JP3484345B2 - Synchronization method in spread spectrum communication - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to spread spectrum
Synchronization method in a communication, in particular, relates to a multiplex communication system in a spread spectrum communication direct diffusion method is relates <br/> to the combination method of code used when performing the synchronization establishment and maintenance of it.

[0002]

2. Description of the Related Art In recent years, a wireless LAN system using a spread spectrum technique has been studied and partially realized.

As these speed-up techniques, a simple parallel system for multiplexing and transmitting different codes, a parallel combination system for communicating a combination of a plurality of codes as information, and an M-arry multiplexing system for multiplexing M-arry Are being considered.

Here, the simple parallel system is a system in which the direct spreading system is multiplexed in parallel for the code to be multiplexed. When r pieces are multiplexed, r information signals are transmitted at one time. is there. The number of correlators required on the receiver side of this system is r, and the number of transmitted spreading codes and the number of despread codes on the receiving side, that is, the number of correlators are equal.

The parallel combination method is the number N of code sequences.
Is a method of multiplexing and transmitting r codes from among
Transmit _2N C _r information signals at one time. The number of correlators required on the receiver side of this system is N, and on the receiver side, the cross-correlation value between the received signal and the N correlators is the maximum of r correlation values, and N- It means that r correlation values are zero.

Similarly, the M-arry multiplex system is a system in which one code is selected from the number M (= N / r) of code sequences and r codes are multiplexed, and r × log ₂ M codes are selected. The information signal of 1 shall be transmitted at one time. The number of correlators required on the receiver side of this system is N, and on the receiver side, the cross-correlation value between the received signal and the N correlators is the maximum of r correlation values, and N- It means that r correlation values are zero.

Orthogonal code sequences are often used as a code multiplexing method for multiplexing and transmitting different codes. The orthogonal code sequence has the characteristics that the cross-correlation characteristic with other codes in the same code sequence becomes zero at zero shift and the autocorrelation characteristic becomes maximum at zero shift. However, the autocorrelation characteristics of orthogonal codes are generally poor, and it is known that a correlation value other than zero shift takes a relatively large value.

Among these code multiplexing symbol synchronization methods, there are 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 using a spreading code for synchronization.

The asynchronous method is used in a method in which all the correlator outputs peak at the same time, such as the simple parallel method. The cross-correlation of the r correlator outputs with the received multiplex signal is maximum at each synchronization point, and in other cases, changes according to the side lobes of the cross-correlation characteristics with the received multiplex signal. Therefore, it can be inferred that the point where all r correlation outputs are maximum is the symbol synchronization point. At this time, the influence of other spread codes on each correlation output can be ignored because of the orthogonality of the codes.

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

[0011] synchronization method using a synchronization spreading code, spread multiplexed transmission information further transmits the multiplexed signal for synchronization spread code signal, synchronizing spread code multiplexed to the information signal at the receiving end The symbol sync point is detected by using a sync detection correlator for detecting the. The other N correlator outputs are read in time with the peak output timing of the synchronization detecting correlator. Therefore, there is an advantage that there is no problem even if the cross-correlation characteristics of the N correlators are bad except for zero shift.

Further, the method of estimating the synchronization point from the frame synchronization is such that a period during which the frame is not spread is provided at the beginning of the frame,
The frame start point is detected by providing a large-amplitude burst period, and symbol synchronization is performed based on the detected frame start point.

[0013]

However, multiplexing the synchronization code not containing the information signal with the spread information signal results in a drop in the signal power per code. further,
Even if a sync code is used, if the cross-correlation of the sync correlator with the received multiplex signal is poor, it takes time to detect the sync point, and the effective transmission rate is lowered.

Further, the method of providing a period in which no spread occurs in the frame or a burst period of large amplitude may have a great influence on other terminals in communication. Further, there is a drawback that the symbol synchronization error rate increases as the frame lengthens.

[0015] The present invention, when the processing of the synchronization signal by the synchronizing spread code on the transmission side, the receiver synchronous signal
It was multiplexed with the synchronous spreading code and other code during signal processing.
It is easy to establish synchronization by performing multiplex processing with a combination of codes whose cross-correlation characteristics with the received multiplex signal are zero near the synchronization point or the absolute value of the value that can be obtained by multiplexing according to the number of multiplexes is the minimum value It is intended to obtain a synchronization method in spread spectrum communication that can be achieved.

