JP4380584B2 - Satellite communication system - Google Patents

Description

  The present invention relates to a satellite communication system using an access method using an initial access signal in an uplink from a terminal transmission unit.

  Hereinafter, a conventional satellite communication system will be described with reference to the drawings. FIG. 14 is a block diagram showing a satellite communication system applied to an initial access signal from a terminal transmission unit in an uplink of a conventional satellite communication system. In FIG. 14, 1 is a satellite, 2 is a ground station receiver, 6 is a terminal transmitter, 13 is a terminal receiver, 15 is a receiver, 29 is a receiver, 30 is a transmitter, 33 is a Doppler extractor, and 34 is It is a Doppler correction unit.

  The operation of the satellite communication system configured as described above will be described below.

  Before the line connection, the terminal receiving unit 13 receives the downlink initial access signal from the satellite 1 at the receiver 15, and thereby calculates the Doppler shift amount of the downlink including the satellite oscillator component from the Doppler extraction unit. Extract at 33. In terminal transmitter 6, first, Doppler correction unit 34 multiplies the result of Doppler extraction unit 33 by the ratio of the uplink frequency and the downlink frequency to estimate the Doppler shift amount in the uplink, and its inversion polarity. Determine the amount of correction. Then, the transmitter 30 transmits the initial access signal by adding the correction amount to the transmission frequency.

  In the ground station receiving unit 2, the receiving unit 29 receives the initial access signal corrected in the uplink Doppler shift amount from the terminal transmitting unit 6 that has arrived through the satellite 1 and relays between the ground station and the terminal. Are connected.

  However, in the conventional satellite communication system described above, the initial access signal frequency in the uplink from the satellite received at the ground station includes a satellite oscillator error component. Therefore, when the channel frequency interval is not sufficient, the error component interferes with the line in the other link, and when the channel frequency interval is sufficient to avoid this, the system capacity is reduced accordingly. It had the problem that it ended up.

  In this satellite communication system, it is required that the initial access signal in the uplink does not interfere with other links in the link or interfere with the system capacity improvement.

  An object of the present invention is to provide a satellite communication system in which an initial access signal in an uplink does not interfere with a line in another link and does not interfere with system capacity improvement.

In order to solve this problem, a satellite communication system according to the present invention includes a satellite that relays an uplink signal, a terminal transmitter that transmits the uplink signal, and a ground station receiver that receives the downlink signal from the satellite. The terminal transmission unit maps a specific hopping pattern on the time axis to the initial access signal and a non-initial access transmission unit that transmits other signals excluding the initial access signal Controls the initial access signal modulator, the initial access CW transmitter that turns on and off the transmission output of the high-frequency carrier signal on the channel boundary, and the initial access CW transmitter continuously after the power is turned on An intermittent transmission control unit that performs intermittent transmission, and the ground station reception unit converts the downlink signal into a baseband signal. A CW receiving unit for access, an intermittent signal Doppler shift compensating unit that extracts a Doppler shift amount of the terminal transmitting unit from the intermittent transmission timing obtained from the baseband signal, and performs Doppler compensation on the downlink signal based on the extracted Doppler shift amount; An initial access demodulating unit that demodulates an initial access signal from the output of the initial access CW receiving unit, and a non-initial access receiving unit that receives and demodulates signals other than the initial access signal, and a terminal transmitting unit Is output after the power is turned on by the intermittent transmission control unit, and the initial access CW transmission unit turns on and off the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1. The satellite communication system is characterized in that intermittent transmission control is performed.

  With the above configuration, the present invention provides a satellite communication system in which the initial access signal in the uplink does not interfere with other links in the link and does not hinder system capacity improvement.

Further, according to the satellite communication system of the present invention, the initial access signal, depending on the hopping pattern indicated by the different hopping signal the normal modulation signal at the time of linking, placed on a high frequency carrier signal in the guard band Therefore, there is an advantageous effect that the initial access signal in the uplink does not interfere with a line in another link and does not interfere with system capacity improvement.

Further, initial access signal, as according to the hopping pattern indicated by the different hopping signal the normal modulation signal at the time of link, is transmitted placed on high frequency carrier signal is on the boundary of each channel frequency Therefore, it is possible to obtain an advantageous effect that it does not interfere with a line in another link and does not become an obstacle to improving the system capacity.

