Chromatic Dispersion Estimation Based on CAZAC Sequence for Optical Fiber Communication Systems

Abstract

We propose a chromatic dispersion (CD) estimation method based on constant amplitude zero-autocorrelation (CAZAC) sequence and fractional Fourier transform (FrFT) algorithm for optical fiber communication systems, which extends the application of CAZAC sequence. By applying FrFT on the CAZAC sequence signal, the optimal order is searched and employed to estimate the accumulated CD because that the CAZAC sequence shares similar properties with chirp signal. We demonstrate the feasibility of the proposed method by the simulation of a 28 GBaud polarization-division-multiplexed (PDM) quadrature phase-shift keying (QPSK) optical fiber communication system. The error of CD estimation is less than 70 ps/nm for the standard single mode fiber (SSMF) link of 2000 km with OSNR in the range of 10-20 dB and the launch power in the range of 0-4 dBm per channel in a five channel system. It shows that the method is robust to ASE noise and optical fiber nonlinearity. Furthermore, the proposed method has been experimentally verified with the error of CD estimation less than 50 ps/nm after 100-900 km fiber link transmission.

Preamble-Based Symbol Timing Algorithms in OFDM Systems

“…𝑆 𝑁 denotes PN sequence of length N. Moreover, 𝜊 represents the Hadamard product operator between vectors. Correlation and energy equations are given in Equation (15) and Equation (16).…”

“…CAZAC sequence is exploited due to its ideal correlation properties in many applications such as channel estimation and synchronization [13][14][15]. One of the CAZAC type sequence, Zadoff-Chu sequence, is used in LTE and LTE-A standards.…”

Optical Performance Monitoring in Mode Division Multiplexed Optical Networks

“…The next important aspect is CD monitoring. To achieve this, training sequence-based approaches have been proposed [18]- [20]. In [18] a constant amplitude zero-autocorrelation (CAZAC) sequence is used.…”