JP2003087156A - Transmitter-receiver in spread spectrum frequency modulation system and transmission and reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmitter-receiver in a spread spectrum frequency modulation system with a bit error rate reduced and a transmission and reception system. SOLUTION: A transmitter consists of a symbol string transforming means 1, a Fourier transforming means 2, a spread means 3, an inverse Fourier transforming means 4 and a multicarrier modulating means 5. Complex symbol strings SIS (m) of a digital signal in a plurality m (m is a positive integer) of subscribers are respectively inputted to the symbol string transforming means 1. The symbol string transforming means 1 rearranges m (m is an integer) kinds of and n (n is an integer) complex symbol strings T (m and n) in each complex symbol. The Fourier transforming means 2 performs Fourier transformation of the results, the spread means 3 randomly performs switching in each symbol, the inverse Fourier transforming means 4 performs inverse Fourier transformation, and the multicarrier modulating means 5 transmits the complex symbol strings as a signal SOS (m) from an unillustrated antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmitting / receiving device and a transmitting / receiving system in a spread spectrum frequency modulation system.

[0002]

2. Description of the Related Art A spread spectrum modulation system spread-modulates transmission power in a frequency band much wider than a normal communication band, even if the S / N (signal-to-noise power ratio) is small. In recent years, it has been widely used for satellite communication, satellite broadcasting, etc. because it enables communication.
From the well-known Shannon's theorem, in digital communication,
The number of bits that can be transmitted without error per unit bandwidth is C (bit / s) for transmission capacity and B (H for occupied frequency bandwidth).
z), assuming that the signal-to-noise power ratio is S / N, C is approximately 1.44B · S / N.

The spread spectrum modulation method is described in "Textbook Wireless Communication Equipment" by Hideki Tsutsusaka and Hideo Ohba, published by The Japan Society of Science and Technology Publishing. A transmitter and a receiver based on a frequency hopping method, which is an example of the spread spectrum modulation method, are disclosed in, for example, the Institute of Electronics, Information and Communication Engineers, VOL. J77-BII-NO. 5 (May 1994 issue) PP 233-239 "Configuration and characteristics of high-speed frequency hopping transceiver using digital signal processing, Sawahashi, Adachi", respectively.
18 and a block diagram as shown in FIG.

In FIG. 17, a transmitter 160 comprises a well-known frequency hopping modulator 161, a hopping sequence generator 163, and a modulating means 162.
The receiver 170 includes a well-known frequency conversion filter 171.
, Hopping sequence generator 173, and demodulation means 1
72 and 72. Modulating means 162 and demodulating means 1
Reference numeral 72 denotes a well-known quadrature modulator (QAM) and quadrature demodulator (QADM) that convert digital data into a complex symbol string, respectively. Also transmitter 160 and receiver 1
Each 70 is capable of transmitting and receiving a complex signal.

In the transmitter 160 of FIG. 17 according to the frequency hopping method, a complex symbol string SIS of a digital signal is applied to the frequency hopping modulator 161. The complex symbol sequence SIS applied to the frequency hopping modulator 161 is a well-known method, and the frequency hopping modulator 161 and the hopping sequence generator 163 are used.
Is converted into a symbol string having a random frequency. Then, for example, it is modulated by the modulation means 162 which is a well-known quadrature modulator (QAM), and is output as a signal SOS from an antenna (not shown).

Further, in the receiver 170 of FIG. 18, the modulated signal SIR received by an antenna (not shown) is
For example, the frequency conversion filter 171 is demodulated by the demodulation means 172 which is a well-known quadrature demodulator (QADM).
Applied to. Then, the frequency conversion filter 171 and the hopping sequence generator 173 are formed by a known method.
As a result, the symbol sequence SOR of the digital signal is output.

[0007]

The transmitter / receiver based on the frequency hopping method has the following problems. The terms are defined and used below for the understanding of the description. (Definition) Interfering station: A transmitting station other than the main transmitting station that communicates with each other. Interfering station: A receiving station that receives a signal transmitted from any interfering station. Complex symbol sequence: A data sequence represented in the time domain, having parameters of amplitude and phase. Complex sequence: A sequence of data expressed in the frequency domain, obtained as a result of Fourier transform.

The signal collision between the interfering station and the interfered station in the transceiver will be described below with reference to FIGS. 19 and 20. FIG. 20 is a diagram for explaining a signal collision between an interfering station and an interfered station in a transceiver, and FIG. 19 is an explanatory diagram when frequency hopping is not performed and FIG. 20 is an explanatory diagram when frequency hopping is performed. 19 and 20, the transmitting and receiving frequencies (f0, f1, f2, f of the interfering station and the interfered station are shown.
3) is the vertical axis, the time (T0, T1, T2, T3) is the horizontal axis, and the time when the transmission / reception symbol string exists at the corresponding transmission / reception frequency is represented by the ● symbol.

As shown in FIG. 19, when the transmitting station transmits a transmission symbol sequence at a single frequency f0 in the order of T0, T1, T2, T3, the interfered station is the same as the given interfering station. The transmission symbol sequence is represented by T0, T1, T at one frequency f0.
Receive in the order of 2 and T3. In such a case, the interfered station may receive a signal of the same frequency as the signal from the main transmitting station for communicating with each other from the interfering station at the same time, and the signals may collide with each other and demodulate the signal correctly. I can't.

FIG. 20 is an explanatory diagram of a frequency hopping system that solves such a problem. In FIG. 20, an arbitrary interfering station randomly transmits a transmission symbol using a plurality of frequencies f0, f1, f2, and f3. For example, any one interfering station performs frequency hopping at times f0, f2, f1, and f3 at times T0, T1, T2, and T3, respectively. At the interfered station, at the times T0, T1, T2, and T3 with the main transmitting station, the frequency f
Frequency hopping is performed at 1, f2, f1, and f0, and demodulation is performed at such frequencies.

In such a case, as is apparent from FIG. 20, the signals of the main transmitting station and the interfering station received at the same frequency at the same time are only the signals transmitted at the frequency f2 at time T1. Therefore, as described with reference to FIG. 19, it is possible to avoid the worst situation in which the collision occurs at the same frequency at all times.

FIG. 21 is a diagram showing an example of bit error rate characteristics in the conventional frequency hopping system described in FIG. In FIG. 21, the vertical axis represents the bit error rate BE
The horizontal axis of R is the ratio DUR of the desired wave power and the undesired wave power, and the number of interfering stations is one. Ideally, the error rate for an interference signal has a Gaussian noise characteristic GN.
However, as described above, the collision with the signal from the interfering station increases the desired wave power, that is, the signal from the main transmitting station (increases the DUR), as indicated by IN in FIG.
Nevertheless, the bit error rate BER is almost constant,
There was a problem that it did not decrease.

In the current communication technology, if the bit error rate BER is about 0.0001, it is possible to perform error correction by well-known Reed-Solomon coding,
There is a demand for a transmitter / receiver and a transmitter / receiver system that can realize a low-cost transmitter / receiver using an LSI and reduce the bit error rate BER.

It is an object of the present invention to solve the above problems and provide a transmission / reception apparatus and a transmission / reception method in a spread spectrum frequency modulation system with a reduced bit error rate.

[0015]

In order to achieve the above-mentioned object, the present invention comprises a symbol string converting means which is a time domain rearranging means for regularly rearranging time-series transmission data. Further, the time domain signal rearranged in the time domain is transformed into a frequency domain, and a spreading means which is a frequency interchange means for irregularly exchanging the signals is provided. As a result, the symbol string converting means improves the uniformity of data for each subscriber when the frequency hopping is performed by the spreading means. That is, even for a subscriber having no transmission data, when performing the frequency hopping, the data of another subscriber is made to exist, and the conversion of data zero is not performed for the conversion to any subscriber. I was not allowed to.

Further, the time domain signal regularly rearranged by the symbol string conversion means is transformed into the frequency domain, and this is irregularly replaced by the spreading means, so that a plurality of symbols of the interfering signal are covered. The central limit theorem is established by interfering with multiple symbols of the interference signal.

Specifically, in the transmitter / receiver according to claim 1, in the transmitter / receiver in the spread spectrum frequency modulation system, each of the transmitter and the receiver constituting the transmitter / receiver is a symbol sequence for rearranging a complex symbol sequence. It is provided with a transforming means, a Fourier transforming means for performing a Fourier transform on the complex symbol sequence, a diffusing means for replacing the transforming result of the Fourier transforming means, and an inverse Fourier transforming means for inverse Fourier transforming the output of the diffusing means. And

In the transmitting / receiving device according to the second aspect, the symbol string converting means sets m (m is an integer) kinds and n (n is an integer) complex symbol strings T (m, n) for each complex symbol. Where k is an integer and ± is the sorting direction, and T (m ±
It is characterized by regularly rearranging into a complex symbol sequence of k, n).

According to a third aspect of the present invention, there is provided the transmitting and receiving apparatus according to the third aspect, wherein the symbol string converting means has a transmitter and a receiver in which rearrangement directions are opposite to each other.

In the transmitting / receiving apparatus according to the fourth aspect, the Fourier transforming means Fourier transforms a complex symbol sequence in which the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence. It is characterized by converting.

According to a fifth aspect of the present invention, there is provided the transmitting / receiving apparatus, wherein the Fourier transforming means is provided in plural.

