JPH09130298A - Transmitter, receiver, communication system and multiple access system for spread spectrum communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need of obtaining accurate synchronization on a reception side in the case of demodulating spectrum spread signals on the reception side. SOLUTION: The buffer means 12, digital synchronization signal generation means 13(0)-13(N) and signal selection means 14 of this transmitter 10 select and output digital signals S(n) corresponding to the decoding value of the divided block from digital synchronization signals S(O)-S(N) alternating in mutually different cycles determined beforehand based on the divided block obtained by divided binary information data signals inputted by an input means 11 by (m) bits each and a digital modulation means 15 converts the selected output to the signal of a radio band and outputs it through an output means 16. The frequency discrimination means 22 of this receiver 20 discriminates the frequency of reception signals inputted through the input means 26 and a binary information data signal demodulation means 24 demodulates the original binary information data signals based on a frequency discriminated result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication system transmitting apparatus, a receiving apparatus, a communication system, and a multiple access system, which perform communication by spreading a frequency band of information.

[0002]

2. Description of the Related Art Conventionally, a spread spectrum communication system of this type and a communication system using this system are, for example,
"Applied spread spectrum communication technology, supervised by Masao Nakagawa,
Trikeps, Chapter 1 ”.

As the spread spectrum communication system, various methods have been studied so far as described in the above-mentioned document, but the most typical one is the direct spread type.

In the direct spread type, an exclusive OR operation is normally performed on a binary information data signal by a spread code signal which is faster than the information data signal in which one bit period of the information data signal corresponds to one cycle. By doing so, the spectrum of the signal is spread. On the receiving side, the received signal is correlated with the same spread code signal as on the transmitting side to demodulate the information data signal.

At this time, the information data signal component returns to the original narrow spectrum signal, but the noise component and the interference component that have no correlation with the used spread code signal remain the wide spectrum signal. Therefore, by removing a signal in an unnecessary band with a filter, the signal-to-noise ratio can be improved by a gain called process gain.

In a multiple access system using a direct spread spectrum spread communication method as a communication method, as described in the above-mentioned document, by using a spread code signal unique to each channel, , Enables multiplex communication. That is, since signals other than the desired channel have a small correlation with the spread code signal used in the desired channel, the power is attenuated by the correlation processing and the filtering processing on the receiving side and can be removed.

[0007]

However, in the above-mentioned direct spread spectrum spread spectrum communication system, when demodulating a signal at the receiving side, it is necessary to correlate the received signal with the same spread code signal as at the transmitting side. And at this time,
There is a problem in that it is required to synchronize the received signal and the spread code signal for demodulation with high accuracy.

The present invention has been made in consideration of the above points, and a transmitter, a receiver, a communication system, and a multiple access of a spread spectrum communication system which do not require accurate synchronization on the receiving side. The purpose is to provide a system.

[0009]

In order to solve the above-mentioned problems, the present invention relates to a case where a spectrum of a binary information data signal is spread in a transmission side of a spread spectrum communication system or a multiple access system. For each divided block obtained by dividing the data string of the binary information data signal by m bits, the value of this divided block is selected from 2 ^m digital periodic signals that alternate at predetermined different periods. It is adapted to diffuse by selecting and outputting the corresponding digital periodic signal.

Further, according to the present invention, when demodulating a received signal whose spectrum has been spread on the receiving side of the system as described above, the frequency of the received signal is discriminated, and an m-bit binary corresponding to the discrimination result. The information data signal is sequentially output.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

[First Embodiment of Communication System of Spread Spectrum Communication System] A first embodiment of a communication system of spread spectrum communication system will be described. Since the transmission device and the reception device of the spread spectrum communication system are components of this communication system, they will be described together with this communication system.

[Structure] FIG. 1 is a block diagram showing the structure of a communication system of spread spectrum communication system.

The illustrated communication system has a transmitter 10 and a receiver 20. Here, the dotted line represents that the transmission signal is a signal in the wireless band.

