Delay and quality metrics in Voice over LTE (VoLTE) networks: An end-terminal perspective

In this paper we evaluate metrics specified in 3GPP to characterize trade-offs between delay and quality of Voice over LTE (VoLTE) mobile phones in various network conditions. We report test results on clock accuracy, terminal delay in uplink and downlink under error-free conditions, as well as delay and quality in the presence of packet losses and network jitter. We discuss how the underlying methodology intended for delay testing can be extended to evaluate de-jitter buffer performance using a black-box approach, and how to model VoLTE packet delay/loss characteristics in a realistic way.