Applications WiMAX

The race is on in the service provider community to offer "triple play" (voice, video and data) or "quadruple play" (voice, video data as well as mobile voice and data). Some ser-vice providers are attempting to do this with 3 or 4 dissimilar networks as illustrated in the figure below. For example, at the time of this writing, Qwest Communications Inter-national sold their own voice and broadband data for the residential market, Dish Net-works for satellite TV and resells Sprint Nextel cellular service. Reselling other service providers services does not generate the profit margins as selling one's own services does. Given the vertical orientation of legacy systems like cable TV (only does TV), circuit-switched voice services (like cell phone networks-designed almost entirely for voice), it is difficult and expensive to offer more than one type of service on any one "stovepipe" network. The solution is IP Multimedia Subsystems (IMS).



IMS Vision

The vision for IMS is that an all-IP network will allow a subscriber to access a multitude of services regardless of how they access the network (cable TV modem, DSL, cellular, Wi-Fi, or WiMAX). Very simply put, the subscriber will be able to access any service on any device

IMS began as a concept in the cell phone industry to offer voice, short messaging service (SMS) and video on cell phones. It utilizes a simple three-layer architecture consisting of the Connectivity Layer (similar to the physical layer in the OSI model), a Control Layer, which provides switching and signaling functions, and the Service Layer where applica-tions such as IPTV and VoIP features are offered. Running parallel to those function layers are a range of support systems, which control security and QoS across the network. The signaling protocol known as Session Initiation Protocol (SIP) provides signaling across the network.

Fixed Wireless (IEEE 802.16-2004) Applications

Perhaps the most lucrative application for WiMAX is that of substitute for the telephone company's copper wire. This is achieved through fixed wireless solutions. A majority of US businesses and residences receive their telephone service and internet access via the telephone company's copper wires. A T1 data line from the telephone company may re-tail for $800/month in many US cities. About 50% of that expense is "local loop" charges or paying to use the telephone company's copper wire to access a wider network. As the diagram below illustrates, a WiMAX service provider could purchase the bandwidth equivalent of a T1 (1.54 Mbps) at, say, $45 and resell to an enterprise customer for $400. Through oversubscription (overselling), that service provider could realize a multiple of that profit.

PSTN bypass for fixed wireless T1/E1/DS3 substitute


Source from www.wimax.com/wimax/wimax.htm

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Compare WiMAX with WiFi

How WiMAX can be used for Broadband Wireless Access (BWA):

Typical areas of application of WiMAX are as given below:

1. Residential and SOHO High Speed Internet Access. The main contenders for residential and SOHO market are the DSL, and Cable Internet technologies. These technologies have already established a market presence, and have proven track record in meeting the demands of the residential and SOHO customers. WiMAX provides an alternative to existing access methods, where it is not feasible to use DSL or Cable Internet. Typical application will be in remote areas where it is not economically feasible to have a DSL or Cable Internet. WiMAX is also expected to be more reliable due to wireless nature of communication between the customer premises and the base station. This is particularly useful in developing countries where the reliability and quality of land-line communications infrastructure is often poor.
2. Small and Medium Business. The WiMAX WBA is well suited to provide the reliability and speed for meeting the requirements of small and medium size businesses in low density environments. One disadvantage of WiMAX is the spectral limitation, in other words limitation of wireless bandwidth. For use in high density areas, it is possible that the bandwidth may not be sufficient to cater to the needs of a large clientele, driving the costs high.
3. WiFi Hot Spot Backhaul: Another area where WiMAX connectivity is for WiFi hot spots connectivity. As of now, there have been several WiFi hotspots and a WiMAX backhaul provides full wireless solution to these wireless networks.


Compare WiMAX with WiFi:

The mail distinction between WiFi and WiMAX is speed and coverage distances. WiFi has a typical bandwidth of 2MBps whereas WiMAX can have a bandwidth of up to 75MBps. The coverage distances also differ to a great extent. A WiFI hotspot typically covers a few hundred feet radius (fraction of a kilometer) whereas a WiMAX can practically cover up to a distance of 10 kilometers (6 miles). One probable application of MAN is to link several WiFi networks together with WBA (Wireless Broadband Access) using WiMAX technology.

Current trends in WiMAX usage:

The technology is relatively new, and several vendors are coming up with the support infrastructure. Intel and Fujitsu are among the leading providers of WiMAX compliant SoC chips. The SoCs’ can be used to make Customer Premise Equipment (CPE) that are used to access WBA base stations. It is expected that 802.16 compliant systems would be in place by the end of 2005.

WiMax References:
http://www.wimaxxed.com/wimaxxed_news/wimax_broadba.html
http://computer.howstuffworks.com/wimax1.htm
http://www.wimaxforum.org/news/downloads/WiMAX-The_Business_Case-Rev3.pdf

Source from www.tutorialsweb.com/wimax/wimax.htm

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WiMAX Coverage and Speed

WiMAX operates on the same general principles as WiFi -- it sends data from one computer to another via radio signals. A computer (either a desktop or a laptop) equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access.

The fastest WiFi connection can transmit up to 54 megabits per second under optimal conditions. WiMAX should be able to handle up to 70 megabits per second. Even once that 70 megabits is split up between several dozen businesses or a few hundred home users, it will provide at least the equivalent of cable-modem transfer rates to each user.

