JP3894468B2 - Spread spectrum communication method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used as a multiple access method of a direct sequence-spread spectrum (DS-SS) communication method applied to wireless communication.
[0002]
[Prior art]
In the conventional direct spectrum spread communication system, different pseudo-random codes (PN: Pseudo Noise codes) are assigned to each of the simultaneous communication stations occupying the same frequency band, and the correlation between these codes is small. Thus, simultaneous communication is performed by a code division multiple access (CDMA) system that identifies each station and extracts a desired signal.
[0003]
A conceptual diagram of the CDMA system is shown in FIG. FIG. 7 shows a case where the number of simultaneous communication stations is k, 70-1 to 70-k are binary-coded information signals of each communication station, and 71-1 to 71-k are information signals 70-1. ... 70-k are spread spectrum modulators using PN codes 72-1 to 72-k, and 73-1 to 73-k are local oscillators based on baseband signals obtained by the spread modulators 71-1 to 71-k. Modulators that modulate the carrier waves output from 74-1 to 74-k, band-pass filters 75-1 to 75-k for extracting frequency components necessary for transmission from the modulated signal, and 76 from a plurality of simultaneous communication stations. A synthesizer that equivalently indicates that the spread spectrum signal is multiplexed and transmitted in space, 77 is a band-pass filter that extracts only frequency components necessary for demodulation from the received signal, and 78 is a signal output from the local oscillator 79. High frequency signal Frequency converter for converting the baseband signal, 80 is a demodulator for detecting information which each communication station has transmitted the received signal band-limited, 81 denotes respective information signals detected by the demodulator.
[0004]
In the prior art, information signals transmitted simultaneously from the respective communication stations are subjected to direct spread spectrum modulation by different types of pseudo random codes PN1 to PNk represented by 72-1 to 72-k and having a small correlation with each other. Here, the same frequency f1 is used for the oscillation frequencies of the frequency oscillators 74-1 to 74-k. Next, the signal modulated into a high frequency signal by the modulator is band-limited by a band-pass filter of 75-1 to 75-k, and then transmitted toward the reception side. As shown in FIG. Are received in a state where the transmission waves of the communication stations 1 to k overlap the center frequency f1. In the demodulator, only the desired wave is detected from a plurality of spread spectrum signal waves received at the same time by performing correlation detection using the pseudo-random code used when spreading a desired information signal. It becomes possible.
[0005]
In the spread spectrum direct communication system, a maximum period sequence (M sequence) is well known as a pseudo-random code used for spread spectrum modulation. However, in order to obtain a large number of simultaneous communication stations in a CDMA system that identifies a communication station only by a pseudo-random code, it is necessary to use a maximum periodic sequence in which many unique PN sequences having a long code length exist. On the other hand, if a pseudo-random sequence with a long code length is used to increase the number of simultaneous communication stations using the same frequency band, the problem of complicating the code creation process, the correlator structure, and the demodulation process occurs. .
[0006]
Thus, since the same pseudo-random code cannot be used at the same frequency in the prior art, it is necessary to change the frequency used by each communication station as shown in FIG. 9 in order for more communication stations to communicate simultaneously. is there. FIG. 9 shows, as an example, a group of 1 to j stations with f1 as the center frequency, and a group of 1 to k stations with f2 as the center frequency. Here, since the number of simultaneous communication stations is m times, that is, the frequency bandwidth necessary for repeatedly using the same pseudo-random code m times is also m times, a communication system in which the available communication bandwidth is limited. Then, the number of stations that can communicate at the same time is limited. In addition, there is a method of assigning a pseudo-random code at any time in response to a communication request from a communication station, instead of fixedly assigning a pseudo-random code to a communication station. Control for realizing this method Methods and apparatus are extremely complex.
