Impact of linear power amplifier efficiency on capacity of OFDM systems with clipping

Capacity of clipped OFDM systems is analyzed. In contradistinction to previous work, we take into account intrinsic properties of the linear power amplifier efficiency - the dependence of power efficiency on clipping ratio. The following tradeoff emerges: a low clipping ratio causes signal distortion and decreases capacity. However, it also increases the efficiency of the power amplifier, which increases capacity. We resolve this tradeoff by evaluating the optimal clipping ratio for achieving maximal capacity. We show that increasing the clipping ratio does not necessarily result in higher capacity. Instead there exists an optimal clipping ratio for given channel SNR. Increasing the clipping ratio beyond optimal significantly reduces capacity.