How to Build a WiMAX Network

Overviewdirection are easily achieved through overlay
The latest technology buzz is WiMAX wirelessnetworks, software upgradeable base stations,
networks. We have heard many things about thisdual mode devices and dual mode base stations.
wonderful new long haul wireless technology thatThis consideration assures you are not stuck in
it almost seems as though you are just a phoneone mode or the wrong mode and that your initial
call away from having yours' designed andinvestment is protected. Makes the CTO and CEO
installed. Well before you start assuming things likehappy.
we all do, we thought as engineers and networkWiMAX base stations transmit up to 30 miles, but
architects we would share personal experiencesbecause it is a cell-based topology, would yield a
and the experiences of colleagues from aroundmore typical range of 3 to 5 miles. WiMAX
the world, in a manner that is direct, helpful,systems can deliver a capacity of up to 75 Mbps
educational, and certainly reality based. This is aper channel, for fixed and portable access
backpocket Primer for anyone now dealing withapplications. This is enough bandwidth to
the implementation of a WiMAX network.simultaneously support hundreds of businesses
First, there are several misconceptions surroundingwith T-1 speed connectivity and thousands of
WiMAX that need to be cleared up so that theresidences with DSL speed connectivity as we
business aspects and engineering basis have ahave seen.
common understanding.WiMAX technology will be incorporated in portable
Secondly, the people who make the variouscomputers and PDAs expected in late 2006 and
decisions within your organizations need toearly 2007, allowing for urban areas and cities to
understand that there are differences between abecome "MetroZones", the new buzz word, for
private network and an interoperable networkportable outdoor broadband wireless access. In
strategy. This subtle difference does exist andaddition, Wireless service providers and
requires a plan which considers the final transitiontelecommunication equipment industries are
aspects, if considered now, to easily provide aembracing WiMAX technology because of its
lower cost upgrade to a true interoperabletremendous cost advantages to provide that
network, now incorporating diverse vendorlast-mile connectivity to large parts of the world
equipment.that are too expensive to serve with wired
Finally, while WiMAX has been out internationallytechnologies requiring all that trenching.
for several years, it is very new to the UnitedSecurity
States, only a few months old, with very littleDue to the security issues with WEP in the 802.11
training and education available to those who haveWi-Fi arenas, the standards bodies took no
the responsibility to build these systems or thosechances with WiMAX, and wisely prioritized
who will make the financial and technical decisionssecurity from the onset. Base station designers
to have these systems built for them as part ofwent to work to assure a dedicated high
their long haul wireless strategy.performance security processor. The WiMAX
Our experiences and the experiences of oursecurity standard requires that all traffic be
collegues are offered here as contributions as wellencrypted with CCMP (which is Counter Mode
as tying these in to the standards and certificationwith Cipher Block Chaining Message Authentication
authorities all meant to provide a reality basedCode Protocol).
quick reference education for anyone in theAccording to the WiMAX forum, the group's aim
throws of How to Build a WiMAX network.is for end-to-end authentication. WiMAX uses
PrimerPKM-EAP (Extensible Authentication Protocol),
WiMAX is a standard designed for fixedwhich relies on the TLS standard following public
broadband wireless access featuring a controllingkey cryptography. Having addressed this level of
base station, that connects subscriber stations notsecurity from the start provides an excellent
to each other but to various public networks,reference point to add multi-level security options
such as the Internet, linked to that base station.as well, if your implementation requires an MLS
The acronym means " worldwide interoperabilityapproach. Secure (blacker) implementations would
for microwave access" or (WiMAX).require such an approach.
WiMAX, as a standards initiative, is based on aWhat is Released?
"set of profiles" supporting a wide range ofThe first certification release for 802.16-2004
frequencies (up to 66GHz)with channel sizesfixed is out there already and includes products
(1.25MHz to 20MHz) and applications (LOS andfrom certified vendors with two profiles in the
NLOS), and finally PTP and PTMP. The WiMAX3.5GHz and the 5.8GHz bands supporting fixed and
profiles narrow the scope of 802.16 to focus onnomadic access. The profiles for 802.16e mobile
first service specific configurations. The IEEE titledare not available nor released as of this writing
the specification 802.16 and released it Decemberbut are expected to be in the ranges of 2.3GHz
2002. The profiles addressed in that "profilesto 2.5GHz when officially released. WiMAX profiles
release" are 802.16-2004 (old d) and 802.16e asbased on 802.16-2004 are better suited to fixed
presented further down.applications that use directional antennas because
The WIMAX forum was formed eight monthsOFDM is inherently less complex than SOFDMA
earlier in April 2002 to support, promote andused in the mobile application. As a results,
certify compatibility and interoperability of devices802.16-2004 networks will be deployed much
based on the 802.16 specification, and to developfaster and at a lower cost. Our experiences are
such devices for the marketplace. Foundingwith these released systems in the US and
Members of the organization include Airspan,around the world in ground applications, mobile
Alvarion, Analog Devices, Aperto Networks,military, public safety and maritime applications.
Ensemble Communications, Fujitsu, Intel, Nokia,Planning for WIMAX
OFDM Forum, Proxim, and Wi-LAN.Companies, cities or projects in maritime or
WiMAX is the IEEE 802.16 Point-to-Multipointground systems in the US that have decided to
broadband wireless access standard for systemsor are considering building and operating a WiMAX
in the stated frequency ranges. WiMAX will initiallynetwork will have a few important issues to
provide fixed nomadic, portable and eventually,consider. The initial spectrum for WiMAX in the
mobile wireless broadband connectivity. To thatUSA is unlicensed spectrum in the 5GHz range.
end there are two standards (802.16d (newGiven this spectrum is open it will have inherent
-2004) and 802.16e respectively) although they willinterference issues and risks which will require
both perform similar functions because they mustattention. There are many ways of overcoming
be interoperable. One clearly is a fixed solution andinterference issues. The answers come from a
the other a mobile solution that must stillproper site selection, following your RF survey
communicate with a fixed solution. So one of thetraining and from the actual selected equipment.
first considerations is whether you want to buildSo, the planning and site survey results remain
out a mobile or fixed network. In many casesthe key to your confident success.
you would have already considered your targetSummary
market segments, spectrum availability, regulatoryWiMAX provides optimized solutions for fixed,
constraints and your deployment need.nomadic, portable and mobile broadband wireless
Which One do I Need?access. There are two flavors in various release
Generally speaking, the current 802.16-2004and implementation modes. The first is
(originally 802.16d) fixed network products are802.16-2004 WiMAX with two initial frequency
less complex than 802.16e mobile networkprofiles - the 3.5GHz and the 5.8GHz bands
systems because; they can be used in a widersupporting fixed and nomadic access in LOS and
range of unlicensed bands, they offer a fasterNLOS environments now. The other flavor is
time-to-market, and in many cases a higher802.16e WiMAX with expected profiles in the
throughput than 802.16e equipment. On the other2.3GHz and 2.5GHz ranges optimized for dynamic
hand, there is better support for mobility and amobile radio channels supporting hands-ff and
wider range of terminal form factors advantagesroaming --arriving by 2007. Another exciting
of 802.16e equipment.technology for all of us. Have fun!an extended
It's certainly a consideration but no matter whatversion of this Primer is presented in our
you chose the migration paths to move in eitherOnLine-CTO e-magazine.