White spaces (radio)

Last updated

In telecommunications, white spaces refer to radio frequencies allocated to a broadcasting service but not used locally. [1] National and international bodies assign frequencies for specific uses and, in most cases, license the rights to broadcast over these frequencies. This frequency allocation process creates a bandplan which for technical reasons assigns white space between used radio bands or channels to avoid interference. In this case, while the frequencies are unused, they have been specifically assigned for a purpose, such as a guard band. Most commonly however, these white spaces exist naturally between used channels, since assigning nearby transmissions to immediately adjacent channels will cause destructive interference to both.

Contents

In addition to white space assigned for technical reasons, there is also unused radio spectrum which has either never been used, or is becoming free as a result of technical changes. In particular, the switchover to digital television frees up large areas between about 50 MHz and 700 MHz. This is because digital transmissions can be packed into adjacent channels, while analog ones cannot. This means that the band can be compressed into fewer channels, while still allowing for more transmissions.

In the United States, the abandoned television frequencies are primarily in the upper UHF 700-megahertz band, covering TV channels 52 to 69 (698 to 806 MHz). U.S. television and its white spaces will continue to exist in UHF frequencies, as well as VHF frequencies for which mobile users and white-space devices require larger antennas. In the rest of the world, the abandoned television channels are VHF, and the resulting large VHF white spaces are being reallocated for the worldwide (except the U.S.) digital radio standard DAB and DAB+, and DMB.[ citation needed ]

White-spaces devices

Various proposals, including IEEE 802.11af, IEEE 802.22 [2] [3] and those from the White Spaces Coalition, have advocated using white spaces left by the termination of analog TV to provide wireless broadband Internet access. A device intended to use these available channels is a white-spaces device (WSD). Such devices are designed to detect the presence of existing but unused areas of airwaves, such as those reserved for analog television, and utilize them for White Space Internet signals. Such technology is predicted to improve the availability of broadband Internet and Wi-Fi in rural areas. [4] [5]

Early ideas proposed including GNSS receivers and programming each WSD with a database of all TV stations in an area, however this would not have avoided other non-stationary or unlicensed users in the area, or any stations licensed or altered after the device was made. Additionally, these efforts may impact wireless microphones, medical telemetry, and other technologies that have historically relied on these open frequencies.[ citation needed ]

Professional wireless microphones have used white space for decades previous to so-called white space devices. [1]

Comparison with Wi-Fi

Like Wi-Fi, TV whitespace is a wireless connection, but uses different frequency bands. TV white space operates in 470 MHz to 698 MHz, whilst Wi-Fi operates in 2.4 and 5 GHz bands. Data transfer speed depends on the model of the radio, the vendor, the antenna length, and other factors. New radios can support more than 50 Mbit/s. Wi-Fi speed similarly depends on several factors, such as range, line of sight, and so on, but may be as much as 1000 Mbit/s using the IEEE 802.11ac standard. Range is a crucial difference between Wi-Fi and TV white space. On average, TV white space range is 6 miles, but it can be less or more depending on factors such as noise, line of sight and so on. One of the three main TV white space manufactures, Carlson wireless, advertises that their radios can go up to 24.8 miles. Both have low power consumption - 20 to 100 watts depending on the device, the antenna length, the vendor, and so on. Both technologies meet the government security standards such as FIPS 197 Compliance (Advanced Encryption Standards). While Wi-Fi works well in cities, TV white space works well in rural areas. [6]

By country

Argentina

Microsoft, in a partnership with the communications authority of Argentina, Ente Nacional de Comunicaciones (ENACOM), planned to deliver wireless access to schools in the province of Mendoza on or around August, 2017. Microsoft will borrow the White Spaces hardware to ENACOM technicians, and national satellite operator ARSAT will act as the ISP. No further trial details has been delivered yet. [7]

Canada

In August 2011, Industry Canada, the Canadian ministry for industry, launched a consultation on "Consultation on a Policy and Technical Framework for the Use of Non-Broadcasting Applications in the Television Broadcasting Bands Below 698 MHz" [8] (pdf). The consultation closed on November 4, 2011. Submissions were received from a wide range of organisations from the telecoms and broadcast industries.

