报文分流最优策略研究.pdf

ISSNN 111777TP Journal of Computer Research and Development 6( ) : 5 1 5 8, 2009 周安福 刘 敏 李忠诚 ( 100190) ( zhouanfu@ ict. ac. cn) Study on Optimal Packet Dispersion Strategy Zhou Anfu, Liu M in, and Li Zhongcheng ( Institute of Comp uting Technology , Chinese A cad emy of S ciences, Beij ing 100190) Abstract During the migration to next generation netw ork, an important trend is that IPbased netw ork w ill become the main vehicle for carrying audio and video applications. VoIP is a representative of such applications. How ever, packet loss is a main factor that degrades Q oS of V oIP, and bursty loss jeopardizes QoS of VoIP much more than scattered loss. Packet dispersion is a mechanism that disperses packets betw een parallel paths follow ing some dispersion strategies. It transforms bursty packet loss to scattered packet loss so as to improve QoS of VoIP. A lthough there are researches focusing on the use of packet dispersion in VoIP transmitting, the theoretic foundation of packet dispersion, such as to w hich extent packet dispersion can improve QoS and w hat is the optimal dispersion strategy, is unknow n. In this w ork, concentrating on these problems, the quantitative relation betw een Q oS of VoIP and the packet dispersion strategy is formulated as constrained optimization problems under Bernoulli packet loss model. Based on the closed form solution of the optimization problem, an algorithm is presented to find the optimal packet dispersion strategy. T he proposed optimal dispersion strategy is verified under Gilbert packet loss model with ns 2 simulation. Key words VoIP; Q oS; bursty packet loss; packet dispersion; optimal strategy 在向下 一代互联网络演进的过程中, 一个重要的趋势是IP 网络将成为语音视频等应用的 要 承载. VoIP 是一个重要的语音应用. 然而, IP 网络的丢包造成了VoIP 的服务质量不能得到保证, 并且 对于VoIP 而言, 连续丢包对其服务质量的影响要远大于分散