When a device connects to an LTE network, in a split second, the network verifies the profile and location. This action is initiated by the Home Subscriber Server (HSS), the main database of users that confirms who the user is and where they belong in the network. For operators, this is the source of trust and reliable service. It also double-checks the user to prevent unauthorized access and keeps the sessions active as users move from one cell to another. In this blog, we will clarify how HSS supports authentication and handover in LTE networks.
What is the Home Subscriber Server (HSS)?
The Home Subscriber Server (HSS) is the master user database of various components of the IMS network. It handles voice calls, stores the subscriber profiles, identifies and approves the subscribers, and even provides information about the subscriber’s live location and IP. Experts describe the HSS as the brain of the core network services. It is very similar to the authentication center (AuC) and the GSM home location register. When multiple HSSs are used, a subscriber location function (SLF) is required to map user addresses.
Moreover, it contains the data of service plans, security credentials (authentication keys and vectors), mobility data, and roaming permissions. HLR and HSS in telecom are used for the same purpose. The difference is that HLR is used in legacy networks, and the HSS is used in modern networks, and they are way more advanced. It supports high-speed data, policy control, and LTE and 5G services.
LTE Authentication: Step-by-Step Role of HSS
An LTE session begins with a detailed inspection. Before data transfer, the network confirms that the subscriber is valid. In between this exchange, the Home subscriber server acts as the repository and controller. The following is the step-by-step role of HSS in the LTE network:
- How LTE Authentication Works: When a device makes an Attach Request, the MME (Mobility Management Entity) requests the HSS for authentication data via the S6a interface. Then, the HSS generates authentication vectors and sends them back so the network and device can verify their identities.
- Authentication Vectors and Credentials: The HSS creates RAND, XRES, AUTN, and the master session key. These elements prove identity, test the network, set up encryption, and maintain the network’s integrity.
- HSS, MME, and AuC Interaction: The AuC within the HSS stores the subscriber’s authentication keys and produces vectors. The MME completes the mutual authentication with the device.
- Protect Subscriber Identity: Temporary identities are used to hide permanent subscriber numbers, and the authentication keys stay inside the HSS to prevent any kind of leak, as they can become an interception later.
- Prevent Security Risks: If the HSS finds an unauthorized identity, it immediately blocks the access, stops replay, and applies encryption to prevent eavesdropping and data theft.
How HSS Enables Seamless Mobility Management
Mobility is the feature that makes a telecom core network truly wireless. Users expect that when they travel on highways or on trains, the data should be stable and voice calls should be of high quality. There are many elements that make it possible, and the most crucial one is the HSS. During handovers, when a device switches cells, the HSS prefers the Mobility Management Entity over the S6a interface to transfer the subscriber context. Further, it creates new serving nodes to get authentication keys and service parameters. This coordination of HSS and MME helps operators balance load across cells.
Furthermore, location updates follow a specific process. When a device enters a new tracking area, it sends a Tracking Area Update request. The new MME informs the HSS, which discards the old location and approves the new one. This helps calls and data to route from the right path. In the case of roaming, the HSS authenticates the subscriber with AKA (Authentication and Key Agreement) procedures and shares subscription data with the visited network. This keeps the sessions active, and you don’t have to log in again.
Operational Benefits for Network Operators
In LTE networks, speed is measured in milliseconds. A few seconds’ delay in authentication or a missing mobility update can affect millions of sessions. In such scenarios, the HSS gives operators and service providers a strategic advantage. Its framework is designed to support a massive subscriber base, roaming traffic, and upcoming digital services.
- Centralized Subscriber Control: HSS in LTE stores subscriber profiles, security credentials, and subscription policies in one unified repository that allows operators to manage users over 2G, 3G, 4G, and IMS networks from a single point of control.
- Fast Authentication Response Times: HSS optimizes authentication and key agreement procedures to reduce attachment latency to help devices connect quickly and keep signaling costs low during peak traffic.
- Reduced Fraud and Identity Risks: HSS does a full identity verification against SIM data and coordinates with equipment registers to protect networks from unknown access and subscription scams.
- Scalable Mobility Management: HSS helps operators to track live location and support handover to allow networks to scale as per the increase in the number of subscribers and IoT devices.
- Improved Service Continuity: Redundancy and geo-redundant architecture of HSS keep sessions active all the time, even during failures or traffic spikes, for a positive user experience.
Best Practices for Managing HSS in LTE Networks
If you learn to manage the Home Subscriber Server, it will be a direct investment in your LTE network. The first way is to install Diameter firewalls and malware detection systems that inspect S6a/S6d signaling to block fraud and abnormal traffic. Next, you can implement strict access control and network segmentation to isolate the HSS from public systems. Also, if you conduct regular audits based on GSMA security frameworks, you can detect weak spots before the hackers.
In addition, real-time review of CPU load, memory usage, and Diameter transaction prices also helps you to detect congestion and abnormal behavior in the network way before. Also, if you plan capacity proactively, you can easily scale with subscriber growth. A horizontally scalable architecture supports super-fast expansion without affecting the performance of the LTE network.
In Summary
Authentication and mobility are two key features of an LTE network that make it reliable and secure. The Home Subscriber Server plays an important role in keeping these features to the point. When HSS performs well, users will have a great experience with your LTE network. If you’re looking for a scalable HSS in LTE, reach out to ComCode Technology. We are a telecom software solutions and consultancy provider for MVNOs, MNOs, messaging providers, private LTE, and private 5G networks. Our solutions are engineered according to your requirements. Contact us before your competitor does.
