JPH09200180A - Spread spectrum communication device - Google Patents

Abstract

(57) Abstract: A spread spectrum communication device capable of reliably extracting despread synchronization timing even when the spread ratio is low and the number of multiplexed signals is large. SOLUTION: A transmitting side amplifies a spread code 4 for despreading synchronization timing extraction by an amplification means 8, and the spread code
Selector circuit 10 for the data of each multiplexed information channel
Send by time division. The receiving side is provided with a synchronization protection means 22 for establishing synchronization of the despreading timing from the peak value of the correlation calculation result when the spreading code for despreading synchronization timing extraction is being transmitted, and for the despreading synchronization timing extraction The synchronization protection means is configured to continue to generate the despreading synchronization timing signal 23 even when the transmission of the spreading code is stopped and the data of each multiplexed information channel is transmitted. When the spreading code for despreading synchronization timing extraction is transmitted, no other spreading code that becomes noise is transmitted, so that the despreading synchronization timing can be extracted without error even in a system with a low spreading ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication device, and more particularly to a device for facilitating despread synchronization timing.

[0002]

2. Description of the Related Art In recent years, as one of LANs, a wireless LAN for wirelessly transmitting terminal data and the like has been actively used. At this time, if the bit rate of the data is high and if the data is not transmitted within the desired bandwidth when transmitted as it is, the data is serial-parallel converted and multiplexed using a plurality of channels for transmission.

A communication device for performing this wireless transmission by a spread spectrum system is known. On the sender side of this device,
A signal of each channel is modulated by using a spreading code independently assigned to each channel, and then information modulation for modulating a carrier wave by the multiplexed wave is performed and transmitted. On the other hand, on the receiving side, after demodulating the information, the signal of each channel is reproduced by despreading taking the correlation with each spreading code.

In this conventional spread spectrum communication apparatus, as shown in FIG.
Spreading codes 3-1 different from each other corresponding to -1 to 5-k
~ 3-k and spreading code generating circuit 2 for outputting spreading code 4 for extracting despreading synchronization timing, and each information channel 5-
Multiplication circuits 6-1 to 6-k for multiplying the signals 1 to 5-k and the spread codes 3-1 to 3-k, and the multiplication circuits 6-1 to 6-k.
Output of k and spreading code for despreading synchronization timing extraction 4
And an information modulation circuit 11 that multiplies the output of the addition circuit 7 by a carrier wave to modulate information, and an antenna 12 that transmits the output of the information modulation circuit 11.

In the receiver 13, an antenna 14 for receiving a signal, an information demodulation circuit 15 for demodulating the output of the antenna 14 by information, spread codes 3-1 to 3-k of the transmitter 1 and despread synchronization. Spreading code 17 same as spreading code 4 for timing extraction
1 to 17-k and spreading code for despreading synchronization timing extraction 18
A spreading code generation circuit 16 for generating a signal, and a correlator 19- for correlating the output of the information demodulation circuit 15 and the spreading codes 17-1 to 17-k.
1 to 19-k and the correlator 19- (k that correlates the output of the information demodulation circuit 15 and the spreading code 18 for despreading synchronization timing extraction
+1), a peak value detection circuit 20 for extracting the timing at which the output of the correlator 19- (k + 1) shows a peak, and a despreading synchronization timing signal 23 output from the peak value detection circuit 20.
Data holding circuits 24-1 to 24-k for latching the values of the outputs of the correlators 19-1 to 19-k when is enabled,
The signals of the information channels 5-1 to 5-k are reproduced on the basis of the outputs of the data holding circuits 24-1 to 24-k.
And a decoding circuit 26 for reproducing to -k.

In the transmitter 1 of this spread spectrum communication apparatus, when the value of the bit data of the information channels 5-1 to 5-k is "1", the multiplication circuit 6-1 to which the signal of the information channel is input. 6-k are spread code generation circuits 2
The spread codes 3-1 to 3-k input from the same are output with the same polarity, and when the value of the bit data of the information channels 5-1 to 5-k is "0", the signal of the information channel is The multiplying circuits 6-1 to 6-k to be input invert the positive and negative polarities of the spreading codes 3-1 to 3-k inputted from the spreading code generating circuit 2 and output them.

The outputs of the multiplying circuits 6-1 to 6-k are added together with the spreading code 4 for despreading synchronization timing extraction in the adding circuit 7 and multiplexed, and then multiplied by the carrier in the information modulating circuit 11. Information is modulated and transmitted from the antenna 12.

