Planning for Quality of Service for Voice over Long Term Evolution “LTE” network

Abstract

The LTE (Long Term Evolution) technology was introduced to reduce the DATA network latency, in addition to provide higher data throughput. But the packet based nature of LTE network prohibits the transmission of voice related services. VoLTE )Voice over LTE( is a solution to transfer voice packets with special treatment over the LTE network, and get benefits from its low latency and quality of services capabilities to have high quality voice services jointly provided by the EPC )Evolved LTE packet core( and the IMS )IP Multimedia Subsystem(. As VoLTE is a new emerging technology for network and devices providers and not matured yet, it has some limitations in providing all voice related services over LTE. Network initiated and user initiated USSD (Unstructured Supplementary Service Data) are not supported directly over VoLTE. CSFB (Circuit Switching Fall Back( is a temporary solution used to instruct the VoLTE device to fall back from the LTE domain to the 3G/2G CS (Circuit Switching( network domain to receive such USSD, then returning back again to VoLTE after completing the reception of the USSD. If the VoLTE network tried to push a USSD notification to a VoLTE subscriber who is engaged in one or more voice calls “conference call”, the commercial network settings will make that subscriber to release all the LTE bearers to fall back to the CS network which causes the drop of all active calls owned by that VoLTE user, which affects negatively on the most important VoLTE QoS (Quality of service) parameters which is service availability and VoLTE call retainability. This thesis introduces the investigation and development of design methodologies for the deployment of VoLTE network which requires strict