2.401 2.495Frequency (GHz)Spread Spectrum Technology 143
Of these 14 channels, mathematically there are only 3 adjacent non-overlapping chan-
nels, with the exception of channel 14. Per the IEEE 802.11-2007 standard, “Channel 14
shall be designated specifically for operation in Japan.” There are 3 MHz of separation
where the radio frequency of one channel ends and the next adjacent non-overlapping chan-
nel begins. For example, channel 1 and channel 6 are adjacent non-overlapping channels.
Channel 1 ends at 2.423 GHz and channel 6 begins at 2.426 GHz. Mathematically this is
a separation of 3 MHz. This means that three access points can be co-located in the same
physical space without overlapping channel interference. However, there is still theoreti-
cally a small amount of overlapping RF or harmonics between these two channels. This
small level of overlap is not large enough to cause any real interference issues. Figure 5.9
illustrates 3 of the first 14 channels that do not overlap in the 2.4 GHz ISM band.
f i g u r e 5 . 9 3 Non-overlapping channels possible in the 2.4 GHz ISM bandPower (mW)Channels 1, 6, and 11 do not overlapChannel 1 Channel 6 Channel 11
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