Asynchronous Transfer Mode Cell Research Articles

VLSI Design of A Chip With High Speed Atm Switch-A Review

In current computer communication network, it is overwhelmed by two technologies, in particular Asynchronous Transfer Mode (ATM) and Internet Protocol (IP). Association situated ATM is the awesome constant administrations which require ensured nature of-administration like video conferencing. Be that as it may, connectionless IP is more proficient than ATM for non-ongoing administrations like email. Right now, the significant exploration challenge is on the most proficient method to coordinate ATM and IP into a solitary network effectively. It is shown by the acknowledgment of the highlight of the A/I Net architecture: the A/I Switch. In this postulation, a VLSI execution of a multistage self-steering ATM switch texture which is one of the vital parts of the A/I Switch will be presented. The size of the switch model is 16x16. The chip is intended to work at the very least frequency of 100MHz and the framework is equipped for dealing with the OC-12 (622 Mbps) connect rate. In view of a piece cut architecture, the whole 16x16 switch is acknowledged utilizing four indistinguishable chips. It accomplishes elite by using dispersed control and accelerate with the input-output buffering technique. A need structure, which upholds four-level, permits the postponement delicate ATM cells to be switched with the briefest inertness. It likewise empowers the non-interleaving directing plan of IP cells.

Digital television transmission based on asynchronous transfer mode

This paper introduces a method to realize digital television transmission based on asynchronous transfer mode (ATM), a technology based on fast packet switching. Choosing the integral multiple length of an ATM cell payload to equal to the length of an MPEG transport stream packet, an MPEG transport stream packet can be inextenso loaded by several ATM cells and transformed into ATM cells. Using ATM virtual connection technology and B-ISDN, the interoperability between ATM and DTV may be realized, and DTV signal transmission may also be realized finally.

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.

An Efficient Network-Switch Scheduling for Real-Time Applications

Bursts consist of a varying number of asynchronous transfer mode cells corresponding to a datagram. Here, we generalized weighted fair queueing to a burst-based algorithm with preemption. The new algorithm enhances the performance of the switch service for real-time applications, and it preserves the quality of service guarantees. We study this algorithm theoretically and via simulations.

An integrated FEC coding scheme for ATM transmission over regenerative satellite networks

The application of asynchronous transfer mode (ATM) on both wireless and satellite networks requires system adaptation. This adaptation has to improve the overall system's performance, and achieve high quality-of-service classes approaching that for fibre-optic communications. In this paper, a new integrated forward-error-correction (FEC) coding scheme is introduced for ATM transmission over regenerative satellite networks. The proposed FEC scheme is a concatenation of two Reed–Solomon codes tailored for the header and payload parts of the ATM cell. This integrated coding scheme is shown to significantly improve the cell loss ratio as compared to the standard CRC code used in the ATM cell header. We obtain both upper and lower performance bounds for the concatenated code and check their accuracy when compared to exact system's performance. Both analytical and simulation results show that a cell loss ratio and bit-error rate (BER) of 10−25 and 10−7 can be, respectively, achieved with minimum delay requirements on the SATCOM link. Finally, an approximation for the system's throughout is obtained. It is shown that using a hybrid selective-repeat automatic-repeat-request (SR-ARQ) with the RS code, a large throughput of approximately 0.843 can be achieved at BERs lower than 10−7 for data services. Copyright © 2005 John Wiley & Sons, Ltd.

Evolvable hardware using context switchable fuzzy inference processor

To achieve real-time performance for some applications of fuzzy systems it is necessary to realise the inference module in hardware. By the same token, real-time applications of evolvable fuzzy hardware systems require the realisation of systems as hardware that can be conveniently reconfigured. A good example of such a scenario is illustrated for the case of asynchronous transfer mode cell scheduling. Since the domain rule-set is expected to evolve during normal operation, it is imperative that the hardware supporting the fuzzy reasoning should be easily reconfigurable. To address this requirement a reconfigurable fuzzy inference chip (RFIC) is described that supports online rule-set reconfigurability. The overall methodology of designing evolvable fuzzy hardware systems based on an RFIC as the core inference processor is presented. The RFIC is an in-system context-switchable inference processor for evolvable fuzzy hardware. Hardware architectural details of the RFIC are presented and its performance simulated to verify its functionality and applicability.

