Research On Enhanced Multimedia Broadcast And Multicast Service Based On Network Coding

Recent years wireless networks have witnessed an explosive growth in enhanced multimedia broadcast and multicast service (E-MBMS). Due to the natural radio feature, media content can now be delivered to multiple users simultaneously and efficiently via a shared cellular channel. E-MBMS supports two types of services for multimedia delivery, namely streaming services and download services. Since the two services have high requirement of accuracy and instantaneity, and wireless channel is changing all the time, previously developed repair mechanisms for cable point-to-point streaming are no longer applicable, making video streaming over E-MBMS even more challenging.Network coding allows source and intermediate nodes to encode several packets, merge and forward them, so as to obtain the network performance gain. Some researches showed maximum capacity in a network can be achieved by using network coding. It also can be combined with erasure recovery mechanisms. The source node groups lost packets of different destination nodes together according to XOR operation, reducing the amount of radio restoration, improving the transmission efficiency. However, such a scenario is limited when receiving node loses not only one packet at a time. Scalable Video Coding (SVC) is a mainstream coding of source node in E-MBMS. There is no recovery mechanism for SVC layer coding now.User cooperation means mobile devices can exchange data packets with neighboring devices nearby over short-range links, to achieve a common or individual goal. Short link often has good channel condition without interference from cellular link. If we can integrate local user cooperation with error correction, the challenge cellular link unable to deal with may be solved.In this paper we present a novel E-MBMS user cooperative erasure recovery mechanism based on network coding. Local cooperative repair together with network coding is used to save total overhead of links and reduce the retransmission times, for purpose of improving Quality of Service (QoS) of video streaming. The simulation results show that the number of retransmissions declines a lot and link overhead can be saved through our mechanism.