Abstract

OFDM communications require extreme linearity of High Power Amplifiers (HPA) to avoid Inter-Carrier Interference (ICI) and subsequent degradation of the BER and Quality of Service (QoS). Amplitude (AM/AM) and Phase (AM/PM) amplifier non-linearities can be compensated in a number of ways. Nevertheless, digital adaptive schemes based on least squares optimization criteria need estimate the delay introduced by the analog chains in the generation of the error signal. A sufficiently precise HPA input-output time delay estimate (IDE) is necessary before attempting pre-distortion of the amplifier itself. This paper introduces statistical criteria for this initial acquisition stage.