Wideband-CDMA Approaches for the Satellite UMTS Component

摘要

The recent European Telecommunications Standards Institute (ETSI) decision to endorse techniques based upon wideband-CDMA approaches for terrestrial UMTS (T-UMTS) will certainly constitute an important driver to orientate the corresponding choice for the satellite UMTS (S-UMTS) component, as a similarity in the access solution would certainly contribute to making dual-mode user-terminals more cost-effective.rnAn access system suitable for via-satellite applications shall be devised keeping in mind the need to face a number of challenging requirements, such as reduced power margin with respect to T-UMTS, significant propagation delay, high frequency error due to Doppler shift especially for the Low-altitude Earth Orbit (LEO) case, difficulty to implement a coherent-demodulation return-link, the need to adopt a satellite-diversity technique.rnAfter briefly reviewing the solutions proposed or adopted for T-UMTS, this paper proposes an access scheme for S-UMTS capable of suiting the above listed constraints, while seeking maximum commonality with the T-UMTS.rnThis paper is based on the initial outcomes of a work activity which a team led by Space Engineering is performing under ESA contract [1], for defining and assessing in detail an access scheme suitable for S-UMTS, and for implementing a comprehensive test-bed capable of demonstrating its performance in a simulated via-satellite propagation environment.