WiMAX WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides for the wireless transmission of data in a variety of ways, ranging from point-to-point links to full mobile cellular-type access. The technology is based on the IEEE 802.16 standard (also called WirelessMAN). 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" (and also to High Speed Packet Access). Currently, Pakistan has the largest fully functional Wimax network in the world. Wateen Telecom installed the network (with an initial rollout in seventeen cities) throughout Pakistan using Motorola hardware. WiMAX 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
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WiMAX
WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides for the wireless transmission of data in a variety of ways, ranging from point-to-point links to full mobile cellular-type access. The technology is based on the IEEE 802.16 standard (also called WirelessMAN).
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" (and also to High Speed Packet Access).
Currently, Pakistan has the largest fully functional Wimax network in the world. Wateen Telecom installed the network (with an initial rollout in seventeen cities) throughout Pakistan using Motorola hardware.
WiMAX 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 with other parts of 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
Many 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 Ham 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 used by Intel to assist the FCC and FEMA in their communications efforts in the areas affected by Hurricane Katrina.
Subscriber 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 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) and PC peripherals (PC Cards or USB dongles). 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 3G cellular technologies.
Current certified devices can 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
Some cellular companies are evaluating WiMAX as a means of increasing bandwidth for a variety of data-intensive 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 in defections of (Nextel) iDEN and 3G subscribers that have resulted in steep quarterly losses and led to a management shake up with Dan Hesse as its new CEO.
On May 7, 2008, Sprint, Clearwire, Google, Intel, Comcast, and Time Warner announced a pooling of 2.5 GHz 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 an MVNO. 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 more dense 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 developing nations.
"Backhaul" for remote cellular operations is typically provided via satellite, and in urban areas via one or several T1 connections. WiMAX is mobile broadband and as such has much more substantial backhaul need. Therefore traditional backhaul solutions are not appropriate. Consequently the role of very high capacity wireless microwave point-to-point backhaul (200 or more Mbit/s with typically 1 ms or less delay) is on the rise. Also fiber backhaul is more appropriate.
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.
Given the limited wired infrastructure in some developing countries, the costs to install a WiMAX station in conjunction with an existing cellular tower or even as a solitary hub are likely to be small in comparison to developing a wired solution. Areas of low population density and flat terrain are particularly suited to WiMAX and its range. For countries that have skipped wired infrastructure as a result of prohibitive costs and unsympathetic geography, WiMAX can enhance wireless infrastructure in an inexpensive, decentralized, deployment-friendly and effective manner.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.
IEEE 802.16
The IEEE 802.16 Working Group on Broadband Wireless Access Standards, which was established by IEEE Standards Board in 1999, aims to prepare formal specifications for the global deployment of broadband Wireless Metropolitan Area Networks. The Workgroup is a unit of the IEEE 802 LAN/MAN Standards Committee. A related future technology Mobile Broadband Wireless Access (MBWA) is under development in IEEE 802.20.
Although the 802.16 family of standards is officially called WirelessMAN, it has been dubbed “WiMAX” (from "Worldwide Interoperability for Microwave Access") by an industry group called the WiMAX Forum. The mission of the Forum is to promote and certify compatibility and interoperability of broadband wireless products.802.16 Standards
The first 802.16 standard was approved in December 2001. It delivered a standard for point to multipoint Broadband Wireless transmission in the 10-66 GHz band, with only a line-of-sight (LOS) capability. It uses a single carrier (SC) physical (PHY) standard.
802.16a was an amendment to 802.16 and delivered a point to multipoint capability in the 2-11 GHz band. For this to be of use, it also required a non-line-of-sight (NLOS) capability, and the PHY standard was therefore extended to include Orthogonal Frequency Division Multiplex (OFDM) and Orthogonal Frequency Division Multiple Access (OFDMA). 802.16a was ratified in January 2003 and was intended to provide "last mile" fixed broadband access.
802.16c, a further amendment to 802.16, delivered a system profile for the 10-66 GHz 802.16 standard.
In September 2003, a revision project called 802.16d commenced aiming to align the standard with aspects of the European Telecommunications Standards Institute (ETSI) HIPERMAN standard as well as lay down conformance and test specifications. This project concluded in 2004 with the release of 802.16-2004 which superseded the earlier 802.16 documents, including the a/b/c amendments.
An amendment to 802.16-2004, IEEE 802.16e-2005 (formerly known as IEEE 802.16e), addressing mobility, was concluded in 2005. This implemented a number of enhancements to 802.16-2004, including better support for Quality of Service and the use of Scalable OFDMA, and is sometimes called “Mobile WiMAX”, after the WIMAX forum for interoperability.
