JP7062096B2 - Relay device and relay method - Google Patents

Description

The present invention relates to a relay device mounted on a multi-beam relay satellite.

In order to improve the frequency utilization efficiency and increase the communication capacity in satellite communication, a multi-beam relay satellite equipped with a digital channelizer has been proposed (for example, Patent Document 1).
The multi-beam relay satellite is also called HTS (High Throughput Satellite) and relays data from a plurality of uplink beams to a plurality of downlink beams.

A multi-beam relay satellite equipped with a digital channelizer has the following functions. The multi-beam relay satellite divides the input beam into multiple subchannels. Then, the multi-beam relay satellite synthesizes and outputs one or more sub-channels by mapping each sub-channel to each output beam. For example, a multi-beam relay satellite divides a beam from a gateway, which is a feeder link, into a plurality of bands, and transmits each divided beam to an access link.

A satellite communication system in which a multi-beam relay satellite as described above is used is called a multi-beam relay satellite system. In a multi-beam relay satellite system, frequency repetition (eg, 3-frequency repetition) is applied to avoid interference between output beams.

In the multi-beam relay satellite system as described above, since a plurality of beams are allocated so as to cover the service coverage, the utilization rate of the allocated frequency is lowered in the area of the coverage area where the number of users is small.

Japanese Unexamined Patent Publication No. 2018-42187

In the present invention, the uplink signal of the return link from each beam is selected so that the frequency utilization rate does not decrease even if there is a beam with a small number of users, and an arbitrary frequency band of the downlink GW frequency band is used as a plurality of user terminal signals. The purpose is to provide a communication method shared by.

The relay device mounted on the multi-beam relay satellite of the present invention is
A receiver that receives the uplink signal of the return link, which is a signal transmitted by each terminal device existing in the beam.
A selection unit that selects the uplink signal to be transmitted to the ground station device from each of the uplink signals based on the signal power strength of the uplink signal.
A transmission unit that transmits the selected uplink signal to the ground station device via a downlink, and a transmission unit.
To prepare for.

According to the present invention, it is possible to provide a method of sharing an arbitrary frequency band of the downlink GW frequency band with a plurality of user terminal signals.

FIG. 1 is a diagram showing a relay device 20 mounted on the multi-beam relay satellite 10 in the figure of the first embodiment. FIG. 1 is a diagram showing an example in which the selection unit 143, the sub-channel level measurement units 120 to 128, and the multicast unit 720 are realized by the processing circuit 40 in the figure of the first embodiment. FIG. 1 is a diagram showing a comparative example of the relay device 20 in the figure of the first embodiment. The figure explaining the relay device 20 in the figure of Embodiment 1. FIG. FIG. 1 is a diagram showing a specific comparative example of the relay device 20 in the figure of the first embodiment. FIG. 1 is a diagram showing a specific comparative example of the relay device 20 in the figure of the first embodiment. FIG. 1 is a diagram showing a specific configuration of the relay device 20 in the figure of the first embodiment. FIG. 1 is a diagram showing a specific configuration of the relay device 20 in the figure of the first embodiment. FIG. 1 is a diagram showing a configuration of a channelizer 30 having 3 inputs and 1 output provided with a selection unit 143 having a competing subchannel selection function in the figure of the first embodiment. The figure which shows the format of the input signal 130 in the figure of Embodiment 1. FIG. FIG. 1 is a diagram showing an example of a combined wave of a gateway output subchannel in the figure of the first embodiment. The figure which shows the control table 143a in the figure of Embodiment 1. FIG. The figure for demonstrating the control table 143a in the figure of Embodiment 1. FIG. In the figure of the first embodiment, the flowchart which shows the conflict process which the selection part 143 selects a subchannel. FIG. 1 is another flowchart showing a conflict process in which the selection unit 143 selects a subchannel in the figure of the first embodiment. In the figure of the first embodiment, the flowchart which shows the conflict selection timer start processing by a selection part 143. In the figure of the first embodiment, the figure of the configuration which performs the sub-channel level measurement on the output side of the switch part 103. FIG. 1 is a diagram showing a switch configuration of a time division multiplex frame in the figure of the first embodiment. The figure which shows the time division multiplex frame in the figure of Embodiment 1. FIG. FIG. 1 is a diagram showing a system configuration of a communication method in the figure of the first embodiment. FIG. 1 is a diagram showing a communication sequence of the system of FIG. 20. The figure which shows the link layer frame format in the figure of Embodiment 1. FIG. In the figure of Embodiment 1, the figure which shows the system which stores the data of UT in the data server 705. The figure which shows the hardware structure of the data server 705 in the figure of Embodiment 1. FIG. The figure which shows the uplink transmission in the figure of Embodiment 1. FIG. The figure which shows the structure of the channelizer 30 in the figure of Embodiment 1. FIG. In the figure of the first embodiment, a sequence showing collision detection control. In the figure of the first embodiment, a sequence showing collision detection control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same or corresponding parts are designated by the same reference numerals. In the description of the embodiment, the description will be omitted or simplified as appropriate for the same or corresponding parts.
In the description of the first embodiment, it is described as (1) to (5) below.
(1) The digital channelizer 30 is referred to as a channelizer 30.
(2) The competing subchannel selection unit 143 is referred to as a selection unit 143.
(3) The user terminal is indicated as UT.
(4) The gateway is indicated as GW.
(5) The band is indicated as BW.

