Handheld wireless radios such as this Maritime VHF radio transceiver use electromagnetic waves to implement a form of wireless communications technology.
Wireless operations permits services, such as long range communications, that are impossible or impractical to implement with the use of wires. The term is commonly used in the telecommunications industry to refer to telecommunications systems (e.g. radio transmitters and receivers, remote controls, computer networks, network terminals, etc.) which use some form of energy (e.g. radio frequency (RF), infrared light, laser light, visible light, acoustic energy, etc.) to transfer information without the use of wires. Information is transferred in this manner over both short and long distances. Wireless technologies have become increasingly popular in our everyday business and personal lives. Cell phones offer users a freedom of movement unbelievable just over 10 years ago. Personal Digital Assistants (PDA) allow individuals to access calendars, e-mail, address and phone numbers lists, and the Internet. Global positioning system (GPS) that the location of the device anywhere in the world. Wireless technologies promise to offer even more features and functions in the next few years. An increasing number of government agencies, business, and home users are using wireless technologies in their environments.
Overview of Wireless Technology
Wireless technologies are enabling one or more devices to communicate without physical connections – without requiring network cabling. Wireless technology aims to provide users access to information anywhere – it allows mobility. Wireless technologies use radio transmissions for transmitting data, whereas wired technologies use cables.
Wireless technologies range from complex systems, such as:
* Cell phones
Simple device such as
* Wireless headphone
Infrared devices such as
* Remote Controls
* Cordless computer keyboards
In this article, a brief overview of critical elements of wireless is presented: wireless networks, wireless devices, wireless standards,
Wireless networks are categorized into three groups based on their coverage range:
Ø WWAN: WWAN representing wireless wide area networks includes wide coverage area technologies such as 2G cellular, Cellular Digital Packet Data (CDPD). Global System for Mobile Communications (GSM)
Ø WLAN: WLAN representing wireless local area networks, WLAN connect computers and other components to the network using an access point device. It communicates with devices with wireless network adaptors. It's coverage areas of 300 feet access point cells linked together within a building or between buildings
Ø WPAN: WPAN representing wireless personal area network technologies such as Bluetooth and infrared.
All of these technologies are "join less" –receive and transmit information using electromagnetic (EM) waves. Wireless technologies use wavelengths ranging from the radio frequency (RF) The frequencies in the RF band cover a significant portion of the EM radiation spectrum, extending from 9 kilohertz (kHz), the lowest allocated wireless communications frequency, to thousands of gigahertz (GHz).
A wide range of devices use wireless technologies, with handheld devices being the most widespread form today. The most commonly used wireless handheld devices such as
* Text messaging
* Smart phone
Personal Digital Assistants
PDAs are data organizers that are small enough to fit into a shirt pocket or a purse. PDAs offer applications
· Office productivity
* Database application
* Address book, scheduler user allows synchronizing data between PDAs and personal computer.
Mobile wireless telephones or cell phones have shortwave analog or digital transmission that allows users to establish wireless connections to nearby transmitters. As with WLANs, the transmitter's span of coverage is called a cell. As the cell phone user moves from one cell to the next, the telephone connection is effectively passed from one local cell transmitter to the next. Today's cell phone is rapidly evolving to include integration with PDAs, thus providing users with increased wireless e-mail and Internet access. Mobile phones with information processing and data networking capabilities are called Smart Phones.
Security administrators may also encounter one-way and two-way text messaging devices. These devices operate on a proprietary networking standard that disseminates e-mail to remote devices by accessing the corporate network. Text-messaging technology is designed to monitor a user's inbox for new e-mail and relay the mail to the user's wireless handheld via the Internet and wireless network.
Wireless encompasses a variety of standards. The principal advantages of standards are to encourage mass production and to allow products from multiple vendors to communicate.
* AMPS (Advanced Mobile Phone Systems)
* FDMA (Frequency Division Multiple Access)
* TDMA (Time Division Multiple Access)
* CDMA (Code Division Multiple Access)
* GSM (Global System for Mobile)
Many handheld devices (e.g., PDAs and cell phones) have followed the Wireless Application Protocol (WAP) standard, which provides for secure access to e-mail and the Internet.
