The LTE Ray Tracing Model involves analyzing electric wave propagation by using the ray tracing method and obtaining the field strength of received signals through theoretical calculation. Some LTE network uses the higher part of the UHF band such as 2.3 GHz and 2.6 GHz.
The wavelength of the radio wave is several centimeters. Therefore, obstructions in the propagation environment are often larger than the wavelength of the radio wave. In this case, the ray tracing method can be used to analyze wave propagation.
In addition, geological information technologies allow you to identify each building in a city as a right prism in a high precision degree. Such a right prism is identified by the top coordinate of the polygon at the bottom and height.
The basic idea of the ray tracing method is as follows:
- Determine the position of a transmission source. Identify all the propagation routes from the transmission source to each receive point, that is, the test point, according to the features and layout of the buildings on the 3D map.
- Determine reflection and diffraction losses based on the Fresnel equation and the geometrical or uniform theory of diffraction. In this case, the field strength of each route to each test point can be obtained. Perform the same point coherence stacking of field strengths of all routes to obtain the total received field strength of each test point.
The LTE Ray Tracing Model is integrated in common commercial planning software This model, however, requires highly precise (at least to within 5 meters) digital maps that contain 3D building information.
The prediction accuracy of the model is closely related to the precision of the digital maps and accuracy of site engineering parameters, such as the antenna position, height, direction angle, and down-tilt angle. Due to the cost, the LTE Ray Tracing Model is used only in network planning in densely populated areas of large cities.