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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 41467 (19)
- University: Sharif University of Technology
- Department: Computer Engineering
- Advisor(s): Beigy, Hamid
- Abstract:
- The rapid growth of broadband wireless access (BWA) has increased the demand of new application such as VoIP, video conferencing, online gaming each of which has different requirement for quality of service. Due to limited bandwidth provided for these networks, one of the most important issues is how effective we manage bandwidth in order to support requests. The quality of service is an important indicator of the effective management of bandwidth. Using mechanisms of call admission control is a commonly accepted method for balance between quality of service and increase of utilization resource in cellular mobile networks. In fact, call admission control is responsible to making decision about accepting or rejecting a request or a new connection. WiMAX is the communication and wireless digital system that can provide desirable quality of service for different types of traffic, particularly for real time services with broad‐bandwidth wireless connection. In this network, the call admission control uses to control the various traffic loads and prevent network overflow and it is very important to support quality of service. In the WiMAX networks, when a new connection request arrives at the base station, the connection admission control (CAC) mechanism takes the decision whether to accept the connection or reject the connection. The connection will be accepted if and only if the minimal requirements for that request can be satisfied by the network. Call admission control algorithm is a open issue and effective manner to ensure quality of services. In this thesis, four call admission control algorithms have been proposed which consist of single threshold with complete sharing call admission control, three threshold call admission control, three thresholds with complete sharing call admission control and three thresholds with complete sharing & borrowing capability call admission control. In these algorithms, all four classes of WiMAX service have considered. The purpose of each algorithm is improvement of utilization and effectiveness use of bandwidth and also reduction of new call blocking probability. In algorithms with complete sharing, the unused portion of bandwidth that reserved for high priority connections giving to lower priority connections in order to better use of bandwidth and prevent of useless bandwidth. High priority connections in three thresholds with complete sharing & borrowing capability call admission control algorithm provide the possibility of their acceptance in network with borrowing of bandwidth from lower priority, so reduces the new high priority call blocking probability. The proposed algorithms have evaluated by simulation and the results show that bandwidth sharing cause effective use of limited wireless resource and increase utilization of bandwidth. Borrowing bandwidth causes to reduce new high priority call blocking
- Keywords:
- Wireless Networks ; Call Admission Control ; Service Quality ; Institute Electrical and Electronic Engineers (IEEE)802.16 Standard ; Wordwide Interoperability for Microwave Access (WIMAX)Networks
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