Email Delivery

Receive new posts as email.

Email address

Syndicate this site

RSS | Atom


About This Site
Contact Us
Privacy Policy


November 2010
Sun Mon Tues Wed Thurs Fri Sat
  1 2 3 4 5 6
7 8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30        

Stories by Category

Basics :: Basics
Casting :: Casting Listen In Podcasts Videocasts
Culture :: Culture Hacking
Deals :: Deals
Future :: Future
Hardware :: Hardware Adapters Appliances Chips Consumer Electronics Gaming Home Entertainment Music Photography Video Gadgets Mesh Monitoring and Testing PDAs Phones Smartphones
Industry :: Industry Conferences Financial Free Health Legal Research Vendor analysis
International :: International
Media :: Media Locally cached Streaming
Metro-Scale Networks :: Metro-Scale Networks Community Networking Municipal
Network Types :: Network Types Broadband Wireless Cellular 2.5G and 3G 4G Power Line Satellite
News :: News Mainstream Media
Politics :: Politics Regulation Sock Puppets
Schedules :: Schedules
Security :: Security 802.1X
Site Specific :: Site Specific Administrative Detail April Fool's Blogging Book review Cluelessness Guest Commentary History Humor Self-Promotion Unique Wee-Fi Who's Hot Today?
Software :: Software Open Source
Spectrum :: Spectrum 60 GHz
Standards :: Standards 802.11a 802.11ac 802.11ad 802.11e 802.11g 802.11n 802.20 Bluetooth MIMO UWB WiGig WiMAX ZigBee
Transportation and Lodging :: Transportation and Lodging Air Travel Aquatic Commuting Hotels Rails
Unclassified :: Unclassified
Vertical Markets :: Vertical Markets Academia Enterprise WLAN Switches Home Hot Spot Aggregators Hot Spot Advertising Road Warrior Roaming Libraries Location Medical Public Safety Residential Rural SOHO Small-Medium Sized Business Universities Utilities wISP
Voice :: Voice


November 2010 | October 2010 | September 2010 | August 2010 | July 2010 | June 2010 | May 2010 | April 2010 | March 2010 | February 2010 | January 2010 | December 2009 | November 2009 | October 2009 | September 2009 | August 2009 | July 2009 | June 2009 | May 2009 | April 2009 | March 2009 | February 2009 | January 2009 | December 2008 | November 2008 | October 2008 | September 2008 | August 2008 | July 2008 | June 2008 | May 2008 | April 2008 | March 2008 | February 2008 | January 2008 | December 2007 | November 2007 | October 2007 | September 2007 | August 2007 | July 2007 | June 2007 | May 2007 | April 2007 | March 2007 | February 2007 | January 2007 | December 2006 | November 2006 | October 2006 | September 2006 | August 2006 | July 2006 | June 2006 | May 2006 | April 2006 | March 2006 | February 2006 | January 2006 | December 2005 | November 2005 | October 2005 | September 2005 | August 2005 | July 2005 | June 2005 | May 2005 | April 2005 | March 2005 | February 2005 | January 2005 | December 2004 | November 2004 | October 2004 | September 2004 | August 2004 | July 2004 | June 2004 | May 2004 | April 2004 | March 2004 | February 2004 | January 2004 | December 2003 | November 2003 | October 2003 | September 2003 | August 2003 | July 2003 | June 2003 | May 2003 | April 2003 | March 2003 | February 2003 | January 2003 | December 2002 | November 2002 | October 2002 | September 2002 | August 2002 | July 2002 | June 2002 | May 2002 | April 2002 | March 2002 | February 2002 | January 2002 | December 2001 | November 2001 | October 2001 | September 2001 | August 2001 | July 2001 | June 2001 | May 2001 | April 2001 |

Recent Entries

In-Flight Wi-Fi and In-Flight Bombs
Can WPA Protect against Firesheep on Same Network?
Southwest Sets In-Flight Wi-Fi at $5
Eye-Fi Adds a View for Web Access
Firesheep Makes Sidejacking Easy
Wi-Fi Direct Certification Starts
Decaf on the Starbucks Digital Network
Google Did Snag Passwords
WiMax and LTE Not Technically 4G by ITU Standards
AT&T Wi-Fi Connections Keep High Growth with Free Service

Site Philosophy

This site operates as an independent editorial operation. Advertising, sponsorships, and other non-editorial materials represent the opinions and messages of their respective origins, and not of the site operator. Part of the FM Tech advertising network.


Entire site and all contents except otherwise noted © Copyright 2001-2010 by Glenn Fleishman. Some images ©2006 Jupiterimages Corporation. All rights reserved. Please contact us for reprint rights. Linking is, of course, free and encouraged.

Powered by
Movable Type

« World's Largest Commercial Building Becomes Hotspot | Main | Detecting, Inspecting, Correcting »

February 11, 2005

Unlicensed Mobile Access on Verge of Deploying

Diagram Architect BigMonica Paolini of Senza Fili explains a technology you've never heard of that will soon be everywhere: Monica, a fellow Seattle-area resident, has written a long and expensive piece of analysis about UMA (Unlicensed Mobile Access), which is a way to use unlicensed Wi-Fi and Bluetooth spectrum to carry voice through a gateway to the existing GSM networks. GSM operators can then leverage their huge investment and better serve existing and new customers with better pricing and service.

