JPH11340950A - Synchronizing system in spread spectrum communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain easy achievement of synchronism establishment by performing multiple processing by the combination of codes in which correlation characteristics for synchronization on the reception side become zero near a synchronous point. SOLUTION: When the number of multiplexing is defined as (r), at a converting part 2, a serial signal is converted to a parallel signal by each of (r) pieces of data. The (r) pieces of converted parallel signals are spread with different orthogonal codes by (r) pieces of spreading parts (1), (2)...(r): 3-1...3-r. In this case, for example, multiple processing is performed by using a spread code for synchronization for the spreading part (1): 3-1. The preamble signal for each frame is used as a synchronizing signal and a signal, to which the preamble signal is converted as the parallel signal, is processed with the spread code for synchronization by the spreading part (1):3-1. In this case, the code for synchronization is a code at the time when the characteristic of mutual correlation between the code for synchronization and a reception multiplex signal multiplexed with the other code at the time of preamble, namely, synchronizing signal processing on the reception side becomes zero near a zero shift point or the absolute value of number of multiplexing becomes a minimum value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex communication system in direct spread spectrum spread spectrum communication.
In particular, the present invention relates to a code combination method used for establishing and holding the synchronization.

[0002]

2. Description of the Related Art In recent years, studies have been made on speeding up of a wireless LAN system using a spread spectrum technique, and some of them have been realized.

[0003] As a method of increasing the speed, a simple parallel system in which different codes are multiplexed and transmitted, a parallel combination system in which a combination of a plurality of codes is communicated as information, and an M-arry multiplex system in which M-arry is multiplexed. And so on.

[0004] Here, the simple parallel system is a system in which the direct spreading system is multiplexed in parallel for the code to be multiplexed, and when r multiplexes are performed, r information signals are transmitted at a time. is there. The number of correlators required on the receiver side in this system is r, and the number of transmitted spreading codes is equal to the number of despreading codes on the receiving side, that is, the number of correlators.

[0005] The parallel combination method refers to the number of code sequences N
Is a method of multiplexing and transmitting r codes from among
Transmit _{2 NC r} information signals at a time. In this system, the number of correlators required on the receiver side is N. On the receiver side, the cross-correlation value between the received signal and the N correlators becomes r, the correlation value becomes the maximum, and N- It means that r correlation values become zero.

Similarly, the M-arry multiplexing method is a method in which one code is selected from the number of code sequences M (= N / r) and r codes are multiplexed, and r × log ₂ M Is transmitted at a time. In this system, the number of correlators required on the receiver side is N. On the receiver side, the cross-correlation value between the received signal and the N correlators becomes r, the correlation value becomes the maximum, and N- It means that r correlation values become zero.

[0007] An orthogonal code sequence is often used in a code multiplexing system for multiplexing and transmitting different codes. The orthogonal code sequence has a feature that the cross-correlation characteristic with other codes in the same code sequence becomes zero at zero shift, and the auto-correlation characteristic becomes maximum at zero shift. However, it has been found that the autocorrelation characteristic of the orthogonal code is generally poor, and takes a relatively large correlation value other than the zero shift.

The symbol multiplexing method of the code multiplexing method includes an asynchronous method in which the symbol synchronization timing is determined from the maximum value of the correlator output, and a synchronization method in which the synchronization timing is obtained by using a synchronization code.

The asynchronous system is used for a system such as a simple parallel system in which all correlator outputs simultaneously peak. The cross-correlation of the r correlator outputs with the received multiplex signal is maximum at the synchronization point, and otherwise changes according to the side lobe of the cross-correlation characteristic with the received multiplex signal. Therefore, the point at which all of the r correlation outputs become maximum can be estimated as the symbol synchronization point. At this time, the influence of other spreading codes on each correlation output can be ignored from the orthogonality of the codes.

