25-07-2014, 11:16 AM
GENERIC ACCESS NETWORK
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ABSTRACT
Generic Access Network (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.
This report will attempt to discuss the details of the GAN, its evolution, its services,
architecture, and other implications.
INTRODUCTION
The Generic Access Network (GAN) is an evolving wireless communications system in
which mobile phone sets function seamlessly between local area networks (LANs) and
wide-area networks (WANs). Using GAN technology, a cell phone subscriber can
communicate by voice, data and multimedia. As GAN technology is implemented,
cellular telephone subscribers can expect improved coverage, the ability to use a single
phone set for all their voice communications and perhaps cheaper rates with a single bill
for Internet and voice communications.
THEORETICAL DESCRIPTION
With dual-mode services(GSM and Wi-fi), subscribers make calls from outside the home
as they would ordinarily, using the GSM radio network at the standard tariff rate. But
inside the home, the call travels over the subscriber’s wireless broadband connection,
so the operator can enjoy a similar economic structure as VoIP-over-broadband
provider.
Standard Wi-Fi access point
A standard Wi-Fi access point (or hotspot) is used to provide Wi-Fi access
to a dual-mode handset. This Wi-Fi access point may be enhanced with
specific Quality of Service (QoS) and security mechanisms, such
as rate-limiting for uplink traffic, Call Admission Control to
limit the number of dual-mode handsets that may associate with it,
802.1x encryption, etc.
GAN/UMA BEYOND THE 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.
SIMILAR TECHNOLOGY
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. 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.
CONCLUSION
GAN dual-mode services to the home give mobile operators the opportunity for a
significant competitive advantage by accelerating fixed-mobile substitution, increasing
penetration, and reducing turnover. The GAN architecture provides an essential
prerequisite for dual-mode services—protecting the mobile operator’s voice network
from threats originating from the Internet. Because the security infrastructure that is
used to offer dual-mode services can be reused for other services, including IMS, the
investment in the GAN solution provides a competitive advantage for tomorrow’s
service as well as today’s.