Cambium Networks PTP 250, User Manual

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PTP 250 User Guide Wireless operation
phn-2510_002v000 (Mar 2012) 1-17
PTP LINKPlanner includes an estimate of mean data rate, the data rate provided by each
modulation and the percentage of time spent in each modulation mode.
MIMO
Multiple-Input Multiple-Output (MIMO) techniques provide protection against fading and
increase the probability that the receiver will decode a usable signal. When the effects of
MIMO are combined with those of OFDM techniques and a high link budget, there is a
high probability of a robust connection.
The PTP 250 transmits two signals on the same radio frequency, one of which is vertically
polarized and the other horizontally polarized. The system also has the ability to adapt
between two modes of operation:
x
Dual Payload : When the radio channel conditions allow, the system will transmit two
different and parallel data streams, one on the vertical channel and one on the
horizontal channel. This doubles the capacity of the system.
x
Single Payload : As the radio channel becomes more challenging, the system has the
ability to detect this and switch to a mode which transmits the same data stream on
both vertical and horizontal channels. This provides polar diversity and is another key
feature which allows the system to operate in challenging radio channels.
The switching between modes is automatically controlled by the adaptive modulation
feature described in
Adaptive modulation on page 1-16 .