A DCT/DST Based Fast OFDM Method in IM/DD Systems

Abstract

Intensity modulation and direct detection (IM/DD) method is widely used in optical communications. IM/DD systems require the transmitted symbols to be real-valued. Fast orthogonal frequency division multiplexing (FOFDM) is a multi-carrier communication method which can transmit by all the subcarriers and produce real-valued samples at the output. Besides the advantages of FOFDM the single-tap equalizer is unfeasible to compensate for inter symbol interference because of linear convolution property cannot be fulfilled by the inverse discrete cosine and discrete cosine transform (IDCT/DCT) pair that extensively used in FOFDM systems. In this letter, a novel FOFDM method is proposed which uses inverse discrete sine and discrete sine transform (IDST/DST) and IDCT/DCT pairs together. The proposed method provides the use of single-tap equalizer with the advantage of lower peak to average power ratio (PAPR).