WiMAX vs. LTE: Should You Switch? Wimax планшет


WiMAX Vs. LTE | eBay

When it comes to 4G data or hotspot sharing for smartphones, tablets, and other electronic devices capable of using wireless Internet, consumers have two main choices: WiMAX and LTE. Each of these modes of data transmission possess its own unique qualities and benefits and a bit of research into the capabilities of the two allow consumers to be on the lookout for a device and corresponding mobile or home carrier bearing the inclusion of one versus the other. Armed with this knowledge, a shopper is able to make a buying decision that works best for their individual or family's needs and complete the purchase with confidence on eBay.

Technical Specification
WiMAX
LTE

Network standard

IEEE 802.16

GSM/EDGE, UMTS/HSPA

VoIP capability

Yes

No - VoLTE (Voice over LTE)

Standard data transmission

30 - 40 MB/second

75.4 MB/second

Maximum data transmission

Up to 1 GB/second

299.6 MB/second

Presence of allocated spectrum

No

No

Spectrum capability

2.3 GHz, 2.5 GHz, 3.5 GHz

1.4 GHz, 3 GHz, 5 GHz, 10 GHz, 15 GHz, 20 GHz

WiMAX

WiMAX, an acronym for Worldwide Interoperability for Microwave Access, is one of the top technology choices included by mobile device manufacturers and uses OFDM (orthogonal frequency division multiplexing) to encode digital data on multiple carrier frequencies. This form of mobile connection was introduced in 2001. WiMAX is capable of providing a reliable signal for multiple Internet-capable devices using simple internal or external peripheral adapters, including smartphones and other cellular devices, wireless-enabled tablets, and laptop computers, as well as gaming consoles and MP3 players as an alternative to a home Wi-Fi signal. This technology is also offered in the form of a subscriber gateway to function as a broad area metered hotspot produced by brands such as Huawei, Motorola, and Airspan and is also prevalent in some earlier HTC and Sprint Nextel phones as well as the Clearwire network. In fact, the advanced WiMAX transmission mode is more similar to Wi-Fi than other cellular technologies due to its signal strength, reliability, and compatibility.

A distinguishing characteristic of WiMAX is its dynamic burst algorithm, a function that enables a high quality connection to a base station, but only when the station is within a particular range of the device. If the distance is bordering on too great, there is a high likelihood of signal interference and dropped performance, an event that leads to misrepresentation of the network as well as a brand or carrier's capabilities.

LTE

LTE, or Long Term Evolution, is another of the major wireless standards implemented around the world today. This technology is used to provide connectivity to smartphones, data hubs, and other advanced internet-ready electronic devices and is most prominently used on the Verizon mobile network, inside newer HTC and Samsung phones, and in other multi-band devices such as laptop cards and wireless hubs. This standard is also heavily used by several pre-paid cellular networks, Rogers and Telus in Canada, and various other companies in Asia and Europe. LTE is defined as being capable of transmitting true 4G signal strength, an important feature for busy professionals, on-the-go parents, students, and others who prioritize a strong, stable connection to the mobile web while out and about.When it was first developed and released in 2009, the goal of LTE was to expand upon the speed and reach of previous mobile Internet connectivity using DSP (digital signal processing) techniques in order to have this mode conform to a simpler IP-based system. This slightly reduces transfer latency and gives a more broad reach in areas where full coverage is available.

Comparing WiMAX vs. LTE

There are several points of comparison to examine when deciding between the purchase and use of WiMAX or LTE and some of the major areas to focus on include the wireless technology standards, data transmission speeds, and spectrum capability.

While both WiMAX and LTE are capable of providing reliable mobile Internet signals, there is a slight difference between the two. WiMAX operates over the IEEE 802.16 frequency, as it is more akin to the home Wi-Fi format, while LTE expands upon the GSM/EDGE and UMTS/HSPA wireless standards. The latter has a wider reach and more broad coverage than the former, a trait that has the potential to be a sole decision maker between the two technologies.

In terms of data transmission speeds, WiMAX operates at a standard 30-40 MB/second compared to the 75.4 MB/second produced by LTE, but the WiMAX maximum speed of up to 1 GB/second is a bit faster overall. On the other hand, LTE is capable of operating across more spectrums with 1.4 GHz, 3 GHz, 5 GHz, 10 GHz, 15 GHz, 20 GHz coverage compared to the 2.3 GHz, 2.5 GHz, 3.5 GHz ability of WiMAX.

Buying WiMAX and LTE Devices on eBay

When shopping for a WiMAX or LTE-capable device on eBay, it is important to use precise keywords to find the item you need quickly and easily. For example, use search phrases such as "Samsung LTE laptop card", "HTC LTE 4G phone", or "Motorola WiMAX hub" for the best results and a smaller pool of listings from which to browse. Once the perfect device is selected, the purchasing process completes with just a few clicks of the mouse and the seller readies your item to ship straight to your door in a matter of days.

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Yeni Nesil Kablosuz İnternet · e-bergi

Biri size kablosuz, geniş bant interneti yaklaşık 50 km'lik bir alanda kullanabileceğinizi söylese ne derdiniz? “Yok artık, daha neler!” cevabınız olurdu sanırım =) . O zaman bu cevabı söylemeye hazır olun, çünkü biraz önce söylediklerim hayal değil. İşte, hayalleri gerçeğe dönüştürecek olan teknoloji.. WIMAX =)

WIMAX NEDİR?

Peki nedir bu Wimax? Açılımı Worldwide Interoperability for Microwave Access (Dünya Çapında Birlikte İşleyen Mikrodalga Erişimi) olan Wimax, MAN (Metropolitan Area Network- Metropol Alan Ağı) gibi geniş kapsamlı ağlar için geliştirilen teknolojilerin uygunluğunu belirleyen standartlar topluluğudur. Sabit kablosuz adında bir teknoloji kullanan Wimax; üzerinde verici antenin bulunduğu uzun bir direkten, bir sinyalin minik alıcılarla alınmasına dayalı bir sistemdir. Sinyal, 35 mil (yaklaşık 50 km) gibi inanılması güç büyüklükte bir alanda yüksek hızda (75 Mbps indirme hızı) ve gelişmiş güvenlikte kablosuz internet bağlantısı sağlamaktadır. Wimax teknolojisi, 4-5 km'lik alanlarda bilgisayara takılan aparatlarla kablosuz internete ulaşmayı mümkün kılarken; modem ve kabloya ihtiyaç duymadığı için adsl ve kablolu internet erişimini de gölgede bırakacaktır. Ayrıca modem ve kablo ihtiyacını da ortadan kaldırdığı için büyük bir ucuzluk sağladığı düşünülebilir. Wimax, Wimax forumu adı verilen, IEEE 802.16 standardına uygun üretilen donanımların; bu standarda uygunluğunu “Wimax Forumu onaylıdır.” ibaresi ile onaylayan bir kurum tarafından desteklenmektedir.

IEEE 802.16 STANDARDI NEDİR?

IEEE, Elektrik ve Elektronik Mühendisleri Enstitüsü (Instutite of Electric and Electronic Engineers), geliştirilen yeni teknolojilere kod numarası verme usülü ile bunları standarda oturtmayı amaçlayan bir kurumdur. 802.16, genişbant kablosuz erişim standardı için IEEE tarafından verilen kod numarasıdır. (802.11 de kablosuz ağların standartlarını içeren Wifi teknolojisine verilen kod numarasıdır.)

