Admission Control Mechanism Research Articles

Adaptive Quality of Service Provisioning in IEEE 802.11 Wireless Local Access Network

–This paper provides a cross-layer Quality of Service (QoS) provisioning scheme for IEEE 802.11 Wireless Local Area Network (WLAN). Specifically, we develop a new scheduling algorithm in link layer and a call admission control mechanism in network layer to support multimedia services. Instead of using a single coordination function in link layer, we adopt polling scheme to support real-time (RT) services while using EDCF contention-based function for nonreal- time (NRT) services, based on wireless channel condition and service fairness. The proposed polling algorithms search idle system time and use it to reduce average packet loss of RT variable-bit-rate (VBR) services, as well as satisfying transmission delay and bandwidth requirements of all RT services. The admission control mechanism provides long-term quality for both RT and NRT services by ensuring low average packet loss ratio for RT services and acceptable minimum throughput for NRT services. Service priority and fairness are achieved by assigning VBR bursts higher priority for resource allocation based on their weighting values. Fairness is also implemented by reserving resource for NRT to avoid possible starvation. Rate allocation for VBR connections are adaptively adjusted with sliding window measurement. Detailed analysis is given by taking into account several key statistical factors, such as service traffic model, the ratio between the polling period and the contention period (CP), burst generation probabilities, and wireless propagation model. Performance is evaluated through OPNET simulation. Both numerical and simulation results demonstrate that our proposed joint scheme is effective in terms of both system resource utilization and QoS provisioning.

Residual resources aware distributed admission control mechanism in mobile multi-hop network

Without considering current residual resources of the medium, nodes in mobile ad hoc networks (MANETs) admit the data flow arbitrarily, and the quality of service (QoS) of the data flows deteriorates. To release the contending on the resources induced by the overloaded flows, the admission control mechanism can effectively keep the balance between injected data flows and network capacity, and it is viewed as the most important technology in MANET. A novel distributed residual resources aware admission control mechanism is proposed in this paper, where the residual resources and the service rate are studied thoroughly. Considering the medium utilization, frame retransmission and backoff procedure, the passive method is applied to predict the residual resources, and the binomial distribution is utilized to model the medium status; moreover, based on the cooperation between the source node and intermediate nodes, the path meeting the resource demand is probed across the network, and the flows are rejected while the residual resources cannot meet its demand. Results show that the network load can be constrained by our proposed admission control mechanism, and the QoS of the data flows can be guaranteed effectively.

Enhanced QoS by Service Differentiation in MAC-Layer for WLAN

IEEE 802.11 wireless Local Area Network (WLAN) have become more and more popular due to easy to deployment and lower cost. It can only provide a best effort service and do not have quality of service (QoS) support for real time (RT) traffic. The IEEE Task Group has been proposed a new standard IEEE 802.11e[1] to address this MAC-layer QoS issue of WLAN. In this paper we proposed a new service differentiation mechanism for admission control in the MAC layer of WLAN for enhancing the QoS.

Performance Evaluation of Traffic Meters: Token Bucket Marker and Two Rate Three Color Marker (trTCM) QoS Admission Control

The key role of traffic meter for quality of service admission control internet is to control the amount of traffic injected into the differentiated service network so that congestion can be avoided to the barest minimum in order to meet certain performance requirements. This paper presents performance evaluation and analysis of two traffic meters: token bucket marker (TBM) and two rate three color marker (srTCM) QoS admission control using user datagram protocol (UDP) and transport control protocol (TCP) traffic agents. The performance measures used for the evaluation and analysis were throughput, fairness and losses. An in-depth study of the aforementioned admission control mechanisms that can enforce service level agreement (SLA) was carried out in order to suggest to the IETF which of the proposed meter would best provide QoS to users. A network simulator, ns-2.35 to be precise, was used to run the simulation to showcase the analysis and evaluation of the traffic meters. For TCP traffic agent, the analysis based on fairness, throughput and losses showed that the two rate three color marker with percentages 13.15 for fairness, 98.85 for throughput and 0.14 for losses was better in all ramification than the token bucket marker traffic meter with percentages of 12.50 for fairness, 96.66 for throughput and 1.34 losses. For UDP traffic, reverse was the case. The token bucker marker traffic meter with 24.54% of fairness, 62.69% of throughput and 37.37% of losses was better than the two rate three color marker traffic meter with 13.99% of fairness, 21.10% of throughput and 78.99% of losses.

