Abstract
Internet-of-Things (IoT) technology has received much attention due to its great potential to interconnect billions of devices in a broad range of applications. IoT networks can provide high-quality services for a large number of users and smart objects. On the other hand, massive connectivity in IoT networks brings problems associated with spectral congestion. This issue can be solved by applying cognitive radio (CR) and non-orthogonal multiple access (NOMA) techniques. In this respect, this paper studies the performance of cooperative CR-NOMA enabled IoT networks over a generalized α - μ fading channel model. Closed-form analytical expressions of the end-to-end outage probability (OP) for the secondary NOMA users are derived using the Meijer's G-function with a consideration of the impacts of the interference temperature constraint, primary interference, residual hardware impairments and imperfect successive interference cancellation. Moreover, to acquire some useful insights on the system performance, asymptotic closed-form OP expressions are provided. Additionally, the impact of α and μ fading parameters on the outage performance is examined and, as a result, it is concluded that the system performance sufficiently improves as α and/or α increase. Furthermore, the outage performance of the proposed system model is shown to outperform that of an identical IoT network operating on orthogonal multiple access. Finally, the provided closed-form OP expressions are validated with Monte Carlo simulations.
Highlights
The Internet-of-Things (IoT) paradigm has recently received much attention, with research covering technology advances in several emerging wireless applications, such as deviceto-device (D2D) [1], body area networks [2] and vehicleto-vehicle [3] communications
We use a non-homogeneous behavior of α − μ distribution in the proposed model by considering practical cases, where the cognitive radio (CR)-non-orthogonal multiple access (NOMA) network experiences different channel fading from one time slot to another, i.e., Rayleigh / Nakagami-m, Rayleigh / Weibull, Nakagami-m / Weibull, Nakagami-m / Rayleigh, etc
Regarding the SIR- versus SNR-based outage probability (OP) comparison, it shows that the OP of NOMA users degrades as the primary interference power level increases
Summary
The Internet-of-Things (IoT) paradigm has recently received much attention, with research covering technology advances in several emerging wireless applications, such as deviceto-device (D2D) [1], body area networks [2] and vehicleto-vehicle [3] communications. The outage performance was examined in [29], where a NOMA relaying system considering Nakagami-m fading channels was studied by assuming that the source transmits superimposed signal to multiple destinations with help of AF relay working in the FD regime. This paper investigates the relay-aided CR-NOMA enabled IoT network using the generalized α − μ fading distribution and consisting of a primary transmitter and receiver as well as secondary source, relay and K destination users. Different from [51], where the authors studied cooperative NOMA systems over α − μ distribution without considering interference-limited scenario, we investigate relay-aided underlay CR-NOMA systems considering primary and secondary interference terms. Closed-form expressions for another asymptotic analysis of the OP at high signal-to-noiseratio (SNR) are obtained to gain more technical insights on the system performance. We use a non-homogeneous behavior of α − μ distribution in the proposed model by considering practical cases, where the CR-NOMA network experiences different channel fading from one time slot to another, i.e., Rayleigh / Nakagami-m, Rayleigh / Weibull, Nakagami-m / Weibull, Nakagami-m / Rayleigh, etc. The derived analytical expressions are used to evaluate the impact of several fading and system parameters on the network performance, where results demonstrate that the performance can be improved sufficiently as α and/or μ are/is increased
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