A novel turbo coding scheme for satellite ATM using reed-muller codes

Block turbo codes with trellis-based decoding are proposed for use in cell-based satellite communication. Shortened Reed-Muller (RM) codes are used as the component codes because their minimal trellis is known. Simulation results for RM turbo codes and shortened RM turbo codes are presented over additive white Gaussian noise and Rayleigh fading channels. The performance of the shortened codes with different shortening patterns are shown. In some cases, the codes have the unequal error protection property, useful in asynchronous transfer mode cell formatting. In order to test the suitability of the proposed coding scheme from a practical point of view, the effect of channel impairments, including channel signal-to-noise ratio mismatch and carrier phase offset, are investigated.

A Simulation Study of IPv6 to ATM Flow-Mapping Techniques

This paper presents a simulation study into the problem of conveying Internet protocol (IP) packets over an asynchronous transfer mode (ATM) network in cases where quality of service (QoS) is an important consideration. The main focus of the work is on mapping IP packet flows onto ATM cell streams, particularly for the purpose of maintaining the QoS requirements of continuous media (audio and video) traffic. Simulation models of two different flow-mapping scenarios are described, and results of an evaluation of the flow-mapping process are presented. These results are also used to validate an analytical solution to the problem, which has been developed in a separate but related piece of work.

TCP Explicit Congestion Notification over ATM-UBR: A Simulation Study

The enhancement of Transmission Control Protocol’s (TCP’s) congestion control mechanisms using Explicit Congestion Notification (ECN) over Asynchronous Transfer Mode (ATM) networks is overviewed. TCP’s congestion control is enhanced so that congestion is indicated by not only packet losses as is currently the case but an agent implemented at the ATM network’s edge as well. The novel idea uses EFCI (Explicit Forward Congestion Indication) bits (available in every ATM cell header) to generalize the ECN response to the UBR (Unspecified Bit Rate) service, notify congestion, and adjust the credit-based window size of the TCP. The authors’ simulation experiments show that TCP ECN achieves significantly lower cell loss, packet retransmissions, and buffer utilization, and exhibits better throughput than (non-ECN) TCP Reno.

Mechanism for shaping the emitted traffic at ATM terminal‐points

AbstractA mechanism for controlling the emitted traffic to asynchronous transfer mode (ATM) network, system design and implementation architectures are introduced. Specifically, the effective rate of a stream, defined under certain multiplexing conditions and quality‐of‐service specifications, is enforced to desired values by controlling the cell emission rate of the generated bursts. The traffic shaping mechanism is closely associated to an ATM transmitter, which is mainly responsible for ATM cell assembly and header error control. The mechanism has been designed to support data communication services. The whole system has been implemented as a VLSI circuit. Copyright © 2002 John Wiley & Sons, Ltd.

Performance models of handover protocols and buffering policies in mobile wireless ATM networks

Due to the connection-oriented nature of the asynchronous transfer mode (ATM), one of the challenges in mobile wireless ATM (WATM) systems is the management of terminal handovers. When ATM connections are reestablished to follow terminals moving between areas covered by distinct base stations, seamless handover protocols are necessary to guarantee that ATM cells are delivered to terminals in the correct order, with cell loss rate and delay that satisfy the contracted quality of service (QoS). A promising approach to meet QoS requirements is based on the use of handover buffers at the (destination) base station, where transmitted cells are stored while the connection is being reestablished. Up to date, only simulation and experimental results are available to determine the performance of such protocols and buffering schemes. This paper presents the first attempt to develop an analytical modeling approach to estimate the performance of handover protocols making use of handover buffers at the base station. By incorporating several approximations, the proposed models allow designers to simultaneously take into account numerous system parameters, including handover buffer size, sustainable and peak cell rates of the ATM connection, terminal offered load, and time needed to reestablish the ATM connection. Analytical performance predictions are shown to closely match results of detailed simulation experiments, thus demonstrating the suitability of the proposed modeling framework for the selection of the most adequate solution to handle handover and provide the QoS required by end users.