According to a sixth aspect of the present invention, in the transmission / reception apparatus, the spreading means includes k complex number sequence groups, one complex number sequence group n complex number sequences F (k, n), and p is a random number for each complex number sequence. It is characterized in that k complex number sequence groups F (± p, n) having ± as the sorting direction are randomly switched.

According to a seventh aspect of the present invention, there is provided a transmission / reception apparatus, wherein the type m in the symbol sequence conversion means and the number n of one complex symbol sequence, the number k of complex number sequence groups in the spreading means,
And the number n of complex number sequences in one complex number sequence group are equal to each other.

[0024] In the transmitting / receiving apparatus according to the eighth aspect, the spreading means of the transmitter and the receiver are switched in opposite directions.

According to a ninth aspect of the transmission / reception apparatus, a plurality of the inverse Fourier transform means are provided.

According to a tenth aspect of the present invention, the symbol sequence conversion means of the transmitter rearranges the complex transmission symbol sequence for each subscriber.

In the transmitter / receiver according to the eleventh aspect of the present invention, the Fourier transform means of the transmitter performs Fourier transform on a plurality of types of complex symbol sequences rearranged by the symbol sequence conversion means.

According to a twelfth aspect of the present invention, there is provided a transmitting / receiving apparatus, wherein the symbol string converting means of the receiver rearranges the outputs of the inverse Fourier transforming means.

In the transmission / reception system according to claim 13, in the transmission / reception system in the spread spectrum frequency modulation system, a symbol sequence conversion means for rearranging the complex symbol sequence, a plurality of Fourier transform means for Fourier transforming the complex symbol sequence, and the Fourier transform means. The transmitter and the receiver are provided with the spreading means for interchanging the conversion results of the converting means and the plurality of inverse Fourier transform means for performing the inverse Fourier transform on the output of the spreading means, and the transmitter uses the complex transmission symbol sequence for each subscriber. The symbol sequence conversion means rearranges, the rearranged complex transmission symbol sequence is Fourier-transformed by the plurality of Fourier transform means, the complex number sequence is replaced by the diffusion means, and the inverse Fourier transform means is performed by the plurality of inverse Fourier transform means. It is converted, modulated at different frequencies and transmitted. Receiving and demodulating the complex transmission symbol sequences transmitted by the transmitter and respectively modulated at different frequencies, performing Fourier transform by the plurality of Fourier transforming means, replacing the complex number sequence by the spreading means, and the plurality of inverses. Inverse Fourier transform is performed by the Fourier transform means, and rearrangement is performed by the symbol string transform means to obtain a complex received symbol string for each subscriber.

In the transmission / reception system according to claim 14, the rearrangement in the symbol string conversion means is m (m is an integer).
Type, n (n is an integer) complex symbol sequence T (m, n)
Is regularly sorted into a complex symbol sequence of T (m ± k, n), where k is an integer and ± is a sorting direction for each complex symbol.

In the transmission / reception system according to the fifteenth aspect, the rearrangement by the symbol string conversion means is performed by reversing the rearrangement direction between the transmitter and the receiver.

In the transmission / reception system according to the sixteenth aspect, the replacement by the spreading means is performed by converting the complex number sequence group of k complex number sequence n, the complex number sequence F (k, n) of n complex number p to each complex number sequence.
Where k is a random number and ± is a rearrangement direction
The feature is that (± p, n) is irregularly replaced.

In the transmission / reception system according to the seventeenth aspect, the replacement by the spreading means is carried out by reversing the replacement directions of the transmitter and the receiver.

[0034]

1 and 2 are block diagrams of a transmission / reception apparatus showing an embodiment of the present invention, in which FIG.
FIG. 2 shows a receiver. An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. For simplicity of explanation,
Digital modulation is based on the well-known 16QAM (quadrature modulator), and time-series transmission data and reception data are
It shall be processed by replacing it with 4-bit parallel data.

In FIG. 1, the transmitter comprises a symbol string transforming means 1, a Fourier transforming means 2, a spreading means 3, an inverse Fourier transforming means 4 and a modulating means 5. To the symbol sequence conversion means 1, complex symbol sequences SIS (m) of digital signals of a plurality of m (m is an integer) subscribers are respectively inputted from a digital signal input means (not shown). The modulation means 5 is a multi-carrier modulator including a plurality of well-known quadrature modulators (QAMs) having different modulation frequencies, and the signal modulated by the modulation means 5 is not shown in the figure. Signal from SOS
(M) is transmitted.

The complex symbol sequence SIS (m) is input to the symbol sequence conversion means 1 and, as will be described later, m
(M is an integer) types and n (n is an integer) number of complex symbol sequences T (m, n) are rearranged for each complex symbol. The signals rearranged for each one complex symbol are input to the Fourier transform means 2.

The Fourier transforming means 2 Fourier transforms the complex symbol string T (m, n) represented in the time domain, which is input from the symbol string transforming means 1, and transforms it into frequency domain data.

The output of the Fourier transforming means 2 is input to the diffusing means 3. As will be described later, the diffusing unit 3 sets k complex number sequence groups, 1 complex number sequence group n complex number sequences F (k, n), where p is a random number and ± is a permutation direction for each complex number sequence. The k complex number sequence groups F (± p, n) are randomly replaced.

The replaced complex number sequence is input to the inverse Fourier transform means 4, and the complex number sequence group F (± p, n) represented in the frequency domain is inverse Fourier transformed to be represented in the time domain. Existing complex symbol sequence t (m, n). The complex symbol sequence t (m, n) is modulated by the modulation means 5 and a signal SOS is output from an antenna (not shown).
(M) is transmitted.

In FIG. 2, the receiver comprises demodulating means 6, Fourier transforming means 2, spreading means 7, inverse Fourier transforming means 4 and symbol string transforming means 8. The signal modulated by the modulator 5 of the transmitter and transmitted from the antenna (not shown) is received by the antenna (not shown) of the receiver and input to the demodulator 6. The demodulation means 6 is a well-known quadrature demodulator (QAD) having a different demodulation frequency.
M) is a multi-carrier demodulator provided with a plurality of signals, and the signal demodulated by the demodulating means 6 is input to the Fourier transforming means 2 as a complex symbol sequence t (m, n).

The Fourier transform means 2 is the same as the Fourier transform means 2 provided in the transmitter, and is a complex symbol sequence t (m, n) represented in the time domain, which is input from the demodulation means 6. ) Is Fourier transformed and transformed into frequency domain data.

Further, the output of the Fourier transforming means 2 is inputted to the spreading means 7, and by the same method as the spreading means 3 of the transmitter, k complex number sequence groups, 1 complex number sequence group n complex number sequences F (k , N) are randomly replaced as k complex number sequence groups F (± p, n) where p is a random number and ± is the interchange direction for each complex number sequence. However, the replacement of the spreading means 7 in the receiver is opposite to the replacement of the spreading means 7 in the transmitter, as will be described later.

The output of the spreading means 7 is obtained by the same inverse Fourier transform means 4 as the inverse Fourier transform means 4 provided in the transmitter, and the complex number sequence group F (± p, n) represented in the frequency domain is obtained. ) Is transformed into a complex symbol sequence T (m, n) represented in the time domain.

The complex symbol sequence T (m, n) is converted into m (m is an integer) types, n by the symbol sequence conversion means 8 which is the same as the symbol sequence conversion means 1 provided in the transmitter.
(N is an integer) number of complex symbol sequences T (m, n) are rearranged for each complex symbol. Related complex symbol sequence T
(M, n) is output from the symbol string conversion means 8 as a signal SOR (m). However, the rearrangement of the symbol string converting means 8 in the receiver is opposite to the rearranging direction of the symbol string converting means 1 in the transmitter, as described later.

FIGS. 3 and 4 are detailed block diagrams of a transmitting / receiving apparatus showing an embodiment of the present invention. FIG. 3 shows a transmitter and FIG. 4 shows a receiver. FIG. 7 shows a shift circuit of the transmission / reception apparatus according to the embodiment of the present invention, FIG. 7A shows a shift circuit used in the transmitter, and FIG. 7B shows a shift circuit used in the receiver. Embodiments of the present invention will be described below with reference to FIGS. 3, 4, and 7. In the embodiments of FIGS. 3 and 4, it is assumed that the processing described below is performed by a microprocessor (not shown) in which a predetermined program is stored in advance. The Fourier transform means and the inverse Fourier transform means are, for example, LS for Fourier transform and inverse Fourier transform commercially available from doubleBW.
By using I “DBW-128” or the like, it is possible to transmit / receive a signal of a 64 complex symbol string in about 32 to 64 μS.

In FIG. 3, the transmitter comprises, as shown in FIG. 1, a symbol string transforming means 1, a Fourier transforming means 2, a spreading means 3, an inverse Fourier transforming means 4 and a modulating means 5. To the symbol string conversion means 1, complex symbol strings SIS (m) of a plurality of m (m is an integer) subscribers are respectively inputted from a digital signal input means (not shown).

The symbol string converting means 1 is composed of a shift circuit 11 and a counter 12 shown in FIG.
Further, the diffusion means 3 is the shift circuit 1 shown in FIG.
1 and a well-known random sequence generator 13. The shift circuit 11 shown in FIG. 7A is realized by a selector circuit. However, in FIG.
Input data type SIS (n) is n = 4,
Each data is 4-bit parallel data, and the input data is shifted by 3 at the maximum and output.

