication device via the second antennas, a flying object that flies in the sky includes the first wireless communication device, and the second wireless communication device is provided on the earth, the wireless communication system includes: a control section that changes either one or both of the following antennas so as to maximize a transmission capacity at each time based on the transmission capacity at each time between the first antennas and the second antennas: the first antenna of the first wireless communication device that performs wireless communication with the second wireless communication device among the plurality of first antennas of the first wireless communication device; or the second antenna of the second wireless communication device that performs wireless communication with the first wireless communication device among the plurality of second antennas of the second wireless communication device, the transmission capacity is calculated using movement scheduling information that shows the position of the first wireless communication device at each time and the position of the second antenna, the control section stores in advance information of the communication destination of the first wireless communication device at each time and information of the communication destination of the second wireless communication device at each time that are selected based on the transmission capacity at each time, and controls so that the communication destination of the first antenna of the first wireless communication device is switched to the second wireless communication device and a wireless signal is transmitted at a time when the first antenna of the first wireless communication device is selected as the communication destination of the second wireless communication device based on the information stored in advance.

2. The wireless communication system according to claim 1, wherein the first wireless communication device and the second wireless communication device perform MIMO communication.

3. The wireless communication system according to claim 1, wherein the flying object is a low-orbit satellite.

4. A wireless communication system that is a wireless communication system having a first wireless communication device and a second wireless communication device, the first wireless communication device includes: one or more first antennas; and a first communication section that performs wireless communication with the second wireless communication device via the first antennas, the second wireless communication device includes: one or more second antennas; and a second communication section that performs wireless communication with the first wireless communication device via the second antennas, a flying object that flies in the sky includes the first wireless communication device, and the second wireless communication device is provided on the earth, the wireless communication system includes: a control section that changes either one or both of the following antennas in order of transmission capacity from high to low based on the transmission capacity at each time between the first antennas and the second antennas: the first antenna of the first wireless communication device that performs wireless communication with the second wireless communication device among the plurality of first antennas of the first wireless communication device; or the second antenna of the second wireless communication device that performs wireless communication with the first wireless communication device among the plurality of second antennas of the second wireless communication device, the second antenna of the second wireless communication device that performs wireless communication with the first wireless communication device, the transmission capacity is calculated using movement schedule information and positions of the second antennas, the movement schedule information showing positions of the first wireless communication device at every time, the control section prestores information associating the number of the first antennas used and the time with each other in order from high to low of transmission capacities between the first antennas and the second antennas at every time, and selects the combination of the number of the first antennas and the number of the second antennas used in communication between the first wireless communication device and the second wireless communication device at every time based on the prestored information.

5. The wireless communication system according to claim 4, wherein the control section decides the combination of the number of the first antennas and the number of the second antennas used during the communicable period in advance, the first wireless communication device notifies the second wireless communication device of information related to the second antennas used during the communicable period, the first wireless communication device and the second wireless communication device perform communication using the decided combination of the number of the first antennas and the number of the second antennas during the communicable period.

6. The wireless communication system according to claim 4, wherein the control section decides the combination of the number of the first antennas and the number of the second antennas used during the communicable period in each scheduled time during the communicable period between the first wireless communication device and the second wireless communication device, the first wireless communication device notifies the second wireless communication device of information related to the second antennas used during the communicable period each time the combination is notified by the control section, the first wireless communication device and the second wireless communication device perform communication using the decided combination of the number of the first antennas and the number of the second antennas during the communicable period.

7. A wireless communication system that is a wireless communication system having a first wireless communication device and a second wireless communication device, the first wireless communication device includes: one or more first antennas; and a first communication section that performs wireless communication with the second wireless communication device through the first antennas, the second wireless communication device includes: one or more second antennas; and a second communication section that performs wireless communication with the first wireless communication device through the second antennas, a flying object flying in the sky includes the first wireless communication device, and the second wireless communication device is provided on the earth, the wireless communication system includes: a control section that changes either or both of: the first antenna of the first wireless communication device that performs wireless communication with the second wireless communication device; or the second antenna of the second wireless communication device that performs wireless communication with the first wireless communication device, in order from high to low of transmission capacities between the first antennas and the second antennas at every time.

8. The wireless communication system according to claim 7, wherein the control section decides the combination of the number of the first antennas and the number of the second antennas used during the communicable period in advance, the first wireless communication device notifies the second wireless communication device of information related to the second antennas used during the communicable period, the first wireless communication device and the second wireless communication device perform communication using the decided combination of the number of the first antennas and the number of the second antennas during the communicable period.

9. The wireless communication system according to claim 7, wherein the control section decides the combination of the number of the first antennas and the number of the second antennas used during the communicable period in each scheduled time during the communicable period between the first wireless communication device and the second wireless communication device, the first wireless communication device notifies the second wireless communication device of information related to the second antennas used during the communicable period each time the combination is notified by the control section, the first wireless communication device and the second wireless communication device perform communication using the decided combination of the number of the first antennas and the number of the second antennas during the communicable period. of the second wireless communication device that performs wireless communication with the first wireless communication device, the transmission capacity is calculated using movement schedule information and positions of the second antennas, the movement schedule information showing positions of the first wireless communication device at every time, the control section prestores information associating the number of the second antennas used and the time in order from high to low of the transmission capacity at every time, and controls, based on the prestored information, reception of a wireless signal transmitted from the first antenna of the first wireless communication device by a predetermined number of the second antennas among the plurality of the second antennas at every time.

