Minimizing channel rental costs for topology control in multihop wireless networks

Multi-spectrum cognitive radios can be deployed in a wireless network to enhance the capacity of the network by reserving multiple channels in multiple frequencies for each link. In this paper we focus on the topology control approach for wireless networking with cognitive radios in which the network operator must lease channels that will be used in the network. We formulate a Channel Renting problem whose goal is to minimize the total number of channels used (or the cost of the channels used) while providing sufficient overall capacity for all subscribers of the network. This requires determining an active channel set for each edge and forming an efficient network topology to meet a set of given source-destination capacity requirements. We present a Mixed Integer Linear Programming (MILP) formulation to provide the optimal solutions of the problem and present an efficient algorithm that performs well compared to the optimal solution. Extensive simulation results show the algorithm is effective at providing robust solutions with minimal cost.