Adaptive frequency hopping

Adaptive frequency hopping
You may recall in Chapter 4, Can we Confidently Rely on Wireless Communication? we
discussed issues surrounding coexistence with other 2.4GHz-enabled products. AFH is a scheme that was introduced by the SIG to reduce interference with a range
of proprietary technologies that already use the 2.4GHz radio spectrum. Both
802.11b- and 802.11g-enabled products utilize the 2.4GHz radio spectrum and the
market penetration of this technology is somewhat widespread. The existing frequency
hopping scheme hops at a rate of 1,600 times per second where the scheme
utilizes all 79 channels available within the 2.4GHz band. New generations of
Bluetooth products will use the AFH to avoid conflicts within the available channel
range. In an environment where there are many 2.4GHz wireless products, there is a
greater probability that a collision will occur on a particular channel and, as such, data
may be lost. AFH affords Bluetooth a more intelligent approach to its frequency
hopping scheme, as it adapts to the environment in which it finds itself. If there is a
consistent problem with a particular channel, then AFH will exclude this channel
from the scheme. Interestingly, in a heavily populated environment, it is conceivable
that the number of available channels would reduce considerably; however, the specification
does dictate that the minimum number of channels readily available should
be around twenty. Although the scheme helps reduce the likelihood of problems
associated with coexistence it is still not completely dependable.