JP2013141061A - Satellite relay device and satellite communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a satellite relay device that is able to improve communication quality with a terminal in a position where beam areas overlap.SOLUTION: A satellite relay device according to the invention comprises: modulation and decoding means (modulation units 207, 208 and decoding units 209, 210) for modulating and decoding some or all of a signal received by a plurality of beams per received signal; a buffer unit 211 for holding a decoded bit sequence and a decoded result per beam; coding units 212, 213 for selecting any two from the held decoded bit sequences and for error-correction coding each of them; an exclusive OR unit 214 for calculating exclusive OR of two bit sequences after they are error-correction coded; a space coding unit 215 for space coding the calculation result of the exclusive OR to generate transmission bit sequences for the plurality of beams; and a modulation unit 216 for generating a modulated signal per beam by modulating the transmission bit sequences.

Description

  The present invention relates to a satellite communication system in which a terrestrial communication terminal communicates via a communication device mounted on a satellite.

  In a conventional satellite communication system, in bidirectional satellite communication, the uplink signals transmitted from two satellite communication terminals are added on the satellite and then transmitted in downlink, and the satellite communication terminal transmits itself from the downlink reception signal. Canceling the signal improves downlink frequency utilization efficiency (for example, Patent Document 1).

JP-A-8-251094

  However, the conventional satellite communication system has a problem that the communication quality of the downlink is deteriorated due to interference between beams in a multi-beam satellite that forms a plurality of beams and repeatedly uses frequencies. Details will be described with reference to FIG.

  FIG. 7 is a diagram illustrating an example of an operation in which two satellite communication terminals (hereinafter referred to as terminals) A and B communicate with a repeater mounted on a satellite. The repeater has two antennas and forms two beam areas. Further, the two beam areas are formed so as to partially overlap each other. In such an environment, consider the case where terminal A is located in a place where beam areas do not overlap and terminal B is located in a place where beam areas overlap as shown in the figure. In this case, the signal transmitted from terminal A is received by the repeater through one antenna, and the signal transmitted from terminal B is received by the repeater through both antennas. Terminal A receives one of the signals transmitted from the two antennas of the repeater, and terminal B receives both of the signals transmitted from the two antennas of the repeater.

  Here, according to the conventional satellite communication system, the repeater mounted on the satellite adds the signals received by the respective antennas, and performs downlink transmission at a common frequency. That is, the downlink signal transmitted from each antenna is exactly the same signal transmitted at the same frequency. In such a case, at a place where the beam areas overlap, a phenomenon called beat interference in which the electric field strength of the signal is lowered occurs due to the phase relationship between the downlink signals arriving from the respective antennas, and the communication quality is lowered.

  The present invention has been made in view of the above, and it is an object of the present invention to obtain a satellite relay device and a satellite communication system capable of improving communication quality with a terminal in a position where beam areas overlap with each other. Objective.

  In order to solve the above-described problems and achieve the object, the present invention provides a relay apparatus mounted on a communication satellite using a plurality of beams, and a part or all of signals received by the plurality of beams. Demodulating and decoding means for demodulating and decoding each received signal, buffer means for temporarily holding a decoded bit sequence and decoding result for each beam output from the demodulating and decoding means, and a plurality of holding means held by the buffer means An encoding unit that selects any two of the decoded bit sequences and performs error correction encoding on each of them, and calculates an exclusive OR of the two bit sequences that have been error-encoded by the encoding unit Exclusive-OR calculation means for performing spatial encoding on the calculation result of the exclusive-OR, and generating transmission bit sequences for a plurality of beams, and the transmission Tsu DOO series modulates, characterized in that it comprises a modulation means for generating a modulation signal for each beam.

  According to the present invention, it is possible to prevent communication quality degradation due to beat interference in an area straddling the boundary of a beam area (an area where beam areas overlap), that is, a plurality of beams from a relay device mounted on a satellite. Thus, it is possible to improve the communication quality in the satellite communication terminal located at a place where the signal can be received.

