m/m/1 queuing system -凯发k8网页登录
overview
this example shows how to model a single-queue single-server system with a single traffic source and an infinite storage capacity. in the notation, the m stands for markovian; m/m/1 means that the system has a poisson arrival process, an exponential service time distribution, and one server. queuing theory provides exact theoretical results for some performance measures of an m/m/1 queuing system and this model makes it easy to compare empirical results with the corresponding theoretical results.
structure
the model includes the components listed below:
entity generator block: models a poisson arrival process by generating entities (also known as "customers" in queuing theory).
simulink function exponentialarrivaltime(): returns data representing the interarrival times for the generated entities. the interarrival time of a poisson arrival process is an exponential random variable.
entity queue block: stores entities that have yet to be served in fifo order
entity server block: models a server whose service time has an exponential distribution.
results and displays
the model includes these visual ways to understand its performance:
scopes labeled "waiting time: theoretical" and "waiting time: simulation" showing the theoretical and empirical values of the waiting time in the queue, on a single set of axes. you can use this plot to see how the empirical values evolve during the simulation and compare them with the theoretical value.
a scope labeled "server utilization" showing the utilization of the single server over the course of the simulation.
theoretical results
queuing theory provides the following theoretical results for an m/m/1 queue with an arrival rate of and a service rate of :
mean waiting time in the queue =
the first term is the mean total waiting time in the combined queue-server system and the second term is the mean service time.
utilization of the server =
experimenting with the model
move the arrival rate knob during the simulation and observe the change in the simulation results
related examples
references
[1] kleinrock, leonard, queueing systems, volume i: theory, new york, wiley, 1975.
see also
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