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Communication is significant way to move the data from one place to other place which is geographically located far away from each other. In early days telegraphy technique was used to send the information from place to other place with the help of wires. Telegraphy is very time consuming and non reliable method of data transmission. To overcome such type of problems engineers developed a new communication technology which is known as mobile communication. Mobile communication fulfils almost all the requirements of growing market and modern world. All business sectors are using mobile communication for data transmission. The new problem of fractal traffic is arrived because of limited channels and increase in fractal traffic to solve this problem traditional method is to improve the data transmission mechanism and quality of service.

Call admission control (CAC) scheme serves as a useful tool for the WiMAX technology, which ensures that resources are not overcommitted and thereby, all existing connections enjoy guaranteed quality of service (QoS). CAC schemes largely rely on readily available information like currently available resources and bandwidth demand of the new call while making an acceptance or rejection decision once a new request arrives. Since wireless channels are not as reliable as wired communication, CAC scheme in WiMAX communication faces a serious challenge of making a right estimate of the usable channel capacity (i.e., effective throughput capacity) while computing the available resources in various communication scenarios. Existing CAC schemes do not consider the impact of mobility at vehicular speeds when computing the usable link capacity and available resources. The main limitation of such CAC scheme is that when a mobile node moves at a slower speed and makes a connection request to the base station (BS), the BS evaluates the situation based on the currently available information. The BS in such cases, is short-sighted and often overestimates the available resources as it completely ignores the scenario when the SS reaches its top speed within a very short time after a CAC decision is made, causing a significant drop in usable throughput. In this paper, we address this limitation of existing WiMAX CAC schemes and propose a new CAC scheme that estimates the usable link capacity for WiMAX communication at vehicular speeds and uses this information while making a CAC decision. We also present a CAC scheme that takes the speed distribution model of a mobile node into account during the CAC decision making process. Simulation results confirm that the proposed scheme achieves lower dropping rate and improved QoS compared to existing schemes.

We propose a call admission control policy and prove that the CTMC that models the multiservice wireless system enforcing the CAC scheme is reversible and its stationary distribution is insensitive to the channel holding time distribution. © 2011 IEEE.

The IEEE 802.16e standard has emerged as an exciting mobile wireless broadband technology that promises to deliver both high throughput and guaranteed quality of service (QoS). Call admission control (CAC) scheme serves as a great utility for WiMAX, which ensures that resources are not over committed and thereby, all existing connections enjoy guaranteed quality of service. Existing CAC schemes largely depend on computation of available resources while making an acceptance or rejection decision once a new request arrives. Since wireless channels are not as reliable as wired communication, CAC scheme in WiMAX communication faces a serious challenge of making a right estimate of the usable channel capacity while computing the available resources at various communication scenarios. Existing CAC schemes do not consider the impact of mobility at vehicular speeds when computing the usable link capacity and available resources. In this paper, we propose a new CAC scheme that estimates the usable link capacity for WiMAX communication at various vehicular speeds and uses this information while making a CAC decision. Extensive simulation results show that the proposed scheme achieves lower dropping rate and improved QoS compared to existing schemes.

The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) is designed to provide differentiated services without real hard performance guarantees, such as bandwidth and delay bounds in wireless LANs. In this paper we design a measurement-assisted, model-based call admission control (MM-CAC) scheme to support guaranteed QoS in the EDCA. For this purpose, we first develop an accurate analytical model of the legacy IEEE 802.11 DCF under non-saturation conditions; then using this model, we define the concept of equivalent number of competing entities, to convert a heterogeneous (multi-class) EDCA network into an equivalent homogeneous network and study traffic classes in isolation. Our analytical model is then invoked to decide to admit a new flow or reject it with much little computational complexity as compared to a fully fledged EDCA model. Numerical results validate our model and analysis, and simulations demonstrate the effectiveness of our MM-CAC scheme. © 2009 World Scientific Publishing Company.