  In addition, in a satellite communication terminal located at a place where signals from a plurality of antennas can be received, it is possible to improve communication quality by combining the downlink signals from each beam. Furthermore, from the viewpoint of the beam area design of the satellite communication system, it is possible to avoid a decrease in communication quality in the boundary region, so that the design of the beam irradiation pattern is facilitated.

FIG. 1 is a diagram showing a configuration example of a first embodiment of a satellite communication system according to the present invention. FIG. 2 is a configuration diagram illustrating a configuration example of the satellite relay device according to the first embodiment. FIG. 3 is a diagram illustrating a configuration example of the satellite relay apparatus according to the second embodiment. FIG. 4 is a diagram illustrating a configuration example of the satellite relay device according to the third embodiment. FIG. 5 is a diagram illustrating a configuration example of the satellite relay device according to the fourth embodiment. FIG. 6 is a diagram illustrating a configuration example of the satellite relay apparatus according to the fifth embodiment. FIG. 7 is a diagram for explaining the problem.

  Embodiments of a satellite relay device and a satellite communication system according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a satellite communication system according to the present invention. As shown in the figure, the satellite communication system of the present embodiment includes a satellite relay device (hereinafter referred to as a repeater) 101 mounted on the satellite 100 and a satellite communication terminal (hereinafter referred to as a repeater) that communicates via the repeater 101. (Referred to as terminals) 106 and 107.

  The repeater 101 includes a plurality of antennas 102 and 103, and beam areas 104 and 105 are formed. The beam areas 104 and 105 partially overlap each other, and the terminal 107 exists in a region where these two beam areas overlap. The terminal 106 exists in the beam area 104. That is, the downlink signal 112 transmitted from the antenna 102 and the downlink signal 113 transmitted from the antenna 103 reach the terminal 107, and only the downlink signal 112 transmitted from the antenna 102 arrives at the terminal 106. Also, the uplink signal 110 transmitted from the terminal 107 reaches both the antennas 102 and 103, and the uplink signal 108 transmitted from the terminal 106 reaches only the antenna 102.

  FIG. 2 is a configuration diagram illustrating a configuration example of the repeater (satellite repeater) 101 according to the first embodiment. As shown in FIG. 2, repeater 101 of this embodiment includes antennas 102 and 103, diplexers 201 and 202, RF receivers 203 and 204, A / D converter (A / D) 205, and 206, a regeneration relay unit 250, a control unit 260, D / A conversion units (D / A) 217 and 218, and RF transmission units 219 and 220. In addition, the regenerative relay unit 250 includes demodulation units 207 and 208, decoding units 209 and 210, a buffer unit 211, encoding units 212 and 213, an exclusive OR unit (XOR) 214, and a spatial encoding unit. 215 and the modulation part 216 are comprised.

  In the satellite communication system using the repeater 101 according to the present embodiment, the uplink signals of the two terminals can be separated in the repeater 101 by using different frequencies or times. Shall.

  Further, in order to simplify the description, a configuration using only two satellite antennas 102 and 103 is shown, but the present invention can also be applied to a configuration using a larger number of antennas. Furthermore, the present invention can be applied to a configuration having a plurality of regenerative repeaters. FIG. 2 describes the signal flow in bidirectional communication between two terminals in such a configuration.

  FIGS. 1 and 2 show a case where a single beam is deployed from a single antenna, but beam forming (analog or digital) that forms a beam using a plurality of antennas on a satellite. The present invention can also be applied to a system or a hybrid system thereof. In this case, each beam formed by beam forming corresponds to the antenna in FIGS.

  Hereinafter, the operation of the repeater 101 of the present embodiment will be described. As an example, an operation when the positional relationship among the repeater 101, the terminal 106, and the terminal 107 is as shown in FIG. 1 will be described.

