Technical vulnerability of the E-UTRAN paging mechanism

The signalling subsystem is the most expensive and complex element in cellular networks. Today´s networks use signalling mechanisms whose design builds on more than 20 years of the operational expertise. Despite this, the signalling subsystem of all mobile network standards remains vulnerable to failures of equipment and to sharp increases in offered load caused by unanticipated traffic patterns. In this work we analyse the technical vulnerability of paging - a key signalling mechanism that is responsible for notifying mobile terminals of downlink service requests. Our assessment considers the operation of Long-Term Evolution (LTE) networks and in particular the performance of the paging mechanism on the radio interface. We implemented the paging procedure in a simulator, and we propose and verify a mathematical model of the system behaviour. The proposed mathematical model effectively captures the non-zero threshold of paging failure probability; it is scrupulously precise for the paging loads below the nonzero threshold and delivers a close approximation with the increasing paging load. The mathematical model can be applied to optimise the performance of the paging mechanism and to devise techniques able to overcome its technical vulnerability.