An OFDM-based wireless ATM transmission system assisted by a cyclically extended PN sequence for future broad-band mobile multimedia communications

An orthogonal frequency division multiplexing (OFDM)-based wireless asynchronous transfer mode (ATM) transmission system is described that is suitable for the future broad-band mobile multimedia communications. In the proposed system, guard symbols, which are cyclically extended by repeating the information symbols, are inserted before and after serial-to-parallel converted wireless ATM data symbols for OFDM transmission. These symbols are used for both wireless ATM frame synchronization and deciding the discrete Fourier transformation (DFT) start point at the receiver. A cyclically extended pseudorandom noise (PN) sequence is inserted into some of the OFDM transmission subchannels at fixed intervals and used to estimate the phase rotation, frequency offset, and delay characteristics. The proposed system does not use symbol-by-symbol guard-interval insertion or removal circuits, as do conventional OFDM systems. With this system, it is easy to estimate the phase rotation, frequency offset, and delay characteristics and to synchronize wireless ATM cells. Computer simulation showed that the bit error rate (BER) performance of the proposed system is better than that of a conventional symbol-by-symbol OFDM system.

System-level data-format exploration for dynamically allocated data structures

System-level exploration of memory organizations is a key issue in successful implementation of data dominated applications based on dynamically allocated data structures involving records and access keys. This paper presents a formalized technique for exploring different memory data-format alternatives when only the system level functional behavior of the application has been defined. Our data-format exploration approach allows to substantially minimize the number of accessed bits by rearranging the format of the data records. The technique exploits parallelism in the data transfer by analyzing the dependencies between data-record accesses. As a result, significant reduction in memory size, bandwidth, and power are obtained. We have validated our techniques using several real-life asynchronous transfer mode cell processing applications, where we have obtained reductions in memory size (up to 20%), power (up to a 60%), and bandwidth.

Error concealment in MPEG video streams over ATM networks

When transmitting compressed video over a data network, one has to deal with how channel errors affect the decoding process. This is particularly a problem with data loss or erasures. In this paper we describe techniques to address this problem in the context of asynchronous transfer mode (ATM) networks. Our techniques can be extended to other types of data networks such as wireless networks. In ATM networks channel errors or congestion cause data to be dropped, which results in the loss of entire macroblocks when MPEG video is transmitted. In order to reconstruct the missing data, the location of these macroblocks must be known. We describe a technique for packing ATM cells with compressed data, whereby the location of missing macroblocks in the encoded video stream can be found. This technique also permits the proper decoding of correctly received macroblocks, and thus prevents the loss of ATM cells from affecting the decoding process. The packing strategy can also be used for wireless or other types of data networks. We also describe spatial and temporal techniques for the recovery of lost macroblocks. In particular, we develop several optimal estimation techniques for the reconstruction of missing macroblocks that contain both spatial and temporal information using a Markov random field model. We further describe a sub-optimal estimation technique that can be implemented in real time.

Two-dimensional CRC for efficient transmission of ATM cells over CDMA

An integrated system for code-division multiple access (CDMA) radio access to the asynchronous transfer mode (ATM) network is considered. The inherently high error rate associated with the Rayleigh fading channel is overcome by two-dimensional CRC codes for efficient ATM-CDMA interfacing. Simulations show promising error probability performance with low coding redundancy.

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.

