JP3692728B2 - Satellite communication system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
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.
[0003]
The operation of the satellite communication system configured as described above will be described below.
[0004]
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.
[0005]
In the ground station receiving unit 2, the receiving unit 30 receives an initial access signal in which the uplink Doppler shift amount is corrected, received from the terminal transmitting unit 6 arriving through the satellite 1, and is connected between the ground station and the terminal. Are connected.
[0006]
[Problems to be solved by the invention]
However, in the conventional satellite communication system described above, the initial access signal frequency in the uplink from the satellite received by 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.
[0007]
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.
[0008]
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.
[0009]
[Means for Solving the Problems]
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 includes a non-initial access transmission unit that transmits a signal other than the initial access signal, and an initial mapping that maps a specific hopping pattern on the time axis only to the initial access signal. An access signal modulation unit and an initial access CW transmission unit that turns on and off the transmission output of a high-frequency carrier signal in the guard band according to a hopping pattern, and the ground station reception unit is a downlink signal from a satellite An initial access CW receiver for converting the first access signal into a baseband signal, an initial access demodulator for demodulating the initial access signal from the baseband signal, And a non-initial access receiver for receiving and demodulating signals other than the initial access signal.
[0010]
As a result, a satellite communication system can be obtained in which the initial access signal in the uplink does not interfere with other links in the link and does not interfere with system capacity improvement.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention is a satellite communication 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 is a non-initial access transmission unit that transmits a signal other than the initial access signal, and an initial access signal modulation that maps a specific hopping pattern on the time axis to only the initial access signal And a CW transmitter for initial access that turns on and off the transmission output of a high-frequency carrier signal in the guard band according to the hopping pattern, and the ground station receiver receives the downlink signal from the satellite as the baseband CW receiver for initial access to convert to signal, demodulator for initial access to demodulate initial access signal from baseband signal, and signal other than initial access signal The initial access signal is in the guard band according to the hopping pattern indicated by the hopping signal different from the normal modulation signal at the time of the link. It has the effect of being transmitted on a high frequency carrier signal.
[0012]
The invention according to claim 2 includes 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 from the satellite. A satellite communication system having a ground station receiver for receiving and a ground station transmitter for transmitting an uplink signal, wherein the terminal receiver receives a downlink signal from the satellite and demodulates the receiver, and a demodulated signal A free channel information extracting unit for extracting uplink free channel information from the terminal, and the terminal transmitting unit transmits a non-initial access transmitting unit for transmitting signals other than the initial access signal and a time for only the initial access signal. It is determined that there is an empty channel based on the empty channel information output from the initial access signal modulator that maps a specific hopping pattern on the axis and the empty channel information extractor. When it does, turn on / off the transmission output of the high-frequency carrier signal in the vacant channel according to the hopping pattern, and turn on / off the transmission output of the high-frequency carrier signal in the guard band when it is determined that there is no vacant channel CW transmitter for initial access and ground station receiver, CW receiver for initial access for converting downlink signal from satellite to baseband signal, and demodulator for initial access for demodulating initial access signal from baseband signal And a non-initial access receiving unit that receives and demodulates signals other than the initial access signal, and the ground station transmission unit includes an empty channel information extracting unit that extracts empty information of the uplink channel from the signal from the satellite, and extraction The uplink channel vacancy information is placed on a high-frequency carrier wave and transmitted to the satellite. The initial access signal before being carried is placed on a high-frequency carrier signal in an empty channel or a high-frequency carrier signal 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. It has the effect of being transmitted.
[0013]
The invention according to claim 3 is 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 that transmits a signal other than the initial access signal, an initial access signal modulator that maps a specific hopping pattern on the time axis only to the initial access signal, The CW transmitter for initial access that turns on and off the transmission output of the high-frequency carrier signal on the channel boundary according to the hopping pattern, and the ground station receiver are the initial ones that convert the downlink signal from the satellite into a baseband signal Access CW receiver, demodulator for initial access demodulating initial access signal from baseband signal, and receiving and demodulating signals other than initial access signal The initial access signal before the line is linked, according to the hopping pattern indicated by the hopping signal different from the normal modulation signal at the time of linking, It has the effect of being transmitted on a high frequency carrier signal on the boundary of the channel frequency.
