WO2022137564A1 - 無線通信装置、無線通信システム、無線通信方法、及びプログラム - Google Patents
無線通信装置、無線通信システム、無線通信方法、及びプログラム Download PDFInfo
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- 238000000034 method Methods 0.000 title claims description 60
- 230000005540 biological transmission Effects 0.000 claims abstract description 200
- 238000004364 calculation method Methods 0.000 claims abstract description 38
- 238000012545 processing Methods 0.000 claims description 101
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- 238000013500 data storage Methods 0.000 description 41
- 238000010586 diagram Methods 0.000 description 14
- 230000015572 biosynthetic process Effects 0.000 description 8
- 238000003786 synthesis reaction Methods 0.000 description 8
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
- H04B7/18513—Transmission in a satellite or space-based system
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
- H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
- H04B7/0413—MIMO systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/24—Cell structures
- H04W16/28—Cell structures using beam steering
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/30—Services specially adapted for particular environments, situations or purposes
- H04W4/38—Services specially adapted for particular environments, situations or purposes for collecting sensor information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/18—TPC being performed according to specific parameters
- H04W52/28—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/38—TPC being performed in particular situations
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/04—Large scale networks; Deep hierarchical networks
- H04W84/06—Airborne or Satellite Networks
Definitions
- the present invention relates to a wireless communication device, a wireless communication system, a wireless communication method, and a program.
- the IoT (Internet of Things) system that realizes various applications by connecting a small terminal device to the Internet is widespread.
- IoT Internet of Things
- a system is known in which a plurality of IoT terminals sense environmental information such as temperature, room temperature, acceleration, and luminosity, transmit it as a wireless signal, and collect environmental information on the cloud side.
- IoT terminals equipped with various sensors are installed in various places. For example, it is expected that IoT will be used to collect data on places where it is difficult to install base stations, such as buoys and ships on the sea, and mountainous areas.
- a wireless system that performs wireless communication between multiple communication devices on the ground using a communication satellite or UAV (Unmanned Aerial Vehicle) as a relay station.
- a radio system using a communication satellite as a relay station a low earth orbit satellite (LEO: Low Earth Orbit) orbiting at an altitude of around 1,000 [km] is used, and an altitude of 36,000 [km] is orbiting.
- Geostationary Orbit (GEO) may be used.
- Low earth orbit satellites have a shorter propagation distance than geostationary satellites. Therefore, when a low earth orbit satellite is used as a relay station, it is possible to realize communication with low delay and low propagation loss.
- low earth orbit satellites orbit over the earth, so the direction of the satellite as seen from the communication equipment on the ground constantly changes.
- the visible time per orbit of a low earth orbit satellite in each communication device on the ground is about 10 minutes or less. Therefore, the time zone in which the low earth orbit satellite and each communication device on the ground can communicate is limited.
- LPWA Low Power Wide Area
- LPWA Low Power Wide Area
- a satellite IoT system in which a communication satellite collects data from an IoT terminal using LPWA is being studied.
- wireless communication between a communication satellite and a terrestrial communication device has a longer propagation distance than wireless communication in which direct communication is performed between a plurality of terrestrial communication devices.
- the use of low earth orbit satellites makes it possible to apply LPWA.
- IoT terminals in the aviation field, the ship field, and the rural area, which was difficult with ordinary LPWA alone. Further, in this case, since a hub station is not required, service development becomes easy.
- the communication device mounted on the communication satellite is mainly supplied with power by a solar cell, and the power that can be consumed is limited.
- a technique for reducing the power consumption of a communication device mounted on a communication satellite has been conventionally studied (see, for example, Patent Document 1).
- the power supply capacity may be limited because the device is required to be smaller, lighter, and simpler.
- long-term driving is required, low power consumption is required.
- the transmission output required for transmitting a signal from the IoT terminal to the low earth orbit satellite depends on the distance between the IoT terminal and the low earth orbit satellite. For example, the closer the distance between the IoT terminal and the low earth orbit satellite, the smaller the transmission output can be used to transmit and receive signals.
- the signal is transmitted with a constant transmission output regardless of the distance between the IoT terminal and the low earth orbit satellite.
- a signal is transmitted with a transmission output large enough to transmit and receive a signal even if the distance between the ground station and the satellite station is long. Therefore, conventionally, when the distance between the IoT terminal and the low earth orbit satellite is short, the signal is transmitted with an unnecessarily large transmission output, so that there is a problem that power is wasted.
- an object of the present invention is to provide a wireless communication device, a wireless communication system, a wireless communication method, and a program capable of suppressing power consumption.
- One aspect of the present invention is a transmission unit that transmits a signal to another wireless communication device mounted on a mobile body, and the transmission unit starts transmission of the signal at a timing capable of communicating with the other wireless communication device.
- the timing control unit acquires the orbital information indicating the orbital orbit and the self-position information indicating the self-position of the moving body, and the self-position and the moving body at the timing are based on the orbit information and the self-position information.
- One aspect of the present invention is a wireless communication system including a first wireless communication device, a relay device mounted on a mobile body, and a second wireless communication device, wherein the first wireless communication device is the relay.
- a first signal transmission unit that transmits the first signal to the device, a timing control unit that starts transmission of the first signal by the first signal transmission unit at a timing communicable with the relay device, and an orbit of the moving body.
- a distance that acquires the orbit information indicating the orbit and the self-position information indicating the self-position, and calculates the positional relationship between the self-position and the position of the moving body at the timing based on the orbit information and the self-position information.
- the relay device includes a calculation unit and an output control unit that controls the transmission output of the first signal by the first signal transmission unit according to the positional relationship, and the relay device is the transmission of the first wireless communication device.
- a first signal receiving unit that receives the first signal
- a storage unit that stores waveform data indicating the waveform of the first signal received by the first signal receiving unit, and the waveform data stored in the storage unit.
- a second signal transmission unit for transmitting the indicated second signal to the second wireless communication device at a timing capable of communicating with the second wireless communication device is provided, and the second wireless communication device is transmitted by the relay device.
- a second signal receiving unit that receives the second signal, a second signal receiving processing unit that performs reception processing of the second signal received by the second signal receiving unit and acquires the waveform data, and the first signal receiving unit.
- a first signal reception processing unit that performs reception processing of the first signal indicated by the waveform data acquired by the signal reception processing unit and acquires data set in the first signal by the first wireless communication device. It is a wireless communication system provided.
- One aspect of the present invention is a transmission step of transmitting a signal to another wireless communication device mounted on a mobile body, and starting transmission of the signal in the transmission step at a timing capable of communicating with the other wireless communication device.
- the timing control step, the orbital information indicating the orbital trajectory of the moving body, and the self-position information indicating the self-position are acquired, and the self-position and the moving body at the timing are based on the orbit information and the self-position information.
- It is a wireless communication method including a distance calculation step for calculating a positional relationship with a position of the above, and an output control step for controlling the transmission output of the signal in the transmission step according to the positional relationship.
- One aspect of the present invention is a wireless communication method executed by a wireless communication system including a first wireless communication device, a relay device mounted on a mobile body, and a second wireless communication device, wherein the first wireless communication device is used.
- the first signal transmission step in which the communication device transmits the first signal to the relay device, and the first signal in the first signal transmission step at the timing when the first wireless communication device can communicate with the relay device.
- the timing control unit for starting transmission and the first wireless communication device acquire the orbit information indicating the orbital orbit of the moving body and the self-position information indicating the self-position, and use the orbit information and the self-position information.
