JPH04360434A - Spread spectrum transmitter and spread spectrum receiver - Google Patents

Abstract

PURPOSE:To quicken the spread spectrum transmission by generating plural spread codes with a different phase from a spread code respectively so as to send the code in parallel. CONSTITUTION:A serial base band data 201 is converted into an n-channel parallel data by a serial/parallel converter 202. On the other hand, a spread code generated by a spread code generator 203 is inputted to delay circuits 241-243 and a parallel data is modulated by modulators 251-253. A spread modulation data is added by an adder 206 analogically, converted into one channel data and the result is inputted to a multiplier 211. Then the signal is multiplied with an output a synchronization spread code generator 208, amplified by an amplifier 212 and the result is sent as a radio signal. A receiver side applies prescribed processing synchronously with the sender side and the same data as the base band data 201 is demodulated, The n-bit data is communicated in parallel in this way, the communication is attained at a speed being a multiple of (n) of the speed of the serial communication.

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.

0002

2. Description of the Related Art Spread spectrum communication is conventionally known as communication that enables multiple access using code division. In this communication, a pseudo-noise signal (PN code) with a sufficiently wider spectrum width than the baseband information signal to be transmitted is used to convert the source data into a baseband signal with a wider bandwidth than the source data, and then PSK (phase shift keying) ), FSK (frequency shift keying) modulation, etc. to form a high frequency signal and transmit it.

0003

[Problems to be Solved by the Invention] However, in the past, data was sent serially, which had the disadvantage of slow data transmission speed.

0004

According to the present invention, parallel transmission is made possible by spreading each bit of parallel data based on a plurality of spreading codes.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a spread spectrum transmitter embodying the present invention. In the figure, 201 is a serial baseband signal, 202 is a serial/parallel converter, 203 is a first spreading code generator, 241 to 243 are delay circuits, 251 to 253 are spreading modulators for channels,
206 is an adder, 207 is a synchronization circuit, 208 is a second spreading code generator (for synchronization), 209 is a local oscillator, 210
211 is a mixing circuit, 211 is a multiplication circuit, 212 is an amplifier, and 213 is a high wave output.

FIG. 2 is a block diagram of a spread spectrum receiver embodying the present invention. In the figure, 214 is a high-frequency received signal, 215 is a SAW (surface acoustic wave) convolver, 216 is a detection circuit, 217 is a peak detector, 218 is a phase comparator, 219 is a loop filter, and 220 is a VCO.
, 221 is a frequency divider, 222 is a first despreading code generator,
223 is a second despreading code generator (for synchronization), 224 is a local oscillator, 225 is a reference signal, 261 to 263 are delay circuits, 271 to 273 are despreading demodulators, 228 is a parallel/serial converter, 29 is the serial baseband data output.

The data transmission operation will be explained according to FIGS. 1 and 2.

On the transmitting side shown in FIG. 1, serial baseband data 201 is converted into n-channel parallel data by a serial/parallel converter 202 composed of a shift register or the like. In this process, the data transmission rate is 1/
It becomes n.

On the other hand, the first spreading code generated by the first spreading code generator 203 is transmitted through n types of delay circuits 241 to 24.
3 is input. The delay time is selected to be shorter than one period of the spreading code pattern, and the delay time in each delay circuit is different.

Furthermore, the second spreading code generator 208
A second spreading code is generated in synchronization with the first spreading code. The second spreading code is used to acquire and maintain synchronization with the receiving side, and has the same sequence length as the first spreading code.

Now, the n-channel parallel data output from the serial/parallel converter 202 is transmitted to the spreading modulator 251.
.about.253, spread modulation is performed using n types of spreading codes having different phases. That is, each data and the spreading code are added modulo 2. The spread modulated data is subjected to analog addition in an adder 206 and converted into one channel data.

The mixing circuit 210 mixes the output of the second spreading code generator 208 and the output of the local oscillator 209, and the multiplier 211 multiplies the output of the adder 206 and the output of the mixing circuit 210. The multiplied data is amplified by an amplifier 212 and sent as a radio signal from the duplexer to the outside via an antenna.

The receiving device shown in FIG. 2 also uses two types of despreading codes, similar to the transmitting device. The first despreading code generated by the first despreading code generator 222 is input to n types of delay circuits 261 to 263 to generate n types of despreading codes having different phases.

Furthermore, the second despreading code generator 223 generates a second despreading code in synchronization with the first despreading code.

Note that the code patterns of the first and second despreading codes on the receiving side and the delay times of the delay circuits 261 to 263 must match those on the transmitting side.

Now, when the radio signal sent out from the transmitting device is received from the above antenna and duplexer, first, the SA
The signal is input to the W convolver 215. SAW Convolver 2
15, a signal 225 obtained by mixing the outputs of the second despreading code generator 223 and the local oscillator 224 is also input, and the correlation with the received signal is taken. Peak detector 21
7 generates a peak output when a peak of correlation is detected,
From that timing, synchronization with the transmitting side is acquired.

