Đang chuẩn bị liên kết để tải về tài liệu:
Báo cáo hóa học: " Research Article Models for Call Acceptance Based on Handoff Guarantees"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Models for Call Acceptance Based on Handoff Guarantees | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 194828 12 pages doi 10.1155 2008 194828 Research Article Models for Call Acceptance Based on Handoff Guarantees Mostafizur Rahman and Attahiru Sule Alfa Department of Electrical and Computer Engineering University of Manitoba Winnipeg MB Canada R3T 5V6 Correspondence should be addressed to Mostafizur Rahman mmrahman@ee.umanitoba.ca Received 1 November 2007 Accepted 6 August 2008 Recommended by Weihua Zhuang Call admission control CAC is important for cellular wireless networks to provide quality-of-service QoS requirements to users. Static and adaptive CAC schemes respectively make unrealistic assumptions about the distributions of the handoff call arrival process and the number of users in a cell. Handoff arrivals are usually assumed to follow Poisson process in static CAC schemes for Poisson new call arrivals and exponentially distributed call holding and cell residence times. We use a simple proof to show that this assumption of Poisson handoff arrival process is not justified for a two-cell wireless network. In general we find that the handoff process can be captured by a two-dimensional Markov chain. We propose a novel adaptive CAC scheme for the twocell system which accepts a new call if it can guarantee with a certain probability that a user s call will be maintained irrespective of its his her movement in the system. Then we extend this adaptive scheme for multiple-cell network. We develop another variant of this adaptive scheme which we call fractional adaptive scheme. Both the adaptive and fractional adaptive schemes are found to outperform the guard channel scheme in controlling the handoff failure probability in a cellular wireless network. Copyright 2008 M. Rahman and A. S. Alfa. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium