White spaces: I’m eager for enthusiastic industry embraces

White spaces: I'm eager for enthusiastic industry embraces

BY BRIAN DIPERT
Contributing Editor

I was delighted, to put it simply and mildly, when I heard a few days ago that the IEEE had recently finalized and published the 802.22 standard for long-distance wireless networks ( www.businesswire.com/news/home/20110726007223/en/IEEE-802.22TM-2011-Standard-Wireless-Regional-Area-Networks) (here's the original release, both as a DOC ( mentor.ieee.org/802.22/dcn/11/22-11-0062-04-0000-ieee-802-22-press-release.doc) and as a PDF ( www.ieee802.org/22/Press_Release/ieee-802-22-press-release_EC_approved.pdf), both straight from the IEEE website). Quoting from the release:

“IEEE 802.22 systems will provide broadband access to wide regional areas around the world and bring reliable and secure high-speed communications to under-served and un-served communities. This new standard for Wireless Regional Area Networks (WRANs) takes advantage of the favorable transmission characteristics of the VHF and UHF TV bands to provide broadband wireless access over a large area up to 100 km from the transmitter. Each WRAN will deliver up to 22 Mbps per channel without interfering with reception of existing TV broadcast stations, using the so-called white spaces between the occupied TV channels. This technology is especially useful for serving less densely populated areas, such as rural areas, and developing countries where most vacant TV channels can be found. IEEE 802.22 incorporates advanced cognitive radio capabilities including dynamic spectrum access, incumbent database access, accurate geolocation techniques, spectrum sensing, regulatory domain dependent policies, spectrum etiquette, and coexistence for optimal use of the available spectrum.”

IEEE 802.22, if it isn't already obviously clear, is the association-sanctioned implementation of the White Spaces technology (en.wikipedia.org/wiki/White_spaces_%28radio%29) that's been under development (and along the way the subject of no shortage of controversy) for nearly a decade. Specifically, the spectrum focus is two-fold; the UHF and VHF bands which are most notably occupied in part by TV broadcasters but which also find use by some wireless microphones and medical equipment. White Spaces devices' intent is to harness unused channels in a particular geographic usage area, along with the between-channel spectral footprints, for both short- and long-distance bidirectional wireless networking purposes (PAN, LAN and WAN alike).

As early as mid-2003, the IEEE had sponsored an industry workshop on cognitive radio, followed up later that same year with a NPRM (notice of proposed rule-making) on the topic. Another NPRM followed in mid-2004, this one specific to television broadcast frequency bands, and in parallel the IEEE began working on the 802.22 standard. In February 2006, a U.S. Senate-authored bill proposed opening unused TV channels to alternative, license-free uses in a license-free manner. In October of that same year, the FCC opened the White Spaces on a limited basis, for use by high-power, fixed-location transmitters. And White Spaces momentum further increased in mid-2009, when analog television transmissions ceased for all but low-power broadcasters, since the resultant 'cleaner' ATSC signals provided for more usable between-channel spectrum.

As originally defined by technology advocates such as Intel, Google and Microsoft, all founding members of the White Spaces Coalition ( en.wikipedia.org/wiki/White_spaces_%28radio%29#White_Spaces_Coalition), transmitters would leverage a variety of technologies to ensure that they would not destructively interfere with other spectrum occupiers:

• They'd embed GPS transceivers to ascertain their locations, and access an online database containing registered transmitters at various locations and their associated frequencies and power outputs, subsequently avoiding those particular spectral swaths as appropriate

• They'd scan the UHF and VHF spectrum at power-up, identify sufficiently strong broadcasters and avoid those particular frequency footprints, and

• They'd remain good spectral citizens throughout system operation, periodically re-scanning the VHF and UHF bands and making appropriate transmission adjustments.

Surprisingly, when the FCC finalized its White Spaces ruling last September, it retained the geo-location requirement but dispensed with the need for regular spectrum sensing along with, if needed, frequency relocation by White Spaces devices to avoid other broadcasters in the band. Part of the reason for this turnabout, it seems, is that White Spaces technology developers successfully convinced the FCC of the negative bill-of-materials cost, form factor, and power consumption impacts of the spectral sensing feature inclusion. I'm not sure I buy into that argument, to be honest, given that spectral sensing and adjustment implementations are already mainstream and mature in 802.11 wireless equipment (the so-called auto-channel selection feature), along with wireless audio streaming schemes.

