Topology Control with Better Radio Models: Implications for Energy and Multi-Hop Interference

Topology Control (TC) is a well-studied technique used in wireless ad hoc networks to find energy-efficient and/or low-interference subgraphs of the maxpower communication graph. However, existing work has the following limitations: (1) theenergy model adopted is quite unrealistic — only transmit power is often considered and homogeneous decay of the radiosignal with distance is assumed; (2) the interference measure does not account for multi-hop communications. In this paper,we show the dramatic effect of the underlying energy and interference model on TC. In particular, we demonstrate that by usingmore realistic energy models and considering the effects of multi-hop interference, radically different conclusions about TC canbe drawn; namely that (1) energy efficient TC is essentially meaningless, since every link turns out to be “efficient”, and that(2) topologies identified as “interference-optimal” in the current literature can be extremely bad from the viewpoint of multi-hopinterference. Given these observations, we propose a new measure of link interference, extend it to deal with multi-hop interference,and design a corresponding optimal communication subgraph, called ATASP. We prove that, in the worst case, ATASP coincideswith the maxpower communication graph, showing that in some unfortunate situations also performing multi-hop interference-based TC is pointless. However, the simulation results with random node deployments presented in this paper show that, on theaverage, ATASP is a sparse subgraph of the maxpower communication graph, and multi-hop interference-based TC is indeedpossible. Since computing ATASP requires global knowledge, we experiment through simulation with known localized algorithmsfor energy-efficient TC and show that they perform well (on the average) with respect to multi-hop interference.