[0014]
The invention according to claim 4 is 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 that transmits a signal other than the initial access signal, an initial access signal modulator that maps a specific hopping pattern on the time axis only to the initial access signal, Control the initial access CW transmitter that turns on and off the transmission output of the high-frequency carrier signal on the channel boundary according to the hopping pattern and the initial access CW transmitter after the power is turned on to perform intermittent transmission. An intermittent transmission control unit, and the ground station reception unit includes an initial access CW reception unit that converts a downlink signal from a satellite into a baseband signal, and a baseband The intermittent signal Doppler shift compensation unit that extracts the Doppler shift amount of the terminal transmission unit from the timing of the intermittent signal obtained from the signal and performs Doppler compensation on the downlink signal from the satellite based on the extracted Doppler shift amount, and CW reception for initial access The initial access demodulating unit for demodulating the initial access signal from the output of the unit and the non-initial access receiving unit for receiving and demodulating signals other than the initial access signal It has an effect of grasping the Doppler shift amount by monitoring the intermittent signal transmitted from the unit.
[0015]
According to a fifth aspect of the present invention, there is provided 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 from the satellite. A satellite communication system having a ground station receiver for receiving and a ground station transmitter for transmitting an uplink signal, wherein the terminal receiver receives a downlink signal from the satellite and demodulates the receiver, and a demodulated signal A free channel information extracting unit for extracting uplink free channel information from the terminal, and the terminal transmitting unit transmits a non-initial access transmitting unit for transmitting signals other than the initial access signal and a time for only the initial access signal. It is determined that there is an empty channel based on the empty channel information output from the initial access signal modulator that maps a specific hopping pattern on the axis and the empty channel information extractor. When it does, turn on / off the transmission output of the high-frequency carrier signal in the vacant channel according to the hopping pattern, and turn on / off the transmission output of the high-frequency carrier signal in the guard band when it is determined that there is no vacant channel It has a CW transmitter for initial access and a pattern length controller that controls the hopping pattern length according to the amount of traffic on the uplink, and the ground station receiver converts the downlink signal from the satellite into a baseband signal A ground station transmitter having an initial access CW receiver, an initial access demodulator for demodulating an initial access signal from a baseband signal, and a non-initial access receiver for receiving and demodulating a signal other than the initial access signal The free channel information extraction unit extracts the free information of the uplink channel from the signal from the satellite, and the extracted free information of the uplink channel is increased. A transmitter that transmits the signal to a satellite and transmits it to the satellite. The initial access signal before the link of the line has a hopping pattern length controlled according to the traffic volume of the uplink. Accordingly, there is an effect that a high frequency carrier signal in an empty channel or a high frequency carrier signal in a guard band is transmitted and transmitted.
[0016]
The invention according to claim 6 is 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 that transmits a signal other than the initial access signal, an initial access signal modulator that maps a specific hopping pattern on the time axis only to the initial access signal, A ground station has a CW transmitter for initial access that turns on and off the transmission output of a high-frequency carrier signal in the guard band according to a hopping pattern, and a frequency controller that scans and controls the transmission frequency on which the initial access signal is placed. The receiving unit includes an initial access CW receiving unit that converts a downlink signal from a satellite into a baseband signal, and an initial access signal from the baseband signal. The initial access demodulator and the non-initial access receiver for receiving and demodulating signals other than the initial access signal. In accordance with a hopping pattern indicated by a hopping signal different from that of a normal modulation signal, there is an effect that the signal is transmitted on a high frequency carrier signal whose frequency is scan-controlled.
[0017]
The invention according to claim 7 is 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 transmission unit includes a non-initial access transmission unit that transmits a signal other than the initial access signal, a modulation unit that performs the same modulation processing on the initial access signal as a signal other than the initial access signal, and a modulation unit. The initial access transmitter for transmitting the modulated signal on a high-frequency carrier wave in the guard band, the frequency controller for performing scan control of the transmission frequency for mounting the initial access signal, and the ground station receiver Receiver for initial access for converting downlink signal to baseband signal, demodulator for demodulating initial access signal from baseband signal, and other than initial access signal A non-initial access receiver for receiving and demodulating the signal, and the initial access signal before the line is linked is a high frequency whose frequency is scan-controlled according to a normal modulation signal at the time of link It has the effect | action that it carries on a carrier wave signal and is transmitted.
