未來的無線多媒體網路下,我們期待能夠使用許多不同種類的服務。頻寬配置(Bandwidth Allocation)和呼叫允入控制(Call Admission Control)的方法是要讓已經被接受的使用者的應用程式能有良好的服務品質。
基於網路資源有限的狀況下,本論文提出頻寬可用度測試法(Bandwidth Availability Testing Method)用來測試使用者的頻寬需求是不是能夠使用為網路服務所接受。我們首先用Bernoulli隨機變數建立頻寬使用的數學模型。接著我們提出計算系統過載的機率(Overload Probability)以及使用者移交(Handoff)被拒絕的機率(Handoff Dropping Probability)。在無線的環境下使用者移交被拒絕的機率可以被視作使用者所使用的服務服務品質的重要指標,因此也可以作為代表要求的頻寬可以被使用的程度。
我們利用提出的頻寬可用度測試方法,替新產生的呼叫(New Call)以及移交的呼叫(Handoff Call)做允入控制。為了要降低移交時使用者被拒絕的機率,並且提高頻寬的利用率,我們提出在允入控制時重新配置頻寬的方法,由已經被接受的使用者取得需要的頻寬,並優先從即將要離開的使用者提供頻寬作重新分配。
我們用模擬的方式來檢驗我們的允入控制方法,並且將結果與其他的方法的結果做比較。實驗結果證實我們的方法能夠提升網路頻寬的使用率,並提高無線網路的傳輸效能。

It is expected that in the future that multimedia wireless network will provide a variety of services. Bandwidth allocation and admission control schemes are used in order to guarantee the
quality of the service requested by users already admitted to the system.

In this thesis, we proposed bandwidth vailability testing (BAT) method to test whether the bandwidth requested by the user is available. We first model the usage of the bandwidth using binomial random variables. Then the algorithm to calculate the overload probability and the handoff dropping probability is proposed. The handoff dropping probability can be deemed as an
important indicator to the quality of service (QoS) received by the users who requested the service, and hence can be an indicator to represent the availability of the requested bandwidth.

Admission control scheme for handoff calls and new calls that make use of the bandwidth availability testing method is proposed in this thesis. In order to reduce the handoff dropping probability and the bandwidth utilization, we proposed a handoff admission control algorithm that reallocate bandwidth from the user who is already admitted to the system. Only the user who will handoff to another cell in a short time will be chosen.

The proposed admission control scheme is tested using the simulation. We compare the result to that of other handoff admission control schemes.

C. Oliveira, J. B. Kim, and T. Suda, ``An Adaptive Bandwidth
Reservation Scheme for High-Speed Multimedia Wireless Networks,``
IEEE JSAC, vol. 16, no. 6, Aug. 1998, pp. 858-874.

S. Choi and K. G. Shin, ``Adaptive Bandwidth
Reservation and Admission Control in QoS-Sensitive Cellular
Networks,`` IEEE Trans. on Parellel and Distributed Systems, vol.
13, no. 9, Sept. 2002, pp. 882-897.s

D. A. Levine, I. F. Akyildiz, ``A Resource Estimation and
Call Admission Algorithm for Wireless Multimedia
Networks Using the Shadow Cluster Concept,`` IEEE Trans.
Networking, vol. 5, no. 1, FEB. 1997, pp. 1-11.

J. Misic and T. Y. Bun, ``Adaptive Admission
Control in Wireless Multimedia Networks Under Nununiform Traffic
Conditions,`` IEEE JSAC, vol. 18, no. 11, NOV. 2000, pp.
2429-2442.

M. Naghshineh and M. Schwartz, ``Distributed Call Admission
Control in Mobile/Wireless Networks,`` IEEE JSAC,
vol. 14, no. 4, MAY 1996, pp. 711-717.

M. E. Kadi, S. Olariu, and H. Abdel-Wahab, ``A Rate-Based Borrowing
Scheme for QoS Provisioning in Multimedia Wireless Networks,``
IEEE Trans. Parellel and Distributed Systems,
vol. 13, no.2, FEB 2002, pp. 156-166.

A. Aljadhai, and T. F. Znati, ``Predictive Mobility
Support for QoS Provisioning in Mobile Wireless Environments,``
IEEE JSAC, vol. 19, no. 10, OCT. 2001, pp. 1915-1930.

W. S. Jeon and D. G. Jeong, ``Call Admission
Control for Mobile Multimedia Communications with Traffic Asymetry
between Uplink and Downlink,`` IEEE TRANS. Vehic. Tech.,vol. 50,
no. 1, JAN. 2001, pp. 59-66.

Geng-Sheng Kuo, Po-Chang Ko, and Min-Lian Kuo,
``A Probabilistic Resource Estimation and Semi-Reservation Scheme
for Flow-Oriented Multimedia Wireless Networks,`` IEEE
Communications Magazine, Feb. 2001, pp. 135-141.

Wee-Seng Soh and Hyong S. Kim, ``QoS
Provisioning in Cellular Networks Based on Mobility Prediction
Techniques,`` IEEE Communication Magazines, Jan. 2003, pp. 86-92.

Jonathan Chan and Aruna Seneviratne, ``A Practical
User Mobility Algorithm for Supporting Adaptive QoS in Wireless
Networks,``

George Liu and Gerald Maguire Jr., ``A class of
mobile motion prediction algorithm for wireless mobile computing
and communications,`` 1996.

W. C. Y. Lee, "Smaller Cells for Greater
Performance," IEEE Commun. Mag., pp. 19-23, Nov. 1991.

Lin, Y.-B., Mohan, S., and Noerpel, A. ``PCS Channel
Assignment Strategies for Hand-off and Initial Access,`` IEEE
Personal Communications Magazine, 1(3): 47-56,1994.

T. H. Coremen, C. E. Leiserson, R. L.
Rivest, and C. Stein,``Introduction to Algorithms,`` The MIT
Press, pp. 1043-49.