WiMAX

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WiMAX, the Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless data over long distances in a variety of ways, from point-to-point links to full mobile cellular type access. It is based on the IEEE 802.16 standard, which is also called WirelessMAN. The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformance 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).^{[citation needed]}

Currently, Pakistan has the largest fully functional nationwide Wimax network in the world.^[1] Wateen Telecom installed the network in seventeen cities throughout Pakistan using Motorola hardware.^[2]

Contents 1 Definitions 2 Uses 2.1 Broadband access 2.1.1 Subscriber units 2.2 Mobile handset applications 2.3 Backhaul/access network applications 3 Technical information 3.1 MAC layer/data link layer 3.2 Physical layer 3.3 Architecture 3.4 Comparison with Wi-Fi 3.5 Spectrum allocation issues 3.6 Spectral efficiency 3.7 Limitations 3.8 Silicon implementations 4 Standards 5 Conformance testing 6 Associations 6.1 WiMAX Forum 6.2 WiMAX Spectrum Owners Alliance 7 Competing technologies 7.1 Mobile Broadband Wireless Access 7.2 Internet-oriented systems 7.3 Comparison 8 Future development 9 Interference 10 Current deployments 10.1 Networks 10.2 Terminals 11 By territory 11.1 Europe 11.1.1 Germany 12 See also 13 References 14 External links

[edit] Definitions

The terms "fixed WiMAX", "mobile WiMAX", "802.16d" and "802.16e" are frequently used incorrectly.^[3] Correct definitions are:

Mobile communication standards

GSM / UMTS (3GPP) Family

GSM (2G) GPRS EDGE (EGPRS) EDGE Evolution CSD HSCSD

UMTS (3G) HSPA HSDPA HSUPA HSPA+ UMTS-TDD TD-CDMA TD-SCDMA FOMA

UMTS Rev. 8 (Pre-4G) LTE HSOPA (Super 3G)

CDMA (3GPP2) Family

cdmaOne (2G)

CDMA2000 (3G) EV-DO

UMB (Pre-4G)

AMPS Family

AMPS (1G) TACS / ETACS

D-AMPS (2G)

Other Technologies

0G PTT MTS IMTS AMTS OLT MTD Autotel / PALM ARP

1G NMT Hicap CDPD Mobitex DataTAC

2G iDEN PDC CSD PHS WiDEN

Pre-4G iBurst HIPERMAN WiMAX WiBro GAN (UMA)

Channel Access Methods FDMA OFDMA TDMA SSMA CDMA

Frequency bands Cellular GSM UMTS PCS SMR

• 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 frequently called "mobile WiMAX".

[edit] Uses

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

• Connecting Wi-Fi hotspots with each other and to other parts of the Internet.
• Providing a wireless alternative to cable and DSL for last mile broadband access.
• Providing high-speed data and telecommunications services.
• Providing a diverse 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 nomadic connectivity.

[edit] Broadband access

Many companies are closely examining WiMAX for "last mile" connectivity at high data rates. 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. Prior to WiMAX, many operators have been using proprietary fixed wireless technologies for broadband services.

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.

WiMAX was used by Intel to assist the FCC and FEMA in their communications efforts in the areas affected by Hurricane Katrina.^[4]

[edit] 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 advent 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.

[edit] 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.^[5] 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.

[edit] 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.^[6][7]

"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.

[edit] 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.

[edit] 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 need compete 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.

[edit] 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.

[edit] 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 architecture is given in the illustration. This defines the following components:

• SS/MS: the Subscriber Station/Mobile Station
• ASN: the Access Service Network ^[8]
• 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: AAA Server, part of the CSN
• NAP: a Network Access Provider
• NSP: 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.

[edit] 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 both have a connection to wireless connectivity and the Internet. Despite this, 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 also 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 data access via 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 hundreds of meters, that uses unlicensed spectrum to provide access to a network, typically covering only the network operator's own property. 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 more analogous to a cordless phone.
• WiMAX and Wi-Fi have quite different Quality of Service (QoS) mechanisms. WiMAX uses a mechanism based on setting up 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.

[edit] 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,^[9] (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,^[10] 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.

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.^[11] EU commissioner Viviane Reding has suggested re-allocation of 500–800 MHz spectrum for wireless communication, including WiMAX.^[12]

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.^[13] 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.

[edit] 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.^{[citation needed]}

[edit] 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.

[edit] 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 solutions 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 & SySDSoft. Both Sequans and Wavesat manufacture solutions for both clients and network while TI, DesignArt, and picoChip are focused on WiMAX chip sets for base stations. The large number of suppliers during introduction phase of WiMAX demonstrates the low entry barriers for IPR.

[edit] Standards

The current WiMAX incarnation, Mobile WiMAX, is based upon IEEE Std 802.16e-2005,^[14] approved in December 2005. It is an amendment of IEEE Std 802.16-2004,^[15] 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.

[edit] 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).^[16]

[edit] Associations

[edit] WiMAX Forum

The WiMAX Forum is the organization dedicated to certifying the interoperability of WiMAX products.^[17] 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.

[edit] 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.^[18]

[edit] 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 and WiBro.

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.

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 solutions 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.

[edit] 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".^[19]

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.

[edit] Internet-oriented systems

Early WirelessMAN standards, the European standard HIPERMAN and Korean standard WiBro have been harmonized as part of WiMAX and are no longer seen as competition but as complementary. All networks now being deployed in South Korea, the home of the Wibro standard, are now WiMAX.

As a short-range mobile Internet solution, such as in cafes and at transportation hubs like airports, the popular Wi-Fi 802.11b/g system is widely deployed, and provides enough coverage for some users to feel subscription to a WiMAX service is unnecessary.