[0018]
According to an eighth aspect of the present invention, there is provided 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, and a downlink signal from the satellite. A satellite communication system having a ground station receiver for receiving and a ground station transmitter for transmitting an uplink signal, the ground station receiver having a receiver for receiving and demodulating a downlink signal from a satellite The ground station transmission unit includes a beam information generation unit that generates position information for irradiating a beam together with a current position of the satellite and a transmission time, and a transmitter that transmits the position information. The beam irradiation area is sufficiently small so that the amount of change in the Doppler shift amount within the area is almost negligible, and the terminal receiving unit receives a downlink signal from the satellite and a beam from the received downlink signal. Affection The terminal transmission unit transmits an initial access signal based on the correction in the Doppler correction unit and the Doppler correction unit that estimates and corrects the uplink Doppler shift amount from the extracted beam information. The terminal receiving unit estimates the Doppler shift amount from the extracted beam information, and the terminal transmitting unit has a function of performing Doppler correction based on the estimated Doppler shift amount.
[0019]
The invention according to claim 9 includes 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 from the satellite. A satellite communication system having a ground station receiving unit for receiving, wherein the terminal receiving unit has a GPS receiving unit that receives a signal from a GPS satellite and extracts self-position information, and the terminal transmitting unit is from the satellite A Doppler correction unit that extracts position information and time information of the satellite at the time of initial access signal transmission from the initial access signal, estimates an upstream Doppler shift amount from the position information and time information, and self-position information, and corrects the Doppler correction A transmission unit that transmits an initial access signal based on correction in the unit, and the ground station reception unit includes a reception unit that receives and demodulates a downlink signal from a satellite. Sending Parts are position information of satellites to estimate correct uplink Doppler shift amount from the time information and self-location information has the effect of transmitting the initial access signal based on the correction.
[0020]
The invention according to claim 10 is a method of transmitting information on its own position and speed continuously at a plurality of short time points and relaying an uplink signal while orbiting a low orbit, and information on its own position and speed. A satellite communication system having a terminal receiver for receiving a downlink signal from a satellite including a terminal transmitter for transmitting an uplink signal and a ground station receiver for receiving a downlink signal from the satellite, The receiving unit includes a receiver that receives a downlink signal from a satellite, and a terminal position extracting unit that extracts its own position information based on satellite position and velocity information, and the terminal transmitting unit includes a terminal position extracting unit. A Doppler correction unit that estimates and corrects the uplink Doppler shift amount based on the self-position information extracted by the unit, and a transmission unit that transmits an initial access signal based on the correction in the Doppler correction unit, and a ground station reception unit The terminal transmission unit estimates and corrects the uplink Doppler shift amount based on the self-position information and receives the initial access signal based on the correction. Has the action of transmitting.
[0021]
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 the 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 uplink signals, 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.
[0022]
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.
[0023]
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.
[0024]
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 into a baseband signal, and the baseband signal is demodulated by the initial access demodulating unit 4.
[0025]
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.
[0026]
(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.
[0027]
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.
[0028]
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.
[0029]
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.
[0030]
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 transmission unit 7 has 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.
[0031]
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 signals 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.
[0032]
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.
[0033]
(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.
[0034]
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.
[0035]
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 / off the transmission output of the high-frequency carrier signal on the boundary between the channel frequencies as shown in FIG.
[0036]
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 signals 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.
[0037]
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.
[0038]
(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.
[0039]
The operation of the satellite communication system of the present invention configured as described above will be described with reference to FIG.
[0040]
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 hopping pattern 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.
[0041]
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 estimates the Doppler shift amount of the uplink, and sends the estimated Doppler shift correction amount information to the terminal transmission unit 6.
[0042]
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.
[0043]
(Embodiment 5)
FIG. 8 is a block diagram showing a satellite communication system according to Embodiment 5 of the present invention. 8, 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 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.
