LTE provides detailed identification and naming values for various entities, that is, users MSs, eNBs, service areas, etc. In the following, we briefly summarize these LTE functionalities.
To identify mobile subscribers, LTE assigns a unique identification called the International Mobile Subscriber Identity (IMSI). The Mobility Management Entity (MME) assigns a Temporary Mobile Subscriber Identity (TMSI) to each visiting mobile subscriber in order to maintain the subscriber's confidentiality. A TMSI assigned during the network access is called the Globally Unique Temporary Identity (GUTI). The home MME correlates the allocated TMSI with the IMSI allocated to the mobile subscriber. If the GUTI is not available to provide unique identification, the serving MME requests the IMSI of the UE using a non-access-straturm procedure. This procedure is shown in Figure 10.5.