Amendments in progress
Active amendments:802.16e-2005 — Mobile 802.16802.16f-2005 — Management Information Base802.16g-2007 — Management Plane Procedures and Services802.16k-2007 — Bridging of 802.16 (an amendment to 802.1D)
Amendments under development:802.16h — Improved Coexistence Mechanisms for License-Exempt Operation802.16i — Mobile Management Information Base802.16j — Multihop Relay Specification802.16Rev2 — Consolidate 802.16-2004, 802.16e, 802.16f, 802.16g and possibly 802.16i into a new document.
Amendments at pre-draft stage:802.16m — Advanced Air Interface. Data rates of 100 Mbit/s for mobile applications and 1 Gbit/s for fixed applications, cellular, macro and micro cell coverage, with currently no restrictions on the RF bandwidth (which is expected to be 20 MHz or higher). The proposed work plan would allow completion of the standard by December 2009 for approval by March 2010.802.16e-2005 Technology
The 802.16 standard essentially standardizes 2 aspects of the air interface - the physical layer (PHY) and the Media Access Control layer (MAC). This section provides an overview of the technology employed in these 2 layers in the current version of the 802.16 specification (which is strictly 802.16-2004 as amended by 802.16e-2005, but which will be referred to as 802.16e for brevity).
PHY
802.16e uses Scalable OFDMA to carry data, supporting channel bandwidths of between 1.25 MHz and 20 MHz, with up to 2048 sub-carriers. It supports adaptive modulation and coding, so that in conditions of good signal, a highly efficient 64 QAM coding scheme is used, whereas where the signal is poorer, a more robust BPSK coding mechanism is used. In intermediate conditions, 16 QAM and QPSK can also be employed. Other PHY features include support for Multiple-in Multiple-out (MIMO) antennas in order to provide good NLOS (Non-line-of-sight) characteristics (or higher bandwidth) and Hybrid automatic repeat request (HARQ) for good error correction performance.
MAC
The 802.16 MAC describes a number of Convergence Sublayers which describe how wireline technologies such as Ethernet, ATM and IP are encapsulated on the air interface, and how data is classified, etc. It also describes how secure communications are delivered, by using secure key exchange during authentication, and encryption using AES or DES (as the encryption mechanism) during data transfer. Further features of the MAC layer include power saving mechanisms (using Sleep Mode and Idle Mode) and handover mechanisms.
A key feature of 802.16 is that it is a connection oriented technology. The subscriber station (SS) cannot transmit data until it has been allocated a channel by the Base Station (BS). This allows 802.16e to provide strong support for Quality of Service (QoS).
QoS
QoS in 802.16e is supported by allocating each connection between the SS and the BS (called a service flow in 802.16 terminology) to a specific QoS class. In 802.16e, there are 5 QoS classes:
802.16e-2005 QoS classes
ServiceAbbrev
DefinitionTypical Applications
Unsolicited Grant ServiceUGSReal-time data streams comprising fixed-size data packets issued at periodic intervalsT1/E1 transport
Extended Real-time Polling ServiceertPSReal-time service flows that generate variable-sized data packets on a periodic basisVoIP
Real-time Polling ServicertPSReal-time data streams comprising variable-sized data packets that are issued at periodic intervalsMPEG Video
Non-real-time Polling ServicenrtPSDelay-tolerant data streams comprising variable-sized data packets for which minimum data rate is requiredFTP with guaranteed minimum throughput
Best EffortBEData streams for which no minimum service level is required and therefore may be handled on a space-available basisHTTP
The BS and the SS use a service flow with an appropriate QoS class (plus other parameters, such as bandwidth and delay) to ensure that application data receives QoS treatment appropriate to the application.
WiMAX Certification
Because the IEEE only sets specifications but does not test equipment for compliance with them, the WiMAX Forum runs a certification program wherein members pay for certification. WiMAX certification by this group is intended to guarantee compliance with the standard and interoperability with equipment from other manufacturers. The mission of the Forum is to promote and certify compatibility and interoperability of broadband wireless products.
External linksIEEE Std 802.16-2004IEEE Std 802.16e-2005ITU Radiocommunication Assembly approves new developments for its 3G standardsIEEE website for 802.16Get IEEE 802 (IEEE 802.16)The WiMAX ForumWiMAX: Opportunity or Hype? A paper presented at the ITERA 2006 academic conference discussing the standardization processEuropean Telecommunications Standards InstituteThe implications of WiMAX for competition and regulation A paper of the OECD, Organisation for Economic Co-operation and DevelopmentWiMAX References^ IEEE 802.16 Task Group m (TGm)
IEEE 802.11
IEEE 802.11 is a set of standards for wireless local area network (WLAN) computer communication, developed by the IEEE LAN/MAN Standards Committee (IEEE 802) in the 5 GHz and 2.4 GHz public spectrum bands.
