Article: Standards from IEEE 802 Unleash the Wireless Internet · 2001. 6. 19. · Article:...

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2001-06-19 IEEE 802.16c-01/10 Project IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16> Title Article: Standards from IEEE 802 Unleash the Wireless Internet Date Submitted 2001-06-19 Source(s) Roger Marks Voice: +1-303-497-3037 NIST Fax: +1-303-497-3037 325 Broadway mailto:[email protected] Boulder, CO 80305 Re: Abstract Within the Institute of Electrical and Electronics Engineers, Inc. (IEEE), the IEEE 802 LAN MAN Standards Committee is developing air interface standards for wireless local area network (LAN), wireless metropolitan area network (MAN), and wireless personal area network (PAN) technology. These standards are enabling the development of an infrastructure for the Wireless Internet. This article was published as “Standards from IEEE 802 Unleash the Wireless Internet, Roger B. Marks, Ian C. Gifford, and Bob O’Hara, IEEE Microwave Magazine 2, pp. 46-56, June 2001.” <http://ieeexplore.ieee.org/iel5/6668/20011/00924918.pdf> Purpose This document may improve the effectiveness of standards developers by aiding their understanding of the wireless projects in the IEEE 802 LAN MAN Standards Committee. Notice This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Copyright Permission Copyright ©2001 Institute of Electrical and Electronics Engineers, Inc. Reprinted, with permission, from IEEE Microwave Magazine, Volume: 2, Issue: 2 , June 2001, pp. 46-56. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/ republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE (contact [email protected]). By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

Transcript of Article: Standards from IEEE 802 Unleash the Wireless Internet · 2001. 6. 19. · Article:...

Page 1: Article: Standards from IEEE 802 Unleash the Wireless Internet · 2001. 6. 19. · Article: Standards from IEEE 802 Unleash the Wireless Internet Date Submitted 2001-06-19 Source(s)

2001-06-19 IEEE 802.16c-01/10

Project

IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>

Title

Article: Standards from IEEE 802 Unleash the Wireless Internet

Date Submitted

2001-06-19

Source(s) Roger Marks Voice: +1-303-497-3037

NIST Fax: +1-303-497-3037

325 Broadway mailto:[email protected]

Boulder, CO 80305

Re:

Abstract Within the Institute of Electrical and Electronics Engineers, Inc. (IEEE), the IEEE 802 LAN MAN Standards Committee is developing air interface standards for wireless local area network (LAN), wireless metropolitan area network (MAN), and wireless personal area network (PAN) technology. These standards are enabling the development of an infrastructure for the Wireless Internet.

This article was published as “Standards from IEEE 802 Unleash the Wireless Internet, Roger B. Marks, Ian C. Gifford, and Bob O’Hara,

IEEE Microwave Magazine

2, pp. 46-56, June 2001.”

<http://ieeexplore.ieee.org/iel5/6668/20011/00924918.pdf>

Purpose This document may improve the effectiveness of standards developers by aiding their understanding of the wireless projects in the IEEE 802 LAN MAN Standards Committee.

Notice

This document has been prepared to assist IEEE 802.16. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.

Copyright Permission

Copyright ©2001 Institute of Electrical and Electronics Engineers, Inc. Reprinted, with permission, from

IEEE Microwave Magazine

, Volume: 2, Issue: 2 , June 2001, pp. 46-56. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE (contact [email protected]).By choosing to view this document, you agree to all provisions of the copyright laws protecting it.

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ISSN 1527-3342/01/$10.00©2001 IEEE46 June 2001ISSN 1527-3342/01/$10.00©2001 IEEE

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Within the Institute of Electrical andElectronics Engineers, Inc. (IEEE),the IEEE 802 LAN MAN Stan-dards Committee is developingair interface standards for wire-

less local area network (LAN), wireless metropolitanarea network (MAN), and wireless personal area net-work (PAN) technology. These standards are enablingthe development of an infrastructure for the wirelessInternet.

Standards for the Convergence of Internetand Wireless Communications TechnologiesThe Internet and wireless communications networksrevolutionized communications in the 1990s. The con-vergence of these two technologies leads naturally tothe wireless Internet. Just as standards determined thedevelopment of the Internet and of wireless cellular te-lephony, so will standards influence the evolution ofthe wireless Internet as a social phenomenon. Both thecellular telephony industry and the Internet communi-cations industry bring their own models for standard-ization, and the two offer contrasting visions. Forlow-level network issues, the Internet-based standard-ization model is currently centered in the IEEE and itsIEEE 802 LAN MAN Standards Committee, the worldleader in LAN and MAN standards. IEEE 802 is cur-rently developing and enhancing standards for wire-less LANs, PANs, and MANs.

The wireless Internet model based on cellular tele-phony is embodied in the International Mobile Tele-communications 2000 (IMT-2000) family of standardsfor third-generation wireless communications, pub-lished by the International Telecommunication UnionRadiocommunication Sector (ITU-R). This set of stan-dards foresees an evolution from circuit-switched mo-bile voice services to packet-switched mobile voice anddata. The infrastructure is to be based on cellularbasestations serving highly mobile users (at automo-tive speeds) at 144 kb/s, with the capability to alsoserve fixed users at rates up to 2 Mb/s. The standardswere developed at a technical level by national or re-gional standards bodies so that, when world-widestandards were forged by the ITU-R, the voting mem-bers (national governments) were centrally involved inthe negotiations. As a result, the standards debatesbecame highly politicized events often publicized as“wars.” The world now eagerly anticipates the eco-nomic success of this technology. For example, licenseauctions in Europe have garnered thousands of eurosper resident. By the time these costly systems are engi-neered, constructed, and marketed, investors will havepaid dearly and will be expecting a heavy return.

