Generic Access Network

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Unlicensed Mobile Access or UMA, is the commercial name of the 3GPP Generic Access Network, or GAN standard. GAN is a telecommunication system which extends mobile services voice, data and IP Multimedia Subsystem/Session Initiation Protocol (IMS/SIP) applications over IP access networks.

The most common application of GAN is in a dual-mode handset service where subscribers can seamlessly roam and handover between local area networks and wide area networks using a GSM/Wi-Fi dual-mode mobile phone. GAN enables the convergence of mobile, fixed and Internet telephony, sometimes called Fixed Mobile Convergence.

The local network may be based on private unlicensed spectrum technologies like 802.11, while the wide network is alternatively GSM/GPRS or UMTS mobile services. On the cellular network, the mobile handset communicates over the air with a base station, through a base station controller, to servers in the core network of the carrier. Under the GAN system, when the handset detects a LAN, it establishes a secure IP connection through a gateway to a server called a GAN Controller (GANC) on the carrier's network. The GANC translates the signals coming from the handset to make it appear to be coming from another base station. Thus, when a mobile moves from a GSM to an 802.11 network, it appears to the core network as if it is simply on a different base station.

The system was initially called UMA and then renamed to GAN. It was developed by a group of operator and vendor companies. The initial specifications were published on 2nd September 2004. The companies then contributed the specifications to the 3rd Generation Partnership Project (3GPP) as part of 3GPP work item "Generic Access to A/Gb interfaces". On 8th April 2005, 3GPP approved specifications for Generic Access to A/Gb interfaces for 3GPP Release 6. TS 43.318 and TS 44.318, and renamed the system to GAN. But the term GAN is little known outside the 3GPP community, and the term UMA is more common in marketing.

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[edit] Modes of operation

The original Release 6 GAN specification supported a 2G (A/Gb) connection from the GANC into the mobile core network (MSC/GSN). Today all commercial GAN dual-mode handset deployments are based on a 2G connection and all GAN enabled device are dual-mode 2G/Wi-Fi.

However, the specification defined support for multimode handset operation. Therefore 2G/3G/Wi-Fi are supported in the standard. The second half of 2008 will bring the first of these devices to market.

A typical UMA/GAN handset will have four modes of operation:

  • GERAN-only: uses only cellular networks
  • GERAN-preferred: uses cellular networks if available, otherwise the 802.11 radio
  • GAN-preferred: uses a 802.11 connection if an access point is in range, otherwise the cellular network
  • GAN-only: uses only the 802.11 connection

In all cases, the handset scans for GSM cells when it first turns on, to determine its location area. This allows the carrier to route the call to the nearest GANC, set the correct rate plan, and comply with existing roaming agreements.

At the end of 2007, the GAN specification was enhanced to support 3G (Iu) interfaces from the GANC to the mobile core network (MSC/GSN). This native 3G interface can be used for dual-mode handset as well as 3G femtocell service delivery. The new capabilities are documented in the GAN release 8 documents.

[edit] Advantages

For carriers:

  • Instead of erecting expensive base stations to cover every nook and cranny of a neighbourhood, GAN allows carriers to add coverage using low cost 802.11 access points. When at home, subscribers have very good coverage.
  • In addition, GAN relieves congestion on the GSM or UMTS spectrum by removing common types of calls and routing them to the operator via the relatively low cost Internet
  • GAN makes sense for network operators that also offer internet services. Operators can leverage sales of one to promote the other, and can bill both to each customer.
  • Some other operators also run networks of 802.11 hotspots, such as T-Mobile. They will be able to leverage these hotspots to create more capacity and better coverage in many populous areas.
  • Subscribers, not the network, pay directly for much of the costs associated with the service. They pay for a connection to the Internet, effectively paying the expensive part of the cost of routing calls from their location.

For subscribers:

  • Subscribers do not rely on their operator's ability to roll out towers and coverage, allowing them to fix some types of coverage blackspot themselves (such as in the home or office.)
  • The cheaper rates for 802.11 use, coupled with better coverage at home, make it more affordable and practical to use cellphones instead of land lines.
  • GAN is currently the only commercial technology available that combines GSM and 802.11 into a service that uses a single number, a single handset, single set of services and a single phone directory for all calls.

[edit] Disadvantages

  • Handsets must support 802.11 network access which requires additional space, power and complexity and may affect the size, weight and battery performance of the phone.
  • Increasingly, consumers take advantage of unlimited or otherwise high-volume data tariffs to make VoIP calls via SIP, as with Skype. GAN will mean that this type of usage is more likely to be charged on a per-minute or unit basis as with voice calls, which may increase the cost of mobile calls made over IP.

[edit] Service deployments

The first service launch was BT with BT Fusion in the autumn of 2005. The service is based on technology which is pre-3GPP GAN standard. Initially, BT Fusion used UMA over Bluetooth with phones from Motorola; since Jan 2007, it uses UMA over 802.11 with phones from Nokia, Motorola and Samsung and is branded as a "Wi-Fi mobile service".

On August 28, 2006, TeliaSonera was the first to launch a 802.11 based UMA service called “Home Free”. The service started in Denmark and has expanded to Sweden and Norway.

