Architecture of LTE

There are three main components in the Architecture of LTE, UE, EUTRAN and EPC. The evolved packet core communicates with the external Internet entities such as IMS, Private and corporate networks. The UE, EUTRAN and EPC have their own internal architectures that will be explained in detail in the later sections. The interfaces between different parts of the system are denoted as, interface between UE and eNB as Uu, Interface between eNB and EUTRAN as S1 and interface between EPC and external network as SGi.

Architecture of LTE 

  • User Equipment (UE)
  • Evolved UMTS terrestrial radio access network  (E-UTRAN)
  • Evolved Packed Core (EPC)

User Equipment (UE)
User equipment is typically divided into two components Mobile termination (MT) and Terminal equipment(TM).  The mobile termination handles all the communication functions and the terminal equipment handles all the data. All the communication between the UE and EUTRAN occurs with the help of the SIM card module inside the UE. The SIM card runs an application that is known as Universal subscriber identity module (USIM). The USIM stores user’s data such as Phone number, Mobile country code and the Mobile radio network operator information. The USIM also supports various security related features that help UE to connect to LTE networks. For example during the Initial LTE attach procedure the UE generate keys that help to authenticate the UE in LTE network.
LTE network supports both IPv4 and IPv6 or dual stack IP versions (Both IPv4 and IPv6 simultaneously). In LTE, UE can have either IPv4 or IPv6 for different networks it connects. A mobile can have both IPv4 and IPv6 address simultaneously if the mobile operator and the UE support both address. The Mobile units can have wide ranges of radio capabilities such as Maximum data rates, number of frequencies supported, Carrier aggregation etc. A UE category has been developed that helps to differentiate different versions of radios capabilities in UE’s. It mainly covers the Maximum data rate that a mobile can send and receive.

UE catageories

These high data rates are achieved using combining different spectrum's to achieve maximum bandwidth which is also known as Carrier aggregation. The process of CA will be explained in upcoming posts.


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