JP2011029720A - Satellite communication apparatus, and satellite communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a satellite communication apparatus for freely setting a transmission rate or freely arranging frequencies. <P>SOLUTION: The satellite communication apparatus which demultiplexes a received signal, sorts by destination a demultiplexed signal which has been demultiplexed, multiplexes the demultiplexed signal which has been sorted by destination of the demultiplexed signal, and transmits the multiplexed signal being a signal multiplexed includes: FFT sections 9-1 to 9-15 for determining demultiplexed signals by performing FFT processing to received signals; a switch matrix 10 for sorting multiplexed signals by destination; and an IFFT section which converts a signal sorted by the switch matrix 10 into a time domain signal by performing IFFT processing by identical destination and determining the time domain signal as a multiplexed signal. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a satellite communication apparatus that extracts each carrier signal from a multiplexed signal obtained by combining a plurality of carrier signals, and extracts and multiplexes and transmits the plurality of carrier signals.

  Conventionally, a demultiplexing process in which a satellite station decomposes a reception signal multiplexed with a plurality of carrier signals to extract each carrier signal, and conversely, a multiplexing process in which a plurality of carrier signals are multiplexed to generate a transmission signal. A technique for realizing the above by digital signal processing has been proposed. An example of such a technique is described in Non-Patent Document 1 below, for example.

As described in Non-Patent Document 1 below, a multiplex signal composed of M (M is a natural number) carrier signals is Z-transformed, and Y (z) is a filter H (z ), Z _k converted from the signal of the carrier number k (k = 0 to M−1) constituting the multiplexed signal can be expressed by the following equation (1). Note that f _k is a carrier frequency and F _s is a signal sampling frequency.

The filter H (z) is decomposed into ^M sub-filters H _i (z ^M ) (i = 0 to M−1) operating at f _s = F _s / M and a delay component z ⁻ⁱ , and the signal X A signal X _k (z ^M ) _obtained by decimating _k (z) to 1 / M can be expressed as the following equation (2).

Therefore, as described in Non-Patent Document 1 below, M processing units including a delay unit, a sub-filter unit, and a phase offset multiplication unit are provided in parallel, and the following operation is performed. A demultiplexing process can be applied to M carrier signals. First, M delay units perform delay adjustment with a delay amount set for itself on a multiplexed signal in which M carrier signals are multiplexed. Then, the sub-filter unit filters the signal after delay adjustment, and the phase offset multiplication unit gives a phase offset of ω ^j (j = 1 to M) to the filtered signal. Then, an FFT (Fast Fourier Transform) unit performs M-point FFT on the signal after the phase offset is applied, thereby obtaining a signal that is demultiplexed into M carrier signals.

As for the multiplexing process, when M signals X _k (z) pass through the filter H ′ (z) and the multiplexed signal is Y (z ′), Y (z ′) is as follows. (3).

Here, as in the demultiplexing process, when the filter H ′ (z) is decomposed into ^M sub-filters H ′ _i (z ^M ) operating at f _s = F _s / M and the delay component z ⁻ⁱ , the above equation is obtained. (3) can be expressed as the following formula (4).

Therefore, the multiplexing process includes an IFFT unit that performs M-point IFFT processing on each of M signals, a phase offset multiplier that gives each signal a phase offset from ω ⁰ to ω ^M−1 , This can be realized by a configuration including a sub-filter unit for filtering and a delay unit that gives a delay time to the filtered signal.

  On the other hand, as shown in Non-Patent Document 2 below, in a satellite communication system in which a ground station and a ground terminal communicate with each other via a satellite station, a large antenna is mounted on the satellite station, and service areas such as Japan and the vicinity of Japan A concept is underway in which a cell design is made up of about 100 cells and each cell is covered with a multi-beam.

  In the system described in Non-Patent Document 2 below, a ground station-satellite station (hereinafter, this line is referred to as a feeder link) and a satellite station-each ground terminal (hereinafter, this line is referred to as a user link) Both the line and the downlink use different frequency bands. The feeder link uses 450 MHz in the Ka band and the user link uses 30 MHz in the S band. The user link is designed so that the service area is composed of about 100 cells, and it is considered to irradiate a multi-beam with a small diameter from the satellite station to the ground. In this system, there is a 7-cell frequency repetition system that divides a frequency band of 30 MHz from the viewpoint of frequency utilization efficiency, uses different frequency bands in 7 cells, and uses the same frequency in a plurality of places as 7 cells. Assumed.

Fumio Takahata et al. , “A PSK Group Modem for Satellite Communications”, IEEE JOURNAL ON SELECTED AREA IN COMMUNICATIONS, VOL. SAC-5, NO. 4, 1987 Minoru Minowa et al., “Earth / Satellite Integrated Mobile Communication System for Safety and Security”, IEICE Transactions B, Vol. J91-B, no. 12, pp. 1629-1640, 2008

However, according to the technique described in the conventional non-patent document 1, the sub-filter H _i (z) obtained by decomposing the filter H (z) into M pieces is used in the demultiplexing process / combining process. The frequency band of the sub-filter H _i (z) is the same regardless of the value of i. For this reason, it is possible to demultiplex a signal in which a plurality of signals having the same frequency band are multiplexed, or to combine a plurality of signals in the same band, but signals having different bands are multiplexed. There has been a problem that it is not possible to demultiplex signals or combine signals of different bands.

  Further, in the technique described in the above-mentioned conventional non-patent document 1, signal demultiplexing and multiplexing can be performed such that the bands of the carrier signals are arranged at equal intervals, but the bands of the carrier signals are equally spaced. Therefore, it is impossible to deal with the case where the bandwidths of the carrier signals are not equal to each other, and therefore, the demultiplexing process and the multiplexing process cannot be performed on these signals. Therefore, when the conventional technique of Non-Patent Document 1 is adopted in the system described in Non-Patent Document 2, only the signals having the same frequency arrangement can be handled, and there is no degree of freedom in the frequency arrangement. Therefore, there is a problem that the frequency used in the cell cannot be changed according to the state of each cell, and the frequency use efficiency cannot be optimized (flexible frequency use cannot be performed). In addition, there is a problem that the service provided can be limited because the frequency cannot be used flexibly.

  The present invention has been made in view of the above, and an object of the present invention is to provide a satellite communication device and a satellite communication system in which a transmission rate can be freely set and a frequency can be freely arranged as compared with the conventional one. To do.

  In order to solve the above-described problems and achieve the object, the present invention demultiplexes the received signal, distributes the demultiplexed signal after demultiplexing to each destination, and distributes the demultiplexed signal after the distribution to the destination A satellite communication device that multiplexes for each destination of a demultiplexed signal and transmits a combined signal that is a signal after multiplexing, and converts the received signal into a frequency domain signal by FFT processing, and converts the frequency domain signal to the frequency domain signal. FFT processing means for making a demultiplexed signal, switch matrix means for distributing the demultiplexed signal for each destination, and time domain signal by subjecting the demultiplexed signal after distribution by the switch matrix means to IFFT processing for the same destination And IFFT processing means for converting the time domain signal into a combined signal.

  According to the present invention, the switch matrix unit 10 distributes the frequency domain signals after FFT processing to be transmitted to the ground terminal in units of clusters based on the destination numbers of the respective signals, and is distributed in units of clusters. The signal is further distributed to each destination cell, and after the IFFT process is performed on the signal after the distribution, the signal is returned to the time domain and transmitted to each cell. There is an effect that the rate can be set and the frequency can be freely arranged.

FIG. 1 is a diagram illustrating a functional configuration example of a first embodiment of a satellite communication device according to the present invention. FIG. 2 is a diagram illustrating an example of a multiplication result obtained by multiplying a received signal by a window function with a multiplication interval shifted. FIG. 3 is a diagram illustrating a configuration example after the switch matrix unit of the satellite station according to the first embodiment. FIG. 4 is a diagram illustrating a configuration example of the matrix unit. FIG. 5 is a diagram illustrating an example of a result of FFT processing performed by the FFT unit. FIG. 6 is a diagram illustrating a configuration example of a cluster. FIG. 7 is a diagram illustrating an example of a correspondence between a destination number and an output destination signal sorting unit. FIG. 8 is a diagram illustrating an example of input / output signals of the signal sorting unit and signals stored in the second RAM unit. FIG. 9 is a diagram illustrating an example of a process flow of the switch matrix unit. FIG. 10 is a diagram illustrating an image of the synthesis process. FIG. 11 is a diagram illustrating a configuration example of a functional unit that performs processing from receiving a signal from the ground terminal of the satellite station according to the first embodiment to input to the switch matrix unit. FIG. 12 is a diagram illustrating an example of components that perform processing subsequent to the switch matrix unit with respect to the signal received from the ground terminal in the satellite station according to the first embodiment. FIG. 13 is a diagram illustrating a configuration example of the switch matrix unit. FIG. 14A is a diagram illustrating an example of frequency arrangement at equal intervals. FIG. 14B is a diagram of an example of frequency arrangement that is not equally spaced. FIG. 14C is a diagram illustrating an example of a frequency arrangement in which the frequency bandwidth is not constant. FIG. 15 is a diagram illustrating a functional configuration example of the satellite station according to the second embodiment. FIG. 16 is a diagram illustrating an example of frequency band division according to the second embodiment. FIG. 17 is a diagram illustrating the concept of frequency use when three spare systems are provided. FIG. 18 is a diagram illustrating another configuration example of the interpolation unit and the frequency conversion unit. FIG. 19 is a diagram illustrating an example of components that perform reception processing of signals from the ground terminal of the satellite station according to the second embodiment. FIG. 20 is a diagram illustrating the concept of signal processing in the processing of the frequency conversion unit and the thinning-out unit according to the second embodiment. FIG. 21 is a diagram illustrating the concept of the processing of the frequency conversion unit to the FFT unit and the processing of the standby system according to the second embodiment. FIG. 22 is a diagram illustrating a functional configuration example of the satellite station according to the third embodiment. FIG. 23 is a diagram illustrating an example of a frame configuration of a transmission signal according to the third embodiment. FIG. 24 is a diagram illustrating the concept of the FFT calculation start position detection process according to the third embodiment. FIG. 25 is a diagram illustrating an example of a delay time calculation method according to the third embodiment.

  Hereinafter, embodiments of a satellite communication device and a satellite communication system according to the present invention will be described 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 functional configuration example of a first embodiment of a satellite communication apparatus (satellite station) according to the present invention. As shown in FIG. 1, the satellite station of the present embodiment includes a receiving antenna 1, frequency converters 2-1 to 2-15, and A / D (Analog / Digital) converters 3-1 to 3-15. , Quadrature detection units 4-1 to 4-15, LPF (Low Pass Filter) units 5-1 to 5-15, thinning units 6-1 to 6-15, and windowing units 7-1 to 7- 15, FFT (Fast Fourier Transform) units 9-1 to 9-15, a switch matrix unit 10, and a control unit 11.

