This queue is a variation of a multiserver system and only
maximum customers are allowed to stay in the system. As
earlier the number of customers in the system is a birth-deat process
with appropriate rates and for the steady-state distribution we
have
From the normalizing condition for we have
To simplify this expression let .
Then
Thus
The main performance measures can be obtained as follows
1. Mean queue length
which results
In particular, if then the L'Hopital's rule should be applied
twice.
2. Mean number of customers in the system
It is easy to see that
and since
we get
.
3. Mean response and waiting times
The mean times can be obtained by applying the Little's law, that is
In the case of an system these formulas are simplified to
3. Distribution at the arrival instants
By applying the Bayes's rule we have
Obviously in the case of an system
since
tends to
.
4. Distribution of the waiting time
As in the previous parts for the theorem of total probability is applied
resulting
Since
applying substitutions ,
we have
thus
The Laplace-transform of the waiting and response times can be derived similarly, by using the law of total Laplace-transforms.
Java applets for direct calculations can be found at |