Study On MIMO Channel Model And Its Characteristics In Coal Mine

Wireless communication technology is applied boomingly underground as the importance of the coal mine safety production and post-disaster relief for countries is strengthen continuously. Compared with other wireless communication technology,the wireless communication technology of MIMO which has the advantages of high capacity, low bit error rate and anti-multipath can satisfy the requirement for quality of communication in underground communication system.Many advantages of MIMO is closely related with the MIMO channel characteristic, which has big differences in different enviroments. So it is important for the practical application of the MIMO technology to understand and grasp the different characteristics of MIMO in different transmission environment and to establish a MIMO channel model consistent with transmission environment.On the basis of analyzing current MIMO modeling method, this paper focuses on the research of MIMO modeling method in underworkings based on method of images. Assuming that scatterers are evenly distributed and the highest number of reflection is 3, it analyzes how to identify mirror point and effective mirror point by using method of images. Tent Law and Fermat Theorem are applied to calculate path length and model parameter; underground MIMO signal channel model is developed.This paper analyzes Space-time correlation coefficient of MIMO signal channel and the effect K, Rice’s factor, has on the correlation coefficient, verifying that MIMO technique can effectively improve self performance by downhole multipath effect.Channel capacity is normalization processed; normalization coefficient and the expression of normalized channel capacity are given in this paper. Simulated analysis of cumulative probability distribution of channel capacity is conducted to prove the rationality of modeling. It also analyzes transmission frequency of electromagnetic wave and the influence which the distance between transmit and receive antennas plays on the signal strength. By comparing with measured field intensity, the underground MIMO model according to method of images is proved to be accurate in near-field region.