JP2804233B2 - Multiplexing method in spread spectrum communication. - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to frequency spread (hereinafter referred to as S
(Referred to as “S”).

[0002]

2. Description of the Related Art In recent years, development of SS communication for consumer use has been activated. In this SS communication, SS multiplex communication by code multiplexing is widely performed.

In the SS multiplex communication, the following processing is performed in order to prevent interference when communicating at the same time.

[0004] First, on the transmitting side, by using different codes,
The data is frequency-spread to a frequency band higher than the frequency band determined by the data rate and the data modulation method and transmitted.
Next, on the receiving side, the target signal is separated and received by correlating the received signal with a code corresponding to the transmitter to be received.

In such SS multiplex communication, a relatively long spreading sequence is used in order to increase the number of communication stations that can communicate simultaneously. This means that upon reception, simultaneously communicated signals of the intended signal type (ie, interfering signals)
It is necessary not only to have good autocorrelation characteristics but also to make the cross-correlation value with respect to the interference signal sufficiently small so that it can be sufficiently separated from the interference signal.

However, when a long spreading sequence is used, the frequency band that can be used is often determined by laws and regulations, so if the spreading factor for data is set to a certain value or more, it is necessary to reduce the data rate. . Further, since the correlation with this long code sequence is obtained, the scale of the correlator required on the receiving side is increased, and there is a demerit that the configuration of the receiver is complicated.

[0007] In order to eliminate such disadvantages in the related art, there has been proposed a method of taking partial correlation of spreading codes and sequentially detecting them. According to this method, once synchronization with the spreading code is established, then at a time interval shorter than the spreading sequence length,
It is possible to perform communication by modulating the spread sequence with data.

[0008]

However, in the above-mentioned conventional method, in order to establish code synchronization, (1) a large-scale correlator for obtaining a long sequence correlation is provided on the receiving side, or (2) It is necessary to take measures such as adopting a so-called sliding correlation method in which the correlation codes are sequentially shifted to search for a match, so as to increase the time until synchronization is established. According to the above (1), there is a problem that the configuration of the receiver becomes large, and according to the (2), the time until the synchronization is established becomes long.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to alleviate the correlation of long sequences, to enable the adoption of a simple configuration, and to improve the performance. It is to provide a multiplexing method in SS communication. Still another object of the present invention is to provide a multiplexing method that can adopt a simple configuration when a SAW matched filter is used as a correlator.

[0010]

According to the present invention, as described above, in order to ease correlation of a long sequence, first, a plurality of specific code strings having a certain characteristic are included. This constitutes a code in SS communication. This specific code string has a common value in all stations.
Based on such a configuration, a combination (pattern) in which a plurality of the specific code strings are arranged in a code generally has an enormous value. Then, each pattern in which the specific code sequence is arranged in the code is allocated to each transmitting station.

Each transmitting station performs spread modulation of communication data using a code in which a specific code sequence is embedded, based on the allocation pattern allocated to itself. Then, the modulated signal is transmitted.

On the other hand, on the receiving side, spread demodulation is performed using a code in which the above-mentioned specific code sequence is embedded, which is allocated to the transmitting station of the other party to be received. At this time, only the above-mentioned specific code sequence is first detected. I do. By comparing the appearance pattern of the specific code sequence obtained by this detection with the code used by the transmitting station that is the partner to receive, it is possible to detect the head of this code used for spread modulation. Become. As a result, it is possible to quickly recognize the partner transmitting station and quickly establish synchronization with a code used for spread modulation on the transmitting side.

[0013] That is, a first aspect of the present invention is a multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein Using a code of the code sequence including a plurality of specific code sequences shorter than the code length, a modulation step of performing spread spectrum modulation of data to be communicated,
A transmitting step of transmitting the signal after the spread modulation obtained in the modulation step, a signal transmitted in the transmitting step, a receiving step of obtaining a received signal, and, from the received signal, the specific code sequence. Detecting and calculating a time interval between the plurality of detected specific code strings, and performing communication based on the time interval pattern calculated in the specific code sequence time interval calculating step. And a station identifying step of identifying a station that is in use, wherein the plurality of stations use the same specific code sequence.

