A simple queue has the following characteristics;
1) There is a simple service channel
2) There are ‘discrete’ customers e.g. customers in a bank, or aircraft waiting to take off as opposed to storm water waiting to drain away.
3) There is an infinite population of potential customers and an infinite maximum queue.
4) There are no simultaneous arrivals of customers at a queue.
5) The queue discipline is on a first come first served basis i.e. FIFO with no priorities or queue barging. No customer leaves before being served.
6) The queue is in a steady state of operation.
7) The number of arrivals (or demands) in a unit of time follow the poisson distribution
8) Service times follow a negative exponential distribution
9) Traffic intensity is less than 1.