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Blog

Adaptive MIMO in the Era of 6GHz Wi-Fi

By James C. Chen, Vice President, Product Marketing & Line Management

Appeared originally in LightReading.com.

I. Introduction of 6GHz 
On December 17, 2018, the Federal Communications Commission (FCC) of the United States issued a Notice of Proposed Rulemaking (NPRM) that opens up a maximum of 1.2GHz of spectrum between 5.925GHz to 7.125GHz for unlicensed use. This development is unprecedented not only for the amount of free spectrum that wireless devices can now use, but also the addition of seven ultra-wide 160MHz channels for Wi-Fi applications. The newly released spectrum is over twice the amount currently allowed in 2.4GHz and 5GHz. And the additional channels allow for 10Gbps wireless networks to proliferate even in dense environments such as Multi-Dwelling Units (MDUs). It is obvious that 6GHz has the potential to usher in a new era for Wi-Fi computing. The FCC’s publication of the NPRM puts it on course for eventual legalization, by most accounts, towards the end of 2020. Other countries, such as those in the European Union and in Asia, will follow suit with their own adoption of 6GHz, most likely in 2022.

II. Market Adoption of New Wi-Fi 6, 6GHz Clients
While there is little doubt that the introduction of 6GHz is a great development, the mechanics of its adoption into everyday devices which we all have and love are a bit more complex. We can look at the adoption of Wi-Fi 5 (802.11ac) technology as a good model of what will most likely happen. The official 802.11ac specification was published by IEEE in December 2013. By the end of 2016, all of Apple’s iPhone products and most of Samsung’s smart phones such as the S, A and F series fully adopted 802.11ac. In the year of 2016, there were over 1.4 billion new mobile phones shipped with the majority (over 1 billion) being 802.11ac (Figure 1). If we apply this model for 802.11ax (Wi-Fi 6) client devices, it will also likely be approximately 3 years from when IEEE publishes the 802.11ax specifications (June 2020) to when there will be over 1 billion new client devices Wi-Fi 6, which will be mid-2023. However, with the addition of 6GHz regulatory approval, this timeline will most likely be slightly extended to the end of 2023, three years after the FCC fully legalizes 6GHz operation by end of 2020 (Figure 2).

Figure 1. Wi-Fi 5 (802.11ac) Adoption by Client Devices
Figure 2. Overall Timeline for Wi-Fi 6 and 6GHz Adoption

III. Solution Needed: Adaptive MIMO
With the introduction of 6GHz, it may be deceptively simple to assume that next generation Wi-Fi 6 infrastructure devices such as home gateways and access points launching in 2020 shall all be designed with a fixed architecture, one that dedicates a fixed 4x4 radio to each of the 3 bands: 2.4GHz, 5GHz and 6GHz (Figure 3). As previously stated, since there will be no meaningful quantity of 6GHz Wi-Fi 6 clients until the end of 2023 (at the earliest), any dedicated 6GHz circuitry inside these 2020 infrastructure devices will be mostly unused for a significant portion of the time - the cost and space associated to these new 6GHz components will essentially be wasted. However, infrastructure devices must be forward-looking as their replacement cycles tend to be longer than that of client devices. These two competing dynamics present an interesting dilemma for Service Providers and others who are considering the inclusion of Wi-Fi 6 with 6GHz support in their respective roadmaps.

Figure 3. Fixed, Triple Frequency 4x4 Design

The solution can be found in a technology called Adaptive MIMO. Adaptive MIMO was first introduced by Quantenna in June 2018 as a way for infrastructure devices to change their 5GHz MIMO configuration between one 8x8 radio and two 4x4 radios given specific use cases. However, this technology is an even more powerful solution as it can address the complex issue of 6GHz market adoption for Wi-Fi 6. Adaptive 6GHz MIMO means that one hardware design can adapt itself between one 8x8 5GHz and one 4x4 2.4GHz radios (configuration 1) and three 4x4 independent radios at 6GHz, 5GHz and 2.4GHz (configuration 2). When this design is deployed in 2020/2021, since there will be little (if any) 6GHz clients, the infrastructure device operates in configuration 1. By the end of 2023, when we project there will be approximately 1 billion new 6GHz clients sold, the infrastructure device operates in configuration 2. This adaptation can be controlled using intelligent analytics which determines the prevalence of 6GHz Wi-Fi 6 clients as well as their performance capabilities. It is important to note that Adaptive MIMO design incorporates a new, unique 5-7GHz FEM (Front End Module) that has very low insertion loss.

Figure 4. Adaptive 8x8 Design

IV. Looking Forward
The introduction of 6GHz is a truly significant event. While it offers remarkable improvements in upcoming 802.11ax (Wi-Fi 6) networks, it also has the ability to dramatically transform the wireless landscape. The next Wi-Fi standard, IEEE 802.11be, is set to establish 320MHz channel operation in the 6GHz band using up to 16x16 MIMO configuration on infrastructure devices. The combination of these developments can increase speed to over 40Gbps, offer previously unseen range performance, and lead to a new age of advance Wi-Fi applications. However, to get there, infrastructure devices must adopt intelligent and cost-efficient architectures, such as Adaptive MIMO.