Further, since the land upper station receiver can understand the Doppler shift amount by monitoring the intermittent signal transmitted from the terminal transmission unit, it is possible to send the Doppler shift amount to the terminal, in other link line Therefore, it is possible to obtain an advantageous effect that it does not cause interference with the system capacity and does not become an impediment to improving system capacity.

Further, the initial access signal before times line to link, in accordance with a hopping pattern indicated by the different hopping signal the normal modulation signal at the time of linking, placed on a high frequency carrier signal frequency is scanned control transmitter Therefore, there is no need for scanning at the ground station receiver, and the device scale of the ground station receiver can be simplified accordingly, and the system capacity can be improved accordingly.

Further, the initial access signal before times line to link, in accordance with the hopping pattern indicated by the different hopping signal the normal modulation signal at the time of linking, a high frequency in the high frequency carrier signal or guard band in free channel Since the transmission is carried on a carrier wave signal, there is an advantageous effect that the initial access signal in the uplink does not interfere with a line in another link and does not interfere with system capacity improvement. can get.

The initial access signal before times line to link, according to the hopping pattern length which is controlled in accordance with the traffic amount of the uplink, the frequency of the carrier signal in the high frequency carrier signal or guard band in free channel Since the data is transmitted after being loaded, there is an advantageous effect that the initial access signal in the uplink does not interfere with a line in another link and does not interfere with system capacity improvement.

According to a first aspect of the present invention, there is provided a satellite communication system having a satellite that relays an uplink signal, a terminal transmitter that transmits the uplink signal, and a ground station receiver that receives the downlink signal from the satellite. The terminal transmission unit includes a non-initial access transmission unit that transmits other signals except the initial access signal, and an initial access signal modulation that maps a specific hopping pattern on the time axis to the initial access signal. And the initial access CW transmitter that turns on and off the transmission output of the high-frequency carrier wave signal on the channel boundary according to the hopping pattern, and the initial access CW transmitter continuously after the power is turned on to intermittently transmit An intermittent transmission control unit that performs an initial transmission, a ground station reception unit, an initial access CW reception unit that converts a downlink signal into a baseband signal, and a base An intermittent signal Doppler shift compensation unit that extracts a Doppler shift amount of the terminal transmission unit from the intermittent transmission timing obtained from the received signal, performs Doppler compensation on the downlink signal based on the extracted Doppler shift amount, and an initial access CW reception unit An initial access demodulating unit that demodulates the initial access signal from the output, and a non-initial access receiving unit that receives and demodulates signals other than the initial access signal, and the carrier signal output by the terminal transmitting unit is intermittent After the power is turned on by the transmission control unit, the initial access CW transmission unit turns on and off the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 to control intermittent transmission. This is a featured satellite communication system.

According to a second aspect of the present invention, a satellite that relays an uplink signal, a terminal receiver that receives a downlink signal from the satellite, a terminal transmitter that transmits an uplink signal, and a downlink signal are received. A satellite communication system having a ground station receiver for transmitting and a ground station transmitter for transmitting an uplink signal, wherein the terminal receiver receives a receiver for receiving and demodulating a downlink signal, and a demodulated downlink signal A terminal free channel information extracting unit for extracting uplink terminal free channel information, a terminal transmitting unit transmitting a signal other than the initial access signal, a non-initial access transmitting unit, and an initial access signal In contrast, an initial access signal modulation unit that maps a specific hopping pattern on the time axis and a free channel when it is determined that there is a free channel based on terminal free channel information. CW for initial access that turns on / off the transmission output of the high-frequency carrier signal in the guard band when the transmission output of the high-frequency carrier signal is turned on / off according to a specific hopping pattern A transmission unit, and an intermittent transmission control unit that continuously controls the initial access CW transmission unit after power-up to perform intermittent transmission, and the ground station reception unit converts the downlink signal into a baseband signal CW receiving unit for initial access, demodulating unit for initial access for demodulating initial access signal from baseband signal, intermittent signal Doppler shift for estimating Doppler shift amount of uplink from baseband signal and sending Doppler shift correction amount information to terminal transmitting unit A correction unit and a non-initial access receiver that receives and demodulates signals other than the initial access signal, and transmits to the ground station The terrestrial station vacant channel information extracting unit for extracting the uplink terrestrial station vacant channel information from the downlink signal from the satellite, and the extracted uplink terrestrial station vacant channel information on the high frequency carrier wave The carrier signal output from the terminal transmitter is transmitted after the power is turned on by the intermittent transmission controller, and the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 The CW transmitter for initial access is intermittently controlled by turning on and off based on the Doppler shift correction amount information, and the ground station receiver receives the initial access signal subjected to intermittent transmission control by the CW receiver for initial access, Satellite communication characterized by sending Doppler shift correction amount information estimated from a baseband signal by an intermittent signal Doppler shift correction unit to a terminal transmission unit System.

