Optimizing power allocation in mission critical cognitive radio networks

Abstract

In order to advance the Mission Critical Networks (MCNs), new technologies such as Cognitive Radio (CR) has to be adopted. However, power is an important resource in CR Networks (CRNs) especially in disastrous environments where power outages are expected and communications become very important for search and rescue teams. Power allocation among Secondary Users (SUs) needs to be optimized particularly when the available transmission power is limited. In this paper, two algorithms are proposed to optimize power allocation among SUs that were successful in accessing the spectrum using hybrid interweave/underlay access scheme. The objective is to maximize the Spectral Efficiency (SE) while respecting the power budget constraints. The scenario in which the CRN has multiple SUs that are interfering with several PUs is addressed. Hence, different SUs will have different power and interference limits depending on PUs' activity. Moreover, since the complexity of the optimization algorithms can be high, a suboptimal discrete Cap-Limited Heuristic (CLH) algorithm is proposed. The CLH algorithm considers assigning power to SUs from a discrete set of power levels. Extensive simulations are performed and the results of the proposed suboptimal algorithm show a near optimal performance with lower complexity and reduced computational-cost.