iXBT Labs - Computer Hardware in Detail






NTT DoCoMo network communication

Today WAP is a primary standard for transferring online information to mobile users. However, this standard has some drawbacks such as low connection speed, non-dynamic data update and a relative complexity of content preparation for publication. Such problems had urged a Japanese company, NTT DoCoMo, to create an i-mode network which was started in February 1999 and now is servicing more than 20 million of users.

The key difference of the i-mode system from the WAP is usage of cHTML (compact HTML - a light version of the HTML 4.0) as a base for content creation. Some functions of course were deleted: support for JPEG (only GIF), tables, image maps, color background and some others (for detailed information on the cHTML go here). Hardware requirements for the cHTML are the following:

  • 128-512 KBytes RAM and 512-1024 KBytes ROM,
  • 1-10 MIPS processor,
  • 50X30, 100X72 or 150X100 display, W/B (though, a color display is also possible).

A typical phone with an i-mode support looks like this:

Such device weighs 90 g. To simplify text input a small keyboard can be attached to a phone. The i-mode network allows a user to access the Internet via an NTT DoCoMo portal which contains references to more than 1,500 resources. There are such services as bank and financial info access, weather forecasts, telephone directories, online stores, ticket purchase etc. A certain button on the phone allows to access the i-mode network. It's worth noting a convenience of combining online information and voice facilities. For example, a user decides to order tickets for a concert or a display. For this purpose he either has to visit a corresponding resource from an i-mode catalog or to dial a number from that catalog by a voice instruction.

The i-mode system allows a user to access independent sites (not included in the i-mode catalog): a user should key in a URL of a site with cHTML contents.

The i-mode network scheme if shown on the figure below:

Such sites as CNN, Dow Jones, Citibank and many others can be accessed in the i-mode.

Phones with i-mode support has an e-mail function what makes possible to send e-mail not only to other i-mode devices but also to usual computers and PDAs. And since i-mode is constantly on-line, e-mail messages can be received and displayed right away. Each user of the i-mode network receives an e-mail address 090xxxxxxxx@docomo.ne.jp, where XXXXXXXX is a phone number of the user in the network.

A user can cancel a receipt of e-mail messages from the Internet, from i-mode devices or from the both in order to get rid of spam. One can also set a mode for automatic sending of e-mail messages in a definite period of time (maximum 3 months ahead) or view an e-mail box with an i-mode phone (though note that this service is not free and not all providers support it).

In January 2001 NTT DoCoMo introduced a new service for i-mode users: implementation of special applets in the phones. A language for applets is based on Java and allows to create such dynamic applications as share rate monitoring and online games. This service is called "i appli". Here are some examples of this technology:

  1. Automatic request for weather forecast for the next day. A user can set his alarm clock in order to get up according to the weather forecast (in case of heavy snowfall it might take much more time to get to work).
  2. Share rate online monitoring can come in handy for speculators.
  3. Maps with description of more than 170,000 places (in Japan).

Such service costs only 300 yens a month ($2.5), plus a charge for data delivery to a user. For example, news delivery costs 17-18 yens, money transference from a bank account - 59-60 yens, share rate delivery - 26-27 yens. Loading of a full-screen image takes 7-8 yen (6 cents).

20 million of users of the i-mode network can use today around 40,000 sites. The figure shows how a number of resources offering i-mode contents is growing:

NTT DoCoMo is going to spread the i-mode network all over the world, and now they are holding talks with telecommunicational companies in the USA and Europe.

But despite all advantages the i-mode has a serious drawbacks: too low speed (9600 KBytes/s). The most part of the mobile phones belongs to the first and second generations (1G and 2G). 1G handsets were analog, the second generation turned to a digital communication. But due to a low data rate they are suitable only for voice communication. These problems brought about the development of a new standard - the next, third generation of mobile communication technologies.

The 3G standard implies a higher data rate - 2 Mbps (like ADSL), what allows to transfer video with a decent image quality, as well as to load and play different audio information (music, news etc.).

Secondly, the 3G standard, like the i-mode, ensures constant network connection: to view an e-mail you need not to dial a number and wait. The companies promise that the price for such service will be acceptable in case of a mass spread-out of the technology. The payment principle will change: in the 3G networks a user will pay not for time but for a volume of the data received.

The 3G networks are based on the W-CDMA standard (Wideband Code Division Multiple Access), which is a part of the CDMA standard group. The W-CDMA differs from the TDMA, which is currently used in GSM and DAMPS networks, in the fact that it uses the same frequency band for transmission of messages in all network locations, what allows to reduce a range of frequencies utilized and increases the system reliability since switch of a frequency band is not necessary when migrating from one location to another:

W-CDMA equipment can choose a data rate automatically according to a volume and a type of data transferred.

NTT DoCoMo offered their own realization of the W-CDMA standard named FOMA (Freedom of Mobile multimedia Access). The maximum speed of the incoming traffic in this system is 384 KBytes/s and the speed of the outgoing one is 64 KBytes/s. The system is capable to integrate with content-servers what makes possible to widen a range of the information accessible:

The commercial use of the FOMA networks is scheduled for May this year. By the launch of the system three types of phones will be available:

  1. A base phone - renewed versions of the current i-mode phones which provide an increased quality of voice transfer.
  2. Video telephone - apart from functions included in base models it will be equipped with a video camera.
  3. PC-card terminal - intended only for a high-speed data rate.

In simple words, the FOMA is an advanced variant of the i-mode, which differs from the latter one in a high-speed of data rate. It will allow users to access multimedia contents or to attach a video clip to an e-mail message. Quality of the received data must get considerably improved: 384 KBytes/s allows to view video clips in real time mode or to organize a conference with only one phone.

Many companies have already introduced prototypes of devices compatible with W-CDMA at CeBIT'2001:

Also, there were prototypes of interface devices in PC-Card format:

Such cards provide high-speed access for data transfer via W-CDMA networks for notebooks and PDA devices. I should note that none of the present-day technologies allows to get such a perfect combination of speed and mobility as W-CDMA does.

But in spite of a great deal of advantages of the W-CDMA technology many analysts doubt that possibilities provided by W-CDMA networks will be very popular. But remember that when VHS format appeared on the market, home video systems market was not built up yet, however with time the VHS proved its mighty. I hope that such a promising technology as W-CDMA will achieve a great success and public recognition on the mass market.


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