Clip correction in wireless LAN receivers

OFDM signals suffer from a large peak to average power ratio, which requires large power back-offs in the transmit and receive chains. This paper presents a digital postprocessing method that mitigates clipping by the analog-to-digital converter (ADC) in the receiver. Clipped peaks cause spurious signals on empty subcarriers, which can be used to eliminate clipping artifacts and to recover the original signal. Simulations show that a significant reduction of 3 dB in the headroom of the A/D converter (ADC) is possible, when an elaborate MMSE clip correction algorithm is used. A simple algorithm still allows for 1 dB reduction of the headroom. As the ADC is consuming an ever increasing fraction of the total receiver power, the results are believed to be relevant for low-power design of OFDM receivers, for instance to prolong battery life of laptops and other portable WLAN devices.