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ATM Networks (atm + network)
Kinds of ATM Networks Selected AbstractsPerformance analysis and interoperability issue of consolidation algorithms in point-to-multipoint ABR servicesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2002Naris Rangsinoppamas Abstract In this paper we propose a performance analysis of the consolidation algorithms in point-to-multipoint ABR services in ATM network. We also present a new efficient consolidation algorithm, which overcomes some drawbacks of the previous works. The performance of the previous works and our proposed consolidation algorithms are analysed mathematically. General equations for calculating the response time and allowed cell rate of the source are derived. The derived equations show relatively good agreement with simulation results and can be applied for using in various network topologies. In addition, the interoperability issue in multicast available bit rate (ABR) is investigated. It is found that the branch points implemented with different consolidation algorithms can work interoperably. It is concluded from the simulation results that the performance of the point-to-multipoint ABR services is dominated by the most upper stream branch point (the nearest one to the source), therefore, in order to avoid the consolidation noise and get a faster response in the network, the most upper stream branch point has to be implemented with a high accuracy consolidation algorithm while the lower stream branch point(s) should be implemented with a fast response consolidation algorithm with a less degree of complexity. Copyright © 2002 John Wiley & Sons, Ltd. [source] Heuristic and simulated annealing algorithms for solving extended cell assignment problem in wireless ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2002Der-Rong Din Abstract In this paper, we investigate the extended cell assignment problem which optimally assigns new adding and splitting cells in Personal Communication Service (PCS) to switches in a wireless Asynchronous Transfer Mode (ATM) network. Given cells in a PCS network and switches on an ATM network (whose locations are fixed and known), we would like to do the assignment in an attempt to minimize a cost criterion. The cost has two components: one is the cost of handoffs that involve two switches, and the other is the cost of cabling. This problem is modeled as a complex integer programming problem, and finding an optimal solution to this problem is NP-hard. A heuristic algorithm and a simulated annealing algorithm are proposed to solve this problem. The heuristic algorithm, Extended Assignment Algorithm (EEA), consists of two phases, initial assigning phase and cell exchanging phase. First, in the initial assigning phase, the initial assignments of cells to switches are found. Then, these assignments are improved by performing cell exchanging phase in which two cells are repeatedly exchanged in different switches with great reduction of the total cost. The simulated annealing algorithm, ESA (enhanced simulated annealing), generates constraint-satisfied configurations, and uses three configuration perturbation schemes to change current configuration to a new one. Experimental results indicate that EAA and ESA algorithms have good performances. Copyright © 2002 John Wiley & Sons, Ltd. [source] A QoS management framework for distributed multimedia systemsINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 2 2003Daniel Won-Kyu Hong This paper proposes a high-performance connection management architecture to design a common QoS framework applied to an ATM network based on the Open Distributed Processing (ODP) concept. We design the QoS framework in accordance from the RM-ODP information and computational viewpoints. Copyright © 2003 John Wiley & Sons, Ltd. [source] 60 GHz fiber-radio communication system for indoor ATM networkMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2001S. Dupont Abstract This paper presents a 60 GHz radio over fiber communication system for high-data-rate ATM indoor transmission. The radio interface is fully MMIC integrated (OMMIC ED 0.2 AH foundry). The system has been successfully tested in an indoor environment for a data rate up to 100 Mbits/s. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 307,310, 2001. [source] Novel DLC model for QoS enhancement of bursty VBR traffic in wireless ATM networksEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 8 2008Hosam El-Ocla Several data-link control (DLC) protocol procedures have been proposed in order to provide reliable data transmission over powerless radio links. However, many quality of service (QoS) issues still need to be achieved such as balance between cell transfer delay (CTD) and cell loss rate (CLR), absence of cell delay variation (CDV) and network traffic utilisation. The main problem with wireless ATM is how to overcome the unreliability of the wireless link in order to maintain QoS requirements especially for variable bit rate (VBR) application. Here, we propose a model that provides QoS support for ATM virtual connections (VC) and solves the unreliability problem of the wireless ATM through an efficient DLC protocol for bursty VBR traffic. This model mainly concerns with enhancing QoS to gain error-free wireless transmission and regulating VBR Traffic. Copyright © 2008 John Wiley & Sons, Ltd. [source] QoS in IntServ-based IP networks: the peak rate policingEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 4 2003Lorenzo Battaglia In the last few years, IP has moved towards resource reservation, with the task to guarantee in the future Quality of Service (QoS). This has led to flow admission control algorithms based on the negotiation of standardised traffic parameters. QoS can be guaranteed in any network, a priori from the used technology, only if the used admission control algorithm wisely shares the network's resources among the users. Any admission control algorithm on its turn can do so, only if every user respects the negotiated traffic parameters. Since any user could, maliciously or not, send at a higher rate than negotiated, i.e. use a higher share of resources than the negotiated one, in every network in which admission control is performed, a policing algorithm is used. An ideal policer should guarantee to reject no packet of a well-behaved user and police contract violation as rigidly as possible. All this independently of the characteristics of the monitored stream and of