I ReferencesII IntroductionII-A History of 802.16 standardsII-B Network ArchitectureII-C Scope of the StandardII-D Hand-off mechanismIII Physical LayerIII-A Channel characteristicsIII-B PerformanceIII-C OFDMIV Media Access Control LayerIV-A Frame structure and Access mechanismIV-B Network Entry ProcessIV-C Connection and servicesIV-D Message formatV Advanced features and Related activitiesV-A Advanced 802.16 featuresV-B Implementation, deployment and other research activitiesVI Announcement1EE228a - Lecture 6 - Spring 2006IEEE 802.16 / WiMAXLectured by Shyam Parekh,Scribed by Jiwoong Lee (porce@eecs)AbstractIEEE 802.16 is an emerging wireless MAN technology. Although it was originally designed to provide wireless last mile/firstmile(rhetoric expressions for access networks) deployment in a MAN, it can also be used for end-user access as an alternative tothe IEEE 802.11 family. Mobility support at vehicular speeds is provided by the most recent standard. In this lecture, we reviewthe history of IEEE 802.16 standardization, physical layer fundamentals and media access control operations.I. REFERENCESThis lecture is based on following standards and technical references. The first two documents are IEEE standards. Amongthem, the first one is for fixed wireless communications and the second one is an amendment for mobile communications. Intel’sWhite papers are good tutorials. The author of the final reference was involved in the standardization process of IEEE 802.16.• IEEE 802.16-2004 (802.16REVd)• IEEE 802.16-2005 (802.16e)• Intel’s White papers, 2004 (http://www.intel.com/technology/itj/2004/volume08issue03/)• IEEE Standard 802.16: A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access, June 2002• Broadband Wireless Access with 802.16/WiMAX: Current Performance Benchmarks and Future Potential, A. Ghosh et al.,IEEE Communication Magazine, Feb 2005• Wireless Communication Standards: A Study of IEEE 802.11, 802.15, and 802.16, T. Cooklev, 2004II. INTRODUCTIONSimilarly to Wi-Fi, WiMAX is an industrial consortium to promote the use of IEEE 802.16 technology. The activities ofWiMAX is still going on. Interoperability, features and applications are the main concerns of that consortium.Many companies in industry are interested in WiMAX technology and its products. In comparison to IEEE 802.11 LANfamily technologies, WiMAX is a Metropolitan Area Network(MAN) standard and plays a bigger role in large scale operatornetworks. In the sense of geographical coverage and overall throughput, IEEE 802.16 has good potential for operation. As oneexample, Lucent is building a base station(BS) and integrating overall networks including backhaul connections and managementplane.In this discussion, we are interested in Ghz range spectrum. Side: Another interesting spectrum ranges from 1014to 1015Hz- free optic spectrum.A. History of 802.16 standards• In 1998, The National Institute of Standards and Technology (NIST) started looking for a different wireless application andheld the first initiative meeting. By the time of the first standardization of 802.16 (in Dec 2001), systems were alreadyavailable. In fact, many basic ideas of 802.16 were borrowed from DOCSIS/HFC(a cable modem technology) and applied tothe wireless setting, although the physical layer specification is different. There is a good analogy to note: Wi-Fi : Ethernet= WiMAX : DOCSIS/HFC.• 802.16 is for Line-of-Sight(LOS) applications utilizing 10-66Ghz spectrum. Although this spectral range has a severeatmospheric attenuation, it is suitable for connections in the operator network between two nodes with high amounts ofbandwidth because many base stations are deployed at elevated positions from the ground. This is not suitable for residentialsettings because of the Non-Line-of-Sight(NLOS) characteristics caused by rooftops or trees.• 802.16a is an amendment for NLOS utilizing 2-11Ghz. Good for Point-to-Multipoint(PMP) and home application. OrthogonalFrequency Division Multiplexing(OFDM) is newly adopted.• 802.16-2004 revises and replaces 802.16, 802.16a, and 802.16REVd. This is the completion of the essential fixed wirelessstandard. Some operators are already interested in integrating this with the Cellular backhaul. After some political debates,it was decided to support not mobile but fixed wireless and nomadic communications. Nomadicity is this: Users are attachedto the network. After a session completes, they can move to a different network. But the session should be re-established(possibly including the authentication) from scratch; it does not have a hand-off mechanism.• 802.16e is a MAC/PHY enhancement for supporting truly mobile communications at vehicular speeds. This supports a fullhand-off. A user’s session is maintained when he moves around.2B. Network ArchitectureBackplane is implemented as either a bridge, a router or a host. When the Service Data Unit(SDU) comes into the Convergencesublayer, the Classifier in Convergence sublayer can classify the type of the traffic (eg. voice, web surfing, ATM CBR ...) andmap it into a particular Connection ID(CID). In turn each CID is referred to a certain specific profile. Each profile describesmodulation scheme, Forward Error Correction(FEC) scheme, etc.. Once the CID is well defined between both communicationparties (such as a Base station(BS) and a Subscriber Station(SS)), the non-changing payload header information(such as ATMcell header or IP header) can be suppressed by Payload Header Suppression(PHS).Fig. 1. ArchitectureC. Scope of the StandardThe scope of 802.16 standard covers PHY, Service Access Point(SAP), Security sublayer, MAC Common Part Sublayer(CPS),and Service-specific Convergence Sublayer(CS).D. Hand-off mechanismThe hand-off procedure of 802.16 is not radically different from that of other well-known wireless technologies. Based onSignal-to-Noise ratio, the SS sends a hand-off request to the serving BS. The serving BS negotiates the bandwidth and QoS withpossible target BSs on behalf of the SS. After receiving the confirmation from one of them, the serving BS notifies the SS ofhand-off response. The SS starts to use the target BS.III. PHYSICAL LAYERIf 2-11Ghz is of interest, utilizing OFDM gives several benefits. In recent standards there are optional beneficial features. Forexample, Adaptive Antenna System(AAS) is a directional signal processing technique which is able to highlight the signal froma certain direction
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