Kenya

A pilot project by Indigo Telecom/Microsoft and the Kenyan government is reportedly delivering bandwidth speeds of up to 16 Mbit/s to three rural communities, which lack electricity - Male, Gakawa and Laikipia, using a solar-powered network. [9]

Namibia

As of July 3,2014, a pilot project called Citizen Connect, a collaboration between the Microsoft 4Afrika Initiative, the MyDigitalBridge Foundation, and the MCA-N (Millennium Challenge Account Namibia), is slated to deliver broadband Internet to "twenty-seven schools and seven circuit offices of the Ministry of Education in Omusati, Oshana and Ohangwena", using "TV White Space technology". [10] [11]

Philippines

In 2014, Microsoft worked with the Philippine government to pilot a program for digitizing the management of remote fishermen. [12]

Singapore

After FCC, Singapore Info-communications Media Development Authority is the second regulator in the world to have TV White Space regulated, ahead of UK and Canada. The Singapore efforts were driven mainly by the Singapore White Spaces Pilot Group (SWSPG) [13] founded by the Institute for Infocomm Research, Microsoft and StarHub. The Institute for Infocomm Research subsequently spun off Whizpace [14] to commercialize TV White Space radio using strong IPs that were developed in the institute since 2006.

South Africa

Google, in a partnership with the Independent Communications Authority of South Africa (ICASA), CSIR, Meraka Institute, the Wireless Access Providers Association (WAPA) and Carlson wireless delivers wireless access to 10 schools through 3 base stations at the campus of Stellenbosch University’s Faculty of Medicine and Health Sciences in Tygerberg, Cape Town. There was an initial trial that took place within 10 schools in order to deliver affordable internet to the selected schools in South Africa without TV interference, and to spread awareness about future TVWS technologies in South Africa. The trial took place over 10 months, from March 25, 2013 to September 25, 2013. [15]

TVWS in Natal TVWS KZN-WA0028.jpg
TVWS in Natal

A second trial involved providing point-to-point Internet connectivity to five rural secondary schools in Limpopo province, with equally good results. [16]

ICASA subsequently issued regulations on the use of television white spaces in 2018. [17] Three temporary TV white space spectrum licenses were issued by ICASA in April 2020, response to the Covid-19 pandemic, in the 470–694 MHz band, to Mthinthe Communications, Levin Global & Morai Solutions. [18]

United Kingdom

Ofcom, the licensing body of spectrum in the UK, has made white-space free to use. [19] [20]

On June 29, 2011, one of the largest commercial tests of white space Wi-Fi was conducted in Cambridge, England. The trial was conducted by Microsoft using technology developed by Adaptrum and backed by a consortium of ISP's and tech companies including Nokia, BSkyB, the BBC, and BT, with the actual network hardware being provided by Neul. In the demonstration, the Adaptrum whitespace system provided the broadband IP connectivity allowing a client-side Microsoft Xbox to stream live HD videos from the Internet. Also as part of the demo, a live Xbox/Kinect video chat was established between two Xbox/Kinect units connected through the same TV whitespace connection. These applications were demonstrated under a highly challenging radio propagation environment with more than 120 dB link loss through buildings, foliage, walls, furniture, people etc. and with severe multipath effects. [21]

In 2017, Microsoft further expanded their research to show that small cell LTE eNodeB's operating in TV White Space could be used to provide cost effective broadband to affordable housing residents. [22]

United States

Full power analog television broadcasts, which operated between the 54  MHz and 806 MHz (54–72, 76–88, 174–216, 470–608, and 614–806) [23] television frequencies (Channels 2-69), ceased operating on June 12, 2009 per a United States digital switchover mandate. At that time, full power TV stations were required to switch to digital transmission and operate only between 54 MHz and 698 MHz. This is also the timetable that the White Spaces Coalition has set to begin offering wireless broadband services to consumers. The delay allows time for the United States Federal Communications Commission (FCC) to test the technology and make sure that it does not interfere with existing television broadcasts. Similar technologies could be used worldwide as much of the core technology is already in place. [24]

Theatrical producers and sports franchises hoped to derail or delay the decision, arguing that their own transmissions – whether from television signals or from wireless microphones used in live music performances – could face interference from new devices that use the white spaces. However, the FCC rejected their arguments, saying enough testing has been done, and through new regulations, possible interference will be minimized.

