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Unlicensed Mobile Access – A Revival

Last week saw some significant wins for champions of ‘free’ usage of spectrum – first is the approval of TV whitespaces spectrum by FCC and the second is the software based solution by Kineto for using UMA as an app in the Android phones. Two entirely different but high impact propositions for the free airwave users, both of them spur developments in their respective ecosystems that will have long-term impacts. I have blogged on the advantages of both these technologies extensively in the past few months. UMA (Unlicensed Mobile Access) uses the Wi-Fi bands for extension of coverage indoors, and T-Mobile USA has been the only Tier I operator who uses this technology in Northern America.

I have extensively spoken about whitespaces in the last few weeks leading upto the voting on September 23rd, please see my older posts here and here. But the topic that has captured my attention was the event that happened around UMA, a technology that is very robust but has had relatively low success rate – UMA or GAN. It is one technology that could have been the end of Vonage if T-Mobile had followed through with the strategy of ‘at home’ products. It was a simple IP telephony that brought true convergence to cellular networks and the home Wi-Fi, even though it supported only 802.11g standards.

UMA in the News

Kineto Wireless, Inc., the key innovator and leading supplier of solutions that enable delivery of mobile services over broadband, today announced it has an updated version of its Smart Wi-Fi Application for Google’s Android operating system version 2.2, also called Froyo.

Kineto’s Smart Wi-Fi Application, based on the 3GPP UMA/GAN standard, turns existing Wi-Fi access points into seamless extensions of the mobile network. Using the Smart Wi-Fi application, subscribers can now resolve indoor mobile coverage problems by receiving their voice and data services over existing Wi-Fi access points.

“Smartphone’s have highlighted the coverage and capacity challenges of mobile networks, especially in indoor locations. Operators have started to look to Wi-Fi, already installed in many homes and offices, to address these issues,” said Mark Powell, vice president and general manager of Kineto’s Client Business Unit and co-founder of the company. “To capitalize on this growing demand, we have now enhanced our Smart Wi-Fi Application to support the latest version of Android and validated it with the leading Android smartphone manufacturers.”

Kineto’s Smart Wi-Fi Application is designed for mobile operators to address the network coverage and capacity issues created by the growing popularity of smartphones and subscriber demand for bandwidth intensive applications and services. The company works with device manufacturers and mobile operators to pre-load the application onto devices.

Wi-Fi continues to be the predominant wireless technology in the home. A study conducted by Arbitron earlier this year found that 62 percent of US broadband-connected households already had Wi-Fi installed. Market research firm In-Stat projects that by 2013, shipments of mobile phones with embedded Wi-Fi will exceed ¾ of a billion units. Kineto’s Smart Wi-Fi Application enables mobile operators to extract the maximum benefit of Wi-Fi for their networks and their subscribers.

For more information about Kineto’s Smart Wi-Fi Application, please visit our website http://www.kineto.com. For a short video of Smart Wi-Fi in action, visit Kineto’s YouTube channel at www.youtube.com/kinetowireless.

T-Mobile USA may soon add a Wi-Fi calling application to certain Android phones in its lineup, according to the blog TMoNews.

According to the blog, which posted what it said were images of a training session for T-Mobile employees, the carrier is going to bring Unlicensed Mobile Access calling technology to certain smartphones running Google’s mobile platform via a pre-loaded Wi-Fi calling app. However–unlike the carrier’s current Wi-Fi calling services–there will be no handoff between Wi-Fi and the company’s cellular network, meaning that once a user leaves a Wi-Fi hotspot, their call will drop. Additionally, the blog post said, the app will not be available on all of T-Mobile’s Android phones.

A T-Mobile spokeswoman declined to comment on the report. The carrier supports UMA calling for Research In Motion’s BlackBerry devices and the Nokia E73. A T-Mobile spokeswoman told FierceWireless earlier this month that the carrier has not made any announcements regarding future plans for UMA.T-Mobile first introduced unlimited Wi-Fi calling for consumers with the launch of its Hotspot@Home service in 2007. The offering allows users to switch between Wi-Fi and the carrier’s cellular network. T-Mobile announced in April that it logs 1.6 million Wi-Fi calls per month.

How does UMA work?

Unlicensed Mobile Access (UMA) is a technology that enables mobile subscribers to access GSM and GPRS networks over unlicensed spectrum technologies (such as 802.11 or Bluetooth). The UMA Network (UMAN) utilizes Wi-Fi (802.11) at the customer’s premises as radio access into the GSM/GPRS network instead of the traditional BSS radio network.

