Editing Orthogonal frequency-division multiplexing (section)

==Usage==
OFDM is used in:
* [[Digital Radio Mondiale]] (DRM)
* [[Digital Audio Broadcasting]] (DAB)
* Digital television [[DVB-T]]/[[DVB-T2|T2]] (terrestrial), [[ATSC 3.0]] (terrestrial), [[DVB-H]] (handheld), [[DMB-T/H]], [[DVB-C2]] (cable)<!--single-carrier: DVB-S, DVB-S2, DVB-C -->
* Wireless LAN [[IEEE 802.11a]], [[IEEE 802.11g]], [[IEEE 802.11n]], [[IEEE 802.11ac]], and [[IEEE 802.11ad]]
* [[WiMAX]]
* [[Li-Fi]]
* ADSL ([[G.dmt]]/[[ITU G.992.1]])
* [[LTE (telecommunication)|LTE]] and [[LTE Advanced]] [[4G]] mobile networks
* [[Digital enhanced cordless telecommunications|DECT]] cordless phones 
* Modern narrow and broadband power line communications<ref name="BERGU14">{{cite book|editor1=Berger, Lars T.|editor2=Schwager, Andreas |editor3=Pagani, Pascal|editor4=Schneider, Daniel M.|date=February 2014|title=MIMO Power Line Communications: Narrow and Broadband Standards, EMC, and Advanced Processing|pages=3–37 |publisher=CRC Press|series=Devices, Circuits, and Systems|isbn=9781466557529|doi=10.1201/b16540-1 |chapter=Introduction to Power Line Communication Channel and Noise Characterisation }}</ref>

