Fundamentals of WiMAX
`Understanding Broadband Wireless Networking
`
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`Jeffrey G. Andrews - Arunabha Ghosh - Rias Muhamed
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`Prentice Hall Communications Engineering and Emerging Technologies Series
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`Foreword by Theodore S. Happaport, Series Editor
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`Qualcomm Incorporated Ex. 1005
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` a
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`Fundamentals of WiMAX
`
`Understanding Broadband Wireless Networking
`
`.
`Jeneratzon
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`Jeffrey G. Andrews, Ph.D.
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`
`
`Department of Electrical and Computer Engineering
`The University of Texas at Austin
`
`Arunabha Ghosh, Ph.D.
`
`AT&TLabs Inc.
`
`Rias Muhamed
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`AT& T Labs Inc.
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`nulation
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`aption
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`o o
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`o o
`PRENTIBE
`HALL
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`PERKINS‘ COIE 7
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`LAW LIBRARY
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`MAR 1 4 2307
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`Library of Congress Ctlmlagt'ng-itt-Pttlvlica/ion Data
`An drews, Jeffrey G.
`Fundamentals of WiMAX :
`Muhamed.
`p. cm.
`
`understanding broadband wireless networking / Jeffrey G. Andrews. Arunabha Ghosh. Rias
`
`Includes bibliographical references and index.
`ISBN 071372225512 (hbk: alk. paper)
`1. Wireless communication systems. 2. Broadb
`Title.
`TK5103.3.A56 2007
`621.382—d022
`
`Copyright © 2007 Pearson Education. Inc
`
`and communication systems.
`
`I. Ghosh. Arunabha. II. Muhamed. Rias. IH.
`
`2006038505
`
`All tights reserved. Prtntcd tn the United States ul'Ainertczt. This publication is pmtected hy copvrtght. and [INBIiTllKhltII'E must
`he nhtatncd lrunt the puhitsl'ter prior it: any pt-nltthued teprttducimn storage tn a retrieval system. or transtntslartn in any
`turn-t or by any means. electronic. mechanical. photocopying. I'CUUKIIIIg. or ltkeuise. For ittlormation regarding permissions.
`“tilt: in:
`Pearson Education, Inc.
`Rights and Contracts Department
`One Lake Street
`Upper Saddle River. NJ 07458
`Fax: (201)236-3290
`ISBN 0-13-222552-2
`
`Text printed in the United States on recycled paper at Courier in Westford, Massachusetts
`First printing. February 2007
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`Wireless
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`Introduction to Broadband
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`
`roadband wii‘cie5s sits at Lhe confluence of two of the most remarkable growth stories ofthe
`B telecommunications industry in recent years. Both wireless and broadband have on their
`own enjoyed rapid mass-market adoption. Wireless mobile services grew from 11 million sub-
`scribers worldwide in 1990 to more than 2 billion in 2005 [1]. During the same period, the Inter—
`net grew from being a curious academic tool to having about a billion users. This staggering
`growth of the Internet is driving demand for higher—speed Internet-access services, leading to a
`parallel growth in broadband adoption. In less than a decade, broadband subscription worldwide
`has grown from virtually zero to over 200 million [2]. Will combining the convenience of wire—
`less with the rich performance of broadband be the next frontier for growth in the industry? Can
`such a combination be technically and commercially viable? Can wireless deliver broadband
`applications and services that are of interest to the endusers? Many industry observers believe so.
`Before we delve into broadband wireless, let us review the state of broadband access today.
`Digital subscriber line (DSL) technology, which delivers broadband over twisted—pair telephone
`Wires, and cable modem technology, which delivers over coaxial cable TV plant, are the predom—
`inant mass-market broadband access technologies today. Both of these technologies typically
`provide up to a few megabits per second of data to each user, and continuing advances are mak-
`ing several tens of megabits per second possible. Since their initial deployment in the late 19903,
`these services have enjoyed considerable growth. The United States has more than 50 million
`broadband subscribers, including more than half of home Internet users. Worldwide, this num-
`ber is more than 200 million today and is projected to grow to more than 400 million by 2010
`[2]. The availability of a wireless solution for broadband could potentially accelerate this
`growth.
`
`What are the applications that drive this growth? Broadband users worldwide are finding that
`It dramatically changes how we share information. conduct business, and seek entertainment.
