5G networks require more base stations than previous LTE networks, making deployment in suburban and rural communities costly. WISPs provide in remote locations using unlicensed spectrum bands.
Proponents of 5G are touting the new technology as the "one global standard" for mobile communications. But despite the excitement around 5G--particularly for low-latency and machine-to-machine communication--there is still room (and importantly, spectrum) for other wireless communications technologies. Wireless Internet Service Providers (WISPs) will continue to be crucial in the age of 5G, as not all areas in the US can be economically serviced by traditional wireline broadband providers, and limitations inherent to 5G mobile broadband will make it unsuitable for practical use in rural or remote deployments.
Balancing long distances, many devices, and high speeds
For wireless communications, one of the most significant encumbrances to engineer around is spectral efficiency--the rate of information that can be transmitted over a given bandwidth, measured in bit(s)/Hz. Changes in radio resource management across successive generational standards--like the jump from LTE (16.32) to LTE Advanced (30)--can be used to increase the spectral efficiency, though this is still effectively a hard limit.
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Consider the generational change between 4G and 5G: One of the (relatively few) ways you can use 5G today is for mobile broadband. Verizon's non-standard 5G TF network deployments in Sacramento, Los Angeles, Houston, and Indianapolis allocate 400 MHz for home internet service, with plans to double this to 800 MHz. Verizon claims "typical speeds around 300 Mbps," and maximum speeds of 940 Mbps "depending on your location," roughly 3,000 feet from the base station.
These are good speeds, though several caveats apply to Verizon's 5G TF deployment:
- These are limited deployments in urban areas, with few subscribers, and little congestion
- This service uses 28 GHz (mmWave) frequencies, which are inherently line-of-sight
- The 5G TF equipment does not compete with standards-based 5G in smartphones
Verizon is planning to transition these deployments with standards-based 5G in the future, which will eventually lead to a situation where home internet users are competing with smartphone users for network use, though the larger problem is delivering consistent speed.
Why mmWave-powered 5G does not work well at long distances
Millimeter wave technology is inherently line-of-sight--obstructions such as walls and foliage interfere with the signal, making it difficult to use inside buildings. Likewise, mmWave signals are effectively absorbed by water droplets when it rains--a phenomenon known as "rain fade," similar to interruptions that occur when using satellite TV services during storms. Ultimately, mmWave signals--also called extremely high frequency (EHF) signals--do not naturally travel as far as other lower-frequency signals, because of their physical properties and atmospheric effects.
As a result of these limitations, deployments of mmWave 5G networks will rely on a higher number of base stations, which individually can serve a few city blocks. Base stations are generally connected to the network through wireline connections. As these base stations are moving progressively closer to subscribers' homes, the economics of connecting rural users will limit rollouts in less densely-populated areas--establishing a need for a different technology that is better suited to the geographical realities of the areas requiring service.
Why wireless ISPs are still useful
WISPs typically use proprietary equipment that operates over unlicensed frequencies, like the 900 Mhz, 2.4 GHz, and 5 GHz frequencies commonly used in wireless consumer electronics, and Wi-Fi networks. This equipment--like Verizon's 5G RF modem--connects to the WISP-operated network over this wireless connection, and provides a standard Wi-Fi signal for standard devices to connect to.
By using these sub-6 GHz frequencies, the radio equipment used by WISP subscribers is more resilient against rain fade and line-of-sight issues inherent to mmWave signals--and can be deployed to service users 10 or 20 kilometers away from the base station, rather than the 2-3 possible with mmWave 5G. While specific attributes of WISP-operated networks depend on how individual network operators deploy their systems, the different frequencies that WISPs operate in--compared to mmWave 5G mobile networks--are key.
"Fundamentally, you have to think in terms of frequencies," said Sakid Ahmed, director of engineering at Cambium Networks. With mmWave, "you know there's going to be distance and weather implications, it's designed for short distance, high capacity." Part of the way this can be achieved is by using higher power antennas and intensive signal processing, both of which are more challenging to with technologies targeted toward battery-operated smartphones."
The radio technology that powers these networks has developed beyond the relatively slow Motorola Canopy equipment commonly in use a decade ago. "What you need is many antennas on the internet source side and many antennas on the internet receiving side," said Kevin Jones, co-founder of Tarana Wireless.
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This principle--also known as MIMO--is also used to provide increased speeds on Wi-Fi as well as 4G and 5G networks. Though the WISP market lacks the same neatly delineated generations of radio equipment as the cellular market--in part, due to the vendor-specific, proprietary nature of the equipment used--the technology behind it has continued to evolve in parallel, adopting many of the same principles and innovations found in 4G and 5G networks, but with a more targeted deployment scenario.
Mobile and home internet use vary significantly
The fundamental difference between mobile and home internet use is that the 5G-like performance being driven by the cellular world requires a lot of infrastructure costs, including billing, provisioning, and roaming, Ahmed said.
Both cellular networks and WISPs are aiming to get more bandwidth to end users, though the contrast between the two markets is important: "Cellular guys are very focused on high urban density, high paying customers--a lot of our [equipment] is getting to the people that are asking for higher bandwidth but not necessarily getting the attention of a Comcast or an AT&T," Ahmed said.
Modern smartphones are capable devices, though the ways home internet services are used do vary from smartphone usage. For example, while you can stream Netflix on smartphones, streaming video in 4K on a TV is, comparatively, a significant increase in bandwidth use. Telecommuters, likewise, need a reliably high quality of service from their ISP. While Verizon's present 5G TF network is not shared with smartphones, future 5G networks from all operators will be--and having home internet users compete with smartphone users for network access is a prospect that is difficult to cater to or engineer for.
Difficult-to-service markets WISPs cater to
Cambium Networks--created following Motorola's sale of the fixed-point wireless Canopy business in 2011, when Motorola spun out their mobile handset division into Motorola Mobility--continues to provide wireless systems for deployment in rural areas and developing countries. ZDNet's Frances Marcellin covered a Cambium deployment by Disaster Tech Lab in 2016 on the Greek island of Lesbos, to provide Wi-Fi access to refugees.
For comparison, Tarana Wireless has worked with Chevron on a deployment of their wireless broadband technology in offshore oil fields in the Permian Basin, to supplant the use of comparatively high cost satellite modems. Tarana touts the spectral efficiency as the "highest reported," at 100 bit(s)/Hz, and ability to operate in non-line-of-sight environments. The company said it hopes to work with WISPs to deploy their wireless network system in suburban residential settings, in the near future.
Suburbia is typically the most common place WISPs are found--outside major cities, the economics for traditional wireline internet are often not compelling enough for ISPs to deploy their services. WISPA, a trade association of wireless ISPs, operates a directory of WISPs to help people in suburban areas connect to the internet.
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