Quality of Service Analysis and Queuing Performance Modeling of Orthogonal Frequency Division Multiple Access Based IEEE 802.16/WiMAX System

The authors present a problem of queuing theoretic performance modeling and analysis of Orthogonal Frequency Division Multiple Access (OFDMA) under broadband wireless networks. They consider a single-cell WiMAX environment in which the base station allocates sub channels to the subscriber stations in its coverage area. The sub channels allocated to a subscriber station are shared by multiple connections at that subscriber station. To ensure the Quality of Service (QoS) performances, a Connection Admission Control (CAC) mechanism is considered at a subscriber station. A queuing analytical framework for these admission control mechanisms is presented considering OFDMA-based transmission at the physical layer and based on the queuing model; both the connection-level and packet-level performances are studied and compared with their analogues in the case without CAC. The connection arrival is modeled by a Poisson process and the packet arrival for a connection by a Markov Modulated Poisson Process (MMPP). Several performance measures, namely connection blocking probability, average number of ongoing connections, average queue length, packet dropping probability, queue throughput and average packet delay, are then derived and quantified.

FAST: Fuzzy Decision-Based Resource Admission Control Mechanism for MANETs

Mobile Ad Hoc Networks (MANETs) have inherently dynamic topologies and heterogeneous network environments. Due to the distributed, multi-hop nature of these networks, as well as limited network resource, wireless capacity and random mobility of nodes, Quality of Service (QoS) provisioning faces severe challenges, especially in multicast scenarios. Resource admission control is one of the most effective methods for resource utilization and QoS guaranteed. In this paper, we combine resource admission control technologies and intelligent methods, propose a fuzzy decision-based resource admission control mechanism for MANETs (FAST), which can fast respond to dynamic topology changes and unstable link status. FAST also supports multicast and destination heterogeneity. Users can choose multiple evaluation parameters with different weights of services in fuzzy decision. Simulation results have proved the efficiency of the mechanism.

On the quality of VoIP with DCCP for satellite communications

SUMMARYWe present experimental results for the performance of selected voice codecs using Datagram Congestion Control Protocol (DCCP) with CCID4 congestion control over a satellite link. We evaluate the performance of both constant and variable data rate speech codecs for a number of simultaneous calls using the ITU E‐model. We analyse the sources of packet losses and additionally analyse the effect of jitter, which is one of the crucial parameters contributing to Voice over IP (VoIP) quality and has, to the best of our knowledge, not been considered previously in the published DCCP performance results. We propose modifications to the CCID4 algorithm and demonstrate how these improve the VoIP performance, without the need for additional link information other than what is already monitored by CCID4. We also demonstrate the fairness of the proposed modifications to other flows. Although the recently adopted changes to TCP‐Friendly Rate Control specification alleviate some of the performance issues for VoIP on satellite links, we argue that the characteristics of commercial satellite links necessitate consideration of further improvements. We identify the additional benefit of DCCP when used in VoIP admission control mechanisms and draw conclusions about the advantages and disadvantages of the proposed DCCP/CCID4 congestion control mechanism for use with VoIP applications. Copyright © 2012 John Wiley & Sons, Ltd.