[0007]
As a technique for solving the above problem, a technique of performing multiple access using only one pseudo-random code commonly given to all the simultaneous communication stations (CFO-SSMA method: Carrier Frequency Offset-Spread Spectrum Multiple Access Method) Is disclosed (Japanese Patent Laid-Open No. 5-268189, Kakutani, Shinonaga, “Spread Spectrum Communication System”). In this technique, a plurality of simultaneous communication stations perform spread spectrum modulation on independent information signals using the same pseudo-random code so that carrier frequencies are different from each other as shown in FIG. It is characterized in that communication is performed so that occupied frequency bands overlap each other. At this time, if each communication station uses a carrier frequency that is an integral multiple of the frequency amount defined by the transmission speed as a unit, the receiving side can extract a desired wave with a known carrier frequency using a bandpass filter. Therefore, it is ideally possible to receive and demodulate desired information without being affected by other signal waves. For this reason, the number of stations capable of simultaneous communication within a limited frequency bandwidth can be greatly increased. Further, since each communication station uses the same pseudo-random code, the device scale of the communication device can be reduced.
[0008]
However, in the above spread spectrum communication method, ideally, communication without interference cannot be performed unless the chip timings of spread spectrum signal waves transmitted from a plurality of simultaneous communication stations are completely matched on the receiving side. In other words, if the spread spectrum signal wave from each communication station is not received in a completely synchronized state on the receiving side, the signals from each communication station cause intersymbol interference with each other, greatly degrading the line quality of the transmission path. There is a problem of making it happen. Furthermore, due to the influence of the band limiting filter for waveform shaping mounted on the transmitter, in the case of the CFO-SSMA method,
There is also a problem that line quality deteriorates due to interference from adjacent signal waves.
[0009]
In order to solve the above problems, there is a method in which the carrier frequency interval is set to be an even multiple of the frequency amount defined by the transmission speed, and each communication station performs communication using a spread spectrum signal wave assigned individually. Disclosure (Japanese Patent Laid-Open No. 10-135870, Ishikawa, Shinonaga, Kobayashi, “spread spectrum communication system”). Compared to the case where the carrier frequency interval is set to be an even multiple of the frequency amount specified by the transmission rate as shown in FIG. 11 and the carrier frequency interval is separated by the frequency amount specified by the transmission rate as shown in FIG. The feature is that interference from adjacent signal waves is minimized.
[0010]
[Problems to be solved by the invention]
As described above, the spread spectrum communication method in which multiple access is performed using only one pseudo-random code commonly given to all the simultaneous communication stations can efficiently use a limited frequency band and is limited. Although the number of stations that can communicate simultaneously within the specified frequency bandwidth can be greatly increased, the chip timings of the spread spectrum signal waves from each communication station are received in a state where they are perfectly matched on the receiving side. Otherwise, there is a problem that the spread spectrum modulation signals from the respective communication stations cause intersymbol interference with each other and greatly degrade the channel quality of the transmission path. As a technique for avoiding this problem, there is a method of performing communication by setting the carrier frequency interval to an even multiple of the frequency amount defined by the transmission speed. However, since the carrier frequency interval is an even multiple of the frequency amount defined by the transmission rate, it is not possible to make maximum use of the frequency utilization efficiency that the CFO-SSMA method can take. That is, since the carrier frequency interval is an even multiple of the frequency amount specified by the transmission rate, the number of stations that can simultaneously communicate is compared to when the carrier frequency interval is an integer multiple of the frequency amount specified by the transmission rate. There arises a problem that can be reduced to half.
