atharva253 / terahertz-wireless-systems

Framework for Terahertz Wireless Systems

This repository provides a Matlab-based framework to perform numerical analysis on channel models obtained upon combining small-scale fading and antenna misalignment effects. This analysis can also be verified using Monte-Carlo Simulations. We have also included code to particularly work with the Fluctuating Two Ray (FTR distribution), which is a recent addition to the channel models of Terahartz Wireless Systems. To use this code, clone this repository to your project folder.

Why Fluctuating Two Ray?

A recent measurement campaign was conducted to measure the THz channel with operation at 304.2 GHz and 8 GHz bandwidth. Gradient descent was used to fit the distribution parameters for Gaussian, Rician, Nakagami-m and FTR distributions. FTR distribution performed a much better fit than other models. Morever, FTR distribution is a generalization of a lot more commonly used probability distributions for small scale fading.

Fundamentals of FTR:

The small-scale fluctuations in the amplitude of a signal transmitted over a wireless channel can be modeled by the superposition of a set of N dominant waves, referred to as specular components, to which other diffusely propagating waves are added.

X + jY is a complex Gaussian random variable, such that X and Y follow a Normal distribution with zero mean and standard deviation sigma. The random phase follows a Uniform distribution between zero and 2 pi. The amplitudes Vn are constants.

FTR Probabability Distribution:

Details on the use of this code:

• get_ftr_pdf.m : Returns a function handle to the FTR PDF. Can be used to verify integrals and for numerical analysis.
• get_combined_pdf.m : Returns a function handle to the Combined FTR + Misalignment errors PDF.
• d_calc.m : Helper function to calculate the value of d as given in the FTR Probability Distribution expression above.
• my_asso_legendre_func.m : This function is be used to calculate Associated Legendre function for real parameters and complex argument. [For details, refer to I. S. Gradshteyn and I. M. Ryzhik, Table of Integrals, Series, and Products, 7th ed. Academic Press, 2007.]
• THz_Pathloss.m : Helper function to calculate the deterministic path loss due to molecular absorption.
• randpdf.m : Helper function to generate pseudo-random numbers from a user defined distribution. [Credits: Adam Nies³ony, Opole University of Technology, Poland]
• get_hf_thz.m : Helper function to generate pseudo-random numbers from the FTR distribution. This is an efficient alternative to randpdf.m, particularly for FTR Monte-Carlo simulations. [For details, refer to J. M. Romero-Jerez, F. J. Lopez-Martinez, J. F. Paris, and A. J. Goldsmith, “The fluctuating two-ray fading model: Statistical characterization and performance analysis,” IEEE Trans. Wireless Commun., vol. 16, no. 7, pp. 4420–4432, Jul. 2017.]
• Combined_thz_experiment.m : A sample virtual experiment to demonstrate the use of all the above functions. Feel free to make changes as required for your own purpose.

Contributors:

Atharva Anand Joshi, Undergraduate Student

Pranay Bhardwaj, PhD Researcher

Dr S. M. Zafaruddin, Senior Member, IEEE

Birla Institute of Technology and Science, Pilani