Research On Construction Of Mine Wireless Communication System Based On Leaky Waveguide

For the limited and narrow communication space of mine tunnel located in deep stratum,the communication system based on leaky coaxial cable has been widely used.The longitudinal electromagnetic wave is guided by the leaky coaxial cable,and the electromagnetic wave is radiated outwardly through the slot structures of the surface of leaky coaxial cable so as to provide enough radio electromagnetic fields inside the tunnel.This guarantees the realization of reversible coupling between base station and mobile stations or among mobile stations.Since the operating frequency of leaky coaxial cable is no more than 1GHz and higher data transmission rate is required in the wireless communication system,other transmission media must be found to meet the need of high frequency operating range.Due to the advantages of leaky waveguide such as high operating frequency,small longitudinal attenuation and high transmission rate,the thesis proposes a communication system composed of leaky waveguide instead of leaky coaxial cable.Main points of the work in this dissertation can be concluded as follows:(1)Based on the slot structures,the new approach that leaky waveguide used in mine communication system is proposed.According to the characteristics of complex environment in mine tunnel,the simulation analysis model of leaky waveguide is established in HFSS.The radiation characteristics of leaky waveguide in complex environment are studied.Simulation results show that the radiation signal of leaky waveguide is reduced to various degrees under the influence of coal dust covering,impurity blocks clogging and internal water.The application feasibility of leaky waveguide in mine communication system is proved,and some suggestions are also given for practical installation.(2)In order to improve the survivability of leaky waveguide communication system,the method of configuring redundant lines on the main communication lines is used.The network structures of four different redundant architectures are given and analyzed.It is found that the system survivability is better when using double shafts or the fully redundant mode by comparing the survivability and the performance of different network structures.The reliable reference data for the construction of mine communication system are offered.(3)The channel capacity of leaky waveguide communication system is discussed.Based on the link budget,leaky waveguide channel is analyzed as wired channel.The channel characteristics of communication system are analyzed by using Shannon capacity and the channel capacity under various modulation schemes.Through comparing the relationship between transmission distance and channel capacity as well as the relationship between signal-to-noise ratio and channel capacity of leaky waveguide and leaky coaxial cable communication system,that the leaky waveguide has the advantages of long transmission distance and high data transmission rate in mine communication system is verified.The above work in this thesis is of practical value for the development of new mine wireless communication system based on leaky waveguide.