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In this paper, we design a secure transmission scheme in uplink and downlink of nonorthogonal multiple access (NOMA) system. In this scenario, two pairs of base stationuser can operate under the presence of eavesdropper. The relay plays an important role to forward signals from group of base stations to serve distant users. However, the eavesdropper can overhear signal which leads to secure performance need be reconsidered. To provide secure performance, we derive the closed-form expressions for strictly positive secrecy capacity (SPSC). In addition, we rely on relay for enlarge coverage area. The channel conditions meet imperfect channel state information (CSI) which shows degraded secure performance. Results confirm the relationship between transmit power at the source and and SPSC how many main parameters affecting secure performance metric. Furthermore, simulation results show that the uplink and downlink NOMA technique improves secure performance in the low SPSC region. We further conduct analysis by using Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

A full-duplex non-orthogonal multiple access (FD-NOMA) systems are expected to play a significant role in fifth generation (5G) networks, addressing spectrum efficiency and massive connections. In this regard, the feasibility of FD communications to improve spectrum utilization is main consideration in term of outage performance. Specifically, we derive exact formulas of outage probability for FD-NOMA, over Nakagami-m fading channels. Extensive analysis revealed that higher quality of channel leads to better performance. We verify expressions throughout Monte-Carlo simulations. [ABSTRACT FROM AUTHOR]

In a wireless system, dual-hop transmission requires Full-Duplex (FD) to transmit signals from the base station too far users. It is more beneficial if we deploy non-orthogonal multiple access to serve specific users, i.e. normal users (near and far users) and device-to-device users. The fairness and outage performance of these users can be studied. We particularly focus on mathematical analysis of outage performance which is computed based on Signal to Noise Ratio (SNR) of received signals at each kind of user. We derive a closed-form formula of such outage probability along with throughput. To realize both the FD NOMA, this paper performs system performance metrics and considers how self-interference make influences system performance. The simulation results validate the theoretical analysis and show that our scheme can obtain a better outage probability and throughput performance with high transmit SNR at the base station and lower required target rates. [ABSTRACT FROM AUTHOR]

The internet of things (IoT) in 5G and beyond wireless systems is interesting topic since IoT network will be platform to develop applications in the future. IoT will open a door for smart services and new wireless architecture. In this study, we consider multiple access technique applied in two-way cooperative scheme, namely two-way non-orthogonal multiple access (TW-NOMA). We derive expressions of outage probability for considered system using amplify and-forward (AF) relay protocol, and we show that fixed power allocation factors and target rates are main impacts on performance of AF TW-NOMA. We finally extend many scenarios to evaluate performance of two-user model and outage probability in a two-user scenario are numerically verified. It is confirmed that simulation results show that AF TW-NOMA provides better data rates and user fairness. [ABSTRACT FROM AUTHOR]

Nowadays, unmanned aerial vehicle (UAV) relays' assisted internet of things (IoT) systems provide facility in order to overcome the large scale fading between source and sink. The full-duplex scheme enables wireless network to provide higher spectrum efficient technology. This paper analyses performance of two users which are served by new emerging non-orthogonal multiple access (NOMA) technique. Exact outage probability of such two users are derived and checked via Monte-Carlo simulation. These analytical results provide guideline to design UAV in real application. This paper provides a comprehensive study to examine impact of interference, fixed power allocation factors to system performance. [ABSTRACT FROM AUTHOR]

In this paper, a downlink performance in non-orthogonal multiple access (NOMA) system is considered. With regard to different priority for two NOMA users, we exploit the closed-form expressions of outage probability over wireless fading channel following Nakagami-m fading. The fixed power allocation factor scheme is examined to reduce the complexity in computation regarding performance analysis. In our analysis, perfect successive interference cancellation (SIC) is applied in order to achieve perfect signal decoding operation. Simulation results show that the considered NOMA downlink scheme is affected by transmit SNR, power allocation factors, fading parameters. [ABSTRACT FROM AUTHOR]

In this paper, we consider downlink non-orthogonal multiple access,(NOMA) in which the relay selection (RS) scheme is enabled for cooperative,networks. In particular, we investigate impact of the number of relays on,system performance in term of outage probability. The main factors affecting,on cooperative NOMA performance are fixed power allocations coefficients,and the number of relay. This paper also indicate performance gap of,the outage probabilities among two users the context of NOMA. To exhibit,the exactness of derived formula, we match related results between,simulation and analytical methods. Numerical results confirms that,cooperative NOMA networks benefit from increasing the number of relay. [ABSTRACT FROM AUTHOR]

In this paper, new radio access scheme that combines Amplify-and-Forward (AF) relaying protocol and non-orthogonal multiple access (NOMA) system is introduced. In particular, different scenarios for fixed power allocation scheme is investigated. In addition, the outage probability of both weak and strong user is derived and provided in closed-form expressions. Such outage is investigated in high SNR scenario and comparison performance between these NOMA scenarios is introduced. Numerical simulations are offered to clarify the outage performance of the considered scheme if varying several parameters in the existing schemes to verify the derived formulas. [ABSTRACT FROM AUTHOR]

In the future wireless systems, non-orthogonal multiple-access (NOMA) with partial relay selection scheme is considered as developing research topic. In this paper, dual-hop relaying systems is deployed for NOMA, in which the signals are communicated with the assistance of decode-and-forward (DF) scheme. This paper presents exact expressions for outage probability over independent Rayleigh fading channels, and two partial relay selection schemes are provided. Using analytical result and Monte- Carlo method, we introduce forwarding strategy selection for fixed user allocation and exactness of derived formula is checked. The presented simulations confirm the the advantage of such proposed NOMA, and the effectiveness of the proposed forwarding strategy. [ABSTRACT FROM AUTHOR]

Considering a dual-hop energy-harvesting (EH) non-orthogonal multiple access (NOMA) relaying system, this paper consider novel relaying protocols based on time power switching-based relaying (TPSR) architecture for amplify-and-forward modes. We introduce novel system model relaying network with impacts of energy harvesting fractions and derive analytical expressions for outage probability for the information transmission link. It confirmed that right selection of power allocation for NOMA to obtain optimal performance. Theoretical results show that, in comparison with the conventional solutions, the proposed model can achieve optimal throughput efficiency for sufficiently small threshold SNR with condition of controlling time switching fractions and power splitting fractions appropriately in TPSR protocol. We also explore impacts of transmission distances in each hop, transmission rate, the other key parameters of TPSR to outage performance for different channel models. Simulation results are presented to corroborate the proposed methodology. [ABSTRACT FROM AUTHOR]