WIMAX'IN KULLANIM ALANLARI

Özellikle kablolu internet erişim imkanı bulunmayan alanlarda, örneğin ulaşım araçlarında ve duraklarda olduğu gibi, baz istasyonları aracılığı ile yüksek hızda internet sağlar.

Bir şehirde, cep telefonu baz istasyonları, telefon şebekeleri ve geniş bant internet ağları gibi pek çok ağ bulunmaktadır. Wimax, Geniş Alan Ağı (Wide Area Network- WAN) 'ndan daha geniş bir alanı, genellikle bir şehri, kapsayan büyüklükte bir ağ yapısı olan Metropol Alan Ağı (Metropolitan Area Network- MAN)'nı kullanan bir teknoloji olduğu için yukarıda bahsedilen tüm ağları tek bir hat üzerinden verebilir. Bu ise gelişmekte olan ülkelerde alt yapı çalışmalarını hızlandırabilir. Şöyle ki; telefon, internet ve televizyon için ayrı ayrı alt yapı kurmak yerine sadece Wimax'ı kullanarak tüm bu hizmetler tek bir alt yapıyla verilebilirler.

Wimax'ın kablosuz erişim özelliği ülkelerdeki verimsiz arazi koşullarından etkilenmeyecektir.

Wimax az gelişmiş ülkelerde daha ucuz yoldan tüm hizmetleri sunabilirken, gelişmiş ülkelerde de fayda sağlamaktadır. Wimax, gelişmiş ülkelerde kablolardan kurtulmak için vazgeçilmez bir alternatiftir. Ayrıca sağladığı geniş bant özelliği ile yeni nesil cep telefonları ve internet uygulamaları için de az maliyetle hizmet vermeyi amaç edinmiştir.

Bir Wimax anteni, Wimax'ın kullandığı frekansın cep telefonlarının kullandıkları frekanstan farklı olmasından dolayı, cep telefonları için yerleştirilmiş istasyonlarda da rahatlıkla kullanılabilir. Kullanılmakta olan cep telefonları ile son derece uyumlu olan Wimax'ın, cep telefonu şebekelerinin sundukları normal hizmetlerin yanında ek hizmet olarak yer alabileceği ise muhtemeldir.

Wimax'ın geniş bant erişimi, Aralık 2004'te Endonezya'da meydana gelen tsunamiden sonra felaket bölgesi ile dışarısı arasındaki haberleşmeyi sağlamakta önemli rol oynadı. Tsunami esnasında birkaç yer dışında tüm alt yapılar zarar görünce, Wimax'ın geniş bant erişimi iletişim kurmaya yardımcı oldu.

Wimax, Katrina kasırgasından sonra zarar gören yerlerde FCC (Federal Communication Commissions- Birleşik Haberleşme Komüsyonu) ve FEMA (Federal Emergency Management Agency- Birleşik Acil Durum Yönetim Şubesi)'nın haberleşme çalışmalarında kullanıldı.

Wimax'ın gelmesiyle mobil ve taşınabilir ünitelerin internet sahibi olabilmesinden dolayı bunlar üzerine artan bir ilgi oluşmaya başladı. ABD'de büyük şirketler yüzlerce megabitlik kablosuz erişim için Wimax kullanmaktadırlar.

Bazı analistler; Wimax'ın, hava dalgaları ile ses ve veri getirmek için başka teknolojilere milyarlar yatırmış olan büyük cep telefonu firmalarından bazıları için ciddi tehdit olabileceğini vurgulamaktadırlar. Wifi de başta bazı firmalar tarafından kabul görmemiş olmasına rağmen, kısa menzilde ne kadar etkili olduğunu kısa zamanda kanıtlayarak kabul görmüştür.

Wimax teknolojisi ilk olarak Çin'de daha sonra eş zamanlı olarak ABD'de ve Türkiye'de Konya'da denenmektedir.

WIMAX - WIFI KARŞILAŞTIRMASI

Bu karşılaştırmaya geçmeden önce Wifi nedir, onu görelim :) Wifi; açılımı wireless fidelity- kablosuz sadakat =) olan kablosuz bağlantı anlamına gelen bir teknolojidir. IEEE 802.11 protokolüyle kablosuz erişim noktalarından yerel alan ağına (locak area network) bağlanabilmeyi sağlayan standartlar topluluğudur. Wifi ile Wimax arasında belli başlı benzerlikler ve farklılıklar vardır:

Wimax da Wifi de ağ için kablolama gereksinimine ihtiyaç duymaz. Böylelikle kablolu ağ kullanılmayan yerlerde kolaylık sağlar. Wifi 2.4 Ghz veya 5 Ghz radyo frekansını kullanırken, Wimax 10-66 Ghz frekans aralığını kullanır.

Wimax, Wifi'nin aksine geniş bant aralığı için etkili kılınmıştır. Yani Wimax'ın asıl fonksiyonu geniş bant internet erişimine olanak sağlamaktır. Wifi'nin tipik bant genişliği 2 Mbps iken Wimax'ın bant genişliği 75 Mbps'ye kadar çıkabilmektedir.

Wifi kısa mesafelerde kablosuz internete erişim imkanı sunarken, Wimax baz istasyonları aracılığı ile daha geniş menzillerde (50km) etkili olmayı hedeflemektedir.

Wan (wide area network) yani geniş ağlar için tasarlanmış Wimax, sunduğu yüksek hız ve gelişmiş güvenlikle Wifi'nin geniş ölçekli ağlardaki bir benzeri olarak tanımlanabilir.

Wimax ve Wifi arasındaki fark, kablosuz telefon ve cep telefonu arasındaki farka benzetilmektedir. :) Wifi, ev veya ofis gibi sınırlı bir alanın içinde, kablosuz telefon gibi bağlantı kurmak için kullanılırken; Wimax ise cep telefonları servisleri gibi, merkezi bir yerden servis alanı dahilinde ya da dışında bulunan birçok yere ve hatta arabalarla o yerden geçen insanlara da geniş bant bağlantı sağlamayı hedeflemektedir.

WIMAX'IN SINIRLANDIRMALARI

Wimax ile ilgili bilinen en büyük yanlış, Wimax'ın 50 km de 70 Mbit/s ulaştırdığıdır. Gerçekte ise, Wimax bunlardan sadece birini yapabilir, yani maksimum 50 km'de geçerli olabilir, ki alan büyüdükçe bit hata oranı (bit error rate) arttığı için düşük bit oranı kullanır.

Birçok kablosuz sistemde olduğu gibi, uygun bant genişliği Wimax'ta da bir çok radyo bölgesi ile birlikte kullanılır. Bu sebeple, belli bir bölgedeki performans birçok aktif kullanıcı dolayısıyla zarar görebilir. Pratikte, birçok kullanıcı 2,4,6,8,10, ya da 12 Mbit/s servislerini kullanacak ve ek radyo kartları gerekli olan kapasiteyi artırmak için baz istasyonlarına eklenecektir.

Kablosuz teknolojilerin geleceğini düşündüğümüzde insanların isteyeceği servisleri tek bir sistemin sağlayacağını düşünmek ilkelce kalmaktadır. Wimax'ın ve diğer eski sistemlerin yanında ArrayComm’s iBurst (radyo spektrumunda ince bir parçayı yöneten kablosuz ağ teknolojisi) ve Flash-OFDM (veri akışını çoğaltmayı umut eden bir frekans kullanan kablosuz teknoloji) gibi teknolojiler çoktan yer bulmuştur.

