Dynamic Window-Constrained Scheduling for Multimedia Applications

Advances in network technologies have introduced opportunities for applications such as video conferencing, tele-medicine, and real-time multimedia applications. These applications require strict performance (or quality of service) requirements on the information transferred across a network. This paper describes a new algorithm, called Dynamic Window-Constrained Scheduling (DWCS), designed to meet the service constraints on packets from multiple streams with different performance objectives. Using only two attributes, a deadline and a loss-tolerance per packet stream, we show DWCS: (1) can limit the number of late packets over finite numbers of consecutive packets in loss-tolerant or delay-constrained, heterogeneous traffic streams, (2) does not require a-priori knowledge of the worst-case loading from multiple streams to establish the necessary bandwidth allocations to meet per-stream delay and loss-constraints, (3) can safely drop late packets in lossy streams without unnecessarily transmitting them, thereby avoiding unnecessary bandwidth consumption, and (4) can exhibit both fairness and unfairness properties when necessary. In fact, DWCS can perform fair-bandwidth allocation, static priority (SP) and earliest-deadline first (EDF) scheduling. We show the effectiveness of DWCS using a streaming video application, running over ATM