在正交频分复用系统中对多径信道进行估计

正变频分复用(OFDM)技术因能有效抑制信道畸变而在无线数据传输中受到广泛的关注。为了能够正确估计发射端的数据,信道的正确估计是非常重要的。将已有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滤波器来对信道建模,并用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,当FIR信道没有深度衰减时,所提算法在相同的子载波和比原有方法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;当信道有深度衰减时采用线性预编码的情况下,算法在比原有方法传输效率有较大提高的情况下也能有效地跟踪信道的变化。

Estimation in an Orthogonal Frequency Division Multiplexing System of the Multipath Channels

More and more attention has been paid to OFDM technology in wireless data transmission systems because it is effective to suppress channel distortion. It is very important to estimate correctly the channel in order to determine the data transferred by a transmitter. In this paper, estimation and equalization of a multipath fading wireless channel which is modeled as a complex-tap FIR filter have been done using cyclic prefix under I/Q modulation. The simulation results show that our algorithm compared with the traditional algorithm, is effective in tracking the change of channel without deep fading under the condition that transmission efficiency has been doubled with the same sub-carriers. It is also effective to track the channel with deep fading under the condition that transmission efficiency has been increased obviously when linear preceding technology is used.