Performance of OFDM systems with adaptive nonlinear amplifiers

Orthogonal frequency division multiplexing (OFDM) is known for its high peak-to-mean-envelope-power ratio. This requires a large amplifier power output backoff, when linear amplification is needed, resulting in low DC to RF power conversion efficiency of the amplifier. Previously, adaptive DC bias controlled amplifiers were proposed, which achieve both high power efficiency and linearity. In this paper, we quantify and optimise the power consumption of OFDM systems when the proposed amplifiers are used. The bit error rate (BER) and adjacent channel power ratio (ACPR) are obtained through computer simulation to help quantifying the amplifier nonlinear effects. It is found that power consumption can be greatly minimized by using adaptive amplifiers, especially with highly nonconstant envelope modulated signals such as OFDM.