M/M/S Queue, probability interpretation











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0
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In an M/M/s queue, what does this expression mean? :



$sum_{n=0}^{s-1}{(s-n)P_n}$



Furthermore, is it possible that the following equation holds? :



$sum_{n=0}^{s-1}{(s-n)P_n} = (1-rho)s$



If so, how could I demonstrate it?



EDIT: An M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers.



Thanks,

Louis










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  • What is an M/M/S queue? What are the variables that you're using?
    – Tki Deneb
    Nov 29 at 17:56










  • @TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
    – Louis-Philippe Noël
    Nov 29 at 21:08










  • I'm afraid I can't help you then, I'm not familiar with this subject.
    – Tki Deneb
    Nov 29 at 22:23















up vote
0
down vote

favorite












In an M/M/s queue, what does this expression mean? :



$sum_{n=0}^{s-1}{(s-n)P_n}$



Furthermore, is it possible that the following equation holds? :



$sum_{n=0}^{s-1}{(s-n)P_n} = (1-rho)s$



If so, how could I demonstrate it?



EDIT: An M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers.



Thanks,

Louis










share|cite|improve this question
























  • What is an M/M/S queue? What are the variables that you're using?
    – Tki Deneb
    Nov 29 at 17:56










  • @TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
    – Louis-Philippe Noël
    Nov 29 at 21:08










  • I'm afraid I can't help you then, I'm not familiar with this subject.
    – Tki Deneb
    Nov 29 at 22:23













up vote
0
down vote

favorite









up vote
0
down vote

favorite











In an M/M/s queue, what does this expression mean? :



$sum_{n=0}^{s-1}{(s-n)P_n}$



Furthermore, is it possible that the following equation holds? :



$sum_{n=0}^{s-1}{(s-n)P_n} = (1-rho)s$



If so, how could I demonstrate it?



EDIT: An M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers.



Thanks,

Louis










share|cite|improve this question















In an M/M/s queue, what does this expression mean? :



$sum_{n=0}^{s-1}{(s-n)P_n}$



Furthermore, is it possible that the following equation holds? :



$sum_{n=0}^{s-1}{(s-n)P_n} = (1-rho)s$



If so, how could I demonstrate it?



EDIT: An M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers.



Thanks,

Louis







probability queueing-theory






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share|cite|improve this question













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edited Nov 29 at 22:55

























asked Nov 28 at 19:25









Louis-Philippe Noël

123




123












  • What is an M/M/S queue? What are the variables that you're using?
    – Tki Deneb
    Nov 29 at 17:56










  • @TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
    – Louis-Philippe Noël
    Nov 29 at 21:08










  • I'm afraid I can't help you then, I'm not familiar with this subject.
    – Tki Deneb
    Nov 29 at 22:23


















  • What is an M/M/S queue? What are the variables that you're using?
    – Tki Deneb
    Nov 29 at 17:56










  • @TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
    – Louis-Philippe Noël
    Nov 29 at 21:08










  • I'm afraid I can't help you then, I'm not familiar with this subject.
    – Tki Deneb
    Nov 29 at 22:23
















What is an M/M/S queue? What are the variables that you're using?
– Tki Deneb
Nov 29 at 17:56




What is an M/M/S queue? What are the variables that you're using?
– Tki Deneb
Nov 29 at 17:56












@TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
– Louis-Philippe Noël
Nov 29 at 21:08




@TkiDeneb an M/M/S queue is a queue with Markovian (Poisson law) process for arrivals, Markovian (Exponential law) process for departures and $s$ servers. Thanks for your time!
– Louis-Philippe Noël
Nov 29 at 21:08












I'm afraid I can't help you then, I'm not familiar with this subject.
– Tki Deneb
Nov 29 at 22:23




I'm afraid I can't help you then, I'm not familiar with this subject.
– Tki Deneb
Nov 29 at 22:23










1 Answer
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If $p_n$ is the stationary distribution then the first expression is the expected number of free servers.



The equation is indeed correct and this can be argued using Little’s law: the arrival rate to each server is $frac{lambda}{s}$ and the expected time in service is $frac{1}{mu}$, so the probability each server is free is $1-frac{lambda}{smu}$. The servers are identical so the the sum is just $s$ times the probability of a free server.






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    1 Answer
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    active

    oldest

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes








    up vote
    0
    down vote



    accepted










    If $p_n$ is the stationary distribution then the first expression is the expected number of free servers.



    The equation is indeed correct and this can be argued using Little’s law: the arrival rate to each server is $frac{lambda}{s}$ and the expected time in service is $frac{1}{mu}$, so the probability each server is free is $1-frac{lambda}{smu}$. The servers are identical so the the sum is just $s$ times the probability of a free server.






    share|cite|improve this answer

























      up vote
      0
      down vote



      accepted










      If $p_n$ is the stationary distribution then the first expression is the expected number of free servers.



      The equation is indeed correct and this can be argued using Little’s law: the arrival rate to each server is $frac{lambda}{s}$ and the expected time in service is $frac{1}{mu}$, so the probability each server is free is $1-frac{lambda}{smu}$. The servers are identical so the the sum is just $s$ times the probability of a free server.






      share|cite|improve this answer























        up vote
        0
        down vote



        accepted







        up vote
        0
        down vote



        accepted






        If $p_n$ is the stationary distribution then the first expression is the expected number of free servers.



        The equation is indeed correct and this can be argued using Little’s law: the arrival rate to each server is $frac{lambda}{s}$ and the expected time in service is $frac{1}{mu}$, so the probability each server is free is $1-frac{lambda}{smu}$. The servers are identical so the the sum is just $s$ times the probability of a free server.






        share|cite|improve this answer












        If $p_n$ is the stationary distribution then the first expression is the expected number of free servers.



        The equation is indeed correct and this can be argued using Little’s law: the arrival rate to each server is $frac{lambda}{s}$ and the expected time in service is $frac{1}{mu}$, so the probability each server is free is $1-frac{lambda}{smu}$. The servers are identical so the the sum is just $s$ times the probability of a free server.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 2 at 21:15









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