Processor-sharing queues are useful in the study of computer and communication systems. Early work on processor-sharing queues was motivated by the study of multiuser mainframe computer systems, e.g., see Kleinrock [1967], Coffman and Kleinrock [1968] and Coffman, Muntz and Trotter [1970]. Recent interest in processor sharing queues is due to their applications to communication networks and web servers, for example, modeling congested links with TCP traffic and job schedulers in web servers. The study of processor-sharing queues has been well documented by,for example, books of Kleinrock [1976], Cohen [1982] and Asmussen [2003] and survey papers of Cohen [1979], Yashkov [1987,1992] and Yashkov and Yashkova [2007].
****** Processor-sharing queues written by Q.L. Li have two points: (1) RG-factorizations, (2) supplementary variable method.