IEEE 802.11 Standards
The following IEEE standards and task groups exist within the IEEE 802.11 working group:
· IEEE 802.11 - The original 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and IR standard (1999)
* IEEE 802.11a - 54 Mbit/s, 5 GHzstandard (1999, shipping products in 2001)
* IEEE 802.11b - Enhancements to 802.11 to support 5.5 and 11 Mbit/s (1999)
* IEEE 802.11c - Bridge operation procedures; included in the IEEE 802.1D standard (2001)
* IEEE 802.11d - International (country-to -country) roaming extensions (2001)
* IEEE 802.11e - Enhancements: QoS, including packet bursting (2005)
* IEEE 802.11F - Inter-Access Point Protocol (2003)
* IEEE 802.11g - 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003)
* IEEE 802.11i-Enhanced security (2004)
* IEEE 802.11j - Extensions for Japan (2004)
* IEEE 802.11k - Radio resource measurement enhancements
* IEEE 8 0 2 .11l - (reserved, typologically unsound) IEEE 802.11e - Enhancements:
* IEEE 802.11m - Maintenance of the standard; odds and ends.
* IEEE 802.11n - Higher throughput improvements
* IEEE 802.11o - ( reserved, typologically unsound)
* IEEE 802.11p - WAVE - Wireless Access for the Vehicular Environment.
* IEEE 802.11r - Fast roaming
* IEEE 802.11s-ESS Mesh Networking
* IEEE 802.11T - Wireless Performance Prediction (WPP) - test methods and metrics
* IEEE 802.11u - Interworking with non-802 networks (e.g., cellular)
* IEEE 802.11v - Wireless network management
The Photophone was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880. Bell believed the photophone was his most important invention. The device allowed for the transmission of sound on a beam of light. On June 3, 1880, Bell transmitted the world's first wireless telephone message on his newly invented form of telecommunication, the far advanced precursor to fiber-optic communications.
Of the eighteen patents granted in Bell's name alone, and the twelve he shared with his collaborators, four were for the photo phone, which Bell referred to as his greatest achievement, writing that the photo phone was "the greatest invention ever made, greater than the telephone". The master patent for the photo phone, was issued in December 1880, many decades before its principles could be applied to practical applications.
Design and history
The photo phone used crystalline selenium cells at the electricity.
World's first wireless telephone communication - June 1880
In their Ω. It was the earliest fiber-optics system recorded.
The term "wireless" came into public use to refer to a radio receiver or Nobel Prize for Physics for their contribution to wireless telegraphy.
21st century development
Internet connections: no radio transmitters need be involved at any point in the process.
Digital audio broadcasting
Digital audio broadcasting (DAB): appears to be set to grow in importance relative to FM radio for airborne broadcasts in several countries.
The electromagnetic spectrum
Light, colors, AM and FM radio and electronic devices make use of the electromagnetic spectrum. In the US the frequencies that are available for use for communication are treated as a public resource and are regulated by the airplane. Wireless communication spans the spectrum from 9kHz to 300GHz.
Wireless technology may supplement or replace hard wired implementations in security systems for homes or office buildings.
Cellular telephony (phones and modems)
A mobile phone or mobile (cellphone and headphone) is an GPS.
The bottom of the economic pyramid.
History of mobile phones
Radio telephony (0G)
In 1908, George Sweigert of Euclid, Ohio on June 10, 1969.
In 1945, the zero generation (0G) of mobile telephones was introduced. Like other technologies of the time, it involved a single, powerful base station covering a wide area, and each telephone would effectively monopolize a channel over that whole area while in use.
Analog cellular telephony (1G)
The first commercial citywide cellular network was launched in Japan by NTT in 1979. Fully automatic cellular networks were first introduced in the early to mid-1980s (the FCC in the United States. The cell sites would be set up such that cells partially overlapped. In a cellular system, a signal between a base station and a terminal only need be strong enough to reach between the two, so the same channel can be used simultaneously for separate conversations in different cells.
