End-to-end delay control of multimedia applications over multihop wireless links

The proliferation of multimedia applications over mobile, resource-constrained wireless networks has raised the need for techniques that adapt these applications both to clients' Quality of Service (QoS) requirements and to network resource constraints. This article investigates the upper-layer adaptation mechanisms to achieve end-to-end delay control for multimedia applications. The proposed adaptation approach spans application layer, middleware layer and network layer. In application layer, the requirement adaptor dynamically changes the requirement levels according to end-to-end delay measurement and acceptable QoS requirements for the end-users. In middleware layer, the priority adaptor is used to dynamically adjust the service classes for applications using feedback control theory. In network layer, the service differentiation scheduler assigns different network resources (e.g., bandwidth) to different service classes. With the coordination of these three layers, our approach can adaptively assign resources to multimedia applications. To evaluate the impact of our adaptation scheme, we built a real IEEE 802.11 ad hoc network testbed. The test-bed experiments show that the proposed upper-layer adaptation for end-to-end delay control successfully adjusts multimedia applications to meet delay requirements in many scenarios.