Expanded, WiMax means World wide Interoperability for Microwave Access.
And who would be the beneficiaries? Well, proponents of the technology claim
that it will make broadband affordable to masses, though the initial adopters
would be enterprises, as usual.
Theoretically, all of the above are correct. Practically too, encouraging
results have been reported from ongoing trials, some of which are being run in
India as well.
What's New about It?
There is nothing new about WiMax, as a concept. Wi-Fi uses much the same
concept, as do some other microwave technologies like MMDS. Both the
technologies use orthogonal frequency division multiplexing (OFDM) or its
In fact, WiMax is more of a standard than a technology. A key purpose that
the standard serves is to focus much of the microwave access work to a more
manageable frequency range.
Earlier, vendors were developing products for too wide a spectrum-from 2
GHz to 66 GHz. That made it too scattered and hence less appealing for carriers.
The WiMax standard put a tab on the upper range, at 11 GHz.
Typically, the sub-11 GHz bands are characteristically more suited for non—line
of sight (NLOS), last-mile distribution, whereas the higher frequencies (up to
66 GHz) adapt well for LOS backhauling.
It is therefore that WiMax, as a last-mile wireless broadband technology,
sought to use the 2 GHz to 11 GHz frequencies.
Not the entire range is available globally. Let's look at what all bands
are usable and promising for WiMax growth.
Two license-exempt industrial, scientific, and medical (ISM) bands exist
between 2.4—2.48 GHz and 5.73—5.85 GHz frequencies. Another unlicensed band
exists between 5.15—5.85 GHz (one may note the overlap with the upper ISM band
here) and is referred to as the Unlicensed National Information Infrastructure
Then there is the multi-channel multipoint distribution service (MMDS) band
in the 2.5—2.7 GHz range. This channel was originally earmarked for
instructional TV purposes in the US, but has now been licensed to Sprint,
Worldcom, and Nucentrix. More than 30 channels of 6 MHz each exist in this band
Licensed channels in the 3.3—3.6 GHz band are available in many Asian and
European countries for broadband wireless access (BWA) purposes. In India the
proposed range is 3.3—3.4 GHz.
is in this light that WiMax Forum had identified three frequency bands-namely
2.4 GHz, 3.5 GHz, and 5.8-for harmonization works.
WiMax stakeholders have also been lobbying with governments world over to
free up the 700—800 MHz frequencies for wireless broadband usage.
As of now, most of the WiMax gears are in the pre-certification stage-WiMax
Forum will begin certifying products only in mid-2005. Also, bulk of the
development is for frequencies between 2 GHz and 11 GHz.
WiMax versus Wi-Fi
An initial apprehension, of Wi-Fi interest groups, was that WiMax will be a
threat to Wi-Fi in future, especially because it would use the same frequencies
and have a longer range, both in LOS and NLOS conditions.
WiMax advocates sought to clear the fear by assuring that the technology
would complement rather than cannibalize Wi-Fi. The argument was that while
Wi-Fi had a role to play as a wireless LAN technology, WiMax would serve as
wireless MAN technology.