Examination of China's 3G CDMA Alternatives
This is an excellent article and it has a very good and up to date overview of the ITU IMT-2000 3G CDMA standards
>> Probing into China's 3G Road
Li Jinliang
China Mobile Communications
Issue 200208
August 2002
cicmedia.com
I. The Development Process of Digital Television Standards
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The forming process of the American digital television standard and measures of laying down digital television standard organized by our country can be learned for reference to the formulation of 3G system standard in our country.
3G has more profound prospects than digital television system. Therefore, the Government should attach great importance to such a tremendous market in the future valued at 1 trillion yuan laying down a national standard for 3G (C3G) by completely learning from the digital television formulation mode of our country.
II. Status Quo of 3G in the World
Technical norms worked out by 3GPP (The 3rd Generation Partnership Project for boosting the W-CDMA standard) and 3GPP2 (for boosting the cdma2000 standard) as authorized by ITU are as follows:
For Access Network:
(1) CDMA DS (W-CDMA), a kind of CDMA FDD system;
(2) CDMA MC (cdma2000), also a kind of CDMA FDD system;
(3) TD-SCDMA and UTRA CDMA (actually two types), a kind of CDMA TDD system;
(4) TDMA MC (UWC-136), a kind of TDMA FDD system;
(5) TDMA SC (UP-DECT), a kind of TDMA TDD system.
For Core Network:
(1) GSM MAP for CDMA DS allowing for the continuation of the current GSM system;
(2) ANSI 41 for CDMA MC to be compatible with the current IS-95 CDMA system;
(3) IP, which is the direction for the future and being formulated now, probably delayed till 2002.
3GPP for W-CDMA worked out GSM core network based W-CDMA Release 99 in 2000, TD-SCDMA Release 4 in 2001 and will formulate IP core network based Release 5. Moreover, Release 3 was updated respectively in March, June and September 2001 with one update every three months.
3GPP2 for cdma2000 worked out three releases, currently having Release 0, Release A and Release B. It laid down the enhanced 1xEV-DO (voice only) standard in 2000, began to formulate 1xEV-DV (data and voice) standard in 200l, and will also draft IP core network based Release C.
As for the formation of IMT-2000 series standards for 3 G only, it has witnessed a lengthy process of 17 years, unfortunately there still exist some undesired parts that are against its original intentions now. There exist the following problems in 3G as analyzed from characteristics and development trend of information and communications technology and as viewed from the current situation of 3G in the world:
• There exist 5 different technical systems for access network and 3 different technical systems for core network, which are not unified in each network yet;
• Series proposals and mainstream technology can not accommodate the development demand of Internet;
• The system is unable to satisfy the development requirement of information and communications industry;
• There exist too many standard versions with updates too frequently made or even one update every three months;
• Technically is not mature and market as well, a lot of problems existing in infrastructure and mobile phones;
• 3G license and spectrum utilization are auctioned at higher prices, massive commercial operations in Europe, US and Japan will be postponed till after 2003 successively.
It can be seen from above that there exist a raft of problems and barriers, no one could tell which technical system will dominate the international market in the future.
III. Progress of 3G in China
As approved by the State Council in November 1998, Chinese 3G (C3G)-a national substantial scientific research project jointly implemented by Ministry of Science and Technology and Ministry of Information Industry was officially initiated. This project has involved almost 3,000 scientific research personnel from more than 20 universities, research institutes and enterprises nationwide for three years, performing theme studies in two phases of W-CDMA and cdma2000. The R&D works have been basically completed and the overall objective set for the project has also been basically realized, having worked out nearly a hundred patents with independent intellectual property rights, developed field experimental systems including wireless access network, core network and terminals. R&D teams from Huawei, ZTE and other companies of our country have been engaged in application research following CDMA development, meanwhile performed the initial development of W-CDMA and cdma2000 and successfully developed pre-commercial operational systems which have officially passed testing sponsored by the national authoritative departments. The successful development of C3G has marked that our country has basically mastered 3G technology, having laid down a certain technical basis for the industrialization of 3G in the future.