[0016]

Means for Solving the Problems] In synchronization method in a spread spectrum communication according to the first invention, there is provided a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, the information signal A plurality of spreading codes for processing the same, and at the same time, the transmitting side performs spread modulation using the synchronizing signal transmitted in accordance with the information signal and at least one synchronizing spreading code, and the receiving side performs despreading. by performing, in which synchronization according to the synchronization correlation characteristics of the reception side, when the processing of the synchronization signal by processing and the synchronizing spread code information signal by the spreading code in the transmitting side, the receiving side sync It is often used with the synchronous spreading code and other codes during signal processing.
Multiplexing processing is performed with a combination of codes whose cross-correlation characteristics with the multiplexed received multiplexed signal are zero near the synchronization point.

[0017] In synchronization method in a spread spectrum communication according to the second invention, there is provided a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, a plurality of diffusion for processing the information signal In addition to multiplexing the code, the transmission side performs spread modulation using the synchronization signal transmitted at the same time as the information signal and at least one synchronization spreading code, and the receiving side performs despreading, thereby receiving. In synchronizing according to the synchronization correlation characteristic on the receiving side, in processing the information signal by the spreading code on the transmitting side and processing the synchronizing signal by the spreading code for synchronizing, at the time of processing the synchronizing signal on the receiving side.
Received multiplex multiplexed with synchronous spreading code and other code in
The cross-correlation characteristics with the number of signals depending on the number of multiplexes near the synchronization point.
In addition , the multiplex processing is performed with the combination of the codes in which the absolute value of the values that can be obtained by the multiplex is the minimum value.

[0018] In synchronization method in a spread spectrum communication according to the third invention, there is provided a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, the information signal using a parallel combination method In addition to multiplexing a plurality of spread codes to be processed, the spread signal is spread-modulated on the transmission side using the synchronization signal transmitted at the same time as the information signal and at least one synchronization spreading code, and despreading is performed on the reception side. By performing the synchronization in accordance with the correlation characteristic for synchronization on the receiving 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 spreading code for synchronization on the receiving side, the synchronizing signal on the receiving side Synchronous spreading code and others during processing
In this case , the multiplex processing is performed by the combination of codes whose cross-correlation characteristics with the received multiplex signal multiplexed with the code are zero near the synchronization point.

[0019] In synchronization method in a spread spectrum communication according to the fourth aspect of the invention, there is provided a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, the information signal using a parallel combination method Along with multiplexing a plurality of spread codes to be processed, perform spread modulation on the transmission side using a synchronization signal and at least one synchronization spread code transmitted in accordance with the information signal,
In addition, by performing despreading on the receiving side, synchronization is obtained according to the synchronization correlation characteristic of the receiving side, in the processing of the information signal by the spreading code and the synchronization signal by the synchronizing spreading code on the transmitting side. In processing, the synchronization spread code and other codes at the time of processing the synchronization signal on the receiving side
With respect to the cross-correlation characteristic with the multiplexed received multiplex signal , multiplex processing is performed with a combination of codes having a minimum absolute value of values that can be obtained by multiplexing according to the number of multiplexes in the vicinity of the synchronization point.

[0020] M-arry of the synchronization method in the spread spectrum communication according to a fifth invention, there is provided a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, processing said information signal
In addition to multiplexing a plurality of spreading codes, performing spread modulation on the transmitting side and despreading on the receiving side using a synchronization signal transmitted at the same time as an information signal and at least one spreading code for synchronization. Thus, in the case of synchronizing according to the correlation characteristic for synchronization on the receiving side, in processing the information signal by the spreading code on the transmitting side and processing the synchronizing signal by the spreading code for synchronizing on the receiving side, the synchronizing signal on the receiving side
During processing, the synchronization spread code and other code multiplexed with other code
Multiplexing is performed with a combination of codes whose cross-correlation characteristics with a signal multiplex signal are zero near the synchronization point.