Embodiment 1.
*** Explanation of configuration ***
The first embodiment will be described with reference to FIGS. 1 to 28. The first embodiment relates to a digital channelizer 30 included in a relay device 20 mounted on a multi-beam relay satellite 10. The feature of the first embodiment is that the channelizer 30 has a selection unit 143.

FIG. 1 shows a relay device 20 mounted on the multi-beam relay satellite 10. The relay device 20 includes a receiving unit 32, a channelizer 30, and a transmitting unit 34.
The channelizer 30 includes a selection unit 143, subchannel level measurement units 120 to 128, and a multicast unit 720.
The selection unit 143 includes a control table 143a and a competition selection timer 143b. In addition to the selection unit 143 and the like, the channelizer 30 has a demultiplexing unit that divides the input band into sub-channels, a demultiplexing unit that combines the sub-channels with the output spectrum, and arbitrary sub-channel information from any input port. A switch unit or the like for switching to the output port is provided, but in FIG. 1, the demultiplexing unit, the wave combine unit, and the switch unit are omitted.
The receiving unit 32 is composed of a plurality of receiving units (# 1 to # 3) 31. The receiving unit 31 has an antenna 33. Each receiving unit 31 inputs the input signals 110 to 112, which will be described later, received from the antenna 33 to the channelizer 30. Each receiver 31 corresponds to a different beam. The receiving unit 32 receives the uplink signal of the return link, which is a signal transmitted by each terminal device existing in the beam. The input signals 110 to 112 are all uplink signals. The selection unit 143 selects the uplink signal to be transmitted to the ground station apparatus from the respective uplink signals based on the signal power strength of each uplink signal. Specifically, the selection unit 143 selects an input signal to be transmitted to the gateway, which is a ground station device, from the input signals 110 to 112 based on the signal power strength of each input signal.
The transmission unit 34 transmits the uplink signal selected by the selection unit 143 from the antenna 35 to the gateware, which is a ground station device, by downlink.

FIG. 2 shows an example in which the selection unit 143, the subchannel level measurement units 120 to 128, and the multicast unit 720 are realized by the processing circuit 40.

FIG. 3 is a comparative example of the relay device 20 of the first embodiment.
FIG. 4 is a diagram illustrating the relay device 20 of the first embodiment.
In FIG. 3 of the comparative example, GW # 1, GW # 2, and GW # 3 are required for the coverage area # 1, the coverage area # 2, and the coverage area # 3, respectively. On the other hand, in FIG. 4,
One GW # 1 can handle the coverage area # 1 corresponding to the entire coverage area # 1, coverage area # 2 and coverage area # 3 in FIG. This is due to the function of the selection unit 143 of the channelizer 30.

5 and 6 are specific comparative examples of the relay device 20. In FIGS. 5 and 6, one figure is divided into two figures by A1-A2 for convenience.
7 and 8 show a specific configuration of the relay device 20. In FIG. 7 and FIG. 8, one figure is divided into two figures by B1-B2 for convenience.

The channelizer 010 of the comparative example has a plurality of demultiplexing units 031 to 039, a switch unit 020, and a plurality of combine parts. The outputs of the demultiplexing units 031 to 039 are input to the combine unit 051 to the combine unit 053. The channelizer 30 of the first embodiment has a selection unit 143.

In the return link communication of FIGS. 5 and 6, the user beam band (021BW) is statically mapped to the user beam band (029BW) from the GW band (061) to the GW band (063). Therefore, regardless of whether or not the user beam band (021BW) to the user beam band (029BW) exists, the GW band (061) to the GW band (063) shown on the right side of the figure are required. Here, the notation of "GW band" indicates a gateway band. Therefore, GW # 1 to GW # 3 are required in FIGS. 5 and 6.
5 and 6 show an example in which UT # 1 (011) to UT # 9 (019) exist from the user beam (001) to the user beam (009).
In the GW # 1 gateway band (081 GW BW) of FIG. 5, the uplink signal from the user beam (001) to the user beam (003) is mapped, and the arbitrary band (061) of the gateway band (081) is UT #. The user beam band (021BW) to the user beam band (023BW), which are uplink signals of 1 (011) to UT # 3 (013), are mapped to the GW band (061).
In the gateway band (082 GW BW) of GW # 2 shown in FIG. 5, the uplink signal from the user beam (004) to the user beam (006) is mapped, and the UT is mapped to the arbitrary band (062) of the gateway (082). The user beam band (024BW) to the user beam band (026BW), which are uplink signals of # 4 (014) to UT # 6 (016), are mapped to the band 062.
In the gateway band (083 GW BW) of GW # 3 shown in FIG. 6, the upling signal of the user beam (007) is mapped to the user beam (009), and the arbitrary band (063) of the gateway (083) is UT. The user band (027BW) to the user band (029BW), which are uplink signals of # 7 (017) to UT # 9 (019), are mapped to the band 063.

