Design and Optimization for VoD Services With Adaptive Multicast and Client Caching

Multicast and prefix caching are two promising approaches to provide scalable video-on-demand (VoD) services. We contribute to solve the adaptive multicast delivery and the cache allocation problem for VoD services with client caching under asynchronous client requests. We first propose a client caching enabled adaptive multicast delivery scheme, which combines the stream merginglike method with prefix caching and adaptive modulation and coding, to fully exploit the multicast opportunity among asynchronous requests from heterogeneous clients. Next, we derive the bandwidth consumption of the proposed delivery scheme under a given prefix cache allocation and Poisson arrival request. We then optimize the cache allocation to minimize the average bandwidth consumption, and the problem is proved to be convex and solved effectively. Finally, three extreme cases are studied to provide closed-form solutions and more insight on the cache allocation and the delivery scheme for VoD systems.