[0021] M-arry of the synchronization method in the spread spectrum communication according to the sixth invention, a synchronization method in a direct spread spectrum communication which performs communication by spread spectrum information signals by spread codes, processing said information signal
In addition to multiplexing a plurality of spreading codes, performing spread modulation on the transmitting side and despreading on the receiving side using a synchronization signal transmitted at the same time as an information signal and at least one spreading code for synchronization. Thus, in the case of synchronizing according to the correlation characteristic for synchronization on the receiving side, in processing the information signal by the spreading code on the transmitting side and processing the synchronizing signal by the spreading code for synchronizing on the receiving side, the synchronizing signal on the receiving side
During processing, the synchronization spread code and other code multiplexed with other code
Regarding the cross-correlation characteristic with the signal multiplex signal, the multiplexing process is performed in the vicinity of the synchronization point with a combination of codes having the smallest absolute value of the values that can be obtained by multiplexing according to the number of multiplexing.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. Embodiment 1 of the present invention will be described with reference to the drawings. In this embodiment, as an example, QP
The description will be made using the SK system, that is, the multi-level phase modulation system.

FIGS. 1 and 2 are block connection diagrams of a direct spread spectrum communication system which realizes a spread code multiplexing system according to Embodiment 1 of the present invention. Therefore, it is simplified.

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

Now, assuming that the number of multiplexes is r, the conversion unit 2 converts a serial signal into a parallel signal for each r data.
The converted r parallel signals are converted into r spread units (1),
(2), ..., (r): 3-1, 3-2, ..., 3-r are spread by different orthogonal codes. Of these r spreading units, for example, spreading unit (1): 3-1 uses the spreading code for synchronization to perform multiplexing processing.

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, the preamble signal of each frame is used as a synchronization signal, and the signal obtained by converting the preamble signal as a parallel signal is converted by the spreading code for synchronization in the spreading unit (1): 3-1. It is processed.

The synchronization spreading code here is used for synchronization at the time of preamble on the receiving side, that is, at the time of synchronizing signal processing.
The cross-correlation characteristic between the spread code and the received multiplex signal multiplexed with another code is zero or the number of multiplexes near the zero shift point.
Is a code that has the smallest absolute value of the values that can be obtained by multiplexing in accordance with.

The parallel signals spread by the r spreaders 3-1, 3-2, ..., 3-r are multiplexed in the adder 4 and converted into multiple spread signals. Then, the secondary modulation unit 5 receives the secondary modulation. Then, the frequency conversion unit 6
At, the signal is converted to a desired frequency and transmitted from the antenna 7.

FIG. 2 shows the receiver 16, where 10 is a frequency conversion unit, 11 is a secondary demodulation unit, 12 is a judgment unit, and 13 is a judgment unit.
-1, 13-2, ………, 13-r is the correlation part (1), (2),
..., (r), 14 is a conversion unit, and 15 is an information signal.

The multilevel spread modulation signal received from the antenna 9 is converted into a baseband band by passing through the frequency conversion section 10, and is converted into a multilevel spread signal through the secondary demodulation section 11. The converted multilevel spread signal is used in the correlation units 13-1, 13
-2, ………, 13-r is input and cross-correlation is taken. This r
The despreading code for synchronization is used for, for example, the correlation unit (1): 13-1 among the correlation units.

The correlator (1): 13-1 multiplexes, in the vicinity of the synchronization point, zero or the number of multiplexes with respect to the combination of codes selected at the time of preamble on the transmitting side, that is, at the time of processing by the spreading code for synchronization. Correlation is performed with a despreading code for synchronization in which the absolute value of the values that can be obtained by conversion is the minimum value. Therefore, in the initial synchronization acquisition mode, the pattern of the cross-correlation characteristic makes the inclination before and after the synchronization point sharp and facilitates the synchronization acquisition.

FIG. 3 shows spreading codes a, b and c in the case of multiplexing 3 as an example. b is a spreading code for synchronization. Further, FIG. 4 is a waveform of FIG. these
The spreading code of is a wide matrix as an n-th order matrix whose component elements are 1 or -1.
By the same method as the well-known Hadamard matrix creation method
Created. Here, assuming that each code is added to the preamble signal, FIG. 4 becomes a multilevel spread code as shown in FIG. 7 .