On September 25, 2006 Orange announced its “unik” service ( “unique ” in the UK). The announcement, the largest to date, covers more than 60m of Orange’s mobile subscribers in the UK, France, Poland, Spain and the Netherlands.

On June 6th 2007 Finnish virtual operator Saunalahti announced plans to publish UMA services on week 24 with the Nokia 6136 UMA phone. Announcement in finnish

The first UMA deployment in the United States was announced by Cincinnati Bell on June 18, 2007. The service called CB Home Run allows users to seamlessly transfer from the Cincinnati Bell cellular network to a home wireless network or Cincinnati Bell's WiFi HotSpots.

This was followed shortly by T-Mobile on June 27, 2007. T-Mobile's service, called T-Mobile HotSpot@Home, allows users to seamlessly transfer from the T-Mobile cellular network to a home wireless network or T-Mobile HotSpot.

In the middle of 2007, Spanish operator Ono launched a UMA service called Oi.

In Canada, both Fido and Rogers Wireless have launched UMA plans under the names UNO and Rogers Home Calling Zone, respectively. Current devices are the Nokia 6301 from Fido and the Nokia 6086 from Rogers Wireless. This service was announced on May 6, 2008.

[edit] UMA/GAN Beyond Dual-mode

While UMA is nearly always associated with dual-mode GSM/Wi-Fi services, it is actually a ‘generic’ access network technology. It provides a generic method for extending the services and applications in an operator’s mobile core (voice, data, IMS) over IP and the public internet.

GAN defines a secure, managed connection from the mobile core (GANC) to different devices/access points over IP.

Femtocells - The GAN standard is currently used to provide a secure, managed, standardized interface from a femtocell to the mobile core network. Recently Kineto, NEC and Motorola issued a joint proposal to the 3GPP work group studying femtocells (also known as ‘home node b’s or HNB) to propose GAN as the basis for that standard.

Analog Terminal Adaptor – Recently T-Mobile announced a commercial trial of a fixed line VoIP service. Similar to Vonage, consumers can port their fixed phone number to T-Mobile, then T-Mobile associates that number with an ATA (analog terminal adaptor). The consumer plugs the ATA into their home broadband network and begins receiving calls to the fixed number over the IP access network.

Linksys developed a UMA-enabled ATA specifically for this application. For T-Mobile, this is a way to offer fixed line services from their mobile core network.

For consumers, the price of the service is $10/month for subscribers with a T-Mobile plan of $40 or more. Note this is completely independent of T-Mobile's dual-mode service. It is available to any T-Mobile subscriber in the US.

Softmobile - Consumers have started to use telephony interfaces on their PCs. Applications like Skype offer a low cost, convenient way to access telephony services while traveling. Now mobile operators can offer a similar service with a UMA-enabled softmobile client. Developed by Vitendo, the client provides a mirror interface to a subscriber’s existing mobile service. For the mobile operator, services can now be extended to a PC/laptop, and they can give consumers another way to use their mobile service.

[edit] Similar technologies

GAN/UMA is not the first system to allow the use of unlicensed spectrum to connect handsets to a GSM network. The GIP/IWP standard for DECT provides similar functionality, but requires a more direct connection to the GSM network from the base station. While dual-mode DECT/GSM phones have appeared, these have generally been functionally cordless phones with a GSM handset built-in (or vice versa, depending on your point of view), rather than phones implementing DECT/GIP, due to the lack of suitable infrastructure to hook DECT base-stations supporting GIP to GSM networks on an ad-hoc basis.[1]

GAN/UMA's ability to use the Internet to provide the "last mile" connection to the GSM network solves the major issue that DECT/GIP has faced. Had GIP emerged as a practical standard, the low power usage of DECT technology when idle would have been an advantage compared to GAN.

There is nothing preventing an operator from deploying micro- and pico-cells that use towers that connect with the home network over the Internet. Several companies have developed so-called Femtocell systems that do precisely that, broadcasting a "real" GSM or UMTS signal, bypassing the need for special handsets that require 802.11 technology. In theory, such systems are more universal, and again require lower power than 802.11, but their legality will vary depending on the jurisdiction, and will require the cooperation of the operator.

[edit] Devices

[edit] References

  1. ^ DECT Web DECT/GSM DUAL MODE and the advent of the ONEPHONE SERVICE
  2. ^ BenQ Global - Communications
  3. ^ Boutique mobile
  4. ^ [1][dead link]
  5. ^ Samsung t409 phone details from T-Mobile
  6. ^ UMA Today : Products : UMA Devices : Dual-Mode Handsets : Samsung P260
  7. ^ The Samsung SGH-P520 Prada Phone - SlashPhone.com
  8. ^ The Samsung Katalyst: T-Mobile's next @Home handset? - Engadget Mobile
  9. ^ T-Mobile BlackBerry Curve - Pale Gold phone details from T-Mobile
  10. ^ FCC Leaks WiFi/UMA Enabled BlackBerry Pearl 8120 (MobileBurn)
  11. ^ http://www.umatoday.com/mobileHandsetsHPiPAQ510.php

[edit] See also

[edit] External links