中继协作多播网络中基于最小集合覆盖的编码重传方案

为提高单中继协作多播传输效率，本文提出一种基于最小集合覆盖的分类网络编码重传方案.该方案充分利用中继节点协作传输的优势，将接收端的丢包按中继节点的接收状态分为两类，并按类先后进行编码重传.在各类丢包内部，根据对应的状态反馈矩阵寻找编码机会生成编码包，并将编码包的选择过程抽象为集合覆盖问题，通过求最小集合覆盖使重传次数逼近最小值.此外，在不增加所得前类编码包数的前提下，利用两类丢包之间的编码机会进一步生成新编码包，以减少重传编码包数，从而提高重传效率.分析与仿真结果表明了该方案的有效性.

Coded Retransmission Scheme Based on Minimum Set Coverage for Relay-Assisted Multicast

A classification network coding retransmission approach based on the minimal set coverage is proposed to improve the single relay cooperative transmission efficiency.In this scheme,to make full use of the advantage of relay-assisted transmission,the lost packets of receivers are classified into two categories according to the packet reception status of relay node after the initial transmission,and then the packets are encoded for retransmission according to the category sequentially.For each classification,according to the corresponding status feed matrix to search for encoding opportunities and generate encoding packets,the encoded packets selecting procedure is abstracted as the set coverage problem,and the number of retransmissions is approached the minimum value by solving the minimal set coverage problem.In addition,to reduce the number of retransmission packets and improve retransmission efficiency,encoding opportunities between the two types of lost packet are further used to generate new encoding packets on the premise of not increasing the current number of encoding packets.The analysis and simulation results show the effectiveness of the scheme proposed.