According to a third aspect of the present invention, in the second aspect of the present invention, the terminal receiver further includes a GPS receiver that extracts position information, and the terminal transmitter further includes the position information and the satellite. A satellite communication system comprising: a Doppler correction unit that estimates a Doppler shift amount from the position information of the signal and extracts a Doppler correction amount; and a terminal transmission unit transmits an initial access signal by adding the Doppler correction amount to a transmission frequency. .

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a block diagram showing a satellite communication system according to Embodiment 1 of the present invention. In FIG. 1, 1 is a satellite that relays an uplink signal, 2 is a ground station receiver that receives a downlink signal from satellite 1, 3 is a CW receiver for initial access of the ground station receiver 2, and 4 is a ground station. The demodulator for initial access of the receiver 2, 5 is a receiver for non-initial access of the ground station receiver 2, 6 is a terminal transmitter for transmitting an uplink signal, and 7 is a CW transmitter for initial access of the terminal transmitter 6. , 8 are initial access signal modulators of the terminal transmitter 6, and 9 is a non-initial access transmitter of the terminal transmitter 6.

  The operation of the satellite communication system configured as described above will be described with reference to FIG. FIG. 2 is a frequency allocation diagram showing the frequency allocation of the initial access signal in the first embodiment. In each figure showing the satellite communication system according to each embodiment, only one terminal is shown, but this is represented by a single terminal, and actually the terminal is composed of a plurality of terminals. is there.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, the initial access signal modulator 8 specifies only the initial access signal on the time axis. In response to this hopping pattern, the initial access CW transmitter 7 transmits a high-frequency carrier signal in the guard band S2 in the system band S1 as shown in FIG. Turn on and off.

  In the ground station receiver 2, an initial access signal prepared separately from the non-initial access receiver 5 that receives signals other than the initial access signal is received from the terminal transmitter 6 that has arrived via the satellite 1. The CW receiving unit 3 receives the signal, converts it to a baseband signal, and the baseband signal is demodulated by the initial access demodulating unit 4.

  As described above, according to the present embodiment, the terminal transmission signal transmitted with the uplink initial access signal is a carrier wave (CW, Carrier Wave) signal, and the sensitivity is increased by that amount. As well as improving accuracy, it does not interfere with the lines in other links and does not hinder system capacity improvement.

(Embodiment 2)
FIG. 3 is a block diagram showing a satellite communication system according to Embodiment 2 of the present invention. In FIG. 3, satellite 1, ground station receiver 2, initial access CW receiver 3, initial access demodulator 4, non-initial access receiver 5, terminal transmitter 6, initial access CW transmitter 7, initial Since the access signal modulating unit 8 and the non-initial access transmitting unit 9 are the same as those in FIG. 10 is a ground station transmitter, 11 is a transmitter, 12 is an empty channel information extractor, 13 is a terminal receiver, 14 is an empty channel information extractor, and 15 is a receiver.

  The operation of the satellite communication system configured as described above will be described with reference to FIG. FIG. 4 is a frequency allocation diagram showing the frequency allocation of the initial access signal in the second embodiment.

  First, in the ground station transmission unit 10, the vacant channel information (empty channel information) is extracted from the signal from the satellite 1 by the vacant channel information extraction unit 12, and the extracted vacant channel information is transmitted to the satellite 1 by the transmitter 11. To the terminal receiving unit 13.

  In the terminal receiving unit 13, the receiver 15 receives a signal with available channel information, and the available channel information extracting unit 14 extracts available channel information from the received signal.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, in the initial access signal modulator 8, only the initial access signal on the time axis is transmitted. A specific hopping pattern is mapped, and in response to the hopping pattern, the initial access CW transmission unit 7 uses a high-frequency carrier signal in an empty channel as shown in FIG. 4 when there is an empty channel based on the empty channel information. Turns on or off the transmission output. If there is no empty channel based on the empty channel information, the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 as shown in FIG. 2 is turned on / off.

