工矿自动化

矿井移动通信、物联网通信、人员和车辆定位等系统的无线网络规划和优化等均需要计算无线传输路径损耗。但目前没有专门针对井下有限空间特殊环境的矿井无线传输路径损耗统计计算方法。现有的通用、地面开放空间及室内无线传输路径损耗统计计算方法均没有考虑巷道断面面积等井下特有环境因素的影响，难以直接用于井下复杂条件。针对上述问题，分析了影响矿井无线传输路径损耗的主要因素，提出了基于巷道断面面积的矿井无线传输路径损耗计算方法。该方法考虑了视距和非视距传输，不但与频率和距离有关，还与巷道断面面积、拐弯、分支、带式输送机、巷道壁平整度等有关。基于实测数据分析，揭示了矿井无线传输特性：(1)矿井无线传输具有显著的频率带通特性，存在频率拐点。当工作频率低于频率拐点时，巷道对无线传输影响大，无线传输路径损耗大，且工作频率越低，巷道对无线传输影响越大；当工作频率高于频率拐点时，巷道对无线传输影响小，但工作频率越高，无线传输路径损耗越大。直巷道的频率拐点在700/800 MHz附近。(2)矿井巷道无线传输路径损耗受巷道断面面积影响大。巷道断面面积越小，无线传输路径损耗越大，特别在工作频率低于频率拐点时，巷道断面面积对无线传输影响更大。(3)矿井拐弯巷道和分支巷道无线传输既受巷道断面面积的影响，又受非视距无线传输频率的影响，且频率对拐弯巷道和分支巷道无线传输的影响比巷道断面面积的影响大；巷道拐弯和分支增加了矿井无线传输路径损耗。使用所提方法对矿井不同场景的无线传输路径损耗进行了计算，结果表明，所提方法的平均绝对误差为3.8 dB，相较于FSPL,CIF,ABG,WINNER Ⅱ,ITU-R M.2412,3GPP InH-Office及ITU-R P.1238计算方法分别降低了7.0,3.3,2.7,5.2,2.9,3.5,5.1 dB。

Wireless network planning and optimization for mine mobile communication, Internet of Things communication, and personnel and vehicle positioning systems all require the calculation of wireless transmission p ath loss. However, no statistical calculation method is currently available that is specifically designed for mine wireless transmission path loss under the special conditions of underground confined spaces. Existing generalpurpose, open-space, and indoor wireless transmission path loss statistical calculation methods do not consider underground-specific environmental factors such as roadway cross-sectional area, making them difficult to apply directly to complex underground conditions. To address these problems, this study analyzed the main factors affecting mine wireless transmission path loss and proposed a mine wireless transmission path loss calculation method based on roadway cross-sectional area. The method considered both line-of-sight and non-line-of-sight transmission, and was related not only to frequency and distance but also to roadway cross-sectional area, curved roadways, branch roadways, belt conveyors, and roadway wall smoothness. Based on measured data, the characteristics of mine wireless transmission were revealed as follows:(1) Mine wireless transmission had a significant frequency band-pass characteristic, with a frequency turning point. When the operating frequency was lower than the frequency turning point, the roadway strongly affected wireless transmission, path loss was high,and the lower the operating frequency, the greater the influence of the roadway on wireless transmission; when the operating frequency was higher than the turning point, the influence of the roadway on wireless transmission was small, but wireless transmission path loss increased as the operating frequency increased. For straight roadways,the frequency turning point occurred around 700/800 MHz.(2) Wireless transmission path loss in mine roadways was greatly affected by roadway cross-sectional area. Smaller roadway cross-sections resulted in higher wireless transmission path loss, and the influence became even greater when the operating frequency was lower than the frequency turning point.(3) Wireless transmission in mine curved and branch roadways was affected both by roadway cross-sectional area and by the frequency of non-line-of-sight wireless transmission, and the influence of frequency on wireless transmission in curved and branch roadways was greater than the influence of roadway cross-sectional area. Curved roadways and branch roadways increased wireless transmission path loss in mines.The proposed method was applied to calculate wireless transmission path loss in different mine scenarios. The results showed that it achieved an average absolute error of 3.8 dB, reducing the error by 7.0, 3.3, 2.7, 5.2, 2.9,3.5, and 5.1 dB compared with the FSPL, CIF, ABG, WINNER Ⅱ, ITU-R M.2412, 3 GPP InH-Office, and ITU-R P.1238 calculation methods, respectively.