Although the terms 802.11 and Wi-Fi are often used interchangeably, the Wi-Fi Alliance uses the term "Wi-Fi" to define a slightly different set of overlapping standards. In some cases, market demand has led the Wi-Fi Alliance to begin certifying products before amendments to the 802.11 standard are completed.General description
The 802.11 family includes over-the-air modulation techniques that use the same basic protocol. The most popular are those defined by the 802.11b and 802.11g protocols, and are amendments to the original standard. 802.11-1997 was the first wireless networking standard, but 802.11b was the first widely accepted one, followed by 802.11g and 802.11n.
Security was originally purposefully weak due to export requirements of some governments, and was later enhanced via the 802.11i amendment after governmental and legislative changes. 802.11n is a new multi-streaming modulation technique that is still under draft development, but products based on its proprietary pre-draft versions are being sold. Other standards in the family (c–f, h, j) are service amendments and extensions or corrections to previous specifications.
802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States under Part 15 of the US Federal Communications Commission Rules and Regulations. Because of this choice of frequency band, 802.11b and g equipment may occasionally suffer interference from microwave ovens and cordless telephones. Bluetooth devices, while
operating in the same band, in theory do not interfere with 802.11b/g because they use a frequency hopping spread spectrum signaling method (FHSS) while 802.11b/g uses a direct sequence spread spectrum signaling method (DSSS). 802.11a uses the 5 GHz U-NII band, which offers 8 non-overlapping channels rather than the 3 offered in the 2.4GHz ISM frequency band.
The segment of the radio frequency spectrum used varies between countries. In the US, 802.11a and 802.11g devices may be operated without a license, as explained in Part 15 of the FCC Rules and Regulations. Frequencies used by channels one through six (802.11b) fall within the 2.4 GHz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption.SummaryWireless local area network standards
802.11ProtocolRelease]Freq.(GHz)Typ throughput(Mbit/s)Max net bitrate(Mbit/s)Mod.rin.(m)rout.(m)
–19972.400.9002
~20~100
a1999523054OFDM
~35~120
b19992.404.3011DSSS~38~140
g20032.419054OFDM~38~140
n20082.4, 574248OFDM~70~250
y20083.7230
~50~5000
802.11-1997 (802.11 legacy)
The original version of the standard IEEE 802.11, released in 1997 and clarified in 1999, specified two raw net bit rates of 1 or 2 megabits per second (Mbit/s), plus forward error correction code, to be transmitted in Industrial Scientific Medical frequency band at 2.4 GHz.
Legacy 802.11 was rapidly supplemented (and popularized) by 802.11b.802.11aRelease dateOp. FrequencyNet bit rate (Typ)Net bit rate (Max)Gross bit rate (Max)Range (Indoor)
October 19995 GHz23 Mbit/s54 Mbit/s72 Mbit/s~35 m
The 802.11a standard uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface (physical layer). It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20 Mbit/s.
Since the 2.4 GHz band is heavily used to the point of being crowded, using the relatively un-used 5 GHz band gives 802.11a a significant advantage. However, this high carrier frequency also brings a disadvantage: The effective overall range of 802.11a is less than that of 802.11b/g; 802.11a signals cannot penetrate as far as those for 802.11b because they are absorbed more readily by walls and other solid objects in their path.
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same media access method defined in the original standard. 802.11b products appeared on the market in
early 2000, since 802.11b is a direct extension of the modulation technique defined in the original standard. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.
802.11gRelease dateOp. FrequencyNet bit rate (Typ)Net bit rate (Max)Gross bit rate (Max)Range (Indoor)
June 20032.4 GHz19 Mbit/s54 Mbit/s72 Mbit/s~38 m
In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band (like 802.11b), but uses the same OFDM based transmission scheme as 802.11a. It operates at a maximum physical layer bit rate of 54 Mbit/s exclusive of forward error correction codes, or about 19 Mbit/s average throughput. 802.11g hardware is fully backwards compatible with 802.11b hardware.
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well before ratification, due to the desire for higher speeds, and reductions in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile adapter card or access point. Details of making b and g work well together occupied much of the lingering technical process; in an 802.11g network, however, activity by a 802.11b participant will reduce the speed of the overall 802.11g network.
