Aastra NeXspan C, Installation Manual

Page: 17 / 196

AMT/PTD/PBX/0020/2/4/EN 01/2007 Page 17
Examples of representation of these measurements:
The graphs below show the change in the RSSI level according to the distance from the base
station studied. The graphs are linked to the chosen direction. To determine whether the overlap
of the two radio areas is correct, you must have the two measurements in both directions for the
plan concerned (for example on horizontal axle of base station 1, right direction – base station 2,
left direction). The graphs are shown side by side to be able to check that the intersection point
of the two curves is situated above the lower level (3DH) of the area limit. It is also necessary to
make sure that the CRCs of each curve are on each side of the intersection point.
These conditions allow you to ensure quality of service for roaming and handover.
• Case of theoretical limits
• Case of two base stations without handover
RSSI (Hex)
60
Bx: base station studied
Dn: direction chosen
60
50
40
30
30
40
50
3D
CRC Err
3D
Err CRC
Graph of Bx for direction Dn
2
RSSI (Hex)
bottom
distance
Graph of Bx for direction Dn
1
BS
top
right
back
front
storey left
60
0
ou
3D
CRC Err
The vertical axis represents the RSSI level of the base station
studied, as seen by the mobile (in mode DEBUG)
The horizontal axis represents the distance between the mobile
and the base station studied
The lower level 3D (hex) that determines the limits of the area if
there is no CRC error
The point of the curve from where the CRC is failed
RSSI (Hex)
60
distance
Bx: base station
studied
Dn: direction chosen
60
50
40
30
30
40
50
3D
CRC Err
3D
CRC Err
Graph of B1 for direction Dn (right) Graph of B2 for direction Dn (left)
RSSI (Hex)