## 5 Evaluation
### Simulation Tests
For the original network, a 100% value is considered to mean that the original message contains itself the whole information content that must be transmitted. A value of less than 100% would mean that some content has been lost, and a value that is higher than 100% would mean that information has been enriched. A simple data processing application was simulated with eleven processing phases (0 to 10) that were defined, and every packet at the origin was sent with a zero value. The intermediate nodes performed PIN whenever the queue length was greater or equal to three packets, and the duration of each processing phase was 3 seconds. First, a new ProcessPhase field is added to the packet definition Figure 9). Figure 9: Definition of the ProcessPhase field. A new PINalarm field was also added to measure the preprocessing percentage. Values were captured whenever a packet was transmitted. In the application handlemessage class, the initial value for ProcessPhase is set to zero for every generated packet. A new checkpoint is added before a packet is added to the queue. PIN is initiated if the queue length is higher than 3 and the ProcessPhase is less than 10). We wrote a dummy ExecutePIN module (Figure 10), which considers that each phase reduces the byte length by 10 percent. We first attempted to send the packet to a different module (a PIN application module was added to the Network Description (ned) configuration, which is the topology description language for OMNET++), but we finally decided not to use this option because of the additional time that was added. We decided to include the PIN code within the queue module code. The results (Table 3) show that PIN reduced the queues (a lower number of queued packets and a lower average queueing time in most cases), and because of the reduced queuing time, there is an opportunity for having PIN at a zero cost. The numbers in the last column (Maximum PIN time for \(\text{cost}=0\)) were calculated by comparing how many packets and for how long they stay in the queues (qlen count multiplied by qlen time), between runs without and with PIN activated. The qlen count increment observed in the last case (extended fish) is because of the congested nodes. PIN helped to reactivate the network flow, and therefore, more packets started to move between the nodes, which caused this increment. The best PIN numbers (the preprocessing percentage and the maximum PIN time for a zero cost) were achieved in the most congested network. PIN adapts to the  
Figure 10: The ExecutePIN module. \begin{table}
\begin{tabular}{l r r} \hline \hline \multirow{2}{*}{**Network name**} & **Qlen count difference:** & **Qlen time avg difference:** & **Maximum PIN time for** \\  & **[packets (percentage)]** & **[seconds (percentage)]** & **cost = 0 [seconds per packet]** \\ \hline Net5 & –2 (–1\%) & –0.09317 (–47\%) & 0.09319 \\ Net10 & –460 (–36\%) & –0.006196 (–10\%) & 0.06423 \\ Fish & –674 (–61\%) & –0.16102 (–19\%) & 0.16613 \\ Extended fish & +31,870 (+726\%) & –787.61389 (–50\%) & 682.00842 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: PIN benefits and costs. network conditions at every moment. PIN does almost nothing in a non-congested network, but as the load increases, it appears to compensate for the waiting times at the routers. The experiment was also useful to show that information was delivered with a certain degree of pre-processing. The Pre-Processing Index numbers are shown in Figure 11.  
Our experiments show that 10% pre-processing levels could be obtained, but this number is with regards to the specific topology and network conditions in the experiment. In a real scenario this number may be less, but also conceivably much higher (even 100%) depending on the topology, traffic, and network conditions. Only the pre-processing and simplification of information functionalities were simulated in the experiment. Information fusion techniques were not included in the experiment. It is expected that this element could contribute significantly to enhance the PIN benefit numbers.