IEEE Communications Magazine • June 2009840163-6804/09/$25.00 © 2009 IEEEINTRODUCTIONThe growing demand for mobile Internet andwireless multimedia applications has motivatedthe development of broadband wireless-accesstechnologies in recent years. Mobile WiMAXwas the first mobile broadband wireless-accesssolution based on the IEEE 802.16e-2005 stan-dard [1] that enabled convergence of mobile andfixed broadband networks through a commonwide-area radio-access technology and flexiblenetwork architecture. The mobile WiMAX airinterface utilizes orthogonal frequency divisionmultiple access (OFDMA) as the preferred mul-tiple-access method in the downlink (DL) anduplink (UL) for improved multipath perfor-mance and bandwidth scalability. Since January2007, the IEEE 802.16 Working Group hasembarked on the development of a new amend-ment of the IEEE 802.16 standard (i.e., IEEE802.16m) as an advanced air interface to meetthe requirements of the International Telecom-munication Union — Radiocommunication/International Mobile Telecommunications (ITU-R/IMT)-advanced for fourth-generation (4G)systems, as well as the next-generation mobilenetwork operators.Depending on the available bandwidth andmulti-antenna mode, the next-generationmobile WiMAX will be capable of over-the-airdata-transfer rates in excess of 1 Gb/s and sup-port a wide range of high-quality and high-capacity IP-based services and applicationswhile maintaining full backward compatibilitywith the existing mobile WiMAX systems topreserve investments and continuing to supportfirst-generation products. There are distinctivefeatures and advantages such as flexibility andthe extensibility of its physical and medium-access-layer protocols that make mobileWiMAX and its evolution more attractive andmore suitable for the realization of ubiquitousmobile Internet access.The next-generation mobile WiMAX willbuild on the success of the existing WiMAXtechnology and its time-to-market advantageover other mobile broadband wireless accesstechnologies. In fact, all OFDM-based, mobilebroadband access technologies that have beendeveloped lately exploit, enhance, and expandfundamental concepts that were originally uti-lized in mobile WiMAX.The IEEE 802.16m will be suitable for bothgreen-field and mixed deployments with legacymobile stations (MSs) and base stations (BSs).The backward compatibility feature will allowsmooth upgrades and an evolution path for theexisting deployments. It will enable roamingand seamless connectivity across IMT-advancedand IMT-2000 systems through the use ofappropriate interworking functions. In addi-tion, the IEEE 802.16m system utilizes multi-hop relay architectures for improved coverageand performance. This article briefly describesthe salient technical features of IEEE 802.16mand the potential for successful deployment ofthe next generation of mobile WiMAX in2011+.ABSTRACTThe growing demand for mobile Internetand wireless multimedia applications has moti-vated the development of broadband wireless-access technologies in recent years. MobileWiMAX has enabled convergence of mobileand fixed broadband networks through a com-mon wide-area radio-access technology andflexible network architecture. Since January2007, the IEEE 802.16 Working Group hasbeen developing a new amendment of the IEEE802.16 standard (i.e., IEEE 802.16m) as anadvanced air interface to meet the require-ments of ITU-R/IMT-advanced for 4G systems,as well as for the next-generation mobile net-work operators.Depending on the available bandwidth andmulti-antenna mode, the next-generation mobileWiMAX will be capable of over-the-air data-transfer rates in excess of 1 Gb/s and of support-ing a wide range of high-quality andhigh-capacity IP-based services and applicationswhile maintaining full backward compatibilitywith the existing mobile WiMAX systems to pre-serve investments and continuing to supportfirst-generation products. This tutorial describesthe prominent technical features of IEEE802.16m and the potential for successful deploy-ment of the next generation of mobile WiMAXin 2011+.WIMAX UPDATESassan Ahmadi, Intel CorporationAn Overview of Next-Generation Mobile WiMAX TechnologyAHMADI LAYOUT 5/15/09 1:10 PM Page 84IEEE Communications Magazine • June 200985IEEE 802.16M SYSTEMREQUIREMENTS ANDEVALUATION METHODOLOGYFull backward compatibility and interoperabilitywith the reference system is required for IEEE802.16m systems, although the network operatorcan disable legacy support in green-field deploy-ments. The reference system is defined as a sys-tem that is compliant with a subset of the IEEE802.16e-2005 [1] features as specified by theWiMAX Forum mobile system profile, Release1.0 [2]. The backward compatibility featureensures a smooth migration from legacy to newsystems without any significant impact on theperformance of the legacy systems, as long asthey exist. Furthermore, the requirements forIEEE 802.16m were selected to ensure competi-tiveness with the emerging 4G radio-access tech-nologies while improving and extending existingfunctionalities of the reference system.The IMT-advanced requirements defined andapproved by ITU-R/Working Party 5D and pub-lished as Report ITU-R M.2134 [3] are referredto as target requirements in the IEEE 802.16msystem requirement document and will be evalu-ated based on the methodology and guidelinesspecified by Report ITU-R M.2135 [4]. Thebaseline performance requirements will be eval-uated according to the IEEE 802.16m evaluationmethodology document [5]. A careful examina-tion of the IMT-advanced requirements revealsthat they are a subset of, and less stringent than,the IEEE 802.16m system requirements; there-fore, the IEEE 802.16m standard can qualify asan IMT-advanced technology. Table 1 summa-rizes the IEEE 802.16m baseline system require-ments and the corresponding requirementsspecified by Report ITU-R M.2134 [3]. In thenext sections, we briefly discuss how theserequirements can be met or exceeded throughthe extension and enhancements of the legacy-system functional features.The IEEE 802.16m systems are expected tomeet all service requirements for IMT-advancedsystems as specified by Report ITU-R M.1822[7], where compliance is verified through inspec-tion [4].The IEEE 802.16m evaluation methodologydocument [5] provides simulation parametersand guidelines for evaluation of the candidateproposals against the IEEE 802.16m systemrequirements [6]. The evaluation scenarios andassociated parameters specified in
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