===OFDM system comparison table===
Key features of some common OFDM-based systems are presented in the following table.
{| class="wikitable"
|-
! Standard name
! [[Digital Audio Broadcasting|DAB]] [[Eureka 147]]
! [[DVB-T]]
! [[DVB-H]]
! [[Digital Terrestrial Multimedia Broadcast|DTMB]]
! [[DVB-T2]]
! [[IEEE 802.11a]]
|-
! Year ratified
| 1995
| 1997
| 2004
| 2006
| 2007
| 1999
|-
! Frequency range of <br />today's equipment (MHz)
| {{nowrap|174–240}}, {{nowrap|1,452–1,492}}
| {{nowrap|470–862}}, {{nowrap|174–230}}
| {{nowrap|470–862}}
| {{nowrap|48–870}}
|
| {{nowrap|4,915–6,100}}
|-
! Channel spacing, <br />''B'' (MHz)
| 1.712
| 6, 7, 8
| 5, 6, 7, 8
| 6, 7, 8
| 1.7, 5, 6, 7, 8, 10
| 20
|-
! FFT size, {{nowrap|k {{=}} 1,024}}
| Mode I: 2k<br />Mode II: 512<br />Mode III: 256<br />Mode IV: 1k
| 2k, 8k
| 2k, 4k, 8k
| 1 (single-carrier)<br />4k (multi-carrier)
| 1k, 2k, 4k, 8k, 16k, 32k
| 64
|-
! Number of non-silent subcarriers, ''N''
| Mode I: 1,536<br />Mode II: 384<br />Mode III: 192<br />Mode IV: 768
| 2K mode: 1,705<br />8K mode: 6,817
| 1,705, 3,409, 6,817
| 1 (single-carrier)<br />3,780 (multi-carrier)
| 853–27,841 (1K normal to 32K extended carrier mode)
| 52
|-
! Subcarrier modulation scheme
| {{Frac|π|4}}-DQPSK
| QPSK,<ref name="QPSK">4QAM is equivalent to QPSK</ref> 16QAM, 64QAM
| QPSK,<ref name="QPSK" /> 16QAM, 64QAM
| 4QAM,<ref name="QPSK" /> 4QAM-NR,<ref>NR refers to Nordstrom-Robinson code</ref> 16QAM, 32QAM, 64QAM
| QPSK, 16QAM, 64QAM, 256QAM
| BPSK, QPSK,<ref name="QPSK" /> 16QAM, 64QAM
|-
! Useful symbol <br />length, ''T<sub>U</sub>'' (μs)
| Mode I: 1,000<br />Mode II: 250<br />Mode III: 125<br />Mode IV: 500
| 2K mode: 224<br />8K mode: 896
| 224, 448, 896
| 500 (multi-carrier)
| 112–3,584 (1K to 32K mode on 8&nbsp;MHz channel)
| 3.2
|-
! Additional guard <br />interval, ''T<sub>G</sub>''/''T<sub>U</sub>''
| 24.6% (all modes)
| {{Frac|1|4}}, {{Frac|1|8}}, {{Frac|1|16}}, {{Frac|1|32}}
| {{Frac|1|4}}, {{Frac|1|8}}, {{Frac|1|16}}, {{Frac|1|32}}
| {{Frac|1|4}}, {{Frac|1|6}}, {{Frac|1|9}}
| 1/128, 1/32, 1/16, 19/256, 1/8, 19/128, 1/4 <br />(for 32k mode maximum 1/8)
| {{Frac|1|4}}
|-
! Subcarrier spacing, <br /><math display="inline">\Delta f = \frac{1}{T_U} \approx \frac{B}{N}</math> (Hz)
| Mode I: 1,000<br />Mode II: 4,000<br />Mode III: 8,000<br />Mode IV: 2,000
| 2K mode: 4,464<br />8K mode: 1,116
| 4,464, 2,232, 1,116
| 8 M (single-carrier)<br />2,000 (multi-carrier)
| 279–8,929 (32K down to 1K mode)
| 312.5 K
|-
! Net bit rate, <br />''R'' (Mbit/s)
| 0.576–1.152
| 4.98–31.67 <br />({{abbr|typ.|typically}} 24.13)
| 3.7–23.8
| 4.81–32.49
| Typically 35.4
| 6–54
|-
! [[Link spectral efficiency]], <br />''R''/''B'' (bit/s·Hz)
| 0.34–0.67
| 0.62–4.0 ({{abbr|typ.|typically}} 3.0)
| 0.62–4.0
| 0.60–4.1
| 0.87–6.65
| 0.30–2.7
|-
! Inner [[forward error correction|FEC]]
| [[Convolutional code|Conv. coding]] with equal error protection code rates: <br />{{Frac|1|4}}, {{Frac|3|8}}, {{Frac|4|9}}, {{Frac|1|2}}, {{Frac|4|7}}, {{Frac|2|3}}, {{Frac|3|4}}, {{Frac|4|5}}

