802.11 WLAN (Wireless Local Area Network) allows people to communicate without any networking cables. However, wireless devices on this wireless LAN networking need to communicate with the networking devices on the “wired LANs”.
802.11 standards include 802.11b, 802.11g (both operate in 2.4 GHz band), 802.11a (operates in 5 GHz band), and the 802.11n standards.
Unlike wired networks, WLAN offers some benefits that are apparent – “no wires” and some that you might not have considered. The most obvious is portability. With Wireless LAN Networking, you can surf the Internet by your pool side, your fireplace, or anywhere else in your house with your laptop. Or you can play online game with your XBOX console in the comfort of your living room without the clutter of the wires.
802.11 WLAN Terms and Concepts
An Access Point is a device that typically serves as a bridge or gateway between wireless devices and the devices on a cabled network. An Access Point must be able to receive and forward network traffic between wireless and cabled network devices. Multiple Access Points can act as repeaters to extend the range of a wireless LANA networking (see also Wireless Distribution System –WDS). Connecting via an access point is called Wireless Infrastructure Mode.
The following figure shows a typical 802.11 WLAN diagram deployed in business or enterprise networks. The topology is a wireless LAN networking infrastructure.
Modem with wireless router
Since the Wireless LAN networking becomes so popular today, wireless manufacturers ship the wireless home routers to support the wireless home networking. The following figure shows typical 802.11 WLAN deployed in home or SOHO (small office home office) which includes a Cable modem (such as SurfBoard cable modem) or xDSL modem, and a wireless router. While the computers that connect to the Wireless LAN networking need other wireless network adapters such as wireless USB network adapters or wireless PCI adapters (for desktop computers).
WLAN with AP
The figure below shows a typical wireless access point configured as the repeater in network infrastructure. There are many wireless access points (such as DAP-2590 Air-premier, or DAP-3520 Air-premier access point)) that can operate as the wireless access point, as the wireless point-to-point repeater, and as the wireless repeaters in a point-to-multi point Wireless LAN networking infrastructure.
Ad Hoc (peer-to-peer) mode
Ad-Hoc mode (or peer-to-peer mode) is a wireless topology where wireless devices communicate with each other directly. An Access Point is not used. On Apple networks, Ad Hoc mode is called computer-to-computer mode. Ad Hoc mode is not as reliable as Infrastructure mode, and if used, should be limited to six devices or less.
In the figure below shows simple ad-hoc diagram of two laptops (with notebook wireless adapters) connect to the print-server to print wirelessly. See also Bluetooth printer adapter for sharing the printer.
NOTE:The term “peer-to-peer” in 802.11 WLAN might have a different meaning depending on its usage. While Ad Hoc peer-to-peer mode refers to a wireless network topology, print-server peer-to-peer printing refers to a direct print path from a network computer to a printer. Commonly all the print-servers can be deployed in both Ad-Hoc Wireless LAN networking or in infrastructure wireless topology.
IEEE standards for 802.11 networks specify a spectrum of radio waves for wireless LAN networking communications. The allowed spectrum is divided into channels consisting of 22 MHz each. The number of available channels authorized for use may be restricted based on your location. Typically all the wireless adapters which are configured for infrastructure mode, they will automatically adjust their channel to match the wireless access point.
Wireless networking use radio signals for network communications, which can be easily monitored by someone eavesdropping on the network. To deter eavesdropping and to help ensure data privacy, encryption of wireless communications may be used. The latest industrial standard in wireless security is the Wi-Fi Protected Access (WPA/WPA2).
NOTE:Wireless performance may be reduced when using encryption keys due to the additional processing time required.
In the WLAN, the range over which wireless devices can communicate depends on the physical environment and the orientation of the wireless access point. For typical 802.11g standard, the wireless coverage ideally can range up to 300 feet. With the wireless –N standards and enhanced technology such as MIMO antenna technology, the wireless coverage can be 4x as long as the 802.11g standards.
NOTE: Signal range and wireless transmission performance is reduced with increasing distance between devices, and with obstacles that block or absorb signals.