That is, the shift circuit 11 is composed of four selectors 11a, 11b, 11c and 11d, and the data SIS inputted to the input terminals a, b, c and d, respectively.
(N) indicates selectors 11a, 11b, 11c, and 11d according to shift data input to the shift terminals S1 and S2.
Are output to the output terminals a, b, c and d respectively. Therefore, the input data is the shift terminals S1 and S2.
The shift circuit 11 shifts the selectors 11a to 11b and 11b to 11c according to the shift data input to
To 11d and 11d to 11a, respectively.

The counter 12 cyclically outputs a value of 0 to 3, and the output is added to the shift terminals S1 and S2 of the shift circuit 11. That is, the complex symbol sequence SIS (m) is regularly shifted in a fixed direction. The speed of such shift is synchronized with the number of one complex symbol as described later.

A plurality of Fourier transform means 2 (DFT
0, DFT1, DFT2, DFT3), and is provided for each output of the symbol string conversion means 1. Then, each Fourier transforming unit is adapted to perform Fourier transform on a complex symbol sequence in which the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence. In FIG. 3, the number of inverse Fourier transforming means 4 is four, and the number of complex symbols to be Fourier transformed is four, as will be described later with reference to FIG.

The random sequence generator 13 provided in the spreading means 3 is a well-known pseudo random number generator, and generates random numbers 0 to 3 at the same speed as the counter 12. The output is applied to the shift terminals S1 and S2 of the shift circuit 11 in the random sequence generator 13. That is, as will be described later, the random sequence generator 13 is configured such that the k complex number sequence group 1 and the 1 complex number sequence group n complex number sequence F (k,
n) is replaced for each complex number sequence, and random number 0 to 3 generated by the random sequence generator 13 is used to irregularly switch k complex number sequence groups F (± p, n) in a certain direction. do. The random sequence generator 13
Generates random numbers synchronized with the random sequence generator 13 in the receiver described later at the same speed in the transmitter and the receiver by a known method.

A plurality of inverse Fourier transform means 4 (IDF
T0, IDFT1, IDFT2, IDFT3), and provided for each output of the spreading means 3. Then, the same number of complex number sequences as the number of complex symbol sequences processed by the Fourier transform means is inversely transformed. In FIG. 3, the number of the inverse Fourier transforming means 4 is four, and the complex number sequence subjected to the inverse Fourier transform by the inverse Fourier transforming means 4 is, for example, 4, as will be described later with reference to FIG.

The complex symbol sequence transformed into the time domain by the inverse Fourier transforming means 4 is inputted to the modulating means 5. The modulation means 5 is a multi-carrier modulator having a plurality of well-known quadrature modulators (QAM) having different modulation frequencies, for example, f0, f1, f2 and f3. The inverse Fourier transform means 4 (IDFT
0, IDFT1, IDFT2, IDFT3), the complex symbol sequence t (m, n) is input to an input terminal (not shown) corresponding to each frequency of the modulation means 5, and each frequency f0, f1, f2 is input. , F3 modulated signal is transmitted as a signal SOS (m) from an antenna (not shown).

In FIG. 4, the receiver is, as shown in FIG. 2, a demodulating means 6, a Fourier transforming means 2, a spreading means 7,
The inverse Fourier transform unit 4 and the symbol string transform unit 8 are included. The symbol string converting means 1 is composed of a well-known shift circuit 11 and a counter 12 as shown in FIG. The spreading means 3 comprises a well-known shift circuit 11 as shown in FIG. 7A and a random sequence generator 1.
It is composed of three.

The complex symbol sequence t (m, n) modulated by the modulator 5 of the transmitter and transmitted as the signal SOS (m) from the antenna (not shown) is received by the antenna (not shown) of the receiver. Then, the signal SIR is sent to the demodulation means 6.
It is input as (m). The demodulation means 6 has different demodulation frequencies, for example, f0, f1, f2 and f3.
This is a multi-carrier demodulator provided with a plurality of well-known quadrature demodulators (QADM). The signals demodulated by the demodulating means 6 for each of the frequencies f0, f1, f2, and f3 are input to the Fourier transforming means 2 as a complex symbol sequence t (m, n).

The Fourier transform means 2 is the same as the Fourier transform means 2 in the transmitter. Each Fourier transform means has a plurality of (DFT0, DFT1, DFT2, DFT
3) Each frequency f0, f1, of the demodulation means 6 is provided.
The signals demodulated for each of f2 and f3 are respectively Fourier transform means DFT0, DFT1, D of the Fourier transform means 2.
The complex symbol sequence t (m, n) is input to FT2 and DFT3.

Then, each Fourier transform means performs the Fourier transform of the complex symbol sequence in which the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence as in FIG. Has become. In FIG. 4, the number of Fourier transform means 2 is four, and the number of complex symbols to be Fourier transformed is, as will be described later with reference to FIG.
For example, it is 4.

The output of the Fourier transform means 2 is the diffusion means 7
Entered in. The spreading means 7 is composed of a shift circuit 71 shown in FIG. 7B and a well-known random sequence generator 13. The shift circuit 71 shown in FIG.
Are realized by the selector circuit. However, FIG.
In (b), the input data type SIR (n) is set to n.
= 4, each data is 4-bit parallel data, and the input data is output after being shifted by a maximum of 3.

The shift circuit 71 includes four selectors 11
a, 11b, 11c, and 11d, input data input to the input terminals e, f, g, and h corresponding to the shift data input to the shift terminals S1 and S2 is input to the selectors 11a to 11d and 11b. To 11a, from 11c to 11b, and from 11d to 11c, respectively, and output to the output terminals E, H, G, and H. That is, FIG. 7 (a)
The shift direction of the shift circuit 11 in FIG. 7 and the shift direction of the shift circuit 71 in FIG. 7B are opposite to each other. Random sequence generator 13 in the spreading means 7
Are the same as those shown in FIG. 3, and description thereof will be omitted.

The output of the diffusing means 7 is input to the inverse Fourier transforming means 4. Since the inverse Fourier transforming means 4 concerned performs the same operation as the inverse Fourier transforming means 4 described in FIG. 3, its explanation is omitted. Then, the output of the inverse Fourier transform unit 4 is input to the symbol string transform unit 8. The symbol string converting means 8 is composed of the shift circuit 71 and the counter 12 shown in FIG. The operation is the same as that of the symbol string converting means 1 described in FIG.
However, the shift circuit 71 has a data shift direction opposite to that of the shift circuit 1, as shown in FIG. Therefore, the rearranged complex symbol sequence returns to the same order as the data transmitted by the transmitter, the transmission data is reproduced, and the complex symbol sequence T is output to the output terminals of the shift circuit 71. (M, n) are output as n signals SOR (n), respectively.

The Fourier transform means and the inverse Fourier transform means do not have to have the same number of outputs of the symbol transforming means or the spreading means as the number of outputs of the symbol transforming means or the spreading means, depending on the performance of the hardware used for each. In that case, it may be configured and used for time-division processing.

5 and 6 are diagrams for explaining the operation of the transmitter and the receiver described in FIGS. 3 and 4, wherein FIG. 5 is an explanatory diagram of the operation of the transmitter and FIG. 6 is an explanatory diagram of the operation of the receiver. Is. FIG. 8 is a time chart explaining the operations of FIGS. 5 and 6. The operation will be described below with reference to the drawings. In addition, FIG.
In the explanation of FIG. 6, the Fourier transform means 2 and the inverse Fourier transform means 4 are provided with memories (not shown) necessary for storing the input data and the output data as necessary. It will be described as being controlled respectively by a microprocessor or a Fourier transform means 2 and an inverse Fourier transform means 4 which are not provided.

First, the operation of the transmitter will be described with reference to FIG. In FIG. 5, FIG. 5A shows a symbol string converting means 1.
5 (b) is a complex symbol sequence input to the Fourier transform means 2, FIG. 5 (c) is a complex number sequence input to the spreading means 3, and FIG. 5 (d) is an inverse Fourier sequence. FIG. 5E is a diagram for explaining the complex number sequence input to the conversion unit 4, and FIG. 5E is a diagram for explaining the complex symbol sequence input to the modulation unit 5. Hereinafter, for the sake of simplification of description, the directions of the complex symbol sequence and complex number sequence of the same subscriber will be referred to as rows, and the same time direction will be referred to as columns.

In FIG. 5, the type of complex symbol sequence (that is, the number of subscribers) m transmitted by the transmitter is 4, the number of complex symbol sequences (that is, the number of Fourier transform symbols) n is 4, and each complex symbol at each time The columns are represented by Tmn.

The complex symbol sequence input to the symbol sequence conversion means 1 has the subscriber number m in the row direction and the time tt in the column direction.
When j (j is an integer) is taken, it becomes as shown in FIG. That is, the complex symbol sequence of the subscriber A is time tt0, t
At t1, tt2, and tt3, the symbol string conversion means 1
The complex symbol string T is connected to the first terminal (not shown) of
It is input as 00, T01, T02, T03. In the same manner, the subscriber B receives the complex symbol sequences T10, T
11, T12, T13, the subscriber C has complex symbol sequences T20, T21, T22, T23, and the subscriber D has complex symbol sequences T30, T31, T32, T33 at time t.
It is input at t0, tt1, tt2, and tt3, respectively.

