Measurement of Distributed Antenna Systems at 2.4 GHz in a Realistic Subway Tunnel Environment

Complete Propagation Model Structure Inside Tunnels

“…Multi-Mode Waveguide [10] Free Space Propagation [12] Near Shadowing Phenomenon [13] In term of the propagation mechanisms in the near region and the far region, there is a wide gap between different academic views. As shown in Table 1, at least three propagation mechanisms in the near region and two propagation mechanisms in the far region have been presented by various classic publications [10][11][12][13].…”

“…As shown in Table 1, at least three propagation mechanisms in the near region and two propagation mechanisms in the far region have been presented by various classic publications [10][11][12][13]. All these references justified their own claims but hardly refuted the conflicting standpoints.…”

“…• The essence of the near shadowing phenomenon [13] is that the line of sight (LOS) or the first Fresnel zone between transmitter (Tx) and receiver (Rx) is (partially) blocked by the user itself. This is why such effect is clearly observed in the cases when the user is relatively large, such as long trains in subway tunnel [13,15], but does not appear in the cases when the user is very small compared with the tunnel.…”

Channel Measurement and Modeling in Complex Environments

“…For instance, a hybrid tunnel propagation model has proposed based on the measurements at 900 MHz on horizontal and vertical polarization in a typical coal mine [88]; the radio propagation model for underground low-power sensor nodes [89]; the measurements in road tunnel [90], railway tunnel [91], subway tunnel [92], etc. There are also few propagation characterizations based on wideband radio channel measurements, which have been made in a highway road tunnel at 5.2 GHz [90]; in the underground mining environments in the range of 150-900 MHz [93], at 1 GHz [94], and at 2-5 GHz [95,96].…”

“…For instance, narrowband measurements have been conducted in circular tunnels at 450 MHz and 900 MHz [101]; in arched railway tunnels at 400 MHz [102] and at 900 MHz [91]; and in subway tunnels at 2.4 GHz [92]. Then the measurement-based empirical model [103] and stochastic models have been proposed, such as two-slope models [104,105], three-slope model [106], four-slope models [102,107], five-zone models [108,109,110], etc.…”