JP3432419B2 - Spread spectrum communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission system that modulates a predetermined spread code with an information signal and transmits a spread spectrum signal generated by further modulating a carrier wave with the modulated signal, and a spectrum of this spectrum. The present invention relates to a spread spectrum communication system including a spread signal as an input signal and a receiving system for demodulating the information signal from the input signal.

[0002]

2. Description of the Related Art In recent years, spread spectrum (SS) is highly resistant to noise and excellent in confidentiality.
Communication systems have begun to attract attention, and along with this, the development of transmission / reception devices thereof is in progress.

Generally, in an SS communication system, an SS signal to be a transmission signal is obtained by first-modulating a predetermined code sequence having a predetermined high bit rate with an information signal, and then using the modulated signal to generate a carrier wave. It is generated as a spread spectrum signal in a wide frequency band by secondary modulation.

In this case, the above code sequence includes, for example,
Pseudo Random Noise (hereinafter abbreviated as PN) code sequence or Gold code sequence, and SS modulation include direct modulation (Direct Sequence, hereinafter abbreviated as DS) or frequency hopping ( Frequency Hopping, hereinafter abbreviated as FH method)
Etc.

In such an SS communication system,
When the transmission system performs SS modulation by the DS method using, for example, a PN code sequence, the reception system demodulates the SS signal, and the PN code used for SS modulation in the transmission system is used. The same PN code is used, and when the received SS signal matches this PN code pattern, it is taken out as an information bit signal.

Since the PN code is composed of a large number of chips (called chips to distinguish it from bits of information), the correlation between different PN codes is very small. Same PN as when modulating signal
By multiplying by the sign, it is possible to extract only the components of the correlated transmission signal.

[0007] The SS signal thus SS-modulated by a predetermined code has a considerably wide frequency band used for communication as compared with the frequency band in a normal communication system. Strengthen against signal interference and interference noise in the area,
Since the power spectrum density is low and the signal confidentiality is excellent, there are advantages such as being hard to be intercepted.

In addition, S using a predetermined code such as a PN code
Since it is a system that performs S modulation and SS demodulation, there is no need to worry about frequency allocation to avoid interference as in a normal communication system, and the problem of insufficient frequency allocation due to an increase in communication stations is solved. It has an advantage and is utilized for military communication or satellite communication by utilizing such characteristics.

In such spread spectrum communication as well, it is desired to use time division multiplexing, block error correction, etc. together in order to improve communication efficiency and reliability.
When performing time division multiplexing or the like, it is necessary to add a frame pattern in the transmission system and perform frame synchronization processing in the reception system in order to transmit the information signal in frame units.

As a conventional spread spectrum communication system for performing time division multiplexing, for example, a system generally composed of a transmission system A and a reception system B as shown in the functional block diagrams of FIGS. 8 and 9 is generally used. is there.

In the transmission system A of FIG. 8, the transmission data 7 is written in the speed conversion buffer 19 in accordance with the write address synchronized with the transmission frame timing 5 sent from the buffer controller 18, and the read address synchronized with the buffer read clock. Is read out and sent to the multiplexer 6. The buffer read clock is a clock 20a generated by the clock generator 20, is synchronized with the transmission clock 2, and has a frequency higher than the transmission clock 2 by the rate of the frame pattern. The data read from the speed conversion buffer 19 and sent to the multiplexer 6 is multiplexed in the multiplexer 6 with the frame pattern synchronized with the read address output from the frame pattern generator 4. The output of the multiplexing unit 6 is multiplied by the spreading code generated by the spreading code generator 3 in the multiplier 8 to spread the data. The spread code clock 20b is generated by the clock generator 20 at the spread rate times the buffer read clock. The spread data is modulated wave 1 by modulator 9.
It is converted to 0 and output to the outside. 10 (a) to 10 (k)
The input / output timing chart of each circuit is shown in FIG.

In the receiving system B shown in FIG. 9, the modulated wave 11 is input and the demodulator 12 converts it into a baseband signal. This baseband signal is processed by the spectrum despreading processing unit 13,
The data is despread using the same spreading code as in the transmission system A, and the despread data is input to the frame synchronization unit 16 and the speed conversion buffer 21. At the same time, the spectrum despreading processing unit 13 causes the speed conversion buffer 2 synchronized with the despread data.
1 Write clock is generated and sent to the clock generator 23. Further, the frame synchronization unit 16 establishes the frame synchronization of the despread data and sets the frame timing to the buffer control unit 2.
Output to 2. The despread data is buffer control unit 2
2 is written in the speed conversion buffer 21 according to the write address synchronized with the frame timing.
The reading of the buffer is performed in synchronization with the write clock generated by the clock generation unit 23, at the reception clock lower by the rate of the frame pattern, and is output according to the read address output by the buffer control unit 22. The buffer control unit 22 also outputs the reception frame timing 17 synchronized with the read address.

