This paper presents an experimental system for remote communication between road users and traffic signs. Implemented solution consists of two modules: a transmitter (traffic sign), including novel system for remote waking-up by the passing vehicle with use of the quasi-passive (biased) diode detector circuit, and a receiver (vehicle), which is responsible for wake-up signaling and interpreting received messages. Both modules use Wi-Fi protocol operating in 2.4 GHz ISM band for sending data, and OOK signaling in 868 MHZ ISM band for sending wake-up signals. The paper provides theoretical analysis, description of design challenges and chosen solutions, and finally, laboratory measurements as well as the results of tests conducted in the systems’ target environment with a moving vehicle, confirming correct operation of the system.