`
`.1rod
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`Figure1. 1 Worldwide subscriber growth 1990—2006 for mobile telephony, Internet usage, and
`broadband access [1, 2 3]
`
`Broadband access not only provides faster Web surfing and quicker file downloads but also
`enables several multimedia applications, such as real-time audio and video streaming, multimedia
`conferencing, and interactive gaming. Broadband connections are also being used for voice tele—
`phony using voice-over—Internet Protocol (VOIP) technology. More advanced broadband access
`systems, such as fiber—to-the—home (FTTH) and very high data rate digital subscriber loop
`(VDSL), enable such applications as entertainment-quality video, including high—definition TV
`(HDTV) and video on demand (VoD). As the broadband market continues to grow, several new
`applications are likely to emerge, and it is difficult to predict which ones will succeed in the
`future.
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`l. Nonmdicily implies the ability to connect to the network from different locations via different base
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`stations; mobility implies the ability to keep ongoing connections active while moving at vehicular
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`speeds.
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`So what is broadband wireless? Broadband wireless is about bringing the broadband experid
`ence to a wireless context, which offers users certain unique benefits and convenience. There are
`two fundamentally different types of broadband wireless services. Thc first type attempts to pro—
`vide a set of services similar to that of the traditional fixed—line broadband but using wireless as
`the medium of transmission. This type, called fixed wireless broadband, can be thought of as a
`competitive alternative to DSL or cable modem. The second type of bioadband wireless, called
`mobile broadband, offers the additional functionality of portability, nomadicity,1 and mobility.
`Mobile broadband attempts to bring broadband applications to new user expelience scenarios V
`and hence can offer the end user a very different value proposition. WiMAX (worldwide interop-
`erability for microwave access) technology, the subject of this book, is designed to accommo—
`date both fixed and mobile broadband applications.
`
`
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`Chapter
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`1
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`~ Introduction to Broadband Wireless
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`
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`Wireless
`
`
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`1.1 Evolution of Broadband Wireless
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`5
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`
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`In this chapter, we provide a brief overview of broadband wireless. The objective is to
`present the the background and context necessary for understanding WiMAX. We review the
`history of broadband wireless, enumerate its applications, and discuss the business drivers and
`challenges. In Section 1.7, we also survey the technical challenges that need to be addressed
`while developing and deploying broadband wireless systems.
`
`1.1 Evolution of Broadband Wireless
`
`The history of broadband wireless as it relates to WiMAX can be traced back to the desire to
`find a competitive alternative to traditional wireline-access technologies. Spurred by the deregu-
`lation of the telecom industry and the rapid growth of the Internet, several competitive carriers
`were motivated to find a wireless solution to bypass incumbent service providers. During the
`past decade or so, a number of wireless access systems have been developed, mostly by start—up
`companies motivated by the disruptive potential of wireless. These systems varied widely in
`their performance capabilities, protocols, frequency spectrum used, applications supported, and
`a host of other parameters. Some systems were commercially deployed only to be decommis»
`sioned later. Successful deployments have so far been limited to a few niche applications and
`markets, Clearly, broadband wireless has until now had a checkered record, in part because of
`the fragmentation of the industry due to the lack of a common standard. The emergence of
`WiMAX as an industry standard is expected to change this situation.
`Given the wide variety of solutions developed and deployed for broadband wireless in the
`past, a full historical survey of these is beyond the scope of this section. Instead, we provide a
`brief review of some of the broader patterns in this development. A chronological listing of some
`of the notable events related to broadband wireless development is given in Table 1.1.
`WiMAX technology has evolved through four stages, albeit not fully distinct or clearly
`sequential: (l) narrowband wireless local-loop systems, (2) first—generation line-of—sight (LOS)
`broadband systems, (3) second-generation non—line-of-sight (NLOS) broadband systems, and
`(4) standards-based broadband wireless systems.
`J
`
`1.1.1 Narrowband Wireless Local-Loop Systems
`Naturally, the first application for which a wireless alternative was developed and deployed was
`Voice telephony. These systems, called wireless local—loop (WLL), were quite successful in
`developing countries such as China, India, Indonesia, Brazil, and Russia, whose high demand
`for basic telephone services could not be served using existing infrastructure. In fact, WLL sys
`tems based on the digital—enhanced cordless telephony (DECT) and code division multiple
`access (CDM A) standards continue to be deployed in these markets.
`In markets in which a robust local-loop infrastructure already existed for voice telephony.
`WLL systems had to offer additional value to be competitive. Following the commercialization
`0f the Internet in 1993, the demand for Internet»access services began to surge, and many saw
`P'UVIding high—speed Internet—access as a way for wireless systems to differentiate themselves.
