In this paper, the statistical channel properties and channel modeling of indoor part for high-speed train communication sysem is presented based on wideband channel measurement at 2.35GHz. Two configurations of base station (8S) antennas, the omni-directional ceiling antenna and the planar antenna on the wall, are used in the measurement, in order to compare different channel characteristics and facilitate the future wide band system deployment. Channel properties, such as Path Loss (PL), Delay Spread (DS) and Ricean K-factor, are analyzed and modeled. The empirical log-distance PL models are derived. It is found that PL with planar antenna at BS is 10dB bigger than that with omni-directional antenna. The latter is even smaller than the PL of the free space. The distributions of DS under these two configurations are both well fitted with the lognormal distribution, and the mean values of them are similar. However, K-factors in decibel are quite different, although both follow well with the normal distribution. The mean values of K-factor with the omni-directional antenna and the planar antenna at BS are 10.41 dB and 4.09 dB, respectively.

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At present, the demand for accurate indoor positioning at a low cost is increasing. Based on the architecture of networking passive radio frequency identification (RFID) systems, research into passive location algorithms is important for finding a location solution with ultra-low cost, easy implementation, and no required maintenance. In this paper, TDACC (time difference of arrival with conic curves) based on signal propagation time is proposed, which breaks down the positioning problem into solving the intersection of an ellipse and a hyperbola. The results indicate that this method has a positioning error of 0 m in the absence of signal interference. When the time delay fluctuates to 1 ns and 2 ns, the average errors of TDACC are 0.19 m and 0.33 m, respectively. Different from other time-based localization methods, the proposed method only requires two distribution nodes without time synchronization, which reduces the system cost. These results will help to promote the deeper semantic communication level fusion of passive RFID. By improving the coordinate positioning in the semantic prior knowledge base, this method will lead to more efficient and accurate industry applications.

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