Optimal and resilient routing for many-to-one topologies in event triggered wireless sensor networks

Existing research initiatives for monitoring changes in the Earth's surface evince the great value of new opportunities for monitoring networks to be deployed in volatile regions prone to movement. Wireless sensor networks (WSNs) for monitoring such volatile regions need routing protocols that can tolerate unpredictable changes akin to that found in ad hoc networks, and, due to the stringent resource constraints of WSNs, routing protocols should also be light-weight and efficient. To satisfy these requirements, one of the most capable and widely assimilated protocols is the Ad hoc On-Demand Distance Vector (AODV) routing protocol, which offers low routing, processing, and memory overhead. The ad hoc and on-demand routing capabilities of AODV can efficiently maintain and reconnect unicast routes following incidents such as node demise and environmental changes that can obstruct, break, and fragment the routes. AODV, however, was not originally designed for WSNs in which numerous sensors typically send data to an associated base station or gateway node. It is this unique requirement in WSNs for efficient discovery of a many-to-one routing topology that is addressed in this work by proposing an incremental enhancement to AODV called Base Station Advertisements (BSA). The proposed hybrid protocol, AODV-BSA, offers efficient discovery of a near-optimal manyto- one routing topology by broadcasting a BSA at the network layer to discover near-optimal unicast routes from each sensor to its associated base station (BS). The many-to-one topology is then maintained via the ad hoc and on-demand capabilities of AODV, which provides robust maintenance by efficiently mending breaks and concatenating new extensions to routes in response to node demise and route fragmentation.