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3G is third-generation technology in the context of mobile phone standards. The services associated with 3G include wide-area wireless voice telephony and broadband wireless data, all in a mobile environment. In marketing 3G services, video telephone has often been suggested as the killer application for 3G.

According to the GSA, in December 2005 there were 100 3G networks in operation in 40 countries around the world. In Asia, Europe, and the USA and Canada, telecommunication companies use W-CDMA technology with the support of around 100 terminal designs to operate 3G mobile networks.

Roll-out of 3G networks was delayed in some countries by the enormous costs of additional spectrum licensing fees. In many parts of the world 3G networks do not use the same radio frequencies as 2G, requiring mobile operators to build entirely new networks and license entirely new frequencies; a notable exception is the United States where carriers operate 3G service in the same frequencies as other services. The license fees in some European countries were particularly high, bolstered by government auctions of a limited number of licences and sealed bid auctions, and initial excitement over 3G's potential. Other delays were as a result of the expenses related to upgrading equipment for the new systems.

The first country that introduced 3G on a large commercial scale was Japan. In 2005, about 40% of subscribers used 3G networks only, with 2G being on the way out. It was expected that the transition from 2G to 3G would be largely completed during 2006, and upgrades to the next 3.5G stage with 3 Mbit/s data rates were under way.

The successful 3G introduction in Japan showed that video telephony was not the killer application for 3G networks after all. The real-life usage of video telephony on 3G networks was found to be a small fraction of all services. On the other hand, downloading of music found strong acceptance by customers. Music download services in Japan were pioneered by KDDI with the EZchakuuta and Chaku Uta Full services.

3G networks are not IEEE 802.11 networks. IEEE 802.11 networks are short range, higher-bandwidth (primarily) data networks, while 3G networks are wide area cellular telephone networks which evolved to incorporate high-speed internet access and video telephony.

Background
On October 1, 2001, NTT DoCoMo—one of the giant telecommunication companies in Japan—was the first telecommunication company to launch a commercial W-CDMA network. The introduction of 3G services within Europe began in early 2003.

The official 3G mobile network is the systems and services based on the International Telecommunication Union (ITU) family of standards under the International Mobile Telecommunications programme, "IMT-2000". A boost was given to 3G mobile networks in Europe when the European Union council suggested that the 3G operators should cover 80% of the European national populations by the end of 2005. The first service of 3G in north Africa started in Morocco late of March provided by the new company, Wana. The other operator should start their network in the middle of 2007. Vodafone Egypt (also known as CLICK GSM) will provide the service in Egypt in the middle of 2006. Early 2007, Vodacom Tanzania switched on its 3G HSDPA in Dar Es Salaam. With the installation of a 3G HSDPA network, Tanzania is only the second country in Africa with such technology, the first being South Africa. In March 2007, Nigeria awarded 3G telecommunication licenses to the nation's three major GSM companies and a relatively unknown operator, Alheri Engineering Co. Ltd, to enable them to expand their scope of operation in the industry. Rogers Wireless began implementing 3G HSDPA services in eastern Canada early 2007 in the form of Rogers Vision, with further expansion into western Canada expected in the near future.

Features
The most significant feature offered by third generation (3G) mobile technologies is the capacity to support greater numbers of voice and data customers — especially in urban centres — as well as higher data rates at lower incremental cost than 2G.

By using the radio spectrum in bands identified, which is provided by the UTI for Third Generation IMT-2000 mobile services, it subsequently licensed to operators. 3G uses .5 MHz channel carrier width to deliver significantly higher data rates and increased capacity compared with 2G networks.

The .5 MHz channel carrier provides optimum use of radio resources for operators who have been granted large, contiguous blocks of spectrum. On the other hand, it also helps to reduce the cost to 3G networks while being capable of providing extremely high-speed data transmission to users.

It also allows the transmission of 384 kbit/s for mobile systems and 2 Mb/s for stationary systems. 3G users are expected to have greater capacity and improved spectrum efficiency, which will allow them to access global roaming between different 3G.

Standards in 3G Mobile Technology
International Telecommunications Unit (ITU): IMT-2000 consists of five radio interfaces

W-CDMA
CDMA2000
TD-CDMA / TD-SCDMA
UWC (often implemented with EDGE)
DECT

Evolution to 3G
The Evolution to 3G describes the updating of cellular mobile telecommunications networks around the world to use new 3G technologies. This process is taking place over the period 1999 to 2010. Japan is the first country having introduced 3G nationally, and in Japan the transition to 3G has been largely completed during 2005/2006. 3G technologies enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.

Operators and UMTS networks
As of 2005, the evolution of the 3G networks was on its way for a couple of years. The main reason for these changes are basically the limited capacity of the existing 2G networks. The second generation of networks were built mainly for telephone calls and slow data transmission. Due to the rapid changes in technology, these factors do not meet the requirements of today's wireless revolution. The developments of so-called "2.5G" (or even 2.75G) technologies such as i-mode data services, camera phones, HSCSD and GPRS have been ways of bridging the oncoming change to 3G networks, but are not permanent solutions. They are merely stepping stones towards the new technology. These stepping stones were built to introduce the possibilities with the future wireless application technology to the end consumers. These procedures are necessary to ensure that the operators and the infrastructure itself have a healthy ground to operate on.

