Avaya DECT R4 Installation And Administration Manual page 52

Planning an IP-DECT system
The base station at corner A reaches the cordless phone at corner B by means of a direct signal
(signal 1) and by means of a reflected indirect signal (signal 2). Many reflected signals reach the
cordless phone. The paths that these signals travel are not equal, and so the signals arrive at
the cordless phone at different times.
A DECT signal consists of frames of 420 bits transmitted every 10 ms. The bit length for DECT
is 0.868 μs. Mutes or Interruptions in your conversation and clicks on the line will occur if the
time difference between the various received signals is of the order of 1/10 bit length. If this
occurs, the receiver hcannot distinguish between the different transmitted bits. Therefore, you
must place the base stations in a metal hall to minimize the time delay spread and the number
of reflections.This means in turn that you must locate the base stations such that the number of
reflections is minimized.
Locations for base stations in metal halls
Apart from the time delay spread, adhere to the following general rules when you place a base
station:
Install a base station in line of sight (The base station 'sees' the user).
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When you increase the number of base stations at locations that are important to the
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client, the speech quality can deteriorate in other places in the hall because the cordless
phone must carry out more handovers.
Place the base station at a minimum height of 3 metres as otherwise it is highly possible
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that something will be placed in front of the base station, and this prevents the materials
and machines in the hall reflecting the signal.
Place the base station at a minimum height of 3 metres. At a lower height, something that
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is placed in front of the base station prevents the materials and machines in the hall from
reflecting the signal.
The rules depend on the dimensions of the hall and the type of antenna in use.
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Avaya DECT R4 - Installation and Maintenance Guide 02/2016