URLLC Challenges in NTN: An Analysis of O-RAN Split-Function Architectures

This article presents a comprehensive analysis of different functional splits (FS) in an open RAN-based unmanned aerial vehicle (UAV) non-terrestrial networks (NTN) architecture for ultra-reliable low-latency communication (URLLC). We systematically analyze and compare the effectiveness of different FSs, focusing on their impact on UAV computational complexity and overall network latency and reliability for URLLC users. Through extensive simulations, we assess the tradeoffs between computational complexity, front-haul bandwidth requirements, and network reliability for various FS options with a particular focus on URLLC traffic. Our results demonstrate that FS-7.2x outperforms other configurations, achieving superior latency performance and enhanced reliability by efficiently balancing onboard processing and front-haul bandwidth utilization. These findings provide critical insights for network designers in optimizing O-RAN configurations for UAV-based NTN, ensuring robust and low-latency communication for next-generation wireless applications.