scholarly journals A Power-Domain NOMA Inspired Overlay Spectrum Sharing Scheme

2018 ◽  
Author(s):  
Fazlul Kader
Keyword(s):  
Spectrum Sharing ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
User Needs ◽  
Sum Capacity ◽  
Closed Form Solutions ◽  
Sharing Scheme ◽  
Power Domain ◽  
Cooperative Spectrum Sharing ◽  
Capacity Gain

Non-orthogonal multiple access (NOMA) and cooperative spectrum sharing (CSS) are integrated into this work to enhance both spectrum efficiency and utilization. An overlay spectrum sharing is proposed by exploiting NOMA in coordinated direct and relay transmission (CDRT) (termed as CSS-NOMA-CDRT). In CSS-NOMA-CDRT, a primary strong NOMA user is directly served by primary transmitter (PT), whereas a primary NOMA weak user needs the assistance of a relay to communicate with PT. Instead of using a dedicated relay, a secondary transmitter (ST) acts as a relay to forward the primary symbol to NOMA weak user and ST transmits own symbol to its receiver at the same time. The performance of the proposed CSS-NOMA-CDRT is evaluated along with closed-form solutions, in terms of ergodic sum capacity and outage probability. Through the analytical and Monte Carlo simulation results, it is demonstrated that CSS-NOMA-CDRT can obtain remarkable capacity gain as compared to the conventional NOMA-based CDRT.

A Novel User Grouping Algorithm for Downlink NOMA

2021 ◽  
Author(s):  
Navideh Ghafouri Jeshvaghani ◽  
Naser Movahhedinia ◽  
Mohammad Reza Khayyambashi
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Spectrum Efficiency ◽  
System Capacity ◽  
Substantial Impact ◽  
User Grouping ◽  
Radio Access ◽  
Power Domain ◽  
Rate Maximization ◽  
Sum Rate

Abstract Non-orthogonal multiple access (NOMA) is one of the promising radio access techniques for resource allocation improvement in the 5th generation of cellular networks. Compared to orthogonal multiple access techniques (OMA), NOMA offers extra benefits, including greater spectrum efficiency which is provided through multiplexing users in the transmission power domain while using the same spectrum resources non-orthogonally. Even though NOMA uses Successive Interference Cancellation (SIC) to repeal the interference among users, user grouping has shown to have a substantial impact on its performance. This prformance improvement can appear in different parameters such as system capacity, rate, or the power consumption. In this paper, we propose a novel user grouping scheme for sum-rate maximization which increases the sum-rate up to 25 percent in comparison with two authenticated recent works. In addition to being matrix-based and having a polynomial time complexity, the proposed method is also able to cope with users experiencing different channel gains and powers in different sub-bands.

scholarly journals A Full Diversity Cooperative Spectrum Sharing Scheme for Cognitive Radio Networks

IEEE Access ◽  
2017 ◽  
Vol 5 ◽  
pp. 17722-17732 ◽  
Author(s):  
Raed F. Manna ◽  
Fawaz S. Al-Qahtani ◽  
Salam A. Zummo
Keyword(s):  
Cognitive Radio ◽  
Cognitive Radio Networks ◽  
Spectrum Sharing ◽  
Radio Networks ◽  
Full Diversity ◽  
Sharing Scheme ◽  
Cooperative Spectrum Sharing

scholarly journals Time Switching Based Wireless Powered Relay Transmission with Uplink NOMA

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5467
Author(s):  
Zhihua Lin ◽  
Shihua Cao ◽  
Jianqing Li
Keyword(s):  
Multiple Access ◽  
Relay Node ◽  
Base Station ◽  
Spectrum Efficiency ◽  
Transmission Model ◽  
System Throughput ◽  
Time Switching ◽  
Power Domain ◽  
End Node ◽  
Save Energy

