  Fifth-generation (5G) cellular networks have led to the implementation of
beyond 5G (B5G) networks, which are capable of incorporating autonomous
services to swarm of unmanned aerial vehicles (UAVs). They provide capacity
expansion strategies to address massive connectivity issues and guarantee
ultra-high throughput and low latency, especially in extreme or emergency
situations where network density, bandwidth, and traffic patterns fluctuate. On
the one hand, 6G technology integrates AI/ML, IoT, and blockchain to establish
ultra-reliable, intelligent, secure, and ubiquitous UAV networks. 6G networks,
on the other hand, rely on new enabling technologies such as air interface and
transmission technologies, as well as a unique network design, posing new
challenges for the swarm of UAVs. Keeping these challenges in mind, this
article focuses on the security and privacy, intelligence, and
energy-efficiency issues faced by swarms of UAVs operating in 6G mobile
networks. In this state-of-the-art review, we integrated blockchain and AI/ML
with UAV networks utilizing the 6G ecosystem. The key findings are then
presented, and potential research challenges are identified. We conclude the
review by shedding light on future research in this emerging field of research.