TÜRKİYE'DE WIMAX

Türkiye'de Wimax ilk olarak ADSL altyapısı bulunmayan Yozgat Boğazlıyan köyünde test edildi. Kurulan Wimax vericisi sayesinde 50kmlik bir alanda internet erişimi sağlandı. Türkiyede araba, otobüs gibi yerlerde internete erişim için çok fazla talep olmayacağı düşünüldüğü için çok fazla baz istasyonu kurmak zorunda kalınmayacağı da düşünülmektedir.

WIMAX'IN GELECEĞİ

Wimax'ın geleceği birçok tartışmaya neden olmaktadır; bazı uzmanlar Wimax kullanımının kırsal kesimlerde sıçrayacağını savunurken, bazı uzmanlar da cep telefonu şirketlerinin zorlu bir savaş içerisine gireceğini öngörmektedirler. Mobil Wimax daha düşük fiyatlarla ve yüksek veri oranları ile sıradan hücresel sistemlerin yaptığı herşeyi yapma potansiyeline sahiptir. Fakat, mobil Wimax sistemlerinin yayılması seneler alır. Üstelik, Wimax'ın fiyat avantajı saatte 60 milin üstüne çıkıldığında azalır, bu yüzden eski sistemle kıyaslandığında yüksek hızlı araçlar için Wimax daha az avantajlı hale gelir.

Peki, kablosuz internet teknolojisinin geleceğine baktığımızda Wimax 'ı nerede görüyoruz? Geniş alanları kapsamada pahalı ve zayıf bir yöntem olan Wifi'nin aksine, Wimax geniş alanlarda etkin olmasıyla Wifi'den daha öndedir. Ayrıca; mobil Wimax kırsal kesimlerde, dizüstü bilgisayarlarda, e-posta ve internet tarayıcısı gibi bazı uygulamalarda etkin olacak gibi gözükmektedir.

Kim bilir, belki de önümüzdeki beş yıl içerisinde bilgisayarlarımızı, daha yüksek kalitede ve inanılmaz hızlı biçimde şu anki cep telefonlarının sahip olduğu özgürlükte kullanıyo olacağız.. Wimax teknolojisiyle neden olmasın? :)

Kaynaklar:

e-bergi.com

WiMAX vs. LTE: Should You Switch?

When it comes to wireless data networks, besides knowing the difference between 3G and 4G, there's another question: Which flavor of 4G do you need? Sprint was the first major wireless carrier in the U.S. with 4G, but is now upgrading its networks from WiMAX to LTE. Virgin and Boost, meanwhile, are just getting WiMAX. Which one should you pick? We've been covering WiMAX vs. LTE and testing devices since the day each technology first launched, so we can give you the full scoop. 

WiMAX vs. LTE: HistoryThe "4G" moniker is officially meaningless, but WiMAX was the first technology to call itself 4G when Sprint announced it back in 2006. WiMAX descends from Wi-Fi rather than from cellular technologies, although it has some aspects in common with LTE, most notably by using a technology called OFDM as a way of packing multiple transmissions into one radio band.

The WiMAX story actually began with home connections instead of phones. WiMAX started out as a way to deliver wireless broadband to homes and businesses. In many parts of the country, "wireless ISPs" still deliver home broadband via WiMAX. The Lab here at PCMag has a fixed WiMAX link from Clearwire as one of our network connections. WiMAX helps ISPs deliver Internet connections without running expensive cables to every home, and speeds often run between 5-10Mbps, or about the same as DSL. In that context, at least, WiMAX isn't going away.

But you're probably wondering about "mobile WiMAX," which Sprint announced in August 2006 and finally launched in September 2008. At the time, 3G networks ran at about one megabit per second, and Sprint's XOHM WiMAX promised to be at least twice as fast. Sprint took the WiMAX bet in part because at the time it was backed by Intel, which promised to put WiMAX into dozens of laptops and help make WiMAX the worldwide standard. It was also backed by Nokia, which was, at the time, the world's number-one cell phone company.

Unfortunately, Sprint squandered its lead by building its network very slowly. In 2006, WiMAX would have been a revelation, but the first city didn't go live until 2008. And by January 2010, it covered just 30 million people in 27 cities. This wasn't about any flaw in the WiMAX technology—just haplessness on the part of Sprint and its partner Clearwire. Outside of the U.S., WiMAX saw some success in Russia, Mongolia, and Pakistan, but was largely shunned in western Europe.

While Sprint dithered, the whole cell phone industry turned away from WiMAX (and Intel) to LTE, which came from the same folks who brought us GSM and promised much better compatibility with existing cell phone equipment. The LTE standard was approved in December 2008, with America's first LTE network coming from MetroPCS in October 2010.

Now both Sprint and Clearwire are building LTE networks, and Sprint has said there won't be any new WiMAX build-out, although the network will stay turned on through 2015.  

WiMAX vs. LTE: PerformanceThe version of WiMAX Sprint uses should deliver 30-40Mbps download speeds, and LTE can deliver up to 100Mbps. In the real world, though, they achieve nothing like those speeds. That's because a network's performance depends much more on how it's built than on the specs of the underlying technology.

Our Fastest Mobile Networks results tell the tale. In our tests across the country, Sprint's WiMAX averaged about 3Mbps down, and it's currently capped to 1.5Mbps up. That's slower than most home broadband. Verizon's LTE network tripled that download speed to 9.46Mbps average, although uploads averaged about 1.35Mbps. That's roughly as fast as many home broadband packages.

But look at MetroPCS's LTE. This is the same LTE technology as Verizon uses, but in much narrower channels, with a focus on low cost rather than performance. MetroPCS averaged only 1.62Mbps down in our tests. That said, we expect Sprint's LTE to be faster than its WiMAX. Otherwise the millions of existing Sprint 4G customers will be disappointed. 

LTE has another key performance advantage: It's better integrated with other cellular technologies, making for smoother transitions between 3G and 4G. WiMAX phones tend to have problems finding 4G again once they drop into a 3G area. LTE phones have less of an issue with that.

For more on Sprint's upcoming LTE network, see "Sprint: A Better Network is Coming" and "Sprint: LTE Speeds Will Advance"

www.pcmag.com

The Future of WiMAX - TFOT

The signal transmitted from the base station to the user or from the user to the base station through wireless channel faces attenuation in space, fraction, refraction, reflection from objects on the propagation path, and shadowing from walls or other barriers. As a result, the transmitted signal is distorted and sometimes splits into different replicas called multi-paths. The transmitted signal is commonly described by its structure in time, frequency (its frequencies and its bandwidth), and space. The receiver’s target at both uplink and downlink is to combat the signal’s distortion in order to perfectly recover the transmitted signal and enable reliable data transmission.

WiMAX plays an important role in both emerging markets and mature markets. There are more than 262 WiMAX operators covered in 91 countries. Many companies, from large communications equipment companies to smaller companies, are involved in developing and manufacturing WiMAX. Asia Pacific accounted for 26% of deployments, Europe 34%, the Middle East 16%, North America 11%, and the Caribbean and Latin America for 13%.

All of these advanced features challenge WiMAX equipment manufacturers to build strong, dedicated, low-cost low power WiMAX base stations and chipsets for the portable units for advanced handsets and PC peripherals (PC cards or USB dongles) and other consumer electronics devices as game terminals.

Broadband is becoming a necessity for many residential and business subscribers worldwide. According to analysts, broadband services will see rapid growth from their current starting point. There were close to 350 million broadband subscribers worldwide at the end of 2007, up from 130 million at the end of 2004. WiMAX as a leading broadband technology is starting to make its niche in this market.