Unequal error protection with avg. code rates of: <br />~0.34, 0.41, 0.50, 0.60, and 0.75
| [[Convolutional code|Conv. coding]] with code rates: <br/>{{Frac|1|2}}, {{Frac|2|3}}, {{Frac|3|4}}, {{Frac|5|6}}, or {{Frac|7|8}}
| [[Convolutional code|Conv. coding]] with code rates: <br/>{{Frac|1|2}}, {{Frac|2|3}}, {{Frac|3|4}}, {{Frac|5|6}}, or {{Frac|7|8}}
| [[Low-density parity-check code|LDPC]] with code rates: <br/>0.4, 0.6, or 0.8
| [[LDPC]]: {{frac|1|2}}, {{frac|3|5}}, {{frac|2|3}}, {{frac|3|4}}, {{frac|4|5}}, {{frac|5|6}}
| [[Convolutional code|Conv. coding]] with code rates: <br/>{{Frac|1|2}}, {{Frac|2|3}}, or {{Frac|3|4}}
|-
! Outer [[forward error correction|FEC]]
| Optional [[Reed–Solomon error correction|RS]] (120, 110, {{nowrap|t {{=}} 5}})
| [[Reed–Solomon error correction|RS]] (204, 188, {{nowrap|t {{=}} 8}})
| [[Reed–Solomon error correction|RS]] (204, 188, {{nowrap|t {{=}} 8}}) + MPE-FEC
| [[BCH code]] (762, 752)
| [[BCH code]]
| {{n/a|None}}
|-
! Maximum travelling <br />speed (km/h)
| 200–600
| 53–185, varies with transmission frequency
|
|
|
|
|-
! Time [[bit interleaving|interleaving]] <br />depth (ms)
| 384
| 0.6–3.5
| 0.6–3.5
| 200–500
| Up to 250 (500 with extension frame)
|
|-
! [[#Adaptive transmission|Adaptive transmission]]
| {{n/a|None}}
| {{n/a|None}}
| {{n/a|None}}
|
| {{n/a|None}}
|
|-
! [[Multiple access method]]
| {{n/a|None}}
| {{n/a|None}}
| {{n/a|None}}
|
| {{n/a|None}}
|
|-
! Typical [[source coding]]
| 192&nbsp;[[kbit/s]] [[MPEG2]] Audio layer 2
| 2–18&nbsp;Mbit/s Standard – HDTV H.264 or MPEG2
| H.264
| Not defined (video: MPEG-2, H.264, H.265 and/or [[Audio Video Standard|AVS+]]; audio: [[MPEG-1 Audio Layer II|MP2]] or [[Dynamic Resolution Adaptation|DRA]] or [[Dolby AC-3|AC-3]])
| H.264 or MPEG2 (audio: AAC HE, Dolby Digital AC-3 (A52), MPEG-2 AL 2)
|
|}

===ADSL===
OFDM is used in [[asymmetric digital subscriber line|ADSL]] connections that follow the [[ANSI T1.413 Issue 2|ANSI T1.413]] and [[G.dmt]] (ITU G.992.1) standards, where it is called ''discrete multitone modulation'' (DMT).<ref>{{cite web |publisher=ANSI T1E1 4, pp. 91-157 |date=1991  |title=A Multicarrier Primer| url=http://web.mit.edu/~6.962/www/www_fall_2000/cksestok/paper2.pdf}}</ref> DSL achieves high-speed data connections on existing copper wires. OFDM is also used in the successor standards [[ADSL2]], [[ADSL2+]], [[VDSL]], [[VDSL2]], and [[G.fast]]. ADSL2 uses variable subcarrier modulation, ranging from BPSK to 32768QAM (in ADSL terminology this is referred to as bit-loading, or bit per tone, 1 to 15 bits per subcarrier).

Long copper wires suffer from attenuation at high frequencies. The fact that OFDM can cope with this frequency selective attenuation and with narrow-band interference are the main reasons it is frequently used in applications such as ADSL [[modem]]s.

===Powerline Technology===
OFDM is used by many [[Power line communication|powerline]] devices to extend digital connections through power wiring. [[Adaptive modulation]] is particularly important with such a noisy channel as electrical wiring. Some medium speed smart metering [[modem]]s, "Prime" and "G3" use OFDM at modest frequencies (30–100&nbsp;kHz) with modest numbers of channels (several hundred) in order to overcome the intersymbol interference in the power line environment.<ref>{{cite conference |url=http://www.lit.lnt.de/papers/isplc_2011_hoch.pdf |last=Hoch |first=Martin |title=Comparison of PLC G3 and Prime |conference=2011 IEEE Symposium on Powerline Communication and its Applications |url-status=dead |archive-url=https://web.archive.org/web/20170810045448/http://www.lit.lnt.de/papers/isplc_2011_hoch.pdf |archive-date=2017-08-10}}</ref>
The [[IEEE 1901]] standards include two incompatible physical layers that both use OFDM.<ref>{{cite journal |title= Recent Developments in the Standardization of Power Line Communications within the IEEE |author= Stefano Galli |journal= IEEE Communications Magazine |date= July 2008 |volume= 46 |number= 7 |pages= 64–71 |doi= 10.1109/MCOM.2008.4557044 |author2= Oleg Logvinov |s2cid= 2650873 |issn=0163-6804}} An overview of P1901 PHY/MAC proposal.</ref> The [[ITU-T]] [[G.hn]] standard, which provides high-speed local area networking over existing home wiring (power lines, phone lines and coaxial cables) is based on a PHY layer that specifies OFDM with adaptive modulation and a Low-Density Parity-Check ([[LDPC]]) FEC code.<ref name="BERGU14" />

