HOME

TheInfoList



OR:

In computer networking, a wireless access point (WAP), or more generally just access point (AP), is a networking hardware device that allows other Wi-Fi devices to connect to a wired network. As a standalone device, the AP may have a wired connection to a router, but, in a wireless router, it can also be an integral component of the router itself. An AP is differentiated from a hotspot which is a physical location where Wi-Fi access is available.


Connections

An AP connects directly to a wired local area network, typically
Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...
, and the AP then provides wireless connections using wireless LAN technology, typically Wi-Fi, for other devices to use that wired connection. APs support the connection of multiple wireless devices through their one wired connection.


Wireless data standards

There are many wireless data standards that have been introduced for wireless access point and wireless router technology. New standards have been created to accommodate the increasing need for faster wireless connections. Some wireless routers provide backward compatibility with older Wi-Fi technologies as many devices were manufactured for use with older standards. * 802.11a * 802.11b * 802.11g * 802.11n (Wi-Fi 4) *
802.11ac IEEE 802.11ac-2013 or 802.11ac is a wireless networking standard in the IEEE 802.11 set of protocols (which is part of the Wi-Fi networking family), providing high-throughput wireless local area networks (WLANs) on the 5 GHz band. The stand ...
(Wi-Fi 5) * 802.11ax, (Wi-Fi 6)


Wireless access point vs. ad hoc network

Some people confuse wireless access points with wireless ad hoc networks. An ad hoc network uses a connection between two or more devices ''without'' using a wireless access point; The devices communicate directly when in range. Because setup is easy and does not require an access point, an ad hoc network is used in situations such as a quick data exchange or a multiplayer video game. Due to its peer-to-peer layout, ad hoc Wi-Fi connections are similar to connections available using
Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is limi ...
. Ad hoc connections are generally not recommended for a permanent installation.
Internet access Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the World Wide Web. Internet access is sold by Interne ...
via
ad hoc network An ad hoc network refers to technologies that allow network communications on an ad hoc basis. Associated technologies include: *Wireless ad hoc network *Mobile ad hoc network * Vehicular ad hoc network ** Intelligent vehicular ad hoc network * Prot ...
s, using features like
Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for se ...
' Internet Connection Sharing, may work well with a small number of devices that are close to each other, but ad hoc networks do not scale well. Internet traffic will converge to the nodes with direct internet connection, potentially congesting these nodes. For internet-enabled nodes, access points have a clear advantage, with the possibility of having a wired
LAN Lan or LAN may also refer to: Science and technology * Local asymptotic normality, a fundamental property of regular models in statistics * Longitude of the ascending node, one of the orbital elements used to specify the orbit of an object in spa ...
.