The complex symbol sequence input to the symbol sequence conversion means 1 is time tt4, tt5, tt6, tt depending on the value of the counter 12, as shown in FIG.
7 sequentially in the column direction, for example, the direction S in FIG.
Are rearranged (shifted) from the direction of the line of the subscriber D to the line of the subscriber A. That is, as shown in FIG. 5B, the counter 12 has the time points tt4, tt5, tt.
At 6 and tt7, the value SN changes to 0, 1, 2, 3 and the complex symbol sequence is sequentially shifted in the S direction by the number corresponding to the SN.

As a result, SN = 0 at time tt4.
Therefore, the complex symbol sequence is not rearranged, and the complex symbol sequence in the row of the subscriber A is the subscriber A at the time tt0.
The complex symbol sequence T00 in the row of the subscriber B is the complex symbol sequence T10 in the row of the subscriber B at the time tt0, and the complex symbol sequence T10 in the row of the subscriber C is the subscriber symbol C at the time tt0. Row of complex symbol sequence T20
However, the complex symbol sequence in the row of the subscriber D is the complex symbol sequence T30 in the row of the subscriber D at time tt0,
The respective outputs of the symbol string conversion means 1 in FIG.

Also, at time tt5, SN = 1 and
The complex symbol sequence of the row of the subscriber A is the complex symbol sequence T11 of the row of the subscriber B at time tt1, and the complex symbol sequence of the row of the subscriber B is the complex symbol sequence T21 of the row of subscriber C at time tt1. The complex symbol sequence of the row of the subscriber C is the complex symbol sequence T of the row of the subscriber D at time tt1.
31 and the complex symbol sequence of the row of the subscriber D are respectively rearranged with the complex symbol sequence T01 of the row of the subscriber A at time tt1 and become the respective outputs of the symbol sequence conversion means 1 at time tt5.

Similarly, at time tt6, SN = 2
Thus, the complex symbol sequence in the row of the subscriber A is the complex symbol sequence T22 in the row of the subscriber C at time tt2, and the complex symbol sequence in the row of the subscriber B is the subscriber D at time tt2.
The complex symbol sequence T32 of the row of the subscriber C, the complex symbol sequence of the row of the subscriber C is the complex symbol sequence T02 of the row of the subscriber A at time tt2, and the complex symbol sequence of the row of the subscriber D is subscriber B at the time tt2. Row of complex symbol sequence T12
Are rearranged and become the respective outputs of the symbol string conversion means 1 at time tt6.

Further, at time tt7, SN = 3, the complex symbol sequence of the row of subscriber A is the complex symbol sequence T33 of the row of subscriber D and the complex symbol sequence of the row of subscriber B is time tt3 at time tt3. , The complex symbol sequence T03 of the row of the subscriber A, the complex symbol sequence of the row of the subscriber C is the complex symbol sequence T13 of the row of the subscriber B at the time tt3, and the complex symbol sequence of the row of the subscriber D is the time tt.
3 and the complex symbol column T23 in the row of the subscriber C in FIG. 3 are respectively rearranged and become the respective outputs of the symbol column conversion means 1 at time tt7.

The complex symbol sequence sequentially shifted in the S direction at each time by the symbol sequence converting means 1 is input to the Fourier transforming means 2 and at the time tf1, the Fourier transforming means 2 is inputted.
Fourier transformed by. That is, the row-direction complex symbol sequence rearranged as shown in FIG. 5B is used to be Fourier transformed by the Fourier transform means 2 as follows.

In the Fourier transform means 2, the complex symbol sequence T00, T11, T22, corresponding to the row of the subscriber A,
T33 uses DFT0, and the complex symbol strings T10, T21, T32, and T03 corresponding to the row of the subscriber B are DFT.
1 is used to represent the complex symbol sequence T corresponding to the row of the subscriber C.
20, T31, T02, and T13 use DFT2 to generate complex symbol sequences T30, T01, and T3 corresponding to the row of the subscriber D.
Fourier transform is performed on each of T12 and T23 using DFT3.

As a result, for example, in the output of DFT3,
Complex symbol sequence T30, T0 represented in the time domain
A complex number sequence F30, F01, F12, F23 represented in the frequency domain obtained by Fourier transforming 1, T12, T23 is obtained. Similarly, the results shown in FIG. 5C are obtained for DFT0, DFT1, and DFT2, respectively. Here, Fkn in FIG. 5C corresponds to the Fourier transform result of Tmn. However, k, m, and n are integers, and k = m in FIG.

Next, the Fourier transform unit 2 (DFT0, D
The output of FT1, DFT2, DFT3) is the spreading means 3
, Respectively. As shown in FIG. 7A, the complex number sequence input to the spreading unit 3 is time tt8, tt9, tt1 depending on the value of the random sequence generator 13.
At 0 and tt11 at random, in the column direction, for example,
The direction is changed (shifted) to the direction indicated by the direction S in FIG. 5D (the direction from the row of the subscriber D to the row of the subscriber A).
That is, as shown in FIG. 5D, the random sequence generator 1
At time tt8, tt9, tt10, and tt11, the value RN3 changes to 0, 2, 3, 1, for example.
In such a case, the complex sequence is converted by the shift circuit 11 into
It is shifted in the S direction by a number corresponding to the RN.

As a result, at time tt8, since RN = 0, the complex sequence is not replaced, and the subscribers A, B,
Complex rows F00, F10, F20, F30 in rows C, D
Are output respectively.

Also, at time tt9, RN = 2,
In the rows of the subscribers A, B, C, D, the complex sequence F31, F01,
F11 and F21 are output respectively.

Similarly, at time tt10, RN =
3 and the complex sequence F1 in the rows of the subscribers A, B, C, D
2, F22, F32 and F02 are output respectively.

Further, at time tt11, RN = 1, and the complex number sequence F03, F1 in the rows of the subscribers A, B, C, D.
3, F23 and F33 are output respectively.

Complex number sequence Fkn obtained as described above
Is an inverse Fourier transform means 4 (IDFT0, IDFT1,
IDFT2 and IDFT3) are respectively input as follows and are subjected to inverse Fourier transform at time tif1. That is, the complex number sequence F00, F31, of the row corresponding to the subscriber A,
F12 and F03 are IDFT0, and complex number sequences F10, F01, F22, and F13 of the row corresponding to the subscriber B are IDFT.
1, the complex number sequence F20, F1 of the row corresponding to the subscriber C
1, F32, F23 are IDFT2, and complex number sequences F30, F21, F02, F33 in the row corresponding to the subscriber D are IDs.
Input to FT3 respectively.

The complex number sequence input as described above is used as the inverse Fourier transform means IDFT0, IDFT1, IDFT.
2. Inverse Fourier transform is performed by the IDFT 3 by a known method. As a result, for example, the complex number sequence F00, F31, F12, F0 represented in the frequency domain is output to the output of IDFT0.
3 is inverse Fourier transformed and the complex symbol sequence tt00, tt31, tt12, tt03 represented in the time domain.
Is obtained. Similarly, IDFT1, IDFT2, I
In DFT3, corresponding to the rows of subscribers A, B, C, D,
The results as shown in FIG. 5E are obtained respectively. here,
Tmn in FIG. 5E corresponds to the inverse Fourier transform result of Fkn. However, k, m, and n are integers, and
In (e), k = m.

The complex symbol sequence transformed into the time domain by the inverse Fourier transforming means 4 is inputted to the modulating means 5. The modulation means 5 is a multi-carrier modulator having a plurality of well-known quadrature modulators (QAM) having different modulation frequencies, for example, f0, f1, f2 and f3. The inverse Fourier transform means 4 (IDFT
0, IDFT1, IDFT2, IDFT3), a complex symbol sequence tmn is input to an input terminal (not shown) corresponding to each frequency of the modulation means 5 and modulated at each frequency f0, f1, f2, f3. Signal from the antenna (not shown) as signal SOS (m) at time t
It is transmitted to mo, tm1, tm2, and tm3, respectively.

That is, the complex symbol sequence t00, t31, t
12, t03 is the frequency f0, and the complex symbol sequence t10,
t01, t22, and t13 have a frequency f1, the complex symbol sequences t20, t11, t32, and t23 have a frequency f2, and the complex symbol sequences t30, t21, t02, and t33 have a frequency f3, respectively, at times tmo, tm1, tm2, and tm3.
Sent to.

Next, the operation of the receiver will be described. 6, FIG. 6A shows a complex symbol sequence input to the Fourier transforming means 2, FIG. 6B shows a complex number sequence input to the spreading means 7, and FIG. 6C shows an inverse Fourier transforming means 4. FIG. 6D is a diagram for explaining an input complex number sequence, FIG. 6D is a diagram for explaining a complex symbol sequence input to the symbol sequence conversion unit 8, and FIG. 6E is a diagram for explaining an output of the symbol sequence conversion unit 8.

In FIG. 6, the type of complex symbol sequence (that is, the number of subscribers) m received by the receiver is 4, the number of complex symbol sequences (that is, the number of Fourier transform symbols) n is 4, and each complex symbol at each time The columns are represented by Tmn.

The complex symbol string tmn modulated by the modulator 5 of the transmitter and transmitted as the signal SOS (m) from the antenna (not shown) is received by the antenna (not shown) of the receiver and demodulated by the demodulator 6 Signal SIR (m). The demodulation means 6 has different demodulation frequencies, for example, f0, f1, f of the same frequency as the transmitter.
A plurality of well-known quadrature demodulators (QADM) of 2, f3,
It is a multi-carrier demodulator provided. The signals demodulated for each frequency f0, f1, f2, f3 by the demodulating means 6 are input to the Fourier transforming means 2 as a complex symbol sequence tmn.

