Constrained Relay Node Placement in Wireless Sensor Networks to Meet Connectivity and Survivability Requirements

The relay node placement problem for wireless sensor networks is concerned with placing a minimum number of relay nodes into a wireless sensor network to meet certain connectivity and survivability requirements. In this paper, we study constrained versions of the relay node placement problem, where relay nodes can only be placed at a subset of candidate locations. In the connected relay node placement problem, we want to place a minimum number of relay nodes to ensure the connectivity of the sensor nodes and the base stations. In the survivable relay node placement problem, we want to place a minimum number of relay nodes to ensure the biconnectivity of the sensor nodes and the base stations. For each of the two problems, we discuss its computational complexity, and present a framework of polynomial time O(1) -approximation algorithms with small approximation ratios.