What is FHSS & DSSS?
Frequency Hopping Spread Spectrum and Direct Sequence Spread Spectrum is the quick answer. Both operate from 2.400-2.485 GigaHertz, in what is known as the ISM band. The 802.11 wireless standard covers both DSSS and FHSS, although not all manufacturers employ or fully adhere to 802.11. Both FHSS and DSSS use the middle 79 frequencies and must leave the top and bottom 3 alone as a “buffer”. The DSSS system utilizes “sets” of frequencies in a sequential progression and uses “channels” 1,6 and 11. There are 11 channels available in the spectrum, but each uses frequencies such that only three channels can coexist and not overlap. To obtain 11Mbps under the 802.11 DS must separate the carrier frequencies of each channel by 30 frequencies and there are only 79 to go around restricting colo use to 3. DSSS can sustain throughputs from anywhere from 4.2Mbps and up depending on the manufacturers claims and methodologies. DSSS can also maintain a higher throughput over distance than FHSS. DSSS is
