Debate about licensed and unlicensed spectrum has been raging as long as I can remember. Heck, I'll sheepishly admit that I was among the skeptics in the very early days of Wi-Fi, long before it took off like gangbusters.
In those early days, it seemed like a no-brainer: Of course you're going to run into interference if there's no one policing the airwaves and no one is checking with anyone else as to who's doing what. Those types of concerns came well before anyone thought about honeypots and Wi-Fi Pineapple devices that hijack Wi-Fi access points and grab consumers' sensitive data. Unlicensed uses simply don't come with the same degree of exclusive use and protections that licensed users get.
Fast forward many years and companies like Qualcomm (NASDAQ:QCOM) are raising concerns about potential interference in a post-auction 600 MHz band. That is to say, potential interference caused by allowing unlicensed devices to operate within the 600 MHz band duplex gap and guard bands at a proposed 40 mW power level. Note: All of this is predicated on the assumption that the FCC is able to pull off a two-part incentive auction with broadcasters and the wireless industry.
Qualcomm and Broadcom, in particular, are at one another's throats via the FCC's electronic filing system, with each accusing the other of misrepresentation and making false or misleading arguments. A Broadcom spokesperson wasn't immediately available to discuss the topic directly with me, but in FCC filings, the company has said it has provided plenty of detailed analysis that demonstrates it is possible for unlicensed devices to operate in the duplex gap/guard bands in the 600 MHz band. (It's worth noting as well that Broadcom is exiting the cellular baseband market while continuing to supply Wi-Fi chips.)
Conversely, Qualcomm says there is overwhelming evidence that allowing unlicensed devices within the 600 MHz band duplex gap and guard bands transmitting at the 40 mW power level currently allowed for portable TV white space devices will cause harmful interference to devices using the 600 MHz licensed spectrum.
Qualcomm has a unique perspective in that its chips support traditional licensed services in the 2G, 3G and LTE bands and also enable Wi-Fi, Bluetooth and other unlicensed technologies. It has filed comments saying it is very concerned about harmful interference in the post-auction 600 MHz band duplex gap and guard bands. The duplex gap is the spectrum separation between the spectrum used for uplink and spectrum used for downlink, and the guard band is the zone of quietness in between the downlink and where the TV stations are repacked into.
When approached about questions of licensed versus unlicensed, Qualcomm's ultimate criterion is technical feasibility, according to Dean Brenner, senior vice president of government affairs at Qualcomm. In general, unlicensed spectrum is suited for lower power, local area services, whereas licensed spectrum entails exclusive use and protections from interference.
"It's important to highlight, Qualcomm is not for unlicensed spectrum or against unlicensed spectrum," he said. "We're trying to enable both licensed and unlicensed spectrum, and we let the technical facts dictate our positions on these issues. For us, it's a technical question, not a religious question and not a political question."
At the FCC's last meeting, Commissioner Ajit Pai said the laws of physics aren't liberal or conservative, Democratic or Republican. "They are immutable," he said, noting his concern that permitting white space devices to operate in the guard bands, at the power levels and bandwidths proposed, might impair the adjacent licensed spectrum.
The big question is: How can the FCC arrange the band plan for 600 MHz after the auction in a manner that allows the fastest and broadest possible use of the spectrum?
Clearly, smart engineers can and do disagree, and companies have different economic motivations for arguing one way or another. Remember how long the FAA argued that in-flight cellphone calls and Internet usage posed a safety threat to the plane's communications? There was a lot of heated debate before the FCC officially declared cellphones were not a threat and left it up to airlines to set their own cellphone-in-flight usage policies. Of course, now that nearly everyone has a cellphone, airlines don't want to open up that hornet's nest to allow for planes full of chatting customers--a commercial and/or moral decision perhaps, but not one necessarily based on scientific facts or technology.
Can decisions like the FCC faces really be determined by technical arguments alone? The answer to that question isn't crystal clear, but in the FCC's zest to open up spectrum for more unlicensed uses, it bears repeating.--Monica