Adaptive Modulation - Motorola PTP 600 series User Manual

Wireless operation
Spectrum management in fixed frequency mode
The transmit and receive frequencies can be fixed in a PTP 600 wireless link. Once
fixed frequency mode is configured, the spectrum management software will not
attempt to move the wireless link to a channel with lower co-channel and adjacent-
channel interference. Therefore this mode of operation is only recommended for
deployments where the installer has a good understanding of the prevailing
interference environment (see
also be taken to ensure that the frequency allocations at each end of the link are
compatible.

Adaptive modulation

The PTP 600 series can transport data over the wireless link using a number of
different modulation modes ranging from 256QAM 0.81 to BPSK 0.63. For a given
channel bandwidth and TDD frame structure, each modulation mode transports data at
a fixed rate. Also, the receiver requires a given signal to noise ratio in order to
successfully demodulate a given modulation mode. Although the more complex
modulations such as 256QAM 0.81 will transport data at a much higher rate than the
less complex modulation modes, the receiver requires a much higher signal to noise
ratio.
The PTP 600 series provides an adaptive modulation scheme where the receiver
constantly monitors the quality of the received signal and notifies the far end of the
link of the optimum modulation mode with which to transmit. In this way, optimum
capacity is achieved at all times. This is one of a number of features which allows the
PTP 600 to operate in challenging none line of sight radio channels.
Specifications of capacity for all channel bandwidths, modulation modes and
configurations are provided in
Specifications of receive level thresholds for each modulation mode (assuming no
interference) are provided in the various system threshold tables in
Reference
NOTE
Link Planner should be used to estimate the performance of a given link.
Link Planner includes an estimate of mean data rate, the data rate provided
by each modulation and the percentage of time spent in each modulation
mode.
1-28
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Step 2: Wireless configuration
Data throughput capacity
information.
Chapter 1 Product description
on page 6-54). Care must
on page 4-117.
Chapter 4
phn-0896_012v000
Jul 2010