MSI WiMax netbook

Unlike service providers mentioned above, Verizon and Vodafone (the joint owners of U.S. based Verizon Wireless), on the other hand, plan to develop and deploy as their fourth generation mobile broadband network the competing technology – LTE. Which 4G technology will win, WiMAX or LTE? Both technologies have much in common from a technology standpoint and have many architectural similarities. Still, WiMAX has the following advantages over LTE: it benefits from strong allies including Intel and Google, and Network Operators is the largest segment of the WiMAX Forum. People might prefer to use WiMAX as the next generation of free Wi-Fi and in order to rebel against the traditional cell phone companies. WiMAX has already started regional and nationwide deployments while LTE may only enter the market in late 2009 (at the earliest). According to Nokia and Ericsson, their primary market – 3G operators – will be unlikely to adopt LTE until a few years later. LTE operator AT&T reiterated its position that its 3.5 (HSPA) and 3G network technologies still have a lot of life left in them, and that LTE technology would not be rolled out for at least another three years. The WiMAX Forum has already started working on the next backwards-compatible generation of the WiMAX standard, the 802.16m, which will be able to use even higher bandwidths and achieve higher spectral efficiency that will be able to compete with 802.11n in non-rural conditions.

Simens Gigaset SE68 SE68WiMAX Express Card (Credit: Simens)

Recently, there are signs that the WiMAX and LTE camps are seeking a negotiated settlement to harmonize WiMAX and LTE. Participants from both the WiMAX and LTE camps and standards organizations have recognized the need to collaborate on developing communications. Vodafone is among the operators that have called for the merging of WiMAX and LTE because of the reduction in both conflicts and costs for the industry. The long-term trends in technology, regulation, ecosystem consolidation, and globalization contribute to the rationale that wireless systems should strive to achieve common air interfaces where feasible. Intel CEO Paul Otellini has also called for harmonization between WiMAX and LTE, pointing out the goals of unified broadband communications and common use of technologies. A head-to-head battle over the next few years would require an outlay of billions of dollars in equipment deployment that can be saved with the harmonization of the standards. The primary obstacle to achieving harmonization of WiMAX and LTE is simply the commercial self-interests of competing companies and manufacturers which prevent a common push forward. Intel will eventually provide combined support regardless of whether or not the standards groups achieve official harmonization about providing a multi-mode WiMAX plus LTE chipset for notebooks. Altair Semiconductor, an innovative mobile WiMAX chipset company, also uses the multi-mode WiMAX plus LTE chipset for other portable devices. The first example of standard harmonization comes from the base station manufacturer Freescale Semiconductor, who recently introduced the industry’s first multi-standard device.

 
A bit of history– Alcatel WiMAX in CeBIT 2007

Infonetics Research, the premier international market research and consulting firm specializing in data networking and telecom, believes that consumers will adopt dual-mode Wi-Fi notepads and phones (Wi-Fi and WiMAX) for use with home wireless networks, public hotspots, and municipal networks. Intel and Nokia are developing technology that is supposed to provide true uninterrupted broadband connectivity based on automatic undetectable switchovers from Wi-Fi to WiMAX. The American municipal wireless networking and intelligent transportation company Azulstar recently launched a high-speed WiMAX service based on Alvarion’s BreezeMAX 3650, which operates in the 3.65 GHz spectrum in New Mexico, which is supposed to support highly reliable services of up to 6 Mbps for home users and up to 100 Mbps for business connections. The launch is supposed to include the complete transition from Wi-Fi to WiMAX technology in Grand Haven, the first Wi-Fi city in the U.S, across New Mexico.

Whether it is LTE or WiMAX, the success of mobile broadband will be driven by the development of user-friendly applications and handsets. Applications driving the mobile broadband market include mobile music, multimedia messaging, gaming, and mobile TV. WiMAX kit vendor NextWave Wireless recently showcased its next generation mobile multimedia platform by demonstrating mobile TV, interactive media services, and digital audio – features it expects will drive the WiMAX market forward. Another company, Runcom Technologies, demonstrated the first internet TV set top box (STB) at the WiMAX Forum  Global Congress 2008 that took place last June in Amsterdam.

Interview with Eran Eshed, Altair Semiconductor

TFOT recently interviewed Eran Eshed, co-founder and VP of marketing and business of Altair Semiconductor, an innovative mobile WiMAX chipset company which recently won the Best of WiMAX World 2008 Award for their WiMAX chipset at the WiMAX World 2008 Conference.

Q: Can you say a few words about Altair’s background?

 
Altair – fabless semiconductor WiMAX

A:

Altair is a fabless chip company developing ultra-low power and high performance 4G/OFDMA silicon solutions. The company was established almost four years ago, by a group of ex-Texas Instruments executives with exceptionally vast experience in the field of broadband semiconductor development. This team has developed during the past 10 years over 25 different complex mixed-signal broadband ICs, which shipped in millions of commercial products in the field. Prior to TI we worked together in a chip startup called “Libit Signal Processing,” which was acquired by TI in 1999, in what is still considered today as one of the most successful semiconductor acquisition in Israel’s tech scene.

Altair’s existing product lines focus around baseband and RF solutions for mobile WiMAX (802.16e) terminals, where our products today set the benchmark in terms of low-power consumption, small footprints, and low cost. Altair is the only company in the WiMAX space today which exclusively focuses on the battery-operated, small form, factor handheld device market segment, as opposed to other players which develop solutions for PC peripherals, notebook computers, and CPEs. In other words, we have a highly optimized solution which competes with other “one size fits all” solutions in our addressable market.

In parallel, Altair has been developing a 3GPP LTE chipset for almost two years now. Our LTE solutions are based on an architecture that is very similar to that of the WiMAX product, and leverages the field proven WiMAX technology we have developed for over three years. We expect to have one of the first commercial LTE ASICs in the market, and are cooperating with tier one operators and infrastructure vendors on this front.

The third product line in which Altair is involved is the homegrown Japanese technology known as XGP, which is being deployed by Willcom Inc., Japan’s PHS operator. Altair had been awarded leading supplier position to Willcom, based on our lowest power, flexible 4G architecture.

Altair is a private company, and has raised a total of $48M in three rounds of financing, making it one of the better funded early stage fabless chip companies in the WiMAX space. Our headquarters are located in Hod-Hasharon, Israel, and we have offices in the US and Korea, as well as representatives in Japan and Taiwan.

Q: Can you give the highlights of WiMAX technology, in your opinion?

A: Mobile WiMAX is a mobile broadband technology that combines the throughputs of fixed broadband technologies such as DSL and cable/DOCSIS with the mobility support of cellular technologies such as GSM or CDMA. WiMAX is based on a different type of modulation than these traditional cellular technologies, called OFDMA (orthogonal frequency division multiplexed access), which is a relatively new communications modulation scheme (at least from the practical application perspective) that allows extending the transmitted signal bandwidth from a few MHz to 20MHz and beyond, delivering throughputs of a few tens of Mbytes/sec, compared to only a few Mbytes/sec using the most advanced cellular 3.5G technologies, which are based on older types of modulation such as Wideband-CDMA. Using OFDMA, the implementation of advanced antenna techniques, such as MIMO or beamforming, become much simpler and efficient, translating into higher spectral-efficiency (i.e. the number of information bits transmitted over a given spectrum resource). The combination of high-speed access with high spectral efficiency means a high-quality experience to the user and a low cost of service delivery to the carrier.

Q: Can you see WiMAX more as next generation of Wi-Fi or more like enhanced mobile standard?