===Wireless local area networks (LAN) and metropolitan area networks (MAN)===
OFDM is extensively used in wireless LAN and MAN applications, including [[IEEE 802.11|IEEE 802.11a/g/n]] and [[WiMAX]].

IEEE 802.11a/g/n, operating in the 2.4 and 5&nbsp;GHz bands, specifies per-stream airside data rates ranging from 6 to 54&nbsp;Mbit/s. If both devices can use "HT mode" (added with [[802.11n]]), the top 20&nbsp;MHz per-stream rate is increased to 72.2&nbsp;Mbit/s, with the option of data rates between 13.5 and 150&nbsp;Mbit/s using a 40&nbsp;MHz channel. Four different modulation schemes are used: [[BPSK]], [[QPSK]], 16-[[QAM]], and 64-QAM, along with a set of error correcting rates (1/2–5/6). The multitude of choices allows the system to adapt the optimum data rate for the current signal conditions.

===Wireless personal area networks (PAN)===
OFDM is also now being used in the [http://www.wimedia.com WiMedia/Ecma-368 standard] for high-speed wireless [[personal area network]]s in the 3.1–10.6&nbsp;GHz ultrawideband spectrum (see MultiBand-OFDM).

=== Terrestrial digital radio and television broadcasting ===
Much of Europe and Asia has adopted OFDM for terrestrial broadcasting of digital television ([[DVB-T]], [[DVB-H]] and [[T-DMB]]) and radio ([[EUREKA 147]] [[Digital Audio Broadcasting|DAB]], [[Digital Radio Mondiale]], [[HD Radio]] and [[T-DMB]]).

==== DVB-T ====
By Directive of the European Commission, all television services transmitted to viewers in the European Community must use a transmission system that has been standardized by a recognized European standardization body,<ref>{{cite web|url=http://ec.europa.eu/archives/ISPO/infosoc/legreg/docs/dir95-47en.html|title=DIRECTIVE 95/47/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on the use of standards for the transmission of television signals|website=ec.europa.eu}}</ref> and such a standard has been developed and codified by the DVB Project, ''Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television''.<ref>ETSI Standard: EN 300 744 V1.5.1 (2004-11).</ref> Customarily referred to as DVB-T, the standard calls for the exclusive use of COFDM for modulation. DVB-T is now widely used in Europe and elsewhere for terrestrial digital TV.

==== SDARS ====
The ground segments of the [[Digital Audio Radio Service]] (SDARS) systems used by [[XM Satellite Radio]] and [[Sirius Satellite Radio]] are transmitted using Coded OFDM (COFDM).<ref>{{cite web |website=EE Times |author=Junko Yoshida |date=June 28, 2001 |url=https://www.eetimes.com/agere-gets-sirius-about-satellite-radio-design/ |title=Agere gets Sirius about satellite radio design}}</ref> The word "coded" comes from the use of [[forward error correction]] (FEC).<ref name=cobas />