- the first wireless communication device is the first in the first signal transmission step according to the positional relationship.
- An output control step that controls the transmission output of the signal, a first signal reception step in which the relay device receives the first signal transmitted by the first wireless communication device, and the relay device receives the first signal.
- a storage step for storing waveform data indicating the waveform of the first signal received in the step, and a second signal indicating the waveform data stored in the storage step by the relay device are stored in the second wireless communication device.
- the second signal reception processing step in which the second wireless communication device performs reception processing of the second signal received in the second signal reception step to acquire the waveform data, and the second wireless communication device The first signal reception processing step of performing the reception processing of the first signal indicated by the waveform data acquired in the second signal reception processing step and acquiring the data set in the first signal by the first wireless communication device. It is a wireless communication method having.
- One aspect of the present invention is a program for operating a computer as the above-mentioned wireless communication device.
- FIG. 1 is a configuration diagram of a wireless communication system 1 according to the first embodiment.
- the wireless communication system 1 has a mobile relay station 2, a terminal station 3, and a base station 4.
- the number of each of the mobile relay station 2, the terminal station 3, and the base station 4 included in the wireless communication system 1 is arbitrary, but it is assumed that the number of the terminal stations 3 is large.
- the wireless communication system 1 is a communication system that transmits information that does not require immediacy.
- the information transmitted from each of the plurality of terminal stations 3 is transmitted via the mobile relay station 2 and collected by the base station 4.
- the mobile relay station 2 is an example of a relay device mounted on a mobile body and in which a communicable area moves with the passage of time.
- the mobile relay station 2 is provided in, for example, a LEO (Low Earth Orbit) satellite.
- the altitude of the LEO satellite is about 2000 [km] or less, and it orbits over the earth in about 1.5 hours.
- the terminal station 3 and the base station 4 are installed on the earth such as on the ground or at sea.
- the plurality of terminal stations 3 exist in different places from each other.
- the terminal station 3 is, for example, an IoT terminal.
- the terminal station 3 collects data such as environmental data detected by the sensor and wirelessly transmits the data to the mobile relay station 2. In the figure, only two terminal stations 3 are shown.
- the mobile relay station 2 receives data transmitted from each of the plurality of terminal stations 3 by wireless signals while moving over the earth.
- the mobile relay station 2 accumulates these received data, and wirelessly transmits the accumulated data to the base station 4 at a timing when communication with the base station 4 is possible.
- the base station 4 receives the data collected by the terminal station 3 from the mobile relay station 2.
- the mobile relay station 2 it is conceivable to use a geostationary satellite or a relay station mounted on an unmanned aerial vehicle such as a drone or HAPS (High Altitude Platform Station).
- a relay station mounted on a geostationary satellite although the coverage area (footprint) on the ground is wide, the link budget for the IoT terminal installed on the ground is very small due to the high altitude.
- the link budget is high, but the coverage area is narrow.
- the drone needs a battery
- the HAPS needs a battery and a solar panel to charge it.
- the mobile relay station 2 is mounted on the LEO satellite. Therefore, in addition to keeping the link budget within the limit, the LEO satellite has no air resistance and consumes less fuel because it orbits outside the atmosphere. In addition, the footprint is larger than when a relay station is mounted on a drone or HAPS.
- the mobile relay station 2 mounted on the LEO satellite communicates while moving at high speed, the time during which each terminal station 3 or base station 4 can communicate with the mobile relay station 2 is limited. Specifically, when viewed from a terminal station on the ground, the mobile relay station 2 passes over the sky in about 10 minutes or less. Further, a wireless communication method having various specifications is used for the terminal station 3.
- the mobile relay station 2 receives the terminal uplink signal from the terminal station 3 in the coverage at the current position during movement, and stores the waveform data of the received terminal uplink signal.
- the mobile relay station 2 wirelessly transmits the base station downlink signal set with the waveform data of the terminal uplink signal to the base station 4 at the timing when the base station 4 exists in the coverage.
- the base station 4 demodulates the base station downlink signal received from the mobile relay station 2 to obtain waveform data of the terminal uplink signal.
- the base station 4 obtains terminal transmission data which is the data transmitted by the terminal station 3 by demodulating and decoding the terminal uplink signal represented by the waveform data.
- the mobile relay station 2 includes an antenna 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 24, and an antenna 25.
- the terminal communication unit 22 has a reception unit 221 and a reception waveform recording unit 222.
- the receiving unit 221 receives the terminal uplink signal by the antenna 21.
- the reception waveform recording unit 222 samples the reception waveform of the terminal uplink signal received by the reception unit 221 and generates waveform data showing the value obtained by the sampling.
- the reception waveform recording unit 222 writes the reception waveform information in which the reception time of the terminal uplink signal in the antenna 21 and the generated waveform data are set in the data storage unit 23.
- the data storage unit 23 stores the received waveform information written by the received waveform recording unit 222.
- the base station communication unit 24 transmits the received waveform information to the base station 4 by the base station downlink signal of any wireless communication method.
- the base station communication unit 24 includes a storage unit 241, a control unit 242, a transmission data modulation unit 243, and a transmission unit 244.
- the storage unit 241 stores the transmission start timing calculated in advance based on the orbit information of the LEO satellite equipped with the mobile relay station 2 and the position of the base station 4.
- the orbit information of LEO is information that can obtain the position, speed, moving direction, etc. of the LEO satellite at an arbitrary time.
- the transmission time may be represented by, for example, the elapsed time from the transmission start timing.
- the control unit 242 controls the transmission data modulation unit 243 and the transmission unit 244 so as to transmit the received waveform information to the base station 4 at the transmission start timing stored in the storage unit 241.
- the transmission data modulation unit 243 reads the received waveform information from the data storage unit 23 as transmission data, modulates the read transmission data, and generates a base station downlink signal.
- the transmission unit 244 converts the base station downlink signal from an electric signal to a wireless signal and transmits it from the antenna 25.
- the terminal station 3 includes a data storage unit 31, a transmission unit 32, one or more antennas 33, a reception unit 34, and a transmission control unit 35.
- the data storage unit 31 stores sensor data and the like.
- the transmission unit 32 reads sensor data from the data storage unit 31 as terminal transmission data, and wirelessly transmits a terminal uplink signal set with the read terminal transmission data from the antenna 33.
- the transmission unit 32 transmits a signal by, for example, LPWA (Low Power Wide Area).
- LPWA includes LoRaWAN (registered trademark), Sigfox (registered trademark), LTE-M (LongTermEvolution for Machines), NB (NarrowBand) -IoT and the like, and any wireless communication method can be used.
- the transmission unit 32 may transmit to another terminal station 3 by time division multiplexing, OFDM (Orthogonal Frequency Division Multiplexing), or the like.
- the transmission unit 32 determines the channel used by the station to transmit the terminal uplink signal and the transmission start timing by a method predetermined in the wireless communication method to be used. Further, the transmitting unit may form a beam of signals transmitted from a plurality of antennas 33 by a method predetermined in the wireless communication method to be used.
- the receiving unit 34 receives the notification signal transmitted from the mobile relay station 2.
- the transmission control unit 35 controls the transmission output of the signal transmitted by the transmission unit 32. The configuration of the control processing of the transmission output of the signal by the transmission control unit 35 will be described later.
- the base station 4 includes an antenna 41, a receiving unit 42, a base station signal receiving processing unit 43, and a terminal signal receiving processing unit 44.