[0011]
[Means for Solving the Problems]
The present invention Between one communication station and the other multiple simultaneous communication stations, In a spread spectrum communication method in which a plurality of communication stations use the same pseudo-random code, and each communication station performs communication so that spread spectrum signal waves overlap each other using different carrier frequencies, One communication station and the other communication station transmit information using any one of the spread spectrum signal waves, and one communication station communicates with the other plurality of simultaneous communication stations. The frequency amount specified by the transmission speed is the unit. , Have carrier frequencies that are integer multiples of each other All of Of the spread spectrum signal wave, as shown in FIG. 2, the carrier frequency interval is an even multiple of the frequency amount defined by the transmission speed. Multiple and all The spread spectrum signal wave is one of horizontal polarization, vertical polarization, right-handed polarization, and left-handed polarization. First Polarization At the same time, Other than the above Multiple and all Spread spectrum signal wave First Orthogonal to polarization Second Transmit using polarization. A plurality of simultaneous communication stations perform information transmission using any one of these spread spectrum signal waves, thereby causing a problem when the carrier frequency interval is set to an integral multiple of the frequency amount defined by the transmission speed. It has a configuration capable of providing a spread spectrum communication system that can avoid quality degradation and can transmit information to a larger number of simultaneous communication stations than in the conventional system.
[0012]
Furthermore, in the spread spectrum communication method according to the present invention, as shown in FIG. Duplicate By selecting a number of spread spectrum signal waves without overlapping each other and performing information transmission using the plurality of selected spread spectrum signal waves, the transmission speed per communication station is increased. Yes.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the spread spectrum communication method of the present invention will be described below.
[0014]
FIG. 1 shows a case where the number of simultaneous communication stations is 2n. In the figure, 1-1 to 1-2n are binary-encoded information signals of communication stations, and 2-1 to 2-2n are spectrum spreads of 2-1 to 2-2n PN codes. Spread modulators 4-1 to 4-2 n are modulators that modulate the baseband signals obtained by the spread modulators 2-1 to 2-2 n according to the carrier frequencies f 1 to f 2 n of each communication station, Reference numerals 1 to 5-2n denote local oscillators that generate carrier frequencies of the respective communication stations, and reference numerals 6-1 to 6-2n denote band-pass filters that extract frequency components necessary for transmission from the modulated signals.
[0015]
In the spread spectrum communication method of the present invention, spread spectrum signal waves from a plurality of simultaneous communication stations are transmitted by polarization orthogonal transmission. In FIG. 1, this function is equivalently shown as a synthesizer 7. Further, 8 is a band-pass filter that extracts a frequency component necessary for demodulation from the received signal, 9 is a frequency converter that converts a high-frequency signal into a baseband signal by a signal output from the local oscillator 10, and 11 is a band-limited signal. The demodulator 12 for obtaining information transmitted from the reference numeral 12 represents an information signal obtained by the demodulator 11.
[0016]
Next, the operation of the spread spectrum communication system according to the present invention shown in FIG. 1 will be described below. Note that description will be made on the assumption that each communication station performs transmission at the same transmission rate, the same spreading factor, and the same clock timing.
[0017]
The information 1-1 to 1-2n is spread spectrum modulated by the PN codes 3-1 to 3-2n in the modulators 2-1 to 2-2n, and the local oscillators 5-1 to 5-1n in the modulators 4-1 to 4-2n. It becomes a high frequency signal centered on the carrier frequency f1 to f2n of each communication station given by 5-2n, and further passes through the band pass filters 6-1 to 6-2n. Spread spectrum signal waves from a plurality of simultaneous communication stations are multiplexed and transmitted in space. Although not shown in FIG. 1, a configuration in which the PN code and the local oscillator are interchanged is also conceivable.
[0018]
Next, the received signal passes through the band-pass filter 8 and is frequency-converted by the frequency converter 9 so that the desired signal becomes the input center frequency of the demodulator. The demodulator 11 calculates the correlation between the input received signal and the PN code PN1 used for spreading on the transmission side. An information signal transmitted by the obtained correlation value can be taken out.
[0019]
Here, in the conventional CFO-SSMA system, the carrier frequency interval is set to be an even multiple of the frequency amount defined by the transmission speed. However, in the present invention, as shown in FIG. Spread spectrum signal waves that are separated by the carrier frequency by the amount of frequency specified in (1) are transmitted with polarized waves that are orthogonal to each other, so that it is possible to minimize degradation of channel quality caused by chip timing errors that occur between adjacent signal waves. . In other words, when looking at the same polarization, the carrier frequency interval is set to an even multiple of the frequency amount defined by the transmission rate, and the line quality degradation due to interference between adjacent signal waves can be minimized.
