Canopy 400 Series OFDM AP and SM
User Guide
Version 1, April 2008
Page 7 of 40
Figure 2: Canopy 400 Series OFDM AP (connectorized radio and antenna)
In addition, a Canopy CMMmicro or CMM4 provides synchronization and power to the Canopy
400 Series APs, and a 600SSC surge suppressor, a replacement for the 300SS surge
suppressor provides over-voltage and over-current protection to both APs and SMs.
2.1
TECHNOLOGY AND BENEFITS
A Canopy 400 Series radio automatically selects QPSK (Quadrature Phase Shift Keying), 16-
QAM (Quadrature Amplitude Modulation), or 64-QAM based on RF environment to provide 1X,
2X, and 3X operation, respectively. This provides 3 speeds whereas standard Canopy provides 2
speeds and gives a top throughput of 21 Mbps aggregate (sum of up plus down).
The OFDM radios feature lower receive sensitivity, FEC (Forward Error Correction), and higher
antenna gain, all of which combine to provide longer range within regulatory-specified EIRP
(Equivalent Isotropic Radiated Power).
Details on performance are listed in Table 1 on page 11.
The Canopy 400 Series radios use an OFDM physical layer with 10 MHz channels and 256 sub-
carriers. Due to the different carrier and modulation schemes between Canopy 400 Series radios
and standard Canopy radios, the two do not interoperate over the air. For example, an OFDM SM
cannot connect to an FSK AP.
2.1.1
NLOS and nLOS Benefits and Limitations
The use of OFDM technology will help in many cases of NLOS (Non Line-of-Sight) and nLOS
near Line-of-Sight (nLOS) links. LOS (Line-of-Sight ) means the installer can see the AP from the
SM and the first Fresnel zone is clear. An example of nLOS is when the installer can see the AP
from the SM, but a portion of the first Fresnel is blocked. An example of NLOS is when the
installer cannot see the AP from the SM, and a portion or even much of the first Fresnel is
blocked, but subsequent Fresnel zones are open. Figure 3 shows examples of such links.
