User's Manual

PMP 400/430 and PTP 200 Series Canopy User Guide
Supplement
Issue 4 0 – DRAFT 6 November 2009 Page 37 of 64
In some cases operators may find that sectors with high levels of small packet requests, such as
might be seen in a sector handling several VoIP streams, benefit overall from slightly higher
Control Slot settings. If different sectors require different numbers of Control Slots, the operator
should use the Frame Calculator to find a combination of settings that put “Rec SEQ Start” times
within 300 bit times. See section 3.7.2 on page 31 for details.
Control Slots are reserved for SMs’ bandwidth requests and never handle data. A higher number
of control slots gives higher probability that an SM’s bandwidth request will be heard when the
system is heavily loaded, but with the tradeoff that sector capacity is reduced by about 100 kbps
for each Control Slot configured, so there will be less capacity to handle the request.
Uplink Data Slots are used first for data. If they are the not needed for data in a given frame the
data slot can be used by the SMs for bandwidth requests. This allows SMs in sectors with zero
control slots configured to still make bandwidth requests using unused data slots.
Downlink Data %, Range, and Control Slots should be set consistent with the results of any
collocation planning done using OFDM and FSK frame calculators in section 3.7.2 on page 31.
The BHM performs its own ranging and so no range need be set for it.
BHMs do not have settings for control slots, as there is no bandwidth request contention on the
one-to-one link.
4.4 DFS AND REGULATORY PARAMETERS FOR 5.8 & 5.4 GHZ RADIOS
Dynamic Frequency Selection (DFS) is a requirement in several countries and regions for 5 GHz
unlicensed systems to detect radar systems and avoid co-channel operation. DFS and other
regulatory requirements drive the settings for the following parameters, as discussed in this
section:
• Region Code
• Primary Frequency
• Alternate 1 and Alternate 2 Frequencies
• External Antenna Gain
On the AP, the “Home => DFS Status” page shows current DFS status of all three frequencies
and a DFS log of past DFS events. Unlike standard Canopy, the PMP 400/430 and PTP 200
Series AP, SM, and BH do not offer “Whitening”, as the OFDM technology obviates the need for
it.
Figure 25: DFS Status on AP "Home => DFS Status" page.