scholarly journals Capacity Analysis of Non-Orthogonal Multiple Access for Uplink and Downlink

2021 ◽  
Author(s):  
Saurabh Srivastava ◽  
Prajna Parimita Dash ◽  
Sanjay Kumar
Keyword(s):  
Cellular Networks ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Performance Measure ◽  
Capacity Analysis ◽  
Capacity Region ◽  
Sum Rate ◽  
User Rate ◽  
Allocation Factor

Non-orthogonal multiple access (NOMA) is intended to be used for the next generation 5G cellular networks. In this paper, the expressions for the channel capacities for symmetric and asymmetric NOMA networks have been analysed. The performance measure of user spectral efficiency and the sum-rate bounds, for the NOMA and the existing orthogonal multiple access (OMA) networks have been compared. Furthermore, analysis of user rate and capacity of NOMA network has been carried out and it is observed that the NOMA capacity region varies as a function of the power allocation factor. The corresponding models have been developed for both uplink and downlink, and simulated with MATLAB. The NOMA performance with imperfect Successive Interference Cancellation (SIC) decoding is also analysed for the downlink. It is also verified that the transmit power may be increased to counter the spectral efficiency reduction due to imperfect SIC.

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 Enhanced Integrated Satellite-Terrestrial NOMA with Cooperative Device-to-Device Communication

Telecom ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 126-149
Author(s):  
Michail Karavolos ◽  
Nikolaos Nomikos ◽  
Demosthenes Vouyioukas
Keyword(s):  
Wireless Networks ◽  
Spectral Efficiency ◽  
Multiple Access ◽  
D2d Communication ◽  
Efficiency Gains ◽  
Satellite Link ◽  
User Pairing ◽  
Device To Device ◽  
Channel Conditions ◽  
Sum Rate

The currently deployed terrestrial wireless networks experience difficulties while coping with the massive connectivity demands of coexisting users and devices. The addition of satellite segments has been proposed as a viable way of providing improved coverage and capacity, leading to the formation of integrated satellite-terrestrial networks. In such topologies, non-orthogonal multiple access (NOMA) can further enhance the efficient use of wireless resources by simultaneously serving multiple users. In this paper, an integrated satellite-terrestrial NOMA network is studied where cooperation between ground users is allowed, following the device-to-device (D2D) paradigm. More specifically, the proposed satellite NOMA cooperative (SANOCO) D2D scheme optimally selects pairs of users, by considering the channel conditions of the satellite and the terrestrial D2D links. In SANOCO-D2D users are served through NOMA in the satellite link, and then, if the weak user fails to decode its signal, terrestrial D2D communication is activated to maintain the total sum rate of the system. Comparisons with conventional orthogonal multiple access (OMA) and an alternative NOMA optimal user pairing scheme show that significant sum rate and spectral efficiency gains can be harvested through SANOCO-D2D under varying channel conditions and terrestrial D2D bandwidth.

scholarly journals Non-Orthogonal Multiple Access for Unicast and Multicast D2D: Channel Assignment, Power Allocation and Energy Efficiency

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3436
Author(s):  
Mariem Hmila ◽  
Manuel Fernández-Veiga ◽  
Miguel Rodríguez-Pérez ◽  
Sergio Herrería-Alonso
Keyword(s):  
Energy Efficiency ◽  
Resource Sharing ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Optimization Problems ◽  
Small Degree ◽  
Capacity Region ◽  
Performance Impact ◽  
Power Control Algorithm ◽  
Wireless Communications Systems

Non-orthogonal multiple access (NOMA) techniques have emerged in the past years as a solution to approximate the throughput performance of wireless communications systems to their theoretical capacity region. We consider in this paper an optimization-based model for multicast device-to-device (MD2D) communications where the channels are not orthogonal and may be (partially or fully) shared among the transmitters in each cluster. This setting leads naturally to the introduction of NOMA transmitters and receivers who use successive interference cancellation (SIC) to separate the superposed signals. To analyze the role of NOMA in MD2D, its performance impact, potential performance gains and possible shortcomings, we formulate a model that includes SIC operations in the decoders, so that higher rates can be attained when several sources transmit on the same channel(s). We also investigate the energy efficiency of the network (global and max-min) through a dynamic power control algorithm and present a centralized and a semi-distributed solution to these optimization problems. Through numerical simulations, we show that NOMA is able to improve both the sum-rate and the max-min rate of a MD2D network even from a small degree of resource sharing. Furthermore, these gains also improve the global energy efficiency on the network, but not always the max-min energy efficiency of the devices.