==== COFDM vs VSB ====

The question of the relative technical merits of COFDM versus [[8VSB]] for terrestrial [[digital television]] has been a subject of some controversy, especially between European and North American technologists and regulators. The [[United States]] has rejected several proposals to adopt the COFDM-based [[DVB-T]] system for its digital television services, and for many years has opted to use [[8VSB]] ([[vestigial sideband modulation]]) exclusively for terrestrial digital television.<ref>{{Cite web|last=Lung|first=Doug|date=2001-01-01|title=8-VSB vs. COFDM: The Debate Continues|url=https://www.tvtechnology.com/opinions/8vsb-vs-cofdm-the-debate-continues|access-date=2021-11-18|website=TVTechnology|language=en}}</ref> However, in November 2017, the [[Federal Communications Commission|FCC]] approved a voluntary transition to [[ATSC 3.0]], a new broadcast standard which is based on COFDM. Unlike the first digital television transition in America, TV stations will not be assigned separate frequencies to transmit ATSC 3.0 and are not required to switch to ATSC 3.0 by any deadline. Televisions sold in the U.S. are also not required to include ATSC 3.0 tuning capabilities. Full-powered television stations are permitted to make the switch to ATSC 3.0, as long as they continue to make their main channel available through a simulcast agreement with another in-market station (with a similar coverage area) through at least November 2022.<ref>{{cite web |title=Report and Order and Further Notice of Proposed Rulemaking |url=https://docs.fcc.gov/public/attachments/FCC-17-158A1.docx |website=Federal Communications Commission |access-date=8 March 2021 |archive-url=https://web.archive.org/web/20201018191123/https://docs.fcc.gov/public/attachments/FCC-17-158A1.docx |archive-date=18 October 2020 |date=20 November 2017}}</ref>

One of the major benefits provided by COFDM is in rendering radio broadcasts relatively immune to [[multipath interference|multipath]] distortion and signal [[fading]] due to atmospheric conditions or passing aircraft. Proponents of COFDM argue it resists multipath far better than 8VSB. Early 8VSB [[digital television|DTV]] (digital television) receivers often had difficulty receiving a signal. Also, COFDM allows [[single-frequency network]]s, which is not possible with 8VSB.

However, newer 8VSB receivers are far better at dealing with multipath, hence the difference in performance may diminish with advances in equalizer design.<ref>{{Cite web|last=TVTechnology|date=2008-04-11|title=Distortions and 8-VSB|url=https://www.tvtechnology.com/news/distortions-and-8vsb|access-date=2021-11-18|website=TVTechnology|language=en}}</ref>

====Digital radio====
<!-- This section is linked from [[Digital Audio Broadcasting]] -->
COFDM is also used for other radio standards, for [[Digital Audio Broadcasting]] (DAB), the standard for digital audio broadcasting at [[VHF]] frequencies, for [[Digital Radio Mondiale]] (DRM), the standard for digital broadcasting at [[shortwave]] and [[medium wave]] frequencies (below 30&nbsp;MHz) and for [[Digital Radio Mondiale#DRM Plus|DRM+]] a more recently introduced standard for digital audio broadcasting at [[VHF]] frequencies. (30 to 174&nbsp;MHz)

The United States again uses an alternate standard, a proprietary system developed by [[iBiquity]] dubbed ''[[HD Radio]]''. However, it uses COFDM as the underlying broadcast technology to add digital audio to AM (medium wave) and FM broadcasts.

Both Digital Radio Mondiale and HD Radio are classified as [[in-band on-channel]] systems, unlike Eureka 147 (DAB: [[Digital Audio Broadcasting]]) which uses separate VHF or [[Ultra high frequency|UHF]] frequency bands instead.

====BST-OFDM used in ISDB====
The ''band-segmented transmission orthogonal frequency-division multiplexing'' (''BST-OFDM'') system proposed for Japan (in the [[ISDB-T]], [[ISDB-TSB]], and [[ISDB-C]] broadcasting systems) improves upon COFDM by exploiting the fact that some OFDM carriers may be modulated differently from others within the same multiplex. Some forms of COFDM already offer this kind of [[hierarchical modulation]], though BST-OFDM is intended to make it more flexible. The 6&nbsp;MHz television channel may therefore be "segmented", with different segments being modulated differently and used for different services.