The biggest difference isn't speed; it's distance. WiMAX outdistances WiFi by miles. WiFi's range is about 100 feet (30 m). WiMAX will blanket a radius of 30 miles (50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter. Of course, at that distance, terrain, weather and large buildings will act to reduce the maximum range in some circumstances, but the potential is there to cover huge tracts of land.

IEEE 802.16 Specifications

* Range - 30-mile (50-km) radius from base station
* Speed - 70 megabits per second
* Line-of-sight not needed between user and base station
* Frequency bands - 2 to 11 GHz and 10 to 66 GHz (licensed and unlicensed bands)
* Defines both the MAC and PHY layers and allows multiple PHY-layer specifications (See How OSI Works)

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WiMAX Indonesia

WiMAX adalah singkatan dari Worldwide Interoperability for Microwave Access, merupakan teknologi akses nirkabel pita lebar (broadband wireless access atau disingkat BWA) yang memiliki kecepatan akses yang tinggi dengan jangkauan yang luas. WiMAX merupakan evolusi dari teknologi BWA sebelumnya dengan fitur-fitur yang lebih menarik. Disamping kecepatan data yang tinggi mampu diberikan, WiMAX juga merupakan teknologi dengan open standar. Dalam arti komunikasi perangkat WiMAX diantara beberapa vendor yang berbeda tetap dapat dilakukan (tidak proprietary). Dengan kecepatan data yang besar (sampai 70 MBps), WiMAX dapat diaplikasikan untuk koneksi broadband ‘last mile’, ataupun backhaul.

Perkembangan Teknologi Wireless

Standar BWA yang saat ini umum diterima dan secara luas digunakan adalah standar yang dikeluarkan oleh Institute of Electrical and Electronics Engineering (IEEE), seperti standar 802.15 untuk Personal Area Network (PAN), 802.11 untuk jaringan Wireless Fidelity (WiFi), dan 802.16 untuk jaringan Worldwide Interoperability for Microwave Access (WiMAX).

Pada jaringan selular juga telah dikembangkan teknologi yang dapat mengalirkan data yang overlay dengan jaringan suara seperti GPRS, EDGE, WCDMA, dan HSDPA. Masing-masing evolusi pada umumnya mengarah pada kemampuan menyediakan berbagai layanan baru atau mengarah pada layanan yang mampu menyalurkan voice, video dan data secara bersamaan (triple play). Sehingga strategi pengembangan layanan broadband wireless dibedakan menjadi Mobile Network Operator (MNO) dan Broadband Provider (BP). Perbandingan beberapa karakteristik sistem wireless data berkecepatan tinggi digambarkan oleh First Boston seperti berikut.

Sekilas Tentang WiMAX

WiMAX (Worldwide Interoperability for Microwave Access) adalah sebuah tanda sertifikasi untuk produk-produk yang lulus tes cocok dan sesuai dengan standar IEEE 802.16. WiMAX merupakan teknologi nirkabel yang menyediakan hubungan jalur lebar dalam jarak jauh. WiMAX merupakan teknologi broadband yang memiliki kecepatan akses yang tinggi dan jangkauan yang luas. WiMAX merupakan evolusi dari teknologi BWA sebelumnya dengan fitur-fitur yang lebih menarik. Disamping kecepatan data yang tinggi mampu diberikan, WiMAX juga membawa isu open standar. Dalam arti komunikasi perangkat WiMAX diantara beberapa vendor yang berbeda tetap dapat dilakukan (tidak proprietary). Dengan kecepatan data yang besar (sampai 70 MBps), WiMAX layak diaplikasikan untuk ‘last mile’ broadband connections, backhaul, dan high speed enterprise.

Yang membedakan WiMAX dengan Wi-Fi adalah standar teknis yang bergabung di dalamnya. Jika WiFi menggabungkan standar IEEE 802.11 dengan ETSI (European Telecommunications Standards Intitute) HiperLAN sebagai standar teknis yang cocok untuk keperluan WLAN, sedangkan WiMAX merupakan penggabungan antara standar IEEE 802.16 dengan standar ETSI HiperMAN.

Standar keluaran IEEE banyak digunakan secara luas di daerah asalnya, Amerika, sedangkan standar keluaran ETSI meluas penggunaannya di daerah Eropa dan sekitarnya. Untuk membuat teknologi ini dapat digunakan secara global, maka diciptakanlah WiMAX. Kedua standar yang disatukan ini merupakan standar teknis yang memiliki spesifikasi yang sangat cocok untuk menyediakan koneksi berjenis broadband lewat media wireless atau dikenal dengan BWA.

Spektrum Frekuensi WiMAX

Sebagai teknologi yang berbasis pada frekuensi, kesuksesan WiMAX sangat bergantung pada ketersediaan dan kesesuaian spektrum frekuensi. Sistem wireless mengenal dua jenis band frekuensi yaitu Licensed Band dan Unlicensed Band. Licensed band membutuhkan lisensi atau otoritas dari regulator, yang mana operator yang memperoleh licensed band diberikan hak eksklusif untuk menyelenggarakan layanan dalam suatu area tertentu. Sementara Unlicensed Band yang tidak membutuhkan lisensi dalam penggunaannya memungkinkan setiap orang menggunakan frekuensi secara bebas di semua area.

