SPC07-4: Performance of Asymmetrically Clipped Optical OFDM in AWGN for an Intensity Modulated Direct Detection System

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Abstract
Orthogonal frequency division multiplexing (OFDM) is used in many wired and wireless broadband communication systems because of its resilience in the presence of signal dispersion or multipath distortion. OFDM has not been used in practical optical communication systems because the bipolar waveform cannot be used in intensity-modulated direct detection (IM/DD) systems. A new unipolar form of OFDM, asymmetrically clipped optical OFDM (ACO-OFDM), has recently been developed. For the case of an AWGN channel, we compare ACO- OFDM and other modulation schemes. It is shown that ACO- OFDM with 4-QAVI subcarrier modulation has the same bandwidth efficiency but requires 2 dB less energy per bit than on-off keying. ACO-OFDM with larger constellation sizes gives higher bandwidth efficiencies and lower optical power than other modulation schemes. Unlike existing methods, the performance of ACO-OFDM is limited by the bandwidth of the transmitter and receiver not the dispersion of the channel.