# Practical Performance Analyses of 5G Sharing Voice Solution
## 1 Introduction
IMS-based voice over new radio (VoNR), as the target voice solution for operators, can fully utilize the advantages of high spectrum utilization, fade resistance, high bandwidth, and high capacity of 5G wireless technology. It provides users with shorter voice access latency and an ultra-high definition communication experience [14]. VoNR is the target voice solution for 5G networks [15]. However, in the early stage of network construction, constrained by the low penetration of 5G UE, insufficient network coverage, and the long-term coexistence of 4G and 5G, the premature scale deployment of VoNR will bring frequent 4/5G handover. Handover is the basis for service continuity in mobile networks, supporting the movement of UE between different base stations or access points (AP) provided with multiple access technologies [16]. The frequent handover will increase delay and affect user experience. In the last decade, many investigations on handover cases have also been conducted. According to the studies, refs. [17; 18; 19] focus on handover efficiency. Ref. [20] focuses on handover tools and architectures. However, there is no research analyzed so far for the voice handover performance of 5G network-sharing architecture under different evolutionary stages. Frequent handover increases time delay and introduces user security issues that affect the user experience. The related state-of-the-art communication and data-sharing security studies are analyzed in [21; 22; 23]. This paper focuses on the time delay caused by handover. In different stages of 5G evolution, with different network structures and deployment scales, how to develop 5G voice solutions that meet the network deployment route and improve call quality is one of the important issues that urgently need to be solved. In the 5G NSA deployment phase, long-term evolution (LTE) and NR are used in dual-connection mode. 5G NR is added to the existing 4G network as a capacity extension. Following the 4G EPC, the 4G network remains the primary control network. 5G NRsupports only best-effort data transmission. Voice is guaranteed service continuity via voice over long-term evolution (VoLTE). The performance of VoLTE was studied in [24]. When evolving to 5G SA network sharing initially without VoNR feature, voice services can be a fallback to 4G LTE network with the help of EPS fallback as a temporary transition solution. Similar to CS fallback in the 4G era, under EPS fallback, the 5G NR network does not provide voice services [25]. The handover/redirection is initiated by the 5G base station (gNodeB) to the 4G core network (EPC), and the UE falls back to the 4G network, where the delay will be increased. As 5G SA networks mature, voice services can be carried by 5G with VoNR. All services are carried through the 5G network, but the voice needs to be controlled by IMS. Under VoNR, the UE resides in the 5G network, and both voice and data are carried in 5G. In poor-coverage areas of 5G signal, 4/5G handover-based interoperability can be achieved, and the LTE networks provide voice services. Similar to the single radio voice call continuity (SRVCC) of 4G, the VoNR also supports smooth handover between VoNR and VoLTE through the Inter-RAT handover mechanism [26]. The remainder of the paper is organized as follows. Section 2 introduces the motivation and contribution. Section 3 investigates the technical details of the 5G access network-sharing solution. In Section 4, the call setup flow of VoLTE under NSA sharing, EPS fallback, and VoNR under SA sharing are investigated. Section 5 provides the experimental results and analysis of VoLTE, EPS fallback, and VoNR. Section 6 summarizes the conclusion.