  In the ground station receiving unit 2, the initial access CW reception prepared separately from the non-initial access receiving unit 5 that receives the initial access signal from the terminal that has arrived via the satellite 1 and receives a signal other than the initial access signal. The signal is received by the unit 3, converted into a baseband signal, and the baseband signal is demodulated by the demodulator 4 for initial access.

  As described above, according to the present embodiment, the terminal transmission signal transmitted by transmitting the uplink initial access signal is a carrier wave signal, and the sensitivity is increased correspondingly, and the demodulation accuracy in the ground station receiving unit 2 is improved. In addition, the initial access signal before the link of the line is a high-frequency carrier signal in an empty channel or a high-frequency carrier wave in a guard band according to a hopping pattern indicated by a hopping signal different from a normal modulation signal at the time of linking. Since the signal is transmitted on the signal, it does not interfere with a line in another link and does not interfere with system capacity improvement.

(Embodiment 3)
FIG. 5 is a block diagram showing a satellite communication system according to Embodiment 3 of the present invention. In FIG. 5, the satellite 1, the ground station receiver 2, the initial access demodulator 4, the non-initial access receiver 5, the terminal transmitter 6, the initial access signal modulator 8, and the non-initial access transmitter 9 are shown in FIG. Therefore, the same reference numerals are given and description thereof is omitted. Reference numeral 16 denotes an initial access CW transmitter, and reference numeral 17 denotes an initial access CW receiver.

  The operation of the satellite communication system configured as described above will be described with reference to FIG. FIG. 6 is a frequency allocation diagram showing the frequency allocation of the initial access signal in the third embodiment.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, the initial access signal modulator 8 specifies only the initial access signal on the time axis. In accordance with the hopping pattern, the initial access CW transmitter 16 turns on and off the transmission output of the high-frequency carrier signal on the boundary between the channel frequencies as shown in FIG.

  In the ground station receiving unit 2, the initial access CW reception prepared separately from the non-initial access receiving unit 5 that receives the initial access signal from the terminal that has arrived via the satellite 1 and receives a signal other than the initial access signal. The signal is received by the unit 17 and converted into a baseband signal, and the baseband signal is demodulated by the initial access demodulating unit 4.

  As described above, according to the present embodiment, the terminal transmission signal that transmits the uplink initial access signal is a carrier wave signal, and the sensitivity is increased correspondingly, and the demodulation accuracy at the ground station is improved. In addition, the initial access signal before the line is linked is placed on a high-frequency carrier signal on the boundary of each channel frequency according to the hopping pattern indicated by the hopping signal different from the normal modulation signal at the time of linking. Since it is transmitted, it does not interfere with the lines in other links and does not hinder system capacity improvement.

(Embodiment 4)
FIG. 7 is a block diagram showing a satellite communication system according to Embodiment 4 of the present invention. In FIG. 7, a satellite 1, a ground station receiver 2, an initial access CW receiver 3, an initial access demodulator 4, a non-initial access receiver 5, a terminal transmitter 6, an initial access CW transmitter 7, an initial Since the access signal modulating unit 8 and the non-initial access transmitting unit 9 are the same as those in FIG. Reference numeral 18 denotes an intermittent signal Doppler shift correction unit, and 19 denotes an intermittent transmission control unit.

  The operation of the satellite communication system of the present invention configured as described above will be described with reference to FIG.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, the initial access signal modulator 8 specifies only the initial access signal on the time axis. 2 is mapped, and the CW transmitter 7 for initial access uses the system bandwidth S1 as shown in FIG. 2 based on the uplink Doppler correction amount information sent from the ground station according to the hopping pattern. The transmission output of the high-frequency carrier signal in the guard band S2 is turned on and off. In this case, the carrier signal transmission output is controlled by the intermittent transmission control unit 19 so that it is intermittently transmitted after the power is turned on.

  The ground station receiver 2 prepares intermittent transmission of the initial access signal from the terminal transmitter 6 arriving via the satellite 1 separately from the non-initial access receiver 5 that receives signals other than the initial access signal. Received by the initial access CW receiver 3, converted into a baseband signal, demodulated by the initial access demodulator 4, and intermittent signal Doppler shift corrector from the converted output signal (baseband signal) 18, the Doppler shift amount of the uplink is estimated, and the estimated Doppler shift correction amount information is sent to the terminal transmission unit 6.

