WiFi offloading vs VoWiFi

In recent years we have encountered a lot of customers wanting to utilize their networks more efficiently, and provide premium service for their subscribers. WiFi offloading and VoWiFi are popular ways to to extend the mobile operator’s network coverage into wifi, free bandwidth from congested cellular networks and improve user experience with better connectivity. The technologies share many similarities and both use a 3GPP AAA server for SIM based authentication.

WiFi offloading offers some flexibility in the supported authentication backends and the SIM authentication can be done through various HSS and HLR interfaces depending on what the mobile operator has available. This is especially important in roaming scenarios where the WiFi provider has agreements with multiple MNOs to offload their subscribers.

WiFi calling is more strictly standardised to support high QoS for the voice call, and also the handover between VoWiFi and VoLTE. This allows users to move outside the range of the WiFi hotspot and seamlessly continue the call over VoLTE, and vice versa.

Let’s take a look at the key differences between the two related technologies:

Comparison	WiFi offloading	VoWiFi
Purpose	Ease network congestion, Network CAPEX savings, Roaming cost savings, Secure authentication to private wireless networks: carrier, industrial, in-flight, underground, IoT	Ease network congestion, Indoor coverage extension, Combat OTT apps, Roaming cost savings
Relationship between MNO and access network provider	Agreement required between MNO and wifi provider	No relationship between MNO and wifi provider
Access network	Carrier or partner wifi	Any public or private wifi
Traffic	Data only	Voice and video calls
SIM authentication protocol	EAP-SIM, EAP-AKA, or EAP-AKA’	EAP-AKA
Supported HSS interfaces	SWx, Wx, Cx, S6a	SWx required
Supported HLR interfaces	MAP, SIGTRAN	Not supported
ePDG	Not applicable	ePDG mandatory
Security	WPA Enterprise	IPSec tunnel between UE and ePDG
IMSI Privacy	Yes, supported by Radiator	Yes, supported by Radiator

What is different?

The main difference between WiFi offloading and VoWiFi is the relationship between the mobile operator and the wifi provider: operator controlled data offloading always requires a prior agreement between the MNO and the WISP. WiFi offloading is often done in high traffic areas such as airports, sports stadiums and concert venues, since offloading users to WiFi is cheaper than adding microcells to boost the mobile signal. MNOs can invest in carrier wifi hotspots themselves, or make offloading agreements with wireless ISPs.

VoWiFi requires the mobile device to be connected to a wifi before attempting a VoWiFi call, but any type of wifi can be used for WiFi calling, including consumer home wifi. Therefore no relationship between the mobile operator and WiFi provider is required. However VoWiFi has specific technical requirements for the MNO: a HSS with SWx interface and ePDG are required.

Private network authentication

WiFi offloading technology is also applicable to private network offerings, such as industrial and IoT networks. SIM authentication provides a secure method to authenticate users into a private network using their SIM credentials and eliminates the human element of reusing and sharing passwords. In high security deployments the SIM authentication can be further combined with device IMEI check, to make sure that only authorised users and devices are able to access the private wifi network. VoWiFi is also possible in private networks, and can enable voice calls in challenging environments such as underground.

Interested in WiFi offloading or VoWiFi?

Radiator SIM Pack provides a fully featured 3GPP AAA server solution, with superb flexibility to connect with your environment. Please contact the Radiator team at sales (at) radiatorsoftware.com to get a quote.

Radiator SIM Pack 2.9 released

Recently, we have met increased demand for SIM authentication in different use cases and services. Radiator development is driven by the actual customer cases and we are now pleased to announce the release of Radiator SIM Pack version 2.9!

Here are selected highlights from the new release:

Cx support for EAP-SIM, EAP-AKA and EAP-AKA’ authentication

Diameter Cx interface provides an alternative way of fetching the SIM authentication vectors when the standard SWx interface is not available from the MNO. Cx is an HSS interface that is typically used to authenticate users from the IMS side of the network, but Radiator can now also use it for SIM based Wi-Fi authentication.

SIGTRAN location update features

Support for MAP UpdateLocation, MAP UpdateGprsLocation and MAP CancelLocation have been implemented in SIGTRAN. Location update features make it possible to resolve the user MSISDN (i.e. mobile number) and use IMSI related profile for authorisation. As a result, different authorisation rules can be enforced based on the MSISDN, or mobile numbers can be included in logging, accounting and other customer specific requirements.

Improved temporary identity generation

Temporary Mobile Subscriber Identity or TMSI is a pseudonym for the subscriber’s actual identity, IMSI. Plain or encrypted IMSI is always used for the initial SIM authentication, but a temporary identity can be generated for the subsequent requests to make re-authentication faster and increase security. Radiator TMSI implementation has now been updated per recent 3GPP specification: the improved implementation no longer requires a SQL session database further enhancing the speed of re-authentication. Historical data is also retained better.

For a full list of new features and changes, please see Radiator SIM Pack revision history.

