Energy efficient broadcasting for situation awareness in ad hoc networks

Ad hoc wireless networks and sensor networks have nodes with limited battery power, and broadcasting is an important operation in such networks. In this paper, we consider energy efficient one-to-all and all-to-all broadcast communications in such power constrained networks. It is assumed that nodes have power control and can adjust the range of their transmissions. Given a network of N nodes in a playing field of size D/spl times/D, we establish a lower bound and present a simple scheme for a source-to-all broadcast operation. Using simulations we show that the average energy cost of broadcasting from any source is within 25% of this lower bound in a network of 100 nodes in a 500 m/spl times/500 m and a 1000 m/spl times/1000 m area. In the situation awareness application, each node periodically transmits a small packet of 60 bytes to all other nodes in the network. For this all-to-all broadcast communication, we present a cluster scheme when nodes are allowed to transmit long distances, and a chain based scheme when nodes are limited to short distances. Our schemes for situation awareness significantly improve the life of the network compared to schemes with direct transmissions.