Hybrid NOMA/OMA Broadcasting-and-Buffer-State-Based Relay Selection

Jun Kochi, Ryota Nakai, Shinya Sugiura

Research output: Contribution to journalArticlepeer-review


In this paper, we propose a novel buffer-aided relay selection scheme that is capable of amalgamating the concepts of non-orthogonal multiple access (NOMA) and orthogonal multiple access (OMA) in the context of two-hop cooperative networks supporting multiple relays. This is enabled by allowing relay nodes to share a common information packet in their buffers with the aid of a source-to-relay broadcasting mode. Hence, the proposed relay selection scheme switches between diverse modes of uplink NOMA, downlink NOMA, unicast, source broadcasting, and cooperative beamforming. The theoretical bounds of the outage probability, throughput, average delay, and diversity order are derived for the proposed scheme, based on a Markov chain model. Through our analytical and numerical results, it is demonstrated that the proposed scheme is capable of switching to one of the best modes in an adaptive manner while outperforming the conventional buffer-aided cooperative schemes.

Original languageEnglish
Article number9337192
Pages (from-to)1618-1631
Number of pages14
JournalIEEE Transactions on Vehicular Technology
Issue number2
Publication statusPublished - 2021 Feb
Externally publishedYes


  • Adaptive transmission
  • NOMA
  • broadcast
  • buffer
  • cooperative network
  • delay
  • markov chain
  • outage probability
  • relay selection
  • theoretical analysis

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Electrical and Electronic Engineering
  • Applied Mathematics

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