PARIS -- Satellite-delivered commercial digital multimedia broadcast (DMB) services in South Korea and Japan have produced sharply contrasting results since their introduction in mid-2005. Program managers say the different results are partly due to regulations on cell-phone towers and partly due to the industrial partnerships formed in each nation.

The early results -- a success in South Korea, a struggle in Japan -- have fueled debate in the United States, Europe, China and elsewhere about which model is most relevant for other regions that are considering introducing the same kind of system.

The Korean and Japanese services both use the MBSat-1 S-band satellite built by Space Systems/Loral and launched in March 2004. The satellite features a 12-meter-diameter antenna that is used to deliver television and radio programming to mobile telephones and other portable devices.

To ensure coverage where the satellite signal is blocked, thousands of signal boosters are deployed on cell-phone towers and other locations. The resulting system is one in which most users are more often linked to the terrestrial network through these ground repeaters than they are directly to the satellite.

Similar projects for broadcasting and two-way Internet links are being planned in the United States, which has L- and S-band systems under construction; and in China where Loral is building a satellite for U.S. direct-television broadcaster EchoStar on behalf of the Chinese government. Europe also is weighing a similar investment.

In South Korea, TU Media leads a consortium of companies that includes television broadcasters and cellular-network operator SK Telecom. They report signing up 750,000 subscribers in the 16 months since the commercial start-up of the service in May 2005.

Heetae Shin, manager of global business development at TU Media, said the company is on track to surpass 1 million subscribers this year and 2.5 million subscribers by early 2008.

"We are a little behind our original plan and we had some start-up difficulties," Shin said in a Sept. 28 interview. "But customer satisfaction is good, and long term we hope for 6.6 million subscribers. Obviously there are some assumptions in this forecast regarding handset prices."

The cellular phones and other pocket devices equipped to receive TU Media's television broadcasts carry an average retail price of $700. Recent models have been priced at between $300 and $800, depending on features, Shin said. The service is billed at a rate of $13 per month.

In Japan, Mobile Broadcasting Corp. manages the DMB service and has confronted issues that have made a repeat of the Korean success story impossible up to now, according to Yoshitake Yamaguchi, the company's acting managing director.

Yamaguchi said Sept. 28 that the company does not publish subscriber numbers but conceded that the market reception "is still less than our previous projections." An industry official said estimates are that paying subscribers number fewer than 25,000.

Yamaguchi said Mobile Broadcasting Corp. thinks that its cash-flow, break-even point would be achieved with a subscriber base of 1 million to 2 million users. "To reach that point, [the company] must reach the 100,000-subscriber point as soon as possible, " he said.

NTT DoCoMo this spring began deliveries of the Moba-HO! DMB terminal, and Toyota has modified its in-car navigation system for Moba-HO! and began offering it as a dealer option in May, Yamaguchi said. Mobile Broadcasting Corp., he said, is focusing on the automobile market for its services, but Japan's ANA airline is offering Moba-HO! service on commercial flights beginning in 2007, according to Mobile Broadcasting Corp.

Shin and Yamaguchi agreed that differing regulations in Korea and Japan relating to cellular networks partly explain the contrasting results.

Shin said Japanese regulations limit cell-tower power output to 1 watt -- which makes in-building penetration problematic. In Korea, however, terrestrial repeaters are able to provide power at levels ranging between 1 and 60 watts, depending on their location.

TU Media and its partners have installed 8,500 of these signal boosters so far, providing a 95 percent signal reliability to customers. It's not enough, he agreed, which is why more towers are being deployed to raise signal reliability closer to 99 percent.

The strong link with SK Telecom, which is TU Media's largest shareholder, also has helped with the adaptation of mobile devices for DMB.

TU Media customer surveys have found that 65 percent of them use the service for video, and 35 percent for the radio programming also offered. Nearly three-quarters of the users are between 20 and 40 years old. Shin said users under 19 are only 4 percent of the market in part because of the continued high cost of the handsets.