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Mobile phone and data standards

0G PTT MTS IMTS AMTS OLT MTD Autotel/PALM ARP

1G NMT AMPS/TACS/ETACS Hicap CDPD Mobitex DataTac

2G GSM iDEN D-AMPS IS-95/cdmaOne PDC CSD PHS GPRS HSCSD WiDEN CDMA2000 1xRTT/IS-2000 EDGE (EGPRS)

3G W-CDMA UMTS (3GSM) FOMA TD-CDMA/UMTS-TDD 1xEV-DO/IS-856 TD-SCDMA GAN (UMA) HSPA HSDPA HSUPA HSPA+ HSOPA

4G UMB UMTS Revision 8 (LTE) WiMAX

Frequency bands SMR Cellular PCS

TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) is a 3G mobile telecommunications standard, being pursued in the People's Republic of China by the Chinese Academy of Telecommunications Technology (CATT), Datang and Siemens AG, in an attempt to develop home-grown technology and not be "dependent on Western technology" [1]. This is likely primarily for practical reasons, both current 3G formats may require the payment of patent fees to Qualcomm and UMTS requires license fees from the primarily European-based 3G consortium. It is based on spread spectrum CDMA technology which makes it unlikely that TD-SCDMA will be able to completely escape payment of CDMA license fees to Qualcomm. The launch of an operational system was initially projected by 2005 but is now projected by 2007 [2].

Contents 1 Deployment and Usage 2 Technical highlights 3 See also 4 External links

On January 20, 2006, Ministry of Information Industry of the People's Republic of China formally announced that TD-SCDMA is the country's standard of 3G mobile telecommunication. On February 15th, 2006, a timeline for deployment of the network in China was announced, stating pre-commercial trials would take place starting after completion of a number of test networks in select cities. These trials are expected to run from March to June, 2006. TD-SCDMA enabled handsets are also set to start testing around the same time, and are expected to be available in Q2 or Q3 of 2006. TD-SCDMA 3G phones are expected to become available at the end of 2006 and other 3G networks will be delayed until TD-SCDMA is ready.

The standard has been adopted by 3GPP since Rel-4, known as "UTRA TDD 1.28Mcps Option". This, and TD-CDMA (an independently developed TDD CDMA system more closely related to W-CDMA), are offered as air interfaces for the UMTS-TDD system, a version of UMTS used largely to provide Internet access. The use of TDD is more efficient than FDD at dynamically providing asymmetric data rates, which are typical in ordinary Internet use.

TD-SCDMA uses TDD, in contrast to the FDD scheme used by W-CDMA. By dynamically adjusting the number of timeslots used for downlink and uplink, the system can more easily accommodate asymmetric traffic with different data rate requirements on downlink and uplink than FDD schemes. Since it does not require paired spectrum for downlink and uplink, spectrum allocation flexibility is also increased. Also, using the same carrier frequency for uplink and downlink means that the channel condition is the same on both directions, and the base station can deduce the downlink channel information from uplink channel estimates, which is helpful to the application of beamforming techniques.

TD-SCDMA also uses TDMA in addition to the CDMA used in WCDMA. This reduces the number of users in each timeslot, which reduces the implementation complexity of multiuser detection and beamforming schemes, but the non-continuous transmission also reduces coverage (because of the higher peak power needed), mobility (because of lower power control frequency) and complicates radio resource management algorithms.

The "S" in TD-SCDMA stands for "synchronous", which means that uplink signals are synchronized at the base station receiver, achieved by continuous timing adjustments. This reduces the interference between users of the same timeslot using different codes by improving the orthogonality between the codes, therefore increasing system capacity, at the cost of some hardware complexity in achieving uplink synchronization.

• Dynamic TDMA

• TD-SCDMA Forum
• TD-SCDMA Industry Alliance
• China will not interfere in 3G standard selection
• China will provide 3G Service in cities where Olympic Games 2008 are held

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