scholarly journals Evaluation of 5G Key Technique: Non-Orthogonal Multiple Access

2019 ◽  
Vol 8 (2S8) ◽  
pp. 1314-1316
Keyword(s):  
Power Allocation ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Quality Data ◽  
Data Service ◽  
Front Edge ◽  
Power Domain ◽  
Channel Interference ◽  
Code Domain

Non-orthogonal multiple access has been put forward as a key technique for 5G. It can provide power-domain and code-domain multiplexing and enables to satisfy the data demand. Its capacity and spectral efficiency are investigated-ed and analyzed. In comparison to the conventional orthogonal multiple access, the existing dominant non-orthogonal multiple access can provide a higher quality data service for multiple users when the transmitted signals are empowered by the power allocation technique and the received signals are decoded by the channel interference cancellation scheme. In this study, NOMA is found to be a front-edge technology the 5G communications.

scholarly journals Uplink IoT Networks: Time-Division Priority-Based Non-Orthogonal Multiple Access Approach

2021 ◽  
Author(s):  
Basem M. Elhalawany ◽  
Ahmad A.Aziz El-Banna ◽  
Kaishun Wu ◽  
Wali Ullah Khan
Keyword(s):  
Power Allocation ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Signal To Noise Ratio ◽  
Ergodic Capacity ◽  
Transmission Time ◽  
Limited Power ◽  
Iot Devices ◽  
Time Division

Non-orthogonal multiple access (NOMA) has been investigated to support massive connectivity for Internet-of-things (IoT) networks. However, since most IoT devices suffer from limited power and decoding capabilities, it is not desirable to pair a large number of devices simultaneously, which encourages two-user NOMA grouping. Additionally, most existing techniques have not considered the diversity in the target QoS of IoT devices, which may lead to spectrum inefficiency. Few investigations have partially considered that issue by using an order-based power allocation (OPA) approach, where the power is allocated according to the order to the user's target throughput within a priority-based NOMA (PNOMA) group. However, this does not fully capture the effects of diversity in the values of the users' target throughputs. In this work, we handle both problems by considering a throughput-based power allocation (TPA) approach, that captures the QoS diversity, within a three-users PNOMA group as a compromise between spectral efficiency and complexity. Specifically, we investigate the performance of a time-division PNOMA (TD-PNOMA) scheme, where the transmission time is divided into two-time slots with two-users per PNOMA group. The performance of such TD-PNOMA is compared with a fully PNOMA (F-PNOMA) scheme, where the three users share the whole transmission time, in terms of the ergodic capacity under imperfect successive interference cancellation (SIC). The results reveal the superiority of TPA compared with OPA approach in both schemes, besides that the throughput of both schemes can outperform each other under imperfect SIC based on the transmit signal-to-noise ratio and the deployment scenarios.

scholarly journals Power Allocation for Energy-Harvesting-based Fading Cognitive Multiple Access Channels: with or without Successive Interference Cancellation

2017 ◽  
Vol 63 (1) ◽  
pp. 65-72
Author(s):  
Qun Li ◽  
Ding Xu
Keyword(s):  
Power Allocation ◽  
Interference Cancellation ◽  
Multiple Access ◽  
Base Station ◽  
Successive Interference Cancellation ◽  
Multiple Access Channel ◽  
Power Constraint ◽  
Transmit Power ◽  
Sum Rate ◽  
Power Limit

