High Spectral Efficient Free-Space Optical Communication Using Multi-Stage Noise Shaping Delta-Sigma Modulation With Partial Transmit Sequence Algorithm and Arithmetic Coding

We propose and experimentally demonstrate an optical wireless communication (OWC)-based mobile-fronthaul (MFH) system achieving recorded highest bit efficiencies (BEs) of 0.848 satisfying the soft-decision forward-error-correction (FEC, i.e., bit-error-rate, BER = 4 × 10^-2) and 0.709 satisfying the hard-decision-FEC (i.e., BER = 3.8 × 10^-3) among 1-bit DSMs. A proof-of-concept 200 m free-space transmission is demonstrated. We first propose utilizing the Hughes-Hartogs (HH) algorithm for the bit-power loading, followed by the partial transmit sequence (PTS) algorithm for reducing the peak-to-average power ratio during the orthogonal frequency division multiplexing. Then, we propose arithmetic coding (AC) in the source coding scheme to further enhance BEs. Here, we experimentally illustrate that by using the proposed HH, PTS and AC algorithms, more than 21% improvement is achieved, which is equal to an increase in the data rate of 6 Gbps per wavelength. We also experimentally illustrate that by employing wavelength division multiplexing in the proposed OWC-based MFH system, a total capacity of 1.163 Tbps (i.e., 28.57 Gbaud × 0.848 × 48 wavelengths) can be attained.