The Fourier transform means 2 is the same as the Fourier transform means 2 in the transmitter. Each Fourier transform means has a plurality of (DFT0, DFT1, DFT2, DFT
3) Each frequency f0, f1, of the demodulation means 6 is provided.
The signals demodulated for each of f2 and f3 are respectively Fourier transform means DFT0, DFT1, D of the Fourier transform means 2.
The complex symbol sequence tmn is input to FT2 and DFT3.

The complex symbol sequence tmn input to the Fourier transform means 2 is as shown in FIG. 6 (a), where m is the number of subscribers in the row direction and time ttj (j is an integer) in the column direction. 5 (e). That is, Fourier transform means DF
Times tt16, tt17, tt18, tt19 at T0
In the complex symbol sequence t00, t31, t12, t0
3 is input. Hereinafter, similarly, the times tt16 and tt
At 17, tt18, and tt19, complex symbol sequences t10, t01, t22, and t13 are included in the DFT1
2 is a complex symbol sequence t20, t11, t32, t23.
However, the DFT3 has complex symbol sequences t30, t21, t0.
2, and t33 are respectively input, and are Fourier-transformed by the Fourier transforming means 2 at time tf2.
That is, each complex symbol string in the row direction of FIG. 6A is Fourier transformed by the Fourier transforming means 2 as follows.

In the Fourier transform means 2, the complex symbol sequences t00, t31, t12, corresponding to the row of the subscriber A,
The DFT0 is used for t03, and the complex symbol sequences t10, t01, t22, and t13 corresponding to the row of the subscriber B are DFT.
1 is used to represent the complex symbol sequence t corresponding to the row of the subscriber C.
20, t11, t32, and t23 use the DFT2 and the complex symbol sequence t30, t21, and t3 corresponding to the row of the subscriber D.
Fourier transform is performed on each of t02 and t33 using DFT3.

As a result, for example, in the output of DFT3,
Complex symbol sequence t30, t2 represented in the time domain
A complex number sequence F30, F21, F02, F33 represented in the frequency domain is obtained by Fourier transforming 1, t02, t33. Similarly, the results shown in FIG. 6B are obtained for DFT0, DFT1, and DFT2, respectively. Here, Fkn in FIG. 6B corresponds to the Fourier transform result of tmn. However, k, m, and n are integers, and k = m in FIG.

Next, the Fourier transform means 2 (DFT0, D
The output of FT1, DFT2, DFT3) is the spreading means 7
, Respectively. As shown in FIG. 7B, the complex sequence input to the spreading means 7 is time tt20, tt21, t depending on the value of the random sequence generator 13.
At t22 and tt23, they are randomly switched (shifted) in the column direction, for example, in the direction indicated by the direction R in FIG. 6C (from the row of the subscriber A to the row of the subscriber D). That is, as shown in FIG. 6C, from the random sequence generator 13, the times tt20, tt21, tt22,
At tt23, a value RN similar to the random number of the random sequence generator 13 at the transmitter, for example 0, 2, 3, 1 is generated. In such a case, the complex number sequence is switched (shifted) in the R direction by the shift circuit 11 by the number corresponding to the RN.

As a result, at time tt20, RN =
Since it is 0, the complex sequence is not replaced and the subscriber A,
Complex rows F00, F10, F20, F in rows B, C, D
30 are output respectively.

Also, at time tt21, RN = 2, and the complex number sequences F11, F2 in the rows of the subscribers A, B, C, D.
1, F31, F01 are output respectively.

Similarly, at time tt22, RN =
3 and the complex number sequence F2 in the rows of the subscribers A, B, C and D.
2, F32, F02 and F12 are output respectively.

Further, at time tt23, RN = 1, and the complex number sequences F33 and F0 in the rows of the subscribers A, B, C and D.
3, F13, F23 are output respectively.

Complex number sequence Fkn obtained as described above
Is an inverse Fourier transform means 4 (IDFT0, IDFT1,
IDFT2 and IDFT3) are input as follows, and inverse Fourier transform is performed at time tif2. That is, the complex number sequence F00, F11, in the row corresponding to the subscriber A,
F22 and F33 are IDFT0, and complex number sequences F10, F21, F32 and F03 of the row corresponding to the subscriber B are IDFT0.
1, the complex sequence F20, F3 of the row corresponding to the subscriber C
1, F02, F13 are IDFT2, and complex number sequences F30, F01, F12, F23 in the row corresponding to the subscriber D are IDs.
Input to FT3 respectively.

The complex number sequence input as described above is used as the inverse Fourier transform means IDFT0, IDFT1, IDFT.
2. Inverse Fourier transform is performed by the IDFT 3 by a known method. As a result, for example, the complex number sequence F00, F11, F22, F3 represented in the frequency domain is output to the output of IDFT0.
3 is inverse Fourier transformed to obtain complex symbol sequences T00, T11, T22, T33 represented in the time domain. Similarly, IDFT1, IDFT2, IDFT3
6D corresponding to the rows of the subscribers A, B, C and D, respectively. Here, FIG.
Tmn in (d) corresponds to the inverse Fourier transform result of Fkn. However, k, m, and n are integers, and FIG.
In (d), k = m.

Inverse Fourier transform means 4 (IDFT0, IDFT
The complex symbol sequence Tmn obtained by FT1, IDFT2, IDFT3) is as shown in FIG. 6 (d) when the subscriber number m is taken in the row direction and the time ttj (j is an integer) in the column direction, It is input to each of the symbol string conversion means 8. That is, the complex symbol sequence T00, T11, T2 of the subscriber A
2, T33 is input to the terminal e in FIG. Less than,
Similarly, the complex symbol sequence T10, T21,
7A and 7B show the complex symbol sequences T20, T31, T02, and T13 of the subscriber C in the terminal f of FIG. 7B.
At terminal g in (b), the complex symbol string T30 of the subscriber D,
T01, T12, and T23 are input to the terminal h of FIG.

The complex symbol sequence Tmn input to the symbol sequence conversion means 8 is time tt24, tt25, t depending on the value of the counter 12, as shown in FIG. 7B.
At t26 and tt27, for example, in FIG.
The direction indicated by the direction R in (d) (from the line of the subscriber A to the subscriber D
The row direction). That is, as shown in FIG. 6 (e), the counter 12 has the time points tt24, tt25, t
At t26 and tt27, the value SN is 0, 1, 2,
3, the complex symbol sequence Tmn is sequentially rearranged (shifted) in the R direction by the number corresponding to the SN.

As a result, at time tt24, SN =
Since it is 0, the complex symbol sequence Tmn is not rearranged, and the complex symbol sequence T0 is arranged in the rows of the subscribers A, B, C and D.
0, T10, T20, T30 are output respectively.

At time tt25, SN = 1 and the complex symbol string T0 is set in the rows of the subscribers A, B, C, and D.
1, T11, T21, T31 are output respectively.

Similarly, at time tt26, SN =
2, the complex symbol columns T02, T12, T22, and T32 are output to the rows of the subscribers A, B, C, and D, respectively.

Further, at time tt27, SN = 3, and the complex symbol string T0 is set in the rows of the subscribers A, B, C, and D.
3, T13, T23, T33 are output respectively.

The complex symbol sequence Tmn output to the output terminal of the symbol sequence conversion means 8 is the subscriber A, B, C,
Corresponding to D, the order is the same as that of the complex symbol sequence shown in FIG. 5A input to the symbol sequence conversion means 1 of the transmitter.

FIGS. 9 to 11 and FIGS. 14 and 15 are diagrams in which the effects of the embodiment of the present invention are obtained by computer simulation. Each drawing will be described below. In each figure, the vertical axis represents the bit error rate BER, and the horizontal axis represents the ratio DUR of the desired wave power and the undesired wave power. The error rate with respect to the interference signal ideally has a Gaussian noise characteristic, and the Gaussian noise characteristic is indicated by a symbol GN in each drawing. The digital modulation is based on 16QAM, and the transmission data and the reception data of the complex symbol sequence are obtained as 4-bit parallel data.

FIG. 9 shows how the BER is affected by the number of interfering subscribers when the number of subscribers is 16, and the number of complex symbols of Fourier transform is 16. Are the symbols W3, W4, W5, W6 of the present invention.
Are results obtained by the conventional frequency hopping shown in FIGS. 17 and 18. The number of interfering subscribers of the present invention is 1 to 1
6, the number of interfering subscribers of conventional frequency hopping is W
Corresponding to 3, W4, W5, W6, 3, 4,
This is the case of 1 and 2. As is apparent from FIG. 9, in the embodiment of the present invention, it is possible to obtain a characteristic almost equal to the Gaussian noise characteristic GN even if the number of interfering subscribers increases (even if the noise component increases).

FIG. 10 is a diagram in which the effects of the symbol sequence conversion means 1 and the symbol sequence conversion means 8 are obtained when the number of interfering subscribers is 1, the number of subscribers is 16, and the number of complex symbols of Fourier transform is 16. Is. That is, the figure shows how the BER is affected when the data exchange is performed only by the diffusion means 3 without the symbol row conversion means 1 and the symbol row conversion means 8.

