Radio or wireless systems use radio frequencies or spectrum as the medium for transmitting information from one location to the other. Traditionally each user is given dedicated frequencies on a long term basis. For example, broadcast stations and public safety organizations have dedicated full-time frequencies. Similarly, cellular carriers also have dedicated full-time frequencies that they assign to individual users for the duration of a call.
Radio is the technology of signalling or communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connected to an antenna which radiates the waves, and received by a radio receiver connected to another antenna. Radio is very widely used in modern technology, in radio communication, radar, radio navigation, remote control, remote sensing and other applications. In radio communication, used in radio and television broadcasting, cell phones, two-way radios, wireless networking and satellite communication among numerous other uses, radio waves are used to carry information across space from a transmitter to a receiver, by modulating the radio signal in the transmitter. In radar, used to locate and track objects like aircraft, ships, spacecraft and missiles, a beam of radio waves emitted by a radar transmitter reflects off the target object, and the reflected waves reveal the object's location. In radio navigation systems such as GPS and VOR, a mobile receiver receives radio signals from navigational radio beacons whose position is known, and by precisely measuring the arrival time of the radio waves the receiver can calculate its position on Earth. In wireless remote control devices like drones, garage door openers, and keyless entry systems, radio signals transmitted from a controller device control the actions of a remote device.
Wireless communication, or sometimes simply wireless, is the transfer of information or power between two or more points that are not connected by an electrical conductor. The most common wireless technologies use radio waves. With radio waves distances can be short, such as a few meters for Bluetooth or as far as millions of kilometers for deep-space radio communications. It encompasses various types of fixed, mobile, and portable applications, including two-way radios, cellular telephones, personal digital assistants (PDAs), and wireless networking. Other examples of applications of radio wireless technology include GPS units, garage door openers, wireless computer mice, keyboards and headsets, headphones, radio receivers, satellite television, broadcast television and cordless telephones. Somewhat less common methods of achieving wireless communications include the use of other electromagnetic wireless technologies, such as light, magnetic, or electric fields or the use of sound.
A spectrum is a condition that is not limited to a specific set of values but can vary, without steps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism. As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum.
Interruptible spectrum is a concept for sharing spectrum among multiple prioritized users. It is based on interruptible concepts in other public utilities, mainly the electric power industry, where the commodity is made available at a low price provided that it can be preempted under stated circumstances by other users. The application of this concept to spectrum was first proposed in a conference paper by Federal Communications Commission(FCC) staffers Mark Bykowsky and Michael Marcus in 2002.
The Federal Communications Commission (FCC) is an independent agency of the United States government created by statute to regulate interstate communications by radio, television, wire, satellite, and cable. The FCC serves the public in the areas of broadband access, fair competition, radio frequency use, media responsibility, public safety, and homeland security.
In 2003, FCC proposed in Docket 03-108 to use interruptible spectrum for sharing public safety spectrum that has low average use but high peak use with commercial users subject to immediate interruption. In 2004 it decided to implement this proposal by in the narrow context of public safety users sharing with only other local and state government users.
In 2006, FCC proposed in Docket 06-229 that then could be used for sharing public safety spectrum with commercial users in former UHF-TV spectrum after the transition to digital television. In its August 2007 Docket 06-229 decision, FCC voted to implement the 700MHz Public/Private Partnership, an implementation of interruptible spectrum concepts in the 700MHz band subject to a minimum bid of $1.4 billion in the band auction. It later designated the Public Safety Spectrum Trust to represent public safety interests in this band and negotiate with the auction winner for a mutual agreement on band use and public and private access to it.
Digital television (DTV) is the transmission of television signals, including the sound channel, using digital encoding, in contrast to the earlier television technology, analog television, in which the video and audio are carried by analog signals. It is an innovative advance that represents the first significant evolution in television technology since color television in the 1950s. Digital TV transmits in a new image format called HDTV, with greater resolution than analog TV, in a wide screen aspect ratio similar to recent movies in contrast to the narrower screen of analog TV. It makes more economical use of scarce radio spectrum space; it can transmit multiple channels, up to 7, in the same bandwidth occupied by a single channel of analog television, and provides many new features that analog television cannot. A transition from analog to digital broadcasting began around 2006 in some countries, and many industrial countries have now completed the changeover, while other countries are in various stages of adaptation. Different digital television broadcasting standards have been adopted in different parts of the world; below are the more widely used standards:
The Public Safety Spectrum Trust Corporation (PSST) was a non-profit organization which represents the radio spectrum needs of police, fire and ambulance agencies in the United States.
