Wireless network interface controller: Difference between revisions

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{{Short description|Hardware component that connects a computer to a wireless computer network}}

{{update|date=July 2013}}

[[File:USB-wireless-adapter.jpg|thumb|250px|A wireless network interface device with a USB interface and internal antenna]]

[[File:DELL TrueMobile 350 Bluetooth card.jpg|thumb|A Bluetooth interface card]]

A '''wireless network interface controller''' ('''WNIC''') is a [[network interface controller]] which connects to a [[radiowireless network]], such as [[Wi-basedFi]], [[computerBluetooth]], networkor [[LTE (telecommunication)|LTE]] (4G) or [[5G]] rather than a wire-basedwired network, such as an [[Token RingEthernet]] ornetwork. It consists of a [[Ethernetmodem]]., an Aautomated WNIC,[[radio justtransmitter]] likeand other[[radio NICs,receiver|receiver]] workswhich onoperate in the Layerbackground, 1exchanging anddigital Layerdata 2 ofin the form of [[OSIdata Modelpacket]].s Awith WNICother iswireless andevices essentialor component[[wireless forrouter]]s wirelessusing [[desktopradio computerwave]].s Thisradiated card usesby an [[antenna (radio)|antenna]], tolinking communicatethe throughdevices [[microwaves]].together A WNICtransparently in a desktop computer usually is connected using the [[Peripheralcomputer Component Interconnect|PCInetwork]] bus. Other connectivityA optionsWNIC, arejust [[USB]]like andother [[PCnetwork cardinterface controller]].s Integrated(NICs), WNICsworks areon alsothe available,layers (typically1 inand [[Mini2 of the PCI]]/[[PCI ExpressOSI Mini Cardmodel]] form).

A wireless network interface controller may be implemented as an [[expansion card]] and connected using [[Peripheral Component Interconnect|PCI]] bus or [[PCIe]] bus, or connected via [[USB]], [[PC Card]], [[ExpressCard]], [[Mini PCIe]] or [[M.2]].

The term is usually applied to [[IEEE 802.11]] adapters; it may also apply to a NIC using protocols other than 802.11, such as one implementing [[Bluetooth]] connections.

The low cost and ubiquity of the [[Wi-Fi]] standard means that many newer mobile computers have a wireless network interface built into the [[motherboard]].

(communications)|channel]] and SSID.

The term is usually applied to adapters using the [[Wi-Fi]] ([[IEEE 802.11]]) adaptersnetwork protocol; it may also apply to a NIC using protocols other than 802.11, such as one implementing [[Bluetooth]] connections.

== Modes of operation ==

An 802.11 WNIC can operate in two modes known as ''infrastructure mode'' and ''[[Mobile ad hoc network|ad hoc mode]]'':

; Infrastructure mode

: In an infrastructure mode network the WNIC needs a [[wireless access point]]: all data is transferred using the access point as the central hub. All wireless [[Node (networking)|nodes]] in an infrastructure mode network connect to an access point. All nodes connecting to the access point must have the same [[service set identifier]] (SSID) as the access point. If wireless security is enabled on the access point (such as [[Wired Equivalent Privacy|WEP]] or [[Wi-Fi Protected Access|WPA]]), the NIC must have valid [[authentication]] parameters in order to connect to the access point.

; Ad hoc mode

: In an ad hoc mode network the WNIC does not require an access point, but rather can interface with all other wireless nodes directly. All the [[Node (networking)|node]]s in an ad hoc network must have the same channel and SSID.

== Specifications ==

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Specifications commonly used in marketing materials for WNICs include:

*Wireless [[data transfer]] rates (measured in Mbit/s); these range from 2 Mbit/s to 54 Mbit/s.<ref name="Meyers">Meyers, Mike: Network+ Certification All-in-One Exam Guide, McGraw-Hill, 2004, p. 230.</ref>

*Wireless transmit power (measured in [[dBm]])

*Wireless network standards (may include standardssupported, such as [[802.11b]], [[IEEE 802.11g11a-1999|802.11a]], [[802.11n11g]], etc.) [[802.11g11n]], offers data transfer speeds equivalent to[[IEEE 802.11a &ndash; up to 54 Mbit/s &ndash; and the wider {{convert11ac-2013|300|ft|m|sing=on}} range of 802.11b11ac]], and is backward compatible with[[Wi-Fi 6|802.11b.11ax]]

Most WNICs support one or more of 802.11, Bluetooth and 3GPP (2G, 3G, 4G, 5G) network standards.

