Multi-Radio Wireless Sensor Networks: Energy Efficient Solutions for Radio Activation

Consider a wireless sensor network where each node has K radios r₁,r₂, ⋯ , r_K such that the one hop reachability distance (resp. energy expended) of (resp. by) radio r_i is greater than that of r_j 1 ≤ j <; i ≤ K. Given such a network, the problem of energy efficient radio activation is to minimize the total energy spent by the active radios across all nodes in order to maintain a connected network. We show that this problem is NP-Hard. We initially pay attention to the case of K = 2 and discuss a basic version of the radio activation problem in such networks. We propose approximation methodologies for solving this problem. Our analytical and experimental studies reveal that the greedy algorithm and the minimum spanning tree solution have the best worst case performance while the greedy algorithm has the best average case performance. To the best of our knowledge, this is one of the first few works to focus on optimal radio activation in generic multi-radio wireless networks.