Spatial diversity based coverage map building in complex tunnel environments

Knowing certain characteristics about signal behavior in specific environments is crucial in order to perform effective utilization of a wireless network, and one manner to achieve this is through the employment of coverage maps. We designed a tool for coverage map building, based on various modules, and implemented them over a real all-terrain vehicle and a Pioneer P3AT robot. We test both tools in the Somport railway tunnel, for which a specific propagation model is unavailable due to characteristics such as lateral vaults and galleries, horseshoe shape, and a change in slope, among others. Results were compared to a Straight Tunnel Ray Tracing model. We found similarities and differences regarding fadings. Also, we were able to dismiss significant influence of vaults and lateral galleries over propagation. We found that due to transversal variations, good quality signal can be achieved in almost the entire studied area by applying a large scale diversity for antennas, and coverage maps were constructed on this basis. Results derived from this work can be used from optimal deployment of a wireless network, up to the development of multi-robot navigation strategies under communication constrains in this type of scenarios.