A call admission control scheme for ATM networks using a simple quality estimate

For systems based on connection-oriented services, such as IEEE 802.16, call admission control (CAC) strategy is essential to provide a desired level of quality of service (QoS). Although many handoff-prioritized CAC schemes, which assume a fixed channel capacity, have been introduced, this assumption is not always valid for IEEE 802.16 that uses adaptive modulation and coding (AMC). With AMC, the modulation type of a user’s connection can be changed dynamically and the ongoing connection might fail due to the change of modulation. In this paper, we approach the AMC-induced CAC problem by focusing on the guaranteed connection. Three kinds of calls, new, handoff, and modulation-changed calls, are considered. We propose a modified guard channel CAC scheme that allows the modulation-changed and handoff calls to use the guard channel. Then we analyze a Markov model for the CAC scheme with long-term AMC in mind. According to the simulation results, the proposed approach reduces the call dropping probability for modulation-changed calls, which suggests the threshold of guard channels in IEEE 802.16 can be determined based on the proposed approach.

Next generation wireless networks will support a diverse set of access technologies. And the demanding breed of multimedia applications will even more considerably require Quality of Service (QoS) support. This paper proposes an optimal prority-based Call Admission Control (CAC) scheme in heterogeneous wireless networks, i.e., the generalized semi-Markov Decision Process based CAC (GCAC). Considering the limitations of the traditional Markov decision process for optimal CAC policy, we characterize the CAC problem through a GSMDP formulation that characterize s the network behaviors in the heterogeneous system more exactly. And the proposed scheme can guarantee the QoS constrains both in the physical and network layer. Numerical examples illustrate that the performance in the GCAC scheme is significantly better than that in the conventioinal GC scheme and an optimal CAC schme based on MDP.

In this paper we consider the problem of determining traffic matrices for end-to-end demands in an IP/MPLS network that supports multiple quality of service (QoS) classes. More precisely, we want to determine the set of traffic matrices Ti for each QoS class i separately. Ti contains average bandwidth levels for QoS class i for every pair of routers within the network. We propose a new method for obtaining QoS class specific traffic matrices that combines estimation and measurement methods: We take advantage of the fact that the total traffic matrix can be measured precisely in MPLS networks using either the LDP or RSVP-TE protocol. These measurements can then be used in a mathematical model to improve estimation methods - known as network tomography - that estimate QoS class specific traffic matrices from QoS class specific link utilizations. In addition to the mathematical model, we present results of the proposed method from its application in Deutsche Telekom's global IP/MPLS backbone network and we show that the estimation accuracy (mean relative error) is improved by a factor of 2.5 compared to results from network tomogravity. We investigate the structure of the estimated traffic matrices for the different QoS classes and motivate in this paper why QoS class specific traffic matrices will be essential for efficient network planning and network engineering in the future.

Call Admission Control (CAC) is one of the most important parts in Radio Resource Management of the wireless networks and it has a huge impact on the quality of service (QoS).Traditional CAC strategies focus on increasing the radio resource utility by decreasing the service blocking probabilities. In this paper, a new CAC scheme based on game theory is introduced to analyze the conflicts and rewards for different network operators. The game theoretic based CAC scheme contains two parts, utility function computation and a non-cooperative game between two networks to maximize their rewards. The proposed framework is preliminary and its objective is investigate the possibility that networks should be able to autonomously define policies for different parts of a coverage area depending on the priority of users and their requirements. In this approach, the two simulated WiMAX networks compete with each other for traffic units in overlapping coverage area and maximize their rewards. The proposed scheme is illustrated with the help of an example in which most of the traffic units lie close to one network as compared to the other network. Future work will present results of simulation studies for more detailed experiments.

Provision of Quality?of?Service (QoS) guarantees is an important and challenging issue in the design of integrated?services packet networks. Call admission control is an integral part of the challenge and is closely related to other aspects of networks such as service models, scheduling disciplines, traffic characterization and QoS specification. In this paper we provide a theoretical framework within which call admission control schemes with multiple statistical QoS guarantees can be constructed for the Generalized Processor Sharing (GPS) scheduling discipline. Using this framework, we present several admission control schemes for both session?based and class?based service models. The theoretical framework is based on recent results in the statistical analysis of the GPS scheduling discipline and the theory of effective bandwidths. Both optimal schemes and suboptimal schemes requiring less computational effort are studied under these service models. The QoS metric considered is loss probability.

In wireless environment the bandwidth resource is limited and therefore judicious use of the available resources is needed. A bandwidth efficient Call Admission Control (CAC) is proposed in this paper for quality of service (QoS) provisioning for the services defined in IEEE 802.16e mobile WiMAX standards to satisfy both bandwidth and delay guarantees to the admitted connections. The concept of adaptive bandwidth degradation is introduced to improve the bandwidth utilization (BU) of the system. The proposed CAC scheme is analyzed by Markov Chain model and performance evaluation is made in comparison with fixed step size degradation. Results show that the proposed adaptive CAC scheme has excellent BU under stressed network condition. Also the long term average revenue is calculated for different service flows and for the overall system to see the efficiency of the adaptive CAC scheme.

This paper presents a novel Call Admission Control (CAC) scheme which adopts the neural network approach, namely Minimal Resource Allocation Network (MRAN) and its extended version EMRAN. Though the current focus is on the Call Admission Control (CAC) for Asynchronous Transfer Mode (ATM) networks, the scheme is applicable to most high-speed networks. As there is a need for accurate estimation of the required bandwidth for different services, the proposed scheme can offer a simple design procedure and provide a better control in fulfilling the Quality of Service (QoS) requirements. MRAN and EMRAN are on-line learning algorithms to facilitate efficient admission control in different traffic environments. Simulation results show that the proposed CAC schemes are more efficient than the two conventional CAC approaches, the Peak Bandwidth Allocation scheme and the Cell Loss Ratio (CLR) upperbound formula scheme. The prediction precision and computational time of MRAN and EMRAN algorithms are also investigated. Both MRAN and EMRAN algorithms yield similar performance results, but the EMRAN algorithm has less computational load.

