Research On Space-time Block Concatenated Codes

Space-time block coding (STBC) scheme introduced by Alamouti is extensively used due to the simplicity in encoding and decoding and full diversity gain. But STBC can not achieve high coding gain,concatenating exterior coding to get the coding gain is considered. Low density parity codes (LDPC) have very high coding gain and the performance of LDPC approaches to the Shannon limit. Based on this,this thesis discusses the concatenating way of the LDPC and STBC and their performance. Furthermore,combining cooperation codes and LDPC is considered because the concatenating cooperation codes can get extra coding gain in addition to diversity gain. Likewise,network codes have net diversity gain,so combining network codes and LDPC is considered to obtain both the high coding gain and net diversity gain. Generally speaking,the main work is as below:(1) Encoding and decoding algorithms of LDPC and STBC are described. How the encoding length and iterative times of LDPC impact on system performance is discussed.(2) The principle of space-time block concatenated codes is introduced. The simulating results show that space-time block concatenated codes can improve the system performance effectively.(3) The 4 ways of combining cooperation codes and LDPC are discussed. The results show that combining cooperation codes and LDPC has approximately 0.5dB higher than no cooperation Space-time block concatenated system when the BER is 10-3, and approximately 1dB when the BER is approaching 10-4.(4) The 2 ways of LDPC-network coding for two models are discussed. The results show that LDPC-network coding have both high coding gain and network diversity gain, so it improve the system performance efficiently.