JPH09223985A - Spread spectrum communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To superimpose information on the relative position relation of two signals and to make a circuit scale small by superimposing first spread modulation signals and second spread modulation signals to mutually orthogonally crossed carrier waves and synthesizing and transmitting them. SOLUTION: Transmission data are differentially encoded by a differential modulator 11 and then, converted into plural parallel data in a serial/parallel converter 12 and spread modulation is executed in a spread modulation part 13 by different spreading codes outputted from a code generator 14 respectively. A part of the output of the spread modulation part 13 is added and synthesized in a first synthesizer 15 and the remaining output of the spread modulation part 13 is added and synthesized in a second synthesizer 16. The output of the first synthesizer 15 and the output of the second synthesizer 16 are superimposed on the mutually orthogonally crossed carrier waves and synthesized in a quadrature modulation part 17 and converted into a desired frequency by a high frequency part, the processings of amplification and filtering, etc., are performed and they are transmitted. Thus, the need of a coordinate transformation circuit and a phase detection circuit is eliminated.

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 method, and more particularly to a quadrature modulated spread spectrum communication method.

[0002]

2. Description of the Related Art A spread spectrum communication system uses a spread code sequence such as a pseudo noise code (PN code) from a normally transmitted digital signal to generate a signal having an extremely wider bandwidth than the original data. It is converted into an RF (radio frequency) signal and transmitted.

Japanese Patent Application No. 5-344920 discloses a quadrature modulated spread spectrum communication device. Japanese Patent Application No. 5-344920
In the No. 1, a system multiplexed by a plurality of spreading codes is described. FIG. 6 shows a general transmitter and FIG. 7 shows a receiver in the case of not multiplexing. In FIG. 6, transmission data is converted into parallel data of two channels of an in-phase channel (Ich) and a quadrature channel (Qch), spread-modulated by the same spreading code PN1 output from the code generator 84, respectively, It is quadrature-modulated, converted to a desired frequency, and transmitted.

In FIG. 7, on the receiving side, the carrier reproduced by the carrier reproducing circuit 91 is used to separate the received signal into Ich and Qch, and the same spreading code PN as that on the transmitting side is used.
Spreading demodulation is performed by correlating with 1, and then data demodulation is performed.

In Japanese Patent Application No. 5-344920, as shown in FIG. 8, both Ich and Qch are multiplexed by the same plurality of spreading codes, orthogonally modulated and transmitted.

[0006]

However, in the above conventional example, the in-phase channel (Ich) and the quadrature channel (Qch) are used.
Since and are spread-modulated using the same spreading code, they are very vulnerable to the deviation of the orthogonal axis and the phase / frequency deviation of the reproduced carrier, similar to normal QPSK, and require highly accurate orthogonality and reproduced carrier. Therefore, there is a problem that it is difficult to downsize the device and expensive parts are required. Further, in order to improve the phase / frequency accuracy of the reproduced carrier, the time required for carrier reproduction increases, and in packet communication in particular, there is a problem that overhead increases and throughput decreases.

[0007]

According to the present invention, transmission data is differentially coded, and a part of the differentially coded data is spread-modulated by a first group of spreading codes to obtain another parallel data. A part of the spread code is spread-modulated by a spread code of the second group different from the spread code of the first group, and the first spread modulated signal and the second spread modulated signal are placed on orthogonal carrier waves, combined, and transmitted. .

With this configuration, information is added to the relative phase relationship between two signals transmitted in parallel, the coordinate conversion circuit and the phase detection circuit are not required, and the circuit scale can be reduced. Further, since it is not necessary to perform calculations such as coordinate conversion and phase detection, the circuit can be configured with a relatively low speed and power consumption can be reduced. Furthermore, since differential encoding is performed before serial-parallel conversion, when two consecutive signals are placed on the same carrier after serial-parallel conversion, data determination is performed with a relative phase difference of 0 radian and π radian.
When two consecutive signals are placed on orthogonal carrier waves after serial-parallel conversion, the data is judged by relative phase difference π / 2 radians and 3π / 2 radians, so the influence on the other becomes small and the transmission line Other channel interference due to distortion can be suppressed.

