Asynchronous Transfer Mode Networks Research Articles

Design of multicode CDMA systems for 3-D stereoscopic video over wireless ATM networks

This paper investigates the application of multicode spread-spectrum code-division multiple-access (SS-CDMA) techniques to three-dimensional (3-D) stereoscopic video transmission over wireless asynchronous transfer mode (ATM) networks. Three-dimensional visual communications, made through the use of stereoscopic images, are able to achieve total display realism. Such services allow users to share the virtual reality (VR) world without any geographical restrictions. In order to create a 3-D system with two images (left and right) that should be transmitted over a bandlimited mobile channel simultaneously, a cost-effective motion picture experts group (MPEG)-based wavelet multiresolution coding with a joint motion and disparity compensation is developed to reduce a large amount of information contained in the images to meet the low-transmission rate limitation of mobile channels. However, the rapidly variable bit rate (VBR) characteristics of the MPEG-based 3-D videos seems a weakness to the transmission of such videos via a constant bit-rate (CBR) mobile channel. The ATM technique is especially well suited for VBR MPEG-based 3-D video because of its ability to allocate bandwidth on demand to these services. However, since the mobile radio has a limited channel capacity, the overall capacity of the traditional ATM-based SS-CDMA system may not be sufficient to accommodate the MPEG-based 3-D video services requested by the multiple mobile users simultaneously. To tackle this difficulty, a multicode CDMA technique is proposed to provide VBR MPEG-based 3-D video services by varying the number of spreading codes assigned to the 3-D video to meet its dynamic throughput requirement. Powerful forward error correction (FEC) codes are necessary to protect the video data so that it can be successfully transmitted at an acceptable signal power level. Two separate FEC code schemes are applied to the header and payload of an ATM cell containing 3-D video data, respectively. The ATM cell header is protected by a relatively powerful FEC code to ensure correct delivery and low cell loss rate (CLR). On the other hand, the ATM cell payload is encoded for varying degrees of error protection according to the priority of the payload data in 3-D videos. An adaptive FEC code combining scheme is proposed to provide the good protection for payload data with the maximization of its code rate to minimize the extra bandwidth for FEC overhead.

Soft handoff in a CDMA wireless ATM environment

Future wireless asynchronous transfer mode (ATM) networks present a number of mobility related challenges. Handoffs due to user mobility require network signaling to maintain the communication link and may result in packet loss due to packet misrouting and/or misordering. This paper proposes a handoff solution for an ATM-based code division multiple access (CDMA) packet switched wireless environment. The proposed solution combines soft handoff and the modified nearest common node rerouting (NCNR) to meet the challenges of wireless ATM. It is shown that, compared with the hard handoff approach, the proposed solution reduces the number of control signals required for handoff and the volume of buffered information packets during handoff, mitigates the problem of packet misrouting and misordering, and significantly improves the radio link transmission accuracy.

Adaptive feedback consolidation algorithm for ABRservice in ATM networks

An adaptive feedback consolidation algorithm is proposed for the multicast available bit rate (ABR) service in asynchronous transfer mode (ATM) networks. The proposed scheme adapts between speed and accuracy of feedback information. The results indicate that the proposed scheme eliminates consolidation noise while exhibiting a fast transient response.

A virtual path routing algorithm for ATM networks based on the equivalent bandwidth concept

The coexistence of a wide range of services with different quality of service (QoS) requirements in today's networks makes the efficient use of resources a major issue. It is desirable to improve network efficiency by adaptively assigning resources to services that have different bandwidth demands. Implementing Broadband Integrated Services Digital Networks (B-ISDN) therefore requires a network control scheme that can handle bursty traffic with unexpected fluctuations. The Asynchronous Transfer Mode (ATM) technology provides this flexibility by virtualizing network resources through the use of the virtual path (VP) concept. In this study, a method for designing a VP-based ATM network is proposed. The developed heuristic design algorithm applies VP routing and separation techniques to minimize the maximum link utilization under processing delay constraints. Each link is assigned a weight that reflects its current utilization. Using these weights, the VPs on highly utilized links are rerouted to less congested physical paths. The algorithm makes use of the equivalent bandwidth concept, which provides an efficient method to estimate capacity requirements of connection requests such that QoS requirements are met. The quality of the solutions achieved by the proposed method is compared to several competitors under varying network topologies and traffic conditions. The observations on the algorithm performance show that the developed method is able to facilitate an efficient use of network resources through the introduction of VPs.

