OFDM系统中联合抑制ICI的算法  

Combined algorithm for suppressing ICI in OFDM system

作　　者：李萌[1] 王琼[1] 蔡希彪[1] 武兴佩 

机构地区：[1]辽宁工业大学电子与信息工程学院,辽宁锦州121001

出　　处：《计算机工程与应用》2016年第10期85-90,共6页Computer Engineering and Applications

基　　金：辽宁工业大学自然科学基金(No.No.x201317)

摘　　要：针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于对称子载波的ICI自消除算法与时域加窗相结合,即在发送数据符号之前,与升余弦函数相乘。对算法进行仿真实验,相对于相邻符号自消除算法,该算法减小了子载波间的干扰系数;加窗后OFDM符号频谱的边瓣衰减速度快,最大可衰减至-40 d B;对于系统的信号干扰比性能(SIR),加窗后的算法同相邻符号自消除算法相比可提高8 d B左右;在信噪比较大的情况下,改善了系统的误码率。仿真结果表明,所提算法能够抑制ICI,提高系统抗干扰性能。The Inter Carrier Interference（ICI）caused by frequency deviation will have an impact on the performance of the Orthogonal Frequency Division Multiplexing（OFDM）communication system. For solving this problem, an algorithm based on symmetric inter carrier is proposed. The proposed algorithm modulates the opposite symbols onto the symmetric inter carriers; at the receiver, the demodulated symbols are combined linearly. For reducing the ICI further, the algorithm is combined with windowing in time-domain. That is the symbols are multiplied by raised cosine function before they were transmitted. In the algorithm simulation experiments, the algorithm based on symmetric inter carrier decreased the Inter Carrier Interference（ICI）coefficient compared with the typical self-cancellation scheme; the side lobe of the OFDM symbol spectrum attenuated fast after windowing, and the maximum could be-40 d B; for the Signal to Interference power Ratio（SIR）, the algorithm after windowing could improve about 8 d B compared with the typical self-cancellation scheme; in the case of lager Signal to Noise Ratio, it also improves the Bit Error Ratio performance. The simulation results show that the proposed algorithm can suppress the ICI and improve the anti-jamming performance of OFDM system.

关 键 词：正交频分复用 频率偏移 子载波间干扰 时域加窗 信号干扰比 

分 类 号：TN911.3[电子电信—通信与信息系统]