what block should be used for creating optical fiber channel in designing ocdma system in simulink? sir please answer it.......

i am designing optical code division multiple access (OCDMA) system and i got stuck while designing channel because it should be optical fiber link but in simulink there is no such type of block. so please tell me which block can work same as optical fiber channel. i am waiting for your favourable reply. please reply as soon as possible because its very urgent for me.

Answer 1

[Prateekshya]

Hello Nikita,

In Simulink, designing an Optical Code Division Multiple Access (OCDMA) system with an optical fiber link can be challenging due to the lack of specific optical fiber blocks in standard Simulink libraries. However, you can simulate an optical fiber channel by using available blocks and techniques to approximate its behavior. Here are some suggestions:

Use MATLAB Add-Ons

• OptiSystem: This is a third-party software that integrates with MATLAB and Simulink, offering comprehensive tools for optical fiber communication system design. You can use OptiSystem to simulate optical fibers and then interface it with Simulink.
• Photonics Libraries: Look for photonics or optical communication libraries available on MATLAB Central File Exchange or other sources. These libraries might offer specialized blocks for simulating optical components.

Simulate Optical Fiber Characteristics

If you want to approximate an optical fiber channel using standard Simulink blocks, you can simulate key characteristics of optical fibers such as attenuation, dispersion, and non-linear effects:

• Attenuation: Use a Gain block to model the signal attenuation over the fiber length. Set the gain to represent the loss (e.g., -0.2 dB/km for typical fiber).
• Dispersion: Use a Transport Delay block to simulate the dispersion effects. The delay can be adjusted based on the fiber length and dispersion parameters.
• Noise and Non-linear Effects: Use Additive White Gaussian Noise (AWGN) blocks to simulate noise. For non-linear effects, you might need to use custom MATLAB Function blocks to implement specific models.

Custom MATLAB Function Blocks

If you have specific mathematical models for the optical fiber behavior, you can use MATLAB Function blocks to implement these models directly in Simulink. This allows you to define custom equations and simulate complex effects.

Simulink Communication System Toolbox

If you have the Communication System Toolbox, you can use some of its blocks to simulate the digital aspects of the OCDMA system, such as encoding and decoding, while approximating the optical channel effects as described above.

Example Setup

Here is a simple example setup using basic blocks:

1. Signal Source: Use a Signal Generator block to create your input signal.
2. Attenuation: Use a Gain block to model signal loss.
3. Dispersion/Delay: Use a Transport Delay block to simulate dispersion.
4. Noise: Use an AWGN block to add noise to your signal.
5. Receiver: Use appropriate blocks to decode and process the received signal.

I hope this helps!