Traditional HLRs (Home Location Registers) in 1G, 2G and 3G networks have always been the heart of the cellular network. The main functions of the HLR are managing subscriptions and subscription data, managing real-time subscriber registrations, managing real-time subscriber mobility and locations, managing real-time subscriber authentication and managing subscriber features. The HSS in LTE networks provides analogous services and is also the heart of the Evolved Packet Core (EPC) network.
As such, most of the activity for Diameter signaling traffic based on the most primary functions in the core network have a great impact on the HSS. If we look at these functions: subscriber registrations and de-registrations (i.e. network attaches and detaches); tracking area updates; authentications per subscriber device (and possibly for some applications); and number of simultaneous LTE applications running on a particular device; it is easy to see how the heart of the network comes under extreme signaling pressure. I’ve estimated that the HSS is involved in 50% to 65% of ALL Diameter signaling messages traversing an LTE packet core network, based on the behavior of the subscribers. Even if the network is optimized for tracking areas and autonomous registrations of the mobile devices, the single most important network entity will need to also manage and process most of the signaling traffic.
The HSS also has complex functions to process subscriber data for roaming, authentication and feature control; simply handling the amount of signaling traffic that enters and egresses the platform can be very burdensome. Let us assume conservatively, that we’re looking at a large network of 25 million LTE subscribers (also supporting VoLTE). Each subscriber might have a couple devices, say a smart-phone and a tablet computer and that these subscribers make 2 calls during the busy hour. Perhaps, each subscriber autonomously registers on the network or changes location area once per hour.
By my calculations and to handle such subscriber behavior, the HSS platform (or platforms) would need to process approximately 530K signaling messages per second! I would speculate that the HSS, and it’s associated signaling traffic, should be the primary concern for any reliable and highly-available LTE network deployment, above and beyond any other entity in the in the EPC.
Randy Snyder
Wireless Cellular Telecommunications Consulting
Wireless Research Services, LLC
Mobile: +1 (702) 521-7900
Email: rsnyder@wrsvs.com
Skype: randallsnyder
http://www.wrsvs.com
As such, most of the activity for Diameter signaling traffic based on the most primary functions in the core network have a great impact on the HSS. If we look at these functions: subscriber registrations and de-registrations (i.e. network attaches and detaches); tracking area updates; authentications per subscriber device (and possibly for some applications); and number of simultaneous LTE applications running on a particular device; it is easy to see how the heart of the network comes under extreme signaling pressure. I’ve estimated that the HSS is involved in 50% to 65% of ALL Diameter signaling messages traversing an LTE packet core network, based on the behavior of the subscribers. Even if the network is optimized for tracking areas and autonomous registrations of the mobile devices, the single most important network entity will need to also manage and process most of the signaling traffic.
The HSS also has complex functions to process subscriber data for roaming, authentication and feature control; simply handling the amount of signaling traffic that enters and egresses the platform can be very burdensome. Let us assume conservatively, that we’re looking at a large network of 25 million LTE subscribers (also supporting VoLTE). Each subscriber might have a couple devices, say a smart-phone and a tablet computer and that these subscribers make 2 calls during the busy hour. Perhaps, each subscriber autonomously registers on the network or changes location area once per hour.
By my calculations and to handle such subscriber behavior, the HSS platform (or platforms) would need to process approximately 530K signaling messages per second! I would speculate that the HSS, and it’s associated signaling traffic, should be the primary concern for any reliable and highly-available LTE network deployment, above and beyond any other entity in the in the EPC.
Randy Snyder
Wireless Cellular Telecommunications Consulting
Wireless Research Services, LLC
Mobile: +1 (702) 521-7900
Email: rsnyder@wrsvs.com
Skype: randallsnyder
http://www.wrsvs.com
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