- the receiving unit 42 converts the terminal downlink signal received by the antenna 41 into an electric signal.
- the base station signal reception processing unit 43 demodulates and decodes the received signal converted into an electric signal by the receiving unit 42, and obtains received waveform information.
- the base station signal reception processing unit 43 outputs the received waveform information to the terminal signal reception processing unit 44.
- the terminal signal reception processing unit 44 performs reception processing of the terminal uplink signal indicated by the received waveform information. At this time, the terminal signal reception processing unit 44 performs reception processing by the wireless communication method used for transmission by the terminal station 3 to acquire terminal transmission data.
- the terminal signal reception processing unit 44 includes a terminal signal demodulation unit 441 and a terminal signal decoding unit 442.
- the terminal signal demodulation unit 441 demodulates the waveform data and outputs the symbol obtained by the demodulation to the terminal signal decoding unit 442.
- the terminal signal demodulation unit 441 may perform demodulation after performing a process of compensating for the Doppler shift of the terminal uplink signal received by the antenna 21 of the mobile relay station 2 with respect to the signal indicated by the waveform data.
- the Doppler shift received by the terminal uplink signal received by the antenna 21 is calculated in advance based on the position of the terminal station 3 and the orbit information of the LEO on which the mobile relay station 2 is mounted.
- the terminal signal decoding unit 442 decodes the symbol demodulated by the terminal signal demodulation unit 441 and obtains the terminal transmission data transmitted from the terminal station 3.
- the terminal station 3 in the present embodiment calculates the distance between the mobile relay station 2 to which the signal is transmitted and its own position.
- the terminal station 3 determines the transmission output of the signal to be transmitted to the mobile relay station 2 based on the calculated distance.
- the transmission output required for transmitting a signal from an IoT terminal to a low earth orbit satellite depends on the distance between the IoT terminal and the low earth orbit satellite. For example, the closer the distance between the IoT terminal and the low earth orbit satellite, the smaller the transmission output can be used to transmit and receive signals.
- the terminal station 3 in the present embodiment has a transmission output sufficient for transmitting a signal to the mobile relay station 2, and transmits with a smaller transmission output. As a result, the terminal station 3 in the present embodiment can suppress power consumption.
- FIG. 2 is a block diagram showing a functional configuration of the transmission control unit 35 of the terminal station 3 according to the first embodiment.
- FIG. 3 is a block diagram showing a configuration of a data storage unit 31 of the terminal station 3 according to the first embodiment.
- the transmission control unit 35 includes a timing control unit 351, a distance calculation unit 352, and an output control unit 353. Further, as shown in FIG. 3, the data storage unit 31 stores sensor data 311, orbit information 312, self-position information 313, and output control information 314.
- the sensor data 311 is data generated by an IoT terminal having a terminal station 3 and transmitted from the terminal station 3 to the mobile relay station 2.
- the sensor data 311 is, for example, environmental data indicating the temperature, humidity, tidal current, etc. around the IoT terminal having the terminal station 3.
- the orbit information 312 is information indicating the orbit of a low earth orbit satellite equipped with the mobile relay station 2.
- the orbit information 312 is information indicating, for example, which low earth orbit satellite is present at what time and position.
- the self-position information 313 is information indicating the position of the self-terminal station 3.
- the self-position information 313 is updated at any time.
- the terminal station 3 is equipped with a positioning system such as GPS, and the self-position information 313 is updated by the position information measured at any time by the positioning system.
- the output control information 314 is information in which the distance between the mobile relay station 2 and the terminal station 3 and the transmission output of the signal are associated with each other.
- the output control information 314 is a function that outputs information indicating signal transmission output when information indicating distance is input.
- the output control information 314 may be a table in which the information indicating the distance and the information indicating the transmission output of the signal are associated with each other.
- the timing control unit 351 reads out the orbit information 312 and the self-position information 313 from the data storage unit 31.
- the timing control unit 351 sets the timing at which the transmission unit 32 transmits a signal based on the sensor data 311 to the mobile relay station 2 based on the track information 312 and the self-position information 313 (hereinafter, referred to as “transmission start timing”). decide.
- the transmission start timing is, for example, the transmission time of a signal based on the above sensor data 311.
- the timing control unit 351 records the transmission start timing information indicating the determined transmission start timing in the data storage unit 31.
- the distance calculation unit 352 acquires the transmission start timing information recorded in the data storage unit 31.
- the distance calculation unit 352 reads out the orbit information 312 and the self-position information 313 from the data storage unit 31.
- the distance calculation unit 352 specifies the position of the mobile relay station 2 at the transmission start timing based on the transmission start timing information and the trajectory information 312.
- the distance calculation unit 352 determines the distance between the mobile relay station 2 and its own terminal station 3 at the transmission start timing based on the specified position of the mobile relay station 2 and the self-position indicated by the self-position information 313. calculate.
- the distance calculation unit 352 records information indicating the calculated distance (hereinafter referred to as “distance information”) in the data storage unit 31.
- the output control unit 353 acquires distance information from the data storage unit 31.
- the output control unit 353 reads the output control information 314 from the data storage unit 31.
- the output control unit 353 determines the transmission output of the signal by the transmission unit 32 based on the distance information and the output control information 314.
- the output control unit 353 records the transmission output information indicating the determined transmission output in the data storage unit 31.
- the output control unit 353 reads out the transmission output information recorded in the data storage unit 31 before the transmission start timing is reached.
- the output control unit 353 controls the transmission unit 32 so that the signal is transmitted to the mobile relay station 2 by the transmission output based on the transmission output information at the transmission start timing.
- FIG. 4 is a flow chart showing the processing of the wireless communication system 1 when the terminal uplink signal is transmitted from the terminal station 3.
- the terminal station 3 acquires data detected by a sensor (not shown) provided externally or internally at any time, and writes the acquired data as sensor data 311 in the data storage unit 31 (step S111).
- the timing control unit 351 reads out the orbit information 312 and the self-position information 313 from the data storage unit 31.
- the timing control unit 351 determines the transmission start timing based on the trajectory information 312 and the self-position information 313 (step S112).
- the timing control unit 351 records the transmission start timing information indicating the determined transmission start timing in the data storage unit 31.
- the distance calculation unit 352 acquires the transmission start timing information recorded in the data storage unit 31.
- the distance calculation unit 352 reads out the orbit information 312 and the self-position information 313 from the data storage unit 31.
- the distance calculation unit 352 specifies the position of the mobile relay station 2 at the transmission start timing based on the transmission start timing information and the trajectory information 312.
- the distance calculation unit 352 determines the distance between the mobile relay station 2 and its own terminal station 3 at the transmission start timing based on the specified position of the mobile relay station 2 and the self-position indicated by the self-position information 313. Calculate (step S113).
- the distance calculation unit 352 records the distance information indicating the calculated distance in the data storage unit 31.
- the output control unit 353 acquires distance information from the data storage unit 31.
- the output control unit 353 reads the output control information 314 from the data storage unit 31.
- the output control unit 353 determines the transmission output of the signal by the transmission unit 32 based on the distance information and the output control information 314 (step S114).
- the output control unit 353 records the transmission output information indicating the determined transmission output in the data storage unit 31.
- the output control unit 353 reads out the transmission output information recorded in the data storage unit 31 before the transmission start timing is reached.
- the output control unit 353 controls the transmission unit 32 so that the signal is transmitted to the mobile relay station 2 at the determined transmission output at the transmission start timing.
