Cross Layer Optimization in Multimedia Sensor Network

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 cross-layer optimization may enhance the expected efficiency of WMSN applications by considering the multimedia traffic characteristics and dynamic tuning of the MAC parameters. IEEE 802.11e is the indisputable standard for supporting multimedia traffic in modern Wireless Local Area Networks. However, it has been proven in capable of handling efficiently multimedia flows in congested networks. The main reason for this suboptimal behavior roots from the static nature of resource allocation specified in IEEE 802.11e. The default TXOP limit values and priority assignment to I, B, P frames proposed by IEEE 802.11e are, however, statically assigned. In this work, a cross-layer mechanism is introduced, under the modified EDCA that permits dynamic allocation of TXOP limit values and change the priority of frames during congestion. The mechanism is designed to cope with high load situations in IEEE 802.11e wireless infrastructure sensor networks by selectively prioritizing and mapping multimedia frames