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The Wireless Home Digital Interface (WHDI) group hasn't really been on my radar screen. I've done only one news item on it, which was the announcement of the release of its 1.0 spec back in December.

I think WHDI's off-my-radar status is because it uses 5 GHz band technology. Once 5 GHz Ultrawideband (UWB) technology acquired the stench of death due to Wireless USB's failure, I lost interest in expensive 5 GHz-based HDMI adapter sets, no matter which technology they used.

But as Sibeam is to WirelessHD, so is chipmaker Amimon to WHDI. And the technology they use is definitely not UWB. Amimon says their technology supports delivery of "equivalent video data rates" of up to 3 Gbps (for uncompressed 1080p) in a 40MHz channel and rates up to 1.5 Gbps (for uncompressed 1080i and 720p) in a single 20MHz channel, in the 5 GHz band.

Folks in the HD transmission game love to talk about handling "uncompressed" streams, because the use of compression implies a sacrifice in image quality. Lack of compression is also a primary differentiator of 60 GHz-based technologies, which can deliver higher real application-level bandwidth.

But when the Amimon technical guru in the demo area heard my skepticism about WHDI's uncompressed claims, he launched into a mini-tutorial on how it was possible. I don't claim to be an expert on HD transmission. But the explanation sure sounded like there was some sort of heavy pre and post transmission processing involved in WHDI. So while it may not be compression, there is a lot of bit-twiddling involved to achieve that 1.5 to 3 Gbps for HD streams.

No matter. The demo suite had multiple rooms, demonstrating different WHDI applications. There was a data transfer demo to an iTouch that had a large reference-design looking adapter strapped to it and a video streaming to a HDTV with WHDI adapter built in.

Another room had a side-by-side comparison demo of an HD video streaming via WHDI and HDMI cable, so that you could play find-the-cable. And the big room had a multi-device demo where they could demonstrate "follow-me" capability from one STB to another (pause video on one TV and resume on another).

A rep. for a competing technology characterized WHDI as an HDMI replacement technology trying to reposition itself as a "whole home" technology. I think "whole home" is an optimistic positioning for a technology whose range is spec'd as "100 feet, through walls". I should also note that none of the demos that I saw included WHDI signals traveling across even a single room wall.

But whether it's for HDMI replacement or whole-home distribution, I suspect that WHDI may have its work cut out for it to win mind-share over its 60 GHz based competition. However, WHDI's weakness is also its strength, since 5 GHz signals can get through media cabinet doors, while 60 GHz signals cannot and this may increase its spousal-approval index.

The big news in WHDI's favor at CES was Amimon's announcement that LG is coming out with HD TV's and accessories using Amimon's second generation WHDI chipset. The WHDI folks characterized this as LG throwing out WirelessHD, which LG included in some of its sets last year. But I think it's more a case of LG, like all other CE vendors, continuing to spread its bets among competing technologies.

WHDI certainly doesn't have a lead over WirelessHD in terms of price. HDMI replacement adapter pairs are still up around $600 or so, although I was told this would be coming down to the $200 - $300 range shortly.

Finally, I always judge a technology's readiness for prime-time by a company's reaction when I ask them for product to review. After all the rah-rah and chest-thumping the WHDI rep did during the demos, he was strangely silent when I asked him to send me WHDI product to test. That, to me, says more than any demo he could have shown. To be fair, however, although I didn't also ask the WirelessHD folks for product to test, they didn't volunteer any, either.

Next time, I'll wrap this up with a look at Quantenna's impressive 4x4 MIMO solution and Atheros' three-stream N.

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