The Federal Communications Commission last week said it will add 195MHz of spectrum to Wi-Fi's 5GHz band. This move is designed to relieve congestion in Wi-Fi networks, particularly in areas of widespread simultaneous usage like airports and sports stadiums. It could help your home network too, but not right away—routers available in stores today may not be able to use the new spectrum at all.
Finding out definitively whether today's routers will support the new spectrum is difficult, partly because the FCC still has to issue specific rules governing its use. We've hit up router vendors and other industry people to find out whether software updates might let current routers access the new spectrum. While the results were a bit muddled, it seems safe to say no one is guaranteeing today's routers will get the benefit of the new 195MHz. Even the latest routers supporting the ultra-modern 802.11ac standard may be left behind.
Cisco refused to comment at all, telling us only "Cisco has not made any announcements about this so cannot discuss at this time." Buffalo told us "the chip vendors will need to work on it" and that "they will at least to have to make changes to the hardware driver. ... The magnitude of that change will determine if Buffalo is able to use the same hardware."
The most extensive response we got from a router vendor was from D-Link, whose associate VP of Product Development Will Brown provided us with this statement:
After discussion with our current chip vendors, we understand that the industry is lobbying to move this licensed spectrum to unlicensed spectrum. In order to take advantage of this spectrum, the chip vendors are reporting that updated chipsets will be required if approved. Our product development philosophy is to provide our customers with the best value. Regardless, if we can achieve this additional feature by a firmware [update] we would commit to providing it as long as it doesn't have detrimental effects on the devices' current features and performance.
As this new feature (spectrum) is released there are a number of go-to-market items that we are evaluating including competitive requirements, cost of implementation, education to our customers, and standards compliance.
Given that Buffalo and D-Link said it may ultimately come down to chip vendors, we checked with Broadcom, Marvell, and Qualcomm Atheros to see what they have to say. So far, we've received a response from Qualcomm, which said "It is true that none of the existing routers can take advantage of the potential additional channels the FCC is planning to un-license. The reason for that is current dual-band routers and chipsets that are in them are designed to support already unlicensed spectrum. The new proposed 5GHz channels are in the higher 5GHz band so that new chips support to support this will be required."
While current Qualcomm chips don't support the additional (or newly "unlicensed") spectrum, a revised version of the chips that will support it is in the works. "Qualcomm Atheros 11ac Wi-Fi products are designed to support these new additional channels of the 5GHz spectrum and will be ready when the FCC's rulemaking process will be kicked off," the company said.
Broadcom has weighed in a little more optimistically, saying "There is a possibility that our existing 11ac solutions could take advantage of the new spectrum. To determine this we need to wait for the FCC to release their detailed technical rules for operation at these new frequencies. We expect this to happen towards the end of February at which point we will have more clarity on the question."
Sharing spectrum isn't easy
One complication in making chips and routers support the new spectrum is that, rather than being devoted exclusively to Wi-Fi, the 195MHz may be shared with federal agencies.
The FCC's announcement noted that the 195MHz at hand is used today "by both federal and non-federal users." Thus, "the effort will require significant collaboration with other federal agencies." For example, the 5.850-5.925GHz band is allocated to the government's dedicated short-range communications (DSRC) project.
If the spectrum is shared in a similar manner as in the TV White Spaces project, this would require routers to register their geographic locations with a database, which would then return a list of authorized channels they may use.
One White Spaces database is operated by Spectrum Bridge, whose CTO Peter Stanforth explained to me via e-mail why a White Spaces approach might require all new hardware:
The FCC has not specified the rules for how the spectrum will be shared. One option is DFS [dynamic frequency selection], already a technology used in 5GHz but one that is not working as well as expected.
Most current devices support DFS. The other option is to add a database like the one for TVWS [TV White Spaces]. There is a manual database today that supports part of this band. Because this is a manual process the sharing is managed through the configuration interfaces in the devices. None of the current devices support a database API so at a minimum they would need a firmware update. However, even if they support the spectrum and add a database API, the FCC is likely to require recertification before they are permitted to use the band. This last step probably means that only new devices will access the band.
While routers would have to communicate with spectrum sharing databases, end-user devices (like laptops, phones, and tablets) would also need to support the right frequencies and the latest standards. Devices like laptops will need new chips as well, Qualcomm told us.
Wi-Fi Alliance Technical Director Greg Ennis speculated some router manufacturers might have built current devices to support the new spectrum, since these particular bands have been proposed for Wi-Fi usage in the past. Even then, how the FCC sets rules governing the spectrum's use will be important. "Until the FCC really goes through their process of determining exactly what the rules are going to be for operating in these bands, it won't be clear how this is going to play out. It may involve rules that require new implementations," Ennis said.
(The FCC has also turned to spectrum sharing to relieve congestion in cellular networks. See also:
FCC to make spectrum sharing reality, whether carriers want it or not.)
More Wi-Fi spectrum is a good thing, no matter when it happens
This isn't to say that the FCC's move isn't meaningful, or that you should even hold off on buying a router (there are plenty of good ones out there already). The point is that adding spectrum to Wi-Fi is more of a long-term play to ensure we don't outgrow our current allotment.
Wi-Fi's 5GHz band currently stretches from 5.150 to 5.825, with a gap in the middle, Ennis told Ars in a phone interview. The FCC plan would add two new bands, ultimately giving Wi-Fi a contiguous block from 5.150 to 5.925. This will be particularly useful to devices using 802.11ac as opposed to the last-generation 802.11n standard. 802.11ac can use channels of up to 160MHz wide, and having a larger contiguous band as proposed by the FCC would allow "more and wider channels (and thus more capacity)," wireless engineer Steven Crowley wrote on his blog.
"This will have a big impact on the devices that support 802.11ac," Stanforth told Ars. "Today they can only get one max size channel; with the new allocation they should be able to get four, which is a big deal."
A statement from FCC Commissioner Ajit Pai notes that 802.11ac "requires large, contiguous swaths of spectrum for high-speed, high-capacity data transfers... The propagation of 5GHz spectrum is relatively short, which minimizes interference and makes 5GHz perfect for common unlicensed applications."
The 195MHz would be the biggest Wi-Fi spectrum expansion in the 5GHz band since 2003, when it was expanded from 300MHz to 555MHz, Crowley wrote.
The FCC's next step is to issue a notice of proposed rule-making to gather comments on the spectrum changes. How long it will take to actually clear the spectrum for Wi-Fi use isn't known, although Ennis said, "I would certainly hope it happens in 2013." (UPDATE: It will take longer than that. The National Telecommunications & Information Administration has said it won't finalize its recommendations to the FCC until December 2014.)
The FCC said the extra spectrum will "relieve congested Wi-Fi networks at major hubs like convention centers and airports" and "help in homes as tablets and smartphones proliferate and video use rises."
Those wider channels will be great for video applications, Ennis said.
Although it will mostly be new devices actually using the new spectrum, Ennis said all Wi-Fi users will ultimately benefit, if only indirectly. Even people stuck on the crowded 2.4GHz band might see congestion relieved as their neighbors move on to more attractive spectrum.
"Adding spectrum ends up helping everybody, including the devices that are currently operating on the 2.4GHz band, because by expanding the spectrum everybody is using that ends up spreading users over a wider total bandwidth," Ennis said.
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