FCC Votes to Open Up 6 GHz Band for Wi-Fi

Over the next decade, Wi-Fi faces a number of difficult challenges. Key among them are the growing demands being placed on Wi-Fi networks, leading to increased congestion, performance limitations, and reduced quality of service (QoS). New Wi-Fi standards such as 802.11ax (Wi-Fi 6) are helping to address some of these challenges; however, there is an increasing acknowledgement that the existing unlicensed spectrum available for Wi-Fi will be insufficient in addressing the future needs of the Wi-Fi ecosystem. Last year, leading companies who are invested in the Wi-Fi ecosystem—including the likes of Broadcom, Cypress, Intel, Cisco, MediaTek, Google, Apple, and Facebook—came together to press the U.S. Federal Communications Commission (FCC) on the need for unlicensed spectrum in the 6 GHz band (i.e., 5925–7125 MHz) to be opened and utilized by Wi-Fi technologies. In anticipation of regulatory action, the Institute of Electrical and Electronics Engineers (IEEE) 802.11ax Task Group amended the Project Authorization Request (PAR) for 802.11ax to expand the scope of the covered frequency bands from 6 GHz to 7.125 GHz and cited the need for new operating classes to support the new gigabit-enabled channels. In June 2018, the Wi-Fi Alliance applauded the FCC’s intention to move forward with a rule on 6 GHz in the next few months, while in October 2018, the FCC voted in favor of opening up 1200 MHz of spectrum for unlicensed devices in the 6 GHz band. Alongside this development, in July 2018 the IEEE agreed to create a new Extremely High Throughput (EHT) study group for the next generation of Wi-Fi with a significant throughput increase over 802.11ax technologies. The key enabler of this increase will be the anticipated 1 GHz of additional unlicensed spectrum to allow wider 320 MHz channels and up to 16 spatial streams. Combined, these efforts will help ensure that Wi-Fi can improve its performance and grow over the next decade.

Enormous growth in Wi-Fi-enabled devices, increased per-user traffic demand, greater number of users per Access Point (AP), increased cellular offloading, higher density Wi-Fi deployments, growing use of outdoor Wi-Fi, heterogeneous device and traffic types, and a desire for more power and spectral efficiency are all major driving forces behind 802.11ax’s introduction. These same trends are all placing increasing demands on the already constrained unlicensed Wi-Fi bands.

In contrast to the past, where one or two Wi-Fi-enabled computing devices were connected to an AP at most, the connected home of today must support multiple Wi-Fi-enabled portable or desktop PCs, tablets, and smartphones. In addition to this, emerging devices such as wearables, virtual reality/augmented reality headsets, security cameras, voice-control front ends, connected Light-Emitting Diode (LED) light bulbs, smart thermostats, smart appliances, wireless speakers, set-top boxes, smart televisions, and game consoles are all increasingly enabled with Wi-Fi connectivity, with new devices coming to market each year. Some estimates anticipate the average household will contain as many as 50 Wi-Fi-enabled devices in the near future. According to ABI Research,the installed base of Wi-Fi-enabled devices is set to reach over 13 billion units by 2023. As a result, the 2.4 GHz band has become extremely congested. And, while the transition to dual-band 2.4 GHz and 5 GHz devices has alleviated some of these constraints (Wi-Fi device shipments are anticipated to increase to almost 4 billion annual shipments over the next few years), the 5 GHz band will become increasingly congested and suffer from similar throughput limitations and performance challenges. Moreover, the traffic of these devices is increasingly rapidly and is utilizing 5 GHz as opposed to 2.4 GHz due to the higher throughput requirements. According to ABI Research, over 80% of Wi-Fi chipset shipments will support 5 GHz by 2022, making that band increasingly congested. 60 GHz WiGig solutions will account for just 5% at this time—meaning there is little opportunity for offloading on to this band. While 802.11ax is also upgrading the 2.4 GHz band features, the majority of traffic will be utilizing the 5 GHz band going forward.

