WO2022137518A1 - 中継装置および中継方法 - Google Patents
中継装置および中継方法 Download PDFInfo
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- WO2022137518A1 WO2022137518A1 PCT/JP2020/048782 JP2020048782W WO2022137518A1 WO 2022137518 A1 WO2022137518 A1 WO 2022137518A1 JP 2020048782 W JP2020048782 W JP 2020048782W WO 2022137518 A1 WO2022137518 A1 WO 2022137518A1
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- 238000004891 communication Methods 0.000 claims abstract description 82
- 230000005540 biological transmission Effects 0.000 claims abstract description 72
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- 230000003595 spectral effect Effects 0.000 description 12
- 230000015572 biosynthetic process Effects 0.000 description 9
- 238000003786 synthesis reaction Methods 0.000 description 9
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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
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
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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
- H04B7/155—Ground-based stations
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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
Definitions
- the present invention relates to a relay device and a relay method.
- IoT Internet of Things
- UAV Unmanned Aerial Vehicle
- geostationary satellite see, for example, Non-Patent Document 1.
- the channel capacity related to wireless communication between the relay device and the base station changes as the relay device moves. Therefore, depending on the timing of communication, the amount of information is small with respect to the channel capacity, and communication resources may not be used effectively. On the other hand, depending on the timing of communication, there is a possibility that the data received by the base station may be lost due to the large amount of information relative to the channel capacity.
- an object of the present invention is to provide a relay device and a relay method in which a relay device that communicates while moving can effectively utilize communication resources while preventing loss of received data.
- One aspect of the present invention is a relay device that performs communication while moving, a receiving unit that receives a signal from a transmitting terminal, a capacity specifying unit that specifies a channel capacity related to wireless communication with a base station, and the received unit. It is a relay device including a data generation unit that generates waveform data representing a signal so that the data size of the waveform data increases as the channel capacity increases, and a transmission unit that transmits the waveform data to the base station. ..
- One aspect of the present invention is a step in which a relay device that communicates while moving receives a signal from a transmitting terminal, a step in which the relay device specifies a channel capacity related to wireless communication with a base station, and the relay.
- This is a relay method including a step of transmitting to the base station.
- a relay device that communicates while moving can effectively utilize communication resources while preventing loss of received data.
- 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 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 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 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, and wirelessly transmits these received data to the base station 4.
- 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.
- drones require batteries and HAPS require solar panels.
- 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.
- 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 communicates while moving at high speed, a Doppler shift occurs in the radio signal. Further, the relay station mounted on the LEO has a smaller link budget than the relay station mounted on the drone or HAPS. Therefore, the mobile relay station 2 receives the radio signal from the terminal station 3 by the plurality of antennas, and transmits the radio signal to the base station 4 by the plurality of antennas. Communication quality can be improved by the diversity effect and beamforming effect of communication using multiple antennas.
- MIMO Multiple Input Multiple Output
- the method of relaying to the base station 4 may be other than MIMO.
- the mobile relay station 2 includes a plurality of first antennas 21, a terminal communication unit 22, a base station communication unit 24, and a plurality of second antennas 25.
- the terminal communication unit 22 includes a plurality of reception units 221, a synthesis unit 222, a spectrum conversion unit 223, a storage unit 224, a reception schedule determination unit 225, and a parameter determination unit 226.
- the plurality of receiving units 221 are provided corresponding to the plurality of first antennas 21, respectively. Each receiving unit 221 receives a signal via the corresponding first antenna 21.
- the synthesizing unit 222 synthesizes the signals received by the plurality of receiving units 221 according to the synthesizing parameters.
- the synthesis unit 222 reproduces the terminal uplink signal by synthesizing the signal.
- the synthesis parameters are represented, for example, by the phase and amplitude offsets of each first antenna 21.
- the spectrum conversion unit 223 converts the signal synthesized by the synthesis unit 222 into a frequency spectrum.
- the spectrum transforming unit 223 obtains the frequency spectrum of the signal received by, for example, FFT (Fast Fourier Transform).
