The localization can be done by choosing the reference point from the database that matches best with the observed data. Moreover, the ultra wide band (Ultra Wide Band: UWB)-based WSN for localization in mining environments was presented by Abdellah et al. [11]. The received signal strength indication (Received Signal Strength protein inhibitor Indication: RSSI)-based location algorithm was optimized by Pei et al. [12], Yang et al. [13] and Zhang et al. [14] to improve positioning accuracy.For practical applications, several issues exist in current designs and deployment schemes with decentralized wireless sensors:Energy: the current wireless sensing designs usually adopt ad hoc networking that fully covers the monitoring areas with wireless sensors. This may result in the so-called data collisions.

With an increasing number of sensors, the sensor node close to the sink would be burdened with tremendous data Inhibitors,Modulators,Libraries transmission levels, which may cause a significant communication and energy bottleneck.Practicability: the fingerprint Inhibitors,Modulators,Libraries method must prepare a large training database for accurate position estimation, and the database must be frequently updated to reduce the deviation of the channel characteristics in the training and position estimation phases. This is hard in a practical underground application.Cost: due to heavy hardware installation and network initialization calibration [15] of UWB, the cost of implementing a UWB-based WSN in a large-scale coal mine is high. In general, the length of main roadways in coal mines may range from a few to tens of kilometers [16].

For multilevel underground tunnel network structures, the total cumulative length of roadways can be hundreds of kilometers. However, the perception range of wireless sensor nodes is only tens of meters (e.g., effective perception radius of Zigbee measuring Inhibitors,Modulators,Libraries point is about 60 meters in the interior roadway Inhibitors,Modulators,Libraries environment [17]), so Cilengitide building a complete coverage positioning system requires high cost, which will further generate data congestion, delays, and maintenance problems due to the large number of measuring points.Reliability: under bad underground conditions (humidity, dust, landslides, etc.), the personnel positioning information can be partially delayed or lost even if the area is completely covered by measuring points. Therefore, in practical applications, reliability is very demanding.

In order to effectively and efficiently manage the large number of sensors, this paper develops a new design and deployment scheme, which forms a low-cost hierarchical coal mine personnel positioning system (Mine Personnel Positioning System: MPPS) with blind areas. The main contributions inhibitor Cisplatin of this paper are as follows:A low cost coal mine personnel positioning system is designed in the tunnel environment based on Zigbee technology.