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Carrier Wi-Fi – A New Era in Mobile Roaming

April 21, 2016

Carrier-grade Wi-Fi has the potential to radically change the Wi-Fi landscape. So, what will it take to make it work more like cellular roaming?

By Ashish Jain

Roaming is a fact of life in today’s mobile-first world. However, the quality of the roaming experience hasn’t kept up with the needs of business users or consumers. Each of us expects to have constant access to voice, messaging and data services, regardless of where we are. And most of us have to juggle a combination of cellular, and Wi-Fi connections in order to access to these services when we’re on the move.

The cellular connection works well when the signal strength is good, and the network is not congested. At other times, Wi-Fi works better. But the Wi-Fi experience can be patchy. Wi-Fi, almost always, requires the user to input a username, and password, and it sometimes even requires a credit card payment. So, the challenge becomes making Wi-Fi roaming work more like cellular roaming — bringing the two networks together to offer an automatic, seamless roaming experience with the best possible connection.

With the majority of Wi-Fi-connected mobile traffic and the number of public Wi-Fi hotspots expected to grow seven-fold to 350 million by 2018, the market is primed for a new alternative. Carrier Wi-Fi may just be the ticket.

Carrier Wi-Fi — A New Dawn in Mobile Roaming

Mobile Network Operators (MNOs) are rethinking their Wi-Fi strategies. Many of them initially viewed Wi-Fi as a competitive threat that would cannibalize demand and erode revenue for cellular services. But now, with up to 80 percent of mobile traffic originating indoors, and mostly on Wi-Fi, MNOs are losing subscriber relationships. These losses result primarily from subpar cellular network signal strength, poor coverage and inadequate capacity.

Today, MNOs are beginning to see Wi-Fi as an important network densification strategy — a tool to help them cope with the mobile data explosion while allowing them to offer better coverage and capacity, especially indoors and in dense urban hotspots. Essentially, MNOs view the addition of Wi-Fi coverage as a way to help them offset the costs of added cellular capacity in the face of flat overall service revenues.

But offering basic, best-effort access to a standalone Wi-Fi network isn’t enough to re-engage with customers. To do that, mobile service providers need to offer a differentiated Wi-Fi service — one that makes Wi-Fi roaming easier. And they need to integrate Wi-Fi into the mobile network to make it into a seamless, cellular-like roaming experience (see Figure 1).

GENBAND standalone vs integrated wifi

Figure 1

Logging onto basic Wi-Fi is almost always a manual or semi-manual procedure requiring a username and password. In some cases, a device will helpfully remember previously used networks and access points, but payment for access is also often required (unless a business-to-consumer operator such as a retail outlet or coffee shop is offering “free” service). When payment is necessary to log onto Wi-Fi, it typically involves the manual input of credit card details. And, entering such details over insecure, unencrypted Wi-Fi can present potential security concerns.

With a Carrier Wi-Fi network, on the other hand, subscribers can connect and authenticate automatically, securely and seamlessly — without subscriber intervention. In the Carrier Wi-Fi scenario, mobile subscription credentials are stored on the user’s mobile device. These credentials are then used for authentication with the subscriber’s home network, which is now integrated into the Carrier Wi-Fi network. The differences between basic and Carrier Wi-Fi are highlighted in Figure 2.

GENBAND basic vs carrier chart
Figure 2

Improvement in the user roaming experience is the key factor driving Carrier Wi-Fi, but several additional benefits emerge along with improved customer satisfaction (refer to Table 1).

GENBAND benefits table
Table 1

Many service providers have already announced their intentions to upgrade to Carrier Wi-Fi. According to recent reports, 85 percent of MNOs plan to invest in Carrier Wi-Fi by 2016, and 72 percent of public hotspots are expected to be compatible with Carrier-grade Wi-Fi by 2018. This is a substantial increase from the approximated 10 percent compatible today.

