# Practical Performance Analyses of 5G Sharing Voice Solution
## 6 Conclusions  
In this paper, all the results presented are based on commercially available NSA/SA shared networks. Firstly, we investigated the basic architecture of 5G sharing. Subsequently, an achievable theoretical solution of the voice service under different evolutionary stages was conducted: VoLTE at the NSA sharing stage, EPS fallback at the early stage of SA sharing, and VoNR at the SA sharing maturity stage. After theoretical analysis, the NSA sharing VoLTE setup delay is about 2.0-3.0 s, the EPS fallback setup delay based on handover or redirection is about 3.0-4.0 s, and SA sharing VoNR setup delay is about 1.5-2.0 s.  
Realistic testing environments of this study were built based on widespread equipment suppliers in the first live commercial 5G sharing networks. We thus conducted field tests on each solution. The performance of VoLTE in both back-to-home and non-back-to-home construction solution was verified in the NSA sharing VoLTE stage. Both are technically achievable. It is found that the VoLTE at NSA is not much improved compared with 4G, all around 2.2-2.8 s, which is consistent with the theoretical analysis value. There is almost no difference in delay between the contractor and the sharer, and sharing brings no additional difference in experience. The back-to-home solution is slightly worse than the non-back-to-home solution in terms of delay, which is brought about by the additional handover, with the handover delay of a single-end UE being around 35 ms.  
In EPS fallback test, it was first verified that EPS fallback can be achieved based on either handover or redirection. Therefore, in the initial stage of SA network construction, EPS fallback is a practical voice solution. The average setup delay is about 3.1 s for handover-based EPS fallback and about 3.9 s for the redirection-based version. This is consistent with the theoretical analysis. The average setup delay based on redirection is relatively high. Thus, from the perspective of delay, it is more highly recommended to deploy handover-based EPS fallback.  
In the SA sharing VoNR test, the average VoNR setup delay was obtained at about 1.9 s. Compared with EPS fallback, it was reduced by about 1.1 s, the VoNR control plane delay was shorter, and the MOS value was higher, which verifies the superiority of VoNR. Meanwhile, at the 4/5G border, it was verified that VoNR can switch to VoLTE to ensure the continuity of voice service and saved 33 ms compared to EPS fallback.  
In summary, the paper provides a variety of solutions to improve voice services in different evolutionary stages of 5G sharing networks. From the theoretical and practical analysis, it can be verified that EPS fallback can only be deployed as a transition solution. VoNR as the ultimate voice solution can bring the lowest access delay, further simplify the implementation process, and improve the best voice quality. Operators worldwide can deploy as needed based on the current network.  
Due to factors such as network load and lack of users, the research is not comprehensive enough. This is where the follow-up improvement of this paper is needed. The subsequent work of the paper includes research on how to further improve VoNR quality and call performance, a detailed evaluation of call jitter, packet loss error rate, etc.  
Conceptualization, W.X.; methodology, W.X.; validation, X.L. and M.W.; formal analysis, X.L.; investigation, X.L.; resources, X.L.; data curation, X.L. and M.W.; writing--original draft preparation, X.L.; writing--review and editing, X.L. and M.W.; supervision, W.X.; project administration, W.X.; funding acquisition, W.X. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the major research project of China Telecom \"5G co-construction and sharing end-to-end networking scheme and key technology research\". Funding number: 20 HQBYYF0026-001.  
**Data Availability Statement:** Exclude this statement.