  The satellite station according to the present embodiment configures a service area with 105 cells, and transmits signals for users to 105 cells. In addition, the satellite station of the present embodiment receives a signal transmitted from the ground station, performs demultiplexing processing on the received signal, extracts each carrier signal, rearranges the extracted carrier signals, and 105 The carrier signal is multiplexed for each destination (105 cells) and transmitted from the satellite station to the ground terminal. FIG. 1 shows components that perform demultiplexing processing and perform processing until the received signal after demultiplexing is input to the switch matrix.

  In the present embodiment, a Ka band signal (feeder link signal) is transmitted from the ground station to the satellite station. This feeder link signal has a bandwidth of 450 MHz and is composed of a plurality of carrier signals.

  The receiving antenna 1 of the satellite station shown in FIG. 1 receives the feeder link signal transmitted from the ground station. The frequency converting unit 2 converts the frequency band of the signal received by the receiving antenna 1 from the Ka band to the IF (Intermediate Frequency) band.

  In addition, it is considered difficult to collectively convert the 450 MHz band signal of the feeder link signal from the viewpoint of the onboard hardware performance, so it is assumed that a plurality of frequency conversion units are provided, 450 Hz is divided, Assume that frequency conversion is performed on a signal in a band divided by each frequency conversion unit. Here, as an example, the bandwidth of a signal converted by one frequency conversion unit is 30 Hz, and 15 (= 450 ÷ 30) frequency conversion units (frequency conversion units 2-1 to 2-15) are provided. To do. Note that the frequency band converted by the frequency converters 2-1 to 2-15 does not necessarily have to be 30 MHz. In addition, when hardware performance is improved in the future, a signal with a bandwidth of 450 MHz is batched. The frequency conversion may be performed by

  The A / D conversion unit 3-i (i = 1, 2,..., 15) converts the reception signal frequency-converted to the IF band from an analog signal to a digital reception signal. The quadrature detection unit 4-i performs quadrature detection of the digital reception signal, converts the digital reception signal from the IF band to the baseband signal, and outputs the in-phase (Ich) signal and the quadrature (Qch) signal of the baseband signal. To do. The LPF unit 5-i performs filtering for cutting unnecessary harmonic components generated in accordance with the quadrature detection process on the in-phase (Ich) signal and the quadrature (Qch) signal of the baseband signal. In this embodiment, the received signal is once converted from the radio frequency band (Ka band) to the IF band and then converted to the baseband. However, the received signal is directly converted from the radio frequency band to the baseband. A direct conversion method may be used.

  The decimation unit 6-i generates a decimation signal with a sampling rate lower than the sampling rate of the A / D conversion unit 3-i by performing decimation processing on the filtered baseband signal. Note that the thinning process performed by the thinning unit 6 is intended to reduce the circuit scale and lower the power consumption at the subsequent stage, and is not always necessary and may be omitted depending on the case.

  The windowing unit 7-i is a window function multiplying unit that multiplies the thinned signal by a window function and outputs a multiplication result. In the subsequent FFT unit 9-i, FFT processing is performed on the thinned signal. However, if there is no continuity at both ends of the section in which the FFT operation is performed, unnecessary harmonics are generated, causing degradation in performance. . For this reason, the windowing unit 7-i multiplies each FFT operation interval by a window function so that both ends of the FFT interval of the received signal have continuity. A typical example of the window function is a Hanning window, but a Hanning window is not necessary as long as both ends of a section converge to the same value.

  Since the received signal information of the portion multiplied by the window function is lost, the windowing unit 7 sets the interval for multiplying the thinned signal (received signal) by the window function when the FFT calculation interval is τ. The multiplication result shifted by 2 is also output. FIG. 2 is a diagram illustrating an example of a multiplication result obtained by multiplying a received signal by a window function with a multiplication interval shifted. The lower part (b) of FIG. 2 has a relationship in which the window function multiplication interval is shifted by τ / 2 with respect to the upper part (a). Here, for easy understanding, the time signal (decimation signal) in FIG. 2 is assumed to have a constant value. As shown in FIG. 2, since the time is shifted by τ / 2, the window function is multiplied in different intervals, and by combining FIGS. 2 (a) and (b), the window function is multiplied. However, no signal information is lost.

The FFT unit 9-i performs 2 ^N -point FFT processing on the thinned signal multiplied by the window function. Although not shown in the figure, each FFT unit 9-1 to 9-15 includes two FFT operation units, because the FFT process is also performed on a signal shifted in time by τ / 2. I have. The FFT unit 9-i converts the thinned signal into a frequency domain signal by FFT processing, and extracts a plurality of carrier signals included in the received signal in units of frequency samples (1 sample = 30 MHz / 2 ^N points). be able to. That is, in the processing up to the FFT unit 9-i, it is possible to demultiplex a received signal in which a plurality of carrier signals are multiplexed and extract a carrier signal that is a demultiplexed signal. The frequency domain signal is input to the switch matrix unit 10.

  FIG. 3 is a diagram illustrating a configuration example after the switch matrix unit 10 of the satellite station according to the present embodiment. As shown in FIG. 3, the satellite station of the present embodiment includes a switch matrix unit 10, a control unit 11, and IFFT units 21-1 to 21-105 as components that perform processing after the switch matrix unit 10. , Signal synthesis units 23-1 to 23-105, interpolation units 24-1 to 24-105, orthogonal modulation units 25-1 to 25-105, and D / A (Digital / Analog) conversion units 26-1 to 26-1. 26-105, frequency conversion units 27-1 to 27-105, and transmission antennas 28-1 to 28-105.

  As described with reference to FIG. 1, the switch matrix unit 10 receives frequency domain signals output from the 15 parallel input FFT units 9-1 to 9-15 based on the control information of the control unit 11. , 105 for each destination (signal transmission destination). As in the FFT units 9-1 to 9-15, the switch matrix unit 10 also has a frequency domain signal corresponding to a thinned signal (received signal) multiplied by a window function without shifting τ / 2 as shown in FIG. The processing corresponding to the two signals, ie, the frequency domain signal corresponding to the thinned signal multiplied by the window function with the time shifted by τ / 2, is performed, and the operations for the two signals are the same. Therefore, in the following, the processing for the frequency domain signal corresponding to the thinned signal (received signal) multiplied by the window function without shifting τ / 2 will be described. However, the thinned signal multiplied by the window function while shifting the time by τ / 2 is described. The processing for the corresponding frequency domain signal is the same as that processing.

  FIG. 4 is a diagram illustrating a configuration example of the matrix unit 10. The switch matrix unit 10 of the present embodiment includes a first RAM (Random Access Memory) unit 14-1 to 14-15, a signal sort unit 15-1 to 15-15, and a second RAM unit 16-1 to 16-15. And third RAM units 17-1 to 17-105.

  The frequency domain signal output from the FFT unit 9-i is input to the first RAM unit 14-i. The first RAM unit 14-i includes a memory for holding data, and stores (writes) only “significant signal” in the frequency domain signal converted by the FFT unit 9-i in its own memory. ). Hereinafter, the “significant signal” stored in the first RAM unit 14-i will be described.

  FIG. 5 is a diagram illustrating an example of a result (frequency domain signal) subjected to FFT processing by the FFT unit 9-i. As shown in FIG. 5, the 30 MHz band frequency domain signal converted by the FFT unit 9-i has no signal component removed as an unnecessary component by filtering of the LPF unit 5-i (out-of-band component). Exists. Since the out-of-band component does not include information and is not necessary for subsequent signal processing, the first RAM unit 14-i stores a signal other than the out-of-band component (referred to as a “significant signal”). By storing only this “significant signal”, that is, only the signal of the frequency component in the band, the memory capacity of the first RAM unit 14-i can be reduced.

  The control unit 11 reads out the signal stored in the first RAM unit 14-i, and with respect to the signal, a destination number that is a number for identifying a destination cell of the signal and a signal arrangement in each destination cell And a signal after the addition are stored in the first RAM unit 14-i. The number of destinations of the signals stored in the first RAM unit 14 is 105, and it is necessary to distribute each signal stored in the first RAM units 14-1 to 14-15 to 105 destinations (destination numbers 1 to 105). is there. However, in order to distribute the signals written in the 15 first RAM units (first RAM units 14-1 to 14-15) to 105 destinations, respectively, there are 1575 signal lines (= 15). × 105) Required. This is not desirable from the viewpoint of circuit scale.

  Therefore, in the present embodiment, seven cells are grouped as one group (hereinafter, this group is referred to as a cluster), and sorting is performed in two stages: sorting in units of clusters and sorting in clusters. FIG. 6 is a diagram illustrating a configuration example of a cluster. In the figure, small circles described as # 1, # 2,... Represent cells, and the numbers described after # described in each cell indicate signal destination numbers. In the example of FIG. 6, thick circles surrounding seven cells # 1 to # 7, # 8 to # 14,... Indicate clusters.

  First, in the first-stage sorting process, the signals stored in the first RAM units 14-1 to 14-15 are sorted in units of clusters. As shown in FIG. 6, a cluster is an area in which seven terrestrial destinations (cells) for transmitting signals from satellite stations are collected. In FIG. 6, only 28 destination numbers are shown for the sake of space, but there are actually cells up to destination number 105.

  The first RAM unit 14-i holds the signal sorting unit 15 corresponding to the destination number added to the signal based on the correspondence between the destination number and the output destination signal sorting unit. Output to -1 to 15-15. FIG. 7 is a diagram illustrating an example of a correspondence between a destination number and an output destination signal sorting unit. As shown in FIG. 7, it is assumed that the destination number and the signal sorting units 15-1 to 15-15 are associated with each other, and the first RAM unit 14-i holds such a correspondence. At this time, the number of destination cells is 105, and a cluster is composed of 7 cells, so the total number of clusters is 15 (= 105 ÷ 7). Therefore, the number of signal sorting units corresponding to each cluster is 15 (signal sorting units 15-1 to 15-15). Instead of the first RAM unit 14-i holding this correspondence (correspondence between the destination number and the output signal sorting unit), the control unit 11 holds this correspondence and is stored in the first RAM unit 14-i. When the stored data is read out, the first RAM unit 14-i may be instructed to output a signal to the corresponding signal sorting unit based on the stored correspondence.

  The signal sorting unit 15-j (j = 1, 2,..., 15) to which the signal output from the first RAM unit 14-i is input performs a traffic equalization process on the input signal and performs processing. The subsequent signal is output to the second RAM unit 16-j. The second RAM unit 16-j includes 15 memories (the same number as the first RAM unit that is the input source to the signal sort unit), and the signal sort unit 15-j performs rearrangement by traffic equalization processing. Later, a signal output from the first RAM unit 14-i is output to one of the memories in the second RAM unit 16-j.

  Here, the traffic equalization processing performed by the signal sorting unit 15-j will be described. FIG. 8 is a diagram illustrating an example of input / output signals of the signal sorting unit 15-j and signals stored in the second RAM unit 16. In the present embodiment, the satellite station includes 15 first RAM units and the number of destinations is 105. However, in order to simplify the description, in the example of FIG. The number of cells is 21 (3 clusters).