The synchronization method is used when values output from N correlators can have r correlation peak values at positions other than the zero shift point as well as the zero shift, for example, as in the parallel combination method. In other words, there is a method in which it is difficult to accurately determine the synchronization point, and a method in which synchronization is achieved by using a method for estimating from a synchronization code or frame synchronization.

In the method of establishing synchronization using a synchronization code, a signal obtained by further multiplexing a synchronization code to a spread multiplexed transmission information signal is transmitted, and the reception side detects the synchronization code multiplexed in the information signal. A symbol synchronization point is detected using a synchronization detection correlator. The other N correlator outputs are read in accordance with the peak output timing of the synchronous detection correlator.
Therefore, there is an advantage that there is no problem even if the cross-correlation characteristics of the N correlators are poor except for the zero shift.

A method of estimating a synchronization point from frame synchronization is to provide a non-spreading period at the beginning of a frame,
By providing a burst period with a large amplitude, a frame start point is detected, and symbol synchronization is performed based on the detected start point.

[0013]

However, multiplexing a synchronization code that does not include an information signal onto a spread information signal results in a reduction in signal power per code. further,
Even if a synchronization code is used, if the cross-correlation of the synchronization correlator with the received multiplex signal is poor, it takes time to detect the synchronization point, and the effective transmission rate is reduced.

The method of providing a non-spreading period in a frame or providing a burst period with a large amplitude may greatly affect other terminals during communication. Furthermore, there is a disadvantage that the error rate of symbol synchronization increases as the frame lengthens.

According to the present invention, in the processing of a synchronization signal by the synchronization spread code on the transmission side, a combination of codes in which the synchronization correlation characteristic on the reception side is zero near the synchronization point or the absolute value of the multiplexing number is the minimum value. The purpose of the present invention is to obtain a synchronization method in spread spectrum communication that can easily establish synchronization by performing multiplexing processing.

[0016]

According to a first aspect of the present invention, there is provided a synchronization method in spread spectrum communication, wherein the information signal is spread by a spread code and the communication is performed. Multiplexing a plurality of spreading codes, and performing spread modulation on a transmission side using a synchronization signal transmitted along with an information signal and at least one synchronization spreading code, and despreading on a reception side. By performing the above, in the synchronization according to the synchronization correlation characteristic of the receiving side, in the processing of the information signal by the spreading code on the transmitting side and the processing of the synchronization signal by the spreading code for the synchronization, the synchronization of the receiving side The multiplexing process is performed by using a combination of codes whose correlation characteristics become zero near the synchronization point.

The synchronization method in spread spectrum communication according to the second invention is a synchronization method in direct spread spectrum communication in which an information signal is spread by a spread code to perform communication, wherein a plurality of spread signals for processing the information signal are provided. By multiplexing the code and performing spread modulation on the transmission side using a synchronization signal and at least one synchronization spreading code transmitted according to the information signal, and performing despreading on the reception side, the reception is performed. The synchronization is performed in accordance with the synchronization correlation characteristic on the transmitting side. In the processing of the information signal by the spreading code on the transmitting side and the processing of the synchronization signal by the synchronization spreading code on the transmitting side, the synchronization correlation characteristic on the receiving side is a synchronization point. The multiplexing process is performed by a combination of codes in which the absolute value of the multiplexing number becomes the minimum value in the vicinity.

[0018] The synchronization method in spread spectrum communication according to the third invention is a synchronization method in direct spread spectrum communication in which communication is performed by spreading an information signal with a spread code, and the information signal is transmitted using a parallel combination method. While multiplexing a plurality of spreading codes to be processed, spread modulation is performed on a transmission side using a synchronization signal transmitted in accordance with an information signal and at least one synchronization spreading code, and despreading is performed on a reception side. By performing the synchronization according to the correlation characteristic for synchronization on the reception side, in the processing of the information signal by the spread code on the transmission side and the processing of the synchronization signal by the spread code for synchronization, the synchronization on the reception side Multiplexing is performed using a combination of codes whose correlation characteristics become zero near the synchronization point.

