Application of Asynchronous Transfer Mode (Atm) technology to Picture Archiving and Communication Systems (Pacs): A survey

Broadband Integrated Services Digital Network (R-ISDN) provides a range of narrowband and broad-band services for voice, video, and multimedia. Asynchronous Transfer Mode (ATM) has been selected by the standards bodies as the transfer mode for implementing B-ISDN; The ability to digitize images has lead to the prospect of reducing the physical space requirements, material costs, and manual labor of traditional film handling tasks in hospitals. The system which handles the acquisition, storage, and transmission of medical images is called a Picture Archiving and Communication System (PACS). The transmission system will directly impact the speed of image transfer. Today the most common transmission means used by acquisition and display station products is Ethernet. However, when considering network media, it is important to consider what the long term needs will be. Although ATM is a new standard, it is showing signs of becoming the next logical step to meet the needs of high speed networks; This thesis is a survey on ATM, and PACS. All the concepts involved in developing a PACS are presented in an orderly manner. It presents the recent developments in ATM, its applicability to PACS and the issues to be resolved for realising an ATM-based complete PACS. This work will be useful in providing the latest information, for any future research on ATM-based networks, and PACS

Design Related Investigations for Media Access Control Protocol Service Schemes in Wavelength Division Multiplexed All Optical Networks

All-optical networks (AON) are emerging through the technological advancement of various optical components, and promise to provide almost unlimited bandwidth. To realise true network utilisation, software solutions are required. An active area of research is media access control (MAC) protocol. This protocol should address the multiple channels by wavelength division mutiplexing (WDM) and bandwidth management. Token-passing (TP) is one such protocol, and is adopted due to its simplicity and collisionless nature. Previously, this protocol has been analysed for a single traffic type. However, such a study may not substantiate the protocol's acceptance in the AON design. As multiple traffic types hog the network through the introduction multimedia services and Internet, the MAC protocol should support this traffic. Four different priority schemes are proposed for TP protocol extension, and classified as static and dynamic schemes. Priority assignments are a priori in static scheme, whereas in the other scheme, priority reassignments are carried out dynamically. Three different versions of dynamic schemes are proposed. The schemes are investigated for performance through analytical modelling and simulations. The semi-Markov process (SMP) modelling approach is extended for the analyses of these cases. In this technique, the behaviour of a typical access node needs to be considered. The analytical results are compared with the simulation results. The deviations of the results are within the acceptable limits, indicating the applicability ofthe model in all-optical environment. It is seen that the static scheme offers higher priority traffic better delay and packet loss performance. Thus, this scheme can be used beneficially in hard real-time systems, where knowledge of priority is a priori. The dynamic priority scheme-l is more suitable for the environments where the lower priority traffic is near real-time traffic and loss sensitive too. For such a scheme, a larger buffer with smaller threshold limits resulted in improved performance. The dynamic scheme-2 and 3 can be employed to offer equal treatment for the different traffic types, and more beneficial in future AONs. These schemes are also compared in their performance to offer constant QoS level. New parameters to facilitate the comparison are proposed. It is observed that the dynamic scheme-l outperforms the other schemes, and these QoS parameters can be used for such QoS analysis. It is concluded that the research can benefit the design of the protocol and its service schemes needed in AON system and its applications

Simulation analysis of FDDI network using NETWORK II.5 software package

In recent years, one of the most exciting advances in media has been the use of fiber optics in LANs. The bandwidth provided by Fiber Optic Technology has drastically increased the number of new applications that can be supported by communication networks. In order to support a variety of services, in 1986, the American National Standard Institute (ANSI) Accredited Standards Committee (ASC) X3, and the ASC X3T9.5 Task Group developed a new standard; the Fiber Distributed Data Interface (FDDI) [1]. This is a high speed (100 Mbps) optical communication network based on a token passing mode of operation. The Medium Access Control (MAC) Protocol selected for this network attempts to provide priority services, as well as bounded delay transmission for real time applications [2]. This thesis presents results for the Voice-Data performance of the Medium Access Control (MAC) protocol, selected for the FDDI network, using the NETWORK 11.5 [6] software package. This protocol can provide priority services to different types of traffic, as well as guarantee bounded delays for real-time applications. The effect of various system parameters on performance is investigated

Performance of a ATM Lan switching fabric

This thesis provides a focus on the architecture of a high-speed packet switching fabric and its performance. The switching fabric is suited for existing transparent protocols, based on Asynchronous Transfer Mode (ATM) technology and standards in an environment of Local Area Network (LAN). A high-speed switching fabric architecture which adopts Time Division mode and bases on a shared medium approach is proposed. This is an architecture for nonblocking performance, no congestion and high reliability. Its principle for performance is a method of sequentially scheduling the inputs and the transferring of bits in parallel. To study the performance of the switching fabric architecture one uses OPNET communication simulation software. Some parameters including the throughputs, the transfer (the switching fabric) delay, the switching overflow and the packet size in the buffer (the input buffer and the output buffer) are implemented through the simulation. And finally, an analysis for the results of the simulation for local ATM IDS fabric architecture is discussed. The results display an architecture that provides a rational design with some expected characteristics

Real time communications in manufacturing

Colloque avec actes et comité de lecture.Manufacturing applications are today distributed and integrated, relying on different types of communication networks to interconnect the different levels of the systems' architecture. This paper discusses the main topics on manufacturing communications from the applications requirements to the most common solutions derived to fulfill them. Temporal and spatial properties of the data to be exchanged are analysed. Data is classified as periodic, aperiodic and sporadic and, for these types, the communication system performance requirements are identified with emphasis on the real-time aspects. A similar discussion is carried on in what concerns the size of data to be transferred per transaction. The use of multimedia and of wide-area communication is also briefly explored. Solutions for different levels of the CIM (Computer Integrated Manufacturing) architecture are identified and an overview of their characteristics is presented. This includes a short description of their organization under the OSI Reference Model and a more detailed discussion on techniques for traffic scheduling. This discussion is mainly focussed on the techniques to control the access to the communications medium and on the use of static or dynamic scheduling. This has essentially in consideration the fulfilment of the data temporal constraints. A short overview of the possibilities opened by the use of Internet in these applications is also included