Coverage Based Expanding Ring Search for Dense Wireless Sensor Networks

Abstract

Expanding Ring Search (ERS) is a prominent technique used for information discovery in multi-hop networks where the initiator of search is unaware of any of the γ locations of the target information. ERS reduces the overhead of search by successively searching larger number of hops starting from the location of search initiator. Even though ERS reduces overhead of search compared to flooding, it still incurs huge cost which makes it unsuitable especially to energy constrained networks like Wireless Sensor Networks (WSNs). Moreover, the cost of search using ERS increases with node density, which limits its scalability in densely deployed WSNs. In this paper, we apply the principles of area coverage to ERS and propose a new protocol called Coverage Based Expanding Ring Search (CERS(k), where k is the amount of parallelism in search) for energy efficient and scalable search in WSNs. CERS(k) is configurable in terms of energy-latency trade-off which enables it applicable to varied application scenarios. The basic principle of CERS(k) is to route the search packet along a set of ring based trajectories that minimizes the number of messages transmitted to find the target information. We believe that query resolution based on the principles of area coverage provides a new dimension for conquering the scale of WSN. We compare CERS(k) with the existing query resolution techniques for unknown target location such as, ERS, Random walk search, and Gossip search.