Japan-WCDMA>
Development Progressing for IMT-2000 Commercial Services
June 21, 1999 (TOKYO) -- Japan is a leader in the development of commercial services for IMT-2000, the next-generation
international system for mobile communications.
The standards-setting process for IMT-2000 is now approaching a final phase.
Preparations in Japan are moving ahead and the commercial technology is coming into view. Many systems will likely coexist
within IMT-2000. In Japan, it is virtually certain that two mobile network systems will be commercialized.
Commercial IMT-2000 services are due to start in March 2001.
Japan's telecom carriers are speeding up the pace of infrastructure development, with field tests being conducted by five
carrier groups.
NTT Mobile Communications Network Inc. (NTT DoCoMo), Japan' largest mobile services consortium, decided on its
equipment vendors at the end of April. Its base station installation program is slated to begin in the summer of 2000.
Japan to Deploy Both W-CDMA and cdma2000
The five groups engaged in field testing are NTT DoCoMo, Japan Telecom Co., Ltd. (JT), Nissan Motor Co., Ltd., KDD
Corp. and the DDI-IDO alliance (DDI Corp. and IDO Corp.). Except for KDD, the other firms (or their parent companies)
are mobile phone operators (Figure 1).
After considering the radio frequency bands allocated for IMT-2000, Japan's Ministry of Posts and Telecommunications
(MPT) decided in July 1998 that a maximum of three cellular service providers would be permitted to operate in each
regional service area. As a result, the five carrier groups will likely combine to form three coalitions. In view of equity
ownership and other relations among the companies, a feasible three-party arrangement might consist of NTT DoCoMo as a
solo player, JT partnering with Nissan, and the existing DDI-IDO alliance.
Two of the approved and coexisting IMT-2000 standards will be commercialized in Japan -- wideband code division multiple
access (W-CDMA) and wideband cdmaOne (cdma2000). In the field tests now underway, DDI-IDO is using cdma2000
and the other four groups are utilizing W-CDMA technology.
W-CDMA technology was selected by four of the five carrier groups, partly because it is a standard that was developed in
Japan. Another factor in its favor is that W-CDMA appears likely to be the standard adopted for commercialization by the
majority of cellular service providers worldwide, thanks to the efforts toward harmonizing the Japanese standard with Europe.
However, for DDI and IDO, cdma2000 is the technology of choice. The reason is that cdma2000 is an extended version of
the cdmaOne mobile phone service provided by IDO and all of DDI's cellular subsidiary companies.
W-CDMA Has an Edge in Global Roaming Potential
IMT-2000 aims to achieve three major capabilities -- global roaming, superior call quality and high-speed data transfers.
How well will NTT DoCoMo's W-CDMA service and DDI-IDO's cdma2000 service perform in these three areas? Each
capability will be examined in turn.
In the area of global roaming, NTT DoCoMo expects that "roaming will be available in some countries in 2002, but it will
probably be 2003 or 2004 before full connectivity is seen worldwide," a company spokesman said.
At first glance, W-CDMA appears to offer greater benefits in terms of international coverage. W-CDMA is an extension of
the Global System for Mobile Communications (GSM), so it will likely be the choice of most countries that have built GSM
networks. GSM is operational in more than 130 countries, including the United States, China and the Middle East, as well as
in its traditional territories in Europe and Asia. By contrast, cdma2000 will probably be commercialized primarily in countries
that already use cdmaOne systems, such as those of North America and South America as well as South Korea. Because
CDMA systems are operational in only about 20 countries, cdma2000 lags behind GSM.
Multi-mode mobile terminals, however, offer the possibility of coverage across many countries in the near future, according to
NTT DoCoMo. The company intends to provide global roaming capabilities by introducing multi-mode terminals that work
on both W-CDMA networks and on other networks already in existence, such as GSM and personal digital cellular (PDC).
In the long term, NTT DoCoMo hopes to offer dual-mode cellular phones that operate on W-CDMA and cdma2000
systems.
