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New tech breaks into network specs war

Posted: 18 Dec 2006 ?? ?Print Version ?Bookmark and Share

Keywords:wireless? ultrawideband? UWB? HD video? WirelessHD?

One of the most promising wireless technologies in the lab has jumped into one of the most hypercompetitive markets in electronics. Six top CE vendors formed the WirelessHD group in October to define 60GHz radios that could carry uncompressed high-definition (HD) video across the living room at a roaring 5Gbps.

The groupcomprising LG, Matsushita, NEC, Samsung, Sony and Toshibawill deliver a specification early next year for links reaching up to 10m. The nascent technology will have to compete with established wired links such as 1394 FireWire and HDMI, as well as 802.11n and multiple flavors of ultrawideband (UWB).

In its favor, the WirelessHD group has the backing of startup SiBeam Inc., founded by UC Berkeley researcher Bob Brodersen, a leading pioneer of CMOS radio.

The proposition
Bandwidth is the trump card for 60GHz radios, which will not be the smallest, cheapest or lowest-power options for the home network. The group has seized on the value proposition of carrying uncompressed HD video at resolutions of up to of 1,920 x 1,080 progressive scan, with latencies ranging from 5ms to 15ms.

WirelessHD chairman John Marshall said TVs, DVD players and other HD gear could actually provide better resolution, with less latency and cost, by using 60GHz radios rather than UWB. That's because the typical 480Mbps bandwidth of UWB requires recompressing packaged or broadcast video, forcing OEMs to put expensive encoders and more RAM into their systems, losing video content and adding latency in the process.

I have seen the difference between lossy twice-compressed content and HDMI uncompressed content, and my eyes aren't golden," said Marshall.

The WirelessHD group is developing a complete spec for 60GHz products that spans everything from the PHY to the application layer, though Marshall would not provide details about the work in progress. The spec is for "predominantly point-to-point" connections, but it does include a back channel running at less than 100Mbps, he said.

With a 10m maximum range and no penetration through walls, 60GHz radios have no immediate road map to becoming the much-desired whole-home net. The technology can be bridged to any existing home net, though the spec will not address bridging specifically.

The industry in general could deliver 60GHz radios in about a year that consume 5W or less and carry a small premium over wired links, SiBeam's Brodersen predicted. They are likely to be packaged in a 1-inch-square module built to accommodate a directional antenna array, he said.

The WirelessHD group faces a handful of business challenges for handling security, royalties, regulations and standards.

Berkeley researchers built waveguides onto CMOS, giving designs for a 60GHz mixer and amp greater predictability. Commercial implementations are expected next year.

Marshall said the 10GHz spec will reference a number of existing content-protection technologies, including Digital Transmission Content Protection (DTCP) and HDMI's High-bandwidth Digital Content Protection (HDCP). But Hollywood may want to see additional protections.

The WirelessHD group is still debating whether to charge royalties. It's a "big issue" that "requires significant discussion and consideration," Marshall said, adding that arguments can be made for both models.

On the regulatory front, 60GHz radios are "not bogged down with a lot of regulatory problems, like UWB is," said Bob Heile, chairman of the IEEE 802.15 Working Group on PANs and chairman of the Zigbee Alliance.

The WirelessHD group can use unlicensed spectrum in the 57-64GHz range in the United States, where transmit power up to 10W is permitted. In Europe and Japan, it will use the 59-66GHz bands.

In Europe, UWB is restricted to the 6-10GHz bands3GHz less than in the U.S. Developers must also keep UWB transmit power 20dB lower than in the U.S., a stricture that could limit bandwidth to 4Gbps. And they must listen for and avoid competing signals.

Although there are a handful of standards efforts afoot in high-speed wireless, none specifically addresses the home HD market. The IEEE 802.15.3c group is taking proposals for 60GHz radio technology standards, but that work is mainly focused on backbone communications, said Heile.

The WirelessHD group "is looking at a very targeted application" and thus is "likely to be able to move faster" than the IEEE process, said Heile, who commended the group for going its own way.

That said, neither WirelessHD nor a competing UWB approach called WirelessHDMI, promoted by Analog Devices Inc. and startup Tzero Technologies, has licensed the core HDMI technology now going into millions of systems a year. "We look forward to working with both efforts to make sure they are compatible with HDMI," said Leslie Chard, president of HDMI Licensing LLC.

The opposition
What's more, WirelessHD must show a path to multiple chip suppliers with interoperable products. That could take two years from when the group delivers its spec, said Stephen Wood, president of the WiMedia Alliance, which primarily promotes UWB technologies such as wireless USB but has been studying 60GHz radios.

Some of the big consumer companies in the WirelessHD group, according to Wood, will roll out camcorders and MP3 players using wireless USB but are not necessarily committed to 60GHz products.

There are plenty of trade-offs in the fragmented sector of consumer interconnects.

In addition to the Tzero/ADI initiative, Bluetooth backers aim to ride UWB to transfer and stream music and video at data rates up to 100Mbps. An initial Bluetooth-over-UWB spec is slated to emerge before June next year and be finalized with working prototypes available by the end of 2007, about the same time as the WirelessHD effort.

Among wired competitors, HDMI jumped from 5Gbps to 10Gbps with its ver 1.3 spec, released last July. OEMs can now deliver products supporting resolutions up to 1,440 progressive, frame rates up to 90Hz or color depth up to 48bits, said Chard.

Backers of 1394 have formed another alternative with the High-Definition Audio-Video Network Alliance (HANA), which aims to extend FireWire into a whole-home network running several hundred meters over various interconnects and carrying generally compressed video, said Jack Chaney, HANA chairman and director of the DMS Labs at Samsung. The HANA approach uses a variety of bridged technologies such as UWB and Ethernet.

The biggest challenge facing WirelessHD may simply be making the technology work as promised. "No one has done anything like this for phased arrays before at the level of integration and cost for consumer equipment they are talking about," said Larry Williams, director of business development for Ansoft Corp., which sells high-speed design software. "There will not be many companies able to achieve this in silicon."

One of the toughest nuts to crack will be delivering an adaptive, directional antenna array that can tolerate a living room where people may walk in front of its beam or move the systems around.

"It must automatically figure out the best beam paths between a transmitter and receiver, and adaptively change them when the path gets blocked," said Brodersen of SiBeam. And since the arrays are in TVs and DVD players, he said, "you can't require setup to be difficult."

- Rick Merritt
EE Times

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