A: Historically, mobile WiMAX was developed as a fixed wireless broadband access technology. It later evolved to become a mobile standard, and adopted many elements from the cellular world. In that sense, it is clear the mobile WiMAX is disrupting the traditional cellular communications ecosystems and is perceived as a springboard for non-traditional cellular vendors, such as Cisco, or ones that were having a difficult time competing with the dominant 2/3G players, such as Samsung or Motorola, into the next generation of mobile wireless communications. Technologies which were perceived from day one as threatening by the cellular community, such as Qualcomm’s Flarion technology, were blocked and eliminated from the standards landscape; so WiMAX, from that perspective, was driven by Intel and their companions in a very strategically-smart manner, keeping it under the 2/3G radar until gaining enough industry momentum to become self sustaining.

Q: What about handover between WiMAX and Wi-Fi or mobile standards like 3G?

A: These items are extremely important for WiMAX’s success as a cellular technology since coverage is expected to be spotty in the early days of deployment and session continuity with existing/legacy technologies is the key to gaining user acceptance. Handovers between WiMAX and WiFi are defined under the IEEE framework (802.21 – media independent handover, or MIH) and handovers with 3G are already defined under 3GPP and 3GPP2, which are the 3G standardization bodies. The WiMAX Forum™ ™ standards are behind these efforts and it has dedicated task groups to ensure standards and interoperability are in place. In the world of everything going pure-IP, or semi-IP such as IMS- this is really more of a political issue than a technical challenge to resolve.

Q: Can you compare WiMAX to other technologies such as LTE?

A: There are several competing standards claiming to be “4G.” It is important to understand that they are all based on the same fundamental elements, namely OFDMA modulation, use of smart antenna techniques, and flat all-IP networks. WiMAX, in contrast to competing technologies such as LTE, benefits from a two year time-to-market advantage, an open vendor ecosystem, and the potential for disruptive business models that are already beginning to change the world of mobile communications.

There is a lot of misconception and too many marketing campaigns that are attempting to shape regulators’ and investors’ opinions on this topic. The simple truth is that WiMAX and LTE are similar in nature as they are based on the same air-interface and network architectures. Spectral efficiencies such as download speeds and cell-ranges are expected to be very similar, with each having subtle technical advantages and disadvantages.

What this really is, is a political battle of evolution versus disruption. In the long run, I believe that LTE will play a more dominant role in the 4G space as it had been adopted by the most of the incumbent and powerful carriers such as Verizon, Vodafone, China Mobile, and others. WiMAX, on the other hand, had been adopted by Sprint (and then spun-off and sold to Clearwire), KDDI, KT, and SKT as well as a variety of competitive LEC/cable operators and ISPs – a pretty strong lobby as well. Don’t expect to be bored in the coming few years.

As a company that develops solutions for both WiMAX and LTE, we feel like guys that sell shovels in a gold rush – maybe a little overstated, but definitely a very unique position to be in.

Q: Sean Maloney, head of Intel’s sales and marketing, has also called for harmonization between WiMAX and LTE, pointing out the goals of unified broadband communications and common use of technologies. Do you think harmonization between these 4G technologies is possible? Needed?

A: I think it is possible, although not very likely. This harmonization proposal is about 3GPP adopting WiMAX as the TDD (time division duplexing) version of 4G while keeping LTE as the FDD (frequency division duplexing) version. When you peel off the technical arguments, you’re left with the strategic and political agendas of the stakeholders, which in my view today, are not in favor this harmonization.

While this debate keeps heating up, China Mobile (the largest cellular carrier in the world) published an LTE-TDD RFI recently, rendering a WiMAX 3GPP 4G-TDD version even more unlikely.

Q: Is WiMAX in competition or in cooperation with wireline technologies?

A: Wireless technologies in general face challenges competing with wireline technologies on quality of service – wires are a more stable and predictable medium to communicate over, and WiMAX is no different in this regard. Where WiMAX becomes really interesting is where (a) there is no wireline infrastructure, or when the infrastructure is available but suffers from low quality and high maintenance costs, or (b) where mobility is desired. I really don’t think WiMAX competes with DSL, cable, or fiber in the access space; it is much more complementary in covering the mobility aspect.

Q: What about commercial success of these standards? Do you think there is a need for further advanced standards like 802.16m which will be able to use even higher bandwidths and achieve higher spectral efficiency?

A: I think that by all standards mobile WiMAX is a success story, considering where it came from and its short history. Compare WiMAX to UWB for example – a great example of how conflicting interests almost killed a great technology, and that game is not over yet.

It is technology’s nature to evolve and improve, regardless of the concrete demand for it to do so. It is difficult for us today to anticipate the technology requirements that will exist for broadband service delivery five or ten years from now; however, it is clear that they will increase, not the other way around.

Q: What is in your forecast for WiMAX’s near future and, in particular, under economical recession?

A: In the near future, the service providers’ motivation is even more important than that of consumers since there is no application yet ready that consumes 10Mbps. The WiMAX service provider wants to increase monthly revenue and improve profitability because the voice revenue is declining. As a result, service providers want to offer advanced services. Since these services are heavy bandwidth consumers, they are uneconomical to deliver using current 3G technology. This is where WiMAX offers something that does not exist today – low cost/bit, high spectral efficiency which ultimately translates into solid and profitable business models. Recessions, such as the one we are witnessing, are not a supportive environment for new and emerging technologies to root, so is not going to be easy for WiMAX carriers and ecosystem vendors. The flip side of this is, however, that WiMAX has crossed a critical-mass maturity line while LTE is still behind, and is therefore in a position to entrench itself yet deeper before the pink color is back to investors’ cheeks and LTE could attempt to catch up. Besides, WiMAX has gained significant traction in geographies like Africa, the Middle East, and southeast Asia, which are much less affected by the crisis than American, European, or Japanese markets, so the exposure for WiMAX in this environment is smaller.

 

thefutureofthings.com

EDGE, WiMAX, 3G, 4G: what’s the difference?

This post aims to provide some insight into some of the most widely used mobile technologies in the Caribbean, and compares their real life download speeds against each other.

Recently in the Caribbean, the main mobile providers have begun to roll out “4G” services. Most mobile users are aware of “3G”, and believe their service is based on 3G technology, but is that true? Moreover, what should be their expectations regarding the much anticipated 4G roll out? This post aims to provide some insight by first highlighting the major technologies that are being used, and thereafter by comparing the data rates of popular technology standards against each other.

What is 3G? What is 4G? Where do they come from?

In order to place today’s technology in the proper context, it is useful to consider how and from where they have developed. The most significant starting point is the GSM (Global System for Mobile communications) standard, as reflected in Figure 1.

Figure 1: Evolution of GSM technology (Source ICT Pulse)

GSM is a second generation mobile technology (2G) – the most widely implemented of its time. It is also the foundation for a number of subsequent standards and technologies. A key feature of the GSM standard was that voice conversations were digitised, as opposed to earlier mobile technologies which were analogue-based. The digital format allowed transmissions to be encrypted and SMS text messaging.

Third Generation (3G) – Third generation mobile technology further developed the data carrying capacity of 2G, from SMS messaging to include mobile Internet, mobile video and TV. The caption “3G” covers broad range of standards, including EDGE, HSPA+, WiMAX, and LTE, and with each new standard, data transmission speeds increased, which in turn improved the mobile phone’s data access capability. Most 3G standards are far more efficient than 2G for voice transmissions, although operators have marketed 3G around its data capability. Nevertheless, there are limitations endemic to the 3G platform that will not satisfy the demand for broadband speeds and capabilities on mobile phones.

