# Hardware Mechanism for Energy Saving in WiFi Access Points
## 3 Experimental Results: Testing our Mechanism  
The calibration of the parameters (\(w\)) identified in Section 2 took us around 2 months (4 h per day approximately) because it was a complex process. About 20 tests were executed, with different types of batteries and voltage adapters. In the first test we searched for safety values of current and voltage supply for the _Ruckus AP_ which only transmitted signaling WiFi beacons (no user data). We found \(46.2\leq V\leq 46.7\) V and \(0.03\leq I\leq 0.41\) A. Figure 6 shows the voltmeter (volt), and amperemeter (amp) measurements (46.5 V and 0.05 A). Those measurements were the ones with which the Ruckus AP was able to work. The measurements were done connecting tips of red cables of the volt and the amp to the positive (+) orange cable of PoE. The tip of black cable of the Volt was connected in the joint of negative poles of PoE (illac cable) and Ruckus AP negative RJ45 cable (brown). The tip of a black cable of amp was connected to a positive cable of RJ45 of the Ruckus AP (blue).  
Find out the high and minimum working values of \(V\) and \(I\) for the Ruckus AP, we tested the time evolution of the charging current and voltage of the chosen battery in standalone. We did this to confirm the theoretical values found in the literature, to observe correct working of the charging process and to observe particular details of that battery. Initially the battery had a vacuum voltage (before starting the charging) of 12.15 V (Figure 7). After a rapid growth (slope of 0.253), at 3 m, the \(I\) reached the maximum value of 1.27 A. That maximum value was maintained for a very short period of time. Then a prolonged fall was produced until 240 m when \(I\) reached 0.02 A. In that period of time \(V\) reached 14.19 V. We considered that in 240 m the battery was charged, but we continued measuring the \(V\) and \(I\) until 360 m. In that period the \(I\) maintained constant and \(V\) increased 0.03 V.  
Determining \(V\) and \(I\) for the _Ruckus AP_ only transmitting WiFi beacons and the characteristics of \(T_{c}\) for the battery in standalone, we designed and tested two different kind of experiments for verifying our formal model and that energy saving was possible with our mechanism:  
* _Analysis of the \(T_{c}\) using our mechanism_: the objective was to analyze the behavior of the battery charging current and voltage when the supply \(S\) energized the _Ruckus AP_ and the battery simultaneously. We observed the behavior of \(I_{c}\), \(V_{c}\), \(I_{a}\) and \(V_{a}\).
* _Analysis of the \(T_{d}\) using our mechanism_: the objective was to analyze if the _Ruckus AP_ could work being energized by \(B\) and to determine \(T_{d}\). We observed the behavior of \(I_{d}\) and V\({}_{d}\).  
The experiments were conducted maintaining the Ruckus AP transmitting only beacons. The shape of the current and voltage curves in the experiments behaved similarly. The differences arised from the initial value of current and voltage and in minor proportion with the particular conditions of the WiFi network channel. We next present the two most different found experiments (we code the experiments as OBTx-1 and OBTx-2 from now on).  
Figure 6: Measuring current and voltage supply to the AP alone and only transmitting beacons.