Performance Analysis of Call Admission Control in WCDMA System with Adaptive Multi Class Traffic based on Fuzzy Logic

S.Malarkkan, and V.C.Ravichandran Research Scholar Professor ECE Department, College of Engineering, Guindy, Anna University, Chennai, India Summary Resource management is one of the most important engineering issues in 3G systems where multiple traffic classes are supported each being characterized by its required quality of service (QoS) parameters. Call admission control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. Call Admission Control is employed to decide whether to accept or not a new service request and its goal is to admit a higher number of service requests while at the same time guaranteeing the required QoS for every already active connection. CAC in CDMA systems is classically based on Interference or Signal to Interference Ratio estimates and threshold comparisons. Traditionally, a CAC scheme should explore a set of measured parameters to make the decision of accepting or rejecting a requesting call. This type of control scheme makes little or no allowance for measurement uncertainties. However, in the wireless system, due to user mobility, dynamic QoS requirements and varying channel conditions, the measurements obtained are, in general, not accurate. Furthermore, it is also difficult to obtain the complete statistics of input traffic. As a result, the decision has to be based on the imprecision and uncertain measurements. To this end, fuzzy logic provides an approximate but effective means of describing the behavior of the systems that are too complex and not easy to tackle mathematically. Having the nature of coping with uncertainty and imprecision problems, fuzzy logic is expected to provide a good solution to the development of a call admission control scheme. The fuzzy CAC scheme analysed in this paper takes into account the mobility information of the new user requesting connection and already existing users, the type of service request (real time or non-real time) and the load factor which is calculated from the intra-cell interference and the intercell interference at the base station.. The QoS requirement of the non real time traffic is reduced to accommodate more number of real time traffic users to improve the performance of the admission control scheme. Simulation results show that the fuzzy based CAC scheme performs better than the fixed CAC schemes without fuzzy in terms of new call blocking and handoff call dropping probabilities.