User's Guide Part 1

User Guide: PTP 600 Series Wireless operation
phn-0896_009v003
Feb 2010
UNDER DEVELOPMENT
1-23
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 Data throughput capacity on
page 4-102.
Specifications of receive level thresholds for each modulation mode (assuming no
interference) are provided in the various system threshold tables in Chapter 4
Reference information.
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.
MIMO
The PTP 600 transmits two signals on the same radio frequency, one which is
vertically polarized, the other which is 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 none
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 Adaptive modulation on
page 1-22.