The transmitted signal is transmitted to the antenna 14 of the receiver 13
The information is demodulated by the information demodulation circuit 15 and then input to the correlators 19-1 to 19- (k + 1). Correlator 19-1
19-k are information demodulated signals and the spread code generation circuit 16
From the spread codes 17-1 to 17-k input from The correlator 19- (k + 1) correlates the information-demodulated signal with the spread code 18 for despreading synchronization timing extraction input from the spread code generating circuit 16. In this despreading, the components related to the spreading codes 17-1 to 17-k in the information demodulated signal are suppressed, and the value of the autocorrelation with the component related to the spreading code 18 for despreading synchronization timing extraction is the correlator 19-.
It is output from (k + 1).

The peak value detection circuit 20 includes a correlator 19- (k +
The peak value of the output of 1) is detected and output as the despreading synchronization timing signal 23. When the peak value is output from the correlator 19- (k + 1), the correlators 19-1 to 19-k
Similarly, the peak value of the autocorrelation for each spreading code 17-1 to 17-k is output. The data holding circuits 24-1 to 24-k latch the outputs of the correlators 19-1 to 19-k when the despreading synchronization timing signal 23 is enabled so that the respective spreading codes 17-1 to 17-1. 17
Hold the peak value of the autocorrelation for -k. The data holding circuits 24-1 to 24-k output the peak value while holding the peak value until the despreading synchronization timing signal 23 is enabled next time. The decoding circuit 26 includes a data holding circuit 24-1.
~ Information channels 5-1 to -5 based on output from 24-k
The -k signal is reproduced on the reproduction channels 25-1 to 25-k.

[0010]

However, in the conventional spread spectrum communication apparatus, when the spread ratio (the ratio of the spread bandwidth to the frequency equal to the symbol rate) cannot be sufficiently obtained due to the limitation of the bandwidth to be used, etc. However, it is difficult to identify the peak of the output from the correlator for the despreading synchronization timing spreading code. This is because when the spreading ratio is small, the autocorrelation value of the spreading code does not become so large,
This is because it is buried in the cross-correlation value of the spread codes that are multiplexed and transmitted, and as the number of spread codes that are multiplexed and transmitted increases, it becomes more difficult to identify whether or not the despread synchronization timing is achieved.

Therefore, the conventional spread spectrum communication device has a problem in that the number of multiplexed signals cannot be increased so much that the speed of data transfer cannot be increased.

The present invention solves these conventional problems, and the despreading synchronization timing can be reliably extracted even when the spreading ratio is low and the number of multiplexing is large, whereby high speed data can be obtained. It is an object of the present invention to provide a spread spectrum communication device that enables transfer.

[0013]

Therefore, in the spread spectrum communication apparatus of the present invention, the transmitting side amplifies the spreading code for despreading synchronization timing extraction, and the spreading code,
The multiplexed data of each information channel is transmitted by time division. The receiving side is provided with synchronization protection means for establishing synchronization of the despreading timing from the peak value of the correlation calculation result when the spreading code for despreading synchronization timing extraction is being transmitted, and the spreading code for despreading synchronization timing extraction is provided. Even when the transmission of the code is stopped and the data of each multiplexed information channel is transmitted, the synchronization protection means continues to generate the despread synchronization timing signal.

Therefore, when the spreading code for extracting the despreading synchronization timing is transmitted, the other spreading code that causes noise is not transmitted, so that the despreading synchronization timing can be extracted without error even in a system having a low spreading ratio. .

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention assigns to the transmitting side, spreading code generating means for generating a plurality of spreading codes, and data and information channels of a plurality of information channels. A plurality of multiplying means for multiplying the spread code, a multiplexing means for multiplexing the outputs of the plurality of multiplying means, a spread for extracting the despread synchronization timing generated by the spread data of each information channel and the spread code generating means. A spreading code generating means for generating a plurality of spreading codes identical to those on the transmitting side, and a plurality of correlating means for calculating a correlation between the received signal and each spreading code. ,
The correlation between the despreading synchronization timing signal generating means for generating the despreading synchronization timing signal from the peak value of the correlation calculation result using the spreading code for despreading synchronization timing extraction and the spreading code assigned to each information channel is calculated. Spread spectrum system including data holding means for holding the data output from the correlation means in synchronization with the despreading synchronization timing signal, and decoding means for reproducing the data of each information channel from the data held in the data holding means In the communication device, on the transmission side, amplification means for amplifying the spreading code for despreading synchronization timing extraction, and data of each information channel multiplexed with the spreading code for despreading synchronization timing extraction output from this amplification means. And a transmission selection means for transmitting in a time division manner, and the receiving side uses a spreading code for despreading synchronization timing extraction. The despreading synchronization timing is held from the peak value of the correlation calculation result and the despreading synchronization timing signal is continuously generated even if this peak value is not output. At this time, since the spreading code other than the spreading code for extracting the despreading synchronization timing is not multiplexed, the despreading synchronization timing can be accurately extracted even if the spreading ratio is low. The synchronization protection means establishes synchronization based on this timing and continues to output the despreading synchronization timing signal.

