Kaihui Wang

Nonlinear Look-Up Table Predistortion and Chromatic Dispersion Precompensation for IM/DD PAM-4 Transmission

In this paper, we propose and experimentally demonstrate 10 GBaud intensity modulation direct detection pulse amplitude modulation 4 transmission over 48-km single mode fiber (SMF). Look-up table predistortion and chromatic dispersion precompensation are employed to mitigate channel bandwidth constraint and nonlinear impairment. At the receiver side, decision-directed least mean square and cascaded multimodule algorithm are employed to improve the decision precision. By combining these techniques, link budgets of 5.3 and 4 dB are achieved at bit error rate of 1 × 10−3 for the back-to-back case and after transmission over 48-km SMF, respectively.

Nonlinear compensation for high-order modulation signal in a IM/DD DFT-S-OFDM system with directly modulated laser

The nonlinear compensation algorithm based on Volterra series has been proved effective in low order modulation OFDM system, such as QPSK/16QAM. In this paper, we demonstrate a 64QAM/ 128QAM DFT-S-OFDM signal generation with DML with some advanced algorithms such as DD-LMS, ISFA, DFT-S and nonlinear compensation to improve the signal performance. For the first time we demonstrate that the nonlinear compensation algorithm based on Volterra series can improve the performance of the high-order modulation DFT-S-OFDM signal such as 64QAM and 128QAM. In this experiment we have realized 19.1/11.2Gb/s 64/128QAM signal transmission over 15km fiber at 1307nm. For 64QAM case, the receiver sensitivity can be improved about 1dB when all the algorithms mentioned in this paper are adopted. And the BER can be improved from 4.7x10-3 to 2.8x10-3 at 7.0dBm for 128QAM signal, which reaches the HD-FEC threshold of 3.8x10-3.

Photonics-aided 2 × 2 MIMO wireless terahertz-wave signal transmission system with optical polarization multiplexing

We experimentally demonstrate a photonics-aided 2 × 2 multiple-input multiple-output (MIMO) wireless transmission system at a terahertz-band (THz-band). In our demonstrated system, the generated 4-Gbaud polarization-division-multiplexing quadrature-phase-shift-keying (PDM-QPSK) signal at 450GHz by photonic remote heterodyning can be delivered over a 142-cm 2 × 2 MIMO wireless transmission link, with a bit-error ratio (BER) less than the hard-decision forward-error-correction (HD-FEC) threshold of 3.8 × 10−3. The further introduction of up to a 50-km single-mode fiber-28 (SMF-28) transmission causes a negligible power penalty. To the best of our knowledge, this is the first time a 2 × 2 MIMO wireless transmission of a polarization-multiplexing terahertz-wave (THz-wave) signal has been realized.

Comparison of DFT-S-orthogonal frequency division multiplexing and single-carrier in a radio-over-fiber system

Abstract. DFT-S-orthogonal frequency division multiplexing (OFDM) and single-carrier (SC) modulation are two typical modulation formats in radio-over-fiber (RoF) systems. They may have respective advantages and disadvantages in different scenarios. Therefore, bit error ratio comparison results of these two modulation formats will be useful for designing and optimizing the practical RoF system. We experimentally compare these two modulation formats in a long wireless distance RoF system at W-band. It can be concluded that DFT-S-OFDM and SC modulation have similar performances in a RoF system with transmission distance over 80-km fiber and 224-m wireless link.

Performance Comparison of PS Star-16QAM and PS Square-Shaped 16QAM (Square-16QAM)

We investigate and compare the performance of star-shaped 16-ary quadrature amplitude modulation (Star-16QAM) and square-shaped 16QAM (Square-16QAM) in the probabilistic shaping (PS) and uniform schemes with coherent detection. With the help of PS technology, the bit error ratio (BER) improvement achieved in the PS-Star-16QAM scheme is greater than that of the PS-Square-16QAM when compared with the uniform schemes in our numerical simulation and experiment. Therefore, the PS-Star-16QAM shows superiority over the PS-Square-16QAM in terms of the BER improvement.