According to a second aspect of the present invention, there is provided a multiplexing method for simultaneously communicating with a plurality of stations using a predetermined code sequence in spread spectrum communication. Using a code of the code sequence containing a specific code string shorter than the length at a predetermined time interval, a modulation step of performing spread spectrum modulation of data to be communicated,
A transmitting step of transmitting the signal after the spread modulation obtained in the modulation step, a signal transmitted in the transmitting step, a receiving step of obtaining a received signal, and, from the received signal, the specific code sequence. A specific code string time interval calculating step of detecting and calculating a time interval of the detected specific code string; and a station performing communication based on the time interval calculated in the specific code sequence time interval calculating step. A plurality of stations using the same specific code string, and the predetermined time interval is different for each station. is there.

According to a third aspect of the present invention, in the multiplexing method for spread spectrum communication according to the first or second aspect of the present invention, the detection of the specific code string is performed by a SAW matched filter. Method.

According to a fourth aspect of the present invention, there is provided a multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication. A modulation step of performing spread spectrum modulation at a center frequency assigned to the own station, a transmission step of transmitting a signal after spread modulation obtained in the modulation step, and receiving the signal transmitted in the transmission step,
A receiving step of obtaining a received signal, an intermediate frequency converting step of converting the received signal to a different intermediate frequency by a transmitting station at a single local frequency, and converting the center frequency to a different intermediate frequency by the transmitting station, a correlation detection step of the correlation detection by the correlation detector having a center frequency corresponding to each of the intermediate frequency, only contains further following that
The invention is characterized by the above items.

That is, the fourth aspect of the present invention is an addition to the above configuration.
In addition, the speed of data to be communicated is multiplexed
This is a multiplexing method in spread spectrum communication characterized by different transmission stations .

The fifth invention, in the multiplexing method in a spread spectrum communication above Symbol present invention in order to solve the above problems, multiplexing in spread spectrum communications and performs the correlation detection by the SAW matched filter Method.

The sixth aspect of the present invention, in the multiplexing method in a spread spectrum communication above Symbol present invention in order to solve the above problems, a data rate to be a communication target, the intermediate frequency to be correlation detection at the receiving station The ratio to the center frequency is
This is a multiplexing method in spread spectrum communication characterized by having the same value in all transmitting stations.

The seventh invention, in order to solve the above problems, in the multiplexing method in a spread spectrum communication above Symbol present invention, the spectrum spreading codes, multiple stations use the same code sequence multiplexed A multiplexing method in spread spectrum communication characterized by the following.

The eighth invention is configured to solve the above problems, in the multiplexing method in a spread spectrum communication above Symbol present invention, a correlator to be used in the correlation detection step, a plurality of SAW matched filters And
A multiplexing method in spread spectrum communication characterized by including a SAW matched filter having a different center frequency but the same code sequence.

In order to solve the above problem, a ninth aspect of the present invention is a multiplexing method for simultaneously communicating with a plurality of stations using a predetermined code sequence in spread spectrum communication. Using a code of a code sequence, a modulation step of spread spectrum modulation of data to be communicated,
A transmitting step of transmitting the signal after spread modulation obtained in the modulation step, a signal transmitted in the transmitting step, a receiving step of obtaining a received signal, and a received signal obtained in the receiving step, A center frequency conversion step of converting to a plurality of intermediate frequencies in a local oscillator having means for changing the frequency, and the plurality of intermediate frequency signals,
A correlation detection step of performing correlation detection by a correlator corresponding to each center frequency.

The tenth invention, in order to solve the above problems, in the multiplexing method in a spread spectrum communication above Symbol present invention, multiple in spread spectrum communication, characterized by performing the correlation detection by the SAW matched filter Method.

The eleventh invention, in order to solve the above problems, in the multiplexing method in a spread spectrum communication above Symbol present invention, the intermediate frequency converting process, the local oscillator for converting the intermediate frequency local This is a multiplexing method in spread spectrum communication, characterized in that the frequency is changed so as to compensate for the temperature change of the center frequency of the subsequent SAW matched filter.

According to a twelfth aspect of the present invention, there is provided a multiplexing method for simultaneously communicating a plurality of stations using a predetermined code sequence in spread spectrum communication,
Data to be communicated, a modulation step of performing spread spectrum modulation at a center frequency assigned to the own station, a transmission step of transmitting a signal after spread modulation obtained in the modulation step, and a transmission step of transmitting in the transmission step Receiving the received signal, a receiving signal to obtain a received signal, the received signal obtained in the receiving step, a center frequency conversion step of converting to a single intermediate frequency in a local oscillator having a means for changing the frequency, A correlation detection step of detecting a correlation of the center frequency-converted signal by a correlator.

The invention of the thirteenth, in the multiplexing method in a spread spectrum communication above Symbol present invention, the correlation detection S
This is a multiplexing method in spread spectrum communication characterized by being performed by an AW matched filter.

