HD-TV over Wifi

This is an older link, but somehow I missed the news that MobiTV is playing around with providing HD-TV over wireless (WiMAX) networks and now has even partnered to create a video on demand over WiMAX solution. Judging by the total lack of specs, technical details, or anything that wasn't written by a marketing team, I'm suspicious of the short term and even the long term viability--HDTV is magnitudes more demanding on a network than Mobi's current cellular technology that delivers grainy video to a cell phone.

Although I could be wrong, I don't expect for wireless to be able to carry IP HD-TV anytime in the near--or even not so near--future. Each HDTV channel is a minimum of 8Mb/s and can go up significantly, depending on quality, compression, etc. WiMAX can theoretically go up to 40Mb/s per channel, but this is shared among all the subscribers on the radio and assuming great distance and line of sight (real-world scenarios will probably give 10Mb/s as a good baseline). With "burstable" Internet applications (web surfing and so forth), the shared bandwidth is not that much of an issue; streaming applications such as television are much more problematic because they require 8Mb/s non-stop for extended periods of time. Given these statistics, even in the best of scenarios it is unlikely that you can support more than 5-10 simultaneous HD streams off of a WiMAX radio at a time. The radio density required to support 8pm primetime would absurd, even with WiMAX, and is simply economically infeasible.

This does illustrate a fundamental weakness to wireless: shared, low bandwidth last mile connections. Cable works well as a shared infrastructure because it can carry lots of data; ADSL2 (used for AT&T's IPTV product) works because, although it provides a meager 20Mb/s link, it is a dedicated 20Mb/s point to point link. WiMAX's mediocre bandwidth combined with shared infrastructure simply cannot carry the amount of data necessary provide video applications. MobiTV either is ignoring the economics of their solution, have some wicked compression scheme, or are using a different definition of HDTV than the rest of the world. Given the suspicious lack of technical details and high emphasis on marketing buzzwords, I am guessing both economic ignorance and a not-quite-so high definition TV.

My pessimism aside, I truly hope that I am wrong and a viable solution is on the horizon. I like wireless simply because it lowers the economic barrier of market entry and increases competition--something that is badly needed in telecom. A viable IPTV over WiMAX solution would radically change the marketplace in a lot of very positive ways. Still, given the typical gap between marketing and reality in the wireless industry, I'll not be holding my breath waiting for this to come to fruition.