Why is Raytracing gaining traction in higher frequency band communications?
Many research papers are now focusing on the ray-tracing method to provide communication between transmitter and receiver. To deploy the ray-tracing method, researchers are primarily focusing on higher frequency bands, such as Sub-6 GHz bands, UWB, or millimeter wave, among others. The main reason for this motivation is that we know that as frequency increases, wavelength decreases. We know that when a wavelength is very short, it is more easily reflected or refracted by surfaces such as a building wall, foliage, and so on. Furthermore, if we use the Sub 6 GHz band or millimeter wave, we will encounter a great deal of reflection and refraction from obstacles. On the other hand, in the context of reflection and refraction from obstacles' surfaces, we can say those frequency bands act as rays.
As we know from optics, when a light wave strikes an even plane, it is reflected with the same angle as the incidence angle. If the surface is slightly uneven, wave refraction along reflection occurs. If the surface is slightly uneven, refraction will win out over reflection. Another reason is that light waves have very short ranges in the hundreds of nanometers.
The same logic applies to higher frequency bands. Building walls, foliage, and other obstacles with reflective surfaces are usually even. Even if it is a little rough, keep in mind that the wavelengths of the above-mentioned bands are easily reflected due to their very short wavelength. And function as a light ray.
How does the raytracing model work?
The raytracing model is based on fundamental electromagnetic principles, fresnel coefficient, and farmat’s law. Fresnel coefficients basically tell us how much signal will be transmitted or reflected when transmitted signal bounces off walls of building or any obstacle. For example, for N number of walls, there are N-first order reflections, N(N-1) second order reflections, N(N-1)(N-2) third order reflections, and so on. MPCs due to LOS and reflective path arrives in receiver with different frequency or time delay, which is usually denoted as taps or nodes. From this we can calculate path length, then pathloss and received power. According to Fermat's theorem, a ray follows the direction that takes the least amount of time and occurs when the angle of incidence is identical to the angle of reflection or propagation.
Why is it gaining popularity?
It is gaining popularity because it adheres to fundamental electromagnetic theories such as the basic reflection rule, the two-ray reflection method, and so on. Furthermore, wave guide technology assists us in determining whether to emit electric fields vertically or horizontally. Raytracing is a straightforward process.
It can be extremely useful in indoor or UMi scenarios. Here, we can estimate the channel, determine the appropriate AoA and AoD for real-time tracking, and so on. It is a less expensive and less time-consuming method.
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UWB | Millimeter wave band | 5G | Difference Between Indoor and Outdoor Wireless Communication