Software-based modem for near field acoustic communication

Acoustical communication has broad utility for consumer use, device-to-device communication, since it utilizes the standard equipment; loudspeaker and microphone. In this paper, we focus on a simple acoustic modem that enables device-to-device communication using orthogonal frequency division multiplexing (OFDM). Considering the lack of computing power in mobile devices, the modem is designed to achieve signal modulation with reasonable calculation cost. In this paper we propose a modulator; OFDM signal is modulated with aid of sinusoidal wave table assuming that the message is BPSK-mapped, and a demodulator; the message is obtained by delay detection. Performance of the proposed modem was evaluated experimentally using actual mobile phones. As a result, we confirmed the utility of the proposed modem; complexity of proposed modem was less than lower than that of conventional modem and it was suitable for acoustic communication between mobile devices.