In FIGS. 7 and 8, the relay device 20 includes a selection unit 143 having a function of selecting competing subchannels in the output stage of the switch unit 103 of the channelizer 30.
When the channelizer 30 includes the selection unit 143, the selection unit 143 selects a sub-channel of the user beam in the user band (021BW) to the user band (029BW).
By this selection, return link communication sharing the band (061) of the gateway band (081GW BWW) of GW # 1 is realized.

FIG. 9 shows the configuration of a channelizer 30 having 3 inputs (110 to 112) and 1 output (165) including a selection unit 143 having a competing subchannel selection function. The channelizer 30 of the first embodiment includes a demultiplexing unit 100 to 102, a switch unit 103, and a wave combining unit 104. The demultiplexing units 100 to 102 include subchannel dividing units 113 to 115 and subchannel level measuring units 120 to 128. The switch unit 103 includes hybrid units 140 to 142, memories 180 to 191, a selector 144, and a selection unit 143. The combined wave unit 104 includes an order changing unit 163 and a combined wave generation unit 164.

The input signal 110 is divided into sub-channels by the sub-channel dividing unit 113. The sub-channel level measuring units 120 to 122 measure the signal power for each sub-channel, and input the sub-channel measurement result and the sub-channel symbol information to the switch unit 103 as input signals 130 to 132. The input signal 111 and the input signal 112 are also processed in the same manner as the input signal 110.

FIG. 10 shows the format of the input signal 130. The input signal 130 has a frame configuration defined by a time axis 170 and a bit width 171. The input signal 130 is serially transmitted between the demultiplexing unit 100 and the switch unit 103. The frame 172 is composed of a frame flag 174 indicating the beginning of the frame, a sub-channel level measurement result 175, and sub-channel symbol information 176.

In the demultiplexing unit # 1 (100), the input signal 130 is the subchannel 01, and the input signal 131 is the subchannel 02. Although the input signal continuous with the input signal 131 is not shown, if this input signal is the input signal 131a, the input signal 131a is the subchannel 03. The same applies to the demultiplexing unit # 2 (101), where the input signal 133 is the subchannel 01 and the input signal 134 is the subchannel 02. Although the input signal continuous with the input signal 134 is not shown, if this input signal is the input signal 134a, the input signal 134a is the subchannel 03. The same applies to the demultiplexing unit # 3 (102). The description of the demultiplexing unit # 3 (102) will be omitted.

The input signals 130 to 138 input to the switch unit 103 are duplicated by the hybrid units 140 to 142 and transmitted to the memories 180 to 191 installed in each output port. The memories 180 to 191 are connected to the selector 144. Since the hybrid units 140 to 142 in FIG. 9 show an example in which one output port is used, the data path duplicated by the hybrid units 140 to 142 is omitted.

When the input signals 145 to 156 are stored in the memories 180 to 191, the selection unit 143 refers to the frame information for each subchannel through the memory access line 195, and if the output subchannels conflict, the selection unit 143 refers to the subchannel to be output. Select.

FIG. 11 shows an example of a combined wave of the gateway output subchannel. The order changing unit 163 maps the subchannels 201 to 203 and the subchannels 205 to 207 to the band (200 GW BW). The subchannels 201 to 203 are assembled in a continuous band by the combine wave generation unit 164 of the combine wave unit 104 to form the output channel 204. Similarly, the subchannels 205 to 207 are assembled in a continuous band by the function of the combined wave generation unit 164 to form the output channel 208.

FIG. 12 shows a control table 143a used by the selection unit 143 for selection control of competing subchannels. The selection unit 143 manages the control table 143a. The control table 143a is composed of an input signal (subchannel of an arbitrary beam) competing for each subchannel and subchannel information for performing competing selection.

FIG. 13 is a diagram for explaining the control table 143a. FIG. 13 schematically shows a state in which the input signal 110, the input signal 111, and the input signal 112 of FIG. 9 are demultiplexed by the demultiplexing unit 100, the demultiplexing unit 101, and the demultiplexing unit 102. The upper part of FIG. 13 shows a state in which the input signal 110 is demultiplexed by the demultiplexing unit 100. The middle stage shows a state in which the input signal 111 is demultiplexed by the demultiplexing unit 101. The lower row shows a state in which the input signal 112 is demultiplexed by the demultiplexing unit 102. The demultiplexed signal is output from the hybrid units 140, 141, 142. From the top, the hybrid unit 140 outputs the input signal 145 of the subchannel 01, the input signal 146 of the subchannel 02, and the input signal 147 of the subchannel 03. From the top, the hybrid unit 141 outputs the input signal 149 of the subchannel 01, the input signal 150 of the subchannel 02, and the input signal 151 of the subchannel 03. From the top, the hybrid unit 142 outputs the input signal 153 of the subchannel 01, the input signal 154 of the subchannel 02, and the input signal 155 of the subchannel 03. FIG. 13 shows the correspondence with these input signals.

