I see articles all of the time where the authors treat all the various wireless technologies used for rural markets as if they are all the same. They often talk about the ‘rural wireless’ solution without distinguishing the fact that there are different wireless technologies using different spectrums that have different operating characteristics. And this is dangerous because I’ve found that politicians and decision makers often don’t understand that ‘wireless’ can mean a wide range of different technologies. So this blog talks about the two primary wireless technologies that are going to be seeing big play in the future in rural broadband deployments.
The first wireless technology is cellular data. Rural customers for years have been using the cellular data plans to provide a bare-bones data connection at home. But priced at $10 to $15 per downloaded gigabyte this is one of the most expensive sources of broadband in the world. Yet rural cellular data is going to be in the news a lot more because AT&T and Verizon intend to use cellular data to replace landline copper connections. AT&T is actively deploying cellular data to fulfill its obligations under the CAF II program.
Cellular companies own a wide range of different licensed spectra, meaning they are the only ones who can use it. Most cellular frequencies share characteristics like the ability to penetrate obstacles such as trees or home walls fairly well. The one characteristic that is not understood about cellular frequencies when used for wireless data is that the strength and speed of the delivered bandwidth is largely determined by the distance of a customer from a cellphone tower. Customers close to a tower might get speeds several times faster than somebody 3 miles from a tower.
Both AT&T and Verizon intend to use ‘fixed’ cellular for rural broadband. That means they will install a small antenna outside a home which allows for a stronger signal than receiving the signal inside the house. Speeds will not only vary by distance from the tower, but also by the specific version of technology being used. For example, 3G cellular only delivers a few Mbps of speed. Current 4G technology can provide up to about 15 Mbps to those close to a tower, but there are many different generations of 4G deployments that will have slower speeds. 5G data will be even faster, with a goal of 50 Mbps, but for a number of reasons (which I won’t go into here) there might not be widespread deployment of rural 5G for at least a decade.
The other future primary technology used for rural wireless is a point-to-multipoint wireless technology. In these networks there is a transmitter on a tower that sends a focused microwave beam to a small dish at a customer’s home. The frequencies used for point-to-multipoint data are much higher than cellular frequencies. If these frequencies were openly broadcast like cellular they wouldn’t travel very far and that lack of distance is the reason the technology only uses a focused beam.
Today the most common deployment of this technology uses the unlicensed WiFi spectrum, which is the same used by WiFi routers in the home. The swaths of spectrum used are 2.4 GHz and 5.7 GHz. In a point-to-multipoint network, these two frequencies are often used together with the higher 5.7 GHz used to reach the closest customers and the lower frequency for customers who are farther away. In practical use in wide open conditions these frequencies can be used to serve customers up to about 3–4 miles from a transmitter. The frequencies have a theoretical cap of 28 Mbps of bandwidth, but it’s possible to get faster speeds by bonding multiple signals together.
The FCC recently authorized the use of 3.65 GHz–3.70 GHz frequency for rural broadband. This spectrum can penetrate trees better than WiFi. It can support a signal of up to 37 Mbps, but can be combined with WiFi to produce even faster speeds. In practical application this spectrum can be used to deliver up to 20 Mbps out five miles from the transmitter, with more bandwidth for those that are closer. There are places where this spectrum can’t be used if there is a government satellite farm or military base nearby.
The FCC is expected to soon release the use of ‘white space’ spectrum for rural broadband. This is spectrum that is the same range as TV channels 14 through 51, in four bands of frequencies in the VHF and UHF regions of 54–72 MHz, 76–88 MHz, 174–216 MHz, and 470–698 MHz. The downside of the spectrum is that it won’t be available everywhere since in some places TV stations will keep their existing spectrum.
The rural potential for white space spectrum is to extend point-to-multipoint radio systems. White space radios should be able to deliver perhaps 45 Mbps up to about 6 miles from the transmitter. That’s easily twice as far as what can be delivered today using unlicensed spectrum and can create a 12-mile circle around a transmitter.
Both of these wireless technologies must be fiber fed in order to achieve the best speeds. There are numerous deployments today of point-to-multipoint wireless systems that only deliver a few Mbps to customers. That’s usually due to the transmitters not being connected to fiber or from serving customers who are too far from a tower.
The distinction between the two kinds of wireless technologies matter. Today a cellular network is not capable of delivering speeds that are considered as broadband. But point-to-multipoint networks can exceed the FCC definition of broadband if the towers are fiber fed and if the customers are close enough to the tower. But this technology often gets a bad name because a lot of wireless companies deliver products that are far slower than the capability of the spectrum.