Connection Admission Control Algorithm Research Articles

Admission Control Policy for Virtual Partitioning with Non-Real-Time Service Pause

For this study, virtual partitioning (VP) of a non-real- time (NRT) service paused for connection admission control (CAC) in a cellular network is applied and evaluated. The mobility scenario of the occurring handoff is described for a cellular network, and the corresponding handoff rate equations are derived. This study proposes the CAC algorithms for connection requests that consider the real-time (RT) service, NRT service, and both new and handoff users. A suitable VP with NRT service pause rules have been defined for RT and NRT connections. The priorities of a CAC for each type of handoff user differ. The unused capacity in an under-loaded RT group can be utilized through NRT connections if necessary. RT connections receive guaranteed access and a better QoS. An RT connection can pause an NRT connection when the NRT group is overloaded. The results of this study demonstrate the performance of a cellular system in terms of the probability of blocking new connection requests and dropping handoff connection requests. The numerical results show a significant performance improvement when the NRT service is paused.

Performance Analysis of a Connection Admission Scheme for Future Networks

Future networks are to deliver any-traffic, anytime, anywhere with full quality of service (QoS) guarantees. They will evolve from typical heterogeneous networks (HetNets) into dense, organic, and irregular heterogeneous networks called DenseNets. They will be complex and face additional challenges of heterogeneity in many design dimensions like different radio access technologies (RAT's) shrinking in structure. Radio Resource Management (RRM) is one of the key challenges in providing for QoS for these networks. Connection Admission Control (CAC) scheme and intelligent scheduling techniques are employed on the links for RRM. In this paper a CAC scheme is developed that features multiple traffic classes, multiple admission parameters at both packet and connection level. The CAC scheme uses both signal to interference ratio (SIR) and delay as admission parameters since the single parameter based CAC algorithm is not adequate for the emerging traffic classes. The performance analysis of the model features Batch Markovian Arrival Process (BMAP) traffic, a better representative of the future traffic characteristics than the traditional Poisson traffic. A simple approximate Markovian analytical model is developed and used to analyze the complex network. The developed model with more admission parameters outperforms those with less admission control parameters for future networks traffic.

Throughput Enhancement for Better QoS in WCDMA Networks

WCDMA is interference limited multiple access technique and mainly used for transmission of high data rate in the 3rd generation cellular and mobile networks. In conventional Call Admission Control (CAC) techniques, when a new call admit in the system to get admission, it checks whether the call is admitted or not on the basis of signal to interference ratio (SIR) and transmission power in the network. If the call is accepted it will create some interference to the ongoing calls during data transmission and reception. This new interference would degrade the performance of ongoing calls; hence the proper Resource Allocation with Call Admission Control in the network is very essential to maintain the communication with guaranteed quality of service (QoS). This paper proposes a novel approach for Resource Allocation with connection admission control (RA-CAC) to maintain present and future target throughput for entire duration of the system which is mainly based on the utility function. The simulation result shows that the proposed Throughput Based Resource Allocation Scheme with connection admission control algorithm can significantly increase packet delivery ratio with less delay and higher throughput.

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.

Dynamic admission control and bandwidth reservation for IEEE 802.16e mobile WiMAX networks

The article presents a dynamic connection admission control (CAC) and bandwidth reservation (BR) scheme for IEEE 802.16e Broadband Wireless Access networks to simultaneously improve the utilization efficiency of network resources and guarantee QoS for admitted connections. The proposed CAC algorithm dynamically determines the admission criteria according to network loads and adopts an adaptive QoS strategy to improve the utilization efficiency of network resources. After new or handoff connections enter the networks based on current admission criteria, the proposed adaptive BR scheme adjusts the amount of reserved bandwidth for handoffs according to the arrival distributions of new and handoff connections in order to increase the admission opportunities of new connections and provide handoff QoS as well. We conduct simulations to compare the performance of our proposed CAC algorithm and BR scheme with that of other approaches. The results illustrate that our approach can effectively improve the network efficiency in terms of granting more connections by as large as about 22% in comparison with other schemes, and can also guarantee adaptive QoS for admitted new and handoff connections.