Receiving side correlator 13-1, 13-2, ..., 1
At 3-r, the demodulated waveform of FIG. 7 is correlated.
FIG. 9 shows the cross-correlation characteristics of the despreading code with respect to the multiple code when there is no deterioration. Here, the correlation units 13-1, 13-2,
............ In 13-r, the spreading code is used as the despreading code.

When a synchronization acquisition circuit such as DLL is used, the S curve can be relatively easily created 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 the cross-correlation characteristic with the multiple spreading code according to the first embodiment of the present invention.

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

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

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

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

Then, the synchronization point detection is performed by using a combination of codes in which the cross-correlation characteristics of the synchronization spreading code at the preamble and the received multiplex signal are zero or the absolute value of the multiplex number is the minimum in the vicinity of the zero shift point. It is possible to facilitate.

Code multiplexing method in the embodiment of the present invention
According to the method , 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 can be easily estimated from the cross-correlation characteristics.

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, in the period other than the preamble period, the synchronization is performed.
It is possible to transmit the synchronization information and the information signal using the special spreading code.

Embodiment 2. The second embodiment will be described with reference to the drawings. In this embodiment, the QPSK method, that is, the multi-level phase modulation method will be used as an example for description.

12 and 13 are block connection diagrams of a direct spread spectrum communication system which realizes a spread code multiplexing system using a parallel combination system according to the second embodiment of the present invention. It is simplified for explanation.

First, FIG. 12 shows a transmitter 30, where 22 is an information signal, 23 is a conversion unit for converting a serial signal into a parallel signal, 24 is a code selection unit, 25-1, 25-2, …
……, 25-r is the diffusion part (1), (2), ………,
(R), 26 is an adder, 27 is a secondary modulator, 28 is a frequency converter, and 29 is an antenna.

Now, when the number of multiplexes is r, the conversion unit 23
Then, the serial signal is converted into the parallel signal for each of the log _2N C _r pieces of data. The converted log _2N C _r parallel signals are selected by the selection circuit 24 from a combination of r codes that are in one-to-one correspondence. Based on the selected combination, the r spreading units 25-1, 25-2, ..., 25-r spread the selected orthogonal code. Of the r spreading units, for example, 25-1 spreading units 1 perform the multiplexing process using the spreading code for synchronization.

R diffusers 25-1, 25-2, ..., 2
The parallel signal spread by 5-r is multiplexed in the adder 26 and converted into a multilevel spread signal. after this,
The secondary modulation unit 27 receives the secondary modulation. Then, it is converted into a desired frequency in the frequency conversion unit 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,
Reference numeral 34 is a code determination unit, 35-1, 35-2, ..., 35-N are correlation units (1), (2), ..., (N), 36 is a conversion unit, and 37 is an information signal. is there.

The multilevel spread modulation signal received from the antenna 31 is converted into a baseband band by passing through the frequency conversion section 32, and is converted into a multilevel spread signal through the secondary demodulation section 33. The converted multi-value spread signal is used in the correlation unit 35-1,
35-2, ..., 35-N are input and cross-correlation is taken.
Of the N correlation units, for example, 35-1 correlation units (1)
Uses a despreading code for synchronization.

Correlation unit (1): 35-1 multiplexes according to the number of zeros or the number of multiplexes in the vicinity of the synchronization point with respect to the combination of codes selected at the time of preamble at the receiving side, that is, at the time of spreading code for synchronization Correlation is performed by the despreading code for synchronization in which the absolute value of the value that can be taken is the minimum value. for that reason,
In the initial synchronization acquisition mode, the pattern before and after the cross-correlation characteristic makes the inclination before and after the synchronization point sharp, which facilitates the synchronization acquisition, and the same effect as that of the first embodiment can be obtained .

Embodiment 3. The third embodiment will be described with reference to the drawings. In this embodiment, the QPSK method, that is, the multi-level phase modulation method will be described as an example.

