Out-of-Band Distortion Reduction in DVB-T Systems with Particle Swarm Digital Predistorters

Predistortion techniques are a well known power amplifier linearization method in order to reduce out-of band interferences in a non-constant envelope modulation system. A new adaptive digital predistorter based on the use of PSO (particle swarm optimization) algorithm is developed and applied in an orthogonal frequency-division multiplexing (OFDM) transmission scheme, such as a digital video broadcasting system. OFDM transmission is an efficient way to deal with multipath, being its implementation less complex than traditional equalizers, however, it is also very sensitive to nonlinear distortions due to its greatly variable envelope. The performance of this method has been verified by means of simulation using an amplifier characterized by a level-dependent complex gain using a memoryless model for different input power levels. In addition, the influence of some PSO parameters (the number of particles) on convergence is studied.