Synchronization is maintained by a phase comparator 218 and a loop filter 21 that utilize detection of correlation between second despreading codes.
9. This is performed by a control system consisting of a VCO 220 and the like. Both the second despreading code and the first despreading code are
Generated using the output of VCO 220 as the reference timing,
Since synchronization is established, despread demodulation is performed based on the first despreading code while synchronization is maintained by the second despreading code.

Specifically, the previously generated n types of despreading codes having different phases are multiplied by the received data and subjected to despreading demodulation, thereby making it possible to obtain data of n channels. The same baseband data as the baseband data 201 can be obtained by performing parallel/serial conversion on the n-channel data obtained in this way in the same order as on the transmitting side.

In the configuration of this embodiment, the transmission rate of spread-modulated data is 1/n compared to the transmission rate of actually transmitted data, so processing gain is increased and high quality can be obtained. .

Note that by selecting an orthogonal sequence with small autocorrelation and cross-correlation as the spreading code to be used,
High quality can be obtained.

[0021] For synchronization maintenance, a delay locked loop (DLL) may be used for synchronization maintenance instead of a control system composed of a phase comparator, a loop filter, a VCO, etc.

[0022] For correlation detection, DSP (Digital Signal Pr
It is also possible to use arithmetic processing using a processor (e.g., a sliding correlator) or a sliding correlator.

As explained above, according to this embodiment, n
Since bit data is communicated in parallel, communication can be performed at n times the speed compared to serial communication.

Furthermore, since n common codes having different phases are used to spread n-bit data, it is not necessary to use n spreading codes.

Furthermore, since a common code is supplied to n delay circuits each having a different delay time, the configuration for generating n codes becomes simple.

When parallel data is processed in the receiving system and the transmitting system, the serial/parallel converter 202
, parallel/serial converter 228 is not required.

Furthermore, when the spreading code generator 203 and the despreading code generator 222 have a function of generating codes having mutually different phases in parallel, the delay circuits 241 to 243, 2
61-263 are not necessary.

[0028] Furthermore, one of the plurality of spreading and despreading codes may be used as the synchronization code. That is,
On the receiving side, by performing code synchronization based on one of the spreading codes and generating another despreading code based on the synchronization, synchronized despreading of the other despreading codes is also possible.

Next, a case where communication with an ISDN (Integrated Services Digital Network) terminal is performed using spread spectrum will be described.

FIG. 3 shows the ISDN network or I
This is a configuration diagram of an interface with an SDN terminal, in which 52 is an AMI/NRZ converter that converts an AMI code from an ISDN network or an ISDN terminal into an NRZ code, 53 is a frame decomposer that decomposes data, and 61 is the first baseband data received from the exchange control unit 2,
62 is second baseband data, 63 is third baseband data, 64 to 66 are spreading modulators, 67 to 69 are PN code generators, 70 is an adder, 71 is a local oscillator, 72 is a modulator , 73 is an amplifier, 74 is a transmission filter, 75 is a duplexer, 76 is an antenna, 77 is a convolver,
78 is a detection circuit, 79 is a peak detector, 80 is a phase comparator, 81 is a loop filter, 82 is a frequency divider, 83 is a VC
O, 84 to 86 are receiving PN code generators, 87 is a local oscillator, 88 is a demodulator, 89 is a variable amplifier, 90 is an AG
C voltage generation circuit, 91 is an IF filter, 92 is a demodulator,
93 is first baseband data, 94 is second baseband data, 95 is third baseband data, 55
56 is a frame assembly unit that assembles the first to third baseband data, and 56 is an NRZ/AMI unit that converts the NRZ code into an AMI code and outputs it to the ISDN network or ISDN terminal.
This is the conversion section.

[0031] The operation when making a call from an ISDN terminal will be explained.

When an ISDN terminal makes a call, AMI-encoded data at a bit rate of 192 Kbps (kilobits per second) arrives at the interface shown in FIG. As shown in Figure 3, at the interface AMI/NR
The Z converter 52 converts the AMI code into an NRZ code,
The frame decomposition unit 53 decomposes the multiplexed frames. A frame consists of two 64 Kbps information channels (B1 and B2 channels), a 16 Kbps control channel (D channel), and other control bits. The B channel data after decomposition is input as a baseband signal synchronized with a 64 KHz clock, and the D channel data is synchronized with a 16 KHz clock and enters the spreading modulators 64 to 66, and is multiplied by the spreading code generated by the PN code generators 67 to 69. be done. PN code generators 67, 68,
69 generates three types of spreading codes having the same sequence length, and the data of each channel is modulated by a different spreading code. The PN code for the B1 channel is PN1, the PN code for the B2 channel is PN2, and the PN code for the D channel is PN.
Set it to 3. In other words, the baseband data and PN code are
Modulo-2 addition is performed by modulators 64 to 66 to produce a spread modulated signal. Furthermore, after being analog-added by an adder 70, the signals are modulated by a modulator 72, and transmitted as radio waves from an antenna 76 via an IF amplifier 73, a transmission filter 74, and a duplexer 75.

