Archive for the ‘Network’ Category


December 8, 2010 1 comment

Wi-Fi and WiMAX are two of the most popular technologies that provide wireless high speed broadband connection, with different characteristics. Both technologies are known in IEEE as the standards 802.11 and 802.16 respectively.


Wi-Fi was created in 1991 in Norway and was originally used with commercial cash register systems it is a wireless local area network which represents the standard IEEE 802.11, the name Wi-Fi is short for “Wireless Fidelity. Wi-Fi connection can provide a high speed connection up to 11 Mbps or greater if the computer used is in range of 20m-50m from the access point indoors or couple of hundered meters outdoors (without noise like walls). Wifi transmits internet connection through electromagnetic waves reserving two layers from the OSI Layers which are the physical layer and the data link layer.
Wi-Fi can also connect DVD’s to TV’s and it is not only valid for internet connections yet it is most commonly used with internet connections.

Wi-Fi has various known standards with different specifications:

  • The 802.11a called Wifi5 allows high bandwidth up to 54 Mbps/30 in practice and it offers 8 radio channels in the 5 GHz frequency band.
  • The 802.11b is the most populer one it provides a connection speed up to 11 Mbps/6 in practice and is reachable in a 300 meters area outdoors. It offers 3 radio channels in 2.4 Ghz frequency range.
  • The 802.11g offers a high bandwidth like the 802.11a (54 Mbps/30 in practice) on the 2.4 Ghz frequency range, also it has a backward compatibility with the 802.11b.
  • The 802.11n provides a very high bandwidth between 54 Mbps up to 600 Mbps with a frequency range of 40 MHz


WiMAX was created in 2002 by Intel and Alvarion and is known as the standard 802.16 by the IEEE. It is short for Worldwide Interoperability for Microwave Access. Its most important characteristic is to provide a connection speed up to 70 Mbps in the range of 50 kilometers. WiMAX technology supports the Quality Of Service (QOS) which ensures that the service will work as long as it is used in practice. WiMAX has an advantage of other wireless connections that it can server thousands of users without being in a direct line-of-sight which is known as (LOS) and this technique is called NLOS which stands for none-line-of-sight, but WiMAX connection speed could be reduced to 20 Mbps if there are obstructions like trees or houses and it won’t be even transmitted if there are obstructions like buildings and mountains.
The BTS (base transceiver station) is the heart of the WiMAX which is an antenna that communicates with the users antennas and this way of communication is called the Point Multipoint link.

WiMAX is divided into two categories, the Fixed WiMAX and the Mobile WiMAX:

  • Fixed WiMAX (IEEE 802.16-2004): needs an antenna at the rooftop like the TV antenna to provide a fixed-line connection and it operates at three frequencies:
  1. 2.5 GHz (requires license to operate).
  2. 3.5 GHz  (requires license to operate)
  3. 5.8 GHz (free license)
  • Mobile WiMAX (IEEE 802.16e): mobile client machines can be connected to the internet using this technique and also it facilitates the use of mobile phone over IP as well as high speed mobile services.

One thing to mention is that the fixed WiMAX can be spread on a radius of 10 km with a connection up to 75 Mbps while the other category (Mobile WiMAX) can be spread on 3.5 km with a speed up to 30 Mbps.
WiMAX also is said to be used in future to link to Wi-Fi hotspots using WiMAX technology. And also to cover areas which wired connections like DSL won’t be able to cover.
WiMAX as Wi-Fi technology have different standards such as: 802.16, 802.16a, 802.16b 802.16c, etc…

Wi-Fi and WiMAX are both:

  • Wireless broadband connections.
  • Useful for Voice over IP (VoIP)
  • Registered as standards in the IEEE
  • Can be used indoors.
  • Have many sub standards.

The main differences between Wi-Fi and WiMAX are:

Difference Issue Wi-Fi (802.11) WiMax (802.16)
Cost Cheap Expensive
Application In-Building, Enterprise Service Provider à carrier class
Range Tens of meters (maximum 300 meters) 7-10 km in practice and up to 50 km
Range speed Almost same speed for the whole covered range Handles users spread out over several kms
Number of users Tens of users Thousands of users
Coverage Best for indoor connection Optimized for outdoor connection. Adaptive modulation, Advanced Antenna
Brands License exempt License and License exempt bands. Also allows Cell Planning
Channels Fixed 20 MHz channel 1.5 à 20 MHz (the operator can choose the size)
Special efficiency 2-7 bps/Hz à 54 Mbps in 20 MHz 3.8 bps/Hz à 75 Mbps in 20 MHz5 bps/Hz à 100 Mbps in 20 MHz
Delay speed Designed to handle indoor multipath delay speed of 0.8\ms Designed for longer multipaths.Multipath delay speed of 10\ms
Duplexing TDD only – Asymmetric TDD/FDD/HFDD – symmetric or asymmetric
MAC Contention Based, Distributed control Grant Based, Centralized control
QoS No delay or throughput guarantees Guarantees QoS
User Differentiation All users will receive same service Different users on different distance scales will receive different levels of service. TI for business, best for residential
Security WEP, WPA and WPA2 128-bit 3DES and 1024-bit RSA

So, as we can see from the table of differences above there is many differences between the two technologies regarding the price, connection speed, coverage and service. But although most of the differences will give the big spot for WiMAX (except the cost issue), still most analysis says that in the near future the most dominant technology of wireless internet will still be the Wi-Fi since it is more stable and easier for use, and most important thing is that the coffee places, beaches, universities and many more places won’t be able or won’t find it feasible to use WiMAX technique since the Wi-Fi will do the job they want 100%, since these places are small areas.