  The uplink signal received by the antenna 102 passes through the diplexer 201, is subjected to high-frequency signal processing such as frequency conversion, amplification, and filter in the RF reception unit 203, and then is quantized discrete signal in the A / D conversion unit 205. (Digital signal) and input to the reproduction relay unit 250. Similarly, the upstream signal received by the antenna 103 also passes through the diplexer 202, is subjected to high-frequency signal processing such as frequency conversion, amplification, and filtering by the RF reception unit 204, and then is quantized by the A / D conversion unit 206. Converted into a discrete signal (digital signal) and input to the regeneration relay unit 250. Since the antenna 102 receives uplink signals (uplink signals 108 and 110) transmitted from both the terminal 106 and the terminal 107, the RF reception unit 203 separates them and processes the uplink signal 108 from the terminal 106. Select as target.

  In the regenerative relay unit 250, the demodulation signal 207 performs demodulation processing of the signal transmitted from the terminal 106 using the digital signal input from the A / D conversion unit 205. Similarly, the demodulator 208 also uses the digital information input from the A / D converter 206 to demodulate the signal transmitted from the terminal 107. Thereafter, the decoding unit 209 performs error correction decoding, deinterleaving, etc. on the demodulated output of the demodulating unit 207 and the decoding unit 210 on the demodulated output of the demodulating unit 208, thereby performing information bit sequence, CRC, number of re-encoded errors. Decoding information such as The outputs of the decoding units 209 and 210 are temporarily stored in the buffer unit 211, and some or all of the information is communicated to the control unit 260.

  The buffer unit 211 transmits the decoded information bit sequence to the encoding units 212 and 213 according to the instruction of the control unit 260. The information decoded by the decoding unit 209 is subjected to error correction coding, CRC addition, and the like in the coding unit 212. The information decoded by the decoding unit 210 is subjected to error correction coding, CRC addition, and the like in the coding unit 213. Note that the encoding units 212 and 213 may add decoding information obtained by the decoding units 209 and 210, for example, information such as a CRC result, in accordance with an instruction from the control unit 260.

  Also, the information sent from the buffer unit 211 to the encoding units 212 and 213 may be changed according to information indicating success / failure of decoding, such as CRC results obtained by the decoding units 209 and 210. For example, when the decoding result of the decoding unit 209 is unsuccessful, that is, the CRC is NG, the information sent to the encoding unit 212 may be a certain known pattern instead of the information after error correction decoding. In that case, the error correction encoding operation of the corresponding encoding unit 212 may be stopped, and the known pattern may be used as an alternative to the error correction encoding output. These operations are controlled by the control unit 260.

  The exclusive OR unit 214 calculates the exclusive OR of both of the transmission bit sequences output from the encoding units 212 and 213. Specifically, the bit sequence output from the encoding unit 212 is A = {a1, a2, a3,..., An}, and the bit sequence output from the encoding unit 213 is B = {b1, b2, b3, .., Bn}, the output bit sequence of the exclusive OR part is C = {c1, c2, c3,..., Cn} (where ci is the exclusive OR (XOR) of ai and bi). If the bit sequence lengths of A and B are different, the bit sequence lengths of A to B or both are adjusted so that the sequence lengths of both are the same. As an adjustment method, in addition to expanding the sequence length by copying or adding a part of the original bit sequence or filling it with a known pattern, a part of the original encoded bit sequence is deleted. Although there are various methods such as a method for reducing the sequence length, any method may be used as long as the sequence lengths of A and B can be made the same. Further, the output of the exclusive OR unit 214 may be obtained by adding the decoding information obtained by the decoding units 209 and 210, for example, information such as a CRC result, to the operation result C of the exclusive OR. Information transmitted to the two terminals is shared by these processes.

  Next, spatial encoding section 215 performs spatial encoding on the transmission information sequence output from exclusive OR section 214 to generate data that is the source of transmission signals transmitted from antennas 102 and 103. . Here, the spatial encoding is performed in order to improve the reception quality by transmitting the same information from a plurality of transmission antennas and combining the plurality of transmission signals on the reception side, and is also called transmission diversity. There are many methods for spatial coding, such as STBC (Space Time Block Coding), CDD (Cyclic Delay Diversity), one that changes modulation mapping for each antenna, and one that simply adds different delay times for each antenna. However, any method may be adopted in the repeater and the satellite communication system according to the present embodiment. The spatial encoding unit 215 generates a different bit sequence for each antenna from a single information bit sequence, but the original information source is the same for each antenna.