The transmitter 10 has a function of spreading and transmitting the spectrum of the binary information data signal to be transmitted.
The receiving device 20 has a function of receiving the signal transmitted by the transmitting device 10 and demodulating the binary information data signal before being spectrum spread.

The transmitting device 10 includes an input means 11, a buffer means 12, and a digital periodic signal generating means 13.
(0), 13 (1), ..., 13 (N), a signal selecting means 14, a digital modulating means 15, and an output means 16.

Here, the input means 11 has a function of inputting to the buffer means 12 an information data signal which has been converted into a digital signal by an analog / digital conversion means (not shown).

The buffer means 12 has a function of temporarily holding the binary information data signal input by the input means 11 and dividing the data string by m bits for output. Here, there is a relationship of N + 1 = 2 ^m between m and N.

Digital periodic signal generating means 13 (0),
13 (1), ..., 13 (N) are digital periodic signals S (0), S (1), alternating with a predetermined period, respectively.
.., S (N) are generated. This (N + 1)
Individual digital periodic signals S (0), S (1), ..., S
The periods (N) are set to different values. In the figure, when N is 3 or more, in other words, m is 2
The above case is shown.

Each time the m-bit data (hereinafter referred to as a “divided block”) supplied from the buffer means 13 is switched, the signal selection means 14 decodes the switched data, and (N + 1) digital data is output. The digital periodic signal S (n) corresponding to the decode value n (n = 0, 1, 2, ..., N) is selected from the periodic signals S (0), S (1), ..., S (N). And then output 2
It has a function of generating a signal in which the spectrum of the binary information data signal is spread.

The digital modulating means 15 has a function of converting the frequency band of the spread spectrum signal from the base band to the radio band by digitally modulating the spread spectrum signal generated by the signal selecting means 14.

The output means 16 has a function of supplying a radio band signal obtained by digital modulation to a transmission antenna or the like (not shown).

The receiving device 20 includes an input unit 21, a frequency discriminating unit 22, and a binary information data signal demodulating unit 23.
And output means 24.

Here, the input means has a function of inputting the signal of the radio band received by the receiving antenna (not shown) to the frequency discriminating means 22.

The frequency discriminating means 22 has a function of discriminating the frequency of the signal in the radio band inputted by the inputting means 21. The frequency discriminating unit 22 may discriminate the frequency by a discriminator used in FM demodulation or the like, or may discriminate the frequency by digital calculation such as fast Fourier transform (FFT).

The binary information data signal demodulating means 23 has a function of demodulating the original binary information data signal by generating m-bit data based on the discrimination result of the frequency discriminating means 22.

The output means 24 has a function of supplying the demodulated binary data signal to digital / analog means (not shown).

[Operation] The operation of the above configuration will be described.

The binary information data signal input by the input means 1 is temporarily stored in the buffer means 12.
The buffer means 12 collects the binary information data signals for every m bits and sends them to the signal selecting means 14.

The signal selecting means 14 is further provided with digital periodic signal generating means 13 (0), 13 (1), ...
13 (N) output digital periodic signal S
(0), S (1), ..., S (N) are supplied.

The signal selecting means 14 decodes the m-bit divided block supplied from the buffer means 12, and the digital periodic signal S (n) corresponding to the decoded value n.
Select This operation is executed every time the divided blocks are switched. As a result, a signal obtained by spreading the spectrum of the binary information data signal is obtained.

This spread spectrum signal is supplied to the digital modulation means 15 and is digitally modulated. As a result, the frequency band of the spread spectrum signal is converted from the base band to the wireless band. Note that a BPSK modulation method, a QPSK modulation method, or the like is used as the digital modulation method.

The spread spectrum signal converted into the radio band is supplied to the antenna (not shown) by the output means 16 and radiated into the air.

