Paper Info
Title
Phase noise influence in coherent optical OFDM systems with RF pilot tone: Digital IFFT multiplexing and FFT demodulation
Abstract
We present a comparative study of the influence of dispersion induced phase noise for CO-OFDM systems using Tx channel multiplexing and Rx matched filter (analogue hardware based); and digital FFT multiplexing/ IFFT demultiplexing techniques (software based). An RF carrier pilot tone is used to mitigate the phase noise influence. From the analysis, it appears that the phase noise influence for the two OFDM implementations is very similar. The software based system provides a method for a rigorous evaluation of the phase noise variance caused by Common Phase Error (CPE) and Inter-Carrier Interference (ICI) and this, in turns, leads to a BER specification. Numerical results focus on a CO-OFDM system with 1 GS/s QPSK channel modulation. Worst case BER results are evaluated and compared to the BER of a QPSK system with the same capacity as the OFDM implementation. Results are evaluated as a function of transmission distance, and for the QPSK system the influence of equalization enhanced phase noise (EEPN) is included. For both types of systems, the phase noise variance increases significantly with increasing transmission distance. An important and novel observation is that the two types of systems have very closely the same BER as a function of transmission distance for the same capacity. For the high capacity QPSK implementation, the increase in BER is due to EEPN, whereas for the OFDM approach it is due to the dispersion caused walk-off of the RF pilot tone relative to the OFDM signal channels. For a total capacity of 400 Gbit/s, the transmission distance to have the BER < 10-4 is less than 277 km. For an RF pilot located in the center of the OFDM band in a CO-OFDM implementation with n-level PSK channel modulation the current results suggest that the walk-off effect is equivalent to the EEPN impact in a single channel n-level PSK system with the same capacity. This observation is important for future design of coherent long-range systems since it shows that there is a free choice between CO-OFDM and a high capacity nPSK implementation at least as long as the phase noise influence is concerned.
Year
Venue
Keywords
2016
Journal of Optical Communications
coherent systems,orthogonal frequency division multiplexed systems,phase noise,rf pilot carrier,telecommunications
Field
DocType
Volume
Demodulation,Phase noise,Electronic engineering,Modulation,Matched filter,Engineering,Multiplexing,Electrical engineering,Pilot signal,Orthogonal frequency-division multiplexing,Phase-shift keying
Journal
abs/1607.04899
ISSN
Citations 
PageRank 
Journal of Optical Communications, Vol.33(3), 217-226, 2012
7
0.85
References 
Authors
5
6
Name
Order
Citations
PageRank
Gunnar Jacobsen13912.03
Tianhua Xu28816.35
Sergei Popov33916.08
Jie Li4163.12
Ari T. Friberg5223.51
Yimo Zhang67815.85