  Next, modulation section 216 modulates each bit sequence output from spatial encoding section 215 for each antenna, performs digital signal processing such as frequency conversion and filter processing as necessary, and D / A conversion section 217. And 218 input signals. Further, the modulation unit 216 may have a function of generating a radio frame by adding pilot symbols, control information (eg, synchronization preamble) and the like to the original bit sequence. The D / A converters 217 and 218 output an analog signal obtained by D / A converting the input signal. The RF transmitters 219 and 220 perform high-frequency signal processing such as frequency conversion, amplification, and filtering on these analog signals. The outputs of the RF transmitters 219 and 220 are output as downlink signals from the antennas 102 and 103 through the diplexers 201 and 220.

  In the satellite communication system (see FIG. 1) including the repeater 101 that relays the signal by the operation as described above, the downlink signals 112 and 113 transmitted from the antennas 102 and 103 are spatially encoded. Therefore, the terminal 107 existing in the region where the beam areas 104 and 105 overlap each other, even when the downlink signals 112 and 113 are in a phase relationship that weakens at the antenna end, separates the downlink signals 112 and 113 by applying transmission diversity. It is possible to synthesize above. Therefore, it can suppress that communication quality falls by beat interference.

  The terminals 106 and 107 calculate the exclusive OR of the transmission bit sequences transmitted by themselves with respect to the demodulated or decoded bit sequences, thereby receiving the bit sequences transmitted from the other party (receptions transmitted toward themselves). Power bit sequence) is restored.

  As described above, in the satellite communication system according to the present embodiment, the repeater temporarily decodes and re-encodes each uplink signal received from the terminal, and spatially calculates the exclusive OR of each transmission bit sequence obtained as a result. A transmission sequence that is encoded and transmitted from each antenna is generated. Thereby, even when a terminal exists in an area straddling the boundary of the beam area (an area where the beam areas overlap), deterioration of communication quality due to beat interference caused by downlink signals from a plurality of beams can be avoided. Furthermore, communication quality can be improved by combining downlink signals from a plurality of beams. Further, from the viewpoint of the beam area design of the satellite communication system, it is possible to avoid the deterioration of the communication quality in the boundary region, so that an effect that the design of the beam irradiation pattern is facilitated can be obtained.

Embodiment 2. FIG.
FIG. 3 is a diagram illustrating a configuration example of a repeater according to the second embodiment. The repeater 101a shown in FIG. 3 is obtained by adding an adder 211 and a phase / amplitude adjuster 222 to the repeater 101 (see FIG. 2) of the first embodiment. The adder 221 adds the output signal from the phase / amplitude adjuster 222 to the output signal from the RF receiver 203. The phase / amplitude adjustment unit 222 adjusts the phase and amplitude of the signal output from the RF reception unit 204 to generate an input signal to the addition unit 221. Since other components are the same as those of the repeater 101 of the first embodiment, the same reference numerals as those of the repeater 101 are given and description thereof is omitted. The configuration of the satellite communication system (the positional relationship between the repeater mounted on the satellite and each terminal) is the same as that in the first embodiment (see FIG. 1).

  The satellite communication system using the repeater 101a according to the present embodiment uses the same frequency or time for the uplink signals of the two terminals, thereby improving the uplink frequency utilization efficiency in addition to the downlink.

  Hereinafter, the operation of the repeater 101a of the present embodiment will be described. As shown in FIG. 1, the uplink signal 108 from the terminal 106 and the uplink signal 110 from the terminal 107 reach the antenna 102. That is, the antenna 102 receives uplink signals transmitted from different terminals. In the present embodiment, when uplink signals 108 and 110 are transmitted at the same frequency, it is possible to separate signals within repeater 101a, thereby improving uplink frequency utilization efficiency.

