Standard DevicesWireless Access Point (WAP)A wireless access point connects a group of wireless devices to an adjacent wired LAN. An access point is similar to an ethernet hub, relaying data between connected wireless devices in addition to a (usually) single connected wired device, most often an ethernet hub or switch, allowing wireless devices to communicate with other wired devices. Wireless AdapterA wireless adapter allows a device to connect to a wireless network. These adapters connect to devices using various interconnects such as PCI, miniPCI, USB, ExpressCard, Cardbus and PC card. Wireless RouterA wireless routerr integrates a WAP, ethernet switch, and internal Router firmware application that provides IP Routing, NAT, and DNS forwarding through an integrated WAN interface. A wireless router allows wired and wireless ethernet LAN devices to connect to a (usually) single WAN device such as cable modem or DSL modem. A wireless router allows all three devices (mainly the access point and router) to be configured through one central utility. This utility is most usually an integrated web server which serves web pages to wired and wireless LAN clients and often optionally to WAN clients. This utility may also be an application that is run on a desktop computer such as Apple's AirPort. Wireless Ethernet BridgeA wireless Ethernet bridgee connects a wired network to a wireless network. This is different from an access point in the sense that an access point connects wireless devices to a wired network at the data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes. Range ExtenderA wireless range extender or wireless repeater can extend the range of an existing wireless network. Range extenders can be strategically placed to elongate a signal area or allow for the signal area to reach around barriers such as those created in L-shaped corridors. Wireless devices connected through repeaters will suffer from an increased latency for each hop. Additionally, a wireless device at the end of chain of wireless repeaters will have a throughput that is limited by the weakest link within the repeater chain. Antenna connectorsMost commercial devices (routers, access points, bridges, repeaters) designed for home or business environments use either RP-SMA or RP-TNC antenna connectors. PCI wireless adapters also mainly use RP-SMA connectors. Most PC card and USB wireless only have internal antennas etched on their printed circuit board while some have MMCX connector or MC-Card external connections in addition to an internal antenna. A few USB cards have a RP-SMA connector. Most Mini PCI wireless cards utilize Hirose U.FL connectors, but cards found in various wireless appliances contain all of the connectors listed. Many high-gain (and homebuilt antennas) utilize the Type N connector more commonly used by other radio communications methods. Non-Standard DevicesDIY Range OptimizationsUSB-Wi-Fi adapters, food container "Cantennas", parabolic reflectors, and many other types of self-built antennae are increasingly made by do-it-yourselvers. For minimal budgets, as low as a few dollars, signal strength and range can be improved dramatically. There is also a type of optimization by polarizing the signal to achieve a planar coverage like a plate. Many of these high-gain aftermarket modifications are technically illegal under FCC and other regulatory guidelines. Long Range Wi-Fi
Recently, long range Wi-Fi kits have begun to enter the market. Companies like RadioLabs and BroadbandXpress offer long range, inexpensive kits that can be setup with limited knowledge. These kits utilize specialized antennas which increase the range of Wi-Fi dramatically, in the case of the world record 137.2 miles (220km). These kits are commonly used to get Broadband internet to a place that cannot access the service itself.[4] The longest link ever achieved was by the Swedish space agency. They attained 310 km, but used 6 watt amplifiers to reach an overhead stratospheric balloon. The longest link without amplification was 279 km in Venezuela, 2006 Read PDF by www.eslared.org Wi-Fi and its support by operating systemsThere are two sides to Wi-Fi support under an operating system: driver level support, and configuration and management support. Driver support is usually provided by the manufacturer of the hardware or, in the case of Unix clones such as Linux and FreeBSD, sometimes through open source projects. Configuration and management support consists of software to enumerate, join, and check the status of available Wi-Fi networks. This also includes support for various encryption methods. These systems are often provided by the operating system backed by a standard driver model. In most cases, drivers emulate an ethernet device and use the configuration and management utilities built into the operating system. In cases where built in configuration and management support is non-existent or inadequate, hardware manufacturers may include their own software to handle the respective tasks. Microsoft WindowsMicrosoft Windows has comprehensive driver-level support for Wi-Fi, the quality of which depends on the hardware manufacturer. Hardware manufactures almost always ship Windows drivers with their products. Windows ships with very few Wi-Fi drivers and depends on the original equipment manufacturers (OEMs)and device manufacturers to make sure users get drivers. Configuration and management depend on the version of Windows.
Apple Mac OSApple was an early adopter of Wi-Fi, introducing its AirPort product line, based on the 802.11b standard, in July 1999. Apple then introduced AirPort Extreme as an implementation of 802.11g. All Macs starting with the original iBook included AirPort slots for which an AirPort card can be used, connecting to the computer's internal antenna. All Intel-based Macs either come with built-in Airport Extreme or a slot for an AirPort card. In late 2006, Apple began shipping Macs with Broadcom Wi-Fi chips that also supported the Draft 802.11n standard which can be unlocked through buying a $2 driver released by Apple at the January 2007 Macworld Expo. The driver is also included for free with Apple's 802.11n AirPort Extreme. Apple makes the Mac OS operating system, the computer hardware, the accompanying drivers, AirPort WiFi base stations, and configuration and management software, simplifying Wi-Fi integration. The built-in configuration and management is integrated throughout many of the operating system's applications and utilities. Mac OS X has Wi-Fi support, including WPA2, and ships with drivers for Apple’s Broadcom-based AirPort cards. Many third-party manufacturers make compatible hardware along with the appropriate drivers which work with Mac OS X’s built-in configuration and management software. Other manufacturers distribute their own software. Apple's older Mac OS 9 does not have built in support for Wi-Fi configuration and management nor does it ship with Wi-Fi drivers, but Apple provides free drivers and configuration and management software for their AirPort cards for OS 9, as do a few other manufacturers. Versions of Mac OS before OS 9 predate Wi-Fi and do not have any Wi-Fi support, although some third-party hardware manufacturers have made drivers and connection software that allows earlier OSes to use Wi-Fi.[5] Open source Unix-like systemsLinux, FreeBSD and similar Unix-like clones have much coarser support for Wi-Fi. Due to the open source nature of these operating systems, many different standards have been developed for configuring and managing Wi-Fi devices. The open source nature also fosters open source drivers which have enabled many third party and proprietary devices to work under these operating systems. See Comparison of Open Source Wireless Drivers for more information on those drivers.
Embedded systemsWi-Fi availability in the home is on the increase. This extension of the Internet into the home space will increasingly be used for remote monitoring. Examples of remote monitoring include security systems and tele-medicine. In all these kinds of implementation, if the Wi-Fi provision is provided using a system running one of operating systems mentioned above, then it becomes unfeasible due to weight, power consumption and cost issues. Increasingly in the last few years (particularly as of early 2007), embedded Wi-Fi modules have become available which come with a real-time operating system and provide a simple means of wireless enabling any device which has and communicates via a serial port. This allows simple monitoring devices, for example a portable ecg monitor hooked up to a patient in the home, to be created. This Wi-Fi enabled device effectively becomes part of the internet cloud and can communicate with any other node on the internet. The data collected can hop via the home's Wi-Fi access point to anywhere on the internet. These Wi-Fi modules are designed so that minimal Wi-Fi knowledge is required by designers to wireless enable their product.
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