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Mobile TV may not yet be ready for prime time

Posted: 16 Mar 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Junko Yoshida? receiver? mobile TV? Mobile and Portable DVB-T Radio Access Interface? MBRAI?

Even before the opening bell sounded at last month's 3GSM World Congress in Barcelona, Spain, technology companies were furiously pitching mobile TV as the way to boost the replacement rate of cellphones and prop up the slip-sliding price of wireless services.

But receiver suppliers face a number of challenges in bringing mobile TV to the real world. Beyond improving receiver sensitivity and gauging consumer preferences in basic trials lies another task universally cited as critical!meeting the Mobile and Portable DVB-T Radio Access Interface (MBRAI). This DVB-H radio specification, defined by the DVB Project, spells out minimum performance conditions under which the radio must operate.

A number of mobile-TV trials are already under way from the United States and Australia to France, Spain, the U.K., Germany, the Netherlands, Finland and Switzerland!just based on DVB-H, one of several competing mobile-TV standards.

What are service providers learning in those trials? So far, the only results leaked suggest that consumers seem to like TV on their mobile handsets and they might like it enough to pay for it. Maybe.

Trials to date have typically used networks that are not dense, since operators tend not to sweat full coverage for test services. But this is a concern for some engineers who wonder whether the first-generation DVB-H receivers available today will be able to deliver promises on performance when used in a real-world environment. "In the U.S., with just a few transmitters at 1.4GHz and tiny receiver antennas, coverage has to be a concern," said Allen Nogee, principal wireless-technology analyst at In-Stat. "And with DTV, it either works or it doesn't."

Receiver performance
Bringing broadband TV into the narrowband mobile-phone world is no walk in the park, said James Fontaine, president and CEO at Microtune Inc., a DTV silicon and systems supplier. The real-world environment is bombarded with strong signals from adjacent channels, multipath interference and radios, radios everywhere, including GPS and emergency services.

Network operators, while keeping most of their trial results to themselves, have been conspicuously mum about receiver performance. That, however, doesn't mean there are no glitches. Any information about receiver performance could reveal proprietary issues concerning the necessary cost in adding more base stations and repeaters.

Yannick Levy, chief executive officer of DVB-H chipmaker DiBcom, noted that better!more sensitive!receivers are a key to stretching networks for less cost. "It is especially important in the beginning, as it affects the initial network infrastructure," he said. Claiming that the company's new DVB-H tuner/receiver offers better sensitivity at 3dB than the "typical receiver," Levy said that, theoretically, "it means network operators can increase the coverage area by approximately 50 percent."

In a real-world environment, users may see a noticeable performance difference among various mobile-TV handset models. However, network operators are initially focusing on getting basic mobile TVs to work and figuring out what content to broadcast. The performance issue may not rise to the forefront until 2007 or even 2008, when the commercial mobile-TV market actually exists.

Challenging spec
Meanwhile, Christophe Cugge, director of marketing and product development for DVB-H mobile TV at Freescale Semiconductor Inc., described the MBRAI spec as "challenging." It defines a series of test conditions across multiple radio performance criteria, including sensitivity, adjacent-channel performance and carrier-to-noise ratio. These conditions determine whether the product meets the minimum DVB-H standard.

Compliance to a full MBRAI spec, however, is hard to measure. Phil Spruce, marketing manager for handhelds at Microtune, said that most chip companies, handset manufacturers and cellular network operators!which typically are not in the TV business!don't even know "how to re-create all the environment measures specified in the MBRAI." Without knowing how to test, how can they claim that a product meets the MBRAI spec?

This gap explains, in part, why many industry analysts see those in the DTV business!Microtune, Broadcom, ATI Technologies and Philips!as potential winners in the DVB-H receiver market in the long run.

Real-world issues
Microtune, for one, has a lab in Dresden, Germany, formerly owned by Temic Telefunken, a supplier of RF system solutions to the cable, PC and automotive industries. The Temic Telefunken link is why Microtune says it was able to meet the complex matrix of conditions specified in MBRAI through testing its DVB-H tuner at the Dresden lab.

Freescale, on the other hand, believes that testing all MBRAI specs could be overkill. Rather, "we have picked the worst-case scenario of the MBRAI spec, notably 64QAM modulation," to test the performance of Freescale's tuner," Cugge said. While nobody thinks 64QAM is practical for receiving DTV signals on a cellphone, "nonetheless, it's in the MBRAI spec and we need to meet that," he added.

Microtune points out that current trials test performance based on a fraction of the MBRAI spec. Moreover, because MBRAI specs are based on theoretical concepts and a theoretical reception environment, "they don't cover real-world issues," Spruce said.

That raises another concern for Alon Ironi, CEO at Siano Mobile Silicon: "There is no real gain from overperformance," he said, and it "always has its penalty in some other parameters," such as price, power and cost.

- Junko Yoshida
EE Times

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