  A reception signal (received signal from the terminal 107) after the high frequency signal processing is performed by the RF reception unit 204 is output to the A / D conversion unit 206 and the phase / amplitude adjustment unit 222. For the output signal to the A / D conversion unit 206, processing similar to that in the first embodiment is performed in the A / D conversion unit 206 and each of the subsequent stages. On the other hand, the output signal to the phase / amplitude adjustment unit 222 is a signal for canceling or reducing unnecessary components included in the output signal from the RF reception unit 203 (that is, the uplink signal 110 transmitted from the terminal 107). The phase and amplitude are adjusted so that The amount of adjustment of the phase and amplitude is instructed from the control unit 260. There may be a case where only one of the phase and the amplitude is adjusted. Here, in the antenna 103 connected to the RF receiving unit 204, the uplink signal 108 transmitted from the terminal 106 does not exist or is sufficiently weak, so that the phase / amplitude adjustment unit 222 can generate the above-described signal. Become. The adder 221 adds the signal output from the phase / amplitude adjuster 222 to the output of the RF receiver 203, thereby removing the component of the uplink signal 110 from the terminal 107, which is an unnecessary component, from the original signal. it can. Therefore, the demodulator 207 at the subsequent stage can demodulate the uplink signal from the terminal 106. The adding unit 221 and the phase / amplitude adjusting unit 222 operate as unnecessary component reducing means. Other operations are the same as those of the repeater 1 of the first embodiment.

  In order to simplify the description in FIG. 3, the output of the RF receiving unit 204 is input to the phase / amplitude adjusting unit 222 and connected to the adding unit 221. Depending on the situation, it may be considered that a plurality of uplink signals are superimposed on the antenna 103 side, so the repeater according to the second embodiment also has a function of switching connection methods such as reverse connection. .

  As described above, according to the repeater according to the present embodiment, it is possible to allocate uplink signals of a plurality of terminals to the same frequency. Frequency utilization efficiency can be improved.

Embodiment 3 FIG.
FIG. 4 is a diagram illustrating a configuration example of a repeater according to the third embodiment. A repeater 101b shown in FIG. 4 is obtained by replacing the regenerative repeater 250 provided in the repeater 101 (see FIG. 2) of Embodiment 1 with a regenerative repeater 250b. The regeneration relay unit 250 b is obtained by replacing the encoding units 212 and 213 and the exclusive OR unit 214 of the regeneration relay unit 250 with an exclusive OR unit 223 and an encoding unit 224. That is, the replay relay unit 250 and the regenerative relay unit 250b have different execution orders for the encoding process and the exclusive OR calculation process. Since other components are the same as those of the repeater 101 of the first embodiment, the same reference numerals as those of the repeater 101 are given and description thereof is omitted. The configuration of the satellite communication system (the positional relationship between the repeater mounted on the satellite and each terminal) is the same as that in the first embodiment (see FIG. 1).

Hereinafter, the operation of the repeater 101b of the present embodiment will be described. The buffer unit 211 outputs each decoded information bit sequence to the exclusive OR unit 223 in accordance with an instruction from the control unit 260. The exclusive OR unit 223 calculates the exclusive OR of the decoding results (information bit series received from the buffer unit 211) obtained by the decoding units 209 and 210. Specifically, the bit sequence that is the decoding result of the decoding unit 209 is A = {a ₁ , a ₂ , a ₃ ,..., _An }, and the bit sequence that is the decoding result of the decoding unit 210 is B = {b ₁ , B ₂ , b ₃ ,..., B _n }, the output bit sequence of the exclusive OR part is C = {c ₁ , c ₂ , c ₃ ,..., C _n } (where c _i is a _i b _i exclusive OR (XOR)). If the bit sequence lengths of A and B are different, the bit sequence lengths of A to B or both are adjusted so that the sequence lengths of both are the same. As an adjustment method, in addition to expanding the sequence length by copying or adding a part of the original bit sequence or filling it with a known pattern, a part of the original encoded bit sequence is deleted. Although there are various methods such as a method for reducing the sequence length, any method may be used as long as the sequence lengths of A and B can be made the same. Further, the output of the exclusive OR unit 223 may be obtained by further adding the decoding information obtained by the decoding units 209 and 210, for example, information such as the CRC result, to the operation result C of the exclusive OR. Information transmitted to the two terminals is shared by these processes.