[0013]

By the way, in the case of performing such multiplexing of frame patterns, both the transmission system A and the reception system B have a speed conversion buffer, a buffer control unit, a buffer writing and reading clock generation unit. There is a problem that the circuit becomes complicated because it becomes necessary.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a spread spectrum communication system capable of realizing frame synchronization with a simple circuit.

[0015]

A transmitter according to claim 1 of the present invention is used in a spread spectrum communication system.
A transmitter that uses a spread clock from the transmit clock.
Generated clock generator and output of the above clock generator
Spread code generator for generating spread code in synchronization with clock
And a frame pattern is generated from the transmission frame timing.
Generating frame pattern generator and the spread code generator
And a multiplexing unit for multiplexing the output of the frame pattern generation unit
And the output of the above-mentioned multiplex part and the transmission data input are multiplied.
A multiplier and a modulator that converts the output of the multiplier into a modulated wave.
And a stage, so as to transmit the modulated wave from the modulation means
It is the one.

According to a second aspect of the present invention, there is provided a transmitting apparatus ,
It is a transmitter used in the spectrum spreading communication system.
A clock that generates a spread clock from the transmit clock
In synchronization with the output clock of the generator and the clock generator
And a transmission sub-data generator
Data and sub clock based on the transmission clock.
Sub-data generator, the spread code generator and sub-data generator
A multiplex part that multiplexes the output of the synthesis part and the output of the multiplex part
The multiplier that multiplies the transmission data input and the multiplier
And a modulation means for converting the output into a modulated wave.
It is obtained so as to transmit the modulated wave from the stage.

The receiving apparatus according to claim 3 of the present invention is a receiver .
It is a receiving device used in the spread spectrum communication system.
A demodulator that receives and demodulates the data of the modulated wave obtained by performing the spreading process with the spreading code, and converts the demodulated data into a baseband signal,
The output of the demodulator is despread and the received data and
Spectrum despreading processor that outputs a clock
Detect frame pattern from band signal and received clock
And a frame synchronization unit that outputs the reception frame timing
The provided is the ash to obtain a reception frame timing from the frame synchronization unit.

The receiving apparatus according to claim 4 of the present invention, scan
It is a receiving device used in the spread spectrum communication system.
A demodulator that receives and demodulates the data of the modulated wave obtained by performing the spreading process with the spreading code, and converts the demodulated data into a baseband signal,
The output of the demodulator is despread and the received data and
Spectrum despreading processor that outputs a clock
The received sub data is detected from the band signal and the received clock.
Equipped with a sub-beta output section that outputs the
It is the ash to obtain a received sub-data from the period unit.

The receiver according to claim 5 of the present invention is a contractor.
In the receiver according to claim 3, the output of the demodulator is
In the latter stage of the spectrum despreading processing unit that performs despreading processing,
The phase of the baseband signal output from the spectrum despreading unit is determined, and the phase of the received data is controlled according to the determination result to eliminate the phase uncertainty of the demodulator.
That in the phase control section is provided, it is the ash so as to remove the phase ambiguity of the demodulator.

