Cisco 7925G Deployment Manual page 45

For rugged environments, it is recommended to select an access point platform that requires external antennas (e.g. Cisco
1602e, 2602e, 3502e, 3602e Series Access Points). It is also important to ensure an antenna type is selected which can
operate well in rugged environments.
Access Point Placement
It is crucial that line of sight to the access point's antennas is maximized by minimizing any obstructions between the Cisco
Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G and the access point. Ensure that the access point and/or
antennas are not mounted behind any obstruction or on or near a metal or glass surface.
If access points with integrated antennas (e.g. Cisco 1040, 1130, 1140, 1602i, 2602i, 3502i and 3602i Series Access Points)
are to be used in some areas, then it is recommended to mount those access points on the ceiling as they have omni-
directional antennas and are not designed to be patches.
Frequency Band
As always, it is recommended to use 5 GHz. Use of 2.4 GHz, especially when 802.11b rates are enabled, may not work
well.
If 2.4 GHz must be used in some areas, either due to decreased 5 GHz coverage in some areas or due to range requirements,
then it is recommended to set the Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G to Auto-a mode, which 5
GHz will be the preferred band, but can roam to 2.4 GHz as necessary.
For the 5 GHz channel set, it is recommended to use a 8 or 12 channel plan only; disable UNII-2 extended channels if
possible.
Data Rates
The standard recommended data rate set of 12-54 Mbs may not work well if multipath is present at an elevated level.
Therefore, it is recommended to enable lower data rates (e.g. 6 Mbps) to operate better in such an environment.
If 5 GHz is used for VoWLAN only, then it is also recommended to disable data rates above 24 Mbps (i.e. 36, 48, 54 Mbps)
to increase first transmission success (e.g. 6 as mandatory, 12 and 24 as supported). If 5 GHz is also used for data, video or
other applications, then is suggested to keep the higher data rates enabled (e.g. 6 as mandatory, 9, 12-54 as supported).
Transmit Power
Due to the potential of elevated multipath in rugged environments, the transmit power of the access point and Cisco Unified
Wireless IP Phone 7925G, 7925G-EX, and 7926G should also be restricted. This is more important if planning to deploy
2.4 GHz in a rugged environment.
If using auto transmit power, the access point transmit power can be configured to use a specified range (maximum and
minimum power levels) to prevent the access point from transmitting too hot as well as too weak (e.g. 5 GHz maximum of
16 dBm and minimum of 11 dBm).
The Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G will utilize the access point's current transmit power
setting to determine what transmit power it uses for transmitted frames when DTPC is enabled in the access point's
configuration.
Fast Roaming
It is recommended to utilize CCKM for fast roaming. Enabling CCKM also reduces the number of frames in the handshake
when roaming to only two frames. Reducing the number of frames during a roam, increases the chances of roam success.
When using 802.1x authentication, it is important to use the recommended EAPOL key settings. See the WLAN
Controller Advanced EAP Settings section in Configuring the Cisco Unified Wireless LAN Controller and Access
Points for more information.
Quality of Service (QoS)
Need to ensure that DSCP values are preserved throughout the wired network, so that Cisco Unified Wireless LAN
Controller and access points can set the WMM UP tag for voice and call control frames correctly.
Beamforming
If using Cisco 802.11n access points, then Beamforming (ClientLink) should be enabled, which can help with client
reception.
See the Beamforming (ClientLink) section in Configuring the Cisco Unified Wireless LAN Controller and Access
Points for more information.
Cisco Unified Wireless IP Phone 7925G, 7925G-EX, and 7926G Deployment Guide
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