CN102857251A - Chip synchronization method by direct sequence spread spectrum based parallel dispreading - Google Patents

Abstract

A chip synchronization method by direct sequence spread spectrum based parallel dispreading is completed by a parallel dispreading system based on the direct sequence spread spectrum. The parallel dispreading system comprises a computer, an AD (analog-to-digital converter), a correlator and a sequence generator. Received parallel data in each channel and pseudo-random code sequences in each group extracted according to set extraction rate are subjected to correlated traversal processing, and current chip offset is judged according to correlated peak values of processed results so that chip synchronization is achieved by means of adjustment. By the chip synchronization method, chip synchronization is achieved quickly and conveniently, a computing method is simple and efficient, and difficulty in synchronization by parallel dispreading in direct sequence spread spectrum communication is overcome.

Description

A kind of chip synchronization method of parallel despreading of direct sequence spread spectrum

Technical field:

The present invention relates to the spread spectrum communication field, particularly when the up link of direct sequence spread spectrum has larger spreading ratio, adopt walk abreast a kind of chip synchronization method of despreading of pseudo random sequence.The present invention is applicable to the communications field of high-speed transfer.

Background technology:

Spread spectrum communication is applied to military communication at first since its have that capacity is large, speed is high, the signal characteristics such as easily hidden, strong security, antijamming capability be strong, and can greatly improve the availability of frequency spectrum, thereby great attraction is arranged for modern communications.Wherein most widely used is exactly direct sequence spread spectrum skill.

Along with the lifting of spread spectrum communication system spreading ratio, parallel despreading receives increasing concern.Compare traditional serial despreading, the parallel despreading of Resistant DS Spread Spectrum System has following advantage: a) adopt parallel AD device, high-speed data is received be converted into the low-speed parallel reception, and then reduce the performance requirement of AD; B) the parallel despreading under the high data rate need not RAM storage, thereby simplified apparatus, reduces complexity, shortens time-delay; C) under the high speed data transfers, adopt the part parallel sequence that receives signal can realize despreading equally.

The chip synchronization of spread spectrum communication system refers in spread spectrum communication so that the pseudo noise code of the pseudo noise code that is used for despreading that receiving terminal produces and transmitting terminal is synchronous, so that receiver goes the acknowledge(ment) signal despreading of being correlated with this pseudo noise code after synchronously.Two steps were caught and follow the tracks of in generally being divided into synchronously of pseudo noise code, considered in most cases can't obtain about prior information regularly, and therefore synchronous matter of utmost importance is to catch.Commonly used realize the serial despreading mainly contain synchronously three kinds of methods: sliding correlation method, sequence estimation method and matched filtering method.

Consider in the Resistant DS Spread Spectrum System, when adopting the serial despreading, chip synchronization take the position as the unit skew; And in parallel despreading, the skew of chip synchronization then is as unit take pseudo noise code code length and the ratio that extracts speed.So in direct sequence spread spectrum communication system, the chip synchronization of parallel despreading need to be carried out the more search of wide region to correlation peak, so that traditional method can't satisfy the synchronisation requirement of parallel despreading well.

Summary of the invention:

For phase fuzzy problem synchronous in the Direct Sequence Spread Spectrum Communication, the object of the invention is to propose a kind of chip synchronization method of parallel despreading, the method can realize the synchronous of chip quickly and easily, and then guarantees the performance of the parallel despreading of spread spectrum communication system.

Main idea of the present invention is: every channel parallel data that will receive, with the relevant treatment of making traversal by every group of pseudo-random code sequence setting the extraction yield extraction, judge the side-play amount of current chip according to the correlation peak of result, and then adjust the synchronous of realization chip.

According to above-mentioned idea, the present invention adopts following technical proposals:

A kind of chip synchronization method of parallel despreading of direct sequence spread spectrum, it is based on, and the parallel solution enlarging system of direct sequence spread spectrum finishes, and described parallel solution enlarging system comprises computer, AD analog to digital converter, correlator and sequencer; Its characteristics are, the method comprises following concrete steps:

(1) sequencer generation length is the pseudo random sequence S of l, and computer extracts by extracting speed D this pseudo random sequence S, obtains D group pseudo-random code sequence, and is kept in the memory of computer:

S _i=Dec| _D(S)，i=0，1，…，D-1；

Wherein, D is the positive integer more than or equal to 1;

(2) the AD analog to digital converter is the reception signal Y of L to length, and L=nl wherein, n are the number of times that detects synchronously, extracts by extracting speed D, obtains the D channel parallel data:

Y _j=Dec| _D(Y)，j=0，1，…，D-1

(3) the AD analog to digital converter is organized pseudo-random code sequence with D road parallel receive data, memory with D and is input to respectively correlator, makes the relevant treatment of traversal, and machine carries out summation operation and adjudicates relatively as calculated again, and formula is as follows:

$P_j={\mathrm{\Σ}}_{i=0}^{D-1}{P}_{\mathrm{ji}}={\mathrm{\Σ}}_{i=0}^{D-1}{Y}_j\⊗S_i,j=\mathrm{0,1},\·\·\·,D-1---\left(1\right)$

Wherein,

The expression related operation, P _JiThe correlated results that represents j road parallel receive data and i road pseudo-random code sequence, P _jRepresent the correlation peak sum after j road parallel receive data and D group pseudo-random code sequence travels through related operation, observation is also compared the correlation peak sum, through behind the threshold judgement, works as P _jPeak value appear at l, 2l ..., in nl sampling instant place, judge that then chip side-play amount left is the x=j position;

(4) according to the side-play amount x that obtains, the data sequence integral body that receives is adjusted the x position to the right, realize the chip synchronization of the parallel despreading of direct sequence spread spectrum.