The effect of the symbol string converting means 1 and the symbol string converting means 8 is that even if the complex symbols are regularly rearranged in a certain direction by the means, even for a subscriber channel without a complex symbol, Complex symbols are assigned. As a result, all subscribers are always assigned a complex symbol, and the Fourier transform means and the inverse Fourier transform means do not convert the complex symbol data to zero, so that the effect of the spreading means 3 in the frequency domain is made uniform. You can

In FIG. 10, the code W7 is the result when the symbol string converting means is not provided, and the code W1 is the result of the embodiment of the present invention. As is apparent from FIG. 10, by regularly rearranging the complex symbols in a certain direction, the influence in the frequency domain in the spreading means 3 becomes uniform,
The distribution of interference is asymptotic to the Gaussian noise distribution characteristic.

In FIG. 11, the number of interfering subscribers is 1, the number of complex symbol sequences and the number of complex symbol sequences are the same as the number of subscribers.
FIG. 7 is a diagram in which BER is influenced by the number of subscribers as (symbol string conversion means and spreading means is a square matrix), and reference numerals W8, W9, and W10 indicate the numbers of subscribers are 16, respectively. The results are 8 and 4. The increase in the number of subscribers facilitates the establishment of the central limit theorem in the frequency domain, and the interference distribution is asymptotic to the Gaussian noise distribution characteristic. From FIG. 11, when the number of subscribers is 16 or more, the Gaussian noise distribution characteristic is almost equal.

As is apparent from FIG. 11, in addition to increasing the number of subscribers so that the central limit theorem holds in the frequency domain, the number of symbols (the number of complex symbol sequences) at the time of Fourier transform is also increased. good. 12 is a diagram for explaining the operation of the transmitter, and FIG. 13 is a diagram for explaining the operation of the receiver, which are diagrams corresponding to FIGS. 5 and 6, respectively.

12 and 13 will be described below.
The description of the same parts as those in FIGS. 5 and 6 is omitted. In FIG. 12, the kind (that is, the number of subscribers) m of the complex symbol string transmitted by the transmitter is 4, the number (that is, the number of Fourier transform symbols) n of the complex symbol string is 6, and each time
Each complex symbol sequence in is represented by Tmn. Further, the counter 12 regularly generates a value of 0 to 3, which is a number necessary for rearranging all the subscribers. The random sequence generator 13 randomly generates a value of 0 to 3, which is the number required to replace all subscribers.

First, the operation of the transmitter will be described with reference to FIG. Similarly to FIG. 5, the complex symbol sequence input to the symbol sequence conversion means 1 is as shown in FIG. 12A when the subscriber number m is taken in the row direction and the time ttj (j is an integer) is taken in the column direction. become. The complex symbol sequence input to the symbol sequence converting means 1 is the counter 1 as shown in FIG.
Depending on the value of 2, the times tt6, tt7, tt8, tt
At 9, tt10, and tt11, they are sequentially rearranged (shifted) in the column direction, for example, in the direction indicated by the direction S in FIG. 12B (from the row of the subscriber D to the row of the subscriber A).

As a result, the symbol string converting means 1 sequentially rearranges (shifts) in the S direction at each time.
The complex symbol string is as shown in FIG. That is, each complex symbol sequence rearranged one row at a time in the column direction until time tt6, tt7, and tt8 returns to four rows at time tt9, that is, the rearrangement returns to zero. Therefore, at the time tt9, the value of the counter 12 is 0. Then, after time tt9, the rearrangement is performed again one by one in the column direction.

Each complex symbol sequence rearranged as shown in FIG. 12B is input to the Fourier transform means 2 and Fourier transformed by the Fourier transform means 2. Then, for example, the output of the DFT3 is the complex symbol sequence T30, T01, T12, T23, T3 represented in the time domain.
4, complex number sequence F30, F01, F12, F23, F31, F0 represented in the frequency domain obtained by Fourier transforming T05
5 is obtained. Similarly, DFT0, DFT1, DF
The results shown in FIG. 12C are obtained at T2. Here, Fkn in FIG. 12C corresponds to the Fourier transform result of Tmn. However, k, m, and n are integers, and k = m in FIG.

Next, the Fourier transform means 2 (DFT0, D
The output of FT1, DFT2, DFT3) is the spreading means 3
, Respectively. As shown in FIG. 7A, the complex sequence input to the spreading means 3 is time tt12, tt13, t depending on the value of the random sequence generator 13.
At t14, tt15, tt16, and tt17, they are randomly switched in the column direction, for example, in the direction indicated by the direction S in FIG. 12D (from the row of the subscriber D to the row of the subscriber A) (shifted). ). That is, as shown in FIG. 12D, the random sequence generator 13 is
At t13, tt14, tt15, tt16, and tt17, for example, values RN of 0, 2, 3, 1, 1, 3 are generated. In such a case, the complex sequence is generated by the shift circuit 11.
The numbers are switched (shifted) in the S direction by the number corresponding to the RN.

As a result, FIG. 1 obtained as described above
The complex number sequence Fkn shown in 2 (d) is the inverse Fourier transform means 4 (IDFT0, IDFT1, IDFT2, IDFT).
3), which are respectively input to and subjected to inverse Fourier transform. The complex number sequence input as described above is inverse Fourier transformed by each inverse Fourier transforming means IDFT0, IDFT1, IDFT2 and IDFT3 by a known method. As a result, for example, the output of IDFT0 has complex number sequences F00, F31, F12, F03, F14, F0 represented in the frequency domain.
5 is inverse Fourier transformed and the complex symbol sequence tt00, tt31, tt12, tt0 represented in the time domain.
3, tt14, tt05 are obtained. Similarly, ID
FT1, IDFT2, and IDFT3 have subscribers A, B, and
The results shown in FIG. 12E are obtained for the rows C and D, respectively. Here, tmn in FIG.
Corresponds to the inverse Fourier transform result of Fkn. However, k, m, and n are integers, and k = m in FIG.

The complex symbol sequence transformed into the time domain by the inverse Fourier transforming means 4 is inputted to the modulating means 5. The modulation means 5 is a multi-carrier modulator having a plurality of well-known quadrature modulators (QAM) having different modulation frequencies, for example, f0, f1, f2 and f3. The inverse Fourier transform means 4 (IDFT
0, IDFT1, IDFT2, IDFT3), a complex symbol string tmn is input to an input terminal (not shown) corresponding to each frequency of the modulation means 5 and modulated at each frequency f0, f1, f2, f3. Signal from the antenna (not shown) as signal SOS (m) at time t
in mg (g is 0 to 5), respectively.

That is, the complex symbol sequence t00, t31, t
12, t03, t14, and t05 have the frequency f0 and the complex symbol sequences t10, t01, t22, t13, t24, and t.
15 is a frequency f1 and is a complex symbol sequence t20, t11,
At t32, t23, t34, and t25, the frequency is f2, and the complex symbol sequences t30, t21, t02, t33, t04,
At t35, the frequency f3 is transmitted.

Next, the operation of the receiver will be described with reference to FIG. In FIG. 13, the type of the complex symbol sequence (that is, the number of subscribers) m received by the receiver is 4, the number of complex symbol sequences (that is, the number of Fourier transform symbols) n is 6, and each complex symbol sequence at each time is Tmn. It is represented by.

The complex symbol string tmn modulated by the modulation means 5 of the transmitter and transmitted as a signal SOS (m) from an antenna (not shown) has frequencies f0, f1 and f.
The signal demodulated every 2 and f3 is input to the Fourier transform means 2 as a complex symbol sequence tmn.

The Fourier transform means 2 is the same as the Fourier transform means 2 in the transmitter. Each Fourier transform means has a plurality of (DFT0, DFT1, DFT2, DFT
3) Each frequency f0, f1, of the demodulation means 6 is provided.
The signals demodulated for each of f2 and f3 are respectively Fourier transform means DFT0, DFT1, D of the Fourier transform means 2.
The complex symbol sequence tmn is input to FT2 and DFT3.

The complex symbol sequence tmn input to the Fourier transform means 2 is as shown in FIG. 13 (a), where m is the number of subscribers in the row direction and time ttj (j is an integer) in the column direction. 12 (e). That is, the Fourier transform means DFT0 has times tt18, tt19, tt20, tt.
21, 21, tt22, and tt23, the complex symbol sequence t0
It is input as 0, t31, t12, t03, t14, and t05.

Thereafter, similarly, at times tt18 and tt1.
At 9, tt20, tt21, tt22, and tt23, the DFT1 includes complex symbol sequences t10, t01, and t2.
2, t13, t24, t15, but the DFT2 has complex symbol sequences t20, t11, t32, t23, t34, t2.
5, the DFT3 has complex symbol sequences t30, t21, t
02, t33, t04, and t35 are input, respectively, and are Fourier-transformed by the Fourier transform means 2, respectively, and the results as shown in FIG. 13B are obtained. Here, Fkn in FIG. 13B corresponds to the Fourier transform result of tmn. However, k, m, and n are integers, and k = m in FIG.

Fourier transform means 2 (DFT0, DF
The output of (T1, DFT2, DFT3)
Each is entered. As shown in FIG. 7B, the complex sequence input to the spreading means 7 is time tt24, tt25, tt2 depending on the value of the random sequence generator 13.
At 6, tt27, tt28, and tt29, they are randomly switched in the column direction, for example, in the direction indicated by the direction R in FIG. 13C (from the row of the subscriber A to the row of the subscriber D). ). That is, as shown in FIG. 13C, the random sequence generator 13 is
At 25, tt26, tt27, tt28, and tt29, the same value RN as the random number of the random sequence generator 13 in the transmitter, for example, 0, 2, 3, 1, 1, 3 is generated. In such a case, the complex sequence is generated by the shift circuit 11.
The numbers are switched (shifted) in the R direction by the number corresponding to the RN. As a result, the output of the diffusion means 7 at each time is as shown in FIG.

