Wireless network and Related Topics

Wi-Fi

7 links

A newly installed home Wi-Fi network in April 2022.

An example of a service set called "WiFi Wikipedia" consisting of two Basic Service Sets. They are able to automatically roam between the two BSSs, without the user having to explicitly connect to the second network.

Depiction of a Wi-Fi network in infrastructure mode. The device sends information wirelessly to another device, both connected to the local network, to print a document.

Access points send out beacon frames to announce the presence of networks.

Network planning frequency allocations for North America and Europe. Using these types of frequency allocations can help minimize co-channel and adjacent-channel interference.

In the 2.4 GHz wavebands as well as others, transmitters straddle multiple channels. Overlapping channels can suffer from interference unless this is a small portion of the total received power.

An embedded RouterBoard 112 with U.FL-RSMA pigtail and R52 mini PCI Wi-Fi card widely used by wireless Internet service providers (WISPs) in the Czech Republic

OSBRiDGE 3GN – 802.11n Access Point and UMTS/GSM Gateway in one device

An AirPort wireless G Wi-Fi adapter from an Apple MacBook

Wireless network interface controller Gigabyte GC-WB867D-I

A QR code to automate a Wi-Fi connection using WIFI:S:Wikipedia; T:WPA;P:Password1!;;

Wi-Fi or WiFi is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves.

Radio

5 links

Technology of signaling and communicating using radio waves.

Radio communication. Information such as sound is converted by a transducer such as a microphone to an electrical signal, which modulates a radio wave produced by the transmitter. A receiver intercepts the radio wave and extracts the information-bearing modulation signal, which is converted back to a human usable form with another transducer such as a loudspeaker.

Comparison of AM and FM modulated radio waves

Frequency spectrum of a typical modulated AM or FM radio signal. It consists of a component C at the carrier wave frequency f_c with the information (modulation) contained in two narrow bands of frequencies called sidebands (SB) just above and below the carrier frequency.

Satellite television dish on a residence

Satellite phones, showing the large antennas needed to communicate with the satellite

Parabolic antennas of microwave relay links on tower in Australia

Satellite Communications Center Dubna in Russia

Communications satellite belonging to Azerbaijan

Military air traffic controller on US Navy aircraft carrier monitors aircraft on radar screen

ASR-8 airport surveillance radar antenna. It rotates once every 4.8 seconds. The rectangular antenna on top is the secondary radar.

A personal navigation assistant GPS receiver in a car, which can give driving directions to a destination.

EPIRB emergency locator beacon on a ship

Wildlife officer tracking radio-tagged mountain lion

US Air Force MQ-1 Predator drone flown remotely by a pilot on the ground

Quadcopter, a popular remote-controlled toy

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 (impressing an information signal on the radio wave by varying some aspect of the wave) in the transmitter.

Cellular network

3 links

Communication network where the link to and from end nodes is wireless.

Example of frequency reuse factor or pattern 1/4

Cellular telephone frequency reuse pattern. See

Cellular network standards and generation timeline.

It was an analog wireless network.

RF CMOS

3 links

Metal–oxide–semiconductor integrated circuit (IC) technology that integrates radio-frequency (RF), analog and digital electronics on a mixed-signal CMOS (complementary MOS) RF circuit chip.

It is widely used in modern wireless telecommunications, such as cellular networks, Bluetooth, Wi-Fi, GPS receivers, broadcasting, vehicular communication systems, and the radio transceivers in all modern mobile phones and wireless networking devices.

This notebook computer is connected to a wireless access point using a PC Card wireless card.

Wireless LAN

2 links

Hidden node problem: Devices A and C are both communicating with B, but are unaware of each other

Roaming among Wireless Local Area Networks

A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building.

Microwave

2 links

Form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively.

The atmospheric attenuation of microwaves and far infrared radiation in dry air with a precipitable water vapor level of 0.001 mm. The downward spikes in the graph correspond to frequencies at which microwaves are absorbed more strongly. This graph includes a range of frequencies from 0 to 1 THz; the microwaves are the subset in the range between 0.3 and 300 gigahertz.

Waveguide is used to carry microwaves. Example of waveguides and a diplexer in an air traffic control radar

Disassembled radar speed gun. The grey assembly attached to the end of the copper-colored horn antenna is the Gunn diode which generates the microwaves.

A satellite dish on a residence, which receives satellite television over a Ku band 12–14 GHz microwave beam from a direct broadcast communications satellite in a geostationary orbit 35,700 kilometres (22,000 miles) above the Earth

The parabolic antenna (lower curved surface) of an ASR-9 airport surveillance radar which radiates a narrow vertical fan-shaped beam of 2.7–2.9 GHz (S band) microwaves to locate aircraft in the airspace surrounding an airport.

Small microwave oven on a kitchen counter

Microwaves are widely used for heating in industrial processes. A microwave tunnel oven for softening plastic rods prior to extrusion.

Absorption wavemeter for measuring in the Ku band.