- the transmission unit 32 reads the sensor data 311 from the data storage unit 31 as terminal transmission data.
- the transmission unit 32 wirelessly transmits the terminal uplink signal set with the terminal transmission data from the antenna 33 at the transmission start timing determined by the timing control unit 351 in step S112. At this time, the transmission unit 32 wirelessly transmits the terminal uplink signal at the transmission output determined by the output control unit 353 in step S114 (step S115).
- the terminal station 3 repeats the process from step S111.
- the receiving unit 221 of the mobile relay station 2 receives the terminal uplink signal transmitted from the terminal station 3 (step S121). Depending on the wireless communication method of the source terminal station 3, there are cases where the terminal uplink signal is received from only one terminal station 3 on a time-division basis for the same frequency, and cases where the terminal uplink signal is received from multiple terminal stations 3 at the same frequency at the same frequency. It may receive a terminal uplink signal.
- the reception waveform recording unit 222 writes the received waveform information in which the waveform data representing the waveform of the terminal uplink signal received by the receiving unit 221 and the reception time are associated with each other in the data storage unit 23 (step S122). The mobile relay station 2 repeats the process from step S121.
- FIG. 5 is a flow chart showing the processing of the wireless communication system 1 when the base station downlink signal is transmitted from the mobile relay station 2.
- the control unit 242 of the base station communication unit 24 of the mobile relay station 2 detects that the transmission start timing is stored in the storage unit 241, the transmission of the received waveform information is transmitted to the transmission data modulation unit 243 and the transmission unit 244.
- Instruct step S211).
- the transmission data modulation unit 243 reads the received waveform information stored in the data storage unit 23 as transmission data, modulates the read transmission data, and generates a base station downlink signal.
- the transmission unit 244 wirelessly transmits the base station downlink signal generated by the transmission data modulation unit 243 from the antenna 25 (step S212).
- the mobile relay station 2 repeats the process from step S211.
- the antenna 41 of the base station 4 receives the base station downlink signal from the mobile relay station 2 (step S221).
- the receiving unit 42 converts the base station downlink signal received by the antenna 41 into a received signal of an electric signal, and outputs the signal to the base station signal receiving processing unit 43.
- the base station signal reception processing unit 43 demodulates the received signal and decodes the demodulated received signal (step S222).
- the base station signal reception processing unit 43 outputs the reception waveform information obtained by decoding to the terminal signal reception processing unit 44.
- the terminal signal reception processing unit 44 performs reception processing of the terminal uplink signal represented by the waveform data included in the received waveform information (step S223). Specifically, the terminal signal demodulation unit 441 specifies the wireless communication method used by the terminal station 3 to transmit the terminal uplink signal based on the information unique to the wireless communication method included in the received signal represented by the waveform data. .. The terminal signal demodulation unit 441 demodulates the received signal represented by the waveform data according to the specified wireless communication method, and outputs the symbol obtained by the demodulation to the terminal signal decoding unit 442. The terminal signal decoding unit 442 decodes the symbol input from the terminal signal demodulation unit 441 by the specified wireless communication method, and obtains the terminal transmission data transmitted from the terminal station 3. The terminal signal decoding unit 442 can also use a decoding method having a large calculation load, such as SIC (Successive Interference Cancellation).
- the base station 4 repeats the process from step S221.
- the terminal station 3 in the present embodiment calculates the distance between the mobile relay station 2 to which the signal is transmitted and its own position at the signal transmission start timing.
- the terminal station 3 determines the transmission output of the signal to be transmitted to the mobile relay station 2 based on the calculated distance.
- the transmission output required for transmitting a signal from an IoT terminal to a low earth orbit satellite in a satellite IoT system depends on the distance between the IoT terminal and the low earth orbit satellite.
- the terminal station 3 in the present embodiment has a transmission output sufficient for transmitting a signal to the mobile relay station 2, and transmits with a smaller transmission output.
- the terminal station 3 does not transmit a signal with an unnecessarily large transmission output even when the distance between the mobile relay station 2 and its own position is short, so that power is wasted. It will not be consumed. Therefore, the terminal station 3 in the present embodiment can suppress the power consumption.
- the mobile relay station transmits a base station downlink signal by a plurality of antennas.
- MIMO Multiple Input Multiple Output
- FIG. 6 is a configuration diagram of the wireless communication system 1a according to the second embodiment.
- the wireless communication system 1a has a mobile relay station 2a, a terminal station 3, and a base station 4a.
- the mobile relay station 2a includes an antenna 21, a terminal communication unit 22, a data storage unit 23, a base station communication unit 26, and a plurality of antennas 25.
- the base station communication unit 26 transmits received waveform information to the base station 4a by MIMO.
- the base station communication unit 26 includes a storage unit 261, a control unit 262, a transmission data modulation unit 263, and a MIMO transmission unit 264.
- the storage unit 261 stores the transmission start timing calculated in advance based on the orbit information of the LEO satellite equipped with the mobile relay station 2a and the position of the base station 4a. Further, the storage unit 261 stores in advance the wait for each transmission time of the base station downlink signal transmitted from each antenna 25.
- the weight for each transmission time is calculated based on the orbit information of the LEO satellite and the position of each antenna station 410 included in the base station 4a. A constant weight may be used regardless of the transmission time.
- the control unit 262 controls the transmission data modulation unit 263 and the MIMO transmission unit 264 so as to transmit the received waveform information to the base station 4a at the transmission start timing stored in the storage unit 261. Further, the control unit 262 instructs the MIMO transmission unit 264 to wait for each transmission time read from the storage unit 261.
- the transmission data modulation unit 263 reads the received waveform information from the data storage unit 23 as transmission data, converts the read transmission data into a parallel signal, and then modulates it.
- the MIMO transmission unit 264 weights the modulated parallel signal by the weight instructed by the control unit 262, and generates a base station downlink signal transmitted from each antenna 25.
- the MIMO transmission unit 264 transmits the generated base station downlink signal from the antenna 25 by MIMO.
- the base station 4a includes a plurality of antenna stations 410, a MIMO receiving unit 420, a base station signal receiving processing unit 430, and a terminal signal receiving processing unit 44.
- the antenna station 410 is arranged at a position away from the other antenna stations 410 so that the difference in the arrival angles of the signals from each of the plurality of antennas 25 of the mobile relay station 2a becomes large.
- Each antenna station 410 converts the base station downlink signal received from the mobile relay station 2a into an electric signal and outputs it to the MIMO receiving unit 420.
- the MIMO receiver 420 aggregates the base station downlink signals received from the plurality of antenna stations 410.
- the MIMO receiving unit 420 stores the weight for each reception time for the base station downlink signal received by each of the antenna stations 410 based on the orbit information of the LEO satellite and the position of each antenna station 410.
- the MIMO receiving unit 420 multiplies the base station downlink signal input from each antenna station 410 by the weight corresponding to the reception time of the base station downlink signal, and synthesizes the received signal to which the weight is multiplied. The same weight may be used regardless of the reception time.
- the base station signal reception processing unit 430 demodulates and decodes the synthesized received signal to obtain received waveform information.
- the base station signal reception processing unit 430 outputs the received waveform information to the terminal signal reception processing unit 44.
- the processing of the wireless communication system 1a when transmitting the terminal uplink signal from the terminal station 3 is the same as the processing of the wireless communication system 1 of the first embodiment shown in FIG.
- FIG. 7 is a flow chart showing the processing of the wireless communication system 1a when the base station downlink signal is transmitted from the mobile relay station 2a.
