High-speed multimedia radio
High-speed multimedia radio is the implementation of high-speed wireless TCP/IP data networks over amateur radio frequency allocations using commercial off-the-shelf 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, 2.4 GHz, 3.4 GHz, and 5.8 GHz. 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.
Capabilities
HSMM can support most of the traffic that the Internet currently does, including video chat, voice, instant messaging, email, the Web, file transfer, 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. 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 s 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 equipment can be used, further increasing range at the cost of speed.| 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
| 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
| 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 |
| 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 |
| 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 |
| 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 |
| 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.| Channel | Center Frequency | FCC Rules |
| −2* | 2.397 GHz* | Part 97* |
| −1 | 2.402 GHz | Part 97 |
| 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
| 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 |
| 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 |
The following images show the overlapping relationship of the Part 15 unlicensed bands and the Part 97 licensed bands. The images are not to scale.
2.4 GHz 802.11b/g
5.8 GHz 802.11a
Channels and power
[FCC] / [United States]
802.11a
802.11b
802.11g
802.11n
802.11y
Frequency sharing
[FCC] / [United States]
802.11a
802.11b/g/n
802.11y
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. If the access point is set to "master" then the user's call sign may be set as the "SSID" and therefore will be transmitted at regular intervals.It is also possible to use a DDNS "push" request to automatically send an amateur call sign in plain text every 10 minutes. This requires that a computer's hostname be set to the call sign of the amateur operator and that the DHCP servers 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.
Security
Because the meaning of amateur transmissions may not be obscured, security measures that are implemented must be published. This does not necessarily restrict authentication or login schemes, but it does restrict fully encrypted communications. This leaves the communications vulnerable to various attacks once the authentication has been completed. This makes it very difficult to keep unauthorized users from accessing HSMM networks, although casual eavesdroppers can effectively be deterred. Current schemes include using MAC address filtering, WEP and WPA/WPA2. MAC address filtering and WEP are all hackable by using freely available software from the Internet, making them the less secure options. Per FCC rules the encryption keys themselves must be published in a publicly accessible place if using WEP, WPA/WPA2 or any other encryption, thereby undermining the security of their implementation. Such measures however are effective against casual or accidental wireless intrusions.Using professional or modified hardware it is possible to operate on 802.11a channels that are outside the FCC authorized Part 15 bands but still inside the 5.8 GHz or 2.4 GHz amateur radio bands. Transverters or "frequency converters" can also be used to move HSMM 802.11b/g/n operations from the 2.4 GHz band to the 3.4 GHz amateur radio band. Such relocation provides a measure of security by operating outside the channels available to unlicensed 802.11 devices.
Custom frequencies
Using amateur-only frequencies provide better security and interference characteristics to amateur radio operators. In the past it used to be easy to use modified consumer grade hardware to operate 802.11 on channels that are outside of the normal FCC allocated frequencies for unlicensed users but still inside an amateur radio band. However, regulatory concerns with the non-authorized use of licensed band frequencies is making it harder. The newer Linux drivers implement that prevents a casual user from operating outside of the country-specific operating bands. This requires the use of radio transceivers based on the use of Transverter technology.420 MHz
Doodle Labs is a privately held manufacturing company with headquarters in Singapore that designs and manufactures a line of long range Wireless Data Transceiver devices.The DL-435 is mini-PCI adapter based on the Atheros wireless chipset.
XAGYL Communications is a Canadian Distributor of Ultra High-Speed, Long Range Wireless equipment.
The XAGYL Communications XC420M is a mini-PCI adapter based on the Atheros wireless chipset.
The Atheros chipset's ability to use 5 MHz transmission bandwidths could allow part 97 operation on the 420–430 MHz ATV sub-band.
900 MHz
Transverters as well as using older 802.11 hardware such as the original NRC WaveLan or FHSS modems made by Aerocomm and FreeWave make it possible to operate on this band. Ubiquiti M9-series also provide hardware capable in this band. Beware that noise floor on this band in the larger cities is usually very high, which severely limits receiver performance.2.4 GHz custom frequencies
Using professional grade hardware or modified consumer grade hardware it is possible to operate on 802.11b/g hardware on channels that are effectively: "−1" at 2.402 GHz, and "−2" at 2.397 GHz. Using these channels allows amateur operators to move away from unlicensed Part 15 operators but may interfere with amateur radio satellite downlinks near 2.400 GHz and 2.401 GHz.3.3–3.8 GHz
Frequency conversion involves the use of transverters that convert the operating frequency of the 802.11b/g device from 2.4 GHz to another band entirely. Transverter is a technical term and is rarely used to describe these products which are more commonly known as frequency converters, up/down converters, and just converters. Commercially available converters can convert a 2.4 GHz 802.11b/g signal to the 3.4 GHz band which is not authorized for unlicensed Part 15 users.Ubiquiti Networks has four radios based on Atheros chipsets with transverters on board for this band. The PowerBridge M3 and M365 for 3.5 GHz and 3.65 GHz respectively for aesthetically low profile PtP connections. The Nanostation M3 and M365 are in a molded weatherproof case with 13.7 dBi dual polarization antennas. The Rocket M3, M365 and M365 GPS are in a rugged case using a hi-power, very linear 2x2 MIMO radio with 2x RP-SMA connectors. Finally the NanoBridge M3 and M365 for long range PtP connections. These devices use N mode Atheros chipsets along with Ubiquiti's airMax TDMA protocol to overcome the hidden node problem which is commonly an issue when using ptmp wireless outdoors. UBNT currently does not allow sales to U.S. Amateurs and only sell these radios under FCC License. This may be due to exclusion areas near coasts and US Navy installations. The 3.5 GHz band is currently used for DoD or Navy radar operations and covers 60 percent of the U.S. population. This however may change due to a recent FCC NPRM & .