  The encoding unit 224 performs error correction encoding, CRC addition, and the like on the output of the exclusive OR unit 223. Note that the encoding unit 224 may add decoding information obtained by the decoding units 209 and 210, for example, information such as a CRC result, in accordance with an instruction from the control unit 260.

  Further, the information sent from the buffer unit 211 to the exclusive OR unit 223 may be changed according to information indicating success / failure of decoding, such as CRC results obtained by the decoding units 209 and 210. For example, when the decoding result of the decoding unit 209 is unsuccessful, that is, the CRC is NG, the information sent to the exclusive OR unit 223 may be a known pattern instead of the information after error correction decoding. This operation is controlled by the control unit 260.

  In addition, although the case where the regenerative repeater 250 of the repeater 101 according to the first embodiment is replaced with the regenerative repeater 250b has been described, the regenerative repeater 250 of the repeater 101a according to the second embodiment is replaced with the regenerative repeater 250b. It is also possible to replace it.

  As described above, according to the repeater according to the present embodiment, since encoding is not performed individually, the same effect as in Embodiments 1 and 2 can be obtained, and the processing amount of the repeater can be reduced. Reduction of circuit scale and low power consumption can be realized.

Embodiment 4 FIG.
FIG. 5 is a diagram illustrating a configuration example of a repeater according to the fourth embodiment. The repeater 101c shown in FIG. 5 is obtained by replacing the regenerative repeater 250b provided in the repeater 101b (see FIG. 4) of Embodiment 3 with a regenerative repeater 250c. The regeneration relay unit 250c is obtained by adding a signal separation unit 225 to the preceding stage of the demodulation units 207 and 208 of the regeneration relay unit 250b. Since other components are the same as those of the repeater 101b of the third embodiment, the same reference numerals as those of the repeater 101b are assigned and description thereof is omitted. The configuration of the satellite communication system (the positional relationship between the repeater mounted on the satellite and each terminal) is the same as that in the first embodiment (see FIG. 1).

  In repeater 101a (see FIG. 3) according to Embodiment 2 described above, upstream signals from two terminals are separated by adder 221 and phase / amplitude adjuster 222 preceding A / D converters 205 and 206. Was configured. On the other hand, in the repeater 101c according to the present embodiment, the signal separation unit 225 in the regenerative relay unit 250c separates the upstream signal. Note that the execution order of the exclusive OR calculation process and the encoding process may be interchanged. That is, the exclusive OR unit 223 and the encoding unit 224 included in the repeater 101c are replaced with the encoding units 221 and 213 and the exclusive OR unit 214 included in the repeater 101 of the first embodiment. It is good also as a structure.

  Hereinafter, the operation of the repeater 101c of the present embodiment will be described. The signal separation unit 225 outputs a signal output from the A / D conversion unit 205 (a digital signal of an upstream signal component received by the antenna 102) and a signal output from the A / D conversion unit 206 (at the antenna 103). The received upstream signal component digital signal) is input and separated by digital signal processing, and the signal corresponding to the upstream signal transmitted from the terminal 106 is sent to the demodulator 207 to the upstream signal transmitted from the terminal 107 Is output to the demodulator 208. As a specific separation method, the method shown in the second embodiment, that is, a signal cancellation method (processing as an unnecessary component reducing unit) that is performed in an analog manner in front of the A / D conversion units 205 and 206 is digital signal processing. 5 or a method such as spatial filtering using the antennas 102 and 103, the connection is not shown in FIG. 5, but the demodulation / decoding results output from the demodulation units 207 and 208 and the decoding units 209 and 210, or Any method can be applied as long as the signal can be digitally spatially separated, such as a method of canceling the signal by feeding back the progress to the signal separation unit 225. The operation of the signal separation unit 225 is controlled by the control unit 260. Other operations are the same as those of the repeater 101b of the third embodiment.

  The case where the regenerative repeater 250b of the repeater 101b according to the third embodiment is replaced with the regenerative repeater 250c has been described. However, the regenerative repeater 250 of the repeater 101 according to the first embodiment is replaced with the regenerative repeater 250c. It is also possible to replace it.