According to a second aspect of the present invention, the spreading code generating means on the transmitting side and the receiving side generate a spreading code for despreading synchronization timing extraction separately from the spreading code assigned to each information channel. The spread code for despreading synchronization timing extraction is amplified and transmitted in time division with the data of each multiplexed information channel, and on the receiving side, the despreading is performed from the correlation calculation result in the correlation means for this spreading code. The synchronization timing is extracted.

According to a third aspect of the present invention, one of the spreading codes assigned to each information channel generated by the spreading code generating means on the transmitting side and the receiving side is also used as a spreading code for despreading synchronization timing extraction. The number of spreading codes used is small, and the hardware scale of the spreading code generating means and the correlation means can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) As shown in FIG. 1, the spread spectrum communication apparatus according to the first embodiment has a transmitter 1 which is provided with mutual information corresponding to information channels 5-1 to 5-k. Spreading code generation circuit 2 that outputs different spreading codes 3-1 to 3-k and despreading synchronization timing extraction spreading code 4
And the signals of the information channels 5-1 to 5-k and the spread code 3
Multiplication circuits 6-1 to 6-k for multiplying -1 to 3-k,
An adder circuit 7 for adding the k outputs of the multiplier circuits 6-1 to 6-k, and an amplifier circuit 8 for amplifying the amplitude of the spreading code 4 for despreading synchronization timing extraction to a multiple of the number of information channels (k times).
A timing control circuit 9 for controlling the timing of switching the outputs of the adder circuit 7 and the amplifier circuit 8, a selector circuit 10 for switching and outputting the outputs of the adder circuit 7 and the amplifier circuit 8 according to the output of the timing control circuit 9, and a selector circuit.
An information modulating circuit 11 that modulates the output of 10 and an antenna 12 that transmits the output of the information modulating circuit 11 are provided.

In the receiver 13, an antenna 14 for receiving a signal, an information demodulation circuit 15 for demodulating the output of the antenna 14 by information, spread codes 3-1 to 3-k of the transmitter 1 and despread synchronization. Spreading code 17 same as spreading code 4 for timing extraction
1 to 17-k and spreading code for despreading synchronization timing extraction 18
A spreading code generation circuit 16 for generating a signal, and a correlator 19- for correlating the output of the information demodulation circuit 15 and the spreading codes 17-1 to 17-k.
1 to 19-k and the correlator 19- (k that correlates the output of the information demodulation circuit 15 and the spreading code 18 for despreading synchronization timing extraction
+1), a peak value detection circuit 20 for extracting a timing at which the output of the correlator 19- (k + 1) indicates a peak, an occurrence time of the peak value detected by the peak value detection circuit 20 and a repetition cycle thereof are detected. Even if the timing extraction circuit 21 that generates a clock that becomes the despreading synchronization timing and the peak value detection circuit 20 stops detecting the peak value and the output of the timing extraction circuit 21 disappears, the frequency and phase are the same as the clocks up to that point. Sync signal 22 which continues to output the clock signal as the despreading synchronization timing signal 23, and when the despreading synchronization timing signal 23 output from the synchronization protection circuit 22 is enabled, the correlators 19-1 to 19-k Of the data holding circuits 24-1 to 24-k for latching the output values of the data holding circuits 24-1 to 24-k Raw channel 25-1～25-
and a decoding circuit 26 for reproducing k.

In this communication device, the transmitter 1 uses the spreading code 4 for despreading synchronization timing extraction and the information channel 5-1.
Spread codes 3-1 to 3-k of ~ 5-k are transmitted in a time division manner. The timing control circuit 9 first controls the selector circuit 10 so as to continuously output the spread code 4 for despreading synchronization timing extraction a plurality of times, whereby the inverse circuit whose amplitude is amplified by k times in the amplifier circuit 8 is inverted. The spreading code 4 for spreading synchronization timing extraction is output from the selector circuit 10, and the information modulation circuit 1
1, transmitted through antenna 12.