- the control unit 262 of the base station communication unit 26 of the mobile relay station 2a detects that it is the transmission start timing stored in the storage unit 261, it transmits the received waveform information to the transmission data modulation unit 263 and the MIMO transmission unit 264. (Step S311).
- the transmission data modulation unit 263 reads the received waveform information stored in the data storage unit 23 as transmission data, converts the read transmission data in parallel, and then modulates it.
- the MIMO transmission unit 264 weights the transmission data modulated by the transmission data modulation unit 263 by the weight instructed by the control unit 262 to generate a base station downlink signal which is a transmission signal transmitted from each antenna 25.
- the MIMO transmission unit 264 transmits each generated base station downlink signal from the antenna 25 by MIMO (step S312).
- the mobile relay station 2a repeats the process from step S311.
- Each antenna station 410 of the base station 4a receives a base station downlink signal from the mobile relay station 2a (step S321).
- Each antenna station 410 outputs a received signal obtained by converting the received base station downlink signal into an electric signal to the MIMO receiving unit 420.
- the MIMO receiving unit 420 synchronizes the timing of the received signal received from each antenna station 410.
- the MIMO receiving unit 420 multiplies and adds the received signal received by each antenna station 410 by a weight.
- the base station signal reception processing unit 430 demodulates the added received signal and decodes the demodulated received signal (step S322).
- the base station signal reception processing unit 430 outputs the reception waveform information obtained by decoding to the terminal signal reception processing unit 44.
- the terminal signal reception processing unit 44 performs reception processing of the terminal uplink signal represented by the waveform data included in the received waveform information by the same processing as in step S223 in the processing flow of the first embodiment shown in FIG. 5 (step). S323). That is, the terminal signal demodulation unit 441 specifies the wireless communication method used by the terminal station 3 to transmit the terminal uplink signal based on the information unique to the wireless communication method included in the received signal represented by the waveform data. The terminal signal demodulation unit 441 demodulates the received signal represented by the waveform data according to the specified wireless communication method, and outputs the symbol obtained by the demodulation to the terminal signal decoding unit 442.
- the terminal signal decoding unit 442 decodes the symbol input from the terminal signal demodulation unit 441 by the specified wireless communication method, and obtains the terminal transmission data transmitted from the terminal station 3.
- the terminal signal decoding unit 442 can also use a decoding method having a large calculation load, such as SIC.
- the base station 4a repeats the process from step S321.
- the terminal station 3 in the present embodiment calculates the distance between the mobile relay station 2a to which the signal is transmitted and its own position at the signal transmission start timing.
- the terminal station 3 determines the transmission output of the signal to be transmitted to the mobile relay station 2a based on the calculated distance.
- the transmission output required for transmitting a signal from an IoT terminal to a low earth orbit satellite in a satellite IoT system depends on the distance between the IoT terminal and the low earth orbit satellite.
- the terminal station 3 in the present embodiment has a transmission output sufficient for transmitting a signal to the mobile relay station 2a, and transmits with a smaller transmission output.
- the terminal station 3 does not transmit a signal with an unnecessarily large transmission output even when the distance between the mobile relay station 2a and its own position is short, so that power is wasted. It will not be consumed. Therefore, the terminal station 3 in the present embodiment can suppress the power consumption.
- the mobile relay station receives data from a plurality of terminal stations and collectively transmits the stored data in a short time with good quality at a timing capable of communicating with the base station. be able to.
- the mobile relay station receives the terminal uplink signal by a plurality of antennas.
- the differences from the second embodiment will be mainly described.
- FIG. 8 is a configuration diagram of the wireless communication system 1b according to the third embodiment.
- the wireless communication system 1b has a mobile relay station 2b, a terminal station 3, and a base station 4b.
- the mobile relay station 2b includes N antennas 21 (N is an integer of 2 or more), a terminal communication unit 22b, a data storage unit 23, a base station communication unit 26, and a plurality of antennas 25.
- the N antennas 21 are described as antennas 21-1 to 21-N, respectively.
- the terminal communication unit 22b has N reception units 221b and N reception waveform recording units 222b.
- the N receiving units 221b are referred to as receiving units 221b-1 to 221b-N, and the N receiving waveform recording units 222b are referred to as receiving waveform recording units 222b-1 to 222b-N.
- the receiving unit 221b-n (n is an integer of 1 or more and N or less) receives the terminal uplink signal by the antenna 21-n.
- the received waveform recording unit 222bn samples the received waveform of the terminal uplink signal received by the receiving unit 221bn, and generates waveform data showing the value obtained by sampling.
- the received waveform recording unit 222b-n writes the received waveform information in which the antenna identifier of the antenna 21-n, the reception time of the terminal uplink signal in the antenna 21-n, and the generated waveform data are set to the data storage unit 23. ..
- the antenna identifier is information that identifies the antenna 21-n.
- the data storage unit 23 stores received waveform information including waveform data of the terminal uplink signal received by each of the antennas 21-1 to 21-N.
- the base station 4b includes a plurality of antenna stations 410, a MIMO receiving unit 420, a base station signal receiving processing unit 430, and a terminal signal receiving processing unit 450.
- the terminal signal reception processing unit 450 performs reception processing of the terminal uplink signal indicated by the received waveform information. At this time, the terminal signal reception processing unit 450 performs reception processing by the wireless communication method used for transmission by the terminal station 3 to acquire terminal transmission data.
- the terminal signal reception processing unit 450 includes a distribution unit 451, N terminal signal demodulation units 452, a synthesis unit 453, and a terminal signal decoding unit 454.
- the N terminal signal demodulation units 452 are described as terminal signal demodulation units 452-1 to 452-N, respectively.
- the distribution unit 451 reads out waveform data at the same reception time from the received waveform information, and outputs the read waveform data to the terminal signal demodulation units 452-1 to 452-N according to the antenna identifier associated with the waveform data. do. That is, the distribution unit 451 outputs the waveform data associated with the antenna identifier of the antenna 21-n to the terminal signal demodulation unit 452-n.
- Each of the terminal signal demodulation units 452-1 to 452-N demodulates the signal represented by the waveform data, and outputs the symbol obtained by the demodulation to the synthesis unit 453.
- the terminal signal demodulation unit 452-n performs a process of compensating for the Doppler shift of the terminal uplink signal received by the antenna 21-n of the mobile relay station 2 with respect to the signal represented by the waveform data, and then demodulates the signal. May be good.
- the Doppler shift received by the terminal uplink signal received by each antenna 21-n is calculated in advance based on the position of the terminal station 3 and the orbit information of the LEO on which the mobile relay station 2b is mounted.
- the synthesis unit 453 adds and synthesizes the symbols input from each of the terminal signal demodulation units 452-1 to 452-N, and outputs them to the terminal signal decoding unit 454.
- the terminal signal decoding unit 454 decodes the additively synthesized symbol and obtains the terminal transmission data transmitted from the terminal station 3.
- FIG. 9 is a flow chart showing the processing of the wireless communication system 1b when the terminal uplink signal is transmitted from the terminal station 3.
- the terminal station 3 performs the same processing as the processing of steps S111 to S115 in the processing flow of the first embodiment shown in FIG.
- the terminal station 3 may transmit to another terminal station 3 by time division multiplexing, OFDM, MIMO, or the like.
- the receiving units 221b-1 to 221b-N of the mobile relay station 2b receive the terminal uplink signal transmitted from the terminal station 3 (step S421).