Abstract This paper considers a fading cognitive multiple access channel (CMAC), where multiple secondary users (SUs), who share the spectrum with a primary user (PU), transmit to a cognitive base station (CBS). A power station is assumed to harvest energy from the nature and then provide power to the SUs. We investigate the power allocation problems for such a CMAC to maximize the SU sum rate under the interference power constraint, the sum transmit power constraint and the peak transmit power constraint of each individual SU. In particular, two scenarios are considered: with successive interference cancellation (SIC) and without SIC. For the first scenario, the optimal power allocation algorithm is derived. For the second scenario, a heuristic algorithm is proposed. We show that the proposed algorithm with SIC outperforms the algorithm without SIC in terms of the SU sum rate, while the algorithm without SIC outperforms the algorithm with SIC in terms of the number of admitted SUs for a high sum transmit power limit and a low peak transmit power limit of each individual SU.

scholarly journals Adaptive Interference Mitigation with User Grouping for Fast Transmission in Cellular Networks

2018 ◽  
Vol 10 (2) ◽  
pp. 702
Author(s):  
Hadhrami Ab. Ghani ◽  
Azlan Abd Aziz ◽  
Azizul Azizan ◽  
Salwani Mohd Daud
Keyword(s):  
Energy Efficiency ◽  
Cellular Networks ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Interference Mitigation ◽  
Minimum Mean Square Error ◽  
Error Rates ◽  
User Grouping ◽  
Mitigation Techniques ◽  
Fast Transmission

Designing uplink systems which group users with adaptive interference mitigation techniques is the objective of this research. Reduction in error rates and improvement in the energy efficiency is expected with this approach in addition to spectral efficiency. This paper reports a study on interference mitigation and transmission designs for groups of users in the uplinks. New formulations for the interference mitigation are produced based on the minimum mean square error and successive interference cancellation approach. By reducing the interference, the energy efficiency can be maintained and improved although the number of users per group increases. The measured error rates of this approach with user grouping achieve gains between 1 to 3 dB against that of the existing approach. With reduced complexity, the proposed scheme should be viable for practical deployment.

Power Allocation Adaptation With Coherence Time for Nonorthogonal Multiple Access on Downlink Transmission

2021 ◽  
Vol 13 (3) ◽  
pp. 53-70
Author(s):  
Jia-Chin Lin ◽  
Chih-Yen Liu
Keyword(s):  
Power Allocation ◽  
Spectral Efficiency ◽  
Multiple Access ◽  
Coherence Time ◽  
Time Varying ◽  
Downlink Transmission ◽  
Successive Interference Cancelation ◽  
Power Domain ◽  
Sum Rate ◽  
Adaptive Power

Nonorthogonal multiple access (NOMA) methods are expected to improve spectral efficiency or increase sum rate in a recent mobile communication network. The performance of the power-domain NOMA highly relies on the effectiveness of successive interference cancelation (SIC) and power allocation techniques. This paper proposes an adaptive power allocation method according to analytical coherence time of time-varying channels to improve the SIC effectiveness. Simulations show that the proposed technique can improve SIC, therefore reducing error probability without reduction of the sum rate.

scholarly journals Adaptive Interference Mitigation with User Grouping for Fast Transmission in Cellular Networks

2018 ◽  
Vol 10 (2) ◽  
pp. 704
Author(s):  
Hadhrami Ab. Ghani ◽  
Azlan Abd Aziz ◽  
Azizul Azizan ◽  
Salwani Mohd Daud
Keyword(s):  
Energy Efficiency ◽  
Cellular Networks ◽  
Spectral Efficiency ◽  
Interference Cancellation ◽  
Interference Mitigation ◽  
Minimum Mean Square Error ◽  
Error Rates ◽  
User Grouping ◽  
Mitigation Techniques ◽  
Fast Transmission

Designing uplink systems which group users with adaptive interference mitigation techniques is the objective of this research. Reduction in error rates and improvement in the energy efficiency is expected with this approach in addition to spectral efficiency. This paper reports a study on interference mitigation and transmission designs for groups of users in the uplinks. New formulations for the interference mitigation are produced based on the minimum mean square error and successive interference cancellation approach. By reducing the interference, the energy efficiency can be maintained and improved although the number of users per group increases. The measured error rates of this approach with user grouping achieve gains between 1 to 3 dB against that of the existing approach. With reduced complexity, the proposed scheme should be viable for practical deployment.

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