WIT-400HE Installation Manual
Date: 15/M
ar/2012
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Written permission of a duly authorized representative of Ericsson-LG Co.Ltd.
26
situations. The solution is to increase the radio coverage area.
A. RF channel Specification
The IEEE 802.11 b/g standard establishes several requirements for the RF transmission
characteristics of an 802.11 radio. These channels have a center frequency separation of only 5
MHz and an overall channel bandwidth (or frequency occupation) of 22MHz. So it has
overlapping channels for each channel as shown in figure below. This is true for 802.11b
products running 1, 2, 5.5, or 11 Mbps as well as the newer 802.11g products running up to 54
Mbps.
B. Channel Allocation and cell planning
When planning a WLAN cell, you should ensure that the channels that the adjacent APs use are
non-overlapping. Non-overlapping channels are frequency bands that do not have a frequency
that is common to each other. For example in the 2.4GHz range there are three channels that are
non-overlapping (channels 1, 6 and 11). Therefore, when you deploy a secondary AP to extend
the Radio coverage, you can use the channel 1 for the first AP, channel 6 for the next adjacent
AP and channel 11 for the third AP as shown in figure below and then start with channel 1. If you
use overlapping channels, radio frequency interference can occur, which leads to connectivity
issues and in poor throughput. Also, you should ensure that you do not place the APs too close
each other. Too many APs in the same vicinity create radio congestion and RF interference that
can reduce data throughput. A careful site survey can determine the best placement of APs for
maximum radio coverage and optimized throughput.
1 channel
6 channel
11 channel
1 channel
6 channel
11 channel