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OK, Heres the Scoop on WiMAX

By Peter Radizeski, RAD-INFO

It happened again today. People asking when WiMax will be rolled out to solve all of their problems. I had to explain what WiMax is. So here it is:

802.11 is a family of specs (a, b, g, n, s) for wireless LAN from the IEEE standards body. While Wi-Fi and 802.11 are used interchangeably, especially in the media, they are not. Wi-Fi is actually a brand owned by the Wi-Fi Alliance. It has come to be associated with 802.11b/g networks.

802.16 is an IEEE standard for wireless MAN (metro area networks). There are many flavors of 802.16.

WIMAX is the Worldwide Interoperability for Microwave Access. WiMax is about using various vendor parts (best of breed) to create your metro network.

That means that you can use an antenna from one company with a radio from another company and CPE/modem/card from another. So far these three manufacturers are approved by the WiMax Forum on some gear: Redline Communications, Aperto Networks and Sequans Communications.

WiMax is not a standard, but is based on 802.16. Mobile WiMax is based on

802.16e-2005 and has the most hype. (How much of the hype will become a reality is beyond me, because physics still applies. In other words, you can only push so much data or bandwidth through a sector of radio spectrum. Period.)

An example using the WLAN spectrum: one channel of 2.4GHz spectrum using 802.11g will only result in about 30MB of throughput, 19MB if it is 11b backward compatible. The 108MB advertised for the various blue boxes is theoretical and requires the use of two channels – one for transmit, one for receive. One channel of spectrum tops out at 54MB per antenna (half-duplex). Factors that will affect the throughput are packet size, MTU, headers, and overhead. Also, server speed will affect how much data can reply to the remote request.

To add to the confusion, the cellcos are working on 3G and 4G networks.

Using 3G or EVDO or EDGE or 3GPP or LTE. 3G refers to the third generation of the cellular data networks, as defined by the ITU standards body and the IMT-2000 global standard. EVDO-RevA would be an example of 3G. Obviously, 3G is a mobile technology. It was designed for video, voice and data.

3GPP is a group of telcos collaborating on GSM specs for worldwide usage.

This means that you can take your Blackberry World Edition to Europe and it should work on the GSM network there. 3GPP members are using the IMT-2000 standard for inter-operability. (Hey, the world is flat remember?) 3GPP2 is a project for CDMA players. 3GPP LTE (long term evolution) is what Verizon just picked for its 4G (fourth-generation) network. It is based on UMTS (W-CDMA). Inter-operable doesn’t mean that your GSM based phone will work on a CDMA network (like Sprint, Verizon Wireless and Alltel). It means that your iPhone should work on T-Mobile, Orange in Europe or Rogers in Canada. EVDO and EDGE are CDMA and GSM, respectively, flavors of cellular data service.

It is important to remember that 802.11 (WLAN) was designed for data, not voice or video. And much of the standardizations have to do with more efficient use of the available spectrum. (We aren’t recreating physics here. It’s more like adding algorithms to do to spectrum what telecom does with light via wave multiplexing like DWDM). 802.16 is a metro Wireless standard. 802.11 is a set of LAN wireless standards. 3G is a cellular standard. All different but treated the same by some uninformed media. It is really confusing to the consumer.

Peter Radizeski is president of

RAD-INFO

. He can be reached at

peter@rad-info.net

.


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