PERFORMANCE ANALYSIS FOR A GUARANTEED HANDOVER SERVICE IN AN LEO CONSTELLATION WITH A SATELLITE-FIXED CELL SYSTEM

It is anticipated that the satellite component of the future universal mobile telecommunications system (UMTS) will be based (partly or tota lly) on non-GEOstationary (non-GEO) constellations of satellites to se rve mixed populations of users, each category being treated through di fferent contracts stipulating different quality of service (QoS), In p articular, we envisage a high-quality premium service which guarantees the success of each handover procedure, called guaranteed handover (G H) ser,ice, and a low-cost lower quality service called regular servic e, where handover failures are accepted provided that the probability of a call being unsuccessful does not exceed a given value. This paper proposes a strategy which eliminates forced call terminations due to handover failures, thus allowing the GH service. This procedure applie s to low earth orbit (LEO) constellations using the satellite-fixed ce ll technique. An analytical model has been derived to calculate QoS pa rameters for a mixed population of GH and regular users. Providing bot h GH service to some users and regular service to other users requires an increased satellite capacity with respect to the case where all th e users are served with the regular service; this capacity increase ha s been evaluated as a function of the percentage of GH users, the traf fic load per cell, and the considered satellite mobility environment. The GH approach has been validated through the comparison with another scheme which envisages the queuing of handover requests for privilege d users.