The hybrid optical wireless (HOW) network has been viewed as a promising solution to meet the increasing user bandwidth and mobility demands. Due to the basic differences in the optical and wireless technologies, a challenging problem lies in the Media Access Control (MAC) protocol design so that it can support stringent Quality of Service (QoS) requirements. In this paper, we describe and evaluate a resource management framework designed for the HOW networks. There are two parts in the resource management framework The first part is the Enhanced MPCP (E-MPCP) scheme aiming at improving signaling ability between the optical and wireless networks. The second part is an Integrated Optical Wireless Admission Control (IOW-AC) scheme aiming at providing the integrated bandwidth allocation in the HOW networks. Our results show that the performances of the system in terms of throughput, delay and packet dropping probability depend on several factors. These factors include the frame duration, the traffic load and the total number of shared users. The results also highlight that our proposed system achieves significant improvements over the traditional approach in terms of user QoS guarantee and network resource utilization.

Efficient utilization of available bandwidth over hybrid optical wireless networks is a critical issue, especially for multimedia applications with high data rates and stringent Quality of Service (QoS) requirements. In this paper, we propose an integrated resource management including an enhanced resource sharing scheme and an integrated admission control scheme for the hybrid optical wireless networks. It provides QoS guarantees for connections through both optical and wireless domain. Simulation results show that our proposed scheme improves QoS performances in terms of high throughput and low dropping probability.

In this paper, we propose a scalable algorithm for connection admission control (CAC). The algorithm applies to a Multiprotocol Label Switching (MPLS) ATM switch with a FIFO buffer. The switch carries data from statistically independent variable bit rate (VBR) sources that asynchronously alternate between ON and OFF states with exponentially distributed periods. The sources may be heterogeneous both in terms of their statistical characteristics (peak cell rate, sustained cell rate, and burst size attributes) as well as their Quality of Service (QoS) requirements. The performance of the proposed CAC scheme is evaluated using known performance bounds and simulation results. For the purpose of comparison, we also present scalability analyses for some of the previously proposed CAC schemes. Our results show that the proposed CAC scheme consistently performs better and operates the link close to the highest possible utilization level. Furthermore, the scheme scales well with increasing amount of resources (link capacity and buffer size) and accommodates intelligently the mix of traffic offered by sources of diversed burstiness characteristics.

We develop and analyze a class of CAC algorithms for resource management in wireless networks with the goal not only to satisfy QoS constraints, but also to maximize a value or reward objective function specified by the system. We demonstrate through analytical modeling and simulation validation that the CAC algorithms developed in this research for resource management can greatly improve the system reward obtainable with QoS guarantees, when compared with existing CAC algorithms designed for QoS satisfaction only. We design hybrid partitioning-threshold, spillover and elastic CAC algorithms based on the design techniques of partitioning, setting thresholds and probabilistic call acceptance to use channel resources for servicing distinct QoS classes. For each CAC algorithm developed, we identify optimal resource management policies in terms of partitioning or threshold settings to use channel resources. By comparing these CAC algorithms head-to-head under identical conditions, we determine the best algorithm to be used at runtime to maximize system reward with QoS guarantees for servicing multiple service classes in wireless networks. We study solution correctness, solution optimality and solution efficiency of the class of CAC algorithms developed. We ensure solution optimality by comparing optimal solutions achieved with those obtained by ideal CAC algorithms via exhaustive search. We study solution efficiency properties by performing complexity analyses and ensure solution correctness by simulation validation based on real human mobility data. Further, we analyze the tradeoff between solution optimality vs. solution efficiency and suggest the best CAC algorithm used to best tradeoff solution optimality for solution efficiency, or vice versa, to satisfy the system's solution requirements. Moreover, we develop design principles that remain applicable despite rapidly evolving wireless network technologies since they can be generalized to deal with management of 'res

Call holding times in telephony networks are commonly approximated by exponential distributions to facilitate traffic engineering. However, for traffic engineering of cellular networks, channel occupancy times need to be modeled instead to facilitate analytical modeling or to feed network simulations. In this paper, we classify channel occupancy times and present an empirical study based on data obtained from a real cellular network to determine which probability distribution functions can approximate them better. The results are environment dependent, but no assumptions that can be influential are made, as opposed to previous analytical and simulation studies which results are highly dependent on the assumptions made by the authors. We show that all types of channel occupancy times can be approximated by lognormal distribution. For stationary users, channel occupancy times are commonly approximated by exponential distribution due to its tractability, assuming that cell residence times are also exponentially distributed. However, we show that lognormal distribution fits much better to both channel occupancy and call holding times regardless of whether users are stationary or mobile., QC 20120109

