Dynamic look-ahead time with conditional call admission based on predicted lifetime

Book-ahead (BA) reservation, which allows advance reservation of network bandwidth, is an effective technique to provide enhanced functionality for multimedia and distributed applications in, a QoS-enabled network. Introduction of BA reservation disrupts service continuity of on-going instantaneous request (IR) calls when resource scarcity arises. A number of call admission control (CAC) models have been proposed in literature to address the problem of interrupted service continuity. This work presents a comparative study of recently proposed models. Simulation results show that among the proposed models dynamic look-ahead time (DLAT) based CAC model (I. Ahmad, et al., 2004) yields the best performance in terms of low preemption probability and high resource utilization for low to moderate BA limit. We also present a modified DLAT model with conditional admission of IR calls that achieves better performance even at high BA limit