Abstract: Optical orthogonal frequency division multiplexing with index modulation technology performs well in terms of bit error rate performance but with low transmission rate. Therefore, employing discrete wavelet transform and combining the idea of differential pulse position modulation, an optical orthogonal frequency division multiplexing with differential index modulation (O-OFDM-DIM) based on discrete wavelet transform is proposed. The transmission rate is greatly improved by using wavelet transform and removing the silent subcarriers at the end of each subcarrier block. The orthogonality of wavelet transform and the subcarrier allocation algorithm are used to eliminate the impact of channel turbulence. The modulation mapping principle of the proposed scheme is introduced in detail, its theoretical bit error rate expression is derived. In addition, its performance is compared with the existing asymmetrically clipped optical orthogonal frequency division multiplexing with index modulation (ACO-OFDM-IM) scheme. The simulation results show that the proposed scheme achieves a higher transmission rate and lower bit error rate than ACO-OFDM-IM. In particular, the transmission rate of the proposed is nearly three times that of its baseline scheme at a high signal-to-noise ratio, and the signal-to-noise ratio is improved by about 2dB under a strong turbulence channel when the bit error is 1×10^-4.

Key words: optical orthogonal frequency division multiplexing, differential index modulation, discrete wavelet transform, bit error rate