QoS Provisioning Using Optimal Call Admission Control for Wireless Cellular Networks

Abstract

The increasing demand for advanced services in wireless networks raises the problem for quality of service (QoS) provisioning with proper resource management. In this research, such a provisioning technique for wireless networks is performed by Call Admission Control (CAC). A new approach in CAC named by Uniform Fractional Band (UFB) is proposed in this work for the wireless networks for providing proper priority between new calls and handover calls. This UFB scheme is basically a new style of handover priority scheme. Handover priority is provided by two stages in this scheme which help the network to utilize more resources. The first priority stage is fractional priority and the second stage is integral priority. Fractional priority is provided by the uniform fractional acceptance factor that accepts new calls with the predefined acceptance ratio throughout the fractional priority stage (fractional band of channels). Integral priority is given to the handover calls by reserving some channels only for handover calls. In this work, it is shown that UFB scheme proofs itself as optimum call admission technique which is concerned about not only the QoS but also the proper channel utilization with respect to conventional guard channel and fractional channel schemes. In this thesis work, conventional fixed and fractional guard channel based CAC schemes are studied literally and presented in this paper in very easy mathematical method. In addition, the handover call rate estimation and its impact on QoS provisioning is discussed widely to attain the optimum QoS in proposed handover priority scheme. In multiple services providing wireless network, excessive call blocking of lower priority traffic is very often event at very high traffic rate which is a concerning issue for QoS provisioning. To attain such QoS provisioning for multiple services, another CAC scheme is proposed in this research work. This scheme is recognised by Uniform Band Thinning (UBT) scheme which is based on uniform thinning technique (UTT) and this is quite similar idea as UFB scheme. In this scheme, a set of channels experiences the fractionizing policy. This scheme reduces the call blocking probabilities (CBP) of lower priority traffic classes without notably increasing the CBP's of the higher priority traffic classes. The analytical functions of this scheme are deduced in general form which is useful to deduce for any number of traffic classes. In addition, numerical analysis of the proposed UBT scheme shows that the performances in terms of call blocking probability, overall call blocking probability, and channel utilization are improved and optimised compared to the conventional fixed guard channel scheme. Keywords: Call admission control, call dropping probability, call blocking probability, quality of services, thinning schemes, acceptance factor, uniform fractional band, uniform band thinning, channel utilization, and traffic class.