中文摘要：

为了实现在发送端未知信道状态信息（CSI）条件下的高效协作通信，研究了基于喷泉码的协作通信系统的性能。研究表明，在放大转发协作中目的端接收到的喷泉码符号的差错率比译码转发协作低。同时为了更充分地利用协作分集增益，提出了将基于喷泉码的放大转发协作通信与自适应解调技术相结合的方案，该方案使协作分集更有效地作用于喷泉码译码，并实现在发送端未知CSI条件下的自适应传输。仿真结果表明，该方案与采用喷泉码的直传通信和译码转发协作通信相比，能够降低误比特率，加快译码速度。

英文摘要：

In order to achieve high-efficiency cooperative communication when channel state information（CSI） is unknown to the sender, the performance of fountain codes based cooperative communication systems was analyzed, and the result implied that the error rate of received fountain coded symbols in amplify-and-forward cooperation was lower than that in decode-and-forward cooperation. Besides, a new scheme was proposed to fully utilize the cooperative diversity gain, which combined fountain codes based amplify-and-forward cooperative communication with adaptive demodulation. In this scheme, the cooperative diversity can help with the decoding of fountain codes more effectively, and adaptive transmission can be realized even when CSI is unknown to the transmitter. The simulation results showed that, compared to direct transmission and decode-and-forward cooperative communication using fountain codes, this scheme did have a lower bit error rate as well as a faster decoding.