  As described above, according to the repeater according to the present embodiment, uplink signals transmitted at the same frequency from a plurality of terminals are separated by digital signal processing, and therefore separated by the analog signal processing shown in the second embodiment. Compared with the method, the separation can be performed with higher accuracy and the communication quality can be improved. In addition, it is possible to reduce the size and power consumption of the equipment by reducing the number of analog parts.

Embodiment 5 FIG.
FIG. 6 is a diagram of a configuration example of a repeater according to the fifth embodiment. The repeater 101d shown in FIG. 6 is obtained by adding a channelizer unit 300 to the repeater 101c of Embodiment 4 (see FIG. 5). As illustrated, the channelizer unit 300 is inserted between the A / D conversion units 205 and 206, the D / A conversion units 217 and 218, and the regenerative relay unit 250c. Since other components are the same as those of the repeater 101c of the fourth embodiment, the same reference numerals as those of the repeater 101c are assigned and description thereof is omitted. The configuration of the satellite communication system (the positional relationship between the repeater mounted on the satellite and each terminal) is the same as that in the first embodiment (see FIG. 1).

  In FIG. 6, only one set of regenerative relay unit 250 c is connected to channelizer unit 300, but a configuration in which a plurality of regenerative relay units are connected to channelizer unit 300 may be used. In addition, the plurality of regenerative repeaters do not use a function of transmitting a bit sequence to be carried on a downlink signal of a plurality of terminals in the downlink by using the exclusive logic units 223 and 214 to transmit at the same frequency, This function may be used only by some regenerative relay units.

  Moreover, although the number of antennas connected to the channelizer unit 300 is two, a plurality (three or more) of antennas may be connected. In that case, the signals of the two antennas selected by the channelizer among the many antennas are connected to the regenerative repeater 250c.

  Furthermore, in addition to a configuration in which one antenna corresponds to one beam, a configuration in which a plurality of beams formed by a large number of antennas by beam forming are connected to a channelizer may be used.

  Hereinafter, the operation of the repeater 101d of the present embodiment will be described. Channelizer section 300 receives as input the signals received by antennas 102 and 103 and converted into digital signals by A / D conversion sections 205 and 206. Channelizer section 300 divides the band of each beam into a plurality of subchannels (channelizes) and outputs the subchannels and antennas (beams) exchanged to D / A conversion sections 217 and 218. At that time, some of the beams and subchannels are input to the regenerative repeater 250c.

  In addition, although the case where the channelizer part 300 was added with respect to the repeater 101c of Embodiment 4 was demonstrated, you may add the channelizer part 300 with respect to each repeater demonstrated in other embodiment.

  As described above, according to the repeater according to the present embodiment, the same effects as those of the first to fourth embodiments described above can be obtained, and the frequency utilization efficiency can be further increased by the frequency and beam exchange function of the channelizer unit. Can be improved.

  As described above, the present invention is useful for a satellite communication system, and is particularly suitable for a satellite relay apparatus that suppresses deterioration in communication quality in an area where beam areas overlap.

100 Satellite 101, 101a, 101b, 101c, 101d Satellite repeater 102, 103 Antenna 104, 105 Beam area 106, 107 Satellite communication terminal 108, 110 Up signal 112, 113 Down signal 201, 202 Diplexer 203, 204 RF receiver 205 , 206 A / D converter 207, 208 Demodulator 209, 210 Decoder 211 Buffer unit 212, 213, 224 Encoder 214, 223 Exclusive OR unit 215 Spatial encoder 216 Modulator 217, 218 D / A Conversion unit 219, 220 RF transmission unit 221 Addition unit 222 Phase / amplitude adjustment unit 225 Signal separation unit 250, 250b, 250c Regenerative relay unit 260 Control unit 300 Channelizer unit

Claims (15)

