IMS Network Element - HSS Overview

IMS Network Element - HSS Overview (study Note)

HSS Overview
- A FE in Core Network (CN) in IMS, its role similar to HLR of the PS & CS domains
- Subscriber database for IMS network, Master database of subscriber information.

HSS (Home Subscriber Server) - Master database of subscriber information:
- User identification, numbering and addressing
- User security: network access control for authentication and authorization
- User location information at inter-system level
- User profile

IMS HSS Function
- Provide Filter Criteria to S-CSCF
- I-CSCF will assign S-CSCF to UE during IMS registration, HSS will provide these information to I-CSCF
- Provide S-CSCF address to I-CSCF for INVITE
- Cancellation of S-CSCF (due to change in subscription of Subscriber)
- Store Information
- Before Registration à Subscriber Profile
- After Registration à Serving-CSCF address/name & Subscriber Profile

HSS stores information required by:
- S-CSCFs (downloaded via Cx interface) Data model and abstract syntax notation in 3GPP TS 29.228;
- IM-SSF Application Servers (downloaded via Si interface);
- Application Servers (downloaded via Sh interface).

Further Information: https://docs.google.com/fileview?id=F.60e80214-c355-44a0-8161-f5283a851bc2