The Length Indicator is used to indicate, each time, the end of an SDU occurs in the PDU. The Length Indicator points out the number of octets between the end of the last Length Indicator field and up to and including the octet at the end of an SDU segment.

This tutorial gives detail description about RLC AM and UM data PDU encoding.

The security architecture in UMTS is divided into four main parts:

1. User identity confidentiality
2. Entity authentication
3. Data integrity
4. Ciphering or confidentiality

In this tutorial User identity confidentiality is covered.

MAC is a layer 2 protocol in the UMTS Access Stratum. MAC has the input as logical channels and at the output it has transport channels.
This tutorial covers only the MAC architecture.

The following sections are covered

• MAC Architecture – UE Side
• MAC Architecture – UTRAN Side

Logical channels define ‘WHAT’ type of information is being transferred and transport channel defines ‘HOW’ the information is being transferred.

In this tutorial different types of logical channels and transport channels and their mappings are described.

Radio Link Control Protocol (RLC) is a layer 2 protocol in the UMTS system. This tutorial is an overview of RLC functionalities and architecture.

• Radio Interface Architecture
• RLC main functionalities
• Data flow between layers
• Model of RLC Sublayer
• RLC Protocol Data Unit
• RLC State Model

Wideband Code Division Multiple Access (WCDMA) is the physical layer used for Universal Terrestrial Radio Access (UTRA) FDD mode. The WCDMA technology provides the UMTS system some of the new functionalities on the air interface.

This tutorial covers the following topics:

• Spreading and Scrambling
• Transport Channel Combining
• Soft Handover
• Compressed Mode
• Power Control

UTRAN Interfaces are the most important point to start learning about the whole system. In this tutorial you can learn the following topics:

• UMTS Interfaces
• Protocols on different interfaces
• Standard numbers and links to the different standards

This tutorial contains some of the basics of 3G technology and network. The following topics are covered:

• What is 3G?
• 3G background.
• UMTS requirements.
• 3gpp specifications.
• UMTS Architecture.