Optimisation of Performance of 4G Mobile Networks in High Load Conditions

The signalling subsystem of the LTE (Long Term Evolution) networks inherited some of the limitations of its preceding technologies. It is vulnerable to overload situations that occur as a consequence of unpredicted user behaviour. The most sensitive zones are the paging procedure and random access procedure and the signalling channels associated with them. Reliable paging procedure is particularly important. As of the current design, in case of overload of paging channels it blocks the possibility of modification of configuration of a cell, thus limiting the possibilities of the system to recover. This research proposes and analyses a solution to overload of the paging channels in LTE systems. It shows that there is a possibility to completely avoid overload of the paging channels in surging load conditions. The research develops and verifies a mathematical model of the paging procedure. This model is incorporated in the solution, thus allowing computation of the critical load thresholds that trigger the reconfiguration of the paging channels. The solution is explained by a detailed algorithm and validated in a simulator of the LTE paging channels. It is partially compliant with the 3GPP specifications. The research includes a compatibility analysis and underlines the operational procedures that must be defined in the standard. It is important that the implementation of the solution does not affect already deployed hardware but requires a modification of the eNb software. Thus it is possible to prevent development of the paging overload situations, and the solution can be implemented in the hardware that is already deployed in the LTE networks. The main result of this research is a reliable paging procedure that opens further opportunities for optimisation of other signalling procedures and channels.