  FIG. 8A schematically shows a signal input to the signal sorting unit. The vertical direction in the figure shows values obtained by discretizing time in predetermined time units. The input #M in the horizontal direction (here, M = 1, 2, 3) is input from the first RAM unit 14-M to the signal sorting unit 15-j (in this case, j = 1, 2, 3). A signal is shown, and a portion having no value (blank) indicates that there is no input signal. In the figure, A0, A1,..., B1,..., C1,... Are input signal identification numbers assigned to explain the signals input from the first RAM unit 14-M, and A is the first identification. The number is the signal input from the first RAM unit 14-1, the identification number prefixed with B is the signal input from the first RAM unit 14-2, and the identification number prefixed with C is the first RAM unit. The signals input from 14-3 are respectively shown.

  Focusing on each input signal in FIG. 8A, the number of signals of input # 1 and input # 3 is large, whereas the number of signals of input # 2 is small. If the signal sorting units 15-1 to 15-3 are not present, the signal input to the first RAM unit 14-j is output to the second RAM unit 16-j. In this case, as shown in FIG. 8A, the number of signals varies depending on each input, and even when there is a time during which no signal is input, the second RAM unit 16-j is output from the first RAM unit 14-j. It is necessary to store all the signals including the data for which no signals exist in their own memories.

For example, the second RAM unit 16-j receives a signal input from the first RAM unit 14-1 to its own memory # 1, a signal input from the first RAM unit 14-2 to its own memory # 2,. Store in order. Therefore, the second RAM unit 16-j has a memory capacity capable of storing Ra (Ra is the number of the first RAM 14) × 2 ^N (2 ^N is the number of FFT points) × SD (SD is the number of bits of each signal information). There is a need. The second RAM section 16-j requires a memory capacity of 3 × 2 ^N × SD in the example of FIG. 8, and the memory capacity of 15 × 2 ^N × SD is required in the configuration of FIG. 4 with Ra = 15. .

  On the other hand, in the present embodiment, the signal sorting unit 15-j converts an input signal as shown in (a) of FIG. 8 into a specific output destination (specific The traffic is equalized so that the signal does not concentrate on the memory) and output to the memory. Here, as described above, since the number of first RAM units is three, the number of memories constituting the second RAM unit 16-j is three from memory # 1 to memory # 3. The horizontal output #M in FIG. 8B indicates that the output is output to the memory #M of the second RAM unit 16-j.

  Specifically, for example, the input # 1 (input to the signal sorting unit 15-1) includes A0 and A1 signal inputs continuously at time “0” and time “1”. 2 (input to the signal sorting unit 15-2), there is no signal input at time “0”, but there is an input of the B1 signal at time “1”, and input # 3 (signal sorting unit 15-3). No input at time “0” and time “1”. In such a case, the signal sorting unit 15-j outputs the signal A0 input at time “0” to the memory # 2 of the second RAM unit 16-j as output # 1, and is input at time “1”. The signal A1 is output as output # 2 to the memory # 2 of the second RAM unit 16-j. Further, the signal sorting unit 15-2 outputs the signal B1 input at time “1” to the memory # 3 of the second RAM unit 16-j as an output # 3.

  By performing such an operation, the output destination of each signal becomes the output destination shown in FIG. For example, in FIG. 8A, seven signals (A0 to A6) are input # 1, three signals (B1 to B3) are input # 2, and eight signals (C1 to C8) are input # 3. While the signal and traffic are biased, in FIG. 8B, six signals are allocated to all of the output # 1, the output # 2, and the output # 3, and the traffic is made uniform. A specific output destination selection method for equalizing traffic in this way may be any method. For example, the number of signals for each output destination with respect to a signal input within a predetermined time. In the case of non-uniformity, the process of selecting a predetermined signal from the output destination signals having a large number of signals and setting the selected signal as another output destination is made as many as possible for each output destination. There are methods such as determining the output destination repeatedly.

  As shown in (c) of FIG. 8, the second RAM unit 16-j sends a signal after the traffic is uniformized by the signal sorting unit 15-j to each memory. The signal (excluding the nonexistent portion) is written. Here, the case where the number of first RAM units is three has been described, but when the number of first RAM units is 15 as in the configuration of FIG. The output destination is selected so as to be uniformly output to the 15 memories of the second RAM unit 16-j.

In this way, the signal sorting unit 15-j equalizes and outputs the traffic of the input signal, so that the memory capacity required by the second RAM unit 16-j is 2 ^N × SD, that is, the signal sorting. It can be reduced to 1 / Ra when the part 15-j does not exist. In the example of FIG. 8 (Ra = 3), the signal sorting unit 15-j is used to reduce the memory capacity of the second RAM unit 16-j to 1/3, and in the configuration of FIG. 4 (Ra = 15), 1/15. Each can be reduced.

Returning to the description of the operation based on the configuration example of FIG. The first RAM unit 14-i distributes the signals stored as described above to the signal sorting units 15-1 to 15-15 corresponding to each cluster, and each signal passes through the signal sorting unit 15-j. The data is written in the second RAM unit 16-j. If there is a possibility that communication traffic to one cluster exceeds the system bandwidth (30 MHz), the memory capacity of the second RAM unit 16-j is set to 2 ^N × SD + α, and the memory capacity is slightly increased. .

  Next, as the distribution process in the second stage, the second RAM unit 16-j reads the signal stored in its own memory # 1 to # 15, and seven third RAM units (for each destination number of the signal) The output destinations are distributed to the third RAM units 17-1 to 17-15). For example, the second RAM unit 16-1 sends a signal having a destination number of 1 (a signal destined for cell # 1) to the third RAM unit 17-1, and a signal having a destination number of 2 (a signal destined for cell # 2). ) To the third RAM unit 17-2,..., And the second RAM unit 16-2 connects the signal having the destination number 8 (the signal destined for the cell # 8) to the third RAM unit 17-8, and so on. Output to each of the seven third RAM units. The third RAM units 17-1 to 17-105 include a memory for holding a signal, and store the input signal in the memory.

  Then, the IFFT unit 21-k (k = 1, 2,..., 105) reads the signal stored in the third RAM unit 17-k for each channel number, sets the signal for each channel number as a frequency domain signal, The frequency domain signal is converted into a time domain signal by IFFT processing.

FIG. 9 is a diagram illustrating an example of a processing flow of the switch matrix unit 10. FIG. 9 shows an example in which three FFT units and three first RAM units are provided for the sake of simplicity of the page and the explanation, and the number of destination cells is 21 (the number of clusters is 3). (1) in FIG. 9 shows frequency domain signals input from the FFT units 9-1 to 9-3, (2) shows signals written in the first RAM units 14-1 to 14-3, 3) shows signals written in the second RAM units 16-1 to 16-21, and (4) shows signals written in the third RAM units 17-1 to 17-21. Also, the rectangles in the figure indicate each signal, and the number in the rectangle indicates the destination number of the signal. In FIG. 9, the horizontal axis indicates a value obtained by discretizing the 30 MHz band into 0 to 2 ^N samples, that is, the frequency. Hereinafter, each signal shown in (1) to (4) will be described.

(1) The frequency domain signal FFT units 9-1 to 9-3 input from the FFT units 9-1 to 9-3 receive the received signals by ^2N- point FFT processing as shown in (1) of FIG. Is converted into a frequency domain signal of a bandwidth of 30 MHz (2 ^N samples) and output to the switch matrix unit 10. By this processing, a plurality of carrier signals included in the received signal can be separated in units of 30 MHz / 2 ^N samples.

(2) The signal first RAM section 14-i (i = 1, 2, 3 in the example of FIG. 9) written in the first RAM sections 14-1 to 14-3 is, as described above, the FFT section 9-i. Among the frequency domain signals output from the "significant signal" is written in its own memory.

(3) Signals written in the second RAM units 16-1 to 16-3 The signals assigned to the first RAM units 14-1 to 14-3 for each cluster are stored in the second RAM units 16-1 to 16-3. The data is written via the signal sorting units 15-1 to 15-3. In the example of FIG. 9, the second RAM unit 16-1 has destination numbers 1 to 7, the second RAM unit 16-2 has destination numbers 8 to 14, and the second RAM unit 16-3 has destination numbers 15 to 15. Up to 21 signals are distributed. Actually, each signal is not continuous for each destination as shown in FIG. 9, but discrete signals in units of samples are arranged. However, for convenience of explanation and illustration, each signal is for each destination. It is assumed that it is gathered together. The processing is the same when discrete signals in units of samples are arranged.

(4) Signals written to the third RAM units 17-1 to 17-21 The signals distributed for each destination number are written to the third RAM units 17-1 to 17-21 together with the channel numbers. At this time, the signal arrangement can be freely set by rewriting the channel number.

  Through the processing of the switch matrix unit 10 described above, the frequency domain signals output from the FFT units 9-1 to 9-3 are rearranged according to the destination number (destination cell) as shown in (4) of FIG. be able to. In the configuration shown in FIG. 4, the signals written in the first RAM units 14-1 to 14-15 are not directly distributed to the 105 destinations, but first, the signal sorting units 15-1 to 15-15 in units of clusters. By allocating to -15, the circuit scale is reduced. Further, the signal sorting units 15-1 to 15-15 perform processing for equalizing the traffic on the signals input from the first RAM units 14-1 to 14-15, and the second RAM units 16-1 to 16-15. Therefore, the memory capacity required for the second RAM units 16-1 to 16-15 can be reduced.

  After the processing of the switch matrix unit 10, the IFFT unit 21-k (k = 1, 2,..., 105) converts the frequency domain signals arranged for each destination stored in the third RAM unit 17-k to the time. Convert to domain signal. By this processing, a time domain signal obtained by combining a plurality of carriers is generated. The IFFT unit 21-k performs a multiplexing process for multiplexing a plurality of carriers with the same destination. The IFFT units 21-1 to 21-105 also perform the FFT processing by multiplying the window function without shifting the time described with reference to FIG. 2, similarly to the FFT units 9-1 to 9-15 and the switch matrix unit 10. In order to process two systems of signals, the executed signal and the signal that has been subjected to FFT processing by shifting the time by τ / 2 and multiplied by the window function, two processing units are provided.

  The signal synthesis unit 23-k multiplies the window function by multiplying the window function without shifting the time and performs the FFT process, and the signal by shifting the time by τ / 2 and multiplying the window function by performing the FFT process. Synthesis is performed using the IFFT processing results for the two systems of signals, and a signal free from missing signal information due to multiplication of the window function is generated. More specifically, a portion without data loss due to the respective window functions is extracted from the signals of both systems and synthesized. FIG. 10 is a diagram illustrating an image of the synthesis process. (A) and (b) in FIG. 10 correspond to (a) and (b) shown in FIG. 2, respectively. FIG. 10C shows a signal image synthesized by the signal synthesizers 23-1 to 23-105. The signal synthesizers 23-1 to 23-105 perform the section (section other than the shaded area in FIG. 10A) removed by the multiplication of the window function from the signal in FIG. ) Is replaced with a section of a signal that is not removed by the window function multiplication (dot filling section), thereby outputting a signal with no signal loss due to the window function multiplication, as shown in FIG.

