Generalized active constellation extension for peak reduction in OFDM systems

The high peaks of an orthogonal frequency division multiplexing (OFDM) signal are distorted nonlinearly by the high power amplifier (HPA). For peak reduction the active constellation extension (ACE) technique can be applied. However, clipping, which is an essential part of ACE, degrades the bit error rate (BER). The degradation is limited by applying the ACE constraints to the clipped signal. In this paper a generalization of the ACE constraints is proposed. In comparison to the conventional constraints a lower out-of-band (OOB) radiation can be achieved. The computational costs for the proposed modification are only very small.