Prediction of operative parameters of land-to-land and land-to-atmosphere wireless communication links

摘要

As was declared in our previous research published during 2006-2014, related mostly to terrestrial communication links, sub-urban and urban, and lesser - to land-atmospheric communication, the most important issue is to understand processes which distort information due to fast fading, as the source of the multiplicative noise, passing within the wireless communication links. The same processes occur with much stronger influence of the multiplicative noise on the data stream parameters because of higher Doppler effects caused by flying vehicles (aircrafts, helicopters, drones, etc.) with higher velocity comparing to the land moving vehicles (cars, buses, trains, etc.). In the previous publications were analytically obtained the time delay standard deviation, the bandwidth of coherency and the Doppler shift speeding only for primitive time-harmonic signals, usually analyzed in the literature, but not for the bandpass signal consisting both the modulated signal and the carrier signal. In this work, we present such characteristics of the modulated signal for the wireless land-to-land and land-to-atmosphere communication links. It is shown that the time delay of the bandpass signal in the land-atmospheric channels can be ranged from several to tens microseconds, which is higher than that occurring in the land-land communication links. This effect depends on the height of the atmospheric moving vehicle, its speed and orientation to the ground-based vehicle. As for the Doppler shift spread, it changes at the ranges not exceeding several kilohertz (kHz) with maximum Doppler shift ranged from several kHz to several hundred kHz, depending on the speed and spatial orientation of moving atmospheric vehicle. In all scenarios of consideration the bandwidth of coherency was ranged from tens to hundreds kHz, that is, was higher than the Doppler spread bandwidth. This allow to conclude that even for the land-atmospheric communication links the flat fast fading, which not so strong depends on the frequency of the carrier signal is usually observed. In other words, the multiplicative noise is not so predominant with respect to flat noise in land-atmospheric links.