Modern Fiber Optic Communication Systems Simulations with Advanced Level Matlab Modules
Digital Signal Processing
QPSK Fiber Optic Communication Systems with Laser Phase Noise Compensation through Digital
Signal Processing (DSP)
(1) Use the Existing Modules / Components for Your Research Papers, Research Projects, Theses and Lab Simulation Experiments.
(2) Modify the Modules / Components to the Next Level for Your Research Papers, Research Projects and Theses.
(3) Integrate Different Modules / Components in the OCSim Package to Realize Your Own Fiber Optic Communication Systems.
(4) Modify the Modules for Co-Simulations with the Third Party Commercial Optical Communication Systems Softwares.
Compensation of laser phase noise in a coherent QPSK system.
This Module calls the following Sub Modules and Components:
This function introduces laser phase noise as a Wiener process. Laser linewidth should be provided.
This function introduces the same phase over the entire symbol interval.
This function describes the fiber propagation.
This function describes optical amplifier.
The receiver is modeled as a low pass second order gaussian filter.
This function gets one sample per symbol.
This function compensates for phase noise using Viterbi-Viterbi algorithm.
Explore Further this Module:
11a.1 Change the linewidths of Tx laser and LO from 25 kHz to 1 MHz and observe the constellation diagrams before and after the phase compensation. Write a program to calculate the phase variance. Plot the phase variance before and after the phase compensation.
11a.2 Set the linewidths to 0 Hz and observe the constellation diagrams before and after the phase compensation. Can the laser phase noise compensator compensate for amplifier noise? Explain.
11a.3 Set the linewidths to 100 kHz. Change the transmission distance from 200 km and 1000 km. Find the optimum block size in each case.
11a.4 Design and simulate following coherent QPSK fiber optic system links with digital signal processing:
28 GBaud, 20 span coherent QPSK fiber optic system link
10 GBaud, 60 span coherent QPSK fiber optic system link
28 GBaud, 20 span Nyquist pulse coherent QPSK fiber optic system link
10 GBaud, 60 span Nyquist pulse coherent QPSK fiber optic system link
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n GBaud, N span coherent QPSK fiber optic system link
n GBaud, N span Nyquist pulse coherent QPSK fiber optic system link
Choose the desired values of n and N for simulations.
Modify to DP-QPSK optical Communication systems. Scientific and Programing support is available for modifying to DP-QPSK optical systems.
Selected Simulated Results Using this Module
Block Diagram of an IF and Phase Compensator used for Simulation
IF = intermediate frequency, Demux = demultiplexer, Phase Comp = block phase estimator and compensator, and Mux= multiplexer
Simulation Setup – 1
Demultiplexing of the Data into K – Blocks with Each Block Consisting of N Samples used for Simulation
Simulation Setup – 2
Block Diagram of a Block Phase Estimator and Compensator for k-th Block used for Simulation
Simulation Setup – 3
Constellation Diagram Before Laser Phase Noise Compensation
Constellation Diagram After Laser Phase Noise Compensation