CN105391455A - Return-to-zero Turbo code starting point and depth blind identification method - Google Patents

Abstract

The invention belongs to the field of Turbo code interleaving parameter blind identification, and particularly relates to a method of carrying out interleaving starting point and interleaving depth estimation on a return-to-zero Turbo code in a condition of a large interleaving depth (hundreds to thousands). According to the interleaver depth and starting point identification method based on a return-to-zero structure, a convolutional coding self return-to-zero structure existing widely in actual applications is used. Under the structure, certain structure features exist whether return-to-zero bits or an all-zero state serves as a coding sequence for a starting state. Through counting on a code word sequence, a code word structure meeting a specific structure is searched, and thus the Turbo code interleaving depth and the interleaving starting point are determined. The operation amount for the Turbo code parameter blind identification algorithm is greatly reduced, a step in which multiple nesting operation is forced to be adopted on multiple unknown parameters in the case of all-blind identification can be avoided. the identification process is separated, one-by-one parameter identification is carried out, and while the operation efficiency is improved, practical operability in identification of a large interleaving depth is also realized.

Description

A kind of zero Turbo code starting point and degree of depth blind-identification method

Technical field

The invention belongs to Turbo code interleave parameter blind recognition field, when particularly relating to larger interleave depth (hundreds of is to several thousand), zero Turbo code is carried out to the method for intertexture 7 and interleave depth estimation.

Background technology

According to Shannon's theorems, as long as rate of delivering a letter is lower than channel capacity, so along with code length levels off to infinite, necessarily exist error rate level off to zero progressive number.The Turbo code coding and decoding scheme proposed for 1993, by making full use of randomness, under the random interleaver condition of 65536, makes 1/2 Rate Turbo Codes achieve the excellent properties of distance shannon limit only 0.7dB.From then on Turbo code is widely used in wireless communication field.The meaning of Turbo code there are provided the concatenated coding scheme under a kind of low signal-to-noise ratio, and highlights the thought of iterative decoding, also has certain facilitation to the research in the fields such as channel equalization afterwards and input.Present Turbo code has been widely used in, in each large communication protocol, comprising the 3G (Third Generation) Moblie agreement of 3GPP, LTE, CCSDS etc.Wherein modal is the PCCC structure of 1/3 code check.

Parallel cascade structure (PCCC) is formed primarily of two 1/2 code check recursive systematic convolutional code (RSC) encoders and an interleaver.Input data directly enter first encoder, export a road information bit and a road check digit.Meanwhile, input data are according to certain interleave depth, and the carrying out of block-by-block interweaves in block.Data after intertexture enter second encoder, only choose a road check digit of output.Finally, three circuit-switched data enter multiplexer, and to carry out deletion multiplexing, sequence after obtaining encoding.

For the identification work of PCCC structure Turbo code, mainly concentrate on the parameter identification of the identification of component coder parameter and interleaver.In the process of blind recognition, the problem such as the start bit also relating to codeword sequence is determined, the determination of interleave depth, identification that whether component coder parameter is consistent.The uncertainty of these parameters is common factors that identification work operand is promoted.Specific to coder parameters identification, the same with convolution code identification, mainly adopt Matrix Elementary Transformation, the method such as Euclid tosses about in bed to be divided by, BM algorithm, Walsh-Hadamard conversion.And the estimation of random interleaver, mainly will interweave the mapping being one by one considered as one group of completely random, utilizes the data of multiframe to compare, thus determine the mapping relations of lower each position.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of zero Turbo code starting point and degree of depth blind-identification method are provided, make the identification of interleave parameter and interleave depth can adapt to intertexture scale larger than ever, and greatly reduce operand, raising error-resilient performance.

The present invention program is: based on interleaver depth and the starting point recognition methods of zero-reset structure, make use of the convolutional encoding of extensively existence in practical application from zero-reset structure.Under such configuration, no matter be zero bit, or using all-zero state as the coded sequence playing primary state, all there is certain architectural characteristic.By the statistics to codeword sequence, find the codeword position meeting ad hoc structure, thus determine interleave depth and the intertexture starting point of Turbo code.

