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WiMAX base station equipment with a sector antenna and wireless modem on top

A pre-WiMAX CPE of a 26 km connection mounted 13 meters above the ground (2004, Lithuania).

WiMAX, meaning Worldwide Interoperability for Microwave Access, is a telecommunications technology that provides wireless transmission of data using a variety of transmission modes, from point-to-multipoint links to portable and fully mobile[citation needed] internet access. The technology provides up to 3 Mbit/s [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] broadband speed without the need for cables. The technology is based on the IEEE 802.16 standard (also called Broadband Wireless Access). The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".[13]

Contents[hide]

1 Definitions 2 Uses

o 2.1 Broadband access 2.1.1 Subscriber units (Client Units)

o 2.2 Mobile handset applications o 2.3 Backhaul/access network applications

3 Technical information o 3.1 MAC layer/data link layer o 3.2 Physical layer o 3.3 Complexities of deployment o 3.4 Integration with an IP based Network o 3.5 Comparison with Wi-Fi o 3.6 Spectrum allocation issues o 3.7 Spectral efficiency o 3.8 Limitations o 3.9 Silicon implementations

4 Standards

2

5 Conformance testing 6 Associations

o 6.1 WiMAX Forum o 6.2 WiMAX Spectrum Owners Alliance

7 Competing technologies o 7.1 Mobile Broadband Wireless Access o 7.2 Internet-oriented systems o 7.3 Comparison

8 Future development 9 Interference 10 Current deployments

o 10.1 Networks 11 By territory

o 11.1 Africa o 11.2 Americas o 11.3 Asia o 11.4 Europe

11.4.1 Germany 11.4.2 United Kingdom

o 11.5 Indonesia 12 Literature 13 See also 14 Notes and references

15 External links

[edit] Definitions

The terms "fixed WiMAX", "mobile WiMAX", "802.16d" and "802.16e" are frequently used incorrectly.[14] 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 formas 802.16e. It introduced support for mobility, amongst other things and is therefore also known as "mobile WiMAX".

[edit] Uses

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

Connecting Wi-Fi hotspots to the Internet. Providing a wireless alternative to cable and DSL for "last mile" broadband access. Providing data and telecommunications services. Providing a source of Internet connectivity as part of a business continuity plan. That is, if

a business has a fixed and a wireless Internet connection, especially from unrelated providers, they are unlikely to be affected by the same service outage.

Providing portable connectivity.

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[edit] Broadband access

Companies are closely examining WiMAX for last mile connectivity.[citation needed] 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.[citation needed]

WiMAX access was used to assist with communications in Aceh, Indonesia, after the tsunami in December 2004.[citation needed] All communication infrastructure in the area, other than amateur radio, was destroyed, making the survivors unable to communicate with people outside the disaster area and vice versa. WiMAX provided broadband access that helped regenerate communication to and from Aceh.[citation needed]

In addition, WiMAX was donated by Intel Corporation to assist the FCC and FEMA in their communications efforts in the areas affected by Hurricane Katrina.[15] In practice, volunteers used mainly self-healing mesh, VoIP, and a satellite uplink combined with Wi-Fi on the local link.[16]

[edit] Subscriber units (Client Units)

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

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

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

[edit] Mobile handset applications

Sprint Nextel announced in mid-2006 that it would invest about US$ 5 billion in a WiMAX technology buildout over the next few years.[17] Since that time Sprint has been dealt setbacks that have resulted in steep quarterly losses. On May 7, 2008, Sprint, Imagine, Google, Intel, Comcast, and Time Warner announced a pooling of an average of 120 MHz of spectrum and formation of a new company which will take the name Clearwire. The new company hopes to benefit from combined services offerings and network resources as a springboard past its competitors. The cable companies will provide media services to other partners while gaining access to the wireless network as a Mobile virtual network operator. Google will contribute Android handset device development and applications and will receive revenue share for advertising and other services they provide. Clearwire Sprint and current Clearwire gain a majority stock ownership in the new venture and ability to access between the new Clearwire andSprint 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.

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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. Otheranalysts point out that as wireless progresses to higher bandwidth, it inevitably competes more directly with cable and DSL, thrusting competitors into bed together. Also, as wireless broadband networks grow denser and usage habits shift, the need for increased back haul and media service will accelerate, therefore the opportunity to leverage cable assets is expected to increase.

[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 poor nations.[18]

[19]

In North America, Backhaul for urban cellular operations is typically provided via one or more copper wire line T1 connections, whereas remote cellular operations are sometimes "backhauled"via satellite. In most other regions, urban and rural backhaul is usually provided by Microwave links. (The exception to this is where the network is operated by an incumbent with ready access to the copper network, in which case T1 lines may be used). WiMAX is a broadband platform and as such has much more substantial backhaul bandwidth requirements than legacy cellular applications. Therefore traditional copper wire line backhaul solutions are not appropriate. Consequently the use of wireless microwave backhaul is on the rise in North America and existing microwave backhaul links in all regions are being upgraded. [20] Capacities of between 34 Mbit/s and 1 Gbit/s are routinely being deployed with latencies in the order of 1ms. [citation needed] In many cases, operators are aggregating sites using wireless technology and then presenting traffic on to fiber networks where convenient.

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

[edit] Technical information

Illustration of a WiMAX MIMO board

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

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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.[citation needed] This can cause subscriber stations distant from the AP to be repeatedly interrupted[citation needed] by closer stations, greatly reducing their throughput.[citation needed]

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.[citation needed] In addition to being stable under overload and over-subscription[citation needed], the 802.16 scheduling algorithm can also be more bandwidth efficient.[citation needed] The scheduling algorithm also allows the base station to control QoS parameters by balancing the time-slot assignments among the application needs of the subscriber stations[citation needed].

[edit] Physical layer

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

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

[edit] Complexities of deployment

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

In the MAC Frame the subscriber stations are allocated and their individual burst profiles defined as well as the specific time allocation, but even if that is done automatically practical deployment

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should avoid high interference and high multipath environments as opposed to what the average radio network planning team (and executive staff from the adopting operator) could think, the reason for it lies in excessive interference and competition during the Initial Ranging (IR) process due to the usage of high transmitting power in base station (BS) and subscriber station (SS) alike,which can result in unwanted delays and ranging attempts that effectively detracts from a good user experience and can even result in wasted allocated symbols due to continuous connections/re-connections.

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

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

[edit] Integration with an IP based Network

The WiMAX Forum WiMAX Architecture

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

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

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SS/MS: the Subscriber Station/Mobile Station ASN: the Access Service Network[21] BS: Base station, part of the ASN ASN-GW: the ASN Gateway, part of the ASN CSN: the Connectivity Service Network HA: Home Agent, part of the CSN AAA: Authentication, Authorization and Accounting Server, part of the CSN NAP: a Network Access Provider NSP: a Network Service Provider

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

[edit] Comparison with Wi-Fi

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

WiMAX uses spectrum to deliver a point-to-point connection to the Internet. Different 802.16 standards provide different types of access, from portable (similar to a cordless phone) to fixed (an alternative to wired access, where the end user's wireless termination point is fixed in location.)

Wi-Fi uses unlicensed spectrum to provide access to a network. Wi-Fi is more popular in end user devices.

WiMAX and Wi-Fi have quite different Quality of Service (QoS) mechanisms. WiMAX uses a mechanism based on connections between the Base Station and the user device. Each connection is based on specific scheduling algorithms. Wi-Fi has a QoS mechanism similar to fixed Ethernet, where packets can receive different priorities based on their tags. For example VoIP traffic may be given priority over web browsing.

Wi-Fi runs on the MAC's CSMA/CA protocol, which is connectionless and contention based, whereas WiMAX runs a connection-oriented MAC.

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

[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,[22] (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.

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

In the USA, the biggest segment available is around 2.5 GHz,[23] and is already assigned, primarily to Sprint Nextel and Clearwire. Elsewhere in the world, the most-likely bands used will be the Forum approved ones, with 2.3 GHz probably being most important in Asia. Some countries in Asia like India and Indonesia will use a mix of 2.5 GHz, 3.3 GHz and other frequencies. Pakistan's Wateen Telecom uses 3.5 GHz.

Analog TV bands (700 MHz) may become available for WiMAX usage, but await the complete 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.[24] Both of these companies have stated their intention of supporting LTE, a technology which competes directly with WiMAX. EU commissioner Viviane Reding has suggested re-allocation of 500–800 MHz spectrum for wireless communication, including WiMAX.[25]

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

Since October 2007, the Radio communication Sector of the International Telecommunication Union (ITU-R) has decided to include WiMAX technology in the IMT-2000 set of standards.[26] Thisenables 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 (~31 miles). In reality, WiMAX can either operate at higher bitrates or over longer distances but not both: operating at the maximum range of 50 km increases bit error rate and thus results in a much lower bitrate. Conversely, reducing the range (to <1m) allows a device to operate at higher bitrates. There are no known examples of WiMAX services being delivered at bit rates over around 3 Mbit/s.