Like 802.11b, 802.11g devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones.802.11-2007
In 2003, task group TGma was authorized to "roll up" many of the amendments to the 1999 version of the 802.11 standard. REVma or 802.11ma, as it was called, created a single document that merged 8 amendments (802.11a,b,d,e,g,h,i,j) with the base standard. Upon approval on March 08, 2007, 802.11REVma was renamed to the current standard IEEE 802.11-2007.This is the single most modern 802.11 document available that contains cumulative changes from multiple sub-letter task groups.802.11nRelease dateOp. FrequencyData rate (Typ)Data rate (Max)Range (Indoor)
Pending5 GHz and/or 2.4 GHz74 Mbit/s300 Mbit/s (2 streams)~70 m
802.11n is a proposed amendment which improves upon the previous 802.11 standards by adding multiple-input multiple-output (MIMO) and many other newer features. Though there are already many products on the market based on Draft 2.0 of this proposal, the TGn workgroup is not expected to finalize the amendment until December 2009.Channels and international compatibility
802.11 divides each of the above-described bands into channels, analogously to how radio and TV broadcast bands are carved up but with greater channel width and overlap. For example the 2.4000-2.4835 GHz band is divided into 13 channels each of width 22 MHz but spaced only 5 MHz apart, with channel 1 centred on 2412 MHz and 13 on 2472, to which Japan adds a 14th channel 12 MHz above channel 13.
Availability of channels is regulated by country, constrained in part by how each country allocates radio spectrum to various services. At one extreme Japan permits the use of all 14 channels (with the exclusion of 802.11g/n from channel 14), while at the other Spain allowed only channels 10 and 11 (later all of the 14 channels have been allowed ), to which France adds 12 and 13. Most other European countries are almost as liberal as Japan, disallowing only channel 14, while North America and some Central and South American countries further disallow 12 and 13. For more details on this topic, see List of WLAN channels.
Besides specifying the centre frequency of each channel, 802.11 also specifies (in Clause 17) a spectral mask defining the permitted distribution of power across each channel. The mask requires that the signal be attenuated by at least 30 dB from its peak energy at ± 11
MHz from the centre frequency, the sense in which channels are effectively 22 MHz wide. One consequence is that stations can only use every fourth or fifth channel without overlap, typically 1, 6 and 11 in the Americas, 1, 5, 9 and 13 in Europe, etc. Another is that channels 1-13 effectively require the band 2401-2483 MHz, the actual allocations being for example 2400-2483.5 in the UK, 2402-2483.5 in the US, etc.
Since the spectral mask only defines power output restrictions up to ± 22 MHz from the center frequency to be attenuated by 50 dB, it is often assumed that the energy of the channel extends no further than these limits. It is more correct to say that, given the separation between channels 1, 6, and 11, the signal on any channel should be sufficiently attenuated to minimally interfere with a transmitter on any other channel. Due to the near-far problem a transmitter can impact a receiver on a "non-overlapping" channel, but only if it is close to the victim receiver (within a meter) or operating above allowed power levels.
Although the statement that channels 1, 6, and 11 are "non-overlapping" is limited to spacing or product density, the 1–6–11 guideline has merit. If transmitters are closer together than channels 1, 6, and 11 (for example, 1, 4, 7, and 10), overlap between the channels may cause unacceptable degradation of signal quality and throughput.Standard and amendments
Within the IEEE 802.11 Working Group, the following IEEE Standards Association Standard and Amendments exist:
* IEEE 802.11 - THE WLAN STANDARD was original 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and IR standard (1997), all the others listed below are Amendments to this standard, except for Recommended Practices 802.11F and 802.11T.
* IEEE 802.11a - 54 Mbit/s, 5 GHz standard (1999, shipping products in 2001)
* IEEE 802.11b - Enhancements to 802.11 to support 5.5 and 11 Mbit/s (1999)
* IEEE 802.11c - Bridge operation procedures; included in the IEEE 802.1D standard (2001)
* IEEE 802.11d - International (country-to-country) roaming extensions (2001)
* IEEE 802.11e - Enhancements: QoS, including packet bursting (2005)
* IEEE 802.11F - Inter-Access Point Protocol (2003) Withdrawn February 2006
* IEEE 802.11g - 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003)
* IEEE 802.11h - Spectrum Managed 802.11a (5 GHz) for European compatibility (2004)
* IEEE 802.11i - Enhanced security (2004)
* IEEE 802.11j - Extensions for Japan (2004)
* IEEE 802.11-2007 - A new release of the standard that includes amendments a, b, d, e, g, h, i & j. (July 2007)
* IEEE 802.11k - Radio resource measurement enhancements (2008)
* IEEE 802.11l - (reserved and will not be used)
* IEEE 802.11m - Maintenance of the standard. Recent edits became 802.11-2007. (ongoing)
* IEEE 802.11n - Higher throughput improvements using MIMO (multiple input, multiple output antennas) (July 2009)
* IEEE 802.11o - (reserved and will not be used)
* IEEE 802.11p - WAVE - Wireless Access for the Vehicular Environment (such as ambulances and passenger cars) (working - 2009?)