[0009]

1 is a block diagram of a first transmission device of a spread spectrum communication device embodying the present invention. In FIG. 1, 11 is a differential modulator that differentially encodes transmission data, and 12 is a serial-parallel converter that converts input data into a plurality of parallel data. Reference numeral 13 is a spread modulator that spread-modulates a plurality of input signals by the same number of different spread codes as that of the input signals, 14 is a code generator that generates a plurality of codes, and 15 and 16 are first and second signals that add and combine the plurality of signals. The first and second combiners 17 are quadrature modulators that combine two input signals on carrier waves whose phases are orthogonal to each other.

The operation of this transmitting apparatus will be described with reference to FIG. After the transmission data is differentially encoded by the differential modulator 11, it is converted into a plurality of parallel data by the serial-parallel converter 12, and the spreading modulator 13 is converted by different spreading codes output from the code generator 14, respectively. Is spread and modulated. The spread modulator 13 is configured as shown in FIG. That is, for n input data # 1, # 2, ..., #n, n spread codes PN1, PN2, ..., PNn output from the code generator 14 are output.
Respectively, and spread modulation is performed by signal processing such as multiplication or EX-OR (exclusive OR).

A part of the output of the spread modulator 13 is added and combined by the first combiner 15, and the rest of the output of the spread modulator 13 is added and combined by the second combiner 16. First synthesizer 15
The output and the output of the second synthesizer 16 are combined on the orthogonal modulator 17 by being placed on carrier waves that are orthogonal to each other, converted into a desired frequency by a high frequency section (not shown), and subjected to processing such as amplification and filtering. , Sent.

FIG. 2 is a block diagram of a receiver of a spread spectrum communication apparatus embodying the present invention. In FIG. 2, reference numeral 21 is a frequency converter for converting a received signal into two signals having orthogonal baseband bands. The frequency converter 21 includes an oscillator, a mixer, a filter, and a phase shifter that shifts the oscillator output by 90 degrees. Reference numerals 22 and 23 denote correlators for performing a correlation calculation between the received signal and the output signal from the code generator 24, and 24 denotes a code generator that generates a desired spread code.
A demodulation unit 5 receives the correlation output and reproduces the data.
A parallel-serial converter 26 converts parallel data into serial data.

The operation will be described with reference to FIG. The received signal is subjected to processing such as amplification and filtering by a high-frequency unit (not shown), and the received signal r that remains at the input frequency or is converted to an intermediate frequency is input to the frequency converter 21, and the two received signals are orthogonal to each other. Baseband signal r _I ,
r _Q is output. Two baseband signals r _I and r _Q
Is divided into a desired number and subjected to correlation calculation with one of the spreading codes output from the code generator 24 by the correlating units 22 and 23, respectively, and the correlation values for r _I and r _Q are output.
The output of the correlator 22 and the output of the correlator 23 are both demodulator 2
5 is input to the demodulator 25, and the demodulator 25
The phase comparison of the correlation outputs corresponding to two consecutive signals input to is performed and data demodulation is performed. The parallel data demodulated by the demodulation unit 25 is converted into serial data by the parallel-serial converter 26 and output.

Now, a more detailed description will be given with reference to FIG. The two orthogonal reception signals r _I and r _Q converted into the baseband by the frequency converter 21 are each branched into a desired number n, and input to the correlator 22 and the correlator 23. The correlator 22 includes n correlators 22-1, 22-2, ..., 22-n.
, PNn, which is the same as the code used for spread modulation on the transmission side and is synchronized with the received signal, and the received signal r _I are calculated on the transmitting side. It Here, if n spread codes are orthogonal, the components modulated by other spread codes are removed from the correlation output, and only the components modulated by one spread code are extracted. Similarly, the correlator 23 has n correlators 23-
1, 23-2, ..., 23-n, each of which is equal to the code used for spread modulation on the transmission side output from the code generator 24,
Spread code PN1, PN2, ..., PNn synchronized with the received signal and received signal
Correlation calculation with r _I is performed, and only the component modulated by each spreading code is extracted.