[0020]
FIG. 3 shows a configuration example of a transmitter in which one communication station communicates using a plurality of spread spectrum signal waves in the present invention, and the number of spread spectrum signal waves selected by one communication station is four waves. Shows the case. In the figure, 20 is an information signal transmitted from a communication station, 21 is a serial-parallel converter for sequentially and repeatedly distributing serial information signals to four output terminals, and 22-1 to 22-4 generate PN codes. Spread modulators that perform spectrum spread using the PN code from the transmitter 23, 24-1 to 24-4 represent the baseband signals obtained by the spread modulators 22-1 to 22-4, and carrier frequencies f1 to f1 of the spread spectrum signal waves. Modulators that modulate in accordance with f4, 25-1 to 25-4 are local oscillators that provide carrier frequencies f1 to f4, and 26-1 to 26-4 are band-passes that extract frequency components necessary for transmission from the modulated signal. Filters 27-1 to 27-2 are signal synthesizers that synthesize a plurality of spread spectrum signals having different carrier frequencies, and 28-1 to 28-2 are spread spectrum synthesis signals. Common amplifier for amplifying a transmission power of 29-1～29-2 shows each band limiting filter to reduce communication bandwidth out radiation. Further, reference numerals 30-1 to 30-2 denote antennas corresponding to the polarized waves. That is, the output signals of the band limiting filters 29-1 to 29-2 are emitted from the antennas as signals having orthogonal polarization, that is, vertical polarization and horizontal polarization, or right-handed polarization and left-handed polarization, respectively. From the signal combiners 27-1 to 27-2 to the band limiting filters 29-1 to 29-2, signal processing is performed on signal waves obtained by combining spread spectrum signal waves having the same polarization, and the same clock is used. It is transmitted to another communication station at the timing. Although not shown in the figure, a configuration in which 23 PN code generators and 25-1 to 25-4 local oscillators are interchanged is also conceivable. When one communication station communicates using a single spread spectrum signal wave, the antenna and the transmission system are only one system in FIG. 3, and the serial-parallel converter is not necessary.
[0021]
Next, the operation of the transmitter of the spread spectrum communication system according to the present invention shown in FIG. 3 will be described below. A description will be given on the assumption that a plurality of spread spectrum signal waves used by one communication station are transmitted at the same transmission rate, the same spreading factor, and the same clock timing.
[0022]
The information signal 20 is sequentially distributed to the output port corresponding to each spread spectrum signal wave by the serial-parallel converter 21. Next, the serial-parallel converted information signal is sequentially sent to the modulators 22-1 to 22-4 for each spread spectrum signal wave at the same timing in accordance with the time timing corresponding to the transmission speed. In the modulators 22-1 to 22-4, the information signal which is the output of the serial-parallel converter is subjected to spread spectrum modulation by the PN code output from the PN code generator 23. Next, the spread spectrum signal is converted into a high frequency signal centered on the carrier frequencies f1 to f4 provided by the local oscillators 25-1 to 25-4 for each spread spectrum signal wave in the modulators 24-1 to 24-4. After the conversion, the signals pass through the band pass filters 26-1 to 26-4. Next, in order to perform polarization orthogonal transmission, the spread spectrum signal waves having carrier frequencies separated by an even multiple of the frequency amount defined by the transmission rate are multiplexed as a set on the frequency axis. In FIG. 3, spread spectrum signal waves having carrier frequencies f1 and f3 and f2 and f4 are multiplexed by the signal synthesizers 27-1 to 27-2, respectively. Further, the signal power required for the communication line is amplified by the common amplifiers 28-1 to 28-2, and the unnecessary radiation power is deleted by the band limiting filters 29-1 to 29-2. Finally, the multiplexed spread spectrum signal wave that has passed through the band limiting filter is input to the antenna corresponding to the polarization, and is subjected to polarization orthogonal multiplexing transmission.
