In a refreshing change from the "whatever is best for the large, emplaced incumbents" attitude of recent years at the Federal Communications Commission (FCC), on June 7, 2007 it renewed its commitment to a bold experiment in spectrum allocation (PDF - 30 pages) for the proposed new 3650 - 3700 MHz (3.65 - 3.70 GHz) band.
The "3650 MHz band" is currently allocated to satellite earth stations, of which there are a handful in the continental United States (CONUS). Two years ago, the FCC proposed to allow the sharing of this band for terrestrial communications use with the primary caveat that the satellite earth stations would be protected from interference.
The primary method of protecting the satellite earth stations from interference was that terrestrial users would have to register / license their systems and obtain prior approval for operation. But, in a unique twist with FCC registration / licensing... the FCC would not mandate or "guarantee" exclusivity on a particular frequency or area. All comers were welcome, but...
The FCC expanded the experiment by mandating that both the operators and systems must "cooperate", the latter doing so through the use of an (undefined by the FCC) "contention protocol".
Responses to this unique proposal from wireless and especially Broadband Wireless industry incumbents was uniformly negative. Two of the most common responses were that the "contention protocol" requirement could not be made to work and that the new band should be conventionally, exclusively allocated via spectrum auction. The former response was predictable because the contention protocol was undefined (deliberately - the FCC wanted industry to come up with the actual technology) and as far as the wireless industry was concerned, contention was an issue they didn't have to deal with because the portions of spectrum they used was allocated (licensed) on an exclusive basis. The latter response was also predictable because this new band was the closest that the US will likely ever have to the 3.5 GHz band which has been made available worldwide by spectrum allocation authorities except in the US where it was previously allocated, and is intensively used by the Department of Defense (DOD).
But there was a groundswell of favorable reaction by a small number of small organizations that praised the FCC, chief among them small, entrepreneurial Wireless Internet Service Providers (WISPs). They particularly liked that this new band would not be available for use for "baby monitors and cordless phones", not to mention battling interference from non-communications uses like microwave ovens and industrial dryers and being second in priority of use to Amateur Radio Operators and others. (3650 will be under FCC Rules, Part 90, rather than Part 15, which WISPs are more familiar with). The overall characteristics of the band and the rules make it well-suited for use in building backhaul links and held the promise of making WiMAX equipment available for use in the US (previously unavailable because to date WiMAX equipment has only been certified for use in the 3.5 GHz (as stated previously, unavailable in the US) and the 2.5 GHz (licensed, and rabidly, expensively being acquired by large wireless companies such as Sprint and Clearwire).
The one change that the FCC made to their original proposal for "3650" after two years was to recognize that their proposal for a "contention protocol" wasn't well-defined. In response, it partitioned 3650 into two 25 MHz segments - 3.650-3.675 GHz and 3.675 - 3.700 GHz. As I understand what the FCC has proposed, any device that uses any mechanism that can be described as a contention protocol can use the lower segment - contention protocols in that segment do not have to be interoperable. That means that the lower segment will be something of a "free-for-all" or as I prefer to call it - Darwinian. The upper segment is reserved for systems that can "play nice", whose contention protocol does attempt to work with other systems. As examples, WiMAX systems would only be allowed in the lower segment because their contention protocol only interoperates with other WiMAX systems. A Wi-Fi system adapted for 3650 would be allowed to use both segments because it "listens before transmit" for any kind of transmission on the channel it's tuned to and if it does receive other transmissions, refrains from transmitting.
Since the original 3650 announcement two years ago, development has been underway for standards-based systems, surprisingly from both "WiMAX" (802.16) and "Wi-Fi" (802.11). The former effort is 802.16h; the latter is 802.11y. The documentation available on both sites is sufficiently obscure that I can't parse out the different approaches from the two groups, so suffice it to say that both the "WiMAX" approach, and the "Wi-Fi" approach will be apparently represented, much the same way that both groups have developed standards for the use of the license-exempt 5.8 GHz band.
While mandated cooperation, both operator and systems, sounds good, in the discussions that raged on various mailing lists immediately after the announcement, Patrick Leary of Alvarion posted some very cogent, and cautionary analysis:
The point is that this band will be really difficult for someone to plan and operate a business except in a rural area with little to no other competition (so it should be great for WISPs). It has zero to do with RF and everything to do with the "cooperation" REQUIREMENT of the rule. It forces a new entrant to work with the incumbent and vice versa. So you work something out and go home. Next day another guys pops up. Guess what, your old agreement gets tossed out the window and you MUST make accommodation for the next guy of else he can take you to court (and win). So then the THREE of you strike a deal and go back home. The next day a 4th WISP comes in and guess what? It starts all over again.
Each time you MUST, by law, cooperate and come to a mutually satisfactory agreement. Again. And Again. And again.
I concur with Leary's analysis, and I think it's prescient. Making use of 3650 will force WISPs into cooperation like they've never had to do before. Even users of other licensed / Part 90 bands will be in an unusual position that in 3650, there is no "we were here first, you're not allowed to interfere with us" prioritization.
Towerstream was happy to see 3650 "come back to life" at the FCC. Towerstream (and a number of other service providers) have reportedly been using 3650 under Experimental FCC licenses.
Towerstream Applauds FCC Spectrum 3650 MHz Band Decision
Middletown, RI, June 8, 2007 – (NASDAQ:TWER) On Thursday, June 7, the Federal Communications Commission (FCC) announced its decision to uphold its 2005 non-exclusive licensing scheme for the 3650-3700 MHz band (3650 MHz band) spectrum. Towerstream Corporation, a leading fixed WiMAX service provider, commended the FCC’s decision to enable flexible use of this spectrum which should benefit consumers and businesses.
"We applaud the FCC for the time and exhaustive diligence they spent considering all the issues surrounding the 3.650 Band," said Jeff Thompson, President and CEO of Towerstream. "This unique licensing scheme provides Towerstream additional tools to deploy affordable alternative broadband services across the US. In addition, we are pleased the FCC is protecting satellite owners who also need to utilize this spectrum."
I was amused and pleasantly surprised to see that Part-15.Org is proactive in forming Part-90.Org - The only organization dedicated to the use of 3650 -3700 MHz by License Exempt Wireless Internet Service Providers.
Harold Feld, who I don't usually agree with has posted an excellent analysis on this latest development on 3650.
By Steve Stroh
This article is Copyright © 2007 by Steve Stroh.
Steve, this is fantastic analysis! Thanks for the details and clear explanation of what the FCC news really means. As a follower of Towerstream I find this especially important to understand.
-Robert
Posted by: Robert Morton | June 13, 2007 at 19:07
You don't usually agree with me? I didn't know that.
Posted by: Harold Feld | June 14, 2007 at 13:30