# Special Issue on Optical Communications and Networking: Prospects in Industrial Applications
## 2 Special Issue Papers
Simulation results show that the proposed SOA-enabled HONoC architecture and the associated algorithm help sustain the performance as network size increases without the need for additional laser source power. \(\bullet\) Two-Dimensional Constellation Shaping in Fiber-Optic Communications [6]  
Constellation shaping has been widely used in optical communication systems. The authors reviewed recent advances in two-dimensional constellation shaping technologies for fiber-optic communications. The system architectures that are discussed include probabilistic shaping, geometric shaping, and hybrid probabilistic-geometric shaping solutions. The performances of the three shaping schemes are also evaluated for Gaussian-noise-limited channels. \(\bullet\) Joint Probabilistic-Nyquist Pulse Shaping for an LDPC-Coded 8-PAM Signal in DWDM Data Center Communications [7]  
M-ary pulse-amplitude modulation (PAM) has useful applications in data center communication due to its simplicity and low cost. The challenge in PAM systems include providing dynamic bandwidth and reaching the Shannon capacity limit. One potential solution is probabilistic shaping distribution with Nyquist pulse shaping for fine entropy granularity and reaching the Shannon limit. In this paper,the authors demonstrated the joint usage of probabilistic shaping and Nyquist pulse shaping with low-density parity-check (LDPC) coding to improve the bit error rate (BER) performance of 8-PAM signal transmission. They optimized the code rate of the LDPC code and investigated different Nyquist pulse shaping parameters using simulations and experiments. They achieved a 0.43 dB gain using Nyquist pulse shaping, and a 1.1 dB gain using probabilistic shaping, while the joint use of probabilistic shaping and Nyquist pulse shaping achieved a 1.27 dB gain, which offers an excellent improvement without upgrading the transceivers. * Adaptive Compensation of Bandwidth Narrowing Effect for Coherent In-Phase Quadrature Transponder through Finite Impulse Response Filter [8] In optical coherent communication systems, the transmitted signals may experience bandwidth narrowing effects after passing through multiple reconfigurable optical add-drop multiplexers (ROADMs), or due to coherent in-phase quadrature (IQ) transponder aging. In this paper, the authors demonstrated a method using a post ADC adaptive finite impulse response (FIR) filter in coherent optical receivers to dynamically compensate for the bandwidth narrowing effect. The influence of chromatic dispersion, polarization mode dispersion, and polarization dependent loss were also investigated comprehensively. Furthermore, the bandwidth information of the transmitted analog signal can be fed back to the coherent optical transmitter for signal optimization, and the transmitter-side FIR filter thus can be changed accordingly. * A Novel Coding Based Dimming Scheme with Constant Transmission Efficiency in VLC Systems [9] Visible light communications (VLC) has attracted tremendous attention due to two functions: communication and illumination. Both reliable data transmission and lighting quality need to be considered when the transmitted signal is designed. To achieve the desired levels of illumination, dimming control is an essential technology applied in VLC systems. In this paper, the authors proposed a block coding-based dimming scheme to construct the codeword set, where dimming control can be achieved by changing the ratio of two levels (ON and OFF) based on on-off keying (OOK) modulation. Simulation results show that the proposed scheme can maintain good error performance with constant transmission efficiency under various dimming levels. * Low-Complexity Hybrid Optical OFDM with High Spectrum Efficiency for Dimming Compatible VLC System [10] In this paper, the authors proposed a novel dimming compatible hybrid optical orthogonal frequency division multiplexing (DCHO-OFDM) method to fulfil the requirements for both communications and illuminations.