Typically, fixed WiMAX networks have a higher-gain directional antenna installed near the client (customer) which results in greatly increased range and throughput. Mobile WiMAX networks are usually made of indoor "Customer-premises equipment" (CPE) such as desktop modems, laptops

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with integrated Mobile WiMAX or other Mobile WiMAX devices. Mobile WiMAX devices typically have omnidirectional antennae which are of lower-gain compared to directional antennas but are more portable. In current deployments, the throughput may reach 2 Mbit/s symmetric at 10 km with fixed WiMAX and a high gain antenna. It is also important to consider that a throughput of 2 Mbit/s can mean 2 Mbit/s, symmetric simultaneously, 1 Mbit/s symmetric or some asymmetric mix (e.g. 0.5 Mbit/s downlink and 1.5 Mbit/s uplink or 1.5 Mbit/s downlink and 0.5 Mbit/s uplink), each of which required slightly different network equipment and configurations. Higher-gain directional antennas can be used with a WiMAX network with range and throughput benefits but the obvious loss of practical mobility.

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

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

[edit] Silicon implementations

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

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

[edit] Standards

The current WiMAX incarnation, Mobile WiMAX, is based upon IEEE Std 802.16e-2005,[27] approved in December 2005. It is a supplement to the IEEE Std 802.16-2004,[28] and so the actualstandard is 802.16-2004 as amended by 802.16e-2005 — the specifications need to be read together to understand them.

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

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

Adding support for mobility (soft and hard handover between base stations). This is seen as one of the most important aspects of 802.16e-2005, and is the very basis of 'Mobile WiMAX' (though this has yet to be demonstrated in any installed systems).

Scaling of the Fast Fourier transform (FFT) to the channel bandwidth in order to keep the carrier spacing constant across different channel bandwidths (typically 1.25 MHz, 5 MHz,

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10 MHz or 20 MHz). Constant carrier spacing results in a higher spectrum efficiency in wide channels, and a cost reduction in narrow channels. Also known as Scalable OFDMA(SOFDMA). Other bands not multiples of 1.25 MHz are defined in the standard, but because the allowed FFT subcarrier numbers are only 128, 512, 1024 and 2048, other frequency bands will not have exactly the same carrier spacing, which might not be optimal for implementations.

Advanced antenna diversity schemes, and hybrid automatic repeat-request (HARQ) Adaptive Antenna Systems (AAS) and MIMO technology Denser sub-channelization, thereby improving indoor penetration Introducing Turbo Coding and Low-Density Parity Check (LDPC) Introducing downlink sub-channelization, allowing administrators to trade coverage for

capacity or vice versa Fast Fourier transform algorithm Adding an extra QoS class for VoIP applications.

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

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

[edit] Conformance testing

TTCN-3 test specification language is used for the purposes of specifying conformance tests for WiMAX implementations. The WiMAX test suite is being developed by a Specialist Task Force at ETSI (STF 252).[29]

[edit] Associations

[edit] WiMAX Forum

The WiMAX Forum is a non profit organization formed to promote the adoption of WiMAX compatible products and services.[30]

A major role for the organization is to certify the interoperability of WiMAX products.[31] 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.

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[edit] WiMAX Spectrum Owners Alliance

WiSOA logo

WiSOA was the first global organization composed exclusively of owners of WiMAX spectrum with plans to deploy WiMAX technology in those bands. WiSOA 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 merged with the Wireless Broadband Alliance in April 2008.[32]

[edit] Competing technologies

Speed vs. Mobility of wireless systems: Wi-Fi, HSPA, UMTS, GSM

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 of course long range mobile Wi-Fi and mesh networking.

3G cellular phone systems usually benefit from already having entrenched infrastructure, having been 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. The worldwide move to 4G for GSM/UMTS and AMPS/TIA (including CDMA2000) is the 3GPP Long Term Evolution effort. A planned CDMA2000 replacement called Ultra Mobile Broadband has been discontinued. For 4G systems, existing air interfaces are being discarded in favor of OFDMA for the downlink and a variety of OFDM based techniques for the uplink, similar to WiMAX.

In some areas of the world, the wide availability of UMTS and a general desire for standardizationhas meant spectrum has not been allocated for WiMAX: in July 2005, the EU-wide frequency allocation for WiMAX was blocked.

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[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 75 to 220 mph (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 because it had been the subject of a number of appeals. A preliminary investigation of one of these "revealed a lack of transparency, possible 'dominance,' and other irregularities in the Working Group".[33]

In September 2006, the IEEE-SA Standards Board approved a plan to enable the working group to continue under new conditions, and on 12 June 2008, the IEEE approved the new standard.

Qualcomm, a leading company behind 802.20, has dropped support for continued development in order to focus on LTE.[34]

[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 technology, 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 neutrality of this article is disputed. Please see the discussion on the talk page. Please do not remove this message until the dispute is resolved. (January 2009)

The following table should be treated with caution because 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.

v • d • e Comparison of Mobile Internet Access methods

Standard Family PrimaryUse

Radio Tech Downlink(Mbit/s)

Uplink(Mbit/s) Notes

LTEUMTS/4GSM

General 4GOFDMA/MIMO/SC-FDMA

326.4 86.4

LTE-Advanced update to offer over 1 Gbit/s speeds.

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802.16 WiMAXMobile Internet

MIMO-SOFDMA 3 3

WiMAX II IMT-Advanced update to offer over 1 Gbit/s speeds.

Flash-OFDMFlash-OFDM

Mobile Internetmobility up to200mph (350km/h)

Flash-OFDM5.310.615.9

1.83.65.4

Mobile range 18miles (30km)extended range 34 miles(55km)

HIPERMAN HIPERMANMobile Internet

OFDM 56.9 56.9

Wi-Fi Wi-FiMobile Internet

OFDM/MIMO/CDMA

108 108Mobile range (3km)

iBurstiBurst 802.20

Mobile Internet

HC-SDMA/TDD/MIMO

64 64 3–12 km

EDGEEvolution

GSMMobile Internet

TDMA/FDD 1.9 0.93GPP Release7

UMTS W-CDMA

HSDPA+HSUPA

HSPA+

UMTS/3GSM

General 3G

CDMA/FDD

CDMA/FDD/MIMO

0.38414.442

0.3845.7611.5

HSDPA widely deployed. Typical downlink rates today 2 Mbit/s, ~200 kbit/s uplink; HSPA+ downlink up to 42 Mbit/s.

UMTS-TDDUMTS/3GSM

Mobile Internet

CDMA/TDD 16 16

Reported speeds according to IPWireless using 16QAM modulation similar to HSDPA+HSUPA

1xRTT CDMA2000Mobile phone

CDMA 0.144 0.144Succeeded by EV-DO

EV-DO 1x Rev. 0

EV-DO 1x Rev.A

EV-DO Rev.B

CDMA2000Mobile Internet

CDMA/FDD2.453.14.9xN

0.151.81.8xN

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 ona 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.

14

LTE is expected to be ratified at the end of 2008, with commercial implementations becoming viable within the next two years.

[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+ greaterbandwidth 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 fromthe U.S. Navy, the Global VSAT Forum, and several member organizations yielded results showing interference at 12 km when using the same channels for both the WiMAX systems and satellites in C-band.[35] The WiMAX Forum has not answered yet.

[edit] Current deployments

[edit] Networks

Main article: List of deployed WiMAX networks

The WiMAX Forum now claims there are over 400 WiMAX networks deployed in over 130 countries.

[edit] By territory

This section gives details of regulatory decisions in various parts of the world. For information on deployments around the world see the List of deployed WiMAX networks

[edit] Africa

In South Africa Telecoms Regulator ICASA has only issued four licences for commercial WiMAX services: to wireless broadband solutions provider iBurst, state-owned signal distributor Sentech, second network operator Neotel, [Amatole Telecommunication Services] (under serviced area

15

license holder in S.A.) and Telkom, all on the 3.5 GHz band. See the List of deployed WiMAX networks for details.

[edit] Americas

See the List of deployed WiMAX networks for details.

[edit] Asia

See the List of deployed WiMAX networks for details.

[edit] Europe

Commission Decision of 2008-05-21 on the harmonisation of the 3400-3800 MHz frequency bandfor terrestrial systems capable of providing electronic communications services in the Community.[36]

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 -),[37] 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 the provisionof 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, whichconcludes 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 European Conference of Postal and Telecommunications Administrations 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 communicationsnetworks.

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 inthe band 3400 to 3600 MHz (in some places up to 4000 MHz).[38]

[edit] United Kingdom

16

The UK telecoms industry is waiting for OFCOM the UK’s telecoms regulator, to launch the tenderprocess for the 2.6 GHz spectrum range for a number of services which can include WiMAX, including mobile services based on the 802.16e standard. This is currently expected in mid-2009.

[edit] Indonesia

The Indonesian government announced on January 22, 2009 two ministry decrees and three regulations releasing spectrum at 2.3GHz and 3.3GHz for wireless broadband access across all regions of Indonesia. This means Indonesia will be using 2.3-GHz bandfor the Wimax 16.e standard while 3.3-GHz will be used for the 16.d standard.[39]

[edit] Literature

K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE and WiMAX, 2nd Edition, John Wiley & Sons, 2008, ISBN 978-0-470-99821-2

M. Ergen, Mobile Broadband - Including WiMAX and LTE, Springer, NY, 2009 ISBN 978-0-387-68189-4

[edit] See also

Wikimedia Commons has media related to: WiMAX

Wikibooks has a book on the topic of Nets, Webs and the Information Infrastructure

Com-bridge Customer-premises equipment Evolved HSPA High-Speed Packet Access (HSPA) List of deployed WiMAX networks Mobile broadband Mobile VoIP Municipal broadband Packet Burst Broadband (PBB) Switched mesh WiBro wireless bridge Wireless broadband Wireless local loop

[edit] Notes and references

1. ^ "Mobilink FAQ". http://www.mobilinkinfinity.com/faqs/. Retrieved on 2009-03-30.

