Aastra X Series, Руководство по установке и внедрению

Страница: 20 / 217

AMT/PTD/TR/0020/2/7/EN 10/2008 Page 1-20
1.5.2 Overlapping radio areas
The radio coverage of a site is established by positioning basic radio areas next to each other.
However, to guarantee quality of service for the entire site, the radio areas must overlap on the
horizontal and vertical axes. This overlap is required so the roaming and handover phases take
place in good radio conditions.
During deployment you must measure the significant values (CRC/RSSI) of the radio area
studied and note them on the site plan. These measurements must be taken on the horizontal
and vertical axes. The six measurements must indicate the following three values: the CRC, the
RSSI, and the distance between the point where the measurement was taken and the base
station concerned.
Figure 1-2: Overlapping radio areas
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.
bottom
RSSI < 3DH
CRC <
BS
top
right
back
front
store
left