  Random deployment of sensor nodes is susceptible to initial communication
hole, even when the network is densely populated. However, eliminating holes
using structural deployment poses its difficulties. In either case, the
resulting coverage holes can degrade overall network performance and lifetime.
Many solutions utilizing Relay Nodes (RNs) have been proposed to alleviate this
problem. In this regard, one of the recent solutions proposed using Artificial
Bee Colony (ABC) to deploy RNs. This paper proposes RN deployment using two
other evolutionary techniques - Gravitational Search Algorithm (GSA) and
Differential Evolution (DE) and compares them with existing solution that uses
ABC. These popular optimization tools are deployed to optimize the positions of
relay nodes for lifetime maximization. Proposed algorithms guarantee
satisfactory RNs utilization while maintaining desired connectivity level. It
is shown that DE-based deployment improves the network lifetime better than
other optimization heuristics considered.
