Performance under shadowing environment of a hybrid system for mobile robots using cellular and ad-hoc modes

A hybrid system for operational mobile robots using two modes, the cellular mode and the direct mode, or the ad-hoc mode, named as “cellular ad-hoc united communication system” has been considered previously by the authors. A mobile terminal (MT) selects the mode which has better communication condition with its received power and changes the modes while communicating. This system has been confirmed to have effective channel usage and reduction in battery consumption. Another advantage which can be expected in this system is validity in shadowing environment. This is because when there is a pair behind walls from base stations (BSs), condition of direct communication (ad-hoc mode) might be better than that through BSs (cellular mode). Thus, here the performance of the hybrid system is examined under shadowing environment with the use of a ray-tracing method. From the results, the validity of the hybrid system toward shadow fading was confirmed