Unlicensed Mobile Access (UMA) Explained

What is UMA?

Taking a call
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UMA stands for Unlicensed Mobile Access. It is a wireless technology that allows seamless transition between wireless WANS (e.g. GSM, 3G, EDGE, GPRS, etc.) and wireless LAN (e.g. Wi-Fi, Bluetooth). This means that a user can initiate a call over GSM, for example, and the calls switches from the GSM network to the office’s Wi-Fi network once the user walks into range. And vice-versa. UMA is one of the ways to FMC (fixed mobile convergence).

This can imply many things, given that unlicensed Wi-Fi and Bluetooth networks are free while wide-area networks tend to be quite expensive. You could theoretically save money this way. UMA technology isn’t commercially mature enough, and maybe technologically so, to allow this, but it is good to have it in the picture, as it is becoming more and more common.

How UMA Works

UMA is in fact a commercial name, its technical name being GAN (Generic Access Network).

When a handset already in communication through a wireless WAN enters the area of a wireless LAN network, it presents itself to the WAN’s GAN controller as being on a different base station of the WAN and shifts to the wireless LAN network. In a word, the unlicensed LAN is presented as a pseudo part of the licensed WAN, and thus the transition is smoothly allowed. Once the user moves out the range of the unlicensed wireless LAN, the connection is roamed back to the wireless WAN.

This whole process is completely transparent to the user. Transparency here means (as it curiously does with networks) that the user does not know (or need to know) the hassle of the handing over. It just happens seamlessly without the user noticing.

How Can Users Benefit From UMA?

  • Users can use their mobile handsets in many places and networks, but still have one single number. .
  • Users can set up their wireless LANs themselves, thereby solving the problem caused by holes in coverage of the provider’s network. .
  • Roaming charges outside the mobile service provider’s network are eliminated since calls can be initiated within free unlicensed wireless LANs. .
  • Mobile communication becomes more reliable and cheap – this may allow users to replace the expensive PSTN phone services.

How Can Providers Benefit From UMA?

  • Carriers can set up Wi-Fi hotspots in network coverage holes, instead of investing on expensive wireless WAN hardware. .
  • Congestion on GSM and other wireless WAN networks are relieved with part of the traffic toggled to unlicensed wireless LANs .
  • Networks like Wi-Fi are better off for carrying other types of media apart from voice, instead of traditional GSM. Thus, providers can design communication packages that include more than voice. This is especially interesting for Internet service providers. .
  • UMA operates at the IP network layer in the protocol stack and is therefore open to many protocols in the interface layer - put simply, it is not restricted to one network, but can work on Wi-Fi, Bluetooth etc. .

Disadvantages of UMA

  • Handsets have to be UMA-compatible. These are rare and quite expensive. This is a problem both for providers and subscribers. .
  • While UMA providers mobility, it cannot provide free or very cheap calling as SIP-based services and services like Skype. As a result, cost cutting might not be convincing in many cases. .

UMA Requirements

To use UMA, you only need a wireless network plan, a wireless LAN – you can have your own at home or can avail of the many existing hotspots in public places - , and a mobile handset that supports UMA. The last one makes the technology still remote, as the amount of UMA compatible handsets isn’t big. Some Wi-Fi and 3G phones just won’t work here.

Some examples are UMA phones are BlackBerry Curve 8900, Pearl 8120 and some others, Nokia 6301, Nokia 6086, Samsung T409, T739 and a bunch of others, some LG and Sony Ericsson phones.

BlackBerry seems to have taken the path of leveraging over UMA’s possibilities to enforce its leading position on the smartphone market, especially with its partnership with T-Mobile, the first carrier in the US to offer a UMA plan.

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