A self-adapting connection admission control solution for mobile WiMAX: Enabling dynamic switching of admission control algorithms based on predominant network usage profiles

WiMAX is a connection-oriented wireless network that provides QoS in metropolitan broadband communications. One important component in WiMAX QoS provisioning and management is the Connection Admission Control (CAC), which must be aware of the network conditions (e.g., user traffic demands and physical aspects). In our research, we define the association between a particular user traffic demand and a specific physical condition as a network usage profile. State-of-the-art proposals focus on optimizing CAC algorithms considering a single network usage profile; the adaptation of CAC algorithms when the predominant network usage profile changes is partially or fully neglected. In this article, we introduce a self-adapting CAC solution that, using a library of CAC algorithms, is able to switch the running algorithm according to the current network usage profile. The evaluation results, obtained through simulations, demonstrate that our self-adapting CAC solution is able to detect the changes on the predominant network usage profile. In addition, the results show how much different profiles can impact on the efficiency of CAC algorithms, thus confirming the need of switching the running CAC algorithm so that QoS can be guaranteed for the ongoing connections.

A hybrid CAC algorithm for maximizing downlink capacity of M-WiMAX systems

Due to the implementation of an Adaptive Modulation-Coding (AMC) mechanism in the 802.16e physical layer, each connection's bandwidth requirements cannot be statically computed, but they derive as a function of the terminals' instantaneous Signal-to-Noise Ratio (SNR). Therefore, the Connection Admission Control (CAC) mechanism fails to establish an efficient policy that would optimally exploit the system's resources. In this respect, the present paper formulates initially an adequate method for statistically calculating the average capacity of a Mobile-WiMAX system, according to the distribution of the several attenuation factors that affect the signal along the propagation path. In parallel, based on the processing of the terminal's SNR samples, a sophisticated algorithm for filtering out any misleading measurements is developed. This second method aims at predicting the upcoming Modulation-Coding state of every connection, so as to acquire a short-term view of its spectrum demands. Finally, all the above info collected from both the estimation methods is utilized by the CAC procedure in order to perform an as accurate as possible computation of the resource availability. As a result, this hybrid approach succeeds in maximizing the network revenue through significantly increasing the number of concurrently serviced connections while guaranteeing their Quality of Service (QoS) standards.

WiMAX Cell Level Simulation Platform Based on ns-2 and DSP Integration

WiMAX Cell Level Simulation Platform Based on ns-2 and DSP IntegrationThe WiMAX (Worldwide Interoperability for Microwave Access) system based on the IEEE 802.16 family of standards is a promising technology for last-mile access. Both IEEE 802.16 and 3GPP-LTE systems candidate for becoming the 4G network of choice. The need to evaluate multiple performance enhancing techniques like MIMO, OFDM(A), novel channel coding schemes like non-binary LDPC codes, together with development of standards like IEEE 802.21, that aims at enabling handover and interoperability between heterogeneous network types, make rapid prototyping-based simulations an important issue. This paper presents a novel approach to 4G-oriented simulation environment that integrates popular network simulator (ns-2) and a Digital Signal Processing (DSP) to enable comprehensive link layer and cell level simulations. Proposed simulation environment is intended as an evaluation platform for assessing QoS/QoE and Connection Admission Control (CAC) algorithms designed for WiMAX systems. Moreover we study ways to improve simulation time (with focus on AWGN channel simulation) by using CUDA parallel processing technology for NVIDIA graphic cards.

Dynamic guard margin CAC algorithm with ensured QoS and low CDP in heterogeneous wireless networks

This paper proposes a dynamic guard margin algorithm for connection admission control in heterogeneous wireless networks, where UMTS and WLAN systems co-exist in different tiers. The algorithm works based on the idea that a network controller should down-grade the similar or lower Quality of Service (QoS) classes of traffic during the QoS negotiation phase in handovers, instead of rejecting handover connection requests of higher QoS class of traffic. The efficiency of the proposed algorithm is evaluated and compared with the other proposed algorithms using computer simulations. The obtained results demonstrated that the proposed algorithm performs much better than the existing algorithms in terms of resource saving, number of accepted connections, number of rejected connections during handovers, and total resource utilization.

A policy approximation method for the UMTS connection admission control problem modelled as an MDP

This article presents a connection admission control (CAC) algorithm for UMTS networks based on the Markov decision process (MDP) approach. To deal with the non-stationary environment due to the time-varying statistical characteristics of the offered traffic, the admission policy has to be computed periodically based on on-line measurements, and the optimal policy computation is excessively time-consuming to be performed on-line. Thus, this article proposes a reduction of the policy space coupled with an aggregation of the state space for the fast computation of a sub-optimal admission policy. Theoretical results and numerical simulations show the effectiveness of the proposed approach.

