LTE: Definition of Emergency Area Id?

Question

It's a operator defined Id but When it is defined ? Does it has any relationship with 3GPP defined Geographical location like cell, TAI etc. It is configured by eNodeB itself or MME configures through any message .

Answer 1

Emergency Area Ids are defined in MME.
Both "Cell-ID list" or "Emergency Area ID list" serves to identify the location in Warning messages.
An Evolution node B (eNB) acquires an eNB -supported Emergency Area ID and an E-UTRAN cell global identifier (E-CGI) list included in it, and when S1 is set up, carries the acquired emergency area ID and the E-CGI list included in it in an S1 setup request message to transmit to a mobility management entity (MME); the MME stores the received emergency area ID and the E-CGI list included in it.