TD-SCDMA scheme proposed by our country at the end of 1999 is accepted by ITU-R as one of 3G systems, which is a complete system standard proposal put forward by China for the first time. It was accepted in march 2001 by 3GPP to become one part of its standards. Time division duplex (TDD), synchronization technology and software radio technology are employed in TD-SCDMA. Datang Group has conducted the standard formulation work for three years and performed product development for two years in cooperation with such domestic and foreign companies as Siemens in the principle of mainly relying on its own efforts. The first call was put through in April 2001, image transmission from terminals to base station was finished in July, its chip was under development in September that year in alliance with domestic and foreign enterprises, a public outdoor field demonstration of TD-SCDMA was conducted in February 2002 for the first time performing real time transmission of voice and image in a vehicle traveling at the speed of 125 km/hour 16 km away from the base station, which had passed acceptance test of the national substantial scientific research project.
FOUNDER LIANYU Communications Co. of our country proposed LAS-CDMA scheme in 2000 as an optional 3GPP2 technology, which employs large area synchronization code division multiple access and other patented technologies. In September 2000, testing and evaluation of concept model of LAS-CDMA were organized by Ministry of Information Industry, having verified the existence of non-interference window. In September 2001, a TD-LAS single base station system was demonstrated in a vehicle traveling at high speed in Shanghai with clear voice and stable image, having verified the feasibility of TDD system. In February 2002, a TD-LAS system consisting of three base stations was tested in Shanghai by TD-LAS system evaluation expert group organized by the State, making an IP call from TD-LAS mobile station to GSM mobile phone and realizing data transmission at 384 Kbit/s in the mobile environment of vehicle traveling at high speed.
Important features of LAS-CDMA codes lie in that self interference of address codes is zero, and mutual interference between address codes is also zero within a given "window" with interference only occurring in edge between one window and another, a non-interference CDMA system can be realized only if these windows are applied to cover the actual propagation conditions.
It is because of the following that LAS code is regarded as a substantial original invention independently developed by our country:
Professor Li Daoben of Beijing University of Posts and Telecommunications has searched for ideal spread spectrum address code with viewpoints of information theory for more than 30 years and finally had an important breakthrough inventing large area synchronization CDMA spread spectrum code entitled LAS. Meanwhile, Professor Fan Pingzhi from Southwest University of Communications (also guest professor of University of Leeds of UK) also published independently many papers in such academic periodicals as IEEE of US, IEE of UK and IEICE of Japan, forming a systemized encoding theory. These two Chinese scholars have acquired the same result respectively.
Second, these research achievements have been filed and awarded with patents at home and abroad. Such research achievements have increasingly been highlighted in the international academic circles and were popularly given attention to at an international conference on sequential design and its application in CDMA system (IWSDA'2001) held in September 2001.
Third, a series of outstanding advantages such as high spectral efficiency, high data rate in transmission and communications at high mobile speed have been verified through computer simulation verification theoretically as well as the above mentioned testing and evaluation many times practically. Particularly due to structural principle of its core address codes is completely different from that employed in traditional CDMA codes, it can be free of constraints from intellectual property rights of other countries.
As for 3G system, four kinds of 3G experimental systems have been successfully developed in parallel including W-CDMA, cdma2000, TD-SCDMA and TD-LAS. All these remarkable scientific research developments have created a basic technical condition for formulating a national standard for 3G in our country. The technical breakthrough of LAS code to CDMA system in particular will bring about revolutionary innovations to mobile communications systems.
IV. The Industrialization Road Of 3G In Our Country
It is clearly specified in the outline of the "Tenth Five-Year Plan" for information industry of our country to speed up research, development and industrialization of the third generation mobile communications technology and products. There are many options for the third generation mobile communications technology and products for us, whether should we follow Europe and Japan to take the road of W-CDMA or walk along the road of cdma2000 as US does, or rely on our own to actively implement the industrialization of TD-SCDMA and TD-LAS system of our country?
