Cognitive full-duplex relay networks under the peak interference power constraint of multiple primary users

Xuan-Toan Doan,Nam-Phong Nguyen,Trung Q Duong,Daniel B Da Costa,Cheng Yin

doi:10.1186/s13638-016-0794-y

Abstract

This paper investigates the outage performance of cognitive spectrum-sharing multi-relay networks in which the relays operate in a full-duplex (FD) mode and employ the decode-and-forward (DF) protocol. Two relay selection schemes, i.e., partial relay selection (PRS) and optimal relay selection (ORS), are considered to enhance the system performance. New exact expressions for the outage probability (OP) in both schemes are derived based on which an asymptotic analysis is carried out. The results show that the ORS strategy outperforms PRS in terms of OP, and increasing the number of FD relays can significantly improve the system performance. Moreover, novel analytical results provide additional insights for system design. In particular, from the viewpoint of FD concept, the primary network parameters (i.e., peak interference at the primary receivers, number of primary receivers, and their locations) should be carefully considered since they significantly affect the secondary network performance.

Highlights

The explosion of data traffic over wireless communication has brought a huge demand for spectrum resources
The key principle behind the functionality of a spectrum sharing approach in cognitive radio networks (CRNs) is that unlicensed secondary users are allowed to access the licensed spectrum as long as the interference from the secondary transmitters is harmless to the primary receivers [3]
The secondary transmitters need to set their transmit powers in order to not cause any interference to the primary network that is above a predefined level

Summary

Introduction

The explosion of data traffic over wireless communication has brought a huge demand for spectrum resources. Note that a conventional relay uses two time-slots for two operating phases, i.e., listening to messages from the information source node and relaying message to the destination To tackle this spectral inefficiency, full-duplex (FD) techniques have been proposed for relay networks [9, 10], which enable relay nodes to transmit and receive signals simultaneously at the price of self-interference. Due to the existence of the common random variables (RVs), i.e., the channels from the source and/or selected relay to multiple primary receivers, the signal-to-noise-ratios (SNRs) of all links become correlated which makes the analysis troublesome To get around this challenge, we first apply the conditional probability on these RVs and derive the analytical expressions for the OP of the considered system. Appendices A, B, C, and D present the proofs of four Lemmas

System and channel models

Outage probability analysis

Conclusions