UMA / GAN Tutorial
An overview or tutorial about the basics of UMA - Unlicensed Mobile Access
and GAN - Generic Access Network providing fixed-mobile convergence between
cellular and unlicensed spectrum technologies such as 802.11 Wi-Fi and
Bluetooth.
UMA or Unlicensed Mobile Access, along with GAN or Generic
Access Network are a new technology that will probably become one of the major
drivers in cellular mobile communications. The new technology allows convergence
between mobile and fixed line communications systems, providing the possibility
for users to have just one number and one phone for the telecommunications
requirements.
UMA / GAN promises to offer new opportunities to users,
mobile operators and manufacturers alike. Thus UMA could be one of the major
drivers for the mobile telecommunications industry in the near future providing
revenue from new sources as well as providing an upgrade path for existing
users.
Drivers for UMA fixed-mobile convergence
The level of mobile use has grown rapidly around the globe.
Particularly in western countries where users have access to both fixed and
mobile services there has been a growing desire to use just one phone for all
their services. With access to wireless connectivity rising from the increased
use of DSL lines to the home as well as wireless coverage in work place and in
wi-fi hotspots there is the possibility of using a variety of short range
wireless connectivity, and chiefly 802.11.
An additional factor is that IMS and VoIP services are now
becoming far more widespread and this raises the possibility of using a single
user interface and connecting the phone either over the cellular network, or by
using wireless connectivity through Wi-fi access points - the system choosing
the optimum service.
With users providing a definite push to generate the
technology for this fixed-mobile convergence, UMA is bound to be a growing
technology.
UMA and GAN
There are two terms associated with the convergence
technology namely UMA - unlicensed mobile access and GAN - generic access
network. Both are virtually the same, and indeed the phones that are being
marketed are being described as UMA phones.
UMA was the first term to be used. The UMA Industry Forum was
founded by a dozen leading cellular companies. However to ensure that there was
standardisation - a key element required for the success of UMA, the work was
introduced into 3GPP under the GSM EDGE Radio Access Network (GERAN) group. The
standard was ratified in April 2006 as TS43.318 release 6 and this included the
term GAN - Generic Access Network.
Although GAN is the term that is used within GERAN to
describe the technology, it is not seen as much outside the 3GPP environs.
Instead the term UMA has been used for much of the marketing of these products.
However in essence both terms, GAN and UMA can be used to describe the
technology.
Introducing UMA / GAN to a network
The introduction of UMA / GAN by a network operator is
relatively low cost and straightforward. While GSM and UMTS require relatively
expensive and complicated backhaul circuits as well as costly base stations, the
addition of UMA only requires the users to additionally utilise their existing
broadband connections.
This means that the network operator only needs to introduce
one major element to the network. This is the UMA Network Controller or UNC.
This can be considered as being much like a Base Station Controller (BSC) but
for the UMA functionality. One side of the UNC is connected to the Internet
giving connectivity for the WLAN access points, and the other side of the UNC
uses a standard A interface for the circuit-switched communications through to
the mobile services switching centre (MSC) and a Gb interface for the packet
switched connectivity through to the serving GPRS support node (SGSN).
Although UMA and GAN are effectively the same, in GAN
parlance slightly different terms are used. GAN refers to the UNC as the GAN
Controller (GANC).
By using the UNC or GANC, it means that when a device hands
over from a GSM to a WLAN, it appears to the core network as just a different
base station.
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