In a contrast of broad proportions, IEEE 802 is devel-oping an alternative series of wireless Internet stan-dards. IEEE’s global standardization effort involves nonational bodies and therefore no national politics; thework proceeds on a technical and business basis. To alarge degree, the intent is to bring to market low-costproducts that serve customer needs. Much of the workinvolves license-exempt spectrum. This removes thespectrum acquisition costs from the economic picture.Furthermore, it weakens the concept of a monolithic“operator” with strong control over the provided ser-vices. Instead, it opens up the market to enterprise andinnovation. IEEE 802 wireless Internet technologies offerdata rates much higher than those provided by even thefixed user case in IMT-2000; for example, the currently

popular IEEE 802.11b standard supports 11 Mb/s. TheIEEE standards do not offer the mobility of IMT-2000 inthe sense of providing services to moving vehicles, andthey are not aimed at providing blanket coverage to us-ers at arbitrary locations within a city. Instead:

� IEEE 802.16 wireless MAN standards will supporthigh-rate broadband-wireless-access services tobuildings, mostly through rooftop antennas, fromcentral basestations.

� IEEE 802.11 wireless LAN standards support us-ers roaming within homes, office buildings, cam-puses, hotels, airports, restaurants, cafes, etc.

� IEEE 802.15 wireless PAN standards will supportshort-range links among computers, mobile tele-phones, peripherals, and other consumer elec-tronics devices that are worn or carried.

Standardization in IEEE 802

IEEE Standards AssociationThe IEEE is a nonprofit transnational technical profes-sional organization with over 350,000 members. IEEEsupports many technical activities, including confer-ences, publications, and local activities. In addition,IEEE carries out an active program in standardizationthrough the IEEE Standards Association (IEEE-SA).While many IEEE-SA activities are global in scope, itsefforts are accredited by the American National Stan-dards Institute (ANSI). ANSI oversight ensures that itsguiding principles of consensus, due process, andopenness are followed.

IEEE-SA standards are openly developed with con-sensus in mind. Participation in their development,

June 2001 47

R.B. Marks is with the National Institute of Standards and Technol-ogy (NIST), Boulder, Colorado, USA. I.C. Gifford is with

M/A-COM, Inc., Lowell, Massachusetts, USA. B. O’Hara is withInformed Technology, Inc., Santa Clara, California, USA.

If IEEE 802 maintains its record ofsuccess in ushering technology intothe economy and into society, thenIEEE 802.16 will be the tool to makefixed broadband wireless accessa mainstream application

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and use is entirely voluntary. However, history hasshown that standards developed in an open forum canproduce high-quality, broadly accepted results that canfocus companies and forge industries.

The IEEE-SA oversees the standardization processthrough the IEEE-SA Standards Board. Project develop-ment is delegated to individual standard sponsors thatare generally units of the IEEE’s technical societies. Oneof the most important of the IEEE-SA sponsor groups isthe IEEE 802 LAN MAN Standards Committee.

IEEE 802 LAN MAN Standards CommitteeThe IEEE 802 LAN MAN Standards Committee issponsored by the IEEE Computer Society. It first met in1980 to develop a LAN standard that evolved into sepa-rate technologies. It develops and maintains standardsat the physical layer (PHY) and medium access controlsublayer (MAC), each of which fits under a commonlogical link control sublayer (LLC) [1]. Together, thesemake up the two lowest layers of the Open Systems In-terconnection (OSI) seven-layer model for data net-works. The seven-layer model is a standard of theInternational Standards Organization (ISO).

IEEE 802 holds week-long plenary meetings threetimes a year under the leadership of a Sponsor Execu-tive Committee (SEC), chaired since 1996 by Jim Carlo.In between these plenaries, most of its active WorkingGroups hold interim meetings.

Historically, 802 has been best known for the IEEE802.3 standard, informally known as Ethernet, which isa tremendous world-wide success. Ethernet is the foun-dation of so many of the world’s LANs that, for mostpractical purposes, LAN simply means a connection ofEthernet devices. Like all successful 802 standards,however, IEEE 802.3 continuously evolves, movingfrom shared coaxial media to twisted pair with the10BaseT standard and raising the supported data rateswith 100BaseT and 1000BaseT. Optical media are alsosupported, and 802.3 is currently developing a 10 Gb/sstandard. IEEE 802’s portfolio of active projects in thecabled realm grew in late 2000 with the approval of the802.17 Working Group on Resilient Packet Rings.

While Ethernet has been its greatest success, 802 isnow the home of a number of wireless network stan-dardization projects that take advantage of the highlysuccessful system of standards development it pio-neered. Before continuing with detailed discussion ofthe IEEE 802 Wireless Standards Program, it will beuseful to overview this process.

IEEE 802 Standardization ProcessIEEE 802 process is designed for quick development ofstandards with broad consensus. The demand for con-sensus helps to ensure that standards are technicallysuperior and meet market needs.

The development process in IEEE 802 follows thechronological steps outlined below. The process is

overseen by 802’s SEC and defined by a set of rules andprocedures [2]. In brief:

� A study group is chartered to study the prospectsfor a standard in a field and potentially to developa project authorization request (PAR) requestingIEEE-SA approval of a new project. The SEC alsorequires that each PAR be accompanied by a state-ment addressing 802’s “Five Criteria for Stan-dards Development,” demonstrating that theintended standard has broad market potential,compatibility with other 802 standards, distinctidentity within 802, technical feasibility, and eco-nomic feasibility.

� The SEC assigns each approved project to an ex-isting or new working group. Technical decisionsare made by the working group by vote of at least75% of its members. Working group membershipbelongs to individuals, not to companies or otherentities, and is awarded on the basis of participa-tion at meetings. Nonmembers participate ac-tively as well.

� The initial draft development method variesamong groups, but the typical process is to dele-gate the problem to a subordinate task group andissue a public call for contributions for docu-mented input. Eventually a baseline draft is se-lected and then developed.

� Before the SEC will advance the draft, it must beapproved in a working group letter ballot inwhich the members are asked to approve the doc-ument. Any vote against the document must beaccompanied by specific comments on whatchanges are required in order that the voter willapprove it. This process forces constructive sug-gestions and helps drive the process to quick im-provement after a few cycles. Members voting toapprove, and nonmembers as well, are also solic-ited for comments. An approval rate of 75% is re-quired to pass. However, changes made inresponse to comments, and negative commentsthat have not been accepted by the comment reso-lution team, must be recirculated for review bythe voters. In effect, the ballot cannot close untilthose voting negative have had their say andfailed to attract other voters to their argument.The approval margin is typically much higherthan 75% at closure.

