Subscriber Location Function in Modern Telco Networks

Subscriber location function in modern telco networks is crucial for providing location-based services to subscribers.

The subscriber location function is used to determine the physical location of a subscriber in a cellular network. This information is then used to provide various services such as emergency services, location-based advertising, and navigation.

In modern telco networks, the subscriber location function is typically implemented using a combination of cell ID, timing advance, and assisted GPS.

Cell ID is a method used to determine the location of a subscriber based on the cell ID of the nearest cell tower.

For more insights, see: Apple Location Services

The Subscriber Location Function (SLF) plays a crucial role in identifying the specific Network Function (NF) Producer selection based on the Subscriber Identity. This involves checking if an SLF lookup needs to be performed before processing the discovery request.

The SLF function on the UDR network function is configured with details of subscribers mapped to group identifiers. Producer network functions are deployed in network belonging to group identifiers.

Take a look at this: ISDN Digital Subscriber Line

The SLF process involves sending an SLF query with the received Subscriber Identity to find the NF Group Id. This NF Group Id is then used to generate the NFDiscover service response.

Here's a step-by-step overview of the SLF process:

The SLF is not a mandatory component of IMS, but it is recommended for large-scale deployments that involve multiple HSS nodes.

We need subscriber locations for some pretty important reasons. Finding the location of a subscriber making a call to emergency services is a critical use case.

The Global Mobile Location Centre (GMLC) is triggered to get the subscriber's location in case the call is cut off, battery dies, etc. This is a lifesaving measure that can be a matter of seconds.

Different countries have different laws regulating access to the subscriber location functions. This means that what's allowed in one country may not be in another.

No magic super stealth SIM cards, special phones, or fancy firmware can prevent the GMLC from finding your location.

Related reading: Do Not Call Registry Text Messages

Location Reporting is a feature that can compromise your privacy.

Your phone can report your location to the network even when you're not actively using a location-based service.

This is done through passive ways of determining location, such as Uplink Time Difference of Arrival (UTDOA) and the Cell Global Identity (CGI).

You can try a hack to disable this functionality, but it's only effective as long as your device is connected to the network.

For example, if you're connected to the network, UTDOA and CGI will continue to report your location.

Location Services is a crucial aspect of Subscriber Location Function. Cell Global Identity (CGI) gives the identity of the eNodeB serving a user, allowing for basic location determination.

There are several methods to determine a user's location, including Cell ID positioning, which can be improved with the Combain Location API, and E-OTD positioning, which requires UE support. This API is based on actual measured training data, not cell tower location, resulting in improved accuracy.

To pinpoint a user's location, various signals can be used, such as signal strength, barometric pressure, and humidity, which can be reported by the base station. Timing Advance (TA) and Time of Arrival (TOA) also rely on timing signals to determine a user's distance from the eNodeB.

For another approach, see: International Mobile Subscriber Identity

Enhanced Services (LBS) are designed to improve network-driven location services, particularly for devices without GPS. This means you can get a more accurate location without relying on satellite signals.

Cell ID positioning has been improved thanks to the Combain Location API, which uses actual measured training data rather than cell tower locations. This results in more accurate location determinations.

Indoor and outdoor positioning is now seamless, ideal for urban and dense environments where GPS often struggles. This is a game-changer for navigating cities and busy areas.

Low-power positioning is also available for IoT devices, extending their battery life. This is a huge advantage for devices that need to run for a long time without recharging.

Here are the key benefits of Enhanced Location-Based Services (LBS):

In LTE networks, Diameter based signaling is used to find a subscriber's location.

To query the MME, the GMLC uses the LCS-Routing-Info-Request on the SLh Diameter interface to the HSS.

The HSS responds with the LCS-Routing-Info-Response, providing the details of the MME serving the subscriber.

The MME can report locations to the GMLC periodically.

To request a subscriber's current location, the GMLC sends a Provide-Location-Request to the MME with the subscriber's IMSI.

The MME responds with the location info in the Provide-Location-Response after querying the eNodeB and optionally the UE.

Cost and efficiency are crucial aspects of any location-based service. Reducing network signaling costs can be achieved by optimizing location updates without overloading network infrastructure.

By minimizing data usage for positioning, you can significantly cut down on costs. Efficient algorithms can replace constant GPS pings, leading to a substantial reduction in data consumption.

Optimizing location-aware services can also improve network resource allocation. This allows for a more efficient use of network resources, leading to better performance and reduced costs.

Here are some key benefits of optimizing location updates and data usage:

Alternative positioning is a crucial aspect of the subscriber location function. It provides a backup for GPS outages, such as those that occur in tunnels, urban canyons, or deliberate jamming scenarios.

In these situations, alternative positioning ensures emergency support is available, aligning with regulatory mandates like E911 and AML. This is essential for public safety and emergency services.

Alternative positioning also enhances location accuracy indoors, where GPS signals are weak or unreliable. This is particularly important in buildings and other structures where GPS signals can be blocked or weakened.

Here are some ways alternative positioning can be achieved:

Compliance and Support is a crucial aspect of any subscriber location function. Ensuring regulatory compliance is a must, especially for emergency services like E911.

E911 requires accurate and reliable location information to dispatch emergency services quickly and efficiently. Advanced Mobile Location (AML) also relies on precise location data to provide emergency responders with critical information.

A unique perspective: Radio Resource Location Services Protocol

AML and E911 are just a few examples of regulatory requirements that need to be met. Lawful interception is another important aspect that must be considered.

To reduce dependence on end-user GPS, privacy-compliant positioning solutions are essential. These solutions provide an alternative method for determining location, ensuring that user data remains secure.

Here are some key compliance and regulatory requirements to keep in mind:

IoT Asset Tracking is a crucial application of Subscriber Location Function. It enables low-power location tracking for NB-IoT, LTE-M, and 5G IoT devices.

Combain's Cell ID positioning is a key enabler of platform-independent IoT tracking solutions. This technology allows for seamless and scalable tracking without the need for GPS, apps, or custom firmware.

Mobile Network Operators (MNOs) and Mobile Virtual Network Operators (MVNOs) can easily offer location services using just SIM data. This makes it possible to track anything from logistics assets to vehicles and IoT devices.

Intriguing read: How to Block All Location Tracking in the Browser

The combined Traxmate SIM Tracking and Combain Cell ID solution can be seamlessly integrated with any IoT connectivity platform. This is due to its open, platform-agnostic architecture.

Machine learning algorithms provide enhanced location accuracy. This is particularly useful for massive-scale IoT deployments, such as asset tracking, logistics, connected cars, and smart meters.

Here are some key benefits of IoT Asset Tracking:

The network and authentication process is crucial for the subscriber location function to work effectively.

The subscriber's device must be registered with the network's authentication server before it can send or receive data.

The authentication server verifies the device's identity by checking its IMEI or IMSI number against a database of valid devices.

This process is typically done through a protocol called RADIUS (Remote Authentication Dial-In User Service).

Authentication servers can be local or remote, depending on the network's configuration.

Once authenticated, the device is assigned an IP address and can communicate with other devices on the network.

The subscriber's location is then determined by the network using a combination of cell ID, location area code, and other information.

Worth a look: Azure Function Authentication