`Fur example, in February 1997, AT&T announced that it had developed a wireless access system
`
`and
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`Chapter
`1
`- Introduction to Broadband Wireless
`
`for the 1,900MH2 PCS (personal communications services) band that could deliver two voice
`lines and a 128kbps data connection to subscribers. This system, developed under the code name
`“Project Angel,” also had the distinction of being one of the first commercial wireless systems to
`use adaptive antenna technology. After field trials for a few years and a brief commercial offer-
`ing, AT&T discontinued the service in December 2001, citing cost run-ups and poor take-rate as
`reasons.
`
`During the same time, several small start-up companies focused solely on providing Inter-
`net—access services using wireless. These wireless Internet service provider (WISP) companies
`typically deployed systems in the license—exempt 900MHz and 2.4GHz bands. Most of these
`systems required antennas to be installed at the customer premises, either on rooftops or under
`the caves of their buildings. Deployments were limited mostly to select neighborhoods and small
`towns. These early systems typically offered speeds up to a few hundred kilobits per second.
`Later evolutions of license—exempt systems were able to provide higher speeds.
`
`1.1.2 First-Generation Broadband Systems
`
`As DSL and cable modems began to be deployed, wireless systems had to evolve to support
`much higher speeds to be competitive. Systems began to be developed for higher frequencies,
`such as the 2.5GHz and 3.5GHz bands. Very high speed systems, called local multipoint distri-
`bution systems (LMDS), supporting up to several hundreds of megabits per second, were also
`developed in millimeter wave frequency bands, such as the 24GHZ and 39GHz bands. LMDS—
`based services were targeted at business users and in the late 1990s enjoyed rapid but short—lived
`success. Problems obtaining access to rooftops for installing antennas, coupled with its shorter-
`range capabilities, squashed its growth.
`
`In the late 1990s, one of the more important deployments of wireless broadband happened
`in the so—called multichannel mulzipoim distribution services (MMDS) band at 2.5GHz. The
`MMDS band was historically used to provide wireless cable broadcast video services, especially
`in rural areas where cable TV services were not available. The advent of satellite TV ruined the
`wireless cable business, and operators were looking for alternative ways to use this spectrum. A
`few operators began to offer one-way wireless Intemet—access service, using telephone line as
`the return path. In September 1998, the Federal Communications Commission (FCC) relaxed
`the rules of the MMDS band in the United States to allow two—way communication services,
`sparking greater industry interest in the MMDS band. MCI WorldCom and Sprint each paid
`approximately $1 billion to purchase licenses to use the MMDS spectrum, and several compa-
`nies started developing high-speed fixed wireless solutions for this band.
`
`The first generation of these fixed broadband wireless solutions were deployed using the
`same towers that served wireless cable subscribers. These towers were typically several hundred
`feet tall and enabled LOS coverage to distances up to 35 miles, using high-power transmitters.
`First-generation MMDS systems required that subscribers install at their premises outdoor
`antennas high enough and pointed toward the tower for a clear LOS transmission path. Sprint
`and MCI launched two-way wireless broadband services using first—generation MMDS systems
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`AT&T announces development of fixed wireless technology code named “Project
`Angel”
`
`FCC auctions 30MHz spectrum in 2.3GHz band for wireless communications services
`(WCS)
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`|
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`February 1997
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`February 1997
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`September 1997
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`1.1 Evolution of Broadband Wireless
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`Table 1.1 Important Dates in the Development of Broadband Wireless
`Date
`
`Event
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`Jand Wireless
`
`r two voice
`code name
`systems to
`:rcial offer-
`:ake-rate as
`
`ding Inter-
`companies
`st of these
`is or under
`: and small
`er second.
`
`to support
`:quencies,
`)im‘ distri-
`were also
`;. LMDS-
`hon—lived
`:s shorter-
`
`happened
`}Hz. The
`
`:specially
`uined the
`:ctium. A
`re line as
`) relaxed
`services,
`ach paid
`I compa-
`
`tsing the
`hundred
`smitters.
