UMTS TDD Technology Overview UMTS TDD Mobile Broadband technology is a packet data implementation of the international 3GPP Universal Mobile Telecommunication System (UMTS) standard. Unlike W-CDMA which uses FDD (Frequency Division), UMTS TDD uses Time-Division-Duplexing (TDD) and is designed to work in a single unpaired frequency band. One of the largest benefits of using TDD is that TDD supports variable asymmetry, meaning an operator can dictate how much capacity is allocated to downlink versus uplink. As the traffic patterns for data typically heavily favor the downlink, this results in better use of spectrum assets and higher efficiency. Over 120 of the Europe’s and Asia’s largest mobile operators have spectrum that is specifically allocated to IMT-2000 TDD technologies. These bands include both the 1900 – 1920 MHz and the 2010 – 2025 MHz bands. To increase flexibility for service providers, particularly in coutries that do not follow the ITU recommendations, UMTS TDD has also been rebanded to allow operation in other licensed spectrum bands, even up to 3.6GHz. The Non Line-Of-Sight characteristic of UMTS TDD allows access indoors, outdoors, and at other times when a direct view of the tower is not available. The standard supports tower-to-tower handoff and continuous connections for customers moving up to speeds of 120 km/h and over. Cell radius can be as small as a microcell or as large as 29km.		Advantages of UMTS TDD Performance: UMTS TDD Solutions have been shown to support peak downlink sector capacities of up to 12Mbps and average capacities per sector that are more than 3 times higher than any other commercial mobile platform. Economics: The cost advantages of a TDD solution are clear, and only stand to improve as this globally accepted standard achieves higher economies of scale in production. Many operators are profitably offering flat rate broadband services that match DSL in speed and price. Spectral Efficiency: The TDD standard’s true N=1 frequency reuse means that a network operator can deploy a network with multiple towers using only one 5 MHz RF channel for a 3.84 Mcps (MegaChip per second) system or one 10 MHz channel for a 7.68 Mcps system. Customer Experience: Generally, with UMTS TDD, the customer installation and user experience is exceptionally simple. Statistics show that most customers can self provision and install themselves on the network with few customer service calls – up to 4 times less than is typical for new DSL subscribers. Mobility: UMTS TDD subscribers can stay connected while traveling in excess of 120 km/hr, so long as they remain within the network footprint. Tower-to-tower handoff, and network-to-network roaming are supported. Commercially Proven: Many competing technologies are still in the lab, but UMTS TDD is in the real world, earning real revenue from enterprise and consumer subscribers. Standards Compliant: As a 3GPP standard, UMTS TDD offers the network operator unparalleled economies of scale, equipment and support from multiple vendors, long-term viability, and innovation from the world's leading R&D teams. UMTS TDD is one of 3 alternative air-interface (physical layer) standards of UMTS, which all share higher layer protocol stack and core network / back office architecture. The other alternatives are FDD W-CDMA and TD-SCDMA. TDD is the branch of the 3GPP standard specifically intended for high data rate services The burst structures defined in the standard are designed to support advanced signal processing, and the standard permits interoperability between UE and network infrastructure from multiple vendors, providing the competitive market that will drive down costs and increase innovation, particularly on UE. Frequency Flexibility: UMTS TDD solutions can operate in either a single 5MHz channel, or a 10MHz channel. The UMTS TDD standard is inherently designed to support N=1 reuse (a single frequency network) in response to network operators in the IMT 2000 3G band, which are only allocated a single TDD channel. UMTS TDD achieves N=1 by using direct-sequence spread-spectrum, which provides the processing gain required for negative C/I operation.

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