PERFORMANCE EVALUATION OF DYNAMIC PRIORITY CALL ADMISSION CONTROL ALGORITHM FOR WCDMA BASED 3G NETWORKS

The wideband code division multiple access (WCDMA) based 3G cellular mobile wireless networks is expected to provide diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). In order to provide the diverse quality of service required by the users of these networks, an effective radio resource management (RRM) is necessary. Radio resource management is responsible for the efficient and optimal utilization of network resources while providing QoS guarantees to various applications. Call admission control is a form of radio resource allocation scheme used for QoS provisioning in a network, which restricts access to the network based on resource availability, in order to prevent network congestion and consequent service degradation. This research focuses on how to maintain service continuity with quality of service guarantees and provide service differentiation to mobile user’s traffic profile by efficiently utilizing system resources. The services are divided into four traffic classes’ handoff real-time, handoff non-real time, new call real-time and new call non-real-time respectively, giving higher priority to handoff traffic classes. It uses an algorithm referred to as dynamic prioritized uplink call admission control (DP-CAC), an efficient tool that provides better performance for WCDMA based 3G network. Beyond system utilization, revenue and grade of service as the key performance indicators, this research work also considers the queuing delay and the call blocking/dropping probability of each traffic class. From the simulation results and analysis it is discovered that the new call non-real-time traffic class experiences greater queuing delay of 1.42E-11 at increasing traffic intensity compared to other traffic classes in the system. It is also discovered that at peak traffic intensity of 3.60E+03 handoff RT has a probability of 1.59E-02, handoff NRT a probability of 1.69E-02, new call RT a probability of 2.00E-02 and new call NRT a probability of 2.10E-02 showing that call blocking/dropping probability of handoff and new calls at high traffic condition is minimized. This is achieved because the model dynamically switches handoff traffic to its reserved channel, and allows new calls to go through the general server thereby providing service continuity to handoff traffic and fairness to new call traffic classes respectively.

For some years now, cellular telephony systems have been experiencing a level of unprecedented growth in the world of telecommunications. When the first cellular technologies were brought into service, at the beginning of the 1980s, there was a rather slow take-off in the number of subscribers, hardly presaging the subsequent spectacular growth [1, 2]. The slow take-off of subscribers was however a result of incompatibility between the systems, and major differences in the use of the radio segment [2, 3]. Unfortunately, travelers who go to countries where the technology offered by their operator is not represented find themselves suddenly deprived of their communication tool because the subscriber management is not at all the same on the different systems [1, 2, 4, 5]. It was therefore imperative to have a unified standard which will address these issues and this led to the evolution of the first generation analogue system and then to fourth generation system referred to as the long term evolution system (LTE). The different evolutions of the cellular network have their respective frequency of operation, modulation scheme, protocol of operation, access mode technology, and physical architecture, but one common feature is the signaling standard.

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