Non-orthogonal multiple access (NOMA) utilizes power domain multiplexing to improve spectrum efficiency compared with orthogonal multiple access (OMA). In the Internet of Things (IoT) uplink NOMA networks, if the channel between the far-end node and the base station is in deep fading, allocating larger transmitting power for this node cannot achieve higher spectrum efficiency and overall system throughput. Relay cooperative communication reduces the transmitting power at the far-end node but leads to extra energy expenditure at the relay node. Fortunately, simultaneous wireless information and power transfer (SWIPT) is advocated in energy-constrained IoT networks to save energy consumption. However, early works all focus on energy harvesting (EH) from one source node or one dedicated power supply station. In this paper, we propose a time switching based wireless powered relay transmission model with uplink NOMA where our EH technique can harvest energy from two simultaneously transmitting nodes. More importantly, by optimizing relay position more energy is harvested from the near-end node at the relay and relay signal attenuation to the destination is reduced as well. Furthermore, the closed-form expressions of outage probability and overall system throughput are derived, and numerical results prove that NOMA in our EH scheme achieves better performance compared to the traditional EH scheme and OMA by optimizing the position of the relay node, time switching factor and so on.

scholarly journals Exploiting non-orthogonal multiple access in device-to-device communication

2021 ◽  
Vol 22 (2) ◽  
pp. 919
Author(s):  
Sang Hoon Lee ◽  
Soo Young Shin
Keyword(s):  
Closed Form ◽  
Interference Cancellation ◽  
Multiple Access ◽  
D2d Communication ◽  
System Capacity ◽  
Time Sharing ◽  
Sum Capacity ◽  
Closed Form Solutions ◽  
Device To Device ◽  
Device To Device Communication

This paper proposes an uplink non-orthogonal multiple access (NOMA) system with device-to-device (D2D) communication, enabling NOMA users to communicate with other users/devices using D2D communication to improve the system capacity. In the NOMA-D2D system, two cellular users communicated with the BS using uplink NOMA, and two cellular users simultaneously communicated with the D2D users using downlink NOMA. Closed-form solutions for the ergodic sum capacity of the proposed system are derived analytically. The analytical results are validated via simulations and they are compared with the results obtained from conventional schemes. The comparison shows that, in scenarios where efficient interference cancellation can be achieved, the proposed NOMA system with the D2D model can achieve higher capacity gains than conventional benchmark schemes. When  dB, NOMA-D2D achieves capacity gains of 192.2% and 157.5% over the conventional OMA and the time-sharing-based NOMA, respectively.

scholarly journals Throughput and Outage Probability Analysis for Cognitive Radio-Non-Orthogonal Multiple Access in Uplink and Downlink Scenarios

2020 ◽  
Vol 7 (4) ◽  
pp. 659-666
Author(s):  
H.T. Madan ◽  
Prabhugoud I. Basarkod
Keyword(s):  
Cognitive Radio ◽  
Outage Probability ◽  
Power Allocation ◽  
Cognitive Radio Networks ◽  
Multiple Access ◽  
Radio Networks ◽  
Spectrum Efficiency ◽  
Secondary Users ◽  
Power Domain ◽  
The Impact

Non orthogonal multiple access (NOMA) in cognitive radio (CR) network has been recognized as potential solution to support the simultaneous transmission of both primary and secondary users. In addition, CR-NOMA can also be used to serve multiple secondary networks in overlay cognitive radio networks. The aim of our work is to increase the secondary user’s throughput without compromising in QoS requirements of the primary users. Our presented work analyses the performance of power domain NOMA in cognitive radio networks for both uplink and downlink scenarios. The primary aspect of the work is to investigate the impact of power allocation on spectrum efficiency and fairness performance of CR-NOMA. Objective function is to maximize the overall throughput under the QOS constraints of the users. We have derived closed form expressions for optimized power allocation coefficient(α) for CR-NOMA uplink and downlink communications. Parameters causing the channel outage, have been examined and conditions for outage probability is derived for CR-NOMA communication. Finally, we have presented the simulation results to validate the mathematical models that are developed for power allocation coefficient and outage probability.

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