� The working group’s final task is to see the draftstandard through “sponsor ballot,” in which it isput before a broad group of interested individu-als. This is similar to a rerun of the working groupletter ballot except that the ballot group is not re-stricted to members of the working group. IEEErequires a balanced ballot group, which ensuresthat is it not dominated by producer or user inter-ests. In addition to the vote, critical comments are,of course vital to the success of the process. It is of-

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ten said that, in 802, the purpose of balloting is notto approve the draft but to improve it.

Experience has shown that the IEEE 802 process isextremely effective at engaging a wide array of inter-ested parties, fostering comments, and making con-structive changes. As a result, 802 drafts are in acontinual state of improvement. When a standard fi-nally makes it through the system, users have solidconfidence in it. With careful attention and the will ofthe developers, it is possible to drive the draft throughthe system within a reasonable time.

IEEE 802 Wireless Standards ProgramThe IEEE 802 Wireless Standards Program comprisesthree working groups:

� IEEE 802.11 working group develops the IEEE802.11 standards for wireless LANs

� IEEE 802.15 working group develops the IEEE802.15 standards for wireless PANs

� IEEE 802.16 working group on broadband wire-less access develops the IEEE 802.16 standards forwireless MANs.

These groups work in a loose association to coordi-nate their activities. IEEE 802.11 and 802.15 haveworked particularly closely since they both address un-licensed bands. 802.16 has historically dealt with li-censed bands and been more independent. However, anew license-exempt project in 802.16 now requires it tocoordinate more closely with the other two workinggroups. Some of this coordination takes place throughthe IEEE 802 regulatory ombudsman, who oversees in-teractions with regulatory activities that affect any orall of the working groups.

The following sections summarize the status andtechnology of the projects in the IEEE 802 wireless stan-dards program.

Wireless LANsThe IEEE 802.11 working group for wireless LAN stan-dards was the first wireless effort in IEEE 802. As withother standards in the 802 family, 802.11 describes aMAC sublayer and multiple PHYs. For the first time inan 802 standard, 802.11 also describes MACmanagement functionality.

The initial base standard, published in 1997, de-scribes the requirements for a LAN implementation us-ing both infrared and spread spectrum radio frequency(RF) communications designed in accordance with rulesfor unlicensed operation. Since then, the base standardhas been revised (as 802.11-1999), and the workinggroup has published two additional PHY amendments(802.11a and 802.11b). The existing standard and itsamendments describe several WLAN PHYs:

� Infrared at 1 and, optionally, 2 Mb/s� Frequency hopping spread spectrum radio at 1

and, optionally, 2 Mb/s in the 2.4 GHz band

� Direct sequence spread spectrum radios with datarates up to 11 Mb/s in the 2.4 GHz band

� Orthogonal frequency division multiplexing ra-dios in the 5-6 GHz band.

Current work includes extending the MAC andMAC-management functionality to provide expandedinternational operation and roaming, improved sup-port for quality of service, enhanced security, dynamicchannel selection, transmit power control, and stan-dardized communication between 802.11 access points.Work is also proceeding to increase the data rate of oneof the existing PHYs.

Medium Access ControlThe 802.11 standard [3] describes two types of wirelessLANs, an ad hoc network (an independent basic ser-vice set (BSS)) and an infrastructure network (com-prised of infrastructure BSSs of one access point and theassociated mobile stations). An ad hoc wireless LANconsists only of mobile stations. This type of wirelessLAN is often set up for a very specific purpose, such asexchanging files during a single meeting, and its life-time is usually limited. The infrastructure BSS, on theother hand, is typically a long-lived wireless LAN thatintegrates mobile stations into a large network infra-structure through the use of access points (AP) that per-form a bridging function between wired and wirelessLANs. The MAC and MAC-management functions al-low the mobile stations to find other mobile stationsand APs, register with the wireless LAN, request en-cryption and power management services from thewireless LAN, and exchange data with other mobilestations and APs. The MAC and MAC-managementfunctions operate over any and all of the PHYs.

The 802.11 MAC incorporates mechanisms to in-crease the reliability of exchanging information in thewireless medium. The basic access mechanism of 802.11(distributed coordination function (DCF)) is carriersense multiple access with collision avoidance(CSMA/CA). The DCF may be used in either the ad hocor infrastructure wireless LANs. The DCF is quite simi-lar to the CSMA with collision detection (CSMA/CD)used in IEEE 802.3 Ethernet. CSMA/CA works by sens-ing the medium for activity before every transmissionand deferring the transmission if the medium is active.As in 802.3, 802.11 uses a binary exponential backoffmechanism to spread transmission opportunities in timeand minimize the likelihood of subsequent collisions.

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Wireless MAN standards will supporthigh-rate broadband-wireless-accessservices to buildings, mostly throughrooftop antennas, from centralbasestations

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Because simultaneous transmission and receptionon the same channel is more difficult using radio thanusing a wired medium, 802.11 uses a collision avoid-ance mechanism rather than physical collision detec-tion. Every frame transmitted by 802.11 is part of aframe exchange sequence that includes an acknowl-edgement from the destination. Each frame includes in-formation on the duration remaining in the sequence offrames being exchanged. Every station processes thisduration information and maintains a network alloca-tion vector (NAV) indicating how much longer the me-dium will be occupied by the frame exchange. TheNAV is used to reduce the problem caused by “hiddennodes,” in which a station receives only one side of theframe exchange; the potential for this problem makesphysical carrier sense an unreliable means of detectingactivity on the medium. Thus, a station senses the me-dium using both its physical carrier sense and a virtualcarrier sense derived from the NAV. If either of these in-dicate that the medium is in use, a station’s transmis-sion is deferred.

