Target transmission radius over LMST for energy-efficient broadcast protocol in ad hoc networks

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^α + c, where α ≥ 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 α > 2 and c > 0, the optimal radius is r = α√(2c/α-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.