On-board B-ISDN fast packet switching architectures. Phase 1: Study

The broadband integrate services digital network (B-ISDN) is an emerging telecommunications technology that will meet most of the telecommunications networking needs in the mid-1990's to early next century. The satellite-based system is well positioned for providing B-ISDN service with its inherent capabilities of point-to-multipoint and broadcast transmission, virtually unlimited connectivity between any two points within a beam coverage, short deployment time of communications facility, flexible and dynamic reallocation of space segment capacity, and distance insensitive cost. On-board processing satellites, particularly in a multiple spot beam environment, will provide enhanced connectivity, better performance, optimized access and transmission link design, and lower user service cost. The following are described: the user and network aspects of broadband services; the current development status in broadband services; various satellite network architectures including system design issues; and various fast packet switch architectures and their detail designs

On the design, implementation and experimental evaluation of a novel gateway architecture for the GSM Short Message Service

Congestion and capacity pi'ohIens of the existing mobile communication networks of the late eighties resulted in the demand for a brand new mobile telephony standard. Competition amongst the various existing standards implementation was fierce and lead to the availability of a plethora of incompatible networks and very little hope for the establishment of a global technology geared up to the expectancy of the users. Paging network were widely used as a cheaper alternative to voice enabled networks and were Offering users the ability to receive textual information while on the move. Bridging the gap between the paging world and the mobile communication world was essential. The Global System for Mobile communications was designed as the European answer. The European alternative was promising a feature rich, secure and truly global system with the added ability to handle two-way paging like functionalities with the Short Message Service (SMS). The success of a new service such as SMS relies heavily on its adoption by a majority of users. which in turn is mainly a consequence of the availability of software application gateways. In the mid nineties a Sheffield based software company realising the market needs teamed up with the University's research department to produce the first commercially available gateway architecture for the SMS. The resulting work is described in this thesis. The first part of the analysis examines the architecture of' a (ISM network and the building blocks of the SMS. The technical implementation is described and the fundamental properties examined such as roaming. routing, protocol limitations, usability and interoperahility problems. The specification and design of the gateway architecture is then addressed with an emphasis on character set conversion, routing and queLicing issues. The implementation details are then examined with a description of each of' the modules. The performance of the gateway is examined with the implenientation of a test bed fed by traffic generated by customers. The issues examined were: identification of bottlenecks, protocol efficiencies and an analysis of the chosen queueing model implementation. The second part of the analysis presents the results obtained from the measurements taken for a period of a year. Arm analytical model was formulated to validate the results from the measurements. The comparison revealed the ability of the model to simulate the behaviour of the gateway under medium to heavy loads and highlighted the areas that would be most affected by optimisation. The important factors limiting throughput and quality of service were di scoverecl in the capacity of the connections to network operators and policy chosen for the message queues. An alternative queueing discipline is proposed that would lead to increased fairness offered to the wide variety of applications connected to the gateway and the network operators through a single link of' known capacity. Interactive conversations such as quizzes and gaines based are offered low latency while more bandwidth demanding ones such as mass voting applications benefit from very high throughput. The overall gateway,architecture described was the first one of its kind and consequently each of its module was designed and implemented from scratch. As a result Dialogue (Tommnunicatmons benefited l'i'omn the novelty and head start needed in a fierce competitive market to position itself as a market leader ]it mobile applications and services, competing with global companies such as Logica. Ericcson or Microsoft

A novel approach for the hardware implementation of a PPMC statistical data compressor

This thesis aims to understand how to design high-performance compression algorithms suitable for hardware implementation and to provide hardware support for an efficient compression algorithm. Lossless data compression techniques have been developed to exploit the available bandwidth of applications in data communications and computer systems by reducing the amount of data they transmit or store. As the amount of data to handle is ever increasing, traditional methods for compressing data become· insufficient. To overcome this problem, more powerful methods have been developed. Among those are the so-called statistical data compression methods that compress data based on their statistics. However, their high complexity and space requirements have prevented their hardware implementation and the full exploitation of their potential benefits. This thesis looks into the feasibility of the hardware implementation of one of these statistical data compression methods by exploring the potential for reorganising and restructuring the method for hardware implementation and investigating ways of achieving efficient and effective designs to achieve an efficient and cost-effective algorithm. [Continues.

A conformance test framework for the DeviceNet fieldbus

The DeviceNet fieldbus technology is introduced and discussed. DeviceNet is an open standard fieldbus which uses the proven Controller Area Network technology. As an open standard fieldbus, the device conformance is extremely important to ensure smooth operation. The error management in DeviceNet protocol is highlighted and an error injection technique is devised to test the implementation under test for the correct error-recovery conformance. The designed Error Frame Generator prototype allows the error management and recovery of DeviceNet implementations to be conformance tested. The Error Frame Generator can also be used in other Controller Area Network based protocols. In addition, an automated Conformance Test Engine framework has been defined for realising the conformance testing of DeviceNet implementations. Automated conformance test is used to achieve consistent and reliable test results, apart from the benefits in time and personnel savings. This involves the investigations and feasibility studies in adapting the ISO 9646 conformance test standards for use in DeviceNet fieldbus. The Unique Input/Output sequences method is used for the generation of DeviceNet conformance tests. The Unique Input/Output method does not require a fully specified protocol specification and gives shorter test sequences, since only specific state information is needed. As conformance testing addresses only the protocol verification, it is foreseen that formal method validation of the DeviceNet protocol must be performed at some stage to validate the DeviceNet specification