Spectrum Sharing with Underlay Constraints in Cognitive Radio Networks

Abstract

In this work, we examine the secondary service's possible capacity for overlay and underlay access schemes. Then, in contrast to the underlay technique, we suggest a novel mixed access strategy in which the secondary service transmits during idle periods without regard for the interference threshold limitation. In contrast to the overlay method, the mixed strategy transmits with a probability p(a) during busy periods, subject to satisfying the interference threshold criterion. The parameter p(a) is a supplementary service parameter that can be changed depending on the spectrum state. Furthermore, we demonstrate that the secondary services can modify probability to identify an appropriate access strategy well with goal of maximising the attained throughput depending on the interference induced by the principal service transmitter at the secondary service receiver.  The suggested spectrum-sharing methodology described in this study based on  decreased system complexity compared to the system in which applied interference at the primary receiver is necessary for spectrum sharing. We also provide a small power allocation technique for the underlay strategy whose obtained capacity is extremely near to the secondary service's maximum attainable capacity.