Research On Efficient Turbo Codes And Its Application In Secure Communication

Due to the excellent performance of approaching Shannon limit, Turbo codeshave been thoroughly applied in deep space communication, satellite communication,multimedia communication and other fields. However, with regard to the systemsadopting Turbo codes as its channel coding method, time delay is always a bottleneckproblem which restricts Turbo Codes’ use in more scenario. For this reason, thedissertation departs from the following two aspects.Firstly, the dissertation takes interleaver-design into consideration to enhance theefficiency and reduce the time delay of encoding and decoding of Turbo codes. On onehand, as for the serial decoding of Turbo codes, the dissertation gives two kinds ofrapid interleaver, with the name of rapid interleaver based on m-sequence and delaycontrollable interleaver. On the other hand, as for the parallel decoding of Turbo codes,a kind of contention-free interleaver based on m-sequence is proposed, as well as aparallel decoding algorithm based on sliding window. Simulation results show that,using corresponding decoding method, three interleaver schemes all can improve theefficiency of Turbo codes in different degrees, and guarantee the performance of Turbocodes.Secondly, in view of the conventional methods that encrypt information and usechannel coding subsequently, the dissertation studies a scheme of joint encryption anderror correction based on efficient Turbo codes, which combines encryption with Turbocoding, reduces steps from two to only one, and meanwhile employs efficient serial orparallel decoding method, so as to increase the efficiency of the communication system.The dissertation verifies the feasibility of this scheme through image transmission.Study indicates that, this strategy has good performance in terms of safety andreliability, which also means it’s a candidate solution for efficient communicationsystem.