UFMC系统在多径衰落信道中的干扰消除

Interference Suppression of Universal Filtered Multicarrier System in Multipath Fading Channel

通用滤波多载波(UFMC)是5G通信系统中的关键技术,能够降低带外泄露。但是在多径衰落信道下UFMC系统会受到符号间干扰(ISI)和多普勒效应产生的载波频率偏差的影响,从而使系统的性能下降。为了消除系统中的干扰,提出了一种迭代最大似然算法。该方法主要通过迭代最大似然算法(ML)计算出载波频率偏差,把估计出的结果作为初始值并运用迭代的方法得到最终的载波频率偏差,当达到收敛区间时,迭代结束;最后利用相位旋转的概念补偿载波频率偏差并运用最小二乘算法更新信道响应信息,减少该系统干扰。仿真结果表明,在信噪比大于10 d B时,随着信噪比的增大,算法能够有效地抑制系统中的干扰,提高UFMC系统的性能。

The key technology in 5G communication transmission,Universal Filtered Multicarrier（ UFMC） can reduce the out-of-band leakage. However,the UFMC system is affected by inter-symbol interference （ISI） and carrier frequency offset（CFO） due to the Doppler-effect in multipath fading channel,and the performance of system is decreased dramatically. In oder to reduce interference,an iterative maximum like-lihood（ ML） algorithm is proposed. The method is mainly based on the improved ML algorithm to calculate the CFO. Then the estimated result is used as the initial value and the final CFO is obtained by the iterative method. Upon reaching convergence zone,the iteration ends. Finally,the CFO is compensated by the con-cept of phase rotation and the channel response information is updated by the least square（ LS） algorithm so as to reduce the interference in the system. Simulation results show that the proposed algorithm can ef-fectively suppress the interference to improve the performance of UFMC system when the signal-to-noise ratio（ SNR） is greater than 10 dB and the SNR is increasing.