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High-speed multimedia radio

January 01, 1970

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.

A typical piece of equipment used for HSMM (Linksys WRT54G)

Basics edit

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).[1][2][3][4][5] 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 edit

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 edit

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.

US / FCC Frequencies and channels edit

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 red should not be used.

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.

3.4 GHz 802.11b/g
 

5.8 GHz 802.11a
 

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

Channels and power edit

FCC / United States edit

802.11a edit

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 edit

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 edit

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 edit

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.

802.11y edit

The 802.11y amateur radio band consists of 24 overlapping channels in the 3.4 GHz (9 cm) band. The 802.11y standard uses OFDM or "Orthogonal Frequency Division Multiplexing" 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.

Frequency sharing edit

FCC / United States edit

802.11a edit

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.

802.11b/g/n edit

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.

802.11y edit

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 edit

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" 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 (ASCII) 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 edit

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[citation needed], 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 (5 cm) or 2.4 GHz (13 cm) amateur radio bands. Transverters or "frequency converters" can also be used to move HSMM 802.11b/g/n operations from the 2.4 GHz (13 cm) band to the 3.4 GHz (9 cm) amateur radio band. Such relocation provides a measure of security by operating outside the channels available to unlicensed (Part 15) 802.11 devices.

Custom frequencies edit

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 Custom Regulatory Database 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 (or frequency converter) technology.

420 MHz edit

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. (Note that 420–430 MHz operation is not allowed near the Canada–US border. Refer to the "Line A" rule.)

900 MHz edit

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 edit

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 edit

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 (9 cm) 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 (Point-to-Point) 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 (Waterproof) 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 (shipborne and ground-based) radar operations and covers 60 percent of the U.S. population. This however may change due to a recent FCC NPRM & Order.

5.8 GHz custom frequencies edit

Using professional grade hardware or modified consumer grade hardware it is possible to operate on 802.11a channels 116–140 (5.57–5.71 GHz) and channels above 165 (> 5.835 GHz). These frequencies are outside of the FCC-allocated Part 15 unlicensed band, but still inside of the 5.8 GHz (5 cm) amateur radio band. Modifying consumer hardware to operate on these expanded channels often involves installing after-market firmware and/or changing the "country code" setting of the wireless card. When buying professional grade hardware, many companies will authorize the use of these expanded frequencies for a small additional fee.

Custom firmware edit

One popular way to access amateur-only frequencies is to modify an off-the-shelf access point with custom firmware. This custom firmware is freely available on the Internet from projects such as DD-WRT and OpenWrt. The AREDN Project supports off-the-shelf firmware that supports Part-97-only frequencies on Ubiquiti and TP-Link hardware.[8] A popular piece of hardware that is modified is the Linksys WRT54GL because of the widespread availability of both the hardware and third-party firmware, however, the Linksys hardware is not frequency agile due to the closed nature of the Linksys drivers.

See also edit

References edit

  1. ^ "Amateur Radio Emergency Data Network". www.arednmesh.org.
  2. ^ "Broadband-Hamnet". www.broadband-hamnet.org.
  3. ^ "ARRL :: Warning". www.arrl.org.
  4. ^ "Using IEEE 802.11b Operating Under Part 97 of the FCC Rules". www.arrl.org.
  5. ^ HSMM Radio Equipment arrl.org
  6. ^ a b c "IEEE 802.11ah | Sub GHz Wi-Fi | Electronics Notes". www.electronics-notes.com.
  7. ^ "Operation in U-NII Bands – 802.11 Channel Plan (§15.407)". FCC. Retrieved 30 July 2023.
  8. ^ "Amateur Radio Emergency Data Network". AREDNmesh.org.

