Performance of an adaptive predistorted power amplifier with peak limited baseband code‐division multiplexed signal

Abstract

AbstractIn FDM and CDM systems, the peak‐to‐average power ratio (PAPR) increases as the number of signals to be multiplexed is increased. When a signal with a large PAPR is incident on a power amplifier, either the out‐of‐band radiation is increased or the power efficiency is degraded. Methods of resolving these problems are nonlinear distortion compensation techniques, one of which is the predistorter. Another conceivable solution is to suppress the PAPR of the input signal. In this paper, we first study the performance when a limiter is used for the CDM signal in the baseband. By computer simulation, it is shown that the PAPR is suppressed by using a limiter and that the deterioration of the SIR performance is small if the PAPR is more than 6 dB. Next, the characteristics are studied by numerical simulation when a CDM signal with a limiter in the baseband is input to an adaptive predistorter‐type distortion‐compensated power amplifier. By combining the CDM signal with a limiter in the baseband and the adaptive predistorter‐type distortion‐compensated power amplifier, it is possible to suppress the out‐of‐band radiated power and simultaneously increase the power efficiency. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(2): 37–45, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10154