It is possible, for example, to send an audio service on a segment that includes a segment composed of a number of carriers, a data service on another segment and a television service on yet another segment—all within the same 6&nbsp;MHz television channel. Furthermore, these may be modulated with different parameters so that, for example, the audio and data services could be optimized for mobile reception, while the television service is optimized for stationary reception in a high-multipath environment.

===Ultra-wideband===
[[Ultra-wideband]] (UWB) wireless personal area network technology may also use OFDM, such as in Multiband OFDM (MB-OFDM). This UWB specification is advocated by the [[WiMedia Alliance]] (formerly by both the Multiband OFDM Alliance [MBOA] and the WiMedia Alliance, but the two have now merged), and is one of the competing UWB radio interfaces.

===Flash-OFDM===
''Fast low-latency access with seamless handoff orthogonal frequency-division multiplexing'' (Flash-OFDM), also referred to as F-OFDM, was based on OFDM and also specified higher [[open systems architecture|protocol layers]]. It was developed by Flarion, and purchased by [[Qualcomm]] in January 2006.<ref>{{cite news |title= Qualcomm and Exoteq Sign OFDM/OFDMA License Agreement |date= August 1, 2007 |work= News release |publisher= Qualcomm |url= http://www.qualcomm.com/news/releases/2007/08/01/qualcomm-and-exoteq-sign-ofdmofdma-license-agreement |access-date= July 23, 2011}}</ref><ref>{{cite news |title= Qualcomm Completes Acquisition Of WiMAX Competitor |date= January 19, 2006|work=Network Computing |url= http://www.networkcomputing.com/wireless/229614067 |access-date= July 23, 2011}}</ref> Flash-OFDM was marketed as a packet-switched cellular bearer, to compete with [[GSM]] and [[3G]] networks. As an example, 450&nbsp;MHz frequency bands previously used by [[Nordic Mobile Telephone|NMT-450]] and [[C-Netz|C-Net C450]] (both 1G analogue networks, now mostly decommissioned) in Europe are being licensed to Flash-OFDM operators.{{citation needed |date= July 2011}}

In [[Finland]], the license holder Digita began deployment of a nationwide "@450" wireless network in parts of the country since April 2007. It was purchased by Datame in 2011.<ref>{{cite web |title= Briefly in English |work= @450-Network web site |publisher= Datame |url= http://www.datame.fi/index.php?id=30 |access-date= July 23, 2011 |archive-url= https://web.archive.org/web/20120315210735/http://www.datame.fi/index.php?id=30 |archive-date= March 15, 2012 |url-status= dead }}</ref> In February 2012 Datame announced they would upgrade the 450&nbsp;MHz network to competing [[CDMA2000]] technology.<ref>{{Cite journal |title=@450 siirtyy cdma2000-tekniikkaan - jopa puhelut mahdollisia |journal=[[Tietoviikko]] |author=Aleksi Kolehmainen |date=February 8, 2012 |url=http://www.tietoviikko.fi/kaikki_uutiset/450+siirtyy+cdma2000tekniikkaan++jopa+puhelut+mahdollisia/a773169 |archive-url=https://web.archive.org/web/20120210214658/http://www.tietoviikko.fi/kaikki_uutiset/450+siirtyy+cdma2000tekniikkaan++jopa+puhelut+mahdollisia/a773169 |url-status=dead |archive-date=February 10, 2012 |language=fi }}</ref>