More of the broadcast spectrum was needed for wireless broadband Internet access, and in March 2009, Massachusetts Senator John Kerry introduced a bill requiring a study of efficient use of the spectrum. [25] Academics have studied the matter and have promoted the idea of using computing technology to capture the benefits of the white space. [26]

Trade groups

The White Spaces Coalition was formed in 2007 by eight large technology companies that planned to deliver high speed internet access beginning in February 2009 to United States consumers via existing white space in unused television frequencies between 54 MHz and 698 MHz (TV Channels 2-51). The coalition expected speeds of 80 Mbit/s and above, and 400 to 800 Mbit/s for white space short-range networking. The group included Microsoft, Google, Dell, HP, Intel, Philips, Earthlink, and Samsung Electro-Mechanics. [27]

Many of the companies involved in the White Spaces Coalition were also involved in the Wireless Innovation Alliance. [28] Another group calling itself the White Space Alliance was formed in 2011. [29]

Google sponsored a campaign named Free the Airwaves with the purpose of switching over the white spaces that were cleared up in 2009 by the DTV conversion process by the FCC and converted to an un-licensed spectrum that can be used by Wi-Fi-like devices. [30] [31] The National Association of Broadcasters disapproved of the project because they claimed it would reduce the broadcast quality of their TV signals. [32]

Preliminary test

The Federal Communications Commission's Office of Engineering and Technology released a report dated July 31, 2007 with results from its investigation of two preliminary devices submitted. The report concluded that the devices did not reliably sense the presence of television transmissions or other incumbent users, hence are not acceptable for use in their current state and no further testing was deemed necessary. [33]

However, on August 13, 2007, Microsoft filed a document with the FCC in which it described a meeting that its engineers had with FCC engineers from the Office of Engineering and Technology on August 9 and 10. At this meeting the Microsoft engineers showed results from their testing done with identical prototype devices and using identical testing methods that "detected DTV signals at a threshold of -114 dBm in laboratory bench testing with 100 percent accuracy, performing exactly as expected." In the presence of FCC engineers, the Microsoft engineers took apart the device that the FCC had tested to find the cause of the poor performance. They found that "the scanner in the device had been damaged and operated at a severely degraded level" which explained the FCC unit's inability to detect when channels were occupied. It was also pointed out that the FCC was in possession of an identical backup prototype that was in perfect operating condition that they had not tested. [34]

FCC decision

TV broadcasters and other incumbent users of this spectrum (both licensed and unlicensed, including makers of wireless audio systems) feared that their systems would no longer function properly if unlicensed devices were to operate in the same spectrum. However, the FCC's Office of Engineering and Technology released a report dated October 15, 2008, which evaluated prototype TV-band white spaces devices submitted by Adaptrum, The Institute for Infocomm Research, Motorola and Philips. The report concluded that these devices had met the burden of proof of concept in their ability to detect and avoid legacy transmissions, [35] although none of the tested devices adequately detected wireless microphone signals in the presence of a digital TV transmitter on an adjacent channel.

On November 4, 2008, the FCC voted 5-0 to approve the unlicensed use of white space, [36] thereby silencing opposition from broadcasters. The actual Second Report and Order was released ten days later and contains some serious obstacles for the development and use of TV Band Devices as they are called by FCC. Devices must both consult an FCC-mandated database to determine which channels are available for use at a given location, and must also monitor the spectrum locally once every minute to confirm that no legacy wireless microphones, video assist devices or other emitters are present. If a single transmission is detected, the device may not transmit anywhere within the entire 6 MHz channel in which the transmission was received. [37] It was hoped that, within a year, this new access will lead to more reliable Internet access and other technologies.

