FCC Win Unlocks Additional 45 MHz for Wi-Fi, but Will the Industry Take Notice?

For over 2 decades, the 5.9 Gigahertz (GHz) spectrum lay dormant, awaiting use by an Intelligent Transport System (ITS) technology that never materialized. Eager to further stimulate the U.S. Wi-Fi industry, the Federal Communications Commission (FCC) in November 2020 unanimously voted to reallocate the lower 45 Megahertz (MHz) portion of the band for unlicensed Wi-Fi use, but the decision was protested by an association of U.S. transportation organizations. In August this year, the DC Court of Appeals finally rejected this challenge, paving the way for the utilization of the spectrum in the United States. Although at first glance the 5.9 GHz band may appear negligible, especially in contrast to the 1200 MHz released through the 6 GHz band in 2020, it is worth watching for several important reasons, not the least because it offers the tantalizing potential prospect of one day seamlessly bridging the gap between the 5 GHz and 6 GHz bands.

To understand the current state and future prospects of the 5.9 GHz spectrum, which spans 5850 MHz to 5925 MHz and is often referred to as U-NII-4, it is important to understand its history. The story begins in the year 1999, when Wi-Fi was still in its infancy and the available 2.4 GHz and 5 GHz bands were more than sufficient for the maximum 54 Megabits per Second (Mbit/s) speeds 802.11a could offer. Thus, the FCC saw fit to allocate U-NII-4 to a nascent technology called Vehicle-to-Everything (V2X), which promised to improve road safety and increase traffic efficiency by facilitating communication between vehicles and road infrastructure. Dedicated Short-Range Radio Communication (DSRC) was to be the underlying wireless communication technology, and it was envisioned that, within the space of a few years, everything from traffic lights to bicycles would be augmented with DSRC. An advanced replacement based on cellular connectivity (Cellular-V2X (C-V2X)) emerged in 2017, but ultimately, V2X failed to live up to its hype, with no automaker ever committing to integrating V2X into their vehicles on a large scale. More than 2 decades after the FCC had consigned the 5.9 GHz spectrum to V2X, it remained underutilized, while at the same time, the demands for additional spectrum from Wi-Fi had become insatiable. Therefore, hot on the heels of the allocation of the 6 GHz spectrum in April 2020, in November 2020, the FCC voted unanimously 5-0 to redistribute the lower 45 MHz (5850 – 5895 MHz) of U-NII-4 for unlicensed Wi-Fi use, at the same time reaffirming that the upper 30 MHz (5895 – 5925 MHz) portion of the band will be reserved for C-V2X applications.

The intelligent transportation lobby did not relinquish its spectrum without a fight, and several American transportation organizations, including the Intelligent Transportation Society of America (ITS America) and the American Association of State Highway and Transportation Officials (AASHTO), attempted to overturn the FCC’s ruling through legal action. In the past, the FCC had been successfully swayed by this lobby. For example, in 2013, ITS America, in collaboration with major automakers and the transportation officials of various U.S. states, successfully lobbied against a reallocation of the 5.9 GHz band. In the 9 years since then though, the equation has shifted. First, and perhaps most importantly, V2X has made little progress and there are no signs that it will do so in the near future. Given that the network demands for unlicensed Wi-Fi use have expanded significantly in recent years, it is hard to justify reserving even small sections of the spectrum for technologies that aren’t actively using it. Second, the FCC, under the direction of Chairwoman Jessica Rosenworcel, appears committed to maintaining the United States’ position as the global leader in Wi-Fi technologies. These factors drove the FCC to reallocate the lower 45 MHz of U-NII-4 in November 2020, and last month convinced the DC Court of Appeals to reject the challenge submitted by the U.S. transportation organizations and to uphold the FCC’s decision.

