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).HSMM Radio Equipment arrl.org 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, 802.11g BPSK/QPSK, or 802.11ah (900 MHz) equipment can be used, further increasing range at the cost of speed.

+ 802.11b Speeds Table 5 MHz bandwidth 2.4 GHz band Mode Modulation Max Speed 1 DSSS BPSK 0.25 Mbps 2 DSSS QPSK 0.5 Mbps 5.5 DSSS QPSK 1.375 Mbps 11 DSSS QPSK 2.75 Mbps - DSSS is 10 watts max PEP in USA

+ 802.11b Speeds Table 10 MHz bandwidth 2.4 GHz band Mode Modulation Max Speed 1 DSSS BPSK 0.5 Mbps 2 DSSS QPSK 1 Mbps 5.5 DSSS QPSK 2.75 Mbps 11 DSSS QPSK 5.5 Mbps - DSSS is 10 watts max PEP in USA

+ 802.11g Speeds Table 5 MHz bandwidth 2.4 GHz band Mode Modulation Max Speed 6 OFDM BPSK 1.5 Mbps 9 OFDM BPSK 2.25 Mbps 12 OFDM QPSK 3 Mbps 18 OFDM QPSK 4.5 Mbps 24 OFDM 16QAM 6 Mbps 36 OFDM 16QAM 9 Mbps 48 OFDM 64QAM 12 Mbps 54 OFDM 64QAM 13.5 Mbps

+ 802.11g Speeds Table 10 MHz bandwidth 2.4 GHz band Mode Modulation Max Speed 6 OFDM BPSK 3 Mbps 9 OFDM BPSK 4.5 Mbps 12 OFDM QPSK 6 Mbps 18 OFDM QPSK 9 Mbps 24 OFDM 16QAM 12 Mbps 36 OFDM 16QAM 18 Mbps 48 OFDM 64QAM 24 Mbps 54 OFDM 64QAM 27 Mbps

+ 802.11ah Speeds Table 1 MHz bandwidth 900 MHz band Mode Modulation Max Speed 0 OFDM BPSK 0.36 Mbps 1 OFDM QPSK 0.72 Mbps 2 OFDM QPSK 1.085 Mbps 3 OFDM 16-QAM 1.445 Mbps 4 OFDM 16-QAM 2.165 Mbps 5 OFDM 16-QAM 2.89 Mbps 6 OFDM 16-QAM 3.25 Mbps 7 OFDM 16-QAM 3.61 Mbps 8 OFDM 256-QAM 4.335 Mbps

+ 802.11ah Speeds Table 2 MHz bandwidth 900 MHz band Mode Modulation Max Speed 0 OFDM BPSK 0.72 Mbps 1 OFDM QPSK 1.44 Mbps 2 OFDM QPSK 2.17 Mbps 3 OFDM 16-QAM 2.89 Mbps 4 OFDM 16-QAM 4.33 Mbps 5 OFDM 16-QAM 5.78 Mbps 6 OFDM 16-QAM 6.5 Mbps 7 OFDM 16-QAM 7.22 Mbps 8 OFDM 256-QAM 8.67 Mbps

+ 802.11ah Speeds Table 4 MHz bandwidth 900 MHz band Mode Modulation Max Speed 0 OFDM BPSK 1.44 Mbps 1 OFDM QPSK 2.88 Mbps 2 OFDM QPSK 4.34 Mbps 3 OFDM 16-QAM 5.78 Mbps 4 OFDM 16-QAM 8.66 Mbps 5 OFDM 16-QAM 11.56 Mbps 6 OFDM 16-QAM 13 Mbps 7 OFDM 16-QAM 14.44 Mbps 8 OFDM 256-QAM 17.34 Mbps

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.

+ 2.4 GHz (13 cm) Channel Center Frequency FCC Rules −2* 2.397 GHz* Part 97* −1 2.402 GHz Part 97 (Guard band) 1 2.412 GHz Part 97 & Part 15 2 2.417 GHz Part 97 & Part 15 3 2.422 GHz Part 97 & Part 15 4 2.427 GHz Part 97 & Part 15 5 2.432 GHz Part 97 & Part 15 6 2.437 GHz Part 97 & Part 15 * must use 5/10Mhz bandwidth

+ 3.5 GHz (9 cm) Channel Center Frequency FCC Rules 76 3.380 GHz Part 97 77 3.385 GHz Part 97 78 3.390 GHz Part 97 79 3.395 GHz Part 97 80 3.400 GHz Part 97 81 3.405 GHz Part 97 82 3.410 GHz Part 97 83 3.415 GHz Part 97 84 3.420 GHz Part 97 85 3.425 GHz Part 97 86 3.430 GHz Part 97 87 3.435 GHz Part 97 88 3.440 GHz Part 97 89 3.445 GHz Part 97 90 3.450 GHz Part 97 91 3.455 GHz Part 97 92 3.460 GHz Part 97 93 3.465 GHz Part 97 94 3.470 GHz Part 97 95 3.475 GHz Part 97 96 3.480 GHz Part 97 97 3.485 GHz Part 97 98 3.490 GHz Part 97 99 3.495 GHz Part 97

