Active Constellation Extension for Increasing the Capacity of Clipped OFDM

The paper studies the method active constellation extension (ACE) for increasing the channel capacity of orthogonal frequency-division multiplexing (OFDM) with a nonlinear power amplifier at the transmitter. It turns out that ACE is able to optimize the capacity but at the expense of an increased out-of-band radiation. In order to solve this issue, ACE is combined with the strategy clipping and filtering. With this combination it is possible to increase the channel capacity while reducing the out-of-band radiation.