17

2. ^ "goBroadband". http://convergence.in/blog/2008/03/24/is-wimax-a-failure-tata-communications-acknowledges-shortcomings/. Retrieved on 2009-03-30.

3. ^ "Deutsche Breitland, offering up to 3Mbps download". http://www.wimaxforum.org/files/case_studies/dbd_deutsche_breitband_dienste.pdf/. Retrieved on 2009-03-30.

4. ^ "Danske Telecom, offers up to 2mbps downstream, up to 192kbps upstream". http://www.wimaxforum.org/files/case_studies/danske_telecom.pdf/. Retrieved on 2009-03-30.

5. ^ "Digital Bridge, 3mbps/2Mbps". http://www.wimaxforum.org/files/case_studies/digital_bridge.pdf/. Retrieved on 2009-03-30.

6. ^ "KT WiBro, offering up to 3Mbps down/1Mbps up". http://www.wimaxforum.org/files/case_studies/kt_wibro_v1.6.pdf/. Retrieved on 2009-03-30.

7. ^ "Max Telecom, provides data chart showing up to 1mbps down and almost 273kbps up". http://www.wimaxforum.org/files/case_studies/max_telecom_1.2.pdf/. Retrieved on 2009-03-30.

8. ^ "Packet One, offers up to 2.4 Mbps downstream". http://www.wimaxforum.org/files/case_studies/packet_one.pdf/. Retrieved on 2009-03-30.

9. ^ "Wateen, has offerings up to 1mbps downstream". http://www.wimaxforum.org/files/case_studies/wateen.pdf/. Retrieved on 2009-03-30.

10. ^ "WiMAX Telecom, up to 2mbps down, up to 500kbps up". http://www.wimaxforum.org/files/case_studies/wimax_telecom.pdf/. Retrieved on 2009-03-30.

11. ^ "Yota, has the highest speed claim on the WiMAX forum of up to 10Mbps downstream".http://www.wimaxforum.org/files/case_studies/yota.pdf/. Retrieved on 2009-03-30.

12. ^ "Yota services are however not yet available". http://www.yota.ru/en/prices/. Retrieved on 2009-03-30.

13. ^ "WiMax Forum - Technology". http://www.wimaxforum.org/technology/. Retrieved on 2008-07-22.

14. ^ "IEEE 802.16 WirelessMAN Standard: Myths and Facts". ieee802.org. http://www.ieee802.org/16/docs/06/C80216-06_007r1.pdf. Retrieved on 2008-03-12.

15. ^ "FCC Pushes WIMax OK for Katrina Victims, Intel supplies the hardware". mobilemag.com. http://www.mobilemag.com/content/100/102/C4618/. Retrieved on 2008-01-08.

16. ^ "Volunteers use mesh, wimax, wi-fi, in katrina-hit regions". wifinetnews.com. http://wifinetnews.com/archives/2005/10/volunteers_use_mesh_wimax_wi-fi_in_katrina-hit_regions.html/. Retrieved on 2009-03-31.

17. ^ "4G Mobile Broadband". sprint.com. http://www2.sprint.com/mr/cda_pkDetail.do?id=1260. Retrieved on 2008-03-12.

18. ^ "Sprint Eyes WiMax Backhaul". lightreading.com. http://www.lightreading.com/document.asp?doc_id=104349. Retrieved on 2008-03-22.

19. ^ "WiMax signals get stronger in India". eetimes.com. http://www.eetimes.com/news/latest/showArticle.jhtml?articleID=206901605. Retrieved on 2008-03-22.

20. ^ "Overcoming the wireline bottleneck for 3G wireless services". supercommnews.com. http://supercommnews.com/wireless/features/wireline_wireless_networks_060305/. Retrieved on 2009-01-03.

21. ^ "The Access Service Network in WiMAX: The Role of ASN-GW". mustafaergen.com. http://www.mustafaergen.com/asn-gw.pdf. Retrieved on 2008-03-12.

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22. ^ "Practical tips on making WiMAX field measurements, Part 1". rfdesignline.com. http://www.rfdesignline.com/197000698;jsessionid=QTVQPMTGVCCPCQSNDLQSKH0CJUNN2JVN?printableArticle=true. Retrieved on 2008-03-25.

23. ^ "U.S. Frequency Allocation Chart". Department of Commerce. http://www.ntia.doc.gov/osmhome/allochrt.pdf. Retrieved on 2008-03-12.

24. ^ "Auctions Schedule". FCC. http://wireless.fcc.gov/auctions/default.htm?job=auctions_sched. Retrieved on 2008-01-08.

25. ^ "European Commission proposes TV spectrum for WiMax". zdnetasia.com. http://www.zdnetasia.com/news/communications/0,39044192,62021021,00.htm. Retrieved on 2008-01-08.

26. ^ "ITU Radiocommunication Assembly approves new developments for its 3G standards". itu.int. http://www.itu.int/newsroom/press_releases/2007/30.html. Retrieved on 2008-03-12.

27. ^ "IEEE 802.16e Task Group (Mobile WirelessMAN)". ieee802.org. http://www.ieee802.org/16/tge/. Retrieved on 2008-03-12.

28. ^ "IEEE 802.16 Task Group d". ieee802.org. http://www.ieee802.org/16/tgd/. Retrieved on2008-03-12.

29. ^ "HiperMAN / WiMAX Testing". ETSI. http://www.etsi.org/WebSite/technologies/HiperMAN-WiMAXTesting.aspx. Retrieved on 2008-03-28.

30. ^ "WiMAX Forum Overview". http://www.wimaxforum.org/about. Retrieved on 2008-08-01.

31. ^ "WiMAX Forum — Frequently Asked Questions". wimaxforum.org. http://www.wimaxforum.org/technology/faq. Retrieved on 2008-03-12.

32. ^ "WBA and WiSOA join efforts on WiMAX global roaming)". http://www.wimaxday.net/site/2008/04/24/wba-and-wisoa-join-efforts-on-wimax-global-roaming. Retrieved on 2008-12-10.

33. ^ "Status of 802.20". ieee.org. http://grouper.ieee.org/groups/802/mbwa/email/pdf00015.pdf. Retrieved on 2008-03-12.

34. ^ "Qualcomm halts UMB project, sees no major job cuts". Reuters. 2008. http://www.reuters.com/article/marketsNews/idUSN1335969420081113?rpc=401&. Retrieved on 2008-12-02.

35. ^ "SUIRG full interference test report". suirg.org. http://www.suirg.org/pdf/SUIRG_WiMaxFieldTestReport.pdf. Retrieved on 2008-03-16.

36. ^ http://ec.europa.eu/information_society/policy/radio_spectrum/docs/in_transit/bwa/bwa_en.pdf

37. ^ http://ec.europa.eu/information_society/policy/radio_spectrum/docs/policy_outline/decision_6762002/en.pdf

38. ^ "Federal Network Agency begins assigning frequencies for wireless Internet access". bundesnetzagentur.de. http://www.bundesnetzagentur.de/media/archive/4564.pdf. Retrieved on 2008-06-01.

39. ^ "Wimax frequencies allocation in Indonesia". http://www.earthtimes.org/articles/show/tranzeo-and-trg-advance-indonesian-wimax-joint-development,694186.shtml.

[edit] External links

WiMAX Forum How WiMAX Works at HowStuffWorks

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Patent alliance formed for WiMAX 4G technology

[show] v • d • e

Mobile telecommunications standards

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

UMTS/FOMA (3G)HSPA • HSDPA • HSUPA • HSPA+ • UMTS-TDD • UTRA-TDD HCR •UTRA-TDD LCR • UMTS-FDD • Super-Charged

3GPP Rel. 8 (Pre-4G)E-UTRA

LTE Advanced (4G) •

cdmaOne (2G) •

CDMA2000 (3G)EV-DO • UMB

AMPS (1G)TACS/ETACS

D-AMPS (2G) •

Pre Cellular (0G)PTT • MTS • IMTS • AMTS • OLT • MTD • Autotel/PALM • ARP

1GNMT • Hicap • CDPD • Mobitex • DataTAC

2GiDEN • PDC • CSD • PHS • WiDEN

Pre-4GiBurst • HiperMAN • WiMAX • WiBro • GAN (UMA)

[hide]Internet Access

NetworkType

Wired Wireless

OpticalCoaxialCable

EthernetCable

Phone linePower

lineUnlicensed

terrestrial bandsLicensed terrestrial

bandsSatellite

LAN1000BASE-X

G.hn EthernetHomePNA · G.hn

G.hnWi-Fi · Bluetooth ·DECT · Wireless USB

WAN PON DOCSISDial-up · ISDN · DSL

BPL Muni Wi-FiGPRS · iBurst · WiBro/WiMAX · UMTS-TDD, HSPA · EVDO · LTE

Satellite

[show] v • d • e

Wireless video and data distribution methods

[show]

20

v • d • e

Wireless system generations

Retrieved from "http://en.wikipedia.org/wiki/WiMAX"Categories: Mobile telecommunications standards | IEEE 802 | Wireless networking | Metropolitan area networks | Ethernet | Network accessHidden categories: Articles needing additional references from April 2009 | All articles with unsourced statements | Articles with unsourced statements since March 2009 | Articles with unsourced statements since September 2007 | NPOV disputes from January 2009 | All NPOV disputes

Mobile VoIPFrom Wikipedia, the free encyclopedia

Jump to: navigation, search

Mobile VoIP is an extension of mobility to a VoIP Voice over IP network.