Most Bluetooth cards do not implement any form of the 802.11 standard.

==Range==

Wireless range may be substantially affected by objects in the way of the signal and by the quality of the antenna. Large electrical appliances, such as refrigerators, fuse boxes, metal plumbing, and air conditioning units can impede a wireless network signal. The theoretical maximum range of IEEE 802.11 is only reached under ideal circumstances and true effective range is typically about half of the theoretical range.<ref name="Meyers">Meyers, Mike: Network+ Certification All-in-One Exam Guide, McGraw-Hill, 2004, p. 230.</ref> Specifically, the maximum throughput speed is only achieved at extremely close range (less than {{convert|25|ft|m}} or so); at the outer reaches of a device's effective range, speed may decrease to around 1 &nbsp;Mbit/s before it drops out altogether. The reason is that wireless devices dynamically negotiate the top speed at which they can communicate without dropping too many data packets.

== {{Anchor|MAC80211|MLME|FULLMAC|SOFTMAC|HARDMAC}}FullMAC and SoftMAC devices ==

{{Main|Comparison of open-source wireless drivers}}

In an 802.11 WNIC, the ''MAC Sublayer Management Entity'' (MLME) can be implemented either in the NIC's hardware or firmware, or in host-based software that is executed on the main CPU. A WNIC that implements the MLME function in hardware or firmware is called a ''FullMAC'' WNIC or a ''HardMAC'' NIC<ref>{{cite web|url=httphttps://wireless.wiki.kernel.org/en/developers/Documentationdocumentation/Glossaryglossary#FullMACfullmac|title=Linux Wireless glossary|at=Definition of FullMAC|accessdateaccess-date=123 JuneJuly 20162020}}</ref> and a NIC that implements it in host software is called a ''SoftMAC'' NIC.<ref name="glossary-softmac">{{cite web|url=httphttps://wireless.wiki.kernel.org/en/developers/Documentationdocumentation/Glossaryglossary#SoftMACsoftmac|title=Linux Wireless glossary|at=Definition of SoftMAC|accessdateaccess-date=123 JuneJuly 20162020}}</ref>

A FullMAC device hides the complexity of the 802.11 protocol from the main CPU, instead providing an [[802.3]] (Ethernet) interface; a SoftMAC design implements only the timing-critical part of the protocol in hardware/firmware and the rest on the host.<ref name="Pathan2010">{{cite book|author=Al-Sakib Khan Pathan|title=Security of Self-Organizing Networks: MANET, WSN, WMN, VANET|url=httphttps://books.google.com/books?id=ZtBnZoijaDcC&pg=PA28|year=2010|publisher=Taylor & Francis|isbn=978-1-4398-1919-7|page=28}}</ref>

FullMAC chips are typically used in mobile devices because:

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* power is saved by having a specialized CPU perform the 802.11 processing;

* the chip vendor has tighter control of the MLME.

Popular example of FullMAC chips is the one implemented on the [[Raspberry Pi|Raspberry Pi 3]].

[[Linux kernel]]'s ''mac80211'' framework provides capabilities for SoftMAC devices and additional capabilities (such as mesh networking, which is known as the [[IEEE 802.11s]] standard) for devices with limited functionality.<ref>{{cite web |url=http://wireless.kernel.org/en/developers/Documentation/mac80211 |title=mac80211 documentation |work=[[kernel.org]]}}</ref><ref name="glossary-softmac"/>

[[FreeBSD]] also supports SoftMAC drivers.<ref>{{cite web|url=http://www.unix.com/man-page/FreeBSD/4/upgt/|title=FreeBSD 11.0 - man page for upgt (freebsd section 4) - Unix & Linux Commands|publisher=|accessdateaccess-date=1 June 2016}}</ref>

== See also ==

{{Portal|Computer networking}}

* [[List of device bandwidths]]

* [[Wi-Fi operating system support]]