Delay-Constrained Admission and Bandwidth Allocation for Long-Reach EPON

Next generation Passive Optical Network (PON) technology has been evolving to consolidate the metro and access networks in order to offer enhanced capacity, high split ratio and reduced deployment cost per subscriber. However, transmission of the signals to long distances up to 100km leads to increased propagation delay whereas high split ratio may lead to long cycle times resulting in large queue occupancies and long packet delays. In this article, we present a delay-constrained admission control mechanism and adapt this scheme to our previously proposed bandwidth allocation technique, namely Periodic GATE Optimization (PGO). We call this new scheme Delay-Constrained Periodic GATE Optimization (DC-PGO). DC-PGO is designed to run for multiple service classes as it inherits the advantages of PGO by periodically building and solving an ILP formula- tion at the OLT in order to obtain the appropriate credit values for the overloaded ONUs. At the ONU side, DC- PGO runs an admission control scheme before pushing the arriving packets in the sub-queues. The admission control scheme uses statistical information consisting of the local data at the ONU and the previously received GATE messages from the OLT. Through simulations, we show that DC-PGO enhances the performance of multi-threaded polling in long- reach Ethernet PON when packets of differentiated service classes arrive with pre-specified delay requirements. Index Terms—Dynamic bandwidth allocation, Ethernet PON, long-reach passive optical networks, multi-threaded polling

Packet Scheduling and Admission Control for QoS Provisioning in Integrated IEEE 802.11e and IEEE 802.16 Mesh Mode

The IEEE 802.11e standard defines the HCF, which can improve the QoS support in 802.11 networks. On the other hand, the IEEE 802.16 is a metropolitan area technology, which can provide QoS per each connection. However, its mesh mode loosely supports QoS per each packet. These two techniques may be integrated to cover a typical urban area. This integration should be such that the minimum QoS requirements of traffic streams traversing the mesh structure of 802.16 can be provided. For this purpose, a new framework for integration of these two standards is presented in this research. It includes a scheduling algorithm and an admission control mechanism for uplink. As such, the minimum QoS requirements of traffic streams are provisioned by introducing a heuristic scheduling algorithm. Besides, an admission control procedure is used to provide fairness among the traffic types as well. The scheduling algorithm for downlink traffic is also provided. We evaluate this framework by simulating a compound network under different traffic conditions and investigate its performance against increasing the number of mobile terminals.

A Survey for Load Balancing in Mobile WiMAX Networks

Mobile Worldwide Interoperability for Microwave Access (Mobile WiMAX) is a wireless access technology based on IEEE 802.16e standard. Mobile WiMAX supports mobility, high utilization of radio resources, beneficial Quality of Service (QoS) framework, and flexible centralized scheduling, which are offered by connection oriented MAC layer. Due to the architecture of MAC layer in mobile WiMAX, admission control, packet scheduling, handover, and load balancing mechanisms can be implemented in the MAC layer by vendors. In this paper, we explain two main features in MAC layer of Mobile WiMAX networks; handover and load balancing. Additionally, we investigate load balancing algorithms suggested in wireless and WiMAX networks to find out appropriate way of load balancing in mobile WiMAX networks.

Hybrid Adaptive Call Admission Control Mechanism for Ensuring QoS in 3GPP: LTE Networks

Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) system is targeted to efficiently guarantee the quality of service (QoS) of services such as audio/video streaming, gaming and Voice over IP (VoIP). So the system resource allocation should obtain the multiuser diversity gain making full use of the channel condition, and take the quality of service (QoS) of different services into account. Due to the heavy user’s space and limited Resource Block (RBs), it is infeasible to guarantee all ongoing users' QoS. Then, some call are blocked and lost. The proposed method reduces the handoff blocking probability in LTE wireless networks. Hybrid Adaptive call admission control scheme performs the QoS operation based on the priority at the time of call admission. This method reduces new call blocking probability.

