How URLLC can Benefit from NOMA-based Retransmissions

Radoslaw Kotaba*, Carles Navarro Manchon, Tommaso Balercia, Petar Popovski

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

16 Citations (Scopus)


Among the new types of connectivity unleashed by the emerging 5G wireless systems, Ultra-Reliable Low Latency Communication (URLLC) is perhaps the most innovative, yet challenging one. Ultra-reliability requires high levels of diversity, however, the reactive approach based on packet retransmission in HARQ protocols should be applied carefully to conform to the stringent latency constraints. The main premise of this paper is that the NOMA principle can be used to achieve highly efficient retransmissions by allowing concurrent use of wireless resources in the uplink. We introduce a comprehensive solution that accommodates multiple intermittently active users, each with its own HARQ process. The performance is investigated under two different assumptions about the Channel State Information (CSI) availability: statistical and instantaneous. The results show that NOMA can indeed lead to highly efficient system operation compared to the case in which all HARQ processes are run orthogonally.
Original languageEnglish
Article number9254087
JournalI E E E Transactions on Wireless Communications
Issue number3
Pages (from-to)1684-1699
Number of pages16
Publication statusPublished - Mar 2021


  • HARQ
  • NOMA
  • Reliability
  • Resource management
  • Time-frequency analysis
  • Ultra reliable low latency communication
  • Uplink
  • Wireless communication
  • radio resource management
  • uplink


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