Energy efficient constrained shortest path first-based joint resource allocation and route selection for multi-hop CRNs

Cognitive radio networks (CRNs) are expected to improve spectrum utilization efficiently by allowing secondary users (SUs) to opportunistically access the licensed spectrum of primary users (PUs). In CRNs, source and destination SUs may achieve information interaction in an ad hoc manner. In the case that no direct transmission link between the SU transmission pairs is available, multi-hop relay SUs can be applied to forward information for the source and destination SUs, resulting in multi-hop CRNs. In this paper, we consider a multi-hop CRN consisting of multiple PUs, SU transmission pairs and relay SUs. Stressing the importance of transmission hops and the tradeoff between data rate and power consumption, we propose an energy efficient constrained shortest path first (CSPF)-based joint resource allocation and route selection algorithm, which consists of two sub-algorithms, i.e., CSPF-based route selection sub-algorithm and energy efficient resource allocation sub-algorithm. More specifically, we first apply CSPF-based route selection sub-algorithm to obtain the shortest candidate routes (SCRs) between the SU pair under the transmission constraints. Then, an energy efficient resource allocation problem of the SCRs is formulated and solved by applying iterative algorithm and Lagrange dual method. Simulation results demonstrate the effectiveness of the proposed algorithm.