Joint spectrum and power optimization in the design of the UMTS satellite component

The paper provides a power and spectrum joint analysis of the universal mob ile telecommunications system (UMTS) satellite component, based on the wide band code division multiple access (W-CDMA) air interface. In fact, power a nd spectral efficiency may become highly conflicting requirements in a sate llite system and a trade-off analysis is needed to drive a proper dimension ing of the satellite. The proposed approach allows a dimensioning of the sa tellite component either in terms of orbit and power budget or in terms of additional capacity for the terrestrial section, for specified orbit and po wer limitations. The impact of candidate frequency bands, orbit type and di versity on both spectral and power requirements of the satellite component is evaluated. For given traffic requirements, power-vs-spectrum trade-off i s proposed which ensures a proper resources utilization. The efficiency eva luation accounts for: beams overlapping, orthogonality, voice activity fact or, diversity and cross-polarization frequency reuse. Perfect power control is assumed and the effect of the excess power required by the shadowed use rs is accounted for in the interference calculation. Furthermore, still in the frame of a proper resource exploitation. a possible optimization of cap acity through the use of unpaired bands in the two link directions is analy sed. Copyright (C) 2001 John Wiley & Sons, Ltd.