WiMAX Forum menetapkan 2 band frekuensi utama pada certication profile untuk Fixed WiMAX (band 3.5 GHz dan 5.8 GHz), sementara untuk Mobile WiMAX ditetapkan 4 band frekuensi pada system profile release-1, yaitu band 2.3 GHz, 2.5 GHz, 3.3 GHz dan 3.5 GHz.

Secara umum terdapat beberapa alternatif frekuensi untuk teknologi WiMAX sesuai dengan peta frekuensi dunia. Dari alternatif tersebut band frekuensi 3,5 GHz menjadi frekuensi mayoritas Fixed WiMAX di beberapa negara, terutama untuk negara-negara di Eropa, Canada, Timur-Tengah, Australia dan sebagian Asia. Sementara frekuensi yang mayoritas digunakan untuk Mobile WiMAX adalah 2,5 GHz.

Isu frekuensi Fixed WiMAX di band 3,3 GHz ternyata hanya muncul di negara-negara Asia. Hal ini terkait dengan penggunaan band 3,5 GHz untuk komunikasi satelit, demikian juga dengan di Indonesia. Band 3,5 GHz di Indonesia digunakan oleh satelit Telkom dan PSN untuk memberikan layanan IDR dan broadcast TV. Dengan demikian penggunaan secara bersama antara satelit dan wireless terrestrial (BWA) di frekuensi 3,5 GHz akan menimbulkan potensi interferensi terutama di sisi satelit.

Elemen Perangkat WiMAX

Elemen/ perangkat WiMAX secara umum terdiri dari BS di sisi pusat dan CPE di sisi pelanggan. Namun demikian masih ada perangkat tambahan seperti antena, kabel dan asesoris lainnya.

Base Station (BS)

Merupakan perangkat transceiver (transmitter dan receiver) yang biasanya dipasang satu lokasi (colocated) dengan jaringan Internet Protocol (IP). Dari BS ini akan disambungkan ke beberapa CPE dengan media interface gelombang radio (RF) yang mengikuti standar WiMAX. Komponen BS terdiri dari:

* NPU (networking processing unit card)
* AU (access unit card)up to 6 +1
* PIU (power interface unit) 1+1
* AVU (air ventilation unit)
* PSU (power supply unit) 3+1

Antena

Antena yang dipakai di BS dapat berupa sektor 60°, 90°, atau 120° tergantung dari area yang akan dilayani.

Subscriber Station (SS)

Secara umum Subscriber Station (SS) atau (Customer Premises Equipment) CPE terdiri dari Outdoor Unit (ODU) dan Indoor Unit (IDU), perangkat radionya ada yang terpisah dan ada yang terintegrasi dengan antena.

Teknologi WiMAX dan Layanannya

BWA WiMAX adalah standards-based technology yang memungkinkan penyaluran akses broadband melalui penggunaan wireless sebagai komplemen wireline. WiMAX menyediakan akses last mile secara fixed, nomadic, portable dan mobile tanpa syarat LOS (NLOS) antara user dan base station. WiMAX juga merupakan sistem BWA yang memiliki kemampuan interoperabilty antar perangkat yang berbeda. WiMAX dirancang untuk dapat memberikan layanan Point to Multipoint (PMP) maupun Point to Point (PTP). Dengan kemampuan pengiriman data hingga 10 Mbps/user.

Pengembangan WiMAX berada dalam range kemampuan yang cukup lebar. Fixed WiMAX pada prinsipnya dikembangkan dari sistem WiFi, sehingga keterbatasan WiFi dapat dilengkapi melalui sistem ini, terutama dalam hal coverage/jarak, kualitas dan garansi layanan (QoS). Sementara itu Mobile WiMAX dikembangkan untuk dapat mengimbangi teknologi selular seperti GSM, CDMA 2000 maupun 3G. Keunggulan Mobile WiMAX terdapat pada konfigurasi sistem yang jauh lebih sederhana serta kemampuan pengiriman data yang lebih tinggi. Oleh karena itu sistem WiMAX sangat mungkin dan mudah diselenggarakan oleh operator baru atau pun service provider skala kecil. Namun demikian kemampuan mobility dari Mobile WiMAX masih berada dibawah kemampuan teknologi selular.

Tinjauan Teknologi

WiMax adalah istilah yang digunakan untuk menggambarkan standar dan implementasi yang mampu beroperasi berdasarkan jaringan nirkabel IEEE 802.16, seperti WiFi yang beroperasi berdasarkan standar Wireless LAN IEEE802.11. Namun, dalam implementasinya WiMax sangat berbeda dengan WiFi.

Pada WiFi, sebagaimana OSI Layer, adalah standar pada lapis kedua, dimana Media Access Control (MAC) menggunakan metode akses kompetisi, yaitu dimana beberapa terminal secara bersamaan memperebutkan akses. Sedangkan MAC pada WiMax menggunakan metode akses yang berbasis algoritma penjadualan (scheduling algorithm). Dengan metode akses kompetisi, maka layanan seperti Voice over IP atau IPTV yang tergantung kepada Kualitas Layanan (Quality of Service) yang stabil menjadi kurang baik. Sedangkan pada WiMax, dimana digunakan algoritma penjadualan, maka bila setelah sebuah terminal mendapat garansi untuk memperoleh sejumlah sumber daya (seperti timeslot), maka jaringan nirkabel akan terus memberikan sumber daya ini selama terminal membutuhkannya.