[0044]
The operation of the satellite communication system configured as described above will be described with reference to FIGS.
[0045]
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.
[0046]
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.
[0047]
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 an 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.
[0048]
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.
[0049]
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 signals 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.
[0050]
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.
[0051]
(Embodiment 6)
FIG. 9 is a block diagram showing a satellite communication system according to Embodiment 6 of the present invention. In FIG. 9, 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. Reference numeral 21 denotes a frequency control unit.
[0052]
The operation of the satellite communication system configured as described above will be described with reference to FIG.
[0053]
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.
[0054]
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 signals 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.
[0055]
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.
[0056]
(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.
[0057]
The operation of the satellite communication system configured as described above will be described with reference to FIG.
[0058]
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.
[0059]
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.
[0060]
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.
[0061]
(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.
[0062]
The operation of the satellite communication system configured as described above will be described.
First, the satellite 1 adopts a multi-beam method, and the beam irradiation area is set to be small enough to almost ignore the Doppler change amount in the area.
[0063]
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.
[0064]
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. .
[0065]
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.
[0066]
(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.
[0067]
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.
[0068]
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.
[0069]
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.
[0070]
(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.
[0071]
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.
[0072]
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.
[0073]
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.
[0074]
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.
[0075]
【The invention's effect】
As described above, according to the satellite communication system of the first aspect of the present invention, the satellite that relays the uplink signal, the terminal transmission unit that transmits the uplink signal, and the ground station reception that receives the downlink signal from the satellite A terminal transmission unit that transmits a signal other than the initial access signal and a specific hopping pattern on the time axis for only the initial access signal. An initial access signal modulation unit for mapping, and a CW transmission unit for initial access that turns on and off a transmission output of a high-frequency carrier signal in a guard band according to a hopping pattern. An initial access CW receiver for converting a downlink signal into a baseband signal, an initial access demodulator for demodulating an initial access signal from the baseband signal, By having a non-initial access receiving unit that receives and demodulates signals other than the initial access signal, the initial access signal is a guard band according to a hopping pattern indicated by a hopping signal different from a normal modulation signal at the time of link. Therefore, the initial access signal in the uplink does not interfere with the link in other links, and does not interfere with system capacity improvement. An advantageous effect is obtained.
[0076]
According to the invention of claim 2, 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 from the satellite A satellite communication system having a ground station receiving unit for receiving signals and a ground station transmitting unit for transmitting uplink signals, wherein the terminal receiving unit receives and demodulates downlink signals from the satellites; A free channel information extracting unit that extracts uplink free channel information from the demodulated signal, and the terminal transmitting unit transmits only signals other than the initial access signal to the non-initial access transmitting unit, and the initial access signal only There is an empty channel based on the initial access signal modulator that maps a specific hopping pattern on the time axis and the empty channel information output from the empty channel information extractor. When it is determined that the transmission output of the high-frequency carrier signal in the empty channel is turned on and off according to the hopping pattern, and when it is determined that there is no empty channel, the transmission output of the high-frequency carrier signal in the guard band is turned on, The CW transmitter for initial access to be turned off and the ground station receiver are for the initial access to convert the downlink signal from the satellite into a baseband signal, and for the initial access to demodulate the initial access signal from the baseband signal A demodulator and a non-initial access receiver that receives and demodulates signals other than the initial access signal, and the ground station transmitter includes an idle channel information extractor that extracts uplink idle information from a signal from a satellite; The link is linked by having a transmitter that places the extracted upstream channel vacancy information on a high-frequency carrier wave and transmits it to the satellite. The previous initial access signal is transmitted on a high-frequency carrier signal in an empty channel or a high-frequency carrier signal in a guard band according to a hopping pattern indicated by a hopping signal different from a normal modulation signal at the time of link. Therefore, an advantageous effect is obtained 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.