8. A wireless communication system that is a wireless communication system having a first wireless communication device and a second wireless communication device, the first wireless communication device includes: one or more first antennas; and a first communication section that performs wireless communication with the second wireless communication device via the first antennas, the second wireless communication device includes: one or more second antennas; and a second communication section that performs wireless communication with the first wireless communication device via the second antennas, the wireless communication system includes: a control section that changes either or both of: a first antenna of the first wireless communication device that performs wireless communication with the second wireless communication device; or a second antenna of the second wireless communication device that performs wireless communication with the first wireless communication device, in order from high to low of a transmission capacity at every time between the first antenna and the second antenna, the transmission capacity is calculated using movement schedule information and positions of the second antennas, the movement schedule information showing positions of the first wireless communication device at every time, the wireless communication system further includes a third wireless communication device that decides information of a combination of the first antenna of the first wireless communication device and the second antenna of the second wireless communication device corresponding to a visible time before the first wireless communication device and the second wireless communication device start communication, the first wireless communication device notifies the second wireless communication device of information related to the second antenna included in the information of the combination transmitted from the third wireless communication device, the first wireless communication device and the second wireless communication device perform communication using the combination of the first antenna and the second antenna decided by the third wireless communication device.

9. A wireless communication system that is a wireless communication system having a first wireless communication device and a second wireless communication device, the first wireless communication device includes: one or more first antennas; and a first communication section that performs wireless communication with the second wireless communication device via the first antennas, the second wireless communication device includes: one or more second antennas; and a second communication section that performs wireless communication with the first wireless communication device via the second antennas, The flying body flying in the sky has the first wireless communication device, and the second wireless communication device is arranged on the earth, The wireless communication system has: The control unit changes either one or both of the following antennas in order from high to low of the transmission capacity between the first antenna and the second antenna at each time: The first antenna of the first wireless communication device, which performs wireless communication with the second wireless communication device, among a plurality of first antennas of the first wireless communication device; or The second antenna of the second wireless communication device, which performs wireless communication with the first wireless communication device, among a plurality of second antennas of the second wireless communication device, The transmission capacity is calculated using movement scheduling information and the position of the second antenna, and the movement scheduling information shows the position of the first wireless communication device at each time, The wireless communication system has a plurality of first wireless communication devices, A plurality of first wireless communication devices share information on the combination of the first antenna and the second antenna by transmitting and receiving information on the combination of the first antenna and the second antenna between one first wireless communication device and other first wireless communication devices, The control unit prestores information associating the number of first antennas used and the time in order from high to low of the transmission capacity between the first antenna and the second antenna at each time, and selects the combination of the number of first antennas and the number of second antennas used in communication between a plurality of first wireless communication devices and the second wireless communication device at each time based on the prestored information.

10. A wireless communication device having: 1 or more antennas; A communication unit that performs wireless communication with a communication destination device through the 1 or more antennas of the own device; and A control unit that changes either one or both of the following antennas based on the transmission capacity between the 1 or more antennas of the own device and the antennas of the communication destination device at each time, so as to maximize the transmission capacity: The antenna of a plurality of antennas of the communication destination device, which performs wireless communication with the own device; or The antenna of a plurality of antennas of the own device, which performs wireless communication with the communication destination device, The transmission capacity is calculated using movement scheduling information and the position of the 1 or more antennas of the own device, and the movement scheduling information shows the position of the communication destination device at each time, The flying body flying in the sky has the communication unit, and the communication destination device is arranged on the earth, The control unit prestores information on the communication destination of the communication unit at each time and information on the communication destination of the communication destination device at each time selected based on the transmission capacity at each time, and controls so that the 1 or more antennas of the own device are switched to the communication destination device and a wireless signal is transmitted at the time when the 1 or more antennas of the own device are selected as the communication destination of the communication destination device based on the prestored information.

11. A wireless communication apparatus that is one of a plurality of wireless communication apparatuses in a wireless communication system, the wireless communication apparatus comprising: one or more antennas; a communication unit that performs wireless communication with a communication destination apparatus via the antenna; and a control unit that determines a communication destination apparatus with which to perform communication in a time period, the time period being a time period in which a transmission capacity is maximized among transmission capacities at every time between the antenna of the wireless communication apparatus and an antenna of the communication destination apparatus, and the time period being obtained with reference to communication destination base station information that is information in which a communication time period is associated with a communication destination apparatus that is a destination of communication in the communication time period, the communication time period indicating a time period in which communication is performed, the transmission capacity being calculated using movement schedule information and a position of the antenna of the communication destination apparatus, the movement schedule information showing a position at every time of the wireless communication apparatus, the control unit prestoring the communication destination base station information in which the communication time period is associated with the communication destination apparatus that is the destination of communication in the communication time period, and controlling so that if it is detected that a current time is a start time of the communication time period set in the communication destination base station information, a wireless signal is transmitted to the communication destination apparatus associated with the communication time period.

