Square-Based Location Update Protocol in wireless sensor networks

The introduction of mobile sink to wireless sensor networks (WSNs) can effectively address the hot-spot problem. However, as the sink moves in the sensing area, its location information needs to be broadcasted periodically to ensure network connectivity. This additional location update process will increase communication cost in each sensor node. To deal with this problem, this paper proposes a Square-Based Location Update Protocol (SLUP). In SLUP, the target area is divided into squares and subdivided into virtual grids. The sink does not need to broadcast its location information to the entire network when it only moves inside a square. Besides, the pattern of sink mobility is determined by real-time network parameters, e.g., Average Residual Energy of Sensor Nodes (ARESN) and sojourn time in a square. Such controlled mobility pattern can not only decrease the probability of moving out of the current square for the sink but also achieve load balancing in the network. Simulation results demonstrate that SLUP outperforms the traditional protocols in reducing the energy consumption of location update and prolonging the network lifetime.