Standar WiMax pada awalnya dirancang untuk rentang frekuensi 10 s.d. 66 GHz. 802.16a, diperbaharui pada 2004 menjadi 802.16-2004 (dikenal juga dengan 802.16d) menambahkan rentang frekuensi 2 s.d. 11 GHz dalam spesifikasi. 802.16d dikenal juga dengan fixed WiMax, diperbaharui lagi menjadi 802.16e pada tahun 2005 (yang dikenal dengan mobile WiMax) dan menggunakan orthogonal frequency-division multiplexing (OFDM) yang lebih memiliki skalabilitas dibandingkan dengan standar 802.16d yang menggunakan OFDM 256 sub-carriers. Penggunaan OFDM yang baru ini memberikan keuntungan dalam hal cakupang, instalasi, konsumsi daya, penggunaan frekuensi dan efisiensi pita frekuensi. WiMax yang menggunakan standar 802.16e memiliki kemampuan hand over atau hand off, sebagaimana layaknya pada komunikasi selular.

Banyaknya institusi yang tertarik atas standar 802.16d dan .16e karena standar ini menggunakan frekuensi yang lebih rendah sehingga lebih baik terhadap redaman dan dengan demikian memiliki daya penetrasi yang lebih baik di dalam gedung. Pada saat ini, sudah ada jaringan yang secara komersial menggunakan perangkat WiMax bersertifikasi sesuai dengan standar 802.162.

Spesifikasi WiMax membawa perbaikan atas keterbatasan-keterbatasan standar WiFi dengan memberikan lebar pita yang lebih besar dan enkripsi yang lebih bagus. Standar WiMax memberikan koneksi tanpa memerlukan Line of Sight (LOS) dalam situasi tertentu. Propagasi Non LOS memerlukan standar .16d atau revisi 16.e, karena diperlukan frekuensi yang lebih rendah. Juga, perlu digunakan sinyal muli-jalur (multi-path signals), sebagaimana standar 802.16n.

Manfaat dan Keuntungan

Banyak keuntungan yang didapatkan dari terciptanya standardisasi industri ini. Para operator telekomunikasi dapat menghemat investasi perangkat, karena kemampuan WiMAX dapat melayani pelanggannya dengan area yang lebih luas dan tingkat kompatibilitas lebih tinggi. Selain itu, pasarnya juga lebih meluas karena WiMAX dapat mengisi celah broadband yang selama ini tidak terjangkau oleh teknologi Cable dan DSL (Digital Subscriber Line).

WiMAX salah satu teknologi memudahkan mereka mendapatkan koneksi Internet yang berkualitas dan melakukan aktivitas. Sementara media wireless selama ini sudah terkenal sebagai media yang paling ekonomis dalam mendapatkan koneksi Internet. Area coverage-nya sejauh 50 km maksimal dan kemampuannya menghantarkan data dengan transfer rate yang tinggi dalam jarak jauh, sehingga memberikan kontribusi sangat besar bagi keberadaan wireless MAN dan dapat menutup semua celah broadband yang ada saat ini. Dari segi kondisi saat proses komunikasinya, teknologi WiMAX dapat melayani para subscriber, baik yang berada dalam posisi Line Of Sight (posisi perangkat-perangkat yang ingin berkomunikasi masih berada dalam jarak pandang yang lurus dan bebas dari penghalang apa pun di depannya) dengan BTS maupun yang tidak memungkinkan untuk itu (Non-Line Of Sight). Jadi di mana pun para penggunanya berada, selama masih masuk dalam area coverage sebuah BTS (Base Transceiver Stations), mereka mungkin masih dapat menikmati koneksi yang dihantarkan oleh BTS tersebut.

Selain itu, dapat melayani baik para pengguna dengan antena tetap (fixed wireless) misalnya di gedung-gedung perkantoran, rumah tinggal, toko-toko, dan sebagainya, maupun yang sering berpindah-pindah tempat atau perangkat mobile lainnya. Mereka bisa merasakan nikmatnya ber-Internet broadband lewat media ini. Sementara range spektrum frekuensi yang tergolong lebar, maka para pengguna tetap dapat terkoneksi dengan BTS selama mereka berada dalam range frekuensi operasi dari BTS.

Sistem kerja MAC-nya (Media Access Control) yang ada pada Data Link Layer adalah connection oriented, sehingga memungkinkan penggunanya melakukan komunikasi berbentuk video dan suara. Siapa yang tidak mau, ber-Internet murah, mudah, dan nyaman dengan kualitas broadband tanpa harus repot-repot. Anda tinggal memasang PCI card yang kompatibel dengan standar WiMAX, atau tinggal membeli PCMCIA (Personal Computer Memory Card International Association) yang telah mendukung komunikasi dengan WiMAX. Atau mungkin Anda tinggal membeli antena portabel dengan interface ethernet yang bisa dibawa ke mana-mana untuk mendapatkan koneksi Internet dari BTS untuk fixed wireless.

Source from http://id.wikipedia.org/wiki/WiMAX

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WiMAX English

WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile internet access. The technology provides up to 3 Mbit/s broadband speed without the need for cables. The technology is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".


Definitions

The terms "fixed WiMAX", "mobile WiMAX", "802.16d" and "802.16e" are frequently used incorrectly. Correct definitions are the following:

* 802.16-2004 is often called 802.16d, since that was the working party that developed the standard. It is also frequently referred to as "fixed WiMAX" since it has no support for mobility.
* 802.16e-2005 is an amendment to 802.16-2004 and is often referred to in shortened form as 802.16e. It introduced support for mobility, amongst other things and is therefore also known as "mobile WiMAX".

