A book-ahead routing scheme to reduce instantaneous request call blocking and preemption rate

Book-Ahead (BA) reservation which allows booking of network bandwidth long before its actual usage time is a key reservation technique in a QoS-enabled network. BA reservation is highly attractive for high bandwidth requiring time sensitive multimedia and distributed applications. Routing of book-ahead (BA) and instantaneous request (IR) reservations has been an important area of research of late. Among all other routing techniques, shortest path routing has been the strongest candidate for BA and IR routing for its resource conservative nature. Imprecise link state information contributes to high call blocking which is a major obstacle for widespread implementation of linkstate QoS routing. In this paper, we propose an improved BA routing scheme by formulating a link cost function that comprises of hop count and a measure to asses the impact of inaccurate state information on call connection at each link. The motivation of this work is to achieve higher network performance by improving existing BA routing in a way that reduces the detrimental effect of imprecise state information on IR call blocking and preemption rate. The proposed BA routing is not an alternative, but a complementary approach to any of the IR routing algorithms formulated with specific interest to address the problem of imprecise routing information on IR call connection. Simulation results show improved network performances in the form of lower IR call blocking rate, lower preemption rate and higher utilization when the proposed routing technique is adopted in a communication network.