1. ELEN 602 Lecture 9 Review of last lecture Little’s Formula M/M/1 Queue
Discussion of M/M/1 Results
M/M/c/c Analysis
M/G/1 Results

2. One large server vs. Many small servers  m
separate
systems 
One
consolidated
system m 
versus m  

3. M/M/c/c System a c ! B ( c , a ) = a å j ! N(t) Poisson arrivals1
Limited
number of
trunks
Many
lines
Pb)  2  c
Pb
E[X]=1/
Blocked calls are cleared from the system; no waiting allowed.
Performance parameter: Pb = fraction of arrivals that are blocked
Pb = P[N(t)=c] = B(c,a) where a=
B(c,a) is the Erlang B formula which is valid for any service time distribution c a c ! B ( c , a ) = c j a å j !
j=0

4. 1 2 c-1 c 1 - t 1 - (t 1 - (2t 1 - ((c-1) t1 2
c-1 c
t
2t
c  t