Cisco Cisco Aironet 1310 Access Point Bridge Libro bianco
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A dual-band deployment may look like the deployment shown in Figure 1.
Figure 1. A Sample Dual-Band Deployment
In this example, a site survey is conducted to optimize the 2.4 GHz (802.11b/g) network, depending on the required coverage and throughput
requirements. The number of 802.11b-only and 802.11g-only clients should be factored in, as these clients will be using the 2.4-GHz network. For
some networks, this number can be expected to decline over time, since client devices like laptops and handhelds will be replenished with dual-band
capable devices (which will use an available 5-GHz channel a priori, as discussed previously). Because only three nonoverlapping channels are
available in the 2.4-GHz band, interference from adjacent cells must be considered. This interference is generally compensated for by reducing the
transmit power of the radios.
With the 802.11b/g network designed, deploying the 802.11a network can simply consist of configuring each 802.11a radio to a unique 5-GHz
channel. In most cases, no second site survey is needed. Since there can be up to 19 channels in the 5-GHz band, up to 19 802.11a radios can be
enabled before interference is encountered. For networks with more than 19 access points, interference must be considered, but its impact should be
negligible---signals will fade before cochannel interference is encountered. In most cases, the 802.11a radios can be deployed at maximum transmit
power without causing cochannel interference. If the deployment density is such that cochannel interference becomes relevant, then the transmit
power of the access points should be reduced to minimize interference.