Asynchronous Transfer Mode Networks Research Articles

Buffer management optimization strategy for satellite ATM

Abstract ECTD (erroneous cell tail drop), a buffer management optimization strategy is suggested which can improve the utilization of buffer resources in satellite ATM (asynchronous transfer mode) networks. The strategy, in which erroneous cells caused by satellite channel and the following cells that belong to the same PDU (protocol data Unit) are discarded, concerns non-real-time data services that use higher layer protocol for retransmission. Based on EPD (early packet drop) policy, mathematical models are established with and without ECTD. The numerical results show that ECTD would optimize buffer management and improve effective throughput (goodput), and the increment of goodput is relative to the CER (cell error ratio) and the PDU length. The higher their values are, the greater the increment. For example, when the average PDU length values are 30 and 90, the improvement of goodput are respectively about 4% and 10%.

Approximate analysis of a dynamic scheduler for self-similar video traffic in ATM networks

Performance evaluation methods that have been used so far failed to capture the real characteristics of network traffic. This is especially true when the service times are general such as the variable bit rate (VBR) video, which is proven to be self-similar. In the paper, diffusion approximation methods are proposed to analyse a dynamic scheduler for self-similar VBR video traffic in asynchronous transfer mode (ATM) networks. The proposed scheme employs a coupled queueing system that has been used extensively in the modelling of computer and communication systems. Diffusion approximations methods are used to decouple a queueing system which represents an ATM network node into separate G/G/1 queues. Real MPEG video traces are used in the discrete event simulation. Results are compared with the approximation, and are found to work very well under different traffic conditions.

A New Hybrid ARQ-FEC Scheme For Wireless ATM Networks

Wired ATM (Asynchronous Transfer Mode) networks are designed taking into account an optical link in the physical layer. The main problem to implement a wireless ATM network is the fact that its radio link bit error rate is high and variable, demanding the use of an additional error control mechanism. The usual techniques for error control are ARQ (Automatic Repeat Request) and FEC (Forward Error Correction). ARQ works better than FEC if the channel bit error rate is low, and is worse if it is high, thus indicating that hybrid ARQ-FEC techniques can improve the radio link performance. A new hybrid ARQ-FEC scheme with multiple FEC states is proposed in this paper. The performance of the proposed scheme is compared with non-adaptive ARQ and FEC schemes, which have similar complexities, and with an ideal adaptive FEC scheme. It is shown that the proposed scheme works better than the non-adaptive schemes, and that the hybrid and the ideal adaptive FEC schemes have similar performances. Moreover, the hybrid scheme does not require an estimate of the bit error rate in the channel, leading to a less complex implementation.

VLSI Implementation of Forward Error Control Technique for ATM Networks

In asynchronous transfer mode (ATM) networks, fixed length cells of 53 bytes are transmitted. A cell may be discarded during transmission due to buffer overflow or a detection of errors. Cell discarding seriously degrades transmission quality. The quality degradation can be reduced by employing efficient forward error control (FEC) to recover discarded cells. In this paper, we present the design and implementation of decoding equipment for FEC in ATM networks based on a single parity check (SPC) product code using very-large-scale integration (VLSI) technology. FEC allows the destination to reconstruct missing data cells by using redundant parity cells that the source adds to each block of data cells. The functionality of the design has been tested using the Model Sim 5.7cXE Simulation Package. The design has been implemented for a 5 × 5 matrix of data cells in a Virtex-E XCV 3200E FG1156 device. The simulation and synthesis results show that the decoding function can be completed in 81 clock cycles with an optimum clock of 56.8 MHz. A test bench was written to study the performance of the decoder, and the results are presented.

A QoS-Tunable Scheme for ATM Cell Scheduling Using Evolutionary Fuzzy System

In packet switching network such as asynchronous transfer mode (ATM), the switching characteristics is important in delivering the guaranteed QoS (Quality of Service) level of the network. Many methods have been developed to control cell flow for shared bandwidth. The first-in first-out (FIFO), static priority (SPR), dynamically weighted priority scheduling (DWPS) (T. Lizambri, F. Duran, and S. Wakid, 1999) and weighted fair queuing (WFQ) (R. Handel, M.N. Huber, and S. Schroder, c1998) are some of the schemes for managing the shared bandwidth. Due to the diversity of services supported in ATM network, it is typical for the traffic flow pattern to change dramatically. A common trait of these algorithms is that their mechanisms are fixed, and they cannot adapt efficiently for such traffic flow changes. In order to address this, we propose an evolutionary fuzzy system (EFS) scheme to do ATM cell scheduling. With EFS, the fuzzy switching algorithm can be adjusted to track the changes in the pattern of traffic flow in order to maintain the desired level of performance. The desired quality of service (QoS) performance level can be conveniently achieved by tuning the parameters of the fitness function.

