Swarm UAV Communications with Diversity and Delay Trade-off using Mobile Caching

Swarm unmanned aerial vehicles (UAVs) are critical to a number of smart city applications, such as distributed sensing and disaster relief. Connected UAVs often operate in complex environments where the communication channels suffer fading loss. Achieving full spatial diversity is important for reliable communication, but cannot be guaranteed at any given time. Here, we show that delay tolerant transmission via caching can enable full diversity. To achieve this, we improve the decode-and-forward cooperative relaying scheme, where the number of successful relay UAVs increases with each additional cooperation stage. We demonstrate a trade-off between the achievable bit error rate and the necessary delay via caching. The results show that a small delay enabled by UAV caching can enable full diversity at SNR levels 10–$;100 \times$ lower in most mobile swarm cases. The proposed protocol can dynamically trade-off transmission reliability with caching capacity and enable reliable UAV swarm coordination in complex environments.