EXPERIMENTAL RESULTS OF A DEMAND-ASSIGNMENT THIN ROUTE TDMA SYSTEM

This paper presents the experimental results measured on the Italsat satellite when data is transmitted by using the FODA/IBEA satellite access scheme. The measures presented refer to the packet arrival time jitter, which affects the real-time data, and to the end-to-end delay of the non real-time data. The experimental results, obtained with four Italian active stations of Italsat confirm the analytical results. The paper also shows the advantage of working in pre-assignment mode, a feature of the capacity assignment algorithm which improves the end-to-end delay of non-real-time data during the transient provoked by a traffic step when the system is scarcely loaded.     

RADIO AND NETWORK COMPARISONS FOR MSBN AND GSM SYSTEMS IN A GEOSTATIONARY SATELLITE ENVIRONMENT

One of the most frequently debated issues in satellite communications concerns the comparison between time division multiple access (TDMA) and code division multiple access (CDMA) systems. Although, in our view, a general answer to this problem cannot be found, this paper presents comparisons of two systems utilizing the above-mentioned access techniques, both from a radio and a network point of view. In particular, the mobile satellite business network (MSBN), (a CDMA system currently being developed by the European Space Agency (ESA) for general satellite applications) and the full integrated extension to satellite systems of the global system for mobile communication (GSM) (the well-known frequency division multiplex (FDM)/TDMA pan-European mobile cellular system) are compared by taking, as the reference payload, the L-band land mobile (LLM) satellite (a spot-beam geostationary satellite whose launch should take place at the end of 1997). Reasonable assumptions take into account the fact that, on one hand, the MSBN system is not completely defined and, on the other, the GSM is applied in a context different from the one specified by the European Telecommunication Standard Institute (ETSI). Performance comparisons are carried out in terms of flexibility and number of available channels for the same quality requirements, emitted power levels, propagation environment and interference levels coming from adjacent satellites. It is concluded that MSBN is more flexible than GSM and that, as regards capacity, an advantage of GSM over MSBN is present in the transportable mobile case, whereas, in the vehicular mobile case, MSBN shows an advantage over GSM. © 1996 by John Wiley & Sons, Ltd.     

Cellular and subcellular coherent dynamics,biological functional properties,and system-environment interaction

In this view point paper, we briefly summarize some of the clinical, biochemical and biophysical results obtainedin our research on Relaxation Response. We also qualitatively describe the theoretical biophysical model that could linkthem. Our work points to a unified view of the human biological system activity, joining the dynamics ruling theinteractions and correlations of the microscopic components to the knowledge of their specific individual propertiesin the effort of going beyond a purely atomistic approach.     

ASCETA: AN EXPERT SYSTEM FOR PASSIVE NETWORK SYNTHESIS

An expert system for passive network synthesis and filter design, developed in an object-oriented environment, is presented. It has been implemented using a shell written in the language SMALL2ALK/V and is highly interactive. It has been conceived and developed mainly for educational purposes, and its implementation has demonstrated the suitability of the object-oriented approach and of the SMALLTALK environment for this kind of problem.     

Probabilistic assessment of small disturbance stability in multimachine power systems

In planning electric power systems, it is always necessary to assess whether small-disturbance (SD) instability phenomena occur at prefixed system operating conditions. This analysis can become very difficult when the problem data are uncertain. In such cases the use of deterministic approaches is inadequate and the application of probabilistic analysis techniques is the most feasible alternative. This paper presents a new and practical probabilistic approach for the assessment of SD stability in multimachine power systems taking into account the uncertainties associated with bus load forecasting and treating loads as random uncorrelated variables with normal distributions. This approach proves suitable for determining the risk of SD instability for each expected system operating condition and for systematically individualizing all factors that can affect the probability of SD instability in large power systems. A numerical example illustrates the capability of the proposed technique.