The fourteenth invention, in the multiplexing method in a spread spectrum communication above Symbol present invention, the intermediate frequency converting process, the local frequency of the local oscillator for converting to an intermediate frequency, a subsequent stage of the SAW matched filter This is a multiplexing method in spread spectrum communication characterized by changing so as to compensate for a change in temperature of the center frequency.

[0028]

The code used in the first present invention always includes a specific code string. Since the specific code string is shorter than the entire code, the operation for detecting the specific code string can be performed more quickly than the operation for detecting the entire code, and the configuration for the operation is simple. It can be.

According to the second aspect of the present invention, a station can be specified only by checking a time interval at which a specific code string is detected, so that multiplex communication can be performed with a very simple configuration.

According to the third aspect of the present invention, in the first and second aspects of the present invention, since the specific code string is detected using the SAW matched filter, efficient detection can be performed.

According to the fourth aspect of the present invention, the center frequencies of the signals transmitted by the respective transmitting stations are different from each other. Further, since a code in the transmitted signal is detected by a plurality of correlation detectors provided at the receiving station and having different center frequencies, transmission is performed based on which correlation detector detects a correlation. It is possible to identify the station.

Further, according to the fourth invention, the data rate
The degree depends on the transmitting station to be multiplexed. Therefore,
Different speeds make it easier to separate between channels.
is there.

According to the fifth aspect of the present invention, the fourth aspect of the present invention
Detects a specific code string using a SAW matched filter
, Efficient detection can be performed.

According to the sixth aspect of the present invention, the data rate is changed in proportion to the center frequency of the different intermediate frequencies of the receiving station. Data rate can be easily detected.

According to the seventh aspect of the present invention, since a plurality of stations use the same code sequence, the code configuration is simplified.

According to the eighth aspect of the present invention, since a plurality of SAW matched filters include those having the same code sequence set therein, even if the center frequency of the filters is shifted, the same SAW matched filters are used. The correlation is obtained in any of the SAW matched filters among the filters in which the code sequence is set.

According to the ninth aspect of the present invention, the received signal is converted into a plurality of center frequency signals. Then, correlation is performed by a correlator having an intermediate frequency corresponding to each of the plurality of intermediate frequency signals. Here, since the intermediate frequencies are different from each other, the correlation circuits can be configured independently of each other.

[0038] According to a tenth invention, since the detection of the specific code sequence performed by using the SAW matched filter, allows an efficient detection.

[0039] According to an eleventh invention, in order to compensate for the temperature variation of the intermediate frequency of the S AW matched filter, it is necessary to change the local frequency, a variable frequency local oscillator for implementing this change in local frequency Multiplexing of spread spectrum communication is achieved by positively utilizing the function of (1).

According to the twelfth invention, the transmission signal is a spread spectrum signal having a different center frequency, so that multiplexing with less interference can be realized. Since conversion is performed, multiplexing of spread spectrum communication can be achieved with a simple circuit configuration.

[0041] According to the present invention of the thirteenth, since the detection of JP Teifugo performed using a SAW matched filter, allows an efficient detection.

According to the fourteenth aspect of the present invention, the local frequency must be changed in order to compensate for the temperature change of the intermediate frequency of the SAW matched filter. Multiplexing of spread spectrum communication is achieved by positively utilizing the function of (1).

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is an explanatory diagram of codes of a code sequence in a preferred embodiment of the present invention. As shown in FIG. 1, the code used in this embodiment is 2 ＾ 15 (= 32
768) It has a chip length. Each of the codes assigned to each of the stations includes a predetermined specific code string therein. The length of this specific code sequence is 2 ＾ 5 (= 32) chips, which is 1/1024 of the total code length.

In the present embodiment, the position where the specific code string is included in the code is 32 which is the length of the specific code string.
(Chip) is defined as a unit. That is, the position where the specific code string may be inserted into the code is 1
There are 024 locations. For example, as shown in FIG. 1, for station A, the first specific code sequence is arranged at 6400 chips from the beginning of the code, and the second specific code sequence is arranged at 12800 chips. I have. And
The third and fourth specific code strings are arranged at 22400th and 24000th, respectively. In FIG. 1, the specific code sequence is indicated by hatching.

As a result, the time interval between the first and second specific code strings is equivalent to 6400 chips, and the time interval between the second and third specific code strings is equivalent to 9600 chips. Is 160.
This is equivalent to 0 chips, and the time interval between the second and third specific code strings is equivalent to 9600 chips.

