A multiple access control protocol for an interactive multimedia network

We propose a multiple access protocol for the transmission of information packets from media servers (MS) to users in an interactive multimedia network. Digital video and data from MS are switched to users using the services of a broadband asynchronous transfer mode (ATM) virtual path crossconnect (VPX) network. The link to a cluster of users is shared by all MS that are in session with the users. The full bandwidth is dynamically allocated to one MS for a certain period of time based on the urgency of the data requests by the users. In the proposed medium access control protocol, new transmissions are scheduled by offering a token to a media server. The token message and its acknowledgment include all the required status and about the network entities involved in the data transaction. The performance of the proposed protocol in the presence of both data on demand (VOD) and video on demand (VOD) traffic is evaluated in terms of the probability of missing the deadline of a data request and the average response time to fulfill data requests. The aggregate arrival processes of interactive data requests by VOD and DOD users are assumed to be Poisson. We show that the available broadband link bandwidth for DOD data traffic is utilized efficiently in the sense that data packets for a large number of DOD users may be statistically multiplexed. The attainable statistical multiplexing gain depends on the number of VOD users retrieving video packets via the link and other traffic related parameters.