LTE Architecture Overview

There are broadly two parts to the network – the Access Network which communicates with the end devices – IoT sensors and controllers, and the Evolved Packet Core which handles all the routing, switching, registration, and interfaces with the IoT Core Platform and IoT Application Platforms (which in LTE terminology are located in the PDN (Packet Data Network).

Access Network

eNodeB’s/MBB

Mobile Broadband LTE Radio access node – base station which receives/transmits RF to end devices (User Equipment, UE).

Evolved Packet Core

MME – Mobility Management Entity

The MME is the main control-node for the LTE access-network. It handles the connection of the end device (User Equipment (UE)) to the network. It provides many funtions including:

  • Registration,
  • Activation,
  • Authentication (in conjunction with the Home Subscriber Server (HSS),
  • Security key management
  • Roaming functionality (in conjunction with the Serving Gateway S-GW).
S-GW – Serving Gateway

The Serving Gateway is basically a router and packet forwarded for the network.

It provides the following functions:

  • Routes and forwards user data packets
  • Mobility anchor for handovers between eNodeB’s and other networks.
  • For idle state User Equipment, the Serving Gateway terminates the downlink data path and triggers paging when downlink data arrives for the User Equipment.
  • It manages and stores UE contexts, e.g. parameters of the IP bearer service, network internal routing information.
  • It also performs replication of the user traffic in case of lawful interception.
PGW – Packet Gateway

The PWG is the Packet Data Broker – handling all user data packets between the End Device (UE) and the IoT Application Platform.

HSS

The Home Subscriber Server is a central database that contains user-related and subscription-related information.

PCRF – Policy & Charging Rules Function

The PCRF provides:

  • The ability to manage network and subscriber policy in real time.
  • The ability to efficiently and dynamically route and prioritize network traffic.
  • Unified view of subscriber context based on a combination of device, network, location and billing data.
  • Key inputs to revenue assurance and bandwidth management.

For further details, refer to the complete description here.

Notes:

By Joe Deu-Ngoc – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=37142420