Connection Admission Control Scheme Research Articles

Joint resource allocation, routing and CAC for uplink OFDMA networks with cooperative relaying

In this paper, we propose a joint resource allocation, routing, and connection admission control (CAC) scheme for uplink transmission in orthogonal frequency division multiple access (OFDMA) relay networks with cooperative relaying. For cooperative relaying, relay station can relay uplink data from mobile station (MS) to base station with cooperation of the MS using transmit diversity. Transmit diversity can be achieved by virtual MISO via distributed space---time coding. The proposed scheme jointly allocates OFDMA resources and selects path for each user with CAC to maximize the upink throughput of cooperative OFDMA relay networks. The basic OFDMA resource unit is considered as a resource element which is one subcarrier over one OFDMA symbol. An efficient multi-choice multi-dimensional knapsack (MMKP) algorithm is presented for the proposed scheme. The proposed MMKP algorithm provides a unified framework which is applicable to OFDMA networks with and without cooperative relaying. We evaluate the performance of the proposed scheme with and without cooperative relaying in a hilly terrain with heavy tree density by using OPNET-based simulation. We show that the cooperative relaying improve the uplink system throughput compared with non-cooperative relaying, and the proposed scheme outperforms the conventional link quality-based scheme in both cooperative and non-cooperative relay networks.

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.

Modulation Aware Connection Admission Control and Uplink Scheduling Algorithm for Wimax Networks

Mobile WiMAX standard defines air interface for mobile broadband wireless access (BWA) systems and aimed to provide high data rate with seamless mobility while maintaining the quality of service (QoS). However, QoS of real-time applications depends on the link quality, which necessitate the channel-aware connection admission control (CAC) and scheduling schemes. In this paper Modulation aware CAC scheme and base station (BS) uplink scheduling algorithm are proposed to improve the system capacity and QoS performance respectively. The proposed CAC scheme aims to increase the admission of higher priority real time services by degrading the bandwidth of admitted lower priority connections on the basis of their channel status without deteriorating their QoS performance much. The performances of proposed algorithms are evaluated through simulation by considering the metrics like throughput, delay and number of connections admitted.

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This paper proposes a neural net based-predictive connection admission control (CAC) scheme for multiclass users in wireless cognitive radio networks. We classifies cognitive users(cu) into real and non real time services, and then permit only real time services to reserve the demanded resource for spectrum handoff in guard channel for provisioning the desired QoS. Neural net is employed to predict primary user`s arrival on time and demanded channels. Resource scheduling scheme is based on (cognitive user I complete access) shown in this paper. For keeping primary users from interference, the CAC is performed on only cognitive user not primary user. Simulation results show that our schemes can guarantee the desired QoS by cognitive real time services.

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 joint uplink/downlink connection admission control in WLAN/cellular integrated systems

Although different connection admission control schemes in wireless local area network (WLAN)/cellular integrated systems have been proposed in the literature, they do not exploit unique features in uplink and downlink connections. In this paper, we propose a joint uplink/downlink connection admission control scheme in WLAN/cellular integrated systems, in which thresholds for admission control are adaptively determined to maximize the network capacity depending on the uplink and downlink characteristics. We develop an analytical model for the connection blocking cost by means of multi-dimensional Markov chains and present an optimization problem for the thresholds to minimize the blocking cost. Analytical and simulation results show that the proposed connection admission control scheme can reduce the number of blocked connections compared with the WLAN-first scheme.

Joint Connection Admission Control and Packet Scheduling in a Cognitive Radio Network with Spectrum Underlay

With the increasing popularity of cognitive radio networks (CRNs), providing data transmissions with quality of service (QoS) requirements in such networks becomes one of the most important topics. In this paper we study QoS provisioning in an ad hoc CRN with spectrum underlay. Both streaming traffic and non-real-time (nrt) data traffic are considered. The former requires a low session outage probability and the latter requires a minimum average throughput. A joint connection admission and packet scheduling scheme is proposed in this paper. The connection admission control scheme limits the amount of traffic admitted into the system so that all admitted connections can receive their required QoS through the proposed packet scheduling schemes. Two packet transmission scheduling schemes are designed, one is optimum and assumes that a central controller can collect the global channel and interference conditions within the CRN and between the primary network and the CRN, while the other one is a heuristic scheme based on the link and interference conditions measured by the nodes in the CRN. In addition to achieving the required QoS, the scheduling schemes utilize the available radio resources fairly and efficiently. Numerical results demonstrate that when the traffic load at the primary network is relatively stationary, the proposed scheduling scheme can achieve very low and fair outage probability for all admitted streaming connections, and all admitted non-real-time data connections can receive the required throughput and fair delay performance.

