VAQMAQ: Video Aware QoS MAC Protocol for Wireless Video Sensor Networks

Abstract

Multimedia applications over wireless sensor networks are emerging rapidly. There is an increasing interest in the research community to design and develop critical services which require video monitoring or emergency voice calls over WSNs. On the other hand, storage, processing and bandwidth limitations of sensor nodes make multimedia data transmission a challenging issue for WSNs. In such context, multimedia coding and efficient exploration of the application contents at other layer of the stack may enhance the efficiency of WMSN applications. IEEE 802.11e is a variant of IEEE family of LAN standard which is most suited for QoS hungry multimedia traffic in modern Wireless Local Area Networks. However, it fairs poorly capable of handling multimedia flows efficiently in congested networks. The main reason poor performance is due to static resource allocation specified in IEEE 802.11e. The default TXOP limit values and priority assignment to I, B, P frames werestatically assigned. In this work, video aware cross-layer mechanism is proposed.Under the modified EDCA that permits dynamic allocation of TXOP limit values and change the priority of frames during congestion. The proposed protocol also copes with high load situations by selectively prioritizing and mapping multimedia frames to appropriate Access Categories (AC’s).