There are several methodologies by which a mobile handset can be integrated into a VoIP network. One implementation turns the mobile device into a standard SIP client, which then uses a data network to send and receive SIP messaging, and to send and receive RTP for the voice path. This methodology of turning a mobile handset into a standard SIP client requires that the mobile handset support, at minimum, high speed IP communications. In this application, standardVoIP protocols (typically SIP) are used over any broadband IP-capable wireless network connection such as EVDO rev A (which is symmetrical high speed — both high speed up and down), HSDPA, WiFi or WiMAX.

Another implementation of mobile integration uses a softswitch like gateway to bridge SIP and RTP into the mobile network's SS7 infrastructure. In this implementation, the mobile handset continues to operate as it always has (as a GSM or CDMA based device), but now it can be controlled by a SIP application server which can now provide advanced SIP based services to it. Several vendors offer this kind of capability today.

Mobile VoIP will require a compromise between economy and mobility. For example, Voice over Wi-Fi offers potentially free service but is only available within the coverage area of a Wi-Fi Access Point. High speed services from mobile operators using EVDO rev A or HSDPA may havebetter audio quality and capabilities for metropolitan-wide coverage including fast handoffs amongmobile base stations, yet it will cost more than the typical Wi-Fi-based VoIP service.

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Mobile VoIP will become an important service in the coming years as device manufacturers exploit more powerful processors and less costly memory to meet user needs for ever-more 'power in their pocket'. Smartphones in mid-2006 are capable of sending and receiving email, browsing the web (albeit at low rates) and in some cases allowing a user to watch TV.

The challenge for the mobile operator industry is to deliver the benefits and innovations of IP without losing control of the network service. Users like the Internet to be free and high speed without extra charges for visiting specific sites. Such a service challenges the most valuable service in the telecommunications industry — voice — and threatens to change the nature of the global communications industry.

Contents[hide]

1 Technologies 2 Recent developments 3 References 4 See also

5 External links

[edit] Technologies

Mobile VoIP relies on two main technologies:

UMA — the Unlicensed Mobile Access Generic Access Network, designed to allow VoIP to run over the GSM cellular backbone

SIP — the standard used by most VoIP services, and now being implemented on mobile handsets

[edit] Recent developments

In the summer of 2006, a SIP (Session Initiation Protocol) stack was introduced and a VoIP client in Nokia E-series dual-mode Wi-Fi handsets (Nokia E60, Nokia E61, Nokia E70). The SIP stack and client have since been introduced in many more E and N-series dual-mode Wi-Fi handsets, most notably the Nokia N95 which has been very popular in Europe. Various services use these handsets. Recently Nokia introduced a built in VoIP client to the mass market device (Nokia 6300i) running Series 40 operating system. Nokia maintains a list of all phones that have an integrated VoIP client here.

Aircell's battle with some companies allowing VoIP calls on flights is another example of the growing conflict of interest between incumbent operators and new VoIP operators.[1]

[edit] References

1. ^ "Aircell: On U.S. Planes, VoIP Will Be Muted" GigaOm August 26, 2008

[edit] See also

22

Fixed mobile convergence MoIP Upsnap Voice over IP Vowlan — VoIP over a Wi-Fi network

[edit] External links

ZDNet: Mobile VoIP means business

[hide] v • d • e

Mobile phones

General History · Development · Features

NetworkingNetwork operators · Standard comparison · Frequencies · Mobile VoIP · SIM · WAP · XHTML-MP · Mobile phone signalGenerations: 1G · 2G · 3G · 4G

DevicesCamera phone · Flip form · Other form factors · Mobile phone manufacturers · Smartphones

Applications and services

Banking · Blogging · Commerce · Content · Email · Gambling · Gaming · Health · Instant messaging · Learning · Location tracking · Marketing · Music · News · Payment · Publishing · Search · SMS · Telephony · Ticketing · Web

Culture Charms · Comics · Dating · Novels · Ringtones · Ringxiety

Health and environment Driving safety · Electronic waste · Radiation & health

Retrieved from "http://en.wikipedia.org/wiki/Mobile_VoIP"

MoIPFrom Wikipedia, the free encyclopedia

Jump to: navigation, search

This article needs additional citations for verification. Please help improve this article by adding reliable references (ideally, using inline citations). Unsourced materialmay be challenged and removed. (February 2008)

MoIP, or mobile communications over internet protocol, is the mobilization of peer-to-peer communications including chat and talk using internet protocol via standard mobile communications applications including 3G, GPRS, Wifi as well as Wimax. Unlike mobile VoIP,

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MoIP is not a VoIP program made accessible from mobile phones or a switchboard application using VoIP in the background. It is rather a native mobile application on users’ handsets and usedto conduct talk and chat over the internet connection as its primary channel.

[edit] How MoIP (mobile) works

MoIP applications typically work without any proprietary hardware, are enhanced with real-time contact availability (presence) and save the users money by utilizing free WiFi internet access or fixed internet data plans instead of GSM (talk) minutes. They are completely mobile-centric, designed and optimized specifically for mobile-handsets environment rather than the PC.

[edit] Alternate Definition

MoIP is also sometimes used to refer to:

Mobile VoIP Modem over IP or Modem over VoIP. Media over Internet Protocol Meetings Over IP Messaging Over Internet Protocol Missile On Internal Power

[edit] External links

ZDNet: Mobile VoIP means business

Mobile broadbandFrom Wikipedia, the free encyclopedia

Jump to: navigation, search

This article may be confusing or unclear to readers. Please help clarify the article; suggestions may be found on the talk page. (February 2009)

A mobile broadband modem in the ExpressCard form factor

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Mobile broadband is the name used to describe various types of wireless high-speed internet access through a portable modem, telephone or other device. Various network standards may be used, such as GPRS, 3G, WiMAX, LTE UMTS/HSPA, EV-DO and some portable satellite-based systems[1].

Devices that provide mobile broadband include: PC data cards, USB modems, USB sticks, phones with data modems and portable devices with built-in support for Mobile Broadband (like notebooks, netbooks and Mobile Internet Devices (MIDs)). Notebooks with built-in Mobile Broadband Modules are offered by all leading laptop manufacturers in Europe and Asia including:Dell, Lenovo (previously IBM), HP, Fujitsu, Toshiba and Acer.

A group of telecommunication manufacturers, mobile phone producers, chipset manufacturers and notebook manufacturers have joined forces to push built-in support for Mobile Broadband technology on notebook computers[2]. The players have established a service mark to identify devices that deliver the highest standard of Mobile Broadband.

Contents[hide]

1 Development 2 See also 3 References

4 External links

[edit] Development

On 11 December 2002, the IEEE Standards Board approved the establishment of IEEE 802.20 [3], the Mobile Broadband Wireless Access (MBWA) Working Group.

The mission of IEEE 802.20 is to develop the specification for an efficient packet based air interface that is optimized for the transport of IP based services. The goal is to enable worldwide deployment of affordable, ubiquitous, always-on and interoperable multi-vendor mobile broadband wireless access networks that meet the needs of business and residential end user markets.

The main barrier to the take up of mobile broadband will be the coverage the mobile phone networks can provide, in many areas customers will not be able to achieve the speeds advertiseddue to mobile data coverage limitations.

Demand from emerging markets fuels a large share of growth in Mobile Broadband over the coming years. Without the need to start from the basis of a widespread fixed line infrastructure, many emerging markets leapfrog developed markets and use Mobile Broadband technologies to deliver high-speed internet access to the mass market.

The global Third Generation Partnership Project (3GPP) family of standards - which includes GSM, EDGE, WCDMA, HSPA and LTE – is the most widespread way to deliver mobile broadband. 3GPP standards are serving about 90 percent of the world’s mobile subscribers.

25

In October 2008, a steering group known as Digital Britain was setup, with the aim of promoting digital telecommunications in the United Kingdom. The conclusion of the steering group was a recommendation that the government took up, namely to have 100% broadband coverage, with aminimum speed of 2mbs in the United Kingdom by the year 2012. Mobile broadband is expected to be utilized to help spread broadband coverage to the more remote areas of the UK.

In 2009 actions were taken by the telecommunication industry that led many to believe that price fixing was taking place. Every provider (AT&T, Verizon, Sprint, and T-Mobile) all offered the same mobile broadband plan at the same price. 5GB max at $60 a month. Under the Sherman Act,[1] July 2, 1890 this would be illegal, and allows for any individual the right to sue under the antitrust laws. As evident in the network outage on April 9, 2009 in Santa Clara, Santa Cruz, and San Benito counties in California all these companies are interlinked and share the same network, which would also constitute monopoly practices.

