Wireless Local Area Network (WLAN)
- [An Example of a Wi-Fi Network - Wikipedia]
- WLAN Technologies
A Wireless Local Area Network (WLAN) implements a flexible data communication system frequently augmenting rather than replacing a wired LAN within a building or campus. WLANs use radio frequency to transmit and receive data over the air, minimizing the need for wired connections.
A WLAN is a group of devices linked together by wireless within a relatively small space like a single office building or home. Three WLAN technologies were included in the original 802.11 standard: Infrared, Frequency Hopping Spread Spectrum (FHSS), and Direct Sequence Spread Spectrum (DSSS). 802.11b focused exclusively on DSSS (Direct-Sequence Spread Spectrum); 802.11a/g/n also used Orthogonal Frequency Division Multiplexing (OFDM).
- Direct-Sequence Spread Spectrum (DSSS)
In telecommunications, direct-sequence spread spectrum (DSSS) is a spread-spectrum modulation technique primarily used to reduce overall signal interference. The direct-sequence modulation makes the transmitted signal wider in bandwidth than the information bandwidth. After the despreading or removal of the direct-sequence modulation in the receiver, the information bandwidth is restored, while the unintentional and intentional interference is substantially reduced.
- Orthogonal Frequency Division Multiplexing (OFDM)
In telecommunications, orthogonal frequency-division multiplexing (OFDM) is a type of digital transmission and a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, used in applications such as digital television and audio broadcasting, DSL internet access, wireless networks, power line networks, and 4G/5G mobile communications.
- WLAN vs. Wi-Fi
Although the terms WLAN and Wi-Fi are used interchangeably, the two wireless technologies are quite different. Fundamentally, Wi-Fi is just a type of WLAN. Wi-Fi products are used to build WLANs. A WLAN can be built on various wireless technologies.
Wi-Fi is the wireless standard 802.11 and nothing else. Through the years, we've seen different evolutions of Wi-Fi, culminating in the new 802.11ax standard. Each version of the 802.11 standard is written for compatibility with 802.3 Ethernet -- the most common LAN type -- given that Wi-Fi typically extends the edge of the LAN.
- Access Points
Access points (APs) act as Layer 2 bridges between 802.11 and 802.3 standards in enterprise networks. While an access point (AP) can technically involve either a wired or wireless connection, it commonly means a wireless device.
An AP works at the second OSI layer, the Data Link layer, and it can operate either as a bridge connecting a standard wired network to wireless devices or as a router passing data transmissions from one access point to another.
- Wireless Access Points (WAPs)
Wireless access points (WAPs) consist of a transmitter and receiver (transceiver) device used to create a wireless LAN (WLAN).
Access points typically are separate network devices with a built-in antenna, transmitter and adapter. APs use the wireless infrastructure network mode to provide a connection point between WLANs and a wired Ethernet LAN. They also have several ports, giving you a way to expand the network to support additional clients.
- Mutiple Wireless Access Points (APs)
Depending on the size of the network, one or more APs might be required to provide full coverage. Additional APs are used to allow access to more wireless clients and to expand the range of the wireless network.
Each AP is limited by its transmission range -- the distance a client can be from an AP and still obtain a usable signal and data process speed. The actual distance depends on the wireless standard, the obstructions and environmental conditions between the client and the AP. Higher end APs have high-powered antennas, enabling them to extend how far the wireless signal can travel.
APs might also provide many ports that can be used to increase the network’s size, firewall capabilities and Dynamic Host Configuration Protocol (DHCP) service. Therefore, APs cab be served as a switch, DHCP server, router and firewall.
- SSID and Wireless APs
To connect to a wireless AP, you need a service set identifier (SSID) name. 802.11 wireless networks use the SSID to identify all systems belonging to the same network, and client stations must be configured with the SSID to be authenticated to the AP. The AP might broadcast the SSID, allowing all wireless clients in the area to see the AP’s SSID. However, for security reasons, APs can be configured not to broadcast the SSID, which means that an administrator needs to give client systems the SSID instead of allowing it to be discovered automatically. Wireless devices ship with default SSIDs, security settings, channels, passwords and usernames. For security reasons, it is strongly recommended that you change these default settings as soon as possible because many internet sites list the default settings used by manufacturers.
- Fat and Thin APs
Access points can be fat or thin. Fat APs, sometimes still referred to as autonomous APs, need to be manually configured with network and security settings; then they are essentially left alone to serve clients until they can no longer function. Thin APs allow remote configuration using a controller. Since thin clients do not need to be manually configured, they can be easily reconfigured and monitored. Access points can also be controller-based or stand-alone.
