ENHANCING SATELLITE BROADCASTING SERVICES USING MULTIRESOLUTION MODULATIONS

In this paper we propose to take advantage of the energy link margin. that can exist of satellite connections to enrich the DVB-S services w ith WEB-like interactive services. The exploitation, of such margin is obtained by using multiresolution modulation techniques. The system a rchitecture analysed is asymmetrical, composed of a satellite forward link and a narrowband terrestrial reverse link. The ATM is adopted to support different QoS for different type of information to be delivere d. The satellite propagation delay and the traffic and congestion cont rol of the ATM suggest to modify the slow start and the congestion avo idance of the TCP. Our approach is based on the combination of a fixed window flow control at transport layer with the ATM traffic and conge stion control. Our analysis shows that the system performance is satis factory if some bounds of the TCP buffer size are respected and the sp acing of the RM cells is within a given range of values.