# Performance Evaluation of LoRa Communications in Harsh Industrial Environments
## 6 LoRa Performance: Using Error Correction and Filtering
### LoRa with Forward Error Correction and Filtering
#### 6.2.2 Many to One Mode  
The judicious integration of an IIR or FIR filter within a single receiver, designed to handle transmissions from sixteen transmitters in MtO mode, marked a decisive step forward in communication performance. By filtering out noise, these filters have considerably improved transmission, even in a LOS configuration which, although ideally favored, benefits from a substantial gain of 5 dB with these filters, as shown in Figures 24a and 25a. Under these conditions, the packet error rate tends towards zero, especially at signal-to-noise ratios of \(-1\) dB and 12 dB for spreading factors of 12 and 7, respectively. The NLOS configuration reinforces the importance of these filters, as shown in Figures 24b and 25b. Despite the inherent complexity of intercepting signals from sixteen separate transmitters and the challenges associated with this configuration, a gain of over 4 dB is observed, with 90% of packets received without fail at signal-to-noise ratios of 10 dB and 25 dB for the spreading factors mentioned. In summary, these results unequivocally demonstrate the positive impact of receiver-integrated IIR and FIR filters, underscoring their vital role in ensuring flawless communication in a scenario where a single receiver handles signals from sixteen or fewer transmitters.  
Figure 21: Magnitude Response (dB) and Phase Response (radians) for IIR Filter.  
An analysis of LoRa technology performance, illustrated in Table 4, reveals key trends for OtM (one-to-many) and MtO (many-to-one) communication modes. In an AWGN context, regardless of the mode used, the SF12 spreading factor systematically presents a more advantageous SNR threshold than SF7. However, as we move towards industrial conditions, the SNR threshold for both modes, OtM and MtO, increases, indicating a need for a stronger signal to overcome the environmental noise.  
This table highlights the relevance of optimizations using forward error correction, especially under demanding industrial conditions. While the adoption of a 4/5 code rate brings improvements, especially in OtM mode, it's really the 4/8 code rate that shines through, especially in OtM mode, testifying to its performance in the face of industrial interference.  
Introducing filters such as IIR or FIR while maintaining a 4/5 coding rate further enhances SNR threshold performance for both communication modes. In particular, the FIR filter shows a slight superiority over the IIR, especially for the OtM mode.  
Figure 23: PER over a fading channel with the industrial noise for the OtM mode, using the error correcting code 4/5 coding rate and FIR filter. **(a)** PER in LOS configuration; **(b)** PER in NLOS configuration.  
Figure 22: PER over a fading channel with the industrial noise for the OtM mode, using the error correcting code 4/5 coding rate and IIR filter. **(a)** PER in LOS configuration; **(b)** PER in NLOS configuration.  
Figure 24: PER over a fading channel with the industrial noise for the MtO mode, using the error correcting code 4/5 coding rate and IIR filter. **(a)** PER in LOS configuration; **(b)** PER in NLOS configuration.  
Figure 25: PER over a fading channel with the industrial noise for the MtO mode, using the error correcting code 4/5 coding rate and FIR filter. **(a)** PER in LOS configuration; **(b)** PER in NLOS configuration.