The input signal 145, the input signal 149, and the input signal 153 are described in the subchannel 01 (210) of the control table 143a of FIG. This means that in FIG. 13, the vertically arranged subchannels 01 have the input signal 145, the input signal 149, and the input signal 153 competing with each other. The input signal 146, the input signal 150, and the input signal 154 are described in the subchannel 02 (214) of the control table 143a. This means that in FIG. 13, the vertically arranged subchannels 02 have the input signal 146, the input signal 150, and the input signal 154 competing with each other. The input signal 147, the input signal 151, and the input signal 155 are described in the subchannel 03 (218) of the control table 143a. This means that in FIG. 13, the vertically arranged subchannels 03 have the input signal 147, the input signal 151, and the input signal 155 competing with each other. Further, in the competition selection execution channels 230, 232, and 234 of the control table 143a of FIG. 12, all of them are described as subchannel 02.

Subchannel competition is carried out by the selection unit 143 for the three subchannels 02 surrounded by the dotted squares in FIG. Specifically, the selection unit 143 selects the input signal having the highest signal power strength among the input signal 146, the input signal 150, and the input signal 154, which are the signals of the three subchannels 02. When the input signal of the subchannel 02 is selected, the input signals of the subchannel 01 and the subchannel 03 are selected by the selection unit 143 from the input signals of the subchannel 01 and the subchannel 03 on both sides of the selected input signal. .. For example, when the input signal 146 of the upper subchannel 02 is selected, the input signals 145 and the input signals 147 on both sides of the input signal 146 are selected as the input signals of the subchannel 01 and the subchannel 03.
As described above, the selection unit 143 selects the input signal having the maximum signal power strength among the input signals which are uplink signals.

In FIG. 12, it is as follows.
<1> In the sub-channel 01 (210), the input signal 145 (211), the input signal 149 (212), and the input signal 153 (213) compete with each other.
The sub-channel 01 is set so that the input signal is selected by the selection unit 143 according to the result of the competitive selection of the sub-channel 02 (231).
<2> The sub-channel 02 (214) competes with the input signal 146 (215), the input signal 150 (216), and the input signal 154 (217).
In the sub-channel 02 (214), the sub-channel 02 (233) is set as the competition selection channel.
Therefore, the selection unit 143 acquires the subchannel level measurement result from the frame information of the input signal 146 corresponding to the subchannel 02, the input signal 150 corresponding to the subchannel 02, and the input signal 154 corresponding to the subchannel 02, and controls the competition. To execute.
<3> In the sub-channel 03 (218), the input signal 147 (219), the input signal 151 (220), and the input signal 155 (221) compete with each other.
Subchannel 03 (218) shows that it follows the competing subchannel selection result of subchannel 02 (235).
<4> The sub-channel N (222) uses the input signal M (223) as an input signal, and the competition selection execution channel (237) is not specified.
<5> The sub-channel N + 1 (224) uses the input signal M + 1 (225) as an input signal, and the competition selection execution channel (239) is not specified.
<6> The sub-channel N + 2 (226) uses the input signal M + 2 (226) as an input signal, and the competition selection execution channel (241) is not specified.

The selection unit 143 acquires the subchannel measurement result from each frame of the input signal 146 which is the subchannel 02, the input signal 150 which is the subchannel 02, and the input signal 154 which is the subchannel 02 according to the control table 143a, and the level. Select the highest input frame (input signal) of.
For example, when the subchannel measurement result acquired from the frame of the input signal 150 has the largest value, the selection unit 143 selects the input subchannel of the input signal 150.

*** Explanation of operation ***
Hereinafter, the operation of the selection unit 143 will be described with reference to FIGS. 14 to 16.
14 to 16 are flowcharts illustrating the operation of the selection unit 143.
The operation of the selection unit 143 corresponds to the selection method. Further, the operation of the selection unit 143 corresponds to the processing of the selection program. The selection program is stored in the processing circuit 40, and the processing circuit 40 can realize the selection unit 143 to execute this program.
The operation of the relay device corresponds to the relay method.

FIG. 14 is a flowchart showing a conflict process in which the selection unit 143 selects a subchannel.
The input subchannel follows the algorithm shown in FIG. When the frame head is received (step S301), the selection unit 143 acquires the level measurement result of the competing subchannel (input signal) according to the control table 143a (step S303). Specifically, in FIG. 13, the selection unit 143 acquires the level measurement results of the input signals 146, 150, 154 of the subchannel 02 of the input 110, the input 111, and the input 112 from the memories 181, 185, 189. The selection unit 143 selects the subchannel having the highest measurement level (step S304).

Next, the selection unit 143 determines whether the conflict selection timer for conflict selection is being activated (step S302), and if the conflict selection timer is not activated, activates the conflict selection timer (step S305).
When the conflict selection timer is running, the selection unit 143 continuously selects the currently selected subchannel regardless of the measurement level result (step S306). Next, the selection unit 143 determines whether the subchannel (input signal) having the maximum measurement level is the same as the selected subchannel (input signal) in the competing subchannel (input signal) (step S307). When the subchannel having the maximum measurement level is the same as the subchannel (input signal) being selected, the selection unit 143 restarts the conflict selection timer (step S308). The selection unit 143 does not operate the conflict selection timer when the subchannel having the maximum measurement level is different from the subchannel being selected.

