Research On P2P Media Streaming Distribution In Wireless Mesh Networks

In a P2P media streaming distribution systems, peers communicate directly with each other for the media content by sharing the terminals'resources such as storage and bandwidth, which scatter in the internet. It can effectively decrease the traffic on the media server, and improve the service capacity of the media streaming distribution system. However there is some obvious difference between WMN and internet: a) the wireless terminals'storage are limited, and they are uncertain; b) the mobile terminals'power are limited, and the WMN's topology dynamically changes due to their mobility; c) the wireless transmitting pathes are unstable due to the wireless links'bandwidth churn, high packet loss rate and high bit error rate; d) the wireless multi-hop architecture causes high interference and high collision between nodes for the large scale media streaming distribution system. So, the nowadays P2P media streaming technologies don't suit to WMN. In order to improve the service capacity of the WMN media streaming distribution system, it is necessary to put more efforts on the research of WMN P2P media streaming distribution technologies, which jointly consider the feathers of WMN and media stream.To solve the above problems, in order to improve the WMN media streaming distribution system's service capacity,this thesis addresses on the key technologies of P2P media streaming distributuion system. First the distributed unstructured P2P overlay network is constructed which is according to the transmitting distance. Over it the main content of this thesis includes three issues: (1) nodes self-determinated caching strategy based on the content popularity and valid media content retrieve distance; (2) distributed power efficient media content locating algorithm based on the correlation of cached media content; (3) collaborated media content delivery algorithm by jointly considering the feathers of WMN and media stream. The works in this thesis has been supported by the Natural Science Foundation of China"Research on interactive media streaming distribution technologies in wireless mesh network"(No.60202005) and Natural Science Foundation of Hubei"Stream media caching based on quality and time two-dimension attribute"(No.2005ABA264).The contributions of this thesis include:1)The heuristic cache algorithm aimed to minimal the total effective network transmission cost is proposed for peer to peer media streaming distribution in WMN, it considers the media internal segment's popularity, the reliability of wireless hosts, and the difference of segment's reality cache dense and expected cache dense. It can effectively reduce the start-up delay and the total transmission cost of media streaming delivering in wireless mesh networks.2)Because media content is self-determinated cached by the nodes, but the cached contents are time-correlated, the hybrid ants-like search algorithm (HASA) for P2P media streaming distribution is proposed by considering the correlation-ship of cached media contents. It takes the advantages of random walks and ants-like algorithms for searching in unstructured P2P networks. It avoids a large amount of redundance query message caused by the flooding based algorithm. And by using the ant-colony theorem, it can record the media content query trails and fit the WMN topology's dynamical change. Simulation results showed that it can effectively improve the search efficiency for P2P media streaming distribution in WMN.3)Due to: 1) Media contents are divided cached; 2) HASA algorithm gets multiple nodes which can provide the same media content; and 3) the path diversity of WMN, the QoS optimal model for WMN P2P media streaming distribution is set up by integrating the wireless interference model and segment based media streaming rate-distortion model into consideration. The cross-layer multi-source multi-path multicast scheduler scheme is proposed and the genetic algorithm is employed to implement the scheme. Comparing to the multi-source multi-path unicast scheduler scheme, the multi-source multi-path multicast scheme adopts the wireless networks'character that the data is transmitted by broadcasting and can effectively decrease the streaming transmitting interfering probability. The simulation results shows that the multi-source multi-path multicast scheduler scheme can effectively decrease the total rate-distortion of P2P media streaming delivery over wireless mesh networks by comparing to the multi-source multi-path unicast scheduler scheme.