WiMAX 5.8Ghz vs Wi-Fi 5.8Ghz in Backhaul and Access Technologies

In today's wireless market, there are numerous  5.8Ghz Wi-Fi based products. Now wireless equipment vendors are releasing 5.8Ghz versions of their WiMAX products. It's tempting for small/medium ISP, businesses and governments to look at the new product offerings, but is it worth the switch to WiMAX from widely used Wi-Fi based products?

What is Wi-Fi and WiMax?

When comparing technologies for deployment applications, defining exactly what we are looking at is a good place to start.

Wi-Fi Definition:
Wi-Fi (pronounced /ˈwaɪfaɪ/) is a trademark of the Wi-Fi Alliance used with certified products that belong to a class of wireless local area network (WLAN) devices based on the IEEE 802.11 standards.

Because of the close relationship with its underlying standard, the term Wi-Fi is often used as a synonym for IEEE 802.11 technology, including the 802.11a/802.11b/802.11g standards.

WiMAX Definition:
WiMAX, means Worldwide Interoperability for Microwave Access.

It is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile Internet access.

The technology provides up to 10 Mbps broadband speed without the need for cables.

It is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard.

WiMAX and Wi-Fii standards

Standard	Family	Use	Radio/RF	Down Link	Uplink
Wi-Fi	802.11a/b/g (11n)	Fixed Internet/Fixed Data services	OFDM/MIMO TDD	288.9 Can support 600Mbps @ 40MHz channels
WiMAX	802.16d 802.16e  (802.16m developmental)	Fixed/Mobile Internet/Data services	OFDMA MIMO-SOFDMA TDD and FDD	144	35

As we can see from the standards information, there are distinct differences in both the WiMAX and Wi-Fi technologies and their possible applications.

Can 5.8GHz WiMAX can compete with 5.8GHz Wi-Fi for a Point to Point application?

For point to point applications, 5.8 Wi-Fi works fairly well and is widely used in Australia.

The main advantage in the WiMAX standard for PTP networks is FDD (full duplex communications) and QoS features. But, in many instances, it is difficult for point to point WiMAX to compete with 802.11 Wi-Fi in point to point systems. Wi-Fi has a better overall data-rate then WiMAX.

In the future, the 802.16m stardard for WiMAX will give point to point systems a better advantage over Wi-Fi point to point systems, offering rates at least 4x the current 802.16e rates.

5.8GHz Point to Multi-Point - WiMAX or Wi-Fi?

The WiMAX standard has many advantages over 802.11 Wi-Fi products in point to multipoint applications.

The hidden node effect is the biggest problem for Wi-Fi networks.

Hidden nodes in a wireless network refer to nodes that are out of range of other nodes or a collection of nodes.

Take a physical star topology with an access point and many nodes surrounding it in a circular fashion. Each node is within communication range of the AP, but some nodes may not be able to communicate with each other, as they do not have a physical connection to each other, thus producing a situation where nodes can not sense the carrier on the network.

Carrier sense multiple access with collision avoidance (CSMA/CA) does not work and collisions occur, scrambling data.

The Wi-Fi RF timing is less robust for long range transmissions and systems that have fixed the Wi-Fi timing problems risk incompatibility problems with the 802.11 standards. There are different versions of 802.11 from vendors including Alverion, Airaya and Skypilot. These companies use products with modified 802.11, but they only work with their own client subscriber units.

WiMAX wins hands down, and was designed to fix shortfalls in the Wi-Fi standard.

I have tried deploying larger Wi-Fi last mile access networks in the past and experienced a lot of problems.

I have never had a problem with WiMAX network deployments and reliability in access networks.