Building Web services middleware with predictable execution times

Predictability of execution has seldom been considered important in the design of Web services middleware. However, with the paradigm shift brought by cloud computing and with offerings of Platforms and Infrastructure as services, execution level predictability is mandating an increased importance. Existing Web services middleware are optimised for throughput with unconditional acceptance of requests and execution in a best-effort manner. While achieving perceived levels of throughput, they also result in highly unpredictable execution times. This paper presents a generic set of guidelines, algorithms and software engineering techniques that enable service execution to complete within a given deadline. The proposed algorithms accept requests for execution based on their laxity and executes them to meet requested deadlines. An introduced admission control mechanism results in a large range of laxities, enabling more requests to be scheduled together by phasing out their execution. Specialised development libraries and operating systems empower them with increased control over execution. Two widely used Web services middleware products were enhanced using these techniques. The two systems are compared with their unmodified versions to measure the predictability gain achieved. Empirical evidence confirms that the enhancements made enable these systems to achieve more than 90% of the deadlines under any type of traffic, while the unmodified versions achieve less than 10% of the deadlines in high traffic conditions. Predictability of execution achieved through these techniques, would open up new application areas such as industrial control systems, avionics, robotics and financial trading systems to the use of Web services as a middleware platform.

Quality of Service over Heterogeneous Network with MPLS Backbone

Internet growth in recent years has encouraged many new applications to be provided for the end user. However, providing and maintaining high quality of service for these new applications is a challenging matter that is getting the attention of many many researchers nowadays. The QoS challenge is emanating from the diversity of these applications, in term of bandwidth requirements and high sensitivity to delay and delay variation. Three main architectures were proposed by IETF in an effort to make the IP QoS a reality. They are integrated services (Intserv), differentiated services (DiffServ) and multiprotocol label switching (MPLS). Sometimes perceived as competitor, these architectures are in fact complementary developments that approach the QoS challenge from different network perspectives. Thus these approaches can work together in a manner that provides a global QoS within Heterogeneous network. This paper aims to propose and discusses an improved admission control mechanism in order to achieve a global QoS in the HN Network. The proposed mechanism uses MPLS-TE tunnels at the core of Heterogeneous networks to maintain QoS for inter-domain flows and applications.

Admission Control for QoS Provision in Wireless Mesh Networks

This work presents an admission control mechanism for multi-hop wireless mesh networks based on the IEEE 802.11e standard and the OLSR routing protocol. This mechanism, called CAC-OLSR, aims at ensuring that traffic flows with quality of service (QoS) requirements are only admitted in the mesh network if it has available resources in order to provide flow requirements. In addition, QoS requirements of previously admitted traffic flows cannot be violated. The proposal was evaluated with NS-2 simulations.

Adjustable Two-Tier Cache for IPTV Based on Segmented Streaming

Internet protocol TV (IPTV) is a promising Internet killer application, which integrates video, voice, and data onto a single IP network, and offers viewers an innovative set of choices and control over their TV content. To provide high-quality IPTV services, an effective strategy is based on caching. This work proposes a segment-based two-tier caching approach, which divides each video into multiple segments to be cached. This approach also partitions the cache space into two layers, where the first layer mainly caches to-be-played segments and the second layer saves possibly played segments. As the segment access becomes frequent, the proposed approach enlarges the first layer and reduces the second layer, and vice versa. Because requested segments may not be accessed frequently, this work further designs an admission control mechanism to determine whether an incoming segment should be cached or not. The cache architecture takes forward/stop playback into account and may replace the unused segments under the interrupted playback. Finally, we conduct comprehensive simulation experiments to evaluate the performance of the proposed approach. The results show that our approach can yield higher hit ratio than previous work under various environmental parameters.

Use of Leftover Service Curve in Admission Control in Ad Hoc Networks

Network calculus approach, with its service curve formalism, proves to be very useful in the analysis of effectiveness of admission control mechanisms and scheduling algorithms used in networks. It enables a transparent coordination of bandwidth assignments, and other resources provided at network nodes. To this end, the so-called ε-effective service curve was devised for ad hoc networks. We show that it is a special kind of the leftover service curve, exploited in the case of presence of cross traffic at nodes. New expressions are derived here. Moreover, the results of simulations for ad hoc networks, carried out with the use of NS3 simulator, are presented. Further, influence of the presence of cross traffic at nodes on servicing the through traffic is analyzed.