The spread spectrum signal emitted in the air is
It is received by an antenna (not shown) of the receiving device 20.
This received signal is supplied to the frequency discriminating means 23 via the input means 21 and discriminates its frequency. As a result, information about the frequency of the received signal is obtained.

This frequency information is supplied to the binary information data signal demodulation means 23 and decoded using the same rule as the signal selection rule of the signal selection means 14. As a result, m-bit data corresponding to the frequency of the received signal is obtained. This process is performed every time new frequency information is obtained.
As a result, the original binary information data signal is demodulated.

The demodulated binary information data signal is supplied to the digital / analog converting means (not shown) by the output means 25 and is returned to the analog signal.

FIG. 2 shows a digital periodic signal generating means 13
It is a figure which shows the digital periodic signal S (0), S (1), ..., S (1) output from (0), 13 (1), ..., 13 (N) in a time domain. In addition, FIG.
It is a figure which shows (0), S (1), ..., S (N) in a frequency domain.

As shown in FIG. 2, digital periodic signal generators 13 (0), 13 (1), ..., 13 (N) output digital periodic signals S (0), S (1) ,.
When viewed in the time domain, S (1) is a signal whose cycle increases by a predetermined value Δ as n increases.

In this case, the digital periodic signal S output from the n-th digital periodic signal generating means 13 (n)
The period of (n) is represented by (P + nΔ). However, the period (P + NΔ) of the digital periodic signal S (0) output from the N-th digital periodic signal generating means 13 (N)
Is set to a value sufficiently smaller than the switching period of the m-bit divided block output from the buffer means 12.

As shown in FIG. 3, digital periodic signal generators 13 (0), 13 (1), ..., 13 (N) output digital periodic signals S (0), S (1) ,.
When viewed in the frequency domain, S (1) is a narrow band signal in which spectra are arranged at equal intervals.

In order to secure such a signal, the above-mentioned condition regarding the period P is necessary. In this case, the spectrum of the digital periodic signal S (n) output from the n-th digital periodic signal generating means 13 (n) becomes the n-th spectrum from the higher frequency (right in the figure). The center frequency fn is fn = 1 / (P + nΔ) / Tc. However, Tc is the digital periodic signals S (0), S
(1), ..., S (N) chip speed.

The signal in the radio band output from the output means 16 of the transmitter 10 shown in FIG. 1 is a signal obtained by shifting the signal in the frequency domain of FIG. 3 to the radio band. When the spectrum is observed with time, each time the signal selecting means 14 switches the selection signal, the narrow band spectrum shown in FIG. 3 is switched.

Therefore, the receiving side can detect the information on the frequency by using an element such as a discriminator used for demodulating the FM signal.
Then, by decoding this frequency information into m-bit data using the same rule as the signal selection rule of the signal selection means 14, the original binary information data can be demodulated.

At this time, if the period P is sufficiently large, 1
Accurate bit synchronization is not necessary because the two frequencies are transmitted for a long time. Further, instead of the discriminator, the frequency can be detected by digital calculation such as fast Fourier transform (FFT).

[Effect] According to this embodiment described in detail above, the following effects can be obtained.

(1) First, according to this embodiment, every divided block obtained by dividing the binary information data signal to be transmitted by m bits alternates with a predetermined cycle different from each other. From the 2 ^m digital periodic signals S (0), S (1), ..., S (N), the digital periodic signal S (n) corresponding to the decoded value n of this divided block is selected and output. As a result, the spectrum of the binary information data signal is spread, so that the reception side does not need to perform correlation with the same spread code signal as the transmission side, but frequency discrimination using a discriminator etc. The binary information data signal can be demodulated. As a result, since it is only necessary for the receiving side to roughly synchronize the signals, the conventional problems can be solved.

(2) Further, according to this embodiment, m
When generating the digital periodic signal S (n) corresponding to the decoded value n of the divided block of bits, (N + 1) digital periodic signal generating means 13 (0), 13 (1),
, 13 (N) and the signal selecting means 14, the signal can be generated with a simple configuration.