[edit] Comparison

Main article: Comparison of wireless data standards

The following table should be treated with caution as it only shows peak rates which are potentially very misleading. In addition the comparisons listed are not normalized by physical channel size (i.e. spectrum used to achieve the listed peak rates); this obfuscates spectral efficiency and net through-put capabilities of the different wireless technologies listed below.

Comparison of Mobile Internet Access methods

Standard	Family	Primary Use	Radio Tech	Downlink (Mbit/s)	Uplink (Mbit/s)	Notes
LTE	UMTS/4GSM	Mobile Internet	OFDMA/MIMO/SC-FDMA	326.4	86.4	LTE-Advanced update to offer over 1 Gbit/s speeds.
802.16e	WiMAX	Mobile Internet	MIMO-SOFDMA	70	70	Quoted speeds only achievable at very short ranges, more practically 10 Mbit/s at 10 km.
HIPERMAN	HIPERMAN	Mobile Internet	OFDM	56.9	56.9
WiBro	WiBro	Mobile Internet	OFDMA	50	50	Mobile range (900 m)
iBurst	iBurst 802.20	Mobile Internet	HC-SDMA/TDD/MIMO	64	64	3–12 km
EDGE Evolution	GSM	Mobile Internet	TDMA/FDD	1.9	0.9	3GPP Release 7
UMTS W-CDMA HSDPA+HSUPA HSPA+	UMTS/3GSM	Mobile Internet	CDMA/FDD CDMA/FDD/MIMO	0.384 14.4 42	0.384 5.76 11.5	HSDPA widely deployed. Typical downlink rates today 1–2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 42 Mbit/s.
UMTS-TDD	UMTS/3GSM	Mobile Internet	CDMA/TDD	16	16	Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA
1xRTT	CDMA2000	Mobile phone	CDMA	0.144	0.144	Succeeded by EV-DO
EV-DO 1x Rev. 0 EV-DO 1x Rev.A EV-DO Rev.B	CDMA2000	Mobile Internet	CDMA/FDD	2.45 3.1 4.9xN	0.15 1.8 1.8xN	Rev 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.

[edit] 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.

[edit] 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.^[20]

The WiMAX Forum has not answered yet.

[edit] Current deployments

[edit] Networks

Main article: List of deployed WiMAX networks

The WiMAX Forum now lists over 350 WiMAX trials and deployments. Current and planned deployments and the bands in which they operate and the standards they use are listed in the above article.

[edit] Terminals

This is a list of WiMAX final user terminals: ^[21]

• Asustek
  • Asustek WM34E1, a mobile WiMAX Wave1 modem. ^[22]
  • Asustek WM25E2 and WM34E2, which support Wave2.
• AWB RG230.
• Motorola / Enfora:
  • WTM1000, WiMAX terminal modem ^[23]
• POSDATA Flyvo’s USB modem U100
• Samsung:^[24]
  • SPH-P9200, combines WiMAX, WiFi and HSDPA.
  • SPH-M8200, a PDA supporting WiMAX and EVDO.
  • SWT-H200K and SPH-H1300, two USB WiMAX data adapters (USB modems).

Please help improve this section by expanding it. Further information might be found on the talk page or at requests for expansion.

[edit] By territory

[edit] Europe

Commissin Decision of 2008-05-21 on the harmonisation of the 3400-3800 MHz frequency band for terrestrial systems capable of providing electronic communications services in the Community. ^[25]

It includes:

• Pursuant to Article 4(2) of Decision 676/2002/EC (of the European Parliament and of the Council of 7 March 2002 on a regulatory framework for radio spectrum policy in the European Community - Radio Spectrum Decision -) ^[26], the Commission gave a mandate dated 4 January 2006 to the European Conference of Postal and Telecommunications Administrations (hereinafter the “CEPT”) to identify the conditions relating to theprovision of harmonised radio frequency bands in the EU for Broadband Wireless Access (BWA) applications.

• In response to that Mandate, the CEPT issued a report (CEPT Report 15) on BWA, which concludes that the deployment of fixed, nomadic and mobile networks is technically feasible within the 3400-3800 MHz frequency band under the technical conditions described in the Electronic Communications Committee's Decision ECC/DEC/(07)02 and Recommendation ECC/REC/(04)05.

• No later than six months after entry into force of this Decision, Member States shall designate and make available, on a non-exclusive basis, the 3400-3600 MHz band for terrestrial electronic communications networks.

• By 1 January 2012 Member States shall designate and subsequently make available, on a non-exclusive basis, the 3600-3800 MHz band for terrestrial electronic communications networks.

• The designation of the 3400-3800 MHz band for fixed, nomadic and mobile applications is an important element addressing the convergence of the mobile, fixed and broadcasting sectors and reflecting technical innovation. Member States shall allow the use of the 3400-3800 MHz band in for fixed, nomadic and mobile electronic communications networks.

• This Decision is addressed to the Member States.

[edit] Germany

German Federal Network Agency has begun assigning frequencies for wireless Internet access in the band 3400 to 3600 MHz (in some places up to 3800 MHz). ^[27]

[edit] See also

• Asustek
• Broadband wireless access
• Customer-premises equipment
• Huawei
• List of deployed WiMAX networks
• Mobile broadband
• Mobile voip
• Municipal broadband
• Switched mesh
• WiBro
• Wireless local loop
• ZTE

[edit] References

[edit] External links

• How WiMAX Works at HowStuffWorks
• Patent alliance formed for WiMAX 4G technology

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