The mobile cellular systems are expected to support multiple services with guaranteed quality of service (QoS).But, the ability of wireless systems to accommodate expected growth of traffic load and broadband services is limited by available radio frequency spectrum. Call admission control (CAC) is one of the resource management functions, which regulates network access to ensure QoS provisioning. However, the decision for CAC is very challenging issue due to user mobility, limited radio spectrum, and multimedia traffic characteristics. In our previous work, we proposed a fuzzy-based CAC system and compared the performance of the proposed system with shadow cluster concept (SCC). In this work, we extend our work by considering the priority of the on-going connections. We evaluate by simulations the performance of the proposed system and compare its performance with our previous work. The performance evaluation shows that the proposed system has a good behavior in keeping the QoS of on-going connections.

The statistics of cell loss at both burst and cell levels are studied by simulation based on the configuration of the Singapore One ATM network. A virtual connection through the Singapore One network is modelled as a tandem queueing network to which mixtures of homogeneous discrete-time burst–silence traffic with different burst lengths are offered. Attention is focused on a designated traffic stream as it goes through the tandem queueing network. In the simulation, the authors have not introduced the ‘independence assumption’ between the adjacent queues, i.e. the actual tandem queueing network is used to obtain the performance measures for the designated traffic stream. Cell loss probability and high-order cell loss distributions such as cell loss-free run distribution and cell loss pattern distribution are obtained. These results provide valuable information for the estimation of end-to-end overall quality of service (QoS), design of the cell policing mechanism and flow control schemes in the ATM networks.

Next generation mobile cellular networks will have to support multimedia services. These applications, however, are very different in relation to Quality of Service (QoS) requirements, imposing restrictive requirements for this type of environment because of its limited bandwidth. This work proposes alternative Call Admission Control (CAC) schemes combined with end-to-end bandwidth reservation. This work aims to attend the different multimedia services according to their different QOS requirements, as well as reducing the rate of call losses during the procedures of handoff, prioritizing users already using the network. Simulation results show that it is possible to guarantee satisfactory levels of handoff losses, maintaining the continuity of the calls and increasing user satisfaction.

Cognitive Radio Network (CRN) is one of the emerging technologies to improve the spectrum utilization where Secondary Users (SUs) opportunistically uses the spectrum without creating significant interference to Primary Users (PUs). However, in CRN channel characteristics varies widely due to the random arrival of PUs which leads to call dropping/call blocking. Excessive call dropping reduces the quality of VoIP communication for SU's. Quality of Service (QoS) can be improved by exclusive channel reservation for SUs which involves policy formation and cost implication. To avoid the complexity, we have used sub-banding concept for Call Admission Control (CAC) scheme and utilized the scheme for VoIP applications using Adaptive Codec Switching Policy. Test bed analysis is performed to evaluate the behavior of some well known high/low bit rate codecs in CRN. Overall system performance is evaluated by using two dimensional Markov Model. Analysis shows that there is significant improvement in system capacity as probability of dropping and probability of blocking reduces. Finally Grade of Service (GoS) is considered as overall system performance metric which shows nearly 39% improvement under high SU traffic condition.

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.

This paper addresses the issue of provisioning end-to-end quality of service (QoS) for multimedia services over heterogeneous networks and introduces a parametric model by using network calculus theory for QoS class mapping between different QoS domains. Then, a QoS mapping scheme based on flow aggregation (QMS-FAG) is proposed in this paper to mitigate the information loss problem due to mapping between QoS domains with different granularity of QoS class and to provide efficient network resources utilization by considering user's quality of experience. In QMS-FAG, the QoS requirements of service flows are indicated by a unique FAG identifier, which is described in a service flow map of QoS parameters. With FAG identifier and mapping executors sitting at the border of different QoS domains, QMS-FAG allows smooth QoS class mapping between networks with different granularity of QoS class. Both numerical analysis and simulation studies are given to demonstrate the efficiency of the proposed method.

In device-to-device (D2D) communications, call admission control (CAC) scheme is a crucial problem. In D2D communications, the cellular user equipment (CUE) and D2D user equipment (DUE) pairs share the same channel resource. Hence additional interference is introduced. Meanwhile, the interference has an important impact on the system performance. In this paper, a CAC scheme based on interference analysis is proposed. First, the interference is modeled and analyzed in detail. Then based on the interference analysis, a CAC scheme is proposed. Simulation results show that D2D communications with the proposed CAC scheme can effectively improve system performance in terms of new call blocking probability and capacity. This proposed scheme can be applied to the design and optimization of D2D communications.

In the present paper, a call admission control scheme that can learn from the network environment and user behavior is developed for code division multiple access (CDMA) cellular networks that handle both voice and data services. The idea is built upon a novel learning control architecture with only a single module instead of two or three modules in adaptive critic designs (ACDs). The use of adaptive critic approach for call admission control in wireless cellular networks is new. The call admission controller can perform learning in real-time as well as in offline environments and the controller improves its performance as it gains more experience. Another important contribution in the present work is the choice of utility function for the present self-learning control approach which makes the present learning process much more efficient than existing learning control methods. The performance of our algorithm will be shown through computer simulation and compared with existing algorithms.