IEEE 802.11

This Linksys WRT54GS Wi-Fi router operates on the 2.4 GHz "g" standard, capable of transmitting 54 Mbit/s.
For comparison, this Netgear dual-band router from 2013 uses the "ac" standard, capable of transmitting 1900 Mbit/s (combined).
Graphical representation of Wi-Fi application specific (UDP) performance envelope 2.4 GHz band, with 802.11g. 1 Mbps = 1 Mbit/s
Graphical representation of Wi-Fi application specific (UDP) performance envelope 2.4 GHz band, with 802.11n with 40MHz
Graphical representation of Wi-Fi channels in the 2.4 GHz band
Spectral masks for 802.11g channels 1–14 in the 2.4 GHz band
802.11 non-overlapping channels for 2.4GHz. Covers 802.11b,g,n

Part of the IEEE 802 set of local area network technical standards, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) computer communication.

- IEEE 802.11

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Ethernet

Family of wired computer networking technologies commonly used in local area networks , metropolitan area networks (MAN) and wide area networks (WAN).

A twisted pair cable with an 8P8C modular connector attached to a laptop computer, used for Ethernet
An Ethernet-over-twisted-pair port
Symbol used by Apple on some devices to denote an Ethernet connection.
Accton Etherpocket-SP parallel port Ethernet adapter (circa 1990). Supports both coaxial (10BASE2) and twisted pair (10BASE-T) cables. Power is drawn from a PS/2 port passthrough cable.
An Intel 82574L Gigabit Ethernet NIC, PCI Express ×1 card
Older Ethernet equipment. Clockwise from top-left: An Ethernet transceiver with an in-line 10BASE2 adapter, a similar model transceiver with a 10BASE5 adapter, an AUI cable, a different style of transceiver with 10BASE2 BNC T-connector, two 10BASE5 end fittings (N connectors), an orange "vampire tap" installation tool (which includes a specialized drill bit at one end and a socket wrench at the other), and an early model 10BASE5 transceiver (h4000) manufactured by DEC. The short length of yellow 10BASE5 cable has one end fitted with an N connector and the other end prepared to have an N connector shell installed; the half-black, half-grey rectangular object through which the cable passes is an installed vampire tap.
A 1990s ISA network interface card supporting both coaxial-cable-based 10BASE2 (BNC connector, left) and twisted-pair-based 10BASE-T (8P8C connector, right)
Patch cables with patch fields of two Ethernet switches
A core Ethernet switch
A close-up of the SMSC LAN91C110 (SMSC 91x) chip, an embedded Ethernet chip
The original Ethernet implementation: shared medium, collision-prone. All computers trying to communicate share the same cable, and so compete with each other.
Modern Ethernet implementation: switched connection, collision-free. Each computer communicates only with its own switch, without competition for the cable with others.

The 48-bit MAC address was adopted by other IEEE 802 networking standards, including IEEE 802.11 (Wi-Fi), as well as by FDDI.

Wi-Fi

A newly installed home Wi-Fi network in April 2022.
Wi-Fi certification logo
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.
An outdoor Wi-Fi access point
Generic 802.11 Frame
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
Embedded serial-to-Wi-Fi module
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.

Direct-sequence spread spectrum

Spread-spectrum modulation technique primarily used to reduce overall signal interference.

Spread spectrum of a modern switching power supply (heating up period) incl. waterfall diagram over a few minutes. Recorded with a NF-5030 EMC-Analyzer

Some practical and effective uses of DSSS include the code-division multiple access (CDMA) method, the IEEE 802.11b specification used in Wi-Fi networks, and the Global Positioning System.

Wireless LAN

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.

This notebook computer is connected to a wireless access point using a PC Card wireless card.
An example of a Wi-Fi network
54 Mbit/s WLAN PCI Card (802.11g)
Peer-to-Peer or ad hoc wireless LAN
Hidden node problem: Devices A and C are both communicating with B, but are unaware of each other
Roaming among Wireless Local Area Networks

Wireless LANs based on the IEEE 802.11 standards are the most widely used computer networks in the world.

Quadrature amplitude modulation

Name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information.

Analog QAM: measured PAL color bar signal on a vector analyzer screen.
Digital 16-QAM with example constellation points
Constellation points for 4-QAM, 16-QAM, 32-QAM, and 64-QAM overlapped
Bit-loading (bits per QAM constellation) on an ADSL line

QAM is used extensively as a modulation scheme for digital telecommunication systems, such as in 802.11 Wi-Fi standards.

Bluetooth

Short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances using UHF radio waves in the ISM bands, from 2.402GHz to 2.48GHz, and building personal area networks .

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Ericsson Bluetooth module PBA 313 01/2S R2A manufactured in week 22, 2001.
A typical Bluetooth mobile phone headset
A Bluetooth USB dongle with a 100 m range
A typical Bluetooth USB dongle
An internal notebook Bluetooth card (14×36×4mm)
Bluetooth Protocol Stack

Bluetooth and Wi-Fi (Wi-Fi is the brand name for products using IEEE 802.11 standards) have some similar applications: setting up networks, printing, or transferring files.

IEEE 802.11g-2003

Amendment to the IEEE 802.11 specification that operates in the 2.4 GHz microwave band.

Top to bottom: Lights flashing at frequencies, 1 Hz and 2 Hz; that is, at 0.5, 1.0 and 2.0 flashes per second, respectively. The time between each flash – the period T – is given by 1⁄f (the reciprocal of f); that is, 2, 1 and 0.5 seconds, respectively.

The 802.11g protocol is now Clause 19 of the published IEEE 802.11-2007 standard, and Clause 19 of the published IEEE 802.11-2012 standard.

Carrier-sense multiple access with collision avoidance

Network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by beginning transmission only after the channel is sensed to be "idle".

Simplified algorithm of CSMA/CA

Devices utilizing 802.11 based standards can enjoy the benefits of collision avoidance (RTS / CTS handshake, also Point coordination function), although they do not do so by default.

IEEE 802.11b-1999

Amendment to the IEEE 802.11 wireless networking specification that extends throughput up to 11 Mbit/s using the same 2.4 GHz band.

802.11b/g channels in 2.4 GHz band

A related amendment was incorporated into the IEEE 802.11-2007 standard.

IEEE 802.11n-2009

Wireless-networking standard that uses multiple antennas to increase data rates.

IEEE 802.11n-2009 is an amendment to the IEEE 802.11-2007 wireless-networking standard.