Throughput Maximization in Energy Limited Full-Duplex Cognitive Radio Networks

In this paper, we consider a cognitive radio system with some of secondary users (SUs) equipped with multiple antenna full-duplex transceivers. We design a hybrid system to sense and access the spectrum opportunistically such that the SU operates on both underlay and interweave hybrid methods while the primary user (PU) may be active or inactive, respectively, to perform the sensing as agile as possible. Moreover, we maximize the throughput by allocating the spectral resources assuming limited available energy during each time frame with constraints on the interference to the primary user. We show that this problem is convex and propose a simple solution algorithm for it. Our simulations confirm the accuracy of our analytical and theoretical results and illustrate that the total achieved throughput of full-duplex cognitive radio even by considering self-interference is maximized under the assumed conditions.

I. Introduction

Cognitive radio (CR) aims to utilize the spectrum opportunities efficiently [1], [2] and is a promising dynamic spectrum access (DSA) technology. The secondary users may use one of three major DSA techniques namely underlay, overlay, and interweave to access the available spectrum [3]. The SUs can use underlay approach by transmitting concurrently with the PUs provided that communications of the PUs remain unaffected. In the overlay technique, the SUs transmit concurrently with the PUs and the power of the SUs are portioned not only for the communication of the secondary network but also they act as relay for the PU network. In the interweave DSA, the SUs coexist with the primary network as they transmit opportunistically when they recognize any spectrum holes.