Hop count discovery protocol for gradient based routing in wireless sensor networks

Wireless sensor networks are a challenging research field for the telecommunication engineer. The limited resources of the individual sensor nodes impose a redesign of the traditional wireless network protocols. These new designs aim primarily at reducing energy consumption and increasing scalability. Several gradient based routing protocols have been proposed in literature. They construct a cost field towards the sink to be able to forward data along the steepest gradient. A naive way to set up the cost field is flooding. In this paper we present an alternative approach based on received signal strength measurements and timers. The field is constructed in "consecutive waves" emanating from the initializing sink node. The considered cost is a combined metric which takes into account the minimum hop distance to the sink. A simulation study, using the OMNET++ network simulator environment, shows the feasibility, discusses the strengths and possible weaknesses of the proposed scheme and illustrates its energy efficient operation.