EN/LZT 123 5762 R2B 1 (3) Ericsson Radio Systems AB2001-03-28

WCDMA Radio Access Network (RAN)

WCDMA RAN is the radio access part of WCDMA/UMTS, the thirdgeneration communication technology. Ericssons comprehensive WCDMARAN offering is 3GPP compliant and supports multi-vendor environment. Afundamental principle is the flexible and integrated management system,which is based on the interaction of the O&M and network planning toolsRANOS and TRAM.

ARCHITECTURE

Ericssons WCDMA Radio Access Network consists of two types of nodes; the RadioNetwork Controller (RNC) and the Radio Base Station (RBS), and software products foroperation & maintenance, RANOS (Radio Access Network Operation Support), and thetoolbox, TRAM (Tools for Radio Access Management) for network planning andoptimization. (Figure 1).

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Figure 1: Radio network overview, logical interfaces.

Elements

Radio Network Controller

The main tasks of the Radio Network Controller (RNC) are to manage Radio AccessBearers for user data transport, manage and optimize radio network resources and controlmobility.

EN/LZT 123 5762 R2B 2 (3) Ericsson Radio Systems AB2001-03-28

Radio Base Station

The Radio Base Station (RBS) provides the actual radio resources and maintains theradio links. The RNC and RBS, as well as several other products in the Ericsson cellularportfolio are based on Cello, a new telecom platform that is suitable for ATM, STM andIP network solutions. Cello supports both IPv4 and IPv61.

ATM switching and IP routing functionality are available in all nodes and provides agreat flexibility when defining the network topology. The platform modularity makes iteasy to create nodes and products with different configurations, functionality, capacity,reliability and performance levels.

RANOS (Radio Access Network Operation Support)

RANOS is a set of software that is specifically designed to support the day-to-dayoperation and maintenance tasks of the WCDMA radio access network.

TRAM (Tools for Radio Access Management)

TRAM is a pc-based toolbox concept that supports planning, test & performancemonitoring of the radio & transport network and it covers all network aspects whenimplementing and monitoring the performance of a WCDMA radio access network.

TRAM-RANOS Interaction

The TRAM-RANOS interaction is based on a dedicated interface for interconnectionbetween the network design and the O&M system. The introduction of UMTStechnology involves new system parameters to be controlled during deployment,operation and optimization. The TRAM-RANOS interaction does not only increase thespeed in the planning, operation and optimization of the UMTS network, but also itminimizes the risk of human errors in these important activities.

RANOS and TRAM are further described in the article RANOS / TRAM.

WCDMA RAN Functionality

The WCDMA RAN functionality can be divided into four areas:

Radio Access Bearer Functionality Radio Network Control Functionality Transport Network Control Functionality Operation and Maintenance

1 IPv4 is the current version of IP and IPv6 is the next generation IP.

EN/LZT 123 5762 R2B 3 (3) Ericsson Radio Systems AB2001-03-28

Radio Access Bearer (RAB) Functionality

The Radio Access Bearer functionality provides the core network with a set of servicesbetween the core network and the user equipment. The RAB are suitable for circuit-switched and packet-switched data services, such as voice and file transferring. The RABalso provides simultaneous handling of circuit-switched and packet-switched data.

The RAB functionality is the basic service that WCDMA RAN provides to the corenetwork for user data transport over Iu, Iub and Uu interfaces2 (see figure 1).

Radio Network Control Functionality

The Radio Network Control functionality takes care of mobility, connection control, andcapacity control.

The mobility functions involve handover, cell reselection, macro diversity combiningand location update management.3.

Connection control functions are paging, managing signaling channels, RABservices, allocation and control of radio and other resources needed for the RABs.

The capacity control or radio resource handling provides functionality for capacitymanagement, power control and access & congestion (overloading) control. Thesefunctions are important in WCDMA, as there is a trade off between coverage,capacity and quality. Ericsson WCDMA RAN solutions make it easy to tunecoverage, capacity and quality against each other. Parameter values calculated byTRAM are used for this control.

Transport Network Control Functionality

The functionality handles the ATM communication between the WCDMA RAN nodes,the WCDMA radio access network and the core network. It provides ATM functionalitysuch as cell transport, switching, cross connection and link termination of ATM protocolsover Iu, Iur and Iub.

Operation and Maintenance (O&M) Functionality

O&M functionality provides Radio and Transport Network configuration. It collects andstores events and statistics, detects and sends alarms to a central fault managementapplication. It also prevents unauthorized use of the system.

O&M are handled through embedded management in RNC and RBS, and also byRANOS and TRAM.

2 Denotion for Interfaces in 3GPP standards.3 The Mobile Terminal determines with which BS it will communicate and initiates handover.