反馈信道下基于LT码的空间网络广播传输策略设计

由于其特有的广域宽覆盖等特点，数据广播业务一直是空间网络的主要业务。然而空地间信道由于受到远距离、天气变化及遮挡等因素影响，数据传输时延长且丢包率较高。为进一步提高数据广播的性能，该文将反馈信息与LT码相结合，提出一种新的空间网络数据广播传输策略。与传统的数据广播策略相比较，新的传输策略利用反馈信息估计信道丢包率，并在此基础上引入信道状态矩阵和数据包选择权重向量，设计了数字喷泉新的编码方法，进而使得数据在重传阶段能够根据信道状态和重传概率实时调整。仿真结果表明，新的数据广播策略能够实现传输较少数据包的基础上实现原始数据的可靠接收。

Design of Efficient Broadcast Transmission Strategy for Spatial Networks Based on LT Codes with Feedback Channel

Since its wide coverage area, data broadcast is the major service of spatial system. However, due to the long distance and the complex, varied climate, data transmission suffers large round-trip-time and poor error performance. In order to achieve better performance, based on fountain codes and the feedback information, a novel and efficient data transmission strategy is proposed. Compared with typical protocols, the proposed strategy uses the feedback information to estimate the channel erasure probability. Besides, a weighted packet chosen vector is introduced into the fountain encoder to ensure the lost packets retransmitted in the order of the total consideration of their lost probability and the number of users which need a retransmission. Simulation results show that by the proposed scheme users can receive the data packets reliably while the total number of transmitted packets is less than the traditional protocols.