Wireless Internet Service Providers (WISPs) have traditionally relied on the use of Wi-Fi technologies that leverage unlicensed frequency ranges of 2.4 and 5 GHz, along with all of the legal limitations that come with them. Recently, however, additional connectivity options have been made available and much more affordable to WISPs. Among those options is the use of Long Term Evolution (LTE) solutions. In this article, we examine how WISPs can use LTE for their networks, which was a topic of particular interest at WISPAMERICA this year.
Traditional WISP operation
WISPs developed from the need for an affordable and easy-to-deploy internet connectivity method in rural and suburban areas where wired connectivity solutions such as fiber, cable, and DSL are not yet cost-effective. WISPs deliver fixed wireless infrastructure, allowing a customer to connect to the network over wireless links with distances of several dozen meters or as far as several kilometers.
This wireless link is considered to be the “last mile” of the telecom network. Internally on the customer premises, this connectivity is then distributed as it would be with any other connectivity scenario, using switches, routers, structured cabling, and Wi-Fi, to name a few options.
WISPs are much more affordable and more easily deployable because they do not require the installation of cabling through municipal roads and other similar infrastructure. Additionally, they leverage unlicensed frequency bands for wireless links.
The result was that as early as the mid-2000s, WISPs could deliver high-speed connectivity that surpassed the average broadband speeds of the day.
As more and more subscribers became connected, more infrastructure and more wireless links were needed. This meant that extra bandwidth was being demanded from a set number of frequency ranges. The demand was growing but the radio frequency spectrum size remained the same.
As mentioned before, WISPs use primarily unlicensed frequency ranges. These are the same frequency ranges employed by Wi-Fi, specifically the 2.4 and the 5 GHz ranges. Because they are unlicensed, it means that:
- Anyone can use them
- They are subject to power output restrictions
- They are subject to hardware installation restrictions of various types
In addition, the 2.4 GHz range has only three non-overlapping channels while the 5 GHz range delivers several dozen channels, depending upon the channel width being used. This means that the available spectrum is a very limited resource and can quickly become overcrowded if there are a lot of wireless devices in the area, especially if you have competing WISPs vying for the same frequencies. For more details on the frequencies and channels used by Wi-Fi networks, take a look at our Know Your Stuff: Wi-Fi Fundamentals article.
The result is that WISPs must do their best to avoid interference by using highly directional antennas, strategically choosing channels to use, and depending upon the integrity and honesty of other WISPs and users to ensure that interference is kept to a minimum.
Some WISPs have been able to purchase licensed frequency ranges in specific areas in order to secure their usage without interference, but this can be out of reach cost-wise for many providers.
LTE as a solution
One of the best solutions is to use LTE technologies for WISP links. LTE is another name for 4G mobile communications infrastructure, which uses licensed frequency bands to transmit its service. While this might sound counterintuitive, since we often think about WISPs and LTE as separate and often competing services, this isn’t always the case.
There are several developments that are changing this. These include:
- Citizens Broadband Radio Service (CBRC) and Educational Broadband Service (EBS) – These are two different frequency ranges at 2.5 GHz and 3.5 GHz, respectively. The FCC has recently changed licensing laws within these two ranges that allow either unlicensed usage or low-cost frequency sharing with an incumbent mobile network operator (MNO). These changes, which took place in 2019 and 2020 respectively, have allowed WISPs to use LTE equipment and infrastructure, leveraging these particular frequencies at lower costs.
- The employment of private LTE infrastructure – LTE equipment providers have taken advantage of these changes to the spectrum usage by delivering equipment that is designed for WISP usage. This results in the creation of private LTE networks that can be leveraged by WISPs, enabling them to avoid the crowded unlicensed spectrum ranges.
- WISP – MNO cooperation – As LTE infrastructure continues to expand, one option for WISPs in some cases would be to cooperate with an MNO in those areas where other options are impractical. It’s possible to deliver fixed wireless links over existing LTE infrastructure that belongs to an MNO.
Keep in mind that WISPs don’t wirelessly connect the individual end devices to the network, but rather connect the premises using fixed wireless links. It is these links that need alternative options to overcome the limitations that unlicensed spectrums have.
LTE and WISPs have traditionally been competitors by the very nature of their implementation. However, with recent development, one finds that LTE can do a lot to support these essential service providers. The development of LTE technology and equipment, in combination with the opening up of the spectrum usage, will go a long way towards ensuring that WISPs will be able to continue to deliver service to the customers that need it.
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