In the receiver 13, this signal is received by the antenna 14 and demodulated by the information demodulation circuit 15, and then each correlator 19-
Output to 1 to 19- (k + 1). Each correlator performs a correlation operation using each spreading code, but since the spreading code other than the spreading code 4 for despreading synchronization timing extraction is not multiplexed in the received signal at this time, the despreading synchronization timing extraction is performed. Correlator for performing correlation calculation using the spreading code 4
Only 19- (k + 1) outputs the peak value of the autocorrelation value related to the despreading synchronization timing extraction spreading code 4 when the synchronization is achieved.

This peak value is output periodically as long as the spreading code 4 for despreading synchronization timing extraction is repeatedly sent. The peak value detection circuit 20 detects this peak value, and the timing extraction circuit 21 outputs a clock in accordance with the detection of the peak value. The synchronization protection circuit 22 establishes synchronization based on this clock and outputs the despreading synchronization timing signal 23 to the data holding circuits 24-1 to 24-k.

Next, the timing control circuit 9 of the transmitter 1
Controls so that the output of the selector circuit 10 is switched to the output of the adder circuit 7, and the selector circuit 10 multiplies the signals of the respective information channels 5-1 to 5-k by the spread codes 3-1 to 3-k. The multiplexed signals of the outputs of the multiplication circuits 6-1 to 6-k are output. This signal is the information modulation circuit 11, antenna
Sent through 12.

In the receiver 13, this signal is received by the antenna 14 and demodulated by the information demodulation circuit 15, and then each correlator 19-
Output to 1 to 19- (k + 1). Each correlator performs a correlation operation using each spreading code. Correlators 19-1 to 19-1
19-k is a spread code output from the spread code generation circuit 16
17-1 to 17-k are used to output the autocorrelation value for the spread code.

On the other hand, the correlator 19- (k + 1) uses the spreading code 4 for despreading synchronization timing extraction, and the spreading code is k
Although the correlation calculation is performed on the individually multiplexed signals, the peak value in this correlation calculation result is always smaller than the peak value when the despreading synchronization timing extraction spreading code 4 was received.

This is because, in the above case, the spreading code 4 for despreading synchronization timing extraction is amplified k times, so that it is the same as when the k spreading codes 4 for despreading synchronization timing extraction are received. , The peak value of the correlation calculation is
It is k times the maximum value of the autocorrelation value (when not amplified). On the other hand, in this case, since the correlation calculation is performed on the k multiplexed signals of the spreading codes different from the despreading synchronization timing extraction spreading code 4, the calculation result of k times the cross-correlation value between different spreading codes is obtained. Generally, the maximum value of the cross-correlation value is always smaller than the maximum value of the auto-correlation value, so this peak value is the same as when the spreading code 4 for despreading synchronization timing extraction was received. It is always smaller than the peak value.

The peak value detection circuit 20 includes a correlator 19- (k +
1) Detects the peak value output when the spreading code 4 for despreading synchronization timing extraction is received, and does not detect the peak value output when the signal in which k spreading codes are multiplexed is received. The level is set.

Therefore, when the receiver 13 starts receiving the output of the adder circuit 7 of the transmitter 1, the peak value detection circuit 20 does not output the peak value and the timing extraction circuit 21 does not output the clock. However, the sync protection circuit 22
Based on the previously established synchronization, keeps outputting the clock holding the frequency and the phase until the timing extracting circuit 21 next outputs the clock.

The data holding circuits 24-1 to 24-k latch the outputs of the correlators 19-1 to 19-k by using the clock output from the synchronization protection circuit 22 as the despreading synchronization timing signal 23 and decode them. The data conversion circuit 26 includes data holding circuits 24-1 to 24-
The signals of the information channels 5-1 to 5-k are reproduced on the reproduction channels 25-1 to 25-k based on the output from k.

As described above, in the communication apparatus of the first embodiment, when the spreading code for despreading synchronization timing extraction is transmitted, the other spreading code that causes noise is not transmitted. Therefore, the despreading synchronization timing can be extracted, and even in a system with a low spreading ratio,
It is possible to increase the number of multiplexed signals and enable high bit rate transmission.

In this embodiment, the amplification amount of the amplification means is set to k times which is equal to the number of information channels, but any number of times can be used as long as the peak value can be detected at the time of extraction of the despreading synchronization timing in the receiver. good.

