Abstract
In this paper, a cooperative non-orthogonal multiple access (NOMA) system is studied for the Internet-of-Things (IoT) in which a master node intends to serve multiple client nodes. The adaptive transmission strategy is proposed at the relay node, i.e., the relay can be half-duplex (HD) and/or full duplex (FD). In practical terms, numerous low-cost devices are deployed in such IoT systems and it exhibits degraded performance due to hardware imperfections. In particular, the effects of hardware impairments in the NOMA users are investigated. Specifically, the closed-form expressions are derived for the outage probability. Moreover, the ergodic capacity is also analysed. This study also comparatively analyzes the orthogonal multiple access (OMA) and NOMA with HD and/or FD relaying. The numerical results are corroborated through Monte Carlo simulations.
Highlights
The non-orthogonal multiple access (NOMA) technique has evolved as one of the potential technologies for efficient utilization of resources in wireless communication systems [1,2,3]
Considering the aforementioned FD or HD scenarios in NOMA approach, this section investigates the effect of hardware impairments on the performance of NOMA over Rayleigh fading conditions
For both FD/HD and orthogonal multiple-access (OMA)/NOMA adaptive architectures, it is observed that the derived outage probability and ergodic capacity perfectly matches with the simulations over entire range of signal-to-noise ratio (SNR) and other parameters which include power allocation factor, hardware impairment levels
Summary
The non-orthogonal multiple access (NOMA) technique has evolved as one of the potential technologies for efficient utilization of resources in wireless communication systems [1,2,3]. The NOMA improves throughput and coverage in the uplink and downlink of a wireless network by incorporate with relaying schemes reported in [5,6]. For all these advantages, NOMA is explored in the recent literature as the candidate for upcoming wireless communication systems such as 5G and beyond [1,2,3]. FD can be used to realize simultaneous NOMA uplink and downlink transmissions, such as in [22], both power allocation and subcarrier allocation have been investigated in such FD-NOMA scenario, and its multi-cell extension has been considered in [23]
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