[0077]
According to the third aspect of the present invention, 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 a signal other than the initial access signal, and an initial access signal modulation unit that maps a specific hopping pattern on the time axis only to the initial access signal. The CW transmitter for initial access that turns on and off the transmission output of the high-frequency carrier signal on the channel boundary according to the hopping pattern, and the ground station receiver converts the downlink signal from the satellite into a baseband signal Receiving an initial access CW receiver, an initial access demodulator for demodulating an initial access signal from a baseband signal, and signals other than the initial access signal. By having a non-initial access receiver for receiving and demodulating, the initial access signal is a high frequency signal on the boundary of each channel frequency according to a hopping pattern indicated by a hopping signal different from a normal modulation signal at the time of link. Therefore, it is possible to obtain an advantageous effect that there is no interference with the lines in other links or an obstacle to the improvement of the system capacity.
[0078]
According to the invention of claim 4, 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 a signal other than the initial access signal, and an initial access signal modulation unit that maps a specific hopping pattern on the time axis only 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 is constantly controlled after the power is turned on. An intermittent transmission control unit that performs the transmission, and the ground station reception unit includes an initial access CW reception unit that converts a downlink signal from a satellite into a baseband signal, and a base station signal. An intermittent signal Doppler shift compensation unit that extracts the Doppler shift amount of the terminal transmission unit from the timing of the intermittent signal obtained from the band signal and performs Doppler compensation on the downlink signal from the satellite based on the extracted Doppler shift amount, and the initial access CW By having an initial access demodulator that demodulates the initial access signal from the output of the receiver and a non-initial access receiver that receives and demodulates signals other than the initial access signal, the ground station receiver transmits from the terminal transmitter The amount of Doppler shift can be ascertained by monitoring the intermittent signal that is transmitted, so that the amount of Doppler shift can be sent to the terminal, causing interference with other links in the link and inhibiting system capacity improvement. The advantageous effect of not becoming a factor is obtained.
[0079]
According to the invention of claim 5, 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 from the satellite A satellite communication system having a ground station receiving unit for receiving signals and a ground station transmitting unit for transmitting uplink signals, wherein the terminal receiving unit receives and demodulates downlink signals from the satellites; A free channel information extracting unit that extracts uplink free channel information from the demodulated signal, and the terminal transmitting unit transmits only signals other than the initial access signal to the non-initial access transmitting unit, and the initial access signal only There is an empty channel based on the initial access signal modulator that maps a specific hopping pattern on the time axis and the empty channel information output from the empty channel information extractor. When it is determined that the transmission output of the high-frequency carrier signal in the empty channel is turned on and off according to the hopping pattern, and when it is determined that there is no empty channel, the transmission output of the high-frequency carrier signal in the guard band is turned on, The CW transmitter for initial access to be turned off and the pattern length controller for controlling the hopping pattern length according to the amount of traffic on the uplink. The ground station receiver converts the downlink signal from the satellite into a baseband signal. An initial access CW receiver for conversion, an initial access demodulator for demodulating an initial access signal from a baseband signal, and a non-initial access receiver for receiving and demodulating a signal other than the initial access signal; The transmission unit includes an empty channel information extracting unit that extracts uplink channel vacancy information from a signal from the satellite, and an extracted uplink channel vacancy information. Is placed on a high-frequency carrier wave, and has a transmitter that transmits it toward the satellite, so that the initial access signal before the link is linked depends on the hopping pattern length controlled according to the amount of traffic on the uplink, Since it is transmitted on a high-frequency carrier signal in a vacant channel or a high-frequency carrier signal in the guard band, the initial access signal in the uplink interferes with the link in other links, and the system capacity is improved. An advantageous effect that it does not become an obstruction factor is obtained.
[0080]
According to the invention of claim 6, 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 a signal other than the initial access signal, and an initial access signal modulation unit that maps a specific hopping pattern on the time axis only to the initial access signal. And an initial access CW transmitter that turns on and off the transmission output of the high-frequency carrier signal in the guard band according to the hopping pattern, and a frequency controller that scan-controls the transmission frequency on which the initial access signal is placed, The ground station receiver includes an initial access CW receiver that converts a downlink signal from a satellite into a baseband signal, and an initial access from the baseband signal. Since the initial access demodulator for demodulating the network signal and the non-initial access receiver for receiving and demodulating signals other than the initial access signal, the initial access signal before linking the line is According to the hopping pattern indicated by the hopping signal different from the modulation signal, it is transmitted on a high-frequency carrier signal whose frequency is scan-controlled, so there is no need for the ground station receiver to scan, and the ground station receiver Therefore, it is possible to simplify the size of the apparatus, and the system capacity can be improved accordingly.
