Research Of Recognition And Analyzation Methods Of Channel Codes

Recognitions and analysis of channel coding is an inverse engineering problem in information theory. That is recovering the channel coding structures and parameters from the received data stream by inverse methods with no prior knowledge about the implemented channel coding parameters. This technique has two possible applications: link adaptation in intelligent communications and information countermeasure in non-cooperative communications. On the link adaptation context, a transmitter needs choose modulation and coding parameters to adapt the electromagnetic environment and noise level. So the receivers must firstly recognize the modulation and coding parameters implemented by the transmitter, and then demodulate and decode the received data. In a non-cooperative context, a passive adversary usually cannot obtain the channel coding parameters; the recognition technique must be applied firstly. And then the receiver can correctly receive, decode and understand the intercepted data. This dissertion mainly considers the second application and gives intense research on the following topics.1. Recognition of frame synchronization parameters.In communication systems, the receivers and transmitters usually implement frame synchronizations for encoders and decoders. Therefore, the recognition of frame synchronization parameters is a key problem. This dissertion firstly aim at the synchronization word based synchronization techniques and propose new methods to estimate the frame length and beginning positions of frames. The methods are also extended to soft decision situations. Furthermore, we also propose synchronization parameter recognitions for blind frame synchronization techniques appeared in recent years.2. Recognition of error-correcting coding.Error-correcting coding is a key technique in channel coding. Therefore, recognition of error-correcting coding parameters is very important in the channel coding recognition problem.Linear block codes are a class of most applied error-correcting codes. This dissertion gives solutions for the recognitions of multiple error-correcting codes, which include binary cyclic codes, Reed-Solomon codes and low density parity check codes. Firstly, based on the study of other scholars’ work on parameter recognitions of Bose-Chaudhuri-Hocquenghem(BCH) codes, which are important subsets of binary cyclic codes, this dissertation points out some drawbacks and give our new solutions and extend the methods on the recognitions of Reed-Solomon codes. And in this dissertation we firstly propose the recognition of binary cyclic codes and Reed-Solomon codes on soft-decisions. The simulation results show that soft-decision based methods have significant improvements on fault-tolerance performances for coding parameter recognitions. On the low density parity check codes, based on the references this dissertion proposes a new and formulized recognition method to achieve the recognition of parity check matrices much rapider and exacter.Convolutional coding is another important section in error-correcting codes. This dissertion gives some complementation for the recognition methods proposed by other scholars and extends the methods to soft-decision situations. Besides, this dissertion proposes a new correlation attack method to meet low signal-to-noise ratio situations. The proposed method includes hard-decision and soft-decision algorithms both. Simulation results show that the correlation attack method, especially the soft-decision based algorithm, has significant better fault-tolerance performances.3. Recognition of interleaver parameters.The communication systems usually adapt interleaving technique to uniformly dispatch the burst errors into different codewords, which can improve the abilities of error-corrections for burst errors. This dissertion proposes a novel recognition method to meet common situations of convolutional interleaver parameter recognitions.4. Overall applications of channel coding recognitions.Based on the study of parameter recognitions of frame synchronizations, error-correcting codes and interlavers, this dissertion finally give some discussions on the overall implementations of the channel coding parameter recognition techniques. According to the general styles of channel coding, this dissertion proposes some strategies for overall recognitions of channel coding. And then, two applications of the channel coding recognitions on information countermeasure are shown. One is the application on electronic jamming, deceiving and cyber-electromagnetism-situation sensing. The other is evaluating the possible security-holes of the channel coding according to the research of channel coding recognitions, in order to adapt safety precautions to protect the transmitted information.