טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentItzhak Sigron
SubjectCarrier Phase Estimation with Multi-Symbol Delay
Detection for Single-Carrier and Multi-Carrier
DepartmentDepartment of Electrical Engineering
Supervisor Full Professor Nazarathy Moshe
Full Thesis textFull thesis text - English Version


Abstract

The topic of this thesis is Carrier Phase Estimation (CPE) algorithms in coherent fiber optics communication for synchronizing the receiver - mitigating the phase noise induced by the transmitter and Receiver lasers, while providing improved overall performance.

CPE is a critical component in coherent optical receivers for high bandwidth transmission. The recently suggested CPE algorithm, using Differential Precoder (DP) at the transmitter and Multi Symbol Differential Detection (MSDD) at the receiver was shown to achieve superior performance over the most common prior-art CPE algorithm, the M-POWER algorithm. Moreover the algorithm suggested has lower complexity implementation. In modern DSP-oriented coherent receivers (RX), the issue of frequency estimation is significant, as very rapid phase rotations are caused by the frequency difference between the signal and the freely running local oscillator (LO), henceforth referred to as Frequency Offset (FO), tending to degrade the performance of the carrier phase estimation.

This thesis is a straight follow on to the research done in MSDD, introducing an improved real-time hardware parallelization implementation of the MSDD algorithm (without increasing the complexity), which improves significantly its performance in higher constellations (16QAM) and higher linewidth phase noise. Furthermore, a few improvements to the MSDD will be disclosed, the non-causal MSDD and the Differential reference MSDD (DR-MSDD), that retain good performance even while using low quality lasers.

In order to work with high spectral efficiency, communication systems are moving towards multi carrier modulation (such as OFDM). In this thesis we introduce a unique CPE algorithm for OFDM and DFT spread OFDM (DS-OFDM) based on the Single Carrier (SC) DP-MSDD CPE algorithm.

In the final part of the thesis we will be evaluating the CPE algorithms above in dispersive optic fibers, introducing the Enhanced Equalization Phase Noise effect for single-carrier and multi-carrier modulations and additionally the Cyclic Prefix Enhanced Phase noise effect for multi-carrier modulations, showing ways of mitigating the latter.