Excerpt from An Unified Method to Analyze Overtake Free Queueing Systems
Let us then ask the key question which motivated the present paper. What are the laws of queueing theory? The fundamental quantities in queueing theory are the stationary queue and system length (q, L) and the waiting and system time (w, 5) under the First in-first-out (fifo) discipline. Of course there are several other random variables of interest (often particular to the application studied), but these are the most widely used. The goal of queueing theory is then to find the distributions of Q, L, W, S in various applications. In its almost a hundred year history queueing theory has addressed a great variety of problems using a variety of techniques, which solve some problems but fail on others. What is interesting is the lack of a unified way to solve a particular application.