In an infrastructure wireless LAN, the 802.11 stan-dard provides an optional access mechanism, called thepoint coordination function (PCF), where the AP acts asa central coordinator for the wireless LAN, schedulingnearly all of the transmissions. The PCF offers a signifi-cant boost in efficiency since almost all collisions areeliminated. Of course, this efficiency comes at an in-creased cost due to the higher complexity of the AP andits required scheduling algorithms. Based upon thisPCF, the 802.11e task group is proceeding to build im-proved support for quality of service. This work is inthe very early stages of development. The resulting802.11e amendment may be available by early 2002.

PHY: Spread Spectrum, OFDM, and InfraredThe 2.4 GHz PHYs of the current standard describe therequirements for operating in a limited number of areas

of the world: the United States, Canada, Europe (withinthe domain of the European Telecommunications Stan-dards Institute (ETSI)), France, Spain, and Japan. In noother locations can a device that implements the 802.11standard using these PHYs be called compliant with802.11. The 802.11d task group has addressed thisshortcoming of the standard by describing a protocolthat will allow an 802.11 device to receive the regula-tory information required to configure itself properly tooperate anywhere on planet Earth. The manufacturer isstill obligated to obtain any required certifications be-fore allowing its equipment to operate in locations re-quiring certification. In the winter of 2001, 802.11d wasin sponsor ballot, with approval as an amendment tothe 802.11 standard expected in the spring of 2001.

Because a wireless medium offers even less protec-tion from eavesdropping than a wired medium, 802.11incorporates encryption into the MAC. Called thewired equivalent privacy (WEP) mechanism, this en-cryption function is intended to prevent “casual eaves-dropping.” It is not a guaranteed privacy mechanismbut is intended to provide only basic protection to theinformation transmitted over the air. The 802.11e taskgroup is working to improve this capability signifi-cantly. The capability envisioned by 802.11e will pro-vide a simple upgrade path, based on the current WEP,to offer better security for current implementations. Itwill also offer a new encryption function based on therecently selected Advanced Encryption System (AES),the result of a years-long selection process by the U.S.Department of Commerce. The work of 802.11e is in thevery early stages of development and could be com-pleted late in 2001.

Of the three initial PHYs in the 802.11 standard, theinfrared (IR) has seen the least use. This PHY uses base-band pulse position to transmit data at 1 and, option-ally, 2 Mb/s. It provides the greatest physical securityof the 802.11 PHYs, since most walls and windowsblock IR radiation. For the same reason, the number ofAPs required to provide wireless LAN coverage for agiven area is often significantly greater than that re-quired for the radio PHYs. This is the likely reason thatthe IR PHY has been used so infrequently.

The frequency hopping (FH) PHY also providesdata rates of 1 and, optionally, 2 Mb/s. At the timeof development, this PHY was suitable for opera-tion under the U.S. FH spread spectrum rules forthe 2.4 GHz band designated for industry, scien-tific, and medical (ISM) applications; it remains us-able under the rules as liberalized in 2000 to allowwideband FH spread spectrum systems. The 802.11FH PHY provides 79 channels with a channel band-width of 1 MHz. For 1 Mb/s, the modulation usedis two-level Gaussian frequency shift keying(GFSK) with a nominal bandwidth bit period of 0.5.Minimum transmit power is 10 mW, althoughtransmit power may be as high as 1 W. The receiver

50 June 2001

Web SitesIEEE-SA

http://standards.ieee.org

IEEE 802 LAN MAN Standards Committeehttp://ieee802.org

IEEE 802.11 Working Grouphttp://ieee802.org/11

IEEE 802.15 Working Grouphttp://ieee802.org/15

IEEE 802.16 Working Grouphttp://WirelessMAN.org

Regulatory Ombudsmanhttp://ieee802.org/Regulatory

N-WESThttp://nwest.nist.gov

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sensitivity is -80 dBm. For 2 Mb/s, the modulation usedis four-level GFSK.

The direct sequence (DS) PHY, as extended in the802.11b amendment, provides data rates of 1, 2, 5.5, and11 Mb/s. In the United States, this PHY operates underthe DS spread spectrum rules for the 2.4 GHz ISMband. The standard provides for 14 overlapping chan-nels of 22 MHz between 2.4 and 2.5 GHz. Not all chan-nels are usable in all regulatory areas; e.g., onlychannels 1 through 11 may be used in the United States.Channel centers are spaced 5 MHz apart. The 1 and 2Mb/s data rates use a fixed 11-chip Barker sequence tomeet the minimum spreading requirements of the U.S.regulations. The modulation used for these rates is dif-ferential binary phase shift keying (DBPSK) and differ-ential quadrature phase shift keying (DQPSK),respectively. The 5.5 and 11 Mb/s data rates use com-plementary code keying (CCK) as the spreading mech-anism. With CCK, a data symbol is created from 8 databits that select one quaternary (4-level) code from a uni-verse of 216 possible codes. This provides some codinggain, although whether it meets the letter of the DSspread spectrum rules of the regulations is arguable.However, it does pass the regulatory test to determinethe minimum coding gain. The work currently pro-ceeding in the 802.11g task group is to increase the datarates for the DS PHY beyond 20 Mb/s. This task groupis working cooperatively with the Office of Engi-neering Technology (OET) at the U.S. Federal Commu-nications Commission (FCC) to identify potential rulechanges for this band that can increase its utility.

The orthogonal frequency division multiplexing(OFDM) PHY, described in 802.11a, is defined to oper-ate only in the 5-6 GHz Unlicensed National Informa-tion Infrastructure (U-NII) bands in the United States.This band offers three subbands of 100 MHz each, at5.15-5.25, 5.25-5.35, and 5.725-5.825 GHz. Some of thesebands are available in Europe, with similar regulatoryrequirements, though the standard does not define op-eration outside of the United States. The OFDM PHYprovides eight data rates: 6, 9, 12, 18, 24, 36, 48, and 54Mb/s. It uses binary phase shift keying (BPSK), quad-rature phase shift keying (QPSK), 16-QAM (quadratureamplitude modulation), and 64-QAM modulationschemes coupled with forward error correction codingof rates 1/2, 2/3, and 3/4. The OFDM symbol has a pe-riod of 4 ms. It uses 48 data subcarriers and 4 pilotsubcarriers. The data subcarriers are all modulated us-ing the same modulation scheme; the pilot subcarriersare always modulated using BPSK. Products based onthe 802.11a standard are not yet commercially availablebut are expected in 2001.

