Delay Spread and Electromagnetic Reverberation in Subway Tunnels and Stations

This letter presents an extensive campaign of wideband propagation measurements conducted in a modern subway environment in Madrid, Spain, at 980 and 2450 MHz. Measurements have been made using a channel sounder in a realistic environment of tunnel and station. Based on the measurement results, the principal parameters, such as mean power and delay spread, have been extracted for wideband propagation modeling. Furthermore, the results have been used to model electromagnetic reverberation, quality factor, and transition region between tunnel and station. The quantitative results provide a detailed wideband model of subway environment, as well as determine the design tradeoffs inside real tunnels and stations, in terms of optimal frequency band, antenna position, and expected multipath.