Implementing Carrier Wi-Fi Roaming

Delivering a truly cellular-like roaming experience over Carrier Wi-Fi requires a number of key functionalities (see Figure 3). First, Wi-Fi networks must be securely connected to the mobile network, and users must automatically be connected to the best-performing available Wi-Fi network.

GENBAND carrier wi-fi arrow diagram
Figure 3

Second, authentication must be secure, seamless and automatic — using mobile subscription credentials, together with authorization and policy control, to allow users access to their preferred service features. And finally, data traffic must be encrypted for the security of both the end user and the network.

The key elements required to enable Carrier-Wi-Fi are a secure Next Generation Wi-Fi network; a secure wireless access gateway solution; a mobile packet core with authentication, service policy control and billing machinery; and mobile devices that support secure Extensible Authentication Protocol (EAP) authentication.

• Next Generation Wi-Fi Network – Advances in Wi-Fi (802.11) technology have led to a family of enhancements referred to as Next Generation Hotspots (NGH) and Hotspot 2.0 “Passpoint.” These enable roaming devices to automatically discover and seamlessly connect to Carrier Wi-Fi networks.

• Wireless Access Gateway – The Wireless Access Gateway (WAG) plays several key roles in enabling Carrier Wi-Fi roaming. It securely aggregates connections between hundreds or thousands of access points and the mobile packet core, while enabling seamless authentication, IP session mobility, interworking, routing, encryption and secure data tunneling. It also provides security, service protection, metering and accounting of data traffic. Additionally, it enables local data traffic breakout or fall back for 2G or non-MNO subscribers (e.g., cable operators).

• Mobile Packet Core 2G/3G/4G LTE – The key difference between basic Wi-Fi and Carrier Wi-Fi lies in the ability of mobile users to authenticate seamlessly back to their home mobile service provider’s core network using their mobile credentials — and, of course, in the ability of users to enjoy all the same services and rates. This requires authentication, service policy control and billing machinery per 3GPP specifications.

• Mobile Devices – Most smartphone devices are already shipping with the required NGH and Hotspot 2.0 Passpoint protocols and security functions described above.

Carrier Wi-Fi Roaming Use Cases

Carrier Wi-Fi can offer subscribers a truly cellular-like data roaming experience. In addition, it is a solution that is equally relevant to subscribers of other Wi-Fi networks, such as cable, fixed network operators, wireless Internet service providers and independent Wi-Fi networks. Two of the key Carrier Wi-Fi use cases generating the most interest in the industry include roaming into a visited Wi-Fi network and roaming into a visited Wi-Fi network served by a Wi-Fi roaming exchange hub.

Roaming into a Visited Wi-Fi Network

Scenario Overview
• Enables Wi-Fi roamers (MNO subscribers) to seamlessly roam into a visited Wi-Fi network by using their home network (mobile) subscription credentials for authentication and authorization (see Figure 4).

GENBAND wi-fi users MNO subs
Figure 4

• The visited Wi-Fi network is either controlled, owned and/or operated by the MNO — or has bilateral peering roaming agreements with the MNO.

Description of Carrier Wi-Fi Roaming and Authentication
• Device receives information about available and preferred Wi-Fi networks, including NGH 2.0 hotspots (see Figure 5).

GENBAND carrier wi-fi connection flow

• Device attempts to attach to the hotspot automatically, without any subscriber interaction, based on user’s mobile credentials.

• Device sends authentication credentials to the visited Wi-Fi network, which queries the home MNO network via the wireless access gateway.

• The user is successfully connected and authorized to access the Wi-Fi network, and data traffic is securely tunneled back to the 3G/4G mobile home network. Figure 5

• For 2G or non-MNO home networks, the Wi-Fi operator may break out the user data locally via the wireless access gateway.

Advantages of the Carrier Wi-Fi Roaming Scenario

• Enables Wi-Fi MNO roamers to access Wi-Fi networks using their mobile subscription credentials – in the same manner in which MNO roamers access cellular networks.

• Offers seamless discovery and automatic connection to nearby hotspots if the networks are NGH/Hotspot 2.0-enabled.