FIG. 14 and FIG. 15 are block connection diagrams of a direct spread spectrum communication system which realizes the spread code multiplexing system using the M-arry multiplexing system according to the second embodiment of the present invention. It is simplified to explain the operating principle.

First, FIG. 14 shows a transmitter 46, in which 38 is an information signal, 39 is a conversion unit for converting a serial signal into a parallel signal, 40 is a code selection unit, 41-1, 41-2, …
……, 41-r is the diffusion part (1), (2), ………,
(R), 42 is an adder, 43 is a secondary modulator, 44 is a frequency converter, and 45 is an antenna.

Now, assuming that the number of multiplexes is r, the conversion unit 39
Then, the serial signal is converted into the parallel signal for each r × log ₂ M pieces of data. The converted r × log ₂ M parallel signals are divided into log ₂ M parallel signals by the code selection circuit 40, one code is selected from the M codes for each parallel signal, and r code is selected. Select a combination. Based on the selected combination, r diffusion units 41-1, 41-2, ..., 41
At -r, spread by the selected orthogonal code.
Of the r spreading units, for example, the spreading unit (1) 41-1 uses the spreading code for synchronization to perform the multiplexing process.

R diffusion sections 41-1, 41-2, ..., 4
The parallel signals spread by 1-r are multiplexed in the adder 42 and converted into a multilevel spread signal. After this , 2
Secondary modulation section 43 receives secondary modulation. Then, the frequency conversion unit 44 converts the frequency to a desired frequency and transmits the frequency 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 is a correlation unit (1), (2), ..., (N), 52
Is a converter, and 53 is an information signal.

The multilevel spread modulation signal received from the antenna 47 is converted into the baseband band by passing through the frequency converting section 48, and is converted into the multilevel spreading signal through the secondary demodulating section 49. The converted multilevel spread signal is used in the correlation units 51-1, 5
1-2, ………, 51-N is input and cross-correlation is taken. Of the N correlation units, the despreading code for synchronization is used for the correlation unit (1) 51-1, for example.

Correlation unit (1): 51-1 performs, in the vicinity of the synchronization point, zero or multiplex according to the number of multiplexes with respect to the combination of codes selected at the time of preamble on the transmitting side, that is, at the time of spreading code for synchronization . Correlation is performed with a synchronization despreading code in which the absolute value of possible values is the minimum value. Therefore, in the initial synchronization acquisition mode, the pattern before and after the cross-correlation characteristic makes the inclination before and after the synchronization point sharper and facilitates the synchronization acquisition, and the same effect as that of the first embodiment can be obtained.

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

As described above, according to the embodiment of the present invention, the cross-correlation characteristic with the multilevel spread code after multiplexing the code selection in the code multiplex communication is zero or the number of multiplexes before and after the zero shift. By using a combination of codes having the smallest absolute value and utilizing the signal pattern of the preamble signal, there is an effect of accelerating the initial synchronization acquisition during the preamble.

Further, by setting the absolute value of zero or the multiplex number to the minimum value before and after the zero shift, there is an effect of accelerating the synchronization holding after the initial synchronization acquisition without requiring a complicated circuit configuration.

[0064] As a result, it is possible to increase also the also the effective transmission rate when temporal change in the frame structure is shorter environments often.

[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, information signals are processed by spread codes on the transmitting side and synchronization is performed by spread codes for synchronization. When processing the signal, the synchronization spreading code and other
To obtain a synchronization method in spread spectrum communication that can easily establish synchronization by performing multiplex processing with a combination of codes whose cross-correlation characteristics with the received multiplex signal multiplexed with the above code are zero near the synchronization point. You can

According to the second aspect of the present invention, in direct spread spectrum communication for speeding up by multiplexing a plurality of spread codes, information signals are processed by the spread codes on the transmitting side and synchronization signals by the spread codes for synchronization are used. In processing
Synchronous spreading code and other code during synchronous signal processing on the receiving side
Code with respect to the cross-correlation characteristics with the received multiplex signal multiplexed by the number code, the absolute value of the value that can be obtained by the multiplexing according to the number of multiplexing in the vicinity of the synchronization point is the minimum value. By performing multiplex processing in, it is possible to obtain a synchronization method in spread spectrum communication that can easily achieve synchronization establishment.

