On Reliability in Downlink Data Dissemination over Opportunistic Multiple Hops in UAV-assisted FANET

Unmanned aerial vehicles (UAVs) acting as cooperative relays in FANETs are a viable way to improve the coverage and performance of current communication networks. Monitoring, surveillance, and telemetry applications are all possible with UAVs. The UAV-assisted cooperative relay network is investigated in a downlink communication scenario over a Nakagami-m fading environment, passing observations to a ground control station (GCS) for analysis. Decode-and-forward (DF) relaying and half-duplexed mode (HD) communication are considered to be used by the relaying UAVs. The use of an opportunistic constellation of UAVs to create a multi-hop serial link is discussed and contrasted to multiple dual-hop links operating in tandem. In the case of multiple dual-hop links, the maximal ratio combining (MRC) technique is being used to combine signals that are sent from the source to the destination via multiple intermediate relays, and this technique is compared to selection combining (SC). For single and multiple relays cases, analytical expressions for transmission times, end-to-end SNRs, and system outage probability are presented. Changing the link SNRs and observing system reliability in terms of probability of outage in various settings is used to investigate the impact of increasing the number of intermediate relays and channel information rates. To validate the analytical results, Monte Carlo simulations are used. The results show that multiple dual-hop links employing MRC perform better than other system settings, and that performance improves as the number of relays and channel state information (CSI) increases, but that the communication range is limited. Multi-hop serial communication can, however, facilitate range extension applications at the cost of diminished reliability. In FANET design, the tradeoffs presented by both configurations must be considered.