OFDM系统在短波信道上的线性均衡方法  

A Linear Equalization Technique for OFDM Systems in HF Channel

作　　者：徐发强[1] 益晓新[1] 

机构地区：[1]解放军理工大学通信工程学院,江苏南京210016

出　　处：《系统仿真学报》2002年第10期1380-1383,1404,共5页Journal of System Simulation

基　　金：国防科技重点实验室基金项目(00JS04.5.1.JB3802)

摘　　要：由于短波信道CHF的时变和多径,使OFDM信号的正交性受到损失(产生子载波间干扰ICI),从而导致了码间串扰(ISI),误码底板上升,并且随着信道的多普勒频率的增加而增加。针对这种情况,提出了一种简单的频域均衡方法。这种均衡方法假设:在一个OFDM块期间,信道的冲激响应(CIR)是线性变化的,而常规的单抽头频域均衡器对频率选择性多径衰落信道的补偿是假定在一个FFT块期间信道是静态的。当相对多普勒频率在范围(1.0005.0<D<Df)以内时,均衡器可以有效地补偿由信道的多径时变造成的正交性损失。通过对ICI的均衡,极大地改善了比特误码率(BER)的性能。A loss of sub-channel orthogonality due to HF channels in orthogonal frequency-division multiplexing (OFDM) systems leads to inter-channel interference (ICI), which increases the error floor in proportion to the Doppler frequency. A simple frequency-domain equalization technique is proposed to tackle this problem. In this technique, the equalization of the received OFDM signal is achieved by assuming that the channel impulse response (CIR) varies in a linear fashion during a block period, while normal single-tap frequency equalization assumes that the channel is statistic in a FFT block. Therefore the loss of orthogonality caused by the time-variation of a multi-path fading channel can be compensated effectively by the proposed equalizer if the relative Doppler frequency change is in the range of (1.0005.0<D<Df). It is also shown that improved BER results can be obtained with the proposed approach by compensating both the multiplicative distortion and the ICI.

关 键 词：OFDM系统 短波信道 线性均衡方法 正交频分复用 时变多径信道 误码底板 计算机仿真 通信系统 频域均衡器 

分 类 号：TN914[电子电信—通信与信息系统]