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Related Research Articles
The industrial, scientific and medical (ISM) radio bands are radio bands reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications.
Examples of applications in these bands include radio-frequency process 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 were limited to certain bands of frequencies. In general, communications equipment operating in these bands must tolerate any interference generated by ISM applications, and users have no regulatory protection from ISM device operation.
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, and numerous other applications.
The Family Radio Service (FRS) is an improved walkie-talkie radio system authorized in the United States since 1996. This personal radio service uses channelized frequencies around 462 and 467 MHz in the ultra high frequency (UHF) band. It does not suffer the interference effects found on citizens' band (CB) at 27 MHz, or the 49 MHz band also used by cordless telephones, toys, and baby monitors. FRS uses frequency modulation (FM) instead of amplitude modulation (AM). Since the UHF band has different radio propagation characteristics, short-range use of FRS may be more predictable than the more powerful license-free radios operating in the HF CB band.
The business band is the name used by US radio users who utilize and scanner hobbyists who listen to the Federal Communications Commission (FCC) Industrial/Business pool frequencies. The regulations listing frequencies in this pool are contained in Subpart C of Part 90, Title 47 of the CFR.
A broadcast license is a type of spectrum license granting the licensee permission to use a portion of the radio frequency spectrum in a given geographical area for broadcasting purposes. The licenses generally include restrictions, which vary from band to band.
High-speed multimedia radio (HSMM) is the implementation of wireless data networks over amateur radio frequencies using commercial off-the-shelf (COTS) hardware such as 802.11 access points. Only licensed amateur radio operators may use amplifiers and specialized antennas to increase the power and coverage of the 802.11 signal.
A spectrum auction is a process whereby a government uses an auction system to sell the rights (licenses) to transmit signals over specific bands of the electromagnetic spectrum and to assign scarce spectrum resources. Depending on the specific auction format used, a spectrum auction can last from a single day to several months from the opening bid to the final winning bid. With a well-designed auction, resources are allocated efficiently to the parties that value them the most, the government securing revenue in the process. Spectrum auctions are a step toward market-based spectrum management and privatization of public airwaves, and are a way for governments to allocate scarce resources.
Alternatives to auctions include administrative licensing, such as the comparative hearings conducted historically, or lotteries.
Spectrum management is the process of regulating the use of radio frequencies to promote efficient use and gain a net social benefit. The term radio spectrum typically refers to the full frequency range from 3 kHz to 300 GHz that may be used for wireless communication. Increasing demand for services such as mobile telephones and many others has required changes in the philosophy of spectrum management. Demand for wireless broadband has soared due to technological innovation, such as 3G and 4G mobile services, and the rapid expansion of wireless internet services.
Bandwidth allocation is the process of assigning radio frequencies to different applications. The radio spectrum is a finite resource, which means there is great need for an effective allocation process. In the United States, the Federal Communications Commission or FCC has the responsibility of allocating discrete portions of the spectrum, or bands, to various industries. The FCC did this recently, when it shifted the location of television broadcasting on the spectrum in order to open up more space for mobile data. Different bands of spectrum are able to transmit more data than others, and some bands of the spectrum transmit a clearer signal than others. Bands that are particularly fast or that have long range are of critical importance for companies that intend to operate a business involving wireless communications.
The United States 700 MHz FCC wireless spectrum auction, officially known as Auction 73, was started by the Federal Communications Commission (FCC) on January 24, 2008 for the rights to operate the 700 MHz radio frequency band in the United States. The details of process were the subject of debate among several telecommunications companies, including Verizon Wireless, AT&T Mobility, as well as the Internet company Google. Much of the debate swirled around the "open access" requirements set down by the Second Report and Order released by the FCC determining the process and rules for the auction. All bidding was required by law to commence by January 28.
