高铁环境下MIMO-OFDM系统中的载波间干扰自消除

高铁(high-speed train, HST)无线信道具有非平稳时变特性, 针对高铁环境下的多入多出-正交频分复用(multiple-input multiple-output orthogonal frequency division multiplexing, MIMO-OFDM)系统, 提出一种载波间干扰(inter-carrier interference, ICI)自消除和迫零(zero forcing, ZF)均衡联合算法. 在接收端, 利用循环前缀(cyclic prefix, CP)序列, 对每个OFDM符号序列抽取子序列并线性平均加权以实现ICI自消除, 然后再对新的ICI减小的OFDM符号序列采用ZF均衡算法进行均衡, 最后通过硬判决检测得到发送信号. 仿真实验表明, 利用CP序列能有效减小ICI, 从而提高载波干扰比(carrier-to-interference ratio, CIR). 对于误码率(bit error rate, BER)性能, 该联合算法优于直接ZF均衡算法, 能够保证较好的通信质量.

Inter-carrier interference self-cancellation for MIMO-OFDM systems in high-speed train environment

Wireless communication channels for high-speed train (HST) systems are nonstationary and time-varying. A joint algorithm of inter-carrier interference (ICI) selfcancellation and zero forcing (ZF) equalization is proposed for multiple-input multipleoutput orthogonal frequency division multiplexing (MIMO-OFDM) systems used in the HST environment. At the receiver, cyclic prefix (CP) and linear weight average, and combing the subsequences extracted from each OFDM symbol are used to achieve ICI selfcancellation. The new OFDM symbol with ICI reduced is equalized by ZF equalization. The transmitted signal is then obtained by hard decision. Simulation results show that ICI can be effectively reduced by using CP, and the carrier-to-interference ratio (CIR) is raised. Besides, the proposed algorithm outperforms the ZF equalization method in terms of bit error rate (BER), and therefore ensures better quality of communications.