# Performance Evaluation of LoRa Communications in Harsh Industrial Environments
## 6 LoRa Performance: Using Error Correction and Filtering
### LoRa with Forward Error Correction and Filtering
#### 6.1.2 Many to One Mode  
In M\(\mathrm{\SIUnitSymbolMicro}\) mode, characterized by the presence of sixteen transmitters communicating with a single receiver, Figure 18 highlights the influence of the coding rate on transmission performance. In the LOS configuration, the 4/5 coding rate demonstrates high accuracy, detecting all signals without error, despite the multitude of transmitters. Signal-to-noise ratios of 4 dB and 18 dB, combined with spreading factors of 12 and 7, attest to this performance. However, the gain in terms of SNR with this ratio is limited to less than 2 dB. On the other hand, the 4/8 code rate, in addition to its detection capability, actively corrects errors. This translates into exceptional efficiency, evident in signal-to-noise ratios of \(-6\) dB and 8 dB for the same spreading factors. With an impressive SNR gain of 9 dB, the 4/8 rate  
Figure 16: PER over a fading channel with the industrial noise in LOS configuration for the \(\mathrm{\SIUnitSymbolMicro}\) mode, using the error correcting code. **(a)** PER for a 4/5 coding rate; **(b)** PER for a 4/8 coding rate.  
Figure 17: PER over a fading channel with the industrial noise in NLOS configuration for the \(\mathrm{\SIUnitSymbolMicro}\) mode, using the error correcting code. **(a)** PER for a 4/5 coding rate; **(b)** PER for a 4/8 coding rate.  
is the optimal choice, especially in this dense transmission mode. In summary, Figure 18 underlines that, faced with the challenges of the MtO mode and its sixteen transmitters, the 4/8 rate appears to be the best option for guaranteeing optimal transmission, particularly in terms of signal-to-noise ratio.  
A detailed exploration of Figure 19 sheds relevant light on the performance of coding rates under NLOS conditions. At first glance, it might appear that the 4/5 and 4/8 coding rates behave comparably. However, closer observation reveals significant differences between the two. While the 4/5 code rate offers reliable transmission, with perfect packet reception at signal-to-noise ratios of 32 dB and 46 dB, the 4/8 code rate excels even further. It guarantees flawless reception at significantly lower levels, precisely 23 dB and 40 dB, for spreading factors of 12 and 7, respectively. This 10 dB gain between the two coding rates is not insignificant and testifies to the superior robustness of the 4/8 rate. In other words, in NLOS transmission environments, where conditions can be unpredictable and obstacles numerous, the 4/8 coding rate clearly stands out as the best option, guaranteeing not only efficient data transmission but also a reduced margin of error, which is essential for ensuring continuity and quality of communication.  
In this subsection, the results show a significant improvement in LoRa's PER performance thanks to the integration of forward error correction. However, to further optimize this performance, we envisage adopting the IIR and FIR filters. This technical choice and the expected benefits will be the focus of discussion in the next subsection.