The synchronization method in spread spectrum communication according to a fourth aspect of the present invention is a synchronization method in direct spread spectrum communication in which an information signal is spread by a spreading code to perform communication, wherein the information signal is transmitted using a parallel combination method. While multiplexing a plurality of spread codes to be processed, spread modulation is performed on the transmission side using a synchronization signal and at least one synchronization spread code transmitted according to the information signal,
In addition, by performing despreading on the receiving side, in a device that synchronizes according to the correlation characteristic for synchronization on the receiving side, processing of an information signal by the spreading code on the transmitting side and synchronization of the synchronization signal by the spreading code for synchronization In the process, the multiplexing process is performed by using a combination of codes in which the absolute value of the multiplexing number has the minimum value near the synchronization point in the synchronization correlation characteristic on the receiving side.

A fifth aspect of the present invention provides a synchronization method in spread spectrum communication, which is a synchronization method in direct spread spectrum communication in which an information signal is spread by a spreading code to perform communication, and wherein the M-arry processes the information signal.
Multiplexing a plurality of spread codes, performing spread modulation on a transmission side using a synchronization signal transmitted in accordance with an information signal and at least one synchronization spread code, and performing despreading on a reception side. By the above, in the case where the synchronization is performed in accordance with the synchronization correlation characteristic on the reception side, in the processing of the information signal by the spreading code and the processing of the synchronization signal by the synchronization spreading code on the transmission side, the synchronization correlation characteristic of the reception side Perform multiplexing processing using a combination of codes that become zero near the synchronization point.

The synchronization method in spread spectrum communication according to the sixth invention is a synchronization method in direct spread spectrum communication in which an information signal is spread by a spreading code and communication is performed, and an M-arry for processing the information signal.
Multiplexing a plurality of spread codes, performing spread modulation on a transmission side using a synchronization signal transmitted in accordance with an information signal and at least one synchronization spread code, and performing despreading on a reception side. By the above, in the case where the synchronization is performed in accordance with the synchronization correlation characteristic on the reception side, in the processing of the information signal by the spreading code and the processing of the synchronization signal by the synchronization spreading code on the transmission side, the synchronization correlation characteristic of the reception side Is to perform multiplexing processing using a combination of codes in which the absolute value of the multiplexing number becomes the minimum value near the synchronization point.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Embodiment 1 of the present invention will be described with reference to the drawings. In addition,
In this embodiment, a description will be given using a QPSK system, that is, a multi-level phase modulation system as an example.

FIGS. 1 and 2 are block connection diagrams of a communication system based on a direct spread spectrum communication system for realizing a spread code multiplexing system according to the first embodiment of the present invention. For simplicity.

FIG. 1 shows a transmitter 8, wherein 1 is an information signal, 2 is a converter for converting a serial signal of the information signal 1 into a parallel signal, 3-1, 3-2,. r is the diffusion part (1),
(2),..., (R), 4 is an adder, 5 is a secondary modulator, 6 is a frequency converter, and 7 is an antenna.

When the number of multiplexes is r, the converter 2 converts a serial signal into a parallel signal for every r data.
The converted r parallel signals are divided into r spreading units (1),
(2),..., (R): Spread by different orthogonal codes in 3-1, 3-2,. Of the r spreading units, for example, a spreading unit (1): 3-1 performs multiplexing processing using a synchronization spreading code.

The information signal 1 is composed of a plurality of frames, and each frame is composed of a preamble signal provided at the beginning of the frame and a subsequent original information signal. In the embodiment of the present invention, a preamble signal of each frame is used as a synchronization signal, and a signal obtained by converting the preamble signal as a parallel signal is converted by a spreading unit (1): 3-1 using a synchronization spreading code. It is processed.

The synchronizing code referred to here means that the cross-correlation characteristic between the synchronizing code and the multiplexed signal multiplexed with other codes at the time of preamble on the receiving side, that is, at the time of synchronizing signal processing, is zero near the zero shift point. Or a code that minimizes the absolute value of the multiplexing number.