I asked Monica if she could extract a high-level overview of UMA for Wi-Fi Networking News, and she obliged. Her full report, intended primarily for decision-makers and analysts involved with GSM networks, is available at her Senza Fili site. (And for those of you who speak Italian, Senza Fili means Without Wires.)

Monica writes:

The UMA (Unlicensed Mobile Access) Consortium was formed by GSM mobile operators with the aim of creating specifications for WCC that would eventually become standards-based and that would interface well with their core networks. Manufacturers have also joined to create an impressive, if restricted, group that includes Alcatel, British Telecom, Cingular, Ericsson, Kineto Wireless, Motorola, Nokia, Nortel Networks, O2, Rogers Wireless, Siemens, Sony Ericsson and T-Mobile USA.

The specifications were published in September 2004 as guidelines for mobile operators and handset manufacturers, and as a blueprint for a future 3GPP standard. They are available at They are clearly designed by and for mobile operators, to allow them to control both cellular and Wi-Fi traffic, and to integrate Wi-Fi voice services seamlessly with their GSM networks. With a Wi-Fi cellular phone, subscribers are able to switch freely from the cellular network they use when away from home, to Wi-Fi when they enter their home network coverage, and vice versa.

UMA enables GSM/GPRS handsets equipped with Wi-Fi or Bluetooth to access the GSM and General Packet Radio Service GPRS core networks using the unlicensed air interface when available (see figure from the UMA Consortium at above right). As such, UMA represents an extension of the GSM/GPRS network for mobile operators, which can support voice services in homes, offices and hotspots both through the cellular and the WLAN networks. Subscribers using UMA can take advantage of improved indoor coverage and higher data rates, when accessing the local WLAN.

(More after the jump.)

Unlike other convergence solutions, UMA is tightly linked to the mobile core network, which is used for routing, authentication and billing. Regardless of the air interface used, the handset or mobile station (MS) is connected to a 2G or 3G core network. A call initiated using the Wi-Fi interface reaches the 2G core network through the UMA Network (UMAN).

It is important to keep in mind that UMA is not a SIP-based VoIP technology, as the core network is still old-fashioned, circuit-switched GSM. VoIP is employed to carry the signal from the MS to the UNC, over the WLAN and the broadband connection, but once transferred to the core GSM network it is indistinguishable from the rest of the cellular traffic.

The MS accesses the UMA network through a Wi-Fi Access Point (AP) and an IP broadband connection. While the AP and the broadband connections are necessary, the UMA specifications do not mandate their particular requirements. The WLAN infrastructure and broadband connection have to be managed by the user (or the mobile operator, if it so decides). Any Wi-Fi AP and broadband connection are expected to work in an UMA environment. However, performance may be impacted when using APs or broadband connections that lack QoS functionality.

The UMA Network Controller (UNC) provides the interface to the cellular core network. The UNC performs the same function as the GERAN base station and, at the core level, traffic from the two systems (GERAN and UMAN) is treated equally. UMA specifications recommend that the UNC is able to route calls through the 3G core network as well.

UMA promises seamless mobility between the WLAN and the cellular network. A call initiated within the cellular network can be transferred to a WLAN network and vice versa as the subscriber moves to areas with or without WLAN coverage. During the handoff, the MS needs to be able to maintain a connection with both networks, as it is a make-before-break connection. As a result, the subscriber will not notice delays or other changes in the quality of the call.

Different security mechanism operate at different levels:

  • MS to AP – UMA does not mandate any security mechanism, but can coexist with those available, such WPA, WPA2, or WEP.
  • MS to UNC – The UNC includes a security gateway that provides mutual authentication and encryption for the traffic across the WLAN and the broadband connection.
  • MS to core mobile network – The encryption and authentication methods used by the MS when using the GERAN are also used to protect UMA connections.
  • MS to application server – An additional end-to-end data application mechanism (for example, HTTPS) may be used if needed.

UMA will be relatively simple and inexpensive to deploy at the core network level, as no substantial changes are required. The UNCs (and links to the core network) are the only key new infrastructure elements that need to be introduced into the access network.

In its basic form—that is without QoS mechanisms in the WLAN—UMA does not require any change to the WLAN network either. Any AP is expected to work with UMA, although we expect that mobile operators will encourage APs that support QoS. This is because the throughput available in the WLAN and in the broadband connection should make it provide toll voice quality if no other application contends for the same bandwidth. If there is contention, however, UMA cannot guarantee the quality of a voice call or the throughput of a data connection and traffic prioritization with QoS can significantly improve performance, especially in a residential environment where traffic is likely to be less heavy than in the enterprise.

The most expensive and technologically challenging component of UMA solution is the Wi-Fi and cellular handset, because of battery-life limitations, cost, and size. To be UMA-enabled, a Wi-Fi and cellular phone requires client software to communicate with the UNC. While it may be possible to load the UMA software in any Wi-Fi and cellular phone, mobile operators are currently working on, and are more likely to market, handsets developed specifically for UMA access. Any UMA-enabled MS includes a Wi-Fi radio, which will give it access to any IP network and VoIP services (such as those from Skype or Vonage for instance). However mobile operators may decide to block this functionality, especially if they decide to subsidize the phones.