This paper addresses the issue of call admission control with the necessary Quality-of-Service (QoS) guarantee for an integrated service mobile cellular network. Specifically, we extend the Limited Fractional Guarded Channel (LFGC) scheme to incorporate the multiple traffic types, and derive the set of parameters that leads to the optimal call admission control. The key challenges are the state-dependent nature of the admission control, and the increasing complexity of the state space in a multi-services environment. We propose a novel control meachanism that only uses a few parameters (2-5) to characterize the optimal control planes, and use the simulated annealing technique to obtain the optimal control parameters.

Many communications and networking systems can be modelled as resource-sharing systems with multiple classes of calls. Call admission control (CAC) is an essential component of such systems. For most practical systems it is prohibitively difficult to compute the optimal CAC policy that optimizes certain performance metrics because of the 'curse of dimensionality'. In this paper we study two families of structured CAC policies: threshold and reservation policies. These policies are easy to implement and have good performance in practice. However, since the number of structured policies grows exponentially with the number of call classes and the capacity of the system, finding the optimal structured policies is a complex unsolved problem. In this paper efficient search algorithms are proposed to find the coordinate optimal structured policies among all structured policies. Through extensive numerical experiments we show that the search algorithms converge quickly and work for systems with large capacity and many call classes. In addition, the returned structured policies have optimal or near-optimal performance, and outperform those structured policies with parameters chosen based on simple heuristics. © 2005 IEEE.

In this paper, We propose a new call admission control scheme called dual threshold bandwidth reservation, or DTBR scheme. The main novelty is that it builds upon a complete sharing approach, in which the channels in each cell are shared among the different traffic types and multiple thresholds are used to meet the specific quality-of-service (QoS) requirements. We present a detailed comparative study based on mathematical and simulation models, and quantitatively demonstrate that the DTBR is capable of providing the QoS guarantee for each type of traffic, while at the same time leading to much better channel efficiency. We further show that the DTBR scheme with elastic data service can offer both service guarantee and service differentiation for voice and data services, and enhance the bandwidth utilization.

This paper analyses the performance of DS-CDMA networks in the presence of call handoffs. We show that a handoff may violate the SINR requirements for other users, and thus cause an outage in the target cell. We propose to use the probability of such events as a possible metric for quality of service in networks with multiple traffic types, and derive the corresponding QoS parameters. A two-level admission policy is defined: in tier 1 policy, the network capacity is calculated on the basis of the bound on outage probability. However, this policy does not suffice to prevent outage events upon handoffs for various traffic types, and henceforth, we propose an extension that reserves extra bandwidth for handoff calls, thus ensuring that handoff calls will not violate the outage probability bound. The overhead imposed by the extension is negligible, as the complete two-tier admission control algorithm is executed only when a call is admitted into the network. Once admitted, calls can freely execute handoffs using the reserved bandwidth. The modified second-tier bandwidth reservation policy is adaptive with respect to the traffic intensity and user's mobility and we show that it can provide satisfactory call (flow) quality during its lifetime. Analytical results for the QoS have been verified by the simulations. Copyright (C) 2002 John Wiley Sons, Ltd.

One of the key issues in the next generation wireless cellular networks is to support multiple services, in which call admission control policy has to guarantee the different Quality of Service (QoS) requirement from diverse applications, and at the same time ensure the scarce bandwidth be utilized efficiently. In this paper, we first build upon our proposed Dual Threshold Bandwidth Reservation (DTBR) scheme to integrate more realistic, variable data traffic, and then proceed to analyze the DTBR scheme using two-dimensional Markov process. Both analysis and simulation results indicate that, by keeping target handoff voice call dropping probability, adoption of elastic data traffic model can reduce handoff voice call dropping probability and improve overall system award; by adjusting the threshold values in the DTBR, we demonstrate that it is capable of satisfying different QoS requirements for voice and data traffic while achieving the maximum utility.