  The interpolation unit 24-k performs an upsampling process for increasing the sampling speed on the signal synthesized by the signal synthesis unit 23-k. This upsampling process is performed in order to match the sampling rate of the signal with the sampling rate of the D / A conversion unit 26-k in the subsequent stage. The quadrature modulation unit 25-k converts the signal input from the interpolation unit 24-k as a baseband signal into an IF band. The D / A converter 26-k converts the IF band signal from digital to analog, and the frequency converter 27-k converts the IF band analog signal into the S band. Here, the frequency conversion from the baseband to the S band is performed via the IF band, but the frequency conversion may be performed directly from the baseband to the S band.

  The transmission antenna 28-k transmits the signal input from the frequency conversion unit 27-k to the destination cell by irradiating the ground cell with a beam. Finally, the ground terminal existing in each cell receives the signal transmitted from the satellite station. In this way, the satellite station receives a signal including a plurality of carrier signals transmitted from the ground station, and the satellite station performs demultiplexing processing of the received signal, rearrangement of signals for each destination, and multiplexing processing. Communication between the satellite station and each ground terminal is performed.

  Subsequently, the satellite station according to the present embodiment receives a signal from the ground terminal located in the covered area 105 (cell), generates a signal to be transmitted to the ground station, or transmits the signal again to the ground terminal. The flow will be described.

  FIG. 11 is a diagram illustrating a configuration example of a functional unit that performs processing from receiving a signal from the ground terminal of the satellite station according to the present embodiment to input to the switch matrix unit. As shown in FIG. 11, functional units that perform processing from receiving a signal from the ground terminal to being input to the switch matrix unit include reception antennas 30-1 to 30-105 and frequency conversion units 31-1 to 31. -105, A / D conversion units 32-1 to 32-15, quadrature detection units 33-1 to 33-15, LPF units 34-1 to 34-105, and thinning units 35-1 to 35-105 And windowing units 36-1 to 36-105 and FFT units 37-1 to 37-105.

  The satellite station of the present embodiment is provided with the receiving antenna units for receiving signals from the terrestrial terminal for the number of 105 beams, and 105 components for the subsequent processing are also arranged in parallel for each beam. It becomes a lined configuration.

  The reception antenna unit 30-k (k = 1, 2,..., 105) receives a signal transmitted from a ground terminal existing in each cell, and the frequency conversion unit 31-k receives the reception antenna unit 30-k. Converts the frequency of the received signal from the S band to the IF band. The A / D conversion unit 32-k converts an IF band reception signal, which is an analog signal, into a digital signal. The quadrature detection unit 33-k performs quadrature detection of the digital reception signal, and converts the digital reception signal from the IF band. While converting into a baseband signal, the in-phase signal and quadrature signal of a baseband signal are output. The LPF unit 34-k performs filtering for cutting unnecessary harmonic components generated in association with the quadrature detection process on the in-phase signal and the quadrature signal of the baseband signal.

  The thinning unit 35-k performs a thinning process on the baseband signal after filtering in the same manner as the thinning unit 6-i. Similar to the windowing unit 7-i, the windowing unit 36-k multiplies the thinned signal by a window function and outputs the multiplication result. Similarly to the windowing unit 7-i, the windowing unit 36-k also outputs the result of multiplying the window function by shifting the time by τ / 2. The FFT unit 37-k converts the two signals output from the windowing unit 36-k into a frequency domain signal by performing an FFT process to obtain a demultiplexed signal.

  FIG. 12 is a diagram illustrating an example of components that perform processing subsequent to the switch matrix unit with respect to the signal received from the ground terminal in the satellite station according to the present embodiment. As shown in FIG. 12, the satellite station includes a switch matrix unit 38, a control unit 11, IFFT (Inverse FFT) units 41-1 to 41-15, and signal synthesis as components that perform processing after the switch matrix unit. Units 42-1 to 42-15, interpolation units 43-1 to 43-15, quadrature modulation units 44-1 to 44-15, D / A conversion units 45-1 to 45-15, and a frequency conversion unit 46-1 to 46-15, an adder 47, and a transmission antenna 48.

  FIG. 13 is a diagram illustrating a configuration example of the switch matrix unit 38. As illustrated in FIG. 13, the switch matrix unit 38 includes fourth RAM units 50-1 to 50-105, signal sort units 51-1 to 51-15, fifth RAM units 52-1 to 52-15, Sorting units 53-1 to 53-15 and sixth RAM units 54-1 to 54-15 are provided.

  The frequency domain signal converted by the FFT unit 37-k is input to the fourth RAM unit 50-k. The fourth RAM unit 50-k includes a memory for holding data, and stores the input frequency domain signal in the memory. The control unit 11 reads the signal stored in the fourth RAM unit 50-k, and based on the destination of the read signal, the control unit 11 receives the destination number (if the destination is a ground terminal, the number for identifying the cell, the destination is In the case of the ground station, a number indicating the ground station) and a channel number are added, and the added signal is stored in the fourth RAM unit 50-k. The fourth RAM unit 50-k, like the first RAM unit 14-i, has an identification number of the input source fourth RAM unit 50-k (in this case, the identifier is k in the case of the fourth RAM unit 50-k) and an output destination. The signal sort unit (any of signal sort units 51-1 to 51-15) corresponding to the destination number is stored in the signal stored based on the held correspondence. ). The correspondence between the destination number held by the fourth RAM unit 50-k and the output signal sorting unit is the same as in FIG. 2, but the signal sorting unit 15-j (j = 1, 2,..., 15 ) Is replaced with the signal sorting unit 51-j.

The signal sorting unit 51-j outputs the signals input from the fourth RAM units 50-1 to 50-105 to the fifth RAM unit 52-j. At this time, as with the signal sorting unit 15-j, the traffic is uniform. Do. When not passing through the signal sorting unit 51-j, the fifth RAM unit 52-j can store Rb (the number of signal lines input from the fourth RAM unit 50-k to the fifth RAM unit 52-j) × 2 ^N × SD. Memory is needed. In the case of the example of FIG. 13, since Rb = 7, the fifth RAM unit 52-j needs a memory capacity capable of storing 7 × 2 ^N × SD.

On the other hand, in the present embodiment, by using the signal sorting unit 51-j to equalize traffic, the fifth RAM unit 52-j only needs to have a memory capable of storing a capacity of 2 ^N × SD. . That is, by using the signal sorting unit 51-j, the memory capacity of the fifth RAM unit 52-j can be reduced to 1 / Rb as compared with the case where the signal sorting unit 51-j is not used.

  The fifth RAM unit 52-j stores the signal input from the signal sort unit 51-j in its own memory, and the stored signal is stored in the signal sort units 53-1 to 53 according to the destination number of the signal. Allocate to -15. This allocation is performed by the fifth RAM unit 52-j holding the correspondence similar to that of FIG. 2 in which the signal sorting unit 53-j is used instead of the signal sorting unit 15-j, and using this correspondence. If the destination number is a ground station, the allocation destination is arbitrary. The signal sorting unit 53-j performs traffic equalization on the signal input from the fifth RAM unit 52-j in the same manner as the signal sorting unit 15-j, and performs the sixth RAM unit 54-i (i = 1, 2,..., 15). By using the signal sorting unit 53-j, the memory capacity of the sixth RAM unit 54-i can be reduced to 1 / Rc compared to the case where the signal sorting unit 53-j is not used. However, Rc is the number of signal lines from the fifth RAM section 52-j that are input to one sixth RAM section 54-i.

  The signals stored in the sixth RAM section 54-i are read by the IFFT section 41-i in the order of channel numbers, and are subjected to a multiplexing process by performing an IFFT process on the read signals. When the destination number is not a ground station but a cell identification number (in the case of a single-hop signal for the ground terminal), the signal stored in the sixth RAM unit 54-i is the first RAM unit 14- output to i. The first RAM unit 14-i treats the signal input from the sixth RAM unit 54-i in the same manner as the signal input from the FFT unit 9-i, and performs the same process as the transmission process to the ground terminal described above. Send to the destination cell.

  The signal synthesizer 42-i synthesizes two systems of signals in the same manner as the signal synthesizer 23-k, and the interpolator 43-i upsamples the input signal in the same manner as the interpolator 24-i. The quadrature modulation unit 44-i converts the signal input from the interpolation unit 43-k as a baseband signal into an IF band. The D / A converter 45-i converts the IF band signal from digital to analog, and the frequency converter 46-i converts the IF band analog signal into the Ka band. Then, the adder 47 adds signals having a bandwidth of 30 MHz input from the frequency converters 46-1 to 46-15, and outputs the signals to the transmission antenna 48 as a signal having a bandwidth of 450 MHz. The transmitting antenna 48 transmits a signal having a bandwidth of 450 MHz to the ground station.

  As described above, in the present embodiment, the frequency domain signal after FFT processing to be transmitted to the ground terminal is obtained as a demultiplexed signal, and the switch matrix unit performs the cluster unit based on the destination number of each demultiplexed signal. The distribution is performed, and the signal distributed in units of clusters is further distributed for each destination cell. Then, the IFFT process is performed after the distribution, so that a time domain signal is transmitted to each cell as a combined signal. Therefore, the frequency to be used can be freely set by changing the channel number of the signal distributed for each cell.

  14-1 to 14-13 are diagrams illustrating examples of signal frequency arrangement. In a conventional satellite station, as shown in FIG. 14-1, signal carrier demultiplexing or multiplexing can be performed so that the bands of the carrier signals are arranged at equal intervals, but as shown in FIG. It is difficult to realize a signal arrangement that is not spaced. Further, as shown in FIG. 14-3, signals having different (not constant) frequency bandwidths cannot be subjected to demultiplexing processing or multiplexing processing. On the other hand, in this embodiment, demultiplexing processing or multiplexing processing of signal arrangement as shown in FIGS. 14-2 and 14-3 can be performed, and flexible frequency utilization can be realized.

  In addition, after the signal received from the ground terminal is converted into a frequency domain signal by FFT processing, when the switch matrix unit 38 collects the signals for each cluster and transmits the signals to the ground terminal, each destination number is further addressed. The signals are distributed and input to the switch matrix unit 10 in cluster units. In the case of addressing to the ground station, the signals collected for each cluster are frequency-converted and transmitted to the ground station. Therefore, there is no restriction on the receivable frequency arrangement for signals received from the ground terminal, and flexible frequency utilization can be realized.

  In addition, the signal sort units 15-1 to 15-15, 51-1 to 51-15, 53-1 to 53-15 perform the traffic equalization, so that the memory of the switch matrix 10 or the switch matrix 38 is stored. The capacity can be reduced and the circuit scale can be suppressed.

Embodiment 2. FIG.
FIG. 15 is a diagram illustrating a functional configuration example of the second embodiment of the satellite station according to the present invention. The satellite station of the present embodiment has the same components as those in FIG. 1 from the receiving antenna 1 to the switch matrix unit 10 among the components that perform the process of receiving from the ground station to the ground terminal. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  As shown in FIG. 15, the constituent elements that perform the process of receiving the ground terminal transmitted from the ground station of the satellite station of the present embodiment are the same as the interpolation unit 60-1 in the configuration shown in FIG. 3 of the first embodiment. ˜60-105, frequency conversion units 61-1 to 61-105, backup system synthesis units 62-1 to 62-105, backup system 63, and control unit 64 are added, and IFFT unit 21-1 Are the same as those of the satellite station of the first embodiment except that IFFT units 21a-1 to 21a-105 are provided instead of to 21-105. The standby system 63 includes an IFFT unit 21a-106, a signal synthesis unit 23-106, an interpolation unit 60-106, and a frequency conversion unit 61-106.

