Supporting Scalable Video Transmission in MANETs through Distributed Admission Control Mechanisms

Emerging multimedia applications over mobile devices are becoming very popular, especially over infrastructure wireless networks such as cellular and WLANs. However, providing this kind of services over infrastructure-less networks like ad hoc networks presents many additional problems. One of these problems is how to share resources fairly among the users involved. In this article we propose a QoS framework supporting scalable video streaming in mobile ad hoc networks based on distributed admission control and video traffic awareness. Our framework promotes fairness between video flows in terms of resource consumption. It also guarantees a significant reduction of the idle times experienced by users during periods of network saturation, thus increasing the video playout time in reception for all users. Using the IEEE 802.11e MAC technology as our basis for traffic differentiation, our framework, called DACME-SV (Distributed Admission Control for MANET's - Scalable Video), relies on a periodic probing process to measure the available bandwidth and the end-to-end delay on the path. DACME-SV adopts a cross-layer approach to determine the optimum number of video layers to transmit at any given time, thus avoiding network congestion and guaranteeing an acceptable video quality at the destination. Experimental results show that idle time periods are substantially decreased, while exhibiting a good overall performance in terms of throughput and delay.