+ 5 GHz (5 cm) Channel Center Frequency FCC Rules TDWR TDWR 136 5.680 GHz Part 97 & Part 15 138 5.690 GHz Part 97 & Part 15 140 5.700 GHz Part 97 & Part 15 142 5.710 GHz Part 97 & Part 15 144 5.720 GHz Part 97 & Part 15 149 5.745 GHz Part 97 & Part 15 151 5.755 GHz Part 97 & Part 15 153 5.765 GHz Part 97 & Part 15 155 5.775 GHz Part 97 & Part 15 157 5.785 GHz Part 97 & Part 15 159 5.795 GHz Part 97 & Part 15 161 5.805 GHz Part 97 & Part 15 165 5.825 GHz Part 97 & Part 15 169 5.845 GHz Part 97 170 5.850 GHz Part 97 171 5.855 GHz Part 97 172 5.860 GHz Part 97 173 5.865 GHz Part 97 174 5.870 GHz Part 97 175 5.875 GHz Part 97 176 5.880 GHz Part 97 177 5.885 GHz Part 97 178 5.890 GHz Part 97 179 5.895 GHz Part 97 180 5.900 GHz Part 97 181 5.905 GHz Part 97 182 5.910 GHz Part 97 183 5.915 GHz Part 97 184 5.920 GHz Part 97

Acronyms Used: (amateur radio) (ISM) (Radar)

Channels and power

FCC / United States

5 GHz All 802.11 standards in the 5 GHz band are OFDM. This band consists of 30 overlapping channels in the 5.650–5.925 GHz.(5 cm) band.

The 802.11a/h/n/ac/ax/be standards use Orthogonal Frequency Division Multiplexing (OFDM) to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11a/h/n/ac/ax/be 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.

This band also exists in ITU Regions 1 and 3, but it is narrower at 5.650–5.850 GHz.

2.4 GHz The amateur ratio band in 2.4 GHz 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 for 802.11b transmission in the USA is 10 W PEP.

The 802.11g/n/ax/be standard use Orthogonal Frequency Division Multiplexing (OFDM) to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11g/n/ax/be 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.

3.4 GHz The 3.300–3.500 GH amateur ratio band is allocated on a secondary basis. It consists of 24 overlapping channels.

The 802.11y standard uses Orthogonal Frequency Division Multiplexing (OFDM) to transmit data and therefore is not classified as spread-spectrum. Because of this 802.11y 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.

It exists in ITU Region 2 and 3, but not in ITU Region 1.

The standardized frequency for 802.11y is 3.655–3695 GHz with 8 non-overlapping channels (and 6 overlapping ones built on top of them). This used to be a licensed range, but is now part of the 3.55–3.7 GHz Citizens Broadband Radio Service (CRBS) band, managed by an automated Spectrum Access System.

Frequency sharing

FCC / United States

5 GHz The 5 cm band is shared with the fixed-satellite service in ITU Region 1, and the radiolocation service. In ITU Region 2 (US) the primary user is military radiolocation, specifically naval radar. Amateur radio operators have secondary privileges to the Federal radiolocation service in the entire band and may not cause interference to these users. Amateur operators are allocated this band are in a co-secondary basis with ISM devices and space research. Amateur, space research, and ISM operators each have the "right to operate". Due to the lack of a high number of Part 15 users (compared to 2.4 GHz), the noise level tends to be lower in many parts of the US but can be quite congested in urban centers and on mountaintops. The frequencies from 5.6-5.65 GHz (channel 132) should generally be avoided to prevent interfering with TDWR weather radar stations.

2.4 GHz The 13 cm band is shared with Part 15 users as well as the Federal radiolocation service, and ISM (industrial, scientific, medical) devices. Amateur radio operators have secondary privileges to the Federal radiolocation service in the entire band and may not cause interference to these users. Amateur radio operators have primary privileges to ISM devices from 2.390–2.417 GHz and secondary privileges from 2.417–2.450 GHz. Because of the high number of Part 15 users, the noise level in this band tends to be rather high.

3.4 GHz The 9 cm band is shared with fixed services and space-to-Earth communications. Amateur radio operators using this band may not cause interference to other licensed users, including government radar stations. The low number of users tends to make this band quiet.

Identification As with any amateur radio mode, stations must identify at least once every 10 minutes. One acceptable method for doing so is to transmit one's call sign inside an ICMP echo request (commonly known as a ping). If the access point is set to "master" (base station) then the user's call sign may be set as the "SSID" and therefore will be transmitted at regular intervals (usually 100 milliseconds, the default beacon interval).

It is also possible to automatically send an amateur call sign in plain text (ASCII) every 10 minutes using DHCP. This requires that a computer's hostname be set to the call sign of the amateur operator and that the DHCP server's lease time be set to less than or equal to 10 minutes. With this method implemented the computer will send a DNS "push" request that includes the local computers hostname every time the DHCP lease is renewed. This method is supported by all modern operating systems including but not limited to Windows, Mac OS X, BSD, and Linux.

802.11 hardware may transmit and receive the entire time it is powered on even if the user is not sending data. Periodic transmissions called "keep-alives" are made to keep the base station aware of the client's continued presence. A BSS Max Idle Period setting reported by the base station determines how often the client must transmit to stay associated. Power-saving features such as 802.11v can help reduce the need of keep-alives.

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