Evaluating Mesh Communications in Disaggregated Near-RT RIC for 5G Open RAN: a Functional and Performance Analysis

The paradigm shift towards the fifth generation of mobile networks (5G) has entailed a transition from a monolithic architecture to a completely disaggregated microservice-based architecture of network functions. This architectural renovation decouples and distributes Containerized Network Functions (CNF), tailored to address the specialized requirements of the Open Radio Access Network (Open RAN) deployment. Specifically, Kubernetes has emerged as a pivotal orchestrator for CNF within the context of disaggregated Open RAN. In particular, the deployment of Operator-defined Applications (xApps) for Near Real-Time RAN Intelligent Controller (Near-RT RIC) scenarios calls for communication substrates to facilitate the communication and coordination with other RAN components, and consequently, to dial with increased dynamicity and flexibility of 5G deployments. To face these issues, we propose service mesh as a cloud-native technology extending the Kubernetes communication infrastructure. Service mesh fulfills diverse requisites of xApps running in the RAN Intelligent Controller for traffic management, instrumentation, security, and observability, inherently facilitating a zero-trust architecture through the incorporation of sidecar proxies co-located with microservices. Moreover, we evaluate the performances of another emerging paradigm, raising as a lightweight solution that allows a more incremental adoption compared to service mesh, represented by ambient mesh. This paper analyses service and ambient mesh for deploying xApps in a state-of-the-art Near-RT RIC, i.e., the O-RAN SC implementation, evaluating both qualitative and quantitative attributes.