  As described above, according to the present embodiment, the terminal transmission signal that transmits the uplink initial access signal is a carrier wave signal, and the sensitivity is increased correspondingly, and the demodulation accuracy at the ground station is improved. Further, since the Doppler shift amount can be grasped by monitoring the intermittent signal transmitted from the terminal transmitting unit in the ground station receiving unit 2, the Doppler shift amount can be sent to the terminal, so that it can be transmitted to other links in the link. It will not interfere with the system and will not hinder system capacity improvement.

(Embodiment 5)
FIG. 8 is a block diagram showing a satellite communication system according to Embodiment 5 of the present invention. In FIG. 8, a satellite 1, a ground station receiver 2, an initial access CW receiver 3, an initial access demodulator 4, a non-initial access receiver 5, a terminal transmitter 6, an initial access CW transmitter 7, an initial The access signal modulator 8, non-initial access transmitter 9, ground station transmitter, transmitter 11, vacant channel information extractor 12, terminal receiver 13, vacant channel information extractor 14, and receiver 15 are the same as in FIG. Therefore, the same reference numerals are given and the description is omitted. Reference numeral 20 denotes a pattern length control unit.

  The operation of the satellite communication system configured as described above will be described with reference to FIGS.

  First, in the ground station transmitting unit 10, the vacant channel information (empty channel information) is extracted from the signal from the satellite 1 by the vacant channel information extracting unit 12, and the vacant channel information is extracted by the transmitter 11 via the satellite 1. Transmit to the terminal receiver 13.

  In the terminal receiving unit 13, the receiver 15 receives the signal with the empty channel information, and the empty channel information extracting unit 14 extracts the empty channel information from the received signal.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, in the initial access signal modulator 8, only the initial access signal on the time axis is transmitted. A specific hopping pattern is mapped, and in response to this hopping pattern, the initial access CW transmitter 7 based on the vacant channel information, if there is a vacant channel, a high-frequency carrier wave in the vacant channel as shown in FIG. Turns signal transmission output on and off. Further, based on the vacant channel information, when there is no vacant channel, the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 as shown in FIG.

  In this case, the pattern length of the hopping pattern is adaptively changed in the pattern length control unit 20 according to the traffic situation. When the traffic is small, the pattern length is shortened to shorten the line connection time. When the traffic is large, the pattern length is lengthened to increase the interference resistance.

  In the ground station receiving unit 2, the initial access CW reception prepared separately from the non-initial access receiving unit 5 that receives the initial access signal from the terminal that has arrived via the satellite 1 and receives a signal other than the initial access signal. The signal is received by the unit 3, converted into a baseband signal, and the baseband signal is demodulated by the demodulator 4 for initial access.

  As described above, according to the present embodiment, the terminal transmission signal that transmits the uplink initial access signal is a carrier wave signal, and the sensitivity is increased correspondingly, and the demodulation accuracy at the ground station is improved. Also, the initial access signal before the line is linked is placed on a high-frequency carrier signal in an empty channel or a high-frequency carrier signal in a guard band according to the hopping pattern length controlled according to the amount of uplink traffic. Therefore, there is no interference with other links in the link, and there is no hindrance to system capacity improvement. Interference ability can be acquired.

(Embodiment 6)
FIG. 9 is a block diagram showing a satellite communication system according to Embodiment 6 of the present invention. In FIG. 9, a satellite 1, a ground station receiver 2, an initial access CW receiver 3, an initial access demodulator 4, a non-initial access receiver 5, a terminal transmitter 6, an initial access CW transmitter 7, an initial Since the access signal modulating unit 8 and the non-initial access transmitting unit 9 are the same as those in FIG. Reference numeral 21 denotes a frequency control unit.

  The operation of the satellite communication system configured as described above will be described with reference to FIG.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, the initial access signal modulator 8 specifies only the initial access signal on the time axis. The initial access CW transmitter 7 turns on / off the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 as shown in FIG. 2 according to the hopping pattern. . In this case, the transmission frequency is scanned by the frequency control unit 21.

  In the ground station receiving unit 2, the initial access CW reception prepared separately from the non-initial access receiving unit 5 that receives the initial access signal from the terminal that has arrived via the satellite 1 and receives a signal other than the initial access signal. The signal is received by the unit 3, converted into a baseband signal, and the baseband signal is demodulated by the demodulation unit for initial access 4.