An 802.11 study group is currently investigating anextension of 802.11a in order to achieve compliancewith ETSI regulations for the corresponding frequencybands in Europe. There is significant industry supportto harmonize 802.11a with a similar ETSI standard

(HIPERLAN/2) so that the market for high-speed wire-less LANs is not fragmented in those bands. The studygroup is investigating means to allow the two stan-dards to coexist in the same band as well as means tomerge the best of both 802.11 and HIPERLAN/2 into asingle new standard. This work is in its early stages,and its outcome is uncertain.

Wireless PANsThe IEEE 802.15 working group for wireless PANs de-velops standards to link pervasive computing devices

that may be portable or mobile and could be worn orcarried by individuals. Communication with nearbystatic devices is also included. The work is exclusivelyin unlicensed bands (primarily at 2.4 GHz), with rangesup to 10 meters and data rates from the kb/s range tobeyond 20 Mb/s. Low power consumption, small size(less than 10 ml), and low cost relative to target devicesare primary considerations. The goal is to developinteroperability standards that have broad market ap-plicability and offer coexistence with wireless LANs.

The group has four authorized projects underway:� Task Group 1 is developing a standard derived

from Bluetooth Specification Version 1.1.� Task Group 2 is developing a recommended prac-

tice for coexistence of wireless LAN and wirelessPAN devices.

� Task Group 3 is developing a high-rate wirelessPAN standard supporting at least 20 Mb/s for ap-plications such as digital imaging and multime-dia.

� Task Group 4 is developing a low-rate wirelessPAN standard supporting rates of 2-200 kb/s withextremely low power consumption and complex-ity for sensors, toys, etc.

History of IEEE 802.15The chain of events leading to the formation of IEEE802.15 began in June 1997 when the IEEE Ad Hoc Wear-ables Standards Committee was initiated during theIEEE New Opportunities in Standards Committeemeeting in June 1997. The purpose of the Committeewas to “encourage development of standards for wear-able computing and solicit IEEE support to developstandards.” The wearables committee met three moretimes, agreed to focus on wireless PAN standards, anddecided to approach IEEE 802. IEEE 802.11 welcomedthe initiative and launched the Wireless Personal AreaNetwork Study Group within 802.11 in March 1998. Atthe time, no other wireless PAN initiatives had been

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Wireless LAN standards support usersroaming through homes, officebuildings, campuses, hotels, airports,restaurants, cafes, etc.

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publicized. However, by March 1999, when the studygroup and 802.11 submitted a PAR to 802, theBluetooth™ special interest group (SIG) had over 600adopter companies and HomeRFTM had over 60. ThePAR was approved and placed in the hands of a newWorking Group 802.15. Bob Heile was named chairand continues in that position. The working group has74 members.

Wireless PAN Derived from BluetoothIEEE 802.15’s Task Group 1 is deriving a draft standardfrom the Bluetooth Specification Version 1.1 under IEEEPAR 802.15.1. Bluetooth is a technology for smallform-factor, low-cost wireless communication and net-working between computers, mobile telephones, andother portable devices. The specification supports datarates up to 721 kb/s as well as three voice channels andtargets low power consumption: 30 µA in “hold” modeand 8-30 mA (less than 0.1 W) during transmission.Bluetooth technology will provide an easy and robustway for a variety of mobile devices to communicate withone another and remain synchronized without the needfor wires or cables.

Figure 1 shows the protocol stacks in the OSI seven-layernetwork model and their relationship to the Bluetooth refer-ence model as it pertains to the 802.15.1 standard.

Wireless PAN CoexistenceTask Group 2 is developing, under IEEE PAR 802.15.2, adraft recommended practice for coexistence of wirelessLAN and wireless PAN devices.

In the context of this project, multiple wireless de-vices are said to “coexist” if they can be collocated with-out significantly impacting their performance. Since the

802.15.1 standard addresses the same license-exempt 2.4GHz band as 802.11’s DS and FH PHYs, mutual interfer-ence is a concern when they operate near each other.Task Group 2 is developing a coexistence model thatquantifies the effect of the mutual interference, with co-existence mechanisms to follow. The final model willconsist of four elements: PHY, MAC, RF propagation,and data traffic. The coexistence model is intended topredict the effects of a nearby 802.11 network on the per-formance of an 802.15.1 network, and vice versa. TaskGroup 2 also plans to study the high-rate wireless PANbeing developed in Task Group 3.

High-Rate Wireless PANTask Group 3 is developing a standard for a high-ratewireless PAN under IEEE PAR 802.15.3, approved inMarch 2000. The goal is to support data rates of at least20 Mb/s for applications such as digital imaging andmultimedia. In a break with 802 tradition, the plan is tocreate a second MAC within the working group.

In November 2000, six candidate proposals for thePHY and four for the MAC were reduced to a singleworking version of the standard. In January 2001, aneight-state, trellis-code modulated, 16/32/64-QAMPHY operating in the 2.4 GHz band was selected. Theproposed system provides adaptive data rates from22-55 Mb/s. The group remains interested in additionalPHYs, possibly operating in unlicensed 5 GHz bands.

Low-Rate Wireless PANFollowing the December 2000 approval of PAR 802.15.4,Task Group 4 held its first meeting and began by assess-ing eight contributions in response to a call for applica-tions. Like Task Group 3, Task Group 4 plans its own

52 June 2001

Application

Presentation

Session

Transport

Network

7

6

5

4

3

2

1

DataLink

Physical

Logical LinkControl (LLC)

Medium Access(MAC)

Physical(PHY)

ISO OSILayers

IEEE 802Standards

IEEE 802.15.1Bluetooth WPAN

Applications/Profiles

Other

LLC RFCOMMTCS SDP

Audio Control

Baseband

Physical Radio

Link Manager

Logical Link ControlAdaptation Protocol(L2CAP)

Figure 1. Mapping of ISO OSI model to scope of IEEE 802.15.1 WPANTM standard.

