Installation guide

TD 92408EN
9 December 2011 / Ver. G
System Planning
Ascom VoWiFi System
8
2.2.3 Customer Is Adding 802.11n APs and Is Also Keeping Old APs
It is not uncommon that, when upgrading a b/g WLAN with a second radio for 5.0 GHz, new
APs have to be in
stalled (if there is no slot reserved in the AP for a second radio).
Most modern APs include support for the 802.11n standard. When a second AP is installed,
old
APs may be left in place to ensure that there is no interruption of the current service. The
new 5.0 GHz network can then be tuned and configured for n-support and HT-enabled
devices can be moved over to the new WLAN.
This also requires additional cable drops
and PoE swi
tch ports, running two systems side by
side.
Customer buys new APs for the a/n-radio only and keeps the old single-radio b/g APs
intact.
New APs set to use only the a-radio. High throughput (HT) only in Greenfield mode.
b/g old AP a new AP Comment
Voice + data
(legacy)
20 MHz only
Data(HT)
40 G
Hz only
This may be a solution when up
grading to 802.11n.
All laptops can then benefit from the HT speeds of the a/n
radio, and the h
igher amount of channels to choose from.
Non-HT clients like VoWiFi Handsets st
ay on the o
ld APs.
There is no need for 802.11n support on the b/g band.
Upgrade old b-cl
ients if possible to g-clients.
Customer buys new APs for the a/n-radio as an extension and keeps the old dual-radio
b/g/a APs
intact.
The customer adds a new area to its existing WLAN, for example an extra building, and
wants to benefit from 802.11n in the new building.
b/g/a old AP a/g new AP Comment
Voice + data
(legacy)
20 MHz only
a-radio:
Data(HT) an
d
Greenfield
mode
40 G
Hz only
g-radio:
Voice + data
(le
gac
y)
20 MHz only
All laptops can then benefit from the HT speeds of the a/n
radio, a
nd the h
igher amount of channels to choose from.
Non-HT clients like VoWiFi Handsets
must
be supported on
both the old and new APs.
There is no need for 802.11n support on the b/
g band.
If possibl
e, upgrade old b-clients to g-clients.
Voice (g) Data This allows the 2.4 GHz band to be dedicated to voice
and all data clien
ts, if possible, are moved to the a-band.
b/g a Comment