TDS-OFDM对信道频谱零点的重建

Signal reconstruction of channel spectral nulls in TDS-OFDM systems

当无线传输信道出现频谱零点,正交频分复用(OFDM)系统会出现严重的性能恶化。针对信道频谱零点带来的性能恶化问题,现有的OFDM系统采用信道编码和交织来恢复丢失的数据。为时域同步OFDM系统提出一种低复杂度的信号重建方法,该方法不需要对现有的时域同步OFDM发射机作任何额外的修改,完全在OFDM接收端进行,在均衡过程中重建因信道频谱零点而丢失的数据,并且其计算复杂度只与快速Fourier变换相当。计算机仿真证明,新方法的应用使时域同步OFDM系统的性能显著提升,大大优于现有的重叠相加均衡方法。

The performance of orthogonal frequency-division multiplexing （OFDM） systems may severely deteriorate when passing through wireless channels with spectral nulls. Current OFDM systems reduce this performance loss by incorporating powerful forward error correction coding with very long interleaving. This paper describes a signal reconstruction scheme, which has the same computational complexity as the fast Fourier transform （FFT） algorithm, for time domain synchronous orthogonal frequency-division multiplex （TDS-OFDM） to reconstruct the missing data due to the channel spectral nulls without requiring any changes at the transmitter. Simulation results demonstrate that significant performance improvement can be achieved using the method over the so-called overlap and add （OLA） scheme.