可靠多播方案的最佳有效负载长度研究

摘要

以保证可靠分发所需总传输时间为评判标准,在考虑分组头开销的条件下,研究了基于简单反馈重传、RS码(Reed-Solomon code)和LT喷泉码技术的3种多播方案中的有效负载长度选取问题,提出了通过理论分析确定最佳有效负载长度的方法,并以仿真实验进行验证.理论分析和仿真实验表明,对于不同的分组头大小和链路误比特率,各方案的有效负载长度均具有最佳取值;链路误比特率越高,最佳有效负载长度所带来的性能增益越明显.其中,基于LT喷泉码的可靠多播方案性能最优.%Using total transmission time-the time needed to guarantee reliable data dissemination -- as judgment criterion,the payload length selection problem was investigated for three multicast solutions which are based on simple feedback retransmission, Reed-Solomon codes, and LT fountain codes, respectively, with the consideration of packet overhead. A theoretical analysis method was proposed to determine the optimal payload lengths, which was verified by simulations.Analyses and simulations indicate, for variable packet overhead sizes and link bit error rates, each method considered has its optimal payload length. As link bit error rate increases, the performance gain brought by the selection of optimal payload lengths becomes more significant. Among the three solutions, the reliable multicast solution based on LT fountain codes has the most outstanding performance.