Complex number sequence Fkn obtained as described above
Is an inverse Fourier transform means 4 (IDFT0, IDFT1,
IDFT2 and IDFT3) are input as follows and inverse Fourier transformed. That is, the complex number sequence F00, F11, F22, F3 of the row corresponding to the subscriber A
3, F04, F15 are IDFT0, and the complex number sequence F10, F21, F32, F03, F1 of the row corresponding to the subscriber B.
4, F25 are IDFT1 and complex number sequences F20, F31, F02, F13, F24, F3 of the rows corresponding to the subscriber C.
5 is the IDFT2, the complex sequence F of the row corresponding to the subscriber D
30, F01, F12, F23, F34, F05 are ID
Input to FT3 respectively.

The complex number sequence input as described above is used as the inverse Fourier transform means IDFT0, IDFT1, IDFT.
2. Inverse Fourier transform is performed by the IDFT 3 by a known method. As a result, for example, the complex number sequence F00, F11, F22, F3 represented in the frequency domain is output to the output of IDFT0.
3, F04, F15 are inverse Fourier transformed to represent complex symbol sequences T00, T11, T22,
T33, T04 and T15 are obtained. Similarly, ID
FT1, IDFT2, and IDFT3 have subscribers A, B, and
The results shown in FIG. 13D are obtained for the rows C and D, respectively. Here, Tmn in FIG.
Corresponds to the inverse Fourier transform result of Fkn. However, k, m, and n are integers, and k = m in FIG.

Inverse Fourier transform means 4 (IDFT0, IDFT
The complex symbol sequence Tmn obtained by FT1, IDFT2, IDFT3) is as shown in FIG. 13 (d) when the subscriber number m is taken in the row direction and the time ttj (j is an integer) in the column direction, It is input to each of the symbol string conversion means 8.
That is, the complex symbol sequence T00, T11, T2 of the subscriber A
2, T33, T04, and T15 are input to the terminal e of FIG. In the same manner, the complex symbol sequences T10, T21, T32, T03, T14 and T25 of the subscriber B are
The terminal f of FIG. 7B is connected to the complex symbol string T2 of the subscriber C.
0, T31, T02, T13, T24 and T35 are shown in FIG.
At terminal g in (b), the complex symbol string T30 of the subscriber D,
FIG. 7B shows T01, T12, T23, T34, and T05.
Is input to each terminal h.

The complex symbol sequence Tmn input to the symbol sequence conversion means 8 is time tt30, tt31, t depending on the value of the counter 12, as shown in FIG. 7B.
At t32, tt33, tt34, and tt35, they are sequentially rearranged (shifted) in the column direction, for example, in the direction indicated by the direction R in FIG. 13D (the direction from the row of the subscriber A to the row of the subscriber D). . That is, as shown in FIG.
The counter 12 displays the times tt30, tt31, tt32,
At tt33, tt34, and tt35, the value SN changes to 0, 1, 2, 3, 0, 1 and the complex symbol sequence Tm
n is sequentially rearranged (shifted) in the R direction by the number corresponding to the SN.

The complex symbol sequence Tmn output to the output terminal of the symbol sequence conversion means 8 is the subscriber A, B, C,
Corresponding to D, the order is the same as that of the complex symbol sequence shown in FIG. 12A input to the symbol sequence conversion means 1 of the transmitter.

FIG. 14 shows how the BER is affected by the number of complex symbol sequences and the number of complex number sequences of the Fourier transform when the number of subscribers is 16 and the number of interfering subscribers is 1. In the figure, the number of complex symbol sequences is the same as the number of complex number sequences of the Fourier transform, and the symbol W11,
W12 and W13 are diagrams for the cases of 16 and 32, 8, and 4, respectively. That is, in the case of the code W11, the number of complex symbols in one complex symbol sequence is equal to or larger than the type of complex symbol sequence. Further, in the case of the symbols W12 and W13, the number of complex symbols in one complex symbol sequence is smaller than the type of complex symbol sequence.

When the number of complex symbols in one complex symbol sequence is smaller than the kind of complex symbol sequence, zero is entered in the complex symbol sequence during Fourier transform, and the complex symbol sequence of such zero is Fourier-transformed. It is converted and the central limit theorem is hard to hold.

Therefore, as is apparent from FIG. 14, in the Fourier transform means and the inverse Fourier transform means, the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence. Fourier transform and inverse Fourier transform are performed on the complex symbol sequence of.

In FIG. 15, similar to FIG. 14, the number of subscribers is 16, the number of interfering subscribers is 1, and the number of complex symbol sequences is 1.
6 is a diagram showing how the BER is affected by the number of complex symbol sequences and the number of complex number sequences of the Fourier transform when the number of complex symbol sequences is 6, and the row and column (complex number sequence group,
It is a figure when changing the number of 1 complex number sequence group n complex number sequences). Reference numerals W17 and W18 indicate the rows and columns of the diffusion means.
It is a figure in case of 16 and 8, respectively.

When the rows and columns of the spreading means are smaller than the rows and columns of the symbol string transforming means, as a result of regular rearrangement, zeros are put in the complex symbol string during Fourier transform, and the complex symbol string of such zero is Fourier-transformed. It is converted and the central limit theorem is hard to hold. Therefore, the type of symbol string conversion means and the number of one complex symbol string are equal to the number of complex number string groups in the spreading means and the number of complex number strings of one complex number string group, respectively.

In FIG. 16, when the number of subscribers is 16, the number of interfering subscribers is 1, and the number of complex symbol sequences and the number of complex number sequences of Fourier transform are 16, the symbol sequence conversion means and the spreading means are arranged. It is a figure which shows the influence with respect to replacement or replacement. The symbol string converting means and the spreading means respectively have a code W.
14 is a case where regular rearrangement and irregular rearrangement are performed, reference numeral W15 is both irregular rearrangement, and reference numeral W16 is irregular rearrangement.

As is clear from FIG. 16, in the case where the irregular permutation in the time domain is indicated by the code W16 in which regular permutation is performed in the frequency domain, the uniformity of the complex symbol sequence in the time domain is Since the central limit theorem in the frequency domain is hard to hold, the characteristic becomes the worst.

Further, in the case shown by the code W15 in which irregular replacement is performed in the time domain and the frequency domain, the uniformity deteriorates in the complex symbol sequence in the time domain, and the characteristic deteriorates. Then, the code W1 is obtained by performing regular rearrangement in the time domain and irregular rearrangement in the frequency domain.
In the case shown in FIG. 4, the homogeneity of the complex symbol sequence in the time domain is improved, and the central limit theorem in the frequency domain is easily established. Therefore, the characteristic is asymptotic to the Gaussian noise distribution GN.

Therefore, the symbol string conversion means for rearranging the complex symbol string performs regular rearrangement, and the spreading means for rearranging the complex number sequence which is the conversion result of the Fourier transform means performs irregular rearrangement.

[0139]

According to the transmitting and receiving device of the first aspect, each of the transmitter and the receiver has a symbol string converting means for rearranging the complex symbol string, and a Fourier transforming means for Fourier transforming the complex symbol string. The transmitter and the receiver may use the hardware having the same function by including the spreading means for exchanging the conversion result of the Fourier transforming means and the inverse Fourier transforming means for inverse Fourier transforming the output of the spreading means. Therefore, the cost of the device can be reduced. Also, by rearranging the complex symbol sequence in the time domain and interchanging the frequency domain complex number sequence, the bit error rate BER can be set to about 0.0001, and error correction by, for example, Reed-Solomon encoding is possible.
Has a property of asymptotically approximating a Gaussian noise distribution using SI,
It is possible to realize a transmission / reception device that is resistant to interference.

According to the transmitting / receiving device of the second, third, sixth and eighth aspects, the symbol string converting means and each of the three means can be realized by a simple shift circuit, which enables downsizing of the device and cost reduction. .

According to the transmitting / receiving device of the fourth aspect, the Fourier transforming means generates the complex symbol sequence in which the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence. Interference characteristics can be improved by performing Fourier transform.

According to the transmitting / receiving device of the fifth and ninth aspects, the device can be speeded up by providing a plurality of Fourier transforming means and inverse Fourier transforming means.

According to the transmitting and receiving apparatus of the seventh aspect, the type m and the number n of one complex symbol sequence in the symbol sequence converting means, the number k of complex number sequence groups in the spreading means,
And the number n of complex number sequences in one complex number sequence group are equal to each other, thereby improving the uniformity of data for each subscriber when frequency hopping is performed by the spreading means. That is, even for a subscriber having no transmission data, when performing the frequency hopping, the data of another subscriber is made to exist, and the conversion of data zero is not performed for the conversion to any subscriber. I was not allowed to. Further, the time-domain signal regularly rearranged by the symbol string conversion means is converted into the frequency domain, and this is irregularly replaced by the spreading means, so that a plurality of symbols of the interfering signal are interfering signals. The central limit theorem is established by interfering with multiple symbols. As a result, the interference characteristics of the transceiver can be significantly improved.

According to the transmitting / receiving device of the tenth and twelfth aspects, the complex symbol sequence is rearranged by using the simple symbol sequence converting means so that the data is reproduced in the same order between the transmitter and the receiver. it can.

