Technical description on UMTS

UMTS- Universal Mobile Telecommunication System sometimes it is called IMT-2000, which is consider to the most sophisticated wireless technology in 3rd generation of communication systems. It is also known as 3G, mainly developed for 3rd generation mobiles which are combined with high speed wireless broadband internet service. 3G broadband technology is now blossoming in UK broadband service. Broadband suppliers like Vodafone are emerging too fast in the sector. This kind of technology has been developing for the growing intensity for mobile internet use around UK.

UMTS or IMT-2000 system has been designed to become a universal communication system. The word universal also means uniform, based on its service level mainly. The main technical features of UMTS are flexible, quite complex system. UMTS uses Wide-band Code Division Multiple Access) technology (W-CDMA). This channel bandwidth is near about 5MHz and every operator uses a pair of line, one for uplink steam and another for download steam and the total bandwidth a use gets is 10MHz. All users are provided the service by a same operator and share same frequency channel and each user gets its uniqueness by a unique 'code' or sequence. Every sequence is multiplied by a factor. As a result the resulting 'chip rate' is much higher than the information rate (the chip rate is set to 3.84 Mchip/s). The sequences assigned to different users are selected such that the connection between them is decreased. Real-time users cause mutual interference, so the more users there are means more interference. The system's capacity is restricted by the level of shared interference. Interference levels can be reduced by using power control from the base station. But this technique is less competent at high terminal speeds. Also its roaming capability (mostly used in GSM, CDMA phones) lets for soft hand-over which is made possible by the microdiversity mechanism. When users are moving across different location, it allows them to connect with several base stations.

The bit-rate of UMTS can varies from 144 kbit/s up to 2 Mbit/s. The speed depends on the service requirements and the mobility characteristics. Comparing with GSM, UMTS is capable of carrying voice communications as well as multimedia services like MMS. ATM Adaptation Layers (AALs) and IP transport protocols to carry data in packet mode is used by UMTS. UMTS uses switched-circuit technology for Voice services like GSM service and multimedia services use IP packet-switched technology. As UMTS is chiefly a point-to-point, it is able to provide common users data services in a broadcast transmission mode. The system could be in transparent or unacknowledged mode without the assurance of delivery of the packet. It should be remain in mind that the broadcast mode may not be commercially possible for the operator and even prove too much costly for the users. UMTS does need spectrum for wireless communication system. For the terrestrial component in Europe, UMTS will use 155 MHz. UTMS will use 1920 to 1980 MHz for the uplink steam and 2110 to 2170 MHz for the downlink steam.

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