Comparison of Intra-Channel Nonlinearity Tolerance between Reduced-Guard-Interval CO-OFDM Systems and Nyquist Single Carrier Systems

Demonstration of Dispersion-Enhanced Phase Noise in RGI CO-OFDM Systems

“…First, with the ECL/ECL configuration, the system with N I F FT = 256 performs slightly worse than the other two systems. This is caused by the reduced tolerance to fiber nonlinearities since for symbols with a larger N I F FT the peak-to-average power ratio (PAPR) increases and the de-correlation between subcarriers resulting from the CD-induced walk-off is reduced [10]. In the ECL/DFB configuration with CPE compensation, the system with N I F FT = 64 has the worst performance due to the largest DEPN.…”

Decision-aided sampling frequency offset compensation for reduced-guard-interval coherent optical OFDM systems

“…Fortunately, for the RGI CO-OFDM system, the symbol size is not restricted by the accumulated CD and can be designed based on other requirements. Former studies found that OFDM systems with a smaller symbol size are more robust to laser phase noise and fiber nonlinearity, but these systems have more side lobe power leakage and thus are more sensitive to narrow filtering effects (when the FFT size < 100) [5,6]. Therefore, a symbol size of 128 samples would be a suitable choice for optical transmission considering the overall conditions.…”

“…This novel scheme enables the use of a small OFDM symbol size while maintaining a reduced CP overhead (≤5%). Moreover, a small OFDM symbol size (e.g., FFT size N DFT ) provides some additional benefits: (1) a reduced computational effort, (2) a reduced training symbol (TS) overhead, (3) a faster channel tracking speed, (4) a higher tolerance to laser phase noise, and (5) an potentially improved fiber nonlinearity tolerance [1][2][3][4][5][6]. Therefore, RGI-CO-OFDM is a promising variation of CO-OFDM systems.…”

Investigation of Coherent Optical Multiband DFT-S OFDM in Long Haul Transmission

“…In the meantime, for OFDM systems, discrete Fourier transform spread (DFT-S) OFDM has been proposed to reduce PAPR, and mitigate the fiber nonlinearity [2]. Both Nyquist-SC and DFT-S OFDM can effectively overcome some of their intrinsic drawbacks, and achieve similar transmission performance, which may be promising techniques for future ultra long-haul transmission [3], [4]. Manuscript Recently, DFT-S OFDM has been combined with orthogonal band multiplexing to achieve a high transmission capacity [2], [5].…”