On September 23, 2010, the FCC released a Memorandum Opinion and Order that determined the final rules for the use of white space for unlicensed wireless devices. [38] The new rules removed mandatory sensing requirements which greatly facilitates the use of the spectrum with geolocation based channel allocation. The final rules [39] adopt a proposal from the White Spaces Coalition for very strict emission rules that prevent the direct use of IEEE 802.11 (Wi-Fi) in a single channel effectively making the new spectrum unusable for Wi-Fi technologies.[ citation needed ]

Broadcaster lawsuit

On February 27, 2009, the National Association of Broadcasters (NAB) and the Association for Maximum Service Television asked a Federal court to shut down the FCC's authorization of white space wireless devices. The plaintiffs allege that portable, unlicensed personal devices operating in the same band as TV broadcasts have been proven to cause interference despite FCC tests to the contrary. The lawsuit was filed in a United States Court of Appeals for the District of Columbia Circuit. The petition for review states that the FCC's decision to allow white space personal devices "will have a direct adverse impact" on MSTV's and NAB's members, and that the Commission's decision is "arbitrary, capricious, and otherwise not in accordance with law.". [40] A Motion to Govern the case was due to be considered on February 7, 2011. [41] In May 2012, the NAB announced it was dropping its court challenge of rules that allow the unlicensed use of empty airwaves between existing broadcast channels. [42]

Tests

On October 16, 2009, researchers at Microsoft Research Redmond, Washington built and deployed a white space network called WhiteFi. [43] [44] In this network, multiple clients connected to a single access point over UHF frequencies. The deployment included experiments to test how much data could be sent before interference became audible to nearby wireless microphones.

On February 24, 2010, officials in Wilmington, North Carolina, which was the test market for the transition to digital television, unveiled a new municipal wireless network, after a month of testing. The network used the white spaces made available by the end of analog TV. Spectrum Bridge was to work to make sure TV stations in the market do not receive interference ("no interference issues" have been reported). The smart city network will not compete with cell phone companies but will instead be used for "national purposes", including government and energy monitoring. TV Band Service, made up of private investors, has put up cameras in parks, and along highways to show traffic. Other uses include water level and quality, turning off lights in ball parks, and public Wi-Fi in certain areas. TV Band had an 18-month experimental license. [45]

In 2011, the Yurok Tribe in Humboldt County, California began white space trials with telecommunications equipment provider Carlson Wireless of Arcata, California. [46]

In July 2013, West Virginia University became the first university in the United States to use vacant broadcast TV channels to provide the campus and nearby areas with wireless broadband Internet service. [47]

Also in July 2013, the Port of Pittsburgh evaluated White Space spectrum for enhancing inland waterway safety and utility with telecommunications equipment provider Metric Systems Corporation of Vista, California. [48]

See also

Related Research Articles

<span class="mw-page-title-main">Wireless broadband</span> Telecommunications technology

Wireless broadband is a telecommunications technology that provides high-speed wireless Internet access or computer networking access over a wide area. The term encompasses both fixed and mobile broadband.

The ISM radio bands are portions of the radio spectrum reserved internationally for industrial, scientific, and medical (ISM) purposes, excluding applications in telecommunications. Examples of applications for the use of radio frequency (RF) energy in these bands include RF heating, microwave ovens, and medical diathermy machines. The powerful emissions of these devices can create electromagnetic interference and disrupt radio communication using the same frequency, so these devices are limited to certain bands of frequencies. In general, communications equipment operating in ISM bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation in these bands.

<span class="mw-page-title-main">Ultra high frequency</span> Electromagnetic spectrum 300–3000 MHz

Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter. Radio waves with frequencies above the UHF band fall into the super-high frequency (SHF) or microwave frequency range. Lower frequency signals fall into the VHF or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. They are used for television broadcasting, cell phones, satellite communication including GPS, personal radio services including Wi-Fi and Bluetooth, walkie-talkies, cordless phones, satellite phones, and numerous other applications.

Wireless local loop (WLL) is the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service (POTS) or Internet access to telecommunications customers. Various types of WLL systems and technologies exist.

<span class="mw-page-title-main">WiMAX</span> Wireless broadband standard

Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband communication standards based on the IEEE 802.16 set of standards, which provide physical layer (PHY) and media access control (MAC) options.

<span class="mw-page-title-main">S band</span> Frequency range

The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz). Thus it crosses the conventional boundary between the UHF and SHF bands at 3.0 GHz. The S band is used by airport surveillance radar for air traffic control, weather radar, surface ship radar, and some communications satellites, particularly satellites used by NASA to communicate with the Space Shuttle and the International Space Station. The 10 cm radar short-band ranges roughly from 1.55 to 5.2 GHz. India's regional satellite navigation network (IRNSS) broadcasts on 2.483778 to 2.500278 GHz.