- the spectrum conversion unit 223 records spectrum data representing the generated frequency spectrum in the storage unit 224. Spectral data is represented by a combination of frequency and power at that frequency.
- the storage unit 224 stores the position data of the terminal station 3 and the orbit data of the LEO satellite.
- the position data of the terminal station 3 is represented by, for example, latitude and longitude.
- the LEO orbit data is data that can obtain the position, speed, moving direction, etc. of the LEO satellite at an arbitrary time.
- the storage unit 224 stores the spectral data of the terminal uplink signal.
- the reception schedule determination unit 225 specifies the timing of receiving a signal from each terminal station 3 based on the position data and the trajectory data of the terminal station 3 stored in the storage unit 224.
- the parameter determination unit 226 calculates a composite parameter for each time based on the reception timing of the signal determined by the reception schedule determination unit 225 and the positional relationship between the mobile relay station 2 and the terminal station 3 of the communication partner at the reception timing. ..
- the composition parameter for each time may be calculated in advance, or the composition parameter may be always constant.
- the base station communication unit 24 transmits waveform data representing the waveform of the terminal uplink signal received by the terminal communication unit 22 to the base station 4 by MIMO.
- the base station communication unit 24 transmits the storage unit 241, the transmission schedule determination unit 242, the control unit 243, the MIMO communication unit 244, the capacity specifying unit 245, the target band determination unit 246, the data generation unit 247, and the transmission unit. It is provided with a data modulation unit 248.
- the storage unit 241 stores the communication time zone between the position of the base station 4 and the base station 4 previously determined from the orbit of the LEO satellite. Further, the storage unit 241 stores in advance the weight of the base station downlink signal transmitted from each second antenna 25 for each transmission time in the communication time zone.
- the transmission time may be represented by, for example, the elapsed time from the transmission start timing.
- the weight for each transmission time is calculated based on the orbit data of the LEO satellite and the position of each antenna station 41.
- the transmission schedule determination unit 242 determines the transmission time zone for each waveform data corresponding to the spectrum data based on the number of spectrum data stored in the storage unit 224 and the communication time zone.
- the transmission schedule determination unit 242 determines the transmission time of each waveform data by, for example, dividing the length of the communication time zone by the number of spectral data, and divides the communication time zone by the transmission time to divide the communication time zone into the transmission time of the individual waveform data. Determine the transmission time zone.
- the control unit 243 instructs the MIMO communication unit 244 to wait for each transmission time read from the storage unit 241.
- the MIMO communication unit 244 establishes MIMO communication with the base station 4 by a predetermined protocol.
- the capacity specifying unit 245 specifies the channel capacity in communication with the base station 4 at the transmission start timing of the individual waveform data determined by the transmission schedule determination unit 242. For example, the capacity specifying unit 245 can obtain the channel capacity from the error rate in the signal received by the MIMO communication unit 244. Further, for example, the capacitance specifying unit 245 may receive a control signal including the value of the channel capacitance from the base station 4.
- the target band determination unit 246 determines the target band, which is the frequency band to be sampled, among the spectral data stored in the storage unit 224, based on the channel capacity specified by the capacity identification unit 245.
- the target band determination unit 246 widens the target band as the channel capacity increases.
- the target band determination unit 246 narrows the target band as the channel capacity becomes smaller.
- the target band determination unit 246 may determine the target band by the following procedure.
- the target band determination unit 246 obtains the data size of the waveform data that can be transmitted to the base station 4 from the length of the transmission time of the waveform data corresponding to the terminal uplink signal to be transmitted and the channel capacity.
- the target band determination unit 246 determines the number of samples that can be transmitted by dividing the obtained data size by the data size per sample.
- the target bandwidth determination unit 246 determines the target bandwidth by multiplying the number of samples by the sampling interval of the spectral data.
- the target band determination unit 246 determines a band having a determined target bandwidth and including a reference frequency as the target band.
- the target band may be determined in advance on a one-to-one basis with respect to the channel capacity.
