Odd-even symbol dispersion pre-compensation technique utilizing interleaved dual-FIR filters in IM-DD systems.

An interleaved odd and even samples electrical dispersion pre-compensation (pre-EDC) scheme with low complexity is proposed to alleviate the severe distortions caused by frequency-selective fading due to chromatic dispersion (CD) in the intensity-modulation and direct-detection (IM-DD) optical transmission systems. This scheme utilizes training-based interleaved dual finite impulse response (FIR) filters for odd and even samples pre-compensation, respectively, referred to as training-based ID FIRs-pre-EDC. Additionally, a Tx and Rx side joint scheme is proposed to enhance the performance of the training-based ID FIRs-pre-EDC by implementing the efficient reduced state maximum likelihood sequence estimation (RS-MLSE) at the receiver side.

LUT enabled low-complexity electrical dispersion pre-compensation scheme for IM-DD systems.

Frequency selective fading caused by chromatic dispersion (CD) and direct detection is the primary impediment for IM-DD systems in achieving a large capacity-distance product. Gerchberg-Saxton (GS) based electrical dispersion pre-compensation (pre-EDC) schemes enhance IM-DD systems' robustness against chromatic dispersion (CD), but their high computational complexity limits practical implementation. In this Letter, a novel, to the best of our knowledge, low-complexity pre-EDC scheme enabled by the cluster-assisting look-up table (CLUT) technique is proposed to further reduce the computation complexity of the non-iterative FIR-based pre-EDC scheme, in which convolution operation is replaced by tables look-up and accumulation processing.

Neural network-based electrical dispersion pre-compensation for a 56 Gb/s PAM-4 over an 80 km fiber in intensity-modulation and direct-detection systems.

A neural network (NN)-based electrical dispersion pre-compensation (pre-EDC) scheme in intensity-modulation and direct-detection (IM/DD) systems is proposed and experimentally demonstrated in this Letter. The scheme enables 56 Gbit/s four-level pulse amplitude modulation (PAM-4) generation at a transmitter over an 80 km single-mode fiber (SMF) transmission in the C-band. The NN is utilized to better fit nonlinear phase-amplitude transformation due to the chromatic dispersion (CD) in IM/DD systems, in place of the existing Gerchberg-Saxton (GS) iterative algorithm and linear GS-based finite impulse response (GS-FIR) non-iterative compensation schemes.

Non-line-of-sight optical wireless communication system enabled by wavefront shaping for multi-user indoor access.

In this Letter, we experimentally investigate a non-line-of-sight (NLOS) optical wireless communication (OWC) system that utilizes wavefront shaping techniques to realize simultaneous data transmission for multiple users. Wavefront shaping techniques are employed to address the issue of low intensity of diffusely reflected light at the receiver in NLOS scenarios for indoor high-speed access. To achieve communication path planning and tracing for two different users in free-space optical communication, the pixels of the spatial light modulator (SLM) are divided into two halves to separately manipulate the wavefront of two independent data carriers centered at different wavelengths.

Modified low-bandwidth sub-Nyquist sampling receiving scheme in an IM/DD OFDM system enabled by improved optical shaping.

In this paper, a modified low-bandwidth sub-Nyquist sampling receiving scheme enabled by optical shaping is investigated in an intensity modulation/direct detection (IM/DD) orthogonal frequency-division multiplexing (OFDM) system, which can reduce the sampling rate and analog bandwidth of an analog-to-digital converter (ADC) at the receiving end. By changing the phase matrix of preprocessing, the modified scheme can distinguish different groups of data only by controlling the delay of the shaping module. In addition, the proposed RF sharing architecture can further reduce the cost and increase the feasibility of the scheme.

Demonstration of 100-Gbit/s 32-QAM signal transmission in a radio-over-fiber system with 2-bit DAC.

In this Letter, a low-cost radio-over-fiber (RoF) system at the Ka band based on a low-resolution digital-to-analog converter (DAC) is proposed and investigated. The noise shaping (NS) technique is adopted to suppress the in-band quantization noise induced by the low-resolution DAC. To evaluate the performance of the proposed RoF system, the transmission of a 80/100-Gbit/s dual-polarization 16/32-QAM signal over 20-km single-mode fiber (SMF) and 1-m 2 × 2 multi-in multi-out (MIMO) wireless link coupled with a 2/3/4-bit DAC is experimentally demonstrated.

Decision region partition aided MLSE for O-band 65-Gbaud PAM-4 system over 40-km transmission with a severe bandwidth constraint.

Maximum likelihood sequence estimation (MLSE) is an optimal solution to realize sequence detection in the digital signal processing (DSP) of short reach O-band intensity modulation/direct detection (IM/DD) systems with bandwidth limitation. However, traditional MLSE requires relatively high computational complexity for short reach optical interconnect. Although the computational complexity of single-symbol sequence detection is quite low, the capability of combating with the inter symbol interference (ISI) is inadequate.

Daily versus three-times-weekly azithromycin in Chinese patients with non-cystic fibrosis bronchiectasis: protocol for a prospective, open-label and randomised controlled trial.

Introduction: Non-cystic fibrosis bronchiectasis (NCFB) brought a heavy healthcare burden worldwide. Macrolide maintenance therapy was proved to be helpful in reducing exacerbation of NCFB. However, the optimal dosing regimens of macrolides have not been determined, and its efficacy in Chinese NCFB population has not been validated.