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unique MAC. Potential applications in-clude sensor and automation needs,interactive toys, and location track-ing for smart tags and badges.

Broadband WirelessAccess StandardsThe IEEE Working Group802.16 on broadband wirelessaccess (BWA) standards de-velops standards and recom-mended practices to supportthe development and deploy-ment of fixed broadband wirelessaccess systems. It refers to its productsas the IEEE 802.16 family of Wireless-MAN™ standards for wireless MANs. The work-ing group’s projects are cosponsored by the IEEEMicrowave Theory and Techniques (MTT) Society aswell as the IEEE Computer Society.

Working group 802.16 is addressing applications ofwireless technology to link commercial and residentialbuildings to high-rate core networks and thereby provideaccess to those networks; this link is sometimes knowncolloquially as the “last mile,” though the term “firstmile” is more appropriate for data flowing out of the cus-tomer site. The work has aimed at a point-to-multipointtopology with a cellular deployment of basestations, eachtied into core networks and in contact with fixed wireless

subscriber stations. The subscriber sta-tions typically include rooftop-

mounted antenna/radio units con-nected to indoor network interface

units, although in some casesboth units could be indoors orboth outdoors. Initial work hasaimed at businesses, withmuch of the market focus onsmall-to-medium-sized enter-

prises. Attention has increas-ingly turned toward residential

opportunities, particularly at thelower frequencies.

The working group has three activeprojects to develop air interface standards.

Task Group 1 is completing the IEEE 802.16 Stan-dard Air Interface for Fixed Broadband Wireless Access Sys-tems. This project addresses a PHY to support licensedbands from 10-66 GHz. The document will include an ac-companying MAC. The standard is not yet final, but thedraft is stable and in working group letter ballot.

Task Group 3 is developing a PHY for licensedbands from 2-11 GHz and the supporting MAC exten-sions. This work is planned as amendment 802.16a tothe baseline 802.16 standard. Task Group 1 and TaskGroup 3 projects are 802’s only work targeted at li-censed bands. 802.16’s newest project, led by TaskGroup 4, looks at license-exempt applications in the 5-6

June 2001 53

Scope of Standard

ATM and PacketConvergence Sublayers

MAC Sublayer - Common Part

Security Sublayer

PHY Layer

Data/Control Plane

SSCS SAP

MAC SAP

PHY SAP

Management Entity

Service SpecificsConvergence Sublayers

Management Entity

MAC Sublayer - Common Part

Security Sublayer

Management Entity

PHY Layer

Management Plane

MA

CP

HY

Net

wor

k M

anag

emen

t Sys

tem

Figure 2. IEEE 802.16 Reference Model and Protocol Stack.

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GHz region, sometimes known as U-NII bands due totheir U.S. designation. Again, the plan is for an amend-ment (802.16b) to the base 802.16 standard, with a PHYand with MAC extensions.

Finally, Task Group 2 is completing the IEEE802.16.2 Recommended Practice for Coexistence of FixedBroadband Wireless Access Systems. The emphasis is onsupporting deployment of systems built according tothe Task Group 1 standard, primarily in the range of23.5 to 43.5 GHz. This is the first document to havecompleted 802.16 working group letter ballot, and pub-lication is anticipated for the summer of 2001.

History of IEEE 802.16The activities of 802.16 were initiated by activity of theNational Wireless Electronics Systems Testbed(N-WEST) at the U.S. National Institute of Standardsand Technology. N-WEST organized a kickoff meetingat the 1998 IEEE Radio and Wireless Conference(RAWCON). The group of 45 accepted an invitation tomeet along with IEEE 802 in November, and 802 thenapproved the formation of a study group under chairRoger Marks. That group met twice and wrote the TaskGroup 1 PAR. The working group’s Session #1 tookplace in July 1999. At that meeting, the Task Group 2PAR was approved by 802; Leland Langston chairedthe project. In November 1999, 802.16 created thestudy group that, under the leadership of BrianKiernan, developed the Task Group 3 PAR that wasapproved in March 2000. At that time, a study groupfor the license-exempt bands was set up under chairDurga Satapathy, who developed the acronymWirelessHUMANTM (Wireless High-Speed UnlicensedMetropolitan Area Network) to describe the standardeffort. The Task Group 3 PAR was approved in Decem-ber 2000. The original Task Group 1, Task Group 3, andTask Group 4 chairs remain in place; in addition, CarlEklund and Jay Klein serve as MAC and PHY chairs, re-spectively, in Task Group 1. The Task Group 2 project ischaired by Phil Whitehead, following a brief stint byAndy McGregor. At the time of this report, 802.16 has137 members, 74 potential members, and 59 official ob-

servers. Its work has been closely followed; for exam-ple, the IEEE 802.16 Web site received over 2.8 millionfile requests in the year 2000.

IEEE 802.16 maintains close working relationshipwith standards bodies in the ITU and the ETSI, particu-larly with the HIPERACCESS and HIPERMAN pro-grams of ETSI’s Broadband Radio Access Networks(BRAN) project and with ETSI Working Group TM4.

The technical accomplishments of IEEE 802.16 aresummarized below. Several publications provide addi-tional detail [5], [6].

Medium Access ControlThe 802.16 working group follows the traditional 802 ap-proach of developing multiple PHY options supportedby a common MAC. The MAC was developed by TaskGroup 1 along with the original 10-66 GHz PHY. Al-though the service requirements of the other air interfaceprojects differ, the original MAC design is flexibleenough to support, with extensions, all three projects.