Code of Federal Regulations, Title 47, Part 15 is an oft-quoted part of Federal Communications Commission (FCC) rules and regulations regarding unlicensed transmissions. It is a part of Title 47 of the Code of Federal Regulations (CFR), and regulates everything from spurious emissions to unlicensed low-power broadcasting. Nearly every electronics device sold inside the United States radiates unintentional emissions, and must be reviewed to comply with Part 15 before it can be advertised or sold in the US market.

IEEE 802.22, is a standard for wireless regional area network (WRAN) using white spaces in the television (TV) frequency spectrum. The development of the IEEE 802.22 WRAN standard is aimed at using cognitive radio (CR) techniques to allow sharing of geographically unused spectrum allocated to the television broadcast service, on a non-interfering basis, to bring broadband access to hard-to-reach, low population density areas, typical of rural environments, and is therefore timely and has the potential for a wide applicability worldwide. It is the first worldwide effort to define a standardized air interface based on CR techniques for the opportunistic use of TV bands on a non-interfering basis.

<span class="mw-page-title-main">High-speed multimedia radio</span>

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.

IEEE 802.11y-2008 is an amendment to the IEEE 802.11-2007 standard that enables data transfer equipment to operate using the 802.11a protocol on a co-primary basis in the 3650 to 3700 MHz band except when near a grandfathered satellite earth station. IEEE 802.11y is only being allowed as a licensed band. It was approved for publication by the IEEE on September 26, 2008.

Super Wi-Fi refers to IEEE 802.11g/n/ac/ax Wi-Fi implementations over unlicensed 2.4 and 5 GHz Wi-Fi bands but with performance enhancements for antenna control, multiple path beam selection, advance control for best path, and applied intelligence for load balancing giving it bi-directional connectivity range for standard wifi enabled devices over distances of up to 1,700 meters. Hong Kong–based Altai Technologies developed and patented Super Wi-Fi technology and manufacturers a product line of base stations and access points deployed extensively around the world beginning in 2007. Due to its extended range and advanced interference mitigation, Super Wi-Fi is primarily used for expansive outdoor and heavy industrial use cases. Krysp Wireless, LLC is Altai Technologies' Master Distributor for North America focused on the sale and distribution of Super Wi-Fi products for large enterprises, WISPs and municipal deployments. Altai's Super Wi-Fi technology should not be confused with the FCC's use of the term relating to proposed plans announced in 2012 for using TV white space spectrum to support delivery of long range internet access.

Weightless was a set of low-power wide-area network (LPWAN) wireless technology specifications for exchanging data between a base station and many of machines around it.

The 2016 United States wireless spectrum auction, officially known as Auction 1001, allocated approximately 100 MHz of the United States Ultra High Frequency (UHF) spectrum formerly allocated to UHF television in the 600 MHz band. The spectrum auction and subsequent reallocations were authorized by Title VI of the payroll tax cut extension passed by the United States Congress on February 17, 2012.

IEEE 802.11af, also referred to as White-Fi and Super Wi-Fi, is a wireless computer networking standard in the 802.11 family, that allows wireless local area network (WLAN) operation in TV white space spectrum in the VHF and UHF bands between 54 and 790 MHz. The standard was approved in February 2014. Cognitive radio technology is used to transmit on unused portions of TV channel band allocations, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones.

<span class="mw-page-title-main">Victor Bahl</span> American computer scientist

Victor Bahl is an American Technical Fellow and CTO of Azure for Operators at Microsoft. He started networking research at Microsoft. He is known for his research contributions to white space radio data networks, radio signal-strength based indoor positioning systems, multi-radio wireless systems, wireless network virtualization, edge computing, and for bringing wireless links into the datacenter. He is also known for his leadership of the mobile computing community as the co-founder of the ACM Special Interest Group on Mobility of Systems, Users, Data, and Computing (SIGMOBILE). He is the founder of international conference on Mobile Systems, Applications, and Services Conference (MobiSys), and the founder of ACM Mobile Computing and Communications Review, a quarterly scientific journal that publishes peer-reviewed technical papers, opinion columns, and news stories related to wireless communications and mobility. Bahl has received important awards; delivered dozens of keynotes and plenary talks at conferences and workshops; delivered over six dozen distinguished seminars at universities; written over hundred papers with more than 65,000 citations and awarded over 100 US and international patents. He is a Fellow of the Association for Computing Machinery, IEEE, and American Association for the Advancement of Science.

