A novel full density QSTBC scheme with low complexity

In this paper, a new design criterion for quasi-orthogonal space time block codes is proposed for four transmit anntenas and four receivers MIMO communication system when it experiences the Rayleigh fading channel. Based on the design criterion, an improved design of QOSTBC(Quasi Orthogonal Space Time Block Code) for coherent channal interference is proposed that avoids repeated transmission of symbols by mapping symbols into another symbol domain which can maximize the euclidean distance between the symbols. Based on the optimal design of symbol structure, the proposed codes have lower decode complexity which performs close to the linear decoder. In the algorithm performance and BER analysis that the results are validated by Monte Carlo simulations. It is shown that the improved algorithm compared with other tranditional methods has higher coding/diversity gain and lower complexity.