Wi max tutorial 2006

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Wi max tutorial 2006

  1. 1. WiMAX Tutorial Luca Dell’Anna November 22nd, 2006 luca@dellanna.com
  2. 2. This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "WiMAX" SummaryWiMAX Tutorial............................................................................................................ 1 1. Introduction ......................................................................................................................... 3 2. Technical overview............................................................................................................... 3 3. Uses for WiMAX.................................................................................................................... 3 4. Broadband Access ................................................................................................................ 4 5. Mobile applications.............................................................................................................. 4 6. Spectrum Allocations for WiMAX........................................................................................... 4 7. Standards............................................................................................................................. 5 7.1. IEEE 802.16e ................................................................................................................. 5 7.2. HIPERMAN..................................................................................................................... 5 7.3. WiBro ........................................................................................................................... 5 8. Associations......................................................................................................................... 6 8.1. WiMAX Forum ............................................................................................................... 6 8.2. WiMAX Spectrum Owners Alliance................................................................................. 6 9. Competing technologies ....................................................................................................... 6 9.1. LTE ............................................................................................................................... 6 9.2. EV-DO ........................................................................................................................... 7 9.3. Wi-Fi............................................................................................................................. 7 9.4. Mobile Broadband Wireless Access ............................................................................... 7 10. Deployment...................................................................................................................... 7 10.1. Australia................................................................................................................... 7 10.2. Austria...................................................................................................................... 7 10.3. Brazil........................................................................................................................ 7 10.4. Canada ..................................................................................................................... 7 10.5. Croatia...................................................................................................................... 8 10.6. Denmark................................................................................................................... 8 10.7. Ireland...................................................................................................................... 8 10.8. Finland ..................................................................................................................... 8 10.9. France ...................................................................................................................... 8 10.10. New Zealand............................................................................................................. 8 10.11. Georgia..................................................................................................................... 8 10.12. Slovakia.................................................................................................................... 8 10.13. UK ............................................................................................................................ 8 10.14. USA........................................................................................................................... 8 10.15. Italy.......................................................................................................................... 9 11. References ....................................................................................................................... 9
