Prioritized admission control with load distribution over multiple controllers for scalable SDN-based mobile networks

Wireless Networks - Software-defined networking (SDN) is a promising networking paradigm towards a centralized network control plane decoupled from the forwarding plane. Owing to its intrinsic...     

Efficient silence suppression and call admission control through contention-free medium access for VoIP in WiFi networks

In view of the rapidly growing trend of migrating customers from traditional wired phones to mobile phones and then to VoIP services in the recent past, there is a tremendous demand for wireless technologies to support VoIP, specially on WiFi technologies which have already matured commercially. This has put forth great research challenges in the area of wireless VoIP. In this article we have addressed two core issues, efficient silence suppression and call admission control, in QoS provisioning for VoIP services in WiFi networks. In this connection we present a QoS-aware wireless MAC protocol called hybrid contention-free access (H-CFA) and a VoIP call admission control technique called the traffic stream admission control (TS-AC) algorithm. The H-CFA protocol is based on a novel idea that combines two contention-free wireless medium access approaches, round-robin polling and TDMA-like time slot assignment, and provides substantial multiplexing capacity gain through silence suppression of voice calls. The TS-AC algorithm ensures efficient admission control for consistent delay bound guarantees and further maximizes the capacity through exploiting the voice characteristic so that it can tolerate some level of non-consecutive packet loss. We expose the benefits of our schemes through numerical results obtained from simulations.     

Call admission control for capacity-varying networks

Many networks, such as Non-Geostationary Orbit Satellite (NGOS) networks and networks providing multi-priority service using advance reservations, have capacities which vary over time for some or all types of calls carried on these networks. For connection-oriented networks, Call Admission Control (CAC) policies which only use current capacity information may lead to excessive and intolerable dropping of admitted calls whenever the network capacity decreases. Thus, novel CAC policies are required for these networks. Three such CAC policies are discussed, two for calls with exponentially distributed call holding times and one for calls whose holding time distributions have Increasing Failure Rate (IFR) functions. The Admission Limit Curve (ALC) is discussed and shown to be a constraint limiting the conditions under which any causal CAC policy may admit calls and still meet call dropping guarantees on an individual call basis. We demonstrate how these CAC policies and ALC represent progressive steps in developing optimal CAC policies for calls with exponentially distributed call holding times, and extend this process to the more general case of calls with IFR call holding times.     

Utility-based admission control for mobile WiMAX networks

This paper presents a novel utility-based connection admission control (CAC) scheme for IEEE 802.16e broadband wireless access networks. We develop specific utility functions for real-time and non-real-time services coupled with a handover process. Given these utility functions we characterize the network utility with respect to the allocated bandwidth, and further propose a CAC algorithm which admits a connection that conducts to the greatest utility so as to maximize the total resource utilization. The simulation results demonstrate the effectiveness of the proposed CAC algorithm in terms of network utility.     

Contention-aware admission control for ad hoc networks

An admission control algorithm must coordinate between flows to provide guarantees about how the medium is shared. In wired networks, nodes can monitor the medium to see how much bandwidth is being used. However, in ad hoc networks, communication from one node may consume the bandwidth of neighboring nodes. Therefore, the bandwidth consumption of flows and the available resources to a node are not local concepts, but related to the neighboring nodes in carrier-sensing range. Current solutions do not address how to perform admission control in such an environment so that the admitted flows in the network do not exceed network capacity. In this paper, we present a scalable and efficient admission control framework - contention-aware admission control protocol (CACP) - to support QoS in ad hoc networks. We present several options for the design of CACP and compare the performance of these options using both mathematical analysis and simulation results. We also demonstrate the effectiveness of CACP compared to existing approaches through extensive simulations.     

