User's Manual

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Copyright © 2004-2012 by InfiNet Wireless
Every step in bitrate increasing requires 3 dB step improvements SNR.
Asymmetry in 8 times corresponds to 9 dB. It means that without link quality
losses we can have 2 times bitrate difference between upstream and
downstream. In order to maintain energetic parameters, we have to increase
base station output power by 9 dB by means of built-in amplifier (for example to
use 300-500mW devices).
4. «Bad subscriber» problem
While working in Point-to-Multipoint topology wireless network could face a
problem when one of the subscriber devices has much poorer connection
characteristics to Base Station than the other ones. Such subscriber device is
using a considerable part of Base Station’s resources. While Base Station is trying
to send him a packet on a low bitrate other subscribers are waiting for this
transaction to finish. Therefore, all the networks’ performance will be reduced.
To lower the influence of such “bad subscriber” on the overall wireless network‘s
performance it is recommended to decrease a priority of this subscriber (using
“qm” command). In this case all the packets to “bad subscriber” will be sent
after other subscriber stations already get their portions of data. This will result
in wireless network performance optimization as subscriber devices’ operation
won’t depend on the bitrate of “bad subscriber”.