DVB-T edges out DVB-H in mobile TV

What would happen if a specification designed to unify an emerging market became obsolete just as the market jelled?

For DVB-H, rushed into development in 2004 to accommodate the low-power requirements of mobile television, the question may not be hypothetical.

While the mobile-TV market in the West has developed at a snail's pace, IC process technology has advanced so rapidly that DVB-T, a terrestrial DTV standard that had been thought too power-hungry for mobile TV, can now easily deliver TV broadcast to battery-operated portable devices. In the view of some, that may negate the need for DVB-H.

The prospect that DVB-T may eclipse the handheld-specific variant for bringing mobile TV to portable devices—though not quite yet to cellphones—has some DVB-H chip vendors repurposing their products and shifting their targets for end-system and geographical markets.

A case in point is Freescale Semiconductor Inc., which had thrown its weight behind DVB-H, and is now pitching a low-power DVB-T tuner for portable media players.

Likewise, DiBcom, a leading DVB-H demodulation chipmaker, has cultivated a volume market, but not for DVB-H on cellphones. Rather, the company has built a business in DVB-T and DVB-T/DVB-H combo solutions for automotive and notebook PCs.

Vendors are also shifting geographical focus for their mobile-TV products.

Analog Devices Inc., which has yet to achieve a sizable DVB-H deployment globally, is leveraging a demodulator developed for DVB-H to target China's GB-2006 terrestrial DTV standard (formerly called DMB-T/H).

South Korea, Japan and China are "the three largest mobile-TV markets today," said David Robertson, product line director for ADI's high-speed converter group. The company is focusing on China and has opened a joint lab with Legend Silicon for developing GB-2006 mobile solutions, Robertson said.

Microtune Inc. is also pursuing a multistandard strategy for mobile TV, focusing on DVB-H and South Korea's T-DMB standard. It has scored a design win for a DVB-H tuner in LG handsets sold in Italy, and it considers China's mobile-TV market "a hot area," said Phil Spruce, mobile-TV product-marketing manager. But Spruce added that the final verdict on China's mobile-TV standard is "still not concrete."

Rethinking standards
Process advancements are driving the rethinking of DTV standards. DiBcom CEO Yannick Levy said he had anticipated the current dilemma when the DVB group launched DVB-H in 2004. Levy started his company in 2000 to develop a DVB-T demodulator equipped with diversity implementations and Doppler effect compensations. In his view, DiBcom had already solved the DVB-T's mobility issues, and he was confident Moore's Law would reduce DVB-T's power appetite to palatable levels.

The DVB Group, however, was convinced that DVB-T would falter for mobile apps and thus pursued DVB-H. The group achieved the handheld spec by integrating such techniques as time slicing and additional forward error correction.

Three years ago, the combination of OFDM baseband processor, built on a 0.18?m process, and a canned RF tuner for DVB-T consumed 1.5W, according to DiBcom's Levy. Today, the pairing of a DVB-T silicon tuner and an OFDM demodulator built on a 90nm process consumes only 350mW.

Although the time-slicing feature of DVB-H can cut its power drain to 30-40mW—a tenth of what DVB-T can offer today—DVB-T's 350mW "isn't that bad," said Levy. South Korea's widely deployed T-DMB consumes 250mW.

Potential allure

Another potential allure of DVB-T—indeed, of terrestrial DTV standards in general—is its free-over-the-air content. "If there is stuff to watch, there is a better chance that consumers will buy mobile-TV handsets. That means we can sell more chips into handsets," said ADI's Robertson.

In South Korea's booming mobile-TV market, terrestrial mobile-TV content is available free. Three of the six T-DMB service providers in Korea are subsidiaries of free-to-air terrestrial DTV broadcasters (broadcasts are based on the Advanced Television Systems Committee standard).

Mobile-TV content is also free in Japan. Japan has embraced a simulcast model, ISDB-T, under which terrestrial DTV broadcast transmits QVGA signals for mobile-TV reception in addition to its main broadcast in SD and HD signals.

U.K., Germany and France are among the European countries in the process of rolling out DVB-T-based free-to-air DTV. But none thus far employs DVB-T for mobile broadcast.

The U.S. is currently the most fragmented mobile-TV battleground, with several service providers—armed with different technologies and infrastructure—fighting over turf.

One potential allure of DVB-T is its free-over-the-air content.

Unclear route
It remains unclear whether any free-to-air broadcasters are willing to invest further in network infrastructure for mobile TV. While starting with DVB-T and gradually phasing in DVB-H is a possible scenario, "I am not seeing that yet," said Levy.

DVB-H stands a better chance of wide deployment for mobile TV simply because it is optimized for mobility, said Yoram Solomon, senior director of strategic marketing and industry relations for Texas Instruments Inc.'s mobile connectivity solutions group.

Solomon also suggested that DVB-H and DVB-T, promoted by the same DVB group, have too much in common to be considered competing technologies.

- Junko Yoshida and Dylan McGrath
EE Times