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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。
In order to solve the problem of multi-user interference and inter-carrier interference caused by frequency deviation in uplink orthogonal frequency division multiple access system, a carrier synchronization tracking method is proposed. The method uses a time-frequency synchronous tracking loop to extract phase errors from the data subcarriers and to compensate the estimated frequency offset of multiple users using frequency-domain interpolation. The method only needs a fast Fourier transform (FFT) unit, which reduces the system complexity. The simulation results show that this method is robust to different subcarrier allocation schemes, and the bit error rate performance loss is less than 0.5 dB compared with the ideal receiving performance of non-frequency offset systems. In addition, this method can quickly converge in 10-20 Orthogonal Frequency Division Multiplexing (OFDM) symbols. Compared with the traditional pilot-assisted tracking method, the spectrum utilization rate is improved, and anti-noise and anti-multipath fading performance is obviously improved.