Changes to Unlicensed Spectrum

Wi-FiEarlier this year in Docket ET No. 13-49 the FCC made a number of changes the unlicensed 5 GHz band of unlicensed spectrum. The docket was intended to unify the rules for using the 5 GHz spectrum. The FCC had made this spectrum available over time in several different chunks and had set different rules for the use of each portion. The FCC was also concerned about interference with some parts of the spectrum with doppler radar and with several government uses of spectrum. Spectrum rules are complex and I don’t want to spend the blog describing the changes in detail. But in the end, the FCC made some changes that wireless ISPS (WISPs) claim are going to kill the spectrum for rural use.

Comments filed by WISPA, the national association for WISPs claim that the changes that the FCC is making to the 5725 – 5850 MHz band is going to devastate rural data delivery from WISPs. The FCC is mandating that new equipment going forward use lower power and also use better filters to reduce out-of-band emissions. And WISPA is correct about what that means. If you understand the physics of wireless spectrum, each of those changes is going to reduce both the distance and the bandwidth that can be achieved with this slice of spectrum. I didn’t get out my calculator and spend an hour doing the math, but WISPA’s claim that this is going to reduce the effective distance for the 5 GHz band to about 3 miles seems like a reasonable estimate, which is also supported by several manufacturers of the equipment.

Some background might be of use in this discussion. WISPs can use three different bands of spectrum for delivering wireless data – 900 MHz, 2.4 GHz and 5 GHz. The two lower bands generally get congested fairly easy because there are a lot of other commercial applications using them. Plus, those two spectrums can’t go very far and still deliver significant bandwidth. And so to the extent they use those spectrums, WISPs tend to use them for customers residing closer to their towers. They save the 5 GHz spectrum for customers who are farther away and they use it for backhaul between towers. The piece of spectrum in question can be used to deliver a few Mbps to a customer up to ten miles from a transmitter. If you are a rural customer, getting 2 – 4 Mbps from a WISP still beats the heck out of dial-up.

Customers closer to a WISP transmitter can get decent bandwidth. About the fastest speed I have ever witnessed from a WISP was 30 Mbps, but it’s much more typical for customers within a reasonable distance from a tower to get something like 10 Mbps. That is a decent bandwidth product in today’s rural environment, although one has to wonder what that is going to feel like a decade from now.

Readers of this blog probably know that I spent ten years living in the Virgin Islands and my data connection there came from a WISP. On thing I saw there is the short life span of the wireless CPE at the home. In the ten years I was there I had three different receivers installed (one at the end) which means that my CPE lasted around 5 years. And the Virgin Islands is not a harsh environment since it’s around 85 degrees every day, unlike a lot of the US which has both freezing winters and hot summers. So the average WISP will need to phase in the new CPE to all customers over the next five to seven years as the old customer CPE dies. And they will need to use the new equipment for new customers.

That will be devastating to a WISP business plan. The manufacturers say that the new receivers may cost as much as $300 more to comply with the filtering requirements. I take that estimate with a grain of salt, but no doubt the equipment is going to cost more. But the real issue is the reduced distance and reduced bandwidth. Many, but not all, WISPs operate on very tight margins. They don’t have a lot of cash reserves and they rely on cash flow from customers to eke out enough extra cash to keep growing. They basically grow their businesses over time by rolling profits back into the business.

If these changes mean that WISPs can’t serve customers more than 3 miles from an existing antenna, there is a good chance that a lot of them are going to fail. They will be faced with either building a lot of new antennas to create smaller 3-mile circles or else they will have to abandon customers more than three miles away.

Obviously spectrum is in the purview of the FCC and some of the reasons why they are changing this spectrum are surely valid. But in this case they created an entire industry that relied upon the higher power level of the gear to justify a business plan and now they want to take that away. This is not going to be a good change for rural customers since over time many of them are going to lose their only option for broadband. While it is important to be sensitive to interference issues, one has to wonder how much interference there is out in the farm areas where these networks have been deployed. This impacts of this change that WISPA is warning about will be a step backward for rural America and rural bandwidth.

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