computer science

Radio Network Controller

Radio Network Controller is a computer 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 Radio Network Controller rather than just read about it. In short: The Radio Network Controller (RNC) is a governing element in the UMTS radio access network (UTRAN) and is responsible for controlling the Node Bs that are connected to it. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile.

Key takeaways

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

Reference excerpt

The Radio Network Controller (RNC) is a governing element in the UMTS radio access network (UTRAN) and is responsible for controlling the Node Bs that are connected to it. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile. The RNC connects to the Circuit Switched Core Network through Media Gateway (MGW) and to the SGSN (Serving GPRS Support Node) in the Packet Switched Core Network.

Interfaces

The logical connections between the network elements are known as interfaces. The interface between the RNC and the Circuit Switched Core Network (CS-CN) is called Iu-CS and between the RNC and the Packet Switched Core Network is called Iu-PS. Other interfaces include Iub (between the RNC and the Node B) and Iur (between RNCs in the same network). Iu interfaces carry user traffic (such as voice or data) as well as control information (see § Protocols), and Iur interface is mainly needed for soft handovers involving 2 RNCs though not required as the absence of Iur will cause these handovers to become hard handovers. Until 3gpp R4, all the interfaces in the UTRAN are implemented using ATM only, except the Uu (air) interface which uses WCDMA technology. Starting R5, IP bearers can be used over Ethernet instead. Physically, these interfaces can be carried over SDH over optical fiber, E1 (sometimes referred to as PDH) - over a copper wire or microwave radio. Several E1s can be bundled to form an IMA Group. Since the interfaces are logical, many interfaces can be multiplexed onto the same transmission line. The actual implementation depends on the network topology; examples are chain, distant star, mesh and loop configurations.

Protocols Iub, Iu and Iur protocols all carry both user data and signalling (that is, control plane).

Signalling protocol responsible for the control of the Node B by the RNC is called NBAP (Node-B Application Part). NBAP is subdivided into Common and Dedicated NBAP (C-NBAP and D-NBAP), where Common NBAP controls overall Node B functionality and Dedicated NBAP controls separate cells or sectors of the Node B. NBAP is carried over Iub. In order for NBAP to handle common and dedicated procedures, it is divided into: NodeB Control Port (NCP) which handles common NBAP procedures and Communication Control Port (CCP) which handles dedicated NBAP procedures. Control plane protocol for the transport layer is called ALCAP (Access Link Control Application Protocol). Basic functionality of ALCAP is multiplexing of different users onto one AAL2 transmission path using channel IDs (CIDs). ALCAP is carried over Iub and Iu-CS interfaces. Signalling protocol responsible for communication between RNC and the core network is called RANAP (Radio Access Network Application Part), and is carried over Iu interface. Signalling protocol responsible for communications between RNCs is called RNSAP (Radio Network Subsystem Application Part) and is carried on the Iur interface.

RNC roles In a relationship to a UE (in a soft handover situation) an RNC can play two different roles. These are:

D-RNC: Drift RNC S-RNC: Serving RNC However, as far as the NodeB is concerned, the RNC may play a third role:

C-RNC: Controlling RNC It is important to know that one RNC can assume more than one role at any time. An RNC also controls the power of a NodeB.

See also Operations and Maintenance Centre Radio Resource Control UMTS

External links NBAP Specifications RANAP Specifications RNSAP Specifications RRC Specifications

References

Worked examples

Example 1 — a first encounter with Radio Network Controller

Start with the simplest possible case. Write down what Radio Network Controller claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer 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 Radio Network Controller 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 Radio Network Controller 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 Radio Network Controller

In research: Radio Network Controller appears in computer 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 Radio Network Controller 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: Radio Network Controller is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3GPP standards, Telecommunications infrastructure, UMTS, so understanding it makes those chapters shorter.
In everyday life: Look for Radio Network Controller 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 Radio Network Controller in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Radio Network Controller 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 Radio Network Controller out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Radio Network Controller in simple terms?

Why does Radio Network Controller matter?

Because it connects several computer 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 Radio Network Controller?

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 Radio Network Controller.