An Evaluation of High-Definition Voice Calls over IMS throughout handover procedures

Abstract

In mobile networks, handover refers to the process of transferring communications, data and radio resources of the mobile user while maintaining the Quality of Service (QoS) of High-Definition (HD) voice calls. Often, this process occurs from a serving cell to a neighbor cell based on the received signal power reported by the User Equipment (UE) to the Base Station (BS). The main contribution of this work is a guideline to evaluate an intra-LTE handover procedure and QoS metrics during a Voice Call over LTE (VoLTE) considering the X2 communication interface and handover decision algorithm based on Reference Signal Received Power (RSRP) values provided by a real-time experimental setup. Furthermore, packet analyzer software was used to collect the packets in real-time execution. In addition, the UE was set to record events that help us to track all the system activity with the mobile core network and monitor the performance. Therefore, received power levels were collected along the voice call, allowing a deep analysis of the QoS and signal level metrics. The results show how the handover procedure impact into QoS, generating an interruption gap during the signal measurements by the UE. In contrast, the results about QoS and signal level metrics satisfy the requirements during the VoLTE call.