A kind of zero Turbo code starting point and degree of depth blind-identification method, comprise the following steps:

S1, set the codeword sequence of reception as C, length is L, and code check is 1/n, creates full null sequence X, and length is L, and the estimation range of interleave depth N is 40 ~ [L/ (30n)] to the maximum, and wherein, n is non-vanishing natural number;

S2, for 3≤i≤L-1, if C _i=C _i+1, C _i-1=C _i-2, then X _i=1,

For i=1,2, if C _i=C _i+1, then X _i=1, wherein, C _irepresent i-th bit;

S3, interleave depth conjecture value are set to N=40;

S4, utilize full null sequence X structural matrix described in S1 $A=\left[\begin{array}{cccc}{X}_1& X_2& \mathrm{...}& X_N\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ X_{28N+1}& X_{28N+2}& \mathrm{...}& X_{29N}\\ X_{29N+1}& X_{29N+2}& \mathrm{...}& X_{30N}\end{array}\right];$

S5, each row asking matrix A described in S4 and Y ₁~ Y _nif there is the Y satisfied condition _j, then the jth position of sequence C is the starting point of first complete interleaving block, and interleave depth is defined as N, otherwise, N=N+1, wherein, j=1,2,3 ..., N, Y _nbe matrix A N arrange and, be that mould 2 adds, consequently 1 or 0;

S6, repetition step S4 and S5, until find correct interleave depth N, or N=[L/ (30n)];

S7, qualified Yj is established to be respectively Y _j1~ Y _jt, for 1≤p≤t, calculate d _p=(j _{(p+1) modt}-j _p+ N) modN, finds out maximum d _n, then n is correct interleaving block starting point, and t is the qualified Y found _jnumber.

The invention has the beneficial effects as follows:

The inventive method greatly reduces the operand of Turbo code parameter blind recognition algorithm, has evaded the step being forced to take multinest computing when total blindness identifies for multiple unknown number.Identifying is separated, parameter identification one by one, thus while raising operation efficiency, the actual operability that also made the identification of large interleave depth possess.

Accompanying drawing explanation

Fig. 1 is the flow chart of a kind of implementation procedure of the present invention under PCCC structure;

Fig. 2 be in the embodiment of the present invention 1 parameter recognition success rate with the change of bit error rate;

Fig. 3 be in the embodiment of the present invention 1 parameter recognition success rate with the change of interleave depth;

Fig. 4 is the parameter recognition success rate of several different component coder in the embodiment of the present invention 2.

Embodiment

Below in conjunction with embodiment and accompanying drawing, describe technical scheme of the present invention in detail.

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, so that those skilled in the art understands the present invention better.Requiring particular attention is that, in the following description, when perhaps the detailed description of known function and design can desalinate main contents of the present invention, these are described in and will be left in the basket here.

Fig. 1 is a kind of embodiment flow chart of the present invention when being applied to PCCC structure Turbo code.As shown in Figure 1, the zero Turbo code starting point under the large interleave depth of the present invention and degree of depth blind-identification method comprise the following steps:

S1: set the codeword sequence of reception as C, length is L, and code check is 1/n.Create full null sequence X, length is L.The estimation range of interleave depth N is 40 ~ [L/ (30n)] to the maximum;

S2: for 3≤i≤L-1, if C _i=C _i+1, C _i-1=C _i-2, then X _i=1; For i=1,2, if C _i=C _i+1, then X _i=1;

S3: interleave depth conjecture value is set to N=40;

S4: utilize sequence X structural matrix $A=\left[\begin{array}{cccc}{X}_1& X_2& \mathrm{...}& X_N\\ .& .& & .\\ .& .& & .\\ .& .& & .\\ X_{28N+1}& X_{28N+2}& \mathrm{...}& X_{29N}\\ X_{29N+1}& X_{29N+2}& \mathrm{...}& X_{30N}\end{array}\right];$

