Abstract
Non-orthogonal multiple access (NOMA) system can meet the demands of ultra-high data rate, ultra-low latency, ultra-high reliability and massive connectivity of user devices (UE). However, the performance of the NOMA system may be deteriorated by the hardware impairments. In this paper, the joint effects of in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) on the performance of two-way relay cooperative NOMA (TWR C-NOMA) networks over the Rician fading channels are studied, where two users exchange information via a decode-and-forward (DF) relay. In order to evaluate the performance of the considered network, analytical expressions for the outage probability of the two users, as well as the overall system throughput are derived. To obtain more insights, the asymptotic outage performance in the high signal-to-noise ratio (SNR) region and the diversity order are analysed and discussed. Throughout the paper, Monte Carlo simulations are provided to verify the accuracy of our analysis. The results show that IQI and ipSIC have significant deleterious effects on the outage performance. It is also demonstrated that the outage behaviours of the conventional OMA approach are worse than those of NOMA. In addition, it is found that residual interference signals (IS) can result in error floors for the outage probability and zero diversity orders. Finally, the system throughput can be limited by IQI and ipSIC, and the system throughput converges to a fixed constant in the high SNR region.
Highlights
The demand for new services and data rate has exploded for wireless communication, due to the growth of data traffic in the mobile Internet
In order to further evaluate the performance of the two-way relaying (TWR) C-non-orthogonal multiple access (NOMA) system, the system throughput is obtained for in-phase and quadrature-phase imbalance (IQI) and imperfect successive interference cancellation (ipSIC) conditions, as well as for that of the ideal condition, respectively, and given by: IQI,ipSIC
The asymptotic outage behaviour and the diversity order were discussed in the high signal-to-noise ratio (SNR) region
Summary
The demand for new services and data rate has exploded for wireless communication, due to the growth of data traffic in the mobile Internet. A higher data rate and massive mobile terminal access are required for the 5th Generation (5G) systems [1,2,3] Many new technologies such as massive multiple-input multiple-output (MIMO), non-orthogonal multiple access (NOMA), millimetre wave and device-to-device communication have been proposed to meet these demands [4]. In order to improve the system throughput, a network NOMA technique was proposed and analysed for the uplink coordinated multi-point transmission (CoMP) in [10] Cooperative communications is another solution to mitigate the fading effects of wireless environments [11]. Two-way relaying (TWR) has attracted a great deal of research attention because of its ability to achieve higher spectral efficiency in comparison to one-way relaying It has advantages in the utilization of wireless networks’ resources, improving spectral efficiency and enhancing network quality with regards to network throughput and error rate performance [16]. It is very necessary to study NOMA systems with Rician fading channels [36]
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