- the terminal uplink signal is received from only one terminal station 3 on a time-division basis for the same frequency, and cases where the terminal uplink signal is received from multiple terminal stations 3 at the same frequency at the same frequency. It may receive a terminal uplink signal.
- the received waveform recording unit 222b-n data is waveform data representing the waveform of the terminal uplink signal received by the receiving unit 221bn, and received waveform information in which the reception time and the antenna identifier of the antenna 21-n are associated with each other.
- the mobile relay station 2b repeats the process from step S421.
- step S323 the terminal signal reception processing unit 450 performs reception processing of the terminal uplink signal indicated by the received waveform information.
- the distribution unit 451 reads out waveform data having the same reception time from the received waveform information, and reads the read waveform data according to the antenna identifier associated with the waveform data, from the terminal signal demodulation unit 452-1 to Output to 452-N.
- the terminal signal demodulation units 452-1 to 452-N each use the wireless communication method used by the terminal station 3 to transmit the terminal uplink signal based on the information unique to the wireless communication method included in the received signal represented by the waveform data. Identify.
- the terminal signal demodulation units 452-1 to 452-N demodulate the received signal represented by the waveform data according to the specified wireless communication method, and output the symbol obtained by the demodulation to the synthesis unit 453.
- the synthesis unit 453 adds and synthesizes the symbols input from each of the terminal signal demodulation units 452-1 to 452-N.
- the signal transmitted by the terminal station 3 is emphasized because it has a correlation, but the influence of randomly added noise is reduced. Therefore, the diversity effect can be obtained for the terminal uplink signal received by the mobile relay station 2b from only one terminal station 3 at the same time. Further, the terminal uplink signal received by the mobile relay station 2b from a plurality of terminal stations 3 at the same time corresponds to performing MIMO communication.
- the synthesis unit 453 outputs the additively synthesized symbol to the terminal signal decoding unit 454.
- the terminal signal decoding unit 454 decodes the symbol added and synthesized by the synthesis unit 453 by the specified wireless communication method, and obtains the terminal transmission data transmitted from the terminal station 3.
- the terminal signal decoding unit 454 can also use a decoding method having a large calculation load, such as SIC.
- the terminal station 3 in the present embodiment calculates the distance between the mobile relay station 2b to which the signal is transmitted and its own position at the signal transmission start timing.
- the terminal station 3 determines the transmission output of the signal to be transmitted to the mobile relay station 2b based on the calculated distance.
- the transmission output required for transmitting a signal from an IoT terminal to a low earth orbit satellite in a satellite IoT system depends on the distance between the IoT terminal and the low earth orbit satellite.
- the terminal station 3 in the present embodiment has a transmission output sufficient for transmitting a signal to the mobile relay station 2b, and transmits with a smaller transmission output.
- the terminal station 3 does not transmit a signal with an unnecessarily large transmission output even when the distance between the mobile relay station 2b and its own position is short, so that power is wasted. It will not be consumed. Therefore, the terminal station 3 in the present embodiment can suppress the power consumption.
- the mobile relay station receives the terminal uplink signal received from the terminal station by diversity reception, MIMO reception, or the like. Therefore, the link budget with the terminal station can be improved.
- the mobile relay station receives data from a plurality of terminal stations and collectively transmits the stored data in a short time with good quality at a timing capable of communicating with the base station. be able to.
- the mobile relay station can store and store the received signal waveform information and communicate with the base station without demodulating the wireless terminal uplink signal received from the terminal station. It is transmitted wirelessly at the right timing.
- the base station performs reception processing such as demodulation / decoding on the terminal uplink signal represented by the received signal waveform in the mobile relay station. Therefore, a non-regenerative relay method that does not depend on the communication method can be applied to a wireless communication system using a low earth orbit satellite. Further, since non-regenerative relay is performed, the mobile relay station does not need to implement the wireless communication method used for the terminal station.
- the mobile relay station is mounted in the above embodiment has been described as a LEO satellite, it may be a geostationary satellite, a drone, a HAPS, or another aircraft flying over the sky.
- the wireless communication device includes a transmission unit, a timing control unit, a distance calculation unit, and an output control unit.
- the wireless communication device is the terminal station 3 in the embodiment
- the transmission unit is the transmission unit 32 and the antenna 33 in the embodiment
- the timing control unit is the timing control unit 351 in the embodiment
- the distance calculation unit Is the distance calculation unit 352 in the embodiment
- the output control unit is the output control unit 353 in the embodiment.
- the transmitter transmits a signal to another wireless communication device mounted on the mobile body.
- the other wireless communication device is the mobile relay stations 2, 2a, 2b in the embodiment
- the signal is the terminal uplink signal in the embodiment.
- the timing control unit starts transmission of a signal by the transmission unit at a timing capable of communicating with another wireless communication device.
- the distance calculation unit acquires the orbit information indicating the orbital trajectory of the moving body and the self-position information indicating the self-position, and the position of the self-position and the position of the moving body at the timing based on the orbit information and the self-position information. Calculate the relationship.
- the orbit information is the orbit information 312 in the embodiment
- the self-position information is the self-position information 313 in the embodiment.
- the output control unit controls the transmission output of the signal by the transmission unit according to the positional relationship.
- the distance calculation unit may calculate the positional relationship indicating the distance between the self-position and the position of the moving body.
- the output control unit may control the transmission output to be smaller as the distance is shorter.
- the distance calculation unit may calculate the positional relationship indicating the elevation angle from the self-position to the moving body.
- the output control unit may control the transmission output to be smaller as the elevation angle is larger.
- the wireless communication system includes a first wireless communication device, a relay device mounted on a mobile body, and a second wireless communication device.
- the first wireless communication device is the terminal station 3 in the embodiment
- the relay device is the mobile relay stations 2, 2a, 2b in the embodiment
- the second wireless communication device is the base station 4 in the embodiment. 4a and 4b.
- the first wireless communication device includes a first signal transmission unit, a timing control unit, a distance calculation unit, and an output control unit.
- the first signal transmission unit is the transmission unit 32 and the antenna 33 in the embodiment
- the timing control unit is the timing control unit 351 in the embodiment
- the distance calculation unit is the distance calculation unit 352 in the embodiment.
- the output control unit is the output control unit 353 in the embodiment.
- the first signal transmission unit transmits the first signal to the relay device.
- the first signal is the terminal uplink signal in the embodiment.
- the timing control unit starts the transmission of the first signal by the transmission unit at the timing when it can communicate with the relay device.
- the distance calculation unit acquires the orbit information indicating the orbital trajectory of the moving body and the self-position information indicating the self-position, and the position of the self-position and the position of the moving body at the timing based on the orbit information and the self-position information. Calculate the relationship.
- the orbit information is the orbit information 312 in the embodiment
- the self-position information is the self-position information 313 in the embodiment.
- the output control unit controls the transmission output of the first signal by the transmission unit according to the positional relationship.
- the relay device includes a first signal receiving unit, a storage unit, and a second signal transmitting unit.
- the first signal receiving unit is the receiving unit 221 and 221b in the embodiment
- the storage unit is the data storage unit 23 in the embodiment
- the second signal transmitting unit is the base station communication unit 24 in the embodiment. 26.
- the first signal receiving unit receives the first signal transmitted by the first wireless communication device.
- the storage unit stores waveform data indicating the waveform of the first signal received by the first signal receiving unit.
