Why Wi-Fi Needs the 6 GHz Band

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By Andrew Zignani | 4Q 2018 | IN-5244

Over the next decade, Wi-Fi faces a number of difficult challenges. Key among them are the growing demands being placed upon Wi-Fi networks leading to increased congestion, performance limitations, and reduced quality of service. New Wi-Fi standards such as 802.11ax are helping to address some of these challenges; however, increasingly there is an acknowledgement that the existing unlicensed spectrum available for Wi-Fi will be insufficient in addressing the future needs of the Wi-Fi ecosystem.

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Increased Demands on Wi-Fi Posing Difficult Challenges 

NEWS


Over the next decade, Wi-Fi faces a number of difficult challenges. Key among them are the growing demands being placed upon Wi-Fi networks leading to increased congestion, performance limitations, and reduced quality of service. New Wi-Fi standards such as 802.11ax are helping to address some of these challenges; however, increasingly there is an 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 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 (5,925 to 7,125 MHz) to be opened up and be utilized by Wi-Fi technologies. In anticipation of regulatory action, the 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 rulemaking on the 6 GHz in the next few months, while 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 additional 1 GHz of unlicensed spectrum to allow wider 320 MHz channels and up to 16 spatial streams.

Why Does Wi-Fi Need the 6 GHz Band?  

IMPACT


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/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 more than 13 billion units by 2022. As a result, the 2.4 GHz band has become extremely congested. While the transition to dual-band 2.4 GHz and 5 GHz devices has alleviated some of these constraints, because 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 utilizing 5 GHz as opposed to 2.4 GHz due to the higher throughput requirements. According to ABI Research, more than 80% of Wi-Fi chipset shipments will support 5 GHz by 2022, making that band increasingly congested. 60 GHz 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, including 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 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 between 1.3 GHz and 1.8 GHz.

As a result of this traffic explosion, cellular operators are increasingly looking to offload traffic on 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. In order 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/month) to 63% (83.6 exabytes/month) by 2021, with 64% of traffic from smartphones and 72% from tablets 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. Furthermore, 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 and errors; and ultimately reducing power consumption and reliability. Performance can no longer be improved by adding additional hotspots because 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 5,725 to 5,850 MHz band (5.8 GHz) band in 2017. A similar process is underway in Europe via the Electronic Communications Committee (ECC), which is also evaluating 6 GHz operation, highlighting a growing understanding of the need for greater unlicensed spectrum availability for Wi-Fi technologies.

Challenges and Recommendations

RECOMMENDATIONS


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 networking infrastructure. As 802.11ax networking 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 and 6 GHz chipsets, which will reduce the cost of devices by eliminating the need for multiple chips in the same device. However, devices themselves may need redesigns and additional features to best support the new bands. If the 6 GHz band is made available, there is also the additional challenge of ensuring coexistence with other users of the band and ensuring that technologies do not encroach upon incumbents, though 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, allowing it to scale up to the next billion devices, and enable the technology to support growth and traffic demands for the next decade. 6 GHz support 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, many stakeholders anticipate 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.