[0023]
With the above circuit configuration, even when each communication station uses a plurality of spread spectrum signal waves in which the carrier frequency interval is an integral multiple of the frequency amount defined by the transmission rate, the carrier frequency interval Is an even multiple of the frequency amount defined by the transmission speed, and it is possible to reduce interference due to chip timing offset.
[0024]
FIG. 4 shows a configuration example of a receiver in which one communication station communicates using a plurality of spread spectrum signal waves in the present invention, and the case where four spread spectrum signal waves are selected by one communication station. Is shown. In the figure, reference numerals 40-1 to 40-2 denote antennas according to polarization, 41-1 to 41-2 denote low noise amplifiers for amplifying received high frequency signals, and 42-1 to 42-2 denote reception for noise removal. Filters 43-1 to 43-4 convert the carrier frequency f1 to f4 of each spread spectrum signal wave to the center frequency f0 of the SAW (Surface Acoustic Wave) matched filters 47-1 to 47-4 of the receiver. Frequency converters 44-1 to 44-4 are local oscillators that generate carrier frequencies f1 to f4 of each spread spectrum signal wave, and 45-1 to 45-4 remove noise components that exist outside the frequency spread bandwidth. Band pass filters 46-1 to 46-4 are automatic gain controllers (AGC) for operating the demodulator in a stable state, and 47-1 to 47-4 are spectrums. SAW matched filters that extract only the information signal component from the scattered signal, 48-1 to 48-4 are delay detection circuits for converting the SAW matched filter output signals into baseband signals, and 49-1 to 49-4 are delay detected circuits. Low-pass filters for removing harmonic signal components contained in the output signal and extracting only the information signal component, 50-1 to 50-4 are information at the peak point (determination point) of the delayed detection output signal. A determination unit for determining a signal, 51 is a parallel-serial converter for converting the determined information signal into an original continuous information signal, and 52 is an information signal output from the parallel-serial converter 51, respectively. Yes. A configuration in which a digital matched filter is applied instead of the SAW matched filters 47-1 to 47-4 is also conceivable. Further, when one communication station communicates using a single spread spectrum signal wave, the antenna and the reception system are only one system in FIG. 4, and the serial-parallel converter is not necessary.
[0025]
Next, the operation of the receiver of the spread spectrum communication system according to the present invention shown in FIG. 4 will be described below.
[0026]
The spread spectrum signal transmitted from another communication station is received by the antennas 40-1 to 40-2 corresponding to the polarization, and is demodulated for each polarization. Input to the amplifiers 41-1 to 41-2. The amplified high-frequency signal group passes through reception filters 42-1 to 42-2 for noise removal, and is further distributed by the number of each spread spectrum signal wave. Next, in the frequency converters 43-1 to 43-4, the high-frequency signal output from the reception filter is subjected to SAW by the frequencies f1 to f4 provided by the local oscillators 44-1 to 44-4 corresponding to the spread spectrum signal waves. The frequency is converted to the center frequency f0 of the matched filters 47-1 to 47-4. The frequency-converted signal passes through the band-pass filters 45-1 to 45-4, and the AGC 46-1 to 46-4 are controlled to always receive the signal from the transmitting station at the same power level. Only the information signal component of the signal that has passed through the AGC is extracted by the SAW matched filters 47-1 to 47-4 and input to the delay detection circuits 48-1 to 48-4. After the high-frequency signal component is removed from the delayed detection signal by the low-pass filters 49-1 to 49-4, the determination unit 50-1 to 50-4 determines the information signal at the peak point of the delayed detection output signal, and Clocks such as symbol timing and sample timing of the received signal are reproduced. Finally, the determination information signal is converted into the original continuous information signal 52 by the parallel-serial converter 51.
[0027]
As described above, by using the transmission / reception apparatus according to the present invention, each communication station transmits a plurality of spread spectrum signal waves simultaneously, so that adjacent spread spectrum signal waves, which is a problem of the conventional CFO-SSMA method, are used. Thus, it is possible to minimize the interference due to the chip timing offset and increase the transmission speed per communication station.
