Impact of NOMA on Age of Information: A Grant-Free Transmission Perspective

Zhiguo Ding, Robert Schober, H. Vincent Poor

Research output: Contribution to journalArticlepeer-review


The aim of this paper is to characterize the impact of non-orthogonal multiple access (NOMA) on the age of information (AoI) of grant-free transmission. In particular, a low-complexity form of NOMA, termed NOMA-assisted random access, is applied to grant-free transmission in order to illustrate the two benefits of NOMA for AoI reduction, namely increasing channel access and reducing user collisions. Closed-form analytical expressions for the time average AoI achieved by NOMA assisted grant-free transmission are obtained, and asymptotic studies are carried out to demonstrate that the use of the simplest form of NOMA is already sufficient to reduce the AoI of orthogonal multiple access (OMA) by more than 40%. In addition, the developed analytical expressions are also shown to be useful for optimizing the users’ transmission attempt probabilities, which are key parameters for grant-free transmission.

Original languageEnglish (US)
Pages (from-to)1
Number of pages1
JournalIEEE Transactions on Wireless Communications
StateAccepted/In press - 2023

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


  • Base stations
  • Complexity theory
  • Internet of Things
  • Markov processes
  • NOMA
  • Non-orthogonal multiple access (NOMA)
  • Signal to noise ratio
  • Wireless communication
  • age of information (AoI)
  • grant-free transmission


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