Uses

The bandwidth and range of WiMAX make it suitable for the following potential applications:

* Connecting Wi-Fi hotspots to the Internet.
* Providing a wireless alternative to cable and DSL for "last mile" broadband access.
* Providing data and telecommunications services.
* Providing a source of Internet connectivity as part of a business continuity plan. That is, if a business has a fixed and a wireless Internet connection, especially from unrelated providers, they are unlikely to be affected by the same service outage.
* Providing portable connectivity.

Broadband access

Companies are closely examining WiMAX for last mile connectivity. The resulting competition may bring lower pricing for both home and business customers or bring broadband access to places where it has been economically unavailable.
WiMAX access was used to assist with communications in Aceh, Indonesia, after the tsunami in December 2004. All communication infrastructure in the area, other than amateur radio, was destroyed, making the survivors unable to communicate with people outside the disaster area and vice versa. WiMAX provided broadband access that helped regenerate communication to and from Aceh.

In addition, WiMAX was donated by Intel Corporation to assist the FCC and FEMA in their communications efforts in the areas affected by Hurricane Katrina. In practice, volunteers used mainly self-healing mesh, VoIP, and a satellite uplink combined with Wi-Fi on the local link.

Subscriber units (Client Units)

WiMAX subscriber units are available in both indoor and outdoor versions from several manufacturers. Self-install indoor units are convenient, but radio losses mean that the subscriber must be significantly closer to the WiMAX base station than with professionally-installed external units. As such, indoor-installed units require a much higher infrastructure investment as well as operational cost (site lease, backhaul, maintenance) due to the high number of base stations required to cover a given area. Indoor units are comparable in size to a cable modem or DSL modem. Outdoor units are roughly the size of a laptop PC, and their installation is comparable to the installation of a residential satellite dish.

With the potential of mobile WiMAX, there is an increasing focus on portable units. This includes handsets (similar to cellular smartphones), PC peripherals (PC Cards or USB dongles), and embedded devices in laptops, such as are now available for Wi-Fi. In addition, there is much emphasis from operators on consumer electronics devices (game terminals, MP3 players and the like); it is notable this is more similar to Wi-Fi than to 3G cellular technologies.

Current certified devices can be found at the WiMAX Forum web site. This is not a complete list of devices available as certified modules are embedded into laptops, MIDs (Mobile Internet Devices), and private labeled devices.

Mobile handset applications

Sprint Nextel announced in mid-2006 that it would invest about US$ 5 billion in a WiMAX technology buildout over the next few years. Since that time Sprint has been dealt setbacks that have resulted in steep quarterly losses. On May 7, 2008, Sprint, Imagine, Google, Intel, Comcast, and Time Warner announced a pooling of an average of 120 MHz of spectrum and formation of a new company which will take the name Clearwire. The new company hopes to benefit from combined services offerings and network resources as a springboard past its competitors. The cable companies will provide media services to other partners while gaining access to the wireless network as a Mobile virtual network operator. Google will contribute Android handset device development and applications and will receive revenue share for advertising and other services they provide. Clearwire Sprint and current Clearwire gain a majority stock ownership in the new venture and ability to access between the new Clearwire and Sprint 3G networks. Some details remain unclear including how soon and in what form announced multi-mode WiMAX and 3G EV-DO devices will be available. This raises questions that arise for availability of competitive chips that require licensing of Qualcomm's IPR.

Some analysts have questioned how the deal will work out: Although fixed-mobile convergence has been a recognized factor in the industry, prior attempts to form partnerships among wireless and cable companies have generally failed to lead to significant benefits to the participants. Other analysts point out that as wireless progresses to higher bandwidth, it inevitably competes more directly with cable and DSL, thrusting competitors into bed together. Also, as wireless broadband networks grow denser and usage habits shift, the need for increased back haul and media service will accelerate, therefore the opportunity to leverage cable assets is expected to increase.

Backhaul/access network applications

WiMAX is a possible replacement candidate for cellular phone technologies such as GSM and CDMA, or can be used as a layover to increase capacity. It has also been considered as a wireless backhaul technology for 2G, 3G, and 4G networks in both developed and poor nations.

In North America, Backhaul for urban cellular operations is typically provided via one or more copper wire line T1 connections, whereas remote cellular operations are sometimes "backhauled" via satellite. In most other regions, urban and rural backhaul is usually provided by Microwave links. (The exception to this is where the network is operated by an incumbent with ready access to the copper network, in which case T1 lines may be used). WiMAX is a broadband platform and as such has much more substantial backhaul bandwidth requirements than legacy cellular applications. Therefore traditional copper wire line backhaul solutions are not appropriate. Consequently the use of wireless microwave backhaul is on the rise in North America and existing microwave backhaul links in all regions are being upgraded. Capacities of between 34 Mbit/s and 1 Gbit/s are routinely being deployed with latencies in the order of 1ms. In many cases, operators are aggregating sites using wireless technology and then presenting traffic on to fiber networks where convenient.

Deploying WiMAX in rural areas with limited or no internet backbone will be challenging as additional methods and hardware will be required to procure sufficient bandwidth from the nearest sources — the difficulty being in proportion to the distance between the end-user and the nearest sufficient internet backbone.

