一种STBC-OFDM系统中的盲和半盲信道估计

Subspace-Based Semi-Blind Channel Estimation for STBC-OFDM Systems

针对尾部补零(Zero padd ing,ZP)的空时分组编码正交频分复用(Space-tim e b lock cod ing orthogona l fre-quency d iv is ion m u ltip lex ing,STBC-OFDM)系统,提出了一种基于子空间分解的信道估计算法。首先利用STBC的编码结构和OFDM信号中由ZP和虚载波(V irtua l carrier,VC)引入的冗余,推导了该算法的盲估计形式,然后对其可辨识性进行了理论分析,证明了该盲方法可以在一个标量因子模糊度的意义上辨识出多个信道的冲激响应。通过结合使用导频信息形成半盲算法,可以消除模糊度。仿真结果表明,该算法的信道估计准确度较高,可以有效地跟踪衰落信道,在低信噪比时性能良好。

A subspaee-based blind channel estimation method is proposed for zero padding （ZP） orthogonal frequency division multiplexing （OFDM） systems with space-time block coding （STBC） transmitter diversity. This method uses the structure of STBC and redundancies of OFDM signal itself introduced by ZP and virtual carriers （VC） to simultaneously estimate multiple channels. By theoretical analysis, it is established that multichannel identifiability is guaranteed up to one scalar. With the pilot information, a subspace-based semi-blind method is developed to resolve ambiguity and the accurate estimation is given. Simulations show that the method with the training-based channel estimator has a good performance.