  In FIG. 15, the components for 7 beams corresponding to one cluster are illustrated like the transmission antennas 28-1 to 28-7, but in reality, 15 configurations for 7 beams are arranged in parallel. In the same manner as in the first embodiment, 105 beams are arranged in parallel.

In the present embodiment, a method for reducing the circuit scale of the IFFT unit 21a as compared with the IFFT unit 21 of the first embodiment will be described. As shown in FIG. 3, the satellite station of the first embodiment performs IFFT units that perform 2 ^N points of IFFT processing for the number of beams corresponding to the number of destinations of signals (number of destinations = number of beams), That is, 105 are provided. These IFFT units 21a-1 to 21a-105 have a performance of performing 2 ^N points of IFFT processing on a signal having a frequency bandwidth of 30 MHz used in the user link.

Here, as in the first embodiment, assuming a 7-cell frequency repetition system and assuming that a total of seven frequency bands irradiating a destination on the ground from a satellite use a maximum frequency band of 30 MHz, each beam has a frequency band of 30 MHz. It is not occupied (because the 30 MHz frequency band is divided and used by 7 cells), and on average, a 1/7 frequency band of 30 MHz is used. That is, it is not necessary to provide 105 ^2N- point IFFT units assuming a 30 MHz band. In this embodiment, paying attention to this point, the circuit scale is reduced.

  FIG. 16 is a diagram illustrating an example of frequency band division according to the present embodiment. In this embodiment, the frequency used in each beam (destination cell) is divided equally into 8 frequency bands of CH (Channel) # 1 to CH # 8 as shown in FIG. ing. In this way, by dividing the frequency band in advance and assigning it to seven beams (seven cells in the same cluster), in the processing corresponding to each beam, if the assigned frequency band is to be processed. It will be good.

In the example shown in FIG. 16, since the frequency bandwidth is equally divided into eight, the frequency bandwidth processed by one beam is 1/8 of 30 MHz. That is, one in the processing of the beams, it is possible to reduce the number of IFFT points from 2 ^N to 2 ^N-3. The frequency band of 30 MHz divided in this way is assigned to 7 beams, one for each beam, and each beam communicates with the ground terminal using the assigned frequency. At this time, 30/8 MHz (for one beam) remains, but the remaining frequency band will be described later.

Thus, for each beam, by assigning 8 equally divided frequency 30 MHz, 1 single is the frequency bandwidth IFFT unit processes 30/8 MHz next, IFFT points is also 2 from 2 ^N point ^N / It can be reduced to 8 (= 2 ^N−3 ) points. Therefore, the circuit scale of the IFFT unit is 1/8 or less compared to the first embodiment.

The operation of this embodiment will be described with reference to FIG. The IFFT units 29a-k (k = 1, 2,..., 105) read out signals stored in the third RAM unit 17-k of the switch matrix unit 10, and 2 ^N / 8-point IFFTs with respect to the read signals. Perform processing and convert to time domain signal. In this embodiment, since it is 2 ^N / 8, the signal sampling rate is 1/8 times that in the case where the number of IFFT points is 2 ^N. Therefore, after the signal synthesis unit 23-k performs signal synthesis on the time domain signal converted by the IFFT unit 29a-k as in the first embodiment, the interpolation unit 60-k sets the sampling rate. Interpolate the signal to increase it to 8 times.

  The frequency converting unit 61-k converts the center frequency of the signal into the center frequency of the frequency band (CH number) assigned to the beam corresponding to the signal. Subsequent processing (interpolation unit 24-k to transmission antenna 28-k) other than the processing of backup system combining unit 62-k described later is the same as that of the first embodiment.

  Through the above processing, a transmission signal having a bandwidth per beam of 30/8 MHz is generated and transmitted to the ground terminal. By the way, as described above, in this embodiment, 30 MHz is divided into eight, and the divided frequencies are assigned to seven beams (destination), so the frequency band for one beam remains. By utilizing this surplus frequency as a spare frequency and using this spare frequency for a cell in which communication is concentrated, the available frequency bandwidth can be doubled.

  For example, it is assumed that communication to cells corresponding to beam # 1 is concentrated and it is necessary to use a frequency of 30/8 MHz or higher. In such a case, the standby system 63 is operated to use the backup frequency. It is assumed that the standby system 63 is not operating during normal times (when the backup frequency is not used). The control unit 64 generates a path connecting from the switch matrix unit 10 to the IFFT units 21a to 106 of the standby system 63. For example, when the beam # 1 uses a spare frequency, the IFFT unit 21a-106 generates a path through which a signal is input from the switch matrix unit 10.

  In the first embodiment, the switch matrix unit 10 simply outputs signals to the IFFT unit 21-k in the order of channel numbers. However, in this embodiment, the switch matrix unit 10 is a spare as described above. Signal output to the system 63 is also performed. That is, in the first embodiment, one second RAM unit distributes signals to the third RAM unit arranged in parallel by seven destination numbers, but in the present embodiment, the second RAM unit is connected to one second RAM unit. There are eight 3RAM units, and when a spare frequency is used, a signal transmitted at that frequency is output to the eighth third RAM unit. Then, the signal stored in the eighth third RAM section is input to the standby system 63. In addition, when using the spare frequency, the data to be transmitted with the beam is the data to be transmitted with the spare frequency (CH # 8), the data to be transmitted with the normal allocation frequency (CH # 1 to CH # 7), However, this distribution may be performed by the control unit 64 or the control unit 11, for example.

  In the standby system 63, the IFFT unit 21a-106, the signal synthesis unit 23-106, the interpolation unit 60-106, and the frequency conversion unit 61-106 are combined with the IFFT unit 21a-k, the signal synthesis unit 23-k, and the interpolation unit 60. -K and frequency converter 61-k perform the same processing. At that time, the frequency converter 61-106 converts the frequency of the input signal to CH # 8, which is a backup frequency. Then, the standby system synthesis unit 62-1 performs synthesis processing of the signal frequency-converted by the frequency conversion unit 61-1 and the signal frequency-converted by the frequency conversion unit 61-106.

  Similarly, when assigning a spare frequency to a beam other than the beam # 1, the spare system 63 reads a signal from the third RAM unit 17-k corresponding to the beam, converts the frequency to CH # 8, The standby system combining unit 62-k corresponding to the beam may perform combining processing of the signal frequency-converted by the frequency converting unit 61-k and the signal frequency-converted by the frequency converting unit 61-106. Note that the standby system synthesis unit 62-k corresponding to the beam that does not use the backup frequency outputs the input signal as it is to the interpolation unit 24-k. In this way, by utilizing the spare frequency, it is possible to increase the frequency band allocated to 60/8 MHz, which is doubled, for each beam that has been allocated 30/8 MHz.

  Further, the provision of a plurality of spare systems 63 shown in FIG. 15 instead of one makes it possible to use the frequency more flexibly although the circuit scale of the hardware slightly increases. FIG. 17 is a diagram illustrating the concept of frequency use when three spare systems are provided. FIG. 17 assumes a case where communication is concentrated on the communication destination cell of CH # 1 (beam # 1). In the figure, spare # 1 to spare # 3 generate transmission signals using unused bands of CH # 2 (beam # 2) and CH # 7 (beam # 7) and CH # 8. . And the backup system | synthesizer 62-1 corresponding to CH # 1 performs the transmission signal of backup # 1 to backup # 3 produced | generated in this way, and the signal frequency-converted by the frequency converter 61-1. Perform synthesis processing. The control unit 64 performs detection of unused bands among the allocated bands of the respective beams.

  In actual processing, since signals are combined after IFFT processing, signals are combined in the time domain, but in FIG. 17, each signal is expressed in the frequency domain for convenience. In addition, FIG. 17 shows an example in which communication is concentrated on the beam # 1, but by combining signals from a plurality of standby systems, the same processing as described above can be performed regardless of which beam has communication concentration. Even when communication concentration occurs in a plurality of beams, flexible frequency utilization such as using spare # 1 and spare # 2 with different beams can be realized. When two or more standby systems 63 are provided, the number of third RAM units connected to one second RAM unit of the switch matrix unit 10 is increased accordingly.

As described above, when the communication is concentrated in a certain cell, the use of the standby system 63 enables flexible frequency utilization. Note that FIG. 16 shows an example in which 30 MHz is divided into eight equal parts, but the number of divisions may be any number as long as it is an integer of 7 or more which is the cell frequency repetition number. In this embodiment, 7-cell frequency repetition is assumed. However, for example, in a 3-cell repetition system, 30 MHz may be divided into four. Alternatively, the frequency band allocated to the standby system 63 may be smaller than 30/8 MHz, and the number of IFFT points performed by the standby system 63 may be smaller than 2 ^N / 8 points. In this case, according to the change in the number of IFFT points, the amount of up-sampling in the interpolation unit 60-106 is changed with respect to the signal after IFFT processing.

  Note that the 30 MHz frequency band division used by the user link and the standby system band are not equally divided as shown in FIG. 16. For example, the control unit 11 or the control unit 64 estimates the traffic in each cell. Alternatively, adaptive division may be performed by reflecting the estimation result. In this case, it is not necessary to assign a band as a backup frequency.

FIG. 18 is a diagram illustrating another configuration example of the interpolation unit and the frequency conversion unit. In the configuration shown in FIG. 15, the interpolation unit 60-k interpolates the signal so that the data point is multiplied by 2 ^M (M = natural number), and the frequency conversion unit 61-k performs frequency conversion of the interpolated signal. However, instead of the interpolation unit 60-k and the frequency conversion unit 61-k, a set of a double interpolation unit 70-1 and a frequency conversion unit 71-1 as shown in FIG. A simple configuration may be used. In the case of the configuration example of FIG. 18, it is known that the double interpolation units 70-1 to 70-M can be realized with a small circuit scale. By adopting the configuration shown in FIG. 18, the configuration shown in FIG. The circuit scale can be reduced.

Next, a technique for reducing the circuit scale of the FFT unit when processing when the satellite station receives a signal from the ground terminal will be described. The FFT unit 37-k (k = 1, 2,..., 105) shown in FIG. 11 of the first embodiment performs 2 ^N point FFT processing. In the present embodiment, in order to reduce the number of FFT points of the FFT unit 37-k from 2 ^N points to 2 ^(N-3) points, the frequency band used by the ground terminal in advance is set in the area where the ground terminal is located. Accordingly, it is assumed that 30 MHz as shown in FIG. 16 is assigned to the frequency band (CH # 1 to CH # 8) divided into eight. In this way, by determining the frequency band (bandwidth: 30/8 MHz) used by the ground terminal in advance, the FFT unit performs FFT processing on the 30/8 MHz frequency band in which the received signal exists instead of 30 MHz. Therefore, the number of FFT points is also changed from 2 ^N points to 2 ^N / 8 points, and the circuit scale of the FFT unit can be reduced to 1/8 or less compared to the first embodiment.