The parallel signals spread by the r number of spreading units 3-1, 3-2,..., 3-r are multiplexed in the adder 4 and converted into multiplexed spread signals. Thereafter, the secondary modulation section 5 receives secondary modulation. And the frequency converter 6
Is converted to a desired frequency and transmitted from the antenna 7.

FIG. 2 shows a receiver 16, in which 10 is a frequency converter, 11 is a secondary demodulator, 12 is a determiner, 13
-1, 13-2,..., 13-r are correlation units (1), (2),
.., (R), 14 is a converter, and 15 is an information signal.

The multi-level spread modulated signal received from the antenna 9 is converted into a baseband band by passing through a frequency conversion section 10, and is converted into a multi-level spread signal through a secondary demodulation section 11. The converted multi-level spread signals are output to the correlation units 13-1 and 13-1.
-2, ........., 13-r and cross-correlated. This r
Of the correlation units, for example, a synchronization despreading code is used for the correlation unit (1): 13-1.

Correlation unit (1): In 13-1, the absolute value of zero or the number of multiplexing in the vicinity of the synchronization point for the code combination selected at the time of preamble on the transmitting side, that is, at the time of processing with the spreading code for synchronization, is calculated. The correlation is obtained with the synchronization despreading code that has the minimum value. Therefore, in the initial synchronization acquisition mode, the slope before and after the synchronization point becomes sharp due to the pattern of the cross-correlation characteristic, and synchronization acquisition becomes easy.

FIG. 3 shows spreading codes a, b, and c in the case of three multiplexing as an example. b is a spreading code for synchronization. FIG. 4 is a waveform diagram of FIG. Here, if each code is added to the preamble signal, FIG. 4 becomes a multi-level spreading code as shown in FIG.

Receiving-side correlation units 13-1, 13-2,..., 1
In 3-r, a correlation is obtained with respect to the demodulated waveform in FIG.
FIG. 5 shows the cross-correlation characteristics of the despreading code with respect to the multiplexed code when there is no deterioration. Here, the correlation units 13-1, 13-2,
In 13-r, the spreading code is used as a despreading code.

When a synchronization acquisition circuit such as a DLL is used, an S curve can be relatively easily formed because the vicinity of the synchronization point is zero.

FIG. 7 shows a spread code waveform after multiplexing according to the first embodiment of the present invention.

FIG. 8 shows a cross-correlation characteristic with a multi-spread code according to the first embodiment of the present invention.

FIG. 9 shows a cross-correlation characteristic with a multiple spreading code according to the first embodiment of the present invention.

FIG. 10 shows a cross-correlation characteristic for DLL according to the first embodiment of the present invention.

FIG. 11 shows the S-curve characteristics of the DLL according to the first embodiment of the present invention.

In the embodiment of the present invention, attention is paid to a preamble signal at the beginning of a frame, and a code combination and a multiplexing method are used such that an information signal multiplexed using an orthogonal code sequence becomes constant during the preamble. This facilitates initial synchronization establishment.

The cross-correlation characteristic between the synchronization code at the time of the preamble and the received multiplexed signal is zero in the vicinity of the zero shift point or a code combination that minimizes the absolute value of the multiplexing number is used to detect the synchronization point. It is possible to make it easier.

According to the code multiplexing method in the embodiment of the present invention, since the received multiplexed signal in the preamble is constant, the output of the correlator for synchronization is constant for each symbol, and the synchronization point is estimated from the cross-correlation characteristic. Is easy.

Also, regarding the synchronization holding during the preamble, since the correlation value near the synchronization point is small, it is easy to hold the synchronization by DLL or the like.

Further, during periods other than the preamble period, it is possible to transmit synchronization information and an information signal using a synchronization code.

Embodiment 2 Embodiment 2 will be described with reference to the drawings. In this embodiment, a description will be given using a QPSK system, that is, a multi-level phase modulation system as an example.

