Motorola 5440AP User Manual - Page 18

Dfs And Regulatory Parameters

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Canopy 400 Series OFDM AP and SM User Guide • if the Downlink Data % is set to greater than 85% and the user enters a range greater than 5 miles, the module will reset the Downlink Data % to 85% • if the range is set to greater than 5 miles and the user enters a Downlink Data % of greater than 85%, the module will reset the Downlink Data % to 85%. Suggested Control Slot settings as a function of number of SMs in the sector are shown in Table 3. Generally all APs in a cluster should use the same number of control slots so as to keep the frame structures, and thereby the send and receive timing, the same. Table 3: Control Slot Settings Number of SMs that Number of Control Register to the AP Slots Recommended 1 to 10 0 11 to 50 1 51 to 150 2 151 to 200 3 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 3.5.2 on page 14 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, but if not needed for data in a given frame can be used by the SMs for bandwidth requests. So, even with zero control slots configured, the SMs can still make bandwidth requests, using any 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 3.5.2 on page 14. 4.4 DFS AND REGULATORY PARAMETERS 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 Release 8.4 has a new page, "Home => DFS Status", that shows current DFS status of all three frequencies and a DFS log of past DFS events. Note, unlike standard Canopy, the Canopy 400 Series AP and SM do not offer "Whitening", as the OFDM technology obviates the need for it. Version 1, April 2008 Page 18 of 40

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Canopy 400 Series OFDM AP and SM
User Guide
Version 1, April 2008
Page 18 of 40
•
if the Downlink Data % is set to greater than 85% and the user enters a range greater
than 5 miles, the module will reset the Downlink Data % to 85%
•
if the range is set to greater than 5 miles and the user enters a Downlink Data % of
greater than 85%, the module will reset the Downlink Data % to 85%.
Suggested Control Slot settings as a function of number of SMs in the sector are shown in Table
3. Generally all APs in a cluster should use the same number of control slots so as to keep the
frame structures, and thereby the send and receive timing, the same.
Table 3: Control Slot Settings
Number of SMs that
Register to the AP
Number of Control
Slots Recommended
1 to 10
0
11 to 50
1
51 to 150
2
151 to 200
3
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 3.5.2 on page 14 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, but if not needed for data in a given frame can be used
by the SMs for bandwidth requests. So, even with zero control slots configured, the SMs can still
make bandwidth requests, using any 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 3.5.2 on page 14.
4.4
DFS AND REGULATORY PARAMETERS
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
Release 8.4 has a new page, “Home => DFS Status”, that shows current DFS status of all three
frequencies and a DFS log of past DFS events. Note, unlike standard Canopy, the Canopy 400
Series AP and SM do not offer “Whitening”, as the OFDM technology obviates the need for it.