VoLTE Optimization

Long‐term evolution (LTE) radio is designed for the packet connections without any support for circuit switched (CS) connections. This chapter presents the different voice options including CS fallback and voice over LTE (VoLTE) and discusses the VoLTE optimization. It illustrates the timing and the main differences of the voice options. The first LTE smartphones used dual radio solution where the terminal included two parallel radios: one for CDMA voice and another for LTE data. When the terminal runs out of LTE coverage area and maintaining an ongoing VoLTE call becomes difficult, evolved packet system (EPS) VoLTE bearer connection can be handed over to CS connection in 3G or 2G network. The procedure that provides the means to the handover is single radio voice call continuity (SRVCC). SRVCC handover triggering points need to be carefully designed in order to maintain the high voice quality, low handover delay and high success rates.