* IEEE 802.11q - (reserved and will not be used, can be confused with 802.1Q VLAN trunking)
* IEEE 802.11r - Fast roaming Working "Task Group r" - (2008)
* IEEE 802.11s - ESS Extended Service Set Mesh Networking (working - 2008?)
* IEEE 802.11T - Wireless Performance Prediction (WPP) - test methods and metrics Recommendation (working - 2008?)
* IEEE 802.11u - Interworking with non-802 networks (for example, cellular) (proposal evaluation - ?)
* IEEE 802.11x - (reserved and will not be used, can be confused with 802.1x Network Access Control)
* IEEE 802.11y - 3650-3700 MHz Operation in the U.S. (2008)
* IEEE 802.11z - Extensions to Direct Link Setup (DLS) (Aug. 2007 - Dec. 2011)
There is no standard or task group named "802.11x". Rather, this term is used informally to denote any current or future 802.11 amendment, in cases where further precision is not necessary. (The IEEE 802.1x standard for port-based network access control is often mistakenly called "802.11x" when used in the context of wireless networks.)
802.11F and 802.11T are recommended practices rather than standards, and are capitalized as such.
Standard or amendment?
Both the terms "standard" and "amendment" are used when referring to the different variants of IEEE 802.11.
As far as the IEEE Standards Association is concerned, there is only one current standard; it is denoted by IEEE 802.11 followed by the date that it was published. IEEE 802.11-2007 is the only version currently in publication. The standard is updated by means of amendments. Amendments are created by task groups (TG). Both the task group and their finished document are denoted by 802.11 followed by a non-capitalized letter. For example IEEE 802.11a and IEEE 802.11b. Updating 802.11 is the responsibility of task group m. In order to create a new version, TGm combines the previous version of the standard and all published amendments. TGm also provides clarification and interpretation to industry on published documents. New versions of the IEEE 802.11 were published in 1999 and 2007.
The working title of 802.11-2007 was 802.11-REVma. This denotes a third type of document, a "revision". The complexity of combining 802.11-1999 with 8 amendments made it necessary to revise already agreed upon text. As a result, additional guidelines associated with a revision had to be followed.Nomenclature
Various terms in 802.11 are used to specify aspects of wireless local-area networking operation, and may be unfamiliar to some readers.
For example, Time Unit (usually abbreviated TU) is used to indicate a unit of time equal to 1024 microseconds. Numerous time constants are defined in terms of TU (rather than the nearly-equal millisecond).
Also the term "Portal" is used to describe an entity that is similar to an IEEE 802.1D bridge. A Portal provides access to the WLAN by non-802.11 LAN STAs.Community networks
With the proliferation of cable modems and DSL, there is an ever-increasing market of people who wish to establish small networks in their homes to share their high speed Internet connection.
Many hotspot or free networks frequently allow anyone within range, including passersby outside, to connect to the Internet. There are also efforts by volunteer groups to establish wireless community networks to provide free wireless connectivity to the public.Security
In 2001, a group from the University of California, Berkeley presented a paper describing weaknesses in the 802.11 Wired Equivalent Privacy (WEP) security mechanism defined in the original standard; they were followed by Fluhrer, Mantin, and Shamir's paper entitled "Weaknesses in the Key Scheduling Algorithm of RC4". Not long after, Adam Stubblefield and AT&T publicly announced the first verification of the attack. In the attack they were able to intercept transmissions and gain unauthorized access to wireless networks.
The IEEE set up a dedicated task group to create a replacement security solution, 802.11i (previously this work was handled as part of a broader 802.11e effort to enhance the MAC layer). The Wi-Fi Alliance announced an interim specification called Wi-Fi Protected Access (WPA) based on a subset of the then current IEEE 802.11i draft. These started to appear in products in mid-2003. IEEE 802.11i (also known as WPA2) itself was ratified in June 2004, and uses government strength encryption in the Advanced Encryption Standard AES, instead of RC4, which was used in WEP. The modern recommended encryption for the home/consumer space is WPA2 (AES PreShared Key) and for the Enterprise space is WPA2 along with a radius server the strongest is EAP-TLS.
