News, views and contacts from the global telecommunications industry

NTT DoCoMo FOMA 3G Mobile Phone Service, Japan

Key Data

NTT DoCoMo, one of the largest mobile communications companies in Japan, launched its third-generation (3G) network on 1 October 2001. Although the network initially only covered a 30km radius in central Tokyo, it was the first 3G network to be implemented in the world.

3G rollout commenced in 2000 and, following the service launch in 2001, continued until the coverage in March 2004 was over 99% of Japan (90% in March 2003). The service was launched under the brand name FOMA (Freedom of Mobile Multimedia Access); it allows the downloading of video images and high-speed Internet access at between 65kbps and 384kbps (downlink), which is 40 times faster than the MOVA 2G network. Other services include packet data communication, short message, voicemail, call-forwarding and call-waiting and enhanced i-mode services. The investment into the infrastructure of the network in 2003 was estimated at ¥800 billion ($6.7 billion).


The contractors supplying and installing the core network equipment, base station transceivers (BST) and infrastructure included NEC, Ericsson and Lucent.

NTT DoCoMo uses an ARIB standardised (wide band code division multiple access) WCDMA solution over the frequency bands 1,920MHz to 1,980MHz and 2,110MHz to 2,170MHz (Frequency Division Duplex). W-CDMA is one of the main technologies for the implementation of third-generation (3G) cellular systems. It is based on a radio access technique proposed and designed by ETSI Alpha group. W-CDMA is based upon two technologies:

Spread spectrum technology: this transmits radio signals over a wider frequency band than conventional 2G systems, allowing all users to share a broad bandwidth. It is robust against disturbance and noise and allows a common frequency to be used across all cells, making frequency switching unnecessary.

Multirate technology: this selects the most suitable communication speed and transmission channel for data based upon its type and size, giving the highest speeds and best quality in transmission.

The network includes over 1,600 base transceiver stations (BTS), which are sited indoors to allow the consumer more accessible connectivity in major buildings, underground retail outlets and subway stations across Japan. In March 2004 the FOMA service was available in 97 stations on four lines of the Toei subway network, and in 43 stations across the seven lines of the Eidan subway network (which is soon to be expanded to 147 stations across eight lines).


The new 3G network also uses Asynchronous Transfer Mode (ATM), a cell switching and asynchronous multiplexing technology that manages packet switching (flexibility, efficiency for intermittent traffic) and circuit switching (constant transmission delay, guaranteed capacity) on the same network using cell relay technology. This means that the same network can handle various traffic types to allow multimedia connectivity (i.e., voice transmission, video, data, MPEG4 etc). The network gains the following benefits:

  • Fixed-size cells, permitting more efficient switching in hardware than is possible with variable-length packets
  • Connection-oriented service, allowing routing of cells through the ATM network over virtual connections, sometimes called virtual circuits, using simple connection identifiers
  • Asynchronous multiplexing, permitting efficient use of bandwidth and interleaving of data of varying priority and size; ATM can also operate point-to-point connections or point-to-multi point connections allowing flexibility for services

The 3G FOMA service has allowed the introduction of newer and faster services by NTT DoCoMo. The i-mode mobile Internet service has benefited from the faster data transmission rate of up to 384kbps. FOMA high-speed packet-data communications are able to handle more multimedia content than ever before.

The greatest benefits are in image and music content and the capability to email messages of greater than 10,000 characters, while attaching images and music files. A mobile videophone service will extend the usefulness of the mobile network and provide a new 'killer app' for NTT DoCoMo. The video transmission will be of sufficiently high image quality to allow even the smallest alterations of facial expressions to be captured in real-time video transmission.

The two data communications services on offer are a packet communication service with a maximum downlink speed of 384kbps and a circuit-switched service offering 64kbps uploading / downloading for large-volume data. Users will be able to view still images, video and other multimedia content using a laptop PC equipped with a 3G network card or a mobile terminal.

One of the latest (March 2004) FOMA developments is controller for home appliances. This will allow a 3G FOMA handset to control the recording by video of a favourite TV show and then allow the tape to be played back and viewed over the phone. The capability of the phone controller could extend to turning lights on and off, setting an air conditioner temperature and controlling both computers and external devices via infrared links and USB connection.


The early range of FOMA handsets included the entry level N2001 (allowing high-speed data communications and multitasking voice and i-mode), the P2101V (video camera and a large colour screen including videophone) and the P2401, a PCMCIA 3G network card for laptops.

NTT DoCoMo introduced the new range of 900i handsets in March 2004 that included: high-capacity Java-based i-appli applications, HTML email (Deco-mail), avatar-capable video phone (Chara-den), combined video and high-fidelity audio for incoming calls (Chaku-motion), and two-million-pixel cameras. The 900i weighs only about 115g and offers about 150hr of standby time.

The newest handset, introduced in early September 2004, is the 3G FOMA 'Raku Raku Phone' handset, which is the first model in the easy-to-use Raku Raku phone series to be compatible with the 3G network. The handset has a camera for videophone calls and sending / receiving video clips via the i-motion mail service. The i-motion mail service lets subscribers send video, recorded by the built-in camera or downloaded from a website, by attaching it to an email. The maximum file size has been extended from 100kB to 300kB, allowing video playback of up to 30 seconds and higher definition images.

The handset features a large 2.4in QVGA screen and the text font may be enlarged up to 30 dots for ease of reading. Onscreen instructions are also available for creating and sending email. In addition, the handset allows 'Multiaccess' which gives subscribers the option of communicating by voice while simultaneously using packet transmissions. The handset is also equipped with a 'Read Aloud' feature that provides audio readouts of i-mode site pages, message logs, operating menus, calculator input / output, email transmission confirmations, low-battery warnings and more.

NTT DoCoMo announced in July 2004 that it will invest ¥5.5 billion over two years (fiscal 2004 to 2005) in Texas Instruments to develop a single-chip large scale integration (LSI), making FOMA 3G handsets compatible with both W-CDMA and 2G GSM / GPRS networks. Currently, it is necessary to embed two chips in order to produce a dual mode handset. Combining the technologies onto a single-chip will result in a low-cost 3G hanset that is able to run on both networks.