Technical information
WiMAX is a term coined to describe standard, interoperable implementations of IEEE 802.16 wireless networks, similar to the way the term Wi-Fi is used for interoperable implementations of the IEEE 802.11 Wireless LAN standard. However, WiMAX is very different from Wi-Fi in the way it works.

MAC layer/data link layer

In Wi-Fi the media access controller (MAC) uses contention access — all subscriber stations that wish to pass data through a wireless access point (AP) are competing for the AP's attention on a random interrupt basis. This can cause subscriber stations distant from the AP to be repeatedly interrupted[citation needed] by closer stations, greatly reducing their throughput.

In contrast, the 802.16 MAC uses a scheduling algorithm for which the subscriber station needs to compete only once (for initial entry into the network). After that it is allocated an access slot by the base station. The time slot can enlarge and contract, but remains assigned to the subscriber station, which means that other subscribers cannot use it. In addition to being stable under overload and over-subscription, the 802.16 scheduling algorithm can also be more bandwidth efficient.[citation needed] The scheduling algorithm also allows the base station to control QoS parameters by balancing the time-slot assignments among the application needs of the subscriber stations.

Physical layer

The original version of the standard on which WiMAX is based (IEEE 802.16) specified a physical layer operating in the 10 to 66 GHz range. 802.16a, updated in 2004 to 802.16-2004, added specifications for the 2 to 11 GHz range. 802.16-2004 was updated by 802.16e-2005 in 2005 and uses scalable orthogonal frequency-division multiple access (SOFDMA) as opposed to the Orthogonal frequency-division multiplexing (OFDM) version with 256 sub-carriers (of which 200 are used) in 802.16d. More advanced versions, including 802.16e, also bring Multiple Antenna Support through MIMO. See: WiMAX MIMO. This brings potential benefits 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 products to sell their equipment as WiMAX certified, thus ensuring a level of interoperability with other certified products, as long as they fit the same profile.

Most commercial interest is in the 802.16d and 802.16e standards, since the lower frequencies used in these variants suffer less from inherent signal attenuation and therefore give improved range and in-building penetration. Already today, a number of networks throughout the world are in commercial operation using certified WiMAX equipment compliant with the 802.16d standard.

Complexities of deployment

Being a standard thought to satisfy the needs of next generation data networks, nomadic and mobile (4G), it is distinguished by a dynamic burst algorithm that adapts the current physical digital modulation according to field variables that are dependent on the radio propagation conditions; the current physical mod is chosen to be spectrally more efficient (more bits per OFDM/SOFDMA symbol), that is, when the bursts have a high signal strength and a high carrier to noise plus interference ratio (CINR) and they can be easily decoded by the digital signal processing (DSP) Algorithms. In contrast, when some of those conditions are bad, then the system chooses a more robust physical mode (burst profile) which means less bits per OFDM/SOFDMA symbol, but with the advantage that power per bit is higher and therefore accurate decoding is easier. Because of this, higher order burst profiles can only be used (dynamically chosen by an algorithm) when the attenuation is not high which means only for subscriber stations located near the base station antenna and therefore the maximum distance can only be achieved by means of selecting the more robust burst profile with the MAC frame allocation inconvenience that it implies as more symbols (more portion of the MAC frame) have to be allocated for transmitting a given amount of data than if the subscriber station was close to the base station.

In the MAC Frame the subscriber stations are allocated and their individual burst profiles defined as well as the specific time allocation, but even if that is done automatically practical deployment should avoid high interference and high multipath environments as opposed to what the average radio network planning team (and executive staff from the adopting operator) could think, the reason for it lies in excessive interference and competition during the Initial Ranging (IR) process due to the usage of high transmitting power in base station (BS) and subscriber station (SS) alike, which can result in unwanted delays and ranging attempts that effectively detracts from a good user experience and can even result in wasted allocated symbols due to continuous connections/re-connections.

The system therefore is very complex to deploy as it is necessary to keep in mind not only the signal strength and CINR (as in systems like GSM) but it is also necessary to think how the spectrum is going to be dynamically assigned (resulting in dynamically changing total available bandwidth)) to the served subscriber stations (other dynamic burst systems have 2 or 3 burst profiles, WiMAX developments have showed up to 7 in use at the same time), the DSP algorithms (Decodification) are tougher than in any other wireless systems, yet they cannot reconstruct any burst in any environment; It is usually very effective though, but coupled with OFDM/SOFDMA, it can result in a double edged sword which means by having a tougher set of DSP algorithms, usually deployed on specific purpose chips, the signal could (harmfully) reach farther distances than expected due to tunnel effects (constructive interference with neighbor frequencies) resulting in highly interfered clutters and with highly reflected signals, with very high signal strength though which can fool the non experienced planning staff (usually coming from 3gpp networks).

As a result the system has to be initially deployed in conjunction with product development staff (who are usually involved in the technology development in some way) from the given vendor as opposed to service technical staff (radio planning) from the operator or vendor as is usual practice, thus raising the cost of deployment. As with all new technologies, configuration and maintenance will become easier to use as more deployments occur.

Integration with an IP based Network
The WiMAX Forum has proposed an architecture that defines how a WiMAX network can be connected with an IP based core network, which is typically chosen by operators that serve as Internet Service Providers (ISP); Nevertheless the WiMAX BS provide seamless integration capabilities with other types of architectures as with packet switched Mobile Networks.

