Critically loaded k-limited polling systems with switch-over times.

We consider a two-queue polling model with switch-over times and k-limited service (serve at most ki customers during one visit period to queue i) in each queue. The major benefit of the k-limited service discipline is that it - besides bounding the cycle time - effectuates prioritization by assigning different service limits to different queues. System performance is studied in the heavy-traffic regime, in which one of the queues becomes critically loaded with the other queue remaining stable. By using a singular-perturbation technique, we rigorously prove heavy-traffic limits for the joint queue-length distribution. Moreover, it is observed that an interchange exists among the first two moments in service and switch-over times such that the HT limits remain unchanged.