power optimization in fault-tolerant topology control algorithms for wireless multi-hop networks
In ad hoc wireless networks, it is crucial to minimize power consumption while maintaining key network properties. This work studies power assignments of wireless devices that minimize power while maintaining k-fault tolerance. Specifically, we require all links established by this power setting be symmetric and form a k-vertex connected subgraph of the network graph. This problem is known to be NP-hard. We show current heuristic approaches can use arbitrarily more power than the optimal solution. Hence, we seek approximation algorithms for this problem. We present three approximation algorithms. The first algorithm gives an O(ka) approximation where a is the best approximation factor for the related problem in wired networks (the best a so far is in O(log k).) Then, using a more complicated algorithm and careful analysis, we achieve O(k) approximation for general graphs. We then present simple and practical distributed approximation algorithms for the cases of 2- and 3-connectivity in geometric graphs. In addition, we demonstrate how we can generalize this algorithm for k-connectivity in geometric graphs. Finally, we show that these approximation algorithms compare favorably with existing heuristics. We note that all algorithms presented in this paper can be used to minimize power while maintaining k-edge connectivity with guaranteed approximation factors.
topology control approximation algorithms power conservation graph properties graph model ad hoc networks