Long Haul Polarization Multiplexed QAM-M Fiber Optic Coherent Communication Systems


OCSim Modules

Modern Fiber Optic Communication Systems Simulations with Advanced Level Matlab Modules

Module 16

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Long Haul Polarization Multiplexed QAM-M Fiber Optic Coherent Communication Systems


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Main Module

fiber_prop_vec_single_chan_qam.m

This module simulates Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic coherent communication systems with (1) loss (2) nonlinearity (3) second order dispersion and (4) third order dispersion effects in N spans of single mode fibers and N in-line amplifiers.
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This Module calls the following Sub Modules and Components:

(1) amp_vec.m
Inline amplifier is realized using this function. This amplifies the polarization multiplexed signal.

(2) ber_calc_qam.m
Calculates the BER by comparing the received bit pattern with the transmitted bit pattern.

(3) constellation_diagram.m
Plots the constellation.

(4) down_sample_CD.m
The number of samples per symbol for modeling the fiber optic system may be different from that used in DSP. This code provides down-sampling of the received signal by a factor that is suitable for DSP processing. 

(5) fiber_prop_vec_no_rot.m 
This code solves the Manakov equations using a split-step Fourier scheme.

(6) gauss.m 
A Gaussian bandpass filter is introduced. The half-bandwidth (‘bw’) should be specified. This could also be used as a low pass filter and in this case, ‘bw’ is the 3-dB bandwidth.

(7) norm_spectrum.m 
This function plots the normalized spectrum of the signal. 

(8) opt_rect_filt.m 
Rectangular filter is introduced to demultiplex the central channel. The half-bandwidth (f_0) should be specified.

(9) power_meter.m
Calculates the average power in dBm.

(10) power_meter_vec.m
Calculates the average power in dBm of the polarization multiplexed signal.

(11) QAM_modulator_nyquist.m
This code generates the QAM data. Arbitrary QAM-M can be generated. For example, when XX=4 and YY=4, we get QAM-16. When XX=8 and YY=8, we get QAM-64. This code can also generate QPSK data by setting XX=2 and YY=2. Nyquist pulses are generated with arbitrary roll-off factors.

 

 


Selected Simulated Results Using this Module 


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Normalized Spectrum at the Transmitter

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 


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Constellation Diagram at the Transmitter

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 


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Constellation Diagram After the CD Compensation

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 


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k-factor vs BER

(Total nonlinear phase accumulated over the fiber optic link due to SPM is k times
nonlinear phase. k depends on the system parameters such as CD and loss and
hence, it needs to be optimized)

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 


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Constellation Diagram after the SPM Compensation

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 


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Normalized Spectrum at the Receiver

(Long Haul Polarization Multiplexed (PM) QAM-M Fiber Optic Coherent Communication Systems)

 

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OCSim Modules details can be seen by clicking the pages below:

OCSim Modules Overview OCSim Modules (1-18) in the Package

Module (1a) | Module (1b) | Module (1c) | Module (2a) | Module (2b) | Module (2c) | Module (3a) | Module (3b) | Module (4a) | Module (4b) | Module (4c) | Module (4d) | Module (5) | Module (6a) | Module (6b) | Module (7) | Module (8a) | Module (8b) | Module (8c) | Module (9a) | Module (9b) | Module (10) | Module (11a) | Module (11b) | Module (12) | Module (13) | Module (14) | Module (15) Module (16) Module (17) Module (18)


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