Motorola PMP 400 Series Supplement To User’s Manual page 9

PMP 400 and PTP 200 Series
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 4 shows examples of such links.
Whereas multi-pathing degrades a link in some technologies, like FSK, OFDM can often use
multi-pathing to advantage to overcome nLOS and NLOS, especially in cases where the Fresnel
zone is only partially blocked by buildings, "urban canyons", or foliage. OFDM tends to help
especially when obstacles are near the middle of the link, and less so when the obstacles are
very near the SM, AP, or BH.
However, attenuation through walls and trees is substantial for any use of the 5.4 GHz or 4.9 GHz
frequency bands. Even with OFDM, these products should not be expected to penetrate walls or
extensive trees and foliage.
2.2 APPLICATIONS
Applications for the PMP 54400 and PTP 54200 Series systems include
High throughput enterprise applications
•
NLOS/nLOS video surveillance in metro areas
•
Extend networks into urban areas
•
Extend networks into areas with foliage
•
Applications for the PMP 49400 Series systems include
High throughput licensed network for government applications
•
Municipal network - NLOS/nLOS video surveillance in metro areas
•
Disaster relief network
•
Data service network - extend licensed networks into areas with foliage
•
Issue 3, January 2009
Figure 4: LOS, nLOS, and NLOS
Canopy User Guide Supplement
Page 9 of 45