Canopy 400 Series OFDM AP and SM
User Guide
Version 1, April 2008
Page 25 of 40
Similarly for the AP, enter the antenna gain in the External Antenna Gain field. The standard
antenna sold with the AP has a 17 dBi gain.
Typical External Antenna Gain values are shown in Table 5.
Table 5: Typical "External Antenna Gain" Values
For this installation
Enter this value in the
“External Antenna Gain” field
Canopy 400 Series AP with standard
connectorized 17 dBi antenna
17
Canopy 400 Series AP with other antenna
The dBi of the antenna
Canopy 400 Series SM
17
The value entered in the External Gain field does not affect the transmitter power. The radio
transmits at the level entered in the Transmitter Output Power. The module only uses the values
entered in the External Antenna Gain field to adjust DFS sensitivity, not to change transmitter
power.
4.5
OTHER CONFIGURABLE PARAMETERS
Other parameters are configured the same as they are in standard Canopy. These include, High
Priority/DiffServ, NAT, DHCP, VLAN, MIR, and CIR. MIR and CIR work the same as in standard
Canopy, but the operator may (or may not) want to take advantage of the higher MIR possible to
provide greater bandwidth to a given SM.
4.6
PARAMETERS THAT ARE NOT CONFIGURABLE
Canopy 400 Series radios use FEC (Forward Error Correction) to extend the range of the
modules. They use Reed-Solomon error correction optimized at 3/4 coding. The coding rate is not
settable by the operator.
OFDM technology uses a cyclic prefix, where a portion of the end of a symbol (slot) is repeated at
the beginning of the symbol (slot) to allow multipathing to settle before receiving the desired data.
The initial release of Canopy 400 Series radios use a cyclic prefix of 1/4 that is not configurable
by the user. This means that for every 4 bits of throughput data transmitted, an additional bit is
used. Future releases may offer lower cyclic prefixes to allow the operator to trade off between
multipathing resistance and throughput.
