Why 3G operators can't ignore TD-SCDMA

Come Beijing Olympics, and China will be showcasing the TD-SCDMA (Time Division-Synchronous Code-Division Multiple Access) technology. Largely unheralded, and spoken about by relatively few, TD-SCDMA may well surprise the telecom industry and pundits.

In fact, it is not even well known that the Ministry of Information Industry (MII) in China had allocated a total frequency of 155MHz for TD-SCDMA way back in Q3 of 2002. Back then, Lothar Pauly, then member of the Group Executive Management of Siemens Information and Communication Mobile had said that the allocation of frequencies for TD-SCDMA in China marked "a milestone in the standard's development." Siemens mobile has been developing 3G technology jointly with the China Academy of Telecommunications Technology (CATT/Datang) since 1998.

As per the TD-SCDMA Forum, China Mobile has announced its TD-SCDMA terminal timetable. Apparently, in China Mobile‘s second round of TD-SCDMA terminal bidding, ZTE has won orders for 61,000 handsets and Samsung for 20,000 handsets.

Also, the MIIT has established a 3G inter-ministerial co-ordination group. Li Yizhong, minister of the new Ministry of Industry and Information Technology (MIIT) in China, says that the ministry has established a 3G inter-ministerial co-ordination group to promote the commercial test and ensure the success of TD-SCDMA.

He says that the ministry should actively promote the commercial test of TD-SCDMA, further reform the system, and carry out the major scientific and technological projects. Relative officials are required to supervise the construction of TD-SCDMA base stations in Beijing to ensure the call quality of TD-SCDMA and ensure the trial operation of TD-SCDMA mobile phone TVs during the upcoming Olympic Games.

The minister has also issued orders to give full support to the implementation of measures and policies beneficial for the development of TD-SCDMA. The ministry should organize Chinese telecommunication units to realize better network optimization, supply special Olympic services, co-ordinate the interoperability between 2G and 3G, solve the problems in the commercial tests, and to ensure the initial success of TD-SCDMA.

All of these developments reminds and takes me back to 2000, when TD-SCDMA was just starting to make the rounds. A good friend, Shih-ying Tan from Siemens Hong Kong, called me up to discuss this technology! Subsequently, it led to visit to Munich, to see the technology first hand!

Here are excerpts from a discussion I had, back in August 2001, with Klaus Maler, who was general manager, TD-SCDMA, for Siemens Information and Mobile Communications in Munich, Germany, at that point of time (in pic). I was serving Wireless Week, US, as its Asia-Pacific editor. Some or most of this may read a bit outdated, but it is still worth a read for those keen on TD-SCDMA.

TD-SCDMA, a 3G technology co-developed by Siemens AG and the China Academy of Telecommunications Technology, is said to be the only technology suitable for TDD (time division duplex) bands. In addition to being more spectrally efficient for both symmetrical and asymmetrical data services, it is capable of dealing with hot spot scenarios. Some TDMA operators reportedly are considering it as an option for migrating to 3G, and once deployed on the mainland of China, it is likely to reach the economies of scale that would make it attractive to mobile operators worldwide.

Acceptance by carriers
What are the chances that TD-SCDMA will be accepted by carriers, given that it is a TDD technology while wideband-CDMA and CDMA2000 are FDD (frequency division duplex) technologies? Isn't TDD in a minority here?

Maler had replied that TD-SCDMA, as well as W-CDMA, uses GSM MAP [manufacturing automation protocol]. This means that it is very likely to have affordable GSM/W-CDMA or GSM/TD-SCDMA dual-mode or GSM/TD-SCDMA/W-CDMA triple-mode handsets. On the other hand, an exotic GSM/CDMA2000 handset should support two different MAPs–GSM and IS-833. Dealing with such complicated and expensive handsets does not encourage GSM operators to adopt a CDMA standard.

As TD-SCDMA is TDD based, it offers optimum spectral efficiency for both symmetric and asymmetric data services. Certainly, carriers won't ignore this aspect. On an international scale, TD-SCDMA is the only technology suitable for the TDD bands, assigned by regulators worldwide and already have been auctioned in Europe. So TD-SCDMA, being an accepted standard worldwide, approved by the ITU and standardized in the 3GPP (Third-Generation Partnership Project), is definitely not in a minority.

Were there any chances that TD-SCDMA won't get locked in like another TDD standard, PHS, has in Japan? In response, Maler said TD-SCDMA is an accepted technology, while PHS is more of a local standard in Japan. Also, TDD frequencies have been allocated in most of the European countries. These are the two major reasons why TD-SCDMA has more potential.