Wireless networks are evolving to include Internet access to interactive multimedia and video conferencing as well as traditional services such as voice, email and web access. These new applications can demand large amounts of network resources, such as bandwidth, to achieve the highest levels of quality (e.g. picture quality). In conjunction with this trend, charging and resource allocation systems must evolve to explicitly consider the trade-off between resource consumption and the Quality of Service (QoS) provided. This paper proposes a novel QoS-based charging and resource allocation framework. The framework allocates resources to customers based on their QoS perceptions and requirements, thereby charging fairly while improving resource allocation efficiency. It also allows the network operators to pursue a wide variety of policy options, including maximizing revenue or using auction or utility-based pricing. Copyright

Some problems related to wireless network access are discussed in the article. Special attention is paid to Medium Access Control and Call Admission Control. Both have direct impact on communication link accession. While the first one dictates how to, the second one decides who can access the link. The problems with wireless medium access are mentioned and requirements on MAC protocols are named. Also need for CAC algorithms is illustrated and simple functional example is proposed. Finally, the reasons for future enhancements are shortly discovered.

This paper presents a new adaptive bandwidth allocation scheme to prevent handoff failure in wireless cellular networks, known as the measurement-based preassignment (MPr) technique. This technique is particularly useful in micro/pico cellular networks which offers quality-of-service (QoS) guarantee against call dropping: The proposed MPr scheme distinguishes itself from the well-known guarded channel (GC) based schemes in that it allows the handoff calls to utilize a prereserved channel. pool before competing for the shared channels with new call arrivals. The key advantage of the proposed MPr scheme is that it enables easy derivation of the number of channels that needs to be reserved for handoff based on a predetermined handoff dropping probability, without the need for solving the often complex Markov chain required in GC schemes; thus, making the proposed MPr scheme-simple and efficient for implementation. This is essential in handling multiple traffic types with potentially different QoS requirements. In addition, the MPr scheme is adaptive in that it can dynamically adjust the number of reserved channels for the handoff according to the periodical measurement of the traffic status within a local cell; thus completely eliminating the signaling overhead for status information exchange among cells mandated in most existing channel allocation schemes. Numerical results and comparisons are given to illustrate the tradeoff.

We have recently witnessed a phenomenal growth in the development and deployment of wireless services, evident from the proliferation of the cellular data services and the emerging wireless multimedia applications. This opens up a new avenue for research, and calls for the re-examination of some of the fundamental issues in wireless cellular networks. With the cell size being systematically reduced into micro-cell and pico-cell systems, in order to increase the overall network capacity, one of the key challenges is the design of effective call admission control (CAC) policies, which have to guarantee potentially different quality of service (QoS) requirements from diverse traffic types while at the same time maintaining high utilization of the scarce wireless bandwidth. The objectives of this article are to review the key issues involved in the design of call admission control policies based on some of the recent proposals, and to discuss the challenges associated to offer effective support for multi-services.

Call admission control is one of the key elements in ensuring the quality of serivce in mobile wireless networks. The traditional trunk reservation policy and its numerous variants give preferential treatment to the handoff calls over new arrivals by reserving a number of radio channels exclusively for handoffs. Such schemes, however, cannot adapt to changes in traffic pattern due to the static nature. This paper introduces a novel stable dynamic call admission control mechanism (SDCA), which can maximize the radio channel utilization subject to a predetermined bound on the call dropping probability. The novelties of the proposed mechanism are: 1) it is adaptive to wide range of system parameters and traffic conditions due to its dynamic nature, 2) the control is stable under overloading traffic conditions, thus can effectively deal with sudden traffic surges; 3) the admission policy is stochastic, thus spreading new arrivals evenly over a control period, and resulting in more effective and accurate control; an 4) the model takes into account the effects of limited channel capacity and time dependence on the call dropping probability, and the influences from nearest and next-nearest neighboring cells, which greatly improve the control precision. In addition, we introduce local control algorithms based on strictly local estimations of the needed traffic parameters, without requiring the status information exchange among different cells, which makes it very appealing in actual implementation. Most of the computational complexities lie in off-line precalculations, except for the nonlinear equation of the acceptance ratio, in which a coarse-grain numerical integration is shown to be sufficient for stochastic control. Extensive simulation results show that our scheme steadily satisfies the hard constraint on call dropping probability while maintaining a high channel throughput.

