OCSim Modules: Module 7

Module 7

Communication Systems

(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.

fiber_prop_linear_system.m

An intensity modulated direct detection (IMDD) fiber optic system is simulated. Gaussian pulses are used. Fiber dispersion and loss are taken into account, but fiber nonlinear effects are ignored. When the eye is nearly closed, Q-factor calculation may not be accurate.

This Module calls the following Sub Modules and Components:

(1) fiber.m
Signal spectrum is multiplied by the linear fiber transfer function (takes into account fiber loss and dispersion, but ignores nonlinear effects).

(2) amp.m
Here, amplifier provides the gain G and it adds noise whose PSD is given by Eq. (1) (see the manual). The amplifier noise is modeled as a white noise with Gaussian distribution. The amount of noise added can be changed by varying nsp.

(3) gauss.m
The optical receiver is modeled as a second order Gaussian filter. The bandwidth of the filter is deltf.

(4) eyediagram.m
This function plots the eye diagram.

(5) computeq.m
This function calculates the mean and variances of bit ’0’ and ’1’ and Q-factor.

Explore Further this Module:

7.1 Change the excess noise-factor from 1 to 10 and plot the Q-factor (or BER) versus . (Note: for practical amplifiers lie in the range of 1.5 to 5).

7.2 Let = 4. Change the Rx bandwidth delft from 0.4*B to 3*B where B is the bit rate. Find the optimum Rx bandwidth. Plot Q-factor as a function of Rx bandwidth.

7.3 Let = 1.5. Change the input power from -5 dBm to 5 dBm and plot the Q-factor (or BER) as a function of fiber launch power.

7.4 Let = 1.5. Remove the dispersion compensating fiber and study the performance (Q-factor or BER) as a function of dispersion coefficient ( ) of the transmission fiber, which ranges from -0.5 ps.ps/km to -22 ps.ps/km. To have a BER of 2X10-3, plot the maximum transmission distance as a function of dispersion coefficient.

7.5 In a dispersion managed fiber with full dispersion compensation, reduce the amplifier spacing by 4 and increase the number of amplifiers by 4 so that the total transmission distance is the same as before. Does the performance improve? Provide explanation.

7.6 Modify the source code so that the raised-cosine NRZ pulses are used in the electrical domain instead of Gaussian pulses. Repeat (i)-(v).

7.7 Design and simulate following IMDD fiber optic system links:

10 Gb/s, 40 span IMDD fiber optic system link
28 Gb/s, 20 span IMDD fiber optic system with inline dispersion compensation link
40 Gb/s, 20 span IMDD fiber optic system with inline dispersion compensation link
40 Gb/s, 20 span IMDD fiber optic system with dispersion managed fiber link
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n Gb/s, N span IMDD fiber optic system link
Choose the desired values of n and N for simulations.

Simulate more:

Switch on to Nonlinearity to design and simulate nonlinear IMDD fiber optic system links.

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. (Long Haul Dispersion Managed Intensity Modulated Direct Detection (IMDD) Fiber Optic Communication Systems)

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. (Long Haul Dispersion Managed Intensity Modulated Direct Detection (IMDD) Fiber Optic Communication Systems) .

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