Abstract: In order to reduce the decoding complexity while having a high rate，a new type of the expanded space-time coded cooperative diversity method is utilized in wireless sensor networks.It is constructed by embedding Alamouti codes into every input information symbols of OAC（Overlapped-Alamouti Codes）.With the simulation，the constraint of the cooperative nodes and the comparison between the proposed method and the existing method are investigated.Simulation results suggest，when M=4，the proposed scheme outperforms the OAC and Toeplitz about 62%~90%.When M=8，the proposed scheme outperforms the OAC and Toplitz about 42%~71%，and more relay nodes have better effect on the system performance improvement.

Key words: space-time codes, cooperative diversity, wireless sensor networks, cooperative nodes

摘要： 为了在达到高码率的同时降低译码复杂度，提出了一种新的基于无线传感器网络的扩展空时编码协作方法，其构造原理是对OAC编码中的每一个参数插入Alamouti编码。通过实验仿真了该方法与原有方法之间的性能对比，以及不同协作节点数与系统性能之间的关系。仿真结果表明，在协作节点为4时，所提出的编码方法相比OAC编码和Toeplitz编码，其误符号率下降幅度为62%~90%，在协作节点数为8时，其误符号率下降幅度为42%~71%，并且随着协作节点数的增加系统性能得到提升。

关键词: 空时编码, 协作分集, 无线传感器网络, 协作节点