Maintaining Connectivity in Sensor Networks Using Directional Antennae

Connectivity in wireless sensor networks may be established using either omnidirectional or directional antennae. The former radiate power uniformly in all directions while the latter emit greater power in a specified direction thus achieving increased transmission range and encountering reduced interference from unwanted sources. Regardless of the type of antenna being used the transmission cost of each antenna is proportional to the coverage area of the antenna. It is of interest to design efficient algorithms that minimize the overall transmission cost while at the same time maintaining network connectivity. Consider a set S of n points in the plane modeling sensors of an ad hoc network. Each sensor is equipped with a fixed number of directional antennae modeled as a circular sector with a given spread (or angle) and range (or radius). Construct a network with the sensors as the nodes and with directed edges (u,v) connecting sensors u and v if v lies within u’s sector. We survey recent algorithms and study trade-offs on the maximum angle, sum of angles, maximum range and the number of antennae per sensor for the problem of establishing strongly connected networks of sensors. Evangelos Kranakis School of Computer Science, Carleton University, Ottawa, ON, K1S 5B6, Canada e-mail: [email protected] Danny Krizanc Department of Mathematics and Computer Science, Wesleyan University, Middletown CT 06459, USA e-mail: [email protected] Oscar Morales School of Computer Science, Carleton University, Ottawa, ON, K1S 5B6, Canada e-mail: [email protected]