In January 2005, IEEE set up yet another task group, TGw, to protect management and broadcast frames, which previously were sent unsecured. See IEEE 802.11wNon-standard 802.11 extensions and equipment
Many companies implement wireless networking equipment with non-IEEE standard 802.11 extensions either by implementing proprietary or draft features. These changes may lead to incompatibilities between these extensions.
For more details on this topic, see 802.11 non-standard equipment.External linksIEEE 802.11 working groupDownload the 802.11 standards from IEEEOfficial IEEE 802.11 Work Plan predictions"Using the Fluhrer, Mantin, and Shamir Attack to Break WEP" (2001), paper by Stubblefield (PDF)802.11n: Next-Generation Wireless LAN Technology, paper by BroadcomReferences^ Looking for 802.11g Wireless Internet Access information, definitions and technology descriptions?^ "ARRLWeb: Part 97 - Amateur Radio Service". American Radio Relay League.
^ a b c "Official IEEE 802.11 working group project timelines" (2007-11-15). Retrieved on 2007-11-18.^ "802.11n Delivers Better Range". Wi-Fi Planet (2007-05-31).^ IEEE. ISBN 0-7381-5656-9.^ "Cuadro nacional de Atribución de Frecuencias CNAF". Secretaría de Estado de Telecomunicaciones. Retrieved on 2008-03-05.^ "Channel Deployment Issues for 2.4 GHz 802.11 WLANs". Cisco Systems, Inc. Retrieved on 2007-02-07.
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 by closer stations, greatly reducing their throughput. This makes services such as Voice over IP (VoIP) or IPTV, which depend on an essentially-constant Quality of Service (QoS) depending on data rate and interruptibility, difficult to maintain for more than a few simultaneous users.
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 (unlike 802.11), the 802.16 scheduling algorithm can also be more bandwidth efficient. 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 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 Multiple-input multiple-output communications (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 .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.Architecture
The WiMAX Forum has defined an architecture that defines how a WiMAX network connects with other networks, and a variety of other aspects of operating such a network, including address allocation, authentication, etc.
An overview of the WiMAX architecture is given in the illustration. This defines the following components:
SS/MS: the Subscriber Station/Mobile StationASN: the Access Service Network BS: Base station, part of the ASNASN-GW: the ASN Gateway, part of the ASNCSN: the Connectivity Service NetworkHA: Home Agent, part of the CSNAAA: AAA Server, part of the CSNNAP: a Network Access ProviderNSP: a Network Service Provider
plus a number of interconnections (or reference points) between these, labeled R1 to R5 and R8.
It's 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, possibly because both begin with the same two letters, are based upon IEEE standards beginning with "802.", and are related to wireless connectivity and Internet access. However, the two standards are aimed at different applications.
* WiMAX is a long-range system, covering many kilometers that typically uses licensed spectrum (although it is possible to use unlicensed spectrum) to deliver a point-to-point
connection to the Internet from an ISP to an end user. Different 802.16 standards provide different types of access, from mobile (similar to a cellphone) to fixed (an alternative to wired access, where the end user's wireless termination point is fixed in location.)
* Wi-Fi is a shorter range system, typically tens of meters, that uses unlicensed spectrum to provide access to a network. Typically Wi-Fi is used by an end user to access their own network, which may or may not be connected to the Internet. If WiMAX provides services analogous to a cellphone, Wi-Fi is similar to a cordless phone. It's important to note, however, that free community Wi-Fi networks have shown that, with proper antennas, Wi-Fi can have a very long range.[citation needed]
* 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, which means that QoS parameters can be guaranteed for each flow. Wi-Fi has introduced a QoS mechanism similar to fixed Ethernet, where packets can receive different priorities based on their tags. This means that QoS is relative between packets/flows, as opposed to guaranteed.
* WiMAX is highly scalable from what are called "femto"-scale remote stations to multi-sector 'maxi' scale base that handle complex tasks of management and mobile handoff functions and include MIMO-AAS smart antenna subsystems.
Due to the ease and low cost with which Wi-Fi can be deployed, it is sometimes used to provide Internet access to third parties within a single room or building available to the provider, often informally, and sometimes as part of a business relationship. For example, many coffee shops, hotels, and transportation hubs contain Wi-Fi access points providing access to the Internet for customers.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,[10] (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. Telecom companies are unlikely to use this spectrum widely other than for backhaul, as 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 uses 3.5 GHz.
Analog TV bands (700 MHz) may become available for WiMAX use, but await the complete rollout 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. 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 Radiocommunication 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. In reality, WiMAX can do one or the other — operating over maximum range (50 km) increases bit error rate and thus must use a lower bitrate. Lowering the range allows a device to operate at higher bitrates.
