3G

3G is the third generation of mobile phone standards and technology, superseding 2G. It is based on the International Telecommunication Union (ITU) family of standards under the International Mobile Telecommunications programme, "IMT-2000".

Standards

Main article: IMT-2000

International Telecommunications Union (ITU): IMT-2000 consists of six radio interfaces

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

3G technologies enable network operators to offer users a wider range of more advanced services while achieving greater network capacity through improved spectral efficiency.

Evolution to 3G

Cellular mobile telecommunications networks are being upgraded to use 3G technologies from 1999 to 2010. Japan was the first country to introduce 3G nationally, and in Japan the transition to 3G was largely completed in 2006. Korea then adopted 3G Networks soon after and the transition was made as early as 2004.

Operators and UMTS networks

As of 2005, the evolution of the 3G networks was on its way for a couple of years, due to the limited capacity of the existing 2G networks. 2G networks were built mainly for voice data and slow transmission. Due to rapid changes in user expectation, they do not meet today's wireless needs.

"2.5G" (and even 2.75G) are technologies such as i-mode data services, camera phones, high-speed circuit-switched data (HSCSD) and General packet radio service (GPRS) were created to provide some functionality domains like 3G networks, but without the full transition to 3G network. They were built to introduce the possibilities of wireless application technology to the end consumers, and so increase demand for 3G services.

Network standardization

The International Telecommunication Union (ITU) defined the demands for 3G mobile networks with the IMT-2000 standard. An organization called 3rd Generation Partnership Project (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).

3G evolution (pre-4G)

See also section Pre-4G wireless standards of the 4G article.

The standardization of 3G evolution is working in both 3GPP and 3GPP2. The corresponding specifications of 3GPP and 3GPP2 evolutions are named as LTE and UMB, respectively. 3G evolution uses partly beyond 3G technologies to enhance the performance and to make a smooth migration path.

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 Time division multiple access (TDMA), change to Enhanced Data Rates for GSM Evolution (EDGE) and then to UMTS.

In Japan, two 3G standards are used: W-CDMA used by NTT DoCoMo (FOMA, compatible with UMTS) and SoftBank Mobile (UMTS), and CDMA2000, used by KDDI. Transition to 3G was completed in Japan in 2006.

Advantages of a layered network architecture

Unlike GSM, UMTS is based on layered services. At the top is the services layer, which provides fast deployment of services and centralized location. In the middle is the control layer, which helps upgrading procedures and allows the capacity of the network to be dynamically allocated. At 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

When converting a GSM network to a UMTS network, the first new technology is General Packet Radio Service (GPRS). It is the trigger to 3G services. 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 change the network directly to UMTS, or invest in an EDGE system. One advantage of EDGE over UMTS is that it requires no new licenses. The frequencies are also re-used and no new antennas are needed.

Migrating from GPRS to UMTS

From GPRS network, the following network elements can be reused:

• Home location register (HLR)
• Visitor location register (VLR)
• Equipment identity register (EIR)
• Mobile switching centre (MSC) (vendor dependent)
• Authentication centre (AUC)
• Serving GPRS Support Node (SGSN) (vendor dependent)
• Gateway GPRS Support Node (GGSN)

From Global Service for Mobile (GSM) communication radio network, the following elements cannot be reused

• Base station controller (BSC)
• Base transceiver station (BTS)

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.

The UMTS network introduces new network elements that function as specified by 3GPP:

• Node B (base station)
• Radio Network Controller (RNC)
• Media Gateway (MGW)

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 Media gateway (MGW) take care of all data transfer in both circuit and packet switched networks. MSC and SGSN control MGW operations. The nodes are renamed to MSC-server and GSN-server.

UMTS terminals

The technical complexities of a 3G phone or handset depends on its need to roam onto legacy 2G networks. In the first countries, Japan and South Korea, there was no need to include roaming capabilities to older networks such as GSM, so 3G phones were small and lightweight. In Europe and America, the manufacturers and network operators wanted multi-mode 3G phones which would operate on 3G and 2G networks (e.g., W-CDMA and GSM), which added to the complexity, size, weight, and cost of the handset. As a result, early European W-CDMA phones were significantly larger and heavier than comparable Japanese W-CDMA phones.

Japan's Vodafone KK experienced a great deal of trouble with these differences when its UK-based parent, Vodafone, insisted the Japanese subsidiary use standard Vodafone handsets. Japanese customers who were accustomed to smaller handsets were suddenly required to switch to European handsets that were much bulkier and considered unfashionable by Japanese consumers. During this conversion, Vodafone KK lost 6 customers for every 4 that migrated to 3G. Soon thereafter, Vodafone sold the subsidiary (now known as SoftBank Mobile).

The general trend to smaller and smaller phones seems to have paused, perhaps even turned, with the capability of large-screen phones to provide more video, gaming and internet use on the 3G networks.

Issues

Although 3G was successfully introduced to users in Europe, Australia, Asia, South America, North America and Africa, some issues are debated by 3G providers and users:

• Expensive input fees for the 3G service licenses
• Numerous differences in the licensing terms
• Large amount of debt currently sustained by many telecommunication companies, which makes it a challenge to build the necessary infrastructure for 3G
• Lack of member state support for financially troubled operators
• Expense of 3G phones
• Lack of buy-in by 2G mobile users for the new 3G wireless services
• Lack of coverage, because it is still a new service
• High prices of 3G mobile services in some countries, including Internet access (see flat rate)
• Current lack of user need for 3G voice and data services in a hand-held device
• High power usage

See also

• 2G
• 2.5G
• 2.75G
• 3.5G
• 3.75G
• 4G
• 3GP 3G multimedia container format (mobile video)
• IP Multimedia Subsystem
• WiBro
• WiMAX
• Wireless modem
• Spectral efficiency comparison table
• DigRF V3