The WiMAX forum proposal defines a number of components, plus some of the interconnections (or reference points) between these, labeled R1 to R5 and R8:

* SS/MS: the Subscriber Station/Mobile Station
* ASN: the Access Service Network
* BS: Base station, part of the ASN
* ASN-GW: the ASN Gateway, part of the ASN
* CSN: the Connectivity Service Network
* HA: Home Agent, part of the CSN
* AAA: Authentication, Authorization and Accounting Server, part of the CSN
* NAP: a Network Access Provider
* NSP: a Network Service Provider

It is important to note that the functional architecture can be designed into various hardware configurations rather than fixed configurations. For example, the architecture is flexible enough to allow remote/mobile stations of varying scale and functionality and Base Stations of varying size - e.g. femto, pico, and mini BS as well as macros.

Comparison with Wi-Fi

Comparisons and confusion between WiMAX and Wi-Fi are frequent because both are related to wireless connectivity and Internet access.

* WiMAX uses spectrum to deliver a point-to-point connection to the Internet. Different 802.16 standards provide different types of access, from portable (similar to a cordless phone) to fixed (an alternative to wired access, where the end user's wireless termination point is fixed in location.)
* Wi-Fi uses unlicensed spectrum to provide access to a network. Wi-Fi is more popular in end user devices.
* WiMAX and Wi-Fi have quite different Quality of Service (QoS) mechanisms. WiMAX uses a mechanism based on connections between the Base Station and the user device. Each connection is based on specific scheduling algorithms. Wi-Fi has a QoS mechanism similar to fixed Ethernet, where packets can receive different priorities based on their tags. For example VoIP traffic may be given priority over web browsing.
* Wi-Fi runs on the MAC's CSMA/CA protocol, which is connectionless and contention based, whereas WiMAX runs a connection-oriented MAC.

Both 802.11 and 802.16 define Peer-to-Peer (P2P) and ad hoc networks, where an end user communicates to users or servers on another Local Area Network (LAN) using its access point or base station.

Spectrum allocation issues

The 802.16 specification applies across a wide swath of the RF spectrum, and WiMAX could function on any frequency below 66 GHz, (higher frequencies would decrease the range of a Base Station to a few hundred meters in an urban environment).

There is no uniform global licensed spectrum for WiMAX, although the WiMAX Forum has published three licensed spectrum profiles: 2.3 GHz, 2.5 GHz and 3.5 GHz, in an effort to decrease cost: economies of scale dictate that the more WiMAX embedded devices (such as mobile phones and WiMAX-embedded laptops) are produced, the lower the unit cost. (The two highest cost components of producing a mobile phone are the silicon and the extra radio needed for each band.) Similar economy of scale benefits apply to the production of Base Stations.

In the unlicensed band, 5.x GHz is the approved profile. Telecommunication companies are unlikely to use this spectrum widely other than for backhaul, since they do not own and control the spectrum.

In the USA, the biggest segment available is around 2.5 GHz, and is already assigned, primarily to Sprint Nextel and Clearwire. Elsewhere in the world, the most-likely bands used will be the Forum approved ones, with 2.3 GHz probably being most important in Asia. Some countries in Asia like India and Indonesia will use a mix of 2.5 GHz, 3.3 GHz and other frequencies. Pakistan's Wateen Telecom uses 3.5 GHz.

Analog TV bands (700 MHz) may become available for WiMAX usage, but await the complete roll out of digital TV, and there will be other uses suggested for that spectrum. In the USA the FCC auction for this spectrum began in January 2008 and, as a result, the biggest share of the spectrum went to Verizon Wireless and the next biggest to AT&T. Both of these companies have stated their intention of supporting LTE, a technology which competes directly with WiMAX. EU commissioner Viviane Reding has suggested re-allocation of 500–800 MHz spectrum for wireless communication, including WiMAX.

WiMAX profiles define channel size, TDD/FDD and other necessary attributes in order to have inter-operating products. The current fixed profiles are defined for both TDD and FDD profiles. At this point, all of the mobile profiles are TDD only. The fixed profiles have channel sizes of 3.5 MHz, 5 MHz, 7 MHz and 10 MHz. The mobile profiles are 5 MHz, 8.75 MHz and 10 MHz. (Note: the 802.16 standard allows a far wider variety of channels, but only the above subsets are supported as WiMAX profiles.)

Since October 2007, the Radio communication Sector of the International Telecommunication Union (ITU-R) has decided to include WiMAX technology in the IMT-2000 set of standards. This enables spectrum owners (specifically in the 2.5-2.69 GHz band at this stage) to use Mobile WiMAX equipment in any country that recognizes the IMT-2000.

Spectral efficiency

One of the significant advantages of advanced wireless systems such as WiMAX is spectral efficiency. For example, 802.16-2004 (fixed) has a spectral efficiency of 3.7 (bit/s)/Hertz, and other 3.5–4G wireless systems offer spectral efficiencies that are similar to within a few tenths of a percent. The notable advantage of WiMAX comes from combining SOFDMA with smart antenna technologies. This multiplies the effective spectral efficiency through multiple reuse and smart network deployment topologies. The direct use of frequency domain organization simplifies designs using MIMO-AAS compared to CDMA/WCDMA methods, resulting in more effective systems.

