## 5 Conclusions and Future Works  
In this paper, we investigated beamforming, single-hop, multi-hop, and cooperative schemes for the aircraft wireless sensor networks and perform energy consumption and throughput analysis in the aircraft channel model. The aircraft channel was modeled by referring ITU-R M.2283, which consists of path loss, shadowing fading, and multi-path fading. The optimal transmitted power was applied to the eight scheme, which satisfied the transmitted power requirement except for multi-hop scheme. The performance of the total energy consumption and throughput was shown. According to the result, the incremental cooperative scheme outperformed by 66.8% better at a spectral efficiency of 2 than the DBF scheme in terms of energy consumption metric in which the beamforming scheme had a relatively high total energy consumption because the total energy consumption of the ABF and the DBF schemes increased in proportion to K-element antenna. Whereas, in terms of throughput metric in the overall SNR range from \(-20\) to \(30\) dB, the beamforming scheme had the best performance in which the beamforming scheme at SNR \(0\) dB achieved 85.4% better than the multi-hop scheme. In the case of the single-hop scheme, it had a similar performance in high a SNR range from \(10\) to \(30\) dB because the signal was strong enough to delivery successfully to the destination node. Finally, in terms of normalized throughput metric in a low SNR range between \(-20\) and \(1\) dB the ABF scheme had a better performance than the others in which the ABF at SNR \(0\) dB achieved 75.4% better than the multi-hop scheme. Whereas, in a high SNR range between \(2\) and \(30\) dB the IDF scheme had a better performance over the others in which the IDF at SNR \(10\) dB achieved 62.2% better than the multi-hop scheme. To apply to the aircraft wireless sensor networks, not only should the energy consumption be considered, but also the reliability for safety should be guaranteed, which is taken into account by the packet delay (including transmission, medium access, and queueing) and the packet loss (including shadow fading, multipath fading, doppler shift, and interference). For example, if one of sensors or one of actuators do not work due to some interference, it could lead to a major accident. Thus, the reliability of the wireless communication should be verified. One of methods to evaluate those factors became BER (bit tror rate), PER (packet error rate), RMSE (root mean square error), etc. For future work we intend to survey the reliability requirement for the aircraft, and based on the requirement to design a system model and evaluate it by using a NS2 simulation tool in terms of diverse wireless communication schemes.  
Data Curation, Methodology S.-H.K.; Formal analysis J.-W.K.; writing--review and editing D.-S.K. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Figure 12: Normalized throughput vs. SNR.  
**Acknowledgments:** This research was supported by Basic Science Research Program, Priority Research Centers Program through the National Research Foundation of Korea (NRF), and the Grand Information Technology Research Center support program through the IITP (IITP-2020-2020-0-01612, 2019R1I1A1A01063895, 2018R1A6A1A03024003).  
**Conflicts of Interest:** The authors declare no conflict of interest.