中继协作无线网络中不完美反馈下基于网络编码的重传方案

无线广播网络传输过程中，目的节点反馈信息丢失或部分丢失导致发送节点不能了解目的节点的真实接收状态.为提高不完美反馈下无线网络的重传效率，本文提出中继协作无线网络中不完美反馈下基于网络编码的重传方案.本方案基于部分可观察马尔科夫决策过程对不完美反馈下的重传过程进行建模.发送节点根据系统观测状态和最大置信度更新系统估计状态，根据数据包发送顺序，优先选择最早丢失且能够恢复最多丢包的编码包重传.目的节点缓存不可解编码包以提升编解码机会.重传过程中源节点关注目的节点请求包需求，相同情况优先选择传输可靠性较高的中继节点，以提升传输有效性.仿真结果表明，在不完美反馈下相对于传统方案，本方案可有效提高重传效率.

Retransmission Scheme Based on Network Coding for Relay-Assisted Wireless Network with Imperfect Feedback

During wireless network transmission,when the feedback information from the destinations is lost or partially lost,the source cannot achieve the real accepting status of destinations.To improve the retransmission efficiency of wireless networks with imperfect feedback,a retransmission scheme based on network coding is proposed.The retransmission procedure with imperfect feedback is modeled based on POMDP (Partially Observable Markov Decision Process) theory.According to the system observation status and the maximum confidence degree,the source updates the system estimation status.And the source gives preference to select the encoding packet that can recover the earliest lost packet and the most lost packets according to the packet sending sequence.To increase the coding and the decoding opportunities the destination can buffer the encoding packets that cannot be decoded.During retransmission procedure the source focuses on the destination requirements.In the same conditions the relay with higher transmission reliability is preferentially selected to improve the transmission efficiency.Simulation results show that the scheme proposed can effectively improve the retransmission efficiency compared with the traditional retransmission scheme with imperfect feedback in wireless multicast network.