# A New LoRa-like Transceiver Suited for LEO Satellite Communications +
## 5 Conclusions  
CSS signals are extremely sensitive to time and frequency offsets, especially the Doppler shift variable in time. In this paper, we proposed a new LoRa-like receiver, to improve the robustness of symbol decoding to synchronization errors. This robustness was obtained by implementing differential symbol coding that modulates the transmitted chirps associated with an original synchronization algorithm. The latter differential processing can be easily implemented, which guarantees the cost-effectiveness of the transmitter. Subsequently, this novel approach allows synchronization of LoRa-like signals by decoupling the estimation of the CFO and the STO, which releases the constraint of the maximum allowed CFO of \(\frac{B}{4}\). In addition, our proposed technique is more robust to the time varying Doppler shift than the existing LoRa-based receivers. Simulation results show the efficiency of our receiver in dealing with time and frequency offsets, especially the time variant frequency shift caused by the Doppler effect. Finally, the capacity of our receiver in processing CFOs greater than \(\frac{B}{4}\), and its robustness to the DR, make it possible to consider, if the communication rate allows it, UNB communications with LEO satellites using LoRa-like signals. In future work, we plan to evaluate the performance of our proposed receiver in real-time communications using software defined radios. We intend to combine our algorithm that deals with the destructive collision in LoRa, as presented in [8], with the one proposed in this paper.  
Conceptualization, M.A.B.T., G.F. and R.T.; methodology, M.A.B.T. and G.F.; software, M.A.B.T.; validation, M.A.B.T., G.F. and R.T.; formal analysis, M.A.B.T. and G.F.; investigation, M.A.B.T.; resources, M.A.B.T.; data curation, M.A.B.T.; writing--original draft preparation, M.A.B.T.; writing--review and editing, M.A.B.T.; visualization, M.A.B.T.; supervision, G.F. and R.T.;  
Figure 13: Evolution of the SNR (dB) and elevation angle as function of time for Eutelsat satellite.  
\begin{table}
\begin{tabular}{l c c c c c c c} \hline \hline \multicolumn{1}{c}{**(\(SF\), \(B\))**} & \multicolumn{1}{c}{**(\(12\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(11\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(10\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(9\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(8\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(7\), \(B_{ref}\))**} & \multicolumn{1}{c}{**(\(7\), \(\frac{B_{ref}}{2^{8}}\))**} \\ \hline \(SNR_{th}\) (dB) & \(-19.5\) & \(-17.5\) & \(-14.5\) & \(-11.8\) & \(-9.2\) & \(-6.5\) & \(-5\) \\ \(S\) (dBm) & \(-136.53\) & \(-134.53\) & \(-131.53\) & \(-128.83\) & \(-126.23\) & \(-123.53\) & \(-137.08\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Receiver sensitivity \(S\) dBm for different \(SF\) and \(B\) values.  
project administration, G.F. and R.T.; funding acquisition, G.F. All authors have read and agreed to the published version of the manuscript.  
This research has been carried out with financial support from the French State, managed by the French National Research Agency (ANR) in the frame of the \"Investments for the future\" Programme IdEx Bordeaux--SysNum (ANR-10-IDEX-03-02).  
Not applicable.  
The authors declare no conflict of interest.