Mimo; Intelligent Dynamic Frequency Selection - Motorola PTP 600 series User Manual

User Guide: PTP 600 Series

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 over a non-line-of-sight path.
The PTP 600 transmits two signals on the same radio frequency, one of which is
vertically polarized and the other horizontally polarized. The PTP 600 also has the
ability to adapt between two modes of operation:
•
Dual Payload: When the radio channel conditions allow, the PTP 600 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 PTP 600.
•
Single Payload: As the radio channel becomes more challenging, the PTP 600
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 PTP 600 to operate in challenging non-
line of sight radio channels.
The two modes have been implemented by the introduction of two sets of modulation
modes. The lower order modulations (BPSK 0.63 up to QPSK 0.87) are only available
as single payload modes. Each of the higher order modulations (16QAM 0.63 to
256QAM 0.81) are available in single payload mode and dual payload mode. The
switching between modes is automatically controlled by the adaptive modulation
feature described in

Intelligent dynamic frequency selection

The PTP 600 series uses an interference mitigation technique known as Intelligent
Dynamic Frequency Selection (i-DFS). Both the PTP 600 Master and PTP 600 Slave
continually monitor for interference on all channels and then select the best frequency
of operation. This is a dynamic process where the PTP 600 can continually move
channels in response to changes in interference. Two modes of operation are available,
one where the two link directions are forced to select the same frequency. This is
determined by the Master. The second mode is where the frequency of operation can
be determined independently for each direction. This is a key feature which enables
the PTP 600 to operate successfully in areas where other radio equipments are
operating within the same band. i-DFS is not available in the 2.5 GHz band.
phn-0896_012v000
Jul 2010
4Gon www.4Gon.co.uk info@4gon.co.uk Tel: +44 (0)1245 808195 Fax: +44 (0)1245 808299
Adaptive modulation on page 1-28.
Wireless operation
1-29