- the data generation unit 247 generates waveform data by extracting the portion of the spectrum data stored in the storage unit 224 related to the target band determined by the target band determination unit 246 at a predetermined sampling interval.
- the waveform data is represented by, for example, a combination of a frequency value and a power value related to the frequency.
- the transmission data modulation unit 248 converts the waveform data generated by the data generation unit 247 into a parallel signal and then modulates it.
- the modulated parallel signal is weighted as a base station downlink signal by a weight instructed by the control unit 243 and transmitted from each second antenna 25.
- the terminal station 3 includes a data storage unit 31, a transmission unit 33, and one or more antennas 34.
- the data storage unit 31 stores sensor data and orbit data of the LEO satellite.
- the transmission unit 33 determines the transmission time zone of the terminal uplink signal based on the orbit data of the LEO satellite. That is, the transmission unit 33 determines the time zone in which the position where the terminal station 3 exists is within the coverage of the first antenna 21 included in the mobile relay station 2 as the transmission time zone of the terminal uplink signal.
- the transmission unit 33 wirelessly transmits a terminal uplink signal in which the sensor data stored in the data storage unit 31 is set as terminal transmission data from the antenna 34.
- the transmission unit 33 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 33 may transmit to another terminal station 3 by time division multiplexing, OFDM (Orthogonal Frequency Division Multiplexing), MIMO, or the like.
- the transmission unit 33 determines the channel and transmission timing used by the station to transmit the terminal uplink signal by a method predetermined in the wireless communication method to be used. Further, the transmission unit 33 may form a beam of signals transmitted from a plurality of antennas 34 by a method predetermined in the wireless communication method to be used.
- the base station 4 includes a plurality of antenna stations 41, a MIMO receiving unit 42, a base station signal receiving processing unit 43, and a terminal signal receiving processing unit 44.
- the antenna station 41 is arranged at a position away from the other antenna stations 41 so that the difference in the arrival angles of the signals from each of the plurality of second antennas 25 of the mobile relay station 2 becomes large.
- Each antenna station 41 converts the base station downlink signal received from the mobile relay station 2 into an electric signal and outputs it to the MIMO receiving unit 42.
- the MIMO receiving unit 42 aggregates the base station downlink signals received from the plurality of antenna stations 41.
- the MIMO receiving unit 42 stores the weight for each reception time for the base station downlink signal received by each antenna station 41 based on the orbit data of the LEO satellite and the position of each antenna station 41. For example, the reception time may be represented by the elapsed time from the timing of the start of reception.
- the MIMO receiving unit 42 multiplies the base station downlink signal input from each antenna station 41 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 43 demodulates and decodes the synthesized received signal to obtain demodulation information.
- the base station signal reception processing unit 43 outputs demodulation information to the terminal signal reception processing unit 44.
- the terminal signal reception processing unit 44 performs reception processing of the terminal uplink signal.
- the terminal signal reception processing unit 44 includes a terminal signal decoding unit 441.
- the terminal signal decoding unit 441 decodes the symbol of the terminal uplink signal from the waveform data indicated by the demodulation information, and obtains the terminal transmission data transmitted from the terminal station 3. That is, the terminal signal decoding unit 441 decodes the symbol of the terminal uplink signal by converting the frequency domain waveform indicated by the waveform data into the time domain waveform.
- FIG. 2 is a flow chart showing the processing of the wireless communication system 1 according to the first embodiment.
- the terminal station 3 acquires data detected by a sensor (not shown) provided outside or inside, and writes the acquired data in the data storage unit 31 (step S101).
- the transmission unit 33 determines whether or not the current time is included in the transmission time zone of the uplink signal based on the position of the terminal station 3 and the orbit data of the LEO satellite (step S102). When the transmission unit 33 determines that the current time is not included in the transmission time zone of the uplink signal (step S102: NO), the terminal station 3 returns the process to step S101.
- step S102 when the transmission unit 33 determines that the current time is included in the transmission time zone of the uplink signal (step S102: YES), the sensor data is read from the data storage unit 31 and the read sensor data is used as terminal transmission data.
