Congestion-based automatic calling for improving call establishment in VoLTE

Through the introduction of LTE (Long Term Evolution), which is a next-generation radio access network, the traditional circuit switching system in cellular telephony networks is migrating to VoLTE (Voice over LTE). Although LTE can provide high quality and high bandwidth, the call processing capacity of a VoLTE system is designed for normal traffic density, as is the traditional cellular network. However, its performance, measured by the successful call rate, deteriorates when overwhelmed by the large number of calls generated by the special circumstances such as large gatherings and disasters. At such times, users continue to retry calls until the call goes through, resulting in additional degradation of system performance. In this paper, we propose a novel method to improve performance in such circumstances by placing a hold on calls that are likely to fail, and automatically making those calls in IMS (IP Multimedia Subsystem), which is the main call-control function in VoLTE. Finally, we present a simulation of our proposal that demonstrates its effectiveness when users are persistent with their calls.