According to the third aspect of the invention, in direct spread spectrum communication for speeding up by multiplexing a plurality of spread codes by using a parallel combination method, processing of an information signal by the spread code on the transmitting side and spread for synchronization. When processing the synchronization signal by the code, when processing the synchronization signal on the receiving side
Between the spread-spectrum code and the received multiplexed signal multiplexed with another code
By performing multiplex processing with a combination of codes whose cross-correlation characteristics are zero near the synchronization point, it is possible to obtain a synchronization method in spread spectrum communication that can easily achieve synchronization establishment.

According to the fourth aspect of the invention, in direct spread spectrum communication aiming at speeding up by multiplexing a plurality of spread codes by using a parallel combination method, information signals are processed and spread for synchronization by spread codes on the transmitting side. When processing the synchronization signal by the code, when processing the synchronization signal on the receiving side
Between the spread-spectrum code and the received multiplexed signal multiplexed with another code
Multiplexing according to the number of multiplexes near the synchronization point with respect to cross-correlation characteristics
By performing multiplex processing with a combination of codes whose absolute values can be minimized, it is possible to obtain a synchronization method in spread spectrum communication that can easily achieve synchronization establishment.

According to the fifth aspect of the present invention, in direct spread spectrum communication in which the speed is increased by multiplexing a plurality of M-arry spread codes, information signals are processed by spread codes on the transmission side and spread codes for synchronization are used. When processing the synchronization signal, the synchronization spread code during synchronization signal processing on the receiving side
Spread spectrum communication that can easily establish synchronization by performing multiplex processing with a combination of codes whose cross-correlation characteristics between the received multiplex signal and other received signals are zero near the synchronization point. synchronization method in can be obtained.

According to the sixth aspect of the present invention, in direct spread spectrum communication for speeding up by multiplexing a plurality of M-arry spread codes, information signals are processed by spread codes on the transmission side and spread codes for synchronization are used. When processing the synchronization signal, the synchronization spread code during synchronization signal processing on the receiving side
Of cross-correlation between received signal and received signal multiplexed with other code
With respect to the
It is possible to obtain a synchronization method in spread spectrum communication that can easily achieve synchronization by performing multiplex processing with a combination of codes having the smallest absolute value of possible values .

[Brief description of drawings]

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

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

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

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

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

FIG. 8 is a numerical diagram showing cross-correlation characteristics 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 DLL cross-correlation characteristics according to the first embodiment of the present invention.

FIG. 11 is an S of DLL according to the first embodiment of the present invention.
The characteristic view which shows a curve characteristic.

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

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

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

FIG. 15 is a configuration diagram showing a receiver using the M-arry multiple spreading system according to Embodiment 3 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 modulation unit, 6, 28, 44 transmitter side frequency conversion unit, 7, 29, 45 transmitter side antenna, 8, 30,
46 transmitter, 9, 31, 47 receiver side antenna, 1
0, 32, 48 receiver side frequency converter, 11, 33, 4
9 secondary demodulation unit, 12 determination unit, 13-1 to 13-r, 35
-1 to 35-N, 51-1 to 51-N correlation part, 14, 36, 5
2 P / S conversion unit, 15, 37, 53 reception side information signal, 16, 54, 55 receiver, 34, 50 code determination unit.

Claims (6)