[edit] See also

Mobile VoIP Broadband Internet access Broadband Mobile Enterprise

[edit] References

This article does not cite any references or sources. Please help improve this articleby adding citations to reliable sources (ideally, using inline citations). Unsourced material may be challenged and removed. (February 2007)

1. ^ Mobile Broadband by M. Ergen

2. ^ GSMA - Mobile Broadband

3. ^ IEE 802.20 Mobile Broadband Wireless Access (MBWA)

[edit] External links

IEEE 802.20 Mission and Project Scope The Mobile Broadband Group Accelerating global development with mobile broadband Mobile Broadband news and articles HSPA – the undisputed choice for mobile broadband

Retrieved from "http://en.wikipedia.org/wiki/Mobile_broadband"Categories: Broadband | TelecommunicationsHidden categories: Wikipedia articles needing clarification from February 2009 | Articles lacking sources from February 2007 | All articles lacking sources

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Voice over Internet ProtocolFrom Wikipedia, the free encyclopedia

(Redirected from Voice over IP)Jump to: navigation, search"Digital voice" redirects here. For the service of the same name, see Comcast Digital Voice.

This article needs additional citations for verification. Please help improve this article by adding reliable references (ideally, using inline citations). Unsourced materialmay be challenged and removed. (January 2009)

This article is in need of attention from an expert on the subject. WikiProject Law or the Law Portal may be able to help recruit one. (November 2008)

Voice over Internet Protocol (VoIP) is a general term for a family of transmission technologies for delivery of voice communications over IP networks such as the Internet or other packet-switched networks. Other terms frequently encountered and synonymous with VoIP are IP telephony, Internet telephony, voice over broadband (VoBB), broadband telephony, and broadband phone.

VoIP systems usually interface with the traditional public switched telephone network (PSTN) to allow for transparent phone communications worldwide.[1]

VoIP systems employ session control protocols to control the set-up and tear-down of calls as well as audio codecs which encode speech allowing transmission over an IP network as digital audio via an audio stream. Codec use is varied between different implementations of VoIP (and often a range of codecs are used); some implementations rely on narrowband and compressed speech, while others support high fidelity stereo codecs.

Cisco VoIP phone

Contents[hide]

1 History 2 VoIP Implementations 3 Adoption

o 3.1 Consumer market o 3.2 PSTN and mobile network providers o 3.3 Corporate use

4 Benefits o 4.1 Operational cost o 4.2 Flexibility

27

5 Challenges o 5.1 Quality of Service

5.1.1 Layer-2 Quality of Service o 5.2 Susceptibility to power failure o 5.3 Emergency calls o 5.4 Number portability o 5.5 PSTN Integration o 5.6 Security o 5.7 Caller ID o 5.8 Interconnection to traditional PSTN telephones o 5.9 Fax handling o 5.10 Support for other telephony devices

6 Legal Issues 7 International VoIP Implementation

o 7.1 IP telephony in Japan 8 See also 9 References

10 External links

[edit] History

1974 - The Institute of Electrical and Electronic Engineers (IEEE) published a paper entitled "A Protocol for Packet Network Interconnection."[2]

1981 - IPv4 is described in RFC-791.[3] 1985 - The National Science Foundation commissions the creation of NSFNET.[4] 1995 - VocalTec releases the first commercial Internet phone software.[5][6] 1996 -

o ITU-T begins the standardization of VoIP initially with the H.323 standard.[7] o US telecommunication companies ask the US Congress to ban Internet phone

technology.[8] 1997 - Level 3 began development of its first softswitch (a term they coined in 1998).[9] 1999 -

o The Session Initiation Protocol (SIP) specification RFC 2543 was released.[10] o The first open source SIP PBX (Asterisk) is created by Mark Spencer of Digium.

[11] 2004 - Commercial VoIP service providers proliferate.[12] 2009 - Skype releases a Wi-Fi only application for the iPhone [13]

[edit] VoIP Implementations

Voice over IP has been implemented in various ways using both proprietary and open protocols and standards. Examples of available VoIP implementations include:

SIP/RTP IMS H.323 Skype

28

Further examples and comparisons are available from the following Wikipedia article: Comparison of VoIP software

[edit] Adoption

[edit] Consumer market

Example of VoIP adapter setup in residential network

A major development starting in 2004[14] has been the introduction of mass-market VoIP services over broadband Internet access services, in which subscribers make and receive calls as they would over the PSTN. Full phone service VoIP phone companies provide inbound and outbound calling with Direct Inbound Dialing. Many offer unlimited calling to the U.S., and some to Canada or selected countries in Europe or Asia as well, for a flat monthly fee as well as free calling between subscribers using the same provider.[15] These services have a wide variety of features which can be more or less similar to traditional POTS.

There are three common methods of connecting to VoIP service providers:

A typical analog telephone adapter (ATA) for connecting an analog phone to a VoIP provider An Analog Telephone Adapter (ATA) may be connected between an IP network (such as

a broadband connection) and an existing telephone jack in order to provide service nearlyindistinguishable from PSTN providers on all the other telephone jacks in the residence. This type of service, which is fixed to one location, is generally offered by broadband Internet providers such as cable companies and telephone companies as a cheaper flat-rate traditional phone service.

29

Dedicated VoIP phones are phones that allow VoIP calls without the use of a computer. Instead they connect directly to the IP network (using technologies such as Wi-Fi or Ethernet). In order to connect to the PSTN they usually require service from a VoIP service provider therefore most people also use them in conjunction with a paid service plan.

A softphone (also known as an Internet phone or Digital phone) is a piece of software thatcan be installed on a computer that allows VoIP calling without dedicated hardware. An advantage of using a softphone with a VoIP service provider is the ability of having a fixedphone number which you can move to any country or location (This is also possible with ATAs and VoIP phones, however requires the physical relocation of the hardware).

[edit] PSTN and mobile network providers

It is becoming increasingly common for telecommunications providers to use VoIP telephony overdedicated and public IP networks to connect switching stations and to interconnect with other telephony network providers (this is often referred to as 'IP backhaul').[16][17]

Many telecommunications companies are looking at the IP Multimedia Subsystem (IMS) which will merge Internet technologies with the mobile world, using a pure VoIP infrastructure. It will enable them to upgrade their existing systems while embracing Internet technologies such as the Web, email, instant messaging, presence, and video conferencing. It will also allow existing VoIP systems to interface with the conventional PSTN and mobile phone networks.

"Dual mode" telephone sets, which allow for the seamless handover between a cellular network and a Wi-Fi network, are expected to help VoIP become more popular.[18]

Phones such as the NEC N900iL, many of the Nokia Eseries and several other Wi-Fi enabled mobile phones have SIP clients built into the firmware. Such clients operate independently of the mobile phone network (however some operators choose to remove the client from subsidised handsets). Some operators such as Vodafone actively try to block VoIP traffic from their network.[19] Others, like T-Mobile, have refused to interconnect with VoIP-enabled networks as was seen inthe legal case between T-Mobile and Truphone, which ultimately was settled in the UK High Courtin favour of the VoIP carrier.[20]

[edit] Corporate use

Because of the bandwidth efficiency and low costs that VoIP technology can provide, businesses are gradually beginning to migrate from traditional copper-wire telephone systems to VoIP systems to reduce their monthly phone costs.[21]

VoIP solutions aimed at businesses have evolved into "unified communications" services that treat all communications—phone calls, faxes, voice mail, e-mail, Web conferences and more—asdiscrete units that can all be delivered via any means and to any handset, including cellphones. Two kinds of competitors are competing in this space: one set is focused on VoIP for medium to large enterprises, while another is targeting the small-to-medium business (SMB) market.[22]

VoIP also offers the advantage of running both voice and data communications over a single network which can represent a significant saving in infrastructure costs.[23]

Other advantages that appeal to business is that the per extension prices of VoIP are lower than those of PBXs or key systems. Also, VoIP switches rely on commodity hardware, such as PCs or

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Linux systems, so they are easy to configure and troubleshoot. Rather than closed architectures, these devices rely on standard interfaces.[24]

VoIP devices also have simple, intuitive user interfaces, so employees can often make simple system configuration changes. Features such as dual-mode cellphones enable users to continue their conversations as they move from an outside cellular service to an internal wi-fi network. The bundling means employees no longer have to carry a desktop phone and a cellphone, so companies can reduce their telecommunications equipment costs. Maintenance also becomes simpler, because there are fewer devices to oversee.[25]

Most recently Skype, which originally marketed itself as a service among friends, has begun to cater to businesses. If a company's clients, contacts and employees join the Skype network, they can be called for free, wherever they are in the world. Skype makes this simple; find the name of your contact, click and call, and all calls cost the employer nothing.[26]

[edit] Benefits

[edit] Operational cost

VoIP can be a benefit for reducing communication and infrastructure costs. Examples include:

Routing phone calls over existing data networks to avoid the need for separate voice and data networks.[27]

Conference calling, IVR, call forwarding, automatic redial, and caller ID features that traditional telecommunication companies (telcos) normally charge extra for are available for free from open source VoIP implementations such as Asterisk.

[edit] Flexibility

VoIP can facilitate tasks and provide services that may be more difficult to implement using the PSTN. Examples include:

The ability to transmit more than one telephone call over the same broadband connection.[28] This can make VoIP a simple way to add an extra telephone line to a homeor office.

Secure calls using standardized protocols (such as Secure Real-time Transport Protocol.)Most of the difficulties of creating a secure phone connection over traditional phone lines, like digitizing and digital transmission, are already in place with VoIP. It is only necessary to encrypt and authenticate the existing data stream.[29]

Location independence. Only an Internet connection is needed to get a connection to a VoIP provider. For instance, call center agents using VoIP phones can work from anywhere with a sufficiently fast and stable Internet connection.

