How 5G technology and design choices are changing LI requirements for Law Enforcement, part 1

When CSPs choose to implement 5G for their customers, they generally follow a phased approach.
The 1st phase generally consists of an upgrade of their Radio Access Network (RAN) in combination with an upgrade of their EPC core.
The 2nd phase would introduce a dedicated 5G core, and the 3rd phase would add support for a dynamic 5G core topology.
The impact of each of those phases on Lawful Interception is far beyond the obvious need for integration with a Lawful Interception solution. In a series of blog posts, I will discuss some of the less obvious implications that Law Enforcement will encounter when CSPs start introducing 5G to their subscribers. This is the first blog in this series.

Phase 1 – RAN / EPC Upgrade

When CSPs upgrade their RAN to support the new 5G frequencies, this often goes hand in hand with the switching-off of the older 2G and/or 3G technologies. When this happens, subscribers can only make voice calls over VoLTE or VoNR. To support roaming subscribers, dedicated provisions need to be made by the CSP to support VoLTE/VoNR Roaming, this can be done either by extending their architecture through either Local BreakOut or S8 Home Routing (S8HR) architecture. The latter is currently recommended by 3GPP. For the interception of VoLTE/VoNR roaming traffic over S8HR special lawful interception equipment is required at the CSP. As VoLTE/VoNR are packet-switched voice call technologies,  legislation should not only mandate the interception of packet-switched data or at least the VoLTE/VoNR services, but also the VoLTE inbound roaming traffic.

With the RAN upgrade also comes the upgrade of the EPC core. This upgrade is typically done to introduce flexibility and scalability in their core network, in other to support higher data throughputs. For some CSPs, this adds the need for an upgrade of their Mediation Function to handle the new throughputs. But as this increased amount of intercepted data will also be handed over to the LEA, the LEMF and the human resources that analyze this data should be able to handle the higher influx of data.

The 3rd impact on Law Enforcement of the RAN upgrade related to the newly to be supported frequencies. Direction Finders and Identity Catchers should support those new frequencies.

Phase 2 – 5G dedicated core

During the 2nd phase, CSPs will introduce a dedicated 5G core.
One of the foremost implications for Law Enforcement of this change is related to the fact that during the standardization done in 3GPP, they took the opportunity to improve the subscribers’ privacy by constructing a protocol architecture that protects against IMSI catchers, by ensuring the full anonymization of the subscribers’ identity from mobile equipment to core network. They did ensure that the permanent identifiers are no longer ever will be sent over the air. This change would make the use of Direction Finding and Identity Catching no longer feasible. To overcome this problem, an extension to the Lawful Interception architecture was designed to facilitate the use of these tools but requires specific infrastructure and cooperation of each Mobile Network Operator. The specifications also describe a warrant interface (HI1). These changes will have a big impact on the workflow and equipment of Law Enforcement. Dedicated Legislation should enforce this.

In part 2, I will continue this series of blogs. Please feel free to contact Group 2000 if you want to know more about the topics discussed within this blog. Or leave your information in the contact form, and our experts will call/email you back.


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