Joint Power Splitting and Resource Allocation with QoS Guarantees in RF-harvesting-Powered Cognitive OFDM Relay Systems

In this paper, we focus on whether and how the quality-of-service (QoS) requirements can be guaranteed in radio frequency (RF)-harvesting-powered cognitive orthogonal frequency division multiplexing (OFDM) relay systems, where the available energy is extremely limited by power transfer capability, and the available spectrum is greatly restricted by primary networks. Thus, the joint power splitting ratio, subcarrier assignment and power allocation problem is formulated under the interference constraints and QoS requirements. In addition, in order to maximize the capacity of the secondary network, an optimal power splitting and resource allocation scheme is proposed based on dual decomposition as well as time sharing conditions. Simulation results show that the proposed scheme can perfectly satisfy the QoS requirements in spite of limited energy and spectrum, and outperforms conventional methods in terms of capacity and QoS satisfaction.