3-D aerial and underwater sensor networks have found various applications in natural habitat monitoring, weather/earthquake forecast, terrorist intrusion detection, and homeland security. The resource-constrained and dynamic nature of such networks has made the stateless routing protocol with only local information a preferable choice. However, most of the existing routing protocols require sensor nodes to either proactively maintain the state information or flood the network from time to time. The existing stateless geometric routing protocols either fail to work in 3-D environments or have tendency to produce lengthy paths. In this paper, we propose a novel routing protocol, namely Geometric STAteless Routing (G-STAR) for 3-D networks. The main idea of G-STAR is to distributively build a location-based tree and find a path dynamically. G-STAR not only generalizes the notion of geographic routing from two modes to one mode, but also guarantees packet delivery even when the location information of some nodes is either inaccurate or simply unavailable regardless of the uses of virtual coordinates. In addition, we develop a light-weight path pruning algorithm, namely Branch Pruning (BP), that can be combined with G-STAR to enhance the routing performance with very little overhead. The extensive simulation results by ns-2 have shown that the proposed routing protocols perform significantly better than the existing 3-D geometric routing protocols in terms of delivery rate with competitive hop stretch. We conclude that the proposed protocols serve as a strong candidate for future high-dimensional sensor networks. (C) 2010 Elsevier B.V. All rights reserved.
