Session negotiation and media adaptation of EVS in Voice over LTE

EVS is expected to fill the large gap between the quality and capacity currently available and those expected for 4G, and beyond, mobile communications systems. The large bit-rate and bandwidth ranges, and the complex structures of the new codec make it challenging to deploy and operate. In this paper, we explain how EVS is systematically integrated into the VoLTE ecosystems, outlining session negotiation procedures in which QoS is agreed between two UEs via IMS, and media adaptation procedures in which a controlled compromise is achieved between voice quality and error resilience when the link quality deteriorates or the radio resource runs out.