Design and analysis of partial protection mechanisms in groomed optical WDM mesh networks

We consider the problem of survivable network design in traffic-groomed optical WDM mesh networks that support subwavelength capacity connections. In typical survivable network designs, individual sessions are provided either full protection or no protection. We consider a quality of protection (QoP) framework where a connection is provided partial protection, i.e., when a link failure occurs on the primary path, the protection bandwidth provided on the backup path is less than or equal to the primary bandwidth. Each connection request specifies the primary bandwidth and a minimum backup bandwidth required. The network will guarantee at least the minimum backup bandwidth and, if capacity is available, higher backup bandwidth up to the primary path's bandwidth. The advantage of such a model is that it can reduce backup capacity requirements based on connection needs leading to lower blocking probability and lower network costs. We consider two scenarios: (i) a network with static traffic that is designed using an integer linear program (ILP) formulation and (ii) a network with dynamic traffic for which we present a heuristic connection admission control algorithm that prevents backup resource contention during recovery from a link failure. The results quantify the gain in blocking probability for different partial protection scenarios. The mechanism proposed to counter backup contention is seen to provide an average of 120% reduction in the contention among backup paths of connections traversing a link, especially when the number of wavelengths in each link is small.

A Scalable Call Admission Control Algorithm

In this paper, we propose a scalable algorithm for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">connection</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">admission</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">control</i> (CAC). The algorithm applies to a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">multiprotocol</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">label</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">switching</i> (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 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">quality</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">of</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">service</i> (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.

Admission Control in UMTS Networks based on Approximate Dynamic Programming

This paper presents a Connection Admission Control (CAC) algorithm for Universal Mobile Telecommunications System (UMTS) networks based on an Approximate Dynamic Programming (ADP) approach. To deal with the non-stationary environment due to the timevarying statistical characteristics of the offered traffic, the admission policy has to be computed periodically based on on-line measurements. If standard algorithms are used, the optimal policy computation is excessively time-consuming to be performed on-line. Thus, an ADP approach for the computation of a sub-optimal admission policy is proposed. TheADPapproach is based (i) on the reduction of the policy space, and (ii) on an approximated state-space aggregation. Theoretical results and numerical simulations show the effectiveness of the proposed approach, which is currently being implemented in a real UMTS testbed.

Packet Scheduler for Mobile Communications Systems with Time-Varying Capacity Region

Adaptive modulation and coding (AMC) scheme is widely used in wireless and mobile communications systems supporting high-speed Internet services. A system using AMC can be modeled as that with time-varying capacity. In this paper, we propose a generalized framework of packet scheduler for wireless systems with time-varying capacity. First, we develop the fundamental scheduling algorithm (FSA) that maximizes the system throughput under given constraints by using the dual optimization technique. Even though FSA can be used as a stand-alone scheduler supporting only nonreal-time traffic, it mainly plays a role in this paper as a basic building block of the advanced scheduling algorithm (ASA). We design ASA so that it supports real-time and nonreal-time traffic simultaneously. Since ASA operates on the basis of connections, we also suggest a connection admission control algorithm that matches well with the proposed scheduler. Finally, we show an application example of the proposed scheduling algorithm to the time-division multiple access system using AMC

Mobility-Aware Admission Control Schemes in the Downlink of Third-Generation Wireless Systems

In this paper, novel connection admission control (CAC) algorithms that take into account the effect of mobility of users both inside and outside the cell in the downlink of third-generation mobile systems are developed. First, the system capacity, including the other-cell interference, subject to feedback between cells is studied. Then, effective bandwidth expressions for calls are obtained as a function of both their location in the cell as well as their class of traffic (i.e., voice versus data). Next, this formulation is used to derive two mobility-aware admission control algorithms, i.e., a priority CAC, where calls are accepted not only upon resource availability, but also through acceptance ratios that reflect their levels of priority, and a squeezing CAC, where elastic calls may be squeezed to a minimum agreed value, giving way to admit more calls in the system and to secure further ongoing mobile users. Using Markovian analysis, several performance measures are obtained, namely the blocking probability, the dropping probability, both intracell and intercell, as well as the overall cell throughput. The authors eventually investigate the performance of our CAC and show how to extend the Erlang capacity bounds, i.e., the set of arrival rates such that the corresponding blocking/dropping probabilities are kept below predetermined thresholds

Effective Admission Policy for Multimedia Traffic Connections over Satellite DVB-RCS Network

Thanks to the great possibilities of providing different types of telecommunication traffic to a large geographical area, satellite networks are expected to be an essential component of the next-generation internet. As a result, issues concerning the designing and testing of efficient connection-admission-control (CAC) strategies in order to increase the quality of service (QoS) for multimedia traffic sources, are attractive and at the cutting edge of research. This paper investigates the potential strengths of a generic digital-video-broadcasting return-channel-via-satellite (DVB-RCS) system architecture, proposing a new CAC algorithm with the aim of efficiently managing real-time multimedia video sources, both with constant and high variable data rate transmission; moreover, the proposed admission strategy is compared with a well-known iterative CAC mainly designed for the managing of real-time bursty traffic sources in order to demonstrate that the new algorithm is also well suited for those traffic sources. Performance analysis shows that, both algorithms guarantee the agreed QoS to real-time bursty connections that are more sensitive to delay jitter; however, our proposed algorithm can also manage interactive real-time multimedia traffic sources in high load and mixed traffic conditions.

