Abstract
In this paper outage performance of a secondary user (SU) is evaluated under an amplify and forward (AF) relay selection scheme with an imperfect channel state information (CSI) while the SU shares spectrum in an underlay cognitive radio network (CRN). In underlay, the SU coexists with primary user (PU) in the same band pro- vided the interference produced by SU at the PU receiver is below an interference threshold of PU. This limits the transmission power of SU and coverage area. Relays help to improve the performance of SU in such underlay sce- nario. However relays are also constrained in their trans- mit power due to interference constraint imposed by PU. Closed form expression of the outage probability of SU with maximum transmit power constraint of relay under imperfect CSI is derived. A scaling factor based power control is used for the SU transmitter and the relay in or- der to maintain the interference constraint at the PU re- ceiver due to imperfect CSI. The impact of several param- eters viz. correlation coefficient, channel estimation error, tolerable interference threshold, number of relays and the maximum transmit power constraint of relay on SU per- formance is investigated. A MATLAB based test bed has also been developed to carry out simulation in order to validate the theoretical results.
Highlights
Due to rapid growth in the field of wireless communication, the demand for the limited electromagnetic radio spectrum is increasing exponentially, which is causing spectrum scarcity
The secondary user (SU) are allowed to access the licensed spectrum allocated to the primary user (PU) as long as the interference produced at the PU receiver due to SU transmission remains below a predefined interference threshold [4]
In [22], we evaluated the outage probability of SU for Rayleigh faded channel with proactive decode and forward (DF) relay scheme considering imperfect channel state information (CSI) due to feedback delay and PU interference
Summary
Due to rapid growth in the field of wireless communication, the demand for the limited electromagnetic radio spectrum is increasing exponentially, which is causing spectrum scarcity. In [10], outage performance of cognitive relay network is evaluated for a given interference constraint of PU in an underlay spectrum sharing mode. Performance of SU in an underlay cognitive relay network under proactive decode and forward relaying scheme has been evaluated under joint constraints of average and peak interference constraint considering Rayleigh faded channel [14]. In [21], outage performance of a cognitive relay network with imperfect channel estimation in spectrum sharing model is evaluated. In [22], we evaluated the outage probability of SU for Rayleigh faded channel with proactive decode and forward (DF) relay scheme considering imperfect CSI due to feedback delay and PU interference. We derived novel closed form analytical expression for the outage probability of SU under the joint impacts of channel estimation error (σe2) and feedback delay (ρ) for a given outage constraint of PU.
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