Mingliang Deng

OFDM-PON optical fiber access technologies

The introduction of OFDM into PON networks is to leverage the merits of OFDM to provide the flexibility and reduce the cost. In this paper, we present our latest works on OFDM-PON. Firstly, we propose and demonstrate a novel OFDM-PON upstream transmission architecture with traffic aggregation by orthogonal band multiplexing. The multiplexed 10-Gb/s OFDM signal is collectively received. We also conduct a proof-of-concept experiment to verify the architecture. Secondly, we propose and experimentally demonstrate wavelet packet transform based OFDM (WPT-OFDM) using real-valued transforms, which enables the cost-effective intensity modulation/direct detection (IM/DD). Unlike conventional FFT-based OFDM, the need for cyclic prefix is eliminated due to the time-frequency localization properties of the wavelet.

Constant envelope modulation enabled fiber nonlinearity mitigation for CO-OFDM transmissions

We propose an approach based on constant envelope modulation to mitigate fiber induced nonlinearities in CO-OFDM systems. The extensive simulation results demonstrate that the proposed scheme not only greatly mitigates the nonlinear sensitivity of CO-OFDM transmissions but also avoids the severe nonlinear tolerance degradation caused by inline dispersion compensation.

Reduced-Guard-Interval OFDM Using Digital Sub-Band-Demultiplexing

The overhead of cyclic prefix (CP) in coherent optical OFDM (CO-OFDM) tends to be too large for high-speed and long-haul optical fiber transmissions. We discuss and experimentally demonstrate a transmission of reduced guard interval OFDM (RGI-OFDM) with much reduced CP overhead based on digital sub-band demultiplexing. The proposed techniques are used to process a 66.7-Gb/s RGI-CO-OFDM signal ( ~ 20-GHz bandwidth) after 5440-km fiber transmission. The experiments show that it can reduce the overhead from 36.7% to 12.5%. We also optimize the digital signal processing in the filter bank for a better performance.

Wavelet packet transform–based optical orthogonal frequency-division multiplexing transmission using direct detection

Abstract. As an alternate to fast Fourier transform-based orthogonal frequency-division multiplexing (OFDM), wavelet packet transform (WPT)-based OFDM (WPT-OFDM) does not require cyclic prefix to avoid inter-symbol-interference. The wavelet has many varieties and therefore, it can provide more freedom for system design to suit different applications. We propose a real-valued WPT-OFDM that uses intensity modulation/direct detection. We also conduct an experiment to verify its performance through a 75-km standard single-mode fiber.

Significant overhead reduction of multi-band Tb/s coherent optical OFDM systems

The timing and optical laser phase of individual bands in multi-band OFDM are correlated. We significantly reduce the OFDM overhead through using FFT window synchronization for channel estimation and sharing pilot subcarriers for phase estimation.

Performance of OFDM with PCF configuration in WDM-PON

In this paper, we conduct a simulation for WDM-PON with coherent optical OFDM using partial carrier filling (PCF) configuration. The impact of PCF patterns and PCF factor on transmission performance at 40-Gb/s over 100 km are studied and simulated. The influence of power into fiber is examined to obtain the optimal value corresponding to the expected transmission distance.