MIMO-OFDM系统中的子载波间干扰消除

推导了一种在快衰落频率选择性信道下适用于多输入多输出正交频分复用(MIMO-OFDM)技术的系统模型.应用这个模型,分析了信道在一个传输符号内的时变特性带来的影响,它破坏子载波间的正交性,从而引起严重的子载波间干扰(ICI).针对这一问题,提出一种频域迭代子载波间干扰消除算法.通过将信道传输矩阵分离为数据部分和ICI部分,首先利用迫零算法获得发送信号的初始估计值,由信道的ICI矩阵生成干扰信号,从接收信号中减去干扰,之后利用数据矩阵和并行干扰抵消算法来消除不同发送天线上相同子载波的多流干扰.仅考虑邻近18个子载波带来的干扰,在其性能与原算法几乎相同的条件下,可以极大地降低计算复杂度.仿真结果表明该算法在不同的多普勒频移条件下能有效消除子载波间干扰,并且在低信噪比下逼近准静态信道下系统的性能.

Intercarrier interference cancellation for MIMO-OFDM systems

We develop a model for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) system over time varying frequency selective fading channels. Using this model, we analyze the impacts of the channel on time variation characteristics within a transmission block which destroy the orthogonality of subcarrier and cause serious intercarrier interference(ICI). To circumvent this problem, we propose a frequency-domain iterative ICI cancellation algorithm. By separating the channel transfer function matrix into data and the ICI part, data are initially obtained by the zero-forcing algorithm, the interference between adjacent subcarriers, created by ICI matrix, is then subtracted from received symbols and finally the parallel interference cancellation detection using the data matrix is performed to suppress the multistream interference from different antennas. By restricting the interference to eighteen neighboring subcarriers, under the condition that the performance loss is neglectable compared with the original method, computational complexity can be drastically reduced. Simulation results show that the proposed method can effectively mitigate the effect of ICI at different doppler shifts and approach the ICI-free performance at a low signal-to-noise ratio.