# A _uv_-Cellular Network: Design, Implementation and Experiments
## 5 Experiments Study
### Performance Metrics & Experiment Results
#### 5.3.2 Test for Throughput  
_Throughput_ represents the amount of data that passes through a network or interface per unit of time, including all uploaded and downloaded traffic. This set of experiments \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Test Data Link** & **Source Node** & **Destination Node** & **Number of** & **Amount of Data** & **Network Packet** & **Data Rate** \\  & & & **Hops** & **(bit)** & **Delivery Fraction** & **(bps)** \\ \hline Between terminal nodes and & AUV 01 & Surface Gateway Node & 3 & 144,936 & 80.5\% & 574.1 \\  & USV 21 & Surface Gateway Node & 2 & 57,096 & 92.9\% & 588.6 \\  & Terminal Node 33 & Surface Gateway Node & 2 & 87,840 & 90.9\% & 625.4 \\ \hline Between terminal nodes & USV 11 & Terminal Node 12 & 2 & 17,560 & 93.3\% & 675.4 \\ within the same subnet & Terminal Node 23 & Terminal Node 24 & 2 & 21,560 & 100.0\% & 718.7 \\ \hline Between terminal nodes & AUV 01 & Terminal Node 22 & 5 & 10,848 & 78.6\% & 542.4 \\ in different subnets & Terminal Node 23 & Terminal Node 34 & 4 & 9336 & 92.7\% & 666.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Data rate test results for different data links. Figure 12: The possible attitudes of AUVs in the underwater. (a) the pitch of AUV is positive. (b) the pitch of AUV is negative. tested the network throughput under different network load conditions. In each group of tests, the Minimum of 1 and maximum of 3 terminal nodes in each level 1 subnet. The test results can be seen in the Table 3.  
Figure 13 illustrates the results of each test group. Regardless of network load, throughput test results indicate significant changes, with the lowest throughput below 350 bps and the best throughput over 750 bps. It is due to the fact that the performance of UWSNs is significantly affected by the underwater communication environment. During the test, when the environment is stable, the network can reliably send and receive packets, allowing for high throughput. However, persistent and severe environmental changes resulted in a considerable fall in communication success rates and negative impact on the results of network performance test which is difficult to eliminate by optimizing network protocols. During this field test, CTD data and AUV navigation data were collected as shown in Figures 14 and 15. By adjusting the size of the sensor data and the frequency of data production, we can obtain underwater information in real time. At the same time, some network nodes are also equipped with underwater cameras to take and transmit the underwater pictures. As the transmission of the original image would consume limited bandwidth resources of underwater communication, in this case study, we have used image compression and reduction techniques to reduce resource consumption while retaining the basic information of the image. The following Figure 16 shows the underwater pictures. Figure 13: The records of the throughput field test. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Network Load** & \begin{tabular}{c} **Amount of** \\ **Data (bit)** \\ \end{tabular} & \begin{tabular}{c} **Data Latency** \\ **(s)** \\ \end{tabular} & \
\begin{tabular}{c} **Network Packet** \\ **Delivery Fraction** \\ \end{tabular} &
\begin{tabular}{c} **Average Throughput** \\ **(bps)** \\ \end{tabular} \\ \hline One Terminal Node & 290,464 & 490 & 85.7\% & 592.783 \\ in Each Subnet & 489,623 & 868 & 80.6\% & 564.081 \\ \hline Three Terminal Node & 612,588 & 1111 & 71.7\% & 551.384 \\ in Each Subnet & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Throughput test results under different network load conditions. In this case study, we deployed the large-scale \(uw\)-Cellular network in a real-world environment and the experimental results showed that the Data Rate between any nodes could reach above 500 bps, and the network Average Throughput was no less than 550 bps under various load situations. The mobile node can choose the relatively optimal path to transmit data according to the routing strategy proposed in this paper.