Hybrid Multimedia-on-Demand Systems 1

1 This work was supported by the City University of Hong Kong under Strategic Research Grant 7000604. 2 Please direct all correspondence to this author. Email:ewong@ee.cityu.edu.hk Fax: +852 2788-7791 Abstract—As broadband networks keep increasing in transmission speed, multimedia-on-demand (MOD) is expected to be one of the most popular broadband services in the near future. MOD systems can provide two types of services: interactive service and batch service. The interactive service provides each user with one dedicated stream. With it, the user can use the VCR function controls such as pause, forward and rewind. However, the service is expensive and not scalable to system size. With batch service, the users who request the same multimedia content within a batch period will be grouped together and served by one dedicated stream. Hence, the system can either use fewer resources or serve more customers. However, batch users must wait for programs to begin and are unable to perform VCR function control. In this paper, we take advantage of both services by considering an MOD system that provides both services. Also, we propose two methods to optimize their coexistence. In addition, an analytical model is derived for performance evaluation. Numerical results show that the proposed hybrid system really outperforms both individual systems. The hybrid system provides a superior solution to both the service providers and the users. Specifically, given a limited storage resource, the service provider receives more revenue by serving more users concurrently, while the users have a satisfactory viewing experience due to higher availability of programs and the low average waiting time.