(3) Further, according to this embodiment, the system can be easily made by the frequency hopping type spread spectrum communication system. That is, in this embodiment, if the viewpoint is changed, the spread spectrum communication system 1
It can also be seen as a variant of the frequency hopping type that is the seed. However, in the frequency hopping type spread spectrum communication system, the synthesizer is an indispensable constituent element, whereas this embodiment does not require the synthesizer. Therefore, in this embodiment, the system can be made more easily than the frequency hopping type.

[Second Embodiment of Spread Spectrum Communication Communication System] A second embodiment of the spread spectrum communication system will be described.

In the first embodiment, the case where four or more digital periodic signals are used has been described. In other words, m
The case has been described where is set to a value of 2 or more. In contrast,
In this embodiment, only two are used. In other words, m is set to 1.

[Structure] FIG. 4 is a block diagram showing a structure of a main part of a second embodiment of a spread spectrum communication system. Note that, in FIG. 4, for simplification of description, parts having substantially the same functions as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

4 is different from FIG. 1 in that the buffer means 12 is not provided, only two digital periodic signal generating means are provided, and the signal selecting means 17 is divided into m bits. The point is that it does not have a block decoding function.

[Operation] The data string of the binary information data signal input from the input means 11 is supplied to the signal selection means 17 for each 1-bit divided block. Here, “for each 1-bit divided block” means that the binary information data signal is supplied as it is. Therefore, in this embodiment, the buffer means 12 becomes unnecessary.

The signal selecting means 17 determines the value of the input signal bit by bit. When the value is "0", the digital periodic signal S (0) output from the digital periodic signal generating means 14 (0) is selected. If it is "1", the digital periodic signal 14 (1) output from the digital periodic signal generating means 14 (0) is selected. Therefore, the signal selecting means 17 does not need the decoding function of the m-bit divided block.

[Effect] According to this embodiment described in detail above, the same effect as that of the previous embodiment can be obtained, and further, the effect that the buffer means 12 becomes unnecessary and the signal selecting means 17 are provided. It is possible to obtain the effect that there is no need to provide a decoding function in.

[One Embodiment of Spread Spectrum Communication Multiple Access System] One embodiment of the spread spectrum communication multiple access system will be described.

[Structure] FIG. 5 is a block diagram showing the structure of an embodiment of the multiple access system of this embodiment.

The illustrated multiple access system has a plurality of terminal devices 31 (0) to 31 (K) and one base station device 32. Here, the dotted line represents that the signal is transmitted in the wireless band. Although FIG. 5 shows a case where one base station device 32 is provided, a plurality of base station devices 32 may be provided and these may be connected by a wired transmission path or a wireless transmission path.

Each terminal device 31 (k) has the same transmission function as the transmission function of the transmission device 10 shown in FIG. 1 or FIG. 4, spreads the spectrum of the binary information data signal, and then digitally modulates and transmits it. To do.

The base station apparatus 8 is the receiving apparatus 20 shown in FIG.
It has the same reception function as the reception function of, and as described above, by frequency discrimination detection using a discriminator,
Demodulate each signal.

[Operation] The operation of the above configuration will be described with reference to FIG.

FIG. 6 is a diagram showing an example of spectrum design in the multiple access system of this embodiment.

In FIG. 6, each narrow band spectrum is simplified and shown by a thick line. Further, in FIG. 6, the terminal devices 31 (0), 31 (1), ..., 31 (K) have the same value as each bit of the binary information data signal as in the transmitting device 10 described in FIG. Accordingly, the case where two digital periodic signals S (0) and S (1) are selectively selected will be shown as a representative.

As shown in FIG. 6, when the value of each bit of the binary information data signal is "0", the terminal devices 31 (0), 3
1 (1), ..., 31 (N), digital periodic signals of narrow band spectrum having center frequencies of f00, f01, ..., F0K are selected. On the other hand, when the value of each bit of the binary information data signal is “1”, the terminal device 31
In (0), 31 (1), ..., 31 (N), digital periodic signals of narrow band spectrum whose center frequencies are f10, f11 ,.

