UMTS

The Universal Mobile Telecommunications System (UMTS) is one of the third generation (3G) mobile telecommunications systems. In the International Telecommunications Union (ITU) this 'family of third generation systems is referred to as 'International Mobile Telecommunications (IMT-2000).

In addition to traditional speech and datacommunication services, UMTS offers the user full interactive multimedia communications, information and entertainment services with speeds of up to 2 Mbit/s, comparable with the current fixed networks. Further evolutions of UMTS will make even higher transmission speeds possible.

In UMTS there are four different kinds of services defined. Each with it's own quality of service:

• Conversational,
  • Temporal relation preserved,
  • Weak and rigorous delays,
  • Services: Telephony, videotelephony, real time video games;
• Streaming,
  • Temporal relation preserved,
  • Services: Multimedia services;
• Interactive,
  • Demand of response,
  • Data integrity preserved,
  • Services: Internet (web browsing);
• Background,
  • No restraints on delays,
  • Data integrity preserved,
  • Services: E-mail.

UMTS is an European initiative to build further on the success of GSM. 3GPP is responsible for the standardisation of both UMTS and GSM.

Frequency bands
The following bands are available for UMTS, in Europe.

The available spectrum of 155 MHz is divided in:

• a paired band,
  FDD: 1920-1980 and 2110-2170 MHz; 2 × 60 MHz;
• two unpaired bands,
  TDD: 1900-1920 MHz and 2010-2025 MHz; in total 35 MHz.

The UMTS Terrestrial Radio Access (UTRA) makes use of W-CDMA in the paired bands. These bands are used for a wide area mobile network with bit rates of 144 kbit/s in suburban and rural areas for high mobile users (up to 500 km/h) up to 384 - 512 kbit/s in urband areas with medium mobility (up to 120 km/h).
The air interface of the unpaired bands is UTRA TDD of which two versions excist, TD-CDMA and TD-SCDMA. These bands are used for high bit rates at hotspots (up to 2 Mbit/s) with low mobility (less then 10 km/h). All bit rates are based on the first generation of UMTS. Further evolutions of UMTS will make even higher transmission speeds possible

In the first release of UMTS (Release 99), the UMTS Terrestrial Radio Access Network (UTRAN) is based on an evolved GSM network with GPRS capabilities. As off Release 5 the UTRAN is IP based.