Wireless video picks up speed

As much as we would all prefer a wire-free environment, the big sticking point with virtually all the current wireless technologies is performance, or rather a lack of it. Wires remain the only practical approach where high throughput rates are required. However, that could soon change as all sorts of developments are in the pipeline, including an interesting new twist on an old wireless theme offering rates as high as 1.5Gbit/s.

Called Wireless High Definition Interface (WHDI) the new technology is primarily designed to deliver uncompressed data to flat panel televisions, but can equally be used to connect video projectors, DVD recorders and other multimedia devices.

It operates in the little-used 5GHz band, just like the similarly much neglected 802.11a wireless LAN technology. The first public demos at the recent Consumer Electronics Show (CES) in Las Vegas used commercial 802.11a chips to which were added the extra antennae of multiple-input, multiple-output (Mimo) technology, much like that now routinely used to beef up 802.11g networks.

On top of this, chip vendor Amimon has added its own encoding expertise. Not so much to cut the high error rates prevalent in all over-the-air transmissions, but to minimise their impact. It distributes the errors to cause only minor, transient colour shifts not normally noticeable to the eye.

The result is the ability to wirelessly transmit high-definition video signals, including the 720p and 1080i digital TV formats popular with most vendors, and latency of less than a millisecond. Moreover, unlike alternatives such as Ultra Wideband (UWB), there’s no need for any kind of data compression, which otherwise could add extra latency and yet more errors. Of course the fact that WHDI is based on 802.11a means no compatibility with other, more popular, Wi-Fi standards, but that’s not really a problem. Indeed it could be seen as a plus, making WHDI less prone to interference from other wireless sources.

The developers aren’t really concerned with backwards compatibility anyway, they simply want to match the speed and quality of current High Definition Multimedia Interface (HDMI), Digital Video Interface (DVI) and component video systems used to deliver uncompressed digital video signals over cable. And that they seemed to have achieved at the CES demonstration, where the company showed two displays linked to the same HDTV source. One of these used a cable, while the other was connected wirelessly – with no perceptible difference.

Of course that was just a demo and the device at CES was a long way off a final product. A lot of work is required to minimise both the price and physical size of the proposed HDMI chip. Amimon will also need to convince other vendors to use its technology instead of wireless alternatives such as UWB or 802.11n.

That said, initial samples of the Amimon wireless modem are expected in the second half of 2006. Plus there has been lots of interest in the technology, which could see it added to TVs, projectors and other multimedia devices very soon indeed.