中文摘要：

为了改善多跳传感器网络的性能，提出了一种基于三种空间分集技术的异步协作传输模式。该模式是考虑非同步网络传输，多个传感器通过共享天线，形成虚拟多天线发送／多天线接收（MIMO）的协作通信，并利用空时编码、发射天线选择和信号空间分集三种空间分集技术，有效抵制传输信道的衰落，提高了系统的分集增益。通过蒙特卡罗仿真，结果表明，对比传统的单发单收传输模式和异步空时协作传输模式，该传输模式获得了更高的分集增益，提高了系统的性能，从而节省了网络的能量损耗。

英文摘要：

In order to improve the performance of multi hop wireless sensor networks, a cooperative trans- mission scheme without perfect synchronization based on three diversity technologies is proposed, in which multiple sensors generate a virtual multiple-antenna transmitter/multiple-antenna receiver （MIMO） cooperative transmission mechanism through sharing antennas under an asynchronous transmission condition. Furthermore, three diversity technologies, space time block code （STBC）, transmit antenna selection （TAS） and signal space diversity, are adopted so as to mitigate channel fading effectively and improve system diversity gains. It is shown by Monte Carlo simulation that compared with the traditional transmission scheme or asynchronous STBC cooperative transmission scheme, the proposed scheme can provide further performance improvement by increasing the diversity order and save more energy in wireless sensor networks.