Wireless to the max

The emerging broadband wireless standard WiMax will address some of the problems with current technology and take wireless to a whole new level.



commentary The emerging broadband wireless standard WiMax will address some of the problems with current technology and take wireless to a whole new level.

A single access point could cover the entire campus whereas 30 or more are currently needed to provide the coverage.
Last month I talked about the range improvements in notebook Wi-Fi, and this month I will talk some more about this burgeoning technology. Wireless LAN is one of the hot topics for clients and the Lab is currently working on several projects in this field.

Sadly, I can say no more on the specific projects because they're under NDA -- although one involves testing a real-world and very large-scale roll out, and the other is an emerging technology that -- if it lives up to its promise -- may just smash the distance record for roaming wireless connections. Since I can't talk about these, let's look at something I can talk about: WiMAX.

WiMAX, which will encompass 802.16-2004 and 802.16e, looks like Wi-Fi on steroids and effectively provides broadband data speeds over kilometres rather than a few hundred feet.

The 802.16-2004 standard (802.16REVd) extends the first standard 802.16a-2001 to indoors near line of sight (NLOS) and was published in July this year. We don't expect to see 802.16e until early next year, which introduces mobility and roaming into the mix.

Just how far and fast can WiMAX be pushed? The claim is up to 75Mbps for the base station with a 20MHz-wide channel. Realistically, regulators only allow a channel of 10MHz, so in practice we will never see this bandwidth. Range is touted to be up to 50km with a reduced data rate of a couple of Mbps, under optimal conditions of course, but again reality will be less than this.

Environment Typical range (cell size) Throughput
City site indoors (NLOS) 1km 21Mbits/s
Suburban site indoors (NLOS) 2.5km 22Mbits/s
Suburban site outdoors line of sight (LOS) 7km 22Mbits/s
Rural site indoors (NLOS) 5km 4.5Mbits/s
Rural site outdoors (LOS) 15km 4.5Mbits/s

So what are we really talking? The table above illustrates the typical ranges and throughputs we can expect to see.

As you can see, there are some important ramifications of the technology. A single access point could cover the entire campus whereas 30 or more are currently needed to provide the coverage. In areas where ADSL or other broadband technologies aren't available, WiMAX could provide a high-bandwidth connection. Imagine roaming when this technology becomes pervasive; it would be a long time between dropouts, compared to current 802.11b/g technology.

This all sounds great but what about the bane of Wi-Fi: security?

WiMAX proposes a broad range of security features including authentication through the use of certificates and extensible authentication protocol and data encryption using either DES or AES. This appears to be quite robust, which should accelerate the acceptance of the technology.

I'm pretty excited about the prospects; the Lab can't wait to get our hands on WiMAX for testing. And I can think of many people who live in estates with little or no provision for ADSL broadband who are champing at the bit with the prospect of the entire estate covered by a single WiMAX Access Point.

Steve Turvey is Lab Manager of the RMIT IT Test Labs, and can be reached at stevet@ rmit.edu.au.

This article was first published in Technology & Business magazine.
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