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03.20.2013
Originally featured on BroadcastEngineering.com
Engineer says white spaces networks are not "super" or even Wi-Fi
Peter Rysavy, a wireless networking engineer, says that white spaces networks are not all they are hyped up to be.

Heretofore, the federal government and its high-tech proponents have argued that "white space" spectrum should be made available for “super Wi-Fi networks” to extend broadband delivery throughout the country.

But Peter Rysavy, a guest contributor who writes in GigaOM, argues there is nothing “super” about white spaces networks and, in fact, it is not compatible with Wi-Fi as we know it. Rysavy is president of Rysavy Research, a wireless network engineering firm based in Hood River, OR.

“Proponents of this unlicensed band are using the term ‘Super Wi-Fi’ to describe the technology that would use this spectrum,” Rysavy wrote. “The only problem is that it’s not super for multiple reasons, and it’s definitely not ‘Wi-Fi.’”

The term Wi-Fi, he said, refers to interoperability compliance with specific IEEE 802.11 standards, and is a designation controlled by the Wi-Fi Alliance, the organization that certifies Wi-Fi gear. The Wi-Fi Alliance is not happy about the term “Super Wi-Fi.”

In a press release last year, the Wi-Fi Alliance wrote: “The technology touted as ‘Super Wi-Fi’ does not interoperate with the billions of Wi-Fi devices in use today.” In addition, it states, “Wi-Fi is a registered trademark of the Wi-Fi Alliance, and the term ‘Super Wi-Fi’ is not an authorized extension of the brand.”

White spaces networks, said Rysavy, need new radios. “Because super Wi-Fi isn’t a new band and has a new radio standard, existing Wi-Fi radios in phones, tablets and laptops won’t work with these white space networks. Any user wishing to connect over a future white space network will need entirely new equipment, most likely a USB form-factor modem.

“Another possibility would be a wireless router that connects to the white space network and provides Wi-Fi connections as a hot spot; however, that newly created Wi-Fi hotspot is then subject to all the congestion frailties we currently experience on Wi-Fi networks today.”

An important issue, he said, is the radio standard itself. “There are two different standards being developed for white space spectrum, IEEE 802.11af and IEEE 802.22. IEEE 802.22 was just recently completed, but IEEE 802.11af is still in development. It’s not at all clear which of these standards will prevail in the market, or whether something entirely new will come along. Dueling standards generally serve to confuse and delay markets.”

As to the “super” part of this technology, Rysavy said: “I don’t really see anything that ‘super’ about it. First, it’s quite slow compared to existing Wi-Fi technologies, limited to a peak rate of 29Mb/s. In contrast, the latest Wi-Fi standard, IEEE 802.11ac which is still under development but available in commercial product, can deliver throughput rates close to 1Gb/s (800Mb/s) in a base configuration, and over 6Gb/s in its most advanced configuration.”

Rysavy questions who will build the networks. “Claims about its superiority are based on an assumption that as-yet-unidentified service providers will deploy networks to operate on this white space spectrum all over the country and offer wireless broadband service,” he wrote. “Policymakers seem to hope that these new networks will somehow alleviate the mobile broadband capacity crunch that we are experiencing.

“This notion, however, is flawed,” he continued. “First, it is extremely unlikely that any entity will invest billions of dollars in massive amounts of network infrastructure to use unlicensed spectrum to support commercial wireless broadband services. The carrier’s inability to guarantee service quality, predict and manage capacity, and eliminate or prevent interference render unlicensed spectrum an inferior solution for providers who compete based on quality of service and ability to support bandwidth-hungry apps and devices.”

A better bet for this spectrum is LTE, Rysavy wrote. “Wireless data technologies that have enjoyed wild success, such as EV-DO, HSPA, and LTE are technologies with extremely broad coverage, coverage achieved from tens of thousands of base stations covering almost all of the population. It may seem to be an apples to oranges comparison to compare a commercial LTE network with a white space network, yet it is exactly this comparison that needs to be made, because the spectrum being contemplated will end up being used for LTE networks or for white-space networks. There is no middle ground currently under discussion or development.”

After a comparison of the two networks, Rysavy concluded that white spaces are for local networks, not national ones. “Usages are more likely to be adhoc and localized – just as with Wi-Fi. It might make sense to deploy a white space network on a campus, at an oil well, or in a town, but given the lack of control over the spectrum, it won’t make sense for any entity to deploy a national network.”

As a consequence, he said, “my expectation is that the total number of white space sites will be significantly lower than that of today’s cellular networks, and thus the aggregate national data capacity provided by the use of that spectrum will also be significantly lower. This lower data capacity represents a lost opportunity for the spectrum.”



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