On the other hand, as also shown in FIG.
For the B station, the first specific code sequence is arranged at 9600 chips from the head of the code, and the second specific code sequence is arranged at 14400 chips. The third specific code string is arranged at the 22400th and 24000th, respectively.

As a result, the time interval between the first and second specific code strings is equivalent to 4800 chips, and the time interval between the second and third specific code strings is equivalent to 11200 chips.

That is, in this embodiment, patterns of time intervals of 6400, 9600 and 1600 are assigned to station A, and 48 patterns are assigned to station B.
Patterns at time intervals of 00 and 11200 are assigned. Then, each station performs spread spectrum modulation using a code including the specific code sequence at the assigned time interval, and transmits the obtained modulated wave.

Next, the receiving side detects this specific code string. The characteristic feature of this embodiment is that the entire code is not detected, but a specific code string having a shorter length is detected. This detection is generally performed by correlating the received signal with a code sequence generated inside the receiving device. According to the present embodiment, however, since correlation is performed only for a short specific code sequence, The scale can be reduced and the detection time can be shortened.

When the specific code string is detected, the detection interval of the specific code string is checked. For example, in FIG.
A schematic diagram of a graph representing the intensity of a correlation signal with respect to a specific code string when a signal of the A station is received is shown. Since the time interval of the peak of the correlation signal is equal to the time interval of the specific code string, measuring the time interval of the peak value means that the time interval of the specific code string has been obtained. Then, the obtained time interval is used as the time interval assigned to the station A,
This is compared with the pattern at the time intervals of 6400, 9600, and 1600 (chip). In this comparison, it goes without saying that the patterns 9600, 1600, and 6400 are considered to be the same as the above-mentioned pattern of the station A. This is because it is generally uncertain from which position a specific code string is detected. Similarly, 16
The patterns of 00, 6400, and 9600 are also determined to be station A.

When the time interval of the specific code string is detected in this manner, each station can be separated by the pattern of this time interval, and only the signal arriving at the pattern of this time interval is a desired signal. By demodulating the data independently modulated in the pattern, multiplex transmission and separation / demodulation by a plurality of stations can be performed. That is, the data to be transmitted from each transmitting station is included in a correlation output (correlation peak) signal that is detected in correlation at a time interval pattern corresponding to each station. For example, the phase of the carrier frequency forming the correlation peak is data-modulated. Although the case of receiving the communication of the station A has been described, the reception and the spread spectrum demodulation are performed in the same manner in the station B.

As described above, according to the method of the present embodiment, it is sufficient to obtain a correlation with respect to a received signal with respect to a specific code string which is a characteristic, and therefore, it is possible to reduce the scale of a correlator used in a receiver. It is. Further, a method of configuring a pulse train having different time intervals and a method of detecting a correlation are described in, for example, Optical Orthgo used for multiplexing optical communication.
It is preferable to determine by the method of nal code (hereinafter, referred to as OOC). About this OOC, for example, R. K. Chung, J.M. A. Saleh
i, and V. K. Wei, “Optical O
rthogonalCodes: Design, An
alysys, and Applications ",
IEEE Trans. Inform. Theory,
vol. 35, NO. 3, May 1989,
J. A. Salehi, "Code Division
Multiple-Access Technique
sin Optical Fiber Network
s-PartI: Fundamental Princ
iples "and the like.

In the above embodiment, the insertion position of the specific code string is fixed at a predetermined 1024 positions.
This is for making it easy to determine the insertion position of the specific code sequence, and in principle, the insertion position can be determined in units of one chip.

The predetermined code sequence including the specific coded sequence may be not only phase modulation but also amplitude modulation or a combination thereof. In other words, a modulation with an amplitude of zero may be added to a portion other than the specific column. In other words, a discontinued signal may be transmitted and received.

Further, in the present embodiment, the correlator may have any configuration.
It is preferable to apply a matched filter or the like. SA
The W matched filter can be realized with low insertion loss,
Since a power supply is not required, it is possible to contribute to lower power consumption of the device.

Second Embodiment In the first embodiment, a pattern of a specific code sequence having a different time interval is assigned to each station, and the stations are identified based on the time interval. On the other hand, as a modification of the above embodiment, it is conceivable to change the data rate for each station. That is, the specific code sequence is included at predetermined intervals in the codes assigned to each station, and the data rate is set to be different for each station.

