Abstract
In modern wideband communication receivers, the large input‐signal dynamics is a fundamental problem. Unintentional signal clipping occurs, if the receiver front‐end with the analog‐to‐digital interface cannot respond to rapidly varying conditions. This paper discusses digital postprocessing compensation of such unintentional clipping in multiband OFDMA receivers. The proposed method iteratively mitigates the clipping distortion by exploiting the symbol decisions. The performance of the proposed method is illustrated with various computer simulations and also verified by concrete laboratory measurements with commercially available analog‐to‐digital hardware. It is shown that the clipping compensation algorithm implemented in a turbo decoding OFDM receiver is able to remove almost all the clipping distortion even under significant clipping in fading channel circumstances. That is to say, it is possible to nearly recover the receiver performance to the level, which would be achieved in the equivalent nonclipped situation.
Highlights
Modern wideband radio receivers, such as cognitive radios, are setting significant challenges for the design of the receiver front-end
The bit-error ratio (BER) results are averaged over 20,000 OFDM symbols, that is, 2000 independent channel
This paper discussed the compensation of unintentional clipping occurring in the A/D converter of a radio receiver
Summary
Modern wideband radio receivers, such as cognitive radios, are setting significant challenges for the design of the receiver front-end. The AGC failure causes too high input level for the A/D converter and the amplitude of the digitized waveform is saturated, that is, the highest signal peaks are clipped This causes considerable signal distortion especially at the weak signal bands due to intermodulation of strong input components. Most of the OFDM-related clipping compensation algorithms in the literature concentrate on deliberate clipping to reduce signal PAPR on the transmitter side [8,9,10]. These methods are not directly applicable to mitigate clipping occurring on the receiver since the exact clipping level is not known in the case of unintentional clipping.
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