[0081]
According to the seventh aspect of the present invention, 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 a signal other than the initial access signal, a modulation unit that performs the same modulation processing on the initial access signal as a signal other than the initial access signal, An initial access transmitter for transmitting a modulated signal from a high frequency carrier wave in a guard band, a frequency controller for scan-controlling a transmission frequency for mounting an initial access signal, and the ground station receiver for the satellite An initial access receiver for converting a downlink signal from the baseband signal into a baseband signal, a demodulator for demodulating the initial access signal from the baseband signal, and an initial access signal Non-initial access receiver for receiving and demodulating signals other than the above, the initial access signal before the link of the line is a high-frequency carrier whose frequency is scan-controlled in accordance with a normal modulation signal at the time of linking Since it is transmitted in the signal, the ground station receiver does not need to scan, and the equipment scale of the ground station receiver can be simplified accordingly, and the system capacity is also improved accordingly. Is obtained.
[0082]
According to the eighth 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 from the satellite A satellite communication system having a ground station receiver for receiving a signal and a ground station transmitter for transmitting an uplink signal, wherein the ground station receiver includes a receiver for receiving and demodulating a downlink signal from a satellite. The ground station transmitter has a beam information generator for generating position information for irradiating the beam along with the current position of the satellite and the transmission time, and a transmitter for transmitting the position information. The beam irradiation area is small enough that the beam is applied and the amount of change in the Doppler shift amount in the area is almost negligible. The terminal receiving unit receives the downlink signal from the satellite and the received downlink signal. To bi A beam information extraction unit for extracting the channel information, and the terminal transmission unit estimates the uplink Doppler shift amount from the extracted beam information and corrects the initial access signal based on the correction in the Doppler correction unit. Since the terminal receiver can estimate the Doppler shift amount from the extracted beam information, and the terminal transmitter can perform Doppler correction based on the estimated Doppler shift amount, the terminal receiver can transmit the satellite oscillator error. Can perform highly accurate Doppler compensation not included, improves demodulation accuracy at the ground station receiver, interferes with other links in the link, and hinders system capacity improvement There is an advantageous effect that there is nothing.
[0083]
According to the invention of claim 9, 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 from the satellite A satellite communication system having a ground station receiving unit for receiving a signal, the terminal receiving unit has a GPS receiving unit that receives a signal from a GPS satellite and extracts self-location information, A Doppler correction unit that extracts satellite position information and time information at the time of initial access signal transmission from the initial access signal from the satellite, and estimates and corrects the uplink Doppler shift amount from the self-position information together with the position information and time information; A transmission unit that transmits an initial access signal based on correction in the Doppler correction unit, and the ground station reception unit includes a reception unit that receives and demodulates a downlink signal from a satellite, thereby transmitting a terminal transmission unit Because it is possible to estimate and correct the uplink Doppler shift amount from the satellite position information, time information and self-position information, and to transmit the initial access signal based on the correction, extremely accurate Doppler compensation that does not include satellite oscillator error As a result, the demodulation accuracy at the ground station receiver is improved, and there is an advantageous effect that it does not interfere with a line in another link or become a hindrance to system capacity improvement. can get.
[0084]
According to the tenth aspect of the present invention, a satellite that continuously transmits its own position and speed information at a plurality of short time intervals and relays an uplink signal while orbiting a low orbit, A satellite communication system having a terminal receiver that receives a downlink signal from a satellite including information, a terminal transmitter that transmits an uplink signal, and a ground station receiver that receives a downlink signal from the satellite. The terminal receiving unit has a receiver that receives a downlink signal from a satellite, and a terminal position extracting unit that extracts its own position information based on satellite position and speed information. A Doppler correction unit that estimates and corrects an uplink Doppler shift amount based on the self-position information extracted by the position extraction unit, and a transmission unit that transmits an initial access signal based on the correction in the Doppler correction unit. The receiving unit has a receiving unit that receives and demodulates the downlink signal from the satellite, so that the terminal transmitting unit estimates and corrects the uplink Doppler shift amount based on the self-location information, and transmits the initial access signal based on the correction. Therefore, it is possible to perform highly accurate Doppler compensation that does not include satellite oscillator errors, improve demodulation accuracy at the ground station receiver, and interfere with other links in the link. In addition, there is an advantageous effect that the system capacity is not hindered.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a satellite communication system according to a first embodiment of the present invention.
