Hello, forum friends today I would like to share with you the structure of PLMN.
2G PLMN:
BTS (Base Transceiver Station):
Piece of equipment that facilitates wireless communication between user equipment (UE) and a network MS = ME + SIM (Mobile Station = Mobile Equipment + Subscriber Identity Module).
BSC (Base Station Controller):
BSC is in control of & supervises a number of base transceiver stations (BTS).
The BSC is responsible for the allocation of radio resources to mobile calls and for the handover that is made between base stations under his control.
MSC (Mobile Switching Center):
The MSC connects calls between subscribers by switching the digital voice packets between network paths.
The MSC is stationed between the base station and the Public Switched Telephone Network (PSTN).
The MSC is responsible for handling voice calls and SMS including other services like FAX.
The MSC also works with the Home Location Register (HLR) – which stores location information.
TRAU (Transcoding Unit):
TRAU makes transcoding for each phone call or data for the user to protect the user data.
HLR/AUC (Home Location Register/Authentication Center):
The home location register (HLR) for obtaining data about the SIM and mobile services ISDN number (MSISDN; i.e., the telephone number) or the IMSI number (International Mobile Subscriber Identity).
The AUC is used to make authentication about the user data.
VLR (Visitor Location Register):
The visitor location register (VLR) provides subscriber information when the subscriber is outside its home network. It contains a changed number called TMSI (Temporary Mobile Subscriber Identity).
EIR (Equipment Identity Register):
Contain the UE (User Equipment) data and the IMEI number (International Mobile Equipment Identity).
SMS-C (Short Message Service Center):
It is responsible for sending and receiving short messages (text messages).
G-MSC (Gateway Mobile Switching Center):
It is used to connect all the other PLMNs with each other and also it is connected with ISDN (Integrated Service of Digital Network) and PSTN (Public Switched Telephone Network).
OMS (Operation and Maintenance Service):
It is called also OMC (Operation and Maintenance Center) or NOC (Network Operation Center), and it is responsible to monitor all the networks and give orders by corrective actions to make the network stable.
3G PLMN:
Node-B:
Piece of equipment that facilitates wireless communication between user equipment (UE) and a network, like the BTS at 2G system.
RNC (Radio Network Controller):
It is used to control a group of Node-B sites and connect it with Circuit Switch and Packet Switch Networks.
SGSN (Service GPRS Support Node):
GPRS is for (General Packet Radio Service), and this unit authenticates the user before using the data and also controls the mobility management for the user.
GGSN (Gateway GPRS Support Node):
It is used to connect all the other PLMNs with each other and also it is connected with ISDN (Integrated Service of Digital Network) and PDU (Protocol Data Unit).
IMS and IP Networks (Internet Protocol Multimedia System & Internet Protocol Network):
It is the internet service and the voice-over packet service to can make calls at the same time while you are using the internet without disconnecting.
4G PLMN:
eNode-B:
Piece of equipment that facilitates wireless communication between user equipment (UE) and a network, like the BTS at 2G system.
SGW (Serving Gateway):
It passes the user data between a group of eNode-B while moving in the network.
MME (Mobility Management Entity):
It is the main control unit in the 4G network, it is used in handover between the other generations, also in the data usage, it defines the PGW or SGW which will be used.
PGW (PDN Gateway):
PDN is for Public Data Network, and this unit is used to forgive each user an IP Address and it is also used to protect the user data from hacking and it is used to improve the QoS (Quality of Service Management).
HSS (Home Subscriber Service):
This unit is used to store all the user data in the 4G network.
AAA (Authentication, Authorization, and Accounting):
Authentication: Make sure that you are related to this network.
Authorization: Define the data which you can use from the network according to your packet.
Accounting: Calculating the data used to calculate the remaining from your packet.
PCRF (Policy Control & Charging Rule Function):
This unit is used to make sure you’re using the services which you are needed and paid for it (Services at your Number and which you paid for it), to give priority to the services according to the user's needs and their place.
