What is WiMAX and How Does it Differ from WiFi?

By | June 6, 2016

When speaking about wireless networks, you might have heard the term WiMAX increasingly used as a technology that will replace WiFi. If you are curious on what the differences between these two are, then this article is meant to exactly answer your questions.

WiMAX stands for “Worldwide Interoperability for Microwave Access” and is a standard-based technology for providing a wireless alternative to cable and DSL connections.

This however is also one of the usages of WiFi. Although WiFi wireless devices are mainly used for short-range wireless connection of end user devices such as laptops, tablets and smartphones, they are also used for site-to-site interconnections.

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Before I explain the core difference of the two, let’s first take a look at the table below which gives some of the basic differences between the two wireless standards:

Specifications WiMAX WiFi
IEEE Standard 802.16x 802.11x
Versions of standard 802.16a, 802.16d and 802.16e 802.11b, 802.11g, 802.11n
Official Release 1997 2004
Frequency bands supported 2.5,3.5 and 5.8GHz supported 2.4 GHz and 5 GHz supported
Data rate 30-40Mbps, but lately updated to 1Gbps 54Mbps, but lately up to 1.2Gbps
Channel Bandwidth Flexible (1.25 to 20 MHz) 10 or 20 or 40 MHz
Normal Ranges 30+ Km 100m for end-user devices (up to 5Km for outdoor point to point connections)

What is the main technical benefit of WiMAX?

WiMAX is not a replacement technology to WiFi – instead, while WiFi is the de-facto global standard for wireless interconnection of end-user devices, WiMAX has addressed a specific technical deficiency of WiFi for interconnection of multiple sites.

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The main drawback of WiFi technology for a point-to-multipoint connection is that it is a connectionless type of protocol named CSMA/CA (Carrier sense multiple access with collision avoidance). Without going into deep technical details, this means that as in WiFi networks all the devices of the network share the same frequency channel, to prevent collision in data transmissions, each device “listens” to make sure no other device is transmitting and then it transmits its data. I.e. there is no centralized management in the network. While this makes the network setup very simple and straightforward (which is a benefit for end-user devices), it creates major problems in larger networks especially when the distances are increased.

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WiMAX has mainly addressed this issue by adopting a fully connection-based protocol, which uses a scheduling algorithm. Unlike a WiFi network, in WiMAX you should define and setup each subscriber station (SS) on the base station including specifying what bandwidth each SS should be given. By doing this, the base station knows the exact number of subscriber stations and allocates a time slot (access slot) to each. This protocol synchronizes the transmission of data between all the stations on the network and totally eliminates the collision issues of a WiFi network. This enables efficient and reliable connection of as many as 80 subscribers on a WiMAX network with guaranteed QoS (Quality of Service), while on an outdoor WiFi network, adding more than 10 CPEs would cause great deficiency with unpredictable quality of service.

To give an example, WiFi is like a crossroad with no traffic light where cars need to check and make sure no-one else is crossing before moving on, while WiMAX is when you have a traffic police (the base station) giving turn to each car to pass.

Conclusion

While WiFi is and will be widely used for short-range wireless connection of end-user devices, WiMAX is the correct, efficient wireless solution for long-range connection of multiple sites such as providing internet connection to multiple homes or interconnection of multiple buildings in a large compound.

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