As a result, the time interval at which the specific code sequence is transmitted, that is, the time interval at which the specific code sequence is detected, differs for each station. Therefore, the station can be identified by checking the time interval at which the specific code string is detected. The time period is not limited to an integral multiple of the code rate, but may be, for example, 1.5 times. In terms of ease of detection, it is preferable to use an integer multiple. However, if communication is to be performed with a large number of stations, there is no problem in principle to take a value other than the integer multiple.

More specifically, on the receiving apparatus side, a correlation pulse train after detection is first obtained by using a correlator such as a SAW matched filter to correlate the received signal with a specific sequence. Then, the detection cycle of the specific code sequence can be obtained based on the correlation pulse sequence. The clock is reproduced with the obtained correlation pulse period,
The multiplexed signal is separated by this clock cycle,
The reproduction of the data is performed.

As described above, according to the second embodiment, the step of correlating pulse trains having different time intervals in the first embodiment has an effect that can be easily realized by simply extracting a clock and detecting this cycle.

Embodiment 3.1 The inventors of the present invention have adopted a correlator used for SS communication as
The application of SAW matched filters has been proposed. For example, Kazuhiko Yamanouchi and Yoshihiko Takeuchi, “Low-Loss Temperature-Compensated SAW Matched Filter Using Unidirectional Electrodes”, Materials of the 40th meeting of the 150th Committee on Acoustic Wave Technology, Japan Society for the Promotion of Science Sun), Kazuhiko Yamanouchi, Yoshihiko Takeuchi,
"Temperature Deviation Correction Method for Surface Acoustic Wave Matched Filter", IEICE Technical Report US94-47 (1994-09), Yoshihiko Takeuchi, Hisaichi Takuma, Makoto Nara, Akira Tago, "Wireless LAN using SAW element" SS demodulator ”, IEICE Technical Report SST94
-19 (1994-06). This SAW matched filter can be realized with low insertion loss and does not require a power supply, and can contribute to a reduction in power consumption of the device.

However, when performing correlation detection, there is a problem that the set code cannot be easily changed.

In Embodiment 3.1, when there are a plurality of signals that need to be correlated, a plurality of SAW matched filters having different center frequencies are prepared, and the local frequency of the SS receiver is selected. The frequency is converted to the center frequency of the SAW matched filter corresponding to the target code, and a correlation output for the target code is obtained.

FIG. 3 is a partial block diagram showing the SAW matched filters 10, 12, and 14 of the receiving apparatus employing the method according to the present embodiment. As shown in FIG. 3, the received signal is subjected to frequency conversion based on the local oscillation frequency, and then the three SAW matched filters 1
0, 12, and 14. Different center frequencies are set for the respective SAW matched filters 10, 12, and 14. Further, the code sequences set in the SAW matched filters 10, 12, and 14 are different.

In the embodiment 3.1, each transmitting station outputs a transmission signal having a different center frequency. That is, a different center frequency is assigned to each transmitting station, and each transmitting station performs frequency spread modulation on data to be transmitted at the center frequency assigned to the own station, and outputs the obtained transmission signal.

A characteristic of the embodiment 3.1 is that the receiving apparatus includes SAW matched filters 10, 12, and 14 corresponding to the transmitting stations. Transmission signals having different intermediate frequencies transmitted from the respective transmitting stations are converted into signals having different intermediate frequencies by the intermediate frequency conversion. Then, the SAW matched filter 1 in which the corresponding intermediate frequency is set, respectively.
0, 12, and 14 perform correlation detection on the signal after the intermediate frequency conversion of each transmission signal. As described above, in the third embodiment.
According to No. 1, since a plurality of SAW matched filters are provided, a multiplexing method can be easily realized.

Embodiment 3.2.1 Although the relationship between the code rate and the data rate and the center frequency is not described in the above-mentioned embodiment 3.1, the center frequency and the code rate are fixed. It is also preferable to set the ratio as follows. This makes it possible to make the data rate different as mentioned in the second embodiment, to facilitate correlation (for the same reason as in the second embodiment), and to further simplify the configuration of the receiver. This has the effect of being able to achieve

Embodiment 3.2.2 In Embodiment 3.2.1, the code sequences assigned to the respective transmitting stations are different from each other as in Embodiment 3.1. However, it is also possible to use the same code sequence. That is, the multiplexing method is realized only by the fact that the center frequencies are different.
If such a configuration is adopted, all of the code sequences assigned to all the transmitting stations can be made the same, so that there is an effect that the number of transmitting stations is not limited.

