Wireless access point

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Cisco Aironet wireless access point

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.

Contents

Connections

Linksys "WAP54G" 802.11g wireless router Linksys WAP54G.JPG
Linksys "WAP54G" 802.11g wireless router
Embedded RouterBoard 112, widely used by wireless Internet service providers (WISPs) across the world, with U.FL-RSMA pigtail and R52 mini PCI Wi-Fi card RouterBoard 112 with U.FL-RSMA pigtail and R52 miniPCI Wi-Fi card.jpg
Embedded RouterBoard 112, widely used by wireless Internet service providers (WISPs) across the world, with U.FL-RSMA pigtail and R52 mini PCI Wi-Fi card

An AP connects directly to a wired local [1] area network, typically Ethernet, 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. [1]

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.

Ad hoc connections are generally not recommended for a permanent installation. [2] Internet access via ad hoc networks, using features like Windows' 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.

Limitations

It is generally recommended that one IEEE 802.11 AP should have, at a maximum, 10-25 clients. [3] 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 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, the current weather, operating radio frequency, 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 reflectors, which only bounce it. In experimental conditions, wireless networking has operated over distances of several hundred kilometers. [4]

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, signal overlap becomes an issue causing interference, which results in signal degradation and data errors. [5]

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) 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 802.11ac) or 20 to 25 Mbit/s at 2 m line of sight (IEEE 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). One impediment to increasing the speed of wireless communications comes from Wi-Fi'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 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 [6] if a strong enough password or passphrase is used.

Some APs support hotspot style authentication using RADIUS and other authentication servers.

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, [7] a position supported in 2014 by Peter Eckersley of the Electronic Frontier Foundation. [8] 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. [9]

See also

Related Research Articles

<span class="mw-page-title-main">IEEE 802.11</span> Specifications for Wi-Fi wireless networks

IEEE 802.11 is part of the IEEE 802 set of local area network (LAN) 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. The standard and amendments provide the basis for wireless network products using the Wi-Fi brand and are the world's most widely used wireless computer networking standards. IEEE 802.11 is used in most home and office networks to allow laptops, printers, smartphones, and other devices to communicate with each other and access the Internet without connecting wires.

<span class="mw-page-title-main">Wireless LAN</span> Computer network that links devices using wireless communication within a limited area

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. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.

<span class="mw-page-title-main">Wireless network</span> Network not fully connected by cables

A wireless network is a computer network that uses wireless data connections between network nodes.

<span class="mw-page-title-main">Wi-Fi</span> Wireless local area network

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. These are the most widely used computer networks in the world, used globally in home and small office networks to link desktop and laptop computers, tablet computers, smartphones, smart TVs, printers, and smart speakers together and to a wireless router to connect them to the Internet, and in wireless access points in public places like coffee shops, hotels, libraries and airports to provide visitors with Internet access for their mobile devices.

<span class="mw-page-title-main">WiMAX</span> Wireless broadband standard

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.

<span class="mw-page-title-main">Wireless mesh network</span> Radio nodes organized in a mesh topology

A wireless mesh network (WMN) is a communications network made up of radio nodes organized in a mesh topology. It can also be a form of wireless ad hoc network.

A wireless distribution system (WDS) is a system enabling the wireless interconnection of access points in an IEEE 802.11 network. It allows a wireless network to be expanded using multiple access points without the traditional requirement for a wired backbone to link them. The notable advantage of WDS over other solutions is that it preserves the MAC addresses of client frames across links between access points.

<span class="mw-page-title-main">Hotspot (Wi-Fi)</span> Wi-Fi access point

A hotspot is a physical location where people can obtain Internet access, typically using Wi-Fi technology, via a wireless local-area network (WLAN) using a router connected to an Internet service provider.

<span class="mw-page-title-main">Wireless network interface controller</span> Hardware component that connects a computer to a wireless computer network

A wireless network interface controller (WNIC) is a network interface controller which connects to a wireless network, such as Wi-Fi or Bluetooth, rather than a wired network, such as a Token Ring or Ethernet. A WNIC, just like other NICs, works on the layers 1 and 2 of the OSI model and uses an antenna to communicate via radio waves.

<span class="mw-page-title-main">Wireless security</span> Aspect of wireless networks

Wireless security is the prevention of unauthorized access or damage to computers or data using wireless networks, which include Wi-Fi networks. The term may also refer to the protection of the wireless network itself from adversaries seeking to damage the confidentiality, integrity, or availability of the network. The most common type is Wi-Fi security, which includes Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA). WEP is an old IEEE 802.11 standard from 1997. It is a notoriously weak security standard: the password it uses can often be cracked in a few minutes with a basic laptop computer and widely available software tools. WEP was superseded in 2003 by WPA, a quick alternative at the time to improve security over WEP. The current standard is WPA2; some hardware cannot support WPA2 without firmware upgrade or replacement. WPA2 uses an encryption device that encrypts the network with a 256-bit key; the longer key length improves security over WEP. Enterprises often enforce security using a certificate-based system to authenticate the connecting device, following the standard 802.11X.

