Designing Reliable Virtualized Radio Access Networks
Ufuk Usubütün, André Gomes, Shankaranarayanan Puzhavakath Narayanan, Matti Hiltunen, Shivendra Panwar
TL;DR
This work introduces a CTMC-based analytical framework to quantify vRAN availability under hardware/software disaggregation and containerized platforms. By modeling CU/DU applications, platform replicas, and cluster deployments, it reveals that OS/CaaS reliability and failover speed are primary determinants of network-wide resilience, with hardware replication providing diminishing returns in slow-failover regimes. The findings show centralized CUs can achieve high availability only if CU reliability is enhanced to avoid a single-point-of-failure risk. The framework informs replication, placement, and failover design choices for Open RAN deployments and supports resilience-oriented provisioning decisions.
Abstract
As virtualization of Radio Access Networks (RAN) gains momentum, understanding the impact of hardware and software disaggregation on resiliency becomes critical to meet the high availability requirements of mobile networks. Our paper presents an analytical model, using continuous time Markov chains, to study the impact of virtualization and disaggregation on RAN availability. Our evaluation, assuming typical parameter value ranges for failure and recovery rates, points to containerized platform reliability as a constraint on vRAN availability. We also find that with active-passive replication, increasing hardware replication factor beyond 2 may not bring any benefits unless failover times are reduced. We also compare the reliability of centralized and distributed virtualized central units.