Efficient bandwidth allocation and call admission control for VBR service using UPC parameters

Provision of Quality-of-Service (QoS) guarantees is an important and challenging issue in the design of Asynchronous Transfer Mode (ATM) networks. Call Admission Control (CAC) is an integral part of the challenge and is closely related to other aspects of network designs such as traffic characterization and QoS specification. Since the Usage Parameter Control (UPC) parameters are the only standardized traffic characterizations, developing efficient CAC schemes based on UPC parameters is significant for the implementation of CAC on ATM switches. In this paper, we develop a CAC algorithm called TAP (derived from TAgged Probability) as well as two other CAC algorithms using the UPC parameters. These CAC algorithms are based on our observation that the loss-probability-to-overflow-probability ratio tends to decrease as the number of sources increases. By introducing the loss-probability-to-overflow-probability ratio K, we find that this ratio sheds light on increasing resource utilization while still guaranteeing QoS. Analysis, simulation, and numerical results have shown that the proposed TAP algorithm is simple and efficient. Copyright © 2000 John Wiley & Sons, Ltd.

Basic processes in ATM networks

We consider a broadband network using the asynchronous transfer mode (ATM): several models have been investigated to study the expected performances for some available bit rates and some sizes of the network buffers. In a previous work (Pellaumail et al., Reseaux ATM et P-simulation, Hermes, Paris, 1994) some processes whose role is essential in several models were introduced. The aim of this paper is to give more information on these basic processes: explicit values of the stationary law, computing the moments, busy period, worst case law, etc.

The RETAIN project: dicom teleradiology over an ATM-based network

The RETAIN project (Radiological Examinations Transfer on an ATM Integrated Network) has aimed at testing videoconferencing and DICOM image transfers to get advice about difficult radiological cases over an asynchronous transfer mode (ATM)-based network, which affords a more comfortable interface than narrow-band networks and allows exchange of complete image series using the DICOM format of studies. For this purpose, an experimental ATM network was applied between six university hospitals in four different countries. An assessment of the functionalities of the system was performed by means of log-file analysis, video recording of the sessions and forms filled out by the participants at the end of each session. Questionnaires were answered by the users at the end of the project to bring out perspectives of utilisation and added value. We discussed 43 cases during 20 sessions. For technical or organisational problems, only 20 of the 36 planned sessions took place. The throughput over ATM (10.5 Mbit/s, 20 times faster than six ISDN B-channels) was adequate. Despite the experimental configuration of the network, the system was considered as satisfactory by all the physicians. In 72 % of the sessions, the expected result (answer to the question) was gained. By common consent, videoconferencing was unanimously regarded as a prominent tool in improving the interaction quality. Asynchronous transfer mode is an efficient method for fast transferring of radiologic examinations in DICOM format and for discussing them through high-quality videoconferencing.

Buffer Management Simulation in Atm Networks

Computer networking communications are now in the era of dedicated, high-speed switched networks. Asynchronous Transfer Mode (ATM) networks are increasing in importance because ATM technology has the ability to deliver a high quality of service, while simultaneously supporting multiple classes of traffic on the same transmission pathway. Traffic management is increasingly becoming an important focus of study in ATM networks. In this context, congestion control through adequate buffering is becoming particularly significant to minimize the probability of cell loss and cell delay when multiple large traffic bursts are received concurrently at a switch [1,2]. This paper presents a simulation of a new dynamic buffer allocation management scheme in ATM networks. To achieve this objective, an algorithm that detects congestion and updates the dynamic buffer allocation scheme was developed for the OPNET simulation package via the creation of a new ATM module. This dynamic buffer allocation scheme utilizes four identified attributes: in-use bandwidth, in-use bandwidth of distinct Quality of Service (QoS) of an incoming traffic, available number of buffers on the corresponding logical queue, and the latest short-term cell arrival rate destined to the corresponding output port. The behavior of the network under bursty traffic conditions was examined.

Policing mechanism and cell loss priority control on voice cells in ATM networks using fuzzy logic

The authors present a fuzzy logic-based implementation of the policing mechanism (PM) and cell loss priority control (CLPC) functions on voice cells in asynchronous transfer mode (ATM) networks. Specifically, a redesigned model of fuzzy leaky bucket (FLB) is presented which serves as an alternative PM on the voice sources in an ATM network. As a continuation of the implementation of the FLB in the ATM network, three models of ATM switches with different algorithms are constructed, to perform CLPC on the voice cells, as well as to enhance the network throughput. Simulation results show that FLB is a better PM than the conventional leaky bucket (LB) in terms of cell loss probability and throughput while the mean transfer delay remains unchanged. It is also shown that the model of ATM switch with fuzzy token generator is the most balanced CLPC scheme as compared with the other two models.