Building an interconnection between PROFIBUS and ATM networks

In this paper, a method describing connection between PROcess Field BUS (PROFIBUS) and asynchronous transfer mode (ATM) systems is presented. The proposed method reveals the usage of ATM at the cell level of the CIM architecture. This leads to the fact that a new bridge based on PROFIBUS and ATM features should be designed. This study is concerned with not only PROFIBUS and ATM interconnection requiring worst-case translation and solution issues (unmatched services, flow diagram, etc.) but also the performance analysis of the model provided CACI Network II.5.

Error concealment for shape in MPEG-4 object-based video coding

In asynchronus transfer mode networks, cell loss or channel errors can cause data to be dropped in the channel. When digital images/videos are transmitted over these networks, one must be able to reconstruct the missing data so that the impact of the errors is minimized. In this paper, we present an error-concealment technique for shape in MPEG-4 object-based video coding. This method, which is based on using global motion estimation and compensation techniques for boundary recovery, consists of three steps: (1) boundary extraction from shape; (2) boundary patching using global motion compensation; and (3) boundary filling to reconstruct the shape of the damaged video object planes. Global motion parameters are inserted as part of the USER_DATA field in the compressed stream and are utilized in reconstructing the damaged boundaries of compressed video object planes.

On-line resources allocation for ATM networks with rerouting

This paper presents an application we developed for France Telecom R&D to solve a difficult real-life network problem. The problem takes place in an Asynchronous Transfer Mode (ATM) network administration context and consists in planning demands of connection over a period of 1 year. A new demand is accepted if both bandwidth and Quality of Service (QoS) requirements are satisfied. Demands are not known prior to the assignment and must be performed on-line according to their arrival. Moreover, the acceptance or the reject of a demand must be decided within a given time of 1 min. First, we look for a route satisfying the new demand. In case of failure, we try to reroute some already accepted connections in order to satisfy this new demand. Rerouting has been modelled as a Weighted Constraint Satisfaction Problem ( WCSP) and solved by VNS / LDS + CP , a hybrid method well suited for solving WCSPs in on-line contexts. Experiments show that our rerouting enables to accept an average of 67% of demands that would be rejected otherwise.

System design and network requirements for interactive multimedia

In recent years, there has been a strong interest in transmitting compressed video over packet switched networks, such as asynchronous transfer mode (ATM). Previous work has dealt with transmitting MPEG over constant bit rate (CBR) and variable bit rate (VBR) services of ATM. The available bit rate (ABR) service of ATM is expected to be much more cost effective than CBR or VBR. However, there hasn't been much work done on running interactive client/server applications (for example, video on demand) over ABR. We have developed a framework to design interactive video systems transmitting MPEG video over the ATM ABR service. We have developed models to determine the network connection parameters required to run interactive client/server multimedia applications over an ATM network using the ABR service. We solve our model using real-time dynamic equilation (RTDE) analysis. We conclude that by proper dimensioning of the buffers at the client and the server, it is possible to run interactive video over the ATM ABR service.

System design and network requirements for interactive multimedia

In recent years, there has been a strong interest in transmitting compressed video over packet switched networks, such as asynchronous transfer mode (ATM). Previous work has dealt with transmitting MPEG over constant bit rate (CBR) and variable bit rate (VBR) services of ATM. The available bit rate (ABR) service of ATM is expected to be much more cost effective than CBR or VBR. However, there hasn't been much work done on running interactive client/server applications (for example, video on demand) over ABR. We have developed a framework to design interactive video systems transmitting MPEG video over the ATM ABR service. We have developed models to determine the network connection parameters required to run interactive client/server multimedia applications over an ATM network using the ABR service. We solve our model using real-time dynamic equilation (RTDE) analysis. We conclude that by proper dimensioning of the buffers at the client and the server, it is possible to run interactive video over the ATM ABR service.

H∞–BASED FLOW CONTROL FOR ATM NETWORKS WITH MULTIPLE BOTTLENECKS

In this paper, the implementation of an H∞ controller, designed in another work for the flow control in communication networks with a single bottleneck, is considered for asynchronous transfer mode (ATM) networks with multiple bottlenecks. The controller calculates the data sending rates by using the information about the queue lengths at the switches. To observe the performance of the system in real ATM networks, a number of simulations are realised for certain realistic cases and the results are presented.