The 802.16 MAC (Figure 2) draws from thedata-over-cable (DOCSIS) standard [7] that has been suc-cessfully deployed in hybrid-fiber coaxial (HFC) cablesystems, which have a similar point-to-multipoint archi-tecture. However, the MAC protocol engine is a new de-sign. It is a connection-oriented MAC able to tunnel anyprotocol across the air interface with full quality-of-ser-vice (QoS) support. Asynchronous transfer mode (ATM)and packet-based convergence layers provide the inter-face to higher protocols. While extensive bandwidth allo-cation and QoS mechanisms are provided, the details ofscheduling and reservation management are left unstan-dardized and provide an important mechanism for ven-dors to differentiate their equipment.

An important MAC feature is the option of grantingbandwidth to a subscriber station rather than to the in-dividual connections it supports. This provides the op-tion of allowing a smart subscriber station to manageits bandwidth allocation among its users. This canmake for more efficient allocation.

The 802.16 MAC is versatile and flexible. For exam-ple, it supports several multiplexing and duplexing

schemes; some possibilities are de-scribed below. In general, thepoint-to-multipoint architecture isimplemented with a controllingbase station interacting with manysubscriber stations. The downlinkfrom the base station may bechannelized and sectorized but,within a channel and sector, all sub-scriber stations receive the samesignal and retain only messages ad-dressed to them. The uplink fromthe subscriber stations is shared,with access assigned by thebasestation.

54 June 2001

Frame

Broadcast

Full Duplex Capable User

Half Duplex Terminal #1

Half Duplex Terminal #2

Downlink

Uplink

Figure 3. Example of Burst FDD Bandwidth Allocation.

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10-66 GHz PHYThe 10-66 GHz PHY assumes line-of-sight propagationwith no significant concern over multipath propaga-tion. Either of two basic modes may be used. The con-tinuous mode uses frequency division duplexing(FDD), with simultaneous uplink and downlink onseparate frequencies. A continuous time division multi-plexed downstream allows a powerful concatenatedcoding scheme with interleaving. The Burst Mode al-lows time division duplexing (TDD), with the uplinkand downlink sharing a channel but not transmitting si-multaneously. This allows dynamic reassignment of theuplink and downlink capacity. This mode also allows“burst FDD,” which supports half-duplex FDD sub-scriber stations that do not simultaneously transmit andreceive (see Figure 3) and may therefore be less expen-sive. Both TDD and Burst FDD support adaptive burstprofiles in which modulation (QPSK, 16-QAM, or64-QAM) and coding may be dynamically assigned on aburst-by-burst basis. This real-time tradeoff of capacityversus robustness again offers to vendors opportunitiesto implement sophisticated algorithms to differentiatetheir approach while retaining interoperability.

The choice of continuous or burst mode may de-pend on the available channel allocations and otherregulatory issues. Because the standard is intended forworld-wide use, the channelization is left flexible. Rec-ommendations are included, however. These suggestsymbols rates as high as 43.4 MBd in a 50 MHz channel,which, assuming 64-QAM, translates to data rates ashigh as 260 Mb/s in that channel.

Licensed Bands, 2-11 GHzTask Group 3 has been developing a standard for 2 to 11GHz BWA. In the United States, the primary targetedfrequencies are in the Multichannel Multipoint Distri-bution Service (MMDS) bands, mostly from 2.5-2.7GHz. World-wide, 3.5 and 10.5 GHz are likely applica-tions. Because non-line-of-sight operation is practicaland because of the lower component costs, these bandsare seen as good prospects for residential andsmall-business services. The spectrum availability issuitable to these uses. Task Group 1 has considered anumber of PHY layer approaches and was scheduled toselect a baseline draft in the spring of 2001. MAC en-hancements are also under development.

Unlicensed Bands, 5-6 GHzIn order to provide for rapid development, Task Group 4is working under a narrow charter. It is tasked to developa PHY layer based on the 802.11a OFDM and/orHIPERLAN/2 PHYs and is developing MAC enhance-ments. It works closely with Task Group 3 to ensure har-mony. Coordination of basestations under independentoperators in unlicensed spectrum is an important issuefacing this group. One proposal is to consider an optionalmesh architecture in addition to a point-to-multipoint to-pology. Some participants have proposed MAC enhance-

ment to support a mesh; this is testimony to the flexibil-ity of the 802.16 MAC.

Coexistence and Regulatory Issues Across 802As 802.11 products proliferate at 2.4 GHz, the prospect ofa large number of 802.15 products operating in the samespaces and in the same unlicensed bands prompts sig-nificant concern about coexistence. In the 5-6 GHz

bands, products based on the 802.11a OFDM standardare expected soon. 802.15’s Task Group 3 has had discus-sions about a PHY in the same bands, and 802.16’s TaskGroup 4 is firmly engaged in developing a fixed wirelessaccess standard at the same frequencies. Meanwhile,802.11 is working with European and Japanese stan-dards groups with the goal of harmonizing the world’s 5GHz wireless LAN standards or, failing that, to ensurethat the systems can coexist. These overlaps havebrought about discussions of a coexistence coordinatinggroup that would interact with all of 802’s developmentprojects addressing those unlicensed bands.

The IEEE 802 wireless projects have also increas-ingly focussed on radio regulations. Again, the unli-censed bands cause the most concern, because theoperation rules strongly impact the allowed technologyand vary from country to country. In March 2000, theSEC assigned regulatory matters to a regulatory om-budsman and elected Vic Hayes to fill this position. Theregulatory ombudsman prepares and submits unified802 positions in regard to spectrum sharing and in sup-port of harmonized global rules. Much of the focus ison the World Radiocommunications Conference(WRC) and the ITU-R. For example, the WRC in 2003has three agenda items related to extension, sharingstudies, and harmonization of the 5 GHz band.

ApplicationsThe IEEE 802 wireless standards program builds on thesuccess of IEEE 802.3 (Ethernet), since much of the successof the Internet is based on the availability of low-costEthernet equipment. In 2000, the Dell’Oro Group pro-jected revenue from Ethernet switch equipment to growat 20% per year to over $23 billion in 2004. Dell’Oro alsoprojected 10 Gb/s Ethernet, the most advanced Ethernettechnology, to reach revenue of $1 billion by 2004 and said“One of the most important trends in networking is theextension of the economics (i.e., price/performance) ofthe LAN to the metro and wide area (MAN/WAN).”