Embodiment 3.3 In the above embodiment 3.1, the code rate and the code sequence set in the plurality of SAW matched filters 10, 12, and 14 are different from each other. It is also preferable to set the same one in terms of quality. FIG. 4 shows a partial configuration diagram of a receiver using a SAW matched filter in which the same code sequence is set as described above.

As shown in FIG. 4, SAW matched filters 20 and 22 to which the same code sequence A (corresponding to transmitting station A) is set are set so that their center frequencies are slightly shifted. The SAW matched filter 2 in which the same code sequence B (corresponding to the transmitting station B) is set
0 and 32 are also set so that their center frequencies are slightly shifted. Unlike the above-described embodiment 3.1, by providing a SAW matched filter having a different center frequency for the same code sequence as described above, even when the center frequency of the SAW matched filter changes with temperature, the same code sequence can be obtained. This has the effect that the correlation can be obtained by any of the SAW matched filters.

Embodiment 4 In Embodiment 3.1, it was proposed to realize a multiplexing method using a plurality of SAW matched filters. In the above case, the intermediate frequency conversion step converts the received signal into an intermediate frequency signal by a single local frequency signal.

In the case where the receiving apparatus adopts the above configuration, as described in Embodiment 3.3, generally, a change in the center frequency of the SAW matched filter due to a change in temperature becomes a problem.

Therefore, in order to compensate for the shift of the center frequency due to the temperature change, in the fourth embodiment, a method of changing the local oscillation frequency has been devised and studied by the present inventors. That is, Kazuhiko Yamanouchi, JP-A-1-123516
No. and Kazuhiko Yamanouchi, Yoshihiko Takeuchi, "Method for Correcting Temperature Deviation of Surface Acoustic Wave Matched Filter," IEICE Tech.
994-09), Yoshihiko Takeuchi and Kazuhiko Yamanouchi, "Study on Temperature Deviation Correction Method for Surface Acoustic Wave Matched Filter", Materials of the 273rd Meeting of Acoustic Engineering Research Institute of Electrical Communication, Tohoku University (1994-07). Therefore, if it is necessary to change the local oscillation frequency depending on the temperature for correlation detection, a correlator capable of detecting the correlation in accordance with the required correlation detection by actively using the means for changing the local oscillation frequency. If the local oscillation frequency is changed in accordance with the center frequency of the above, it can be realized by changing the desired correlation detection to the local oscillation frequency.

As described above, according to the fourth embodiment, various types of correlation detection can be performed using only the components of the existing spread spectrum communication apparatus, and various multiplexing methods can be realized.

Embodiment 5 FIG. 5 shows a simple spread spectrum communication in which a transmission signal is converted into a spread spectrum signal having a different center frequency and transmitted, and is converted into a single center frequency by a variable local oscillator on the receiving side. It is the schematic which showed the suitable example which shows the multiplexing method.

On the transmitting side, the data to be transmitted is converted by a code generator 40 into a spread spectrum signal. This signal is converted into an RF signal having a different frequency by a variable local oscillator 41 whose frequency can be changed, amplified by a power amplifier, and transmitted from an antenna. On the receiving side, after the spread spectrum signals of different frequencies input from the antenna are amplified by the low noise amplifier, they are converted to a single center frequency by the variable local oscillator 50 whose frequency can be changed, and the SAW matched filters 51 The correlation is obtained and a correlation output is obtained.

Here, on the transmitting side, the center frequency of the spread spectrum signal can be selected differently at each transmitting station, and multiplexing of spread spectrum communication is achieved. Here, since the center frequencies are different, there is an advantage that interference between the transmitting stations is small. Also, on the receiver side, a spread spectrum signal having a different center frequency is converted into a single intermediate frequency at a local frequency corresponding to each, so that a specific station can be selectively received, and a single center frequency can be received. Since the frequency is used, there is an advantage that the configuration of the correlator, which is a SAW matched filter here, can be simplified. In addition, if the operating temperature is detected and the oscillation frequency of the local oscillator 50 is changed to compensate for the temperature characteristics of the SAW matched filter, the oscillation frequency of the local oscillator 50 must be changeable. Has the advantage that multiplexing of spread spectrum communication can be easily measured by positively utilizing.

[0078]

As described above, according to the first aspect of the present invention, it is possible to obtain a multiplexing method in spread spectrum communication in which code synchronization can be easily achieved.

According to the second aspect of the present invention, an operation such as pattern detection is not required as in the first aspect of the present invention. Therefore, a multiplexing method in spread spectrum communication which can very easily achieve code synchronization is provided. The effect is obtained.

