Modeling and Analysis of a Hybrid CAC Scheme in Heterogeneous Multimedia Wireless Networks

Modeling and Analysis of a Hybrid CAC Scheme in Heterogeneous Multimedia Wireless Networks

Yuhong Zhang (Texas Southern University, USA) and Ezzatollah Salari (University of Toledo, USA)
Copyright: © 2012 |Pages: 14
DOI: 10.4018/jhcr.2012010102
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A hybrid call admission control (CAC) scheme for a heterogeneous multimedia mobile network is proposed and investigated. In addition to the reservation of the system capacity to the cells, the network center also reserves an amount of bandwidth for a possible dynamic allocation to all cells in order to increase the system utilization and minimize the blocking probability of calls. In each cell, a specific class of calls may need a specific bandwidth for connection, a specific call connection time period, and may possess a specific mobility feature. By considering the specific characteristics for different classes of calls, each cell of the network has the capability to provide service to at least a minimum number of calls for each class. This paper successfully derives an analytical expression for the stationary distribution of the number of calls in the whole network and obtains explicit mathematical formulae for measuring system performance, including the utilization of the network, the blocking probability for each class of calls, and the throughput of the network. The consistency of the numerical analysis with the theoretical results and the simulation analysis based on the model description confirms the correctness of the modeling and analysis.
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Next generation wireless networks are expected to provide a diverse range of multimedia services to mobile users with guaranteed quality of service (QoS). Since the radio resources are considered to be the primary scarce resource in mobile wireless networks, the main challenge in the design of an efficient call admission control (CAC) scheme is to balance two conflicting requirements: 1) satisfying the QoS requirement for each traffic class; 2) maximizing the system utilization (Oliveria, Kim, & Suda, 1998; Palade & Puschita, 2008; Chou & Shin, 2004) There are normally three main strategies for radio resource allocations in cellular wireless networks known as Fixed Channel Assignment (FCA), Dynamic Channel Assignment (DCA) and Hybrid Channel Assignment (HCA) (Lin & Noerpel, 1994). In general, there is a trade-off between quality of service, the implementation complexity of the channel allocation algorithms, and resource utilization efficiency. How to balance these three factors is important for the channel allocation strategies. There are various discussions concerning the advantages and disadvantages of the three allocation methods in the literature (Cox & Reudink, 1973; Everitt & Mansfield, 1989; Jiang, Lai, & Soundarajan, 2002; Katzela & Naghshineh, 1996; Zhang & Yum, 1989).

In both theoretical analysis and practical aspects, wireless systems supporting multiple users have more challenges than systems with a single user. For example, in a multiuser wireless system, a limited amount of system resources is shared by different call requests such as videos, phone calls, emails, etc. Such a system needs to efficiently allocate system resources to different service requests to achieve the satisfactory service quality. Because of various content complexities of different call requests, a multiuser wireless system may explore the content diversity among different users to efficiently utilize system resources and satisfy users' quality requirements. In addition, with a complicated wireless and mobile system involving many factors such as mobility, bandwidth allocation, and random call arrival processes, it is very difficult to find analytical expressions to measure the performance of the system. Instead of modeling the complete network, most analytical studies for the performance measurement of wireless systems concentrate on a single cell model (Alfa & Li, 2002; Fang, 2003; Fang & Zhang, 2002; Lin, Mohan, & Noerpel, 1994). Some papers in literature (Kim & Varshney, 2004; Oliveria, Kim, & Suda, 1998; Mitchell & Sohraby, 2001) consider the admission control scheme for multimedia traffic carried in high-speed wireless cellular networks. But the performance of the proposed scheme is evaluated through simulation technique, not an analytical expression. The effectiveness of these policies for multiple types of services having different QoS requirements in an integrated wireless and mobile network has not been investigated. Therefore, it is necessary to seek new resource allocation schemes and analytical models for the future integrated wireless and mobile networks, which can efficiently satisfy the desired level of QoS and provide appropriate priorities to each type of service.

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