FIGS. 12 and 13 are block connection diagrams of a direct spread spectrum communication system for realizing a spread code multiplexing system using a parallel combination system according to the second embodiment of the present invention. Has been simplified for the sake of explanation.

First, FIG. 12 shows a transmitter 30, 22 is an information signal, 23 is a converter for converting a serial signal to a parallel signal, 24 is a code selector, 25-1, 25-2, 25-2. …
……, 25-r are diffusion parts (1), (2), ……,
(R) and 26 are adders, 27 is a secondary modulator, 28 is a frequency converter, and 29 is an antenna.

Now, assuming that the multiplex number is r, the conversion unit 23
In converts a serial signal into parallel signals for each log _{2 N} C _r pieces of data. The converted log _{2 N} C _r parallel signals are
The selection circuit 24 selects r code combinations that correspond one-to-one. Based on the selected combination, r number of spreading units 25-1, 25-2,..., 25-r are spread by the selected orthogonal code. Of these r diffusion units,
For example, multiplexing processing is performed using a synchronization spreading code for the spreading unit 25-1.

R diffusion units 25-1, 25-2,..., 2
The parallel signal spread by 5-r is multiplexed in an adder 26 and converted into a multilevel spread signal. after this,
The secondary modulation section 27 receives secondary modulation. Then, the signal is converted into a desired frequency by the frequency converter 28 and transmitted from the antenna 29.

FIG. 13 shows the receiver 55.
Is an antenna, 32 is a frequency converter, 33 is a secondary demodulator,
Numeral 34 denotes a sign determination unit, 35-1, 35-2,..., 35-N denote correlation units (1), (2),..., (N), 36 denotes a conversion unit, and 37 denotes an information signal. is there.

The multi-level spread modulated signal received from the antenna 31 is converted to a baseband band by passing through a frequency converter 32, and is converted to a multi-level spread signal through a secondary demodulator 33. The converted multi-level spread signal is output to the correlator 35-1,
35-2,..., 35-N, and cross-correlate.
Of the N correlation sections, for example, 35-1 correlation sections (1)
Uses a despreading code for synchronization.

Correlation unit (1): 35-1 has a minimum value of zero or the absolute value of the multiplexing number near the synchronization point for the combination of codes selected at the time of preamble on the receiving side, that is, at the time of code processing for synchronization. The correlation is obtained with the despreading code for synchronization. Therefore, in the initial synchronization acquisition mode, the slope before and after the synchronization point becomes sharper than the pattern of the cross-correlation characteristic, so that the acquisition of the synchronization is facilitated, and the same effect as in the first embodiment can be obtained.

Embodiment 3 Embodiment 3 will be described with reference to the drawings. In this embodiment,
As an example, a description will be given using a QPSK system, that is, a multi-level phase modulation system.

FIGS. 14 and 15 are block connection diagrams of a direct spread spectrum communication system for realizing a spread code multiplexing system using the M-arry multiplexing system according to the second embodiment of the present invention. It is simplified for explanation of the operation principle.

First, FIG. 14 shows a transmitter 46, 38 is an information signal, 39 is a converter for converting a serial signal into a parallel signal, 40 is a code selector, 41-1, 41-2, and 41-1. …
……, 41-r are diffusion parts (1), (2), ……,
(R), 42 are adders, 43 is a secondary modulator, 44 is a frequency converter, and 45 is an antenna.

When the multiplex number is r, the conversion unit 39
In this example, a serial signal is converted into a parallel signal every r × log ₂ M data. The converted r × log ₂ M parallel signals are divided into log ₂ M parallel signals by a code selection circuit 40, and one code is selected from M codes for each parallel signal, and r codes are selected. Select a combination. Based on the selected combination, r diffusion units 41-1, 41-2,..., 41
At -r, it is spread by the selected orthogonal code.
The multiplexing process is performed using, for example, a synchronization spreading code for the 41-1 spreading unit (1) among the r spreading units.

