Wi-Fi user experience: The impact of 802.11k, r and v
The ongoing evolution of Wi-Fi continues to explore higher speeds, but network manageability and Wi-Fi user experience are also becoming more important.
This is partly a factor of how dependent users are on Wi-Fi, both in the enterprise and the home. Last year, 60% of mobile data traffic was offloaded onto the fixed network via Wi-Fi or femtocells – about 10.7 exabytes per month, according to Cisco’s Visual Networking Index. Cisco predicts that by 2021, 50% of all IP traffic will be Wi-Fi (30% will be carried by fixed networks and 20% via cellular networks). Parks Associates recently found that domestic smartphone users reported a 40% increase in their monthly Wi-Fi data consumption last year. Wi-Fi usage increased fster than mobile data usage, and more than two-thirds of smartphone users consumed more than 3 GB per month.
Kevin Robinson, VP of marketing for Wi-Fi Alliance, said that there has been a gradual shift in Wi-Fi standards from a focus on top-end speed performance, to Wave 2 of 802.11ac being an “inflection point” for an increased focus on improving network capacity, efficiency and manageability. “The next set of standards you’ll see coming out from the industry will continue to be focused on manageability,” Robinson said. He pointed specifically to IEEE’s 802.11k, 11r and 11v features that address chaotic environments (such as transportation hubs) and steering Wi-Fi clients to less-congested, nearby APs automatically, depending on network conditions, as well as capabilities to better transition from AP to AP and network to network with very rapid handovers. There is also an emphasis on shortening authentication time, he added, particularly on returns to an already-known network.
Robinson told RCR Wireless News that 802.11k, r, and v are underlying technologies for an upcoming Wi-Fi Certified program from Wi-Fi Alliance. “Many silicon vendors already support the functionality and mobile and infrastructure vendors have implementations in the market, but Wi-Fi Alliance expects broad industry adoption once the certification program is launched,” he added.
“K, R and V are all about how to hand off the client so that the client can roam from one access point to another more gracefully or more easily,” said Sundar Sankaran, VP of engineering at Ruckus and lead for its access point platform engineering team. “More and more clients are supporting K, R and V right now, and that’s the reason you’re hearing more about it.”
Here’s a quick run-down of how each of these features provides a better Wi-Fi user experience:
802.11k: Sankaran said that in a situation where a Wi-Fi client is surrounded by many access points, it has to decide which AP is best for it to connect to. Clients typically send out probe signals to determine this, and the “best” AP changes as the user moves, based on signal strength. 802.11k enables the client to ask one AP about the other APs in the network — a neighbor list — and the client then makes use of that list in order to decide which AP to connect to, rather than sending probe signals.
802.11v: This feature enables client steering. Normally, Sankaran said, a Wi-Fi client and an AP can both do some amount of measuring the signal environment and exchanging information to determine that “next best AP” for the client to connect to as it moves through the network. 802.11v enables an AP to warn and then force a client with a fading signal to disconnect, while providing information about other APs that the client can utilize that may be more lightly loaded or provide better signal strength. This prevents so-called “sticky” clients from being able to cling to a preferred AP that is providing a poor signal or is congested.
802.11r: This feature is also known as “fast roaming.” Sankaran said that in terms of authentication, once a device is authenticated on a Wi-Fi network, 802.11r provides some short-cuts on authentication among APs on the same network — so the network and device aren’t basically trading the same :handshake” information back and forth every time a client connects to a new AP within the network. The number of exchanges is reduced, he said, which means the roaming or reconnection time is also reduced, therefore improving the user experience.
In general, Sankaran said, the three features are meant to make roaming from AP to AP within a network much more seamless, so that packets aren’t dropped and disrupt sensitive and popular services such as voice over Wi-Fi calling and video streaming. They also improve network efficiency, so that a client is communicating with the closest AP rather than one that’s far away and enabling a better all-around experience for both itself and other Wi-Fi clients on the network.
“A lot of this is about making the experience better, and the network in turn more efficient,” Robinson said. “I think those type of capabilities are going to open up a number of different services that an operator could provide. … What most people are thinking about are some of the capabilities around how does the industry provide improved Wi-Fi as a technology, so that it acts more in a way that carriers can easily manage it – that they can have more control over spectrum use, load balancing and they can provide a more consistent experiences to their end users,” Robinson said.