Since the outputs of the correlator 22 and the correlator 23 are orthogonal components, the two outputs represent the phase of each correlator output. Further, since the output from each correlator is a signal differentially encoded on the transmission side, by performing phase comparison of the correlation outputs corresponding to two consecutive signals input to the transmission side serial-parallel converter 12, Data can be demodulated. That is, in the demodulator 25-2, the phase represented by the outputs of the correlators 22-1 and 23-1 is compared with the phase represented by the outputs of the correlators 22-2 and 23-2, and the data determination is made based on the phase difference. To do.
Here, if the signal modulated by the spread code PN1 and the signal modulated by the spread code PN2 on the transmission side are connected to the same input terminal of the quadrature modulator 17, the phase difference is 0 radian or π.
If the signal modulated by the spreading code PN1 and the signal modulated by the spreading code PN2 are connected to different input terminals of the quadrature modulator 17 on the transmitting side, the phase difference is determined. Data judgment is performed depending on whether it is π / 2 radians or 3π / 2 radians.

Similarly, in the demodulator 25-3, the correlator 22-
The phase represented by the outputs of 2,23-2 and the phase represented by the outputs of the correlators 22-3, 23-3 are compared, and data judgment is performed based on the phase difference. In the demodulator 25-n, correlators 22- (n-1), 23-
The phase represented by the (n-1) output is compared with the phase represented by the outputs of the correlators 22-n and 23-n, and data judgment is performed based on the phase difference. In the demodulator 25-1, the correlators 22-1, 23-
Set the phase represented by one output and the correlator 22-n, 23-n output to 1
The phases represented by the outputs delayed by the data symbols are compared, and data judgment is performed based on the phase difference.

As described above, in the demodulator 25, two continuous signals input to the transmission side serial-parallel converter 12 are converted into the quadrature modulator 1.
7 is connected to the same input terminal, data judgment is performed depending on whether the phase difference is 0 radian or π radian, and if connected to different input terminals of the quadrature modulator 17, the phase difference is π / 2.
Since data judgment is performed based on radians or 3π / 2 radians, even if components modulated by other spreading codes leak to the correlator output due to synchronization shift due to transmission path distortion or SN deterioration, the effect can be suppressed. it can.

FIG. 5 shows an embodiment in the case of 8-multiplexing. 5, the same parts as those in FIG. 1 are designated by the same reference numerals.

In FIG. 5, the transmission data is the differential modulator 1.
After being differentially encoded by 1, the serial-to-parallel converter 12 outputs 8
Different parallel codes PN1, which are converted into one parallel data # 1, # 2, # 3, ..., # 8 and output from the code generator 16 in the spread modulator 13.
Spread modulation is performed at PN2, PN3, ..., PN8. That is, the data # 1 is spread-modulated with the spreading code PN1, and the data # 1
2 is spread coded by spreading code PN2, data # 3 is spreading code
Spreading modulation is performed by PN3, and data # 8 is spreading modulation performed by spreading code PN8. Of the outputs from the spread modulator 13, # 1, # 2, #
5, # 6 are additively combined by the first combiner 15, and # 3, # 4, #
7, # 8 are added and combined by the second combiner 16, are orthogonally modulated by the orthogonal modulator 17, and are transmitted.

On the receiving side, in FIG. 2, the outputs obtained by performing the correlation calculation with the spreading codes PN1, PN2, PN3, ..., PN8 in the correlating unit 22 are spread in R1I, R2I, R3I ,. Code PN1,
PN2, PN3, ..., PN8 are calculated by R1Q, R2Q,
If R3Q ..., R8Q, then in the demodulator 25, R1I, R1Q and R2I, R2
Data is demodulated by determining whether the phase difference is 0 radian or π radian from Q, and data is demodulated by determining whether the phase difference is π / 2 radian or 3π / 2 radian from R2I, R2Q and R3I, R3Q. . Similarly, data demodulation is performed by the demodulators 25-2, 25-3, ..., 25-8 shown in FIG. In the demodulator 25-1, R8I, R8Q and R1I, R1Q delayed by one symbol are used.
Data is demodulated by determining whether the phase difference is π / 2 radians or 3π / 2 radians.

Here, the case where the number of multiplexing is 8 has been described as an example, but the number of multiplexing is not limited to this.

In addition, a signal in the baseband band is converted to analog /
By performing digital conversion, the subsequent processing can be performed digitally.

Further, the serial data is not limited to the form in which the serial data is converted into a plurality of parallel data by the serial-parallel converter and the parallel data may be transmitted without using the serial-parallel converter.