A satellite relay device mounted on a communication satellite using a plurality of beams,
Demodulating and decoding means for demodulating and decoding a part or all of the signals received by the plurality of beams for each received signal;
Buffer means for temporarily holding a decoded bit sequence and a decoding result for each beam output from the demodulation decoding means;
Encoding means for selecting any two of the plurality of decoded bit sequences held in the buffer means and error-correcting each of the two;
Exclusive OR calculation means for calculating exclusive OR of two bit sequences after being error-encoded by the encoding means;
Spatial encoding means for performing spatial encoding on the calculation result of the exclusive OR, and generating transmission bit sequences for a plurality of beams;
Modulation means for modulating the transmission bit sequence to generate a modulated signal for each beam;
A satellite relay device comprising: A satellite relay device mounted on a communication satellite using a plurality of beams,
Demodulating and decoding means for demodulating and decoding a part or all of the signals received by the plurality of beams for each received signal;
Buffer means for temporarily holding a decoded bit sequence and a decoding result for each beam output from the demodulation decoding means;
Exclusive OR calculation means for calculating an exclusive OR by selecting any two of the plurality of decoded bit sequences held in the buffer means;
Encoding means for error correcting encoding the exclusive OR;
Spatial coding means for performing spatial coding on the sequence after error coding by the coding means and generating transmission bit sequences for a plurality of beams;
Modulation means for modulating the transmission bit sequence to generate a modulated signal for each beam;
A satellite relay device comprising: An unnecessary component reducing unit that adjusts at least one of the phase and amplitude of a signal received by a specific beam and reduces an unnecessary component from a signal received by a beam other than the specific beam by using an adjusted signal obtained as a result. ,
The satellite relay device according to claim 1, wherein the satellite relay device is provided in a preceding stage of the demodulation and decoding means.   The said unnecessary component reduction means performs the production | generation process of the said adjusted signal, and the reduction process of the said unnecessary component for the received signal before analog-digital conversion is implemented. Satellite relay device.   The said unnecessary component reduction means performs the production | generation process of the said adjusted signal, and the reduction process of the said unnecessary component for the received signal after analog-digital conversion was implemented, The said unnecessary component reduction process is characterized by the above-mentioned. Satellite relay device. Filtering means for reducing unnecessary components contained in the received signal by spatial filtering;
The satellite relay device according to claim 1, wherein the satellite relay device is provided in a preceding stage of the demodulation and decoding means. A channelizer that divides a reception band of each of the plurality of beams into sub-channels and generates an input signal to the demodulation and decoding unit, the unnecessary component reducing unit, or the filtering unit;
The satellite relay device according to claim 1, further comprising: The exclusive OR calculation means includes:
For the two bit sequences to be calculated, if the two sequence lengths do not match, calculate the exclusive OR after deleting a part of the longer bit sequence and matching the two sequence lengths. The satellite relay device according to any one of claims 1 to 7, wherein The exclusive OR calculation means includes:
For the two bit sequences to be calculated, if the two sequence lengths do not match, add a bit pattern to the bit sequence with the shorter sequence length and match the two sequence lengths, and then perform an exclusive OR operation. The satellite repeater according to claim 1, wherein the satellite repeater is calculated.   The satellite relay apparatus according to claim 9, wherein a bit pattern to be added to the bit sequence having a shorter sequence length uses a copy of a part of the original bit sequence.   The satellite relay apparatus according to claim 9, wherein a bit pattern known between transmission and reception is used as a bit pattern to be added to the bit sequence having the shorter sequence length. The exclusive OR calculation means includes:
The satellite relay apparatus according to any one of claims 1 to 11, wherein a decoding result in the demodulation and decoding means corresponding to each input bit sequence is added to a calculation result.   The encoding means outputs a specific bit pattern as a transmission bit sequence without performing encoding processing when a demodulation result corresponding to an input bit sequence is a decoding failure. The satellite relay apparatus as described in any one of 1-12.   14. The modulation unit according to claim 1, wherein at least one of a pilot symbol and a synchronization preamble is added to a transmission bit sequence input from the spatial encoding unit and then modulated. The satellite relay device described in 1.   A satellite communication system, wherein bidirectional communication between satellite communication terminals is realized using the satellite relay device according to claim 1.

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