The narrow band spectra of the (K + 1) digital periodic signals selected when the bit value of the binary information data signal is "0" do not overlap each other.
They are lined up at equal intervals. Similarly, the narrow band spectra of the (K + 1) digital periodic signals selected in the case of “1” are also arranged at equal intervals without overlapping each other. Moreover, (K + 1) narrow band spectra selected in the case of “0” and (K +) in the case of “1”.
1) Narrow-band spectra are also arranged without overlapping each other.

According to such a configuration, all the terminal devices 31 (1), 31 (2), ...
In (K), since the narrow band spectrums do not overlap with each other, the base station device 32 has an arbitrary terminal device 31.
The signal from (K) can be demodulated by frequency discrimination detection.

In FIG. 6, the narrow band spectrums are prevented from overlapping in all the terminal devices 31 (1), 31 (2), ..., 31 (N) configuring the system. It is sufficient to ensure that the narrowband spectra do not overlap only between devices that are geographically close to each other that may cause

[Effect] According to this embodiment described in detail above, the same effect as the spread spectrum communication system described above can be obtained in the multiple access system.

Although the two embodiments of the communication system of the present invention and the one embodiment of the multiple access system have been described above, the present invention is not limited to the above-mentioned embodiments. Besides, it goes without saying that various modifications can be made without departing from the scope of the invention.

[0070]

As described in detail above, according to the present invention, a predetermined different cycle is set for each divided block obtained by dividing the binary information data signal to be transmitted by m bits. By selecting and outputting the digital periodic signal corresponding to the value of this divided block from the 2 ^m digital periodic signals alternating with
Since the spectrum of the binary information data signal is spread, the original binary information is detected on the receiving side by frequency discrimination detection using a discriminator, etc. without taking correlation with the same spread code signal as the transmitting side. The data signal can be demodulated. As a result, since it is only necessary for the receiving side to roughly synchronize the signals, the conventional problems can be solved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment of a spread spectrum communication system according to the present invention.

FIG. 2 is a diagram showing a digital periodic signal in the time domain in the communication system of FIG.

FIG. 3 is a diagram showing a digital periodic signal in the frequency domain in the communication system of FIG.

FIG. 4 is a block diagram showing a configuration of a main part of a second embodiment of a spread spectrum communication system according to the present invention.

FIG. 5 is a block diagram showing a configuration of an embodiment of a spread spectrum communication multiple access system of the present invention.

6 is a diagram showing a spectrum design example of a spread spectrum communication system in the multiple access system of FIG. 5;

[Explanation of symbols]

10 ... Transmitting device 20 ... Receiving device 11 ... Input means 12 ... Buffer means 13 (1), 13 (2), ..., 13 (N) ... Digital periodic signal generating means 14, 17 ... Signal selecting means 15 ... Digital modulating means 16 ... Output means 31 (1), 31 (2), ..., 31 (K) ... Terminal device 32 ... Base station device

Claims (11)