- the transmission unit 33 wirelessly transmits the terminal uplink signal set with the terminal transmission data from the antenna 34 (step S103).
- the terminal station 3 returns the process to step S102. As a result, the terminal station 3 continues to transmit the uplink signal during the transmission time zone.
- the reception schedule determination unit 225 of the mobile relay station 2 determines the terminal station 3 to be received of the terminal uplink signal at each time based on the position data and the orbital data of the terminal station 3 stored in the storage unit 224 (step). S121).
- the parameter determination unit 226 sets the synthesis parameters of the synthesis unit 222 at the current time based on the terminal station 3 to be received and the orbit data determined by the reception schedule determination unit 225 (step S122).
- the plurality of receiving units 221 of the mobile relay station 2 receive the terminal uplink signal transmitted from the terminal station 3 (step S123).
- 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 synthesizing unit 222 synthesizes the terminal uplink signals received by the plurality of receiving units 221 according to the synthesizing parameters set in step S122 (step S124).
- the spectrum conversion unit 223 converts the signal synthesized by the synthesis unit 222 into spectrum data and records it in the storage unit 224 (step 125).
- the transmission schedule determination unit 242 refers to the storage unit 241 and determines whether or not the current time is included in the communication time zone with the base station 4 (step S126). If the current time is not included in the communication time zone with the base station 4 (step S126: NO), the process returns to step S121. On the other hand, when the current time is included in the communication time zone with the base station 4 (step S126: YES), the transmission schedule determination unit 242 determines the number of spectral data stored by the storage unit 224 and the communication time with the base station 4. The transmission time for each waveform data is determined based on the length of the band (step S127).
- the base station communication unit 24 selects the spectral data stored in the storage unit 224 one by one in the order of transmission (step S128), and executes the processes of steps S129 to S131 below.
- the capacity specifying unit 245 specifies the channel capacity in communication with the base station 4 (step S129).
- the target band determination unit 246 determines the target band for sampling the spectral data selected in step S128 based on the calculation using the length of the transmission time of the waveform data determined in step S127 and the channel capacity specified in step S129. (Step S130).
- the data generation unit 247 generates waveform data by extracting the portion of the spectrum data selected in step S128 related to the target band determined in step S130 at a predetermined sampling interval (step S131).
- the transmission data modulation unit 248 performs parallel conversion of the waveform data generated in step S131 and then modulates the waveform data.
- the MIMO communication unit 244 weights the transmission data modulated by the transmission data modulation unit 248 by the weight instructed by the control unit 243 to generate a base station downlink signal transmitted from each second antenna 25.
- the MIMO communication unit 244 transmits each generated base station downlink signal from the second antenna 25 by MIMO during the transmission time zone determined in step S127 (step S132).
- the mobile relay station 2 transmits the waveform data related to all the spectral data stored in the storage unit 224, the process returns to step S121.
- Each antenna station 41 of the base station 4 receives the base station downlink signal from the mobile relay station 2 (step S141).
- Each antenna station 41 outputs a received signal obtained by converting the received base station downlink signal into an electric signal to the MIMO receiving unit 42.
- the MIMO receiving unit 42 synchronizes the timing of the received signal received from each antenna station 41.
- the MIMO receiving unit 42 synthesizes the received signal received by each antenna station 41 based on the wait.
- the base station signal reception processing unit 43 demodulates the combined received signal (step S142).
- the base station signal reception processing unit 43 outputs the waveform data obtained by decoding the demodulated reception signal to the terminal signal reception processing unit 44.
- the terminal signal decoding unit 441 of the terminal signal reception processing unit 44 decodes the symbol of the terminal uplink signal indicated by the waveform data, and obtains the terminal transmission data transmitted from the terminal station 3 (step S143).
- the terminal signal decoding unit 441 can also use a decoding method having a large calculation load, such as SIC (Successive Interference Cancellation).
