System Overview

Purpose

This repository defines the control, orchestration, and operations architecture for a 5G SA Open RAN stack that covers CU-CP, CU-UP, and DU-high while preserving a strict native boundary for timing-sensitive southbound work.

MVP Goal

The first meaningful target is:

• one DU
• one cell group
• one UE
• attach plus ping
• controlled backend failover between pre-provisioned targets

System Shape

_{Figure source: ../assets/infographics/architecture/00-system-overview.infographic}

Major Boundaries

• BEAM core: topology, state machines, failure handling, orchestration, config, observability.
• Native gateway: slot-paced and backend-specific RT-adjacent transport.
• Backend adapters: local_du_low, aerial_backend, and stub_fapi_profile.
• Ops plane: ranctl, skills, and Symphony/Codex workflows.

Architecture Choices

• Use Mix umbrella so multiple OTP applications share one repository and one release discipline.
• Standardize southbound traffic on a canonical IR to prevent backend-specific leakage into DU-high logic.
• Keep scheduler logic behind a host boundary so CPU and future cuMAC schedulers are swappable.
• Use precheck -> plan -> apply -> verify -> rollback for all mutating operations.

Assumptions

• RU-side low-PHY remains external to BEAM-managed code.
• FAPI-like semantics are sufficient for DU-high to native gateway exchange.
• Backend switching is limited to pre-provisioned targets, not ad hoc shell-level failover.

Deferred Decisions

• exact ASN.1 and NGAP/F1AP/E1AP codec strategy
• exact transport libraries for SCTP and GTP-U
• real DU-low and Aerial runtime implementations