Backers of this government-private sector effort, from Prime Minister Junichiro Koizumi on down, see e-Japan as the country's main chance of catching and then surpassing the United States and South Korea in broadband. But to get there from here, nagging storage and transmission issues have to be solved — and solved in a cost-effective way.

Engineers took advantage of this month's Ceatec 2002 show here to showcase their solutions to these thorny problems.

The e-Japan road map acknowledges a world in which high-definition video content gets funneled to those 20 million homes along with mobile network services. To capture all that dense data, companies are looking to optical storage for both its density and the speed at which subsystems should be able to shunt information back and forth. On the transmission side, wireless technologies, including those based on the emerging IEEE 802.11e standard, are being tapped.

Among the storage possibilities on view at Ceatec were entries from two camps promoting separate solutions for next-generation DVD. Toshiba Corp. used a 15-Gbyte single-layer disk to send data at 36 Mbits/second, in a system that uses a 405-nanometer blue-violet laser with a numerical aperture of 0.65. Toshiba and partner NEC Corp. in August proposed this scheme, tentatively called the Advanced Optical Disk system, to the DVD Forum as DVD's next turn. In the proposed specifications, disk capacity is defined as 30 Gbytes for a dual-layer ROM disk and 40 Gbytes for a dual-layer writable disk.

Meanwhile, backers of the rival Blu-ray Disk system — Hitachi, JVC, Matsushita, Pioneer, Philips, Sharp and Sony — demonstrated prototype recorders. The Blu-ray Disk currently supports only recording capability. But at the Makuhari show ground here, a variety of disks were proposed to enrich the Blu-ray family, including dual-layer recordable, read-only, write-once and micro disks. The companies did not disclose the timing of any introductions based on these prototypes.

Philips generated a fair amount of buzz by debuting a coin-size rewritable optical disk featuring 1 Gbyte of storage capacity, along with a miniaturized optical drive using its blue-laser technology. The prototype drive measures 50 x 36 x 7 mm; the optical disk, 30 mm in diameter, offers gigabyte storage capacity on a single side, single layer.

The Dutch giant insisted it is still just exploring this Small Form Factor Optical drive technology. However, by delivering the proof of concept in a working prototype, Philips strutted a readiness to exploit its lead in recordable DVD, created through its own DVD+RW and blue-laser technologies.

Matsushita showed a double-layer disk that a spokesman said can largely be built on a current-generation DVD production line. That's good news for manufacturers worried about the Blu-ray Disk's 0.1-mm cover layer on the recording layer, a structure that is expected to present difficulties in production. Matsushita has developed phase-change recording-layer material that does not change the transmissive ratio before and after recording. Using the material for the recording layer at the cover side, Matsushita was able to employ the same process of injection and evaporation that is used for DVD disk production today.

Almost transparent

Pioneer showed an almost transparent read-only disk with a 25-Gbyte capacity. To cope with the small pits that mark the Blu-ray Disk, Pioneer made the reflecting layer about 40 percent thinner than in the DVD-ROM disk. Pioneer, which led DVD-R and RW disk development, is now focusing on ROM-disk development.

For a write-once disk, disk giant TDK proposed a disk that uses non-organic recording material — an alloy of silicon and copper. "Organic materials that can be used with a blue laser are still in the research level, but our write-once disk with a non-organic recording layer has reached product level," said Hiroyasu Inoue, associate chief researcher at TDK's development center. Before recording, silicon and copper layers are stacked; when the disk is recorded, the layers melt and merge, which makes alteration impossible.

TDK also presented phase-change disk technology that makes it possible to record data on a Blue-ray Disk at 4x speed or faster. Inoue attributed the high-speed recording to an improvement in spin-coating technology to form a uniform recording layer, along with material optimization and highly heat-conductive layers that sandwich the recording layer.

TDK reported that it has verified recording operation at 144 Mbits/s, about four times the speed of the Blu-ray Disk (specified at 36 Mbits/s), and at 200 Mbits/s, with jitter of 7.5 percent and 10 percent, respectively.

Wireless transmission

How to deliver this mass of content is another challenge. If Ceatec is any indicator, wireless transmission is one solution much on the minds of vendors.

Sharp Corp. demonstrated high-definition (HD) image transmission using its prototype 5.2-GHz-band wireless video communication modules, which comply with the IEEE 802.11e draft. The 802.11e specifications define a maximum 54-Mbit/s transmission, but in the demonstration, one-channel HD content and LAN data traveled at 36 Mbits/s. The 802.1e spec, said a Sharp spokesman, "is designed to secure channels for video and audio." The company is "waiting for the 802.1e format to be finalized," he said.

Matsushita, for its part, demonstrated wireless HD transmission based on IEEE 802.11a. The prototype receiver has a wave-tracing antenna that sets the optimum angle to receive the radio wave.

As the ultimate in HD transmission, Victor Co. of Japan Ltd. (JVC) demonstrated non-compressed baseband wireless transmission at 1.25 Gbits/s aimed at home use. "This optical-transmission [scheme] transmits pixel data from a tuner to a display without deterioration," said a JVC spokesman. The infrared laser satisfies eye-save requirements, as defined in IEC 60825-1 for home use. The transmission distance is about 10 meters.

Another way to tackle the camel-in-the-needle's-eye challenge is by data compression. Mitsubishi Electric managed to compress HD video to 9.8 Mbits/s, a bit rate that would make it possible to store about two hours of HD content in a current-generation DVD disk. In the demonstration, Mitsubishi engineers used a dual-layer DVD-RW disk, which stores HD content that's compressed off line.

The high compression was realized by an autonomous algorithm that sets optimized compression parameters depending on the complexity of the images. "Encoding takes time, but encoded data is compliant with MPEG-2, so a conventional DVD decoder can decode the signal," said a Mitsubishi spokesman.

Terrestrial digital broadcasting, a major part of which will be HD programs, is slated to begin next year in Japan. Together with the broadcasting, the HD infrastructure appears to be getting ready on both the home front and the network side.

— Additional reporting by Junko Yoshida.