正交频分多址接入系统的上行载波同步跟踪方法

为了解决上行正交频分多址系统中频率偏差导致多用户干扰和载波间干扰的问题,提出了一种载波同步跟踪方法。该方法使用了时频同步跟踪环路,从数据子载波提取相位误差,并利用频域插值补偿多个用户的估计频偏。该方法只需要一个快速Fourier变换(FFT)单元,降低了系统实现复杂度。仿真结果表明:该方法对不同的子载波分配方式具有鲁棒性,与无频偏系统的理想接收性能相比,误码率性能损失小于0.5 dB。此外,该方法可以在10~20个正交频分复用(OFDM)符号内快速收敛。与传统的导频辅助跟踪方法相比,提高了频谱利用率,抗噪声和抗多径衰落性能有明显改善。

Uplink carrier offset tracking method for orthogonal frequency division multiple access systems

A synchronization tracking method is given for uplink orthogonal frequency division multiple access(OFDMA) systems.The system uses time-frequency tracking loops to extract phase errors from data subcarriers with frequency interpolation to compensate for the estimated carrier frequency offsets.The method uses only one fast Fourier transform(FFT) unit which significantly reduces system complexity.Simulation results show that the method is robust against various subcarrier allocation schemes,with bit-error-rate(BER) performance very close to that of an offset-free system. In addition,the method converges within 1020 OFDM symbols. The bandwidth efficiency,as well as the resistance to frequency selective fading and noise,is much better than that of the pilot-subcarrier-aided method.