Channel Capacity of Short-Range Ultrasonic Communications in Air

Abstract

The use of ultrasound in air as a means of digital communications has been demonstrated in recent years. Due to electromagnetic compatibility, privacy, and security issues, this kind of transmission fits the requirements of many medical applications, body-area networks, and general wireless short-range systems, where the transmission takes place in a single room with the distance up to 10 m. In the literature, different models of airborne ultrasound transmission have been investigated, but not supported by discussion of the channel theoretical capacity. On the other hand, knowledge of this measure is essential in the design of an efficient communication link and allows identifying its potential areas of applications. In this letter, we calculate estimates of the Shannon limit for five different configurations of airborne ultrasound digital communication channels. Our evaluation is based on the numerical results available in the literature. The obtained estimates show that in case of systems with multichannel transmission and higher order modulation schemes, the achieved data rates are closest to theoretical boundaries, but still further work is needed in order to achieve more efficient data transmission in airborne ultrasound communication channels.