Integration with other services available over the Internet, including video conversation, message or data file exchange in parallel with the conversation, audio conferencing, managing address books, and passing information about whether others (e.g., friends or colleagues) are available to interested parties.

[edit] Challenges

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[edit] Quality of Service

Because the underlying IP network is inherently unreliable, in contrast to the circuit-switched public telephone network, and does not inherently provide a mechanism to ensure that data packets are delivered in sequential order, or provide Quality of Service (QoS) guarantees, VoIP implementations face problems mitigating latency and jitter.

Voice travels over IP networks in packets in the same manner as data, so when you talk over an IP network your conversation is broken up into small packets. These voice and data packets travel over the same network with a fixed bandwidth. This system is more prone to congestion[citation needed] and DoS attacks [30] than traditional circuit switched systems.

Fixed delays cannot be controlled (as they are caused by the physical distance the packets travel), however some delays can be minimized by marking voice packets as being delay-sensitive (see, for example, DiffServ). Fixed delays are especially problematic when satellite circuits are involved, due to long round-trip propagation delay (400–600 milliseconds for links through geostationary satellites).

A cause of packet loss and delay is congestion, which can be avoided by means of teletraffic engineering.

The receiving node must restructure IP packets that may be out of order, delayed or missing, while ensuring that the audio stream maintains a proper time consistency. Variation in delay is called jitter. The effects of jitter can be mitigated by storing voice packets in a jitter buffer upon arrival and before producing analog audio, although this further increases delay. This avoids a condition known as buffer underrun, in which the voice engine is missing audio since the next voice packet has not yet arrived. When IP packets are lost or delayed at any point in the network between VoIP users there will be a momentary dropout of voice if all packet delay and loss mechanisms cannot compensate.

It has been suggested to rely on the packetized nature of media in VoIP communications and transmit the stream of packets from the source phone to the destination phone simultaneously across different routes (multi-path routing).[31] In such a way, temporary failures have less impact on the communication quality. In capillary routing it has been suggested to use at the packet levelFountain codes or particularly raptor codes for transmitting extra redundant packets making the communication more reliable.[citation needed]

A number of protocols have been defined to support the reporting of QoS/QoE for VoIP calls. These include RTCP XR (RFC3611), SIP RTCP Summary Reports, H.460.9 Annex B (for H.323), H.248.30 and MGCP extensions. The RFC3611 VoIP Metrics block is generated by an IP phone or gateway during a live call and contains information on packet loss rate, packet discard rate (due to jitter), packet loss/discard burst metrics (burst length/density, gap length/density), networkdelay, end system delay, signal / noise / echo level, MOS scores and R factors and configuration information related to the jitter buffer.

RFC3611 VoIP metrics reports are exchanged between IP endpoints on an occasional basis during a call, and an end of call message sent via SIP RTCP Summary Report or one of the othersignaling protocol extensions. RFC3611 VoIP metrics reports are intended to support real time

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feedback related to QoS problems, the exchange of information between the endpoints for improved call quality calculation and a variety of other applications.

[edit] Layer-2 Quality of Service

A number of protocols that deal with Data link layer and Physical Layer include Quality of Service mechanisms that can be used to ensure that applications like VoIP work well even in congested scenarios. Some examples include:

IEEE 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of Quality of Service enhancements for wireless LAN applications through modifications to the Media Access Control (MAC) layer. The standard is considered of critical importance for delay-sensitive applications, such as Voice over Wireless IP.

The ITU-T G.hn standard, which provides a way to create a high-speed (up to 1 Gigabit/s) Local area network using existing home wiring (power lines, phone lines and coaxial cables). G.hn provides QoS by means of "Contention-Free Transmission Opportunities" (CFTXOPs) which are allocated to flows (such as a VoIP call) which require QoS and which have negotiated a "contract" with the network controller.

[edit] Susceptibility to power failure

Telephones for traditional residential analog service are usually connected directly to telephone company phone lines which provide direct current to power most basic analog handsets independently of locally available power.

IP Phones and VoIP telephone adapters connect to routers or cable modems which typically depend on the availability of mains electricity or locally generated power.[32] Some VoIP service providers use customer premise equipment (e.g., cablemodems) with battery-backed power supplies to assure uninterrupted service for up to several hours in case of local power failures. Such battery-backed devices typically are designed for use with analog handsets.

The susceptibility of phone service to power failures is a common problem even with traditional analog service in areas where many customers purchase modern handset units that operate wirelessly to a base station, or that have other modern phone features, such as built-in voicemail or phone book features.

[edit] Emergency calls

This section uses first-person ("I"; "we") or second-person ("you") inappropriately.Please rewrite it to use a more formal, encyclopedic tone. (March 2009)

This section is written like a personal reflection or essay and may require cleanup. Please help improve it by rewriting it in an encyclopedic style.

The nature of IP makes it difficult to locate network users geographically. Emergency calls, therefore, cannot easily be routed to a nearby call center. Sometimes, VoIP systems may route emergency calls to a non-emergency phone line at the intended department. In the United States,at least one major police department has strongly objected to this practice as potentially endangering the public.[33]

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A fixed line phone has a direct relationship between a telephone number and a physical location. A telephone number represents one pair of wires that links a location to the telco's exchange. Once a line is connected, the telco stores the home address that relates to the wires, and this relationship will rarely change. If an emergency call comes from that number, then the physical location is known.

In the IP world it is not so simple. A broadband provider may know the location where the wires terminate, but this does not necessarily allow the mapping of an IP address to that location. IP addresses are often dynamically assigned, so the ISP may allocate an address for online access,or at the time a broadband router is engaged. The ISP recognizes individual IP addresses, but does not necessarily know what physical location to which it corresponds. The broadband serviceprovider knows the physical location, but is not necessarily tracking the IP addresses in use.

There are more complications, since IP allows a great deal of mobility. For example, a broadband connection can be used to dial a virtual private network that is employer-owned. When this is done, the IP address being used will belong to the range of the employer, rather than the addressof the ISP, so this could be many kilometres away or even in another country. To provide another example: if mobile data is used (e.g. a 3G mobile handset or USB wireless broadband adapter) then the IP address has no relationship with any physical location, since a mobile user could be anywhere that there is network coverage, even roaming via another cellco.

In short there is no relationship between IP address and physical location, so the address itself reveals no useful information for the emergency services.

At the VoIP level, a phone or gateway may identify itself with a SIP registrar by using a username and password. So in this case, the Internet Telephony Service Provider (ITSP) knows that a particular user is online, and can relate a specific telephone number to the user. However, it does not recognize how that IP traffic was engaged. Since the IP address itself does not necessarily provide location information presently, today a "best efforts" approach is to use an available database to find that user and the physical address the user chose to associate with that telephone number--clearly an imperfect solution.

VoIP Enhanced 911 (E911) is another method by which VoIP providers in the United States are able to support emergency services. The VoIP E911 emergency-calling system associates a physical address with the calling party's telephone number as required by the Wireless Communications and Public Safety Act of 1999. All "interconnected" VoIP providers (those that provide access to the PSTN system) are required to have E911 available to their customers.[34] VoIP E911 service generally adds an additional monthly fee to the subscriber's service per line, similar to analog phone service. Participation in E911 is not required and customers can opt-out or disable E911 service on their VoIP lines, if desired. VoIP E911 has been successfully used by many VoIP providers to provide physical address information to emergency service operators.

One shortcoming of VoIP E911 is that the emergency system is based on a static table lookup. Unlike in cellular phones, where the location of an E911 call can be traced using Assisted GPS orother methods, the VoIP E911 information is only accurate so long as subscribers are diligent in keeping their emergency address information up-to-date. In the United States, the Wireless Communications and Public Safety Act of 1999 leaves the burden of responsibility upon the subscribers and not the service providers to keep their emergency information up to date.

A tragic example of a miscommunication with VoIP is the death of 18-month-old Elijah Luck in Calgary, Canada. In an emergency, 9-1-1 services were called. An ambulance was sent to the former home of the Lucks. The VoIP telephone company knew the correct address, as they were paying their bill from the correct current billing address the company had on record. "It's up to subscribers to ensure the company has up-to-date contact information" was the response from

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the VoIP company. After about a half hour wait, the Lucks called from a neighbour's land line, whereupon emergency services arrived in six minutes. Elijah Luck was pronounced dead at the Alberta Children's Hospital.[35]

[edit] Number portability

Local number portability (LNP) and Mobile number portability (MNP) also impact VoIP business. In November 2007, the Federal Communications Commission in the United States released an order extending number portability obligations to interconnected VoIP providers and carriers that support VoIP providers[36]. Number portability is a service that allows a subscriber to select a new telephone carrier without requiring a new number to be issued. Typically, it is the responsibility of the former carrier to "map" the old number to the undisclosed number assigned by the new carrier. This is achieved by maintaining a database of numbers. A dialed number is initially received by the original carrier and quickly rerouted to the new carrier. Multiple porting referencesmust be maintained even if the subscriber returns to the original carrier. The FCC mandates carrier compliance with these consumer-protection stipulations.

