Section: Communications -- Focus: Wireless Traffic On Broadband
EETimes June 19, 2000, Issue: 1118
Convergence yields i-mode device
Andrew Burt, Wireless Market Development Director, Toshiba America Electronic Components, San Jose, Calif., andrew_burt@taec.toshiba.com
Mobile cellular terminals will be the technology to watch in the next decade. The growth of this industry will overshadow that of the traditional cellular phone and personal computer markets, introducing technologies that redefine Internet appliances of the future. One to watch is the i-mode terminal, a Web access cellular phone already introduced in Japan that, with a few simple keystrokes, connects to a wide range of URLs and displays a Web page. The convergence of the PC market with the cellular phone market will result in this wireless Internet appliance.
However, defining such a product is proving to be difficult for systems designers, especially when attempting to determine whether the form's nature will be that of a cellular phone or a PC. Harvard Business School Prof. Richard S. Rosenbloom has labeled this product a "disruptive technology-a revolutionary design that has created a detour along the evolutionary path of a product."
The main successors of each product segment are claiming to take a leadership position in this revolution. Both the cell phone and the PC industry are evolving to make final competitive application form factors and feature sets. A technically advanced Internet appliance must be wireless and it must meet the market's key criterion (originated at AT&T) of "anytime, anywhere Internet access."
"Web in your pocket" wireless Internet access is creating bold and brave new possibilities for both the wireless service operator and the end user. For the operator the migration path from the current traditional circuit-switched network to an IP-based packet network is a given, since the benefits of an open architecture that allows voice and data to be handled easily bring huge improvements in network efficiencies.
However, soon the majority of new cellular phones will allow truncated data access that uses Web sites specifically formatted in both Handheld Device Markup Language (HDML) or Wireless Access Protocol (WAP), an open global specification for wireless products to access information. The WAP standard is being driven by the WAP Forum. Its membership of over 200 companies is drawn from handset manufacturers, air time providers, infrastructure equipment providers and content developers.
With truncated data access, users can access a narrow choice of information and services such as news, weather and stock quotes. This information can be displayed on a larger screen with the addition of some PC interconnect, such as a cable and a cradle, working as the dial modem for a laptop PC. This modem will run at the cellular data rate, which is 14.4 kilobits/second in, for example, a CDMAOne service, increasing to 28.8 kbits/s and 56 kbits/s using new compression technologies.
The CDMAOne cellular service is the one most frequently referred to as 2G (for second-generation) cellular. The higher-speed migration of a fundamentally similar system is referred to as 2.5G. Another 2.5G system is the extension of the European Global System for Mobile Communications (GSM) cellular standard with General Packet Radio Service, which supports WAP. This system employs packet-switching methods instead of the circuit-switching techniques used in traditional networks. Its major success in the cellular marketplace will likely be in Europe, where approximately 100 million users will be offered this wireless data service in the next year.
In Japan, the scene may have already been set by NTT DoCoMo's offering of a truncated service with its Internet Access Service, dubbed the i-mode phone, while its local competitors DDI and IDO are scrambling to offer a similar, code-division, multiple-access (CDMA)-based service. It is estimated that this region will account for one-third of wireless data users this year based on those or similar product offerings.
Starting in early 1999, the i-mode phone service captured a 15 percent share of the domestic Pacific digital market and is one of the fastest-growing services within Japan. It uses HDML for content access, since WAP's availability was limited when the service began.
The i-mode service is based on an additional packet communication network built on NTT's DoCoMo Pacific Digital Cellular infrastructure. The service's hardware consists of four major components: a cellular phone capable of voice and packet communication with a browser installed, a packet network, an i-mode server and information providers.
An i-mode phone is about the same size and weighs as much as a normal Japanese cellular phone, but with a larger LCD display. This cellular phone will carry voice communication and text messaging exchange, as well as allow e-mail and Web access. The Internet service portion of i-mode service consists of text mode only and will use a subset, or compact version of HTML, which will allow connection to most home pages. The typical content available to users includes services such as financial transactions, e-mail, entertainment and database searches.
The mobile phone will be enhanced this year so that it will be able to connect to a company intranet and include Java technologies. A recently announced joint Sun Microsystems-NTT operation offers the availability of Java-based Web pages on mobile phones. More services are being considered and offered and the key will be what content is available at what cost for the user. Also, the i-mode system will be linked to car navigation and position location.
