A communication multiplexer problem: Two alternating queues with dependent randomly-timed gated regime

Iddo Eliazar*, Gadi Fibich, Uri Yechiali

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Two random traffic streams are competing for the service time of a single server (multiplexer). The streams form two queues, primary (queue 1) and secondary (queue 0). The primary queue is served exhaustively, after which the server switches over to queue 0. The duration of time the server resides in the secondary queue is determined by the dynamic evolution in queue 1. If there is an arrival to queue 1 while the server is still working in queue 0, the latter is immediately gated, and the server completes service there only to the gated jobs, upon which it switches back to the primary queue. We formulate this system as a two-queue polling model with a single alternating server and with randomly-timed gated (RTG) service discipline in queue 0, where the timer there depends on the arrival stream to the primary queue. We derive Laplace-Stieltjes transforms and generating functions for various key variables and calculate numerous performance measures such as mean queue sizes at polling instants and at an arbitrary moment, mean busy period duration and mean cycle time length, expected number of messages transmitted during a busy period and mean waiting times. Finally, we present graphs of numerical results comparing the mean waiting times in the two queues as functions of the relative loads, showing the effect of the RTG regime.

Original languageEnglish
Pages (from-to)325-353
Number of pages29
JournalQueueing Systems
Issue number4
StatePublished - 2002


  • Alternating service
  • Busy period
  • Multiplexer
  • Polling
  • Queue length
  • Randomly-timed gated regime
  • Timers
  • Two queues
  • Waiting times


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