Range Parameter

 
Range Parameter
The range parameter defines the distance to which typical products based on the technology
can propagate data. For a wireless LAN, the range is generally the distance between an access
point and a radio card installed in a client device, such as a laptop. As an example, the range of
2.4GHz wireless LANs is 150 to 900 feet, depending on the data rate, output power, and facility
construction.
If all other attributes are equal, an increase in data rate decreases the effective range (and vice
versa). Range affects the requirement for geographical coverage area. A longer range enables
the construction of a wireless LAN having fewer access points and covering a wider area.
Table 8.1 identifies the affect that specific types of material have on the transmission of RF
signals.
TABLE 8.1 Attenuation Effects of Various Elements
Relative Degree of
RF Barrier Attenuation Example
Air Minimal
Wood Low Office partitions
Plaster Low Inner walls
Synthetic material Low Office partitions
Asbestos Low Ceilings
Glass Low Windows
Water Medium Damp wood, aquariums
Brick Medium Inner and outer walls
Marble Medium Inner walls
Paper High Paper rolls, cardboard boxes
Concrete High Floors and outer walls
Bulletproof glass High Security booths
Metal Very high Desks, office partitions, reinforced
concrete, elevator shafts, warehouse
shelving
As an example, metal offers very high attenuation to the propagation of radio signals, which
significantly limits the range of the wireless LAN. When defining this parameter or particular
technologies, be sure to consider attenuation characteristics of the typical environment where
the wireless LAN will operate.