Protocol-aided channel equalization in wireless ATM

We study the equalization problem in time division multiple access wireless asynchronous transfer mode (ATM) systems. Aiming at minimizing the overhead associated with equalization, we propose a protocol-aided channel equalization (PACE) approach for wireless ATM. Specifically, the medium access control (MAC) and data link control (DLC) protocols are exploited to provide known ATM cell headers to the receiver at the base station. A blind channel estimation-decision feedback equalizer (BCE-DFE) algorithm is developed for uplink data transmissions. There are two advantages of the BCE-DFE algorithm: the elimination of training symbols for uplink data bursts and the removal of channel estimation error propagation suffered by conventional block equalization schemes. Simulation results show the BCE-DFE has a robust performance for wireless ATM uplink data transmissions over fast time-varying channels.

The UniMIN switch architecture for large-scale ATM switches

A general expansion architecture is proposed that can be used in building large-scale switches using any type of asynchronous transfer mode (ATM) switch. The proposed universal multistage interconnection network (UniMIN) switch is composed of a buffered distribution network (DN) and a column of output switch modules (OSMs), which can be any type of ATM switch. ATM cells are routed to their destination using a two-level routing strategy. The DN provides each incoming cell with a self-routing path to the destined OSM, which is the switch module containing the destination output port. Further routing to the destined output port is performed by the destination OSM. Use of the channel grouping technique yields excellent delay/throughput performance in the DN, and the virtual FIFO concept is used for implementing the output buffers of the distribution module without internal speedup. We also propose a "fair virtual FIFO" to provide fairness between input links while preserving cell sequence. The distribution network is composed of one kind of distribution module which has the same size as the OSM, regardless of the overall switch size N. This gives good modular scalability in the UniMIN switch. Performance analysis for uniform traffic and hot-spot traffic shows that a negligible delay and cell loss ratio in the DN can be achieved with a small buffer size, and that DN yields robust performance even with hot-spot traffic. In addition, a fairness property of the proposed fair virtual FIFO is shown by a simulation study.

On the optimality and the asymptotic optimality of the smallest weighted available buffer policy

A major design challenge of Asynchronous Transfer Mode (ATM) networks is to efficiently provide the quality of service (QOS) specified by users with different demands. We classify sources so that sources in one class join the same buffer and have the same requirement for the ATM cell loss ratio. It is important to search for the service discipline that minimizes the accumulated cell loss under the constraint that the cell loss ratios of the sources are proportional to their QOS requirements. In this paper we consider a model that has N finite buffers and a single server. Buffer i, of size B i , is assigned a positive number w i . The server serves from one of the non-empty buffers whose indices are equal to argmin w i (B i -Q i ), where Q i is the queue length of buffer i. This scheduling policy is called the smallest weighted available buffer policy (SWAB). We show that in a completely symmetric setting, the SWAB policy minimizes the discounted expected loss of cells under some technical conditions. For asymmetric models, we show that the accumulated loss of cells of the SWAB service discipline is asymptotically optimal under heavy traffic conditions in the diffusion limit. Finally, we obtain the expression of w i so that the cell loss ratios of the sources in the diffusion limit are proportional to their QOS requirements.

On the optimality and the asymptotic optimality of the smallest weighted available buffer policy

A major design challenge of Asynchronous Transfer Mode (ATM) networks is to efficiently provide the quality of service (QOS) specified by users with different demands. We classify sources so that sources in one class join the same buffer and have the same requirement for the ATM cell loss ratio. It is important to search for the service discipline that minimizes the accumulated cell loss under the constraint that the cell loss ratios of the sources are proportional to their QOS requirements. In this paper we consider a model that hasNfinite buffers and a single server. Bufferi, of sizeBi, is assigned a positive numberwi. The server serves from one of the non-empty buffers whose indices are equal to argminwi(Bi-Qi), whereQiis the queue length of bufferi. This scheduling policy is called the smallest weighted available buffer policy (SWAB). We show that in a completely symmetric setting, the SWAB policy minimizes the discounted expected loss of cells under some technical conditions. For asymmetric models, we show that the accumulated loss of cells of the SWAB service discipline is asymptotically optimal under heavy traffic conditions in the diffusion limit. Finally, we obtain the expression ofwiso that the cell loss ratios of the sources in the diffusion limit are proportional to their QOS requirements.