12  n  WiMAX: A Wireless Technology Revolution
supporting both Wi-Fi and WiMAX will be available for notebook computers,
PDAs, smart phones, and other handheld devices, thus enabling end users a seam-
less transition between 802.11-based LANs and 802.16-based MANs. What this
points out is that WiMAX actually can provide two forms of wireless service:
there is the NLoS, Wi-Fi sort of service, where a small antenna on your computer
connects to the tower. In this mode, WiMAX uses a lower frequency range, i.e.,
2 to 11 GHz (similar to Wi-Fi). Lower-wavelength transmissions are not as easily
disrupted by physical obstructions; they are better able to diffract, or bend, around
obstacles. ere is LoS service, where a fixed dish antenna points straight at the
WiMAX tower from a rooftop or pole. e LoS connection is stronger and more
stable, so it is able to send a lot of data with fewer errors. LoS transmissions use
higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies,
there is less interference and lots more bandwidth. Wi-Fi-style access will be limited
to a 4- to 6-mi radius (perhaps 25 sq mi or 65 sq km of coverage, which is similar
in range to a cell-phone zone). rough the stronger LoS antennas, the WiMAX
transmitting station would send data to WiMAX-enabled computers or routers set
up within the transmitter’s 30-mi radius (2800 sq mi or 9300 sq km of coverage).
is is what allows WiMAX to achieve its maximum range.
WiMAX operates on the same general principles as Wi-Fi — it sends data from
one computer to another via radio signals. A computer (either a desktop or a laptop)
equipped with WiMAX would receive data from the WiMAX transmitting station,
probably using encrypted data keys to prevent unauthorized users from stealing
access. e fastest Wi-Fi connection can transmit up to 54 Mbps under optimal
conditions. WiMAX should be able to handle up to 70 Mbps. Even once that
70 Mb is split up between several dozen businesses or a few hundred home users,
it will provide at least the equivalent of cable-modem transfer rates to each user.
e biggest difference is not speed; it is distance. WiMAX outdistances Wi-Fi by
miles. Wi-Fi’s range is about 100 ft (30 m). WiMAX will blanket a radius of 30 mi
(50 km) with wireless access. e increased range is due to the frequencies used and
the power of the transmitter. Of course, at that distance, terrain, weather, and large

that the industry can provide it. Two primary bands are under consideration — the
licensed 3.5-GHz band and the unlicensed 5.8-GHz UNII band frequencies
(Table 1.6). Of these, the 3.5-GHz band seems to offer more promise, given the
●
●
●
n
3GPP bands
WiMAX approved
WiMAX proposed
880
960
1710
1885
2200
2305
2360
2400
2480
2500
2690
2700
2900
3300
3400
3600
5150
5350
5470
5725

measured in square meters. ese BSs will eventually cover an entire metropolitan
area, making that area into a WMAN and allowing true wireless mobility within
it, as opposed to hot-spot hopping required by Wi-Fi. Proponents of WiMAX are
hoping that the technology will eventually be used in notebook computers and
PDAs. True roaming cell-like wireless broadband, however, will require 802.16e.
True broadband for portable users, based on IEEE 802.16e, enables the creation of
a “CPE-less” broadband market, providing broadband connectivity for laptops and
PDAs with integrated WiMAX technology.
Governments globally are starting to prioritize broadband as a key political
objective for all citizens to overcome the “broadband gap,” also known as the
“digital divide.” In last-mile markets where traditional cable or copper/fiber infra-
structures are saturated, outdated, or simply out of reach, BWA technology fills the
void admirably, providing highly efficient and cost-effective access services for a
large number of subscribers who would otherwise be left out of the loop in devel-
oped markets. e growing demand for broadband services on a global scale is clear
and uncontestable. Businesses, public institutions, and private users regard it as an
enabling technology, and it has become a given requirement for delivering commu-
nications services in the information age. e introduction of WMAN standards
(802.16 and HiperMAN), and the guidelines set forth by the WiMAX Forum to
ensure its success, will do much to encourage the growth of broadband wireless
markets everywhere, benefiting everyone in the delivery chain — from equipment
vendors to carriers to end users. As the wireless industry’s most experienced solu-
tions provider, Alvarion has a long and impressive record of commitment to devel-
oping and introducing standardized protocols. e buzz on WiMAX these days is
electric. Internationally, it seems that WiMAX is already poised to take off as it is
a hungrily awaited product.
Numerous countries have aggressive service providers fielding broadband ser-
vices largely in the 3.5-GHz spectrum. e results of various investigations show
that there is a positive business case for operators who want to add services and
applications comparable to other existing broadband technologies (e.g., cable or

benefit from economies of scale and hence bring dramatic improvement to the
business case for the operator. WiMAX products are set to become the mainstream
broadband wireless platform. Although the overall number of subscriber lines is
quite small relative to DSL or cable, the dollar value is growing to the point where
even major carriers are beginning to pay close attention. It is not only the devel-
oped markets that can benefit from WiMAX. For emerging markets, operators
are interested in using WiMAX for low-cost voice transport and delivery, which
has been very difficult with proprietary solutions. As noted previously, the mar-
kets without any fixed infrastructure pose the greatest opportunities. Develop-
ments such as WiMAX chipsets embedded in laptops and other mobile devices
will lead to broadband portability and to a CPE-less business model, which makes
the case even more compelling for an operator because the user is subsidizing the
model.
e main problems with broadband access are that it is expensive and it does
not reach all areas. e main problem with Wi-Fi access is that hot spots are very
small, so coverage is sparse. WiMAX has the potential to do to broadband Internet
access what cell phones have done to phone access. In the same way that many peo-
ple have given up their “landlines” in favor of cell phones, WiMAX could replace
cable and DSL services, providing universal Internet access just about anywhere
you go. WiMAX will also be as painless as Wi-Fi — turning your computer on will
automatically connect you to the closest available WiMAX antenna. An important
aspect of the IEEE 802.16 is that it defines a MAC layer that supports multiple
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16  n  WiMAX: A Wireless Technology Revolution
physical layer (PHY) specifications. is is crucial to allow equipment makers to
differentiate their offerings. Enhancements to current and new technologies and
potentially new basic technologies incorporated into the PHY can be used. A con-
verging trend is the use of multimode and multiradio SoCs and system designs that
are harmonized through the use of common MAC, system management, roaming,
IMS, and other levels of the system. WiMAX may be described as a bold attempt at

products from a wide range of vendors, enables system vendors to create many dif-
ferent types of products, including various configurations of BSs and customer
premise equipment. WiMAX supports a variety of wireless broadband connections:
In addition to supporting the 2- to 11-GHz frequency range, the 802.16d standard sup-
ports three PHYs. e mandatory PHY mode is 256-point FFT orthogonal frequency
modulation (OFDM). e other two PHY modes are single carrier (SC) and 2048
orthogonal frequency division multiple access (OFDMA) modes. e corresponding
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