Cellular systems required several leaps of technology, including handover, which allowed a conversation to continue as a mobile phone traveled from cell to cell. This system included variable transmission power in both the base stations and the telephones, which allowed range and cell size to vary. As the system expanded and neared capacity, the ability to reduce transmission power allowed new cells to be added, resulting in more, smaller cells and thus more capacity. The evidence of this growth can still be seen in the many older, tall cell site towers with no antennae on the upper parts of their towers. These sites originally created large cells, and so had their antennae mounted atop high towers; the towers were designed so that as the system expanded—and cell sizes shrank—the antennae could be lowered on their original masts to reduce range.
Digital mobile communication (2G)
The first "modern" network technology on digital Telecom Finland who ran a 1G NMT network.
The first data services appeared on mobile phones starting with person-to-person SMS text messaging in Finland in 1993. First trial payments using a mobile phone to pay for a Coca Cola vending machine were set in Finland in 1998. The first commercial payments were mobile parking trialled in Sweden but first commercially launched in Norway in 1999. The first commercial payment system to mimic banks and credit cards was launched in the Philippines in 1999 simultaneously by mobile operators Globe and Smart. The first content sold to mobile phones was the ringing tone, first launched in 1998 in Finland. The first full internet service on mobile phones was i-Mode introduced by NTT DoCoMo in Japan in 1999.
Wideband mobile communication (3G)
In 2001 the first commercial launch of WCDMA standard.
Until the early 1990s, following introduction of the miniaturization of digital components and the development of more sophisticated batteries, mobile phones have become smaller and lighter.
Mobile phones are used for a variety of purposes, including keeping in touch with family members, conducting business, and having access to a telephone in the event of an emergency. Some individuals keep multiple cell phones in some cases for legitimate reasons such as having one phone for business and another for personal use, though a second cell phone may also be used to covertly conduct an affair or illicit business transaction. Child predators are able to take advantage of cell phones to secretly communicate with children without the knowledge of their parents or teachers, which has raised concerns.
Organizations that aid victims of domestic violence offer a secret cell phone to potential victims. These devices are often old phones that are donated and refurbished to meet the victim's emergency needs. The victim can then have the phone handy when necessary and without the abuser knowing.
A study by Motorola found that one in ten cell phone subscribers have a second phone that often is kept secret from other family members. These phones are used to engage in activities including extramarital affairs or clandestine business dealings.
There are several categories of mobile phones, from basic phones to feature phones such as music phones and camera phones. There are also smartphones; the first smartphone was the iPhone.
Mobile phones often have features beyond sending touchscreen.
Typical mobile phone SIM card
In addition to the battery, postage stamp, the SIM Card is usually placed underneath the battery in the rear of the unit, and stores the phone's configuration data, and information about the phone itself, such as which calling plan the subscriber is using. When the subscriber removes the SIM Card, it can be re-inserted into another phone that is configured to accept the SIM card and used as normal.
Each SIM Card is activated by use of a unique numerical identifier; once activated, the identifier is locked down and the card is permanently locked in to the activating network. For this reason, most retailers refuse to accept the return of an activated SIM Card.
Those cell phones that do not use a SIM Card have the data programmed in to their memory. This data is accessed by using a special digit sequence to access the "NAM" as in "Name" or number programming menu. From here, one can add information such as a new number for your phone, new Service Provider numbers, new emergency numbers, change their Authentication Key or A-Key code, and update their Preferred Roaming List or PRL. However, to prevent someone from accidentally disabling their phone or removing it from the network, the Service Provider puts a lock on this data called a Master Subsidiary Lock or MSL.
The MSL applies to the SIM only so once the contract has been completed the MSL still applies to the SIM. The phone however, is also initially locked by the manufacturer into the Service Providers MSL. This lock may be disabled so that the phone can use other Service Providers SIM cards. Most phones purchased outside the US are unlocked phones because there are numerous Service Providers in close proximity to one another or have overlapping coverage. The cost to unlock a phone varies but is usually very cheap and is sometimes provided by independent phone vendors.
