Peak-to-Average Power Ratio (PAPR) Reduction Using Combination of Precoding and Companding Techniques for VLC OFDM Systems

Abstract

In VLC system, increase in data rate leads to inter symbol interference (ISI). It is desired to reduce the high ISI using suitable modulation technique for high rate data traffic. Orthogonal frequency division multiplexing (OFDM) is an efficient modulation format to alleviate ISI effect. OFDM in VLC system allows high data rate transmission in multipath surrounding and efficiently utilizes the available LED modulation bandwidth. However, optical OFDM (O-OFDM) system suffers from the problem of high peak-to-average power ratio (PAPR). The problem of PAPR in direct current (DC) biased O-OFDM (DCO-OFDM) system results in nonlinearities and degradation in system performance due to LED chip overheating and signal clipping distortion. In this paper a combinative scheme comprising of precoding matrix and Mu-law companding method is proposed for PAPR reduction. It is shown that this hybrid technique is an attractive solution to achieve a beneficial trade-off between PAPR and improved bit error rate (BER) of the system.