Some problems related to wireless network access are discussed in the article. Special attention is paid to Medium Access Control and Call Admission Control. Both have direct impact on communication link accession. While the first one dictates how to, the second one decides who can access the link. The problems with wireless medium access are mentioned and requirements on MAC protocols are named. Also need for CAC algorithms is illustrated and simple functional example is proposed. Finally, the reasons for future enhancements are shortly discovered.

Some problems related to wireless network access are discussed in the article. Special attention is paid to Medium Access Control and Call Admission Control. Both have direct impact on communication link accession. While the first one dictates how to, the second one decides who can access the link. The problems with wireless medium access are mentioned and requirements on MAC protocols are named. Also need for CAC algorithms is illustrated and simple functional example is proposed. Finally, the reasons for future enhancements are shortly discovered.

The next generation of mobile wireless networks has to provide the quality-of-service (QoS) for a variety of applications. One of the key generic QoS parameters is the call dropping probability, which has to be maintained at a predefined level independent of the traffic condition. In the presence of bursty data and the emerging multimedia traffic, an adaptive and dynamic bandwidth allocation is essential in ensuring this QoS, The paradox, however, is that all existing dynamic bandwidth allocation schemes require the prior knowledge of all traffic parameters or/and user mobility parameters. In addition, most proposals require extensive status information exchange among cells in order to dynamically readjust the control parameters, thus making them difficult to be used in actual deployment. In this paper, we introduce a novel adaptive bandwidth allocation scheme which estimates dynamically the changing traffic parameters through local on-line estimation. Such estimations are restricted to each individual cell, thus completely eliminating the signaling overhead for information exchange among cells. Furthermore, we propose the use of a probabilistic control policy, which achieves a high channel utilization, and leads to an effective and stable control. Through simulations, we show that our proposed adaptive bandwidth allocation scheme can guarantee the predetermined call dropping probability under changing traffic conditions while at the same time achieving a high channel utilization.

Call admission control can significantly affect the performance of a cellular system by adding additional bandwidth to a wireless network. In this paper, we show how call admission control can be used to optimize the performance of a hierarchical cellular system. The hierarchical system we study is based on a novel frequency planning scheme, whereby both the micro and macro layers can share the same spectrum and a hard partition of frequency spectrum is not needed. The original analysis of the hierarchical system showed that a significant capacity gain can be achieved by the scheme. However, this capacity is gained at the expense of the carrier-to-interference ratio (C/I) performance of the macrocells. In this paper, we show that call admission control can be used in hierarchical cellular systems to achieve a capacity gain without sacrificing the C/I performance of the macrocells.

Adaptive admission control in cellular wireless networks reserves bandwidth for handoff calls, which is proportional to the traffic intensity in the surrounding cells. This paper analyzes performance (QoS) of the adaptive admission algorithm in the presence of nonuniform traffic conditions in the network. We model the performance of small, moderate, and large hot-spots, and analyze average cell capacity utilizations and their derivatives when the hot-spot new call arrival rate is growing and surrounding cells operate! at the constant load, The analysis shows that under sufficient bandwidth reservation, derivatives of the hot-spot cell capacity utilizations converge to zero for hot-spot call arrival rates larger than twice the nominal load. Since the average utilization is the linear combination of all the state probabilities of the Markov chain, the convergence of its derivative to zero under high offered loads means that the derivatives of other linear combinations of state probabilities, such as handoff dropping probability and new call blocking probability, will also converge to zero, Therefore, handoff dropping probability and new call blocking probability must be bounded by the logarithmic function of new call arrival rate for large arrival rates. Due to the feedback property embedded in the bandwidth reservation process, our admission algorithm offers QoS bounds both under nominal load and under high arrival rates. The analytical results have been validated by simulations.

In this paper, a new adaptive admission control scheme for wireless cellular network supporting mixed narrowband and wideband traffic is proposed. The scheme is event-based and provides hard constraints on hand-off dropping probability requirements. The role of the quality of service (QoS) regulation parameter P-ov in the call admission process is analyzed acid presented. The analytic results are validated by simulation. We also show that the analytic model is extensible to more than two types of traffic. (C) 1999 Elsevier Science B.V. All rights reserved.

