War of the WiFi 6 GHz band to be decided by January

A standoff between the communications and energy sectors looms as the FCC looks likely to approve a spectrum-sharing proposal for WiFi in the 6 GHz band. However, the expansion of spectrum to additional wireless devices faces opposition from utilities with the backing of the US Department of Energy, forcing chip major Broadcom to spout the benefits that 6 GHz WiFi will bring.

WiFi chip makers believe the decision will lead to improved quality and capacity by avoiding interference from legacy devices, while the utilities players argue that sliding in WiFi alongside critical energy use cases will disrupt communications. However, the proposal will allow only devices supporting the latest WiFi 6 standard (802.11ax) to operate in 6 GHz, therefore removing any potential disruption from legacy devices operating in 802.11ac/n/g/a/b.

Broadcom argues that the abundance of 160 MHz-wide channels in the 6 GHz slice will increase throughput by more than two-fold over the 80 MHz channels found in 5 GHz spectrum. As a result, the latter suffers from significantly more congestion and interference. Range and latency are also improved dramatically, as shown by the bar chart below.

For managed services use cases such as high-bandwidth video applications operating in the 5 GHz band, the arrival of WiFi 6 is being heralded as the most important step forward in WiFi since its inception. The new standard includes latency-reducing techniques like OFDMA, while MU-MIMO increases capacity when serving a small number of high bandwidth clients.

Meanwhile, because 2.4 GHz is often congested with legacy clients, making the 6 GHz band available will extend the 5 GHz band to free up unprecedented capacity for gigabit broadband access, allowing WiFi 6 to serve next generation mission critical applications.

Broadcom warns however that what 6 GHz gains in throughput and latency, it lacks in range, dropping slightly below the 5 GHz range as illustrated in the graph.

The FCC recently underscored its intent to release the full 1.2 MHz of spectrum in the 6 GHz band to WiFi and other unlicensed use cases. Chairman Ajit Pai stated, “This band is currently populated by microwave services that are used to support utilities, public safety, and wireless backhaul. But studies have shown that sharing this band with unlicensed operations is feasible – and can put massive amounts of new spectrum into the hands of consumers.”

The WiFi Alliance meanwhile has been busy lobbying for additional unlicensed spectrum for WiFi in the 5 GHz and 6 GHz bands, with members developing a certification program for WiFi devices operating in the 6 GHz spectrum.

Elsewhere, WiFi Alliance members are exploring the use of 60 GHz fixed wireless to deliver the “last-mile” connection for multi-gigabit internet. Alliance members are currently collaborating to define the interoperability of 60 GHz Fixed Wireless devices at the MAC/PHY level.

“As the full 6 GHz band is made available for unlicensed use – with multiple 160 MHz-wide channels – the WiFi 6 consumer experience will be turbocharged for the gigabit home and AR/VR,” Vijay Nagarajan, VP of Wireless Communications & Connectivity at Broadcom, said recently.

Assuming the FCC’s proposal is ratified, it will be important for WiFi vendors to be able to support all three of the standard’s bands, 2.4 GHz, 5GHz and 6 GHz, in a single unit. To this effect, Faultline has referenced technology in the past such as a chipset from full duplex radio technology developer Kumu, promising to suppress the self-interference that could occur in such devices, especially because there will be only a narrow guard band between the two higher frequencies.

That guard band is insufficient for a conventional RF filter to handle, according to Joel Brand, Kumu’s VP of product management. The company’s chip can be used to enhance the performance of those filters, or replace them completely.

Reports suggest that regulators could make a 6 GHz decision as soon as January 2020. The concern now, however, according to Law360, is that the utilities are belatedly stepping up their opposition in light of new evidence apparently showing interference to critical applications.

Specifically, opposition has said 6 GHz spectrum is “used for critical situational awareness, to underpin safety functions, and to enable crews to safely repair and restore services after storms.” Utilities groups also argue that it risks interference relating to “the greater deployment of distributed energy resources such as solar or battery storage, smart meters, and other technologies to enable grid modernization.”