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Why the 802.11k and Neighbor Report are Important?

A lot of air time (pun intended) has been provided for the PHYsical layer amendments to the 802.11 standard. These would include 802.11n, 802.11ac, 802.11ad, and others. These amendments tend to get a lot of publicity because they have increased the speed/throughput of 802.11 over the years (from 1-2 Mbps in 1997 for the original 802.11 spec to “gigabit” in 2013 with the 11ac and 11ad amendments).

But what about those amendments that simply aren’t as “sexy” and provide only MAC layer enhancements? Aren’t these important too?

The answer is YES and in this short series of blogs, we’ll spend some time looking at the lesser known but undeservedly underappreciated amendments to 802.11, especially 802.11k, 802.11r, and 802.11v and the features/benefits they provide.

This first blog will explain the basics of 802.11k “WLAN Radio Measurements” and will specifically zoom in on the Neighbor Request/Report.

Wireless LAN Radio Measurements (802.11k)

Wireless Local Area Network (WLAN) Radio Measurements can enable any device, AP or client, with the capability to better understand the environment in which it is operating. A variety of requests can be generated for which the device receiving a request can respond with a report.

As one example, an AP could ask a client “how well are you hearing me?” using a Link Measurement request. The client would respond with a Link Measurement report (conversely, a client could ask an AP “how well are you hearing me?”).

Since the ability to measure and collect information is provided, a device submitting a request can make a better informed decision as to its “next steps” in adapting to/compensating for the dynamics of the WLAN environment.

Information obtained from a measurement and/or report can be made available to upper layers of the measuring and/or requesting device where it may be used for a range of applications. Such applications may be engaged in attempting to preserve the QoE (Quality of Experience) for the end user.

As one example, in order to preserve the QoE for applications such as VoIP and video streaming, WLAN Radio Measurements may be used by client device to collect information from the AP prior to that client device disassociating from one AP and reassociating to a new AP. This can dramatically speed up reconnecting from one AP to another AP in the same WLAN.

802.11k describes the following measurements: Read More »

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Wi-Fi Roaming 101

Wi-Fi roaming is often a tumultuous subject.  The crux of the issue is, with Wi-Fi the roaming decision is left to the client.

In the recent years, there have been great strides in improving Wi-Fi roaming with the creation of standards-based roaming technologies.  Cisco first pioneered fast roaming many years ago with CCKM (Cisco Centralized Key Management), which was the foundation for 802.11r.  11r which was ratified by the IEEE in 2008, allows for fast roaming, even on a secure 802.1X SSID.  With 802.11r it is possible to roam without disruption during a voice or video call.

While client support of 802.11r is largely lacking in the laptop space,  there is large support in the smartphone realm.  Apple iOS devices have supported 11r since iOS 6 (  The recent Samsung smartphones, such as the Galaxy S4, S5, and Note 3, also support 11r.

Note: Some non-802.11r clients can react adversely when connected to an 11r WLAN.  The current recommendation from Cisco is to have a separate WLAN for 802.11r clients.

802.11k is another amendment from the IEEE that helps to improve roaming.  802.11k provides a whole slew of information to the client, which allows the client to understand the RF environment and make an informed roaming decision.  This information can include channel load and AP neighbor lists.

11r and 11k help, however, that does not mean the infrastructure is irrelevant in the roaming picture.  With the help of a model train, we did some testing to figure out just how much impact the infrastructure could have.  We compared Cisco to one of our competitors, whom we will call Vendor A.

This video summarizes the results and shows the train in action, or continue reading for more details:
Read More »

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