[0033] The transmitted data is received by the ISDN network interface. The received signal is sent to the antenna 76
, are first inputted from the duplexer 75 to the SAW convolver 77. On the other hand, the code PN1 generated by the PN code generator 84 used on the transmitting side is also input to the SAW convolver 77, and the correlation with the received signal is detected. Synchronization with the transmitting side is captured based on the timing of the peak output of the correlation. The synchronization is maintained by a control system composed of a phase comparator 80, a loop filter 81, and a VCO 83, which utilize detection of the correlation of PN1. If PN1 is synchronized, PN2 and PN3 are similarly acquired.

Now, the local reference signal is obtained by multiplying the output of the local oscillator 87 by the PN code generated by the previously synchronized PN code generators 84 to 86. That is, it is multiplied by each code of PN1, PN2, and PN3 to obtain three types of local reference signals. The intermediate frequency signal obtained by mixing the received signal and the local reference signal by the demodulator 88 passes through the filter 91 and is demodulated for each channel by the demodulator 92 to generate baseband data 93, 94,
It becomes 95.

The baseband data 93, 94, and 95 are multiplexed by the frame assembly section 55, converted into AMI codes by the NRZ/AMI conversion section 56, and transmitted to the ISDN network.

B channel data and D channel data transmitted to the ISDN terminal are transmitted in the reverse flow as in the above case.

[0037]

[Effects of the Invention] As explained above, according to the present invention, it is possible to speed up spectrum communication.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a spread spectrum transmitter embodying the present invention.

FIG. 2 is a configuration diagram of a spread spectrum receiving device implementing the present invention.

FIG. 3 is a configuration diagram of a spread spectrum communication device according to another embodiment of the present invention.

[Explanation of symbols]

203 First spreading code generator 208 Second spreading code generator 215 SAW convolver 222 First despreading code generator 223 Second despreading code generator 241 Delay circuit 261 Delay circuit

Claims (10)

[Claims] 1. Generating means for generating a plurality of identical spreading codes having mutually different phases, and spreading modulating each bit of information of the plurality of bits of transmission information with each of the plurality of spreading codes generated by the generating means. A spread spectrum transmitting apparatus comprising: a modulating means; and a transmitting means for adding and transmitting information of each bit of a plurality of bits of transmission information modulated by the modulating means. 2. The generating means further generates a synchronization spreading code, and the transmitting means includes an adding means for adding information of a plurality of transmission bits modulated by the modulating means; 2. The spread spectrum transmitting apparatus according to claim 1, further comprising multiplication means for multiplying the added information by the synchronization spreading code generated by said generation means. 3. The generating means has a plurality of delay means each having a different delay time, and by supplying a common spreading code to the plurality of delay means, a plurality of spreading codes having mutually different phases are generated. 2. The spread spectrum transmitting apparatus according to claim 1, wherein a plurality of spread spectrum transmissions occur. 4. The spread spectrum transmitting apparatus according to claim 2, wherein said generating means generates a synchronization spreading code having the same code length as said plurality of spreading codes. 5. Generation means for generating in parallel a plurality of identical despreading codes having mutually different phases; and modulation means for modulating a received signal in parallel with each of the plurality of despreading codes generated by the generation means. A spread spectrum receiving device characterized by having: 6. The generating means includes means for generating a synchronization spreading code in synchronization with the plurality of despreading codes, and correlation means for correlating the synchronization spreading code with the received signal, 6. The spread spectrum receiving apparatus according to claim 5, wherein the plurality of despreading codes are generated in accordance with the correlation output. 7. The generating means has a plurality of delay means each having a different delay time, and by supplying a common despreading code to the plurality of delay means, the generation means has a plurality of despreading means having different phases. 6. The spread spectrum receiving apparatus according to claim 5, wherein a plurality of codes are generated. 8. The spread spectrum receiving apparatus according to claim 6, wherein said generating means generates a synchronization spreading code having the same code length as said plurality of despreading codes. 9. Generating means for generating a plurality of spreading codes; and a plurality of spreading means for spreading transmission information based on each of the plurality of spreading codes generated by the generating means.
and supply means for supplying each bit of transmission information of a plurality of bits to the plurality of spreading means. 10. Generating means for generating a plurality of despreading codes, despreading means for despreading based on each of the despreading codes generated by the generating means, and each of the plurality of despreading means. 1. A spread spectrum receiving apparatus comprising supply means for supplying received signals in parallel.