The mobile phone became a mass media channel in 1998 when the first ringtones were sold to mobile phones by Radiolinja in Finland. Soon other media content appeared such as news, videogames, jokes, horoscopes, TV content and advertising. In 2006 the total value of mobile phone paid media content exceeded internet paid media content and was worth 31 Billion dollars. The value of music on phones was worth 9.3 Billion dollars in 2007 and gaming was worth over 5 billion dollars in 2007.
The mobile phone is often called the Fourth Screen or Third Screen .It is also called the Seventh of the Mass Media. Most early content for mobile tended to be copies of legacy media, such as the banner advertisement or the TV news highlight video clip. Recently unique content for mobile has been emerging, from the ringing tones and ring back tones in music to "mobisodes," video content that has been produced exclusively for mobile phones.
The advent of media on the mobile phone has also produced the opportunity to identify and track Alpha Users or Hubs, the most influential members of any social community. AMF Ventures measured in 2007 the relative accuracy of three mass media, and found that audience measures on mobile were nine times more accurate than on the internet and 90 times more accurate than on TV.
Comparison to similar systems
A type of telephone permanently mounted in a vehicle, these often have more powerful transmitters, an external antenna and loudspeaker for hands free use. They usually connect to the same networks as regular mobile phones.
Cordless telephone (portable phone)
Cordless phones are telephones which use one or more radio handsets in place of a wired handset. The handsets connect wirelessly to a base station, which in turn connects to a conventional land line for calling. Unlike mobile phones, cordless phones use private base stations, and which are not shared.
Professional Mobile Radio
Advanced professional mobile radio systems can be very similar to mobile phone systems. Notably, the TETRA, the European digital PMR standard, to implement public mobile networks.
This is a term which covers radios which could connect into the telephone network. These phones may not be mobile; for example, they may require a PSTN phone call.
This type of phone communicates directly with an artificial satellite, which in turn relays calls to a base station or another satellite phone. A single satellite can provide coverage to a much greater area than terrestrial base stations. Since satellite phones are costly, their use is typically limited to people in remote areas where no mobile phone coverage exists, such as mountain climbers, mariners in the open sea, and news reporters at disaster sites.
This type of phone delivers calls over GSM networks. Several vendors have developed standalone Wi-Fi phones. Additionally, some cellular mobile phones include the ability to place VoIP calls over cellular high speed data networks and/or wireless internet.
Effect on Health
Mobile phone radiation and health
Because mobile phones emit precautionary principle be observed, recommending that use and proximity to the head be minimized, especially by children.
People specifically fear the consequences that electromagnetic radiation might have on children. In order to avoid harm, a variety of initiatives have been created. For example, one initiative states that "Mobile towers be located further away from child-care centers or schools where there are larger concentrations of children."
Restriction on usage
Some schools limit or restrict the use of mobile phones. Schools set restrictions on the use of mobile phones because of the use of cell phones for cheating on tests, harassing other people, causing threats to the schools security, and facilitating gossip and other social activity in school. Many mobile phones are banned in school locker room facilities, public restrooms and swimming baths.
Many mobile phones, along with other electronic products, have high quality turn a blind eye to its original source or do not adequately trace the source.
Wi-Fi (pronounced IEEE 802.11 standards. Because of the close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for IEEE 802.11 technology.
The Wi-Fi Alliance is a global, non-profit association of companies that promotes WLAN technology and certifies products if they conform to certain standards of interoperability. Not every IEEE 802.11-compliant device is submitted for certification to the Wi-Fi Alliance, sometimes because of costs associated with the certification process and the lack of the Wi-Fi logo does not imply a device is incompatible with Wi-Fi devices.
Today, an IEEE 802.11 device is installed in many laptop or palm-sized computers.
A roof mounted Wi-Fi antenna
A Wi-Fi enabled device such as a wireless mesh networks, for example, in London.