R diffusion units 41-1, 41-2,..., 4
The parallel signals spread by 1-r are multiplexed in the adder 42 and converted into multi-level spread signals. After this, 2
The secondary modulation section 43 receives secondary modulation. Then, the signal is converted into a desired frequency by the frequency conversion unit 44 and transmitted from the antenna 45.

FIG. 15 shows a receiver 54, in which 47 is an antenna, 48 is a frequency conversion section, 49 is a secondary demodulation section, 50 is a code determination section, 51-1, 51-2,... …,
51-N are correlation units (1), (2),..., (N), and 52
Is a converter, and 53 is an information signal.

The multi-level spread modulation signal received from the antenna 47 passes through the frequency conversion section 48, is converted into a baseband band, passes through the secondary demodulation section 49, and is converted into a multi-level spread signal. The converted multi-level spread signals are output to the correlation units 51-1 and 5-1.
1-2,..., And 51-N are input and cross-correlated. Of the N correlation sections, for example, a synchronization despreading code is used for 51-1 correlation section (1).

Correlation unit (1): In 51-1, for the combination of codes selected at the time of the preamble on the transmitting side, that is, at the time of the spreading code processing for synchronization, the zero or the absolute value of the multiplexing number is the minimum value near the synchronization point. The correlation is obtained with the despreading code for synchronization. Therefore, the slope before and after the synchronization point becomes steeper than the pattern of the cross-correlation characteristic in the initial synchronization acquisition mode, facilitating synchronization acquisition, and the same effect as in the first embodiment can be obtained.

As described above, by configuring the transmission / reception device as in the embodiment of the present invention, synchronization acquisition / holding utilizing a preamble signal at the time of code multiplexing can be easily performed.

As described above, according to the embodiment of the present invention, the cross-correlation characteristic between the code selection and the multi-level spreading code after multiplexing the code selection in the code multiplex communication becomes zero or the number of multiplexing until around the zero shift time. Using the combination of codes having the minimum absolute value and utilizing the signal pattern of the preamble signal has the effect of hastening the initial synchronization acquisition during the preamble.

Further, since the absolute value of zero or the number of multiplexes takes the minimum value before and after the zero shift, there is an effect that the synchronization holding after the initial synchronization acquisition is hastened without requiring a complicated circuit configuration.

As a result, the effective transmission rate can be increased even in an environment where the frame configuration is short and there are many temporal changes.

[0065]

According to the first aspect of the present invention, in direct spread spectrum communication for speeding up by multiplexing a plurality of spread codes, processing of an information signal by a spread code on the transmitting side and synchronization by a spread code for synchronization are performed. In signal processing, by performing multiplexing processing with a combination of codes having a correlation characteristic for synchronization on the receiving side that becomes zero near the synchronization point, a synchronization scheme in spread spectrum communication that can easily achieve synchronization can be obtained. .

According to the second aspect of the present invention, in direct spread spectrum communication for speeding up by multiplexing a plurality of spread codes, processing of an information signal by a spread code on the transmitting side and synchronization of a synchronization signal by a spread code for synchronization are performed. In processing
A synchronization method in spread spectrum communication that can easily achieve synchronization is obtained by performing multiplexing processing with a combination of codes in which the absolute value of the multiplexing number has a minimum value in the vicinity of the synchronization point where the correlation characteristic for synchronization on the reception side is near. be able to.

According to the third aspect of the present invention, in a direct spread spectrum communication which speeds up by multiplexing a plurality of spread codes by using a parallel combination method, processing of an information signal by spread codes on a transmitting side and spread for synchronization are performed. In processing a synchronization signal by a code, a synchronization method in spread spectrum communication that can easily achieve synchronization is obtained by performing multiplexing processing with a combination of codes in which the correlation characteristic for synchronization on the receiving side becomes zero near the synchronization point. be able to.

