We consider the first passage to overload for a buffered statistical multiplexer loaded with N identical binary on-off sources. First passage times to overload are related to the characterization of congestion imminence which in turn is crucial in the design of effective congestion control algorithms for delay sensitive services in broadband wide area networks. We give the moments of the first passage time to overload as solutions of a set of linear first order ordinary differential equations. Furthermore, adapting the methodology developed by Anick, Mitra and Sondhi (1982) we express the moments of the first passage time to overload in a spectral expansion form, involving the system's eigenvalues. Numerical results for the first two moments are presented.

The authors present a multimedia medical communications system based on packet local area networks. This system is intended to facilitate the communications between radiologists and physicians within a hospital. Radiographs are taken, digitized, and then stored in the database. Radiologists retrieve radiographic images from the database for diagnosis, and make diagnostic reports to be stored in the database. Physicians can then consult these radiographic images and diagnostic reports. A real-time conference can be set up between a radiologist and a physician who are in different locations, for discussing a particular case or radiographic images can be retrieved from the database for diagnosis and conferencing. Simulations indicate the delay for displaying an image of 1 Mb from the local storage (hard disk) at a workstation is approximately 6.5 s.>