[0028]
Next, using the method of the present invention, in the same area, the frequency arrangement of the signal wave is determined so that the carrier frequency interval is an integral multiple of the frequency amount specified by the transmission rate, and multiple communication stations are connected in multiple ways. A form is demonstrated.
[0029]
FIG. 6 shows a configuration example of a system in which a plurality of simultaneous communication stations are connected to a backbone network via one communication control station (access point) according to the system of the present invention. FIG. 6 shows a configuration example in which five simultaneous communication stations are connected to one communication control station, and communication is performed using one spread spectrum signal wave per communication station. In the figure, reference numeral 60 denotes a communication control station (access point) connected to the backbone network, and 61-1 to 61-5 denote communication stations. The communication stations 61-1 to 61-5 are configured to allocate any one of the spread spectrum signal waves having carrier frequencies f1 to f5.
[0030]
Here, as shown in FIG. 6, the carrier wave frequencies f1 to f5 of the spread spectrum signal wave are separated from each other by an integral multiple of the frequency amount defined by the transmission rate, and f2, f3, f4, f5 is set. Furthermore, spread spectrum signal waves which are a set of carrier frequencies separated from each other by an even multiple of the frequency amount defined by the transmission rate, that is, {f1, f3, f5} and {f2, f4} are transmitted by the same polarization. The two sets have orthogonal polarizations. Therefore, even when the carrier frequency interval is an integral multiple of the frequency amount specified by the transmission rate within the same area, there is no interference between signals due to chip timing offset, and more simultaneous communication stations transmit information than in the conventional method. System that can be provided.
[0031]
When the system configuration is used, control for maintaining timing synchronization between all communication stations and the communication control station is periodically performed so that data packet signals transmitted from a plurality of communication stations are simultaneously received by the communication control station. Need to be done. Specifically, the communication control station transmits a PN burst signal for supplementing chip timing synchronization to each communication station, and the communication station transmits a PN burst whose timing is synchronized with the PN burst on a chip basis to the communication control station. This is realized by using a method of returning the data.
[0032]
In addition, the difference in the received signal level between the spread spectrum signal waves caused by the difference in distance between each communication station and the communication control station is a major factor that deteriorates the reception characteristics at the communication control station. In order to avoid this problem, the transmission power of each communication station is controlled. Specifically, the communication control station periodically observes the reception level of the PN burst signal transmitted from each communication station, and the transmission power control is performed so that the reception signal levels of all spread spectrum signal waves are equal at the communication control station. Can be realized by instructing each communication station. This can be realized by performing transmission power control in steps of about 1 dB according to this command on the communication station side.
[0033]
In this system mode, an example in which a plurality of communication stations are connected in multiple ways in one area has been shown. However, the present invention can be similarly applied to a case where two or more areas exist. Further, the present invention can be applied to a system configuration in which a plurality of spread spectrum signal waves are simultaneously transmitted per communication station and a plurality of communication stations perform multiple access. As described above, according to the system of the present invention, it is possible to construct a network not only in one system form but also in various system forms.
[0034]
【The invention's effect】
Therefore, according to the present invention, since the frequency interval can be an integral multiple of the frequency amount defined by the transmission rate, it is possible to theoretically increase the number of simultaneously communicable stations to the maximum.
[0035]
In addition, when one communication station selects and communicates with a plurality of spread spectrum signal waves, it is possible to increase the transmission speed per communication station.
[0036]
In addition, since spread spectrum signal waves from multiple simultaneous communication stations are transmitted in orthogonal polarization, it is possible to maximize the frequency utilization efficiency within the specified band without degrading the line quality of the transmission path. It is.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of a spread spectrum communication method according to the present invention.
FIG. 2 is a diagram showing an example of frequency arrangement of spread spectrum signal waves by the spread spectrum communication method of the present invention.
