User guide

Ubee Interactive 3.9 Wireless Network Deployment and Troubleshooting
DDW3612 Subscriber User Guide • July, 2010 53
3.9.1.2 Estimating Wireless Cable Modem to Wireless Client Distances
This section provides some guidelines on how far a wireless cable modem can be
placed in varying environments from wireless client devices. These variances include
the capabilities of wireless clients and the types of material through which the wireless
signal must pass. When the wireless cable modem and wireless clients reach the
distance threshold between each other, network performance degrades.
1. Connect a wireless client to the wireless cable modem. Refer to “Connect/Validate
Wireless Clients” on page 10 if needed.
2. Place the wireless client at around one meter (three feet) away from the wireless
cable modem.
3. Obtain the RSSI value for the connected client. Refer to “Wireless - Access
Control” on page 44. This value will be used in the formula further below.
4. Use the table below to determine what materials the wireless signal must travel
through in order to reach the desired wireless coverage distance.
5. Using the attenuation value from the materials table above, enter it in the following
formula. Additional explanation is provided further below.
Attenuation Considerations at 2.4GHz
Material Attenuation
Connector/Cable 3.5dB
Free Space .24dB / foot
Interior Drywall 3dB to 4dB
Cubicle Wall 2dB to 5dB
Wood Door (Hollow/Solid) 3dB to 4dB
Brick, Concrete Wall (Note 1) 6dB to 18db
Glass Window (not tinted) 2dB to 3dB
Double Pane Coated Glass 13dB
Bullet Proof Glass 10dB
Steel / Fire Exit Door 13dB to 19dB
Human Body 3dB
Trees (Note 2) .15dB / foot
Note 1: Different types of
concrete materials are used in
different parts of the world and
the thickness and coating differ
depending on whether it is used
in floors or interior or exterior
walls.
Note 2: The attenuation caused
by trees varies significantly
depending upon the shape and
thickness of the foliage.