S5: each row and the Y that ask A ₁~ Y _n.If there is the Y satisfied condition _j, then the jth position of sequence C is the starting point of first complete interleaving block, and interleave depth is defined as N.If there is multiple Y _j, then whole Y is recorded _j.If do not exist, then N=N+1;

S6: repeat step S4 and S5, until find correct interleave depth N, or N=[L/ (30n)];

S7: establish qualified Y _jbe respectively Y _j1~ Y _jt.For 1≤p≤t, calculate d _p=(j _{(p+1) modt}-j _p+ N) modN, maximizing d _n, then n is correct interleaving block starting point.

Embodiment 1,

The object of the present embodiment emulates the parameter blind recognition success rate under different interleaving depths and different bit error rate condition.With 1/3 code check, PCCC structure, it is example that two component coder parameters are all [13,15].Under the condition of interleave depth 200, regulate bit error rate, record recognition success rate, obtains Fig. 2.Can find out, along with the raising of bit error rate, recognition success rate progressively declines, but the method has goodish error-resilient performance on the whole.Under the error rate 2.5% condition, regulate interleave depth, record recognition success rate, obtains Fig. 3.Can find out, interleave depth is very little on the impact of recognition success rate, and this is the theoretical foundation that the method is applicable to large interleave depth.

Embodiment 2,

The object of the present embodiment is the recognition performance of this method under the different component coder parameter of research.Equally with for 1/3 code check, PCCC structure that two component coders are identical, 682 generator polynomials between [101,103] to [177,175] are probed into.At interleave depth 200, under the condition of bit error rate 2.5%, carry out statistic of classification to the recognition success rate of each coding polynomial, result is as Fig. 4.

Can find out, the identification probability of most component coder is more than 85%.In fact, due to the rule that the recognition success rate shown in example 1 changes along with bit error rate, on the 0.1% common in practice order of magnitude, the recognition success rate of most component coder can reach ideal effect.In order to the recognition performance of outstanding different component coder can be slightly different, just bit error rate is increased to 2.5% herein.But still having the encoder of a large amount of success rate more than 90%, the scope of application of visible this method is wide.

Claims (1)

1. make zero Turbo code starting point and a degree of depth blind-identification method, it is characterized in that, comprise the following steps:

S1, set the codeword sequence of reception as C, length is L, and code check is 1/n, creates full null sequence X, and length is L, and the estimation range of interleave depth N is 40 ~ [L/ (30n)] to the maximum, and wherein, n is non-vanishing natural number;

S2, for 3≤i≤L-1, if C _i=C _i+1, C _i-1=C _i-2, then X _i=1,

For i=1,2, if C _i=C _i+1, then X _i=1, wherein, C _irepresent i-th bit;

S3, interleave depth conjecture value are set to N=40;

S4, utilize full null sequence X structural matrix described in S1 $A=\left[\begin{array}{cccc}{X}_1& X_2& ...& X_N\\ \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}.\\ .\\ .\end{array}& \begin{array}{c}\\ \\ \end{array}& \begin{array}{c}.\\ .\\ .\end{array}\\ X_{28N+1}& X_{28N+2}& ...& X_{29N}\\ X_{29N+1}& X_{29N+2}& ...& X_{30N}\end{array}\right];$

S5, each row asking matrix A described in S4 and Y ₁~ Y _nif there is the Y satisfied condition _j, then the jth position of sequence C is the starting point of first complete interleaving block, and interleave depth is defined as N, otherwise, N=N+1, wherein, j=1,2,3 ..., N, Y _nbe matrix A N arrange and, be that mould 2 adds, consequently 1 or 0;

S6, repetition step S4 and S5, until find correct interleave depth N, or N=[L/ (30n)];

S7, establish qualified Y _jbe respectively for 1≤p≤t, calculate d _p=(j _{(p+1) modt}-j _p+ N) modN, finds out maximum d _n, then n is correct interleaving block starting point, and t is the qualified Y found _jnumber.