A municipal wireless antenna in Minneapolis
In the early 2000s, many cities around the world announced plans for a city wide Wi-Fi network. This proved to be much more difficult than their promoters initially envisioned with the result that most of these projects were either canceled or placed on indefinite hold. A few were successful, for example in 2005, United States to offer city wide free Wi-Fi.Few of the Municipal Wi-Fi firms have now entered into the field of Smart grid networks.
The first Wi-Fi network in the world was actually a campus based network. Carnegie Mellon University went live with the first-ever Wi-Fi network in 1994.
Direct computer-to-computer communications
Wi-Fi also allows communications directly from one computer to another without the involvement of an access point. This is called the ad-hoc mode of Wi-Fi transmission. This personal computers. However the Wi-Fi Alliance is hoping to promoting this method for quick file transfers and media sharing through a new discovery and easy security setup which they are calling Wi-Fi Direct.
Wi-Fi technology is based on IEEE 802.11 standards. The backward compatibility, and to promote wireless local area network technology. Today the Wi-Fi Alliance consists of more than 300 companies from around the world. Manufacturers with membership in the Wi-Fi Alliance, whose products pass the certification process, are permitted to mark those products with the Wi-Fi logo.
Specifically, the certification process requires conformance to the IEEE 802.11 radio standards, the EAP authentication standard. Certification may optionally include tests of IEEE 802.11 draft standards, interaction with cellular phone technology in converged devices, and features relating to security set-up, multimedia, and power saving.
The Wi-Fi name
The term Wi-Fi suggests Wireless Fidelity, compared with the long-established audio recording term High Fidelity or Hi-Fi. Wireless Fidelity has often been used in an informal way, even by the Wi-Fi Alliance itself, but officially the term Wi-Fi does not mean anything.
The Wi-Fi Alliance initially stated that Wi-Fi "actually stood for" Wireless Fidelity, as with the White papers still held on their website say: "...a promising market for wireless fidelity (Wi-Fi) network equipment.
The Alliance has since downplayed the connection to Hi-Fi. Their official position now is that it is merely a brand name that stands for nothing in particular, and they now discourage the use of the term Wireless Fidelity.
Advantages and challenges
A keychain size Wi-Fi detector.
Wi-Fi allows local area networks (LANs) to be deployed without wires for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.
Wireless network adapters are now built into most laptops. The price of chipsets for Wi-Fi continues to drop, making it an economical networking option included in even more devices. Wi-Fi has become widespread in corporate infrastructures.
Different competitive brands of access points and client network interfaces are inter-operable at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are backwards compatible. Wi-Fi is a global set of standards. Unlike mobile phones, any standard Wi-Fi device will work anywhere in the world.
Wi-Fi is widely available in more than 220,000 public hotspots and tens of millions of homes and corporate and university campuses worldwide. The current version of passphrase is used. New protocols for Quality of Servicemake Wi-Fi more suitable for latency-sensitive applications, and powers saving mechanism improve battery operation.
Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the U.S. for the 2.4 GHz band. Japan has one more on top of that. Europe, as of 2007, was essentially homogeneous in this respect. A very confusing aspect is the fact that a Wi-Fi signal actually occupies five channels in the 2.4 GHz band resulting in only three non-overlapped channels in the U.S.: 1, 6, 11, and three or four in Europe: 1, 5, 9, 13 can be used if all the equipment on a specific area can be guaranteed not to use 802.11b at all, even as fallback or beacon. dBm.
An Czech Republic.
OSBRiDGE 3GN - 802.11n Access Point and UMTS/GSM Gateway in one device.
USB wireless adapter
A data between connected wireless devices in addition to a (usually) single connected wired device, most often an Ethernet hub or switch, allowing wireless devices to communicate with other wired devices.
USB, Express Card, Card bus and PC Card. Most new laptop computers are equipped with internal adapters. Internal cards are generally more difficult to install.
Wireless data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes.
