Coded Orthogonal Frequency Division Multiplexed (COFDM) techniques, used by terrestrial European broadcasting systems (DAB, DVB-T), could be adopted in the last mile of the downlink channel for Wireless Broadband Communication System to provide Multimedia Services to mobile or nomadic users by cellular coverage techniques, as evinced from the actual research activity. COFDM signals are characterised by non-constant envelope (peak-to-mean power ratio > 10 dB) which forces to project amplifiers with low or well-counteracted nonlinear distortion effects. Our aim is to present Itelco experience to characterise non-linear distortions introduced by final amplifiers on COFDM signals (AM/AM, AM/PM and NonLinearities with Memory). Both experimental measurements and simulation results will be shown. Moreover we will point out the improvements achievable by digital baseband predistortion, to counteract for AM/AM and AM/PM non-linearities, and by RF compensation techniques to remove NonLinear Memory effects
Non Linear Distortions Introduced by Amplifiers on COFDM Signals. Measurements, Effects and Compensation Techniques
BANELLI, Paolo;
1997
Abstract
Coded Orthogonal Frequency Division Multiplexed (COFDM) techniques, used by terrestrial European broadcasting systems (DAB, DVB-T), could be adopted in the last mile of the downlink channel for Wireless Broadband Communication System to provide Multimedia Services to mobile or nomadic users by cellular coverage techniques, as evinced from the actual research activity. COFDM signals are characterised by non-constant envelope (peak-to-mean power ratio > 10 dB) which forces to project amplifiers with low or well-counteracted nonlinear distortion effects. Our aim is to present Itelco experience to characterise non-linear distortions introduced by final amplifiers on COFDM signals (AM/AM, AM/PM and NonLinearities with Memory). Both experimental measurements and simulation results will be shown. Moreover we will point out the improvements achievable by digital baseband predistortion, to counteract for AM/AM and AM/PM non-linearities, and by RF compensation techniques to remove NonLinear Memory effectsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
