Abstract
In this paper, the performance of a dual-hop multiuser underlay cognitive network is thoroughly investigated by using a decode-and-forward (DF) protocol at the relay node and employing opportunistic scheduling at the destination users. A practical scenario where cochannel interference signals are present in the system is considered for the investigation. Considering that transmissions are performed over nonidentical Rayleigh fading channels, first, the exact signal-to-interference-plus-noise ratio (SINR) of the network is formulated. Then, the exact equivalent cumulative distribution function (cdf) and the outage probability of the system SINR are derived. An efficient tight approximation is proposed for the per-hop cdfs, and based on this, the closed-form expressions for the error probability and the ergodic capacity are derived. Furthermore, an asymptotic expression for the cdf of the instantaneous SINR is derived, and a simple and general asymptotic expression for the error probability is presented and discussed. Moreover, adaptive power allocation under the total-transmit-power constraint is studied to minimize the asymptotic average error probability. As expected, the results show that optimum power allocation improves the system performance compared with uniform power allocation. Finally, the theoretical analysis is validated by presenting various numerical results and Monte Carlo simulations.
Highlights
C OGNITIVE radio (CR) has become a more attractive research field in wireless communication for many researchers in the last few years [1]–[5]
This paper provides a comprehensive performance analysis for the effect of co-channel interference in practical multiuser dual-hop underlay cognitive radio networks, considering independent non-identical Rayleigh fading channels affecting the relay and the destination nodes
To calculate the per hop error probability, we propose the following theorem: Theorem 1: We are aiming to represent the per hop equivalent cumulative distribution function (CDF) for both first and second hops in a simpler form which is more convenient mathematically, such that we can carry out further investigation of the system performance
Summary
C OGNITIVE radio (CR) has become a more attractive research field in wireless communication for many researchers in the last few years [1]–[5]. This is because of its promise of using the existing frequency spectrum more efficiently. Three paradigms have been proposed for realizing the CR network [2]. Based on the simplicity of implementation, they are underlay, interweave and overlay. In an underlay CR scheme, there is a strict power constraint on the transmission power [2] for the purpose of the protection of the quality of service (QoS) of the primary user.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