Fourth Generation (4G) – Fourth generation mobile technology has truly been designed to fully realise mobile broadband.  Standards such as WiMAX and HSPA+, which are currently being used by Digicel and LIME, respectively, are generally considered precursors to the full 4G standard, but nevertheless could fall under the 4G umbrella. Standards that fully satisfy the 4G classification are LTE Advanced and WirelessMAN-Advanced (also called “WiMAX 2”), but they are still being finalised and will not be ready for adoption before 2012.

As discussed in an earlier post, Evolving Over the Long Term: Considerations towards implementing LTE, one of the main characteristics of the 4G standard as defined by the International Telecommunications Union (ITU), is that the networks are all IP packet switched networks. This means that no distinction is being made between voice packets and data packets, and consequently voice and data traffic, which will have serious implications on current pricing structures for mobile services.

Is my mobile phone’s technology faster than yours?

Having outlined the evolution of mobile technologies, the key point to note is that each generation, and for the most part each standard, is an improvement on earlier generations or standards. However, with the variety of standards available and being used by mobile network operators, it can sometimes be challenging to fully appreciate their impact on the mobile phone user’s experience. Table 1 below, highlights the maximum download and upload speeds for some of the major standards that are being used, as well as those proposed for 4G.

Table 1: Maximum data speeds for select mobile standards (Source: Discuss Tech)

With regard to WiMAX/WiMAX 2 and LTE/LTE Advanced, it is important to note that the maximum data speeds vary based on the relative speed of the user’s movement. For example, with regard to WiMAX 2 and LTE Advanced, if the user is in a high-speed situation, for example in a moving vehicle or on a train, the maximum possible data speed is around 100 Mbps (download) and 50 Mbps (upload). On the other hand, if the user is stationary or even walking, download and upload speeds of up to 1 Gbps and 500 Mbps, respectively, can be achieved.

But in the real world, how do the technologies measure up against each other? Table 2 attempts this comparison by calculating typical download times across key mobile standards used in the Caribbean. It is stressed that the maximum download speeds presented in Table 1 have not been used, since very rarely do mobile users achieve such speeds. The norm tends to be within the region of 40% – 50% of the maximum speed, but it could be lower, depending on network traffic, distance away from cell tower, etc.

.

Standard (speed)Item (data size) EDGE(175Kbps) WiMAX(5Mbps) LTE(10Mbps) HSPA+(21Mbps)
Small web page (100 KB) 4.6s 0.2s 0.1s <0.1s
Complicated website (250 KB) 11s 0.4s 0.2s 0.1s
Image from 5M pixel camera (1.5 MB) 1m 10s 2.4s 1.2s 0.6s
MP3 music file, good quality (5 MB) 3m 54s 8s 4s 1.9s
Complete CD (650 MB) 8h 27m 17m 20s 8m 40s 4m 8s
Movie (1.5 GB) 19h 58m 40m 58s 20m 29s 9m 45s

Table 2: Comparison of download times for select mobile standards used in the Caribbean (Source: 123myip.co.uk)

Final remarks

Although the telecommunications industry is anxiously awaiting the launch of 4G, it is unlikely that there will be an immediate wholesale abandonment of 3G and pre-4G technologies. Experts anticipate, into the foreseeable future, that 3G technologies will remain for voice traffic, with a 4G overlay for data, until appropriate models and mechanism are established to facilitate comprehensive billing of IP traffic.

Further, the race is on to see which standard, LTE Advanced or WiMax 2, will be ready first and will be implemented by mobile network operators, equipment manufacturers and handset providers. It is likely that one of the standards will eventually become an orphan, especially if there are deployment or operation issues. Hence it is important that mobile operators and regulators get it right.

___________

www.ict-pulse.com

WiMax vs WiFi - Difference between WiFi and WiMax Technologies

As wireless networking tends to spread itself outside offices and houses, it becomes utterly needed to invent protocols and systems which could support large scale networking with high data speeds. Several technologies for such wide accesses have been in the communications market such as 2G, 3G and the recent, 4G.  There are, however, many tradeoffs in using these technologies on a larger basis such as providing internet or stream multimedia wirelessly. This is why a new protocol, named WiMAX was incepted. Linguistically, it seems like an extended technological term to Wi-Fi, but there are several differences between these two protocols. This article will explore about various differences between WiFi and WiMax - the two wireless connectivity technologies share.

1. Abbreviated Term: Wi-Fi stands for Wireless Fidelity, a term that was more of a marketing stint as it rhymed with Hi-Fi. WiMAX, on the other hand, stands for Worldwide Interoperability for Microwave Access, a term fulfilling technological as well as commercial requirements.

 

2. Official Release: Wi-Fi was officially launched in the year 1997 where as WiMAX came to the picture in the year 2004.

 

3. IEEE Standards: Wi-Fi has been defined under IEEE 802.11x standards where x is various Wi-Fi versions. WiMAX is standardized under 802.16y family of wireless networking where y refers to various WiMAX versions.

 

4. Versions of the Standard: Depending on several factors such as frequency, range, encryption, application etc., Wi-Fi has several versions of it such as 802.11b, 802.11g, 802.11n.

On the similar factors, WiMAX has a number of different versions too:802.16a, 802.16d and 802.16e are some popular WiMAX versions.

 

5. Frequency Band: Wi-Fi has been defined under ISM bands where user has to pay no extra charging for utilizing those bands. On the contrast, there is no bar on frequency usage in the WiMAX. This means that WiMAX protocols might work in the ISM bands or they might use a licensed frequency version for which the user probably would be charged.

 

6. Range: An ideal Wi-Fi based network reaches around 100metres as it maximum range whereas an ideal WiMAX network can reach about 80-90kilometers in terms of range.

 

7. Data Transfer Rates: Wi-Fi based networking can transfer data at speeds up to 54mbps. On the other hand, WiMAX networks exchange data at speeds upto 40mbps. In WiMAX, data transfer rates have more variation as distances to be covered are quite larger.

 

8. Channel Bandwidth: Wi-Fi networks have a channel bandwidth of 20MHz, whereas WiMAX networks have a flexible bandwidth option which ranges from 1.25MHz to 20MHz.

 

9. Bandwidth Efficiency: This term refers to bits of information sent per second per unit frequency. This is a measure of how qualitatively the channel is managed by the network. Bandwidth efficiency of a WiMAX channel (upto 5bps/s/Hz) is theoretically twice as efficient as Wi-Fi based networks (upto 0.44bps/s/Hz for 802.11a and 2.7bps/s/Hz for b/g/n standards).

 

10. Difference in MAC Layer: MAC layer is an essential part of an OSI model. It defines communication procedures that a protocol uses.  Wi-Fi’s MAC layer uses CSMA/CA protocol which is not connection oriented while that in WiMAX is connection oriented.

 

11. Encryption Techniques: Encryption techniques in WiMAX include Triple Data Encryption Algorithm and Advanced Encryption Standards. On the other hand, in Wi-Fi, encryption techniques are Advanced Encryption Standard (AES) and RC4.

 

12. Authentication: Authentication is process under Network Security where connection is checked for its identity before being established.  Both these wireless networking technologies apply different set of protocols for authentication purposes. Wi-Fi uses Extensible Authentication Protocol (EAP) Wired Equivalent Privacy (WEP) security algorithms depending on the Wi-Fi version. On the other hand, WiMAX uses X.509 or PKMv2 as authentication algorithms.

 

13. Applications: Wi-Fi and WiMAX, though being used for same purpose of data exchange, are designed to cater two completely different needs. Wi-Fi is needed to serve for household and corporate needs of interconnectivity. Wi-Fi technology connects printers to computer, gaming consoles to router etc.

