在OFDM系统中用循环前缀对时变色散信道进行估计

Channel estimation for OFDM system in time-varying dispersive channels using the cyclic prefix

目前 ,正交频分复用 (OFDM)技术因能在无线时变信道中进行高速数据传输而受到广泛的关注。在相干的OFDM系统中 ,接收机能否获得准确的信道状态信息(CSI)是系统性能提高的关键。为了能在接收端获得准确的CSI和提高系统的传输速率 ,文中将文献 [3]的算法由单路发射推广为I Q两路发射 ,采用复抽头系数的FIR滤波器对多径衰落信道进行建模 ,并用通常被丢弃的循环前缀作为训练序列对信道进行估计和均衡。仿真结果表明改进的算法在相同的子载波和比文献 [3]传输效率提高一倍的情况下能有效地自动跟踪信道的变化。

At present, more comprehensive attention has been taken to OFDM technology in data transmitting systems with wireless time-varying channel. In coherent systems, it is key to obtain the accurate channel status information (CSI). In order to get the CSI at receiver and increase the transmit rate of the systems, the algorithm in was generalized from single channel to I/Q channels; and the estimation and equalization of multipath fading wireless channel which was modeled as complex-taps FIR have been done using cyclic prefix discarded usually. The simulation shows that the modified algorithm is effective in tracking the changing of channel under the situation of same sub-carriers and that transmission efficiency has been double compared with