The evolution of networks from the second generation of technologies to the third generation technologies could not be done without the help of network operators. In 2005 there were about 23 networks worldwide that operated on 3G technologies, the most advanced being KDDI in Japan. Some of these networks were only for test use but some were already in consumer based use.

2G to 3G Network Standardization
The International Telecommunication Union (ITU) has defined the demands for third generation mobile networks with the IMT-2000 standard. An organization called 3GPP has continued that work by defining a mobile system that fulfills the IMT-2000 standard. This system is called Universal Mobile Telecommunications System (UMTS). The evolution of the system will move forward with so called releases. In each release new features will be introduced. The following features are just examples of many others in these new releases.

Release '99
Bearer services
64 kbit/s circuit switched
384 kbit/s packet switched
Location services
Call services: GSM-compatible, USIM-based

Release 4
Edge radio
Multimedia messaging
MeXe levels
Improved location services
IP Multimedia Services (IMS)

Release 5
IP Multimedia Subsystem (IMS)
IPv6, IP transport in UTRAN
Improvements in GERAN, Mexe, etc
HSDPA

Release 6
WLAN integration
Multimedia broadcast and multicast
Improvements in IMS
HSUPA
There are several different paths from 2G to 3G. In Europe the main path starts from GSM when GPRS is added to a system. From this point it is possible to go to the UMTS system. In North America the system evolution will start from TDMA going to EDGE and from there to UMTS.

In Japan, there are two 3G standards used: W-CDMA (which is compatible with UMTS) by NTT DoCoMo and Softbank, the other one is CDMA2000 which is used by KDDI. Transition to 3G is being largely completed in Japan during 2005/2006.

Layered Network Architecture Advantages
The UMTS system is based on layered services, unlike GSM. On the top there is the services layer, which will give advantages like fast deployment of services and centralized location. In the middle there is the control layer, which will help upgrading procedures and allow the capacity of the network to be dynamically allocated. On the bottom is the connectivity layer where any transmission technology can be used and the voice traffic will transfer over ATM/AAL2 or IP/RTP.

Mobile Technologies
The first new technology when going from GSM towards UMTS is General Packet Radio Service (GPRS). It is the trigger to 3G services. The main point is that the network connection is always on, so the subscriber is online all the time. From the operator's point of view, it is important that GPRS investments are re-used when going to UMTS. Also capitalizing on GPRS business experience is very important.

From GPRS, operators could go directly to UMTS, but they could also invest in an EDGE system. One advantage of EDGE is that there is no new licence needed as in UMTS. The frequencies will also be re-used and no new antennas are needed. The main issue is that subscribers will have to buy new EDGE terminals.

From GPRS to UMTS
HLR (Home location register)
VLR (Visitor location register)
EIR (Equipment identity register)
From GPRS network, the following network elements will be reused:

MSC (Mobile switching centre) (vendor dependent)
AUC (Authentication centre)
SGSN (Serving GPRS Support Node) (vendor dependent)
GGSN (Gateway GPRS Support Node)
From Global Service for Mobile communication radio network, the following network elements can NOT be reused. Note, however they can remain in the network and be used in dual network operation where 2G and 3G networks co-exist while network migration and new 3G terminals become available for use in the network.

BSC (base station controller)
BTS (base transceiver station)
The UMTS network introduces new network elements that give functionality as given in the 3GPP specifications:

Node-B (base station)
RNC (Radio Network Controller)
MGW (Media Gateway)
The functionality of MSC and SGSN changes when going to UMTS. In a GSM system the MSC handles all the circuit switched operations like connecting A- and B-subscriber through the network. SGSN handles all the packet switched operations and transfers all the data in the network. In UMTS the MGW (Media gateway) will take care of all data transfer in both, circuit and packet switched networks. MSC and SGSN will act as "brains" of the system and they will control MGW operations. The name of the nodes will change into MSC-server and GSN-server.

Future Network
When UMTS networks are in commercial use and users utilize the services, the capacity given by UMTS will need to be tested to ensure its sufficiency. Increasing WLAN capacity could be one potential cost-efficient solution, another being integration with UMTS. When so called "hot services" are found in UMTS, areas of demand for the network should be analysed for post-UMTS development, as it is hard to estimate which areas will experience the most demand.

UMTS, 3G Terminals
3G handsets usually include cameras, music players, video players, contactless smartcards for payment functions (wallet phones), web browsers, email clients and more. This shows that UMTS system is based on layered services and future applications can be supported without too much impact to the underlying radio access network.

UMTS Terminals - The future
The future of UMTS terminals sees a change coming. So far the UMTS technology in Europe has primarily been used in very similar terminals as the GSM technology. The UMTS terminals have been very closely linked with GSM phones in Europe. This factor is now slowly starting to change - and has not been the case in Japan and South Korea, where 3G introduction is several years ahead of Europe.

Issues
Even though 3G has successfully been introduced to European , Asian and North African mobile users, there are some issues that are debated by 3G providers and users:

High input fees for the 3G service licenses
Great differences in the licensing terms
Current high debt of many telecommunication companies, making it more of a challenge to build the necessary infrastructure for 3G
Member State support to the financially troubled operators
Expense of 3G phones
Lack of 2G mobile user buy-in for 3G wireless service
Lack of coverage because it is still new service
High prices of 3G mobile services in some countries, including Internet access .