IQ不平衡OFDM系统高性能稀疏信道估计算法

High-Performance Sparse Channel Estimator for OFDM System with IQ Imbalances

针对正交频分复用系统中收发两端都有同相和正交不平衡的问题,本文提出了一种时域最小二乘(Time domain least square,TD-LS)信道估计算法。在此基础上,为了进一步挖掘无线信道的稀疏特性,又引入稀疏信号处理理论中的迭代收缩(Iterative shrinkage,IS)和平行协调下降(Parallel coordinate descent,PCD)思想,构造了一种联合的信道估计算法:TD-LS-IS-PCD。仿真结果表明:采用相同的最小二乘补偿算法时,提出的TD-LS和TD-LS-IS-PCD的误码性能明显优于传统的频域最小二乘算法;同时TD-LS-IS-PCD算法误码性能优于TDLS,逼近理想情况,因此该算法充分挖掘了信道的稀疏特性。

In the orthogonal frequency division multiplexing（OFDM）system with IQ imbalances,a time-domain least square（TD-LS）algorithm is proposed to estimate channel and IQimbalance parameters.To further exploit the sparsity of wireless channel,iterative shrinkage（IS）and parallel coordinate descent（PCD）are combined with the proposed TD-LS to form a new joint channel estimator TD-LS-IS-PCD.Simulation result shows that,in terms of bit error rate（BER）,the proposed TD-LS and TD-LS-IS-PCD algorithms perform much better than the traditional frequency-domain least square（FD-LS）when the same least square equalizer is adopted.Furthermore,the BER performance of TD-LS-IS-PCD approaches that of the ideal channel estimator.