QoS-Aware Relay Node Placement in a Segmented Wireless Sensor Network

In some applications of wireless sensor networks (WSNs) it may be necessary to federate a number of disjoint segments. Linking these segments may be subject to varying inter-segment quality of service (QoS) requirements. This paper presents an effective approach for federating these segments. The main idea is to place relay nodes (RNs) in order to establish intersegment connectivity with the least number of RNs while meeting the desired QoS requirements. Finding the optimal number and position of RNs is shown to be NP-hard and heuristics are thus pursued. The deployment area is modeled as a grid with equal-sized cells. Each cell is evaluated based on the residual capabilities of RNs populated in the cell. The optimization problem is then mapped to finding the cell-based least cost paths that collectively meet the QoS requirements. The performance of the proposed approach is validated through simulation.