基于空间迭代的信道估计和译码联合算法

Space-iteration channel estimation and detection joint algorithm

为了提高M IMO+OFDM系统在信道信息估计不准确时的译码性能,提出了一种基于SAGE(空间交替期望最大)算法的信道估计和M IMO译码联合算法。具体方法是:将发送的子帧分成若干个子块,第一个子块为导频子块,为第二个子块的译码提供信道信息;译码时对第二个子块进行内部的参数循环估计,完成该子块的译码后,解出该子块的信道信息,并将其作为下一子块译码的信道参数,依次完成所有子块的译码。经过仿真验证,该算法的性能优于LMMSE信道估计+ML译码算法的性能,运算复杂度低于EM算法。基于SAGE算法的信道估计和检测联合算法根据前一子块的译码结果,实时更新信道信息,充分利用译码包含的信道信息。该算法在不增加开销的情况下,能较好地追踪信道的变化,且能快速收敛,带来稳定的性能增益。

To improve the detection performance under imperfect channel information, this distribution put forward a channel estimation and detection joint algorithm based on SAGE, the detail was ： divided the received frame was into a few blocks, the first block was pilot block and provide the channel information for detection of the second block ; then detected symbols in the second block in turn ; when the second block finished detection, used the channel information of this block for the detection of next block, and detected repeat those processes until all blocks. Simulation results show SAGE algorithm has better perform- ance than ML detection ＋ LMMSE channel estimation algorithm, and lower calculation complexity and quicker astringency than EM algorithm. SAGE algorithm can update instantly channel information based on detection results of the previous block and quick astringency under inaccurate channel information, and achieve good and robust performance.