Bandlimiting Polar Signals with Special W-CDMA Constellations

The polar transmitter concept promises significant higher power efficiency utilizing nonlinear power amplifiers. RF transmitters using polar transmitter technique are currently available for EDGE systems and are under development for UMTS. The UMTS extensions HSDPA and HSUPA provide a number of additional physical uplink channels which can lead to a variety of constellations incorporating constellation points at the I/Q origin. Such signals show increased activity at magnitudes around zero. This paper explains how such configurations arise and what effect a band limiting block in the magnitude signal has on signal quality indicated in EVM.