Impact of Upper Layer Adaptation on End-to-end Delay Management in Wireless Ad Hoc Networks

A good amount of research has been developed to support QoS issues in IEEE 802.11 ad hoc networks, such as QoS routing, MAC layer QoS support, and cross-layer QoS design. However, QoS solution at upper layers for real-time multimedia applications is overlooked. This paper investigates impact of the adaptation mechanisms at application layer and middleware layer on end-to-end delay management. Upper layer adaptation is a localized method with small overhead, and the adaptation mechanism is hardware independent. The application layer adaptor is to dynamically change the requirement levels based on end-to-end QoS measurement. The middleware adaptor is to dynamically adjust the service classes for applications by feedback control theory. We use real IEEE 802.11 ad hoc network environment to evaluate the impact of upper layer adaptation, and conclude that the upper layer adaptation for end-to-end delay is efficient in many scenarios, but it is not enough for contention scenarios, where lower layer scheduling should be adopted.