IEEE 802.11 Frequency Hopping Spread Spectrum (FHSS)
Frequency hopping works by modulating a data signal with a carrier signal that hops from frequency to frequency as a function of time over a wide band of frequencies. With 802.11 FHSS, the carrier frequency hops over the 2.4GHz frequency band between 2.4GHz and 2.483GHz. The signal stops long enough at each frequency to transmit data for an amount of time based on the dwell time set as a configuration parameter.
IEEE 802.11 FHSS provides the following advantages (in comparison to DSSS):
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Greater tolerance of signal interference because of operation over wider (83.5MHz) bandwidth
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Capability to operate up to 10 collocated access points without significant interference
IEEE 802.11 FHSS provides the following disadvantages (in comparison to DSSS):
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Lowest potential data rates (2Mbps) from individual physical layers
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Less range than direct sequence because of need for at least 18dB SNR at the receiver
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Potential obsolescence as more companies continue to favor the higher-speed (802.11b) direct sequence products