  This paper presents an investigation into parameter adaptation in behavioral
model--based digital predistortion for radio frequency power amplifiers. A
novel measurement setup framework that emulates real--time adaptation in
transmitters is developed that allows evaluation of different parameters,
configurations and adaptation algorithms. This setup relieves the need for full
feedback loops for parameter adaptation while providing the flexibility needed
in the design process of parameter adaptation.
  Issues such as convergence speed, sensitivity to quantization noise in the
feedback loop and predistortion performance are investigated for some different
parameter update algorithms using the proposed measurement setup. The approach
presented in this paper allows the possibility to analyze different aspects of
digital predistortion adaptation algorithms, and is an important enabling step
for further research on parameter adaptation before the real--time hardware is
implemented for use.