- the second signal transmission unit transmits a second signal indicating the waveform data stored in the storage unit to the second wireless communication device at a timing capable of communicating with the second wireless communication device.
- the second signal is a base station downlink signal in the embodiment.
- the second wireless communication device includes a second signal receiving unit, a second signal receiving processing unit, and a first signal receiving processing unit.
- the second signal receiving unit receives the second signal transmitted by the relay device.
- the second signal receiving unit is the antenna 41 and the receiving unit 42 in the embodiment, and the antenna station 410 and the MIMO receiving unit 420.
- the second signal reception processing unit performs reception processing of the second signal received by the second signal reception unit to acquire waveform data.
- the second signal reception processing unit is the base station signal reception processing unit 43 and the base station signal reception processing unit 430 in the embodiment.
- the first signal reception processing unit performs reception processing of the first signal indicated by the waveform data acquired by the second signal reception processing unit, and acquires the data set in the first signal by the first wireless communication device.
- the first signal reception processing unit is, for example, the terminal signal reception processing units 44 and 450 in the embodiment.
- the first signal reception processing unit can perform reception processing by a plurality of wireless methods. Further, the reception process performed by the first signal reception processing unit includes a process of compensating for the Doppler shift received by the first signal received by the first signal reception unit.
- the first signal receiving unit may receive the first signal by a plurality of antennas.
- the storage unit stores waveform data indicating the waveform of the first signal received by each of the plurality of antennas.
- the reception process performed by the first signal reception processing unit includes a process of demodulating the first signal represented by the waveform data corresponding to each of the plurality of antennas and decoding the signal obtained by synthesizing the demodulation results.
- the mobile relay stations 2, 2a, 2b, the terminal station 3, and the base stations 4, 4a, 4b in the above-described embodiment may be realized by a computer.
- a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by a computer system and executed.
- the term "computer system” as used herein includes hardware such as an OS and peripheral devices.
- the "computer-readable recording medium” refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, and a storage device such as a hard disk built in a computer system.
- a "computer-readable recording medium” is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or a client in that case. Further, the above program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system. It may be realized by using a programmable logic device such as FPGA (Field Programmable Gate Array).
- FPGA Field Programmable Gate Array
- Received waveform recording unit 241 and 261 ... Storage unit, 242, 262 ... Control unit, 243, 263 ... Transmission data modulator, 244 ... Transmitter, 264 ... MIMO transmitter, 311 ... Sensor data, 312 ... Orbit information, 313 ... Self-location information, 314 ... Output control information, 351 ... Timing control unit, 352 ... Distance calculation unit, 353 ... Output control unit, 410 ... Antenna station, 420 ... MIMO receiver, 441 ... Terminal signal demodulation unit, 442 ... Terminal signal decoding unit, 450 ... Terminal signal reception processing unit, 451 ... Distributor, 452-1 to 452-N ... Terminal signal demodulation unit, 453 ... Synthetic unit, 454 ... Terminal signal decoding unit
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Abstract
Description
図1は、第1の実施形態による無線通信システム1の構成図である。無線通信システム1は、移動中継局2と、端末局3と、基地局4とを有する。無線通信システム1が有する移動中継局2、端末局3及び基地局4のそれぞれの数は任意であるが、端末局3の数は多数であることが想定される。無線通信システム1は、即時性が要求されない情報の伝送を行う通信システムである。複数の端末局3からそれぞれ送信された情報は、移動中継局2を介して伝送され、基地局4によって収集される。
移動中継局2は、アンテナ21と、端末通信部22と、データ記憶部23と、基地局通信部24と、アンテナ25とを備える。
端末通信部22は、受信部221と、受信波形記録部222とを有する。受信部221は、アンテナ21により端末アップリンク信号を受信する。受信波形記録部222は、受信部221が受信した端末アップリンク信号の受信波形をサンプリングし、サンプリングにより得られた値を示す波形データを生成する。受信波形記録部222は、アンテナ21における端末アップリンク信号の受信時刻と、生成した波形データとを設定した受信波形情報をデータ記憶部23に書き込む。データ記憶部23は、受信波形記録部222により書き込まれた受信波形情報を記憶する。
送信制御部35は、送信部32によって送信される信号の送信出力を制御する。送信制御部35による信号の送信出力の制御処理の構成については後述される。
図4は、端末局3から端末アップリンク信号を送信する場合の無線通信システム1の処理を示すフロー図である。端末局3は、外部又は内部に備えられた図示しないセンサが検出したデータを随時取得し、取得したデータをセンサデータ311としてデータ記憶部31に書き込む(ステップS111)。
本実施形態では、移動中継局は、複数本のアンテナにより基地局ダウンリンク信号を送信する。以下では、基地局ダウンリンク信号の送信に、MIMO(Multiple Input Multiple Output)を用いる場合を例にして、第1の実施形態との差分を中心に説明する。
