Research On Statistical Model For Wideband Wireless Channel And OFDM Modulation Of Confined Space

The confined space relative to free space consists of indoor propagation, subway, tunnel, underground market and underground coal mine. This paper focuses on the research of radio propagation in underground coal mine.Recently there are more accidents in coal mine which bring large losses to the economy and lives. It's vital to establish a flexible and reliable alarm and monitoring system which can improve the safety production and emergency service and disaster relief and protect the state property and life safety of miners.The exact description of channel propagation characteristics is important for the above system. Because the lack of propagation model of coal mine, this paper makes deeply research on propagation characteristics and establishes the statistical propagation model of coal mine, and this will be helpful for the research on radio propagation in subway and tunnel. Farther the parameter of the OFDM (Orthogonal Frequency Division Multiplexing) system is designed for coal mine communication.The main work of this paper is the research on the noise and characteristics of radio propagation in coal mine. Because of the large power and frequently start of the mining equipment, the noise consists of AWGN (Additive White Gaussian Noise) and impulse noise. Then the impact of coal mine section, roughness, tilt of tunnel wall and carrier frequency on propagation loss is analysed. At last the wideband wireless statistic model based on Nakagami distribution is put forward and the simulation is taken. The simulation results consistent with the measurements show that the delay spread is larger as the higher carrier frequency at UHF in coal mine.There are large amounts of multipath in coal mine laneway. OFDM make use of the serial-paralley converter and cyclic prefix to decrease the ISI (InterSymbol Interference). Therefore OFDM is applied to improve the performance of wireless communication system in coal mine. The parameter of OFDM is designed for various places of coal mine based on the forward model, and the simulation is taken under 2.4GHz and 5.8GHz. The simulation results show that OFDM after designed for various places has great performance under multipath and impulsive niose.