- SIC Successessive Interference Cancellation
- the mobile relay station 2 has a different band for sampling waveform data based on the channel capacity related to communication with the terminal station 3. Specifically, the mobile relay station 2 generates waveform data so that the larger the channel capacity, the wider the target band. As a result, the mobile relay station 2 can effectively utilize the communication resource while preventing the reception data from being lost. That is, the wireless communication system 1 can transmit information in a wide band when the channel capacity is large.
- the mobile relay station 2 according to the first embodiment adjusts the data size of the waveform data according to the width of the target band.
- the mobile relay station 2 according to the second embodiment adjusts the data size of the waveform data according to the sampling interval.
- FIG. 3 is a configuration diagram of the wireless communication system 1 according to the second embodiment.
- the wireless communication system 1 according to the second embodiment has a different configuration of the mobile relay station 2 from the first embodiment.
- the mobile relay station 2 according to the second embodiment includes an interval determination unit 249 instead of the target band determination unit 246.
- the interval determination unit 249 determines the sampling interval of the spectral data stored in the storage unit 224 based on the channel capacity specified by the capacity identification unit 245. The interval determination unit 249 narrows the sampling interval as the channel capacitance increases. On the other hand, the target band determination unit 246 increases the sampling interval as the channel capacitance becomes smaller. For example, the interval determination unit 249 may determine the sampling interval by the following procedure. The interval determination unit 249 obtains the data size of the waveform data that can be transmitted to the base station 4 from the length of the transmission time of the waveform data corresponding to the terminal uplink signal to be transmitted and the channel capacity. The interval determination unit 249 determines the number of samples that can be transmitted by dividing the obtained data size by the data size per sample. The interval determination unit 249 determines the sampling interval by dividing the predetermined sampling target bandwidth by the number of samples. The sampling interval may be determined in advance on a one-to-one basis with respect to the channel capacity.
- the interval determination unit 249 may determine the sampling interval so that the logarithmic representation of the frequency to be sampled becomes a constant interval. That is, the interval determination unit 249 may determine the sampling interval so that when the data waveform is plotted on a semi-logarithmic graph, the intervals between the plots on the frequency axis represented by the logarithm are equal.
- FIG. 4 is a flow chart showing the processing of the wireless communication system 1 according to the second embodiment.
- the operation of the wireless communication system 1 according to the second embodiment is partially different from that of the first embodiment.
- the wireless communication system 1 executes the following steps S230 and S231 in place of steps S130 and S131 according to the first embodiment.
- the interval determining unit 249 uses the length of the transmission time of the waveform data determined in step S127 and the channel capacity specified in step S129. Based on the calculation, the sampling interval of the spectral data selected in step S128 is determined (step S230).
- the data generation unit 247 generates waveform data by extracting a portion of the spectral data selected in step S128 related to a predetermined frequency region at a sampling interval determined in step S230 (step S231).
- the transmission data modulation unit 248 converts the waveform data generated in step S231 in parallel and then modulates it.
- the MIMO communication unit 244 weights the transmission data modulated by the transmission data modulation unit 248 by the weight instructed by the control unit 243 to generate a base station downlink signal transmitted from each second antenna 25.
- the MIMO communication unit 244 transmits each generated base station downlink signal from the second antenna 25 by MIMO during the transmission time zone determined in step S127 (step S132).
- the mobile relay station 2 makes the sampling interval of the waveform data different based on the channel capacity related to the communication with the terminal station 3. Specifically, the mobile relay station 2 generates waveform data so that the sampling interval becomes narrower as the channel capacitance increases. As a result, the mobile relay station 2 can effectively utilize the communication resource while preventing the reception data from being lost. That is, the wireless communication system 1 can improve the accuracy of the waveform to be reproduced by narrowing the sampling interval when the channel capacity is large.
- the mobile relay station 2 according to the second embodiment has a fixed sampling target band and changes the sampling interval according to the channel capacity, but is not limited to this.
- the mobile relay station 2 according to another embodiment may change both the sampling interval and the sampling target band according to the channel capacity.
