What is TD-SCDMA

TD-SCDMA is "time division-synchronous code Division Multiple Access" abbreviation, the Chinese meaning is "cent synchronous code division multiple Access", this communication technology also belongs to a kind of wireless communication technical standard, It was first proposed by China and on the basis of this wireless transmission technology (RTT) and international cooperation, completed the TD-SCDMA standard, become a CDMA TDD standards, this is a pioneering work of China's mobile communications industry, but also China's third generation of mobile communications development contribution. China's TD-SCDMA has officially become one of the world's 3G standards in the competition with the 3G standards proposed by Europe and the United States, marking China's global leadership in the field of mobile communications. The main technology of the scheme is concentrated in the hands of Datang Corporation, whose design refers to the time domain mode of TDD (TDMA) in the unpaired frequency band.

The TDD pattern is based on the iterative TDMA frame structure in the time domain of the wireless channel. This frame structure is subdivided into several time slots. In the TDD mode, it is easy to switch between the upper and lower links flexibly. The salient advantage of this pattern is that the time slot allocation between the top/downlink links can be changed by a flexible conversion point to meet different business requirements. In this way, using TD-SCDMA technology, all 3G symmetric and asymmetric services can be realized by changing the switching point of the upper/down link flexibly. The appropriate TD-SCDMA time domain operation mode solves the problem of resource allocation on the top/down link of all symmetric and asymmetric business and any mixed service.

The TD―SCDMA Wireless transmission scheme integrates the basic transmission methods such as FDMA,TDMA and CDMA flexibly. Combined with joint detection, it shows remarkable performance in terms of transmission capacity. Through the introduction of smart antenna, capacity can be further improved. The smart antenna reduces the interference caused by the small interval frequency multiplexing, and provides higher traffic volume through higher frequency multiplexing rate. Based on high business agility, TD―SCDMA wireless networks can be connected to switched networks via the wireless network Controller (RNC), as defined by the circuit and packet switching services in the three-generation mobile communications. In the final release, plan to have TD―SCDMA wireless networks directly connected to the Internet. (Computer science)

TD-SCDMA's Advanced mobile wireless system is designed for symmetric and asymmetric 3G services in all wireless environments, and it runs on the unpaired radio frequency spectrum. The time domain Adaptive resource allocation of TD-SCDMA transmission direction can obtain the optimal utilization of spectrum allocation independent of symmetric business load relationship. Therefore, TD-SCDMA through the best adaptive resource allocation and optimal spectrum efficiency, can support the speed from 8kbps to 2Mbps of voice, the Internet and all the 3G business.

TD-SCDMA for TDD mode, in the scope of application has its own characteristics: first, the terminal mobile speed by the existing DSP operation speed limit can only do 240km/h; second, the base station coverage radius within 15km, spectrum utilization and system capacity can reach the best, in the user capacity is not very large area, Base station maximum coverage up to 30-4km. Therefore, TD-SCDMA suitable for use in cities and suburbs, both in urban and suburban areas do not affect the actual use of these two deficiencies. Because in cities and suburbs, speed is generally less than 200km/h, urban and suburban population density is high, because of capacity, cell radius is generally within 15km. While in rural areas and large areas full coverage, the use of WCDMA FDD mode is also appropriate, so TDD and FDD models are complementary to each other.

The status quo of TD-SCDMA standards

Since the release of 3GPPR4 in March 2001, the substantive work of TD-SCDMA standard specification is mainly done under the 3GPP system. More than two years after the R4 standard was released, along with many other industry operators and equipment manufacturers, Datang has been through numerous meetings discussions, mail group discussions, and through a large number of submissions, physical layer processing of TD-SCDMA standard specifications, high-level protocol stack messages, network and interface signaling messages, RF indicators and parameters, conformance testing and other parts of the content of the revised and improved, so far the TD-SCDMAR4 standard has reached a fairly stable and mature degree.

Under the frame of 3GPP system, after merging and perfecting, due to the difference of duplex mode, all the technical features and advantages of TD-SCDMA can be embodied in the physical layer of the air interface. The difference of physical layer technology is the main difference between TD-SCDMA and WCDMA. In the core network, TD-SCDMA and WCDMA use the same standard specification, including the core network and wireless access network using the same IU interface; On the high level protocol stack of air interface, TD-SCDMA and WCDMA are identical. These similarities ensure the seamless roaming, handoff, consistency of business support, guarantee of QoS, etc., and ensure the consistency of TD-SCDMA and WCDMA in the subsequent development of standard technology.

January 20, 2006 has been declared as China's national communications standards. (Note: The argument is not exact.) January 20 National Ministry of Information Industry as industry standards, rather than national communication standards)

The follow-up development of TD-SCDMA Standard

With the development of 3G technology and system, both equipment manufacturers, operators, and various research institutes, Governments and ITU have begun to study the future of technology in 3G. In several technical development directions identified by the ITU, including the smart antenna technology and TDD time Division duplex technology, that these two technologies are the future trend of technology development, and the smart antenna and TDD Division duplex technology, in the current TD-SCDMA standard system has been very well reflected and applied, From this point, we can see that TD-SCDMA standard technology has a considerable development prospects.