端末局3から端末アップリンク信号を送信する場合の無線通信システム1aの処理は、図4に示す第1の実施形態の無線通信システム1の処理と同様である。
本実施形態では、移動中継局は、複数のアンテナにより端末アップリンク信号を受信する。以下では、第2の実施形態との差分を中心に説明する。
図9は、端末局3から端末アップリンク信号を送信する場合の無線通信システム1bの処理を示すフロー図である。同図において、図4に示す第1の実施形態と処理フローと同じ処理には、同一の符号を付している。端末局3は、図4に示す第1の実施形態の処理フローにおけるステップS111~ステップS115の処理と同様の処理を行う。なお、端末局3は、他の端末局3と時分割多重、OFDM、MIMOなどにより送信を行ってもよい。
2、2a、2b…移動中継局,
3…端末局,
4、4a、4b…基地局,
21、21-1~21-N…アンテナ,
22、22b…端末通信部,
23…データ記憶部,
24、26…基地局通信部,
25…アンテナ,
31…データ記憶部,
32…送信部,
33…アンテナ,
34…受信部,
35…送信制御部,
41…アンテナ,
42…受信部,
43、430…基地局信号受信処理部,
44…端末信号受信処理部,
221、221b-1~221b-N…受信部,
222、222b-1~222b-N…受信波形記録部,
241、261…記憶部,
242、262…制御部,
243、263…送信データ変調部,
244…送信部,
264…MIMO送信部,
311…センサデータ,
312…軌道情報,
313…自己位置情報,
314…出力制御情報,
351…タイミング制御部,
352…距離算出部,
353…出力制御部,
410…アンテナ局,
420…MIMO受信部,
441…端末信号復調部,
442…端末信号復号部,
450…端末信号受信処理部,
451…分配部,
452-1~452-N…端末信号復調部,
453…合成部,
454…端末信号復号部
Claims (17)
- 移動体に搭載された他の無線通信装置へ信号を送信する送信部と、
前記他の無線通信装置と通信可能なタイミングで前記送信部による前記信号の送信を開始させるタイミング制御部と、
前記移動体の周回軌道を示す軌道情報と自己位置を示す自己位置情報とを取得し、前記軌道情報と前記自己位置情報とに基づいて前記タイミングにおける前記自己位置と前記移動体の位置との位置関係を算出する距離算出部と、
前記位置関係に応じて前記送信部による前記信号の送信出力を制御する出力制御部と、
を備える無線通信装置。 - 前記距離算出部は、前記自己位置と前記移動体の位置との間の距離を示す前記位置関係を算出する
請求項1に記載の無線通信装置。 - 前記出力制御部は、前記距離が短いほど前記送信出力をより小さくするように制御する
請求項2に記載の無線通信装置。 - 前記距離算出部は、前記自己位置から前記移動体への仰角を示す前記位置関係を算出する
請求項1に記載の無線通信装置。 - 前記出力制御部は、前記仰角が大きいほど前記送信出力をより小さくするように制御する
請求項4に記載の無線通信装置。 - 第一無線通信装置と、移動体に搭載された中継装置と、第二無線通信装置と、を有する無線通信システムであって、
前記第一無線通信装置は、
前記中継装置へ第一信号を送信する第一信号送信部と、
前記中継装置と通信可能なタイミングで前記第一信号送信部による前記第一信号の送信を開始させるタイミング制御部と、
前記移動体の周回軌道を示す軌道情報と自己位置を示す自己位置情報とを取得し、前記軌道情報と前記自己位置情報とに基づいて前記タイミングにおける前記自己位置と前記移動体の位置との位置関係を算出する距離算出部と、
前記位置関係に応じて前記第一信号送信部による前記第一信号の送信出力を制御する出力制御部と、
を備え、
前記中継装置は、
前記第一無線通信装置が送信した前記第一信号を受信する第一信号受信部と、
前記第一信号受信部が受信した前記第一信号の波形を示す波形データを記憶する記憶部と、
前記記憶部に記憶された前記波形データを示す第二信号を、前記第二無線通信装置と通信可能なタイミングで前記第二無線通信装置に送信する第二信号送信部と、
を備え、
前記第二無線通信装置は、
前記中継装置が送信した前記第二信号を受信する第二信号受信部と、
前記第二信号受信部が受信した前記第二信号の受信処理を行って前記波形データを取得する第二信号受信処理部と、
前記第二信号受信処理部が取得した前記波形データが示す前記第一信号の受信処理を行って前記第一無線通信装置が前記第一信号に設定したデータを取得する第一信号受信処理部と、
を備える、
無線通信システム。 - 前記距離算出部は、前記自己位置と前記移動体の位置との間の距離を示す前記位置関係を算出する
請求項6に記載の無線通信システム。 - 前記出力制御部は、前記距離が短いほど前記送信出力をより小さくするように制御する
請求項7に記載の無線通信システム。 - 前記距離算出部は、前記自己位置から前記移動体への仰角を示す前記位置関係を算出する
請求項6に記載の無線通信システム。 - 前記出力制御部は、前記仰角が大きいほど前記送信出力をより小さくするように制御する
請求項9に記載の無線通信システム。 - 前記第一信号受信処理部は、複数の無線方式により前記受信処理が可能である、
請求項6から10のうちいずれか一項に記載の無線通信システム。 - 前記第一信号受信処理部が行う前記受信処理は、前記第一信号受信部において受信した前記第一信号が受けたドップラーシフトを補償する処理を含む、
請求項6から10のうちいずれか一項に記載の無線通信システム。 - 前記第一信号受信部は、複数のアンテナにより前記第一信号を受信し、
前記記憶部は、複数の前記アンテナそれぞれが受信した前記第一信号の波形を示す波形データを記憶し、
前記第一信号受信処理部が行う前記受信処理は、複数の前記アンテナそれぞれに対応した前記波形データが示す前記第一信号を復調し、復調結果を合成した信号を復号する処理を含む、
請求項6から請求項12のうちいずれか一項に記載の無線通信システム。 - 前記中継装置は、低軌道衛星に備えられ、
前記第一無線通信装置及び前記第二無線通信装置は、地球上に設置される、
請求項6から請求項13のうちいずれか一項に記載の無線通信システム。 - 移動体に搭載された他の無線通信装置へ信号を送信する送信ステップと、
前記他の無線通信装置と通信可能なタイミングで前記送信ステップにおける前記信号の送信を開始させるタイミング制御ステップと、
前記移動体の周回軌道を示す軌道情報と自己位置を示す自己位置情報とを取得し、前記軌道情報と前記自己位置情報とに基づいて前記タイミングにおける前記自己位置と前記移動体の位置との位置関係を算出する距離算出ステップと、
前記位置関係に応じて前記送信ステップにおける前記信号の送信出力を制御する出力制御ステップと、
を有する無線通信方法。 - 第一無線通信装置と、移動体に搭載された中継装置と、第二無線通信装置と、を有する無線通信システムが実行する無線通信方法であって、
前記第一無線通信装置が、前記中継装置へ第一信号を送信する第一信号送信ステップと、
前記第一無線通信装置が、前記中継装置と通信可能なタイミングで前記第一信号送信ステップにおける前記第一信号の送信を開始させるタイミング制御部と、
前記第一無線通信装置が、前記移動体の周回軌道を示す軌道情報と自己位置を示す自己位置情報とを取得し、前記軌道情報と前記自己位置情報とに基づいて前記タイミングにおける前記自己位置と前記移動体の位置との位置関係を算出する距離算出ステップと、
前記第一無線通信装置が、前記位置関係に応じて前記第一信号送信ステップにおける前記第一信号の送信出力を制御する出力制御ステップと、
前記中継装置が、前記第一無線通信装置が送信した前記第一信号を受信する第一信号受信ステップと、
前記中継装置が、前記第一信号受信ステップにおいて受信された前記第一信号の波形を示す波形データを記憶する記憶ステップと、
前記中継装置が、前記記憶ステップにおいて記憶された前記波形データを示す第二信号を、前記第二無線通信装置と通信可能なタイミングで前記第二無線通信装置に送信する第二信号送信ステップと、
前記第二無線通信装置が、前記中継装置が送信した前記第二信号を受信する第二信号受信ステップと、
前記第二無線通信装置が、前記第二信号受信ステップにおいて受信された前記第二信号の受信処理を行って前記波形データを取得する第二信号受信処理ステップと、
前記第二無線通信装置が、前記第二信号受信処理ステップにおいて取得された前記波形データが示す前記第一信号の受信処理を行って前記第一無線通信装置が前記第一信号に設定したデータを取得する第一信号受信処理ステップと、
を有する無線通信方法。 - 請求項1から5のうちいずれか一項に記載の無線通信装置としてコンピュータを機能させるためのプログラム。
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JP2006197488A (ja) * | 2005-01-17 | 2006-07-27 | Toshiba Corp | 無線中継装置 |
JP2013131930A (ja) * | 2011-12-21 | 2013-07-04 | Kddi Corp | 非再生中継装置、無線通信システムおよび無線中継方法 |
JP2014204177A (ja) * | 2013-04-02 | 2014-10-27 | 国立大学法人東北大学 | 衛星を利用したデータ中継システムおよびデータ中継方法 |
JP2019047262A (ja) * | 2017-08-31 | 2019-03-22 | 日本電気株式会社 | Leo通信端末、leo通信サービスシステム、leo通信端末用プログラム、及びleo通信端末省電力制御方法 |
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US5874913A (en) * | 1996-08-29 | 1999-02-23 | Motorola, Inc. | Method and apparatus to compensate for Doppler frequency shifts in a satellite communication system |
JP2006197488A (ja) * | 2005-01-17 | 2006-07-27 | Toshiba Corp | 無線中継装置 |
JP2013131930A (ja) * | 2011-12-21 | 2013-07-04 | Kddi Corp | 非再生中継装置、無線通信システムおよび無線中継方法 |
JP2014204177A (ja) * | 2013-04-02 | 2014-10-27 | 国立大学法人東北大学 | 衛星を利用したデータ中継システムおよびデータ中継方法 |
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