Page 10 - Site Surveys
Page 10
DECT - Installation Manual
Base Station Coverage: In Practice
38HBKD0001SAH – Issue 14 (27th October 2003)
Base Station Coverage: In Practice
In practice, no rules can be given for base station coverage. Coverage is
affected by too many factors that are unique to each site. We can only
guide you as to those things that are likely to affect base station coverage.
Obvious causes of signals problems:
– Metal
surfaces.
– Concrete thickness greater than one metre.
Beware of:
–
Windows with reflective film/specialised glass: (eg Pilkington 'K')
These produce increased signal reflection and reduced signal pass-
through.
–
Wire Meshes and Grills with apertures of less than 4cm:
These block signals as effectively as continuous metal sheet.
–
Fire Doors:
These block the signals. In multi-occupancy building such as hotels
the high number of fire-doors may be a problem.
–
Stair Wells:
In modern office buildings, stair wells frequently combine concrete
building supports, fire doors and the intervening floor material, making
them a special problem.
–
Screened Rooms:
Typically found in offices involved with TV, video and radio production,
but also possible in computer centers.
Base station overlap areas:
– In overlap areas, the signal from one base station is getting weak and
so the handset will start call handover to the next base station.
However this process can take up to 10 seconds. In overlap areas
look out for items such as closing doors that might suddenly block the
already weak signal before handover is completed.
–
To calculate the overlap required, based on the handset user's speed,
allow 10 seconds to guarantee handover.
_ Remember that base stations located on different floors will add to the
number of overlaps.
– Ideally base stations should be a minimum of 25 to 40 metres apart.
–
The number of base station signals which can be monitored by DECT
Handsets is four.
– Do not put more than 3 DBSs in a cluster for the purpose of
maximising call capacity, i.e. within 25cm of each other.
Opportunities to be aware of:
– In multi-storey buildings, if the building construction allows, a base
station on one floor can also serve the floor above or below.