Therefore, the selection unit 143 has a timer that is activated by selecting an input signal that is an uplink signal, and when the timer is activated after the input signal is selected, the input signal is continuously input regardless of the signal power strength. It is selected, it is determined whether the selected input signal and the subsequent input signal are the same, and when the input signals are the same, the timer is restarted.

By adopting such a control algorithm, the selection unit 143 can continuously select the selected subchannel (input signal) for a certain period of time, and can communicate without disturbing the user's transaction in the middle. ..

FIG. 15 is a control algorithm in which step S307 of FIG. 14 is changed to step S310. In the algorithm shown in FIG. 15, if the measurement level of the selected subchannel (input signal) is equal to or higher than the threshold value (step S310) in the determination that the conflict selection timer is running, the selection unit 143 restarts the conflict selection timer ( Step S308).
By determining the threshold value in this way, it is possible to prevent the UT (user terminal) located in the cell edge from being interrupted by the UT located in the cell center during communication.

As described above, the selection unit 143 has a timer that is activated by selecting an input signal that is an uplink signal, and when the timer is activated after the selection of the input signal, the input signal is input regardless of the signal power strength. It is continuously selected, and it is determined whether or not the signal power strength of the continuously selected input signal is equal to or higher than the threshold value. The selection unit 143 restarts the timer when the signal power strength is equal to or higher than the threshold value.

FIG. 16 shows the conflict selection timer activation process by the selection unit 143. At the time of starting the conflict selection timer, the selection unit 143 determines whether the number of restarts of the timer is within the maximum allowable number of restarts (step S312), and if the number of restarts of the timer is within the maximum number of allowable restarts, the conflict selection timer. Is restarted (step S313). The selection unit 143 does not restart the conflict selection timer if the number of restarts of the timer is equal to or greater than the maximum allowable number of restarts. By controlling in this way, it is possible to prevent one UT from occupying the uplink line.

In this way, when the timer is restarted, the selection unit 143 determines whether or not the number of restarts of the timer is within the allowable number of times, and restarts the timer when the number of restarts is within the allowable number of times.

In the channelizer 30 of FIG. 9, the sub-channel level is measured at the demultiplexing section, but it is also possible to measure the sub-channel level at the output side of the switch section 103.
FIG. 17 shows a configuration in which the sub-channel level is measured on the output side of the switch unit 103. In FIG. 17, the sub-channel level measuring unit 900 is connected to the selection unit 143. The selection unit 143 measures the signal power level of the sub-channel from the symbol information of the sub-channel designated as the competing channel by the control table 143a by using the sub-channel level measurement unit 900. The selection unit 143 executes the sub-channel selection by using the measurement result of the sub-channel level measurement unit 900 in the same manner as in FIG.

Although the channelizer 30 shown in FIG. 9 shows the selection control of competing subchannels in a switch configuration in which switching is performed in subchannel units, it is also possible to configure a time division multiplexing frame switch.

FIG. 18 shows a switch configuration of a time division multiplex frame. The demultiplexing units 100 to 102 include time division multiplexing units 400 to 402. The time division multiplexing units 400 to 402 input the multiple frames with the paths 405 to 407 to the switch unit 103. The hybrid units 140 to 142 of the switch unit 103 duplicate and transmit a frame to the selector 144 arranged for each output port. Since FIG. 18 shows an example of one output port, the transmission path by frame duplication is omitted. The frames 410 to 412 transmitted from the hybrid units 140 to 142 are temporarily stored in the memories 420 to 422.

When the frames 410 to 412 are received, the selection unit 143 accesses the memories 420 to 422 via the memory access lines 425 to 427, and acquires the level measurement results of the competing subchannels from the frames 410 to 412. .. The selection unit 143 compares the level measurement results, selects a subchannel using an algorithm similar to the configuration of FIG. 9 (FIGS. 14 to 16), and transmits the subchannel symbol information to the combine unit 104.

FIG. 19 shows a time division multiplexing frame. FIG. 19 shows an example in which the frame N + 1 (451) is continuously transmitted following the frame N (450). In the frame N (450), the subchannel 01 level measurement result (453) and the subchannel 01 symbol information (454) are set following the frame flag (452) indicating the frame head. In the frame N (450), the subchannel 02 level measurement result (455) and the subchannel 02 symbol information (456) of the next subchannel are set following this information.

As shown in FIGS. 18 and 19, even in a time-division multiple frame, sub-channel selection can be performed by accessing the memory at the frame reception timing and acquiring the level measurement result of the competing sub-channel.

Next, the communication method will be described with reference to FIGS. 20 to 22.
FIG. 20 shows the system configuration of the communication method described below. UT # 1 (500) and UT # 2 (501) are located in the beam # 1 (001), and the uplink signal 502 of UT # 1 (500) and the uplink signal (503) of UT # 2 (501) are present. To send. The satellite payload is composed of an antenna 504, a receiving unit 31, a channelizer 30, and a transmitting unit 34. The receiving unit 31 is composed of a filter 505 and an input side amplifier 506, and the transmitting unit 34 is composed of an output side amplifier 507 and a filter 508. The receiving unit 31 may connect a frequency conversion unit to the output side of the amplifier 506. Similarly, the transmission unit 34 may connect a frequency conversion unit to the amplifier 507 input side.

