Cooperative Caching for Multimedia Streaming in Overlay Networks

Traditional data caching, such as web caching, only focuses on how to boost the hit rate of requested objects in caches, and therefore, how to reduce the initial delay for object retrieval. However, for multimedia objects, not only reducing the delay of object retrieval, but also provisioning reasonably stable network bandwidth to clients, while the fetching of the cached objects goes on, is important as well. In this paper, we propose our cooperative caching scheme for a multimedia delivery scenario, supporting a large number of peers over peer-to-peer overlay networks. In order to facilitate multimedia streaming and downloading service from servers, our caching scheme (1) determines the appropriate availability of cached stream segments in a cache community, (2) determines the appropriate peer for cache replacement, and (3) performs bandwidth-aware and availability-aware cache replacement. By doing so, it achieves (1) small delay of stream retrieval, (2) stable bandwidth provisioning during retrieval session, and (3) load balancing of clients' requests among peers

Desktop multimedia environments to support collaborative distance learning

Desktop multimedia conferencing, when two or more persons can communicate among themselves via personal computers with the opportunity to see and hear one another as well as communicate via text messages while working with commonly available stored resources, appears to have important applications to the support of collaborative learning. In this paper we explore this potential in three ways: (a) through an analysis of particular learner needs when learning and working collaboratively with others outside of face-to-face situations; (b) through an analysis of different forms of conferencing environments, including desktop multimedia environments, relative to their effectiveness in terms of meeting learner needs for distributed collaboration; and (c) through reporting the results of a formative evaluation of a prototype desktop multimedia conferencing system developed especially for the support of collaborative learning. Via these analyses, suggestions are offered relating to the functionalities of desktop multimedia conferencing systems for the support of collaborative learning, reflecting new developments in both the technologies available for such systems and in our awareness of learner needs when working collaboratively with one other outside of face-to-face situations

Architecture for Cooperative Prefetching in P2P Video-on- Demand System

Most P2P VoD schemes focused on service architectures and overlays optimization without considering segments rarity and the performance of prefetching strategies. As a result, they cannot better support VCRoriented service in heterogeneous environment having clients using free VCR controls. Despite the remarkable popularity in VoD systems, there exist no prior work that studies the performance gap between different prefetching strategies. In this paper, we analyze and understand the performance of different prefetching strategies. Our analytical characterization brings us not only a better understanding of several fundamental tradeoffs in prefetching strategies, but also important insights on the design of P2P VoD system. On the basis of this analysis, we finally proposed a cooperative prefetching strategy called "cooching". In this strategy, the requested segments in VCR interactivities are prefetched into session beforehand using the information collected through gossips. We evaluate our strategy through extensive simulations. The results indicate that the proposed strategy outperforms the existing prefetching mechanisms.Comment: 13 Pages, IJCN

QoE-centric management of multimedia networks through cooperative control loops

The Internet has evolved from a service to transport simple text files into a platform for transporting a variety of complex multimedia services. The initial centralized management systems were not designed and are therefore not able to perform efficient management of Quality of Experience (QoE) for these complex services. Deploying an autonomic management system resolves these complexity issues and allows efficient resource allocation based on the service type, end-user requirements and device characteristics. However, existing autonomic management systems only allow limited cooperation between different autonomic elements (AE), which limits their capabilities to provide end-to-end QoE assurance. This research will therefore design cooperative AEs, optimize their organization and provide cooperative allocation algorithms to optimize end-to-end QoE

Collaborative spectrum sensing optimisation algorithms for cognitive radio networks

The main challenge for a cognitive radio is to detect the existence of primary users reliably in order to minimise the interference to licensed communications. Hence, spectrum sensing is a most important requirement of a cognitive radio. However, due to the channel uncertainties, local observations are not reliable and collaboration among users is required. Selection of fusion rule at a common receiver has a direct impact on the overall spectrum sensing performance. In this paper, optimisation of collaborative spectrum sensing in terms of optimum decision fusion is studied for hard and soft decision combining. It is concluded that for optimum fusion, the fusion centre must incorporate signal-to-noise ratio values of cognitive users and the channel conditions. A genetic algorithm-based weighted optimisation strategy is presented for the case of soft decision combining. Numerical results show that the proposed optimised collaborative spectrum sensing schemes give better spectrum sensing performance