Quality of service-guaranteed cluster-based multihop wireless ad hoc sensor networks

With the help of prioritised polling token and a local synchronisation scheme, this study proposes a quality of service (QoS)-guaranteed scheduling algorithm. It works based on distributed intelligence and schedules both intra-cluster and inter-cluster connections in a cluster-based multihop wireless ad hoc sensor network. Theoretical analyses are employed to derive the bounds for the jitter and delay of each intra-cluster and inter-cluster connection. Based on the obtained jitter bounds and delay bounds, a connection admission control scheme is proposed as the admission criterion for each newly requested connection. Both numerical and simulation results show that by taking the advantages of proposed polling-based QoS scheduling algorithm and the connection admission control jointly, the QoS requirements of all admitted intra-cluster and inter-cluster connections are guaranteed.

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.

A combined resource management and admission control scheme for optimizing uplink performance of M-WiMAX systems

According to the AMC (Adaptive Modulation-Coding) mechanism of the M(obile)-WiMAX, the amount of data per modulation symbol depends on the perceived Signal-to-Noise Ratio, while, based on the OFDMA (Orthogonal Frequency Division Multiple Access) technique, each communication entails multiple concurrent transmissions. Therefore, in the uplink case, where each terminal has a maximum power limitation, the assignment of additional subcarriers does not always correspond to a proportional datarate increment, since the power dispersion over a larger set of symbols can cause the transition to a lower AMC level. In this framework, the present paper introduces a novel RRM (Radio Resource Management) algorithm that dynamically alters the number of subcarriers to be allocated to each connection so as to achieve spectrum saving via augmenting the bits per symbol ratio. Furthermore, in order to mitigate the extensive fluctuations imposed by the novel RRM scheme, an adequate minimum-complexity CAC (Connection Admission Control) scheme is proposed, which succeeds in accurately estimating the bandwidth requirements of the active flows by incorporating theoretical calculations along with a sampling process. It is proven analytically as well as through simulations that the new combined RRM-CAC strategy increases substantially the system capacity, without violating the Quality-of-Service guarantees.

Wireless telemedicine services over integrated IEEE 802.11/WLAN and IEEE 802.16/WiMAX networks

Wireless telemedicine, also referred to as mobile health, which capitalizes on advances of wireless technologies to deliver health care and exchange medical knowledge anywhere and any time, overcomes most of geographical, temporal, and even organizational barriers to facilitate remote diagnosis and monitoring, and transfer of medical data and records. In this article we investigate the application of integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN broadband wireless access technologies along with the related protocol issues for telemedicine services. We first review IEEE 802.11/WLAN and IEEE 802.16/WiMAX technologies, and make a comparison between IEEE 802.11/WLAN and IEEE 802.16/WiMAX. Then some open research issues in the integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN networks are discussed, especially regarding QoS support, radio resource management, scheduling and connection admission control schemes, as well as handover and mobility management. Finally, applications and deployment scenarios of integrated IEEE 802.16/WiMAX and IEEE 802.11/WLAN for telemedicine services are further deliberated.

Downlink resource management for QoS scheduling in IEEE 802.16 WiMAX networks

IEEE 802.16, also known as WiMAX, has received much attention recently for its capability to support multiple types of applications with diverse Quality-of-Service (QoS) requirements. Beyond what the standard has defined, radio resource management (RRM) still remains an open issue, which plays an important role in QoS provisioning for different types of services. In this paper, we propose a downlink resource management framework for QoS scheduling in OFDMA based WiMAX systems. Our framework consists of a dynamic resource allocation (DRA) module and a connection admission control (CAC) module. A two-level hierarchical scheduler is developed for the DRA module, which can provide more organized service differentiation among different service classes, and a measurement-based connection admission control strategy is introduced for the CAC module. Through system-level simulation, it is shown that the proposed framework can work adaptively and efficiently to improve the system performance in terms of high spectral efficiency and low outage probability.

Scheduling and CAC in IEEE 802.16 Fixed BWNs: A Comprehensive Survey and Taxonomy

IEEE 802.16 technology has emerged as a competitive alternative to wireline broadband access solution. IEEE 802.16 can provide quality of service (QoS) guarantees for heterogeneous classes of traffic with different QoS requirements. The standard, however, leaves open the resource management and scheduling issues, which are crucial components to guarantee QoS performance. The main objective of this paper is to provide a better understanding of the missing components to ensure QoS support in IEEE 802.16 fixed broadband wireless networks (BWNs), namely scheduling and connection admission control (CAC) schemes. First, we highlight the key challenges in designing such schemes, for both point-to-multipoint (PMP) and mesh modes. Then, we survey, classify, and compare different scheduling and admission control mechanisms proposed in this work-in-progress area.

