A new dynamic reservation integrated services multiple access (DRISMA) protocol is proposed for the emerging wireless ATM networks. Compared to other PRMA-based protocols, DRISMA has two distinctive features. First, while each voice station reserves isochronous channels by capturing minislots, both the capturing probability and the number of mini-slots per frame are adjusted dynamically to enha...

The Available Bit Rate is an important service class for ATM networks because it provides a rate control mechanism that enables to dynamically adjust the source rate to the amount of resources available in the network. We present in this paper an original design of an Explicit Rate based ABR algorithm: ERAQLES. It provides a dynamic evaluation of the level of available resources left unused in ...

A number of recent studies have investigated scheduling tech niques in support of variable bit rate VBR video When compared with constant bit rate CBR video VBR has a lower storage and bandwidth requirement while providing the same quality of images However a VBR video clip might exhibit a signi cant variance in the bit rate required to support its continuous display The previous studies have p...

This paper discusses some issues and possibilities for more eeective ABR (Available Bit Rate) traac management which arise from a careful consideration of various time scales present in an ATM networking environment. Since the ABR applications will typically use the remaining resources after CBR (Constant Bit Rate) and VBR (Variable Bit Rate) applications have been accommodated, the ABR rate sh...

An efficient bandwidth allocation scheme is proposed for supporting integrated services in wireless ATM networks. These include CBR, VBR and ABR types of traffic. The proposed scheme is based on A-PRMA for carrying ATM traffic in a dynamic TDMA type access system. It allows mobile users to adjust the reserved bandwidth according to their current demands and the wireless channel status. Extensiv...

CBR (Constant Bit Rate) video fluctuates in quality, while its multiplexing behaviour is easy to predict: the links can be loaded to almost 100%. VBR (Variable Bit Rate) video aims at constant quality, but as the bit rate fluctuates over time the links cannot be fully loaded. Because in unconstrained VBR video the bit rate fluctuation might be too large, capped VBR video is proposed as an alter...

The main aim of the research described in the paper was analyse the accuracy of photointerpretation of impervious surface using IKONOS images and its influence on the imperviousness factor determination. Two kinds of IKONOS image were chosen to tests: panchromatic and colour pansharp. Airborne ortopho (pixel size of 0.2m) was applied as a reference. Six operators, digitised three times, two kin...

In this paper I will give a model-theoretic account for structural realism. I will introduce the so-called ‘hierarchy of models’ which can be used to formally analyse the structure shared by a ‘high-level theory’ and the ‘phenomena’. I will show that structural empiricism (as characterized by Bueno (1997, 2000) and Van Fraassen (1980)) cannot be accommodated in the hierarchy of models and show ...

In recent years, a number of sophisticated architectures have been proposed to provide VoD service using multicast transmissions. Compared to their unicast counterparts, these multicast VoD systems are highly scalable and can potentially serve millions of concurrent users. Nevertheless, these systems are designed for streaming constant-bit-rate (CBR) encoded videos and thus cannot benefit from ...