Jenny asks…
tell me the abstract of Wi-Fi technology in detail?
Contributor via RSS answers:
Wi-Fi was originally a brand licensed by the Wi-Fi Alliance to describe the embedded technology of wireless local area networks (WLAN) based on the IEEE 802.11 standard. As of 2007, common use of the term Wi-Fi has broadened to describe the generic wireless interface of mobile computing devices, such as laptops in LANs.[citation needed] The term Wi-Fi was chosen as a play on the term “Hi-Fi”, and is often thought to be an abbreviation for wireless fidelity. Wi-Fi and the Wi-Fi CERTIFIED logo are registered trademarks of the Wi-Fi Alliance, the trade organization that tests and certifies equipment compliance with the 802.11x standards.
Common uses for Wi-Fi include Internet and VoIP phone access, gaming, and network connectivity for consumer electronics such as televisions, DVD players, and digital cameras. In spite of media reports about possible health risks from Wi-Fi, scientific studies have failed to show a causal effect.
Technical information
Main article: Wi-Fi Technical Information
Wi-Fi networks use radio technologies called IEEE 802.11. These technologies have gone through several generations since their inception in 1997. Wi-Fi is supported to different extents under Microsoft Windows, Apple Mac OS and open source Unix and Linux operating systems.
[edit] Uses
A person with a Wi-Fi enabled device such as a PC, cell phone or PDA can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot. Hotspots can range from a single room to many square miles of overlapping hotspots. Wi-Fi can also be used to create a mesh network. Both architectures are used in community networks.[citation needed]
Wi-Fi also allows connectivity in peer-to-peer (wireless ad-hoc network) mode, which enables devices to connect directly with each other. This connectivity mode is useful in consumer electronics and gaming applications.
When the technology was first commercialized there were many problems because consumers could not be sure that products from different vendors would work together. The Wi-Fi Alliance began as a community to solve this issue so as to address the needs of the end user and allow the technology to mature. The Alliance created the branding Wi-Fi CERTIFIED to show consumers that products are interoperable with other products displaying the same branding.
Home Wi-Fi clients come in many shapes and sizes, from stationary PCs to digital cameras. The trend as of 2007 is to incorporate wireless into every electronic where mobility is desired.[citation needed]
Wi-Fi devices in home or consumer-type environments can connect via a broadband Internet connection into a single router which can serve both wired and wireless clients. They can also use ad-hoc mode for client to client connections, and be built into non-computer devices to enable wireless connectivity to the Internet.
Business and industrial Wi-Fi has become ubiquitous as of 2007. In business environments, increasing the number of Wi-Fi access points provides redundancy, support for fast roaming and increase overall network capacity by using more channels or creating smaller cells. Wi-Fi enables wireless voice applications (VoWLAN or WVOIP). Over the years, Wi-Fi implementations have moved toward ‘thin’ access points, with more of the network intelligence housed in a centralized network appliance, relegating individual Access Points to be simply ‘dumb’ radios. Outdoor applications may utilize true mesh topologies. As of 2007, Wi-Fi installations can provide a proactive, self-managed network that functions as a security gateway, firewall, DHCP server, intrusion detection system, and a myriad of other features not previously considered relevant to a wireless network.[citation needed]
The most publicly visible use of Wi-Fi is at hotspots, including:
Free Wi-Fi at venues like Panera Bread, It’s a Grind Coffee House, select hotels, and over 100,000 locations in the USA has been growing in popularity. According to a door-to-door survey in San Jose, CA, the number of venues and users is growing fast.[citation needed]
Paid Wi-Fi at venues like Starbucks, McDonalds, and at hotels. This trend is growing rapidly at venues that require a higher rate of customer churn, such as sit-down restaurants.[citation needed]
Metropolitan-wide WiFi (Mu-Fi) already has more than 300 projects in process.[3]
[edit] Advantages of Wi-Fi
Wi-Fi allows LANs to be deployed without cabling for client devices, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.
