In order to guarantee quality of service (QoS) of existing users and to optimize the overall system resource utilization, call admission control (CAC) along with efficient resource reservation scheme plays an important role in next generation wireless networks like WiMax. In prediction based or proactive CAC scheme, new incoming call is admitted or denied based on some predictive or analytical assessment of the user's QoS constraints, wireless channel condition and/or the traffic characteristics. In this paper, we propose a new predictive CAC and resource reservation scheme that predicts the instantaneous new incoming call's QoS requirement using adaptive filtering approach based on the past knowledge gained as well as the QoS trend of the already admitted calls. In our approach, we predict the QoS characteristics of the new calls requiring admission in the network at a predetermined future time. This estimation is based on normalized least mean square (NLMS) adaptive filtering. Based on the estimated characteristic of the future calls and the amount of reserved resource available, instantaneous CAC decision is taken on the new calls and network congestion notification is made and network utilization factor is determined. We have presented computer simulation results to show the effectiveness of our proposed scheme and the efficacy of the different parameters for optimizing the overall CAC and resource reservation process.
[Show abstract][Hide abstract] ABSTRACT: Radio resource management (RRM) plays a major role in Quality of Service (QoS) provisioning for wireless communication systems. The performance of RRM techniques has a direct impact on each user's individual performance and on the overall network performance. Arriving (new and handoff) calls are granted/denied access to the network by the call admission scheme (CAC) based on predefined criteria, taking the network loading conditions into consideration. CAC in wireless networks has been receiving a great deal of attention during the last two decades due to the growing popularity of wireless communications and the central role that CAC plays in QoS provisioning in terms of the signal quality, call blocking and dropping probabilities, packet delay and loss rate, and transmission rate. In the first and second generation of wireless systems, CAC has been developed for a single service environment. In the third generation and beyond wireless systems, multimedia services such as voice, video, data, and audio are to be offered with various QoS profiles. Hence, more sophisticated CAC schemes are developed to cope with these changes. This article provides a comprehensive survey of CAC schemes in modern wireless networks.
[Show abstract][Hide abstract] ABSTRACT: This paper introduces a distributed call admission controller for ad hod networks. The call admission controller is based on service curve provisioning. Service curve reflects the status of network and depends on the number of active nodes, their activity index, and the back-off procedure used for contention resolution. The service curve along with the aggregated traffic function can be used to calculate maximum delay and maximum backlog. We assume that the call requests are granted if the service curve is bounded below by some non-decreasing deterministic function which is called the universal service curve. The universal service curve is independent of the number of nodes and traffic fluctuation and acts as a worst-case reference curve. All users willing to establish a new connection should compare the performance of network to the universal service curve. A call request is accepted if the true service curve stays above the universal service curve.
[Show abstract][Hide abstract] ABSTRACT: This article presents a survey on the issues and the approaches related to designing call admission control schemes for fourth-generation wireless systems. We review the state of the art of CAC algorithms used in the traditional wireless networks. The major challenges in designing the CAC schemes for 4G wireless networks are identified. These challenges are mainly due to heterogeneous wireless access environments, provisioning of quality of service to multiple types of applications with different requirements, provisioning for adaptive bandwidth allocation, consideration of both call-level and packet-level performance measures, and consideration of QoS at both the air interface and the wired Internet. To this end, architecture of a two-tier CAC scheme for a differentiated services cellular wireless network is presented. The proposed CAC architecture is based on the call-level and packet-level QoS considerations at both the wireless and wired parts of the network. A performance analysis model for an example CAC scheme based on this architecture is outlined, and typical numerical results are presented.
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