  FIG. 19 is a diagram illustrating an example of a component that performs signal reception processing from the ground terminal of the satellite station according to the present embodiment. As shown in FIG. 19, in the satellite station of the present embodiment, the components that receive signals from the ground terminal are the frequency conversion units 80-1 to 80-1 in addition to the components shown in FIG. 11 of the first embodiment. 80-105, thinning-out parts 81-1 to 81-105, and spare system 82 are added, and FFT units 37a-1 to 37a-105 are provided instead of FFT units 37-1 to 37-105. The same as in the first embodiment. In addition, the constituent elements that perform processing after the switch matrix unit 38 are the same as those in FIG. 12 described in the first embodiment.

  Since the process from the reception antenna 30-k receiving the signal transmitted from the ground terminal to the thinning-out unit 35-k is the same as that of the first embodiment, the description thereof is omitted. In the present embodiment, it is assumed that the signal transmitted from the ground terminal uses a band within 30/8 MHz allocated to each cell (each beam) in advance as described above. The frequency converting unit 80-k performs frequency conversion such that the center frequency of the allocated band is converted to 0 MHz with respect to the reception signal (thinned signal) output from the thinning unit 35-k. The thinning unit 81-k performs 1/8 thinning processing on the received signal.

  FIG. 20 is a diagram illustrating a concept of signal processing of processing of the frequency conversion unit 80-3 and the thinning-out unit 81-3 according to the present embodiment. The upper part (a) of FIG. 20 shows an example of a signal output from the thinning unit 35-3. Here, the beam # 3 corresponding to the thinning unit 35-3 has CH # 3 as a frequency band. Assume that it is assigned. The middle part (b) of FIG. 20 illustrates an example of the frequency after the frequency conversion unit 80-3 performs frequency conversion on the signal of the CH # 3 frequency output from the thinning-out unit 35-3. In this way, the signal in the frequency band of CH # 3 is converted to a frequency centered at 0. The lower part (c) of FIG. 20 shows an example of a result of the thinning unit 81-3 performing the thinning process on the signal frequency-converted by the frequency conversion unit 80-3.

The windowing unit 36-k multiplies the received signal thinned by 1/8 by the window function in the same manner as in the first embodiment, and the FFT 37a-k calculates 2 for the received signal multiplied by the window function. ^N / 8 point FFT processing is performed. In, 2 ^N point had been FFT processing, as described above, the circuit scale of the FFT unit 37a-k compared to the first embodiment, the frequency band used by the pre-ground terminal ground terminal located By defining the area, it is possible to reduce the frequency to 1/8 or less as compared with the FFT unit 37-k in the first embodiment that performs 2 ^N point FFT processing.

  Further, in order to provide flexibility in frequency use, the present embodiment includes a standby system 82 that is not connected to the receiving antenna units 30-1 to 30-105. The standby system 82 includes a frequency converter 80-106, a thinning unit 81-k, a thinning unit 81-k, a windowing unit 36-k, and an FFT unit 37a-k. A windowing unit 36-106 and an FFT unit 37a-106 are included.

  For example, as shown in FIG. 16, when the frequency band is divided and assigned to each cell, communication concentrates on beam # 3 using CH # 3, and a band of 30/8 MHz or higher is necessary. And At this time, in addition to CH # 3, CH # 8, which is a spare frequency, is assigned as a frequency band used by beam # 3. Whether or not to perform this allocation is determined by the control unit 63, and the cell corresponding to the beam # 3 is notified that the backup frequency is used. The receiving antenna 30-3 corresponding to the beam # 3 receives a 60/8 MHz signal. After the signal received by the receiving antenna 30-3 is processed up to the thinning-out unit 35-3 in the same manner as described above, the thinning-out unit 35-3 sends the thinned-out signal to the subsequent stage based on the instruction of the control unit 64. To the frequency converter 80-3 and the frequency converter 80-106 of the standby system 82.

  The control unit 64 manages frequency allocation information (which frequency band is allocated to which cell) and, when using the spare frequency, the thinning unit corresponding to the beam to which the spare frequency is assigned. In this case, it is instructed to output the thinned signal to the frequency converters 80 to 106 of the standby system 82.

  Thereafter, the frequency converter 80-3 converts the CH3 signal to the center frequency 0 MHz, and the standby system frequency converter 80-106 converts the CH8 signal to the center frequency 0 MHz. The thinning unit 81-3 and the spare system thinning unit 81-106 perform 1/8 thinning processing on each signal.

  FIG. 21 is a diagram illustrating the concept of the processing of the frequency conversion units 80-3 to FFT unit 37a-3 and the processing of the standby system 82 according to the present embodiment. FIG. 21 (a) shows an example of a thinned signal output from the thinning unit 35-3, and there is a signal in CH # 3 and CH # 8 to which a frequency is assigned to beam # 3. ing. The horizontal axis in FIG. 21 indicates the frequency. 21B shows a signal after the frequency conversion unit 80-3 performs frequency conversion on the signal of CH # 3, and FIG. 21C shows the frequency conversion unit 80- of the standby system 82. 106 shows a signal after frequency conversion is performed on the signal of CH # 8. Further, (d) and (e) of FIG. 21 show the results of the thinning processing performed by the thinning unit 81-3 and the thinning unit 81-106, respectively.

  Note that a plurality of standby systems 82 may be provided, and the processing bandwidth of the standby system 82 may be larger or smaller than 30/8 MHz. In FIG. 21, the case where communication is concentrated on beam # 3 is described as an example. However, when communication is concentrated on any beam from beam # 1 to beam # 105, communication is concentrated on a plurality of beams. In this case, flexible frequency utilization can be realized by utilizing a plurality of standby systems.

  In preparation for input from the standby system 82, the fourth RAM section of the switch matrix 38 is configured by 105 + the number of the standby systems 82. Accordingly, the number of signal lines input to the signal sorting unit connected to the fourth RAM unit to which signals from the standby system 82 are input and the number of signal lines output from the signal sorting unit also increase. The operations of the present embodiment other than those described above are the same as those of the first embodiment.

As described above, in the present embodiment, the frequency band is divided by the number of cells in the cluster + 1, the divided frequency band is assigned to each cell, and the IFFT unit 21a-k and the FFT unit 37a-k are 2 ^N / 8. The FFT processing of points was performed. Therefore, the same effects as those of the first embodiment can be obtained, and the circuit scale compared to the first embodiment can be reduced to 1/8 or less. Although the number of circuits for configuring the standby system 63 and the standby system 82 increases, it is relatively small compared to the reduction amount that can be achieved in the IFFT unit 21a-k and the FFT unit 37a-k. Even if the minutes are taken into consideration, the total can be reduced to about 1/7 or less.

  In this embodiment, the case of 7-cell frequency repetition is taken as an example. However, in the case of K-cell frequency repetition, the circuit scale is 1 / K compared to the first embodiment.

Embodiment 3 FIG.
FIG. 22 is a diagram illustrating a functional configuration example of the third embodiment of the satellite station according to the present invention. FIG. 22 shows the components up to the switch matrix 10 among the components that implement the process of transmitting the signal received from the ground station to the ground terminal. Components having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted. As shown in FIG. 22, the satellite station of the present embodiment deletes the windowing units 7-1 to 7-15 from the configuration shown in FIG. Except for the addition of extraction units 91-1 to 91-15, the configuration is the same as that of FIG.

  In the present embodiment, the FFT unit 9-i (i = 1, 2,..., 15) and the IFFT unit 21-k (i = 1, 2,..., 105) of the first embodiment, or the second embodiment. The calculation amount of the FFT unit 9-i and the IFFT unit 21a-k is reduced. In the following description, a case where the calculation amount is reduced with respect to the first embodiment will be described as an example, but the calculation amount can be similarly reduced in the second embodiment.

  In the FFT calculation, as described in the first embodiment, there is no continuity of the signal at both ends of the FFT calculation section (the values at both ends are different), so that harmonics are generated and an unnecessary spectrum is generated, leading to characteristic deterioration. . Therefore, in the first embodiment, the window function is multiplied to prevent this deterioration, but there is a possibility that the signal is lost due to the window function multiplication. Therefore, in the first embodiment, two series of signals having different window function multiplication ranges are obtained in parallel, and both are subjected to FFT / IFFT processing, and then synthesized by the signal synthesis unit 23-k, so that The method of ensuring continuity was taken. Therefore, two FFT units 9-i, components of the switch matrix unit 10, and IFFT units 21-k shown in FIG. 1 according to the first embodiment are required to correspond to each system, and the circuit scale is large. There is a problem of becoming. The same applies to the second embodiment.

  In the first embodiment, the signal transmitted from the ground station to the satellite station is assumed to be a burst transmission signal. However, in this embodiment, when the transmission signal is framed and the FFT processing is performed in the satellite station, the FFT calculation section A frame signal configured to have 0 at both ends is transmitted from the ground station. By adopting such a frame configuration, both ends of the data are almost “0” and have the same numerical value, so that continuity can be ensured and there is no need to perform window function multiplication. Therefore, the FFT unit 9-i and the switch matrix unit 10 need only process one system of signals.

  FIG. 23 is a diagram illustrating an example of a frame configuration of a transmission signal according to the present embodiment. In the present embodiment, as shown in FIG. 23, the transmission signal is framed, and a section without a transmission signal (a section having a value of 0) is provided in portions corresponding to both ends of the FFT calculation section, thereby Ensure continuity. However, in this case, when the FFT calculation process is performed on the signal from the ground station received by the satellite station, the FFT calculation process is performed in the intended correct section so that there is always no signal at both ends of the FFT calculation section. There is a need. Therefore, the satellite station needs to determine the FFT calculation timing based on the received signal.

  Therefore, in the present embodiment, as illustrated in FIG. 22, the conversion is performed with the power conversion unit 90-i that performs power conversion on the received signal (thinning signal) that the thinning unit 6-i performs the thinning process. A timing extraction unit 91-i that detects a no-signal section based on the received power and outputs the FFT calculation timing to the FFT calculation unit 9-i. Since the process from the reception antenna 1 receiving the signal transmitted from the ground station to the thinning-out unit 6-i is the same as that in the first embodiment, the description thereof is omitted.

  The power conversion unit 90-i performs power conversion of the reception signal subjected to the thinning process by the thinning unit 6. The timing extraction unit 91-i detects a no-signal section based on the power information, and transmits an FFT calculation start position (FFT start timing) that is a predetermined position in the no-signal section to the FFT calculation unit 9. It is assumed that which position in the no-signal section is the FFT calculation start position (for example, the center position of the no-signal section) is determined in advance. The FFT calculator 9-i performs an FFT process based on the FFT calculation start position input from the timing extractor 91-i.

