An overview of 3G-UMTS Network

The network architecture describes all the network elements and the existing physical link between the network elements. The architecture defines the functionality of each network elements and their interaction with other network elements.

The UMTS (Universal mobile telecommunication system) is a 3G (Third generation) wireless system. The UMTS uses a wideband CDMA technology for transmission, and a more efficient modulation than the GSM (2nd Generation). This allows UMTS to reach higher utilization, and offer higher bandwidth to end user. UMTS offers bit rates up to 2Mbps for users.

UMTS consists of three domains:
1. Core network (CN)
2. UMTS terrestrial Radio access network (UTRAN)
3. User Equipment (UE)



A 3G network includes two main sections: a packet switched core network (PS-CN), which is based on IP, and one or more Radio access network (RAN). Each RAN is divided into subsystems, each consisting of one controller, called Base station controller (BSC) in GPRS and Radio network controller (RNC) in UMTS, connected to several Base Transceiver station (BTSs).

The interfaces involved in 3G network are: Iu, Iub, and Iur. The Iu interface is an interface between RNC and Core network elements. The Iub interfaces exist between the Node B and RNC. The Iur interfaces exist between the two RNCs. Additionally Uu represents Air interface between user equipment (UE) and Node B.
WCDMA is used in UTRAN air interface. WCDMA has two mode of operation: Frequency division duplex (FDD) and Time division duplex (TDD).

The functionalities of Node B:
1.Air interface transmission/reception
2.Modulation/Demodulation
3.CDMA physical channel coding
4.Micro diversity
5.Error Handling
6.Closed loop power control

The functionalities of RNC are:
1.Radio Resource control
2.Admission control
3.Channel allocation
4.Power control settings
5.Handover control
6.Macro diversity
7.Ciphering
8.Broadcast signaling
9.Open loop power control

User equipment (UE) has the same identity pattern as GSM.
1.International mobile subscriber identity (IMSI)
2.Temporary mobile subscriber identity ( TMSI)
3.Mobile station ISDN (MSISDN)
4.International mobile station equipment identity (IMEI)
5.Other patterns.