(Second Embodiment) The spread spectrum communication apparatus of the second embodiment uses the spread code for despreading synchronization timing extraction as another spread code to reduce the circuit scale.

As shown in FIG. 2, this communication device has a transmitter 1 equipped with an amplifier circuit 8 for amplifying a spread code 3-k.
The receiver 13 is provided with a peak value detection circuit 20 that detects a peak value from the output of the correlator 19-k that performs despreading using the same spreading code 17-k as the spreading code 3-k. Other configurations are the same as those of the first embodiment.

In this device, the spreading code for despreading synchronization timing is also used as the spreading code 3-k on the transmitting side and the spreading code 17-k on the receiving side, and the correlator for extracting the despreading synchronizing timing is used. Is also used as 19-k. Except for that point, the configuration and operation are the same as in the first embodiment.

In the apparatus of the second embodiment, even in a system having a low spreading ratio, high bit rate transmission by multiplexing is possible, the number of spreading codes used is reduced, and the spreading code generating means and It is possible to reduce the hardware scale of the correlation means.

[0037]

As is apparent from the above description, the spread spectrum communication apparatus of the present invention multiplexes the spreading code for despreading synchronization timing with another spreading code when extracting the despreading synchronization timing. Since transmission is not performed, the despreading synchronization timing can be extracted regardless of the size of the spreading ratio, and even in a system with a low spreading ratio, the number of multiplexes can be increased to speed up data transmission.

In addition to the above effects, in the device in which the spreading code for despreading synchronization timing extraction also serves as the spreading code for information transmission, the number of spreading codes to be used is reduced and the spreading code generating means and the correlating means are used. It is possible to reduce the hardware scale.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of a spread spectrum communication device according to a second embodiment of the present invention,

FIG. 3 is a block diagram showing a configuration of a conventional spread spectrum communication device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 transmitter 2 spreading code generation circuit 3-1 to 3-k spreading code 4 spreading code for despreading synchronization timing extraction 5-1 to 5-k information channel 6-1 to 6-k multiplication circuit 7 addition circuit 8 amplification circuit 9 Timing control circuit 10 Selector circuit 11 Information modulation circuit 12, 14 Antenna 13 Receiver 15 Information demodulation circuit 16 Spreading code generating circuit 17-1 to 17-k Spreading code 18 Spreading code for despreading synchronization timing extraction 19-1 to 19 -(K + 1) correlator 20 peak value detection circuit 21 timing extraction circuit 22 synchronization protection circuit 23 despreading synchronization timing signal 24-1 to 24-k data holding circuit 25-1 to 25-k reproduction channel 26 decoding circuit

Claims (3)

[Claims] 1. A transmitting side, a spreading code generating means for generating a plurality of spreading codes, a plurality of multiplying means for multiplying each data of a plurality of information channels and a spreading code assigned to each information channel, and a plurality of multiplying means. The receiving side is provided with a multiplexing means for multiplexing the outputs of the multiplying means, and a transmitting means for transmitting the multiplexed information channel data and the spreading code for despreading synchronization timing extraction generated by the spreading code generating means. , Spreading code generating means for generating a plurality of spreading codes identical to those on the transmitting side, a plurality of correlating means for calculating a correlation between a received signal and each spreading code, and a correlation using a spreading code for despreading synchronization timing extraction Despreading synchronization timing signal generating means for generating a despreading synchronization timing signal from the peak value of the calculation result,
Data holding means for holding the data output from the correlation means for calculating the correlation with the spreading code assigned to each information channel in accordance with the despreading synchronization timing signal, and each information channel from the data held in the data holding means In a spread spectrum communication device comprising a decoding means for reproducing the data of 1., an amplification means for amplifying the spreading code for extracting the despreading synchronization timing, and a despreading synchronization timing output from the amplification means on the transmission side. A spread code for extraction and transmission selection means for transmitting the data of each of the multiplexed information channels in time division are provided, and on the receiving side, the correlation calculation result of the spread code for despread synchronization timing extraction Holds the despread sync timing from the peak value and generates the despread sync timing signal even if the peak value is no longer output Spread spectrum communication device characterized in that a synchronization protection means continue. 2. The spreading code generating means on the transmitting side and the receiving side generates the spreading code for extracting the despreading synchronization timing, separately from the spreading code assigned to each information channel. The spread spectrum communication device described in. 3. One of the spreading codes assigned to each information channel generated from the spreading code generating means on the transmitting side and the receiving side is also used as the spreading code for extracting the despreading synchronization timing. The spread spectrum communication device according to claim 1.