Description varix 200/varix 14 (DECT)
2 - 11
2 Planning a cordless communications network
Besides ensuring that the entire area is covered by the FPs’ footprints, the predicted amount of
telephone traffic must be taken into consideration. It may become necessary to install additio-
nal FPs.
- The following table lists the number of FPs required per radio cell. It is assumed that the
number of PPs within the radio cell is known.
- No more than 4 FPs may be installed within a cell.
-
If the number of necessary FPs exceeds 4, then the radius of the radio cell has to be
decreased and the locations of all the other radio cells will need to be modified.
Fig. 2.2
Number of PPs for n FPs per radio cell and 0.15 Erlang per PP
2.4.2
Ranges
The average horizontal range of a DECT hop inside
an office building is between 10 and 30 metres
(radius). Inside large enclosures, e.g. exhibition halls
and factories, the limit is 100 to 200 metres. Out in
the open, the size of a cell can increase to between
300 and 500 metres. These figures can vary greatly,
depending on the materials used in a building (walls
and ceilings made of reinforced concrete, wood
etc.). Metal walls and large metal cages reflect all
signals, putting significant limitations on the system's
capabilities within these areas. Rooms in hospitals
where X-rays are used and which are protected by lead screening, as well as computer
rooms in banks which are protected against sources of electronic interference, are also
screened against DECT signals.
Probability of a busy line
Number of FPs
2%
1%
0.5%
0.1%
1
7
5
4
3
2
24
20
18
13
3
44
39
35
28
4
65
59
54
44
10 m - 30 m
100 m - 300 m
antenna
outdoors
indoors
Fig. 2.3
