Link level modelling techniques for analysing the configuration of link adaptation algorithms in mobile radio networks

The operation of Link Adaptation algorithms is based on channel quality estimates. It is therefore important to analyse the performance of such algorithms with link level models that properly capture the channel conditions and dynamics. Previous research [1] concluded that the use of simple link level models does not give an accurate prediction of the estimated performance of Link Adaptation algorithms. Following this previous work, this paper shows that the link level model considered for the study of Link Adaptation algorithms can also influence the decisions regarding the optimum configuration of the algorithm

Performance and configuration of link adaptation algorithms with mobile speed

Link Adaptation is an adaptive radio link technique that selects a transport mode, from a set of predefined modes of varying robustness, depending on the channel quality conditions and dynamics. Previous work has shown the need to adapt the configuration of the Link Adaptation algorithm to certain operating conditions such as the system load. Since the channel quality dynamics are also influenced by the user speed, this paper investigates the impact of the mobile speed on the performance and configuration of Link Adaptation algorithm

On the importance of using appropriate link-to-system interfaces for the study of link adaptation

Link Adaptation is an adaptive radio link technique that selects a transport mode, from a set of predefined modes of varying robustness, depending on the channel quality conditions and dynamics. It is therefore very important, when analysing the performance and operation of Link Adaptation, to properly capture such conditions and dynamics. In this context, this paper investigates the effect that different link-to-system level interfaces have on the study of Link Adaptation, in particular on its throughput performance and associated signalling cost

Deploying a middleware architecture for next generation mobile systems

Although 2G systems quite adequately cater for voice communications, today demand is for high-speed access to data centric applications and multimedia. Future networks have been designed to provide higher rates for data transmission, but this will be complemented by higher speed access to services via hotspots using secondary wireless interfaces such as Bluetooth or WLAN. With a wide range of applications that may be developed, a growing number of short range wireless interfaces that may be deployed, and with mobile terminals of different capabilities, a means to integrate all these variables in order to facilitate provision of services is desirable. This paper describes an architecture involving the use of middleware that makes software development independent of the specific wireless platfor

Evaluation of a prototype interface for structured document retrieval

Document collections often display either internal structure, in the form of the logical arrangement of document components, or external structure, in the form of links between documents. Structured document retrieval systems aim to exploit this structural information to provide users with more effective access to structured documents. To do this, the associated interface must both represent this information explicitly and support users in their browsing behaviour. This paper describes the implementation and user-centred evaluation of a prototype interface, the RelevanceLinkBar interface. The results of the evaluation show that the RelevanceLinkBar interface supported users in their browsing behaviour, allowing them to find more relevant documents, and was strongly preferred over a standard results interface

Multikilowatt hydrogen-nickel oxide battery system

The potential of the H2-NiO battery for terrestrial applications was assessed. A multicell design approach that differs significantly from the aerospace individual pressure vessel was used. A number of experimental 100-Ah cells were built to evaluate the new design concepts and components. The experimental cells provided the input needed for a multicell battery design. It is found that new multicell H2-NiO battery has a number of potential advantages for aerospace applications such as the manned space station. The advantages are discussed, and a design concept is presented for a multikilowatt battery in a lightweight pressure vessel