Electronic Design

Speedy Cell-Phone "Concierge" Snares 14 Million Subscribers

In what qualifies as an extraordinarily fast introduction, NTT DoCoMo of Tokyo, Japan, has transformed the wireless phone into a "palm concierge." In just a year and a half, 14 million people have subscribed to DoCoMo's i-mode service. That's 10% of all Japanese homes. Kei-ichi Enoki, managing director at DoCoMo, says the company obtained these subscribers by skirting the PC's intimidating aspects.

Possibly, i-mode is the first service to demonstrate that the Internet and true communication mobility can indeed be successfully merged (Fig. 1). Along with traditional voice communications, i-mode offers mobile banking, airline and concert ticket reservations, CD sales, news, weather forecasts, and even horoscopes through its Internet connection.

Enoki says the idea was to allow users to access the Internet without even thinking they were doing so. If the user receives a phone call while surfing the Web, the call gets priority. Once the call is complete, the phone automatically returns to i-mode operation.

In addition to 9.6-kbit/s packet transmission functions, the i-mode cell phone features browser software. Enoki points out that terminals combining cell phones and the Internet have existed for some time. These terminals pursue ease of information viewing rather than conversation, so they're considered information devices instead of telephones. They weigh over 150 g, they're larger than an open hand, and they're about as complicated to operate as a PC.

The International Mobile Telecommunications 2000 (IMT2000) standard should add to i-mode's preferability. Poised to begin service in May, it integrates high-speed, high-volume communications—up to 2 Mbits/s—with GSM or traditional cell phones (PDC). Enoki says the next-generation i-mode, based on IMT2000, will enable users to send and receive moving images throughout the world with quality on par with TV images. Over 20 times faster than a PDC, it will require reduced LSI power and 10 times as much memory.

The key to success is expected to be low-power processors that fulfill a wide range of needs—not just the traditional audio signal processing, but also image, application, and security operation processing. Diverse, high-volume memory will be required because of the immense size and diversification of the data volumes transmitted. Nonvolatile memory will be essential for media downloading services and for backup status parameters to handle momentary interruptions in communication processing.

The power budget for the power amplifier in the new IMT2000-based W-CDMA version will drop from 70% to 25% of the total (Fig. 2). But the need for more signal processing will increase the power consumed by components other than the power amplifier. While users only glance at a traditional, voice-only cell-phone screen, they would watch the i-mode's color screen for much longer periods of time. These factors make power consumption an important issue. So, polymer batteries that use metal lithium will have to replace today's lithium-ion batteries.

TAGS: Mobile
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