While IEEE 802.15-based products are not yet avail-able, they promise to extend the wireless Internet to a

June 2001 55

Wireless PAN standards will supportshort-range links among computers,mobile telephones, and otherconsumer electronics devicesthat are worn or carried

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wide range of devices. One driver will be cost, asBluetooth radios are often projected to fall from the $20range to around $5. Another critical success factor islow power consumption, which will significantly ex-pand the range of applications as compared to currentwireless technology. IEEE 802.15 is addressing the trueconsumer electronics industry, from mobile telephonesand handheld devices to sensors and toys. The numberof units deployed based on the 802.15 standards may beenormous. For example, market research firm CahnersIn-Stat Group has projected over 670 millionBluetooth-enabled devices world-wide by 2005.

The IEEE 802.11 wireless LAN standard was initiallypublished in 1997, with the important 802.11a and 802.11bamendments in 1999. It has already been emulatingEthernet’s success, demonstrating that standardizationdoes open new markets. As a recent publication noted,“The curve of wireless interest over time shows three keyturning points. The first was the finalization of the IEEE802.11b standard for 11 Mb/s direct-sequence radios. Therate itself wasn’t the key, though. Standardization was.This allowed interoperability among vendors and helpedbring the cost down to where it is today, with a bill of ma-terials of less than $40 for the radio” [8]. This has dramati-cally shifted wireless LAN applications. While theoriginal target was primarily businesses that wanted tosave on LAN installation costs, 802.11 products are nowsignificantly penetrating home networking markets.Even more significant is the surge in public deployments,a trend strong enough to receive recent treatment in themainstream press. The New York Times, in a major articleon the topic, wrote, “Wireless high-speed Internet access,a longtime dream of the technophile and business trav-eler, is finally arriving at hundreds of access points inpublic and private places across the United States. With alaptop computer equipped with a wireless card, anyonewithin a few hundred feet or so of one of these accesspoints, or hot spots, can tap into a wireless network thatis in turn connected to the Internet via a broadband con-nection. The user can then send e-mail or surf the Web atspeeds in the megabit range... By late this year, industryexperts say, the hundreds of hot spots will become thou-sands as service providers and entrepreneurs install thenecessary equipment—generally, a small transceiverand a broadband connection—in all major airport termi-nals, sports arenas, and other business and consumersites. By sometime next year, one company expects tohave access points in 5,000 Starbucks stores. Some ofthese services may be free, run by volunteers intriguedby the community-building prospects of wireless net-working... But most access points are and will be com-mercial, run by companies that will charge for theservices” [9]. An accompanying article on the standardsaid “The protocol called IEEE 802.11b has been put inplace by so many companies offering wirelessshort-range networks that it is emerging as the standardfor the field” [10]. The success of 802.11 products is based

not only on the price drops but also on the increasingubiquity of the service, a result that is also driven by stan-dardization. The New York Times expressed this by quotingone industry manager as saying that this new wireless ac-cess is about “giving you the ability to roam from one net-work to another and be blissfully ignorant” of thetechnical intricacies and quoted a user as saying, “It’s thekind of thing that’s such a fundamental capability that itstarts feeding on itself.” With the user of a portable com-puter now able to access the Internet at work, home, res-taurants, cafes, hotels, and airports, all with the sameequipment and all at blazing speed, the wireless Internetis arriving, and it is based on IEEE 802 standards.

One major roadblock remains to be addressed in orderto complete this picture of a wireless Internet based onIEEE 802. How will all of those access points be connectedwith fast access to the Internet itself? Cable modems pro-vide service in some residential neighborhoods but areavailable in very few commercial districts; furthermore,their uplink capacity may be too narrow for this purpose.Digital subscriber line (DSL) can provide broadband ser-vice but is limited in range. Fiberoptic links offer verybroadband rates, but only about 5% of U.S. commercialbuildings have access to fiberoptic links, and the cost oflaying cable is extremely high. In many cases, the mostefficient means of reaching the many widely dispersedsites providing license-exempt wireless Internet accessbased on IEEE 802 standards will be fixed broadbandwireless access. If IEEE 802 maintains its record of suc-cess in ushering technology into the economy and intosociety, then IEEE 802.16 will be the tool that makes fixedbroadband wireless access a mainstream application.IEEE 802 will have unleashed the wireless Internet.

AcknowledgmentsThe authors appreciate manuscript review from Don-ald DeGroot, Vic Hayes, Brian Kiernan, David R. Smith,and Claude Weil.

References[1] Overview and Guide to the IEEE 802 LMSC. Available:

http://ieee802.org/overview2000.pdf[2] Operating Rules of IEEE Project 802 LAN MAN Standards Com-

mittee. Available: http://ieee802.org/rules.pdf[3] B. O’Hara and A. Petrick, IEEE 802.11 Handbook: A Designers Guide.

IEEE Standards Press, 1999.[4] T. Siep, An IEEE Guide: How to Find What You Need in the Bluetooth

Spec. Piscataway, NJ: IEEE Press, 2000.[5] J. Foerster and G. Sater, “LMDS Standards Architectural Issues,”

2000 IEEE Wireless Communications and Networking Conf.[6] B. Petry, “Broadband wireless access: High rate, point to

multipoint, fixed antenna systems,” in The RF and MicrowaveHandbook. Boca Raton, FL: CRC, 2001, pp. 2-41 to 2-51.

[7] Radio Frequency Interface Specification (version 1.1), Data-Over-CableService Interface Specifications, Cable Television Laboratories, Inc.

[8] P. Mannion, “Ad hoc networks ascend to the airwaves,” EE Times,pp. 85-86, Feb. 26, 2001.

[9] G. Fleishman, “The Web, without wires, wherever,” The New YorkTimes, Feb. 22, 2001.

[10] G. Fleishman, “Protocol wars: A standard emerges, but watch out forthose microwave ovens,” The New York Times, Feb. 22, 2001.

56 June 2001