Revisiting Band-Limited DS/SS Signal Design for GNSS

A lot of attention has been devoted in the last 20 years to the issue of Signal-in-Space design for Global Navigation Satellite Systems (GNSSs). The fundamental, unifying feature of such effort has been designing constant-envelope formats to maximize the power efficiency of the High-Power Amplifiers (HPA) on board the satellite. In reality, such signals have to be filtered by the on-board generation units, so that the constant-envelope feature is somewhat lost, especially in the latest wideband signals like GALILEO E5. On the other hand, mass-market receivers are capable to exploit wider bandwidths than in the past, so it makes sense to increase the chip rate of future signals and fill-up the allocated bandwidth as much as possible not to generate performance losses and precious bandwidth waste. This short paper investigates a signal design approach, wherein GNSS signals are wideband and band-limited by design (hence variable-envelope), so that their implementation is $\mathbf{1 0 0 \%}$ accurate wrt the theoretical model. The aim is either achieving better ranging accuracy in the same occupied bandwidth, or smaller bandwidth occupancy for the same accuracy.