• Enables peer-to-peer operator implementation of Carrier Wi-Fi, with several benefits to end users and network operators.

Roaming into Visited Wi-Fi Networks served by a Wi-Fi Roaming Hub

Scenario Overview
• Similar to the above-described use case, but any Wi-Fi roamers (MNO or other subscribers) can seamlessly roam into a visited Wi-Fi network using their home network (mobile, MSO, WNO, etc.) credentials.

• The visited Wi-Fi networks would have roaming partnerships or consortia agreements with a Wi-Fi Roaming Hub provider.

What is a Carrier Wi-Fi Roaming Hub?

In order to provide a global Carrier Wi-Fi roaming service, mobile operators would need to establish bilateral roaming agreements with multiple Wi-Fi operators. This a challenging task. An alternative approach is to partner with a Carrier Wi-Fi Roaming Hub provider (see Figure 6).

GENBAND wi-fi users

Figure 6

• A Carrier Wi-Fi Roaming Hub (Exchange or Interconnect Hub) enables the creation of an aggregated network of both Wi-Fi and MNO networks. This ensures seamless roaming interoperability and a wider geographical reach for subscribers.

• The Wireless Broadband Alliance (WBA) specifies standard Wi-Fi hub service specifications for Wireless Roaming Intermediary eXchange (WRIX) hubs. You can find more details by visiting the WBA website at www.wballiance.com.

Description of Carrier Wi-Fi Roaming and Authentication with Roaming Hub

• In addition to the previous use case, the following factors apply:

• The Wi-Fi Roaming Hub provider hosts the WAG.

• The Hub sends user authentication requests from the Wi-Fi network to the appropriate home network.

• The Hub enables both mobile and non-mobile carriers to work with any Wi-Fi network.

• The WAG provides signaling interworking and data encryption.

• Based on roaming policies, the Hub may also provide local breakout of user data traffic.

Advantages of Using a Roaming Hub

• A Carrier Wi-Fi Roaming Hub simplifies the technical and commercial arrangements between roaming partners.

• It allows service providers to extend their data, voice and messaging services over Wi-Fi.

• It expands service providers’ global geographic reach, as well as roaming subscribers’ ease of access to Wi-Fi networks within venues such as malls, hotels, stadia, conference centers, enterprises and airports, as well as on planes and trains.

• It offers secure interconnection, as well as data and financial clearing for accounting and billing by the trusted Hub partner.

• It creates opportunities for Hub operators to generate revenue through Wi-Fi Roaming or Wi-Fi Roaming-as-a-Service offerings.

Summary

Carrier Wi-Fi provides a powerful solution that will allow service providers to significantly enhance mobile data roaming services. As a result of this solution, subscribers will enjoy seamless, trouble-free, cellular-like roaming experiences across both Wi-Fi and cellular networks (See Figure 7).

GENBAND summary of carrier benefits chart

Figure 7

By combining NGH and WAG technologies, service providers can implement a Carrier Wi-Fi solution that ensures automatic network discovery and connection, secure authentication and encryption of user data traffic to the packet core network.

Further, by improving the quality of the roaming experience, mobile service providers can reestablish and strengthen subscriber relationships — thereby boosting customer satisfaction and retention and significantly reducing churn. The reduced cost of building coverage and capacity over Carrier Wi-Fi networks, coupled with additional roaming revenue opportunities, is an attractive offering not just to mobile operators, but to network service providers in every segment. The benefits of Carrier Wi-Fi are poised to introduce a new era in mobile roaming.

Author Bio
Ashish Jain is Director of Solutions Marketing at GENBAND. He has over 10 years of telecommunications industry experience with expertise in the areas of Voice over IP for fixed and mobile networks, Wireless Security, Mobile OTT, Internet/e-commerce, and enterprise social media applications. Ashish holds a bachelor’s degree in Electronics Engineering and a master’s degree in Computer Science, with specialization in networks and communications, from The University of Texas.

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