 | This article needs to beupdated. Please help update this article to reflect recent events or newly available information.(July 2013) |
Awireless network interface controller (WNIC) is anetwork interface controller that connects to awireless network, such asWi-Fi,Bluetooth, orLTE (4G) or5G rather than a wired network, such as anEthernet network. It consists of amodem, an automatedradio transmitter andreceiver which operate in the background, exchanging digital data in the form ofdata packets with other wireless devices orwireless routers usingradio waves radiated by anantenna, linking the devices together transparently in acomputer network. A WNIC, just like othernetwork interface controllers (NICs), works on the layers 1 and 2 of theOSI model.
A wireless network interface controller may be implemented as anexpansion card and connected usingPCI bus orPCIe bus, or connected viaUSB,PC Card,ExpressCard,Mini PCIe orM.2.
The low cost and ubiquity of theWi-Fi standard means that many newer mobile computers have a wireless network interface built into themotherboard.
The term is usually applied to adapters using theWi-Fi (IEEE 802.11) network protocol; it may also apply to a NIC using protocols other than 802.11, such as one implementingBluetooth connections.
An 802.11 WNIC can operate in two modes known asinfrastructure mode andad hoc mode:
TheIEEE 802.11 standard sets out low-level specifications for how all 802.11wireless networks operate. Earlier 802.11 interface controllers are usually only compatible with earlier variants of the standard, while newer cards support both current and old standards.
Specifications commonly used in marketing materials for WNICs include:
Most WNICs support one or more of 802.11, Bluetooth and 3GPP (2G, 3G, 4G, 5G) network standards.
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.[1] Specifically, the maximum throughput speed is only achieved at extremely close range (less than 25 feet (7.6 m) or so); at the outer reaches of a device's effective range, speed may decrease to around 1 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.
In an 802.11 WNIC, theMAC 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 aFullMAC WNIC or aHardMAC NIC[2] and a NIC that implements it in host software is called aSoftMAC NIC.[3]
A FullMAC device hides the complexity of the 802.11 protocol from the main CPU, instead providing an802.3 (Ethernet) interface; a SoftMAC design implements only the timing-critical part of the protocol in hardware/firmware and the rest on the host.[4]
FullMAC chips are typically used in mobile devices because:
Popular example of FullMAC chips is the one implemented on theRaspberry Pi 3.
TheLinux kernel'smac80211 framework provides capabilities for SoftMAC devices and additional capabilities (such as mesh networking, which is known as theIEEE 802.11s standard) for devices with limited functionality.[5][3]
FreeBSD also supports SoftMAC drivers.[6]