The spread spectrum communications system of claim 6 of the present invention includes a clock generator for generating a spread spectrum clock from the transmission clock, the spreading code generator for generating a spreading code in synchronization with the output clock of the clock generator A vessel,
A frame pattern generating section for generating a frame pattern from transmission frame timing; a multiplexing section for multiplexing the spreading code generator and the output of the frame pattern generating section; and a multiplier for multiplying the output of the multiplexing section with the transmission data input. , a transmission apparatus and a modulation means for converting the multiplier output to the modulation wave, a demodulator for converting the modulated wave into a baseband signal, the receive clock and the received data to despreading processing outputs of the demodulators spectral despreading process unit for outputting, in which a receiving apparatus and a frame synchronization unit for outputting a received frame timing detecting a frame pattern from the baseband signal and the reception clock.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. 1 and 2 are functional block diagrams of a transmission system A and a reception system B of the spread spectrum communication system according to the first embodiment of the present invention. The transmission system A includes a clock generator 1 that generates a spread clock from a transmission clock 2, a spread code generator 3 that generates a spread code in synchronization with an output clock of the clock generator 1.
A frame pattern generator 4 for generating a frame pattern from a transmission frame timing 5, a multiplexer 6 for multiplexing the output of the spread code generator 3 and the frame pattern generator 4, an output of the multiplexer 6 and an input of transmission data. And a modulator 9 for converting the output of the multiplier 8 into a modulated wave 10 (FIG. 1). On the other hand, the receiving system B is a demodulator 12 for converting the received modulated wave 11 into a baseband signal, and a spectrum despreading for despreading the output of the demodulator 12 and outputting received data 14 and a received clock 15. It includes a processing unit 13 and a frame synchronization unit 16 that detects a frame pattern from the baseband signal and the reception clock 15 and outputs a reception frame timing 17 (FIG. 2).

Next, the operation of the spread spectrum communication system having the above configuration will be described with reference to the functional block diagrams of FIGS. 1 and 2 and the timing chart (transmission system) of FIG. In the transmission system A, the clock generator 1 synchronizes with the transmission clock 2 (FIG. 3B) and generates a spread clock (FIG. 3G) that is twice the spread rate of the transmission clock 2. The spread code generator 3 generates a spread code (FIG. 3 (h)) from the spread clock and outputs it to the multiplexer 6. In the frame pattern generator 4, the transmission frame timing 5 (see FIG.
A frame pattern (FIG. 3 (i)) synchronized with (f)) is generated and output to the multiplexer 6. Here, the frame pattern length is 2 (F0, F1 in the figure), and the frame pattern (F'0, F'1) is generated at each transmission frame timing 5. The multiplexing unit 6 multiplexes the input spreading code and the frame pattern ((F0, F1) or (F'0, F'1)) at a constant ratio and outputs the multiplexed signal to the multiplier 8. In the multiplier 8,
Data is spread by multiplying this output (FIG. 3 (j)) and the transmission data 7 (“N−1”, “0”, “1”, etc. in FIG. 3 (d)). The spread data (FIG. 3 (k)) is converted into a modulated wave 10 by the modulator 9 and output to the outside.

In the receiving system B, the input modulated wave 11
Is converted into a baseband signal by the demodulator 12. This baseband signal is despread by the spectrum despreading processing unit 13 using the same spreading code as that of the transmission system A. However, despreading processing is not performed on the portion of the baseband signal where the frame pattern is multiplexed. The despread data is output as the reception data 14, and the cycle of the spreading code detected by the spectrum despreading processing unit 13 is output as the reception clock 15. The baseband signal and the frame pattern position detected by the spectrum despreading processing unit are input to the frame synchronization unit 16 and, after establishing frame synchronization, output as the reception frame timing 17.

Further, by sufficiently reducing the multiplexing ratio of the frame pattern, the reduction of the spreading gain caused by replacing a part of the spreading code with the frame pattern is reduced.

Embodiment 2. In the first embodiment, the case where a part of the frame pattern is multiplexed with the spread code has been described, but in the second embodiment, as shown in FIG. 4 and FIG. This circuit realizes sub data transmission.

4 and 5, reference numeral 24 is transmission sub-data, 25 and 27 are sub-data interface sections used in place of the frame pattern generation section 4 and the frame synchronization section 16, and 26 is reception sub-data. Transmission system A
Then, based on the transmission clock 2 and the transmission sub-data 24, the sub-data interface section 25 outputs the sub-data, and the multiplexing section 6 multiplexes it with the spread code. In the timing chart of FIG. 3, F0 and F1 correspond to the transmission sub-data 24, and the others are the same. In the receiving system B, the sub data interface unit 27 outputs the received sub data 26 from the baseband signal.

Embodiment 3. Has been described a system for multiplexing a part frame pattern to the spreading code in the first embodiment, FIG. 6, as shown in FIG. 7, the phase system at the output side of the spectrum inverse diffusion processing section 13
The control unit 28 provided with, to determine the phase of the baseband signal by the frame synchronization section 16, the the result of the demodulator 12 by controlling the received data phase at the position <br/> phase controller 28 The phase indeterminacy may be removed. With such a configuration, it is possible to have a simple circuit configuration.
, Since it divided the phase ambiguity of the demodulator, it is possible to improve the reliability of demodulation.

