The Research And Application Of Layer Video Multicast And QoS Core Problems

With the requirement for the application based on group communication such asvideo conference, remote education, video order and so on is increasing constantly, theapplication of video multicast is expected to become widespread in the Internet in thefuture. Video stream is sensitive to delay and jitter, requires large bandwidth andforeseeable delay and the ratio of lose. In other words, it has specific requires for QoS.However, Internet principally provides best-effort transmission service and do notconsider QoS metrics. So, it has not explicit guarantee for transmission time andreliability. Thus, it is needed a new network model which can afford end-to-end QoS tosatisfy the requirement of increasing video multicast.What's more, because of the asynchronism of user's requirements, performance ofhosts and network itself, the data source of multicast sending video data with single ratecan't satisfy all of recesivers. In order to solve this problem, this paper adopts layeredvideo multicast scheme, and therefore proposes new design schemes for transmissionnetwork and terminal systemes.In respect of network,on the research of multicast technology and IP QoSarchitecture, this paper proposes a network model which can support end-to-end QoSguarantee, and divides this network into core network and edge network which adoptdifferent QoS architecture to adapt respective network specialties.In the design of core network, this paper adopts DiffServ over MPLS networkmodel and illuminates this model and its core technologies. And then, the paperproposes a new multicast scheme supporting asynchronous QoS requirements calledMDMS. MDMS realizes the mechanism satisfying asynchronous QoS requirements in3th layer and the multichast mechanism using MPLS model in 2th layer. And then,through analyses about some characteristics of multicast service, memory overhead andaggregate tree in MDMS, this paper demonstrates that MDMS accords with its designgoal and can afford better performance than other schemes in core network.In the design of edge network, this paper adopts IntServ model to resilze QoSguarantee,and proposes a new muliticast routing protocol named DQSSMR on theresearch of some existing routing protocols used in IntServ model. DQSSMR discardsthe flooding of JOIN message and improves the selection arithmetic of candidate nodeand strategy of multi-path search. Analyse demonstrates the improvements of DQSSMRare effective. At last, in respect of terminal system, this paper proposes a design scheme forteiminal system of layered video multicast application. It includes the sending schemeof layered video data and a simple adaptive control strategy of terminal system. Theresults of simulation experiment demonstrate that the release scheme of video data andthe adaptive control mechanism are effective.