Highlights of UMA Technology:

  • Seamless delivery of mobile voice and data services over unlicensed wireless networks.
  • Seamless transitions (roaming and handover) between Cellular RAN and unlicensed wireless networks.
  • Preserves investment in existing/future mobile core network infrastructure

UMA is transparent to existing, standard network devices (e.g. access points, routers and modems).Security equivalent to current GSM mobile networks. No impact to operations of Cellular RAN (e.g.  Spectrum, cell planning, etc). This is an IP based network running over ATM and a TDM  carrying SS7 respectively.

A mobile subscriber with a UMA-enabled, dual-mode handset moves within range of an unlicensed wireless network to which the handset is allowed to connect.

Upon connecting, the handset contacts the UMA Network Controller (UNC) over the broadband IP access network to be authenticated and authorized to access GSM voice and GPRS data services via the unlicensed wireless network.

If approved, the subscriber’s current location information stored in the core network is updated, and from that point on all mobile voice and data traffic is routed to the handset via the Unlicensed Mobile Access Network (UMAN) rather than the cellular radio access network (RAN).

ROAMING: When a UMA-enabled subscriber moves outside the range of an unlicensed wireless network to which they are connected, the UNC and handset facilitate roaming back to the licensed outdoor network. This roaming process is completely transparent to the subscriber.

HANDOVER: If a subscriber is on an active GSM voice call or GPRS data session when they come within range (or out of range) of an unlicensed wireless network, that voice call or data session can automatically handover between access networks with no discernable service interruption. Handovers are completely transparent to the subscriber.


For carriers:

  • Instead of erecting expensive base stations to cover dead zones, GAN allows carriers to add coverage using low cost 802.11 access points. Subscribers at home 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 can leverage these hotspots to create more capacity and provide better coverage in populous areas.
  • Subscribers, not the network, pay directly for much of the service. They pay for a connection to the Internet, effectively paying the expensive part 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 dead zones (such as in the home or office) themselves.
  • The cheaper rates for 802.11 use, coupled with better coverage at home, make more affordable and practical the use of cell phones instead of land lines.
  • Using IP over 802.11 eliminates expensive charges when roaming outside of a carrier’s network.
  • 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, a single set of services and a single phone directory for all calls.
  • GAN can migrate between IP and cellular coverage and is thus seamless; in contrast, calls via third-party VOIP plus a data phone are dropped when leaving high-volume data coverage.

Devices and Networks

Some of the smartphones that support UMA are from Blackberry as well as Nokia. Phones will need UMA software stack to be built in along with Wi-Fi capable radios, as UMA-enabled dual-mode handsets enable mobile subscribers to automatically and seamlessly roam and handover between cellular networks and public and private Wi-Fi networks. With UMA-enabled dual-mode handsets, subscribers receive a consistent user experience for their mobile voice, data and IMS services as they transition between networks.

A UMA solution relies on a centralized controller deployed in the mobile Core Network.  This controller is known as the “GAN-Controller” or GAN-C and is based upon the 3GPP GAN specification.

The GAN-C or the UNC (UMA Network Controller) abstracts the mobile core network from the broadband IP network.  It aggregates the Smart Wi-Fi connections into the mobile core, and provides a secure interface for subscribers to access mobile voice, data and IMS services.

Functionally the UNC appears to the Core Network as if it were an RNC or BSC in a standard 3GPP radio access network.  The UNC manages the following functions:

  • Smartphone session management
  • Smartphone registration/deregistration
  • Circuit service (CS) and packet service (PS) control
  • Individual smartphone session mapping into the correct core network identifiers (e.g. Location Area, Cell ID, Service Area, Routing Area)

Between the smartphone and the UNC is the Up interface.  Due to the nature of the public Internet, Up sessions are encoded in a VPN tunnel.  The UNC contains a security gateway function which terminates the VPN tunnels.  The security gateway relies on the AAA server to enable a (U)SIM-based authentication process between the smartphone and the HLR.  This authentication process is used to establish and configure the VPN between the smartphone and the UNC.

Operators have the option to use the AAA server as an additional business/policy logic server to provide enhanced access controls, location determination and other features. The former function is part of the access network security infrastructure, and the latter is supported over a well-defined RADIUS interface from the UNC.

Operator Deployments

Sources: http://www.umatechnology.org ; http://www.smart-wi-fi.com

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