4,386 research outputs found

    Stationary remaining service time conditional on queue length

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    In Mandelbaum and Yechiali (1979) a simple formula is derived for the expected station-ary remaining service time in a FIFO M/G/1 queue, conditional on the number of customers in the system being equal to j, j ≥ 1. Fakinos (1982) derived a similar formula using an alternative method. Here we give a short proof of the formula using rate conservation law (RCL), and generalize to handle higher moments which better illustrates the advantages of using RCL

    Stationary analysis of a single queue with remaining service time dependent arrivals

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    We study a generalization of the M/G/1M/G/1 system (denoted by rM/G/1rM/G/1) with independent and identically distributed (iid) service times and with an arrival process whose arrival rate λ0f(r)\lambda_0f(r) depends on the remaining service time rr of the current customer being served. We derive a natural stability condition and provide a stationary analysis under it both at service completion times (of the queue length process) and in continuous time (of the queue length and the residual service time). In particular, we show that the stationary measure of queue length at service completion times is equal to that of a corresponding M/G/1M/G/1 system. For f>0f > 0 we show that the continuous time stationary measure of the rM/G/1rM/G/1 system is linked to the M/G/1M/G/1 system via a time change. As opposed to the M/G/1M/G/1 queue, the stationary measure of queue length of the rM/G/1rM/G/1 system at service completions differs from its marginal distribution under the continuous time stationary measure. Thus, in general, arrivals of the rM/G/1rM/G/1 system do not see time averages. We derive formulas for the average queue length, probability of an empty system and average waiting time under the continuous time stationary measure. We provide examples showing the effect of changing the reshaping function on the average waiting time.Comment: 31 pages, 3 Figure

    Stationary distributions of the multi-type ASEP

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    We give a recursive construction of the stationary distribution of multi-type asymmetric simple exclusion processes on a finite ring or on the infinite line ZZ. The construction can be interpreted in terms of "multi-line diagrams" or systems of queues in tandem. Let qq be the asymmetry parameter of the system. The queueing construction generalises the one previously known for the totally asymmetric (q=0q=0) case, by introducing queues in which each potential service is unused with probability qkq^k when the queue-length is kk. The analysis is based on the matrix product representation of Prolhac, Evans and Mallick. Consequences of the construction include: a simple method for sampling exactly from the stationary distribution for the system on a ring; results on common denominators of the stationary probabilities, expressed as rational functions of qq with non-negative integer coefficients; and probabilistic descriptions of "convoy formation" phenomena in large systems.Comment: 54 pages, 4 figure

    The Mx/G/1 queue with queue length dependent service times

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    We deal with the MX/G/1 queue where service times depend on the queue length at the service initiation. By using Markov renewal theory, we derive the queue length distribution at departure epochs. We also obtain the transient queue length distribution at time t and its limiting distribution and the virtual waiting time distribution. The numerical results for transient mean queue length and queue length distributions are given.Bong Dae Choi, Yeong Cheol Kim, Yang Woo Shin, and Charles E. M. Pearc
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