Research And Implementation Of IPTV Rapid Switching And Congestion Control On ACR

The convergence of networks represents the development of the networks technology and the direction of the market evolution. IP technology has been recognized as the best supporting technology for converging the three nets in the future because of its openness, connection and high market support. This thesis has studied how to support the IPTV operation in the IP network. On the base of "the research on system performance and key technology of the Large-scale Access Convergence Router" which is the significant special subject in the information technology field of the national "the tenth five-year plan" 863 plan, the thesis proposes "one step look-up table, two steps replication", the fast switch scheme of IPTV control multicast and LMERIO, the control arithmetic of multicast congestion. Based on these above, the thesis also presents the designed scheme, which concerning using the multicast technology to support IPTV service in ACR. And the thesis also depicts the EMD project realization of the hardware in detail.The main work and contribution of the thesis as follows:Firstly, it summarizes technology challenges and difficulties in the development of IPTV.Secondly, concerning the problems of severe lag when frequency channel switching , hardship multicast management and so on, the thesis proposes one kind fast multicast switching of controlled multicast based on the ACR construction ~ "one step look-up table, two steps replication". The key idea of the scheme is finishing the authentication, the watching rights and the look-up operation on the one step and puts the look-up operation which deals with long time-delay in the one step and realizes in parallel. It divides the fast replication into two steps and accordingly decrease the time of multicast switching and realize multicast management and fast switch of multicast.Thirdly, in order to avoid multicast congestion on the basis of the study control of multicast congestion of IP net, according to layered multicast idea of Streaming Media, the thesis proposes an arithmetic of multicast congestion control named LMERIO. The arithmetic can receive different layered packets based on the useable bandwidth and obligate bandwidth to avoid congestion. And it also can adjust lose rate and enhance using rate of the processing resource in order to the service level. Simulation results show the arithmetic has fast congestion speed, good stability and equity.Fourthly, based on the scheme of "one step look-up table, two steps replication" and LMERIO arithmetic, the thesis puts forward the whole scheme of EMD module of ACR router and the engineering design scheme of LMERIO arithmetic. And it has passed hardware experiment. According to the test of EMD and capability evaluation of IPTV channel switching time-delay, it shows that EMD can satisfy the designed function and capability requirement. And it also can satisfy the requirement of the short time-delay of IPTV channel switching.