The aim of the project is to analysis the performance of clipping noise in OFDM by using QPSK modulation with four subcarriers.
Now a days in digital communication system in long distance transmission the optical fiber cable will be widely used called optical
wireless communication (OWC) systems. orthogonal frequency-division multiplexing (OFDM) systems employing coded modulation
Clipping is applied to reduce the peak-to-average-power-ratio (PAPR) of the transmit signal. But clipping noise will be occurred on
OWC systems employing OFDM is investigated. There are two existing optical OFDM transmission schemes 1. Asymmetrically
clipped optical OFDM (ACO-OFDM) and 2. Direct current biased clipped optical OFDM (DCO-OFDM). The Time domain signal
clipping generally results from direct current (DC) biasing and/or from physical limitations of the transmitter front-end. Analytical
expressions for the attenuation factor and the clipping noise variance are determined in closed- form and employed in the derivation of
the electrical signal-to- noise ratio (SNR). The validity of the model is verified through a bit-error ratio (BER) simulation. Finally the
BER performance of ACO-OFDM with DCO-OFDM is compared for different clipping levels and multi level QPSK modulation
schemes for ACO and DCO.