W-CDMA: China's No. 1 Son?

The latest chapter in the long-running Chinese 3G technology saga has seen Wideband Code Division Multiple Access (W-CDMA) tipped as the potentially dominant standard of choice (see What's Up With Chinese 3G?).

China currently has over 221 million mobile users and adds around four million new subscribers a month, making it the largest single cellular market in the world. Growth figures like these have network infrastructure suppliers and handset manufacturers waiting with baited breath to see which 3G standards the Chinese will pick.

Although the Chinese government has yet to confirm which technology will get the green light -- W-CDMA, CDMA2000, or the homegrown TD-SCDMA (Time Division Synchronous CDMA) -- it is widely assumed that four 3G licences will be awarded. The favorites to win 3G business are incumbents China Mobile Communications Corp. and China Unicom Ltd., as well as fixed-line players China Netcom Corp. Ltd. and China Telecommunications Corp. (NYSE: CHA).

According to a report from Norson Telecom Consulting, China Unicom is the only carrier expected to “forge ahead in a minority position with CDMA2000,” leaving the remaining three operators to begin building W-CDMA networks “with elements of TD-SCDMA.”

“China Telecom…has halted TD-SCDMA testing and shifted its focus to W-CDMA,” notes the research house. “China Netcom, in line with strategic partner Singapore Telecom, has also shown a preference for W-CDMA. TD-SCDMA deployment will remain minimal with the standard merging gracefully into the W-CDMA family.”

The findings mark a significant turnaround in market sentiment. It was originally believed that the Chinese government would opt for a CDMA2000 majority, before talk later turned to a more likely split of two W-CDMA and two CDMA2000 contracts (see Chinese 3G: Open to All?).

The W-CDMA air interface is part of the Universal Mobile Telecommunications Standard (UMTS), which has already been adopted as the European 3G standard. Used with existing Global System for Mobile Communications (GSM) core networks, the theory goes that W-CDMA-compliant handsets and base stations can increase wireless data transfer rates to a maximum of 2 Mbit/s.

CDMA2000 technology is a packet-based extension to CDMA networks that can theoretically support data rates of 144 kbit/s.

Developed by the Chinese Academy of Telecommunications Technology (CATT), TD-SCDMA combines older Time-Division Multiple Access (TDMA) with Time-Division Duplexing (TDD) techniques of broadcasting over a single chunk of spectrum rather than the normal two bands.

Analysts at Norson do not expect 3G licences to be issued until the second half of 2004. “With few successful examples of 3G launches worldwide, the Chinese government will not likely rush into a domestic 3G launch, preferring to keep Chinese operators away from the ‘bleeding edge’ until 3G technologies and business models mature.”

— Justin Springham, Senior Editor, Europe, Unstrung
yangxiao0513 12/4/2012 | 11:30:51 PM
re: W-CDMA: China's No. 1 Son? It is easy to chang the current mobil systems form GSM to WCDMA than TD-SCDMA in China. Since TD-SCDMA adopt more complex tech such smart antenna than WCDMA. Now, the smart antenna has caused great system implementation complexity, which is difficult for the practical base station products. However, for WCDMA, if it adopts STS tech, it will face similar problems. Our simulation shows that STS is also difficult to put into use at base stations.
standardsarefun 12/4/2012 | 11:30:50 PM
re: W-CDMA: China's No. 1 Son? yangxiao, can you give us a few more details i=on the complexity increase for TD-SCDMA vs. WCDMA? Would love to see some real information on this suject that is so often lost in deep politics
yangxiao0513 12/4/2012 | 11:30:34 PM
re: W-CDMA: China's No. 1 Son? I said that TD-SCDMA with more complexity than WCDMA, based on following reasons:

1.TD-SCDMA base station has a cicular array antenna with 8 elements;
2. TD-SCDMA base station needs to provide space beam to 48 mobil acitve users in a cell at same time;
3. there are many problems are caused by the smart anttena:
a. cicular array antenna only has lower space solutions, which lead to the space beams are overlaps;
b. TD-SCDMA base receivers and transmitters need tracking the users; space position;
c. if the users cross into another cell, two base stations need tracking the user and switching their space beam;
d. the above problems will lead to revise some phisical layers and air interfaces;
e. now, the above problems have not been solved.

Thus the TD-SCDMA has much more complexity than WCDMA.

Futher detailed discussion please by E-mail.

My E-Mail: [email protected]
El Rupester 12/4/2012 | 11:27:09 PM
re: W-CDMA: China's No. 1 Son? Yang-Xiao

This is a complex subject.

In many respects I think you are right.
This is a complex system, and probably the first system where smart antennas are included in the standard.

However, you have described the commonest implementation (Siemens / Datang 8-antenna circular) and not all of those features are actually required in the TD-SCDMA standard.

It would be possible to design a simpler implementation that was still standard compliant.

For example, a 3-sector system (as usual cellular) with 4 antennas planar for each sector would deliver higher capacity (sectors) with less complexity in algorithms (4 antennas vs 8 in beam-forming; easier joint-detection & cancellation).

However, aside from the air-interface, there is another area where TD-SCDMA is very attractive.

WCDMA requires much more of a new core network (RNC, Iu-PS and the like), while the TD-SCDMA version ("TSM") uses far more of the GSM notwork (BSC, Gb).

This might make complexity less, and certainly has a lot of attraction for the deployment.
standardsarefun 12/4/2012 | 11:21:58 PM
re: W-CDMA: China's No. 1 Son? el, I am sorry but I don't agree when you say that:
> WCDMA requires much more of a new core network (RNC, Iu-PS and the like), while the TD-SCDMA version ("TSM") uses far more of the GSM notwork (BSC, Gb).

Within 3GPP both of these radio technologies are treated within the same document series and both then use the same signalling protocols between RAN and Core. You might well have seen some sort of demo network with TD-SCDMA conencted via A and Gb but this is not 3GPP compliant
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