Hotspots - Aastra Messkoffer Bedienungsanleitung

Measurement/Planning

Hotspots

A hotspot is an area with an above-average number of handsets. Such an area can be covered with
several base stations as the resources in the coverage range of neighbouring base stations are
cumulated. It is recommended to cover hotspots with several base stations as they operate in "Zero-
Blind-Slot mode" and the calls can be spread out across 120 radio channels.
In practice it has emerged that interference from neighbouring channels in a hotspot without spe-
cial measures means that only approximately one quarter of the radio channels can be used simulta-
neously. This means that approx. 30 simultaneous connections are possible, which require for exam-
ple four base stations. Thus approx. 60 handsets can be used in a hotspot with a high traffic volume
(simultaneous call connections of approx. 50% of the handsets). It is essential to observe the mini-
mum distances when installing the base stations.
If extensive interference occurs in a hotspot or if more than 30 simultaneous connections are
required, check the following measures:
• Distribute the base stations that cover the hotspot spaciously around the hotspot. In doing so,
especially walls can help attenuate the strong signals which the base stations mutually disturb
each other.
Also check the possibility of a spherical arrangement of the base stations that cover the hotspot
through floors and ceilings.
With this solution approach, ensure that handsets do not suddenly seize the call channels of the
hotspot base stations that were previously supplied by other base stations (when setting up a
connection, handsets always seize channels of the base station that deliver the strongest signal).
It may therefore occur that moving the hotspot base stations triggers a chain reaction and that
other base stations have to be re-positioned.
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