Iterative power control based admission control for wireless networks

This paper studies transmission power control algorithms for cellular networks. One of the challenges in commonly used iterative mechanisms to achieve this is to identify if the iteration will converge since convergence indicates feasibility of transmit power allocation under prevailing network conditions. The convergence criterion should also be simple to calculate given the time constraints in a real-time wireless network. Towards this goal, this paper derives simple sufficient conditions for convergence of an iterative power control algorithm using existing bounds from matrix theory. With the help of suitable numerical examples, it is shown that the allocated transmit powers of the nodes converge when sufficient conditions are satisfied, and diverge when they are not satisfied. This forms the basis for an efficient link data-rate based admission control mechanism for wireless networks. The mechanism considers parameters such as signal strength requirement, link datarate requirement, and number of nodes in the system. Simulation based analysis shows that existing links are able to maintain their desired datarates despite the addition of new wireless links.     

MaxNet: a congestion control architecture for scalable networks

MaxNet is a distributed congestion control architecture. This paper analyzes the stability properties of MaxNet. We show that MaxNet is stable for networks with arbitrary delays, numbers of sources, capacities, and topologies. Unlike existing proposals, MaxNet does not need to estimate the number of bottleneck links on the end-to-end path to achieve these scaling properties.     

Flow admission control for multi-channel multi-radio wireless networks

Providing Quality of Service (QoS) is a major challenge in wireless networks. In this paper we propose a distributed call admission control protocol (DCAC) to do both bandwidth and delay guaranteed call admission for multihop wireless mesh backbone networks, by exploiting the multi-channel multi-radio (mc-mr) feature. We propose a novel routing metric for route setup, and present an efficient distributed algorithm for link reservation that satisfies the required bandwidth and reduces the delay by a local scheduling that minimizes one hop delay. To the best of our knowledge, this is the first distributed protocol that embeds mc-mr feature in Time Division Medium Access (TDMA) to do QoS call admission in wireless backbone networks. Extensive simulation studies show that our protocol significantly improves network performance on supporting QoS sessions compared with some widely used protocols.     

Connection admission control for mobile multiple-class personalcommunications networks

In this paper, we investigate the connection admission control problem in mobile personal communications networks. Since user mobility and multimedia traffic are important factors in personal communications networks, in contrast to other studies on this aspect which either focused on only single-class call connections or ignored user mobility, our study directly addresses the connection admission control for multiple-class calls with user mobility. A generic class of coordinate-convex admission control policies is considered. An efficient numerical method is proposed to derive the connection-level quality of service (QoS), and is verified with computer simulation results. The results obtained show that, besides offered load, user mobility can have a great impact on the connection-level QoS. The proposed analysis may be employed in a network design tool for studying the admission control policy and for selecting system parameters to satisfy the required connection-level QoS     

Effective bandwidth-based admission control for multiservice CDMAcellular networks

We develop product form traffic models for single- and multiple-cell code-division multiple-access (CDMA) networks with multiple classes of mobile subscribers. The key feature of this development is the specification of a flexible call admission control procedure that details the numbers of mobiles of each class in each cell that the system operator should allow in order to maintain an acceptable quality of service. Effective bandwidth techniques from the analysis of statistical multiplexing at an asynchronous transfer mode (ATM) based broadband integrated services digital network (ISDN) link are used to give performance guarantees that overcome the variability in interference levels characteristic of CDMA cellular networks. The result is an admissible region bounded by a finite number of hyperplanes and a simple and efficient call admission policy. The CDMA mobile network, operating within the admissible region described, has a very similar form to a circuit-switched network operating with fixed routing. This similarity allows the existing traffic modeling techniques and network management strategies for general loss networks to be applied to CDMA mobile cellular networks. In particular, with standard assumptions on the call arrival processes and holding times, the stationary state distribution has a product form on the truncated state space defined by the call admission strategy     