Wireless range extenders or wireless repeaters can extend the range of an existing wireless network. Range extenders can be strategically placed to elongate a signal area or allow for the signal area to reach around barriers such as those created in L-shaped corridors. Wireless devices connected through repeaters will suffer from an increased latency for each hop. Additionally, a wireless device connected to any of the repeaters in the chain will have a throughput that is limited by the weakest link between the two nodes in the chain from which the connection originates to where the connection ends.
Distance records (using non-standard devices) include 382km (237 mi) in June 2007, held by Ermanno Pietrosemoli and EsLaRed of Venezuela, transferring about 3 MB of data between mountain tops of El Aguila and Platillon. The Swedish Space Agencytransferred data 310km, using 6 watt amplifiers to reach an overhead stratospheric balloon.
Embedded serial-to-Wi-Fi module
Wi-Fi availability in the home is on the increase.This extension of the Internet into the home space will increasingly be used for remote monitoring. Examples of remote monitoring include security systems and tele-medicine. In all these kinds of implementation, if the Wi-Fi provision is provided using a system running one of operating systems mentioned above, then it becomes unfeasible due to weight, power consumption and cost issues.
Increasingly in the last few years, embedded Wi-Fi modules have become available which come with a real-time operating system and provide a simple means of wireless enabling any device which has and communicates via a serial port. This allows simple monitoring devices – for example, a portable ECG monitor hooked up to a patient in their home – to be created. This Wi-Fi enabled device effectively becomes part of the Internet cloud and can communicate with any other node on the Internet. The data collected can hop via the home's Wi-Fi access point to anywhere on the Internet.
These Wi-Fi modules are designed so that designers need minimal Wi-Fi knowledge to wireless-enable their products.
The main issue with wireless network security is its simplified access to the network compared to traditional wired networks such as firewall. Most business networks protect sensitive data and systems by attempting to disallow external access. Thus being able to get wireless reception provides an attack vector, if encryption is not used or can be defeated.
Attackers who have gained access to a Wi-Fi network can use DNS spoofing attacks very effectively against any other user of the network, because they can see the DNS requests made, and often respond with a spoofed answer before the queried DNS server has a chance to reply.
A common but unproductive measure to deter unauthorized users is to suppress the AP's spoofing an authorized address.
Klein's attack to crack a WEP key with a 50% success rate using only 40,000 packets.
Wireless energy transfer
An artist's depiction of a solar satellite, which could send energy wirelessly to a space vessel or planetary surface.
Wireless energy transfer or wireless power transmission is the process that takes place in any system where wires. Wireless transmission is useful in cases where instantaneous or continuous energy transfer is needed, but interconnecting wires are inconvenient, hazardous, or impossible.
Wireless energy transfer is different from wireless transmission for the purpose of telecommunications, such as power received, becomes critical if it is too low to recover the signal successfully. With wireless energy transfer efficiency is the more important parameter.
The most common form of wireless power is carried out using lasers.
Microwave power transmission
The earliest work in the area of wireless transmission via radio waveswas performed by Nikola Tesla also investigated radio transmission and reception.
Japanese researcher Yagi antenna. While it did not prove to be particularly useful for power transmission, this beam antenna has been widely adopted throughout the broadcasting and wireless telecommunications industries due to its excellent performance characteristics.
Power transmission via radio waves can be made more directional, allowing longer distance power beaming, with shorter wavelengths of electromagnetic radiation, typically in the beaming of power to spacecraft leaving orbit has been considered.
Power beaming by microwaves has the difficulty that for most space applications the required aperture sizes are very large due to Thinned array curse, it is not possible to make a narrower beam by combining the beams of several smaller satellites.
For earthbound applications a large area 10km diameter receiving array allows large total power levels to be used while operating at the low power density suggested for human electromagnetic exposure safety. A human safe power density of 1mW/cm2 distributed across a 10km diameter area corresponds to 750 megawatts total power level. This is the power level found in many modern electric power plants.
With a laser beam centered on its panel of photovoltaic cells, a lightweight model plane makes the first flight of an aircraft powered by a laser beam inside a building at NASA Marshall Space Flight Center.
