Collaboration and Optimization for Multimedia Communications

The advances of Internet and wireless access technologies have opened up new opportunities to serve high quality, on-demand multimedia applications. Applications like mobile TV, IPTV, on-demand streaming, and peer-to-peer video sharing have fundamentally changed the content distribution landscape, and have been accelerating a social and engineering revolution in media distribution and consumption. To achieve the ultimate goals of total freedom in self-expression, seamless mobile access, and anytime anywhere media consumption, technology advances in various areas need to be reexamined and jointly utilized under a coherent optimization framework to reach an efficient end-to-end media delivery solution. New models, metrics, and methodologies in source, and channel coding, distributed and collaborative communications are needed to intelligently adapt the multimedia content to suit user preferences, meet device and network constraints, and achieve better communication resource utilization. The source coding and adaptation decisions of media sources need to be reconciled with the limited network resources, end-user preferences, and resource allocation schemes at network nodes. Distributed optimization schemes like pricing and game theoretical approaches are needed to improve resource allocation and management efficiency. In this special issue on multimedia networking, we present several papers that address such issues. The first paper of this special issue, " A collaborative wireless access to on-demand services " by Z. Naor, presents a collaborative access scheme that exploits the broadcast nature of the wireless communications in order to achieve better multicast content delivery. The proposed method is particularly suitable for sessions of long time durations, for applications where clients can subscribe to ahead of time, and for applications in which the clients receive the same information simultaneously. The second paper of this special issue, " A stream tapping protocol involving clients in the distributions of videos on demand " by S. Kulkarni et al., presents a stream tapping protocol that involves clients in the video distribution process. Compared with the traditional taping protocol, the proposed one greatly reduces the workload of the video server by delegating part of the content distribution process to the clients who are watching the video. The third paper of this special issue, " Automatic bandwidth adjustment for content distribution in MPLS networks " by D. Moltchanov, discusses a new algorithm for dynamic resource adaptation to temporarily changing traffic conditions in multiprotocol label switching (MPLS) networks. The major advantage of the proposed approach is that it is fully autonomous, takes into account statistical characteristics of traffic …