Research On Blind Recognition Technology For Linear Block Code

In order to ensure the reliability and security of information transmission in actual digital communication system, usually using channel coding techniques. Developing rapidly in many fields, channel coding techniques gain a high-profile as well. The purpose of channel coding recognition is to estimate the coding system and to code parameters of the intercepted code sequence with just a few or even without prior information, so as to extract the original information sequence. The linear block codes have characteristics of simple encoding, stronger error correction capability which have been widely used in many areas of digital communication. Therefore, the paper researches on blind identification problem for binary linear block code parameters.Firstly, introduce the basic knowledge of block codes, mathematical models and identification parameters of coding identification. Above in all is the foundation of the parameter estimation algorithm discussion. Then summarize the advantages and disadvantages of existing linear block code parameter identification algorithm, and then propose an algorithm based on the similarity of code weight of the identification code length and synchronization points, which is the the similarity of code weight distribution between the actual sequence and random sequence and the generator matrix is recognized by the feature of depth distribution, the blind recognition of linear block codes is realized.The recognition method is simple, theoretical analysis and simulation experience show that the method has better error-tolerance and the recognition has better performance in 0.01 BER. Finally, researching on the special linear block code, that is to say the cyclic codes.Aimed at semi-blind estimating for BCH code parameter, according to the cyclic property,use the division algorithm to get the highest common factor before and after the shif and the order numbers relative to the distribution of random sequence are uneven. According to this differences, this paper presents a code-length identification method which use variance difference and the average Euclidean distance as a code-length algorithm. And comparethese two kinds of effect quantitative indicators and then presents a new fusion target identification code-length algorithm. Build a common factor coefficient of probability distribution, and a common factor coefficient of probability distribution. Generated polynomial is identified and then half blind identification of BCH code is completed.Through experiment simulation, fusion target method has a better fault tolerance on identification of code-length. In order to solve the blind identification problem for high rate cyclic code with high BER effectively, inspired by BCH code recognition algorithm,using the most notable differences of the highest common factor order distribution, propose a blind identification algorithm of cyclic code based on standard error rate difference of the highest common factor order according to improved theoretical and experimental simulation. The method has less computation as well better error-tolerance. And the effect is obvious in the short-code recognition, in the BER of 0.023 conditions.