- the mobile relay station 2 generates waveform data so that the larger the channel capacity related to the communication with the terminal station 3, the larger the data size. As a result, the mobile relay station 2 can effectively utilize the communication resource while preventing the reception data from being lost.
- the mobile relay station 2 includes a processor, a memory, an auxiliary storage device, and the like connected by a bus, and functions as a device including a terminal communication unit 22 and a base station communication unit 24 by executing a relay program.
- the processor include a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), a microprocessor and the like.
- the relay program may be recorded on a computer-readable recording medium.
- the computer-readable recording medium is, for example, a storage device such as a magnetic disk, a magneto-optical disk, an optical disk, or a semiconductor memory.
- the relay program may be transmitted via a telecommunication line.
- All or part of each function of the mobile relay station 2 may be realized by using a custom LSI (Large Scale Integrated Circuit) such as an ASIC (Application Specific Integrated Circuit) or a PLD (Programmable Logic Device).
- LSI Large Scale Integrated Circuit
- ASIC Application Specific Integrated Circuit
- PLD Programmable Logic Device
- Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array).
- Such integrated circuits are also included as an example of a processor.
- the mobile relay station 2 may be configured by a single computer, or the configuration of the mobile relay station 2 is divided into a plurality of computers, and the plurality of computers cooperate with each other. By doing so, it may function as a mobile relay station 2.
- the data generation unit 247 generates waveform data by sampling the spectrum data representing the frequency domain waveform generated by the spectrum conversion unit 223, but the present invention is not limited to this.
- the data generation unit 247 may generate waveform data by sampling a time domain waveform.
- the data generation unit 247 may make the sampling interval of the signal synthesized by, for example, the synthesis unit 222 different according to the channel capacitance.
- the mobile relay station 2 determines the length of the waveform data transmission time according to the number of received terminal uplink signals, and determines the data size of the waveform data based on the length of the transmission time.
- the length of the transmission time may be fixed regardless of the number of terminal uplink signals.
- the mobile relay station 2 according to another embodiment may determine the data size of the waveform data regardless of the length of the transmission time. Even in these cases, the mobile relay station 2 can effectively utilize the communication resource while preventing the loss of the received data by determining the data size of the waveform data at least based on the channel capacity.
- the mobile relay station 2 is mounted on the LEO satellite, but the present invention is not limited to this.
- the mobile relay station 2 according to another embodiment may be mounted on another aircraft such as a geostationary satellite, a drone, or HAPS.
- the mobile relay station 2 moves over the earth, and the terminal station 3 and the base station 4 are provided on the earth, but the wireless communication system 1 according to another embodiment is the earth such as the moon. It may be targeted at a celestial body other than the above.
- the terminal station 3 autonomously specifies the transmission timing of the terminal uplink signal, but the other embodiments are not limited to this.
- the terminal station 3 may receive a notification of the transmission timing by a beacon signal or the like from the mobile relay station 2 and transmit the terminal uplink signal according to the transmission timing.
- the capacity specifying unit 245 of the mobile relay station 2 specifies the channel capacity related to the communication with the base station 4 by MIMO communication with the base station 4, but is not limited to this.
- the capacity specifying unit 245 stores the channel capacity related to communication with the base station 4 in advance in the storage unit 241 at each time, and reads the channel capacity from the storage unit 241. good.
- the capacity specifying unit 245 obtains the elevation angle of the mobile relay station 2 with respect to the base station 4 based on the track data and the position of the base station 4, and estimates the channel capacity from the elevation angle. good.