It is assumed that the control table 143a used in the selection unit 143 included in the switch unit 103 of the channelizer-30 is preset before launch or set in orbit by a mission control station (not shown).

UT # 1 (500) and UT # 2 (501) use the same channel 41 on the GW side.

FIG. 21 shows the communication sequence in FIG. UT # 1 (500) continuously transmits the same packet S1 (0) 520 to 526 a predetermined number of times. After continuous transmission, UT # 1 (500) transmits subsequent packets S1 (1) 527, S1 (2) 528, S1 (3) 529, S1 (4) 530, and S1 (5) 531. Here, S1 (0) indicates the 0th frame, similarly, S1 (1) is the 1st frame, S1 (2) is the 2nd frame, S1 (3) is the 3rd frame, and S1 ( 4) indicates the 4th frame, and S1 (5) indicates the 5th frame.

UT # 2 (501) continuously transmits the same packet S2 (0) 540 to 546 a predetermined number of times. UT # 2 (501) transmits the subsequent packets S2 (1) 547, S2 (2) 548, S2 (3) 549, and S2 (4) 550 after continuous transmission. Here, S2 (0) indicates the 0th frame, S2 (1) is the 1st frame, S2 (2) is the 2nd frame, S2 (3) is the 3rd frame, and S2 (4) is the 3rd frame. The fourth frame is shown.

The channelizer 30 performs level measurement for each subchannel, but the channelizer 30 requires an arbitrary level measurement period 511 before detecting the subchannel power. Since the selection unit 143 cannot execute the competing subchannel selection 512 during the arbitrary level measurement period 511, the frame received during the level measurement period 511 is not selected and is discarded. Therefore, UT # 1 (500) and UT # 2 (501) continuously feed the first frame so as to exceed the level measurement period 511.

When the channelizer 30 detects the sub-channel power, the selection unit 143 selects the sub-channel. When the selection unit 143 selects a subchannel, the selected subchannel is combined by the combine wave generation unit 164, and the combined signal is transmitted to the GW 510.

In FIG. 21, UT # 1 (500) is selected, and packet S1 (0) 550 to 553, packet S1 (1) 554, packet S1 (2) 555, packet S1 (3) 556, and packet S1 (4) 557. , Packet S1 (5) 558 is transmitted to GW510. The duplicate packet S1 (0) 551, the packet S1 (0) 552, and the packet S1 (0) 553 received by the GW 510 are determined to be duplicate packets because, for example, the sequence numbers 602 included in the link layer protocol are the same. It is discarded at GW510.
FIG. 22 shows the link layer frame format. The link layer frame format has a link layer header 600, a link ID 601, a sequence number 602, and data 603. The GW 510 can determine packet duplication by the link layer frame format.

The signals 540 to 550 from UT # 2 (501) are discarded by the channelizer 30.

As described above, in the communication methods shown in FIGS. 20 to 22, data can be transmitted to the GW 510 even if the channelizer 30 requires a level measurement period 511 for the signal from the user terminal.

A method of grasping the selection result of the selection unit 143 on the user terminal will be described with reference to FIGS. 23, 24, 25, 26, 27, and 28.

In FIG. 23, the UT # 1 (702) located in the beam # 1 (700) transmits the UT # 1 signal 710 on the uplink 714 of the return link, and the UT # 2 located in the beam # 2 (701). (703) transmits the UT # 2 signal 711 on the uplink 715 of the return link. The multi-beam relay satellite 10 receives the UT # 1 signal 710 from the antenna 707 and the UT # 2 signal 711 from the antenna 708. The selection unit 143 of the relay device 20 mounted on the multi-beam relay satellite 10 selects the UT # 1 signal 710 by the competing subchannel selection of the UT # 1 signal 710 and the UT # 2 signal 711, and passes through the antenna 709. Then, the UT # 1 signal 710 is mapped to the UT band 713 of the GW band 712 and transmitted by the downlink 716.
When the GW # 1 (704) receives the signal to which the UT # 1 signal 710 is mapped on the downlink 716, the GW # 1 (704) stores the signal in the data server 705 which is a storage device.
GW # 1, which is a ground station device, includes a data server 705 that stores an input signal, which is an uplink signal transmitted by a transmission unit 34 via a downlink.

In FIG. 23, the data server 705 is placed on the ground, but it can also be placed inside the multi-beam relay satellite 10. In that case, the data server 705 is deployed on the output side of the channelizer 30 of the multi-beam relay satellite 10, and the relay device 20 includes a data server 705 that stores an input signal that is an uplink signal selected by the selection unit 143. ..

FIG. 24 shows the hardware configuration of the data server 705. The data server 705 is a computer. The data server 705 includes a processor 705a, a main storage device 705c, an auxiliary storage device 705d, an input interface 705e, an output interface 705f, and a communication interface 705g as hardware. The processor 705a realizes the function of the control unit 705b. The program of the control unit 705b is stored in the auxiliary storage device 705d. Further, the auxiliary storage device 705d stores data included in the signal 713 to which the UT # 1 signal 710 is mapped, which is transmitted from the terminal device (UT) existing in the beam.

