Broadcasters around the globe are getting ready to switch on mobile TV as the next big thing for cell phones, driving a shift to handsets with color VGA displays greater than 2 inches in size. The broadcast debut hands engineers hefty challenges reining in cost, board space and, especially, power consumption for those big-screen phones.
The good news is that most of the pieces of the mobile-TV puzzle are on their way to market, so designers can start building first-generation handsets. Options are on the horizon for new low-power display technologies that could help craft even better products in the next year or two.
The design challenge comes as some reviewers criticize Apple Computer Inc.'s Video iPod for delivering less than three hours of battery life to users who want to watch the latest rock videos on the digital music players. "Unfortunately, battery technology is not getting good enough fast enough, so we may be headed for a brick wall," said Joel Pollack, chief executive officer of Clairvoyante Inc. (Cupertino, Calif.), which enables lower-power display modules to help avoid that crash.
Alon Ironi is more optimistic. "The integration of camera phones was more difficult [than mobile TV], because it had more impact on the kernel and real-time threads in the baseband that were problematic," said the chief executive of Siano Mobile Silicon (Netanya, Israel), a startup providing integrated tuner/demodulators for mobile TV. "A lot of the top-tier companies are starting their [mobile-TV handset] designs now for the second half of 2006." Next year, said Ironi, "is mainly about pilots; 2007 will be the real ramp of the market."
Nokia Corp. put an early stake in the ground this month when it announced its N92 handset, geared for frequencies used in Europe for the Digital Video Broadcast-Handheld (DVB-H) standard. The handset's 2.8-inch display twists, so that the device can sit on a table like a portable DVD player, act like a handheld video camera with LCD viewfinder or take the familiar form of a clamshell phone.
The phone is specified to deliver four hours of TV watch time using a 1,500-milliwatt lithium-polymer battery. However, Nokia gave scant details about the internals of the 600-euro phone, which will not ship until about next June.
A Nokia spokesman would not comment on how broadly or quickly the company will roll out mobile-TV capabilities across its product line.
"Having this kind of complexity in a very small footprint creates an electrical environment that is very challenging," said Juha Lipiainen, a director for multimedia strategy and business development at Nokia. "The issue is how to economically encapsulate the mobile-TV capability in hardware."
Indeed, mobile TV drives new hardware requirements throughout the handset, starting with tuner/demodulator chips an arena where seven or more suppliers have already emerged.
Siano appears to have an early edge, because it offers a slightly lower power consumption and broader spectrum support than the rest of the pack. The SMS1000 two-chip set consumes 25 mW average and 225 mW peak, and is sampling now. Production is planned by June.
The Siano chip set supports four mobile-TV spectrum bands. It handles the standard 450- to 860-MHz and 1,660- to 1,690-MHz bands for DVB-H in Europe and the United States, respectively. It can also tune in the 170- to 250-MHz bands for the Terrestrial Digital Mobile Broadcasting standard that will be used in Korea and parts of Europe, as well as the 1,450- to 1,490-MHz band the DVB-H group may endorse in January as a way to open up much-needed mobile-TV spectrum in Europe.
Siano gets its edge from using zero-IF conversion from RF analog to baseband, saving die area and power, and opening room for broader spectrum coverage. The startup claims it has proprietary techniques for handling the side effect of the zero-IF technique: greater baseband noise.
Using a two-chip approach is the best route to power savings, said Ironi. "The requirements of the RF in the tuner and digital in the demodulator are quite different. If you enforce the requirements of one over the other, you don't get optimized power consumption," he said. Siano would not reveal its die size or process technology, but did say its parts will cost less than $10 when volumes hit in 2007. At least one other vendor also uses a zero-IF approach: startup Athena Semiconductors Inc., acquired for $21.6 million by Broadcom Corp. in October.
The Hollywood DVB-H single-chip tuner/demodulator from Texas Instruments Inc., meanwhile, consumes 30 mW average and 300 mW peak in a die measuring less than 1 cm2. However, those specs are based on estimates of a part that has yet to sample. The chip is not expected to ship until later next year, aiming at handsets shipping in 2007.
