NexRAN: Closed-loop RAN slicing in POWDER - A top-to-bottom open-source open-RAN use case
Technical Report , University of Utah. 2021.
Much like earlier “network softwarization” efforts, the Open RAN concept is poised to have a transformative impact on the manner in which radio access networks (RANs) are realized and operated. The inherent complexity of the RAN ecosystem and the fact that it is rapidly evolving makes Open RAN a rich area of research into use cases, system realization, security etc. This same complexity, however, hampers research efforts. Specifically, there is a lack of end-to-end open source software and fully developed use cases associated with the Open RAN ecosystem. Further, to truly advance the state-of-the-art will require use cases to be explored in realistic wireless environments. This paper describes our efforts to address these shortcomings by realizing NexRAN, a top-to-bottom open-source Open RAN use case in the POWDER mobile and wireless research platform. Specifically, NexRAN allows closed-loop control of a RAN slicing realization in an O-RAN ecosystem. RAN slicing is implemented in the srsRAN open source mobility stack and is exposed through a custom service model to the NexRAN xApp executing on a RAN intelligent controller (RIC) from the O-RAN Alliance. The NexRAN xApp realizes policy driven closed-loop control of RAN slices by reading the current state of RAN elements (using the standard O-RAN key performance measurements (KPM) service model) and controlling slice behavior via the custom slicing service model. We demonstrate and evaluate NexRAN in the POWDER platform and have open sourced all aspects of our realization to enable research into this domain.