UMA enables dual-mode handsets

Enterprise mobility is a boon for productivity and flexibility in the workplace, but also represents a significant expense to the bottom lines of most organizations. For IT managers, the promise of mobile and Wi-Fi convergence looks to lower cellular costs while increasing the performance of mobile voice and data applications.

Unlicensed Mobile Access (UMA) brings cost and performance advantages to mobile services and offers four benefits: discounts for services delivered over the IP network, minimal impact to enterprise IT support staff or additional capital equipment, increased mobile performance, and seamless, high-quality in-building coverage.

UMA is the 3rd Generation Partnership Project (3GPP ) standard that specifies access to, and mobility of, mobile/Wi-Fi convergence. UMA enables mobile operators to deliver their existing services, whether based on circuit, packet, Session Initiation Protocol or IP Multimedia Subsystem (IMS), over unlicensed spectrum technologies, including Bluetooth and 802.11. Users will be able to roam between cellular networks and public and private unlicensed wireless networks using dual-mode mobile handsets. The UMA specification defines a new network element - the UMA Network Controller - as well as protocols that provide for the secure transport of GSM and General Packet Radio Service signals over IP. Known as TS 43.318 in the 3GPP standards body, the specification has been approved for inclusion into the upcoming 3GPP Release 6.

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Enterprise mobility is a boon for productivity and flexibility in the workplace, but also represents a significant expense to the bottom lines of most organizations. For IT managers, the promise of mobile and Wi-Fi convergence looks to lower cellular costs while increasing the performance of mobile voice and data applications.

Unlicensed Mobile Access (UMA) brings cost and performance advantages to mobile services and offers four benefits: discounts for services delivered over the IP network, minimal impact to enterprise IT support staff or additional capital equipment, increased mobile performance, and seamless, high-quality in-building coverage.

UMA is the 3rd Generation Partnership Project (3GPP ) standard that specifies access to, and mobility of, mobile/Wi-Fi convergence. UMA enables mobile operators to deliver their existing services, whether based on circuit, packet, Session Initiation Protocol or IP Multimedia Subsystem (IMS), over unlicensed spectrum technologies, including Bluetooth and 802.11. Users will be able to roam between cellular networks and public and private unlicensed wireless networks using dual-mode mobile handsets. The UMA specification defines a new network element - the UMA Network Controller - as well as protocols that provide for the secure transport of GSM and General Packet Radio Service signals over IP. Known as TS 43.318 in the 3GPP standards body, the specification has been approved for inclusion into the upcoming 3GPP Release 6.

As with all new mobile/Wi-Fi solutions, a new dual-mode handset equipped with a Wi-Fi radio is required to access the service. For initial use, the handset must be configured with the enterprise access keys (the Service Set Identifier, user name and security keys), which are then stored in a profile on the handset, along with a home or hot-spot profile or both. The dual-mode handset periodically looks for Wi-Fi access points to associate with; when there is a match and signal strength and parameters are met, the handset initiates the Wi-Fi attach procedure based on the profile.

After attaching to the enterprise Wi-Fi network, the UMA client establishes an IPSec tunnel to the mobile operator, which requires an outbound IPSec tunnel through the enterprise's firewall or security system. The mobile handset and mobile operator then exchange keys and identity credentials. When authorized, a valid UMA session is established.

If the subscriber is in a current voice or data session, a UMA network controller in the mobile network will seamlessly hand off the session from the GSM network to the enterprise Wi-Fi network. This process is based on the same technology used to hand off sessions between radio towers in a mobile network when a subscriber is on the road.

With UMA, the handset client is constantly monitoring signal strength and is prepared to hand over to a different Wi-Fi access point within the enterprise, or to the GSM network if needed. With UMA, subscribers receive a consistent user experience for their mobile voice, data and IMS services as they transition between networks.