Enhanced availability in randomly deployed wireless sensor networks via hybrid uni/omni-directional antennas

Availability is a critical requirement in any modern information system. For many classes of sensor networks, random deployment cannot be avoided and the associated wireless network connectivity characteristics significantly impact system availability. A highly available network must be able to sustain services such as data gathering and event-detection even during link losses owing to reasons that include intermittent interference and network attacks. Improved availability is often achieved by rerouting the traffic along alternative paths. Accordingly, k-connectivity is a key property of highly available networks. In this paper, we analyze k-connectivity of hybrid wireless networks that incorporate both omniand sectorized uni-directional antennas. We present results that help understand the relationship between node density, transmission radius, antenna beam width and the existence of disjoint paths between the networkpsilas member nodes and a sink. Analytical and simulation-based results are provided to motivate the use of this emerging paradigm. We demonstrate that under a broad class of conditions, a hybrid approach significantly improves k-connectivity and has a larger average number of disjoint paths between member nodes and the network sink even at lower node densities and transmission radii.