Limitations

A commonly-held misconception is that WiMAX will deliver 70 Mbit/s over 50 kilometers (~31 miles). In reality, WiMAX can either operate at higher bitrates or over longer distances but not both: operating at the maximum range of 50 km increases bit error rate and thus results in a much lower bitrate. Conversely, reducing the range (to <1m) allows a device to operate at higher bitrates. There are no known examples of WiMAX services being delivered at bit rates over around 3 Mbit/s.
Typically, fixed WiMAX networks have a higher-gain directional antenna installed near the client (customer) which results in greatly increased range and throughput. Mobile WiMAX networks are usually made of indoor "Customer-premises equipment" (CPE) such as desktop modems, laptops with integrated Mobile WiMAX or other Mobile WiMAX devices. Mobile WiMAX devices typically have omnidirectional antennae which are of lower-gain compared to directional antennas but are more portable. In current deployments, the throughput may reach 2 Mbit/s symmetric at 10 km with fixed WiMAX and a high gain antenna. It is also important to consider that a throughput of 2 Mbit/s can mean 2 Mbit/s, symmetric simultaneously, 1 Mbit/s symmetric or some asymmetric mix (e.g. 0.5 Mbit/s downlink and 1.5 Mbit/s uplink or 1.5 Mbit/s downlink and 0.5 Mbit/s uplink), each of which required slightly different network equipment and configurations. Higher-gain directional antennas can be used with a WiMAX network with range and throughput benefits but the obvious loss of practical mobility.

Like most wireless systems, available bandwidth is shared between users in a given radio sector, so performance could deteriorate in the case of many active users in a single sector. In practice, most users will have a range of 2-3 Mbit/s services and additional radio cards will be added to the base station to increase the number of users that may be served as required.

Because of these limitations, the general consensus is that WiMAX requires various granular and distributed network architectures to be incorporated within the IEEE 802.16 task groups. This includes wireless mesh, grids, network remote station repeaters which can extend networks and connect to backhaul.

Silicon implementations

A critical requirement for the success of a new technology is the availability of low-cost chipsets and silicon implementations.

Intel Corporation is a leader in promoting WiMAX, and has developed its own chipset. However, it is notable that most of the major semiconductor companies have not and most of the products come from specialist smaller or start-up suppliers. For the client-side these include Sequans, whose chips are in more than half of the WiMAX Forum Certified(tm) MIMO-based Mobile WiMAX client devices, GCT Semiconductor, ApaceWave, Altair Semiconductor, Beceem, Comsys, Runcom, Motorola with TI, NextWave Wireless, Wavesat, Coresonic and SySDSoft. Both Sequans and Wavesat manufacture products for both clients and network while Texas Instruments, DesignArt, and picoChip are focused on WiMAX chip sets for base stations. Kaben Wireless Silicon is a provider of RF front-end and semiconductor IP for WiMAX applications.

Standards

The current WiMAX incarnation, Mobile WiMAX, is based upon IEEE Std 802.16e-2005, approved in December 2005. It is a supplement to the IEEE Std 802.16-2004, and so the actual standard is 802.16-2004 as amended by 802.16e-2005 — the specifications need to be read together to understand them.

IEEE Std 802.16-2004 addresses only fixed systems. It replaced IEEE Standards 802.16-2001, 802.16c-2002, and 802.16a-2003.

IEEE 802.16e-2005 improves upon IEEE 802.16-2004 by:

* Adding support for mobility (soft and hard handover between base stations). This is seen as one of the most important aspects of 802.16e-2005, and is the very basis of 'Mobile WiMAX' (though this has yet to be demonstrated in any installed systems).
* Scaling of the Fast Fourier transform (FFT) to the channel bandwidth in order to keep the carrier spacing constant across different channel bandwidths (typically 1.25 MHz, 5 MHz, 10 MHz or 20 MHz). Constant carrier spacing results in a higher spectrum efficiency in wide channels, and a cost reduction in narrow channels. Also known as Scalable OFDMA (SOFDMA). Other bands not multiples of 1.25 MHz are defined in the standard, but because the allowed FFT subcarrier numbers are only 128, 512, 1024 and 2048, other frequency bands will not have exactly the same carrier spacing, which might not be optimal for implementations.
* Advanced antenna diversity schemes, and hybrid automatic repeat-request (HARQ)
* Adaptive Antenna Systems (AAS) and MIMO technology
* Denser sub-channelization, thereby improving indoor penetration
* Introducing Turbo Coding and Low-Density Parity Check (LDPC)
* Introducing downlink sub-channelization, allowing administrators to trade coverage for capacity or vice versa
* Fast Fourier transform algorithm
* Adding an extra QoS class for VoIP applications.

802.16d vendors point out that fixed WiMAX offers the benefit of available commercial products and implementations optimized for fixed access. It is a popular standard among alternative service providers and operators in developing areas due to its low cost of deployment and advanced performance in a fixed environment. Fixed WiMAX is also seen as a potential standard for backhaul of wireless base stations such as cellular, or Wi-Fi.

SOFDMA (used in 802.16e-2005) and OFDM256 (802.16d) are not compatible thus most equipment will have to be replaced if an operator wants or needs to move to the later standard. However, some manufacturers are planning to provide a migration path for older equipment to SOFDMA compatibility which would ease the transition for those networks which have already made the OFDM256 investment. Intel provides a dual-mode 802.16-2004 802.16-2005 chipset for subscriber units.

Source from : http://en.wikipedia.org/wiki/WiMAX

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