12. A wireless communication method that is a wireless communication method performed by a wireless communication system having a first wireless communication apparatus and a second wireless communication apparatus, a flying object flying in the sky having the first wireless communication apparatus, the second wireless communication apparatus being provided on the earth, the wireless communication method comprising: a first communication step in which the first wireless communication apparatus performs wireless communication with the second wireless communication apparatus via one or more first antennas; a second communication step in which the second wireless communication apparatus performs wireless communication with the first wireless communication apparatus via one or more second antennas; and a control step in which a control unit changes either one or both of the following antennas so that a transmission capacity is maximized based on the transmission capacity at every time between the first antenna and the second antenna: the first antenna of the plurality of first antennas of the first wireless communication apparatus that performs wireless communication with the second wireless communication apparatus; or the second antenna of the plurality of second antennas of the second wireless communication apparatus that performs wireless communication with the first wireless communication apparatus, the transmission capacity being calculated using movement schedule information and a position of the second antenna, the movement schedule information showing a position at every time of the first wireless communication apparatus. ​ In the control step, information of a communication destination of the first wireless communication device at each time and information of a communication destination of the second wireless communication device at each time are stored in advance based on the transmission capacity at each time, and control is performed so that the communication destination of the first antenna of the first wireless communication device is switched to the second wireless communication device and a wireless signal is transmitted at a time when the first antenna of the first wireless communication device is selected as a communication destination of the second wireless communication device based on the information stored in advance.

13. A wireless communication method, which is a wireless communication method performed by a wireless communication device, the wireless communication method having: a communication step in which wireless communication is performed with a communication destination apparatus through one or more antennas; and a control step in which either one or both of the following antennas is changed based on a transmission capacity at each time between the one or more antennas of the wireless communication device and an antenna of the communication-destination device so that the transmission capacity is maximized: an antenna of the plurality of antennas of the communication-destination device that performs wireless communication with the own device; or an antenna of the plurality of antennas of the own device that performs wireless communication with the communication-destination device, the transmission capacity being calculated using movement schedule information and positions of the one or more antennas of the wireless communication device, the movement schedule information showing a position of the communication-destination device at each time, a flying body flying in the sky is provided with the wireless communication device, and the communication-destination device is provided on the earth, in the control step, information of a communication destination of the wireless communication device at each time and information of a communication destination of the communication-destination device at each time are stored in advance based on the transmission capacity at each time, and control is performed so that the communication destination of the one or more antennas of the wireless communication device is switched to the communication-destination device and a wireless signal is transmitted at a time when the one or more antennas of the wireless communication device is selected as a communication destination of the communication-destination device based on the information stored in advance.

14. A wireless communication method, which is a wireless communication method performed by a wireless communication device in a wireless communication system having a plurality of wireless communication devices, the wireless communication method having: a communication step in which wireless communication is performed with a communication-destination device through one or more antennas; and a control step in which either one or both of the following antennas is changed based on a transmission capacity at each time between the one or more antennas of the wireless communication device and an antenna of the communication-destination device so that the transmission capacity is maximized: an antenna of the plurality of antennas of the communication-destination device that performs wireless communication with the own device; or an antenna of the plurality of antennas of the own device that performs wireless communication with the communication-destination device, the transmission capacity being calculated using movement schedule information and positions of the one or more antennas of the wireless communication device, the movement schedule information showing a position of the communication-destination device at each time, a flying body flying in the sky is provided with the wireless communication device, and the communication-destination device is provided on the earth, in the control step, information of a communication destination of the wireless communication device at each time and information of a communication destination of the communication-destination device at each time are stored in advance based on the transmission capacity at each time, and control is performed so that the communication destination of the one or more antennas of the wireless communication device is switched to the communication-destination device and a wireless signal is transmitted at a time when the one or more antennas of the wireless communication device is selected as a communication destination of the communication-destination device based on the information stored in advance. a control step of deciding a communication-destination device to communicate with in a time period in which a transmission capacity is maximized among transmission capacities at every time between each of antennas of a plurality of the wireless communication devices and an antenna of the communication-destination device, and the time period is obtained with reference to communication-destination base station information that is information in which a communication time period is associated with a communication-destination device that is a destination of communication in the communication time period, the communication time period indicating a time period in which communication is performed, the transmission capacity being calculated using movement schedule information that shows a position of each of the plurality of the wireless communication devices at every time and a position of the antenna of the communication-destination device, in the control step, the communication-destination base station information in which the communication time period is associated with the communication-destination device that is the destination of communication in the communication time period is stored in advance, and the control is performed so that if it is detected that a current time is a start time of the communication time period set in the communication-destination base station information, a wireless signal is transmitted to the communication-destination device associated with the communication time period.

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