FIG. 25 shows a communication mode of a forward link that acquires stored data from a data server as a result of being selected by the selection unit 143. When the data server 705 receives the data acquisition request from the user terminal, the data corresponding to the data acquisition request is mapped to the UT band 722 of the GW band 721 by the uplink 725 of the forward link, and the data is mapped to the UT band 722. The UT signal is transmitted to the multi-beam relay satellite 10. The multi-beam relay satellite 10 multicasts the UT signal mapped to the UT band 722 received from the antenna 709 to the beam # 1 (700) and the beam # 2 (701) to be selected for the upling of the return link. The multicast unit 720 of the multi-beam relay satellite 10 maps the UT signal mapped to the UT band 722 to the UT # 1 band (723) and transmits it via the downlink 726 to the beam # 1 (700). The multicast unit 720 maps the UT signal mapped to the UT band 722 to the UT # 2 band 724 and transmits the UT signal to the beam # 2 (701) via the downlink 727.

As described above, the relay device 20 includes a multicast unit 720 that multicasts an input signal, which is an uplink signal stored in the data server, to each beam of different beams.

FIG. 26 shows the configuration of the channelizer 30. Multicast by the multicast unit 720 uses the switch function of the channelizer 30. The multicast unit 720 controls the switch function. The signal for each subchannel from the demultiplexing unit 800 is transmitted by the subchannel 810, the subchannel 811, and the subchannel 812. These signals are duplicated by the hybrid unit 804 and transmitted to the selector 805 and the selector 806 as the sub-channel signal 813, the sub-channel signal 814, and the sub-channel signal 815.

The selector 805 selects a subchannel from the input signal and transmits the subchannel 816, the subchannel 817, and the subchannel 818 to the combiner unit 801.

The selector 806 selects a subchannel from the input signal and transmits it to the combiner unit 802 as a subchannel 819, a subchannel 820, and a subchannel 821.

FIG. 26 shows an example of multicast transmission on path 822. The sub-channel signal 812 is transmitted to the selector 805 and the selector 806 as sub-channel information 815. A signal is transmitted from the selector 805 to the combiner unit 801 as a subchannel information signal 818, and this signal is transmitted from the selector 806 to the combiner unit 802 as subchannel information 821.

27 and 28 show a collision detection control sequence. H, I, J, K in FIG. 27 are connected to H, I, J, K in FIG. 28. UT # 1 (702) and UT # 2 (703) start transaction processing, execute subchannel competition control on the selection unit 143 of the multi-beam relay satellite 10, and then send and save transaction data to the data server 705. , The sequence for detecting the collision in the selection unit 143 by acquiring the stored transaction data from the data server 705 is shown.

The UT # 1 transaction (0) 900 transmitted by the UT # 1 (702) indicates the transaction data at the 0th sequence number. The transaction data at the 0th sequence number is received by the multi-beam relay satellite 10, and the multi-beam relay satellite 10 transmits the transaction data to the data server 705 as UT # 1 transaction (0) 901. The UT # 2 transaction (0) 902 from UT # 2 (703) is discarded 903 by the subchannel competition control of the selection unit 143 of the multi-beam relay satellite 10. At this time, UT # 2 (703) does not know that the transaction is discarded by the subchannel contention control.

Similarly, the UT # 1 transaction (1) 904 from UT # 1 (702) indicates the first data in the sequence number of the transaction. The transaction data having the first sequence number is received by the multi-beam relay satellite 10, and the multi-beam relay satellite 10 transmits the transaction data to the data server 705 as a UT # 1 transaction (1) 905. The UT # 2 transaction (1) 906 from UT # 2 (703) is discarded 907 by the subchannel competition control of the multi-beam relay satellite 10. At this time, UT # 2 (703) does not know that the transaction is discarded by the subchannel contention control.
The discard in the subchannel contention control is continued until the transaction of UT # 1 is completed according to the algorithm shown in FIGS. 14 to 16.

UT # 1 transaction (2) 908 indicates the second data of the sequence number of the transaction.
The transaction data of the second sequence number is relayed by the multi-beam relay satellite 10 and transmitted as UT # 1 transaction (1) 909.
The UT # 2 transaction (2) 911 is discarded 912 by the subchannel competition control of the multi-beam relay satellite 10.

When the UT # 1 (702) transmits all the UT # 1 transaction data, the UT # 1 (702) transmits the UT # 1 data acquisition request 913. The multi-beam relay satellite 10 transmits the UT # 1 data acquisition request 913 to the data server 705 as the UT # 1 data acquisition request 915.

