Mar 17 2014
LTE Technology Overview
The LTE technology enabled fast mobile internet connection. Check the basic architecture and components of the 4G networks. LTE is a full IP technology used for the mobile broadband services for data transfer and voice calls. Soon it will be used for the Multimedia Broadcast Multicast Service (MBMS).
The LTE Radio Architecture
We could divide LTE architecture consists from the two parts:
- Radio Access Network
- Core Network
In the figure you can see how all the nodes are logically connected. Straight lines are for the user traffic, while dashed lines are for the control traffic.
Core Network is the brain of the system. It is formed of telephony switches that enable the different services for the mobile users. Core network devices connect the mobile devices in the mobile network. They also connect the mobile network with the fixed telephony network and internet. The LTE core network is called EPC (Evolved Packet Core) or System Architecture Evolution (SAE).
The core network is formed from the five nodes:
Mobility Management Entity or MME is the central control node in the EPC network. It is responsible for mobility and security signaling, tracking and paging of mobile terminals.
Serving Gateway or S-GW transports the user traffic between the mobile terminals and external networks. It also interconnects the radio access network with the EPC network. It is connected to the P-GW.
PDN (Packet Data Network) Gateway connects the EPC network to the external networks. It routes traffic to and from PDN networks.
HSS (Home Subscriber Server) is the database of all mobile users that includes all subscriber data. It is also responsible for authentication and call and session setup.
PCRF (Policy and Charging Rules Function) is node responsible for real-time policy rules and charging in EPC network.
Radio Access Network
The radio access network is used for wireless radio connection between the mobile phones and antennas from the mobile operator. Radio infrastructure is formed of the following nodes:
- LTE mobile terminal
- Radio interface
The radio access network is also called EUTRAN or Evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network. EUTRAN can be also called just LTE (Long Term Evolution).
LTE Mobile Terminals
LTE mobile terminals are the mobile phones and other devices that support the LTE standard.
Read more about the LTE mobile terminals in the post 4G Wireless Internet – How to get the Mobile Internet Access with 4G.
Radio interface is a wireless connection between the LTE mobile terminals and eNodeB. It is wireless signals that form the mobile cells.
E-UTRAN Node B or eNodeBs are situated all over the network of the mobile operator. They connect the LTE mobile terminal via radio interface to the core network.
LTE enables the maximum data rates of 150 Mbps for download and 75 Mbps for upload. It has the flexible bandwidth of 6 different bandwidths. In the post What is LTE, 4G Technology and LTE Advanced, you can read more about LTE features, but also about the new LTE Advanced standard.
Since LTE doesn’t have different bearers for voice calls and internet access, it needs to handle the voice calls on completely different way than 2G and 3Gnetworks. The post Voice over LTE (VoLTE) – the New Features in the LTE describes how the phone calls are handled in the LTE networks.
The leader in the LTE technology is the Ericsson. Read more about the Ericsson LTE technology and product in the article Evolved Packet Core.