A reconfigurable upper audio band modem for data communication between mobile devices

Abstract

For communicating short data sequences over small distances, the use of devices with conventional wireless radio frequency interfaces requires standardized hardware, dedicated infrastructure and appropriate Link/Network layer protocols. To address challenges associated with these requirements, a communication mechanism using devices which support simple audio interfaces (speakers and microphones) is proposed using the upper audio band (UAB) of frequencies (16---20 kHz). Devices with audio interfaces can be deployed in a personal area network for communicating at low data rates over small distances. Multi-tone FSK modulation is used for transmitting Reed---Solomon encoded data over the UAB. For peer-to-peer communication applications, a sensing mechanism is enabled on the receiving device to sense for empty time---frequency slots and schedule its data transmission at the appropriate times. A system prototype is developed using portable speakers and smartphones with sensitive microphones. The effective throughput of the modem is evaluated for different sensing durations and distances. Ad-hoc peer-to-peer networks can be enabled between mobile devices for communicating short data sequences based on the UAB modem.