基于BEM的时变信道估计改进算法

Improved Algorithm of BEM-based Time-varying Channel Estimation

针对参数未知、存在大多普勒频移的时变信道情况,介绍了与之相适应的BEM模型,分析了2种适用于估计BEM模型加权系数的算法,即LS算法和基于迭代的BLUE算法。LS算法简单快捷,其性能不如BLUE算法;BLUE算法因迭代初始值精度不高,在低信噪比时同样存在估计性能差的缺点。提出一种基于BEM模型的时变信道参数估计改进算法,将LS的估计结果作为BLUE的初始迭代值估计BEM模型系数,从而得到更精确的时变信道参数。在典型的时变信道下,以OFDM传输系统为例,对传统BLUE算法和改进后的BLUE算法进行了对比仿真分析。分析结果表明,在低信噪比条件下,相同迭代次数时,改进后的BLUE算法优于传统BLUE算法。

Aiming at unknown statistic characteristic and high Doppler frequency shift of channel, the time-varying channel approxi- mation model--basis expansion model （BEM） model is introduced briefly. The channel estimation based on BEM often uses LS algorithm and iterative-based BLUE algorithm. LS is simple and fast, and its performance is not as good as that of the iterative-based BLUE.,as the iterative initial value is not precise, the BLUE algorithm has the shortcoming of poor estimation performance under low SNR. This paper proposes an improvement algorithm of BEM-based time-varying channel estimation,which uses the estimation results from LS as the initial iterative value of BLUE to estimate BEM model coefficients and obtain the precise time-varying channel parame- ters.By taking OFDM as an example,the traditional BLUE and improved BLUE is simulated,compared and analyzed. The results show that the improved BLUE algorithm is better than the traditional BLUE algorithm under the condition of same iterative number and low SNR.