[[Slovak Telekom]] in [[Slovakia]] offers Flash-OFDM connections<ref>{{cite web |title= Mapy pokrytia |work= Slovak Telekom web site |url= http://www.telekom.sk/osobne/pomoc-a-podpora/servis-pre-vas/mapa-pokrytia/ |language= sk |access-date= May 30, 2012 |archive-date= May 31, 2012 |archive-url= https://web.archive.org/web/20120531053123/http://www.telekom.sk/osobne/pomoc-a-podpora/servis-pre-vas/mapa-pokrytia/ |url-status= dead }}</ref> with a maximum downstream speed of 5.3&nbsp;Mbit/s, and a maximum upstream speed of 1.8&nbsp;Mbit/s, with a coverage of over 70 percent of Slovak population.{{citation needed |date= July 2011}} The Flash-OFDM network was switched off in the majority of Slovakia on 30 September 2015.<ref>{{cite news |title= Slovak Telekom closed Flash-OFDM network|date= November 5, 2015 |work= ceeitandtelecom |url= http://www.ceeitandtelecom.com/news/252913/slovak-telekom-closed-flash-ofdm-network }}</ref>

[[T-Mobile International AG|T-Mobile]] Germany used Flash-OFDM to backhaul Wi-Fi HotSpots on the Deutsche Bahn's ICE high speed trains between 2005 and 2015, until switching over to UMTS and LTE.<ref>{{cite news |title= Ins Netz bei Tempo 300 |date= December 23, 2014 |publisher= heise online |url= https://www.heise.de/ct/ausgabe/2015-2-ICE-Zuege-bekommen-schnelles-Internet-2500736.html |access-date= December 20, 2016 |archive-date= December 21, 2016 |archive-url= https://web.archive.org/web/20161221162556/https://www.heise.de/ct/ausgabe/2015-2-ICE-Zuege-bekommen-schnelles-Internet-2500736.html |url-status= dead }}</ref>

American wireless carrier [[Nextel Communications]] field tested wireless broadband network technologies including Flash-OFDM in 2005.<ref>{{cite news |title= Nextel Flash-OFDM: The Best Network You May Never Use |date= March 2, 2005 |work= PC Magazine |url= https://www.pcmag.com/article2/0,2817,1770838,00.asp |access-date= July 23, 2011 }}</ref> [[Sprint Nextel|Sprint]] purchased the carrier in 2006 and decided to deploy the mobile version of [[WiMAX]], which is based on [[Orthogonal frequency-division multiple access|Scalable Orthogonal Frequency-Division Multiple Access]] (SOFDMA) technology.<ref>{{cite news |title= Sprint Nextel Goes To The WiMax |date= August 8, 2006 |author= Sascha Segan |work= PC Magazine |url= https://www.pcmag.com/article2/0,2817,2000732,00.asp |access-date= July 23, 2011 |archive-url=https://web.archive.org/web/20181130135655/https://www.pcmag.com/article2/0,2817,2000732,00.asp |archive-date=2018-11-30 }}</ref>

Citizens Telephone Cooperative launched a mobile broadband service based on Flash-OFDM technology to subscribers in parts of [[Virginia]] in March 2006. The maximum speed available was 1.5&nbsp;Mbit/s.<ref>{{cite news |title= Citizens Offers First "Truly Mobile" Wireless Internet in Christiansburg and other parts of the New River Valley |work= News release |publisher= Citizens Wireless |date= March 28, 2006 |url= http://www.citizens.coop/aboutus/newsreleases/TrulyMobileWireless.pdf |access-date= July 23, 2011 |archive-date= July 18, 2011 |archive-url= https://web.archive.org/web/20110718162144/http://www.citizens.coop/aboutus/newsreleases/TrulyMobileWireless.pdf |url-status= dead }}</ref> The service was discontinued on April 30, 2009.<ref>{{cite web |title= Thank you for supporting Citizens Mobile Broadband |year= 2009 |publisher= Citizens Wireless |url= http://www.citizens.coop/internet/mobilebroadband.shtm |access-date= July 23, 2011 |archive-url= https://web.archive.org/web/20110718162204/http://www.citizens.coop/internet/mobilebroadband.shtm |archive-date= July 18, 2011 |url-status= dead }}</ref>