  3. 3. 1. IntroductionWiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum, formed in June 2001 topromote conformance and interoperability of the IEEE 802.16 standard, officially known as WirelessMAN. The Forumdescribes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as analternative to cable and DSL".2. Technical overviewThe definition: "WiMAX is not a technology, but rather a certification mark, or stamp of approval given to equipmentthat meets certain conformity and interoperability tests for the IEEE 802.16 family of standards. A similar confusionsurrounds the term Wi-Fi (Wireless Fidelity), which like WiMAX, is a certification mark for equipment based on adifferent set of IEEE standards from the 802.11 working group for wireless local area networks (WLAN). Neither WiMAX,nor Wi-Fi is a technology but their names have been adopted in popular usage to denote the technologies behindthem. This is likely due to the difficulty of using terms like IEEE 802.16 in common speech and writing."WiMAX is a term coined to describe standard, interoperable implementations of IEEE 802.16 wireless networks, in arather similar way to Wi-Fi being interoperable implementations of the IEEE 802.11 Wireless LAN standard. However,WiMAX is very different from Wi-Fi in the way it works.In Wi-Fi the media access controller (MAC) uses contention access — all subscriber stations that wish to pass datathrough a wireless access point (AP) are competing for the APs attention on a random interrupt basis. This can causesubscriber stations distant from the AP to be repeatedly interrupted by closer stations, greatly reducing theirthroughput. This makes services such as Voice over IP (VoIP) or IPTV, which depend on an essentially constant Qualityof Service (QoS) depending on data rate and interupptibility, difficult to maintain for more than a few simultanteoususers.In contrast, the 802.16 MAC uses a scheduling algorithm for which the subscriber station need compete once (for initialentry into the network). After that it is allocated an access slot by the base station. The time slot can enlarge andcontract, but remains assigned to the subscriber station which means that other subscribers cannot use it. The 802.16scheduling algorithm is stable under overload and over-subscription (unlike 802.11). It can also be more bandwidthefficient. The scheduling algorithm also allows the base station to control QoS parameters by balancing the time-slotassignments among the application needs of the subscriber stations.The original WiMAX standard (IEEE 802.16) specified WiMAX for the 10 to 66 GHz range. 802.16a, updated in 2004 to802.16-2004 (also known as 802.16d), added specification for the 2 to 11 GHz range. 802.16d (also known as "fixedWiMAX") was updated to 802.16e in 2005 (known as "mobile WiMAX"). and uses scalable orthogonal frequency-divisionmultiplexing (OFDM) as opposed to the OFDM version with 256 sub-carriers used in 802.16d. This brings potentialbenefits in terms of coverage, self installation, power consumption, frequency re-use and bandwidth efficiency.802.16e also adds a capability for full mobility support. The WiMAX certification allows vendors with 802.16d productsto sell their equipment as WiMAX certified, thus ensuring a level of interoperability with other certified products, aslong as they fit the same profile.Most interest will probably be in the 802.16d and .16e standards, since the lower frequencies suffer less from inherentsignal attenuation and therefore give improved range and in-building penetration. Already today, a number ofnetworks throughout the World are in commercial operation using certified WiMAX equipment compliant with the802.16d standard.The WiMAX specification improves upon many of the limitations of the Wi-Fi standard by providing increasedbandwidth and range and stronger encryption. It provides connectivity between network endpoints without need fordirect line of sight in favourable circumstances. The non-line-of-sight propagation (NLOS) performance requires the .16dor .16e revisions, since the lower frequencies are needed. It relies upon multi-path signals, somewhat in the mannerof 802.11n.3. Uses for WiMAXA commonly held misconception is that WiMAX will deliver 70 Mbit/s, over 70 miles (112.6 kilometers). Each of theseare true individually, given ideal circumstances, but they are not simultaneously true. WiMAX has some similarities to