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 an omni-directional antenna which is of lower-gain compared to directional antennas but are more portable. In practice, this means that in a line-of-sight environment with a portable Mobile WiMAX CPE, speeds of 10 Mbit/s at 10 km could be delivered. However, in urban environments they may not have line-of-sight and therefore users may only receive 10 Mbit/s over 2 km. In current deployments, throughputs are often closer to 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 Mobile 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, many users will have a range of 2-, 4-, 6-, 8-, 10- or 12 Mbit/s services and additional radio cards will be added to the base station to increase the capacity as required.
Because of this, various granular and distributed network architectures are being incorporated into WiMAX through independent development and within the 802.16j mobile multi-hop relay (MMR) task group. 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 is a leader in promoting WiMAX, and has developed its own chipset. However, it is notable that most of the major semiconductor companies have to date been more cautious of involvement and most of the products come from specialist smaller or start-up suppliers. For the client-side these include ApaceWave, GCT Semiconductor, Altair
Semiconductor, Beceem, Comsys, Runcom, Motorola with TI, NextWave, Sequans, Redpine signals, Wavesat, Coresonic and SySDSoft. Both Sequans and Wavesat manufacture products for both clients and network while TI, 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. The large number of suppliers during introduction phase of WiMAX demonstrates the low entry barriers for IPR.Standards
The current WiMAX incarnation, Mobile WiMAX, is based upon IEEE Std 802.16e-2005,[15] approved in December 2005. It is a supplement to the IEEE Std 802.16-2004,[16] 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'.
* 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.
* Improving NLOS coverage by utilizing advanced antenna diversity schemes, and hybrid-Automatic Retransmission Request (HARQ)
* Improving capacity and coverage by introducing Adaptive Antenna Systems (AAS) and Multiple Input Multiple Output (MIMO) technology
* Increasing system gain by use of denser sub-channelization, thereby improving indoor penetration
* Introducing high-performance coding techniques such as Turbo Coding and Low-Density Parity Check (LDPC), enhancing security and NLOS performance
* Introducing downlink sub-channelization, allowing administrators to trade coverage for capacity or vice versa
* Enhanced Fast Fourier Transform algorithm can tolerate larger delay spreads, increasing resistance to multipath interference
* Adding an extra QoS class (enhanced real-time Polling Service) more appropriate 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, Wi-Fi or even Mobile WiMAX.
SOFDMA (used in 802.16e-2005) and OFDM256 (802.16d) are not compatible so 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. This affects a relatively small number users and operators.Conformance testing
TTCN-3 test specification language is used for the purposes of specifying conformance tests for WiMAX implementations. WiMAX test suite is developed by a Specialist Task Force at ETSI (STF 252).
AssociationsWiMAX Forum
The WiMAX Forum is a non profit organization formed to promote the adoption of WiMax compatible products and services .
A major role for the organization is to certify the interoperability of WiMAX products. Those that pass conformance and interoperability testing achieve the "WiMAX Forum Certified" designation and can display this mark on their products and marketing materials. Some vendors claim that their equipment is "WiMAX-ready", "WiMAX-compliant", or "pre-WiMAX", if they are not officially WiMAX Forum Certified.
Another role of the WiMax Forum is to promote the spread of knowledge about WiMax. In order to do so, it has a certified training program that is currently offered in English and French. It also offers a series of member events and endorses some industry events.WiMAX Spectrum Owners Alliance
WiSOA is the first global organization composed exclusively of owners of WiMAX spectrum with plans to deploy WiMAX technology in those bands. WiSOA is focussed on the regulation, commercialisation, and deployment of WiMAX spectrum in the 2.3–2.5 GHz and the 3.4–3.5 GHz ranges. WiSOA are dedicated to educating and informing its members, industry representatives and government regulators of the importance of WiMAX spectrum, its use, and the potential for WiMAX to revolutionise broadband.Competing technologies
Within the marketplace, WiMAX's main competition comes from existing widely deployed wireless systems such as UMTS and CDMA2000, as well as a number of Internet oriented systems such as HIPERMAN.
3G cellular phone systems usually benefit from already having entrenched infrastructure, being upgraded from earlier systems. Users can usually fall back to older systems when they move out of range of upgraded equipment, often relatively seamlessly.
Speed vs. Mobility of wireless systems: Wi-Fi, HSPA, UMTS, GSM
The major cellular standards are being evolved to so-called 4G, high bandwidth, low latency, all-IP networks with voice services built on top. With GSM/UMTS, the move to 4G is the 3GPP Long Term Evolution effort. For AMPS/TIA derived standards such as CDMA2000, a replacement called Ultra Mobile Broadband is under development. In both cases, existing air interfaces are being discarded, in favour of OFDMA for the downlink and a variety of OFDM based techniques for the uplink, much akin to WiMAX.