2 is a frequency allocation diagram showing a frequency allocation of initial access signals in Embodiment 1. FIG.
FIG. 3 is a block diagram showing a satellite communication system according to a second embodiment of the present invention.
4 is a frequency allocation diagram showing the frequency allocation of initial access signals in Embodiment 2. FIG.
FIG. 5 is a block diagram showing a satellite communication system according to a third embodiment of the present invention.
6 is a frequency allocation diagram showing a frequency allocation of initial access signals in Embodiment 3. FIG.
FIG. 7 is a block diagram showing a satellite communication system according to a fourth embodiment of the present invention.
FIG. 8 is a block diagram showing a satellite communication system according to a fifth embodiment of the present invention.
FIG. 9 is a block diagram showing a satellite communication system according to a sixth embodiment of the present invention.
FIG. 10 is a block diagram showing a satellite communication system according to a seventh embodiment of the present invention.
FIG. 11 is a block diagram showing a satellite communication system according to an eighth embodiment of the present invention.
FIG. 12 is a block diagram showing a satellite communication system according to a ninth embodiment of the present invention.
FIG. 13 is a block diagram showing a satellite communication system according to a tenth embodiment of the present invention.
FIG. 14 is a block diagram showing a conventional satellite communication system.
[Explanation of symbols]
1 satellite
2 Ground station receiver
3, 17 CW receiver for initial access
4 Demodulator for initial access
5 Non-initial access receiver
6 Terminal transmitter
7, 16 CW transmitter for initial access
8 Initial access signal modulator
9 Non-initial access transmitter
10 Ground station transmitter
11 Transmitter
12 Free channel information extraction unit
13 Terminal receiver
14 Free channel information extraction unit
15 Receiver
18 Intermittent signal Doppler shift correction unit
19 Intermittent transmission controller
20 Pattern length controller
21 Frequency controller
22 Transmitter for initial access
23 Initial access receiver
24 Modulator
25 Demodulator
26 Beam information generator
27 Beam information extraction unit
28, 34 Doppler correction unit
29 Receiver
30 Transmitter
31 GPS receiver
32 Terminal position extraction unit
33 Doppler extraction unit

Claims (6)

  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, wherein the terminal transmitter A non-initial access transmitter for transmitting signals other than the initial access signal, an initial access signal modulator for mapping a specific hopping pattern on the time axis only to the initial access signal, and a high-frequency carrier wave in the guard band An initial access CW transmission unit that turns on and off a signal transmission output according to the hopping pattern, and the ground station reception unit converts the downlink signal from the satellite into a baseband signal. A CW receiver, an initial access demodulator that demodulates an initial access signal from the baseband signal, and a signal other than the initial access signal. And a non-initial access receiver for adjusting the satellite communication system.   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 ground station receiver that receives a downlink signal from the satellite; A satellite communication system having a ground station transmitter for transmitting an uplink signal, wherein the terminal receiver receives a downlink signal from the satellite and demodulates the receiver, and a free space for the uplink from the demodulated signal. A free channel information extracting unit for extracting channel information, the terminal transmitting unit transmitting a signal other than the initial access signal, a non-initial access transmitting unit, and an initial access signal only on the time axis It is determined that there is an empty channel based on the initial access signal modulation unit for mapping a specific hopping pattern and the empty channel information output from the empty channel information extraction unit. When turned on, the transmission output of the high-frequency carrier signal in the empty channel is turned on and off according to the hopping pattern, and when it is determined that there is no empty channel, the transmission output of the high-frequency carrier signal in the guard band is turned on, The initial access CW transmitter that turns off, and the ground station receiver that demodulates the initial access signal from the baseband signal and the initial access CW receiver that converts the downlink signal from the satellite into a baseband signal An initial access demodulator, and a non-initial access receiver for receiving and demodulating a signal other than the initial access signal, and the ground station transmitter is a free space for extracting uplink channel free information from the signal from the satellite A channel information extraction unit; and a transmitter for transmitting the extracted uplink channel vacancy information on a high-frequency carrier wave and transmitting the information to the satellite. Satellite communication system according to claim Rukoto.   