Automated Maritime Telecommunications System (AMTS) is a commercial mobile radio service used within the United States. It operates within the VHF frequency range, just above the North American Band III television range, and offers both voice and data communications to maritime customers. The system is operated by a network of private carriers across the country, with coverage primarily including coastal and inland waterways.
The digital dividend refers to the radio spectrum which is released in the process of digital television transition. When television broadcasters switch from analog TV to digital-only platforms, part of the electromagnetic spectrum that has been used for broadcasting will be freed-up because digital television needs less spectrum than analog television. One reason is that new digital video compression technology can transmit numerous digital subchannels using the same amount of spectrum used to transmit one analog TV channel. However, the primary reason is that digital transmissions require much less of a guard band on either side, since they are not nearly as prone to RF interference from adjacent channels. Because of this, there is no longer any need to leave empty channels to protect stations from each other, in turn allowing stations to be repacked into fewer channels, leaving more contiguous spectrum to be allocated for other wireless services.
The Pan-American television frequencies are different for terrestrial and cable television systems. Terrestrial television channels are divided into two bands: the VHF band which comprises channels 2 through 13 and occupies frequencies between 54 through 216 MHz, and the UHF band, which comprises channels 14 through 83 and occupies frequencies between 470 and 890 MHz. These bands are different enough in frequency that they often require separate antennas to receive, and separate tuning controls on the television set. The VHF band is further divided into two frequency ranges: VHF low band between 54 and 88 MHz, containing channels 2 through 6, and VHF high band between 174 and 216 MHz, containing channels 7 through 13. The wide spacing between these frequency bands is responsible for the complicated design of rooftop TV antennas. The UHF band has higher noise and greater attenuation, so higher gain antennas are often required for UHF.
The Asia-Pacific Telecommunity (APT) band plan is a type of segmentation of the 698–806 MHz band formalized by the APT in 2008–2010 and specially configured for the deployment of mobile broadband technologies. This segmentation exists in two variants, FDD and TDD, that have been standardized by the 3rd Generation Partnership Project (3GPP) and recommended by the International Telecommunications Union (ITU) as segmentations A5 and A6, respectively. The APT band plan has been designed to enable the most efficient use of available spectrum. Therefore, this plan divides the band into contiguous blocks of frequencies that are as large as possible taking account of the need to avoid interference with services in other frequency bands. As the result, the TDD option includes 100 MHz of continuous spectrum, while the FDD option comprises two large blocks, one of 45 MHz for uplink transmission in the lower part of the band and the other also of 45 MHz for downlink transmission in the upper part. As defined in the standard, both FDD and TDD schemes for the 700 MHz band include guard bands of 5 MHz and 3 MHz at their lower and upper edges, respectively. The FDD version also includes a center gap of 10 MHz. The guardbands serve the purpose of mitigating interference with adjacent bands while the FDD center gap is required to avoid interference between uplink and downlink transmissions. The two arrangements are shown graphically in figures 1 and 2.
A Private Shared Wireless Network (PSWN) is a wide area wireless radio telecommunications network developed and provided by MetroConnect specifically for the use of public safety, utilities, machine to machine, and business communications. Its broad area coverage allows for a greater signal range and a lower cost of implementation. Public safety agencies and businesses utilize a Private Shared Wireless Network to send and receive data, communicate, and receive diagnostics information on their fixed equipment, vehicles and/or employees.
Middle 20th century frequency allocation assigned much of the radio spectrum to broadcasting. Late in the century, other uses arose and in United States, spectrum reallocation mostly refers to reassigning frequency bands to uses such as wireless broadband, trunking, or point-to-point microwave services.
Citizens Broadband Radio Service (CBRS) is a 150 MHz wide broadcast band of the 3.5 GHz band. Some of this spectrum will continue to be used by the United States government for radar systems, but will be available for others where not needed by the Navy. In 2017, the Federal Communications Commission (FCC) completed a process begun in 2012 to establish rules for commercial use of this band. Wireless carriers using CBRS might be able to deploy 5G mobile networks without having to acquire spectrum licenses.
