science

Open RAN

Open RAN is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Open RAN rather than just read about it. In short: Open RAN, or Open Radio Access Network architecture is based on 3GPP standards for Radio Access Networks (RAN) but contains many extensions, disaggregates RAN components and makes their interfaces open, aiming to improve flexibility and interoperability. RAN hardware and software are cloudified/virtualized, and it includes intelligent management (SMO).

Key takeaways

Open RAN belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Open RAN to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Open RAN from memory before moving on to harder problems.

Reference excerpt

Open RAN, or Open Radio Access Network architecture is based on 3GPP standards for Radio Access Networks (RAN) but contains many extensions, disaggregates RAN components and makes their interfaces open, aiming to improve flexibility and interoperability. RAN hardware and software are cloudified/virtualized, and it includes intelligent management (SMO). Those open interfaces aim for mixing components from different vendors and quicker deployment of new services. Open RAN standardization is led by the O-RAN ALLIANCE. Cloudification means disaggregating hardware and software, making RAN software cloud-native functions running on a general-purpose hardware. Intelligent open management includes automated management and orchestration systems which can utilize Artificial Intelligence and Machine Learning for life cycle management of network functions. Open interfaces: standardized open interfaces, such as the O-RAN ALLIANCE's specifications and 3GPP-defined interfaces, facilitate interoperability between disaggregated RAN components.

Key components In Open RAN, the RAN is split into three main blocks: the Radio Unit (RU), the Distributed Unit (DU), and the Centralised Unit (CU). The RU performs basic RF and low-PHY functions such as precoding and beamforming. The DU performs additional PHY functions such as scrambling and modulation, and handles MAC and RLC functions such as radio resource allocation. The CU handles functions such as SDAP and RRC.

RAN Intelligent Controller (RIC) is an optional virtualized optimization technology for 5G. It adds programmability to a new or existing RAN and allows SON-like (Self-Optimizing Networks) capabilities. The optimization in RIC is boosted by policy-driven closed loop automation and AI/ML. In O-RAN deployments, there are the near real-time RIC (near-RT RIC) which operates on sub-100 millisecond intervals, and the non real-time RIC (non-RT RIC) which operates on intervals longer than 1 second. The near-RT RIC houses xApps, which are programs that optimize functions such as beamforming, traffic steering, and power control. The non-RT RIC houses rApps, which manage longer-term policies such as network slicing. The fronthaul interface lies between radio Units (RU) and baseband units (Distributed Units (DU)). It is a focus area in Open RAN. O-RAN has specified an eCPRI-based 7.2x open interface to be used in the fronthaul, allowing connections between radio units and baseband units of different vendors.

Near-RT RIC The near-RT RIC really houses multiple interworking components.

Internal messaging infrastructure connects the xApps, platform services, and interface (O1, A1, E2) terminations to each other. O-RAN Alliance specifies not what technology the near-RT RIC must use, but there are certain functionalities that this internal messaging infrastructure must provide. The subscription manager allows xApps to listen to functions exposed over the E2 interface. The security sub-system prevents malicious xApps from leaking sensitive RAN data or negatively affecting RAN performance. The RAN Network Information Base (NIB) Database stores information from the E2 interface, typically KPMs from RANs and UEs. The UE-NIB contains information about UEs, specifically their identity key (UE-ID), which allows for xApps to control UEs. These NIBs may be queried through the Shared Data Layer API, usually by xApps. Conflict mitigation prevents RAN performance from being degraded by xApps making conflicting managing decisions on RANs. This is an emerging functionality and is not included in all near-RT RIC implementations. xApps are the meat and potatoes of the near-RT RIC, and the other components exist to support the xApps. xApps are typically realized as Kubernetes or Docker containers. The O-RAN alliance only stipulates that a few KPIs are exposed to the xApps.

O-RAN ALLIANCE O-RAN ALLIANCE (O-RAN) was founded in 2018 by AT&T, China Mobile, Deutsche Telekom, NTT DOCOMO and Orange to promote open mobile networks. O-RAN has over 30 operator members and almost 300 contributors. O-RAN specifications define the parts of the O-RAN Architecture, which can be used to develop Open RAN solutions.

O-RAN ALLIANCE also handles the activities of the earlier xRAN and C-RAN forums.

References

External links O-RAN ALLIANCE

Worked examples

Example 1 — a first encounter with Open RAN

Start with the simplest possible case. Write down what Open RAN claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Open RAN before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Open RAN ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Open RAN

In research: Open RAN appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Open RAN in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Open RAN is common in secondary-school and first-year university syllabi. It links to neighbouring topics Radio technology, so understanding it makes those chapters shorter.
In everyday life: Look for Open RAN outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Open RAN in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Open RAN means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Open RAN out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Open RAN in simple terms?

Why does Open RAN matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Open RAN?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Open RAN.