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, wherein the terminal transmitter A non-initial access transmitter for transmitting signals other than the initial access signal, an initial access signal modulator for mapping a specific hopping pattern on the time axis only to the initial access signal, and a high frequency signal on the channel boundary An initial access CW transmitter that turns on / off the transmission output of a carrier wave signal according to the hopping pattern, and the ground station receiver receives an initial access CW that converts a downlink signal from the satellite into a baseband signal. And an initial access demodulator for demodulating an initial access signal from the baseband signal, and receiving and demodulating signals other than the initial access signal And a non-initial access receiver.   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, wherein the terminal transmitter A non-initial access transmitter for transmitting signals other than the initial access signal, an initial access signal modulator for mapping a specific hopping pattern on the time axis only to the initial access signal, and a high frequency signal on the channel boundary An initial access CW transmitter that turns on / off the transmission output of a carrier wave signal according to the hopping pattern, and an intermittent transmission controller that controls the initial access CW transmitter continuously after power is turned on to perform intermittent transmission; The ground station receiver includes an initial access CW receiver that converts a downlink signal from the satellite into a baseband signal, and the base An intermittent signal Doppler shift compensation unit that extracts a Doppler shift amount of the terminal transmission unit from a timing of the intermittent signal obtained from a signal, and performs Doppler compensation on a downlink signal from the satellite by the extracted Doppler shift amount; A satellite communication system comprising: an initial access demodulating unit that demodulates an initial access signal from an output of the initial access CW receiving unit; and a non-initial access receiving unit that receives and demodulates a signal other than the initial access signal. .   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 ground station receiver that receives a downlink signal from the satellite; A satellite communication system having a ground station transmitter for transmitting an uplink signal, wherein the terminal receiver receives a downlink signal from the satellite and demodulates the receiver, and a free space for the uplink from the demodulated signal. A free channel information extracting unit for extracting channel information, the terminal transmitting unit transmitting a signal other than the initial access signal, a non-initial access transmitting unit, and an initial access signal only on the time axis It is determined that there is an empty channel based on the initial access signal modulation unit for mapping a specific hopping pattern and the empty channel information output from the empty channel information extraction unit. When turned on, the transmission output of the high-frequency carrier signal in the empty channel is turned on and off according to the hopping pattern, and when it is determined that there is no empty channel, the transmission output of the high-frequency carrier signal in the guard band is turned on, A CW transmitter for initial access to be turned off, and a pattern length controller for controlling the hopping pattern length according to the amount of uplink traffic, and the ground station receiver is based on a downlink signal from the satellite A CW receiver for initial access for converting to a band signal, a demodulator for initial access for demodulating an initial access signal from the baseband signal, and a receiver for non-initial access for receiving and demodulating a signal other than the initial access signal. The ground station transmission unit includes a free channel information extraction unit that extracts free channel information from a signal from the satellite; Place the extracted free information of the uplink channel frequency of a carrier wave, a satellite communication system, comprising a transmitter for transmitting toward the satellite.   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, wherein the terminal transmitter A non-initial access transmitter for transmitting signals other than the initial access signal, an initial access signal modulator for mapping a specific hopping pattern on the time axis only to the initial access signal, and a high-frequency carrier wave in the guard band An initial access CW transmission unit that turns on and off a signal transmission output according to the hopping pattern; and a frequency control unit that scan-controls a transmission frequency on which an initial access signal is placed; CW receiver for initial access for converting a downlink signal from a satellite into a baseband signal, and an initial access signal from the baseband signal And a non-initial access receiver for receiving and demodulating signals other than the initial access signal.

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