LTE in unlicensed spectrum is an extension of the Long-Term Evolution (LTE) wireless standard that allows cellular network operators to offload some of their data traffic by accessing the unlicensed 5 GHz frequency band. LTE-Unlicensed is a proposal, originally developed by Qualcomm, for the use of the 4G LTE radio communications technology in unlicensed spectrum, such as the 5 GHz band used by 802.11a and 802.11ac compliant Wi-Fi equipment. It would serve as an alternative to carrier-owned Wi-Fi hotspots. Currently, there are a number of variants of LTE operation in the unlicensed band, namely LTE-U, License Assisted Access (LAA), MulteFire, sXGP and CBRS.

<span class="mw-page-title-main">Wi-Fi 6</span> Wireless networking standard

Wi-Fi 6, or IEEE 802.11ax, is an IEEE standard from the Wi-Fi Alliance, for wireless networks (WLANs). It operates in the 2.4 GHz and 5 GHz bands, with an extended version, Wi-Fi 6E, that adds the 6 GHz band. It is an upgrade from Wi-Fi 5 (802.11ac), with improvements for better performance in crowded places. Wi-Fi 6 covers frequencies in license-exempt bands between 1 and 7.125 GHz, including the commonly used 2.4 GHz and 5 GHz, as well as the broader 6 GHz band.

White Space Internet uses a part of the radio spectrum known as white spaces. The frequency range is created when there are gaps between the coverage areas of television channels. The spaces can provide broadband internet access that is similar to that of 4G mobile.

Citizens Broadband Radio Service (CBRS) is a 150 MHz wide broadcast band of the 3.5 GHz band in the United States. In 2017, the US Federal Communications Commission (FCC) completed a process which began in 2012 to establish rules for commercial use of this band, while reserving parts of the band for the US Federal Government to limit interference with US Navy radar systems and aircraft communications.