  4. 4. DSL in this respect, where one can either have high bandwidth or long reach, but not both simultaneously. The otherfeature to consider with WiMAX is that available bandwidth is shared between users in a given radio sector, so if thereare many active users in a single sector, each will get reduced bandwidth.The bandwidth and reach of WiMAX make it suitable for the following potential applications: * Connecting Wi-Fi hotspots with each other and to other parts of the Internet * Providing a wireless alternative to cable and DSL for last mile (last km) broadband access. * Providing high-speed mobile data and telecommunications services (4G)4. Broadband AccessMany cable, wireless, and traditional telephone companies are closely examining it, in active trials or small scaledeployments, for "last mile" connectivity at high data rates. This could result in lower pricing for both home andbusiness customers as competition lowers prices. In areas without pre-existing physical cable or telephone networks,WiMAX will, it appears, be a viable alternative for broadband access that has been economically unavailable. Prior toWiMax, many operators have been using proprietary fixed wireless technologies for broadband services.WiMAX subscriber units are available in both indoor and outdoor versions from several manufacturers. Self installindoor units are convenient, but the subscriber must be significantly closer to the WiMax base station than withprofessionally installed units. As such, indoor installed units require a much higher infrastructure investment as wellas operational cost (site lease, backhaul, maintenance) due to the high number of base stations required to cover agiven area. Indoor units are comparable in size to a cable modem or DSL modem. Outdoor units allow for thesubscriber to be much further away from the WiMax base station, but usually require professional installation. Outdoorunits are roughly the size of a textbook, and their installation is comparable to a residential satellite dish.5. Mobile applicationsThere is potential for using WiMAX with legacy cellular networks. WiMAX antenna equipment can "share" a cell towerwithout compromising the function of cellular arrays already installed. Some cellular companies are evaluating WiMAXas a means of increasing bandwidth for a variety of data-intensive applications; indeed, Sprint Nextel has announcedin mid-2006 that it will be investing about US$ 3 billion in a WiMAX technology buildout over the next few years.Mobile WiMAX network equipment and terminals is expected to become available in the next few years. In line withthese possible applications is the technologys ability to serve as a high bandwidth "backhaul" for Internet or cellularphone traffic from remote areas back to an internet backbone. Although the cost-effectiveness of WiMAX in a remoteapplication will be higher, it is not limited to such applications, and may be an answer to reducing the cost of T1/E1backhaul as well. Given the limited wired infrastructure in some developing countries, the costs to install a WiMAXstation in conjunction with an existing cellular tower or even as a solitary hub are likely to be small in comparison todeveloping a wired solution. Areas of low population density and flat terrain are particularily suited to WiMAX and itsrange. For countries that have skipped wired infrastructure as a result of inhibitive costs and unsympatheticgeography, WiMAX can enhance wireless infrastructure in an inexpensive, decentralized, deployment-friendly andeffective manner.6. Spectrum Allocations for WiMAXThe 802.16 specification applies across a wide swath of the RF spectrum. However, specification is not the same aspermission to use. There is no uniform global licensed spectrum for WiMAX. In the US, the biggest segment available isaround 2.5 GHz, and is already assigned, primarily to Sprint Nextel and Clearwire. Elsewhere in the world, the mostlikely bands used will be around 3.5 GHz, 2.3/2.5 GHz, or 5 GHz, with 2.3/2.5 GHz probably being most important inAsia. In addition, several companies have announced plans to utilize the WiMAX standard in the 1.7/2.1 GHz spectrumband recently auctioned by the FCC, for deployment of "Advanced Wireless Services"(AWS).There is some prospect in the U. S. that some of a 700 MHz band might be made available for WiMAX use, but it iscurrently assigned to analog TV and awaits the complete rollout of digital TV before it can become available, likely by2009. In any case, there will be other uses suggested for that spectrum if and when it actually becomes open.It seems likely that there will be several variants of 802.16, depending on local regulatory conditions and thus onwhich spectrum is used, even if everything but the underlying radio frequencies is the same. WiMAX equipment will
