Towards a cross layer framework for improving the QoS of delay sensitive heterogeneous WMSNs

Wireless multimedia sensor networks consist of thousands of sensor nodes and one or more sink nodes which are distributed in a geographical area to gather information about physical phenomenon of interest. Nowadays modern motes have many sensors running in them and they sense different physical quantities such as temperature, pressure, light etc. When these sensor nodes are used for monitoring mission critical applications they need to provide the quality of service required by different applications running in them. The QoS required by these applications include delivery of packets within deadline, improved reliability, reduced packet drop probability, reduced delay etc. In this paper, we propose a cross layer framework for improving the QoS of delay sensitive heterogeneous wireless multimedia sensor networks by considering interaction among MAC, network and transport layers. To provide fairness to sensor nodes that are far from the sink node in a multi hop heterogeneous network, dynamic priority is assigned to the packets based on the static priority, remaining time to deadline and the number of hops between the sensor node and the sink node. Sensor nodes are grouped into hierarchical clusters and a priority based medium access control scheme is used to assign time slots to the cluster members to transmit their sensed data to the cluster heads.