Radio channel characterization study and wireless communication trial in mine shaft

In order to obtain the radio channel characterizations in mine shaft environment,the narrowband and wide- band channel measurements at 2. 4 GHz were carried out in a real mine shaft in the condition of point-to-point commu- nication with directional antennas. Important parameters such as path loss and delay spread were presented and com- pared with that in underground roadways. The results show that the path loss exponent is smaller than that in free space,showing a waveguide effect. RMS delay spread was found to follow the lognormal distribution. Its mean value was found smaller than that in underground roadways. It was also found that the RMS delay spread increases then de- creases with the increase of Tx-Rx distance. The 90% coherence bandwidth is mostly less than 12 MHz,meaning a transmission capacity of data,voice and video. In general,the shaft channel condition is sound. A video surveillance system based on the WLAN was designed. The field test was conducted with a good performance for over a year. The study provides important parameters and reference for designing mine shaft communication and monitoring systems.