Research And Simulation On Space-Time Block Code In Time-Varying Fading Channel

Space-Time Block Code (STBC) is a new channel coding technology with the extensive application of wireless communications. It combines coding, modulation, transmit and receive diversity, and validly increases the anti-noise performance in fading channels. The key feature of STBC is that the transmit sequences from any two transmit antennas are orthogonal. This feature not only provides the maximum diversity order in slow and flat channels, but also declines the complexity of STBC decoding. Because of its better performance and simplicity of implementation, more and more people have focused on the study of it.Starting with the introduction of the wireless channel and the main parameters, then, the perspective of the Alamouti space-time block coding, transmission diversity scheme, orthogonal design of space-time block encoding rules, merge criterion and the maximum likelihood decoding algorithm are discussed in detail. Space-time block coding is given generalized maximum likelihood decoding algorithm.If the number of transmit antennas is more than two, the Space-Time Block Code with complex constellation modulation have to be at a loss of code rate. This paper puts forward two options:first, the coding matrix which combines the matrix coding matrix rotation with constellation rotation has full marks set into gain, improving the performance of the system; second, matrix diagonalization changes the channel matrix into a diagonal matrix. Linear decoding at the receiving end reduces the decoding complexity in some extent. Both the maximum likelihood decoding algorithm based on QR decomposition and the improved of SD algorithm reduce the decoding complexity.The simulations of STBC in quasi-static fading channels such as Rayleigh are given. The analysis and the comparison of the performance are also presented.