  As described above, according to the present embodiment, the terminal transmission signal that transmits the uplink initial access signal is a carrier wave signal, and the sensitivity is increased correspondingly, and the demodulation accuracy in ground station receiving unit 2 is improved. In addition, since the transmission is performed in the guard band S2, the terminal transmission frequency is scanned without causing interference to other channels. Therefore, the ground station receiver 2 does not need to scan, and the apparatus of the ground station receiver 2 The scale can be simplified as much. And the system capacity will be improved accordingly.

(Embodiment 7)
FIG. 10 is a block diagram showing a satellite communication system according to Embodiment 7 of the present invention. In FIG. 10, the satellite 1, the ground station receiver 2, the non-initial access receiver 5, the terminal transmitter 6, and the non-initial access transmitter 9 are the same as those in FIG. Omitted. Reference numeral 21 denotes a frequency control unit, 22 denotes an initial access transmission unit, 23 denotes an initial access reception unit, 24 denotes a modulation unit, and 25 denotes a demodulation unit.

  The operation of the satellite communication system configured as described above will be described with reference to FIG.

  In the terminal transmitter 6, apart from the non-initial access transmitter 9 for transmitting signals other than the uplink initial access signal, the modulator 24 performs modulation similar to the non-initial access on the initial access signal, The initial access transmission unit 22 carries the high-frequency carrier signal and transmits it in the guard band S2 (FIG. 2). In this case, the transmission frequency is scanned by the frequency control unit 21.

  In the ground station receiving unit 2, an initial access receiving unit prepared separately from the non-initial access receiving unit 5 that receives an initial access signal from a terminal that has arrived via the satellite 1 and receives a signal other than the initial access signal. 23 is received and converted into a baseband signal, and the demodulator 25 demodulates the baseband signal.

  As described above, according to the present embodiment, since the uplink initial access signal is transmitted in the guard band S2, the demodulation accuracy in the ground station receiving unit 2 is improved and interference is also given to other channels. Absent. Further, since the terminal transmission frequency is scanned, the ground station receiver 2 does not need to scan, and the apparatus scale of the ground station receiver 2 can be simplified as much. And the system capacity will be improved accordingly.

(Embodiment 8)
FIG. 11 is a block diagram showing a satellite communication system according to Embodiment 8 of the present invention. In FIG. 11, the satellite 1, the ground station receiver 2, the terminal transmitter 6, the ground station transmitter 10, the transmitter 11, the terminal receiver 13, and the receiver 15 are the same as those in FIG. The description is omitted. Reference numeral 26 denotes a beam information generation unit, 27 denotes a beam information extraction unit, 28 denotes a Doppler correction unit, 29 denotes a reception unit, and 30 denotes a transmission unit.

  The operation of the satellite communication system configured as described above will be described.

  First, the satellite 1 employs a multi-beam method, and the beam irradiation area is set to be small so that the Doppler change amount can be almost ignored in the area.

  In the ground station transmitting unit 10, position information to which each beam of the satellite 1 is irradiated is added to the transmission signal in each beam by the beam information generating unit 26, and this is transmitted to the terminal receiving unit 13 by the transmitter 11. Send.

  In the terminal receiving unit 13, the signal is received by the receiver 15, and the beam irradiation position, that is, the position information of the terminals 6 and 13 is extracted from the received signal by the beam information extracting unit 27. Then, in the terminal transmitter 6, the Doppler correction unit 28 estimates the Doppler shift amount of the uplink from the position information of the terminals 6 and 13 and the position information of the satellite 1, and extracts the Doppler correction amount. Then, the transmitter 30 transmits the initial access signal by adding the Doppler correction amount to the transmission frequency, and the receiver 29 of the ground station receiver 2 receives the initial access signal from the terminal arriving via the satellite 1. .

  As described above, according to the present embodiment, since extremely accurate Doppler compensation that does not include a satellite oscillator error is performed, demodulation accuracy in the ground station receiver 2 is improved, and lines in other links are also provided. It will not interfere with the system and will not hinder system capacity improvement.

(Embodiment 9)
FIG. 12 is a block diagram showing a satellite communication system according to Embodiment 9 of the present invention. In FIG. 12, the satellite 1, the ground station receiving unit 2, the terminal transmitting unit 6, the terminal receiving unit 13, the Doppler correction unit 28, the receiving unit 29, and the transmitting unit 30 are the same as those in FIG. Description is omitted. 31 is a GPS receiver.