External links edit

  • FCC Part 97 Rules
  • FCC Part 15 Rules
  • FCC rejection of OFDM as Spread Spectrum
  • Using Part 15 Wireless Ethernet Devices For Amateur Radio
  • 5.0 GHz (802.11a/h) Channels and Frequencies
  • BROADBAND-HAMNET.ORG Wireless Mesh: The award-winning Broadband-Hamnet – A project started in Austin, TX but has become the Ham Broadband standard worldwide, to create broadband-speed (>1 Mbit/s) mesh networks for Ham Radio use.
  • AREDN – Amateur Radio Emergency Data Network: This project picks up where Broadband-Hamnet leaves off and advances the Open Source software to widely available commercial devices and expands the technology beyond 2.4 GHz to the 900 MHz, 3.4 GHz, and 5.7 GHz ham bands.
  • Enabling Innovative Small Cell Use In 3.5 GHZ Band NPRM & Order

January 01, 1970
high, speed, multimedia, radio, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, examples, perspective, this, article, deal, primarily, with, united, states, represent, . This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject You may improve this article discuss the issue on the talk page or create a new article as appropriate December 2010 Learn how and when to remove this message This article includes a list of general references but it lacks sufficient corresponding inline citations Please help to improve this article by introducing more precise citations April 2009 Learn how and when to remove this message Learn how and when to remove this message 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 A typical piece of equipment used for HSMM Linksys WRT54G Contents 1 Basics 2 Capabilities 3 Bandwidths and Speeds 4 US FCC Frequencies and channels 5 Channels and power 5 1 FCC United States 5 1 1 802 11a 5 1 2 802 11b 5 1 3 802 11g 5 1 4 802 11n 5 1 5 802 11y 6 Frequency sharing 6 1 FCC United States 6 1 1 802 11a 6 1 2 802 11b g n 6 1 3 802 11y 7 Identification 8 Security 9 Custom frequencies 9 1 420 MHz 9 2 900 MHz 9 3 2 4 GHz custom frequencies 9 4 3 3 3 8 GHz 9 5 5 8 GHz custom frequencies 10 Custom firmware 11 See also 12 References 13 External linksBasics editThe 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 1 2 3 4 5 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 editHSMM 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 editHSMM 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 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 6 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 6 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 6 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 MbpsUS FCC Frequencies and channels editThe 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 red should not be used 802 11b g n 13 cm Channel Center Frequency FCC Rules 2 2 397 GHz Part 97 1 2 402 GHz Part 97 0 2 407 GHz Guard band 1 2 412 GHz Part 97 amp Part 15 2 2 417 GHz Part 97 amp Part 15 3 2 422 GHz Part 97 amp Part 15 4 2 427 GHz Part 97 amp Part 15 5 2 432 GHz Part 97 amp Part 15 6 2 437 GHz Part 97 amp Part 15 must use 5 10Mhz bandwidth 802 11y 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 97 802 11a 5 cm 7 Channel Center Frequency FCC Rules 132 5 660 GHz TDWR 134 5 670 GHz TDWR 136 5 680 GHz Part 97 amp Part 15 138 5 690 GHz Part 97 amp Part 15 140 5 700 GHz Part 97 amp Part 15 142 5 710 GHz Part 97 amp Part 15 144 5 720 GHz Part 97 amp Part 15 149 5 745 GHz Part 97 amp Part 15 151 5 755 GHz Part 97 amp Part 15 153 5 765 GHz Part 97 amp Part 15 155 5 775 GHz Part 97 amp Part 15 157 5 785 GHz Part 97 amp Part 15 159 5 795 GHz Part 97 amp Part 15 161 5 805 GHz Part 97 amp Part 15 165 5 825 GHz Part 97 amp 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 3 4 GHz 802 11b g nbsp 5 8 GHz 802 11a nbsp Acronyms Used amateur radio ISM Radar Channels and power editFCC United States edit 802 11a edit 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 edit 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 edit 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 edit 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 802 11y edit The 802 11y amateur radio band consists of 24 overlapping channels in the 3 4 GHz 9 cm band The 802 11y standard uses OFDM or Orthogonal Frequency Division Multiplexing 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 Frequency sharing editFCC United States edit 802 11a edit 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 802 11b g n edit 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 802 11y edit 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 