According to the third aspect of the present invention, since the SAW matched filter is used for the correlator, there is an effect that the multiplexing method can be efficiently realized.

According to the fourth invention, there is an effect that a multiplexing method in spread spectrum communication in which separation between channels using different code sequences can be performed more reliably is obtained.

Further, according to the fourth invention, the data rate
Because of the different degrees, different code sequences
Spread for more reliable separation between channels
There is an effect that a multiplexing method in communication can be obtained .

According to the fifth aspect of the present invention, a SAW matched
Since the filter is used for the correlator, the multiplexing method is efficient.
There is an effect that can be realized.

According to the sixth aspect of the present invention, there is an effect that a multiplexing method in spread spectrum communication in which the transmission data rate can be easily known from the intermediate frequency for which correlation is detected can be obtained.

According to the seventh aspect of the present invention, since the same code sequence is allocated to each transmitting station, there is an effect that the multiplexing method can be easily realized.

According to the eighth aspect of the present invention, since the same code sequence is set and a plurality of SAW matched filters having different center frequencies are used, even if a shift occurs in the center frequency, spread spectrum communication is possible. Is obtained in that the multiplexing method is obtained.

According to the ninth aspect , the received signal is converted into a plurality of center frequency signals. Then, correlation is performed by a correlator having an intermediate frequency corresponding to each of the plurality of intermediate frequency signals. Here, since the intermediate frequencies are different from each other, there is an effect that the correlation circuits can be configured independently of each other.

According to the tenth aspect of the present invention, since the SAW matched filter is used for the correlator, there is an effect that the multiplexing method can be efficiently realized.

[0089] According to an eleventh invention, in the above Symbol present invention, to compensate for changes in temperature of the intermediate frequency of the SAW matched filter, it is necessary to change the local frequency, realizing a change in the local frequency Thus, there is an effect that multiplexing of spread spectrum communication can be achieved by positively utilizing the function of the variable frequency local oscillator.

According to the twelfth invention, the transmission signal is a spread spectrum signal having a different center frequency, so that multiplexing with less interference can be realized. Since the conversion is performed, there is an effect that multiplexing of spread spectrum communication can be achieved with a simple circuit configuration.

[0091] According to the present invention of the thirteenth, the upper Symbol present invention, since the detection of the specific code using the SAW matched filter, there is an effect that allows an efficient detection.

[0092] According to a fourteenth invention, in the above Symbol present invention, to compensate for changes in temperature of the intermediate frequency of the SAW matched filter, it is necessary to change the local frequency, realizing a change in the local frequency Thus, there is an effect that multiplexing of spread spectrum communication can be achieved by positively utilizing the function of the variable frequency local oscillator.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of codes of a code sequence used in a preferred embodiment of the present invention.

FIG. 2 is a schematic diagram of a graph showing a change in the intensity of a correlation signal in the example.

FIG. 3 shows a plurality of SAWs of a receiving apparatus according to an embodiment 3.1.
FIG. 3 is a partial configuration diagram of matched filters 10, 12, and 14.

FIG. 4 is a diagram illustrating a plurality of Ss of a receiving apparatus according to an embodiment 3.2.1.
AW matched filters 20, 22, 24, 30, 3,
It is a partial block diagram of 2, 34.

FIG. 5 is a schematic diagram illustrating a configuration of a transmission side and a reception side of a spread spectrum communication apparatus according to a fifth embodiment.

[Explanation of symbols]

10, 12, 14, 20, 22, 24, 30, 32, 3,
4 SAW Matched Filter 40 Code Generator 41, 50 Variable Local Oscillator 51 SAW Matched Filter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-291744 (JP, A) JP-A-2-207605 (JP, A) JP-B-44-24220 (JP, B1) (58) Field (Int.Cl. ⁶ , DB name) H04J 13/00, 13/06 H04B 1/69 H04B 1/707 H04B 1/713

Claims (14)