The first Hollywood product supports the standard DVB-H band in the United States and European frequencies up to 750 MHz. Future Hollywood products will support up to 860 MHz and perhaps the 1,400-MHz band that's being opened up.
Among major chip vendors, Philips and Freescale also supply DVB-H tuners and demodulators. Philips offers separate integrated parts for the standard U.S. and European frequencies that consume 45 mW average and 300 mW peak. They come in a 15 x 26-mm module that includes all necessary discrete parts. "We expect by mid-2006 to have single tuners that support both [DVB-H] bands," said Joost Verhoeks, a product-marketing manager for Philips Semiconductors.
Freescale Semiconductor Inc. in early August taped out a tuner for Europe's 470- to 860-MHz DVB-H band. A version for the U.S. 1,600-MHz band is going through a design change and won't be in production until early next year. Both fit into a 49-mm2 package and are designed to be paired with a demod chip from startup DiBcom (Palaiseau, France).
Once the TV signal is captured and converted to digital, it needs to be decompressed. Some engineers say that will best be handled in software on the baseband or applications processor, while others insist a hardware decode block is the best bet, given that the signal is likely based on the muscular H.264 MPEG-4 standard. "The people that do TV well will put in dedicated hardware," said Kevin Gillett, director of strategic platforms at Epson's R&D center in Richmond, British Columbia. "We are even seeing that happening in audio."
Power consumption goes down by a factor of as much as six for cell phones that include a hardware MP3 decode block, vs. using software decode on an ARM7. Similarly, a 200-MHz video decode block at less than $10 could halve power consumption compared with doing the work on a 400-MHz ARM9. Some designers will take a half-step by designing a dedicated block specifically for motion compensation the biggest power draw. Such a block might add just $2 to a cell phone's bill of materials. "There will be a wide variety of parts and approaches," Gillett said. The Epson group is developing MPEG accelerators for Japan's mobile-TV standard now, and may turn to DVB-H decoders next.
TI handles video decode on its Omap processor. Philips offers both hardware and software options. "In the end, it will be a software codec assisted by some hardware blocks," said Verhoeks of Philips.
Displays tackle power
The display and its power-hungry backlight represent the biggest power hurdles in mobile TV. A 2.2-inch thin-film transistor (TFT) LCD at quarter-VGA resolution consumes just 12 mW, but its backlight requires a whopping 216 mW and even more for VGA screens. Such next-generation mobile-TV screens could require five to 10 LEDs to deliver the required brightness of 150 to 200 nits (a measure of brightness based on candelas/meter2).
"Improving display quality without driving up power consumption is the big issue, and brightness is the core of that," said Vinita Jakhanwal, principal analyst for mobile displays at market watcher iSuppli Corp. (El Segundo, Calif.).
The move to brighter LEDs may reduce the number of those devices needed. Emerging display technologies also hold out hope. Low-temperature polysilicon LCDs, for example, provide higher resolutions without compromising brightness. Organic-LED displays don't use backlights at all, but the active-matrix versions of OLEDs needed to obtain the picture quality for mobile TV have yet to demonstrate the low costs, high yields and long lifetimes required for volume markets.
Field-sequential displays use colored (red, green and blue) light rather than the white LEDs, with their brightness-sapping color filters, of traditional LCDs. However, so far commercial field-sequential displays have yet to find market success.
Among other options, startup Clairvoyante has developed a novel technology that could reduce power consumption in traditional TFT LCDs, and startup Iridigm Display acquired by Qualcomm in September 2004 has a display based on microelectromechanical systems that does not require a backlight.
Whatever options win out, the transition is on to large, color high-resolution cell phone displays. "The shift to color was driven by the camera phone, and the shift to VGA resolution will be driven by broadcast TV, video and Web browsing," said Jakhanwal of iSuppli. She estimates that 98 percent of phones will sport color by 2009.
By 2007, iSuppli predicts, phones with 2- to 2.5-inch displays will represent as much as 34 percent of the market. Most OEMs will deliver their first mobile-TV handsets with 2- to 2.5-inch VGA screens, according to iSuppli. "Consumer expectations for mobile-TV viewing are pretty much the same as in the living room," Jakhanwal said.