Virtual Path Layouts in ATM Networks

We study virtual path layouts in a very popular type of fast interconnection networks, namely asynchronous transfer mode (ATM) networks. One of the main problems in such networks is to construct path layouts that minimize the hop-number (i.e., the number of virtual paths between any two nodes) as a function of the edge congestion c (i.e., the number of virtual paths going through a link). In this paper we construct for any n vertex network H and any c a virtual path layout with hop-number $O(\frac{diam(H)\log\Delta}{\log c})$, where diam(H) is the diameter of the network H and $\Delta$ is its maximum degree. Involving a general lower bound from [E. Kranakis, D. Krizanc, and A. Pelc, Seventh IEEE Symposium on Parallel and Distributed Processing, IEEE Computer Society, 1995, pp. 662--668], we see that these hop-numbers are optimal for bounded degree networks with the diameter O(log n) for any congestion c. In the case of unbounded degree networks (with the diameter O(log n)) these hop-numbers are optimal for any $c\geq\Delta$. For instance, this gives optimal hop-numbers for hypercube related networks. Moreover, we improve known results for paths and meshes and prove optimal hop-numbers for hypercubes.

A neural-fuzzy system for congestion control in ATM networks

We propose the use of a neural-fuzzy scheme for rate-based feedback congestion control in asynchronous transfer mode (ATM) networks. Available bit rate (ABR) traffic is not guaranteed quality of service (QoS) in the setup connection, and it can dynamically share the available bandwidth. Therefore, congestion can be controlled by regulating the source rate, to a certain degree, according to the current traffic flow. Traditional methods perform congestion control by monitoring the queue length. The source rate is decreased by a fixed rate when the queue length is greater than a prespecified threshold. However, it is difficult to get a suitable rate according to the degree of traffic congestion. We employ a neural-fuzzy mechanism to control the source rate. Through learning, membership values can be generated and cell loss can be predicted from the status of the queue length. Then, an explicit rate is calculated and the source rate is controlled appropriately. Simulation results have shown that our method is effective compared with traditional methods.

Engineering ATM networks for congestion avoidance

With the combination of telecommunication, entertainment and computer industries, computer networking is adopting a new method called Asynchronous Transfer Mode (ATM) networking. Congestion control plays an important role in the effective and stable operation of ATM networks. Traffic management concerns with the design of a set of mechanisms which ensure that the network bandwidth, buffer and computational resources are efficiently utilized while meeting the various Quality of Service (QoS) guarantees given to sources as part of a traffic contract. In this paper, the most widely recognized congestion control schemes for ABR service are investigated. Some of these schemes show either lack of scalability or fairness while other well‐behaved schemes may require a highly complex switch algorithm that is unsuitable for implementation in cell‐switching high‐speed ATM networks. A new and improved congestion control scheme is proposed to support the best‐effort ABR traffic. This algorithm provides the congestion avoidance ability with high throughput and low delay, in addition to achieving the max–min fairness allocation.

The ERICA switch algorithm for ABR traffic management in ATM networks

This paper describes the "explicit rate indication for congestion avoidance" (ERICA) scheme for rate-based feedback from asynchronous transfer mode (ATM) switches. In ERICA, the switches monitor their load on each link and determine a load factor, the available capacity, and the number of currently active virtual channels. This information is used to advise the sources about the rates at which they should transmit. The algorithm is designed to achieve high link utilization with low delays and fast transient response. It is also fair and robust to measurement errors caused by the variations in ABR demand and capacity. We present performance analysis of the scheme using both analytical arguments and simulation results. The scheme is being considered for implementation by several ATM switch manufacturers.

A center-controlled dynamic rerouting scheme for fast and reliable handover in mobile ATM networks

This paper proposes a scheme for fast and reliable handover that uses dynamic rerouting controlled by a call setup control station (CCS) operating in mobile asynchronous transfer mode (ATM) networks. The CCS selects appropriate rerouted path and crossover switch (COS), and remotely controls the new path's setup. This omits crossover switch discovery process, and makes fast handover possible. The CCS can select the appropriate rerouted path because it directly and with little delay collects information about the state of links such as traffic loads, quality-of-service (QoS) parameters, and disconnection or restoration of links advertised from every ATM switch in its domain. This reduces blocking and congestion, and makes reliable handover possible. The CCS accepts a handover request message for either backward or forward handover, and can remotely control the new path's setup in the same manner for either handover. The scheme provides forward handover when the radio propagation conditions deteriorate unpredictably. This paper also shows sequences of call origination, connection pre-establishment, and route-change in our proposed scheme, and illustrates operation of the CCS and the ATM switches.

