# A Multi-Parameter Comprehensive Optimized Algorithm for MPTCP Networks
## 6 Conclusions and Outlook  
In this work, we utilize our multi-parameter comprehensive optimized algorithm (MPCOA) algorithm proposed in Section 3, trying to obtain optimized multi-performance parameter output in MPTCP networks. The results of three scenarios involving six sites of the multi-homed NorNet Core testbed in Section 5 show that it is feasible to increase the network performance by choosing appropriate PM and CC and setting reasonably small buffer size. Using the MPCOA algorithm can improve the throughput and reduce the waste of buffer resources. Actually, the MPCOA algorithm first tries to find the minimum BS, appropriate CC algorithm and PM algorithm while maximizing the throughput. However, if the throughput is maximum, the corresponding BS is usually not the minimum. In this case, the algorithm will seek the minimum BS in a certain range of maximum throughput, and find the minimum size of BS by sacrificing \(\delta\) throughput. Through repeated experiments in multiple scenarios, we can draw four useful conclusions: (1) for homogeneous networks, the path management algorithm can choose FullMesh directly; (2) for heterogeneous networks, PCDC can be directly used for path management; (3) \(\delta\) generally takes the empirical value of 7%. If the buffer resource is tight, a larger \(\delta\) can be selected. If the communication scenario has sufficient buffer resource and requires higher throughput, \(\delta\) can be set smaller, or even set to 0; (4) when the MPCOA algorithm is used in practice, because regression modeling takes a long time, we can directly set the buffer size according to 50% of the traditional solution, which can greatly save time. Of course, this is only a compromise due to the current lack of computing power.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Scenario** & **Optimized Solutions** & **Traditional Solutions of BS** \\ \hline SRL-HU & \(OPM=\) PCDC, \(OCC=\) Hybla, & \(B\geq 329\) MiB (\(RTT_{\max}=1.800\) s, \\  & \(OBS=12.36\) MiB, \(OTP=74.65\) Mbit/s & \(RTO_{\max}=2.000\) s) \\ UNIS-HiN & \(OPM=\) PCDC, \(OCC=\) Cubic, & \(B\geq 54\) MiB (\(RTT_{\max}=0.020\) s, \\  & \(OBS=9.22\) MiB, \(OTP=266.66\) Mbit/s & \(RTO_{\max}=1.000\) s) \\ UiT-HAW & \(OPM=\) FullMesh, \(OCC=\) Scalable, & \(B\geq 1.22\) MiB (\(RTT_{\max}=1.800\) s, \\  & \(OBS=0.50\) MiB, \(OTP=0.81\) Mbit/s & \(RTO_{\max}=2.000\) s) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Solutions for three scenarios.  
As part of our ongoing and future work, we are going to further observe the usage of the sacrificing factor \(\delta\) for different corner scenarios, and analyze more corner cases, such as the examined inter-continental setup with its very dissimilar paths and highly volatile path characteristics. Furthermore, we are working on the impact of the MPCOA path manager on bottlenecks and scheduler policies to maximize MPTCP's performance benefits in heterogeneous networks.  
Conceptualization, X.Z. and T.D.; methodology, M.C.; software, M.W.R. and T.D.; validation, M.C., and X.Z.; formal analysis, M.C., X.Z. and T.D.; investigation, Y.T.; resources, M.W.R. and T.D.; data curation, M.W.R. and Y.T.; writing--original draft preparation, M.C. and M.W.R.; writing--review and editing, M.C. and X.Z.; visualization, M.W.R.; supervision, X.Z. and Y.T.; project administration, X.Z. and M.C.; funding acquisition, M.C. and X.Z. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the National Natural Science Foundation of China under Grant No. 61662020, and in part by the Hainan Provincial Natural Science Foundation of China under Grant No. 620 MS023, in part by the CERNET NGI Technology Innovation Project under Grant No. NGII20160110, and in part by the Research Council of Norway (Forskingsradet, No. 208798/F50).  
Not applicable.  
The authors would like to thank the editors and the reviewers for their valuable time and constructive comments.  
The authors declare no conflict of interest.