## 5 Conclusions  
In this paper, we conducted a comprehensive comparison of the channel characteristics for all the frequency bands, including sub-6 GHz, mmWave, THz, and VLC, in the industrial scenario. Firstly, the channel characteristics, including the path loss, RMS DS, and AS, were analyzed with respect to the frequency dependence and the distance dependence. On the one hand, the visible light band exhibited significant differences in channel characteristics compared to the electronic wave band. Due to the LOS transmission of VLC, the visible light band had a higher path loss, and the path loss exponent reached 3.84. Due to the Lambertian radiation pattern, which has a wide range of reflection angles, the AS of the visible light band was much larger than that of the electronic wave band, which was 1.73 (\(\log_{10}(^{\circ})\)) and 0.80 (\(\log_{10}(^{\circ})\)) for the visible light and THz bands, respectively. On the other hand, the blockage effect of the metal instruments in the industrial scenario will greatly affect the channel characteristics. As the transceiver distance grows large, signals from both sides of the receiver will be blocked by metal instruments, resulting in a decreasing trend in the RMS DS for the electronic wave band. Secondly, the statistical characteristics of the channel properties were analyzed and modeled. It was found that both the RMS DS and the AS could be well fitted by the  
Figure 11: The mean value of the lognormal fitting for the AS. lognormal function for all the frequency bands. For the mean of the RMS DS fitting model, the value for the visible light band was \(-7.93\) (\(\log_{10}(\mathrm{s})\)), which was obviously lower than that of the electronic wave bands. In the electronic wave bands, the value of the mean was not significantly changed with the frequency and could be modeled as a constant with the value of \(-7.74\) (\(\log_{10}(\mathrm{s})\)). For the mean of the AS fitting model, the value for the visible light band was \(1.73\) (\(\log_{10}(^{\circ})\)), which was much higher than that for the electronic wave band. In the electronic wave band, the mean of the AS had a decreasing trend with an increasing frequency, which could be modeled as a logarithmic function. Finally, the proposed statistical parameters of the channel characteristics were compared with the 3 GPP TR 38.901 standard. It was found that the height of the receiver caused a larger PLE and a lower AS in the electronic wave bands in our research compared with those in 3 GPP TR 38.901. For the RMS DS, the 3 GPP model parameter for the factory scenario can be extended to apply to THz bands. What is more, the channel characteristics of the industrial scenario were compared with those of the indoor hotspot scenario. For the electronic wave bands, the channel characteristics of the industrial scenario exhibited a lower PLE, similar RMS DS, and lower AS. For the visible light bands, the channel characteristics of the industrial scenario exhibited a greater PLE, greater RMS DS, and larger AS. This study can provide insights for the evaluation and standardization of multi-frequency communication technology in industrial scenarios. [PERSON], [PERSON], and [PERSON] are my instructors and gave me full guidance and English correction during the writing process. Then, [PERSON] carried out the related work, including the construction of the simulation environment, the analysis of the simulation data, and the writing of the original draft. [PERSON], [PERSON], and [PERSON], as experts in VLC channel modeling in the company, also provided a lot of guidance on modeling during the data analysis. All authors have read and agreed to the published version of the manuscript.