基于优先级的IEEE 802.16中VoIP弹性接纳控制算法

通过分析IEEE 802.16关于VoIP(voice over IP)的传输规范和服务质量保证机制,指出了区分VoIP的优先级和VoIP要求弹性QoS的性质对VoIP接纳控制有着极其重要的意义,提出了VoIP接纳控制的弹性准则和优先级准则。在运用有效带宽理论确定了VoIP传输所需最小带宽的基础上,提出了基于优先级的弹性接纳控制算法,并以概率强度因子对算法进行了优化。该算法能够根据剩余资源动态地调整接纳强度和策略,对不同优先级的VoIP表现出不同的接纳特性,资源紧张时合理限制低优先级VoIP的接纳。为评价算法性能,通过Markov模型对建议算法的拒绝率进行分析,并在PMP(point-to-multipoint)模式下与新呼叫限制算法进行了对比仿真,结果表明本算法在表现出更高接纳能力的同时具有更低的新连接阻塞率和切换连接掉线率。     

A service-oriented admission control strategy for class-based IP networks

The clear trend toward the integration of current and emerging applications and services in the Internet launches new demands on service deployment and management. Distributed service-oriented traffic control mechanisms, operating with minimum impact on network performance, assume a crucial role as regards controlling services quality and network resources transparently and efficiently. In this paper, we describe and specify a lightweight distributed admission control (AC) model based on per-class monitoring feedback for ensuring the quality of distinct service levels in multiclass and multidomain environments. The model design, covering explicit and implicit AC, exhibits relevant properties that allow managing quality of service (QoS) and service-level specifications (SLSs) in multiservice IP networks in a flexible and scalable manner. These properties, stemming from the way service-dependent AC and on-line service performance monitoring are proposed and articulated in the model’s architecture and operation, allow a self-adaptive service and resource management, while abstracting from network core complexity and heterogeneity. A proof of concept is provided to illustrate the AC criteria ability in satisfying multiple service class commitments efficiently. The obtained results show that the self-adaptive behavior inherent to on-line measurement-based service management, combined with the established AC rules, is effective in controlling each class QoS and SLS commitments consistently.     

Opportunistic call admission control for wireless broadband cognitive networks

Wireless Broadband Cognitive Networks (WBCN) are new trend to better utilization of spectrum and resources. However, in multiservice WBCN networks, call admission control (CAC) is a challenging point to effectively control different traffic loads and prevent the network from being overloaded and thus provide promised quality of service. In this paper, we propose a CAC framework and formulate it as an optimization problem, where the demands of both WBCN service providers and cognitive subscribers are taken into account. To solve the optimization problem, we developed an opportunistic multivariate CAC algorithm based on a joint optimization of utility, weighted fairness, and greedy revenue algorithms. Extensive simulation results show that, the proposed call admission control framework can meet the expectations of both service providers and subscribers in wireless broadband cognitive networks.     

An efficient admission control mechanism for optical burst-switched networks

This article proposes the load-level-based admission control (LLAC) mechanism in order to provide service differentiation for optical burst-switched networks. The LLAC mechanism admits bursts of a given service class according to the network load and a class-associated parameter. Based on this parameter, called load level, the proposed mechanism differentiates the burst blocking probability experienced by each service class. We develop an analytical model for the proposed mechanism and evaluate its performance for different configurations through mathematical analysis. The results show that the load-level-based mechanism reduces the blocking probability of high-priority bursts by two orders of magnitude or more depending on the analyzed scenario. In addition, compared to other similar mechanisms, the load-level-based mechanism effectively differentiates the services in all analyzed configurations, requires less states in optical burst switching (OBS) nodes, and does not suffer from priority inversion.

