What is 2G, 3G, 4G?
With all the recent fuss over 4G / LTE. Pentura thought a nice blog post highlighting the changes and developments of mobile infrastructure would be interesting for our readers. Below is a high-level description of the 2G, 3G, 3G-Femto and finally 4G networks.
2G (GSM/GPRS) is the initial backbone for all mobile infrastructure. At the front end it comprises of a Radio Tower (BTS) , and the Base Station Controller (BSC). The backend comprises of the usual core components the HLR, VLR, MSC.
When it came to implementing 3G, the decision was made to build on top of the existing 2G infrastructure and share some of the backend components. The only difference is the Radio Tower (NodeB) that supports a higher data rate (faster speed) together with a Radio Network Controller (RNC). Note: Users are referred to User Entities (UE). The backend comprises of the usual core components the HLR, VLR, MSC, with the addition of the SSGN and GGSN; which provide access to the Packet Switching Network, otherwise known as the INTERNET!
The diagram below shows how 2G (top) and 3G/UMTS (bottom) networks work side-by-side:
3G – Femtocell Technology
This technology allows customers with broadband connections so set up their own mini mobile tower in their home/business supporting up to 8 Mobile Subscribers (MS). The femtocell is known as an eNodeB or rather a Home eNodeB (HeNB), that then tunnels all communication down an IPSEC tunnel to your cellular providers IPSEC gateway; Thus being able to talk to your cellular providers core network.
Note: The Femtocells do not support encryption unlike the big eNodeBs on your cellular network. So if you monitor the connection between your handset and the Femtocell you will see the negotiation of the A5/0 encryption scheme; A5/0 = NO ENCRYPTION!
This is now where things become a little different…
Again the Radio Tower is connected to a device called an eNodeB (like the Femto Cell), this connects to the EPC. The EPC is an all-in-one solution that contains the following components : Mobile Management Entity (MME) (replacing the MSC); which in turn connects to the Service Gateways SGw and PGw (which replace the GGSN and the SSGN) and the Policy Charging and Rules Functionality (PCRF): performing bandwidth shaping and billing. That connects users to the Public Data Network (Internet),