Connection admission control of ATM network using integrated MLP and fuzzy controllers

This paper presents a new approach to the problem of call admission control (CAC) of variable bit rate (VBR) traffic in an asynchronous transfer mode (ATM) network. Our approach employs an integrated neural network and fuzzy controller to implement the CAC controller. This scheme capitalizes on the learning ability of a neural network and the robustness of a fuzzy controller. Experiments show that this scheme is able to achieve high throughput and low cell loss while achieving fairness among different classes of VBR traffic. For comparison, we have also implemented four other CAC schemes: (1) peak bandwidth method, (2) equivalent bandwidth method, (3) average bandwidth method and (4) neural network quality of service (QoS) predictor. Results of these experiments are presented in this paper.

Cell-loss control in multiplexing of VBR video over ATM networks

In this article we investigate the impacts of interspacing and source polling policies on the cell?loss rates in transmission of variable bit rate video sources over Asynchronous Transfer Mode networks. We present a mathematical model that finds the approximate optimal starting times of the video sources that minimize the congestion at the multiplexer. Combined with the approximate optimal source starting times, we propose a source ordering and polling policy for reducing the cell?loss rates. The proposed policy is tested against alternative policies using simulation of pre?recorded video data.

Bandwidth renegotiation with traffic smoothing and joint rate control for VBR MPEG video over ATM

Variable bit-rate (VBR) MPEG video traffic is highly bursty due to group of pictures structure, and shows time-variant statistical characteristics due to scene changes. These characteristics make it more difficult to manage network resources, and leads to the significant reduction in network utilization. We deal with the issues related to efficiently transmitting VBR MPEG video traffic over asynchronous transfer mode networks, while maintaining consistent visual quality and improving network utilization on the basis of real-time applications. First, we propose a joint encoder and channel-rate control scheme that comply with not only negotiated traffic parameters, but also constraints imposed by encoder and decoder buffers. Second, we propose a dynamic bandwidth renegotiation method by combining the above scheme with a traffic smoothing method that can make the peak rate close to the sustainable rate. The efficiencies of the proposed methods are compared with a few other competitive schemes such as transmission methods for unconstrained VBR and the constant bit-rate scheme with average bandwidth equal to that of the proposed methods.

Real-time estimation of the parameters of long-range dependence

An on-line version of the Abry-Veitch (see IEEE GLOBECOM'98, Sydney, Australia,p.3716-21, 1998) wavelet-based estimator of the Hurst parameter is presented. It has very low memory and computational requirements and scales naturally to arbitrarily high data rates, enabling its use in real-time applications such as admission control, and avoiding the need to store huge data sets for off-line analysis. The performance of the estimator as a function of the length of data processed is demonstrated using simulated data. An implementation for 10-Mb/s Ethernet based on standard hardware supporting sampling rates of 1 data point per millisecond is described, and results of its operation presented, as is an implementation for 155-Mb/s asynchronous transfer mode networks. Finally we illustrate the power of on-line measurements by collecting measurements over a period of five months, and using them to look for diurnal trends in scaling properties of the data.

Development of a System to Provide Full, Real-time Remote Control of a Scanning Electron Microscope across the Second Generation Internet: The Teaching SEM

The development and makeup of a real-time full remote control system for the University of Michigan, Department of Materials Science and Engineering Teaching SEM is described. The instrument was initially controlled via the campus local area Ethernet network and cable TV network. The latest implementation employs Fast Ethernet, Asynchronous Transfer Mode (ATM) networks, and moving picture experts group (MPEG) video encoding to effect the remote control via the computer network alone. Remote control demonstrations from Washington, DC, Dearborn, MI, and Emerson School, Ann Arbor, MI are described.

A predictive self-tuning fuzzy-logic feedback rate controller

This paper addresses the design and analysis of an end-to-end rate-based feedback flow control algorithm motivated by the available bit rate (ABR) service in wide-area asynchronous transfer mode (ATM) networks. Recognizing that the explicit feedback rate at time t will not affect the ABR buffer until time t+D for some D/spl ges/0, our approach is to first predict the ABR buffer status at time t+D, then base fuzzy-logic rate control decisions on these predicted values, and finally tune the controller parameters using gradient descent methods. Simulations show that this predictive self-tuning fuzzy-logic (PSTF) control scheme is efficient, stable, and outperforms other proposed ABR rate controllers in a variety of network environments. With delays corresponding to a US coast-to-coast connection, the PSTF controller can maintain high link utilization, avoid buffer overflows, and provide fair allocation of resources.