In some areas of the world the wide availability of UMTS and a general desire for standardization has meant spectrum has not been allocated for WiMAX: in July 2005, the EU-wide frequency allocation for WiMAX was blocked.Mobile Broadband Wireless Access
Mobile Broadband Wireless Access (MBWA) is a technology being developed by IEEE 802.20 and is aimed at wireless mobile broadband for operations from 120 to 350 km/h. The 802.20 standard committee was first to define many of the methods which were later funneled into Mobile WiMAX, including high speed dynamic modulation and similar scalable OFDMA capabilities. It apparently retains fast hand-off, Forward Error Correction (FEC) and cell edge enhancements.
The Working Group was temporarily suspended in mid 2006 by the IEEE-SA Standards Board since it had been the subject of a number of appeals, and a preliminary investigation of one of these "revealed a lack of transparency, possible 'dominance,' and other irregularities in the Working Group".
In September 2006 the IEEE-SA Standards Board approved a plan to enable the working group to continue under new conditions, and the standard is now expected to be finalized by Q2 2008.Comparison of Mobile Internet Access methods
5.7611.5HSDPA widely deployed. Typical downlink rates today 1–2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 42 Mbit/s.
UMTS-TDDUMTS/3GSMMobile InternetCDMA/TDD1616Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA
1xRTTCDMA2000Mobile phoneCDMA0.1440.144Succeeded by EV-DO
EV-DO 1x Rev. 0EV-DO 1x Rev.AEV-DO Rev.BCDMA2000Mobile InternetCDMA/FDD2.453.14.9xN0.151.81.8xNRev B note: N is the number of 1.25 MHz chunks of spectrum used. Not yet deployed.
Notes: All speeds are theoretical maximums and will vary by a number of factors, including the use of external antennae, distance from the tower and the ground speed (e.g. communications on a train may be poorer than when standing still). Usually the bandwidth is shared between several terminals. The performance of each technology is determined by a number of constraints, including the spectral efficiency of the technology, the cell sizes used, and the amount of spectrum available. For more information, see Comparison of wireless data standards. LTE is still on the drawing board and LTE specifications herein are yet to be certified. LTE is expected to be commercially available in 2012.
Future development
Mobile WiMAX based upon 802.16e-2005 has been accepted as IP-OFDMA for inclusion as the sixth wireless link system under IMT-2000. This can hasten acceptance by regulatory authorities and operators for use in cellular spectrum. WiMAX II, 802.16m will be proposed for IMT-Advanced 4G.
The goal for the long term evolution of both WiMAX and LTE is to achieve 100 Mbit/s mobile and 1 Gbit/s fixed-nomadic bandwidth as set by ITU for 4G NGMN (Next Generation Mobile Network) systems through the adaptive use of MIMO-AAS and smart, granular network topologies. 3GPP LTE and WiMAX-m are concentrating much effort on MIMO-AAS, mobile multi-hop relay networking and related developments needed to deliver 10X and higher Co-Channel reuse multiples.
Since the evolution of core air-link technologies has approached the practical limits imposed by Shannon's Theorem, the evolution of wireless has embarked on pursuit of the 3X to 10X+ greater bandwidth and network efficiency by advances in the spatial and smart wireless broadband networking technologies.Interference
A field test conducted by SUIRG (Satellite Users Interference Reduction Group) with support from the U.S. Navy, the Global VSAT Forum, and several member organizations yielded conclusive results on the incompatibility of WiMAX systems and satellites sharing the C-band.
The WiMAX Forum has not answered yet.
WiMAX Terminals
This is a list of WiMAX final user terminals:
* Asustek
o Asustek WM34E1, a mobile WiMAX Wave1 modem.
o Asustek WM25E2 and WM34E2, which support Wave2.
* AWB RG230.
* CiriTech
o CiriMAX200, a mobile WiMAX Wave2 modem.
* Motorola / Enfora:
o WTM1000, WiMAX terminal modem
* Nokia
o N810 WiMAX Edition 802.16e, 2.5 GHz; also has 802.11b/g and Bluetooth 2 + EDR.[26]
* POSDATA Flyvo’s USB modem U100
* Samsung:
o SPH-P9200, combines WiMAX, WiFi and HSDPA.
o SPH-M8200, a PDA supporting WiMAX and EVDO.
o SWT-H200K and SPH-H1300, two USB WiMAX data adapters (USB modems).