A combined admission control algorithm with DA protocol for satellite ATM networks

Admission control is an important strategy for Quality of Service (QoS) provisioning in Asynchronous Transfer Mode (ATM) networks. Based on a control-theory model of resources on-Demand Allocation (DA) protocol, the paper studies the effect of the protocol on the statistical characteristics of network traffic, and proposes a combined connection admission control algorithm with the DA protocol to achieve full utilization of link resources in satellite communication systems. The proposed algorithm is based on the cross-layer-design approach. Theoretical analysis and system simulation results show that the proposed algorithm can admit more connections within certain admission thresholds than one that does not take into account the DA protocol. Thus, the proposed algorithm can increase admission ratio of traffic sources for satellite ATM networks and improve satellite link utilization.

Combined Connection Admission Control and Packet Transmission Scheduling for Mobile Internet Services

Mobile Internet access is expected to be the most popular communication service in the near future. In this paper, we investigate radio resource management for mobile Internet multimedia systems that use the orthogonal frequency division multiple access and adopt the adaptive modulation and coding technique. It is assumed that real-time (RT) service such as streaming video and best-effort (BE) services such as file transfer protocol and hypertext transfer protocol coexist in the systems. We suggest two levels of radio resource management schemes: the connection admission control (CAC) scheme at the first level and the packet transmission scheduler at the second level. The proposed scheduler does not assign higher priority to RT packets over BE packets unconditionally. Instead, only the RT packets that are close to the deadline are given higher priority. Therefore, the performance of BE services is improved at the cost of RT services. To control the performance degradation in RT services within an acceptable level, the CAC algorithm functions as a congestion controller. The combined effects of the proposed CAC and packet scheduling by using the cross-layer simulation that covers from the physical layer to the Internet application layer are evaluated. The numerical results show that the proposed schemes greatly improve the performance of BE services while maintaining the quality of video service at an acceptable level

QoS Mechanisms for the MAC Protocol of IEEE 802.11 WLANs

There are two essential ingredients in order for any telecommunications system to be able to provide Quality-of-Service (QoS) guarantees: connection admission control (CAC) and service differentiation. In wireless local area networks (WLANs), it is essential to carry out these functions at the MAC level. The original version of IEEE 802.11 medium access control (MAC) protocol for WLANs does not include either function. The IEEE 802.11e draft standard includes new features to facilitate and promote the provision of QoS guarantees, but no specific mechanisms are defined in the protocol to avoid over saturating the medium (via CAC) or to decide how to assign the available resources (via service differentiation through scheduling). This paper introduces specific mechanisms for both admission control and service differentiation into the IEEE 802.11 MAC protocol. The main contributions of this work are a novel CAC algorithm for leaky-bucket constrained traffic streams, an original frame scheduling mechanism referred to as DM-SCFQ, and a simulation study of the performance of a WLAN including these features.

Integrated Connection Admission Control and Bandwidth on Demand Algorithm for a Broadband Satellite Network with Heterogeneous Traffic

There are many system proposals for satellite-based broadband communications that promise high capacity and ease of access. Many of these proposals require advanced switching technology and signal processing on-board the satellite(s). One solution is based on a geosynchronous (GEO) satellite system equipped with on-board processing and on-board switching. An important feature of this system is allowing for a maximum number of simultaneous users, hence, requiring effective medium access control (MAC) layer protocols for connection admission control (CAC) and bandwidth on demand (BoD) algorithms. In this paper, an integrated CAC and BoD algorithm is proposed for a broadband satellite communication system with heterogeneous traffic. A detailed modeling and simulation approach is presented for performance evaluation of the integrated CAC and BoD algorithm based on heterogeneous traffic types. The proposed CAC and BoD scheme is shown to be able to efficiently utilize available bandwidth and to gain high throughput, and also to maintain good Grade of Service (GoS) for all the traffic types. The end-to-end delay for real-time traffic in the system falls well within ITU's Quality of Service (QoS) specification for GEO-based satellite systems.