# Enabling Autonomous Agents for Mobile Wireless Sensor Networks
## 6 Tests and Results
### Results  
An overview of the results is presented in Figures 5-10. Figure 5 presents the final state in the network for two SPF tests--Subplots a and b--with the extreme values regarding cohesion forces (SPF4 and SPF10, with SPF4 being the weakest and SPF10 the strongest). The two subplots below, Subplots c and d, show the effect of the cohesion forces in the Agents ALG2 algorithm. On the left side, the lack of cohesion forces leads to the isolation of some nodes, whereas the subplot on the right includes a cohesion force, showing a uniform node distribution across the network without isolating nodes. A matter of interest is represented in the battery state (color gradients) that the nodes exhibit between the different approaches. A step imbalance can be perceived at the battery depletion in the SPF tests, where some of the nodes, especially those at the boundaries, comparably spend way less battery than the others. On the contrary, the Agents balance the battery expenditure uniformly. A graphical representation related to the evolution of the different tests is given in Figure 6. In this figure, the evolution in coverage is compared with the elapsed time, also highlighting the relevance of the crucial parameter \(\alpha\). All of the SPF-only tests demonstrate temporary certain coverage blackouts around 40 days of simulation time, regardless of whether a stronger cohesion force is employed (_spf10_) or a weaker cohesion force (_spf4_). The reason for the blackouts is due to how the cohesion forces operate, as they are directly proportional to the number of depleted nodes, among other parameters; Equation (16). Since the SPF strategy relies only on the cohesion forces as attractors to balance the network, there are moments where the distance between nodes is greater than the coverage radius, causing partial disconnections. In the Agents' case, no communication outages can be perceived, showing a better overall stability (except for the test without cohesion forces, where a step loss in coverage can be seen towards the simulation end). The presence of dropouts in coverage can provide misleading conclusions if only the final lifespan is regarded. This is due to the routing algorithm and the battery simulation related to it. As unconnected nodes do not forward neighbors' traffic, unconnected nodes spend less battery during a network simulation cycle, making the network artificially last longer. In this case, although the network has a greater lifespan, it is less usable than more stable alternatives. For this reason, different checkpoints are established to evaluate the merits of each approach at different simulation times. These values are obtained through ANOVA-1 analysis of the 30 simulations that take place for every test, ensuring the statistical significance of our results. \begin{table}
\begin{tabular}{c c c c} \hline
**Algorithm** & **Nomenclature** & **Alpha** & **Simulation Runs** \\ \hline \multirow{4}{*}{SPF} & SPF4 & 4 & 30 \\  & SPF5 & 5 & 30 \\  & SPF6 & 6 & 30 \\  & SPF7 & 7 & 30 \\  & SPF10 & 10 & 30 \\ \hline \multirow{4}{*}{Agents} & alg0 & 1.6 & 30 \\  & alg1 & 1.6 & 30 \\  & alg2 & 1.6 & 30 \\  & alg2 sc & 0 & 30 \\ \hline \end{tabular}
\end{table} 
Table 3: A summary of the different tests carried out. A proposed milestone covers the event when half of the initial nodes have depleted. Because the simulations comprise a number of 100 robots, this event is evaluated when 50 nodes have run out of battery. Figures 7 and 8 represent the time needed to reach that event and the coverage with this number of nodes. In the Agents approach, a clear advantage in efficiency is shown with respect to the SPF approach. Every algorithm in the Agents strategy takes at least a median value for 80 days to deplete 50 nodes, whereas the SPF-only strategy takes, in the best scenarios, less than 75 days, even approaching  
Figure 5: Battery levels (color gradient from green to red), network liveliness and connection diagram for the final state. Tests: (**a**) SPF4, (**b**) SPF10, (**c**) ALG2 sc, (**d**) ALG2.