  5. 5. not, therefore, be as portable as it might have been - perhaps even less so than WiFi, whose assigned channels inunlicensed spectrum varies little from jurisdiction to jurisdiction.The actual radio bandwidth of spectrum allocations is also likely to vary. Typical allocations are likely to providechannels of 5 MHz or 7 MHz. In principle the larger the bandwidth allocation of the spectrum, the higher thebandwidth that WiMAX can support for user traffic.7. StandardsThe current 802.16 standard is IEEE Std 802.16e-2005[1], approved in December 2005. It followed on from IEEE Std802.16-2004[2], which replaced IEEE Standards 802.16-2001, 802.16c-2002, and 802.16a-2003.IEEE Std 802.16-2004 (802.16d) addresses only fixed systems. 802.16e adds mobility components to the standard. 7.1. IEEE 802.16eIEEE 802.16-2005 (formerly named, but still best known as, 802.16e or Mobile WiMAX) provides an improvement on themodulation schemes stipulated in the original (fixed) WiMAX standard. It allows for fixed wireless and mobile Non Lineof Sight (NLOS) applications primarily by enhancing the OFDMA (Orthogonal Frequency Division Multiple Access).SOFDMA (Scalable OFDMA) improves upon OFDM256 for NLOS applications by: * Improving NLOS coverage by utilizing advanced antenna diversity schemes, and hybrid-Automatic RetransmissionRequest (hARQ) * Increasing system gain by use of denser sub-channelization, thereby improving indoor penetration * Introducing high-performance coding techniques such as Turbo Coding and Low-Density Parity Check (LDPC),enhancing security and NLOS performance * Introducing downlink sub-channelization, allowing administrators to trade coverage for capacity or vice versa * Improving coverage by introducing Adaptive Antenna Systems (AAS) and Multiple Input Multiple Output (MIMO)technology * Eliminating channel bandwidth dependencies on sub-carrier spacing, allowing for equal performance under any RFchannel spacing (1.25-14 MHz) * Enhanced Fast Fourier transform (FFT) algorithm can tolerate larger delay spreads, increasing resistance tomultipath interferenceOn the other hand, 802.16-2004 (fixed WiMAX) offers the benefit of available commercial products and implementationsoptimized for fixed access. Fixed WiMAX is a popular standard among alternative service providers and operators indeveloping areas due to its low cost of deployment and advanced performance in a fixed environment. Fixed WiMax isalso seen as a potential standard for backhaul of wireless base stations such as cellular, WiFi of even mobile WiMAX.SOFDMA and OFDMA256 are not compatible so most equipment will have to be replaced. However, some manufacturersare planning to provide a migration path for older equipment to SOFDMA compatibility which would ease the transitionfor those networks which have already made the OFDMA256 investment. 7.2. HIPERMANThe equivalent of 802.16 in Europe is HIPERMAN. The WiMAX Forum is working to ensure that 802.16 and HIPERMANinter-operate seamlessly. 7.3. WiBroKoreas electronics and telecommunication industry spearheaded by Samsung Electronics and ETRI has developed itsown standard, WiBro. In late 2004, Intel and LG Electronics have agreed on interoperability between WiBro and WiMAX.WiBro has South Korean government support with the requirement for each carrier to spend over US$1 billion fordeployments. The Koreans sought to develop WiBro as a regional and potentially international alternative to 3.5G or 4Gcellular systems. But given the lack of momentum as a standard, WiBro has joined WiMAX and agreed to harmonizewith the similar OFDMA 802.16e version of the standard. What makes WiBro roll-outs, which will start in April 2006, a
  6. 6. good test case for the overall WiMAX effort is that it is mobile, well thought out for delivery of wireless broadbandservices, and the fact that the deployment is taking place in a highly sophisticated, broadband-saturated market.WiBro will go up against 3G and very high bandwidth wire-line services rather than as gap-filler or rural under-servedmarket deployments as is often exampled as the best fit markets for WiMAX.8. Associations 8.1. WiMAX ForumThe WiMAX Forum is "the exclusive organization dedicated to certifying the interoperability of BWA products, theWiMAX Forum defines and conducts conformance and interoperability testing to ensure that different vendor systemswork seamlessly with one another." Those that pass conformance and interoperability testing achieve the "WiMAXForum Certified" designation and display this mark on their products and marketing materials. Vendors claiming theirequipment is "WiMAX-ready", "WiMAX-compliant", or "pre-WiMAX" are not WiMAX Forum Certified, according to theForum. [2] 8.2. WiMAX Spectrum Owners AllianceWiSOA is the first global organisation composed exclusively of owners of WiMAX spectrum. WiSOA is focussed on theregulation, commercialisation, and deployment of WiMAX spectrum in the 2.3–2.5 GHz and the 3.4–3.5 GHz ranges.WiSOA are dedicated to educating and informing its members, industry representatives and government regulators ofthe importance of WiMAX spectrum, its use, and the potential for WiMAX to revolutionise broadband.