References

  1. 1 2 Ray, Bill (April 22, 2011). "How to build a national cellular wireless network for £50m". The Register. Retrieved February 4, 2012.
  2. "IEEE 802 LAN/MAN Standards Committee 802.22 WG on WRANs (Wireless Regional Area Networks)". IEEE . Retrieved January 18, 2009.
  3. Carl Stevenson; G. Chouinard; Zhongding Lei; Wendong Hu; S. Shellhammer; W. Caldwell (January 2009). "IEEE 802.22: The First Cognitive Radio Wireless Regional Area Networks (WRANs) Standard". IEEE Communications Magazine . 47 (1). US: IEEE: 130–138. doi:10.1109/MCOM.2009.4752688. S2CID   6597913.
  4. Seabold, Dave (September 2, 2011). "UK Leads Europe in White Space Technology". EU Design Studio. Retrieved February 4, 2012.
  5. O'Brien, Terrence (December 22, 2011). "FCC approves first white space device and database for Wilmington, NC". engadget. Retrieved February 4, 2012.
  6. Musa, Sam. "TV White Space for Rural Communities". Academia.edu. Dr. Sam Musa.
  7. "El Enacom probará tecnología White Spaces en Mendoza con equipos de Microsoft" . Retrieved July 17, 2017.
  8. "Consultation on a Policy and Technical Framework for the Use of Non-Broadcasting Applications in the Television Broadcasting Bands Below 698 MHz". Industry Canada. August 26, 2011. Retrieved January 20, 2012.
  9. "Solar power, white spaces bring 16Mbps broadband to towns without electricity".
  10. Mutenda, Memory (July 3, 2014). "27 schools get internet connectivity". Informante. Retrieved July 6, 2014.
  11. Ageng'o, Carlos (January 15, 2014). "Mydigitalbridge Foundation, Microsoft Pilot Whitespaces Project Brings Broadband to Namibia". Techweez. Retrieved July 6, 2014.
  12. "TV White Space Deployment in PH the Largest in Asia | DICT" . Retrieved September 13, 2022.
  13. "About the SWSPG" (PDF). Retrieved October 27, 2023.
  14. "PageNotFound".
  15. "The Cape Town TV White Spaces Trial". TENET. Retrieved March 1, 2017.
  16. Masonta, Moshe T.; Kola, L. M.; Lysko, Albert A.; Pieterse, L.; Velempini, M. (September 2015). "Network performance analysis of the Limpopo TV white space (TVWS) trial network". CSIR. Retrieved May 29, 2020.
  17. "Regulations On The Use Of Television White Spaces 2018". ICASA. Retrieved May 29, 2020.
  18. "Temporary radio frequency spectrum issued to qualifying applicants in an effort to deal with COVID-19 communication challenges". ICASA. Retrieved May 29, 2020.
  19. "Licence-exempt devices". October 25, 2019.
  20. "Spectrum management". July 28, 2020.
  21. "Adaptrum's White Space Wi-Fi Tests Positively in Cambridge". July 5, 2011. Retrieved July 5, 2011.
  22. "Project Belgrade - Microsoft Research". Microsoft Research. Retrieved February 17, 2018.
  23. "FCC Rules and Regulations Pt2" (PDF).
  24. Eric Bangeman. The White Spaces Coalition's plans for fast wireless broadband: Fast broadband without fiber... or even wires", Ars Technica, 2007-4-17. Retrieved on June 12, 2007.
  25. Eggerton, John (October 5, 2009). "Broadcasters Tackle Spectrum-Sharing Debate". Broadcasting & Cable . Retrieved October 9, 2009.
  26. Patrick S. Ryan, Wireless Communications and Computing at a Crossroads: New Paradigms and Their Impact on Theories Governing the Public's Right to Spectrum Access. Journal on Telecommunications & High Technology Law, Vol. 3, No. 2, p. 239, 2005
  27. Eric Bangeman (April 17, 2007). "The White Spaces Coalition's plans for fast wireless broadband: The technology". Ars Technica. Retrieved May 23, 2013.
  28. "Wireless Innovation Alliance". Web site. Retrieved May 23, 2013.
  29. "WhiteSpace Alliance Formed to Deliver Affordable, High-Speed Broadband Internet Access to 3.5 Billion Households". News release. Retrieved May 23, 2013.
  30. Free the Airwaves, archived from the original on February 7, 2009
  31. Moriarity, Caitlin (August 18, 2008). "Google to FCC: Free The Airwaves". CRN.
  32. Reardon, Marguerite (August 18, 2008). "Debate rages over free wireless spectrum". Wireless. CNET. Retrieved May 23, 2013.
  33. Initial Evaluation of the Performance of Prototype TV Band White Space Devices , 2007-7-31. Retrieved on August 2, 2007.
  34. Microsoft: FCC tested broken white spaces device, neglected backup unit , 2007-8-15. Retrieved on August 15, 2007.
  35. Evaluation of the Performance of Prototype TV Band White Space Devices, Phase II , 2008-10-15. Retrieved on October 24, 2008.
  36. Harold Feld And now the moment we've all been waiting for WHITE SPACES", WetMachine.com, November 4, 2008. Retrieved on November 5, 2008
  37. Second Report and Order
  38. FCC Second Memorandum and Order, September 23, 2010
  39. "Federal Register :: Request Access".
  40. Petition for Review
  41. "REPORT AND ORDER AND FURTHER NOTICE OF PROPOSED RULEMAKING" (PDF). Retrieved October 27, 2023.
  42. "Broadcasters withdraw "white spaces" challenge". Reuters. May 3, 2012.
  43. Anderson, Nate (August 27, 2009). "WiFi on steroids? First "WhiteFi" prototypes hit testing stage". ArsTechnica. Retrieved November 11, 2014.
  44. Shields, Todd (September 13, 2010). "Microsoft Tests Super-Size Wireless Hot Spot in TV Gaps". Bloomberg. Retrieved November 11, 2014.
  45. Eggerton, John (February 24, 2010). "Wilmington Tests WiFi in White Spaces". Broadcasting & Cable . Retrieved February 25, 2010.
  46. "California's Yurok Tribe Takes Advantage of White Spaces Technology". Radio Resource Magazine. June 14, 2011. Retrieved May 23, 2013.
  47. "Nation's first campus 'Super Wi-Fi' network launches at West Virginia University". WVUToday. June 9, 2013. Retrieved July 9, 2013.
  48. "Port of Pittsburgh Evaluates White Space Spectrum Use for Enhancing Inland Waterway Safety and Utility".