Double-granularity connection admission control scheme based on compression sensing

Data compressing techniques are often adopted in practical network systems to improve the efficiency of traffic transmission.However,compression status is ignored in most admission control schemes that usually measure the performance in term of blocking(dropping) probability.In this paper,a Double Granularity Multiple Threshold(DGMT) CAC scheme based on compression sensing was proposed.By sensing compressing levels of arrival connections,DGMT scheme controlled connection admission in granularities of both connection and original information.Multiple thresholds strategy was used in DGMT.Alternatively,Original Information Loss Ratio(OILR) and Transmission Efficiency of Original Information(TEoOI) were presented to measure CAC performances.Theoretical analysis and simulation results show that OILR and TEoOI can well indicate CAC performances,and the performance obtained by compression sensing CAC algorithm improves significantly.

An adaptive fuzzy-based CAC scheme for uplink and downlink congestion control in converged IP and DVB-S2 networks

This paper introduces a robust buffer occupancy-based connection admission control (CAC) mechanism to alleviate both uplink and downlink congestions in converged IP and broadcasting networks. The scheme also ensures a fair share of downlink bandwidth among competing satellite terminals (subnetworks) in the event of congestion. The proposed scheme is dubbed Weighted Fair CAC (W-FCAC). It accepts or rejects connections based on an adaptive fuzzy-based approach. The use of the fuzzy-based mechanism is for the purpose of overcoming issues related to instantaneous link capacity assessment, flow characterization and the associated high computational complexity, and use of traffic descriptors for new flows. Additionally, the adaptive fuzzy logic makes the proposed CAC approach robust to traffic dynamics. These features make the scheme highly suitable for DVB-S2 environments where the link capacity frequently fluctuates due to the adaptive coding/modulation of the physical layer during noisy periods. Simulation results elucidate that the proposed W-FCAC scheme prevents downlink congestion and fairly allocates network resources among satellite terminals. It also minimizes the frequency of congestion events while maintaining efficient utilization of network resources.

Resource allocation for end-to-end QoS provisioning in a hybrid wireless WCDMA and wireline IP-based DiffServ network

In the future UMTS network, the heterogeneous traffics of multimedia services demand various QoS provisioning. At the same time, the seamlessly conveying of information between mobile users and a hybrid network requires the networking from wireless to wireline domains. However, in both academia and industries, the end-to-end QoS provisioning in the integration of wireline and wireless networks remains a challenge. In this paper, a modeling of a hybrid wireless WCDMA and wireline IP-based DiffServ network is presented to investigate the resource allocation for end-to-end QoS provisioning for multimedia services. In the wireless domain, the mathematical modeling of the cross-layer model including the physical layer, the link layer and the network layer is built. The connection admission control scheme is implemented based on the cross-layer model to determine the amount of resource for different services. In the wireline domain, we define the mapping of QoS classes between UMTS and DiffServ networks according to different QoS requirements. We propose a bandwidth allocation scheme to provide satisfactory packet loss and delay guarantee in DiffServ networks. The final end-to-end admission control scheme combines the resource allocation and admission control in both wireless and wireline domains. The analytical and simulation results show that the proposed resource allocation and admission control schemes work cooperatively in the presented hybrid wireless and wireline networks to guarantee the end-to-end QoS requirements for multimedia services.

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.

Performance Analysis for QoS Provisioning at Connection-Level in Cellular WCDMA Networks

In this paper we propose a new connection admission control (CAC) scheme namely dynamic bandwidth reservation (DBR) algorithm at the network layer in order to provision connection-level QoS in cellular WCDMA network. DBR scheme supports Multirate services for new and handover (HO) connections traffic by employing orthogonal variable spreading factor (OVSF). However, to exploit the wireless time-varying channel, we employed a prediction criterion of wireless channel for each mobile connection. Therefore, we impact the wireless channel characteristics in the new/HO traffic distribution. The teletraffic analysis of the proposed scheme is analyzed using a novel multistep Markov chain model. We compare our proposed scheme with multiple leaf code reservation (MLCR) schemes without code reassignment [4]. The performance of the proposed scheme is measured in terms of handover connection dropping probability (HCDP), new connection blocking probability (NCBP), forced termination probability (FTP) and channel 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