UMTS Terrestrial Radio Access Network

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UTRAN acronym for: UMTS Terrestrial Radio Access N etwork

Introduction

An approximate translation into Spanish of this acronym would be UMTS Terrestrial Radio Access Network (Universal Mobile Telecommunications System). UMTS presents an architecture in which three main elements are described, the UE or user equipment, UTRAN (UMTS Terrestrial Radio Access Network) and the central network (Core Network). UTRAN enables user equipment to access the core network of UMTS, one of the leading third-generation (3G) wireless mobile communications networks. The UTRAN system has been developed to achieve high transmission speeds. New types of data transfer and algorithms help achieve this speed.

In UTRAN, access to the UMTS network core is carried out via radio, through a series of network elements interconnected with each other and with the network core through terrestrial transport interfaces. The Uu interface is located between the UE and the UTRAN network, and between the UTRAN network and the Core Network is the lu interface. The interface between the UE and the UTRAN network is WCDMA technology, that is, the connection between the user equipment and the radio access network for UMTS is through WCDMA technology. In addition to radio access through UTRAN, UMTS also allows the use of a satellite radio access network.

The UTRAN network consists of several elements, among which are the RNC (Radio Network Controller) that are responsible for controlling the radio access network and the Node B correspond to the base stations where the antennas and communication elements are located. radio transmission. Both elements together form the RNS (Radio Network Subsystem), a set of radio subsystems, the communication mode of the UMTS network. The internal interfaces of UTRAN include the lub interface which is between Node B and the RNC and the lur interface which connects the RNCs to each other.

Architecture

UTRAN technology is made up of various layers that are completely independent of each other. This would facilitate a possible modification of a part of this technology in the future without having to create another part again, it would only be enough to modify some of its layers.

Description of the elements:

-User Equipment (EU): The user equipment or UE, also called mobile, is the equipment that the user brings with them to achieve communication with a base station at the time they want and the place where coverage exists. This may vary in size and shape, however it must be prepared to support the standard and protocols for which it was designed.

-Uu interface: The Uu interface is located between the user equipment and the UTRAN network.

-RNC (Radio Network Controller):

The RNC controls one or more Node Bs. The RNC connects to the MSC via the luCS interface or to an SGSN via the luPs interface. The interface between two RNCs is the lur interface, therefore a direct connection between them is not necessary. exist. If we compare the RNC with the GSM (Groupe Spécial Mobile) network, it is comparable with the BSC (Base Station Controller).

Some of the functions performed by RNC are:

-Manage the transport resources of the interface lu.

- Managing system information and system information schedules.

- Traffic management on the common channels.

-Combination on the Macro diversity and division of data plots transferred on many B Nodes.

- Allocation of channel codes on the down link.

- Admission control.

- Traffic management on shared channels.

-Node B:

Node B creates, maintains, and sends a radio link in cooperation with the terminal. That is, it is the component responsible for radio transmission and reception between the mobile terminal and one or more UMTS cells.

Some of the functions performed by Node B are:

-Transmission of system information messages according to the schedule determined by the RNC.

-Report the interference measurements on the uplink and the power information on the down link.

-Combination for Macro diversity and division of internal data plots to Node B.

-Interface lu:

This interface connects the core network to the UMTS radio access network. It is the central and most important interface for the 3GPP concept. The lu interface can have two different physical instances to connect to two different elements of the core network, all depending on whether it is a circuit-switched or packet-switched network. In the first case, it is the lu-CS interface that serves as a link between UTRAN and the MSC, and it is the lu-PS interface that is responsible for connecting to the network. radio access with the SGSN of the core network.

-Central Network (Core Network):

The core network is made up of several elements, the two of greatest interest are the MSC, the central piece in a network based on circuit switching, and the SGSN, the central piece in a network based on packet switching.

-MSC (Mobile Switching Center):

As already mentioned, the MSC is the centerpiece of a circuit-switched network. The same MSC is used by both the GSM and UMTS systems, that is, the BSS (Base Station subsystem) of GSM and the RNS of UTRAN can connect with the same MSC. This is possible since one of the objectives of 3GPP was to connect the UTRAN network with the GSM/GPRS core network. The MSC has different interfaces to connect with the PSTN network, with the SGSN and with other MSCs.

The last stage of MM (Mobility Management) and CM is carried out at the MSC (Connection Management) in the air interface protocol, so the MSC must take charge of the direction of these protocols or delegate responsibility to anyone another element of the core network. It is also in charge of paging, coordinating the organization of calls from all mobiles in the jurisdiction of an MSC, collecting data for the billing and control center and operation of echo cancellation, among others.

-SGSN (Serving GPRS Support Node):

The SGSN is the central piece in a network based on packet switching. The SGSN connects with UTRAN through the lu-PS interface and with the GSM-BSS through the Gb interface. The SGSN contains the subscription information, the IMSI (International Mobile Subscriber Identity), the location and the area in which the mobile is registered among other information.

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