Limitations

It is generally recommended that one IEEE 802.11 AP should have, at a maximum, 10-25 clients. However, the actual maximum number of clients that can be supported can vary significantly depending on several factors, such as type of APs in use, density of client environment, desired client throughput, etc. The range of
communication Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inqui ...
can also vary significantly, depending on such variables as indoor or outdoor placement, height above ground, nearby obstructions, other electronic devices that might actively interfere with the signal by broadcasting on the same frequency, type of
antenna Antenna ( antennas or antennae) may refer to: Science and engineering * Antenna (radio), also known as an aerial, a transducer designed to transmit or receive electromagnetic (e.g., TV or radio) waves * Antennae Galaxies, the name of two collid ...
, the current weather, operating
radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the up ...
, and the power output of devices. Network designers can extend the range of APs through the use of repeaters, which amplify a radio signal, and
reflector Reflector may refer to: Science * Reflector, a device that causes reflection (for example, a mirror or a retroreflector) * Reflector (photography), used to control lighting contrast * Reflecting telescope * Reflector (antenna), the part of an ...
s, which only bounce it. In experimental conditions, wireless networking has operated over distances of several hundred kilometers. Most jurisdictions have only a limited number of frequencies legally available for use by wireless networks. Usually, adjacent APs will use different frequencies (Channels) to communicate with their clients in order to avoid interference between the two nearby systems. Wireless devices can "listen" for data traffic on other frequencies, and can rapidly switch from one frequency to another to achieve better reception. However, the limited number of frequencies becomes problematic in crowded downtown areas with tall buildings using multiple APs. In such an
environment Environment most often refers to: __NOTOC__ * Natural environment, all living and non-living things occurring naturally * Biophysical environment, the physical and biological factors along with their chemical interactions that affect an organism or ...
, signal overlap becomes an issue causing interference, which results in signal degradation and data errors. Wireless networking lags wired networking in terms of increasing bandwidth and throughput. While (as of 2013) high-density 256-QAM (TurboQAM) modulation, 3-antenna wireless devices for the consumer market can reach sustained real-world speeds of some 240 Mbit/s at 13 m behind two standing walls (
NLOS Non-line-of-sight (NLOS) radio propagation occurs outside of the typical line-of-sight (LOS) between the transmitter and receiver, such as in ground reflections. Near-line-of-sight (also NLOS) conditions refer to partial obstruction by a physic ...
) depending on their nature or 360 Mbit/s at 10 m line of sight or 380 Mbit/s at 2 m line of sight (
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operati ...
802.11ac IEEE 802.11ac-2013 or 802.11ac is a wireless networking standard in the IEEE 802.11 set of protocols (which is part of the Wi-Fi networking family), providing high-throughput wireless local area networks (WLANs) on the 5 GHz band. The stand ...
) or 20 to 25 Mbit/s at 2 m line of sight (
IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a 501(c)(3) professional association for electronic engineering and electrical engineering (and associated disciplines) with its corporate office in New York City and its operati ...
802.11g), wired hardware of similar cost reaches closer to 1000 Mbit/s up to specified distance of 100 m with twisted-pair cabling in optimal conditions ( Category 5 (known as Cat-5) or better cabling with
Gigabit Ethernet In computer networking, Gigabit Ethernet (GbE or 1 GigE) is the term applied to transmitting Ethernet frames at a rate of a gigabit per second. The most popular variant, 1000BASE-T, is defined by the IEEE 802.3ab standard. It came into use ...
). One impediment to increasing the speed of wireless communications comes from
Wi-Fi Wi-Fi () 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 ...
's use of a shared communications medium: Thus, two stations in infrastructure mode that are communicating with each other even over the same AP must have each and every frame transmitted twice: from the sender to the AP, then from the AP to the receiver. This approximately halves the effective bandwidth, so an AP is only able to use somewhat less than half the actual over-the-air rate for data throughput. Thus a typical 54 Mbit/s wireless connection actually carries
TCP/IP The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the su ...
data at 20 to 25 Mbit/s. Users of legacy wired networks expect faster speeds, and people using wireless connections keenly want to see the wireless networks catch up. By 2012, 802.11n based access points and client devices have already taken a fair share of the marketplace and with the finalization of the 802.11n standard in 2009 inherent problems integrating products from different vendors are less prevalent.


Security

Wireless access has special security considerations. Many wired networks base the security on physical access control, trusting all the users on the local network, but if wireless access points are connected to the network, anybody within range of the AP (which typically extends farther than the intended area) can attach to the network. The most common solution is wireless traffic encryption. Modern access points come with built-in encryption. The first generation encryption scheme, WEP, proved easy to crack; the second and third generation schemes, WPA and WPA2, are considered secure if a strong enough password or passphrase is used. Some APs support hotspot style authentication using
RADIUS In classical geometry, a radius (plural, : radii) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', ...
and other
authentication server An authentication server provides a network service that applications use to authenticate the credentials, usually account names and passwords, of their users. When a client submits a valid set of credentials, it receives a cryptographic ticket tha ...
s. Opinions about wireless network security vary widely. For example, in a 2008 article for '' Wired'' magazine, Bruce Schneier asserted the net benefits of open Wi-Fi without passwords outweigh the risks, a position supported in 2014 by Peter Eckersley of the Electronic Frontier Foundation. The opposite position was taken by Nick Mediati in an article for '' PC World'', in which he advocates that every wireless access point should be protected with a password.


See also

*
Femtocell In telecommunications, a femtocell is a small, low-power cellular base station, typically designed for use in a home or small business. A broader term which is more widespread in the industry is ''small cell'', with ''femtocell'' as a subset. It ...
– a local-area base station using cellular network standards such as UMTS, rather than Wi-Fi * HomePlug – wired LAN technology that has a few elements in common with Wi-Fi * Lightweight Access Point Protocol – used to manage a large set of APs * List of router firmware projects * Wi-Fi array – system of multiple APs *
Wi-Fi Direct Wi-Fi Direct (formerly Wi-Fi Peer-to-Peer) is a Wi-Fi standard for peer-to-peer wireless connections that allows two devices to establish a direct Wi-Fi connection without an intermediary wireless access point, router, or Internet connection. W ...
– a Wi-Fi standard that enables devices to connect with each other without requiring a (hardware) wireless access point and to communicate at typical Wi-Fi speeds *
WiMAX 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. The WiMAX ...
– wide-area wireless standard that has a few elements in common with Wi-Fi


References

{{Reflist Access point Network access Telecommunications infrastructure Access point