[3]9. Competing technologiesWiMAX is a framework for wireless development based on a forward-looking core set of technologies. More recently3GPP cellulars 4G, 802.22 Cognitive Radio RAN (Rural Area Network), and 802.20, the High Speed Mobile BroadbandWireless Access (MBWA) Working Group, have shifted toward use of similar constructs of multi-channel scalable OFDM,HARQ, FEC, MIMO-AAS and other complementary technologies as are part of WiMAX.UMTSFor some applications, UMTS could be a direct competitor to WiMAX. UMTS has been deployed in Europe and elsewheremostly by Mobile Telephone operators. The HSDPA technology enables down-link with data transmission up to 14.4Mbit/s (see above for comparison). UMTS also provides a circuit channel optimized for voice and video traffic. In July2005 EU frequency allocation for WiMAX was blocked by France and Finland, where manufacturers have investedheavily in UMTS technology. On the other side of the world, frequency bidding in Malaysia was stopped and anyallocation of WiMAX has been suspended indefinitely in September 2006.While ordinary UMTS service is being provided largely as an upgrade to existing cellular telephone systems, a variantof UMTS, UMTS-TDD, exists which is being deployed primarily as a mobile broadband Internet provisioning system, andas such could be seen as a more direct competitor to WiMAX. A number of ISPs around the world have deployed thesystem already.[4]. UMTS-TDD uses a Time Division Duplexed air interface (so both the downlink and uplink can sharethe same frequency, making it more dynamic in terms of being able to allocate spectrum as traffic patterns changecompared to traditional UMTS. UMTS-TDD provides lower bandwidth and less range than WiMAX at both standardstheoretical maximums, but is more consistant in terms of its capabilities within the range it does allow. 9.1. LTEThe most recent 3GPP standardization activities are development of advanced systems based on OFDM rather thanCDMA. The 3G Long Term Evolution (LTE) platform will be based on MIMO-OFDM similar to WiMAX/802.16e-2005. This isa major shift from CDMA/WCDMA system evolution or the prior road map for over-laying OFDM onto the WCDMAsystem architecture such as MC-CDMA and TD-SCDMA to frequency interference mitigation via orthogonalchannelization methods. Some suggest that WiMAX is disruptive while LTE is an evolution of the cellular road map.Both WiMAX and LTE use a different core technology than 3G and prior cellular systems and neither can provide shareduse of current cellular spectrums. A major reason for the shift from the CDMA platform to OFDM is the ability of OFDM
  7. 7. to make better use of MIMO and AAS multi-antenna and signal path technologies. Debates about core spectralefficiencies are dwarfed by improvements already achievable via the use of MIMO and, so far, limited AAS. Theevolution of wireless calls for greater gains from the synergistic combination of these technologies in the future.While both systems use OFDM/OFDMA, LTE is optimized more for wide area mobile voice communications. LTE will useOFDMA for the down-link and SC-OFDM (Single Carrier OFDM) for the uplink while WiMAX/802.16e-2005 uses OFDMA forboth the up and down links. SC-OFDM can maintain connections at longer distance but has lower bandwidth thanOFDMA. However, WiMAX advocates perceive evolution of WBB as also shifting the architectural evolution of wirelessnetworks to more symmetrical, higher bandwidth in which multi-mode CDMA and other technologies can fulfill longrange and low bandwidth persistent requirements. 9.2. EV-DOEvolution-Data Optimized is a wireless radio broadband data standard adopted by many CDMA mobile phone serviceproviders around the globe. It is standardized by 3GPP2, as part of the CDMA family of standards. 9.3. Wi-FiWi-Fi is a Wireless Local Area Network (LAN) technology that works in unlicensed spectrum, using the 2.4GHz and 5 GHzbands. Wi-Fi is a cheap and easy way of providing local connectivity at high speed. WiMAX uses licenced spectrum andhas strong authentication mechanisms built in. It has considerably greater range than Wi-Fi. Taken together, thismeans that WiMAX and Wi-Fi are generally complementary rather than competing. 