An Adaptive Virtual Path Allocation Policy for Broadband Networks

We propose a new policy for virtual path bandwidth allocation in
broadband networks. Based on a threshold scheme, our policy handles
the inherent tradeoff between bandwidth utilization and processing
costs. In each virtual path controller the thresholds are chosen so
as to keep bandwidth utilization high, while obtaining a low rate of
processing requests. Two novel ideas are used in our threshold
scheme: {\em adaptivity}, which results in a better prediction of
future bandwidth requirements; and {\em hysteresis}, which prevents
excessive processing of requests due to oscillations around
thresholds. We tested the performance of our new bandwidth control
scheme, and compared it with previously suggested schemes. The
performance measures were the expected amount of unused bandwidth, the
average signaling load and the blocking probability.
Our analysis is based on a {\em time segmentation}
technique, which allows us to reduce a Markov chain with $NM$ states
into $M$ Markov chains with $N$ states and a one-dimensional chain
with $M$ states. Our results show that our policy significantly
improves upon previously suggested approaches.