In the case of electromagnetic radiation closer to visible region of spectrumcan be transmitted by converting electricity into a solar cell receiver. This mechanism is generally known as "Power Beaming" because the Power is beamed at a receiver that can convert it to usable electrical energy.
The Bluetooth standard describes how mobile phones, computers, and PDAs should interconnect with each other, with home and business phones, and with computers using short range wireless connections. Bluetooth network applications include wireless synchronization, e-mail/Internet/intranet access using local personal computer connections, hidden computing through automated applications and networking, and applications that can be used for such devices as hands-free headsets and car kits. The Bluetooth standard specifies wireless operation in the 2.45 Gigahertz (GHz) radio band and supports data rates up to 720kbps.
Bluetooth is an open wireless protocol for exchanging data over short distances (using short radio waves) from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization.
Bluetooth uses a radio technology called frequency-hopping spread spectrum, which chops up the data being sent and transmits chunks of it on up to 79 frequencies. In its basic mode, the modulation is Gaussian frequency-shift keying (GFSK). It can achieve a gross data rate of 1 Mb/s. Bluetooth provides a way to connect and exchange information between devices such as mobile phones, telephones, laptops, personal computers, printers, Global Positioning System (GPS) receivers, digital cameras, and video game consoles through a secure, globally unlicensed Industrial, Scientific and Medical (ISM) 2.4 GHz short-range radio frequency bandwidth. The Bluetooth specifications are developed and licensed by the Bluetooth Special Interest Group (SIG). The Bluetooth SIG consists of companies in the areas of telecommunication, computing, networking, and consumer electronics.
Bluetooth is a standard and a communications protocol primarily designed for low power consumption, with a short range based on low-cost transceiver microchips in each device. Bluetooth makes it possible for these devices to communicate with each other when they are in range. Because the devices use a radio communications system, they do not have to be in line of sight of each other.
In most cases the effective range of class 2 devices is extended if they connect to a class 1 transceiver, compared to a pure class 2 network. This is accomplished by the higher sensitivity and transmission power of Class 1 devices.
List of applications
A typical Bluetooth mobile phone headset.
More prevalent applications of Bluetooth include:
* Wireless control of and communication between a mobile phone and a hands-free headset. This was one of the earliest applications to become popular.
* Wireless networking between PCs in a confined space and where little bandwidth is required.
* Wireless communication with PC input and output devices, the most common being the printer.
* Transfer of files, contact details, calendar appointments, and reminders between devices with OBEX.
* Replacement of traditional wired GPS receivers, medical equipment, bar code scanners, and traffic control devices.
* For controls where infrared was traditionally used.
* For low bandwidth applications where higher [USB] bandwidth is not required and cable-free connection desired.
* Sending small advertisements from Bluetooth-enabled advertising hoardings to other, discoverable, Bluetooth devices.
* Wireless bridge between two Industrial Ethernet networks.
* Two seventh-generation PlayStation 3, use Bluetooth for their respective wireless controllers.
* Dial-up internet access on personal computers or PDAs using a data-capable mobile phone as a wireless modem like Novatel Mifi.
Bluetooth vs. Wi-Fi IEEE 802.11 in networking
Bluetooth and Wi-Fi have many applications in today's offices, homes, and on the move: setting up networks, printing, or transferring presentations and files from PDAs to computers. Both are versions of unlicensed wireless technology.
local area network access in work areas.
A Bluetooth USB dongle with a 100m range.
Bluetooth exists in many products, such as telephones, the citation needed], modems and headsets. The technology is useful when transferring information between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones or byte data with hand-held computers.
Bluetooth protocols simplify the discovery and setup of services between devices. Bluetooth devices can advertise all of the services they provide. This makes using services easier because more of the security, network address and permission configuration can be automated than with many other network types.
Mobile phone requirements
A mobile phone that is Bluetooth enabled is able to pair with many devices. To ensure the broadest support of feature functionality together with legacy device support, the Open Mobile Terminal Platform (OMTP) forum has recently published a recommendations paper, entitled "Bluetooth Local Connectivity"; see external links below to download this paper.