Improving quality of experience in wireless VoIP through novel call scheduling

In the last few years we have experienced a dramatic increase in the use of IP networks for voice applications (VoIP) over wireless networks due to increased bandwidth availability and enhanced device capabilities. Since demand often exceeds available capacity, Call Admission Control mechanisms are in place to prevent the uncontrolled usage of bandwidth. Through the use of an intermediary gateway, VoIP calls are in many cases terminated to a normal landline or cellphone; the capacity of such a gateway is also a finite resource since the number of users can vary significantly as many are mobile. In this article we propose an enhanced scheme that aims to manage access to the lines available so that they are used in a fair manner and utilized to the highest degree possible. This management is facilitated by enhancing a proxy implementation with a number of call scheduling policies. The ability to satisfy pending call requests as soon as lines become available, results in increased user service satisfaction. Moreover, it increases line utilization which is crucial from an economic viewpoint. The ultimate goal is to improve Quality of Experience which is deemed as highly important especially considering that wireless network users experience opportunistic and intermittent connectivity.

Dynamic call and connection admission control in automatically switched optical network for grid computing applications

In recent years, Grid computing applications are becoming more and more important to the scientific and business communities and are likely to open to the consumer market and widely develop in the near future, which is a great challenge brought by the potentially large number of Grid users (perhaps millions) and high frequency of their job requests. Automatically switched optical network (ASON), which is a promising high capacity intelligent transport network infrastructure, has been already deployed in the world and regarded as a promising solution to foster the expansion of Grid computing from local area networks to wide area networks. However, by theoretical analysis and simulative evaluation of Grid job blocking in the distributed call and connection setup process of ASON, this paper verifies that ASON and the conventional admission control mechanism confront a problem in supporting future large-scale Grid computing. In order to address this issue, a novel dynamic call and connection admission control (DCCAC) scheme is proposed to improve the network performance and guarantee quality of service (QoS) of Grid applications. This scheme is applicable with complete network information, no network information and partial network information. Numerical results show that the DCCAC scheme can improve the efficiency of the network to a great extent. Moreover, all the analysis and algorithms in this paper are based on ITU-T ASON recommendations, which make the DCCAC scheme more applicable in network engineering for future Grid computing.

Dynamic Preemption Call Admission Control Scheme Based on Markov Decision Process in Traffic Groomed Optical Networks

In optical grooming networks, the capacity fairness issue can be resolved by utilizing a call admission control (CAC) mechanism. Existing CAC schemes are generally based on one of four different techniques, namely, static bandwidth reservation, static threshold setting, mathematical statistics, and Markov decision processing without buffer implementation (NB). However, irrespective of the technique used, a trade-off exists between the network fairness and the network throughput. In our previous work, a conditional-preemption CAC (CP-CAC) mechanism was proposed to increase the network throughput while simultaneously maintaining the fairness. However, a CP-CAC mechanism considers only the blocking probability at particular instants of preemption. This paper proposes the use of a dynamic-preemption call admission control scheme (DP-CAC) to decide whether or not to preempt existing requests based on the optimal policy derived from a Markov decision process. Similar to CP-CAC, the DP-CAC method is also based on a dynamic threshold setting concept and is implemented using a single connection buffer and an associated set of virtual indicators. The simulation results show that compared to the CP-CAC mechanism, the proposed DP-CAC further improves the network throughput without sacrificing the fairness. Additionally, the average waiting time induced by the buffer implementation for DP-CAC is just 0.23 time units shorter compared to 0.25 for CP-CAC. Finally, it is shown that the proposed method also ensures fairness in a variety of common network topologies including 6 × 6mesh-torus, NSF, and Cost239.

An Efficient Method for Proportional Differentiated Admission Control Implementation

The admission control mechanism inspired in the framework of proportional differentiated services has been investigated. The mechanism provides a predictable and controllable network service for real-time traffic in terms of blocking probability. Implementation of proportional differentiated admission control is a complicated computational problem. Previously, asymptotic assumptions have been used to simplify the problem, but it is unpractical for real-world applications. We improve previous solutions of the problem and offer an efficient nonasymptotic method for implementation of proportional differentiated admission control.