Patent ID: 8681740

Claim:
A method for monitoring a Long Term Evolution (LTE) mobile telecommunications network during user equipment mobility, the LTE mobile telecommunications network having User Equipment in radio communication with an Evolved Packet Core (EPC) having a first mobility management entity (MME) in communication with a Home Subscriber Service (HSS) by a S6a interface, the EPC interfacing with an evolved Universal Mobile Telecommunications System Terrestrial Radio Access Network (E-UTRAN) having a plurality of enhanced NodeBs interconnected by X2 interfaces and a Serving GPRS Support Node (SGSN) communicating with the MME via a S3 interface, and the EPC having a second MME communicating with the first MME via a S10 interface, the method comprising the steps of: providing a network monitoring system for capturing and analyzing Packet Data Units (PDUs) from a subset of network interfaces in the LTE mobile telecommunications network; identifying, at the network monitoring system, first context data associated with a first user on S1-MME interfaces between the MMEs and a first enhanced NodeB in the E-UTRAN and S6a interfaces between the MMEs and the HSS, wherein the network monitoring system is connected to the S1-MME interfaces, the S6a interfaces, the S10 interface, the S3 interface, and the X2 interface; identifying a source identifier, a destination identifier, a Key Access Security Management Entries (K ASME ) key and an enhanced NodeB (K eNB ) key for the first user from the first context data; deriving, at the network monitoring system, one or more next hop parameters for first user equipment from the K ASME and K eNB keys; and creating a first context entry for the first user in a table, the first context entry comprising the source identifier, destination identifier, K ASME key, K eNB key, and the one or more next hop parameters for the first user so that the network monitoring system tracks and correlates the K ASME and K eNB keys during handover from one of the eNBs to another of the eNBs by the network monitoring system only monitoring the S1-MME interfaces and the S6a interfaces, wherein the tracking and correlation allows deciphering traffic after handoff.