Network Planning and Diagnostics
Wireless Communication Stability Considerations
62
SKF Wireless Machine Condition Sensor
Service Manual
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Consider elevating the mesh network if ground level is too congested with
obstructions. For example, elevated routers may receive the signals that are
obstructed at ground level and then route them to the gateway, as shown in the
following figure.
Figure 33
.
Diagram of an Elevated Mesh Network,
Red Lines Indicate Communication Paths Blocked by Obstacles.
Wireless Communication Stability Considerations
Location and Signal Strength
Radio signal strength decreases in free space with the inverse square of the distance; an
example of Free Space Path Loss (FSPL) is provided below with a link budget calculation
example. In an industrial environment, there are several potential obstacles for radio
waves, for example buildings, walls, pipes, or even moving obstacles like trucks. These
obstacles can reflect, bend, diffuse or block radio waves. The table below lists radio
signal attenuation through common obstacles (source is Dust Networks Inc.).
Material
Signal attenuation
Clear glass window
2 dB
Brick wall
2 to 8 dB
Solid wood door
3 dB
Cubicles
3 to 5 dB
Cinder block wall
4 dB
Drywall/sheetrock wood framed
4 to 6 dB
Marble
5 dB