Soon, 3G cellular wireless protocols are likely to be Internet-ready from the start, building on the present momentum from 2.5G. The new 3G services will first be available in Japan during 2001, with other regions of the world beginning field trials and planning service introductions.
For data, the 1X Radio Transfer Technology for CDMA-based protocols and the Enhanced Data Rate for Global Evolution for Time Division Multiple Access (TDMA)-based protocols are the key technologies to watch. Those systems have data rates in excess of 100 kbits/s, which make them very appropriate for handling wireless data efficiently, as well as profiles that will enable 2 Mbits/s for a stationary device. Since portability and connectivity are key for cellular phone users, this 2-Mbit/s data rate will be unacceptable unless the infrastructure can work.
The i-mode terminal's acceptance will facilitate new services such as multimedia. Since Web connectivity from a mobile terminal is desirable, as indicated by the success of i-mode in Japan, the next step is to make the experience similar to that gained when accessing the Web from a desktop PC. Color moving images and quality audio will be the next goal for OEMs. Two key technologies will play a part in this new development: display technology and compression standards for the transmission of images and sound.
Key role
Toshiba plays a key role in both of these areas. First, it creates small thin-film transistor LCD’s of polysilicon that are reflective and robust enough for such an application while providing good visual results. Second, the MPEG-4 industry standard is now used in any Toshiba 2.5G or 3G system while providing good visual results for the transmission of media.
The Moving Picture Experts Group (MPEG) is a working group of ISO/IEC whose charter is the development of international standards for compression, decompression, processing and coded representation of moving pictures, audio and their combination. Toshiba's MPEG-4 standard is aimed at small displays with low refresh rate, such as 15 frames per second, making it ideal for mobile multimedia applications.
The evolution of the cellular mobile terminal's baseband for 2.5G and 3G cellular phones has already been addressed in the industry for CDMA, GSM and TDMA standards. Those devices are made up of a microprocessor for running the phone, an embedded DSP core for vocoders and some specific hardware for other functions. Adding processing requirements for multimedia requires a leap in technology. Assessing the power budget for those functions in the baseband device quickly makes it obvious that the benefit of an external LSI under the baseband processor's control is the logical choice. Since not all terminals need to be Web-capable for some years to come, loading the baseband processor with this requirement may put an unnecessary cost penalty on an already cost-constrained component.
The Toshiba MPEG-4 solution offers two main components: the LSI and the software that resides as middleware on the protocol stack in a typical multimedia terminal. The standard cellular baseband links to the Toshiba MPEG-4 LSI via a custom interface.
The device contains three RISC cores that control video, audio and multiplexing, as well as an embedded dynamic random access memory that minimizes the device's power drain.
Minimizing power drain prevents the diversion of signals to external memory. Excessive use of power, or an increase in the established form factor, inhibits the functionality of Web browsing on a phone.
Therefore, low-power techniques must be employed as well as embedded memory, low-current RISC cores and cells and a low Vt CMOS technology, which contributes to low power in such an LSI.
In addition to the hardware, this solution includes some MPEG-4 middleware that resides on the customer's protocol stack and interfaces to the cell phone software stack through predefined APIs.
The hardware/software tradeoff has been optimized for the low-power requirements of a portable product and designed to interface between existing baseband processors from many vendors.
Two paths
Ideally, the baseband processor road map continues on its evolutionary path while multimedia services are supported by add-on components. This solution supports images and audio over an air link of 64 kbits/s and a frame refresh rate of 15 frames/s, which is the optimum level for good-quality audio and steady, nonblocky images.
As the cellular terminal's form factor undergoes some radical changes during this decade, it is clear that Internet access will be the next new feature added. The complete chain of events is in place to ensure this:
- the content development of e-commerce or e-entertainment;
- infrastructure changes enabling the efficient handling of data such as packet switching;
- WAP and its industry developments, and higher-speed radio links of either 2.5 or 3G. From this point the step to multimedia video and high-quality audio will be a small step for the infrastructure as well as a small step for the terminal builders.
eetimes.com
Copyright ® 2000 CMP Media Inc
techweb.com |