WiMAX serves a larger inter-operable network. WiMAX can be used to provide internet services to a larger area where it can serve households, mobile phones and even Wi-Fi spots. WiMAX has a different hardware specification and currently WiMAX serving towers tend to be as tall as Wi-Fi towers. On the other hand, Wi-Fi antennas are small enough to be placed on 5 inch by 3 inch routers.

 

 

www.engineersgarage.com

188.916 Introduction to Security: WİMAX NEDİR?

WİMAX NEDİR?

              WiMAX(Worldwide Interoperability for Microwave Access),  son kullanıcıya kablo ve ADSL alternatifi olarak genişband erişim sağlayabilecek standart-tabanlı kablosuz erişim teknolojisidir. (Dünya çapında,birlikte çalışabilir, mikrodalga erişim” olarak karşımıza çıkmaktadır.)

              IEEE 802.16 standartına uyumlu olarak, “sabit”, “taşınabilir” ve son aşamada “mobil” özelliği geliştirelecek WiMAX genişband erişim teknolojisinde, baz istasyonları 3-10 km lik kapsama alanında, kanal başına 40mbps kapasite sağlıyabilme özelliğinde geliştirişmektedir. Bu kapasite, yüzlerce Kurumsal müşteriye T-1, binlerce bireysel müşteriye ADSL hızında erişim sağlayabilecektir.

WİMAX TÜRLERİ

•          802.16e: Nokia Siemens Networks'ün de sunmuş olduğu en çok tercih edilen geniş bant kablosuz ve hareket halinde kullanmaya uygun olan WiMax çözümleri.

•          802.16d: Hareketli olmayan noktalar için daha çok kullanılan çözüm.

•          Flash OFDM: 3G'den hızlı olan ve Avrupa'da trenlerde daha çok kullanılan WiMax çözümü.

WİMAX NASIL ÇALIŞIR

               Wimax aslında ip tabanlı kablosuz erişim teknolojisidir. Bununla beraber hem fiberoptik bağlantılar, kablolu modemler kullanan sistemler ve DSL bağlantılar gibi kablolu şebekelere hem de 3G şebekelere entegre olabileceği için çeşitli şekillerde hizmet tiplerini desteklemektedir.     

               Bugün ofislerde ve diğer kapalı alanlarda kullanılan wireless cihazları 30-40 metrelik mesafede yaklaşık 10 Mbt/sn hızında bağlantı sağlarken 802.16 olarak da adlandırılan WiMAX 50 km’lik bir alanda 70 Mbt/sn hızında internet bağlantısı sağlayabiliyor. WİMAX DSL ve kablolu interneti geride bırakacak kadar geniş imkânlar sunuyor. Wimax sadece taşınabilir bilgisayarlarda değil aynı zamanda sabit bilgisayarlar için de interneti kablosuz hale getirmeyi hedefliyor. Bu demek oluyor ki kullanıcılar internet erişim ihtiyaçlarını çatıya ya da pencereye kurulacak uydu anteni benzeri bir antenle evlerindeki ya da ofislerindeki sabit bilgisayarlarında da karşılayabilecekler.

FARKLI GENİŞLİKTEKİ AĞLAR VE KULLANIMLARI

WPAN (Wireless Personal Area Network)

                 Bu standart kısa mesafede sınırlı sayıda aygıtı bağlamaktadır.10 metreden az mesafede kişisel bağlantı hizmeti sunmayı amaçlamıştır. Hız 7.5 GHz frekans bandında hız 500 Mbps’ye kadar ulaşmaktadır, bu standardın en bilinen teknolojisi bluetooth teknolojisidir.

 WLAN (Wireless Local Area Network)

                 Bina, okul, hastane, kampus gibi sınırlı coğrafi alanda kurulan, çok sayıda kişisel bilgisayarın yer aldığı ve iletişimin RF (Radyo Frekansı) veya kızılötesi teknolojisi ile yapıldığı iletişim ortamıdır. WLAN sistemlerinin mesafesi 25–100 metre civarındadır. WLAN’ lardaki Wi-Fi teknolojisinin 802.11g standardı ile hız 54 Mbps’ye ulaşmıştır; fakat bu hız 100 metre mesafe için geçerlidir.

WMAN (Wireless Metropolitan Area Network)

                 MAN’lar genellikle bir kampus veya bir şehir mesafesindeki geniş şebekelerdir. WMAN’lar da bu teknolojinin kablosuz bağlantı şeklidir. Bu teknoloji ile birkaç kilometrelik alanda 11 GHz’in altındaki frekanslarda hız 75 Mbps civarındadır. Bu standartlarda çalışan teknolojiler arasında sabit ve göçebe Wimax (802.16d) ve mobil Wimax (802.16e)’de gösterilebilir.

WWAN (Wireless Wide Area Network)

                   Bu çalışmalar neticesinde  900, 1800 ve 1900 MHz’de 1.5 – 8 km’lik mesafedeki hız 348 Kbps olarak elde edilmiştir. WWAN teknolojileri ile telefonlar, laptop’lar ile taşınabilir cihazlara  yüksek hızlı veri hizmetlerinin sunulması hedeflenmektedir.

WiMAX’İNDİĞER KABLOSUZ TEKNOLOJİLERE GÖRE AVANTAJLARI

1)Çoklu yol etkileşimi

2)Gecikme dağılımı

3)Sağlamlık

     Çoklu yol etkileşimi ve gecikme dağılımı özelliği, kullanıcı baz istasyonunun görüş açısı dışındayken de iyi bir performans gerçekleşmesini sağlıyor.

WİMAX TEKNOLOJİSİNİN KULLANDIĞI FREKANSLAR

            Wimax’in karşılaştığı sorunlardan birisi de ülkeden ülkeye değişen frekans planlamasıdır. Buna verilebilecek en güzel örnek ABD ile Avrupa arasında kullanılan farklı GSM frekanslarıdır.

              Ülkelerin çeşitli kablosuz iletişim teknolojileri için kendilerine özgü ihtiyaçlarının karşılanması bakımından taşınabilir cihazların çoklu bandı desteklemesi ile maliyet azalacaktır. Bunu yanında ürün karmaşası da ortadan kalkabilir. Fakat yine de standartlar ve ülke düzenlemeleriyle dünya çapında frekans uyumluluğunu, dolayısıyla verimliliği sağlamak için endüstride çalışmalar devam etmektedir.

            Amerika’da frekans bantları 2.5 – 2.7 GHz’dir. Avrupa, Latin Amerika ve Asya 1.5GHz frekans bandını tahsis etmektedir. Aşağıdaki şekilde Wimax için kullanılabilir bantlar ve frekans aralıkları verilmiştir.

WİMAX &Wİ-Fİ KARŞILAŞTIRILMASI

           WIMAX, WiFi ve Ethernet ile aynı LLC katmanını kullanır. Bu yüzden hem WAN, hem de LAN bağlantıları WIMAX'a köprülenebilir.

          WIMAX için tasarlanan MAC katmanı değişik fiziksel katmanlarla uyumlu halde tasarlandığı için üreticilere geniş bir yelpaze sundu. Böylelikle WIMAX kablosuz genişbant internetin yanında cep telefonları, avuçiçi bilgisayarlar gibi araçlardan da sinyal alabiliyor. Bu gibi nedenler GSM şirketlerinin de WIMAX'e ilgi duymasına sebep oldu.

