Abstract
A subcarrier nulling technique based on Reed–Solomon (RS) encoding and nonlinear distortion measurement in orthogonal frequency-division multiplexing (OFDM)-based visible-light communication (VLC) is proposed. The effect of nonlinear clipping imposed by the low dynamic range in an OFMD-VLC leads to a non-uniform distortion on the data-bearing OFDM subcarriers. This distortion combined with the low bandwidth modulation of the light-emitting diode could limit the throughput of the VLC system. The proposed technique employs the clipping distortion to adaptively select and null the group of subcarriers that are responsible for the peak values in the OFDM symbol. Using the frequency domain RS block code, the OFDM transmitter is provided with the flexibility to find and remove the accumulated in-band distortion anywhere within the OFDM frame without the need for prior subcarrier reservation. With the help of log-likelihood ratio detection, nulled subcarriers are estimated at the receiver, and the RS codewords with erasure are recovered and decoded without using side information. This technique mitigates the error vector magnitude and reduces the peak to average power ratio in an OFDM-VLC under severe clipping conditions with reduced complexity. The proposed technique bit error rate performance is studied and compared with traditional techniques in a VLC system with clipping constraint.
Published Version
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