High-speed multimedia radio (HSMM) is the implementation of high-speed wireless TCP/IP data networks over amateur radio frequency allocations using commercial off-the-shelf (COTS) hardware such as 802.11 Wi-Fi access points. This is possible because the 802.11 unlicensed frequency bands partially overlap with amateur radio bands and ISM bands in many countries. Only licensed amateur radio operators may legally use amplifiers and high-gain antennas within amateur radio frequencies to increase the power and coverage of an 802.11 signal.
Basics
The idea behind this implementation is to modify commercial 802.11 equipment for use on licensed Amateur Radio frequencies. The main frequency bands being used for these networks are: 900 MHz (33 cm), 2.4 GHz (13 cm), 3.4 GHz (9 cm), and 5.8 GHz (5 cm). Since the unlicensed 802.11 or Wi-Fi frequency bands overlap with amateur frequencies, only custom firmware is needed to access these licensed frequencies. Such networks can be used for emergency communications for disaster relief operations as well as in everyday amateur radio communications (hobby/social).
Capabilities
HSMM can support most of the traffic that the Internet currently does, including video chat, voice, instant messaging, email, the Web (HTTP), file transfer (FTP), and forums. The only differences being that with HSMM, such services are community instead of commercially implemented and it is mostly wireless. HSMM can even be connected to the Internet and used for web surfing, although because of the FCC regulations on permitted content, this is done only when directly used for ham radio activities (under Part 97). Using high gain directional antennas and amplifiers, reliable long-distance wireless links over many miles are possible and only limited by propagation and the radio horizon.
Bandwidths and Speeds
HSMM networks most-often use professional hardware with narrower channel bandwidths such as 5 or 10 MHz to help increase range. It is common for networks to use channel -2 with a 5 MHz bandwidth. For long-range links extending outside of metropolitan areas 802.11b DSSS modulations or 802.11ah (900 MHz) equipment can be used, further increasing range at the cost of speed.
- DSSS is 10 watts max PEP in USA
- DSSS is 10 watts max PEP in USA
US / FCC Frequencies and channels
The following is a list of the 802.11 channels that overlap into an amateur radio band under the FCC in the United States. Note that the 5 cm amateur band extends from 5.65 to 5.925 GHz, so that there are many frequencies outside the Part 15 ISM/UNII block used for 802.11a. Many commercial grade 802.11a access points can also operate in between the normal channels by using 5 MHz channel spacing instead of the standard 20 MHz channel spacing. 802.11a channels 132, 136 and 140 are only available for unlicensed use in ETSI regions. Channels and frequencies marked in should not be used.
* must use 5/10Mhz bandwidth
Acronyms Used: (amateur radio) (ISM) (Radar)
Channels and power
FCC / United States
802.11a
The 802.11a amateur radio band consists of 30 overlapping channels in the 5.650–5.925 GHz (5 cm) band. The 802.11a standard uses OFDM or "Orthogonal Frequency Division Multiplexing" to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11a hardware is not subject to the power rules in FCC Part 97 § 97.311 and the maximum allowable output power is 1,500 watts (W) PEP.
802.11b
The 802.11b amateur radio band consists of 8 overlapping channels in the 2.390–2.450 GHz (13 cm) band. The 802.11b specification uses Direct Sequence Spread Spectrum (DSSS) to transmit data and is subject to the rules of FCC Part 97 § 97.311. Therefore, the maximum allowable power output in the USA is 10 W PEP.
802.11g
The 802.11g amateur radio band consists of 8 overlapping channels in the 2.4 GHz (13 cm) band. The 802.11g standard uses OFDM or "Orthogonal Frequency Division Multiplexing" to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11g hardware is not subject to the power rules in FCC Part 97 § 97.311 and the maximum allowable output power is 1,500 W PEP.
802.11n
The 802.11n amateur radio band consists of 8 overlapping channels in the 2.4 GHz (13 cm) band. The 802.11n standard uses OFDM or "Orthogonal Frequency Division Multiplexing" to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11n hardware is not subject to the power rules in FCC Part 97 § 97.311 and the maximum allowable output power is 1,500 W PEP.