  FIG. 24 is a diagram showing the concept of the FFT calculation start position detection process of the present embodiment. (A) of FIG. 24 has shown the image of the received signal output from the thinning-out part 6-i. Since the received signal is framed, as shown in FIG. 24A, there is a non-signal portion (blank portion) between Data as transmission data. FIG. 24B shows an image of power after the power conversion unit 90-i performs power conversion on the reception signal output from the thinning-out unit 6-i shown in FIG. The timing extraction unit 91-i detects a section where the power value is low, that is, a section where no signal exists, based on the power shown in FIG. 24B, and an FFT calculation start position which is a predetermined position in the section. To extract. The FFT calculation start position extracted by the timing extraction unit 91-i is output to the FFT unit 9-i, and the FFT unit 9-i is input from the timing extraction unit 91-i as shown in FIG. The FFT processing is executed using the FFT calculation start position as the FFT calculation start position.

  By performing the FFT operation as described above, the FFT unit 9-i, the IFFT unit 21-k, and the switch matrix unit 10 do not need to correspond to two systems of signals with different window function multiplication positions. It is only necessary to process the signal. Therefore, in the present embodiment, one component is provided for each of the FFT unit 9-i, the IFFT unit 21-k, and the switch matrix unit 10 according to the first embodiment so as to correspond to the two systems. It will be good. The present embodiment is the same as the first embodiment except that the FFT unit 9-i, IFFT unit 21-k, switch matrix unit 10 and window function of the present embodiment are combined into one system. Further, in the present embodiment, the signal synthesis unit 23-k after the IFFT unit 21-k is not necessary, and the signal after processing by the IFFT unit 21-k is output to the interpolation unit 24-k. The components and processing after the interpolation unit 24-k are the same as those in the first embodiment.

  Note that the timing extraction unit 91-i uses the result of averaging the power of the received signal a plurality of times in the frame period using the signals of a plurality of frames when extracting the FFT calculation start position, and there is no signal. A section (= a section with a small power value) may be obtained. At that time, an average value calculation method that weights the value used for calculating the average value may be used.

  In this embodiment, the FFT calculation start position is obtained using the power of the received signal. However, the present invention is not limited to this, and the fixed signal is reproduced at the satellite station and inserted at the head of the signal frame. A signal may be detected, and the timing of the FFT calculation start position may be obtained based on the position of the fixed pattern.

  Also, instead of extracting the FFT calculation start position based on the received signal, the FFT calculation start position is obtained by synchronizing the ground station and the satellite station using GPS (Global Positioning System) or the like and transmitting / receiving the signal. May be determined. In this case, since the satellite station is synchronized with the ground station, it is possible to grasp the timing of receiving the signal transmitted from the ground, and the ground station is located at the place where the FFT calculation start position is intended for the satellite station. Can be set.

  In addition, communication is performed between the ground station and the satellite station using a line different from the feeder link, and the satellite station determines an FFT calculation start position by referring to a command signal transmitted from the ground station through the communication. May be.

  The ground terminal detects the received power and the fixed pattern inserted at the head of the signal frame based on the signal received from the satellite station, thereby extracting the FFT calculation start position and demodulating the signal.

  When the satellite station receives a signal from each ground station terminal, the FFT calculation position at the time of the FFT processing performed by the satellite station is fixed, and the timing at which the ground station terminal transmits the signal is controlled. It is possible to perform the FFT operation at the position.

  As an example, there is a method in which the ground terminal transmits a signal from the ground terminal to the satellite station at a timing determined based on the delay time when the signal is transmitted from the satellite station to the ground terminal.

  FIG. 25 is a diagram illustrating an example of a delay time calculation method according to the present embodiment. FIG. 25A shows an example of a signal received by a satellite station from a ground station. As described above, the timing extraction unit 91-i extracts the FFT calculation start position. FIG. 25B is a diagram illustrating an example of a pulse signal when the FFT calculation start position is generated as a pulse. The FFT unit 9-i executes the FFT calculation with the position where the pulse shown in FIG.

  FIG. 25C shows an example of a pulse signal corresponding to a time point when a signal is transmitted from the satellite station to the ground terminal when the pulse signal shown in FIG. 25B is used as a reference. is there. In the satellite station, transmission is delayed by a delay time D1 from (b) of FIG. 25 due to a processing time (processing delay) for generation as a transmission signal to the ground terminal after the calculation by the FFT unit 9-i. Is done. Since the delay time D1 is a fixed delay, it can be grasped in advance.

  FIG. 25 (d) shows an example of a pulse signal corresponding to the time when the ground terminal receives a signal from the satellite station and performs demodulation processing when the pulse position of FIG. 25 (c) is used as a reference. Is. (D) of FIG. 25 is compared with the pulse position of FIG. 25 (c), the propagation delay time D2 due to the propagation delay from the satellite station to the ground terminal, the demodulation delay time D3 related to the demodulation processing at the ground terminal, Delayed by the amount of time added. Although the propagation delay time D2 varies depending on the position of the ground terminal, it is possible to grasp the distance from the satellite station by acquiring the position information of the ground terminal, and the ground terminal grasps the distance from the satellite station. Thus, the propagation delay time D2 can also be grasped. Also, the demodulation delay time D3 of the ground terminal can be grasped in advance because it is fixed.

  From the above, the delay time (delay time from the satellite station to the ground terminal) until the ground terminal demodulates the signal transmitted from the satellite station after the FFT section 9-i of the satellite station performs the FFT operation is D1 + D2 + D3. These delay times can be calculated. Similarly, it is possible to calculate a delay time (delay time from the ground terminal to the satellite station) from when the ground terminal transmits a signal until the satellite station performs the FFT operation on the signal. The ground terminal calculates the delay time from the satellite station to the ground terminal and the delay time from the ground terminal to the satellite station. Based on the calculated delay time, the ground terminal performs the FFT operation at the correct position. Controls the transmission timing of the transmission signal. With the transmission control at the ground terminal, the satellite station can perform the FFT operation at a desired timing by performing the FFT operation processing at a fixed timing.

  By performing such processing, the FFT unit 37-k, the switch matrix unit 38, and the switch matrix unit 38 are also used when processing the signal transmitted from the ground terminal, as in the case of processing the signal transmitted from the ground station. Each of the IFFT units 41-i can be configured with only one system, and the signal synthesis unit 42-i can be dispensed with. In addition, instead of the ground station terminal performing the transmission control as described above, the calculation start position can be detected by framing the signal transmitted from the ground station and providing a no-signal section. Good.

  In general, beacon information is transmitted from the satellite station, but the ground terminal transmits a signal to the satellite station based on the beacon information, so that the reception timing of the signal transmitted from the ground terminal by the satellite station is as follows. You may grasp. That is, the ground terminal controls the timing of the transmission signal based on the beacon information. Alternatively, the satellite station may grasp the reception timing of the signal transmitted from the ground terminal by synchronizing the satellite station and the ground terminal using GPS.

  Also, for a signal transmitted from the satellite station to the ground station, the ground station can detect the FFT calculation start position based on the delay time in the same manner as the ground terminal. Therefore, for the signal transmitted from the ground station, the satellite station may fix the FFT calculation start position, and the ground station may control the transmission based on the delay time. Similarly to the uplink from the ground station to the satellite station, the ground station obtains information on the FFT calculation start position from the satellite station using a line different from the feeder link, and extracts the FFT calculation start position based on the information. You may do it.

  As described above, in the present embodiment, the transmission signal is framed and a no-signal section is provided between transmission data so that the continuity of the FFT calculation section is maintained, and the power conversion unit 90-i of the satellite station is maintained. Power-converts the received signal, extracts the FFT calculation start position based on the power converted by the timing extraction unit 91-i, and performs the FFT calculation based on the FFT calculation start position extracted by the FFT unit 9-i. I made it. Therefore, the satellite station winding unit 7-i and the signal synthesis unit 23-i can be omitted, and the FFT unit 9-i, the switch matrix unit 10, and the IFFT unit 21-k, which are conventionally required two by two, are also provided. You only have to prepare one by one. Therefore, in this embodiment, it is possible to reduce the circuit scale to ½ or less of the conventional one. In the second embodiment as well, the circuit scale can be reduced by performing the same configuration change as the present embodiment and performing the same operation as the present embodiment.

  In the present embodiment, an example in which the transmission signal is framed has been described. However, in the same manner as in the first embodiment, the windowing unit 7-i performs the window function multiplication process in the satellite station without performing the frame formation. May be performed. However, a signal with a shifted window function multiplication range is not generated. In this case, the received signal multiplied by the window function lacks the signal information of the window function multiplication part, but the error rate required for the system was satisfied by compensating for the lost signal using error correction processing. Communication can be performed.

  As described above, the satellite communication device and the satellite communication system according to the present invention are useful for a communication system that extracts each carrier signal from a multiplexed signal obtained by combining a plurality of carrier signals and multiplexes and transmits the plurality of carrier signals. In particular, it is suitable for a communication system that requires flexible frequency utilization.

1,30-1 to 30-105 reception antennas 2-1 to 2-15, 31-1 to 31-105, 27-1 to 27-105, 46-1 to 46-15, 61-1 to 61-106 , 80-1 to 80-106 Frequency conversion unit 3-1 to 15-15, 32-1 to 32-15 A / D conversion unit 4-1 to 4-15, 33-1 to 33-15 Quadrature detection unit 5 -1 to 5-15, 34-1 to 34-105 LPF part 6-1 to 6-15, 35-1 to 35-105, 81-1 to 81-106 thinning part 7-1 to 7-15, 36 -1 to 36-106 Windowing section 9-1 to 9-15, 37-1 to 37-105, 37a-1 to 37a-106 FFT section 10,38 Switch matrix section 11, 64 Control section 14-1 to 14 -15 1st RAM section 15-1 to 15-15, 51-1 to 51 -15, 53-1 to 53-15 Signal sort unit 16-1 to 16-15 Second RAM unit 17-1 to 17-105 Third RAM unit 21-1 to 21-105, 41-1 to 41-15, 21a -1 to 21a-106 IFFT section 23-1 to 23-106, 42-1 to 42-15 Signal synthesis section 24-1 to 24-105, 43-1 to 43-15, 60-1 to 60-106 Interpolation Unit 25-1 to 25-105, 44-1 to 44-15 quadrature modulation unit 26-1 to 26-105, 45-1 to 45-15 D / A conversion unit 28-1 to 28-105 transmitting antenna 47 addition Sections 50-1 to 50-105 Fourth RAM section 52-1 to 52-15 Fifth RAM section 54-1 to 54-15 Sixth RAM section 62-1 to 62-105 Standby system composition section 63, 82 Standby system 90-1 ~ 90-15 Electric power Conversion unit 91-1 to 91-15 Timing extraction unit

Claims (23)