A voice call originating in the VoIP environment also faces challenges to reach its destination if the number is routed to a mobile phone number on a traditional mobile carrier. VoIP has been identified in the past as a Least Cost Routing (LCR) system, which is based on checking the destination of each telephone call as it is made, and then sending the call via the network that willcost the customer the least[citation needed]. This rating is subject to some debate given the complexity of call routing created by number portability. With GSM number portability now in place, LCR providers can no longer rely on using the network root prefix to determine how to route a call. Instead, they must now determine the actual network of every number before routing the call.

Therefore, VoIP solutions also need to handle MNP when routing a voice call. In countries withouta central database, like the UK, it might be necessary to query the GSM network about which home network a mobile phone number belongs to. As the popularity of VoIP increases in the enterprise markets because of least cost routing options, it needs to provide a certain level of reliability when handling calls.

MNP checks are important to assure that this quality of service is met. By handling MNP lookups before routing a call and by assuring that the voice call will actually work, VoIP service providers are able to offer business subscribers the level of reliability they require.

In countries such as Singapore, the most recent Mobile number portability solution is expected to open the doors to new business opportunities for non-traditional telecommunication service providers like wireless broadband providers and voice over IP (VoIP) providers.[citation needed].

[edit] PSTN Integration

E.164 is a global numbering standard for both the PSTN and PLMN. Most VoIP implementations support E.164 to allow calls to be routed to and from VoIP subscribers and the PSTN/PLMN[37]. VoIP implementations can also allow other identification techniques to be used. For example, Skype allows subscribers to choose 'Skype names'[38] (usernames) whereas SIP implementations can use URIs [39] similar to email addresses. Often VoIP implementations employ methods of translating non-E.164 identifiers to E.164 numbers and vice-versa, such as the Skype-In service provided by Skype[40] and the ENUM service in IMS and SIP[41].

Echo can also be an issue for PSTN integration[42] . Common causes of echo include impedance mismatches in analog circuitry and acoustic coupling of the transmit and receive signal at the receiving end.

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[edit] Security

As a computer-based technology, Voice over Internet Protocol telephone systems (VoIP) are as susceptible to attacks as PCs. This means that hackers who know about these vulnerabilities caninstitute denial-of-service attacks, harvest customer data, record conversations and break into voice mailboxes.[43]

Another challenge is routing VoIP traffic through firewalls and network address translators. PrivateSession Border Controllers are used along with firewalls to enable VoIP calls to and from protected networks. Skype uses a proprietary protocol to route calls through other Skype peers on the network, allowing it to traverse symmetric NATs and firewalls. Other methods to traverse NATs involve using protocols such as STUN or ICE.

Many consumer VoIP solutions do not support encryption, although having a secure phone is much easier to implement with VoIP than traditional phone lines. As a result, it is relatively easy toeavesdrop on VoIP calls and even change their content.[44] An attacker with a packet sniffer could intercept your VoIP calls if you are not on a secure VLAN.

There are open source solutions, such as Wireshark, that facilitate sniffing of VoIP conversations. A modicum of security is afforded by patented audio codecs in proprietary implementations that are not easily available for open source applications[citation needed], however such security through obscurity has not proven effective in other fields.[citation needed] Some vendors also use compression to make eavesdropping more difficult.[citation needed] However, real security requires encryption and cryptographic authentication which are not widely supported at a consumer level. The existing security standard Secure Real-time Transport Protocol (SRTP) and the new ZRTP protocol are available on Analog Telephone Adapters(ATAs) as well as various softphones. It is possible to useIPsec to secure P2P VoIP by using opportunistic encryption. Skype does not use SRTP, but uses encryption which is transparent to the Skype provider[citation needed]. In 2005, Skype invited a researcher, Dr Tom Berson, to assess the security of the Skype software, and his conclusions areavailable in a published report[45].

The Voice VPN solution provides secure voice for enterprise VoIP networks by applying IPSec encryption to the digitized voice stream.

[edit] Caller ID

Caller ID support among VoIP providers varies, although the majority of VoIP providers now offer full caller ID with name on outgoing calls.

In a few cases, VoIP providers may allow a caller to spoof the caller ID information, potentially making calls appear as though they are from a number that does not belong to the caller[46]. Business grade VoIP equipment and software often makes it easy to modify caller ID information. Although this can provide many businesses great flexibility, it is also open to abuse.

The "Truth in Caller ID Act" has been in preparation in the US congress since 2006, but as of January 2009 still has not been enacted. This bill proposes to make it an offence in the USA to "knowingly transmit misleading or inaccurate caller identification information with the intent to defraud, cause harm, or wrongfully obtain anything of value ..."[47]

[edit] Interconnection to traditional PSTN telephones

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Some analog telephone adapters do not decode pulse dialing from older phones. The VoIP user may use a pulse-to-tone converter, if needed.[citation needed]

[edit] Fax handling

Support for sending faxes over VoIP implementations is still limited. The existing voice codecs arenot designed for fax transmission; they are designed to digitize an analog representation of a human voice efficiently. However, the inefficiency of digitizing an analog representation (modem signal) of a digital representation (a document image) of analog data (an original document) morethan negates any bandwidth advantage of VoIP. In other words, the fax "sounds" simply don’t fit inthe VoIP channel. An alternative IP-based solution for delivering fax-over-IP called T.38 is available.

The T.38 protocol is designed to work like a traditional fax machine and can work using several configurations. The fax machine could be a traditional fax machine connected to the PSTN, or an ATA box (or similar). It could be a fax machine with an RJ-45 connector plugged straight into an IP network, or it could be a computer pretending to be a fax machine. [48] Originally, T.38 was designed to use UDP and TCP transmission methods across an IP network. The main difference between using UDP and TCP methods for a FAX is the real time streaming attributes. TCP is better suited for use between two IP devices. However, older fax machines, connected to an analog system, benefit from UDP near real-time characteristics[citation needed].

There have been updated versions of T.30 to resolve the fax over IP issues, which is the core fax protocol. Some new fax machines have T.38 built-in capabilities which allow the user to plug right into the network with minimal configuration changes[citation needed]. A unique feature of T.38 is that each packet contains a copy of the main data in the previous packet. This is an option and most implementations seem to support it. This forward error correction scheme makes T.38 far more tolerant of dropped packets than VoIP[citation needed]. With T.38, two successive lost packets are needed to actually lose any data. The data you lose will only be a small piece, but with the right settings and error correction mode, there is a high probability that you will receive the whole transmission.

Tweaking the settings on the T.30 and T.38 protocols could also turn your unreliable fax into a robust machine[citation needed]. Some fax machines pause at the end of a line to allow the paper feed to catch up. This is good news for packets that were lost or delayed because it gives them a chance to catch up. However, were this to happen on every line, your fax transmittal would take along time. Another possible solution is to treat the fax system as a message switching system, which does not need a real-time data transmission (such as sending a fax as an email attachment(see Fax) or remote printout (see Internet Printing Protocol)). The end system can completely buffer the incoming fax data before displaying or printing the fax image.

[edit] Support for other telephony devices

Another challenge for VoIP implementations is the proper handling of outgoing calls from other telephony devices such as DVR boxes, satellite television receivers, alarm systems, conventionalmodems and other similar devices that depend on access to a PSTN telephone line for some or all of their functionality.

These types of calls sometimes complete without any problems, but in other cases they fail. If VoIP and cellular substitution becomes very popular, some ancillary equipment makers may be forced to redesign equipment, because it would no longer be possible to assume a conventional PSTN telephone line would be available in consumer's homes.

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[edit] Legal Issues

This article is in need of attention from an expert on the subject. WikiProject Law or the Law Portal may be able to help recruit one. (November 2008)

As the popularity of VoIP grows, and PSTN users switch to VoIP in increasing numbers, governments are becoming more interested in regulating VoIP in a manner similar to PSTN services,[49] especially with the encouragement of the state-mandated telephone monopolies/oligopolies in a given country, who see this as a way to stifle the new competition.

Another legal issue that the U.S. Congress is debating concerns changes to the Foreign Intelligence Surveillance Act. The issue in question is calls between Americans and foreigners. The National Security Agency (NSA) isn't authorized to tap Americans' conversations without a warrant--but the Internet, and specifically voice over Internet protocol, or VoIP, doesn't draw as clear a line to the location of a caller or a call's recipient as the traditional phone system does. [50] So as VoIP's low cost and flexibility convinces more and more organizations to adopt the technology, the line separating the NSA's ability to snoop on phone calls will only get blurrier.[51] VoIP technology has also increased security concerns because VoIP and similar technologies have made it more difficult for the government to determine where a target is physically located when communications are being intercepted, and that creates a whole set of new legal challenges.[52]

In the U.S., the Federal Communications Commission now requires all interconnected VoIP service providers to comply with requirements comparable to those for traditional telecommunications service providers. VoIP operators in the U.S. are required to support local number portability; make service accessible to people with disabilities; pay regulatory fees, universal service contributions, and other mandated payments; and enable law enforcement authorities to conduct surveillance pursuant to the Communications Assistance for Law Enforcement Act (CALEA). "Interconnected" VoIP operators also must provide Enhanced 911 service, disclose any limitations on their E-911 functionality to their consumers, and obtain affirmative acknowledgements of these disclosures from all consumers.[53] VoIP operators also receive the benefit of certain U.S. telecommunications regulations, including an entitlement to interconnection and exchange of traffic with incumbent local exchange carriers via wholesale carriers. Providers of "nomadic" VoIP service — those who are unable to determine the location of their users — are exempt from state telecommunications regulation.[54]

Throughout the developing world, countries where regulation is weak or captured by the dominantoperator, restrictions on the use of VoIP are imposed, including in Panama where VoIP is taxed, Guyana where VoIP is prohibited and India where its retail commercial sales is allowed but only for long distance service.[55] In Ethiopia, where the government is monopolizing telecommunication service, it is a criminal offense to offer services using VoIP. The country has installed firewalls to prevent international calls being made using VoIP. These measures were taken after a popularity in VoIP reduced the income generated by the state owned telecommunication company.