(57) [Claims] 1. A multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein the code including a plurality of specific code sequences shorter than a code length of the code sequence. Using a sequence code, a modulation step of performing spread spectrum modulation of data to be communicated, a transmission step of transmitting a signal after spread modulation obtained in the modulation step, and a signal transmitted in the transmission step. Receiving, a receiving step of obtaining a received signal, a specific code sequence time interval calculating step of detecting the specific code sequence from the received signal, and calculating a time interval of the detected plurality of specific code sequences, Based on the time interval pattern calculated in the specific code sequence time interval calculation step, a station identification step of identifying a communicating station, A multiplexing method in spread spectrum communication characterized by using a specific code string. 2. A multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein a specific code sequence shorter than a code length of the code sequence is included at predetermined time intervals. Using the code of the code sequence, a modulation step of performing spread spectrum modulation of data to be communicated, a transmission step of transmitting a signal after spread modulation obtained in the modulation step, and a transmission step of transmitting in the transmission step. Receiving the received signal, to obtain a received signal, from the received signal, to detect the specific code sequence, a specific code sequence time interval calculation step of calculating the time interval of the detected specific code sequence, A station identification step of identifying a communicating station based on the time interval calculated in the specific code sequence time interval calculation step, wherein the plurality of stations have the same specific code. A multiplexing method in spread spectrum communication, wherein the predetermined time interval is different for each station. 3. The multiplexing method for spread spectrum communication according to claim 1, wherein the detection of the specific code string is performed by a SAW matched filter. 4. A multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein data to be communicated is spread using a center frequency assigned to the own station. A modulation step of modulating, a transmission step of transmitting a signal after spread modulation obtained in the modulation step, a reception step of receiving a signal transmitted in the transmission step and obtaining a reception signal, An intermediate frequency conversion step of converting to a different intermediate frequency by the transmitting station at one local frequency, and a correlation having a center frequency corresponding to each of the intermediate frequencies converted to the center frequency by the transmitting station. seen including a correlation detection step of the correlation detection by the detector, the speed of the data to be object of communication are multiplexed
Multiplexing method in spread spectrum communication characterized by different transmission stations . 5. The multiplexing method in spread spectrum communication according to claim 4, wherein the correlation detection is performed by a SAW matched filter. 6. The multiplexing method in spread spectrum communication according to claim 4 , wherein the ratio between the data rate to be communicated and the center frequency of the intermediate frequency detected and correlated by the receiving station is equal to all transmitting stations. A multiplexing method in spread spectrum communication, wherein 7. The multiplexing method in spread spectrum communication according to claim 6 , wherein a plurality of stations to be multiplexed with the spread spectrum code use the same code sequence. . 8. The multiplexing method in spread spectrum communication according to claim 7 , wherein the correlator used in the correlation detecting step is constituted by a plurality of SAW matched filters, and the same code sequence having different center frequencies is used. A multiplexing method in spread spectrum communication, comprising: a SAW matched filter having the same. 9. A multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein communication is performed using a code of a code sequence assigned to the own station. A modulation step of performing spread spectrum modulation on data; a transmission step of transmitting a signal after spread modulation obtained in the modulation step; a reception step of receiving a signal transmitted in the transmission step and obtaining a reception signal; A center frequency converting step of converting the received signal obtained in the receiving step into a plurality of intermediate frequencies with a local oscillator having a means for changing the frequency, and a correlation corresponding to the respective center frequencies of the plurality of intermediate frequency signals. A multiplexing method in spread spectrum communication, comprising: 10. The multiplexing method in spread spectrum communication according to claim 9 , wherein the correlation detection is performed by a SAW matched filter. 11. The multiplexing method in spread spectrum communication according to claim 9 , wherein in the intermediate frequency conversion step, the local frequency of a local oscillator for converting to an intermediate frequency is set to a SAW at a subsequent stage.
A multiplexing method in spread spectrum communication characterized by changing so as to compensate for a change in the center frequency of a matched filter with temperature. 12. A multiplexing method for simultaneously performing communication between a plurality of stations using a predetermined code sequence in spread spectrum communication, wherein data to be communicated is spread using a center frequency allocated to the own station. A modulating step of modulating, a transmitting step of transmitting a signal after spread modulation obtained in the modulating step, a receiving step of receiving a signal transmitted in the transmitting step and obtaining a received signal, A center frequency converting step of converting the received signal into a single intermediate frequency by a local oscillator having a means for changing the frequency; and a correlation detecting step of detecting the correlation of the center frequency converted signal by a correlator. A multiplexing method in spread spectrum communication, comprising: 13. The multiplexing method in spread spectrum communication according to claim 12 , wherein the correlation detection is performed by a SAW matched filter. 14. The multiplexing method in spread spectrum communication according to claim 12 , wherein in the intermediate frequency conversion step, the local frequency of a local oscillator for converting to an intermediate frequency is set to a SAW in a subsequent stage.
A multiplexing method in spread spectrum communication characterized by changing so as to compensate for a change in the center frequency of a matched filter with temperature.