IEEE 802.11n-2009 or 802.11n is a wireless-networking standard that uses multiple antennas to increase data rates. The Wi-Fi Alliance has also retroactively labelled the technology for the standard as Wi-Fi 4. It standardized support for multiple-input multiple-output, frame aggregation, and security improvements, among other features, and can be used in the 2.4 GHz or 5 GHz frequency bands.

<span class="mw-page-title-main">Home network</span> Type of computer network

A home network or home area network (HAN) is a type of computer network that facilitates communication among devices within the close vicinity of a home. Devices capable of participating in this network, for example, smart devices such as network printers and handheld mobile computers, often gain enhanced emergent capabilities through their ability to interact. These additional capabilities can be used to increase the quality of life inside the home in a variety of ways, such as automation of repetitive tasks, increased personal productivity, enhanced home security, and easier access to entertainment.

<span class="mw-page-title-main">Computer network</span> Network that allows computers to share resources and communicate with each other

A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.

Long-range Wi-Fi is used for low-cost, unregulated point-to-point computer network connections, as an alternative to other fixed wireless, cellular networks or satellite Internet access.

IEEE 802.11a-1999 or 802.11a was an amendment to the IEEE 802.11 wireless local network specifications that defined requirements for an orthogonal frequency-division multiplexing (OFDM) communication system. It was originally designed to support wireless communication in the unlicensed national information infrastructure (U-NII) bands as regulated in the United States by the Code of Federal Regulations, Title 47, Section 15.407.

IEEE 802.11b-1999 or 802.11b is an amendment to the IEEE 802.11 wireless networking specification that extends throughput up to 11 Mbit/s using the same 2.4 GHz band. A related amendment was incorporated into the IEEE 802.11-2007 standard.

IEEE 802.11g-2003 or 802.11g is an amendment to the IEEE 802.11 specification that operates in the 2.4 GHz microwave band. The standard has extended throughput to up to 54 Mbit/s using the same 20 MHz bandwidth as 802.11b uses to achieve 11 Mbit/s. This specification under the marketing name of Wi-Fi has been implemented all over the world. 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.

There are several uses of the 2.4 GHz band. Interference may occur between devices operating at 5.4 GHz. This article details the different users of the 2.4 GHz band, how they cause interference to other users and how they are prone to interference from other users.

Wi-Fi Direct 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. Wi-Fi Direct is single-hop communication, rather than multihop communication like wireless ad hoc networks.

IEEE 802.11ac-2013 or 802.11ac is a wireless networking standard in the IEEE 802.11 set of protocols, providing high-throughput wireless local area networks (WLANs) on the 5 GHz band. The standard has been retroactively labelled as Wi-Fi 5 by Wi-Fi Alliance.

References

  1. 1 2 "Wireless Routers Guide: Everything You Need To Know". Breech.co. Retrieved 2018-10-17.
  2. Chris Hoffman (2016-09-22). "What's the Difference Between Ad-Hoc and Infrastructure Mode Wi-Fi?" . Retrieved 2017-12-16.
  3. "Designing and Building a Campus Wireless Network" (PDF). MCNC. 2012. For areas that have high bandwidth and a concentrated area of users (i.e. classrooms in a 1:1 computing school), plan for approximately 15-25 data users per AP. When wireless devices are used for high bandwidth applications or concurrent use such as online testing, an even greater number of APs may be required to achieve a density closer to 10-15 users per AP.
  4. Ermanno Pietrosemoli. "Setting Long Distance WiFi Records: Proofing Solutions for Rural Connectivity". Fundación Escuela Latinoamericana de Redes University of the Andes (Venezuela) . Retrieved March 17, 2012.
  5. "The overlapping channel problem".
  6. Zhang, Yan; Zheng, Jun; Ma, Miao (2008-01-01). Handbook of Research on Wireless Security. Idea Group Inc (IGI). ISBN   9781599048994.
  7. Bruce Schneier (2008-01-10). "Steal This Wi-Fi". Wired Magazine .
  8. "Why We Need An Open Wireless Movement". Electronic Frontier Foundation. 27 April 2011.
  9. Nick Mediati (June 24, 2011). "How to Secure Your Home Wi-Fi Network". PC World .