[Claims] 1. A 2 ^m number of digital periodic signals alternating in predetermined different periods for each divided block obtained by dividing a data string of a binary information data signal to be transmitted by m bits. Spread spectrum signal generating means for generating a signal in which the spectrum of the binary information data signal is spread by selecting and outputting a digital periodic signal corresponding to the value of this divided block from among these, and this spread spectrum signal generation And a digital modulation means for digitally modulating the spread spectrum signal generated by the means to convert the frequency band of the spread spectrum signal from a base band to a radio band. . 2. The spread spectrum signal generating means generates 2 of each of the 2 ^m digital periodic signals.
and the ^m digital periodic signal generating means, from among the 2 ^m pieces of digital periodic signal output from the 2 ^m pieces of digital periodic signal generating means, the signal for selecting the digital periodic signal corresponding to the value of the divided blocks 3. The spread spectrum communication system transmitter according to claim 1, further comprising a selection unit. 3. The transmission device according to claim 1, wherein the m is 1. 4. A 2 ^m number of digital periodic signals that alternate at a predetermined different period for each divided block obtained by dividing a data string of a binary information data signal to be transmitted by m bits. A device that receives a spread spectrum signal that is generated by selecting and outputting a digital periodic signal corresponding to the value of this divided block from the inside, and that has been converted from a base band to a radio band by digital modulation. And a frequency discriminating means for discriminating the frequency of the received signal, and a binary information data signal demodulating means for demodulating the binary information data signal based on the discrimination result of the frequency discriminating means. Spread spectrum communication receiver. 5. A transmission device for spectrum-spreading a binary information data signal and transmitting the same, and a binary information data before spectrum-spreading based on the received signal for receiving the signal transmitted by the transmission device. A receiver for demodulating a signal, the transmitter for each divided block obtained by dividing a data string of a binary information data signal to be transmitted by m bits,
The spectrum of the binary information data signal is obtained by selecting and outputting the digital periodic signal corresponding to the value of this divided block from the 2 ^m digital periodic signals that alternate at predetermined different periods. A spread spectrum signal generating means for generating a spread signal and a digital signal for converting the frequency band of the spread spectrum signal from a base band to a radio band by digitally modulating the spectrum spread signal generated by the spread spectrum signal generating means. Modulation means, and the receiving device demodulates the binary information data signal based on the frequency discrimination result of the frequency discrimination means for discriminating the frequency of the signal sent from the transmission device and the frequency discrimination means. And a binary information data signal demodulating means for performing spread spectrum communication. System communication system. Wherein said spread spectrum signal generation means, 2 and the ^m digital periodic signal generating means for generating each of the 2 ^m pieces of digital periodic signal, output from the 2 ^m pieces of digital periodic signal generating means 6. A spread spectrum communication system communication system according to claim 5, further comprising signal selecting means for selecting a digital periodic signal corresponding to the value of the divided block from 2 ^m digital periodic signals. . 7. The spread spectrum communication system according to claim 5, wherein said m is 1. 8. A spread spectrum communication multiple access system comprising a plurality of terminal devices and one or a plurality of base station devices, wherein each of the plurality of terminal devices transmits a binary information data signal to be transmitted. For each divided block obtained by dividing the data string by m bits, the digital periodic signal corresponding to the value of this divided block is selected from 2 ^m digital periodic signals that alternate at predetermined different periods. A spread spectrum signal generating means for generating a signal by spreading the spectrum of the binary information data signal by selecting and outputting, and digitally modulating the spread spectrum signal generated by the spread spectrum signal generating means. , A digital that converts the frequency band of this spread spectrum signal from the base band to the radio band. Modulating means, the one or more base station apparatus, based on the frequency discrimination result of the frequency discrimination means for discriminating the frequencies of the signals sent from the plurality of terminal devices, the frequency discrimination means, A spread spectrum communication system multiple access system comprising: a binary information data signal demodulating means for demodulating the binary information data signal. 9. The 2 ^m digital periodic signals output from each of the plurality of terminal devices are set so that the periods are all different from each other only among the plurality of terminal devices located geographically nearby. 9. The multiple access system of spread spectrum communication system according to claim 8. Wherein said spread spectrum signal generation means, 2 and the ^m digital periodic signal generating means for generating each of the 2 ^m pieces of digital periodic signal, output from the 2 ^m pieces of digital periodic signal generating means 9. The multiple access according to the spread spectrum communication system according to claim 8, further comprising signal selecting means for selecting a digital periodic signal corresponding to the value of the divided block from 2 ^m digital periodic signals. system. 11. The spread spectrum communication multiple access system according to claim 8, wherein said m is 1.