[0028]

As described above, according to the invention described in claim 1, it is used in a spread spectrum communication system.
The transmitter that generates the spread clock from the transmit clock
Clock generator and the output clock of the clock generator.
A spread code generator that generates a spread code in synchronization with
Generate frame pattern from received frame timing
The frame pattern generator, the spreading code generator and the frame
A multiplexing unit that multiplexes the output of the pattern generating unit;
Multiplier that multiplies the output of the multiplexer and the input of the transmission data
And a modulation means for converting the output of the multiplier into a modulated wave.
For example, since as to transmit the modulated wave from the modulation means, you can remove the buffer and its control unit of the transmission system, can be a simple circuit structure.

According to the invention described in claim 2, spectrin
The transmitter used in the spread spectrum communication system.
Clock generator that generates a spread clock from the
The spread code is synchronized with the output clock of the clock generator.
Generated spreading code generator, transmission subdata and transmission clock
Sub data generation that generates sub data based on lock
Section, and the output of the spreading code generator and sub-data generation section
And the output of the above-mentioned multiplex part and the transmission data input
A multiplier that multiplies the force and the output of the above multiplier into a modulated wave
And a modulation means for converting. Thus transmits the modulated wave from the modulation means, in the transmission system, it can remove buffer and its control unit, can be a simple circuit structure.

According to the invention of claim 3, the spectrum
The receiver used in the spread spectrum communication system
It is a receiving device used in a spread spectrum communication system.
Receive the data of the modulated wave obtained by spreading processing with the spread code
A demodulator that demodulates and converts to a baseband signal, and
The output of the modulator is despread and the received data and the received clock are
Output spectrum despreading unit and the above baseband
Detects and receives the frame pattern from the signal and the reception clock
Equipped with a frame synchronization unit that outputs frame timing
For example, since to obtain the receive frame timing from the frame synchronization unit can be easily circuit configuration of the reception system.

According to the invention of claim 4, the spectrum
The receiver used in the spread spectrum communication system
It is a receiving device used in a spread spectrum communication system.
Receive the data of the modulated wave obtained by spreading processing with the spread code
A demodulator that demodulates and converts to a baseband signal, and
The output of the modulator is despread and the received data and the received clock are
Output spectrum despreading unit and the above baseband
Detects and outputs the received sub data from the signal and received clock
And a sub-beta output section that
Since the received sub-data is obtained from this, the buffer and its control unit in the receiving system can be deleted, and the circuit configuration can be simplified.

According to the invention of claim 5, claim 3
In the receiver described in the paragraph 1, the output of the demodulator is despread.
After the spectrum despreading unit to be processed,
Determining the phase of the baseband signal outputted from the torque despread processing unit, the result of the determination, controls the upper Symbol received data phase, the phase of removing phase ambiguity of the demodulator
Since the control unit is provided to eliminate the phase indeterminacy of the demodulator, the circuit configuration can be simplified and the reliability of the receiving system during demodulation can be improved.

According to the invention described in claim 6, in the transmitting device , the spread code is generated in synchronization with the clock generating section for generating the spread clock from the transmission clock and the output clock of the clock generating section. Spreading code generator, a frame pattern generating section for generating a frame pattern from the transmission frame timing, a multiplexing section for multiplexing the output of the spreading code generator and the frame pattern generating section, an output of the multiplexing section and transmission data It is composed of a multiplier that multiplies the inputs and a modulation means that converts the output of the multiplier into a modulated wave, and receives it.
The device , a demodulator for converting the modulated wave to a baseband signal, a spectrum despreading unit for despreading the demodulator unit to output reception data and a reception clock, and the baseband signal and the reception clock from Since it is composed of a frame synchronization unit which detects a frame pattern and outputs a reception frame timing, a simple circuit configuration can be realized.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a first embodiment of a spread spectrum communication system according to the present invention.

FIG. 3 is a timing chart showing the operation of the first embodiment of the spread spectrum communication system according to the present invention.

FIG. 4 is a block diagram showing a second embodiment of the spread spectrum communication system according to the present invention.

FIG. 5 is a block diagram showing a second embodiment of a spread spectrum communication system according to the present invention.

FIG. 6 is a block diagram showing a third embodiment of the spread spectrum communication system according to the present invention.

