# SCHC over LoRaWAN Efficiency: Evaluation and Experimental Performance of Packet Fragmentation
## 6 Results
### Results with and without Processing Times  
To analyze how the processing time affects the channel occupancy efficiency, we defined two cases: case 1 does not consider the processing time defined in (4). Case 2 considers the processing time. For case 1, the time involved in sending 13 SCHC Fragment messages plus receiving a SCHC ACK is given by Table 5.  
Figure 7: Experimental vs. theoretical channel occupancy efficiency for each spreading factor. (**a**) Spreading factor 7. (**b**) Spreading factor 8. (**c**) Spreading factor 9. (**d**) Spreading factor 10. (**e**) Spreading factor 11. (**f**) Spreading factor 12.  
In particular, for the case of data rate 0, the time of a SCHC window is 66970 [ms]. This time involves an efficiency of 32%. Table 6 summarizes the best-case efficiency for the data rates used in this work.  
For case 2, Table 7 considers the same case as the previous paragraph, including the value of the processing time to calculate the channel occupancy efficiency. When processing  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\
\begin{tabular}{c} **Data** \\ **Rate** \\ \end{tabular} } & \multirow{2}{*}{**SF**} & \multicolumn{2}{c}{**Maximum**} & \multirow{2}{*}{
\begin{tabular}{c} **Physical Bit** \\ **Rate (Bps)** \\ \end{tabular} } & \multicolumn{2}{c}{**Total ToA (without** **Process Time)**} & \multicolumn{2}{c}{**Maximum Efficiency**} \\  & & & **Size (Bytes)** & & \\ \hline
0 & 12 & 51 & 250 & 66,970 & 32\% \\
1 & 11 & 51 & 440 & 50,197 & 24\% \\
2 & 10 & 51 & 980 & 38,493 & 14\% \\
3 & 9 & 115 & 1760 & 19,125 & 17\% \\
4 & 8 & 222 & 3125 & 11,030 & 18\% \\
5 & 7 & 222 & 5470 & 10,153 & 11\% \\ \hline \hline \end{tabular}
\end{table}
Table 6: Maximum theoretical channel occupancy efficiency in AU915 band (without process time).  
Figure 8: Channel occupancy efficiency. (**a**) Theoretical channel occupancy efficiency. (**b**) Maximum theoretical channel occupancy efficiency.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{\
\begin{tabular}{c} **Data** \\ **Rate** \\ \end{tabular} } & \multirow{2}{*}{**SF**} & \multicolumn{2}{c}{**
\begin{tabular}{c} **n\({}^{\circ}\) of Tiles in** \\ **Payload** \\ **Size (Bytes)** \\ \end{tabular} } & \multicolumn{2}{c}{**n\({}^{\circ}\) of Tiles in**} & \multicolumn{2}{c}{**n\({}^{\circ}\) of SCHC**} & \multicolumn{2}{c}{**n\({}^{\circ}\) of**} \\  & & **Payload** & **Rate (Bps)** & **Fragment** & **Fragment** & **Remaining** \\  & & **Size (Bytes)** & & **(Full Payload)** & **Files** \\ \hline
0 & 12 & 51 & 250 & 5 & 12 & 3 \\
1 & 11 & 51 & 440 & 5 & 12 & 3 \\
2 & 10 & 51 & 980 & 5 & 12 & 3 \\
3 & 9 & 115 & 1760 & 11 & 5 & 8 \\
4 & 8 & 222 & 3125 & 22 & 2 & 19 \\
5 & 7 & 222 & 5470 & 22 & 2 & 19 \\ \hline \hline \end{tabular}
\end{table}
Table 4: n\({}^{\circ}\) of Tiles and n\({}^{\circ}\) of SCHC Fragment messages for a SCHC window (630 bytes) for each data rate in AU915 frequency band.  
times are included, the channel occupancy efficiency for data rate 0 decreases from 32% to 15%, showing the importance of the processing time on the channel occupancy efficiency. Figure 8b shows the maximum theoretical channel occupancy efficiency with and without the processing time for each spreading factor.  
Figure 9 shows the maximum theoretical channel occupancy efficiency as a function of the SCHC window size (in bytes) and the spreading factor, using a processing time equal to zero, without packet loss.