Modeling spatial correlation for MAC protocols in event-driven wireless sensor networks

In event-driven scenario, each event triggers a large number of nodes for sensing and transmission, thus the nodes encounter spatially-correlated contention due to correlation between nodes in spatial domain. In this paper, a correlation model is proposed to describe the correlation characteristics of sensor nodes using the overlapped field of coverage where each node follows boolean disk coverage Model. Based on correlation model, C-INS algorithm is presented to exploit the spatial correlation in event area. In addition, a random correlated event traffic model for NS-2 network simulator is developed to apply the results of proposed correlation model to the MAC protocols. It is used as an example to show how to apply our correlation model to exploit the spatial correlation in event-driven workload. Simulations in NS2 are carried out with existing MAC protocols to measure the effectiveness of proposed correlation model and C-INS algorithm. The simulation results show that by exploiting spatial correlation network performance in terms of energy consumption and delay guarantee improves drastically. The analytical results of proposed correlation model shows good spatial correlation between nodes with a control parameterθ.