A measurement-based admission control algorithm for integratedservice packet networks

Many designs for integrated services networks offer a bounded delay packet delivery service to support real-time applications. To provide a bounded delay service, networks must use admission control to regulate their load. Previous work on admission control mainly focused on algorithms that compute the worst case theoretical queueing delay to guarantee an absolute delay bound for all packets. In this paper, we describe a measurement-based admission control algorithm (ACA) for predictive service, which allows occasional delay violations. We have tested our algorithm through simulations on a wide variety of network topologies and driven with various source models, including some that exhibit long-range dependence, both in themselves and in their aggregation. Our simulation results suggest that measurement-based approach combined with the relaxed service commitment of predictive service enables us to achieve a high level of network utilization while still reliably meeting the delay bound     

Adaptive connection admission control for differentiated services access networks

In our earlier work, we have proposed some modifications for the bandwidth broker framework. With our modifications, it is possible to use measurement-based admission control in addition to the more traditional parameter-based admission control. Moreover, we have presented a new flexible admission control scheme that has proven to be very efficient in terms of bottleneck link utilization. Two problems, however, have arisen: the use of scheduling weights in admission control and bursty connection arrivals. In this paper, we present that the former one can be dealt with the use of adaptive scheduling weights, while the latter one can be fought with adaptive reservation limits. The proposed new algorithms are validated through simulations and their performance is compared against the nonadaptive basic scheme.     

Dynamic call admission control in ATM networks

The authors present dynamic call admission control using the distribution of the number of cells arriving during the fixed interval. This distribution is estimated from the measured number of cells arriving at the output buffer during the fixed interval and traffic parameters specified by users. Call acceptance is decided on the basis of online evaluation of the upper bound of cell loss probability, derived from the estimated distribution of the number of calls arriving. QOS (quality of service) standards can be guaranteed using this control when there is no estimation error. The control mechanism is effective when the number of call classes is large. It tolerates loose bandwidth enforcement and loose policing control, and dispenses with modeling of the arrival processes. Numerical examples demonstrate the effectiveness of this control, and implementation is also discussed     

Call admission control in wireless multimedia networks

Call admission control (CAC) is a mechanism used in networks to administer quality of service (QoS). Whereas the CAC problem in time-division multiple access (TDMA)-based cellular networks is simply related to the number of physical channels available in the network, it is strongly related to the physical layer performance in code-division multiple access (CDMA) networks since the multi-access interference in them is a function of the number of users and is a limiting factor in ensuring QoS. In this article, the CAC issues in multimedia DS-CDMA systems are reviewed by illustrating the basic principles underlying various schemes that have been proposed progressively from the simplest to the complex. The article also introduces SIR as a measure of QoS and describes the relatively simple schemes to administer CAC. The expression for SIR resulting from linear minimum mean-squared error processing is also presented. This article illustrates how CAC for multiple class service can be casted into an optimality framework and then discuss the recent work addressing self-similar multiple access interference.     

Edge distributed admission control in MPLS networks

This paper proposes a novel approach for admission control in traffic engineered data networks, which applies at network edges by means of dynamic thresholds evaluated on the basis of network status. The proposed method is described with focus on IP/MPLS networks, but it actually applies as well to a variety of scenarios, such as ATM or generalized MPLS. The proposed solution allows more efficient usage of network resources, especially at medium/high load, and increased robustness of the network.     

Proactive load balancing with admission control for heterogeneous overlay networks

The next generation wireless networks will be the coexistence of heterogeneous wireless technologies. Balancing the traffic load among different networks can effectively utilize the overall radio resources in the system. In this paper, we propose an efficient load balancing scheme for the heterogeneous overlay systems, which is applied in the call admission control process. If the available network(s) cannot provide enough resource for the request call without degrading the quality‐of‐service (QoS) obtained by the ongoing calls, the system will perform load balancing operations first by initiating vertical handoffs among networks in order to create more rooms for the request call. The load balancing algorithm is to minimize the variance between the network utilizations of the entire system, which can be formulated as a quadratic binary programming problem. Simulation results show that the proposed scheme can admit more calls into the system compared with the other three reference schemes and then improve the overall throughput. Meanwhile, the scheme can keep the networks working in effective states and provide a better QoS support for users. Copyright © 2011 John Wiley & Sons, Ltd.