15
Projecting the DECT network
Alternative calculation for small systems
For smaller systems, an approximate evaluation of the traffic volume can be sufficient.
Examples:
The traffic volume is evaluated for every area as "low", "medium" or "high". The evaluation
specifies the number of handsets that can conduct calls simultaneously as a percentage:
Hotspots
A hotspot is an area in which more calls than average are conducted simultaneously, e.g.,
open-plan offices or other areas where there are a lot of handsets in a small space.
You can cover such areas with several base stations since the DECT bandwidths in the cov-
erage areas of neighbouring base stations add up. The DECT standard provides 120 radio
channels that can be shared by several base stations. In practice, however, approximately
only one quarter of these radio channels can be used without special measures, since the
neighbouring channels interfere with one another. This results in a practical value of a
maximum of 30 simultaneous connections. With a maximum of eight handsets per base
station, this means that four Gigaset N720 IP PRO base stations would be required.
If we assume that a maximum of 50% of the available handsets are making a call simulta-
neously in a hotspot, 60 handsets can be used with four base stations.
If interference frequently occurs at a hotspot or more than 30 connections are required
simultaneously, the following measures are possible:
u
Distribute the base stations that cover the hotspot as widely as possible at the bound-
aries of the hotspot so that they are as far away from each other as possible and mutual
interference is minimised.
u
If this measure is not sufficient, use walls or other suitable means to diminish the
strong signals.
u
It might also be helpful, if the circumstances at the location allow, to arrange the base
stations in the shape of a ball, i.e., cover the hotspot through floors and ceilings.
When optimising the coverage of the hotspot areas, make sure that handsets do not sud-
denly occupy the call channels of the hotspot base stations that were previously supplied
by other base stations. When establishing a connection, handsets always occupy chan-
nels of the base station that provides the strongest signal. Therefore, moving the hotspot
base stations may affect other base stations and you may have to relocate the base sta-
tions of the entire network.
Evaluation
%
Maximum number of handsets that can be
operated from one base station
Low
Approx. 10%
80
Medium
Approx. 25%
32
High
Approx. 50%
16
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