Performance of Turbo Codes in Multipath Fading Channels

• Main Authors: Jan, Da-Shang, 簡大翔
• Other Authors: Yu T. Su
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/17613315689352163385

碩士 === 國立交通大學 === 電信研究所 === 85 === AbstractA class of powerful error-correcting codes called parallel concatenated codes, or turbo codes, has been proposed recently. Such a code consists of two or more parallel recursive systematic convolutional codes, each "subcode" is used to encode the same but independently interleaved data sequence. Together with a maximum a posteriori probability (MAP) iterative decoding rule, turbo codes have been shown to achieve bit error rate performance close to the Shannon's AWGN limit. The performance and behavior of turbo codes in practical multipath fading channels, however, remains to be determined. The fading effect usually incurs burst errors that greatly hinder a channel code's error correcting capability. Modification of the decoder structure is needed to account for the influence of multipath fading. The purpose of this thesis is to investigate the impacts of channel conditions and various system design alternatives on the overall system performance. Channel models used are: independent and correlated Rayleigh fading channels and those based on Jakes' model. Given the channel model we then study how the channel state information is derived and such information can be used to help decoding. Computer simulation is employed to quantify various system behavior and to provide numerical examples that give us system solutions.