BACKSCATTERING AND PULSE SIMULATION IN OPTICAL FIBER

I want to simulate the simplest OTDR as possible. For example, only considering the backscattering of the pulse, and attenuation. What is the simplest way to do it in MatLab? I need to enter fiber parameters (refractive index, distance, for example), pulse width, power (amplitude), etc., and get the receiving power and backscattered power. How can I do it?