Design approach for a time reversal test bed for radio channels

In time reversal, a message signal to be transmitted is first convolved with the time-reversed channel impulse response and then sent to the receiver. The “time-reversed” waves which propagate into the channel retrace their former paths; they eventually lead to a focus of power in space and time at the receiver. Time reversal systems can use antenna arrays in order to enhance the focusing, but they do not necessarily need to. The channel´s degrees of freedom are rather excited by using broadband signals, and the focusing can be achieved with single-antenna links. To the authors´ best knowledge, there has been no demonstration of time reversal in wireless radio yet. This paper describes the broad design principles of a system that is designed to demonstrate time reversal in wireless radio channels. The system block diagram, some critical specifications and sources of error are described. Experimental data will be presented, if available in time, at the workshop.