Series of Bluetooth
Bluetooth 1.0 and 1.0B
Versions 1.0 and 1.0B had many problems, and manufacturers had difficulty making their products interoperable. Versions 1.0 and 1.0B also included mandatory Bluetooth hardware device address transmission in the Connecting process (rendering anonymity impossible at the protocol level), which was a major setback for certain services planned for use in Bluetooth environments.
* Ratified as IEEE Standard 802.15.1-2002.
* Many errors found in the 1.0B specifications were fixed.
* Added support for non-encrypted channels.
* Received Signal Strength Indicator (RSSI).
This version is backward compatible with 1.1 and the major enhancements include the following:
* Faster Connection and Discovery
* Adaptive radio frequency interference by avoiding the use of crowded frequencies in the hopping sequence.
* Higher transmission speeds in practice, up to 721 Kbit/s, than in 1.1.
* Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better support for concurrent data transfer.
* Ratified as IEEE Standard 802.15.1-2005.
* Introduced Flow Control and Retransmission Modes for L2CAP.
This version of the Bluetooth specification was released on November 10, 2004. It is backward compatible with the previous version 1.2. The main difference is the introduction of an Enhanced Data Rate (EDR) for faster data transfer. The nominal rate of EDR is about 3 megabits per second, although the practical data transfer rate is 2.1 megabits per second.According to the 2.0 specification, EDR provides the following benefits:
* Three times the transmission speed (2.1Mbit/s) in some cases.
* Reduced complexity of multiple simultaneous connections due to additional bandwidth.
* Lower power consumption through a reduced duty cycle.
Bluetooth Core Specification Version 2.1 is fully backward compatible with 1.2, and was adopted by the Bluetooth SIG on July 26, 2007. It supports theoretical data transfer speeds of up to 3 Mb/s. This specification includes the following features:
The 3.0 specification was adopted by the UWB, but UWB is missing from the specification.
Telephone control protocol
Telephony control protocol-binary is the bit-oriented protocol that defines the call control signaling for the establishment of voice and data calls between Bluetooth devices. Additionally, "TCS BIN defines mobility management procedures for handling groups of Bluetooth TCS devices."
TCS-BIN is only used by the cordless telephony profile, which failed to attract implementers. As such it is only of historical interest.
Adopted protocols are defined by other standards-making organizations and incorporated into Bluetooth's protocol stack, allowing Bluetooth to create protocols only when necessary. The adopted protocols include:
Point-to-Point Protocol (PPP)
Internet standard protocol for transporting IP datagrams over a point-to-point link
Object Exchange Protocol (OBEX)
Session-layer protocol for the exchange of objects, providing a model for object and operation representation
Wireless Application Environment/Wireless Application Protocol (WAE/WAP)
WAE specifies an application framework for wireless devices and WAP is an open standard to provide mobile users access to telephony and information services.
Bluetooth implements E0 stream cipher is used for encrypting packets, granting confidentiality and is based on a shared cryptographic secret, namely a previously generated link key or master key. Those keys, used for subsequent encryption of data sent via the air interface, rely on the Bluetooth PIN, which has been entered into one or both devices.
In September 2008, the National Institute of Standards and Technology (NIST) published a Guide to Bluetooth Security that will serve as reference to organization on the security capabilities of Bluetooth and steps for securing Bluetooth technologies effectively. While Bluetooth has its benefits, it is susceptible to denial of service attacks, eavesdropping, man-in-the-middle attacks, message modification, and resource misappropriation. Users/organizations must evaluate their acceptable level of risk and incorporate security into the lifecycle of Bluetooth devices.
23. Carson, Mary Kay (2007). Alexander Graham Bell: Giving Voice To The World. Sterling Biographies. 387 Park Avenue South, New York, NY 10016: Sterling Publishing Co., Inc. pp.76-78.
- Bell, A. G.: "On the Production and Reproduction of Sound by Light", American Journal of Science, Third Series, vol. XX, #118, October 1880, pp.305 - 324; also published as "Selenium and the Photophone" in Nature, September 1880.