基于非线性空时编码系统的自适应信道估计

用非线性分组编码，在时间选择性衰落信道环境下，将基本LMS自适应算法推广到对二维空时编码信号的权矩阵自适应迭代估计，分析了对输入信号序列编码所生成的非线性编码矩阵之间的相关性，运用解相关LMS自适应算法对衰落信道进行估计．在不同噪声情况下，根据估计信道和噪声统计量，推导了对非线性编码进行解码的最大似然决策方法．仿真试验表明，采用扩展LMS算法和解相关LMS算法跟踪时变衰落信道响应具有较强的鲁棒性和快速收敛性，非线性空时分组编码系统相对干线性编码系统提高了编码系统性能，运用最大似然决策方法进行解码降低了系统误码率．

Adaptive channels estimation for non-linear space-time coding systems

Considering the correlation among the non-linear code matrices produced by the input signal sequences, the time selective fading channels are estimated by decorrelation LMS adaptation algorithm. In the various noise environments, it is derived that the maximum-likelihood method decoding the non-linear space-time block codes by channels estimate, the noise statistics and received signals. Simulations illustrate that using LMS algorithm and decorrelation LMS algorithm to track fading channels has good stability and fast convergence. It is also shown that the non-linear coding outperforms the corresponding liner coding by about 2 dB and the method of maximum-likelihood decreased the bit-error-ratio by 43%.