Elastic calls in an integrated services network: the greater the call size variability the better the QoS

We study a telecommunications network integrating prioritized stream calls and delay tolerant elastic calls that are served with the remaining (varying) service capacity according to a processor sharing discipline. The remarkable observation is presented and analytically supported that the expected elastic call holding time is decreasing in the variability of the elastic call size distribution. As a consequence, network planning guidelines or admission control schemes that are developed based on deterministic or lightly variable elastic call sizes are likely to be conservative and inefficient, given the commonly acknowledged property of e.g.\ \textsc{www}\ documents to be heavy tailed. Application areas of the model and results include fixed \textsc{ip} or \textsc{atm} networks and mobile cellular \textsc{gsm}/\textsc{gprs} and \textsc{umts} networks. \u

Diffusion of mobile phones in Portugal: unexpected success?

This paper begins with a somewhat paradoxical situation: Portugal is one of the less innovative countries within the European Union by most innovation indicators but, simultaneously, it is a leading country in the diffusion of mobile phones. The remarkable evolution of the mobile telecommunications sector over the last 15 years turns the issue a little more intriguing. This paper addresses the diffusion of mobile phones in Portugal and focuses particularly on the take-off stage, which signalled a sudden change in the pattern of diffusion. The introduction of an innovation – prepaid cards – explains most of the change in the diffusion curve occurred around 1996 and the subsequent increase in the penetration rate. Prior known research has not considered pre-paid cards an important determinant of mobile phone diffusion, but pre-paid services had an enormous impact on the rate of adoption of mobile phones in many countries and it is the major take-off determinant of mobile phone diffusion in Portugal. The time lag between the launching of this innovation in Portugal and its adoption by other EU countries explains why Portugal not just caught up with the EU average mobile phone penetration rate around 1996, but moved ahead of it from then on

Telephone Usage and Travel Behaviour in Nigeria

The application of telecommunications to travel has changed people’s daily lifestyles by diminishing the time-space constraints and giving virtual accessibility to activity centres. However, the effect of telecommunications on travel behaviour has been a main concern on whether it has complementary or substitution effects. This study explores the relationship between telephone usage and travel behaviour among the staff of Obafemi Awolowo University, Ile-Ife, Nigeria. The information for this study was obtained from primary data through the use of structured questionnaire. From the population of 2620 staff, 5% sample size comprising of 131 staff was randomly selected for the questionnaire survey. The findings reveal that most of the staff travels less than 10km for work, shopping and social trips, spend less than 20 minutes journey time and mostly used private cars for commuting to the activities. Furthermore, there is high telephone usage among the staff as about 33% make more than 15 telephone calls per day. The hypothesis test of the relationship between telephone usage and travel shows that the correlation coefficient of 0.181 is significant at 0.047 for substituted trips and 0.226 at 0.013 for complemented trips. The study concludes that there is net substitution and strong complementary effect of telephone usage on travel among the staff. Keywords: Telephone usage, Travel behaviour, Telecommunications, Complementary, Substitutio