Trends in operator AAA cases

In our recent projects with customers ranging from small private operators to major tier 1 carriers, we have seen these significant trends:

• Demand for Wifi offloading and VoWiFi remains high for various reasons: coverage and capacity expansion, ease of congestion in high density areas, and cost saving, especially for saving international roaming costs.
• Non-fixed backhaul connectivity cases (in-flight, train, maritime) cases are emerging.
• New private LTE/5G operators need SIM authentication to add Wi-Fi networks to their offerings. Radiator is an integral part in different MVNE solutions in connecting the MVNO and MNO network elements.

In addition, security requirements have increased. Demand for IMSI Privacy is driven by Android and iOS, and support for IMSI encryption is now a must for new offloading projects. RadSec is required for various roaming scenarios, including OpenRoaming. Both are supported by the Radiator SIM Pack - with a long track record of field proven production implementations.

Would you like to know more?

Radiator pre-sales team includes experienced engineers who can provide expertise for advanced Diameter and roaming use cases, including non-standard and custom cases.

In addition to top tier technical support, we also provide a flexible licensing model to match your business case. Whether you have your own subscribers, IoT devices or roaming guests, you can grow your license at the same pace where your business grows - you can just buy add-on licensing as you are onboarding more SIM authentication or VoWiFi end users, for example.

We always know that every customer case is different - so please do not hesitate to contact us at info@radiatorosoftware.com.

Cutting roaming costs and expanding coverage with Radiator SIM-based authentication.

Modern SIM-based devices, like smartphones and tablets, are able to join and switch between different networks automatically. This is especially valuable to mobile operators who want to offload data from their mobile network to a nearby Wi-Fi network, because Wi-Fi connections are significantly cheaper to operate. It also enables Wi-Fi providers to monetize their Wi-Fi net- works and provide services in partnership with mobile operators. In addition, with use of OpenRoaming or other Wi-Fi roaming services, it also provides a way to expand the coverage of carrier Wi-Fi.

Use cases for the SIM authentication include:

Wi-Fi Offloading:

In busy locations with high volumes of mobile traffic like sports stadiums, shopping malls, public transport hubs and underground metros, SIM-based devices can automatically switch from mobile data connections to local Wi-Fi networks. Transferring the data traffic to Wi-Fi networks reduces the load on the mobile network, which improves the coverage and the user experience. In addition, using Wi-Fi roaming services, such as Orion Wi-Fi or OpenRoaming, can further reduce costs when carriers can use these additional services for Wi-Fi offloading.

Voice over Wi-Fi

SIM-based devices can also switch voice calls from mobile networks to Wi-Fi networks, and this kind of call is known as Voice over Wi-Fi. As with data traffic, switching traffic from regular calls to Wi-Fi networks can help carriers and operators to reduce the load on the mobile network, enabling better call quality and continuity.

Wi-Fi Roaming

When a SIM-based device automatically joins a Wi-Fi network or switches to another one, this is called Wi-Fi roaming. Wi-Fi roaming is used to maintain an uninterrupted data connection when the user moves from location to location, or when the current Wi-Fi connection is overloaded or when the signal is weak. In these situations as well, using OpenRoaming and other Wi-Fi roaming services can expand the coverage for mobile carrier.

Wi-Fi SIM-based authentication is essential to making these capabilities work. Before a device is allowed to join a new Wi-Fi network, it must be authenticated using the IMSI*. For this reason, Wi-Fi SIM-based authentication is supported by the latest Android and iOS mobile devices. However, there are still some security issues with this type of authentication. As a result, mobile OS manufacturers are now pushing for even better security on Wi-Fi networks and they require IMSI Privacy Protection with all new OS versions.

How can Radiator help you in this?

The Radiator SIM Pack for Radiator AAA Server Software makes it easy for operators to enable IMSI Privacy Protection. It is the key component needed for secure and seamless switching between mobile and Wi-Fi networks using SIM-based authentication. The Radiator SIM Pack also provides all the functions required for a 3GPP AAA Server.

IMSI privacy is a key feature of the Radiator SIM Pack, and it provides server-side support for permanent identity protection during Wi-Fi SIM-based authentication, Wi-Fi offloading and VoWiFi, resulting in a higher quality user experience. You can read more about Radiator SIM Pack and IMSI Privacy protection from our IMSI Privacy whitepaper.

In addition to this, Radiator provides also all the services and products needed when joining to  Wi-Fi roaming services, such as OpenRoaming, or when connecting to mobile carrier infrastructure by using Diameter interfaces.

Would you like to know more?

If you would like to know more about Radiator, SIM authentication, IMSI Privacy, joining OpenRoaming etc., and how we can help you in your use case, you can always contact our team at info(a)radiatorsoftware.com. Looking forward to hearing from you!

*) In SIM-based mobile devices, like smart phones and tablets, the user’s unique identifier is stored on the SIM card in a standard format known as the International Mobile Subscriber Identifier, or IMSI for short.