3G, short for third generation, is the third generation of wireless mobile telecommunications technology. It is the upgrade for 2G and 2.5G GPRS networks, for faster web speed. This depends on a set of standards used for mobile devices and mobile telecommunications use services and networks that follow the International Mobile Telecommunications-2000 (IMT-2000) specifications by the International Telecommunication Union. 3G finds application in wireless voice telephony, mobile internet access, fixed wireless Internet access, video calls and mobile TV.
3G telecommunication networks support services that provide an information exchange rate of at least 0.2 Mbit/s. Later 3G releases often denoted 3.5G and 3.75G, also provide mobile broadband access of several Mbit/s to smartphones and mobile modems in laptop computers. This guarantees it can be applied to wireless voice telephony, mobile Internet access, fixed wireless Internet access, video calls and mobile TV technologies.
2.2.1 Universal Mobile Telecommunications System (UMTS)
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks in view of GSM standard. UMTS uses wideband code division multiple access (W-CDMA) radio access technology to offer more prominent spectral efficiency and bandwidth to mobile network operators. UMTS specifies a complete network system, which incorporates the radio access network (UMTS Terrestrial Radio Access Network, or UTRAN), the core network (Mobile Application Part, or MAP) and the authentication of users via SIM (subscriber identity module) cards. UMTS requires new base stations and new frequency allocations.
3GPP UMTS, the Universal Mobile Telecommunications System is the third generation (3G) successor to the second generation GSM based cellular technologies which likewise incorporate GPRS, and EDGE. Although UMTS uses a totally different air interface, the core network elements have been migrating towards the UMTS requirements with the introduction of GPRS and EDGE. In this way the transition from GSM to the 3G UMTS architecture did not require such an expansive immediate venture. UMTS utilizes Wideband CDMA – WCDMA – as the radio transmission standard. It employs a 5 MHz channel bandwidth. Using this bandwidth, it has the capacity to carry over 100 simultaneous voice calls, or it is able to carry data at speeds up to 2 Mbps in its original format.5
2.2.2 UMTS Architecture
The UMTS network architecture can be divided into three fundamental components:
1. User Equipment (UE): The User Equipment or UE is the name given to what was previous named the mobile, or cell phone. The new name was picked on the grounds that the significantly more prominent usefulness that the UE could have. It could also be anything between a mobile phone used for talking to a data terminal attached to a computer with no voice capability.
2. Radio Network Subsystem (RNS): The RNS also known as the UMTS Radio Access Network, UTRAN. It provides and manages the air interface for the overall network.
3. Core Network: The core network provides all the central processing and management for the system.
The core network is then the overall entity that interfaces to external networks including the public phone network and other cellular telecommunications networks.6 . Figure 2.1 shows the overview of the UMTS network architecture.
User Equipment, UE
The USER Equipment or UE is a noteworthy component of the overall UMTS network architecture. It forms the last interface with the user. In perspective of the far greater number of applications and facilities that it can perform, the decision was made to call it a user equipment rather than a mobile. However, it is basically the handset, although having access to much higher speed data communications, it can be much more versatile, containing many more applications. It consists of a variety of different elements including RF circuitry, antenna, battery, processing, etc.
3G UMTS Core Network
The 3G UMTS core network architecture is a migration of that used for GSM with further elements overlaid to enable the additional functionality demanded by UMTS.Figure 2.2 shows the core UMTS network. In view of the different ways in which data may be carried, the UMTS core network are split into two different areas:
• Circuit switched elements: These elements are primarily based on the GSM network entities and carry data in a circuit switched manner, i.e. a permanent channel for the duration of the call.
• Packet switched elements: These network entities are designed to carry packet data. This enables much higher network usage as the capacity can be shared and data is carried as packets which are routed according to their destination.
Some network elements, particularly those that are associated with registration are shared by both domains and operate in the same way that they did with GSM.