DAP deployment rules and requirements 37
• Do not install basestations in spaces that transport air, such as ducts
or plenums.
• Do not mount basestations on the ceiling.
Coverage and signal strength calculation
Synchronization between DAPs requires sufficient radio signal strength
between DAPs. The following items are relevant for the signal strength
for synchronization.
• To achieve a good voice quality, the minimum signal strength at the
receiver in the handset and DAP must be -72 dBm. This includes a
margin of -10 dBm for fast fading dips.
• Synchronization is possible if the strength of the received signal from
another DAP is -80 dBm ... -85 dBm. This is adjustable.
• In an open area, the distance is doubled if the received signal strength
is 6 dB lower. This means that at a minimum signal strength for good
voice quality of -72 dBm and a distance X, the signal strength at
the double distance, 2x, is -78 dBm. See Figure 9 "Signal strength
considerations" (page 37).
Figure 9
Signal strength considerations
• In an open area there is more than sufficient signal strength for
synchronization. The expected level at the double distance is -78 dBm.
The required level is -80 dBm ... -85 dBm. This leaves a safely margin
of 2 ... 7 dB.
• Objects between the DAPs can introduce loss. Also, many objects
cause reflections that let the signal reach the DAPs through other path
with sufficient signal strength.
• In rare cases, factors in the surrounding environment can cause
the error rate in the received frames to be temporarily much higher
Nortel Communication Server 1000
SIP DECT Fundamentals
NN43120-123 01.07
6 January 2009
Copyright © 2008-2009 Nortel Networks
.
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