           WIMAX için tasarlanan MAC katmanı WiFi'den farklı olarak çalışıyor. WiFi'de tüm kullanıcılar bir erişim noktasına aynı anda bir bakıma birbirleri ile yarışarak istek gönderirler. Bu tip bir gönderide istekler rastgele bir biçimde sıralanır. Bu durumda erişim noktasına uzak olan istemci hep sonlarda sıraya girer. Belki kendisine sıra gelene kadar bağlantının ölü olduğuna kanaat getirip, bağlantının tekrar tekrar sonlandırılmasına sebep olur. WIMAX'de ise bağlantı noktasına erişmek isteyen istemciler sıraya alınır. Böylelikle her istemci sadece bir kere yarışa girer. İstemcinin uzaklığına göre beli bir zaman aralığında erişim verilir. Bu tip bir sıralama algöritması ile bant genişliği daha da verimli kullanılır.

WİMAX’IN SAĞLADIĞI ÖZELLİKLER

1.      11 GHz altındaki lisanslı ve lisanstan muaf bant işlemleri desteği,

2.      Telekomünikasyon işletmecisinin maliyetini azaltan yüksek görüş hatlı verimlilik,

3.      Daha güvenli iletim için ileri hata düzeltme,

4.      Mesafeyi ve kapasiteyi artırmak için gelişmiş anten teknikleri desteği,

5.      50 km’ye kadarki mesafelerde müşteriye ulaşmak için bant genişliğinden taviz veren uyarlanabilir modülasyon desteğidir.

WİMAX’İN YAYILIMI İLE SEKTÖRDE MEYDANA GETİRDİĞİ  ETKİ

1.      Bileşen ücretleri için yeni iş hacmi oluşturmak,

2.      İşletmeciler açısından, donanım maliyetini aşağıya çeken ve ticari markalaşma ile başarılamayan fiyat/performans gelişmesini hızlandıran ortak bir platform oluşmaktadır.

3.      Tüketicilere getirileri ise; binaya erişimin zor olduğu kent merkezleri, abonelerin merkez ofisten çok fazla uzak olduğu banliyöler ve altyapının zayıf olduğu düşük nüfus  yoğunluklu kırsal alanlar gibi özellikle hizmet eksiğinin bulunduğu alanlar için, daha fazla genişbant erişim seçeneğinin olması ve bunun yaratacağı rekabet ile daha düşük aylık abonelik fiyatlarına yol açması olacaktır.

WİMAX TEKNOLOJİSİ UYGULAMALARI

1-Talebe Göre Genişbant: Wimax teknolojisinin servis sağlayıcılara getirdiği diğer önemli bir kolaylık, 802.11 kablosuz erişim noktalarını kullanan, yüzlerce veya binlerce kullanıcılı ticaret fuarları, ulusal ya da uluslararası yarışmalar gibi geçici organizasyonlarda, talebe bağlı yüksek hızlı bağlantıları anında konfigüre edebilme imkanı vermesidir.

2- Yapılara Genişbant Sunmak: Kablo ve DSL uygulamalarındaki sınırlamalar bu teknolojilerin çok miktardaki genişbant müşterilerine ulaşmasını engellemektedir.

Wimax’in yüksek bant genişliği, doğal esneklik ve düşük maliyet özellikleri sayesinde kablolu ve ticari marka kablosuz teknoloji sınırlamalarının üstesinden gelinmesini sağlamaktadır.

3- Kırsal Kesimler: Wimax kablosuz internet teknolojisi, düşük nüfus yoğunluğu nedeniyle hizmet gitmemiş kırsal ve uzak alanlar için makul bir tercihtir. Böyle alanlarda kamu hizmeti veren kuruluşlar, hizmet götürmek için yerel bir Kablosuz İnternet Servis Sağlayıcı (Wireless Internet Service Provider -WISP) ile birlikte çalışabilir.

4- Fiber Optik Kablonun Son Kullanıcıya Ulaştırılması: Günümüzde aboneler genişbant ihtiyacını DSL ile karşılamaktaysa da yapılacak yeni erişim şebekesi yatırımlarında genişbant erişim ihtiyacını da karşılayacak fiber optik kablo altyapısı tercihler sıralamasında ilk sıralarda bulunmaktadır. Bu uygulamanın yaygınlaşmasındaki en büyük engel, maliyettir. Bu sorununu çözmek için, fiberoptik altyapısını ve onun masraflarını minimize etmek amacıyla, genişbant hizmetlerin abonelere ulaştırılmasında yüksek bant genişlikli Wimax teknolojisini kullanabilirler.

6. Ses ve Görüntü İletimi: Yüksek bant genişliği VoİP telefon hizmetlerinin kaliteli bir şekilde gerçekleşmesini dar bant genişliğine göre önemli ölçüde gerçekleştirir. Wimax’in sağladığı bant genişliği ses ve görüntü iletimi için gerekli olan düşük gecikme süresi özelliği sağlar.

    

TÜRKİYEDE WİMAX

            Wimax’in ülkemizdeki durumu ile diğer ülkelerdeki durum arasında fark yoktur. Diğer ülkeler için sertifikasyonsuz kurulan Wimax şebekeleri dışında diğer ülkelere verilen test izinleri Türkiye için de verilmiştir. Başvuruları test ve deneme için yapan ülkemizde şu ana kadar yapılan 10 başvuru kabul edilmiş olup Ankara, İstanbul, Gebze, Eskişehir ve Yozgat illerinde çeşitli denemeler gerçekleştirilmiştir.

Tek kırsal yerleşim başvurusu olan Yozgat ili Boğazlıyan ilçesinde test ve deneme çalışmaları başlamıştır. Yozgat’ta kurulan Wimax şebekesinin amacı, “Milli Eğitim Bakanlığı İnternete Erişim Projesi” kapsamında  42.000 okula genişbant internet erişiminin sağlanması hedefine ulaşabilmektir.

Bu şebeke Türk Telekomünikasyon A.Ş tarafından geliştirilmekte olup, coğrafi nedenler ve ADSL teknolojisinin mesafeyle ilgili sınırlamalarından dolayı 3.5 GHz bandında çalışan ADSL erişimine alternatif olarak sunulmaya çalışılmaktadır.

Superonline 1 Şubat 2006 tarihinden başlamak üzere Telekomünikasyon Kurumu’ ndan 3,5 GHz frekans bandında WiMAX Test ve Deneme İzni aldı. İzin kapsamında İstanbul Beşiktaş ve Levent olmak üzere iki lokasyonda baz istasyonlarını kurdu ve testlere başladı.

İstanbul’da toplam 28 MHz bant genişliğinde, 3465-3472 MHz, 3493-3500 MHz, 3565-3572 MHz ve 3593-3600 MHz frekans bantlarında sistemler kuruldu.

 3.5GHZ TÜRKİYEDEKİ DURUMU

3.5 GHz Türkiye’de Türk Telekom A.Ş.’nin kullanımında. Herhangi bir lisans veya yetkilendirme dahilinde bir kullanım sözkonusu değil. Geçmişte Kablosuz Telefon Hizmetleri kapsamında TT’nin kullanımına verilmiş.

Bugün gelinen noktada, 30’dan fazla ülkede 160 işletmecinin ticari ve test amaçlı kurduğu baz istasyonu sayısı yaklaşık 5000’e ve abone ekipmanlarının sayısı ise onbinlere ulaşmıştır.

            4G’ye geçiş sürecinde Wimax, gerek arkasındaki teknolojisi gerekse de her zaman her yerde var olabilme hedefi ile önemli bir rol üstlenerek 4G hedeflerinin şekillenmesine katkıda bulunmakta ve hatta belki de temelini oluşturmaktadır.

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