Peak-to-average power ratio reduction in all-optical orthogonal frequency division multiplexing system using rotated constellation approach

https://hal.archives-ouvertes.fr/hal-01088835/document

Performance improvement of a SOA-based coherent optical-OFDM transmission system via nonlinear companding transforms

In coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems, the high peak to average power ratio (PAPR) will causes serious signal degradation through the nonlinearity of modulator and fiber. In this paper, the PAPR reduction techniques based on wavelet packet transform (WPT) for CO-OFDM systems are proposed, the WPT is used instead of traditional fast Fourier transform (FFT). Moreover, two efficient PAPR reduction techniques are combined with the proposed WPT-OFDM. Simulation results show that the PAPR of proposed scheme combined with selective mapping (SLM) and partial transmit sequence in combination with clipping (clipping PTS) are optimized compared to the traditional FFT. Under the same conditions, while maintaining good performance in the BER compared to ordinary FFT. And the proposed WPT system provides the high spectral efficiency transmission without CP.

The PAPR reduction techniques based on WPT for CO-OFDM systems

High peak-to-average power ratio (PAPR) of the orthogonal frequency division multiplexing (OFDM) signal is one of the limitations to the transmission performance of an optical OFDM system. Many PAPR reduction techniques have been proposed in previous works. However, most of them only consider a single scheme while overlooking the complementary features of these techniques. We propose a twofold PAPR reduction technique called Hadamard transform combined with a partial transmit sequence (PTS) (HTCP). The proposed HTCP scheme combines the merits of two complementary techniques, i.e., Hadamard transform and PTS, to improve the performance of the optical OFDM system in terms of PAPR and bit error rate (BER). Furthermore, the side information generated in PTS is transmitted by pilot sequences which increase the utilization of subcarriers. Least square estimation is used to estimate the pilot signal’s phase to recover the side information. The HTCP scheme is theoretically analyzed in a direct-detection optical OFDM system. Simulation results show that the HTCP scheme has a better performance with regards to PAPR and BER compared with the case of applying only the Hadamard transform or PTS technique.

Twofold peak-to-average power ratio reduction technique in direct-detection optical orthogonal frequency division multiplexing system

The Inter-Carrier Interference (ICI) compensation for Coherent Optical Orthogonal Frequency Division Multiplexing (CO-OFDM) system has been studied in this paper. The purpose behind is to investigate the presence of ICI due to the impact of Laser Phase Noise (LPN) and Fiber Non-Linearity (FNL). Thereby, we propose a simple clipping scheme which represents an effective distortion algorithm to decrease the Peak to Average Power Ratio (PAPR) for 4QAM system. The method exhibits a significant process on ICI cancellation in CO-OFDM system. The OFDM signal is basically transmitted along 550km distance rated at 10Gbps single mode fiber for the coherent optical mode. The new findings show that the receiver sensitivity is highly improved below 10−3 FEC for laser power 5dBm; and archives about 1dBm to 2.4dBm when laser power becomes 8dBm at a typical clipping ratio of 0.6. In particular, the system exhibits a good performance over a 385km transmission distance in comparison to the conventional CO-OFDM. As a result, the proposed clipping shows that the system can enhance its the performance by reducing ICI in the CO-OFDM system; in addition to present a high robustness in BER metric against FNL by a clear reduction in PAPR.

李玉权

Papers

Fiber nonlinearity mitigation by PAPR reduction in coherent optical OFDM systems via biased clipping OFDM