articles for telecom engineers

When someone with some experience using wireless networks hears the term called Wireless LAN, the first thing that comes to his / her mind is IEEE (International
Electrical and Electronics Engineers) 802.11 or Wifi. In reality we can assume that this technology has started when the first Wireless LAN standard was accepted by 802.11 commitee. It is qu­ite hard to believe but Wireless LAN speed has inc­reased 150 times since it was first introduced, reac­hing up to 300 Mbps from 2 Mbps.

In fact 802.11 is a generic name for family of wi­reless LAN standards. The numbering comes from IEEE’s 802 group who is specialized in many net­working standards including Ethernet. First wireless LAN standard was ratified in 1997, supporting 1 and 2 Mbps rates. Right after the ratification, many com­panies has started manufacturing Wireless LAN devi­ces.
Wireless LANs popularity and penetration rate increased rapidly after the ratification of 802.11 b standard. That technology operated at free to use 2.4 GHz frequency band and reached up to 11 Mbps ra­te. 802.11 b was so successful devices from various technology providers were compatible and operated flawlessly with each other. Many companies provi­ded WLAN cards, volumes were very high. Thus, 802.11 b WLAN devices were available to customers at very reasonable prices ($20 - $30 for a WLAN card). 802.11b was the first WLAN technology that got integrated in to some laptop computers. When a user bought a laptop with WLAN feature, he/she co­uld easily connect to a local network or internet wire­lessly if a WLAN is available.
While the penetration of WLAN devices was inc­reasing, companies and 802.11 standards committee continued working on a faster technology. 802.11a technology, reaching up to 54 Mbps, was ratified short time after 802.11 b. Unfortunately, since 802.11 a was operating at 5 GHz frequency band, it was not backward compatible to 802.11 b, had higher cost and lower wireless coverage. Because of those disadvantages, 802.11 a never hit mainstream WLAN market.

Because of the need for faster wireless speeds and failure of 802.11 a standard, IEEE started working on a faster technology which will be backward compatible to 802.11 b. 802.11g standard which is operating at 2.4 GHz, reaching up to 54 Mbps and back­ward compatible with 802.11 b was ratified in year 2003. Because of its higher speed and lack of disadvantages against 802.11 b, it started replacing 802.11 b market very quickly. In less than a year 802.11 b was phased out and 802.11g became the number 1 WLAN technology.
As the speed of wireless LANs increased, the need for higher speed increased also. Today 802.11n standard which can reach up to 300 Mbps is coming up. It uses a technology called MIMO (Multiple Input Multiple Output) which provides higher rates and better wireless coverage. 802.11n did not repeat the mistake that 802.11a has made. 802.11n is backwards compatible to both 802.11g and 802.11 b operating at 2.4GHz and also 802.11a ope­rating at 5 GHz. That way user who already has older devices did
_ not hesitate to introduce 802.11n to their network since they can still use their previous computers with older WLAN technology without loosing any performance. In a mixed WLAN, while 802.11n compatible devices operated at higher speed, 802.11g!b or 802.11 a devices can still operate as before. As 802.11 n is ex­pected to be ratified towards the end of 2007, there are many 802.11n draft 1.0 or draft 2.0 compatible devices in the market. Even the real performance of those devices are lower than expec­ted, the companies claim that pre-802.11n products will be 802.11n compatible with a software upgrade when 802.11n is ra­tified. Even today, there are laptop computers are available with 802.11n integrated as a standard feature. Similar to 802.11 g pha­sing out 802.11b technology, as the prices come down, 802.11n will phase 802.11g out and in less than a year and 802.11g pro­duction will seize. Higher speed technologies are always prefer­red by the end users even if they do not need it for the time being.
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