[0024]

As described above, according to the present invention,
The transmission data is differentially encoded, each data is spread-modulated with a different spreading code, a part of the data is placed on the first carrier wave, and the rest is placed on the second carrier wave orthogonal to the first carrier wave to be transmitted. The conversion circuit and the phase detection circuit are unnecessary, and the circuit scale can be reduced. Also, since there is no need to perform calculations such as coordinate conversion and phase detection,
It can be configured with a relatively low-speed circuit, and power consumption can be reduced. Further, it is possible to suppress other channel interference due to transmission line distortion.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first transmission device of a spread spectrum communication device embodying the present invention.

FIG. 2 is a block diagram showing a receiving device of a spread spectrum communication device embodying the present invention.

FIG. 3 is a block diagram showing an example of a spread modulator of a first transmitter of a spread spectrum communication device embodying the present invention.

FIG. 4 is a block diagram showing an example of a correlation unit and a demodulation unit of the receiving device of the spread spectrum communication device of the present invention.

FIG. 5 is a block diagram showing a second transmission device of the spread spectrum communication device of the present invention.

FIG. 6 is a diagram showing a transmitter of a conventional spread spectrum communication device.

FIG. 7 is a diagram showing a receiving device of a conventional spread spectrum communication device.

FIG. 8 is a diagram showing a transmitter when a conventional spread spectrum communication device is multiplexed.

[Explanation of symbols]

 11 Differential Modulator 13 Spreading Modulator 15, 16 Combiner 17 Quadrature Modulator

Claims (8)

[Claims] 1. A spread spectrum communication method for communicating with a signal spread spectrum modulated by a spread code, wherein transmission data is differentially coded, and a part of the differentially coded data is spread by a first group of spread codes. And a part of the other is spread-modulated by a spreading code of a second group different from the spreading code of the first group, and the first spreading modulation signal and the second spreading modulation signal are placed on mutually orthogonal carrier waves, A spread spectrum communication method characterized by combining and transmitting. 2. In a spread spectrum communication device for communicating with a signal spread spectrum modulated by a spread code, differential modulation means for differentially coding transmission data, and outputs of the differential modulation means by a plurality of spread codes. A plurality of spreading modulation means for spreading modulation; a first modulating means for modulating a first carrier wave by a part of the outputs of the plurality of spreading modulation means; Spread spectrum communication characterized by comprising: a second modulating means for modulating a second carrier orthogonal to the first carrier; and a transmitting means for transmitting the output of the first modulating means and the output of the second modulating means. apparatus. 3. The spread spectrum communication device according to claim 2, wherein the plurality of spread codes are substantially orthogonal to each other. 4. The spread spectrum communication device according to claim 2, wherein the plurality of spread codes are orthogonal to each other. 5. A spread spectrum communication device for communicating with a signal spread spectrum modulated by a spread code, and differential modulation means for differentially coding transmission data, and N (N> 2) of the differential modulation means. The N carriers (N> 2) for spreading modulation with N spread codes, and N1 (N1> 1) out of the N spread modulator outputs, the first carrier wave. Other than the N1 outputs of the plurality of spread modulation means outputs.
A second modulation means for modulating a second carrier wave whose phase is orthogonal to that of the first carrier wave by N2 pieces (N2 = N-N1); and the first modulator means output and the second modulator means output. A spread spectrum communication device comprising a transmitting means for transmitting. 6. A first signal and a second signal which make a received signal orthogonal to each other.
Conversion means for converting to a signal, and a first correlating means for correlating a code group and outputting a plurality of first correlation outputs, and a second signal and a spreading code group for correlating a plurality of second correlation signals. And a demodulation means for demodulating based on a phase difference of a predetermined set of the plurality of first and second correlation outputs. 7. The demodulating means outputs the first and second correlation outputs for a first spreading code and the first and second correlation outputs for a second spreading code corresponding to the first spreading code. 7. The spread spectrum communication device according to claim 6, wherein the demodulation is performed based on the phase difference between the sets. 8. A spread spectrum communication method, wherein each of a plurality of differentially encoded data is spread by different spreading codes, divided into two sets, and transmitted on carriers orthogonal to each other.