STBC-OFDM协作通信系统存在载波频偏时的均衡算法

在基于空时分组编码正交频分复用的协作通信系统中，不同用户节点间存在的载波频偏会产生子信道间干扰与子信道内干扰. 该文研究对抗这两种干扰的实用均衡方法. 针对较小的归一化频偏差，提出一种实现迫零均衡的低复杂度迭代算法IAZF. 针对较大的归一化频偏差，构造一种串行最小均方误差组间干扰消除与并行干扰消除联合的均衡算法JEA，并根据信道矩阵的近似带状结构，实现了均衡所需的矩阵求逆的递推计算，节省了计算量. 仿真结果表明：在相当大的归一化频偏差范围内，JEA的性能稳健，特别是在归一化频偏差大于0.25 时明显优于现有方法. 在归一化频偏差小于0.15时，IAZF提供了逼近其他方法的性能且复杂度更低.

Equalization for Cooperative Communication System Based on STBC-OFDM with Carrier Frequency Offsets

In cooperative communication systems based on space-time block coded orthogonal frequency division multiplexing (STBC-OFDM), inter-channel interference (ICI) and co-channel interference (CCI) arise from multiple carrier frequency offsets (CFO) among different user nodes. Practical equalization methods are studied to combat these two interferences. When difference of normalized CFOs (DCFOs) is small, a low-complexity iterative approach named IAZF is proposed, which achieves zero forcing (ZF) equalization. In case of large DCFOs, a joint equalization algorithm (JEA) is given, which combines successive minimum mean square error (MMSE) inter-block interference cancellation with parallel interference cancellation. Furthermore, by exploiting the approximate banded structure of channel matrix, we implement recursive calculation of matrix inversion of JEA to reduce the computation burden. Simulation results show that, in a quite large range of DCFOs, JEA is robust with significant improvement over the existing methods, especially when DCFOs is larger than 0.25. The performance of IAZF approaches those of other methods when DCFOs is less than 0.15, and requires low computation load.