Time Division Synchronous Code Division Multiple Access

What Does Time Division Synchronous Code Division Multiple Access Mean?

Time Division Synchronous Code Division Multiple Access (TD-SCDMA) refers to an air interface used in Universal Mobile Telecommunications System (UTMS) networks in the People’s Republic of China. TD-SCDMA was developed as a substitute for W-CDMA. It is also referred to as IMT 2000 Time-Division (IMT-TD) or UMTS-TDD.


TD-SCDMA, a 3G mobile telecommunications standard, was developed initially for China. It was adopted by 3GPP and International Telecommunications Union (ITU) and is becoming a global standard. TD-SCDMA works by using the S-CDMA channel access method over multiple time slots. It is ideal for densely populated locations, and low mobility instances within pico or micro cells.

Techopedia Explains Time Division Synchronous Code Division Multiple Access

TD-SCDMA was developed by the Chinese Academy of Telecommunications Technology (CATT), Siemens AG, and Datang with an intention to avoid dependence on Western technologies like W-CDMA and CDMA2000 EV/DO. The use of other 3G formats patented by western countries require payment of huge patent fees, so TD-SCDMA was developed to evade these high patent fees.

The official launch of a national TD-SCDMA network was first projected by 2005. On 7th January, 2009, People’s Republic of China approved a TD-SCDMA 3G license to China Mobile.

TD-SCDMA blends an innovative Time Domain Duplex (TDD) / Time Domain Multiple Access (TDMA) system using a flexible CDMA component functioning in a synchronous mode. The TDD system permits dynamic adjustments to the volume of timeslots used for uplink and downlink. The system can take care of asymmetric traffic more easily with various data rate requirements on uplink and downlink. Furthermore, usage of the same carrier frequency for downlink and uplink implies that the channel conditions are exactly the same in both directions. This lets the base station deduce the downlink channel data from uplink channel estimates.

TD-SCDMA standard runs on a range of frequency bands somewhere between 1785 MHz and 2220 MHz. When it comes to wireless local loop, TD-SCDMA is often implemented using a frequency band between 1900 MHz and1920 MHz. In TD-SCDMA, voice data are sent at 8 kbps and possible data rates for switch circuit services like video are 12.2, 64, 144, 384, and 2048 kbps. TD-SCDMA’s chip rate is 1.28Mcps.


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Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…