9.4. Mobile Broadband Wireless AccessMBWA is a technology under development by IEEE 802.20. It is a future technology for true wireless broadband or 4G.However The IEEE recently (June 2006) said it would pause the 802.20 working group that has the backing ofQualcomm, the US cellular communications giant that acquired 802.20 developer Flarion Technologies in January. Thisfollowed questions of whether panel participants had disclosed their affiliations in a propermanner.http://grouper.ieee.org/groups/802/mbwa/email/pdf00015.pdf10. DeploymentThe following are current and planned deployments, the bands in which they operate and the standards they use. 10.1. Australia Unwired holds licences in the 3.5GHz and 2.3GHz bands, and has plans to build a Mobile WiMax network on the2.3Ghz band once WiMax Forum certified hardware is available. This will be a replacement to its proprietary fixedwireless system which currently exists on the 3.5Ghz band. Austar holds licences in the 3.5GHz and 2.3GHz bands. 10.2. Austria WiMAX Telecom holds 3.5GHz licences for the entire country. 10.3. Brazil Brazilian Telecommunications Agency to sell licences for WiMAX. See news (in portuguese)A few Brazilian companies already have rights to important parts of the WiMax spectrum, both at 2.5GHZ (MMDS band)and 3.5GHz. 10.4. Canada
  8. 8. Rogers Communications and Bell Canada have formed a joint venture called Inukshuk Wireless. Rogers has providedits spectrum rights in the 2.3-Ghz, 2.5-GHz and 3.5-GHz bands, while Bell Canada has contributed its spectrum holdingsat 2.3 GHz and 3.5 GHz. Services are currently available from both companies in Canada.Rogers Communications Bell Canada 10.5. Croatia VIPnet and Odašiljaèi hold 3.5GHz licences for the capital, Zagreb. Portus, Optima Telekom, WiMAX Telecom and OiV hold 3.5GHz licences for some regions. 10.6. Denmark Despite of government reluctance to allow private companies to use the WiMAX frequency ranges, a few companiesare using the WiMAX technologies with different frequencies. For private customers, the largest cities are covered byClearWire, while Butler Networks delivers WiMAX access to bussiness customers through other telecommunicationproviders. 10.7. Ireland Irish Broadband Irish Broadband holds 3.5 GHz licenses in Ireland. Clearwire Broadband an American Company that also holds regional 3.5Ghz licences in many for the big cities inIreland, they utilize Non-LOS technology to provide last mile access. Pre 802.16e equipment. Lastmile Broadband also hold regional 3.5GHz licences and plan to deploy a WiMAX network in the fourth quarter of2006. [4] Eircom, The largest Telecom in Ireland hold the only nationwide 3.5Ghz licence, although not commercial availableyet they plan for 2007 to have rolled out WiMAX. 10.8. Finland There are some 15 WiMax operators in Finland spread throughout the country. The coverage is mainly concentratedon the rural areas and the Lappland, but SuomiCom has partial coverage also in the Helsinki Metropolitan Area. 10.9. France Iliad , owner of the Free (French ISP) , holds the only national license since 2005. 49 regional licenses wereregistered in july 2006. 10.10. New Zealand nzwireless is deploying WiMAX in the 3.5GHz spectrum for fixed installation, currently covering the Wellington CBD CallPlus are deploying a nationwide 3.5GHz WiMAX network under the brand Blue Reach 10.11. Georgia QTEL Georgia is currently deploying an unlicensed 5.8 Ghz WiMax system in Tbilisi. Nationwide deployment isplanned for Q1 & Q2 of 2007. 10.12. Slovakia WiMAX Telecom holds 3.5GHz licences. 10.13. UK UK Broadband a subsidiary of PCCW, owns 3.5 GHz licenses. 10.14. USA
  9. 9. Valtech Communications deployed network in Northwest Ohio at beginning of 2006. Currently holds licenses for theMidwest and Florida. Clearwire holds 2.5GHz licences in several regions. Sprint Nextel holds licences in the 2.5GHz band covering most of the US. Sprint plans to build a "Nationwideadvanced wireless broadband network expected to cover 100 million people in 2008" 1 NextWave Wireless holds licences in the 1.7GHz and 2.1GHz band.4 10.15. ItalyAvailable spectrum on 3.5 GHz. No date for bid yet11. References 1. WiMAX Forum 2. IEEE 802.16 — The IEEE 802.16 Working Group on Broadband Wireless Access Standards 3. WiMAXPro.com - The Original WiMAX News, Information & Whitepapers 4. WiMAX.com - WiMAX News, Information & Whitepapers 5. comtechnews ComTech News on "Why WiMAX will Become the Future of Telecommunications" 6. WiMAX Day - News and Information about WiMAX Industry 7. WiMAX - WiMAX Industry News

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