The received signal is demultiplexed, the demultiplexed signal that is the demultiplexed signal is distributed for each destination, and the demultiplexed signal after distribution is multiplexed for each destination of the demultiplexed signal. A satellite communication device that transmits a combined signal,
FFT processing means for converting a received signal into a frequency domain signal by FFT processing, and using the frequency domain signal as the demultiplexed signal;
Switch matrix means for distributing the demultiplexed signal for each destination;
IFFT processing means for converting the demultiplexed signal after the distribution by the switch matrix means to a time domain signal by performing IFFT processing for each same destination, and using the time domain signal as the combined signal;
A satellite communication device comprising: The FFT process is a 2 ^N (N is a natural number) point FFT process.
The satellite communication device according to claim 1. The IFFT processing is 2 ^N (N is a natural number) points IFFT processing,
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. The destination has two or more layers,
The switch matrix means distributes the demultiplexed signal for each layer,
The satellite communication apparatus according to claim 1, 2, or 3. Transmit antenna means for generating a plurality of transmit beams;
Further comprising
The destination is a cell formed by the transmission beam.
The satellite communication apparatus according to claim 1, 2, or 3. Transmit antenna means for generating a plurality of transmit beams;
Further comprising
The destination is a cell formed by the transmission beam,
A cluster is composed of a predetermined number of the cells, and the same frequency band is used between the clusters.
The hierarchy is the two hierarchy of the cluster and the cell,
The switch matrix means performs distribution for each cell in the cluster after performing distribution for each cluster as distribution for each hierarchy.
The satellite communication device according to claim 4. The frequency band assigned to the cluster is divided into C frequency bands larger than the predetermined number, and the divided frequency band, which is the divided frequency band, is pre-assigned to the cell on a one-to-one basis, and the divided frequency band Of these, a frequency band not assigned to the cell is determined as a spare frequency band,
The IFFT processing means performs the IFFT processing with the number of IFFT points corresponding to the divided frequency bandwidth allocated to the corresponding destination,
When determining whether to allocate the backup frequency band to one or more cells of the cell, and assigning the backup frequency band to one or more cells of the cell, the backup frequency Control means for classifying the received signal to be transmitted to the cell to be assigned a band into the received signal to be transmitted in the spare frequency band and the received signal to be transmitted in the divided frequency band previously assigned to the cell;
Interpolation means for performing interpolation so that the combined signal has a C-fold score;
A frequency conversion means for converting the combined signal after interpolation by the interpolation means into a divided frequency band assigned to a destination cell of the combined signal;
Based on the classification result of the control means, IFFT processing is performed on the received signal transmitted in the backup frequency band with the number of IFFT points corresponding to the backup frequency band, and the signal after IFFT processing is interpolated C times. Also, standby system processing means for generating a backup system signal by converting the interpolated signal into a backup system frequency, and
Based on the determination result of the control means, the spare system signal and the signal converted into the divided frequency band by the frequency conversion means corresponding to the cell to which the spare frequency band is allocated are synthesized, and after the synthesis Standby system combining means for combining the signal of
Further comprising
The satellite communication device according to claim 6. Receiving antenna means for generating a receiving beam and receiving a signal transmitted from a ground terminal;
Further comprising
A cluster is composed of a predetermined number of cells, the same frequency band is used between the clusters, and the frequency band allocated to the cluster is divided into C frequency bands larger than the predetermined number, A division frequency band that is the divided frequency band is assigned to the cell in a one-to-one correspondence, a frequency band that is not assigned to the cell among the division frequency bands is determined as a spare frequency band, and the reception The signal is a signal received by the receiving antenna means,
When determining whether to allocate the backup frequency band to one or more cells of the cell, and assigning the backup frequency band to one or more cells of the cell, the backup frequency A control means for notifying the cell to which the band is assigned;
Ground terminal frequency converting means for converting the received signal transmitted in the divided frequency band into a frequency band centered on 0;
Thinning means for thinning received signals after frequency conversion by the ground terminal frequency converting means to 1 / C;
The input signal is frequency-converted so that the center frequency of the spare frequency band is 0, the frequency-converted signal is thinned out to 1 / C, and the FFT processing is performed on the thinned-out signal. A ground terminal standby system processing means that uses the processed signal as a reception standby system signal;
Further comprising
The control means outputs the received signal received from the cell assigned the backup frequency band to the ground terminal frequency conversion means and inputs to the ground terminal backup system processing means,
The FFT means uses the signal after thinning by the thinning means as the reception signal to be subjected to the FFT processing.
The satellite communication apparatus according to claim 1, 2, or 3. The transmission destination of the combined signal is a ground station,
Ground station frequency conversion means for generating a divided transmission frequency band signal obtained by converting the combined signal into the divided transmission frequency band for each divided transmission frequency band obtained by dividing the transmission frequency band transmitted to the ground station into a predetermined number; ,
Adding means for adding the divided transmission frequency band signals generated for each of the divided transmission frequency bands;
Further comprising
The destination is the ground station frequency conversion means,
The satellite communication apparatus according to claim 1, 2, or 3. The transmission destination of the combined signal is a ground station,
Ground station frequency conversion means for generating a divided transmission frequency band signal obtained by converting the combined signal into the divided transmission frequency band for each divided transmission frequency band obtained by dividing the transmission frequency band transmitted to the ground station into a predetermined number; ,
Adding means for adding the divided transmission frequency band signals generated for each of the divided transmission frequency bands;
Further comprising
The destination is the ground station frequency conversion means,
The satellite communication device according to claim 8. The received signals are M (M is a natural number),
Let the number of destinations be L,
The FFT processing means performs the FFT processing on each of the M received signals,
The switch matrix targets the demultiplexed signals corresponding to the M received signals as distribution targets for each destination,
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. M and L are 2 or more,
The switch matrix means includes
A first storage that holds the reception signal and outputs the reception signal to an output destination corresponding to the destination based on a correspondence between a predetermined destination and an output destination and a destination of the reception signal that is held M means,
Second storage means for storing the received signal composed of L memories;
A signal sorting unit that is connected to the second storage unit in a one-to-one relationship, and that rearranges the signals output from the first storage unit;
With L,
The output destination is the signal sorting means,
The signal sorting means equalizes the output frequency of the signals input from the M first storage means to the L memories constituting the second storage means to which the signal sorting means is connected. Rearrange and output to the L memories
The satellite communication device according to claim 11. Window function multiplication means for generating two types of window function multiplication signals by multiplying the reception signal and two types of window functions whose multiplication intervals for the reception signal are different from each other by a predetermined time;
Signal combining means for combining two input signals;
Further comprising
The FFT processing means performs the FFT processing using two types of window function multiplication signals as reception signals to be processed,
The switch matrix means sets the demultiplexed signals respectively corresponding to the two types of window function multiplication signals as distribution targets for each destination,
The IFFT processing means sets the signal after the distribution to the two types of window function multiplication signals as the target of the IFFT processing,
The signal combining means uses the two signals as the combined signals obtained by the IFFT means corresponding to two types of window function multiplication signals.
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. Window function multiplication means for generating two types of window function multiplication signals by multiplying the reception signal and two types of window functions whose multiplication intervals for the reception signal are different from each other by a predetermined time;
Signal combining means for combining two input signals;
Further comprising
The FFT processing means performs the FFT processing using two types of window function multiplication signals as reception signals to be processed,
The switch matrix means sets the demultiplexed signals respectively corresponding to the two types of window function multiplication signals as distribution targets for each destination,
The IFFT processing means sets the signal after the distribution to the two types of window function multiplication signals as the target of the IFFT processing,
The signal synthesis means uses the two signals as the combined signal obtained by the IFFT means corresponding to the two types of window function multiplication signals.
The interpolating means sets the signal after the signal synthesizing means to synthesize the combined signal to be interpolated,
The satellite communication device according to claim 7. A window function for generating two types of window function multiplication signals by multiplying the signal after thinning by the thinning means and two types of window functions whose multiplication intervals for the signal after thinning differ by a predetermined time. Multiplication means;
Signal combining means for combining two input signals;
Further comprising
The FFT processing means obtains the demultiplexed signal by using two types of window function multiplication signals as reception signals to be processed, and receiving signals to be subjected to the FFT processing,
The switch matrix means sets the demultiplexed signals respectively corresponding to the two types of window function multiplication signals as distribution targets for each destination,
The IFFT processing means sets the signal after the distribution to the two types of window function multiplication signals as the target of the IFFT processing,
The signal synthesis means uses the two signals as the combined signal obtained by the IFFT means corresponding to the two types of window function multiplication signals.
The satellite communication device according to claim 8 or 10, characterized in that The predetermined time is a time corresponding to a half of the FFT calculation interval in the FFT processing.
The satellite communication device according to claim 13, 14 or 15. The received signals are M (M is a natural number),
Let the number of destinations be L,
The window function multiplication means generates the two types of window function multiplication signals for each of the M reception signals,
The FFT processing means performs the FFT processing on M sets of the two types of window function multiplication signals,
In the switch matrix, the demultiplexed signals respectively corresponding to the two types of the window function multiplication signals of M sets are assigned to each destination.
The satellite communication device according to claim 13, wherein the satellite communication device is a satellite communication device. M and L are 2 or more,
The switch matrix means includes
A first storage that holds the reception signal and outputs the reception signal to an output destination corresponding to the destination based on a correspondence between a predetermined destination and an output destination and a destination of the reception signal that is held M means,
Second storage means for storing the received signal composed of L memories;
A signal sorting unit that is connected to the second storage unit in a one-to-one relationship, and that rearranges the signals output from the first storage unit;
With L,
The output destination is the signal sorting means,
The signal sorting means equalizes the output frequency of the signals input from the M first storage means to the L memories constituting the second storage means to which the signal sorting means is connected. Rearrange and output to the L memories
The satellite communication device according to claim 17. The received signal is transmitted with a no-signal interval inserted for each predetermined amount of data,
Power conversion means for calculating a power value of the received signal;
A timing extraction unit that extracts the no-signal section based on the power value, and extracts a predetermined position in the no-signal section as an FFT calculation start position that is a calculation start position of the FFT processing;
Further comprising
The FFT processing means performs the FFT processing based on the FFT calculation start position.
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. Based on information received from GPS satellites, establish synchronization with the device from which the received signal is transmitted,
The FFT processing means obtains the FFT calculation start position based on an FFT calculation start position instruction signal indicating the FFT calculation start position, which is the calculation start position of the FFT process, transmitted from the transmission source device of the received signal. The FFT processing is performed based on the FFT calculation start position.
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. The transmission source device of the received signal obtains the FFT calculation start position, which is the calculation start position of the FFT processing performed by the satellite communication device based on the processing delay and propagation delay with the satellite communication device, and the FFT The received signal is transmitted based on the calculation start position,
The FFT processing means fixes the FFT calculation start position, which is the calculation start position of the FFT process,
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. The transmission source device of the reception signal transmits the reception signal based on beacon information received from the satellite communication device,
The FFT processing means fixes the FFT calculation start position, which is the calculation start position of the FFT process,
The satellite communication device according to claim 1, wherein the satellite communication device is a satellite communication device. With the ground station,
A ground terminal,
A satellite communication device according to any one of claims 1 to 22,
With
The satellite communication device demultiplexes a received signal received from the ground station, distributes a demultiplexed signal that is a signal after demultiplexing to each destination, and combines the divided signal for each destination of the demultiplexed signal Then, a combined signal, which is a signal after multiplexing, is transmitted to the ground terminal, or a received signal received from the ground terminal is demultiplexed, and the demultiplexed signal, which is a signal after demultiplexing, is distributed to each destination. The combined signal is combined for each destination of the demultiplexed signal, and the combined signal that is the combined signal is transmitted to the ground station.
A satellite communication system.

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