Monotonicity and stability of periodic polling models

Polling Systems;Stability;operations research

Monotonicity and stability of periodic polling models

Projet MEVALThis paper deals with the stability of periodic polling models with mixed service policies. The interarrivals to all queues are independent and exponentially distributed and the service and the switch-over times are independent with general distributions. The necessary and sufficient condition for the stability of such polling systems is established. The proof is based on the stochastic monotonicity of the state process at the polling instants. The stability of only a subset of the queues is also analyzed, and, in case of heavy traffic, the order of explosion of the queues is given

Optimization of polling systems with Bernoulli schedules

Optimization;Polling Systems;Queueing Theory;operations research

A transient analysis of polling systems operating under exponential time-limited service disciplines

In the present article, we analyze a class of time-limited polling systems. In particular, we will derive a direct relation for the evolution of the joint queue-length during the course of a server visit. This will be done both for the pure and the exhaustive exponential time-limited discipline for general service time requirements and preemptive service. More specifically, service of individual customers is according to the preemptive-repeat-random strategy, i.e., if a service is interrupted, then at the next server visit a new service time will be drawn from the original service-time distribution. Moreover, we incorporate customer routing in our analysis, such that it may be applied to a large variety of queueing networks with a single server operating under one of the before-mentioned time-limited service disciplines. We study the time-limited disciplines by performing a transient analysis for the queue length at the served queue. The analysis of the pure time-limited discipline builds on several known results for the transient analysis of the M/G/1 queue. Besides, for the analysis of the exhaustive discipline, we will derive several new results for the transient analysis of an M/G/1 during a busy period. The final expressions (both for the exhaustive and pure case) that we obtain for the key relations generalize previous results by incorporating customer routing or by relaxing the exponentiality assumption on the service times. Finally, based on the interpretation of these key relations, we formulate a conjecture for the key relation for any branching-type service discipline operating under an exponential time-limit

Stability of two exponential time-limited polling models

In this article, we consider the stability of two single-server polling models. More specifically, we will state and prove the stability conditions of single-server polling systems operating under the pure and exhaustive exponential time-limited service discipline. These conditions will be proven for the polling system operating under the periodic polling strategy and preemptive service. The stability proof of the pure time-limited discipline is straightforward as stability may be considered for each queue in isolation. The proof for the exhaustive time-limited discipline is more laborious. We follow the line of proof as introduced by Fricker and Ja\"{i}bi for a large class of service disciplines. Unfortunately, the preemptive nature of the exhaustive time-limited discipline excludes it from this class and as a result substantial efforts are required to modify the proof as to allow for preemptive disciplines. Finally, the extension of the proofs to the Markovian polling strategy is discussed

Upstream traffic capacity of a WDM EPON under online GATE-driven scheduling

Passive optical networks are increasingly used for access to the Internet and it is important to understand the performance of future long-reach, multi-channel variants. In this paper we discuss requirements on the dynamic bandwidth allocation (DBA) algorithm used to manage the upstream resource in a WDM EPON and propose a simple novel DBA algorithm that is considerably more efficient than classical approaches. We demonstrate that the algorithm emulates a multi-server polling system and derive capacity formulas that are valid for general traffic processes. We evaluate delay performance by simulation demonstrating the superiority of the proposed scheduler. The proposed scheduler offers considerable flexibility and is particularly efficient in long-reach access networks where propagation times are high