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Abstract
Description
図1は、第1の実施形態に係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。
移動中継局2は、複数の第1アンテナ21と、端末通信部22と、基地局通信部24と、複数の第2アンテナ25とを備える。端末通信部22は、複数の受信部221と、合成部222と、スペクトル変換部223と、記憶部224と、受信スケジュール決定部225と、パラメータ決定部226とを有する。複数の受信部221は、それぞれ複数の第1アンテナ21に対応して設けられる。各受信部221は、対応する第1アンテナ21を介して信号を受信する。合成部222は、複数の受信部221が受信した信号を、合成パラメータに従って合成する。合成部222は、信号の合成により端末アップリンク信号を再生する。合成パラメータは、例えば各第1アンテナ21の位相と振幅のオフセットによって表される。
図2は、第1の実施形態に係る無線通信システム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取得し、取得したデータをデータ記憶部31に書き込む(ステップS101)。送信部33は、端末局3の位置とLEO衛星の軌道データに基づいて、現在時刻がアップリンク信号の送信時間帯に含まれるか否かを判定する(ステップS102)。送信部33が現在時刻がアップリンク信号の送信時間帯に含まれないと判定した場合(ステップS102:NO)、端末局3はステップS101に処理を戻す。
移動中継局2は、記憶部224が記憶するすべてのスペクトルデータに係る波形データを送信すると、処理をステップS121に戻す。
第1の実施形態に係る移動中継局2は、波形データのデータサイズを対象帯域の広さによって調整する。これに対し、第2の実施形態に係る移動中継局2は、波形データのデータサイズをサンプリング間隔によって調整する。
中継プログラムは、コンピュータ読み取り可能な記録媒体に記録されてもよい。コンピュータ読み取り可能な記録媒体とは、例えば磁気ディスク、光磁気ディスク、光ディスク、半導体メモリ等の記憶装置である。中継プログラムは、電気通信回線を介して送信されてもよい。
なお、移動中継局2の各機能の全て又は一部は、ASIC(Application Specific Integrated Circuit)やPLD(Programmable Logic Device)等のカスタムLSI(Large Scale Integrated Circuit)を用いて実現されてもよい。PLDの例としては、PAL(Programmable Array Logic)、GAL(Generic Array Logic)、CPLD(Complex Programmable Logic Device)、FPGA(Field Programmable Gate Array)が挙げられる。このような集積回路も、プロセッサの一例に含まれる。
以上、図面を参照して一実施形態について詳しく説明してきたが、具体的な構成は上述のものに限られることはなく、様々な設計変更等をすることが可能である。すなわち、他の実施形態においては、上述の処理の順序が適宜変更されてもよい。また、一部の処理が並列に実行されてもよい。
Claims (5)
- 移動しながら通信を行う中継装置であって
送信端末から信号を受信する受信部と、
基地局との無線通信に係るチャネル容量を特定する容量特定部と、
受信した前記信号を表す波形データを、前記チャネル容量が大きいほど前記波形データのデータサイズが大きくなるように生成するデータ生成部と、
前記波形データを前記基地局へ送信する送信部と
を備える中継装置。 - 前記送信端末から受信した信号を周波数スペクトルに変換するスペクトル変換部と、
前記データ生成部は、前記周波数スペクトルのサンプリングにより、前記チャネル容量が大きいほど前記周波数スペクトルのサンプルサイズが大きくなるように前記波形データを生成する
請求項1に記載の中継装置。 - 前記データ生成部は、前記チャネル容量が大きいほど、前記周波数スペクトルのうちサンプリングの対象とする周波数帯域を広くする
請求項2に記載の中継装置。 - 前記データ生成部は、前記チャネル容量が大きいほど、サンプリング間隔を狭くする
請求項2又は請求項3に記載の中継装置。 - 移動しながら通信を行う中継装置が、送信端末から信号を受信するステップと、
前記中継装置が、基地局との無線通信に係るチャネル容量を特定するステップと、
前記中継装置が、受信した前記信号を表す波形データを、前記チャネル容量が大きいほど前記波形データのデータサイズが大きくなるように生成するステップと、
前記中継装置が、前記波形データを前記基地局へ送信するステップと
を有する中継方法。
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US20200177272A1 (en) * | 2018-11-29 | 2020-06-04 | Astranis Space Technologies Corp. | Adjustable payload system for small geostationary (geo) communication satellites |
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US9118455B2 (en) * | 2009-06-16 | 2015-08-25 | Viasat, Inc. | Dynamic bandwidth resource allocation for satellite downlinks |
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