Cisco Cisco MGX-FRSM-HS2 B Serial Frame Service Module Libro blanco
Wireless LAN Design Guide for High Density
Client Environments in Higher Education
15 © 2011 Cisco and/or its affiliates. All rights reserved.
The wireless LAN controller maintains two lists of APs, Figure 10, both transmit and receive (TX and RX) neighbors that
indicate how other APs hear a selected AP and how a selected AP hears other APs. This can be viewed using the Wireless
LAN Controller (WLC) Configuration Analyzer tool and used to tune the resulting network and identify sources of RF as the APs
themselves see it. Since this observation is based on OTA metrics and not based on predictive modeling, these values are
independent of the antenna and AP combination.
indicate how other APs hear a selected AP and how a selected AP hears other APs. This can be viewed using the Wireless
LAN Controller (WLC) Configuration Analyzer tool and used to tune the resulting network and identify sources of RF as the APs
themselves see it. Since this observation is based on OTA metrics and not based on predictive modeling, these values are
independent of the antenna and AP combination.
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2.4 GHz Channel Reuse in High-Density Wireless Design
In 2.4 GHz there are three non-overlapping channels with which to work in achieving isolation. The RF properties of 2.4 GHz
signals give it better range and less attenuation than signals in 5 GHz. In a high-density environment, there is often only one
clean channel reuse within a 10,000 square foot area. Channel reuse in such an area is opportunistic at best and it is not
possible to estimate without careful advanced survey techniques. Results will vary from no increase in bandwidth to modest
gains and will differ from site to site. If faced with such a challenge, consult with a professional with experience in advanced
engineering techniques specific to a high density RF deployment. Adding more APs can reduce the number of users per cell and
may appear to give more coverage when the space is empty. But once it fills up, the effect will be that of one large super cell
covering the room with limited bandwidth and sporadic connections for all.
signals give it better range and less attenuation than signals in 5 GHz. In a high-density environment, there is often only one
clean channel reuse within a 10,000 square foot area. Channel reuse in such an area is opportunistic at best and it is not
possible to estimate without careful advanced survey techniques. Results will vary from no increase in bandwidth to modest
gains and will differ from site to site. If faced with such a challenge, consult with a professional with experience in advanced
engineering techniques specific to a high density RF deployment. Adding more APs can reduce the number of users per cell and
may appear to give more coverage when the space is empty. But once it fills up, the effect will be that of one large super cell
covering the room with limited bandwidth and sporadic connections for all.
NOTE: Before considering a four-channel plan in 2.4 GHz, see
for an
excellent discussion on the issues. The conclusion is that it is better for two APs to share a channel than to have two channels
overlapping on the edge. Two APs sharing a channel can demodulate each others’ transmissions and share the bandwidth
amicably. When two channels overlap at the edge, it is just noise to both and will result in collisions, retransmits, and SNR
degradation.
overlapping on the edge. Two APs sharing a channel can demodulate each others’ transmissions and share the bandwidth
amicably. When two channels overlap at the edge, it is just noise to both and will result in collisions, retransmits, and SNR
degradation.