`outdoor
`
`1. Sprint
`systems
`
`
`American Telecasting (acquired later by Sprint) announces wireless Internet access
`services in the MMDS band offering 750kbps downstream with telephone dial—up
`modem upstream
`
`September 1998 FCC relaxes rules for MMDS band to allow two-way communications I ‘
`A ,1 1999
`MCI and Sprint acquire several wireless cable operators to get access to MMDS
`pr1
`spectrum
`
`July 1999
`First working group meeting of IEEE 802,16 group
`
`March 2000
`AT&T launches first commercial high-speed fixed wireless service after years of trial
`
`May 2000
`Sprint launches first MMDS deployment in Phoenix, Arizona, using first—generation
`LOS technology
`
`June 2001
`,. WiMAX Forum established
`
`October 2001
`Sprint halts MMDS deployments
`-December 2001 AT&T discontinues fixed wireless services
`
`
`
`IEEE 802.16 standards completed for > llGHz.
`December 2001
`
`February 2002
`Korea allocates spectrum in the 2.3GHz band for wireless broadband (WiBro)
`
`January 2003
`IEEE 802.16a standard completed
`
`
`June 2004 IEEE 802.16—2004 standard completed and approved
`September 2004
`lntel begins shipping the first WiMAX chipset, called Rosedale
`December 2005
`IEEE 802.16e standard completed and approved
`January 2006
`First WiMAX Forum—certified product announced for fixed applications
`June 2006
`WiBro commercial services launched in Korea
`
`August 2006
`
`Sprint Nextel announces plans to deploy mobile WiMAX in the United States
`
`in a few markets in early 2000. The outdoor antenna and LOS requirements proved to be signifi—
`cant impediments. Besides, since a fairly large area was being served by a single tower, the
`capacity of these systems was fairly limited. Similar first-generation LOS systems were
`deployed internationally in the 3.5GHz band.
`
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`Chapter
`
`1
`
`- Introduction to Broadband Wireless
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`1.1.3 Second-Generation Broadband Systems
`
`Second-generation broadband wireless systems were able to overcome the LOS issue and to pro-
`vide more capacity. This was done through the use of a cellular architecture and implementation
`of advanced-signal processing techniques to improve the link and system performance under
`multipath conditions. Several start-up companies developed advanced proprietary solutions that
`provided significant performance gains over first—generation systems. Most of these new sys-
`tems could perform well under non—line-of—sight conditions, with customer—premise antennas
`typically mounted under the eaves or lower. Many solved the NLOS problem by using such tech-
`niques as orthogonal frequency division multiplexing (OFDM), code division multiple access
`(CDMA), and multiantenna processing. Some systems, such as those developed by SOMA Net-
`works and Navini Networks, demonstrated satisfactory link performance over a few miles to
`desktop subscriber terminals without the need for an antenna mounted outside. A few megabits
`per second throughput over cell ranges of a few miles had become possible with second—
`generation fixed wireless broadband systems.
`
`1.1.4 Emergence of Standards-Based Technology
`
`In 1998, the, Institute of Electrical and Electronics Engineers (IEEE) formed a group called
`802.16 to develop a standard for what was called a wireless metropolitan area network, or wire—
`less MAN. Originally, this group focuscd on developing solutions in the lOGHz to 66GHz band,
`with the primary application being delivering high—speed connections to businesses that could
`not obtain fiber. These systems, like LMDS, were conceived as being able to tap into fiber rings
`and to distribute that bandwidth through a point—to—multipoint configuration to LOS businesses.
`The IEEE 802.16 group produced a standard that was approved in December 2001. This stan—
`dard, Wireless MAN-SC, specified a physical layer that used singiercarrier modulation tech-
`niques and a media access control (MAC) layer with a burst time division multiplexing (TDM)
`structure that supported both frequency division duplexing (FDD) and time division duplexing
`(TDD).
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`After completing this standard, the group started work on extending and modifying it to
`work in both licensed and license-exempt frequencies in the 2GHz to llGHz range, which
`would enable NLOS deployments. This ameiidment, IEEE 802.16a, was completed in 2003,
`with OFDM schemes added as part of the physical layer for supporting deployment in multipath
`environments. By this time, OFDM had established itself as a method of choice for dealing with
`multipath for broadband and was already part of the revised IEEE 802.11 standards. Besides the
`OFDM physical layers, 802.16a also specified additional MAC—layer options, including support
`for orthogonal frequency division multiple access (OFDMA).
