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Chapter 1: Product description
Adaptive mode is not available in the following configurations:
•
When link mode optimization is set to TDM Traffic (see
•
In regions where radar avoidance is operational (see
•
When the ODU is not a Full variant.
OFDM and channel bandwidth
The PTP 650 series transmits using Orthogonal Frequency Division Multiplexing (OFDM). This
wideband signal consists of many equally spaced sub-carriers. Although each sub carrier is
modulated at a low rate using conventional modulation schemes, the resultant data rate from the
sub-carriers is high. OFDM works exceptionally over a Non-Line-of-Sight (NLoS) channel.
The channel bandwidth of the OFDM signal is configurable to one of the following values: 10, 20,
40 and 45 MHz. Higher bandwidths provide greater link capacity at the expense of using more
spectrum. Systems configured for a narrower channel bandwidth provide better receiver
sensitivity and can also be an appropriate choice in deployments where the amount of free
spectrum is limited.
Each channel is offset in center frequency from its neighboring channel by 10 or 5 MHz.
Note
The Channel Bandwidth must be configured to the same value at both ends of the link.
Not all channel bandwidths are available in all regulatory bands.
Spectrum management
The spectrum management feature of the PTP 650 Series monitors the available wireless spectrum
and directs both ends of the wireless link to operate on a channel with a minimum level of co-
channel and adjacent channel interference.
Spectrum management measurements
The PTP 650 Series performs two mean signal measurements per TDD cycle, per channel. This
mean measurement represents the mean received signal power for the 40 microsecond
measurement period.
The Spectrum Management algorithm collects measurements equally from all channels in the
operating band. This process is called the Channel Availability Check (CAC). The CAC uses a
round-robin channel selection process to collect an equal amount of measurements from each
channel. The CAC measurement process is not altered by the channel barring process.
Measurements are still collected for all channels irrespective of the number of barred channels.
Link mode optimization
Radar avoidance
Page
1-9
Wireless operation
on page 1-8).
on page 1-12).
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