Distributed User Clustering and Resource Allocation for Imperfect NOMA in Heterogeneous Networks

Abdulkadir Celik, Ming-Cheng Tsai, Redha M. Radaydeh, Fawaz S. Al-Qahtani, Mohamed-Slim Alouini

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64 Scopus citations


In this paper, we propose a distributed cluster formation (CF) and resource allocation (RA) framework for non-ideal non-orthogonal multiple access (NOMA) schemes in heterogeneous networks. The imperfection of the underlying NOMA scheme is due to the receiver sensitivity and interference residue from non-ideal successive interference cancellation (SIC), which is generally characterized by a fractional error factor (FEF). Our analytical findings first show that several factors have a significant impact on the achievable NOMA gain. Then, we investigate fundamental limits on NOMA cluster size as a function of FEF levels, cluster bandwidth, and quality of service (QoS) demands of user equipments (UEs). Thereafter, a clustering algorithm is developed by taking feasible cluster size and channel gain disparity of UEs into account. Finally, we develop a distributed α-fair RA framework where α governs the trade-off between maximum throughput and proportional fairness objectives. Based on the derived closed-form optimal power levels, the proposed distributed solution iteratively updates bandwidths, clusters, and UEs’ transmission powers. Numerical results demonstrate that proposed solutions deliver a higher spectral and energy efficiency than traditionally adopted basic NOMA cluster size of two. We also show that an imperfect NOMA cannot always provide better performance than orthogonal multiple access under certain conditions. Finally, our numerical investigations reveal that NOMA gain is maximized under downlink/uplink decoupled (DUDe) UE association.
Original languageEnglish (US)
Pages (from-to)7211-7227
Number of pages17
JournalIEEE Transactions on Communications
Issue number10
StatePublished - Jul 9 2019

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by NPRP from the Qatar National Research Fund under grant no. 8-1545-2-657. A part of this paper has been presented at IEEE GLOBECOM 2018, Singapore [1].


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