REDUCTION OF NON LINEARITY EFFECTS ON OFDM SIGNALS: A PRE-DISTORTION SCHEME BASED ON POWER SERIES / REDUÇÃO DOS EFEITOS DE CANAIS NÃO-LINEARES SOBRE SINAIS OFDM: UM ESQUEMA DE PRÉ-DISTORÇÃO NÃO-LINEAR BASEADO EM SÉRIE DE POTÊNCIAS

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The main problems of multiple carriers through non-linear devices are, AM / PM conversion, conversion AM / PM conversion, and intermodulation. These problems are usually present in satellite transmissions, where high-power amplifiers (HPAs) and nonlinear transponders are used, as well as in terrestrial broadcasting systems where, in order to enlarge the service area(geographical area in which the service is offered). High-power amplifiers operating in their non-linear region are used. The multicarrier transmission called OFDM, which is widely used in TV broadcasting digital signals falls in this context. In order to alleviate the effects of nonlinear channels on OFDM signals, the present study suggests the use of a pre-distortion system mathematically described through a complex power series. Two Strategies are considered in order to determine the pre-distortion system parameters: the reduction of the intermodulation power sum associated to intermodulation products of any specified order, and the equalization of the intermodulation power associated to intermodulation product of various orders. Analysis of configurations based on these two strategies are presented together with numerical results involving situations of specific interest.

ASSUNTO(S)

intermodulation non-linearity nao-linearidade intermodulacao pre-distorcao pre-distortion

ACESSO AO ARTIGO

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