`Further revisions to 802.16a were made and completed in 2004. This revised standard, IEEE
`80216—2004, replaces 802.16, 802.16a, and 802.16c with a single standard, which has also been
`adopted as the basis for HIPERMAN (high—performance metropolitan area network) by ETSI
`(European Telecommunications Standards Institute). In 2003, the 802.16 group began work on
`
`enhancements to the specifications to allow vehicular mobility applications. That revision,
`
`
`_m...s-—¢M
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`:0 Broadband Wireless
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`_1 1 Evolution of Broadband Wireless
`
`9
`
`l Sidebar 1.1 A Brief History of OFDM
`
`S issue and to pro—
`‘ld implementation
`nerformance under
`tary solutions that
`
`of these new syse
`premise antennas
`
`y using such tech—
`r’t multiple access
`:d by SOMA Net—
`er a few miles to
`
`2. A few megabits
`ble with second—
`
`d a group called
`network, or wire—
`1 to 66GHZ band,
`nesses that could
`
`lp into fiber rings
`LOS businesses.
`200]. This stan—
`modulation tech—
`
`tiplexing (TDM)
`vision duplexing
`
`modifying it to
`{a range, which
`npleted in 2003,
`rent in multipath
`for dealing with
`1rds. Besides the
`
`1cluding support
`
`1 standard, IEEE
`ch has also been
`
`twork) by ETSI
`. began work on
`That revision,
`
`
`
`
`Although OFDM has become widely used only recently, the concept dates
`back some 40 years. This brief history of OFDM cites some landmark dates.
`
`1966: Chang shows that multicarrier modulation can solve the multipath
`problem without reducing data rate [4]. This is generally considered
`the first official publication on multicarrier modulation. Some earlier
`work was Holsinger’s 1964 MIT dissertation [5] and some of Ga]-
`lager’s early work on waterfilling [6].
`1971: Weinstein and Ebert show that multicarrier modulation can be
`accomplished using a DFT [7].
`1985: Cimini at Bell Labs identifies many of the key issues in OFDM
`transmission and does a proof-of—concept design [8].
`following
`1993: DSL adopts OFDM,
`also called discrete multitone,
`successful field trials/competitions at Bellcore versus equalizer-based
`systems.
`1999: The IEEE 802.11 committee on wireless LANs releases the 802.11a
`standard for OFDM operation in SGHz UNI band.
`2002: The IEEE 802.16 committee releases an OFDM-based standard for
`. wireless broadband access for metropolitan area networks under revi—
`sion 802.1621.
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`2003: The IEEE 802.11 committee releases the 802.11g standard for opera—
`tion in the 2.4GHz band.
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`2003: The multiband OFDM standard for ultrawideband is developed, show-
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`ing OFDM’s usefulness in low—SNR systems.
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`802.16e, was completed in December 2005 and was published formally as IEEE 802.16e—2005.
`It specifies scalable OFDM for the physical layer and makes further modifications to the MAC
`layer to accommodate hi gh»speed mobility.
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`As it turns out, the IEEE 802.16 specifications are a collection of standards with a very
`broad scope. In order to accommodate the diverse needs of the industry, the standard incorpo—
`rated a wide variety of options. In order to develop interoperable solutions using the 802.16 fam-
`ily of standards, the scope of the standard had to be reduced by establishing consensus on what
`Options of the standard to implement and test for interoperability. The IEEE developed the spec—
`ifications but left to the industry the task of converting them into an interoperable standard that
`Can be certified. The WiMAX Forum was formed to solve this problem and to promote solutions
`based on the IEEE 802.16 standards. The WiMAX Forum was modeled along the lines of the
`Wi—Fi Alliance, which has had remarkable success in promoting and providing interoperability
`testing for products based on the IEEE 802.11 family of standards.
`The WiMAX Forum enjoys broad participation from the entire cross—section of the industry,
`including semiconductor companies, equipment manufacturers, system integraters, and service
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`providers. The forum has begun interoperability testing and announced its first certified product
`based on IEEE 80216-2004 for fixed applications in January 2006. Products based on IEEE
`802.18e-2005 are expected to be certified in early 2007, Many of the vendors that previously
`developed proprietary solutions have announced plans to migrate to fixed and/0r mobile
`WiMAX. The arrival of WiMAX—certified products is a significant milestone in the history of
`broadband wireless.
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`1.2 Fixed Broadband Wireless: Market Drivers and Applications
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`Applications using a fixed wireless solution can be classified as point-fo-pnim or paint-m-mzllti-
`point. Point—to—point applications include interbuilding connectivity within a campus and micro—
`wave backhaul. Point-to-multipoint applications include (1) broadband for residential, small
`office/home office (SOHO), and small— to medium—enterprise (SME) markets, (2) T1 or frac-
`tional Tl-like services to businesses, and (3) wireless backhaul for Wi-Fi hotspots. Figure 1.2
`illustrates the various point—to-multipoint applications.
