U.S. mobile operators have had something of a love-hate relationship with Wi-Fi in recent years. AT&T Mobility, Sprint and T-Mobile US were all owners of public Wi-Fi hot spots at one time, but today only AT&T operates a significant Wi-Fi network.
Sprint sold its Wi-Fi network at seven airports to Boingo in 2007, and later struck a deal with Boingo to offload cellular traffic to Boingo’s airport Wi-Fi.
T-Mobile US once operated Wi-Fi networks for Starbucks and FedEx Kinko’s; now the carrier offers its voice over Wi-Fi service without the benefit of its own Wi-Fi network.
AT&T took over the Starbucks Wi-Fi network from T-Mobile US, only to lose it to Google last year. The carrier still operates more than 34,000 hot spots covering all 50 U.S. states. In addition, AT&T customers can auto-authenticate to more than 1 million Wi-Fi hot spots around the world.
Trusted vs. untrusted Wi-Fi
Mobile operators know they may get the blame if they direct users to Wi-Fi that does not perform well. At the same time, they cannot effectively offload traffic without turning to Wi-Fi that is beyond their control. Most U.S. operators own a lot less Wi-Fi than they did a few years ago, but they are offloading more traffic to Wi-Fi. Most of that offload is to untrusted Wi-Fi networks.
“Trusted and untrusted Wi-Fi access is a distinction between how a Wi-Fi access network integrates with the mobile core network or the evolved packet core [for LTE],” said InterDigital’s Robert Gazda, senior director of technology development. “Trusted Wi-Fi access is typically controlled or owned by the mobile network operator. Today, most Wi-Fi networks are untrusted access. Either they do not support 802.x security, they are not owned or controlled by the MNO, or they are simply not integrated with the mobile core.”
Untrusted does not have to mean insecure or unreliable. Device-side software helps carriers authenticate users, ensure security and monitor quality. Operators are finding it easier to work within the Android ecosystem, since Android is a more open system than iOS. Sprint’s automatic offload to Boingo Wi-Fi works on Android devices.
“The offload mechanism is through an application pre-installed on Sprint Android phones called the Sprint Connections Optimizer,” said Boingo CTO Derek Peterson. “The application includes a Boingo SDK that provides trusted connection capabilities to the application based on BSSID (Access Point ID), network type, authentication type and other identifiers to enable a successful connection to the network. Upon connection request from the application an authentication and authorization request is forwarded from the visiting network (Boingo) to the home network (Sprint) across an encrypted tunnel. With a successful authentication/authorization the user is allowed on the visiting network.”
Seamless authentication is one step on the road to seamless handoffs between Wi-Fi and cellular. Low-latency applications like voice and video require more integration than data handoffs.
Among the U.S. operators, T-Mobile US may be the furthest along in integrating Wi-Fi with the mobile core. The carrier’s voice-over-Wi-Fi service offers seamless handoffs to the cellular network (although this may work better in some locations than in others). T-Mobile US has said that it views Wi-Fi calling more as a service for users than as an offloading strategy, and that millions of its customers are using the service.
For more on Wi-Fi offload, download the on-demand RCR Wireless News feature report Effective Strategies for Wi-Fi Offloading and the complimentary webinar on the same topic featuring panelists from Republic Wireless, Senza Fili Consulting, Ixia and InterDigital Communications.