According to the fourth aspect of the present invention, in a direct spread spectrum communication which speeds up by multiplexing a plurality of spread codes by using a parallel combination method, processing of an information signal by spread codes on a transmitting side and spread for synchronization are performed. In processing the synchronization signal by code, synchronization can be easily established by performing multiplexing processing with a code combination in which the absolute value of the multiplexing number has the minimum value in the vicinity of the synchronization point where the correlation characteristic for synchronization on the receiving side is the minimum. A synchronization method in spread spectrum communication can be obtained.

According to the fifth aspect of the present invention, in the direct spread spectrum communication for increasing the speed by multiplexing a plurality of M-arry spread codes, the information signal processing by the spread code on the transmitting side and the synchronization spread code are performed. In processing a synchronization signal, it is possible to obtain a synchronization method in spread spectrum communication that can easily achieve synchronization by performing multiplexing processing with a combination of codes in which the correlation characteristic for synchronization on the receiving side becomes zero near the synchronization point. it can.

According to the sixth aspect of the present invention, in the direct spread spectrum communication for increasing the speed by multiplexing a plurality of M-arry spreading codes, the processing of the information signal by the spreading code on the transmitting side and the processing by the synchronization spreading code are performed. In the processing of the synchronization signal, the spread spectrum that can easily achieve synchronization is achieved by performing multiplexing processing with a combination of codes in which the absolute value of the multiplexing number has a minimum value near the synchronization point when the correlation characteristic for synchronization on the receiving side is near the synchronization point A synchronization method in communication can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a transmitter using a parallel multiplex spreading method according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a receiver using a parallel multiplexing spreading method according to the first embodiment of the present invention.

FIG. 3 is a numerical diagram showing each spreading code before multiplexing according to the first embodiment of the present invention.

FIG. 4 is a waveform chart showing each spreading code before multiplexing according to the first embodiment of the present invention.

FIG. 5 is a numerical diagram showing a mutual relation characteristic of a despreading code with respect to a multiplexed code when there is no deterioration according to the first embodiment of the present invention.

FIG. 6 is a characteristic diagram showing an autocorrelation characteristic of the synchronization spreading code according to the first embodiment of the present invention.

FIG. 7 is a waveform chart showing a spread code waveform after multiplexing according to the first embodiment of the present invention.

FIG. 8 is a numerical diagram showing a cross-correlation characteristic with a multiple spreading code according to the first embodiment of the present invention.

FIG. 9 is a characteristic diagram showing a cross-correlation characteristic with a multiple spreading code according to the first embodiment of the present invention.

FIG. 10 is a characteristic diagram showing a cross-correlation characteristic for DLL according to the first embodiment of the present invention.

FIG. 11 shows the S of the DLL according to the first embodiment of the present invention.
FIG. 4 is a characteristic diagram showing curve characteristics.

FIG. 12 is a configuration diagram showing a transmitter using a parallel combination multiplexing spreading method according to a second embodiment of the present invention.

FIG. 13 is a configuration diagram showing a receiver using a parallel combination multiplexing spreading method according to a second embodiment of the present invention.

FIG. 14 is a configuration diagram showing a transmitter using an M-arry multiplex spreading method according to a third embodiment of the present invention.

FIG. 15 is a configuration diagram showing a receiver using an M-arry multiplex spreading method according to a third embodiment of the present invention.

[Explanation of symbols]

1, 22, 38 Transmitter side information signal, 2, 23, 39
S / P converter, 3-1 to 3-r, 25-1 to 25-r, 41-1 to
41-r diffusion unit, 4, 26, 42 adder, 5, 27,
43 secondary modulator, 6, 28, 44 transmitter-side frequency converter, 7, 29, 45 transmitter-side antenna, 8, 30,
46 transmitter, 9, 31, 47 receiver side antenna, 1
0, 32, 48 Receiving side frequency converter, 11, 33, 4
9 Secondary demodulation unit, 12 judgment unit, 13-1 to 13-r, 35
-1 to 35-N, 51-1 to 51-N correlator, 14, 36, 5
2 P / S converter, 15, 37, 53 Receiver side information signal, 16, 54, 55 Receiver, 34, 50 Sign determination unit.