`Consumer and small-business broadband: Clearly, one of the largest applications of
`WiMAX in the near future is likely to be broadband access for residential, SOHO. and SME
`markets. Broadband services provided using fixed WiMAX could include high-speed Internet
`access, telephony services using voice over IR and a host of other Internet-based applications.
`Fixed wireless offers several advantages over traditional wired solutions. These advantages
`include lower entry and deployment costs; faster and easier deployment and revenue realization;
`ability to build out the network as needed; lower operational costs for network maintenance,
`management, and operation; and independence from the incumbent carriers.
`From a customer premise equipment (CPE)2 or subscriber station (SS) perspective, two
`types of deployment models can be used for fixed broadband services to the residential, SOHO,
`and SME markets. One model requires the installation of an outdoor antenna at the customer
`premise; the other uses an all-in-one integrated radio modem that the customer can install
`indoors like traditional DSL or cable modems. Using outdoor antennas improves the radio link
`and hence the performance of the system. This model allows for greater coverage area per base
`station, which reduces the density of base stations required to provide broadband coverage,
`thereby reducing capital expenditure, Requiring‘an outdoor antenna, however, means that instal—
`lation will require a truck—roll with a trained professional and also implies a higher SS cost.
`Clearly, the two deployment scenarios show a trade—off between capital expenses and operating
`expense: between base station capital infrastructure costs and SS and installation costs. In devel—
`oped countries, such as the United States, the high labor cost of truck-roll. coupled with con-
`sumer dislike for outdoor antennas, will likely favor an indoor SS deployment, at least for the
`residential application. Further, an indoor self—install SS will also allow a business model that
`can exploit the retail distribution channel and offer consumers a variety of SS choices. ln devel—
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`2. The CPE is referred to as a subscriber station (SS) in fixed WiMAX.
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`1nd Wireless
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`1_2 Fixed Broadband Wireless: Market Drivers and Applications
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`11
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`3d product
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`previously
`or mobile
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`history of
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`litoimulti—
`tnd micro-
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`tial, small
`'I or frac—
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`Figure 1.2
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`cations of
`and SME
`(1 Internet
`)lications,
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`dvantages
`:alization;
`ntenance,
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`II'ITI'IIII
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`Symmetric T1 Services for
`Enterprise
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`1:”
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`Wireless Backhaul for
`Hotspots
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`Fractional T1 for SME
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`" l"
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`I"A
`- It"
`. -
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`Residential/SOHO
`Broadband
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`Figure 1.2 Point-to-multipoint WiMAX applications
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`oping countries, however, where labor is cheaper and aesthetic and zoning considerations are not
`so powerful, an outdoor—SS deployment model may make more economic sense.
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`:tive, two
`11, SOHO,
`customer
`an install
`radio link
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`1 per base
`coverage,
`aat instal-
`' SS cost.
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`operating
`In devel-
`with con—
`st for the
`Iodel that
`In devel—
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`In the United States and other developed countries with good wired infrastructure, fixed
`wireless broadband is more likely to be used in rural or underserved areas, where traditional
`means of serving them is more expensive. Services to these areas may be provided by incumbent
`telephone companies or by smaller players, such as WISPs, or local communities and utilities. It
`is also possible that competitive service providers could use WiMAX to compete directly with
`DSL and cable modem providers in urban and suburban markets. In the United States, the FCC’s
`August 2005 decision to rollback cable plant sharing needs is likely to increase the appeal of
`fixed wireless solutions to competitive providers as they look for alternative means to reach sub—
`scribers. The competitive landscape in the United States is such that traditional cable TV compa»
`nies and telephone companies are competing to offer a full bundle of telecommunications and
`entertainment services to customers. In this environment, satellite TV companies may be pushed
`to offering broadband services including voice and data in order to stay competitive with the
`telephone and cable companies, and may look to WiMAX as a potential solution to achieve this.
`T1 emulation for business: The other major opportunity for fixed WiMAX in developed
`markets is as a solution for competitive Tl/El, fractional Tl/El, or higher—speed services for the
`business market. Given that only a small fraction of commercial buildings worldwide have
`access to fiber, there is a clear need for alternative high—bandwidth solutions for enterprise
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`Chapter
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`customers. in the business market, there is demand for symmetrical Tl/El services that cable
`and DSL have so far not met the technical requirements for. Traditional telco services continue
`to serve this demand with relatively little competition. Fixed broadband solutions using WiMAX
`could potentially compete in this market and trum