Design Guide

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Cisco Aironet 1520, 1130, 1240 Series Wireless Mesh Access Points, Design and Deployment Guide, Release 6.0
OL-20213-01
Site Preparation and Planning
Figure 33 Cell Radius of 1000 Feet and Access Point Placement for Voice Mesh Networks
Note Refer to “Guidelines For Using Voice On The Mesh Network” section on page 112 for additional
voice considerations when configuring voice on your network.
Wireless Propagation Characteristics
Table 11 provides a comparison of the 2.4 GHz and 5 GHz bands.
The 2.4 GHz band does provide better propagation characteristics than 5 GHz, but 2.4 GHz is an
unlicensed band and has historically been affected with more noise and interference to date than the
5 GHz band. In addition, because there are only three backhaul channels in 2.4 GHz, co-channel
interference would result. Therefore, the best method to achieve comparable capacity is by reducing
system gain (that is, transmit power, antenna gain, receive sensitivity, and path loss) to create smaller
cells. Keep in mind that these smaller cells require more access points per square mile (greater access
point density).
Therefore, 2.4GHz has more penetration capability across the obstacles due to larger wavelength. In
addition, 2.4 GHz has lower date rates which increases the success of the signal to reach the other end.
Table 11 Comparison of 2.4-GHz and 5-GHz Bands
2.4 GHz Band Characteristics 5 GHz Band Characteristics
3 channels 20 channels
More prone to co-channel interference No co-channel interference
Lower power Higher power
Data rates less than 6 Mb/s Data rates 6 Mb/s and greater (up to 54 Mb/s).
Lower SNR requirements given lower data rates Higher SNR requirements given higher data rates
Better propagation characteristics than 5 GHz but
more susceptible to noise and interference
Worse propagation characteristics than 2.4 GHz
but less susceptible to noise and interference
Unlicensed band. Widely available throughout the
world.
Not as widely available in the world as 2.4-GHz.
Licenses in some countries.