Toward Next Generation Open Radio Access Network--What O-RAN Can and Cannot Do!

The open radio access network (O-RAN) describes an industry-driven open architecture and interfaces for building next generation RANs with artificial intelligence (AI) based control. This paper dissects the O-RAN framework and provides a unique assessment of what it enables and where its current shortcomings are. This was motivated by a user survey that we conducted with responses from representative wireless researchers and developers from industry, academia, and government. The survey shows that the physical and medium access control layers are of most relevance to researchers and that nearly 80% believe that the O-RAN architecture will drive future cellular network innovations and deployments. The major contributions of O-RAN are the open interfaces among RAN modules and the specifications of different control loops that facilitate data driven network configuration and operation using AI. These AI controllers are encapsulated as xApps that can be introduced to control communications, networking, or service functions. The important O-RAN limitations relate to security, scope of AI control, and latency. We conclude this paper by indicating how specific limitations can be overcome in future O-RAN architecture revisions.