Ultrasonic wireless communication in air using OFDM-OOK modulation

A short-range multi-channel airborne ultrasonic data communication system using orthogonal frequency division multiplexing (OFDM) is described in this paper. An on-off keying (OOK) based OFDM modulation scheme was implemented successfully in the system by using a pair of commercially available air-coupled capacitive ultrasonic transducers. 56 orthogonal channels with a channel spacing of 1 kHz were transmitted in parallel, achieving a data transfer rate of 56 kbps with ultrasonic wireless synchronization. A simulation model developed in the work was able to predict ultrasonic signals accurately through the air channel. System performance was characterised by bit error rate (BER) testing over different transmission ranges. Error free decoding was achieved at distances up to 3 m.