This paper studies the practical challenges that arise due to the coexistence of two wireless technologies, both operating in the license-exempt 5 GHz band. In particular, WiFi and WiMAX equipment have been used in the experiments. The mutual interference caused by the two technologies operating in different but narrowly separated frequency channels has a negative impact on the performance of both systems. Further challenges are introduced when the two systems are in close physical proximity of each other or, in a more extreme scenario, share the same antenna as could be required in railway applications. This paper investigates these issues through a series of experimental tests based on a multi-radio platform testbed. The conclusions drawn from this study will be used as a base for the implementation of a multi-radio platform to provide communications between train and land in both directions in the context of the Spanish high-speed railway system.

Peer Reviewed