This visualization shows what format of 802.11 frames (also
is being used in the given WLAN area. Wi-Fi networks use three
Non-HT: This is a legacy frame format used by 802.11 a/b/g
HT-mixed: This is a frame format introduced in the 802.11n
standard. It uses a protection mechanism that allows 802.11n
devices to coexist with legacy 802.11 a/b/g devices, including
those that do not belong to your WLAN.
HT-Greenfield: This is a frame format introduced in the 802.11n
standard, too. Unlike in HT-mixed mode, devices operating in
Greenfield mode assume that there are no legacy 802.11 a/b/g
stations around using the same or adjacent channels. 802.11 a/b/g
devices cannot communicate with Greenfield devices. Rather, their
packets will collide, causing problems for both parties.
VHT: This is the latest frame format introduced in the 802.11ac
standard. This format is used in the 5 GHz band only. It uses a
protection mechanism that allows 802.11ac devices to coexist with
legacy 802.11a and 5 GHz 802.11n devices, including those that do
not belong to your WLAN.
Frame format is shown for the AP that has the strongest signal in
the given map area among the APs selected for analysis. This mimics
the roaming behavior of client adapters that connected to the
strongest AP. While other audible APs may use other frame formats,
a typical adapter will connect to the AP with the strongest signal.
You can deselect one or several of the selected APs to see frame
formats for less strong APs.
Among the three pre-802.11ac frame formats, the best throughput is
provided by HT-Greenfield. In HT-mixed format, protection
mechanisms that ensure coexistence with legacy equipment reduce
throughput. However, it should be noted that as per the 802.11n
standard, support for HT-Greenfield frame format is not mandatory,
and currently, few APs support it. In the realm of 802.11ac, VHT is
the only available format.
Double-clicking on the Frame Format legend on the status bar allows
you to configure the color scheme and change its value
If you do not see the frame formats that you expect to see, the
following solutions are suggested:
Check your AP configuration. If you are using 802.11n equipment,
see if Greenfield mode is available, if HT-Greenfield frame format
is what you want. Note that some APs have the “802.11n only”
option, but this option does not necessarily mean that
HT-Greenfield frame format will be used. Rather, switching this
option on may simply disable legacy data rates.
Your AP's ability to send frames in HT-Greenfield format depends on
the wireless environment. A Greenfield-enabled AP may fall back to
HT-mixed format in some situations (e.g., when a non-802.11n device
connects to the AP or when other non-Greenfield APs are detected
nearby). Because of the changing environment, the site survey
results regarding the frame format may change from time to time.
Perform site surveys regularly.
If you are using legacy 802.11 a/b/g equipment, consider upgrading
to 802.11n or 802.11ac.
Remember that VHT is not available in the 2.4 GHz band.