editAs 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 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 ASCII 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 editBecause 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 citation needed 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 5 cm or 2 4 GHz 13 cm amateur radio bands Transverters or frequency converters can also be used to move HSMM 802 11b g n operations from the 2 4 GHz 13 cm band to the 3 4 GHz 9 cm amateur radio band Such relocation provides a measure of security by operating outside the channels available to unlicensed Part 15 802 11 devices Custom frequencies editUsing 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 Custom Regulatory Database 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 or frequency converter technology 420 MHz edit 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 Note that 420 430 MHz operation is not allowed near the Canada US border Refer to the Line A rule 900 MHz edit 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 edit 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 edit 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 9 cm 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 Point to Point 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 Waterproof 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 shipborne and ground based radar operations and covers 60 percent of the U S population This however may change due to a recent FCC NPRM amp Order 5 8 GHz custom frequencies edit Using professional grade hardware or modified consumer grade hardware it is possible to operate on 802 11a channels 116 140 5 57 5 71 GHz and channels above 165 gt 5 835 GHz These frequencies are outside of the FCC allocated Part 15 unlicensed band but still inside of the 5 8 GHz 5 cm amateur radio band Modifying consumer hardware to operate on these expanded channels often involves installing after market firmware and or changing the country code setting of the wireless card When buying professional grade hardware many companies will authorize the use of these expanded frequencies for a small additional fee Custom firmware editOne popular way to access amateur only frequencies is to modify an off the shelf access point with custom firmware This custom firmware is freely available on the Internet from projects such as DD WRT and OpenWrt The AREDN Project supports off the shelf firmware that supports Part 97 only frequencies on Ubiquiti and TP Link hardware 8 A popular piece of hardware that is modified is the Linksys WRT54GL because of the widespread availability of both the hardware and third party firmware however the Linksys hardware is not frequency agile due to the closed nature of the Linksys drivers See also editMap of AREDN network HSMM nodes Amateur radio emergency communications Amateur radio frequency allocations AMPRNet DD WRT Metropolitan Area Network Orthogonal frequency division multiplexing Packet Radio Spread spectrum Tomato Firmware Ultra wideband Wireless Distribution System Wireless LAN List of HSMM nodesReferences edit Amateur Radio Emergency Data Network www arednmesh org Broadband Hamnet www broadband hamnet org ARRL Warning www arrl org Using IEEE 802 11b Operating Under Part 97 of the FCC Rules www arrl org HSMM Radio Equipment arrl org a b c IEEE 802 11ah Sub GHz Wi Fi Electronics Notes www electronics notes com Operation in U NII Bands 802 11 Channel Plan 15 407 FCC Retrieved 30 July 2023 Amateur Radio Emergency Data Network AREDNmesh org External links editFCC Part 97 Rules FCC Part 15 Rules FCC rejection of OFDM as Spread Spectrum Using Part 15 Wireless Ethernet Devices For Amateur Radio 5 0 GHz 802 11a h Channels and Frequencies BROADBAND HAMNET ORG Wireless Mesh The award winning Broadband Hamnet A project started in Austin TX but has become the Ham Broadband standard worldwide to create broadband speed gt 1 Mbit s mesh networks for Ham Radio use AREDN Amateur Radio Emergency Data Network This project picks up where Broadband Hamnet leaves off and advances the Open Source software to widely available commercial devices and expands the technology beyond 2 4 GHz to the 900 MHz 3 4 GHz and 5 7 GHz ham bands Enabling Innovative Small Cell Use In 3 5 GHZ Band NPRM amp Order Retrieved from https en wikipedia org w index php title High speed multimedia radio amp oldid 1221639380, wikipedia, wiki, book, books, library,

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