(57) [Claims] 1. A synchronization method in direct spread spectrum communication in which an information signal is spread spectrum by a spread code for communication, wherein a plurality of spread codes for processing the information signal are multiplexed, and at the same time according to the information signal. Spreading modulation is performed on the transmitting side using the transmitted synchronizing signal and at least one synchronizing spreading code, and despreading is performed on the receiving side, so that synchronization is obtained according to the synchronizing correlation characteristic on 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 synchronization on the transmitting side, it should be performed at the time of processing the synchronizing signal on the receiving side.
And the received multiplexed signal multiplexed with another code
A method of synchronization in spread spectrum communication characterized by performing multiplex processing with a combination of codes whose cross-correlation characteristics of are zero near the synchronization point. 2. A synchronization method in direct spread spectrum communication in which an information signal is spread spectrum by a spread code for communication, wherein a plurality of spread codes for processing the information signal are multiplexed, and at the same time according to the information signal. Spreading modulation is performed on the transmitting side using the transmitted synchronizing signal and at least one synchronizing spreading code, and despreading is performed on the receiving side, so that synchronization is obtained according to the synchronizing correlation characteristic on 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 synchronization on the transmitting side, it should be performed at the time of processing the synchronizing signal on the receiving side.
And the received multiplexed signal multiplexed with another code
The cross-correlation characteristics of the multiple
A synchronization method in spread spectrum communication characterized by performing multiplex processing with a combination of codes that minimizes the absolute value of the values that can be obtained by duplication . 3. A synchronization method in direct spread spectrum communication for performing spread spectrum communication of an information signal with a spread code, wherein a plurality of spread codes for processing the information signal are multiplexed using a parallel combination method, and Spreading modulation is performed on the transmitting side using a synchronization signal transmitted in accordance with the information signal and at least one spreading code for synchronization,
In addition, by performing despreading on the receiving side, synchronization is obtained according to the synchronization correlation characteristic of the receiving side, in the processing of the information signal by the spreading code and the synchronization signal by the synchronizing spreading code on the transmitting side. In processing, the synchronization spread code and other codes at the time of processing the synchronization signal on the receiving side
A synchronization method in spread spectrum communication, wherein multiplexing processing is performed by a combination of codes whose cross-correlation characteristics with a multiplexed received multiplexed signal are zero near the synchronization point. 4. A synchronization method in direct spread spectrum communication for performing spread spectrum communication of an information signal with a spread code, wherein a plurality of spread codes for processing the information signal are multiplexed using a parallel combination method, and Spreading modulation is performed on the transmission side using a synchronization signal transmitted at the same time as the information signal and at least one spreading code for synchronization, and despreading is performed on the reception side to obtain correlation characteristics for synchronization on the reception side. Accordingly, in the processing for synchronizing the information signal by the spreading code and the processing for the synchronizing signal by the synchronizing spreading code on the transmitting side, the synchronizing spreading code and other codes at the time of processing the synchronizing signal on the receiving side are often used.
Regarding the cross-correlation characteristics with the multiplexed received multiplex signals, the spectrum is characterized by performing multiplex processing with a combination of codes that minimizes the absolute value of the value that can be obtained by multiplexing according to the number of multiplexes in the vicinity of the synchronization point Synchronization method in spread communication. 5. A synchronization method in direct spread spectrum communication in which an information signal is spread spectrum by a spread code for communication, wherein a plurality of M-arry spread codes for processing the information signal are multiplexed and the information signal is multiplexed. According to the synchronization correlation characteristic of the receiving side by performing the spreading modulation on the transmitting side using the synchronizing signal and the at least one spreading code for synchronization, and despreading on the receiving side. In synchronization, in the processing of the information signal by the spread code on the transmitting side and the processing of the synchronization signal by the spreading code for synchronization, the synchronization signal processing on the receiving side
Received by multiplex with synchronous spreading code and other code
A synchronization method in spread spectrum communication characterized by performing multiplex processing with a combination of codes whose cross-correlation characteristics with a multiple signal are zero near the synchronization point. 6. A synchronization method in direct spread spectrum communication in which an information signal is spread spectrum by a spread code for communication, wherein a plurality of M-arry spread codes for processing the information signal are multiplexed, and the information signal is also multiplexed. According to the synchronization correlation characteristic of the receiving side by performing the spreading modulation on the transmitting side using the synchronizing signal and the at least one spreading code for synchronization, and despreading on the receiving side. In synchronization, in the processing of the information signal by the spread code on the transmitting side and the processing of the synchronization signal by the spreading code for synchronization, the synchronization signal processing on the receiving side
Received by multiplex with synchronous spreading code and other code
Regarding the cross-correlation characteristics with multiple signals ,
A synchronization method in spread spectrum communication characterized by performing multiplex processing with a combination of codes having the smallest absolute value of the values that can be obtained by appropriate multiplexing .