In the European Union, the treatment of VoIP service providers is a decision for each Member State's national telecoms regulator, which must use competition law to define relevant national markets and then determine whether any service provider on those national markets has "significant market power" (and so should be subject to certain obligations). A general distinction is usually made between VoIP services that function over managed networks (via broadband connections) and VoIP services that function over unmanaged networks (essentially, the Internet).

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VoIP services that function over managed networks are often considered to be a viable substitute for PSTN telephone services (despite the problems of power outages and lack of geographical information); as a result, major operators that provide these services (in practice, incumbent operators) may find themselves bound by obligations of price control or accounting separation.

VoIP services that function over unmanaged networks are often considered to be too poor in quality to be a viable substitute for PSTN services; as a result, they may be provided without any specific obligations, even if a service provider has "significant market power".

The relevant EU Directive is not clearly drafted concerning obligations which can exist independently of market power (e.g., the obligation to offer access to emergency calls), and it is impossible to say definitively whether VoIP service providers of either type are bound by them. A review of the EU Directive is under way and should be complete by 2007.

In India, it is legal to use VoIP, but it is illegal to have VoIP gateways inside India. This effectively means that people who have PCs can use them to make a VoIP call to any number, but if the remote side is a normal phone, the gateway that converts the VoIP call to a POTS call should not be inside India.

In the UAE, it is illegal to use any form of VoIP, to the extent that websites of Skype and Gizmo Project are blocked.

In the Republic of Korea, only providers registered with the government are authorized to offer VoIP services. Unlike many VoIP providers, most of whom offer flat rates, Korean VoIP services are generally metered and charged at rates similar to terrestrial calling. Foreign VoIP providers such as Vonage encounter high barriers to government registration. This issue came to a head in 2006 when Internet service providers providing personal Internet services by contract to United States Forces Korea members residing on USFK bases threatened to block off access to VoIP services used by USFK members of as an economical way to keep in contact with their families inthe United States, on the grounds that the service members' VoIP providers were not registered. A compromise was reached between USFK and Korean telecommunications officials in January 2007, wherein USFK service members arriving in Korea before June 1, 2007 and subscribing to the ISP services provided on base may continue to use their U.S.-based VoIP subscription, but later arrivals must use a Korean-based VoIP provider, which by contract will offer pricing similar tothe flat rates offered by U.S. VoIP providers.[56]

[edit] International VoIP Implementation

[edit] IP telephony in Japan

This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources (ideally, using inline citations). Unsourcedmaterial may be challenged and removed. (January 2009)

In Japan, IP telephony (IP電話 IP Denwa ?) is regarded as a service applied by VoIP technologyto the whole or a part of the telephone line. As of 2003, IP telephony services have been assigned telephone numbers. IP telephony services also often include videophone/video conferencing services. According to the Telecommunication Business Law, the service category for IP telephony also implies the service provided via Internet, which is not assigned any telephone number.

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IP telephony is basically regulated by Ministry of Internal Affairs and Communications (MIC) as a telecommunication service. The operators have to disclose necessary information on its quality, etc., prior to making contracts with customers, and have an obligation to respond to their complaints cordially.

Many Japanese Internet service providers (ISP) are including IP telephony services. An ISP who also provides IP telephony service is known as a "ITSP (Internet Telephony Service Provider)". Recently, the competition among ITSPs has been activated, by option or set sales, in connection with ADSL or FTTH services.

The tariff system normally applied to Japanese IP telephony is described below;

A call between IP telephony subscribers, limited to the same group, is usually free of charge.

A call from IP telephony subscribers to a fixed line or PHS is usually a uniformly fixed rateall over the country.

Between ITSPs, the interconnection is mostly maintained at VoIP level.

Where the IP telephony is assigned normal telephone number (0AB-J), the condition for its interconnection is considered same as normal telephony.

Where the IP telephony is assigned specific telephone number (050), the condition for its interconnection is described below;

o Interconnection is sometimes charged. (Sometimes, it's free of charge.) In case of free-of-charge, mostly, communication traffic is exchanged via a P2P connection with the same VoIP standard. Otherwise, certain conversions are needed at the point of the VoIP gateway which incurs operating costs.

Since September 2002, the MIC has assigned IP telephony telephone numbers on the condition that the service falls into certain required categories of quality.

High-quality IP telephony is assigned a telephone number, normally starting with the digits 050. When VoIP quality is so high that a customer has difficulty telling the difference between it and a normal telephone, and when the provider relates its number with a location and provides the connection with emergency call capabilities, the provider is allowed to assign a normal telephone number, which is a so-called "0AB-J" number.

[edit] See also

Wikimedia Commons has media related to: VoIP

Capillary routing Communications Assistance For Law Enforcement Act Comparison of VoIP software Computer conferencing Differentiated services ENUM H.323 Harvard sentences

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Integrated services Internet fax IP Multimedia Subsystem IP Phone Mobile VoIP Mouth-to-ear delay PATS Predictive dialers Secure telephone SIP VoiceXML VoIP recording

[edit] References

1. ^ "Skype for Business". Skype, (C) 2008 Skype Limited. http://www.skype.com/intl/en/business/allfeatures/callphones/.

2. ^ Vinton G. Cerf, Robert E. Kahn, "A Protocol for Packet Network Intercommunication", IEEE Transactions on Communications, Vol. 22, No. 5, May 1974 pp. 637-648

3. ^ "RFC791". University of Southern California. September 1, 1981. http://www.faqs.org/rfcs/rfc791.html. Retrieved on 2009-01-21.

4. ^ "The Launch of NSFNET". The National Science Foundation. http://www.nsf.gov/about/history/nsf0050/internet/launch.htm. Retrieved on 2009-01-21.

5. ^ Keating, Tom. "Internet Phone Release 4" (PDF). Computer Telephony Interaction Magazine. http://blog.tmcnet.com/blog/tom-keating/docs/cti-buyers-guide-1996.pdf. Retrieved on 2007-11-07.

6. ^ "The 10 that Established VoIP (Part 1: VocalTec)". iLocus. http://www.ilocus.com/2007/07/the_10_that_established_voip_p_2.html. Retrieved on 2009-01-21.

7. ^ "H.323 Visual telephone systems and equipment for local area networks which provide a non-guaranteed quality of service". ITU-T. http://www.itu.int/rec/T-REC-H.323-199611-S/en. Retrieved on 2009-01-21.

8. ^ "RFC-2235". R. Zakon. http://www.faqs.org/rfcs/rfc2235.html. Retrieved on 2009-01-21.9. ^ "The 10 that Established VoIP (Part 2: Level 3)". iLocus. July 13, 2007.

http://www.ilocus.com/2007/07/the_10_that_established_voip_p_1.html. Retrieved on 2007-11-07.

10. ^ "RFC-2543, SIP: Session Initiation Protocol". Handley,Schulzrinne,Schooler,Rosenberg. http://www.ietf.org/rfc/rfc2543.txt. Retrieved on2009-01-21.

11. ^ "What is Asterisk". Asterisk.org. http://www.asterisk.org/about. Retrieved on 2009-01-21.

12. ^ "VoIP on the Verge". Telecommuncations Online. November 1, 2004. http://www.telecoms-mag.com/Americas/article.asp?HH_ID=AR_539. Retrieved on 2009-01-21.

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52. ^ Greenberg, Andy (May 15, 2008). [http://www.forbes.com/2008/05/15/wiretapping-voip-lichtblau-tech-security08-cx_ag_0515wiretap.html/ "The State Of Cybersecurity Wiretapping's Fuzzy Future"]. [9]. http://www.forbes.com/2008/05/15/wiretapping-voip-lichtblau-tech-security08-cx_ag_0515wiretap.html/. Retrieved on 2009-03-02.

53. ^ 47 C.F.R. pt. 9 (2007) 54. ^ See http://www.fcc.gov/voip/. 55. ^ Proenza, Francisco J.. "The Road to Broadband Development in Developing Countries

is through Competition Driven by Wireless and VoIP" (PDF). http://www.e-forall.org/pdf/Wireless&VoIP_10July2006.pdf. Retrieved on 2008-04-07.

56. ^ Stars and Stripes: USFK deal keeps VoIP access for troops

[edit] External links

Voice over Internet Protocol at the Open Directory Project

[hide] v • d • e

Computer-mediated communication

Online chat, Online discussion, Communication software, Collaborative software

Asynchronous conferencingE-mail • Electronic mailing list • Internet forum • Shoutbox •Wiki

Synchronous conferencing Data conferencing • Instant messaging • LAN messenger •

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Videoconferencing • Voice chat • VoIP • Talker • Web chat • Web conferencing

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