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Wireless local area networks (WLANs) have three main types 802.11 a/g/n, n being the latest technology. These wireless networks have been implemented nearly everywhere including home and work. The figure below found through google.com images shows a basic home or small office set up.
802.11a wireless LAN is a standard that provides up to 54 Mbps in the 5GHz band. It provides 20 MHz of bandwidth and has an indoor range of 35 meters. This version was also the most costly of all the standards but is now becoming old technology.
802.11g WLAN standard that provides 54 Mbps in the 2.4 GHz band. It has a slightly increased indoor range of 38 meters and also provides 20 MHz of bandwidth. This standard is most used today for its performance and price.
802.11n Wireless standard that provides upwards up 100 Mbps in either the 2.4 or 5 GHz band. It's bandwidth is 20 or 40 MHz. This standard also provides the largest indoor range of 70 meters. The newest technology for wireless networking is the 802.11n standard and is what most are currently upgrading to.
With WLAN signal interference becomes a large issue when transferring data. 802.11 standards use over-the-air modulation techniques to decrease interference with other signals. Direct-sequence spread spectrum (DSSS) and orthogonal frequency-division multiplexing (OFDM) signaling methods are what help minimize these problems.
802.11 is the wireless protocol series of standardization created by the IEEE (Institute of Electrical and Electronic Engineers). 802.11 is specific to standards dealing with wireless networking. All net working technologies, WAN, LAN, or WLAN, are standardized with the number 802. Farther more, there are four different types of Wireless local area networks that are broken down to a,b,g and n. These standardizations of wireless protocols help to inform consumers and match technologies, although things like laptops have cards that are compatible with many of the standards. Only a,g and n wireless local access network standards will be discussed in detail.
The IEEE implemented the 802.11a amendment to the original standard in 1999. It the oldest of the three standards so it is the least cutting-edge and is more expensive compared to the other contemporary technologies like 802.11g/n or Bluetooth. Another characteristic to note of the 802.11a standard is that is range is short because the propagation distance will decrease with a higher radio frequency of 5GHz. Operatering in the 5Â GHz frequency makes it less crowded and hence has a relatively smaller interference problem. It also, uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) with a maximum raw data rate of 54 Mbps. 802.11a has 12 channels. This is important because a larger number of users can be accommodated with no performance degradation with more channels. 802.11stadards are not compatible except if using equipment that has a dual band capability (laptop/ Ipod ect.). Most routers have multiple band capability so that they support all 802.11 standards. Not many consumer products use 802.11 because many use the newer technologies, these devices include smart phones and PDAs. These are likely to be supported by either 802.11g or Bluetooth standards.
802.11g is the most widely used variation of the 802.11 wireless LANs. It works in the 2.4 GHz band, but operates at a maximum raw data rate of 54 Mbps. Since 802.11g is used so much by consumer products, the 2.4GHz band can be noisy with interference. 802.11g is very close to the 802.11a network, except for a few backward compatibility features. The indoor range is alos comparible to that of 802.11a standard. Also, like 802.11a it also uses a 52-subcarrier orthogonal frequency-division multiplexing (OFDM) with a maximum raw data rate of 54 Mbps. Even though 802.11g operates in the frequency 2.4 GHz band it achieves the same data. Another good thing that comes about from the use of the 2.4 GHz band is that the wireless 802.11g technology is cheap comparitively.
The newest wireless network technology is the 802.11n. The IEEE have been revising for years and is still not finalized. Though it is not finalized many consumer products can be found. The 802.11n standard is well on its way to replacing 802.11g, as soon as support and price are comparable. Wireless N uses a technology known in the industry as MIMO. This stands for multiple input, multiple output. Instead of a device having a single antenna, it has multiple antennae that are arranged so as to have maximum transmitting power, and maximum reception. This greatly increases range (while using the 2.4GHz frequency band) and speed. Wireless 802.11n has speeds that exceed 100 Mbps which is far greated than the 802.11a/g standards. 802.11n devices can operate on 2.4 or 5GHz bands. It is important to note that to use 5GHz frequency all connected devices must be 802.11n compliant. Like the 802.11a it has less trouble with interference while operating in the 5 GHz frequency band.
802.11a/g/n Wireless networking at a glance.
Most wireless networking hardware vendors support all the 802.11 standards so that they can inter-operate.
Vendors Include: Belkin, Cisco, D-Link, Hawking Technologies, IOGear, KTI Networks, Netgear, SMC Networks, TrenDnet, Zonet.
Sample Pricing for various Models (Newegg)
Linksys WRT54GL 802.11b/g Wireless Broadband Router up to 54Mbps
D-Link DIR-655 802.11b/g/n Xtreme N Gigabit Wireless Broadband Router up to 300Mbps
NETGEAR WGR614 802.11b/g Wireless-G Broadband Router up to 54Mbps
802.11 Wireless has made its way into every aspect of our lives. It is seen at home and at the work place. Most every company has wireless access to stay connected and competitive. This can be seen in office building and chain stores. For robust machine shops and automated manufacturing plants, wireless technology provides excellent solutions to the problem of the high cost of industrial wiring and also provides an ultimate barrier to electrical surges introduced to field equipment through field wiring. This also allows for remote monitoring of the plants productivity and status. The flip side to these wireless advantages is the difficulty of supplying power to field devices, which previously were powered from the same cable used to conduct the data exchange between the field device and a host system.
Stanford, Michael (September 7, 2007). "How does 802.11n get to 600Mbps?". Wirevolution.
IEEE 802.11n-2009-Amendment 5: Enhancements for Higher Throughput. IEEE-SA. 29 October 2009.
Â The IEEE 802.11 Standard: www.pulsewan.com/data101/802_11_b_basics.htm
Wireless Networking: www.vicomsoft.com/knowledge/reference/wireless1.html
"802.11a-1999 High-speed Physical Layer in the 5 GHz band" (pdf). 1999-02-11. Retrieved 2007-09-24.
Computer Networks: Planning, Design, Implementation