Queueing Model - Notation

Notation

Queuing models can be represented using Kendall's notation:

A/B/S/K/N/D

where:

• A is the interarrival time distribution
• B is the service time distribution
• S is the number of servers
• K is the system capacity
• N is the calling population
• D is the service discipline assumed

Many times the last members are omitted, so the notation becomes A/B/S and it is assumed that K =, N = and D = FIFO.

Some standard notation for distributions (A or B) are:

• M for a Markovian (poisson, exponential) distribution
• Eκ for an Erlang distribution with κ phases
• D for degenerate (or deterministic) distribution (constant)
• G for general distribution (arbitrary)
• PH for a phase-type distribution