FIG. 3 is a diagram showing an embodiment of a transmitter configuration of a spread spectrum communication method according to the present invention.
FIG. 4 is a diagram showing an embodiment of a receiver configuration of a spread spectrum communication method according to the present invention.
FIG. 5 is a diagram showing an example of frequency arrangement of spread spectrum signal waves by the spread spectrum communication method of the present invention.
FIG. 6 is a diagram showing an example of network construction by the spread spectrum communication method of the present invention.
FIG. 7 is a diagram illustrating a configuration example of a spread spectrum communication method according to a conventional technique.
FIG. 8 is a diagram illustrating a method of multiplexing spread spectrum signal waves in a spread spectrum communication method according to the prior art.
FIG. 9 is a diagram showing an example of frequency arrangement of spread spectrum signal waves in a spread spectrum communication method according to a conventional technique.
FIG. 10 is a diagram showing an example of frequency arrangement of spread spectrum signal waves according to the CFO-SS system which is a conventional system.
FIG. 11 is a diagram illustrating an example of frequency arrangement of spread spectrum signal waves according to a conventional CFO-SS system.
[Explanation of symbols]
1-1 to 1-2n information signal
2-1 to 2-2n modulator
3-1-3-2n PN code
4-1 to 4-2n modulator
5-1 to 5-2n Local oscillator
6-1 to 6-2n band pass filter
7 Synthesizer representing transmission path model
8 Bandpass filter
9 Frequency converter
10 Local oscillator
11 Demodulator
12 Information signal after demodulation
20 Information signal
21 Serial-parallel converter
22-1 to 22-4 modulator
23 PN code generator
24-1 to 24-4 modulator
25-1 to 25-4 Local oscillator
26-1 to 26-4 band pass filter
27-1 to 27-2 Signal Synthesizer
28-1 to 28-2 Common amplifier
29-1 to 29-2 Band-limiting filter
30-1 to 30-2 Antenna according to polarization
40-1 to 40-2 Antenna corresponding to polarization
41-1 to 41-2 amplifier
42-1 to 42-2 reception filter
43-1 to 43-4 Frequency converter
44-1 to 44-4 Local oscillator
45-1 to 45-4 Bandpass Filter
46-1 to 46-4 Automatic Gain Controller (AGC)
47-1 to 47-4 SAW matched filter
48-1 to 48-4 Delay Detection Circuit
49-1 to 49-4 Low-pass filter
50-1 to 50-4 determiner
51 Parallel-serial converter
52 Information signal
60 Communication control station
61-1 to 61-5 communication station
70-1 to 70-k information signal
71-1 to 71-k modulator
72-1 to 72-k PN code
73-1 to 73-k modulator
74-1 to 74-k local oscillator
75-1 to 75-k bandpass filter
76 Synthesizer representing transmission path model
77 Band pass filter
78 Frequency converter
79 Local oscillator
80 Demodulator
81 Information signal after demodulation

Claims (1)

Information signals are individually spread spectrum-modulated individually using the same pseudo-random code sequence between one communication station and the other plurality of simultaneous communication stations, and the plurality of communication stations are subjected to the spread spectrum modulation. In a spread spectrum communication method for transmitting signals independently and simultaneously using carrier frequencies separated by an integral multiple of each other in units of a frequency amount defined by a transmission rate,
The one communication station and the other communication station transmit information using any one of spread spectrum signal waves,
The one communication station is a unit of the amount of frequency defined by the transmission rate with respect to the other plurality of simultaneous communication stations, and all the spread spectrum signal waves having carrier frequencies separated by an integral multiple of each other. Among them, a plurality of and all of the spread spectrum signal waves whose carrier frequency intervals are an even multiple of the frequency amount defined by the transmission speed are transmitted with the first polarization , and at the same time, a plurality of other than the spread spectrum signal waves and all of the spread spectrum communication method is characterized in that information transmitted in the second polarization spread spectrum signal waves orthogonal to the first polarization.

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