Turbo Codes Performance Research In Complex Channel

A novel channel coding scheme called Turbo codes is one of the most exciting channel coding schemes introduced in the last two decades. The coding system is a novel combination of iterative decoding with Soft-Input/Soft-Output (SISO) algorithms and Recursive Systematic Convolutional (RSC) codes in parallel connected by an interweaver. With these components, Turbo codes can approach to Shannon limit and perform very well in AWGN channels. Their performance in correlated fading wireless channels remains a question. The wireless channel is particularly dynamic due to multipath fading and Doppler spread.These effects havestrong negative impact on the transmission of Turbo codes. So it is important to study Turbo codes in wireless channel.Firstly , this paper reviews the history of channel code and presents the status of Turbo codes, recommends the code-decode structure and basic principle of Turbo Code. Some decoding algorithm of Turbo codes in common use are compared in their capability and complexity.Secondly, this paper discusses the channel, and made some research for the channel concept, the classification of the channel, especially for wireless channel.Then, using Matlab tool to simulate the Rayleigh Clarke Channel Reference Model, The simulation graphics and simulation codes are given, which prove that the mobile stations move faster, their receiving signals decline more seriously.Lastly, the paper studies the application of Turbo Codes in wireless channel, compares the Turbo Codes capability in AWGN and Rayleigh channels, and points out the infection of the channel interweave to Turbo Codes. The emulating results show that the Turbo codes capability in AWGN performs 1.5-2.5dB better than that in Rayleigh channel.They also show that the channel interweave can advance the capability of Turbo codes.