Unsurprisingly, the huge growth in Wi-Fi enabled devices has also seen an explosion in traffic growth. Many of the device types listed above are also using increasing amounts of data per device, ranging from streaming high-resolution music and videos, video calling, application and firmware updates, digital downloads, social networking, data-heavy web content, and online gaming, among others. This will only increase over time as the resolutions increase to 4K and 8K in the future and greater performance is demanded. The growth of cloud services and uploading of content to social media and sharing websites is also resulting in more uplink traffic. Cisco anticipates that Wi-Fi devices will account for almost half of all Internet Protocol (IP) traffic by 2020—up from 42% in 2016. A recent report commissioned by the Wi-Fi Alliance indicated that by as early as 2020, Wi-Fi networks will need significantly more spectrum in order to satisfy increased traffic demands. The report also indicated that by 2025, between 500 MHz and 1 GHz of additional spectrum at the very least would be needed to satisfy peak usage, with upper estimates placing this number between 1.3 GHz and 1.8 GHz.

As a result of this traffic explosion, cellular operators are increasingly looking to offload traffic to Wi-Fi. Similarly, consumers with limited data plans are deciding to connect to Wi-Fi when at home or in public areas to circumvent these limitations. To do so, however, the user experience must be comparable to that of the existing cellular network, and the Wi-Fi network must be able to accommodate this extra traffic. Cisco anticipates that mobile offload is set to increase from 60% (10.7 exabytes per month) to 63% (83.6 exabytes per month) by 2021, with 64% of the traffic to come from smartphones and 72% to come from tablets, and is forecasted to be offloaded onto Wi-Fi by 2021, placing additional burdens on the 5 GHz band.

Most deployments today are also now characterized by several overlapping Wi-Fi networks. Real-world performance is already beginning to suffer in these dense deployment areas and will continue as this transition to high-density environments continues. Further, with the 2.4 GHz band already congested and the growing transition to the 5 GHz band, interference from neighboring devices is significantly impacting performance, reducing overall throughput, increasing latency test errors, and ultimately reducing power consumption and reliability. Performance can no longer be improved by adding additional hot spots, as this only increases the chance of interference and collisions.

In the United Kingdom, communication regulator Ofcom made an additional 125 MHz of spectrum available for Wi-Fi by supporting the 5725–5850 MHz band (5.8 GHz) in 2017. A similar process is underway in Europe via the Electronic Communications Committee (ECC), who is also evaluating 6 GHz operation. This highlights a growing understanding of the need for greater unlicensed spectrum availability for Wi-Fi technologies.

The 802.11ax working group is currently determining how best to incorporate 6 GHz support into 802.11ax in anticipation of the spectrum becoming available. This will help pave the way for smoother adoption of 6 GHz chipsets and devices, if it is granted. The increased spectrum is also likely to form the foundation of the next EHT standard that goes beyond 802.11ax, with the primary objective of increasing throughput through wider 320 MHz channels, more spatial streams, and multiband aggregation.

One of the key challenges will be the availability of 6 GHz compatible chipsets and network infrastructure. As 802.11ax network devices are beginning to roll out without 6 GHz support, it may be some time before enterprises opt for a further upgrade that supports the additional band. It is also not clear whether additional band support will result in a considerable cost increase for devices that incorporate it. Companies such as Broadcom have already proposed that the 6 GHz band could be integrated into unified 5 GHz and 6 GHz chipsets that will reduce the cost of devices by eliminating the need for multiple chips in the same device. However, the devices themselves may need redesigns and additional features to best support the new bands. If the 6 GHz band is made available, then there is also the additional challenge of ensuring coexistence with other users of the band as well as ensuring that the technologies do not encroach upon incumbents—although Wi-Fi has traditionally been strong within this department.

The rollout of 802.11ax in conjunction with extra spectrum availability will enable better Wi-Fi service and performance than ever before. This will allow such Wi-Fi capabilities to scale up to the next billion devices and to enable the technology to support growth and traffic demands for the next decade. Support for 6 GHz could enable Wi-Fi to connect more users than ever before, improve overall network performance, improve outdoor performance, and enable new high-performance use cases and device types to be connected with very low latency. If additional spectrum is made available, it is anticipated by many stakeholders that the majority of station and AP devices going forward will have tri-band capabilities that support 2.4 GHz, 5 GHz, and 6 GHz. However, in the future, as Wi-Fi increasingly must be able to accommodate different device types and heterogeneous services (each with their own QoS requirements), the IEEE may need to focus more on more effective management of the spectrum resources through different approaches that extend beyond traditional increases in spectrum availability and additional bandwidth.