Although not as revolutionary as the 2020 release of the 6 GHz spectrum, the lower portion of U-NII-4 still offers the prospect of three additional 20 MHz channels, two additional 40 MHz channels, and one additional 80 MHz channel. Several caveats have been attached to its use, including that only indoor Access Points (APs) can harness U-NII-4, and that they must use an integrated antenna, cannot use a weatherized enclosure, and may not be battery powered. The biggest hurdle though is the current limited amount of client support that U-NII-4 faces. For this reason, it is likely that, initially, premium APs (which connect with premium 5.9 GHz-enabled client devices) and mesh networks (which leverage U-NII-4 for backhaul) will be the most likely to take advantage of the new spectrum.

At present, only a handful of routers on the market are equipped to harness the 5.9 GHz band, with examples including the Synology RT6600ax and ASUS ROG Rapture GT-AX11000 routers. Support, thus far, has been lackluster due to the previously unresolved state of the 5.9 GHz band, but now that the matter is settled, equipment vendors should feel confident that there will be a market for 5.9 GHz-compatible equipment. There are several areas where the new spectrum will be the most attractive. The first is in the premium segment, whose raison d'être is to deliver cutting-edge technology to the users. Indeed, the two currently available routers listed above fit into this category. Going forward, premium vendors selling into the United States should look to offer 5.9 GHz support as a means to both further enhance the user experience and to differentiate their products from the competition. This also holds true for vendors of premium client devices. Another area where the additional spectrum will be highly valued is in mesh products, as 5850 – 5895 MHz occupies the sweet middle ground between data capacity and range, ideal for the backhaul of Wi-Fi mesh nodes.

To date, no other country has chosen to reallocate the 5.9 GHz band from ITS to unlicensed Wi-Fi, and while some may contemplate following the United States’ lead (as was the case for 6 GHz), the fact that neither Europe nor Japan previously chose to support the U-NII-3 extension (5725 – 5850 MHZ) does not bode well for U-NII-4. Thus, it is vital that industry bodies raise the issue with national communication agencies, highlighting the benefits of the spectrum for the Wi-Fi industry, and the economy more broadly. Communication agencies should also consider the advantages of more closely aligning the ITS strategies with the United States, such as the ability to attain greater economies of scale in equipment. In Mainland China, the national smart vehicle strategy is focused on harnessing C-V2X communication in the upper 20 MHz (5905 – 5925 MHz) of U-NII-4, leaving the possibility open for reallocation of the lower portion. In the European Union (EU), where U-NII-4 is currently divided between non-safety road ITS (5855 – 5875 MHz), safety-related road ITS (5875 – 5905 MHz), and safety-related rail ITS (5915 – 5935 MHz), it may make more sense to realign allocation closer to that of the world’s two single largest auto markets, the United States and China.

Although only the lower 45 MHz of the 5.9 GHz band has been reallocated by the FCC in this instance, in the future, if the remaining 30 MHz were also diverted for unlicensed use, it would be possible to seamlessly bridge the gap between the 5 GHz (5150 – 5825 MHz) and 6 GHz (5925 – 7125 MHz) bands, a tantalizing prospect that would vastly ease spectrum congestion and unlock multiple wider channels for consumers and enterprises. This possibility hinges on the progress of C-V2X technology. U.S.-based ITS bodies are hoping now that the FCC has settled the lower portion of the 5.9 GHz band, they will finally waive authority for the commencement of C-V2X operations in the remaining 30 MHz. There are a variety of C-V2X chipsets on the market from multiple vendors (including Autotalks, Morningcore, HiSilicon-Huawei, and Qualcomm), with Qualcomm’s 9150 C-V2X chipset receiving Radio Equipment Directive (RED) certification in Europe in early 2020, which opens the door for the commercial introduction of the technology to the continent. Yet, despite this piecemeal progress, without widespread automaker support for the technology, C-V2X will struggle to get off the ground. And with the bandwidth demands of Wi-Fi only set for continued growth, if V2X does not move into higher gear in the not too distant future, we may also witness the FCC reallocating the remainder of U-NII-4 for unlicensed use. Thus, those in the Wi-Fi industry should also keep one eye on the C-V2X market for foresight on what the future holds for U-NII-4.