Comment On David Isenberg's Beyond White Spaces Article

David Isenberg (who's a must read for me) has posted a thought-provoking article titled Beyond White Spaces.

What... (regregrettably) most people miss in the discussion about license-exempt use of Television Broadcast Spectrum White Spaces are a number of points that, if taken into consideration, considerably alter the overall discussion and potential for license-exempt use of White Spaces.

One fundamental point that's universally overlooked in the White Spaces discussions is that the original rules that are put into place are subject to change as technology makes new things possible, usage patterns change, economic value changes. So, the admittedly puny capabilities of this first generation of license-exempt White Spaces devices that are envisioned is just a timid first step. In time, there will be bolder steps. One example is the FCC's Part 15.247 rules for license-exempt communications operation in the "junk bands" of 902-928 MHz, 2.40-2.485 MHz, and 5.2/5.4/5.5 GHz have evolved continuously... and in some cases radically, from their first iteration. The changes came about because of improved technology, fears that were later proven to be unfounded, requests from industry and user groups, etc. Having been on the inside of some of those changes, I've been pleasantly surprised to learn that the FCC's rules are not rigid and unchangeable... and if you know what to look for... sometimes amazingly prescient and flexible.

Another fundamental point is that it's obvious to those that have looked seriously at the trends is that there will be yet another round of reduction of the spectrum currently allocated to over-the-air television broadcasting. We'll have another chance at crafting a new generation of devices and systems that operate in this spectrum.

Third, White Spaces is intended... and will have its greatest impact by far, in rural areas. High-powered, High Profile White Spaces systems operating under "non-exclusive licensed lite" rules rather than full license-exempt rules is a real game changer in Broadband Internet Access for rural areas. It's not a panacea - it will remain expensive to build towers, buy radios, and put together high-quality systems. There's still the backhaul problem (as in, not much, and pretty expensive in rural areas). But dollar-for-dollar, hertz-for-hertz, systems operating in White Space spectrum, at reasonably high power (tens of watts should work fine) will provide far better coverage and penetration than available such systems to date. Everyone would love to have fiber-to-the-premises, but that's tough to do other than with outright government-scale grants, in areas that have only a few "premises" within a 100 square mile area.

One thing Isenberg doesn't quite get right is that for White Spaces to succeed, especially in rural areas, it doesn't have to be an "Ethernet" or "Wi-Fi" scale of success. The numbers can be small (on a mass-market scale) but still large enough to attract vendors who can make quality systems that are affordable enough. Alvarion was able to do this using wholly-proprietary technology, and there's sufficient momentum in White Space that a dominant standard will emerge from the three competing contenders (one based on 802.11/Wi-Fi, one based on 802.16/a/WiMAX, and the other is a gestating new IEEE standard - 802.22).

But Isenberg hits it out of the park when he suggests that we need a comprehensive plan that doesn't address "slivers" of spectrum. The trouble is that when it comes time to convening groups to hammer out such plans, they end up populated with spectrum and technology partisans, and the resulting compromises necessary to reach any kind of conclusion end up so vague, gradual, and non-distruptive that not implementing them is actually more productive. What's really needed is a group that can truly look at the "big picture" of spectrum, technology, emerging trends, best practices, etc. without the partisan baggage that anyone beholden to "those that fund them" inevitably bring. We've done this before with, for example, National Science Foundation (NSF) and Defense Advanced Research Projects Agency (DARPA) grants that span multiple years and allow truly deep and independent research and conclusions. There are technology, operational and business models, and systems models that have never been tried, or tried on a small scale, that could be woven into a plan that could really work. I, for one, am available.

Comments

[Charles Brown]

Hi Steve,

I was wondering about your views of aggregate bandwidth capability for providing what could legitimately be called "broadband" over the 6MHz channels in the white spaces. I never see that topic discussed anywhere either. What do you think we are we talking about here in terms of BWIA?

I take your point about "increments" in regulatory matters, but I would like to remind that the Part 15.247 rules were pushed from being visionary, infrastructure class BWIA in 1985 to short-range WLAN devices, especially with regard to the power rules. To my mind, this was hardly positive "regulatory evolution" even it did result in new technology development within the confines of 802.11. One could argue the opposite point, i.e., what could we have seen in product development and alternative access infrastructure had the original vision of 15.247 prevailed in its original form? It seems to me that this is a history lesson worth noting as well.

Steve replies:

Charles - agreed that 15.247 could have been so much more. Our mutual colleague Dewayne Hendricks has educated me about how much grander was the original vision than what actually came to be allowed. But, politics... and the FCC is all about politics... has been called "the art of the possible" and I think that applies to 15.247. It's taken decades longer than we hoped to see some of the real potential of license-exempt spectrum usage, but it's finally happening.

As for white spaces... well... 15 years or so ago, Alvarion was able to achieve 3 bits/Hz - a FHSS system that achieved 3 Mbps in a 1 MHz channel. That's old technology now, but even using a conservative 5 MHz channel to provide for some guard bands, that's a potential 15 Mbps. And, there's nothing to prevent systems from aggregating adjacent channels, so you really aren't "stuck" with "just" a mere 6 MHz channel.