the background traffic. This holds also for Integrated Services (IS) based IP networks. In these networks, every user negotiates a peak and an average rate. In this paper we present the solution to the peak rate policing issue. We adapt the Generic Cell Rate Algorithm (GCRA), well-known policer used in ATM networks, to police the peak rate of flows of packets with variable length. We intuitively call this modified GCRA Generic Packet Rate Algorithm (GPRA) and dimension its parameters so that independently of the characteristics of the policed flow and of the background traffic, no packets of a well-behaved user are rejected and that the flows of any misbehaving user are rigidly policed. Copyright © 2003 AEI. [source] Performance issues of bandwidth management in ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2003Christos Bouras Abstract In our days, efficient management of the available network resources becomes a critical issue, both from a functional point of view (so that users can be provided with the bandwidth they need), and an economical point of view (so that carriers can satisfactorily and efficiently serve as many customers as possible and at the same time increase their revenue). In this paper we consider a bandwidth control scheme (i.e. managed bandwidth service) for an ATM network infrastructure which is applied to the Greek research and technology network (GRNET). We present some methods that we have tested (in a simulation setting) in order to increase the efficiency of the system and the utilization of the available bandwidth. More specifically, we consider a bandwidth-resizing algorithm for virtual paths, in order to keep the allocated bandwidth very close to the bandwidth actually used. This leads to an increased number of accepted requests and better network utilization. We, also, use the simulation results in order to get an estimation of the effective bandwidth for VBR paths that can be used in call admission. Finally, we consider a semi-offline scheme where requests are gathered and considered for acceptance in regular intervals. Simulation results show an increase in the utilization of resources. As a further improvement, we allow connections to be allocated a little before or after the time initially requested. This leads to further improvement in network utilization. All the improvement schemes were tested with the ATM-TN simulator and the results look promising. Copyright © 2003 John Wiley & Sons, Ltd. [source] A batch-type time-true ATM-network simulator,design for parallel processingINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 8 2002Michael Logothetis Abstract This paper presents a new type of network simulator for simulating the call-level operations of telecom networks and especially ATM networks. The simulator is a pure time-true type as opposed to a call-by-call type simulator. It is also characterized as a batch-type simulator. The entire simulation duration is divided into short time intervals of equal duration, t. During t, a batch processing of call origination or termination events is executed and the time-points of these events are sorted. The number of sorting executions is drastically reduced compared to a call-by-call simulator, resulting in considerable timesaving. The proposed data structures of the simulator can be implemented by a general-purpose programming language and are well fitted to parallel processing techniques for implementation on parallel computers, for further savings of execution time. We have first implemented the simulator in a sequential computer and then we have applied parallelization techniques to achieve its implementation on a parallel computer. In order to simplify the parallelization procedure, we dissociate the core simulation from the built-in call-level functions (e.g. bandwidth control or dynamic routing) of the network. The key point for a parallel implementation is to organize data by virtual paths (VPs) and distribute them among processors, which all execute the same set of instructions on this data. The performance of the proposed batch-type, time-true, ATM-network simulator is compared with that of a call-by-call simulator to reveal its superiority in terms of sequential execution time (when both simulators run on conventional computers). Finally, a measure of the accuracy of the simulation results is given. Copyright © 2002 John Wiley & Sons, Ltd. [source] Heuristic and simulated annealing algorithms for solving extended cell assignment problem in wireless ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2002Der-Rong Din Abstract In this paper, we investigate the extended cell assignment problem which optimally assigns new adding and splitting cells in Personal Communication Service (PCS) to switches in a wireless Asynchronous Transfer Mode (ATM) network. Given cells in a PCS network and switches on an ATM network (whose locations are fixed and known), we would like to do the assignment in an attempt to minimize a cost criterion. The cost has two components: one is the cost of handoffs that involve two switches, and the other is the cost of cabling. This problem is modeled as a complex integer programming problem, and finding an optimal solution to this problem is NP-hard. A heuristic algorithm and a simulated annealing algorithm are proposed to solve this problem. The heuristic algorithm, Extended Assignment Algorithm (EEA), consists of two phases, initial assigning phase and cell exchanging phase. First, in the initial assigning phase, the initial assignments of cells to switches are found. Then, these assignments are improved by performing cell exchanging phase in which two cells are repeatedly exchanged in different switches with great reduction of the total cost. The simulated annealing algorithm, ESA (enhanced simulated annealing), generates constraint-satisfied configurations, and uses three configuration perturbation schemes to change current configuration to a new one. Experimental results indicate that EAA and ESA algorithms have good performances. Copyright © 2002 John Wiley & Sons, Ltd. [source] An enhanced explicit rate algorithm for ABR traffic control in ATM networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2001Y. H. Long Abstract A high performance, low computational complexity rate-based flow control algorithm which can avoid congestion and achieve fairness is important to ATM available bit rate service. The explicit rate allocation algorithm proposed by Kalampoukas et al. is designed to achieve