Subject : Mobile Communication

Topic : 3G Communication System

Difficulty : Medium

Fig 1 shows UMTS Network architecture.as showed in fig UMTS uses some elements of the GSM architecture.

The Mobile Station (MS) is user equipment (UE). Function of MSC is same as that in GSM.
SGSN & GGSN are the gateways used to connect with other network (PSTN,PLMN,INTERNET) with speed upto 2 MBPS.
The core n/w elements are connected to radio n/w through Iu interface.
The Radio Access n/w (RAN) called as Terrestrial Radio Access N/W (UTRAN) Iur interface connects Radio n/w controllers. Base stations are connected to RNC through the Iub interface

Fig-2 The UMTS interface diagram
The UMTS interfaces as shown in Fig.2 are described as follows :
1. Uu : It is the interface between the network and the user equipment. It is similar to the Um interface in GSM network.
2 Iu _ CS : It is similar to the A interface in GSM networks .It represents a circuit switched connection for carrying signaling and voce traffic between the core voice network and UTRAN. RANAP is the signaling protocol used.
3 Iu _ PS :It is similar to the Gb interface in GSM networks. It represents a packet switched connection for carrying signaling and voice traffic between the core voice network and UTRAN. RANAP is the signaling protocol used.
4.Iub _ This interface is used for controlling many Node B. NBAP is the signaling protocol used.It is similar to the Abis interface in GSM networks.
5.Iur _This interface is used for supporting mobility of MSCs. When subscriber moves. Iur transfers subscriber data to new RNC as he moves. RNSAP is the signaling protocol used.