Composite event coverage in wireless sensor networks with heterogeneous sensors

Event monitoring is a popular task carried out by Wireless Sensor Networks (WSNs). A composite event involves multiple properties requiring different types of sensors to monitor. Considering the costs of different deployment of heterogeneous sensors and the total budget for a monitored region, this paper investigates the composite event coverage problem with the purpose of optimizing coverage quality subjecting to the constraint of not exceeding the total budget. This is a novel coverage problem which is different from the traditional ones where deployment costs of sensors, total budget and composite events are not considered. Two exact algorithms are proposed whose time complexities are O(n^k) and O(n^k-1) respectively in the worst case, and a (1 - e^-1)-approximate algorithm are designed. The simulation results indicate the efficiency and effectiveness of the proposed algorithms.