Research On Performance Of Cognitive Relay Networks Based On Wireless Portability And Non-Orthogonal Multiple Access

Non-orthogonal Multiple Access(NOMA)is considered as a key technology in the fifth generation mobile communication network because it not only improves the frequency spectrum efficiency of the system,but also reduces transmission delay and provides better fairness for users.Simultaneous Wireless Information and Power Transfer(SWIPT),can achieve power and energy transmission simultaneously,improve energy efficiency and prolong the battery life.In addition,Cognitive Radio(CR)is recognized as an effective method to improve spectrum utilization.In this paper,NOMA and SWIPT technologies are applied to cognitive radio networks to further improve the spectral efficiency and energy efficiency,and improve the transmission reliability.In order to reveal the performance gains brought by NOMA and SWIPT technologies for cognitive networks quantitatively and qualitatively,this paper mainly investigates the theoretical performance for the SWIPT-NOMA cognitive relay networks.The main contents are as follows.(1)To evaluate the transmission reliability in Rayleigh fading channel environment,an analytical expression of the overall interrupt probability of the system was derived for two transmission modes with direct link communication and two-phase communication.Furthermore,in order to reveal the influence law of channel parameters on interrupt performance,an asymptotic expression was derived under the condition of high signal-to-noise ratio the experimental results show that compared with the two-stage communication mode,the system can obtain better interrupt performance in the direct communication mode.In addition,compared with the NOMA cognitive relay network,the energy efficiency of NOMA cognitive relay network with SWIPT technology is improved by 75.35.(2)To evaluate the transmission reliability of signal transmission in Nakagami-m fading channel environment,the closed expression of subuser interrupt probability in SWIPT-NOMA cognitive relay network,the asymptotic expression under the condition of high signal-to-noise ratio and the throughput of the system are derived.The experimental results show that the larger the value of fading coefficient m,the better the interrupt performance of the system,and the corresponding throughput has been improved.In addition,compared with the traditional OMA network,the SWIPT-NOMA based cognitive relay network can provide users with better fairness and obtain higher energy efficiency.(3)Considering that it is impossible to realize perfect Serial Interference Canceller(SIC)in actual hardware design,the interrupt performance of primary and secondary users of SWIPT-NOMA cognitive relay network in Nakagami-m fading channel environment with incomplete SIC is studied.To obtain a more intuitive rule,the asymptotic expression of interrupt probability is analyzed when the signal-to-noise ratio approaches infinity.The experimental results show that the interrupt performance and spectrum utilization of the SWIPT-NOMA cognitive relay network with incomplete SIC are still better than the conventional OMA network when the optimal power distribution conditions are met.