## Conclusions: Low Temperature
### High Temperature: \(22\,^{\circ}\)C-\(40\,^{\circ}\)C
#### 7.3.3 A2t-Ftsp  
Once both FTSP and AT-FTSP have been analyzed, this set of experiments end with the results of A2T-FTSP for high temperature ranges. For the temporal range without temperature change (\(0\) s-\(1,000\) s), A2T-FTSP has a good behavior and a better average synchronization error (\(1.1\)\(\mu\)s). Nevertheless, after applying a temperature variation on the nodes, the average synchronization error increases drastically, producing a peak average synchronization error of \(4.25\)\(\mu\)s. After this situation, A2T-FTSP starts to apply the new clock skew method, decreasing the average synchronization error gradually, until the end of the test, where the error returns to similar values compared to the first temporal interval. The test ends with an average synchronization error of \(2.609\)\(\mu\)s. The improvement with respect to FTSP is clear, amounting to \(184.86\%\). **Conclusions: High Temperature**  
The tests carried out with FTSP, AT-FTSP and A2T-FTSP (see Figure 8) show an improvement of the new approaches when compared to the original FTSP version. In the following section, the main contributions of these tests are listed:  
* High temperatures penalize, to a large extent, the behavior of the synchronization methods. All the tests have demonstrated the above mentioned penalization in the average synchronization error. * Once again, the use of the temperature-sensitive clock skew module allows one to reduce the average synchronization error by using a basic temperature sensor. Both AT-FTSP and A2T-FTSP improve the behavior and the average synchronization error between \(159.40\%\) and \(184.86\%\). **8. Comparison to Previous Approaches**  
This section compares the new proposals of this work with the algorithms described in Section 2.2 (see Tables 6 and 7). As a reference, the TCTS and EACS algorithms were chosen, because (i) these  
Figure 8: Behavior study: \(22\,^{\circ}\)C–\(40\,^{\circ}\)C.  
synchronization protocols take into account temperature variations, (ii) are based on obtaining the clock skew of the nodes to improve the synchronization process and (iii) are designed to be used in WSNs. It is out of the scope of this work to readapt TCTS and EACS algorithms to the experimental TelosB testbed described in this article, due to the complexity of the task. Therefore, only the results provided in the original articles are compared in this work. Nevertheless, the comparison is hard to obtain, because of the experimental setups designed by their respective authors. Those experiments tried to obtain large resynchronization periods instead of looking for decreasing the average error with microsecond accuracy for static synchronization periods. For the EACS scheme, the authors provided simulated and experimental results. During the whole \(8,000\) s simulation, the error was always below \(2\) ms. On the other hand, for the experimental setup with Mica2 motes, the error was always below \(8\) ms over the \(7,200\) s test duration. The authors established that resynchronization periods for simulation can be prolonged more than \(1,500\) s, while the resynchronization period can be enlarged to around \(1,000\) s, with a \(1\) ms resynchronization threshold. Therefore, the frequency stability of this virtual clock with an error of \(8\) ms in a period of \(1,000\) s was \(8\) ppm. [PERSON] _et al._[12] carried out simulated experiments. Results show that TCTS, on the average, has an average beacon interval of \(329\) s, and \(95\%\) of the errors lie within \(\pm 4\) tics of a \(32\) KHz clock