When the UT # 2 (703) transmits all the UT # 2 transaction data, the UT # 2 (703) transmits the UT # 2 data acquisition request 917. The multi-beam relay satellite 10 discards the UT # 2 data acquisition request 917 by the sub-channel competition control of the multi-beam relay satellite 10.
UT # 1 (702) activates the timer when the UT # 1 data acquisition request 913 is transmitted (914).
Similarly, UT # 2 (703) activates the timer when the UT # 2 data acquisition request 917 is transmitted (918).
When the data server 705 receives the UT # 1 data acquisition request 915 from the multi-beam relay satellite 10, it responds to the UT # 1 data acquisition request 915 and responds to the transaction (0) 920 to the UT # 1, the transaction (1) 925 to the UT # 1, and the UT. Transaction (2) 930 to # 1 is transmitted to the multi-beam relay satellite 10. The transaction (0) indicates the data at the 0th sequence number of the transaction, the transaction (1) indicates the data at the sequence number 1 of the transaction, and the transaction (2) indicates the data at the sequence number 2 of the transaction.
Upon receiving the transaction (0) 920 to UT # 1, the multi-beam relay satellite 10 performs multicast 921. The multi-beam relay satellite 10 transmits transaction (0) 922 to UT # 1 to UT # 1 (702) and transaction (0) 923 to UT # 1 to UT # 2 (703). ..
Transaction (0) 923 to UT # 1 for UT # 2 (703) is UT # 2 (703) and is discarded 924 because the destination is different.

Upon receiving the transaction (1) 925 to UT # 1, the multi-beam relay satellite 10 performs multicast 926.
The multi-beam relay satellite 10 transmits the transaction (1) 927 to the UT # 1 to the UT # 1 (702) and the transaction (1) 928 to the UT # 1 to the UT # 2 (703). ..
Transaction (1) 928 to UT # 1 for UT # 2 (703) is UT # 2 (703) and is discarded 929 because the destination is different.

Upon receiving the transaction (2) 930 to UT # 1, the multi-beam relay satellite 10 performs multicast 931.
The multi-beam relay satellite 10 transmits a transaction (2) 932 to UT # 1 to UT # 1 (702) and a transaction (2) 935 to UT # 1 to UT # 2 (703). ..
Transaction (2) 936 to UT # 1 for UT # 2 (703) is UT # 2 (703) and is discarded 936 because the destination is different.
Upon receiving the transaction (2) 932 to UT # 1, which is the last transaction data, UT # 1 (702) assembles the data.
When UT # 1 (702) confirms that the signal is correctly received, it determines that the service is confirmed to be 933, and stops the timer 934.
In UT # 2 (703), since the desired transaction data is not received, the timer times out 937 and detects a delivery failure 938. When UT # 2 (703) detects a delivery failure, it starts retransmitting the transaction.

*** Effect of Embodiment 1 ***
In the first embodiment described above, the channelizer 30 of the relay device 20 includes the selection unit 143. Therefore, in FIG. 3, three GWs are required for three beams, whereas when the relay device 20 is used, a smaller number of GWs, for example, for the three beams in FIG. 3 is required. As shown in FIG. 4, it is possible to handle with one GW.

The relay device 20 includes a receiving unit 32 and a transmitting unit 34, but the receiving unit 32 can be realized by a receiver which is hardware. Further, the transmitter 34 can be realized by a transmitter which is hardware.

10 multi-beam relay satellite, 20 relay device, 32 receiver, 34 transmitter, 143 selector, 143a control table, 143b conflict selection timer, 705 data server, 720 multicast section.

Claims (9)

In the relay device mounted on the multi-beam relay satellite
A receiver that receives the uplink signal of the return link, which is a signal transmitted by each terminal device existing in the beam.
A selection unit that selects the uplink signal to be transmitted to the ground station device from each of the uplink signals based on the signal power strength of the uplink signal.
A transmission unit that transmits the selected uplink signal to the ground station device via a downlink, and a transmission unit.
A relay device equipped with. The selection unit is
The relay device according to claim 1, wherein the uplink signal having the maximum signal power strength is selected from the uplink signals. The selection unit is
If the timer has a timer to be activated in association with the selection of the uplink signal and the timer is activated after the selection of the uplink signal, the uplink signal is continuously selected and selected regardless of the signal power strength. The relay device according to claim 2, wherein it is determined whether or not the uplink signal and the subsequent uplink signal are the same, and when the uplink signals are the same, the timer is restarted. The selection unit is
If the timer has a timer that is activated in association with the selection of the uplink signal and the timer is activated after the selection of the uplink signal, the uplink signal is continuously selected and continued regardless of the signal power strength. The relay device according to claim 2, wherein it is determined whether or not the signal power strength of the uplink signal selected in the above-mentioned is equal to or higher than a threshold value, and the timer is restarted when the signal power strength is equal to or higher than the threshold value. The selection unit is
3. 4. The relay device according to 4. The relay device further
The relay device according to any one of claims 1 to 5, further comprising a storage device for storing the uplink signal selected by the selection unit. The ground station device is
The relay device according to any one of claims 1 to 5, further comprising a storage device for storing the uplink signal transmitted by the transmission unit on the downlink. The relay device further
The relay device according to claim 6 or 7, further comprising a multicast unit that multicasts the uplink signal stored in the storage device to the respective beams of different beams. The receiver receives the return link uplink signal, which is a signal transmitted by each terminal device present in the beam.
The selection unit selects the uplink signal to be transmitted to the ground station device from the respective uplink signals based on the signal power strength of the respective uplink signals.
A relay method in which a transmission unit transmits the selected uplink signal to the ground station device via a downlink.

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