Design and analysis of overlay cognitive relaying NOMA networks with non-ideal system imperfections

Abstract

Modern wireless networks must be implemented in order to handle the rapidly increasing data traffic caused by the proliferation of mobile applications and their integration into numerous parts of daily life. The most crucial criteria to take into account when deploying the next-generation communication networks are high-speed internet access, large capacity, low signal latency, extended battery lifetime, wide coverage, etc. In this context, cognitive radio and non-orthogonal multiple access (NOMA) have emerged as potential techniques to provide high throughput with widespread coverage for future wireless networks. This thesis appraises the per formance of an overlay cognitive non-orthogonal multiple access (OCNOMA) sys tem by employing an energy-harvesting based spectrum sharing cooperation (SSC) scheme in the presence of hardware impairments (HIs) at the transceiver nodes. Here, a secondary transmitter (ST) node with limited energy captures energy from the radio-frequency (RF) signal of the primary transmitter (PT) and uses it to send both its own information signal and the primary information signal using the NOMA approach. For this, we investigate two SSC schemes using amplify-and-forward (AF) and decode-and-forward (DF) relaying strategies, named as SSC-AF and SSC-DF schemes. Further, we evaluate the system throughput and energy efficiency for the considered OCNOMA system. Our results manifest the advantages of the proposed SSC schemes over the benchmark direct primary transmission and orthogonal multiple access (OMA) schemes.