Call Quality to Exceed cdmaOne but Rank Lower Than PHS
Call quality with commercial IMT-2000 systems will be an improvement on PDC and cdmaOne technologies. The
deployment of CDMA technology in W-CDMA and cdma2000 networks enables each transmission to be spread across
multiple channels, thereby enhancing transmission quality. Although cdmaOne also uses CDMA technology, the cdmaOne
spectrum is only 1.25MHz wide, whereas W-CDMA and cdma2000 have spectrums of approximately 5MHz. In theory,
W-CDMA and cdma2000 provide better transmission qualities than cdmaOne.
However, there are two aspects to call quality -- transmission quality (whether voice dropouts are avoided) and voice quality
(whether the voice is in high fidelity). In terms of voice quality, neither W-CDMA nor cdma2000 appears capable of
matching the personal handyphone system (PHS). Voice quality is largely determined by the voice codec (coder/decoder). A
new 12.2kbps codec called Adaptive Multi-Rate (AMR) is planned for W-CDMA, while cdma2000 will use an 8.55kbps
Enhanced Variable Rate Codec (EVRC). PDC, in contrast, is capable of only 6.7kbps in full-rate mode and 3.45kbps in
half-rate mode. But the EVRC to be used in cdma2000 is the same technology as that incorporated in cdmaOne.
The voice quality of the new commercial services should surpass that of PDC systems but be less than the voice quality of
PHS, which uses 32kbps Adaptive Differential Pulse Code Modulation (ADPCM).
NTT DoCoMo to Start with a 384kbps Data Rate
To meet the requirements of the International Telecommunications Union (ITU), commercial W-CDMA and cdma2000
service providers will likely offer the same maximum data rates. Services that deliver up to 384kbps will be on the agenda for
mobile communications up to walking speed. However, cellular service providers using different technologies could offer
other service menus.
For example, NTT DoCoMo plans six options, a choice between a packet-switched or circuit-switched service, each
available at 8kbps, 64kbps and 384kbps rates. More difficult questions are whether IDO and DDI will offer 384kbps
services. The DDI-IDO alliance needs to market cdma2000 as a separate offering from the cdmaOne services that they
launched in 1998-1999, and they also must consider the planned depreciation of the cdmaOne infrastructure.
"For our cdmaOne subscribers, IDO will have a 144kbps packet-switched option by 2001. A possible strategy is to offer
cdma2000 subscribers the same high throughput -- a maximum 144kbps packet service available immediately -- without
launching a 384kbps service," an IDO spokesman said.
Cellular service providers agree that packet-switched services will be the mainstream in IMT-2000 data communications
because packet transmission offers rapid data access at an affordable price. Another advantage is that packet-switched
transmission consumes less power than circuit switching, and for this reason handsets can be miniaturized easily. IDO and
DDI may not offer extra fast circuit-switching services.
Packet Transmission Charges to Depend on cdmaOne Performance
The fee schedule that industry-leader NTT DoCoMo decides upon will influence the charges set by its rivals. DoCoMo's
charges for voice-only W-CDMA services are unlikely to differ from the prices of its current mobile call services. Already,
the company faces spectrum shortages for its PDC services and it urgently needs to shift current subscribers into new
services. It is unlikely, therefore, that NTT DoCoMo would set a premium for W-CDMA services.
As regards charges for data communications, the NTT DoCoMo official explained the company thinking as follows:
"Circuit-switched services cost more than packet-switched services. For example, PDC costs 30 yen a minute at rates of
around 8kbps. If you multiply that rate eight-fold to 64kbps, the result is a charge of 240 yen a minute. But with W-CDMA,
you have a more efficient use of channel capacity. So, for example, if the capital costs are halved, that works out to 120 yen a
minute."
The calculation is a rough estimate. But the chances appear to be remote of NTT DoCoMo offering a 64kbps
circuit-switched service at a price that matches its current 10 yen-20 yen-a-minute PHS services.
Packet switching, on the other hand, poses a difficult problem as regards price setting. If charges are set with only email usage
in mind, surfing the Web would become quite prohibitive because the data volume is vastly greater than for email message
transfers.
IDO anticipates having a 64kbps packet transmission capacity available on its cdmaOne system in December 1999.
On the matter of the packet-switched pricing problem, an IDO official said, "Setting the level of charges is a key issue for our
cdma2000 business strategy."
Related story: Japan's Common Carriers Accelerating Moves to Implement IMT-2000
(Yasukazu Sugiyama, Staff Editor, Nikkei Communications)
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