使用软判决反馈的迭代信道估计方法在CDMA系统中研究

Iterative channel estimation using soft decision feedback in CDMA system

首先介绍了基于CDMA2 0 0 0系统中Rake接收机的信道估计方法 ,然后将Turbo原理引入信道估计 ,针对CDMA系统提出了 2种迭代信道估计方法 .通过使用Rake接收机或解码之后的软信息来改善整个CDMA系统的性能 ,对CDMA系统中联合运用信道估计与解码技术进行了研究 .由于联合信道估计与解码技术可以利用通信系统不同模块之间的“软信息”交换 ,从而有效提高信道估计准确程度和解码器的性能 .仿真结果表明 ,利用解码之后的软信息来修正信道估计的方法较传统的Rake接收机中的信道估计方法性能有较大改善 ,在误码率为 1 0 - 3左右时 ,可以提高大约 2dB .

The channel estimation in Rake receiver is introduced based on CDMA2000 system and then the Turbo principle is applied to channel estimation. Two iterative channel estimation schemes with soft decision feedback for CDMA system are presented. Joint channel estimation and soft output from Rake receiver and decoder method are also discussed. Joint channel estimation and decoder technique effectively improve the performance of channel estimation and decoder by taking advantage of information exchange between different units in a communication system. These two schemes can remarkably improve the performance of CDMA system by using soft information after Rake receiver or decoder. The simulation result shows that the improvement of the bit-error rate over non-iterative scheme is about 2 dB when bit error rate equals 10-3 (decoder feedback).