We investigate minimum energy broadcasting problem where mobile nodes have the capability to adjust their transmission range. The power consumption for two nodes at distance r is r/sup /spl alpha// + c, where /spl alpha/ /spl ges/ 2 and c is a constant that includes signal processing and minimal reception power. We show that, for c > 0 (which is realistic assumption), it is not optimal to minimize transmission range. Furthermore, we demonstrate that there exists an optimal radius, computed with a hexagonal tiling of the network area that minimizes the power consumption. For /spl alpha/ > 2 and c > 0, the optimal radius is r = /spl alpha//spl radic/(2c//spl alpha/-2), which is derived theoretically, and confirmed experimentally. We propose also a localized broadcast algorithm TR-LBOP that takes this optimal radius into account. This protocol is experimentally shown to be efficient compared to existing localized protocol LBOP and globalized BIP protocol. Most importantly, TR-LBOP is shown to have limited energy overhead with respect to BIP for all network densities, which is not the case with LBOP whose overhead explodes for higher densities.
['François Ingelrest', 'David Simplot-Ryl', 'Ivan Stojmenovic']
Target transmission radius over LMST for energy-efficient broadcast protocol in ad hoc networks