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The Federal Communications Commission plans to designate 100 MHz of spectrum for small cell use, which would go a long way in encouraging the deployment of a dense layer of mobile broadband capacity for our smartphones to romp around in. But there’s a catch: carriers don’t just get to buy this spectrum and lock it into their networks — they have to share it with the government agencies already occupying it.
The FCC’s plan is part of a larger, and quite controversial, proposal first put forth by the President’s Council of Advisors on Policy and Technology (PCAST) to clear 1000 MHz of airwaves for mobile broadband use. That’s far more than the Obama administration is aiming for in its broadband plan, but PCAST’s recommendations all come with the sharing caveat: instead of booting the feds out of their airwaves, the public and private sectors must find a way to coexist.
The FCC is chipping away at the recommendation one spectrum band at a time, and it’s choosing to start with the 3.5 GHz band. In his announcement Wednesday, commission chairman Julius Genachowski said he would take formal steps by the end of the year to open the 3.5 GHz band for small cell use. While Genachowski never mentioned the word “sharing” in his statement, Ars Technica confirmed with FCC officials that the plan was to make 3.5 GHz shared between its current government radar use and wireless carriers.
All of the major carriers in the U.S. have talked up small cells, though Sprint(s s) is the only one that has laid out a specific deployment timeline. Sprint plans to deploy tens of thousands of the tiny base stations in 2013 and 2014, starting with malls and big public venues and then moving into high-traffic outdoor areas. At GigaOM’s Mobilize conference next week, Sprint CTO Stephen Bye will share more details on Sprint’s small cell plans.
The 3.5 GHz band would be ideal for small cell deployments. By creating a separate band for the tiny little networks, carriers wouldn’t have to worry about interference with their primary macro networks. Rather than try to wrap big tower-based macro cells around small cells using the same frequencies, a dedicated band means micro- and pico-cells could be placed directly under the macro umbrella. Each of those small cells would have the same capacity as their larger counterparts, so adding dozens of small cells beneath a single macro cell would boost its capacity enormously.
Also, higher frequencies don’t propagate as far as lower ones, which is why carriers have always sought to acquire lower band spectrum whenever possible. Since small cells, by definition, have much tinier coverage areas, they’re ideally suited for such high-frequency spectrum.
Don’t expect carriers to fall all over themselves to get this spectrum, though. The operators would rather own their licenses outright than share them with anyone, and the big carrier trade group CTIA has said that spectrum sharing in many cases simply won’t work. There are two different ways to share the airwaves — divvying them up by time or by geography — and according to CTIA, both approaches present problems.
In the case of small cells, carriers need that capacity most in densely populated areas where numerous customers are competing for bandwidth within a limited space. So if the government’s radar facilities are geographically distance — out in the desert, say — then spectrum sharing could work. If they’re at a busy metropolitan airport, that’s another story altogether.
The same goes for timesharing. If the government only uses those frequencies in the wee hours of the night, then carriers could easily turn their small cells off as traffic on the network is at its lowest point. The problem is if the Feds need their airwaves during the peak hours of the day, which is when carriers need them most as well.
We’ll see more details emerge as the FCC starts its deliberations, but even if a spectrum-sharing compromise can be worked out at 3.5 GHz, don’t expect the carriers to embrace this deal. They don’t want to set a spectrum sharing precedent, so they’re likely to lobby the government to clear out as much of this spectrum as possible for their own exclusive use.
Photo courtesy of Shutterstock user Everett Collection
Given the amount of spectrum the carriers currently have and how poorly managed and implemented it is (in terms of use) they should be happy to get anything further. The constraints are artificial at best and they use it to force customers to pay mightily for access.
Perhaps the Gov’t should have taken the 700Mhz C Block and built its own LTE network and allowed all carriers to use it so it would be uniformly accessed, managed capable from device to device. Oh wait I forgot in our country its not for the people by the people, its for the corporations by the corporations and thru the lobbyists.
The idea of tying spectrum sharing with small cells, then, makes sense on a number of fronts:
• The propagation characteristics of the 3.5 GHz band are limited, mitigating interference and making deployments in shopping malls, train stations, retail parks, and campuses ideal.
• Since small cells deliver targeted coverage, their chances of interfering with other services in shared spectrum are limited.
• The 3.5 GHz band is available on a nearly global basis, offering a potential for a global LTE band.
• It offers new opportunities for mobile competition. UK telecom regulator Ofcom was the first to propose the idea of auctioning off spectrum for small cells on a shared-spectrum basis last year. Its proposal included making 2 x 20 MHz available on a number of low-power licenses that would share spectrum at 2.6 GHz, with priority given to new entrants. The thought is that one entity builds a wholesale small cell network and sells access to others. Vendors such as Alcatel-Lucent argue that small cells should be deployed with a dedicated carrier if possible to eliminate concerns around interference between small cells and macro networks. Ofcom’s entire 4G auction plans are still under debate.
• The use of small cells represents a highly efficient use of the spectrum because of the greater capacity that can be provided with the intensive frequency re-use that can be achieved across a given area.
• Small cells will almost always be backed up by a macro cell layer of coverage. If a small cell is shut down in the 3.5 GHz shared band, operators can pick up coverage again in the macro network.
Certainly, a number of questions still need to be answered when it comes to the deployments of small cells in general, particularly around backhaul and network planning. A neutral-host concept in deploying small cells could eliminate concerns over multiple small cell deployments in a particular area from a regulatory and technical standpoint, but it also could reduce some of the efficiency gains if small cells are not tightly coordinated with a macro network, a point AT&T has highlighted in its criticisms of the PCAST report.
Check out our report on this: https://www.currentanalysis.com/f/2012/SpectrumSharing/return-spectrumsharing6g.asp
Would be interesting to see what spectrum will be used for backhaul of these small cells, in the case of NLoS given the absence of fiber at most small cell site locations.
Reblogged this on ytd2525.
Since NextWave sold their 2.3 GHz (WCS) spectrum to AWS, that 20-30 MHz licensed spectrum is now available for their small cell deployments as they have a very large US footprint of that band. That has left the lightly licensed 50MHz at the 3.65 GHz band to “share”, and another 100 MHz here is very helpful. If the carriers were open to sharing their RAN nodes than their would be a lower likelihood of interference in that band as wel.