Analysis of bandwidth allocation strategies with access restrictions in broadband ISDN

Bandwidth allocation strategies with access restrictions for the integration of wideband (WB) and narrowband (NB) traffic in a broadband integrated services digital network (BISDN) are studied. Access restrictions are placed on both types of traffic to meet the grade of service required for each. The WB traffic is assumed nonqueuable, whereas the NB traffic may be queued. As an improved strategy, an access strategy which allows each type of traffic to use its bandwidth in the access-restricted region with the risk of being preempted by an arriving call for which the overflowed region is reserved is considered. Under this strategy, the preempted NB calls are queued at the head of a waiting room, and preempted WB calls are queued in another finite waiting room. The performance of these strategies is analyzed in terms of access delay for NB traffic and blocking probability for WB traffic by the matrix-geometric solution method. It is shown numerically that these strategies can easily be adapted to varying traffic loads by changing the restriction levels