Mainland China is already the largest mobile market now. TD-SCDMA will be deployed in China as a global standard, addressing all sizes of cells, [so] the necessary effects of scale will be available for operators worldwide.

"We had discussed with mainland Chinese manufacturers a few years ago the advantages of combining TDD technologies with smart antennas. We studied this issue and this evolved into continuous improvement and actual development. This happened at a time when we were looking at the mainland Chinese market as a major focus. Last year, when we realized that TD-SCDMA had good potential, we started to introduce it into the 3GPP. Now it has been accepted as a global standard," he said.

According to him, TD-SCDMA has a very bright future, [although] operators may go for a combination of technologies. TD-SCDMA allows operators to add spectrum for voice services using their core GSM networks. The version we are talking about for the launch in mainland China is based on a GSM core network. This will later evolve into a UMTS core network. We started developing the technology three years late, [so you could] say that TD-SCDMA is three years more modern than the other technologies. Now, we are all having trials simultaneously.

Is there a compelling case for TDMA operators to go the TD-SCDMA route? At the moment [this is 2001 end, remember], most TDMA operators in United States, for example, Cingular Wireless, AT&T Wireless and VoiceStream Wireless, are embracing GSM, thereby, acknowledging it as a worldwide standard. They are also committed to adopting the following migration path–TDMA-GSM-GPRS-EDGE-UMTS– following the footsteps of European operators.

Both of the UMTS alternatives –- W-CDMA and TD-SCDMA -– are being taken into consideration by TDMA operators, either as a complementary or an alternative solution. In particular, American TDMA operators believe that TD-SCDMA, thanks to its higher data transmission rate and its capability to deal with asymmetrical traffic and hot spot scenarios, is an interesting technology. The 1.6MHz bandwidth [it uses] will certainly ease the spectrum allocation in the already crowded spectrum currently available in the United States.

Most of the TDMA operators are moving to the GSM-GPRS-EDGE-W-CDMA route. It's not easy to get FDD spectrum in the United States and it will become even more difficult in the future. This is a very good opportunity for a TDD technology like TD-SCDMA.

TD-SCDMA in Europe
Were there any plans to implement TD-SCDMA in Europe, and especially Germany, given that Siemens has been playing an active role in developing this technology?

In Europe, TD-SCDMA will be deployed with capacity-enlargement purposes in W-CDMA networks in hot spot scenarios. By that time, TD-SCDMA will already be a mature technology and will have derived benefits from the mainland Chinese experience.

Most of the operators are now focusing on W-CDMA. They can consider TD-SCDMA to enhance services later on. We are speaking with several operators in Europe. They have been surprised and have actively responded [because] they can see that the chances for TD-SCDMA to succeed have improved considerably. Operators that had not chosen Siemens for some reason now have decided to take another look at us.

And why aren't GSM operators elsewhere showing interest in this technology? Instead, they have been opting for W-CDMA? In the very beginning in Europe, around 1998, TDD was conceived as a technology only for micro and picocell coverage. Consequently, it was considered interesting only in a second phase of the UMTS deployment as a capacity enlargement. Spectrum was assigned and licenses were bought bearing this in mind.

As TD-SCDMA is also able to cover large cells, the momentum behind it is increasing considerably and we are getting quite a lot of interest from European operators of merging TDD activities into this technology.

TD-SCDMA is quite a good alternative. Also, if an operator already has W-CDMA and adds TD-SCDMA, or it's the other way around, it's quite a good combination. Very soon, carriers will notice capacity shortages, especially for the more powerful applications. Facing the fact that they are wasting bandwidth, in terms of asymmetrical traffic, TDD is the technology of choice. The combination of both technologies -- W-CDMA and TD-SCDMA -- may apply in most countries, even here in Europe.

By the way, there used to be LinkAir's LAS-CDMA (Large Area Synchronized Code-Division Multiple Access). LAS-CDMA was also said to offer a higher spectral efficiency and moving speed, thus providing better support for mobile applications. Its asymmetric traffic, higher throughput, and smaller delay provide also improved IP support. A LAS-CDMA TDD variant is compatible with systems such as TD-SCDMA.

I had written about LAS-CDMA back in 2000, but have been unable to find the link. Even there's no update on this technology. Would be great if folks could update me on LAS-CDMA.

Lastly, I need to thank Chi-Foon Chan, president and COO of Synopsys, who I recently met on the sidelines of the Synopsys SNUG event. Chan discussed TD-SCDMA and LAS-CDMA briefly, while touching upon the semicon/EDA industry. But, more of that later!