A Novel Spectrally-Efficient Uplink Hybrid-Domain NOMA System

Chen Quan, Animesh Yadav, Baocheng Geng, Pramod K. Varshney, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


This letter proposes a novel hybrid-domain (HD) non-orthogonal multiple access (NOMA) approach to support a larger number of uplink users than the recently proposed code-domain NOMA approach, i.e., sparse code multiple access (SCMA). HD-NOMA combines the code-domain and power-domain NOMA schemes by clustering the users in small path loss (strong) and large path loss (weak) groups. The two groups are decoded using successive interference cancellation while within the group users are decoded using the message passing algorithm. To further improve the performance of the system, a spectral-efficiency maximization problem is formulated under a user quality-of-service constraint, which dynamically assigns power and subcarriers to the users. The problem is non-convex and has sparsity constraints. The alternating optimization procedure is used to solve it iteratively. We apply successive convex approximation and reweighted \ell _1 minimization approaches to deal with the non-convexity and sparsity constraints, respectively. The performance of the proposed HD-NOMA is evaluated and compared with the conventional SCMA scheme through numerical simulation. The results show the potential of HD-NOMA in increasing the number of uplink users that can be supported in a given time-frequency resource.

Original languageEnglish (US)
Article number9145680
Pages (from-to)2609-2613
Number of pages5
JournalIEEE Communications Letters
Issue number11
StatePublished - Nov 2020
Externally publishedYes


  • Sparse code multiple access
  • non-orthogonal multiple access
  • wireless communications

ASJC Scopus subject areas

  • Modeling and Simulation
  • Computer Science Applications
  • Electrical and Electronic Engineering


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