Overload control of the isochronous traffic in QPSX

QPSX (queued packet and synchronous circuit exchange) is a distributed communications switch that provides integrated packet-data and circuit switching. The isochronous slots are allocated to circuit switching and are therefore not available for packet switching. The statistical characteristics of the packet-switching capacity are derived by analyzing the steady-state distribution of the number of isochronous slots. The latter is derived for the case in which first-fit circuit allocation policy is implemented with an optimal circuit overload control, by taking into consideration the waste created by this policy. Numerical results demonstrate the improvement that can be obtained in the packet capacity utilizing blocking policy