As of 2007 wireless network adapters are built into most modern laptops. Getting a laptop without a built in WiFi has now become an exception. Wi-Fi chipset pricing continues to come down, making Wi-Fi a very economical networking option and driving inclusion of Wi-Fi in an ever-widening array of devices. Wi-Fi products are widely available in the market.
Different competitive brands of access points and client network interfaces are inter-operable at a basic level of service. Products designated as “Wi-Fi Certified” by the Wi-Fi Alliance are backwards inter-operable. Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi client works in different countries around the world.
Widely available in more than 250,000 public hot spots and tens of millions of homes and corporate and university campuses worldwide, as of 2007, Wi-Fi has become the preferred method of network connectivity.[citation needed] WPA is not easily cracked if strong passwords are used and WPA2 encryption has no known weaknesses. New protocols for Quality of Service (WMM) and power saving mechanisms (WMM Power Save) make Wi-Fi even more suitable for latency-sensitive applications (such as voice and video) and small form-factor.
[edit] Disadvantages of Wi-Fi
Spectrum assignments and operational limitations are not consistent worldwide. Most of Europe allows for an additional 2 channels beyond those permitted in the US (1-13 vs 1-11); Japan has one more on top of that (1-14), and some countries, like Spain, prohibited use of the lower-numbered channels. Europe, as of 2007, is now essentially homogeneous in this respect. Furthermore some countries, such as Italy, used to require a ‘general authorization’ for any Wi-Fi used outside an operator’s own premises, or require something akin to an operator registration.[citation needed] Equivalent isotropically radiated power (EIRP) in the EU is limited to 20 dBm (0.1 W).
Power consumption is fairly high compared to some other low bandwidth standards, such as Zigbee and Bluetooth, making battery life a concern.
The most common wireless encryption standard, Wired Equivalent Privacy or WEP, has been shown to be easily breakable even when correctly configured. Wi-Fi Protected Access (WPA and WPA2) which began shipping in 2003 aims to solve this problem and is now available on most products. Wi-Fi Access Points typically default to an open (encryption-free) mode. Novice users benefit from a zero configuration device that works out of the box but without security enabled providing open wireless access to their LAN. To turn security on requires the user to configure the device, usually via a software graphical user interface (GUI). Wi-Fi networks that are open (unencrypted) can be monitored and used to read and copy data (including personal information) transmitted over the network unless another security method is used to secure the data like a VPN or a secure web page. (HTTPS/Secure Socket Layer)
Many 2.4 GHz 802.11b and 802.11g Access points default to the same channel on initial start up, contributing to congestion on certain channels. To change the channel of operation for an access point requires the user to configure the device.
Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g with a stock antenna might have a range of 45 m (150 ft) indoors and 90 m (300 ft) outdoors. Range also varies with frequency band. Wi-Fi in the 2.4 GHz frequency block has slightly better range than Wi-Fi in the 5 GHz frequency block. Outdoor range with improved antennas can be several kilometres or more with line-of-sight.
Wi-Fi pollution, of an excessive number of an access point with other access points in the area, especially on the same or neighboring channel, can prevent access and interfere with the use of other access points by others caused by overlapping channels in the 802.11g/b spectrum as well as with decreased signal-to-noise ratio (SNR) between access points. This can be a problem in high-density areas such as large apartment complexes or office buildings with many Wi-Fi access points. Additionally, other devices use the 2.4 GHz band: microwave ovens, cordless phones, baby monitors, security cameras, and Bluetooth devices can cause significant additional interference.
It is also an issue when municipalities[4] or other large entities such as universities seek to provide large area coverage. Everyone is considered equal for the base standard without 802.11e/WMM when they use the band. This openness is also important to the success and widespread use of 2.4 GHz Wi-Fi, but makes it unsuitable for “must have” public service functions or where reliability is required. Users sometimes suffer network “frustrations” or a total network breakdown if gaming because a neighbour microwaves some popcorn.
Interoperability issues between brands or proprietary deviations from the standard can disrupt connections or lower throughput speeds on other user’s devices that are within range. Additionally, Wi-Fi devices do not, as of 2007, pick channels to avoid interference
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