Double Directional Channel Measurements in an Arched Tunnel and Interpretation Using Ray Tracing in a Rectangular Tunnel

Abstract

Abstract-The objective of this paper is to study the wideband characteristics of the radio channel in a tunnel environment, not only the delay spread, but also the angle of departure/arrival of the rays, their relative weights and their delays, which are important values for Multiple-Input Multiple-Output applications. In order to achieve this goal, a measurement campaign has been carried out in a straight arched tunnel over a frequency band extending from 2.8 to 5.0 GHz and distance varying from 50 m up to 500 m. First, the variations of the channel impulse response and of the delay spread versus the distance between the transmitter and the receiver are analyzed. Then, the bidirectional channel characteristics have been extracted from the measured channel matrices using a high resolution estimation algorithm. The main contribution of this paper is to clearly show the quantitative variation of the delay spread and the angle of departure/arrival of the rays along a real tunnel and to investigate the possibility of using the ray theory in a rectangular tunnel to interpret experimental results obtained in an arched tunnel.

Mimo Capacity in Uwb Channels in an Office Environment for Different Polarizations

“…4. These antennas work in the 2-10 GHz frequency band and have been widely used in literature for UWB measurements [22][23][24][25] since they operate in the UWB band. Furthermore, the antennas have 1 dBi gain and an XPD of 12 dB.…”

Characterization of Angular Spread in Underground Tunnels Based on the Multimode Waveguide Model

“…The results of AS characterization in this study can be used to extend the IEEE 802.11n MIMO channel model to underground mines or as the basis for other correlation-based MIMO channel models for underground tunnels. We compared and validated our findings to experimental work presented in [3], and also to simulations using a ray-tracing based software (Wireless InSite from Remcom Inc.) [9].…”

“…However, MIMO research, and in particular, antenna configuration design and characterization of angular spread for wireless propagation in tunnels and mines, is sparse, and related work in literature is limited. Recently, AS was experimentally studied in [3] for a large arched subway tunnel (8.6 m × 6.1 m) with slightly rough walls (i.e., roughness is less than 2 cm, or less than 0.1λ). However, the accuracy of the experimental characterization is only good for distances up to a limited distance (about 150 m), and for larger distances it becomes degraded and more difficult to extract and distinguish individual rays.…”

Optimal configuration of distributed MIMO antennas in underground tunnels

“…Based on [4], [9], for different transmitter-receiver separations, path loss is different; the larger the separation, the higher the path loss, and thus the lower the capacity. Therefore, based on this analysis as well as angular spread considerations, transmitter-receiver separation should be kept as small as possible.…”