When message transmission rate surpasses the load of single channel AD analog to digital converter, adopt multi-channel A/D analog to digital converter parallel sampling, the 1/D the when sample frequency of each AD is single AD sampling like this, and then reduce spread spectrum communication to the requirement of AD performance of devices.

Compare parallel despreading with the serial despreading to higher requirement is arranged synchronously, this is because in the serial despreading, simultaneous bias take the position as unit; And during parallel despreading, simultaneous bias with

Be unit.What the present invention proposed extracts receive data and frequency expansion sequence respectively, adopt again the algorithm of the relevant summation of traversal, can realize quickly and easily chip synchronization, and computational methods are simply efficient, solved well synchronous this difficulties of the parallel despreading of Direct Sequence Spread Spectrum Communication.

Description of drawings:

Fig. 1 use one road AD analog to digital converter to receive data by the multiplying power schematic diagram of sampling.

Fig. 2 use 4 road AD analog to digital converters to receive data by the multiplying power schematic diagram of sampling.

The traversal correlation computations flow chart of Fig. 3 chip synchronization side-play amount.

Embodiment:

The present invention will be further described below in conjunction with accompanying drawing and implementation.The present embodiment is implemented under take technical solution of the present invention as prerequisite, provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

Get D=4 in the present embodiment, as shown in Fig. 1,2,3, the chip synchronization method of the parallel despreading of a kind of direct sequence spread spectrum of the present invention, its concrete steps are as follows:

(1) length that sequencer is generated is the pseudo random sequence S of l, extracts by 4 times extraction speed, thereby obtains 4 groups of pseudo-random code sequences:

S _i=Dec| _D(S)，i=0,1，…，3；

In conjunction with single channel or multi-channel A/D analog to digital converter, by 4 times extraction speed, be that the reception signal Y of 4l extracts to length, setting herein and detecting number of times synchronously is 4, thereby obtains 4 tunnel parallel frequency expansion sequences:

Y _j=Dec| ₄(Y)，j=0，1，…，3；

(2) 4 road parallel receive data and 4 groups of pseudo-random code sequences are input to correlator, make the relevant treatment of traversal, that is:

$P_j={\mathrm{\Σ}}_{i=0}^3{P}_{\mathrm{ji}}={\mathrm{\Σ}}_{i=0}^3{Y}_j\⊗S_{i}j=\mathrm{0,1},\·\·\·,3---\left(1\right)$

Wherein,

The expression related operation, P _JiThe correlated results that represents j road parallel receive data and i road pseudo-random code sequence, P _jRepresent the correlation peak sum after j road parallel receive data and 4 groups of pseudo-random code sequences travel through related operation; Observation is also compared correlation peak, through behind the threshold judgement, works as P _jPeak value appear at l, 2l, 3l during this four sampling instants place of 4l, judges that chip side-play amount left is the x=j position;

(4) last side-play amount x according to obtaining adjusts the x position to the right with the data sequence integral body that receives, and realizes the chip synchronization of the parallel despreading of direct sequence spread spectrum.

Claims (2)

1. the chip synchronization method of the parallel despreading of a direct sequence spread spectrum, it is based on, and the parallel solution enlarging system of direct sequence spread spectrum finishes, and described parallel solution enlarging system comprises computer, AD analog to digital converter, correlator and sequencer;

It is characterized in that, the method comprises following concrete steps:

(1) sequencer generation length is the pseudo random sequence S of l, and computer extracts by extracting speed D this pseudo random sequence S, obtains D group pseudo-random code sequence, and is kept in the memory of computer:

S _i＝Dec| _D(s)，i＝0，1，…，D-1；

Wherein, D is the positive integer more than or equal to 1;

(2) the AD analog to digital converter is the reception signal Y of L to length, and wherein L=nl is the number of times that detects synchronously, extracts by extracting speed D, obtains the D channel parallel data:

Y _j＝Dec| _D(Y)，j＝0，1，…，D-1

(3) the AD analog to digital converter is organized pseudo-random code sequence with D road parallel receive data, memory with D and is input to respectively correlator, makes the relevant treatment of traversal, and machine carries out summation operation and adjudicates relatively as calculated again, and formula is as follows:

$P_j={\mathrm{\Σ}}_{i=0}^{D-1}{P}_{\mathrm{ji}}={\mathrm{\Σ}}_{i=0}^{D-1}{Y}_j\⊗S_i,j=\mathrm{0,1},\·\·\·,D-1---\left(1\right)$

Wherein,

The expression related operation, P _JiThe correlated results that represents j road parallel receive data and i road pseudo-random code sequence, P _jRepresent the correlation peak sum after j road parallel receive data and D group pseudo-random code sequence travels through related operation, observation is also compared the correlation peak sum, through behind the threshold judgement, works as P _jPeak value appear at l, 2l ..., during nl sampling instant place, judge that then chip side-play amount left is the x=j position;

(4) according to the side-play amount x that obtains, the data sequence integral body that receives is adjusted the x position to the right, realize the chip synchronization of the parallel despreading of direct sequence spread spectrum.

2. the chip synchronization method of the parallel despreading of direct sequence spread spectrum according to claim 1 is characterized in that, when message transmission rate surpasses the load of single channel AD analog to digital converter, adopts multi-channel A/D analog to digital converter parallel sampling.

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