Performance Analysis of Dual-Hop UAV-Assisted mmWave Links Considering Orientation Fluctuations

In emergency scenarios, infrastructure of wireless networks is usually damaged and becomes out of service. Therefore, Unmanned Aerial Vehicles (UAVs) have been widely nominated as an alternative to provide prompt and efficient wireless connectivity. To this end, UAV-assisted communication systems are recently being under investigation. In this paper, the focus is on UAV-assisted dual-hop links in which the source, relay and destination can be either ground-based or aerial nodes. Specifically, the paper analyzes the performance of these links in terms of the outage probability (OP) and the bit error rate (BER) considering eight different setups of dual-hop UAV-assisted links operating over the millimeter wave (mmWave) band. Unlike others, the performance analysis is conducted considering practical models of the channel fading, path loss, antennas gain and UAVs' fluctuations. A generalized mathematical framework is followed to obtain the cumulative distribution function (CDF) and the probability density function (pdf) of the overall signal-to-noise ratio (SNR), which are utilized to characterize closed form expressions for the average OP and BER for all proposed setups. Analytical results are validated by Monte Carlo simulations which investigate the role of many setup parameters including the number of antenna elements, the fluctuation intensity, the transmit power and the modulation order. Moreover, results indicate that increasing the number of aerial entities in the link negatively affects its performance due to the impact of the fluctuations on the directional antennas in the mmWave band.