Submission to CAC

Asynchronous transfer mode (ATM) is the base for future telecommunication network. The greatly variable requirements for different applications, especially in video and data traffic, make high demands on the development of traffic control in ATM networks. Speaking about Quality of Service (QoS), in ATM there is a traffic control mechanism, which ensures the standard requested by a new application or service. In the following paper an introduction to traffic control mechanism in ATM known as a connection admission control (CAC) and appropriate CAC method are presented.

Intelligent Leaky Bucket Algorithms for Sustainable-Cell-Rate Usage Parameter Control in ATM Networks

In this paper, we propose two intelligent leaky bucket algorithms for sustainable-cell-rate usage parameter control of multimedia transmission in asynchronous transfer mode networks. One is the fuzzy leaky bucket algorithm, in which a fuzzy increment controller (FIC) is incorporated with the conventional leaky bucket algorithm; the other is the neural fuzzy leaky bucket algorithm, where a neural fuzzy increment controller (NFIC) is added with the conventional leaky bucket algorithm. Both the FIC and the NFIC properly choose the long-term mean cell rate and the short-term mean cell rate as input variables to intelligently determine the increment value. Simulation results show that both intelligent leaky bucket algorithms have significantly outperformed the conventional leaky bucket algorithm, by responding about 160% faster when taking control actions against a nonconforming connection while reducing as much as 50% of the queueing delay experienced by a conforming connection. In addition, the neural fuzzy leaky bucket algorithm outperforms the fuzzy leaky bucket algorithm, in aspects of three performance measures such as selectivity, responsiveness, and queueing delay, especially when the traffic flow is bursty, dynamic, and nonstationary.

Virtual network embedding in the cycle

We consider a problem motivated by the design of Asynchronous transfer mode (ATM) networks. Given a physical network and an all-to-all traffic, the problem consists in designing a virtual network with a given diameter, which can be embedded in the physical one with a minimum congestion (the congestion is the maximum load of a physical link). Here we solve the problem when the physical network is a ring. We give an almost optimal solution for diameter 2 and bounds for large diameters.

Traffic splitting in a network: split traffic models and applications

The contemporary high-speed networks, e.g. the Internet and asynchronous transfer mode (ATM) networks provide a convenient and cost-effective communication platform to carry the emerging multimedia applications. However, problems, such as network congestion caused by overloaded traffic get worse day by day. Thus, how to properly control the system while maintaining the quality of service (QoS) for users becomes an important and challenging issue. To reach the goal of QoS guarantee, load sharing or traffic balancing is one of important techniques to improve the whole network performance. In this paper, we focus on the probabilistic routing policy and analyze split traffic models under such a probabilistic routing policy with input traffic models of the batch Markovian arrival process (BMAP) and discrete-time BMAP (D-BMAP) which can be employed to characterize the multimedia traffic in current and future networks. We successfully show that the split traffic on each routing path from an original BMAP (D-BMAP) input is still a BMAP (D-BMAP). The detailed traffic structure is also acquired. Applying traffic splitting along with the output process characterization, we propose a network-wise performance evaluation method suitable for mesh networks with a probabilistic routing algorithm to get the end-to-end delay, delay variance, and cell loss probability. With numerical experiments, we show that (i) the probabilistic routing policy with a random routing matrix performs well for systems; (ii) the proposed method of network-wise performance analysis has good accuracy.

Centralized Flow Control Scheme for Rate-based Networks

This paper describes the Centralized Flow Control Scheme (CFCS) for a network that uses rate-based flow and congestion control. An example of such a network is an Asynchronous Transfer Mode (ATM) network using the Available Bit Rate (ABR) service. CFCS is a centralized control scheme in which a Network Controller Switch (NCS) maintains the current information of the network such as the number of Virtual Circuits (VCs) active at each switch, available capacity at each switch and rate assigned for each active VC. In order to do this it maintains a Rate Allocation Table (RAT). In our scheme, NCS is the main network controller switch with enough processing power and other switches in the network are the switches without processing power and they do not execute flow control algorithm. We call such switches as Passive Switches (PAS). PAS are controlled by NCS. Thus, in this scheme, the NCS controls the overall operation of the network by allocating rates to ABR connections with the help of RAT. CFCS can achieve zero cell loss, high utilization of links, maintains fairness in allocating bandwidth, it reduces transient response time. Moreover, it needs less feedback information for control and need less parameter to set by users and network administrators. We show the effectiveness of our scheme by simulation experiments.

