Installation guide

TD 92408EN
9 December 2011 / Ver. G
System Planning
Ascom VoWiFi System
40
The two handsets from Ascom are not to be considered as clients with the same
performance profile. Both are branded with the Ascom logo but must be considered as two
cousins in the Ascom family or as if they were phones from different vendors.
A.6.4 Replacing All Handsets
If the decision is to for
k
lift the VoWiFi installation and replace all i75 VoWiFi Handsets with
i62s then the project must be considered as a total new installation and the whole process
of doing a site survey etc. has to be repeated. This also of course includes the confirmation
of voice quality achieved and the roaming behavior by doing a walk-through test while in
call mode.
This is even more important if the i62 will be running in the
5 GH
z band, where the cell size
is normally smaller, and power settings lower which will require that APs are placed in a
more dense pattern.
A.6.5 Replacing all i75 VoWiFi Handsets with i62 VoWiFi Handsets
Even if the i62 VoWiFi Handset is mainly based on the same s
o
ftware as the i75 VoWiFi
Handset, the two VoWiFi Handsets have different characteristics. When a total replacement
of i75 VoWiFi Handsets with i62 VoWiFi Handsets is proposed, there are several issues that
must be considered.
Features like the use of certificates, baselinin
g
and license handling are only supported by
the latest software releases of the PDM and the Device Manager. This requires an update of
the software in the Unite modules used for management.
There are also some differences in the way the i62 VoWiFi Handset interacts with
other
Unite modules. This requires a careful investigation that solutions designed for a customer
still functions as expected, for example Interactive Messaging (IM) or Alarm features.
The deployer should also carefully test that the VoIP an
d WLAN protocols work as expected.
Shortly said; there may always be some incapability at a site due to the complexity of the
installation.
When deploying the new i62 VoWiFi Handset, the information describe
d elsewhere in this
documents should be taken into account.
Typically there are four things that should be evaluated using the tools in th
e VoWiFi
Handset:
• Coverage area co-channel interference
• Roaming candidates
• Roaming performance (where an
d when ro
aming occurs)
• Voice quality in walk and talk test
This can be done by measurement only, and of course l
istening to real calls.
Note: If the i62 VoWiFi Handset is replacing the i
75 VoWiFi Handset and the decision is to
move voice over to the a-band, a new site survey must be performed even if the a-radios are
located in the same AP as the b/g radio. The reason for this is explained in 5 Basic Cell
Planning on
page 18.
A.
6.6 Replacing a Few Handsets
If a current existing customer is adding i62s as replacements fo
r i75s that are broken, or if
there is an expansion of the system, then the design becomes even more complex.
Without a good understanding of the behavior of the two handsets it is difficult
to compare
RSSI measurements if done side-by-side.