Call admission control (CAC) is one of the key elements to provide quality of service (QoS) guarantee in wireless mobile networks. A good CAC scheme should efficiently support handoffs and maintain a high utilization of the scarce radio resource while it should also be simple for implementation without loss of applicability. Since the traditional guard channel policy is not optimal for a hard constrained handoff dropping probability, there are some new proposals in the literature. Among them, the distributed call admission control seems to be simpler and more efficient with regards to the above requirements. However, there are some problems in original scheme which make the implementation complex and lead to performance degradation. In this paper, we will first discuss simplifications to the original scheme, and then further enhance the modified scheme by considering the difference of mobility support requirement between high and low mobility users. The simulation results shows that the enhanced scheme gives better performances.

Estimating the cell loss probability in an ATM multiplexer is a key issue in network management and traffic control such as call admission control and bandwidth allocation. In this paper, we derive a new approximation to estimate the total and individual cell loss probabilities in an ATM multiplexer fed by a superposition of heterogeneous on-off sources with exponentially distributed on and off periods. Based on this approximation, a simple and accurate method is proposed to estimate the aggregate required bandwidth by a given mix of traffic to guarantee a given cell loss probability.

An important parameter an asynchronous transfer model (ATM)-based network design and management is the cell loss ratio (CLR) in ATM multiplexers. It is a key parameter to many vital functions in the network such as call admission control (CAC), bandwidth allocation, etc, However, the CLR depends usually on many unknown and unpredictable traffic parameters such as input traffic correlations. In this paper, we propose a simple and robust fuzzy-based algorithm to predict the CLR in large-sized systems based on both a small amount of information from small-sized systems, and the asymptotic behavior for very large systems, Unlike the model-based approaches, our approximation avoids the problem of assuming any traffic parameters or arrival process, This algorithm is used with real-time traffic measurement to propose an effective measurement-based call admission control framework for ATM networks.

An important parameter in ATM-based network design and management is the cell loss probability in ATM multiplexers. However, it depends on many unknown and unpredictable traffic parameters such as burst length distribution, mean rate, etc. In this paper, we propose a simple and robust fuzzy-based algorithm to predict the cell loss probability in large-sized systems based only on both a small amount of information from small-sized systems, and the asymptotic behavior for very large systems. Numerical results show that the value predicted by this algorithm is quite accurate. The application of the proposed algorithm to call admission control is also presented.

In this paper, we study the call admission control problem for an ATM multiplexer loaded with heterogeneous low-motion VBR video sources. To estimate the bandwidth required by a VBR video source, we characterize its traffic by five parameters: peak rate, bottom rate, mean rate, standard deviation, and the coefficient of the autocorrelation function. The aggregate traffic of a number of VBR video sources is modelled by a discrete-time Markov modulated deterministic process (D-MMDP) which can be obtained by the superposition of a number of identical and independent two-active-state mini-sources. Based on the effective bandwidth approach and the Gaussian approximation, we derive simple formulas for estimating the required bandwidth. From the numerical results, we conclude that the stationary Gaussian approximation produces a very efficient and yet conservative call admission control scheme for the teleconference VBR video sources studied in this paper. The performance of the effective bandwidth approach degrades due to its inability of making full use of statistical multiplexing gain when the number of source increases.

Noura, M., Ahmad, I., Noura, A., & Nordin, R. (2017). A Discrete Event Simulation for Hierarchical Mobile IPv6. Wireless Personal Communications, 95(4), 4883-4901. Available here

In this paper we consider call admission control in cellular environment for data sessions and voice calls of high priority. A cell is divided into two zones with different average signal to noise ratio, and each zone uses its own modulation and coding. A dynamic resource allocation scheme is further considered, which allows communication systems to utilize their resources more efficiently. All the idle channels, which are left after the voice calls, are allocated to elastic data sessions to increase their transmission rate. When a voice call arrives, required channels can be released to serve it if only elastic data calls have a minimum required bandwidth to continue their sessions. To evaluate the role of elastic traffic, analytical models with elastic and fixed data sessions are formulated and solved. For both cases we derive blocking probabilities as well as other performance metrics of interest. According to numerical results, elastic data sessions achieve higher channel utilization and their mean transmission time is ten times less than that of fixed data sessions. As a result, the mean number of elastic data sessions in the system is twice less than that of fixed data sessions. © 2011 IEEE.