According to the transmitter / receiver of the eleventh aspect, the Fourier transform means of the transmitter can improve the interference characteristic by performing the Fourier transform on the plural kinds of complex symbol sequences rearranged by the symbol sequence conversion means. .

According to the transmission / reception system of the thirteenth to seventeenth aspects, the transmitter and the receiver can use the hardware having the same function, which leads to the cost reduction of the device and the complex symbol in the time domain. By rearranging the columns and rearranging the frequency domain complex number sequences, it is possible to realize a transmission / reception system that is asymptotic to the Gaussian noise distribution and is resistant to interference.

[Brief description of drawings]

FIG. 1 is a block diagram of a transmitter showing an embodiment of the present invention.

FIG. 2 is a block diagram of a receiver showing an embodiment of the present invention.

FIG. 3 is a detailed block diagram of a transmitter showing an embodiment of the present invention.

FIG. 4 is a detailed block diagram of a receiver showing an embodiment of the present invention.

5A and 5B are diagrams for explaining the operation of the transmitter described in FIG. 3, in which FIG. 5A is a complex symbol sequence input to the symbol sequence conversion unit 1, and FIG. 5B is a Fourier transform unit 2. 5 (c) is a complex number sequence input to the spreading means 3, FIG. 5 (d) is a complex number sequence input to the inverse Fourier transforming means 4, and FIG. 5 (e) is a modulation means. FIG. 6 is a diagram for explaining each of the complex symbol sequences input to 5;

6A and 6B are diagrams for explaining the operation of the receiver described in FIG. 4, wherein FIG. 6A is a complex symbol string input to the Fourier transforming means 2 and FIG. 6B is input to the spreading means 7. 6 (c) is a complex number sequence input to the inverse Fourier transform means 4, FIG. 6 (d) is a complex symbol sequence input to the symbol sequence conversion means 8, and FIG. 6 (e) is a symbol sequence. It is a figure explaining each output of the conversion means 8.

FIG. 7 is a shift circuit of a transmitter / receiver according to an embodiment of the present invention, FIG. 7 (a) is a shift circuit used in a transmitter,
FIG. 7B shows a shift circuit used in the receiver.

FIG. 8 is a time chart illustrating the operation of FIGS. 5 and 6.

FIG. 9 is a diagram showing an embodiment of the present invention in which the number of subscribers is 16,
It is a figure which calculated how the bit error rate BER is influenced by the number of interfering subscribers when the number of complex symbols of Fourier transform is set to 16.

FIG. 10 is an effect of the symbol sequence conversion means 1 and the symbol sequence conversion means 8 when the number of interfering subscribers is 1, the number of subscribers is 16 and the number of complex symbols of Fourier transform is 16 in the embodiment of the present invention. FIG.

In the embodiment of the present invention, the number of interfering subscribers is 1, the number of complex symbol sequences and the number of complex symbol sequences are the same as the number of subscribers (symbol sequence conversion means and spreading means are square matrices), It is the figure which calculated how BER is influenced by the number of subscribers.

FIG. 12 is a diagram illustrating an operation of a transmitter according to an embodiment of the present invention, in which the number of complex symbol sequences is compared with the number of subscribers,
This is the case when the number of complex sequences is large.

FIG. 13 is an operation explanatory diagram of a receiver according to an embodiment of the present invention, in which the number of complex symbol sequences is compared with the number of subscribers,
This is the case when the number of complex sequences is large.

FIG. 14 is a diagram illustrating an embodiment of the present invention in which the number of subscribers is 1
FIG. 6 is a diagram showing how BER is affected by the number of complex symbol sequences and the number of complex number sequences of Fourier transform when the number of interfering subscribers is 1.

FIG. 15 is a diagram illustrating an embodiment of the present invention in which the number of subscribers is 1
Fig. 6 shows how the BER is affected by the number of complex symbol sequences and the number of complex number sequences of Fourier transform when the number of interfering subscribers is 1 and the number of complex symbol sequences is 16. is there.

FIG. 16 is a diagram showing an influence on rearrangement or rearrangement of the symbol string conversion means and the spreading means in the embodiment of the present invention.

FIG. 17 is a block diagram of a transmitter in a conventional frequency hopping transceiver.

FIG. 18 is a block diagram of a receiver in a conventional frequency hopping transceiver.

FIG. 19 is a diagram for explaining the signal collision between the interfering station and the interfered station in the conventional transceiver, and is an explanatory diagram in the case where there is no frequency hopping.

FIG. 20 is a diagram for explaining the signal collision between the interfering station and the interfered station in the conventional transceiver, and is an explanatory diagram in the case where there is frequency hopping.

FIG. 21 is a diagram showing an example of bit error rate characteristics in a conventional frequency hopping system.

[Explanation of symbols]

1 Symbol string conversion means 2 Fourier transform means 3 diffusion means 4 Inverse Fourier transform means 5 Modulation means 6 Demodulation means 7 diffusion means 8 Symbol string conversion means 11,71 shift circuit 12 counter 13 Random sequence generator

Claims (17)

[Claims] 1. A transmission / reception device in a spread spectrum frequency modulation system, wherein each of a transmitter and a receiver constituting the transmission / reception device performs symbol sequence conversion means for rearranging a complex symbol sequence and Fourier transform of the complex symbol sequence. A transmitting / receiving apparatus comprising: a Fourier transforming means, a spreading means for exchanging the conversion results of the Fourier transforming means, and an inverse Fourier transforming means for inverse Fourier transforming the output of the spreading means. 2. The symbol string conversion means comprises m (m is an integer) types and n (n is an integer) complex symbol strings T (m,
The n) is regularly rearranged for each complex symbol into a complex symbol sequence of T (m ± k, n), where k is an integer and ± is a rearrangement direction. Transceiver device. 3. The transmitting / receiving apparatus according to claim 1, wherein the symbol string converting means has a transmitter and a receiver in which rearrangement directions are opposite to each other. 4. The Fourier transforming means Fourier transforms a complex symbol sequence in which the number of complex symbols in one complex symbol sequence is equal to or larger than the kind of complex symbol sequence. The transmission / reception device according to claim 1. 5. The transmitter / receiver according to claim 1, wherein a plurality of the Fourier transform means are provided. 6. The spreading means sets k complex number sequence groups, 1 complex number sequence group n complex number sequences F (k, n), where p is a random number and ± is a rearrangement direction for each complex number sequence. , K complex number sequence groups F (± p, n) are randomly switched, and the transmitting / receiving apparatus according to claim 1. 7. The type m and the number n of one complex symbol sequence in the symbol sequence converting means, the number k of complex number sequence groups in the spreading means, and the number n of complex number sequences in one complex number sequence group, respectively, The transmitter / receiver according to claim 1, wherein they are equal. 8. The spreading means comprises a transmitter and a receiver,
8. The replacement direction is reverse.
The transmitter / receiver according to. 9. The transmitter / receiver according to claim 1, wherein a plurality of the inverse Fourier transform means are provided. 10. The transmitter / receiver according to claim 1, wherein the symbol string conversion means of the transmitter rearranges the complex transmitted symbol string for each subscriber. 11. The transmitter / receiver according to claim 1, wherein the Fourier transform means of the transmitter Fourier transforms a plurality of kinds of complex symbol sequences rearranged by the symbol sequence conversion means. 12. The transmitter / receiver according to claim 1, wherein the symbol string conversion means of the receiver rearranges the outputs of the inverse Fourier transform means. 13. In a transmission / reception system in a spread spectrum frequency modulation system, a symbol sequence conversion means for rearranging a complex symbol sequence, a plurality of Fourier transform means for performing a Fourier transform of a complex symbol sequence, and a conversion result of the Fourier transform means are interchanged. The transmitter and the receiver each having a spreading means and a plurality of inverse Fourier transform means for performing an inverse Fourier transform on the output of the spreading means, the transmitter arranges the complex transmission symbol sequence for each subscriber by the symbol sequence conversion means. In other words, the rearranged complex transmission symbol sequence is Fourier-transformed by the plurality of Fourier transforming means, the complex number sequence is replaced by the spreading means, and the inverse Fourier transforming is performed by the plurality of inverse Fourier transforming means. The signal is transmitted after being modulated by the transmitter. Complex transmission symbol sequences modulated at different frequencies are received and demodulated, Fourier transform is performed by the plurality of Fourier transform means, the complex number sequence is replaced by the spreading means, and inverse Fourier transform is performed by the plurality of inverse Fourier transform means. A transmission / reception system characterized by converting and rearranging by the symbol string conversion means to obtain a complex received symbol string for each subscriber. 14. The rearrangement in the symbol sequence conversion means is performed for m (m is an integer) types and n (n is an integer) number of complex symbol sequences T (m, n), k for each complex symbol. 14. The transmission / reception system according to claim 13, wherein rearrangement is performed regularly into a complex symbol sequence of T (m ± k, n) in which integers and ± are rearranged. 15. The transmission / reception system according to claim 13, wherein the rearrangement by the symbol string conversion means is performed by reversing the rearrangement direction between the transmitter and the receiver. 16. The replacement by the spreading means is performed by k complex number sequence groups, one complex number sequence group n complex number sequences F (k, n).
14. The transmission / reception system according to claim 13, wherein is randomly replaced with k complex number sequence groups F (± p, n) in which p is a random number and ± is a rearrangement direction for each complex number sequence. . 17. The transmission / reception system according to claim 13, wherein the switching by the spreading means is performed by reversing the switching directions of the transmitter and the receiver.