In addition, in the 3GPP release after the R4, TD-SCDMA standards also introduced new technical features to further improve the performance of the system, including: through the air interface to achieve the synchronization between the base station, as a base station synchronization of another standby scheme, Especially suitable for the guarantee of communication network reliability in emergency situation; terminal positioning function, through the smart antenna, the use of signal arrival angle to position the end user location, in order to better provide location-based services; high-speed downlink packet access, hybrid automatic retransmission, adaptive modulation coding to achieve high rate downlink packet service support ; multi-antenna input and output technology (MIMO), using base Station and terminal multi antenna technology and signal processing to improve the performance of wireless system, uplink enhancement technology adopts adaptive modulation and coding, hybrid ARQ technology, fast allocation of dedicated/shared resources and corresponding physical layer and high level signaling support mechanism. Enhance uplink channel and business capability.

With the full support of the government and operators, the TD-SCDMA Industry Alliance and the industrial chain have been basically established, product development has been further promoted, more and more equipment manufacturers have invested in the TD-SCDMA product Development camp. With the development of equipment and field test, TD-SCDMA standard will be further validated and strengthened.
In order to speed up the industrialization of TD-SCDMA, the early formation of a complete industrial chain and multiple manufacturers supply environment, October 30, 2002, the TD-SCDMA Industry Alliance was established in Beijing. The TD-SCDMA Industry Alliance member Enterprises from the initial 7, developed to the current 30 enterprises, covering the TD-SCDMA industry chain from the system, chips, terminals to test instruments in every aspect.
Union Nature:

The TD-SCDMA Industry Alliance is a voluntary social organization which is engaged in the TD-SCDMA Enterprise and engages in the research, development, production, manufacture and service of TD-SCDMA standards and products.

Alliance Tenet:

Integrate and coordinate industrial resources, improve the research and development of mobile communication enterprises in the alliance, and promote the rapid and healthy development of TD-SCDMA communication industry, and realize the popularization and application of TD-SCDMA in China and global communication market.

Alliance Business Scope:

The TD-SCDMA industry Alliance mainly revolves around the TD-SCDMA technology to carry on the standard advancement and the consummation as well as the industry management and the coordination, promotes the enterprise resources sharing and the mutual benefit, proposes the Government to formulate the important industrial policy which is advantageous to the TD-SCDMA development, promotes the alliance internal Communication Enterprise's group

The TD-SCDMA Industry Alliance carries out the Unified intellectual property management policy, the technical information and the market information highly shares, through the close communication, the reasonable division of labor, promotes the TD-SCDMA industry fast healthy development.

Alliance members:

Institute of Telecommunications Science and Technology (Datang Telecom Technology Industry Group), Holley Group Co., Ltd., Huawei Technology Co., Ltd., Lenovo (Beijing) Co., Ltd., Shenzhen ZTE Co., Ltd., China Electronic Information Industry Group, China Putian Information Industry Group, Beijing Tian Acer Technology Co., Ltd. Chongqing Heavy Mail Branch Co., Ltd., Hisense Group Co., Ltd, kaiming Information Technology Co., Ltd., Xian Haitian Antenna Technology Co., Ltd., exhibition Communications (Shanghai) Co., Ltd, Beijing Zhong Chuang Letter Testing Technology Co., Ltd., Hubei Public Friends Technology Industry Co., Ltd., Shanghai Bell Alcatel Co., Ltd., Shanghai di-bit Industrial Co., Ltd., UT Tatsu Kang Company, British Huada (Shanghai) Electronics Co., Ltd., Zhongshan Communication Equipment Co., Ltd., Qingdao Haier Communications Co., Ltd., Shanghai Ke Tai Century Technology Co., Ltd., Wuhan Institute of Posts and Telecommunications, TCL Group, Guangzhou new Mail Communications Equipment Co., Ltd., Andrew Telecom Equipment (China) Co., Ltd., ding-core communications (Shanghai) Co., Ltd., Beijing Xinghe bright spot Communication Software Co., Ltd., Beijing Letter Communication Technology (Guangzhou) Co., Ltd, China Electronics Technology Group 14th Institute, Mobby Antenna Technology (SHENZHEN) Co., Ltd., RDA Microelectronics (Shanghai) Co., Ltd., Beijing Han-Ming Shun Technology Co., Ltd., Ningbo Wave Guide Company Limited, China Electronics Technology Group 41st Institute, billion Yangxin Tong Co., Ltd., Shenzhen Mayor's Network Technology Co., Ltd, Yulong Computer Communication Technology (Shenzhen) Co., Ltd., Seamus Tong Information Technology (Shanghai) Co., Ltd., Mirs Holdings Limited.