  The operation of the satellite communication system configured as described above will be described.

  First, the terminal receiving unit 13 has the GPS receiving unit 31 and extracts the position information of the terminals 6 and 13.

  Then, in the terminal transmitter 6, the Doppler correction unit 28 estimates the Doppler shift amount of the uplink from the position information of the terminals 6 and 13 and the position information of the satellite 1, and extracts the Doppler correction amount. Then, in the transmission unit 30, the initial access signal is transmitted by adding the Doppler correction amount to the transmission frequency, and the initial access signal from the terminal transmission unit 6 arriving through the satellite 1 is received by the reception unit 29 of the ground station reception unit 2. Receive at.

  As described above, according to the present embodiment, since extremely accurate Doppler compensation that does not include a satellite oscillator error is performed, demodulation accuracy in the ground station receiver 2 is improved, and lines in other links are also provided. It will not interfere with the system and will not hinder system capacity improvement.

(Embodiment 10)
FIG. 13 is a block diagram showing a satellite communication system according to Embodiment 10 of the present invention. In FIG. 13, the satellite 1, the ground station receiver 2, the terminal transmitter 6, the terminal receiver 13, the receiver 15, the Doppler correction unit 28, the receiver 29, and the transmitter 30 are the same as those in FIG. The description is omitted.

  The operation of the satellite communication system configured as described above will be described.

  The satellite 1 orbiting the low orbit constantly transmits the position and velocity information of the satellite 1 to the terminal receiving unit 13 as a position velocity signal at a plurality of time points with short intervals.

  In the terminal receiving unit 13, the position velocity signal is received by the receiver 15 and converted into a baseband signal. The terminal position extracting unit 32 obtains the position information of the terminals 6 and 13 from the position and velocity information of the satellite 1. Extract.

  In the terminal transmission unit 6, the Doppler correction unit 28 estimates the uplink Doppler shift amount from the position information of the terminals 6 and 13 and the position information of the satellite 1, and extracts the Doppler correction amount. Then, the transmitter 30 transmits the initial access signal by adding the Doppler correction amount to the transmission frequency, and the receiver 29 of the ground station receiver 2 receives the initial access signal from the terminal arriving via the satellite 1. To do.

  As described above, according to the present embodiment, since extremely accurate Doppler compensation that does not include a satellite oscillator error is performed, demodulation accuracy in the ground station receiver 2 is improved, and lines in other links are also provided. It will not interfere with the system and will not hinder system capacity improvement.

  In the wireless communication device, the wireless communication system, and the wireless communication method of the present invention, the initial access signal in the uplink does not interfere with a line in another link, and does not interfere with system capacity improvement. It can be used as wireless communication.

1 is a block diagram showing a satellite communication system according to Embodiment 1 of the present invention. Frequency allocation diagram showing frequency allocation of initial access signal in embodiment 1 Block diagram showing a satellite communication system according to a second embodiment of the present invention. Frequency allocation diagram showing frequency allocation of initial access signal in embodiment 2 Block diagram showing a satellite communication system according to Embodiment 3 of the present invention. Frequency allocation diagram showing frequency allocation of initial access signal in embodiment 3 Block diagram showing a satellite communication system according to a fourth embodiment of the present invention. Block diagram showing a satellite communication system according to a fifth embodiment of the present invention. Block diagram showing a satellite communication system according to a sixth embodiment of the present invention. Block diagram showing a satellite communication system according to a seventh embodiment of the present invention. Block diagram showing a satellite communication system according to an eighth embodiment of the present invention. Block diagram showing a satellite communication system according to a ninth embodiment of the present invention. Block diagram showing a satellite communication system according to a tenth embodiment of the present invention. Block diagram showing a conventional satellite communication system

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Satellite 2 Ground station receiver 3, 17 Initial access CW receiver 4 Initial access demodulator 5 Non-initial access receiver 6 Terminal transmitter 7, 16 Initial access CW transmitter 8 Initial access signal modulator 9 Non Initial access transmitter 10 Ground station transmitter 11 Transmitter 12 Empty channel information extractor 13 Terminal receiver 14 Empty channel information extractor 15 Receiver 18 Intermittent signal Doppler shift corrector 19 Intermittent transmission controller 20 Pattern length controller 21 Frequency Control unit 22 Initial access transmission unit 23 Initial access reception unit 24 Modulation unit 25 Demodulation unit 26 Beam information generation unit 27 Beam information extraction unit 28, 34 Doppler correction unit 29 Reception unit 30 Transmission unit 31 GPS reception unit 32 Terminal position extraction Part 33 Doppler extraction part

