Antenna selection and adaptive power allocation strategies for underlay spectrum sharing in mimo cognitive radio systems

Abstract

With the rapid emergence of new wireless communication technologies large bandwidth is needed to offer high data rate services But due to the limited availability of unallocated spectrum the spectrum shortage problem is increasing The increasing demands for new wireless services and high data rates have prompted the need for developing new solutions for efficient spectrum utilization Over the past decades Cognitive radio CR technology has been of greater research focus in developing dynamic spectrum access methods to utilize the scarce spectrum efficiently CR allows the unlicensed users Secondary Users SUs to dynamically utilize the spectrum resource of licensed users Primary Users PUs and autonomously adapt its parameters according to the environment in order to preserve the PUs communication quality Thus CR Network CRN overcomes spectrum scarcity and helps in improving the Spectral Efficiency SE Among the different operational paradigms of CR the underlay mode allows the SUs to transmit simultaneously with the PU in the same spectrum as long as the interference caused by the SUs to the PU is below the interference temperature limit otherwise called as interference threshold newline