A medium to long term roadmap for access services on DTV

DTV4All is a project partly funded by the European Commission (CIP ICT Policy Support Programme) to facilitate the provision of access services on digital television across the European Union. Access services literally help their users access the content of television programmes. Important examples of access services for people who are hard of hearing or deaf are subtitles and deaf signing provided with television programmes to allow their users to more fully appreciate the programme dialogue. The primary aim of the DTV4All project is to encourage the roll out of access services on digital television across the EC. To do this the project targets eroding the barriers to the roll out of access services by making clear what these barriers are and how they may be overcome. This paper provides an overview of the progress the project has made in its first two years in meeting this target

Sound propagation and force chains in granular materials

Granular materials are inherently heterogeneous, leading to challenges in formulating accurate models of sound propagation. In order to quantify acoustic responses in space and time, we perform experiments in a photoelastic granular material in which the internal stress pattern (in the form of force chains) is visible. We utilize two complementary methods, high-speed imaging and piezoelectric transduction, to provide particle-scale measurements of both the amplitude and speed of an acoustic wave in the near-field regime. We observe that the wave amplitude is on average largest within particles experiencing the largest forces, particularly in those chains radiating away from the source, with the force-dependence of this amplitude in qualitative agreement with a simple Hertzian-like model of particle contact area. In addition, we are able to directly observe rare transient force chains formed by the opening and closing of contacts during propagation. The speed of the leading edge of the pulse is in quantitative agreement with predictions for one-dimensional chains, while the slower speed of the peak response suggests that it contains waves which have travelled over multiple paths even within just this near-field region. These effects highlight the importance of particle-scale behaviors in determining the acoustical properties of granular materials

Missed opportunities: Module design to meet the learning and access needs of practitioners - A work based learning pilot in the rehabilitation setting

It is with great pleasure that this report is presented as a result of an exciting project that truly exemplified partnership working. For a Higher Education Institution to come together with an NHS organisation to negotiate and tailor an education initiative in direct response to the needs of both the organisation and its staff is a very positive direction of travel. The project has been possible through the enthusiasm and commitment of its partners, their contribution of resources including time and funding, and the support of others who have played a part in enabling it to happen. The willingness of the students taking part in the pilot module should be recognised as much of what we have learnt from the process and the evaluation of it, will more directly benefit future students rather than the participating students themselves. As with any pilot, there are risks and where challenges have not been foreseen they have been addressed along the way, flexibly and promptly. Whilst a relatively small project, it has generated much interest from others interested in work based learning approaches and potential students from across the health care professions wanting to take part in future courses. On behalf of the Project Team, I hope you find the report useful and encourage you to make contact if you require further information, wish to explore work based learning opportunities (uni-discipline or multi-professional) here at the University or would like to discuss research or evaluation

Characterisation of real GPRS traffic with analytical tools

With GPRS and UMTS networks lunched, wireless multimedia services are commercially becoming the most attractive applications next to voice. Because of the nature of bursty, packet-switched schemes and multiple data rates, the traditional Erlang approach and Poisson models for characterising voice-centric services traffic are not suitable for studying wireless multimedia services traffic. Therefore, research on the characterisation of wireless multimedia services traffic is very challenging. The typical reference for the study of wireless multimedia services traffic is wired Internet services traffic. However, because of the differences in network protocol, bandwidth, and QoS requirements between wired and wireless services, their traffic characterisations may not be similar. Wired network Internet traffic shows self-similarity, long-range dependence and its file sizes exhibit heavy-tailedness. This paper reports the use of existing tools to analyse real GPRS traffic data to establish whether wireless multimedia services traffic have similar properties as wired Internet services traffic

User behaviour modelling for resource management in a hybrid UMTS/DVB-T network

Third generation mobile networks such as UMTS are designed to enhance the deployment of multimedia services providing high data rates and new flexible communication capabilities. However, these systems are interference limited and as such their performance is lowered in the case of a large number of users generating heavy traffic. A solution to this problem is to interconnect the UMTS network to a Digital Video Broadcasting-Terrestrial (DVB-T) network, so that the lack of capacity of UMTS during busy periods can be offset by the high bit rate available on the broadcast network. In order to justify this choice a prediction of the number of subscribers requesting the new multimedia applications designed for this scenario is needed. This paper focuses on the user behaviour modelling for multimedia services in a hybrid UMTS/DVB-T platform. The aim of the paper is to provide operators with a forecast of the demand for new multimedia services showing how they can be subject to a very high number of subscriptions, which UMTS would hardly be able to handle

Seamless soft handover in DVB-H networks

DVB-H (Digital Video Broadcasting for Handhelds) is a standard specified by the DVB Organization specifically for the broadcast of TV-like content and data to handheld devices, such as mobile phones, which have unique requirements in terms of power consumption, screen-size and mobility. Seamless handover in such a unidirectional network is especially challenging. In this paper we describe the handover issues of DVB-H networks and propose a novel seamless soft handover mechanism based on measuring CDF (Cumulative Distribution Function) of the signal to noise ratio (SNR) in the DVB-H terminal receiver front-end . Details of the algorithm is given and simulation is done to prove the benefits of such soft handover scheme

Performance analysis of time slicing in DVB-H

TV is the biggest media and the last one missing from mobile phones. Digital Video Broadcasting for Handhelds (DVB-H) is the latest development from the DVB Project targeting handheld, battery powered devices such as mobile telephones, PDAs(Personal Digital Assistants), etc. Time Division Multiplexing (TDM) is the technology that is usually used in computer and telecommunication systems. Time slicing is one of the characteristics that makes it possible to broadcast high resolution TV programes and fast IP data services to battery powered handheld terminals. This paper discusses the characteristics and advantages of Time slicing algorithm in DVB-H and presents the performance analysis of time slicing in DVB-H through both theoretical analysis and software simulation

Experimentally validated continuous-time repetitive control of non-minimum phase plants with a prescribed degree of stability

This paper considers the application of continuous-time repetitive control to non-minimum phase plants in a continuous-time model predictive control setting. In particular, it is shown how some critical performance problems associated with repetitive control of such plants can be avoided by use of predictive control with a prescribed degree of stability. The results developed are first illustrated by simulation studies and then through experimental tests on a non-minimum phase electro-mechanical system