At the end of June 2002, the quantity of mobile users in our country has hit 176 million exceeding US last year, consequently enabling our country to have the largest mobile communications network in the world. This number will probably exceed 350 million by 2005, the overall volume of investment in infrastructure added up by the overall volume of sales of mobile terminals in next few years will go over 1 trillion yuan, revenues of relevant industries boosted by the mobile communication industry can be over 10 trillion yuan. Following China's accession to WTO, as one of largest information technology markets in the world, China has already become an important battle field watched closely by internationally renowned carriers and manufacturers. Such a tremendous market is a resource that is worthwhile for us to take pride in, we could not stay idle and do nothing at all. The controversy on the standard for 3G will have an impact on the development direction and process of global information and communications industry, we can fully implement our own LAS, C3G and other patented technologies, actively organize the formulation of 3G system standards, protect domestic market with technical system standards to support the development of national industry with domestic market.
Generally speaking, Europe and Japan want to utilize W-CDMA while US intends to use cdma2000, so these two large groups will dispute in this regard with strength scattered, thus leaving a space for our country to develop our own technical system; frequently updated standard versions have puzzled manufacturers, it is hard for the technology to mature right now, so commercial operation has to be postponed several times, giving a period of time for our country to develop independently. The downturn of global economy has impeded the development of 3G, but our economy and mobile communications have still maintained momentum of sustained growth. We can sit down and observe the constructions of various kinds of 3G communications networks in the world, and it is absolutely not necessary to let our country to become a test field of their various technical systems that are not mature yet.
In order to pool our resources for advancing 3G standard of our country and implementing its industrialization, the following suggestions are made:
(1) To Test and Evaluate Experimental Systems for 3G
It is recommended to test and evaluate 4 kinds of 3G experimental systems in an equal condition for W-CDMA, cdma2000, TD-SCDMA and TD-LAS that are developed in China, aiming at complementing each other and promoting convergence other than discarding any of them. Main technical personnel respectively in charge of these four experimental systems can be called to work out together the specific testing and evaluation measures and opportunities should be given to investigate 3G systems in the world so as to learn from them for reference in our construction.
(2) To Formulate a National Standard for 3G
After the evaluation above mentioned, national will should be fully embodied to complement different options and promote their convergence so as to form the unified national standard of 3G as the basis for the development of commercial system and industrialization in our country. We should not be discouraged to think that 3G is done and new options will not be agreed and accepted. We should find that there are five standards for 3G in the world, which are not unified with frequent version updates, it is far from being decided which technical system has more advantages. The controversy on standards is in fact the controversy on national interests, whoever has the strongest national strength will enable its standard to become the mainstream standard of the world. China is the largest market all over the world and can completely own its own standards and have an influence over the tide of the world.
(3) To Boost Industrialization of 3G in China
Considering that mobile communications industry is substantial infrastructure construction vital to national economy, which demands tremendous investment in various aspects such as manpower, material and financial resources and so on, it is far from enough to just rely on efforts of a small number of enterprises. We should not distribute our limited manpower, material and financial resources into industrialization of four different systems at the same time, we should leave something aside so as to do something else. Therefore, it should be raised to the height of national will and listed under the national development plan, taking effective measures, coordinating all forces, giving all necessary supports to 3G technology with independent intellectual property rights and greatly moving forward the industrialization of enhanced TD-SCDMA.
It has been an inevitable trend for 3G to migrate towards wireless Internet. If we adhere to the correct direction of independent innovations, we can rest assured that 3G will undoubtedly enter and have a deep influence on life of our country in the future. As above mentioned, technical and marketing environments at home and abroad have provided a good opportunity of "once in a hundred years" for our country to revitalize information and communications industry. If we can get hold of such an opportunity for 3G communications system, be brave to innovate, take a more advantageous path and endeavor to master substantial original core technology with independent intellectual property rights, we will catch up with the world development and enable China to become a strong power of information and communications in the 21st century.
About the Author:
Li Jinliang is senior engineer at professor level, member of Science and Technology Commission of Electronics under Ministry of Information Industry, member of China Society of Communication and expert enjoying special allowances from the State. He has long been engaged in scientific research works of tactical communications and mobile communications system with many prizes awarded and has published many technical books. <<
The ITU IMT-2000 Radio Interface Standards (Original)
itu.int
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