Note on the feedback control algorithms used in high-speed networks

In this article we analyze a linear feedback control algorithm particularly suited to the Available Bit Rate service class in Asynchronous Transfer Mode (ATM) networks. We envisage the development of a closed-loop, fluid approximation model, in which the propagation delay is reflected across the network, while the rate of transmission and the queue occupancy are modeled as fluids. Using a fluid model has the advantage to permit a simplified study of the network behavior. The above model is described with the continuous-time system of delay-differential equations, which is solved semi-analytically. The contribution of this work is to provide a sending rate scheme, which is based on both a rate control function and a suitable fuzzy function for network load and delay. It is shown that the concept of fuzzy set theory can be proved beneficial in the analysis of network load and delay, whose uncertainty is an inherent characteristic. Finally, the developments in the area of time-delay systems control allow to compute exact stability bounds of the Round Trip Time (RTT) and thus to indicate if the connection is in a stable state. †E-mail: mbekakos@ee.duth.gr ‡E-mail: dj.evans@ntu.ac.uk

On the Remaining Service Time upon Reaching a Given Level in M/G/1 Queues

The ability of effectively finding the distribution of the remaining service time upon reaching a target level in M/G/1 queueing systems is of great practical importance. Among other things, it is necessary for the estimation of the Quality-of-Service (QoS) provided by Asynchronous Transfer Mode (ATM) networks. The previous papers on this subject did not give a comprehensive solution to the problem. In this paper an explicit formula for this distribution is given. This formula is general as it includes any initial level of the length of the queue, any type of service distribution (heavy tails) and any traffic intensity ρ. Moreover, it is easy to use and fast in computation. To show this several numerical examples are presented. In addition, a solution of the similar problem in G/M/1 queues (which is the distribution of the remaining interarrival time) is given.

Traffic splitting in a network: split traffic models and applications

The contemporary high-speed networks, e.g. the Internet and asynchronous transfer mode (ATM) networks provide a convenient and cost-effective communication platform to carry the emerging multimedia applications. However, problems, such as network congestion caused by overloaded traffic get worse day by day. Thus, how to properly control the system while maintaining the quality of service (QoS) for users becomes an important and challenging issue. To reach the goal of QoS guarantee, load sharing or traffic balancing is one of important techniques to improve the whole network performance. In this paper, we focus on the probabilistic routing policy and analyze split traffic models under such a probabilistic routing policy with input traffic models of the batch Markovian arrival process (BMAP) and discrete-time BMAP (D-BMAP) which can be employed to characterize the multimedia traffic in current and future networks. We successfully show that the split traffic on each routing path from an original BMAP (D-BMAP) input is still a BMAP (D-BMAP). The detailed traffic structure is also acquired. Applying traffic splitting along with the output process characterization, we propose a network-wise performance evaluation method suitable for mesh networks with a probabilistic routing algorithm to get the end-to-end delay, delay variance, and cell loss probability. With numerical experiments, we show that (i) the probabilistic routing policy with a random routing matrix performs well for systems; (ii) the proposed method of network-wise performance analysis has good accuracy.

Provisioning multicast QoS for WDM-based optical wireless networks

Wavelength division multiplexing (WDM)-based optical technique is becoming the right choice for the next-generation Internet infrastructure to transport high-speed Internet Protocol traffic. Today, wireless asynchronous transfer mode (WATM) network plays the leading role; undoubtedly it will be replaced with wireless WDM (WWDM) network to provide higher quality of service for mobile users. In addition many conventional and emerging applications, such as teleconferencing and distributed games, require multicasting increasingly. Many efforts to support multicasting for WATM networks have been offered, yet there are rarely addressed on WWDM networks. Moreover, conventional operations to set up and tear down optical connections in WDM networks are unable to apply directly to WWDM networks. User's mobility may make the operating optical-multicast-tree to change into very inefficient. The tree may expand and consume excessive resources, and even lost connection due to violating the associated QoS constraints. In this paper, a Constrained Optical Tree Migration Scheme (COTMS) is proposed to support real-time multicast services for WWDM networks. COTMS efficiently deals with the constrained tree migration problem and adapts easily to the operations of WDM. Simulation results reveal that COTMS can markedly reduce the resources used by per optical tree, thus achieving both low handoff-dropping/join-blocking rate and high-resource utilization. Moreover, COTMS is also suitable for ad-hoc networks with multiple different frequencies for multicast routing.