Editing Wireless LAN (section)

== Types of wireless LANs ==
The [[IEEE 802.11]] has two basic modes of operation: ''infrastructure'' and ''ad hoc'' mode. In ad hoc mode, mobile units communicate directly peer-to-peer. In infrastructure mode, mobile units communicate through a [[wireless access point]] (WAP) that also serves as a bridge to other networks such as a [[local area network]] or the Internet.

Since wireless communication uses a more open medium for communication in comparison to wired LANs, the 802.11 designers also included encryption mechanisms: [[Wired Equivalent Privacy]] (WEP), no longer considered secure, [[Wi-Fi Protected Access]] (WPA, WPA2, WPA3), to secure wireless computer networks. Many access points will also offer [[Wi-Fi Protected Setup]], a quick, but no longer considered secure, method of joining a new device to an encrypted network.

=== Infrastructure ===
Most Wi-Fi networks are deployed in ''infrastructure mode''. In infrastructure mode, wireless clients, such as laptops and smartphones, connect to the WAP to join the network. The WAP usually has a wired network connection and may have permanent wireless connections to other WAPs.

WAPs are usually fixed and provide service to their client nodes within range. Some networks will have multiple WAPs using the same SSID and security arrangement. In that case, connecting to any WAP on that network joins the client to the network, and the client software will try to choose the WAP that gives the best service, such as the WAP with the strongest signal.

=== Peer-to-peer ===
[[File:Wlan adhoc.png|thumb|Peer-to-Peer or ad hoc wireless LAN]]

An [[Wireless ad hoc network|ad hoc network]] is a network where stations communicate only [[peer-to-peer]] (P2P). There is no base and no one gives permission to talk. This is accomplished using the [[Independent Basic Service Set]] (IBSS). A [[Wi-Fi Direct]] network is a different type of wireless network where stations communicate peer-to-peer.<ref>{{cite web|title=Is this the same as Ad Hoc mode?|url=http://www.wi-fi.org/knowledge-center/faq/same-ad-hoc-mode|archive-url=https://web.archive.org/web/20130830054611/https://www.wi-fi.org/knowledge-center/faq/same-ad-hoc-mode|archive-date=2013-08-30}}</ref> In a peer-to-peer network wireless devices within range of each other can discover and communicate directly without involving central access points.

In a Wi-Fi P2P group, the group owner operates as an access point and all other devices are clients. There are two main methods to establish a group owner in the Wi-Fi Direct group. In one approach, the user sets up a P2P group owner manually. This method is also known as ''autonomous group owner'' (''autonomous GO''). In the second method, called ''negotiation-based group creation'', two devices compete based on the group owner intent value. The device with higher intent value becomes a group owner and the second device becomes a client. Group owner intent value can depend on whether the wireless device performs a cross-connection between an infrastructure WLAN service and a P2P group, available power in the wireless device, whether the wireless device is already a group owner in another group or a received signal strength of the first wireless device.

[[File:Wifi hidden station problem.svg|thumb|[[Hidden node problem]]: Devices A and C are both communicating with B, but are unaware of each other]]

[[IEEE 802.11]] defines the PHY and [[medium access control]] (MAC) layers based on [[carrier-sense multiple access with collision avoidance]] (CSMA/CA). This is in contrast to Ethernet which uses [[carrier-sense multiple access with collision detection]] (CSMA/CD). The 802.11 specification includes provisions designed to minimize collisions because mobile units have to contend with the [[hidden node problem]] where two mobile units may both be in range of a common access point, but out of range of each other.

=== Bridge ===
A bridge can be used to connect networks, typically of different types. A wireless [[Ethernet]] bridge allows the connection of devices on a wired Ethernet network to a wireless network. The bridge acts as the connection point to the wireless LAN.

=== Wireless distribution system ===
A [[wireless distribution system]] (WDS) enables 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 need for a wired backbone to link them, as is traditionally required. The notable advantage of a WDS over some other solutions is that it preserves the MAC addresses of client packets across links between access points.<ref>{{cite web|url=http://www.dd-wrt.com/wiki/index.php?title=WDS_Linked_router_network|title=Wireless Distribution System Linked Router Network|website=DD-WRT Wiki|access-date=December 31, 2006|archive-date=June 30, 2017|archive-url=https://web.archive.org/web/20170630160927/http://www.dd-wrt.com/wiki/index.php?title=WDS_Linked_router_network|url-status=live}}</ref> 

An access point can be either a main, relay, or remote base station. A main base station is typically connected to the wired Ethernet. A relay base station relays data between remote base stations, wireless clients or other relay stations to either a main or another relay base station. A remote base station accepts connections from wireless clients and passes them to relay or main stations.

Because data is forwarded wirelessly, consuming wireless bandwidth, throughput in this method is halved for wireless clients not connected to a main base station. Connections between base stations are done at layer-2 and do not involve or require layer-3 IP addresses. WDS capability may also be referred to as repeater mode because it appears to bridge and accept wireless clients at the same time (unlike traditional bridging).

All base stations in a WDS must be configured to use the same radio channel and share WEP keys or WPA keys if they are used. They can be configured to different service set identifiers. WDS also requires that every base station be configured to forward to others in the system as mentioned above.