Battling for high definition wireless to run multiple television channels

Paul Boughton
Groups around the world are squaring up to provide gigabit data over wireless links in the home. Nick Flaherty reports.

Companies around the world are running to provide high bandwidth wireless links to run multiple TV channels or high definition TV either between equipment or around the home.

But there are several ways of providing gigabit wireless links, from the 5GHz up to the 60GHz frequency bands, and the developments are becoming stuck in many different standards groups.

Part of the problem is the move to high definition TV (HDTV). The challenge is not just to link a set top box to the TV wirelessly, replacing the current HDMI cable, but to be able to support HDTV signals up to the highest 1080p format, which for an uncompressed stream can require up to 3Gbit/s of data. This is a major challenge for wireless systems.

The aim is then to extend this capability around the house with equipment at consumer electronics prices, which means there is the need for some kind of standardisation to get a large enough market to reach those lower prices.

Mesh networking

A new start-up, Quantenna Communications, is aiming to provide up to 1Gbit/s through traditional technology. With a combination of MIMO (multiple in, multiple out, using the 802.11n standard), beam forming antennas, dual bands (using the 2.4GHz band for control signals and the 5Ghz band for video transmission) and mesh networking. The mesh networking algorithms embedded in the chipset allows a small unit to be plugged in around the home to provide more coverage and avoid dead spots.

"Our unique combination of cutting-edge 4x4 MIMO and Tx beamforming on the smallest footprint positions Quantenna in the forefront of the highly competitive Wi-Fi chip market," said Dr Behrooz Rezvani, Quantenna's founder and CEO. "Through years of development and careful consideration of the challenges that have previously impeded ultra reliable wireless bandwidth, we can now enable our customers to meet the most demanding consumer challenges today, which is guaranteeing bandwidth."

Solving problems

But in recent months a group of TV and equipment makers has also coalesced around a technology developed in Israel, launching the Wireless Home Digital Interface. While some large companies are involved, other companies large and small have been working on solving these problems for years and are not going to let this go easily.

This brings together many of the leader equipment makers - Hitachi, Motorola, Samsung, Sharp and Sony - around one technology with a new approach, a new video modem that can handle uncompressed HD video in the unlicensed 5GHz developed by Amimon in Israel.

This video modem prioritises different parts of the uncompressed video stream into different layers, sending the most significant layers over the most robust link with the most error correction and so with the most overhead, but leaving the less significant part so the video with less error correction, and in this way fitting the content into the data rats supported by existing 5GHz technology.

Uncompressed video

The key is that is can handle uncompressed video from the set top box, games console or Blu ray player to the TV, but also send this around the home, eliminating the need for the compressed distribution network.

"To have a viable wireless HD communication standard it needs to support uncompressed video, not compressed," said Noam Geri, vice president of marketing and co-founder at Amimon. This is because copy protection,electronic programme guides and overlays tend to be added onto the video stream and so a compressed stream doesn't have the same quality,he says. "The consumer electronics manufacturers will not support something that degrades the performance or quality of the image, so they want uncompressed video," he said.

But these are not the only option. The Wireless HD consortium, formed at the end of 2006, also brought together LG Electronics, Matsushita Electric (Panasonic), NEC, Samsung, Sony and Toshiba around a 60GHz technology developed by SiBeam. This has now evolved into a specification for 4Gbit/s data rates at 60GHz - plenty for HDTV - and the group has 40 companies, mainly Japanese, signed up.

Around the same time, Philips was proposing a variant of the 802.11n standard technology developed by Metalink for its solution, and there are also companies such as Tzero and Pulse-Link working to provide technology for a wireless version of HDMI and extending that out into the home in different ways and fighting each other over patents in the courts.

Wire technology

Tzero has its technology shipping in wireless HDMI devices from Hitachi, while PulseLink has had its wireless technology adopted as part of the next generation of 1394 wire technology to use the same protocols across both wireless and wires.

The 1394 Trade Association has developed a "no new wires" home networking standard that provides for data rates up to 800 Megabits per second, enabling a high-speed multimedia home network that can work with all 1394 and IP-enabled devices over coax wiring to move compressed data around the home either wirelessly or, using the same protocols, over existing 1394 Firewire links.

The MAC/PHY layers specified in the new standard are available now in a new chipset from Pulse~Link using its CWave UWB technology that includes guaranteed Quality of Service (QoS) and data rate performance.

"After more than two years of close collaboration with the 1394 Trade Association and its member companies, Pulse-Link is proud to be a part of the first International standard to incorporate UWB over coax," said John Santhoff, co-founder and Chief Technology Officer. "Pulse-Link's contribution of its substantial Intellectual Property (IP) into this standard opens a true whole-home HD networking experience of 1394 and IP content to consumers globally."

Wireless HDMI

Pulse-Link is also targeting the HDMI market, having demonstrated a wireless HDMI solution using Cwave two years ago. This is now coming to market as the cost of the components, notably a JPEG2000 codec from Analog Devices, is now cost effective enough, says Santhoff.

This means there could be a single protocol from the TV through the entire network, as the new standard also serves as the basis for the whole-home networking backbone defined by the High-Definition Audio-Video Network Alliance (HANA).

Many of the guidelines for development of HANA-enabled products will be based on the new 1394 Over Coax Specification.

Control protocols

Geri at Amimon points to the technology lead that WHDI at 5GHz has over WiHD at 60GHz, even though it is two years behind with the specification. The group expects a specification by the end of this year with silicon in 2009 supporting 1080p and the control protocols, moving to a single chip in 2010.

Pre-compliant WHDI equipment will start shipping by the end of the year, with fully compliant systems in 2009, he says. "5GHz has a 15 year headstart over 60GHz on cost, and we can do WHDI in a single (CMOS) chip," he said.

But this 60GHz 'millimetre wave' technology has other applications as well, from imaging with cameras that can see through clothing, as well as opportunities for equipment makers to get bandwidth of over 1Gbit/s for metro area wireless networks.

But there is some big competition. IBM started targetting 60GHz applications in 2003 for the higher bandwidth, partly funded by the US space agency Nasa and the US research agency DARPA.

In 2004 it demonstrated the world's first silicon-based active mixers and low-noise amplifiers at 60 and 77 GHz, and also demonstrated other mmWave radio building blocks, including power amplifiers and voltage-controlled oscillators.

Low-cost pacakaging

In early 2006, it developed a fully integrated 60-GHz receiver and transmitter chipset, which includes all of the RF and analogue portions of the radio, as well as the low-cost packaging and antennas that are needed.

These packaged chips have been demonstrated at 630 Mbps throughput at a maximum range of 10 metres with a complexity is approaching that typically seen in silicon at much lower frequencies.

But Geri at Amimon points to the problems of 60GHz with penetration, as bodies moving around the room significantly change the performance of a 60GHz system leaving it as a short distance solution rather than for the whole home. WHDI adds control protocols so that a DVD player downstairs can be controlled directly while watching the output upstairs.

Geri plays down the health risks of the competing technologies. "60GHz is one of the resonant frequencies of water and that doesn't sound like a good thing, and because of the poor propagation it has to be transmitted at a higher power.

Of all the wireless technologies, 5GHz is probably the safest, it's much lower power than 60GHz or cellular phones."

The battle to provide high speed wireless links around the home continues, and there is a complex balance of standards, innovation, technologies and cost that companies have to achieve.

From the innovation of existing 5GHz technology through Quantenna and Amimon to provide 1Gbit/s at low cost through to the companies opening up the 60Ghz band to new applications and bringing the component and equipment costs down there, there is all still to play for.