Characterization of the radio propagation channel aboard trains for optimal coverage at 2.45GHz

The paper investigates the intra-car propagation properties of the radio channel at 2.45 GHz aboard trains. Results show that path loss is slightly smaller than that in free space and that it does not change significantly with the propagation direction. The delay spread strongly depends on polarization. Finally, the model that best fits the dependence of the coherence bandwidth on delay spread is obtained. The final aim of the presented study is to use such model to evaluate the maximum distance between access points mounted aboard that results in a delay spread that still allows transmission of the bandwidth required for optimal performance of the wifi service.