The age of information: Real-time status updating by multiple sources

Roy D. Yates, Sanjit K. Kaul

Research output: Contribution to journalArticlepeer-review

276 Scopus citations


We examine multiple independent sources providing status updates to a monitor through simple queues. We formulate an age of information (AoI) timeliness metric and derive a general result for the AoI that is applicable to a wide variety of multiple source service systems. For first-come first-served and two types of last-come first-served systems with Poisson arrivals and exponential service times, we find the region of feasible average status ages for multiple updating sources. We then use these results to characterize how a service facility can be shared among multiple updating sources. A new simplified technique for evaluating the AoI in finite-state continuous-time queuing systems is also derived. Based on stochastic hybrid systems, this method makes AoI evaluation to be comparable in complexity to finding the stationary distribution of a finite-state Markov chain.

Original languageEnglish (US)
Article number8469047
Pages (from-to)1807-1827
Number of pages21
JournalIEEE Transactions on Information Theory
Issue number3
StatePublished - Mar 2019

All Science Journal Classification (ASJC) codes

  • Information Systems
  • Computer Science Applications
  • Library and Information Sciences


  • Age of information
  • communication networks
  • queueing systems
  • stochastic hybrid systems


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