max,min fairness in ATM networks. It has several attractive features, such as a fixed computational complexity of O(1) and the guaranteed convergence to max,min fairness. In this paper, certain drawbacks of the algorithm, such as the severe overload of an outgoing link during transient period and the non-conforming use of the current cell rate field in a resource management cell, have been identified and analysed; a new algorithm which overcomes these drawbacks is proposed. The proposed algorithm simplifies the rate computation as well. Compared with Kalampoukas's algorithm, it has better performance in terms of congestion avoidance and smoothness of rate allocation. Copyright © 2001 John Wiley & Sons, Ltd. [source] Dynamic bandwidth allocation and buffer dimensioning under equal segment scheme to support video-on-demand servicesINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2001Liren Zhang Abstract This paper focuses on the optimization of network bandwidth allocation and buffer dimensioning to transport pre-stored MPEG video data from source to playback destination across ATM networks. This is one of the most important issues in the support of video-on-demand (VoD) service. This paper provides a novel scheme in the dynamic allocation of bandwidth to segments of video using ABR mode. The dynamic bandwidth allocation is based on a new concept, called playback tunnel which is obtained from the traffic characteristics of the pre-stored MPEG video trace to determine the optimum of transmission bandwidth as well as the buffer capacity to ensure that the playback buffer neither underflows nor overflows. The proposed scheme is tested with real-life MPEG video traces. The obtained results have shown its significant performance improvement in terms of the capacity of playback buffer, the start-up playback delay, the size of video segment and the network multiplexing gain. Copyright © 2001 John Wiley & Sons, Ltd. [source] Queuing analysis of shared-buffer ATM switches with grouped output channelsINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 3 2001Abdullah A. Abonamah Abstract Shared buffering and channel grouping are powerful techniques with great benefits in terms of both performance and implementation. Shared-buffer switches are known to have better performance and better utilization than input or output queued switches. With channel grouping, a cell is routed to a group of channels instead of a specific output channel. In this way, congestion due to output contention can be minimized and the switch performance can therefore be greatly improved. Although each technique is well known by itself in the traditional study of queuing systems, their combined use in ATM networks has not been much explored previously. In this paper, we develop an analytical model for a shared-buffer ATM switch with grouped output channels. The model is then used to study the switch performance in terms of cell loss probability, cell delay and throughput. In particular, we study the impact of the channel grouping factor on the buffer requirements. Our results show that grouping the output channels in a shared-buffer ATM switch leads to considerable savings in buffer space. Copyright © 2001 John Wiley & Sons, Ltd. [source] Measured average cell rate-based congestion avoidance schemeINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 1 2001Hyun M. Choi Abstract Techniques for congestion control of available bit-rate (ABR) traffic in ATM (asynchronous transfer mode) networks remain an important issue. Several congestion control schemes have been proposed to adjust the cell rates of sources with a modified or mean allowed cell rate. To make these schemes work effectively in practice, the modified or mean allowed cell rate must converge under all conditions. However, it is not easy to obtain an accurate value, and an inaccurate value could result in network performance degradation such as severe oscillations and considerable unfairness. Therefore, we propose a measured average cell rate-based congestion avoidance for ABR traffic in ATM networks. The scheme has high throughput and achieves shorter queue lengths without congestion. With measured average cell rate, the scheme provides fast convergence to a start-up virtual connection (VC) and rate of equalization from different initial conditions of the sources. Thus, this scheme provides better fairness among connections. Copyright © 2001 John Wiley & Sons, Ltd. [source] A novel methodology for robust VBR video transmission in an ATM systemINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2002A. Alheraish A dynamic FEC (DFEC) scheme for VBR video in ATM networks is proposed. The scheme combines the design of source encoder, error control, and the network. In the design, we will develop a methodology to vary FEC redundancy dynamically. The methodology considers the fluctuations in video source and network utilisation to adjust the FEC redundancy levels. We demonstrate the effectiveness of the proposed scheme by examining its performance with three existing schemes in terms of loss rates, throughput, and quality degradation. Copyright © 2002 John Wiley & Sons, Ltd. [source] Reducing signaling traffic in wireless ATM networks through handoff scheme improvementINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2002Professor Anna Ha We propose a new handoff call management scheme which reduces signaling traffic in wireless ATM networks and improves the efficiency of the virtual channel. Chaining followed by a make-break algorithm is a suitable handoff scheme for various situations. In the chaining part of the scheme, a chain routing algorithm is studied and compared with the hop-limiting scheme. When the algorithm is implemented in our scheme, it improves the performance of the existing scheme in call drop rates so as to reduce the signaling traffic in wireless ATM networks. Copyright © 2002 John Wiley & Sons, Ltd. [source] ARCMA,adaptive request channel multiple access protocol for wireless ATM networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2001Professor Anna Ha We propose a new multiple access protocol based on demand assignment. This protocol is designed to reduce contention in the request phase while minimizing transmission delay under various network (ATM) environments. Our protocol uses an adaptive scheme that changes under heavy traffic conditions, and also provides priority to certain delay-sensitive traffic. Copyright © 2001 John Wiley & Sons, Ltd. [source] |