Universal Mobile Telecommunications System (UMTS)

In 1988, the European Community (CEC) began a "European Advanced Communications Research (RACE)" development plan by the European 26 research units jointly develop a new generation of mobile communication systems. Called "Universal Mobile Telecommunications System", referred to UMTS, the European Telecommunications Standards Institute (ETSI) is responsible for UMTS standardization work, and with the ITU is responsible for third-generation mobile communication system IMT-2000 standardization work coordinated.

Universal Mobile Telecommunications Systems is also known as 3G, a Third Generation Broadband which based on GSM standard. UMTS is use Wide-band Code Division Multiple Access to provide a efficient and bandwidth to mobile network operators.

UM TS as a complete 3G mobile communication technology standards, UMTS air interface is not limited to the definition. In addition to WCDMA air interface technology as the preferred access to constantly improve the outside, UMTS also have introduced a TD-SCDMA and HSDPA technology.

Today's cellular telephone systems are mainly circuit-switched , with connections always dependent on circuit availability. packet-switched connection, using the Internet Protocol ( IP ), means that a virtual connection is always available to any other end point in the network. It will also make it possible to provide new services, such as alternative billing methods (pay-per-bit, pay-per-session, flat rate, asymmetric bandwidth, and others). The higher bandwidth of UMTS also promises new services, such as video conferencing. UMTS promises to realize the Virtual Home Environment ( VHE ) in which a roaming user can have the same services to which the user is accustomed when at home or in the office, through a combination of transparent terrestrial and satellite connections.

Trials of UMTS technology, using advanced mobile phone/computing device prototypes, are currently being conducted by Nortel Networks and BT (British Telecommunications).

The electromagnetic radiation spectrum for UMTS has been identified as frequency bands 1885-2025 MHz for future IMT-2000 systems, and 1980-2010 MHz and 2170-2200 MHz for the satellite portion of UMTS systems.

UMTS include a full set of network communication system like

• Radio access network (UMTS Terrestrial Radio Access Network, or UTRAN),
• Core network (Mobile Application Part, or MAP)
• Authentication of users via SIM (subscriber identity module) cards

Features of UMTS:

• UMTS supports transfer rates (not often seen 2Mbps) 1920kbps, but typically only about 384Kbps the highest rate in the real high-load systems. Even so the data rate has been higher than the GSM data channel error correction 14.4kbps or composed of more than 14.4 kbps HSCSD channel can really achieve an acceptable price to move WWW access and MMS. UMTS is a prerequisite to achieve now widely used GSM mobile phone system, belonging to 2G technology. There is also a way of evolution from 2G GPRS is called. (Can be seen as 2.5G) GPRS support better data rate (maximum theoretically possible to 140.8kbps, can actually achieve close to 56Kbps), better than connection-oriented data encapsulation. GPRS has been deployed in many GSM networks. 
• China Unicom's UMTS network upgrade to HSDPA, sometimes also called 3.5G. It can achieve a downlink transmission speeds greater than 10Mbps. 
• UMTS has emphasized the possibility that the market for mobile video conference call to achieve, despite the fact that there are many promising service has not been tested to verify. 
• Other possible applications as well as UMTS music downloads and video telephony.

Put it simply , UMTS combines  W-CDMA, the air interface ( wireless mobile telephone communication protocols and a base station ) , the core part of mobile application of the GSM system (MAP, see en: MAP) ( This protocol provides user to call routing function from the user or to the user) , and GSM voice coding algorithm e.g. adaptive Multi-Rate (AMR) and the Enhanced Full Rate (EFR) ( which defines a digital voice compression coding method ) . In other words , W-CDMA ( defined according to the IMT-2000 ) only one air interface protocol and is a complete 3G UMTS mobile communication world for the stack can be used to replace the GSM. However, in practice it often as all W-CDMA air interface uses the general term for the family of 3G standards , including UMTS, FOMA and J-Phone.

And other variants of the same W-CDMA , UMTS uses a pair of 5 MHz channels , uplink channel in the vicinity of 1900 MHz, downlink channel in the vicinity of 2100 MHz. In contrast , CDMA2000 can use one or more of 1.25 MHz channels in each direction , so UMTS often because of its high bandwidth requirements has been criticized .

Originally provided for the UMTS band uplink 1885-2025 MHz, downlink 2110-2200 MHz. The current spectrum allocation can be found in  .

The existing GSM operators have a simple but relatively expensive upgrade to UMTS solution: most of the existing infrastructure can maintain the status quo , but to obtain spectrum licenses and UMTS on existing towers covering the cost can be prohibitively expensive .