UTRA TDD LCR (TD-SCDMA) ...
NF,
<< The more I read about TD-SCDMA, the more I get the impression that it may have already lost many of the advantages it's designers envisioned back in '99. Many of the "tricks" are being incorporated into other wireless flavours. By the time TD-SCDMA becomes commercial, it is most likely going to be lagging in both capacity and capability compared to existing commercial wireless networks. >>
In a certain sense you are correct ... but I think you might be missing something.
What makes TD-SCDMA (3GPP UTRA TDD LCR) unique is that it goes where other fully standardized 3G technologies simply do not go ... i.e into relatively uniform unpaired spectrum set aside by the ITU at WARC 92 (1992) of which there is plenty with no solution until now (except from IP Wireless). There is no WCDMA solution and there is no CDMA2000 DO-EV solution -- now, or planned ...
• China has set aside 155 MHz of unpaired IMT-2000 spectrum for a TDD solution.
• Japan has IMT-2000 unpaired spectrum for a TDD solution.
• Virtually every European network operator that has a UMTS WCDMA license for paired IMT-2000 spectrum also has a license for 5, 10, or 15 MHz of IMT-2000 unpaired spectrum for a TDD solution (either UTRA TDD LCR or UTRA TDD ) accompanying the FDD (WCDMA) license.
Spectrum is finite and precious, especially since wireless data chews it up. The unpaired TDD spectrum will be utilized globally where it is licensed and available, particularly in urban areas.
<< It may be the case, that the one positive TD-SCDMA retained over versions of wireless (ie combining TDD/CDMA/TDMA into a single offering on top of circuit switched GSM-MAP). >>
More correctly stated, IMT-TC Time Code (TDMA/CDMA) combined TDMA and CDMA on a circuit switched and packet switched GSM-MAP network with the GPRS IP backbone supporting the GPRS bearer, in the TDD mode. There was a 2nd generation commercial or semi-commercial version for FDD mode. TD-SCDMA was originally commercialized as a 2nd generation solution.
Perhaps this 2004 Word document will help clear up some misconceptions you may still have ...
tdscdma-forum.org
You might also want to digest this 2004 Yankee Group article which begins ...
tdscdma-forum.org
October 2003 marked the first anniversary of China’s 3G-frequency plan; however, the Chinese government has not yet granted 3G licenses to any operators. Although the government continuously supports China’s native standard, Time Division-Synchronized Code Division Multiplex Access (TD-SCDMA), the regulators and potential operators face the dilemma of choosing from one of the two different flavors of TD-SCDMA -- the TD-SCDMA system for mobile (TSM) and Time Division Duplex Low Chip Rate (TDD-LCR) ...
<< Combining TDD/CDMA/TDMA into a single offering on top of circuit switched GSM-MAP) is what resulted in it's belated delivery. >>
Not really. What actually delayed it, as I have stated to you before, was the lower priority it was given by most of the major network infra suppliers (particularly Ericsson, Nokia, and Lucent) and the harmonization of TD-CDMA and TD-SCDMA which took more time than anticipated. Such is life. Standards mature when they feel like maturing, and they especially mature after they get into real life pre-commercial trials and are shaken down. Nobody is more acutely aware of this than QUALCOMM who delayed and delayed and delayed IS-95 cdmaOne -- or Ericsson with IS-54 TDMA whose original standard was rushed to completion. It took IS-136 to straighten it out.
There was one thing that delayed it, and it is the identical thing that delayed WCDMA. GPRS delayed it. Motorola especially (and a few others) attempted to commercialize GPRS infra and handsets to an early and immature version of the GSM R'97 standard (while others like Ericsson and Nokia waited for the standard to mature). In addition within 3GPP it took until June 2001 (instead of the December 2000 target) to achieve backward and forward compatibility of WCDMA in 2.1 GHz with GSM/GPRS in 900/1800 MHz for the UMTS R'99 standards
Even though Hutchinson 3G launched UMTS commercially with roaming on R'97 GSM/GPRS networks, GPRS and WCDMA still needed to be matured to achieve seamless intermodal and interfrequency handover of CS voice and CS and PS voice and data -- no small task.
A reasonably fully mature GSM R'99 standard and a reasonably fully mature and stable UMTS (WCDMA) standard were achieved in March 2002 and the March 2003 releases were even more stable. Tests scripts (the final ingredient) for test equipment completed sometime after November 2003. In order to get all multi-sourced GSM/3GSM operators on the same page, however, they needed to upgrade to the GSM R'99-March03 software infra rev. and rollout UMTS R'99-March03 software. Some weren't budgeted in 2003 for that for that GPRS software upgrade so the major commercial launches other than HW 3's, took place in H2 2004, 12 to 18 months after the initial '3' commercial launches.
Motorola went through the same thing when they tried to bring up IS-95 CDMA in Hong Kong in 1994.
They finally brought HW-HK up one year later but it was still a bloody mess. It took the Koreans (carriers -- particularly SK Telecom, and Samsung and LG) working hand in hand with QUALCOMM to straighten it out. They worked around the clock 24/7 in a pre-commercial then a commercial environment to make it work and mature the standard. One full year after the Hong-Kong mess (still a mess) launched Korea had a working CDMA system with half a million subscribers (compared to ~5,000 in the States and maybe 50.000 in Hong Kong) and by year end they had over 1 million. By that time AMPS to CDMA to AMPS to CDMA handover issues in 800 MHz had also been resolved and it was onwards and upwards.
<< The more I read about TD-SCDMA >>
Keep reading. There will be a quiz. <ggg>
One final thought. How and to whom China licenses TDD spectrum and the buildout requirements they place on it will determine its relative sucess or failure in the near to medium term.
- Eric - |