I wholeheartedly support the other seeming motivation for the FCC's simplification, however. The FCC had grown disenchanted with wireless microphone implementers who'd ignored Part 74 licensing requirements (www.fcc.gov/guides/wireless-microphone-faqs), with the silent sanction of equipment providers. However, the FCC didn't completely leave manufacturers and users in the lurch. It reserved two nationwide channels for wireless microphone use, which will allow an estimated 12 to 16 mics to operate simultaneously and interference-free. Installations (concerts, sports events, etc) can petition the FCC’s administrators for geo-location database inclusion, either on a temporary or permanent basis, if more reserved spectrum is necessary. And although these users will have to prove that the default channels are insufficient, they don't need to be licensed operators in order to register with the database. Not that these concessions have notably quieted the wireless microphone industry participants' grumbling…

Another notable set of complainers are the television broadcasters, loath to embrace anything that might even remotely impede their transmissions. I acknowledge the ongoing value of free-to-air (i.e. advertising-supported) television affiliates, as a vehicle for communicating local news, emergency services and other information to the masses on a no-cost-to-recipient basis (save teh television, of course). However, I've also long been underwhelmed by the broadcast industry's slow technology progression pace; look, for example, how strongly it fought the NTSC-to-ATSC transition, at how it's long under-responded to the threats of cable-, IPTV- and satellite-based services, and how it's more recently under-estimated the impact of Internet-based television content intermediaries such as Amazon Instant Video, Hulu, iTunes, and Netflix.

As I wrote for EDN Magazine after the conclusion of the 2010 NAB Show:

“Throughout the week I repeatedly asked various broadcaster representatives what plans they had for the spectrum that they were squatting on but under-utilizing, therefore attracting the FCC’s re-use interest. Again and again, I at best got vague and brief concepts tossed back at me such as ‘unicast or multicast data services’, ‘non-realtime material‘ and ‘mobile television’ (the latter actually doesn’t require incremental spectrum at all).

“Most of the time I received only an indignant and misguided rant of the form ‘that’s not the point…the government gave us the spectrum and we can do or not do whatever we want with it’. Each time that happened, I envisioned a petulant spoiled brat sitting in a sandbox, unwilling to share his toys with others but then wondering why nobody will be friends with and share their toys with him.

“Earth to NAB: put up, or shut up. You don’t own the spectrum; it’s licensed to you. Use it, in a meaningful manner and a timely fashion, or you’ll rightly lose it to someone who can make better use of it. The taxpayers of this country, who are the spectrum’s true owners, should demand nothing less.”

And not surprisingly, the cellular service providers are also doing their best to slow if not completely stall White Spaces developments, tossing out a variety of lame arguments but fundamentally driven by the fact that they view the embryonic technology as being competitive with their own wireless data plans. Again, feel free to label me unsympathetic. Cellular carriers regularly raise rates, throttle bandwidth and cap monthly usage allocations, with egregious overage charges beyond these aggregate traffic thresholds. They forego ongoing wireless network build-out costs in the pursuit of ever-higher profits, instead forcing customers to shoulder the load via fremtocell purchases that traffic-burden their broadband Internet connections. And even in the looming LTE era, they explicitly choose incompatible frequencies in order to ensure non-interoperability with each other.

White Spaces technology has the opportunity to actualize the largely unfulfilled promise of WiMAX, providing a much-needed alternative to cellular data and other legacy broadband implementations. Its VHF and UHF frequencies travel far and penetrate premises' walls with relative ease. The combination of “smart” antenna design and DSP algorithm advancements will effectively address weather- and other-related interference issues, even in mobile usage scenarios. White Spaces technology can bring broadband services to currently unfulfilled residents of rural climes, as well as additional competition to the under-fulfilled bulk of the United States. A single word is sufficient to summarize my perspective; “Godspeed.” ■