Claims (3)

A satellite communication system having a satellite that relays an uplink signal, a terminal transmitter that transmits the uplink signal, and a ground station receiver that receives a downlink signal from the satellite,
The terminal transmitter is
A non-initial access transmitter for transmitting other signals except the initial access signal;
An initial access signal modulator that maps a specific hopping pattern on the time axis to the initial access signal;
A CW transmission unit for initial access that turns on and off the transmission output of a high-frequency carrier signal on a channel boundary according to the hopping pattern;
An intermittent transmission control unit that continuously controls the initial access CW transmission unit to perform intermittent transmission after power-on,
The ground station receiver is
An initial access CW receiver for converting the downlink signal into a baseband signal;
Extracting the Doppler shift amount of the terminal transmission unit from the timing of the intermittent transmission obtained from the baseband signal, an intermittent signal Doppler shift compensation unit that performs Doppler compensation on the downlink signal by the extracted Doppler shift amount;
An initial access demodulator that demodulates an initial access signal from the output of the initial access CW receiver;
A non-initial access receiver for receiving and demodulating other signals excluding the initial access signal,
The carrier signal output from the terminal transmitter is a power output from the intermittent transmission controller, and the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1 is the CW transmission for initial access. A satellite communication system characterized in that intermittent transmission control is performed by turning on and off the unit. A satellite that relays an uplink signal; a terminal receiver that receives a downlink signal from the satellite; a terminal transmitter that transmits the uplink signal; a ground station receiver that receives the downlink signal; A satellite communication system having a ground station transmitter for transmitting an uplink signal,
The terminal receiver is
A receiver for receiving and demodulating the downlink signal;
A terminal idle channel information extracting unit that extracts uplink terminal idle channel information from the demodulated downlink signal, and
The terminal transmitter is
A non-initial access transmitter for transmitting other signals except the initial access signal;
An initial access signal modulator that maps a specific hopping pattern on the time axis to the initial access signal;
When it is determined that there is an empty channel based on the terminal empty channel information, the transmission output of the high-frequency carrier signal in the empty channel is turned on / off according to the specific hopping pattern, and it is determined that there is no empty channel When the initial access CW transmitter for turning on and off the transmission output of the high-frequency carrier signal in the guard band,
An intermittent transmission control unit that continuously controls the initial access CW transmission unit to perform intermittent transmission after power-on,
The ground station receiver is
An initial access CW receiver for converting the downlink signal into a baseband signal;
An initial access demodulator that demodulates an initial access signal from the baseband signal;
An intermittent signal Doppler shift correction unit that estimates the Doppler shift amount of the uplink from the baseband signal and sends Doppler shift correction amount information to the terminal transmission unit;
A non-initial access receiver for receiving and demodulating other signals excluding the initial access signal,
The ground station transmitter is
A ground station vacant channel information extracting unit that extracts ground channel vacant channel information of the uplink from the downlink signal from the satellite;
A transmitter that places the extracted uplink ground station vacant channel information on a high-frequency carrier wave and transmits it to the satellite; and
The carrier signal output from the terminal transmitter is after the power is turned on by the intermittent transmission controller, and the initial access CW transmitter transmits the transmission output of the high-frequency carrier signal in the guard band S2 of the system band S1. The intermittent transmission is controlled by turning on and off based on the Doppler shift correction amount information,
The ground station receiving unit receives the initial access signal subjected to the intermittent transmission control by the initial access CW receiving unit, and receives the Doppler shift correction amount information estimated from the baseband signal by the intermittent signal Doppler shift correcting unit. A satellite communication system, characterized by being sent to the terminal transmitter. The terminal receiving unit further includes a GPS receiving unit that extracts position information,
The terminal transmission unit further includes a Doppler correction unit that estimates a Doppler shift amount from the position information and the satellite position information and extracts a Doppler correction amount,
The satellite communication system according to claim 2, wherein the terminal transmission unit transmits the initial access signal by adding the Doppler correction amount to a transmission frequency.

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