Non-line-of-sight Radio
Because of building obstructions such as walls and ceilings, propagation losses indoors can be significantly higher. This occurs because of a combination of attenuation by walls and ceilings, and blockage due to equipment, furniture, and even people.
- For example, a “2 x 4” wood stud wall with drywall on both sides results in about 6dB loss per wall.
- Older buildings may have even greater internal losses than new buildings due to materials and line of sight issues.
Experience has shown that line-of-sight propagation holds only for about the first 3 meters. Beyond 3 meters propagation losses indoors can increase at up to 30dB per 30 meters in dense office environments.
This is a good “rule-of-thumb”, in that it is conservative (it overstates path loss in most cases). Actual propagation losses may vary significantly depending on building construction and layout.
Read more about this topic: Link Budget
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