FIG. 7 is a block diagram showing a third embodiment of the spread spectrum communication system according to the present invention.

FIG. 8 is a block diagram showing an example of a conventional spread spectrum communication system.

FIG. 9 is a block diagram showing an example of a conventional spread spectrum communication system.

FIG. 10 is a timing chart showing the operation of a conventional spread spectrum communication system.

[Explanation of symbols]

1 clock generation unit, 2 transmission clock, 3 spreading code generator, 4 frame pattern generation unit, 5 transmission frame timing, 6 multiplexing unit, 7 transmission data, 8 multiplier, 9 modulator, 10 modulated wave, 11 modulated wave, 12
Demodulator, 13 spectrum despreading section, 14 received data, 15 received clock, 16 frame synchronization section, 1
7 reception frame timing, 18 (transmission system) buffer control unit, 19 (transmission system) speed conversion buffer, 2
0 (transmitter) clock generator, 21 (receiver)
Speed conversion buffer, 22 (reception system) buffer control section, 23 (reception system) clock generation section, 24 transmission sub-data, 25 (transmission system) sub-data interface section, 26 reception sub-data, 27 (reception system) ) Sub data interface section, 28 phase control section

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Claims (6)

(57) [Claims] 1. A spread clock is generated from a transmission clock.
Clock generator and the output clock of the clock generator.
A spread code generator that generates a spread code in synchronization with
Generate frame pattern from received frame timing
The frame pattern generator, the spreading code generator and the frame
A multiplexing unit that multiplexes the output of the pattern generating unit;
Multiplier that multiplies the output of the multiplexer and the input of the transmission data
And a modulation means for converting the output of the multiplier into a modulated wave.
Provided, characterized in that transmits the modulated wave from the modulation means
And a transmitter . 2. A spread clock is generated from a transmission clock.
Clock generator and the output clock of the clock generator.
A spread code generator that generates a spread code in synchronization with
Signal sub data and sub data based on the transmission clock
The sub-data generator for generating, the spreading code generator and the support
And a multiplexing unit that multiplexes the output of the
And a multiplier that multiplies the output of
And a modulation means for converting the output of the multiplier into a modulated wave,
JP sending the modulated wave modulated wave from the modulation means
Transmitter to collect . 3. A modulated wave data obtained by spreading processing with a spreading code is received, demodulated and converted into a baseband signal.
Received data after despreading the demodulator and the output of the demodulator
And a spectrum despreading unit that outputs a reception clock,
A frame that detects the frame pattern from the baseband signal and the receive clock and outputs the receive frame timing.
A receiving device , comprising: a frame synchronization unit, wherein the reception frame timing is obtained from the frame synchronization unit . 4. A modulated wave data obtained by spreading processing with a spreading code is received, demodulated and converted into a baseband signal.
Received data after despreading the demodulator and the output of the demodulator
And a spectrum despreading unit that outputs a reception clock,
From the above baseband signal and receive clock, receive sub data
And a sub-beta output unit that detects and outputs
And wherein the obtaining the received sub data from the serial frame synchronizer
Receiving device . 5. A space for despreading the output of the demodulator.
The spectrum despreading process described above is provided at the subsequent stage of the Ketul despreading process unit.
Determine the phase of the baseband signal output from the processing unit ,
A phase control unit for controlling the phase of the received data according to the determination result and removing the phase uncertainty of the demodulator is provided.
The receiving device according to claim 3, wherein 6. Receiving frame timing of transmission data
Side to detect the frame timing together with the received data.
In the output spread spectrum communication system, Clock generation to generate spread clock from transmit clock
DepartmentAnd the above clock generationDepartmentExpanded in synchronization with the output clock of
A spreading code generator that generates a spread code and a transmission frame type
Frame pattern that generates frame pattern from minging
Code generator, the spreading code generator and the frame pattern generator.
The multiplex part that multiplexes the output of the raw part and the output of the multiplex part
The multiplier that multiplies the transmission data input and the multiplier output
A modulation means for converting the force into a modulated wavedidSendapparatus
When, A demodulator for converting the above modulated wave into a baseband signal,
DemodulationVesselThe output is despread and the received data and receive clock are
Spectrum despreading processor that outputs the
The frame pattern is detected from the input signal and the received clock.
And a frame synchronization unit that outputs the reception frame timing
PossessiondidReceiveapparatusSpect, characterized by
Le spreading communication system.