Mobile Switching Centre (MSC)
The Mobile Switching Centre (MSC) is a telephone exchange
that makes the connection between mobile users within the network, from
mobile users to the public switched telephone network and from mobile
users to other mobile networks.
The MSC also administers handovers to neighbouring base stations,
keeps a record of the location of the mobile subscribers, is
responsible for subscriber services and billing.
Home Location Register (HLR)
The
Home Location Register is a database from a mobile network
in which information from all mobile subscribers is stored. The HLR
contains information about the subscribers identity, his telephone
number, the associated services and general information about the
location of the subscriber. The exact location of the subscriber is kept
in a
Visitor Location Register.
Base Station Subsystem (BSS)
A base station is a radio transmitter/receiver, including an antenna,
used in a mobile telecommunications network. The base station maintains
the communication between the network and the mobile users through a
radio link.
The geographic area covered by a base station is called a
cell.
Visitor Location Register (VLR)
The
Visitor Location Register (VLR) is a database in a mobile communications network associated to a Mobile Switching Centre (
MSC).
The VLR contains the exact location of all mobile subscribers currently
present in the service area of the MSC. This information is necessary
to route a call to the right base station. The database entry of the
subscriber is deleted when the subscriber leaves the service area.
Equipment Identity Register (EIR)
The Equipment Identity Register (EIR) is a database that
contains a record of the all the mobile stations (MS)that are allowed in
a network as well as an database of all equipment that is banned, e.g.
because it is lost or stolen.
The identity of the mobile station is given by the International Mobile Equipment Identity (
IMEI). Each time a call is made, the
MSC requests the IMEI of the mobile station, which is then send to the EIR for authorisation.
HSS vs HLR
HSS is the evolution of the HLR for the next generation networks, such as IMS and LTE.
It
should be capable of taking to an SS7 network (MAP stack) for old CS
capabilities and be able to talk to the new networks via DIAMETER.
HSS
is then the new foundations to support the Evolved Packet Core through
S6 interface of Diameter protocol, and Cx/Sh for IMS networks.
On both cases, the AuC can be embed to generate authentication vectors for both.
HLR handles voice, sms and 3G data, essentially MAP traffic.
HSS handles 4G data, basically anything on DIAMETER.
REFERENCES
http://www.telecomabc.com
https://en.wikipedia.org/wiki/Base_station_subsystem
https://www.broadforward.com/home-subscriber-server-hss/
https://www.summanetworks.com/home/solutions/hss-hlr-replacement.html
https://www.linkedin.com/pulse/sim-cards-demystified-patrick-mutabazi/
