Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation
Non-Orthogonal Multiple Access (NOMA) has emerged as a promising strategy for increasing spectral efficiency in wireless multiuser communications. The performance of NOMA highly depends on the users’ channel conditions, being enhanced when these are significantly different, i.e., one stro...
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| Format: | Article |
| Language: | English |
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IEEE
2023-01-01
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| Series: | IEEE Access |
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| Online Access: | https://ieeexplore.ieee.org/document/10177152/ |
| _version_ | 1797776964196499456 |
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| author | Alvaro Pendas-Recondo Rafael Gonzalez Ayestaran Jesus Alberto Lopez-Fernandez |
| author_facet | Alvaro Pendas-Recondo Rafael Gonzalez Ayestaran Jesus Alberto Lopez-Fernandez |
| author_sort | Alvaro Pendas-Recondo |
| collection | DOAJ |
| description | Non-Orthogonal Multiple Access (NOMA) has emerged as a promising strategy for increasing spectral efficiency in wireless multiuser communications. The performance of NOMA highly depends on the users’ channel conditions, being enhanced when these are significantly different, i.e., one strong user and one weak user. On the contrary, rate fairness is compromised when users present similar channel conditions since the maximization of the sum capacity may result in the allocation of most resources to one user. In general, this problem can be avoided with correct user grouping. However, there are scenarios, e.g., picocells or femtocells, where finding users with distinctive channel conditions is not always possible. In this paper, we study the application of beamforming in a two-user Multiple-Input-Single-Output (MISO) downlink NOMA system to achieve rate fairness through channel shaping even when the conditions of both users are similar. The proposed formulation includes the effect of Near-Field (NF) radiation, which yields an accurate modeling of the problem at hand in a small-cell scenario. We use an optimization algorithm to jointly calculate both the power allocation and the complex weights to be applied to the elements of a given array. Numerical simulations across scenarios with distinctive or similar channel conditions show that the proposed approach outperforms alternative NOMA methods in ensuring rate fairness. Additionally, it yields improved overall rates compared to Far-Field (FF) formulation-based modelling and beamforming Time Division Multiple Access (TDMA) solutions. |
| first_indexed | 2024-03-12T22:57:21Z |
| format | Article |
| id | doaj.art-e925efd0a503465aa939057e95befc9d |
| institution | Directory Open Access Journal |
| issn | 2169-3536 |
| language | English |
| last_indexed | 2024-03-12T22:57:21Z |
| publishDate | 2023-01-01 |
| publisher | IEEE |
| record_format | Article |
| series | IEEE Access |
| spelling | doaj.art-e925efd0a503465aa939057e95befc9d2023-07-19T23:00:48ZengIEEEIEEE Access2169-35362023-01-0111712507125910.1109/ACCESS.2023.329348910177152Beamforming for NOMA Under Similar Channel Conditions Including Near-Field FormulationAlvaro Pendas-Recondo0https://orcid.org/0000-0002-8029-8024Rafael Gonzalez Ayestaran1https://orcid.org/0000-0002-9775-9448Jesus Alberto Lopez-Fernandez2https://orcid.org/0000-0001-7603-9591Department of Electrical Engineering, Group of Signal Theory and Communications, University of Oviedo, Gijón, SpainDepartment of Electrical Engineering, Group of Signal Theory and Communications, University of Oviedo, Gijón, SpainDepartment of Electrical Engineering, Group of Signal Theory and Communications, University of Oviedo, Gijón, SpainNon-Orthogonal Multiple Access (NOMA) has emerged as a promising strategy for increasing spectral efficiency in wireless multiuser communications. The performance of NOMA highly depends on the users’ channel conditions, being enhanced when these are significantly different, i.e., one strong user and one weak user. On the contrary, rate fairness is compromised when users present similar channel conditions since the maximization of the sum capacity may result in the allocation of most resources to one user. In general, this problem can be avoided with correct user grouping. However, there are scenarios, e.g., picocells or femtocells, where finding users with distinctive channel conditions is not always possible. In this paper, we study the application of beamforming in a two-user Multiple-Input-Single-Output (MISO) downlink NOMA system to achieve rate fairness through channel shaping even when the conditions of both users are similar. The proposed formulation includes the effect of Near-Field (NF) radiation, which yields an accurate modeling of the problem at hand in a small-cell scenario. We use an optimization algorithm to jointly calculate both the power allocation and the complex weights to be applied to the elements of a given array. Numerical simulations across scenarios with distinctive or similar channel conditions show that the proposed approach outperforms alternative NOMA methods in ensuring rate fairness. Additionally, it yields improved overall rates compared to Far-Field (FF) formulation-based modelling and beamforming Time Division Multiple Access (TDMA) solutions.https://ieeexplore.ieee.org/document/10177152/Beamformingmultiple-input-single-output (MISO)near-field (NF)non-orthogonal multiple access (NOMA)power allocationrate fairness |
| spellingShingle | Alvaro Pendas-Recondo Rafael Gonzalez Ayestaran Jesus Alberto Lopez-Fernandez Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation IEEE Access Beamforming multiple-input-single-output (MISO) near-field (NF) non-orthogonal multiple access (NOMA) power allocation rate fairness |
| title | Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation |
| title_full | Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation |
| title_fullStr | Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation |
| title_full_unstemmed | Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation |
| title_short | Beamforming for NOMA Under Similar Channel Conditions Including Near-Field Formulation |
| title_sort | beamforming for noma under similar channel conditions including near field formulation |
| topic | Beamforming multiple-input-single-output (MISO) near-field (NF) non-orthogonal multiple access (NOMA) power allocation rate fairness |
| url | https://ieeexplore.ieee.org/document/10177152/ |
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