HexRAN: A Programmable Multi-RAT Platform for Network Slicing in the Open RAN Ecosystem

In recent years, the Open Radio Access Network (O-RAN) architecture has emerged as a major driving force for programmability in cellular networks and is recognized as a key enabler for network slicing within 5G and beyond. While O-RAN harbors the potential to revolutionize cellular access networks, the absence of an open platform for use case prototyping has served as an impediment to its widespread adoption. The situation is further compounded by the fact that O-RAN's flagship use case, network slicing, presents a rigid dichotomy. On the one hand, systems research in the slicing domain is largely centered around LTE, while, on the other hand, 3GPP slicing specifications exclusively cater to 5G Standalone (SA). From a practical standpoint, most commercial networks today use a mix of 4G, 5G NSA (Non-standalone), and 5G SA, necessitating the need for solutions across all radio access technologies (RATs). With a view to addressing these challenges, this paper introduces HexRAN, a first of its kind purpose-built multi-RAT O-RAN compliant access network. Key highlights of HexRAN include support for LTE, 5G NSA, and 5G SA with full disaggregation, a novel Programmable Protocol-level API repository, a multi-RAT RAN slicing framework, a modular and extensible E2 Agent, and a new O-RAN service model in support of slicing. Furthermore, the paper also includes a comprehensive system evaluation addressing the key themes of scalability and disaggregation, the slicing framework's impact, and system performance. The results thus obtained showcase that not only is HexRAN the most feature-complete RAN platform to date, it also offers a significant performance advantage over the prior art.