1.2 GHz microwave spark transmitter (left) and coherer receiver (right) used by Guglielmo Marconi during his 1895 experiments had a range of 6.5 km

ku band microstrip circuit used in satellite television dish.

Heinrich Hertz's 450 MHz spark transmitter, 1888, consisting of 23 cm dipole and spark gap at focus of parabolic reflector

Jagadish Chandra Bose in 1894 was the first person to produce millimeter waves; his spark oscillator (in box, right) generated 60 GHz (5 mm) waves using 3 mm metal ball resonators.

$Microwave spectroscopy experiment by John Ambrose Fleming in 1897 showing refraction of 1.4 GHz microwaves by paraffin prism, duplicating earlier experiments by Bose and Righi.$

Augusto Righi's 12 GHz spark oscillator and receiver, 1895

Antennas of 1931 experimental 1.7 GHz microwave relay link across the English Channel.

Experimental 700 MHz transmitter 1932 at Westinghouse labs transmits voice over a mile.

Southworth (at left) demonstrating waveguide at IRE meeting in 1938, showing 1.5 GHz microwaves passing through the 7.5 m flexible metal hose registering on a diode detector.

The first modern horn antenna in 1938 with inventor Wilmer L. Barrow

thumb|Randall and Boot's prototype cavity magnetron tube at the University of Birmingham, 1940. In use the tube was installed between the poles of an electromagnet

First commercial klystron tube, by General Electric, 1940, sectioned to show internal construction

British Mk. VIII, the first microwave air intercept radar, in nose of British fighter. Microwave radar, powered by the new magnetron tube, significantly shortened World War II.

Mobile US Army microwave relay station 1945 demonstrating relay systems using frequencies from 100 MHz to 4.9 GHz which could transmit up to 8 phone calls on a beam.

Microwaves are widely used in modern technology, for example in point-to-point communication links, wireless networks, microwave radio relay networks, radar, satellite and spacecraft communication, medical diathermy and cancer treatment, remote sensing, radio astronomy, particle accelerators, spectroscopy, industrial heating, collision avoidance systems, garage door openers and keyless entry systems, and for cooking food in microwave ovens.

The atmospheric attenuation of microwaves in dry air with a precipitable water vapor level of 0.001 mm. The downward spikes in the graph corresponds to frequencies at which microwaves are absorbed more strongly, such as by oxygen molecules.

Microwave transmission

3 links

Transmission of information by electromagnetic waves with wavelengths in the microwave range of the electromagnetic spectrum.

A parabolic satellite antenna for Erdfunkstelle Raisting, based in Raisting, Bavaria, Germany

C-band horn-reflector antennas on the roof of a telephone switching center in Seattle, Washington, part of the U.S. AT&T Long Lines microwave relay network

Dozens of microwave dishes on the Heinrich-Hertz-Turm in Hamburg, Germany

Communications tower on Frazier Mountain, Southern California with microwave relay dishes

Production truck used for remote broadcasts by television news has a microwave dish on a retractible telescoping mast to transmit live video back to the studio.

Antennas of 1931 experimental 1.7 GHz microwave relay link across the English Channel. The receiving antenna (background, right) was located behind the transmitting antenna to avoid interference.

US Army Signal Corps portable microwave relay station, 1945. Microwave relay systems were first developed in World War II for secure military communication.

In recent years, there has been an explosive increase in use of the microwave spectrum by new telecommunication technologies such as wireless networks, and direct-broadcast satellites which broadcast television and radio directly into consumers' homes.

Base station

2 links

Base station (or base radio station) is – according to the International Telecommunication Union's (ITU) Radio Regulations (RR) – a "land station in the land mobile service."

Basic base station elements used in a remote-controlled installation. Selective calling options such as CTCSS are optional.

The diagram shows a band-pass filter used to reduce the base station receiver's exposure to unwanted signals. It also reduces the transmission of undesired signals. The isolator is a one-way device which reduces the ease of signals from nearby transmitters going up the antenna line and into the base station transmitter. This prevents the unwanted mixing of signals inside the base station transmitter which can generate interference.

A cell tower near Thicketty, South Carolina.

Two GSM mobile phone base station towers disguised as trees in Dublin, Ireland.

A base station disguised as a palm tree in Tucson, Arizona.

Close-up of a base station antenna in Mexico City, Mexico. There are three antennas: each serves a 120-degree segment of the horizon. The microwave dish links the site with the telephone network.

A professional rack-mount iDEN Base Radio at a Cell Site.

Trunked systems have groups of base stations configured as repeaters. The center blocks with frequencies in this trunked block diagram each represent a base station.

136–174 MHz US professional base station antenna examples.

WiMAX base station equipment with a sector antenna and wireless modem on top

Cellular network base station in Yekaterinburg

The term is used in the context of mobile telephony, wireless computer networking and other wireless communications and in land surveying.

WaveLAN

1 links

WaveLAN was a brand name for a family of wireless networking technology sold by NCR, AT&T, Lucent Technologies, and Agere Systems as well as being sold by other companies under OEM agreements.