As the leaves change, I find myself hunched over my desk absorbing all the new features in IEEE 802.11be. Of these features, MLO (Multi-link Operation) is the most-discussed feature I've seen. However, there's other features that deserve the spotlight. Other new 802.11be features that may change the protocol landscape include: -SCS (Stream Classification Service) with QoS Characteristics
-EPCS (Emergency Preparedness Communication Service)
-Preamble Puncturing
-R-TWT (Restricted Target Wake Time)
-Multiple RUs
Most of these are aimed at improving service quality, link stability, and efficiency. That begs the question: will people favor Wi-Fi 7 for these improvements over cellular and IoT protocol solutions?
I will be referring to a great book written by the best and brightest at Cisco throughout this post: "Wi-Fi 7 In Depth: Your guide to mastering Wi-Fi 7, the 802.11be protocol, and their deployment". Run, don't walk to get this book. It outlines a practical understanding of how we may see these new features develop in the market. O'Reilly subscribers may already have access to it today.
Why Wi-Fi 7 competes more with 5G Cellular
Competitive improvements mainly stem from features affecting Wi-Fi's stability and efficiency. The book shares on preamble puncturing in Chapter 3 that "802.11ax introduces the idea of preamble puncturing"(2), but 802.11be improves on this by allowing for interference detection within the channel. Instead of wasting the whole channel for a smaller section impacted by interference, the STA will skip preamble transmissions around the interference. Many of Wi-Fi's challenges stem from it's unlicensed use and dancing around incumbents, so we shall see if this gets it closer to 5G stability.
Multiple RUs (Resource Units) builds on OFDMA capabilities introduced in 802.11ax. The book outlines in Chapter 4 that in Wi-Fi 6 "Each STA has an RU allocation, whose size is determined by the AP[..] This structure can be wasteful for small channel bandwidths[...]"(1). Adjusting for differently sized and non-continuous RUs, making the entirety of channels more useful to clients. Many people have said that OFDMA and MU-MIMO from 802.11ax were lackluster in practical improvements so we will see if the former problem is solved with Multiple RUs.
Why Wi-Fi 7 competes more With IoT Protocols
As opposed to the pure efficiency improvements that compete with cellular, Wi-Fi 7 outlines service quality improvements such as SCS and R-TWT that aim to resolve challenges with low-bandwidth clients. Chapter 4 mentions that SCS provides QoS Characteristics (QCs) that include attributes like "maximum delay, periodicity, minimum throughput, and reliability"(1) for client applications. In short, clients can better dictate the minimum attributes they need for a quality experience per service it uses. This should align better with vertical specific devices that maybe need extremely low bandwidth and don't want to waste the scheduling capacity (IoT) or voice devices that need medium bandwidth, but extremely low latency.
R-TWT on the other hand is "designed to provide predictable latency performance for low-latency flows[...] by defining enhanced channel access protection" (Chapter 7, 1). These protection and reservation mechanisms should prevent STAs that truly don't need low-latency service from using them. I am curious if reserving these time-slots can result in over-allocation in any scenario in high-density deployments.
Both of these features at their core existed before 802.11be so we will see if these improvements enable client adoption. IoT protocols are known for supporting large numbers of low-bandwidth clients. Low-latency environments continue to have challenges in Wi-Fi deployments today, but may not overlap so much with the IoT protocol market. Wi-Fi continues to evolve into a client swiss army knife, but can it be good at everything?
Will we see shifts in protocol adoption?
I'm excited for features such as Preamble Puncturing and Multiple-RUs. These seem like "no-brainer" improvements to the protocol with less complexity than some others introduced in the standard. For other features such as SCS w/ QC and R-TWT, it's usefulness boils down to:
-How practical is this feature to implement for the client vendors?
-What does the Wi-Fi Alliance require for Wi-Fi 7 certification?
The WFA's Technology Overview paper (2) shows all these features part of Wi-Fi 7 certification so far. I think client vendors may be slow to adopt Wi-Fi 7 certification at all if any of these requirements pose significant implementation complexity. That could be why we just saw the release of a Wi-Fi 7 iPhone, and have yet to see a Wi-Fi 7 MacBook, for example. If client vendors can overcome these hurdles, Wi-Fi 7 provides excellent improvements with a technology that is readily accessible for businesses compared to its competitors. There are still use cases where cellular or IoT protocols still make more sense such as extremely large, outdoor coverage areas. I would pay attention to the overlapping segments such as indoor use or small-area outdoor deployments.
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Cover Photo by Rajesh S Balouria (Pexels.com)
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