Claims (6)

[Claims] 1. A synchronization method in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication, wherein a plurality of spread codes for processing the information signal are multiplexed and matched with the information signal. By performing spread modulation on the transmission side using the transmitted synchronization signal and at least one synchronization spreading code, and performing despreading on the reception side, synchronization is achieved according to the synchronization correlation characteristic on the reception side. In the processing of the information signal by the spreading code on the transmitting side and the processing of the synchronizing signal by the synchronizing spreading code on the transmitting side, the multiplexing process is performed by a combination of codes whose correlation correlation characteristic on the receiving side becomes zero near the synchronization point. A synchronization method in spread spectrum communication characterized by performing. 2. A synchronous system in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication, wherein a plurality of spread codes for processing the information signal are multiplexed and matched with the information signal. By performing spread modulation on the transmission side using the transmitted synchronization signal and at least one synchronization spreading code, and performing despreading on the reception side, synchronization is achieved according to the synchronization correlation characteristic on the reception side. In the processing of the information signal by the spreading code and the processing of the synchronization signal by the synchronization spreading code on the transmitting side, the synchronization correlation characteristic on the receiving side is near the synchronization point and the absolute value of the multiplexing number is the minimum value. A synchronization method in spread spectrum communication, characterized in that multiplex processing is performed using a combination of codes. 3. A synchronization method in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication by multiplexing a plurality of spread codes for processing the information signal using a parallel combination method. Performing spread modulation on the transmission side using a synchronization signal and at least one synchronization spreading code transmitted according to the information signal,
In addition, by performing despreading on the receiving side, in the one that synchronizes according to the correlation characteristic for synchronization on the receiving side, the processing of the information signal by the spreading code on the transmitting side and the synchronization signal by the spreading code for synchronization are performed. A synchronization method in spread spectrum communication, characterized in that, in processing, multiplexing processing is performed using a combination of codes whose synchronization correlation characteristics on the receiving side become zero near a synchronization point. 4. A synchronization method in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication by multiplexing a plurality of spread codes for processing the information signal using a parallel combination method. By performing spread modulation on the transmission side using a synchronization signal and at least one synchronization spread code transmitted in accordance with the information signal, and performing despreading on the reception side, the synchronization correlation characteristic on the reception side is improved. When processing is performed on the information signal using the spreading code on the transmitting side and processing the synchronization signal using the spreading code for synchronization on the transmitting side, the synchronization correlation characteristic on the receiving side has an absolute value of the multiplexing number near the synchronization point. A synchronization method in spread spectrum communication, wherein multiplex processing is performed using a combination of codes having a minimum value. 5. A synchronization method in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication by multiplexing a plurality of M-arry spread codes for processing the information signal, Performing spread modulation on the transmission side using a synchronization signal and at least one synchronization spread code transmitted in accordance with the synchronization signal, and performing despreading on the reception side, according to the synchronization correlation characteristic on the reception side. In the synchronization, in the processing of the information signal by the spreading code on the transmitting side and the processing of the synchronization signal by the spreading code for synchronization, the combination of codes having a synchronization correlation characteristic of zero on the receiving side near the synchronization point. Synchronization method in spread spectrum communication characterized by performing multiplex processing. 6. A synchronization method in direct spread spectrum communication for performing communication by spreading an information signal by a spread code and performing communication by multiplexing a plurality of M-arry spread codes for processing the information signal, Performing spread modulation on the transmission side using a synchronization signal and at least one synchronization spread code transmitted in accordance with the synchronization signal, and performing despreading on the reception side, according to the synchronization correlation characteristic on the reception side. In the synchronization, in the processing of the information signal by the spreading code on the transmitting side and the processing of the synchronization signal by the spreading code for the synchronization, the correlation characteristic for synchronization on the receiving side has an absolute value of the multiplexing number near the synchronization point. A synchronization method in spread spectrum communication, characterized in that multiplex processing is performed using a combination of codes having a minimum value.