Wideband Near-Field Data Transmission Using Pulse Harmonic Modulation

Abstract

This paper introduces a new modulation technique, called pulse harmonic modulation (PHM), for wideband, low power data transmission across inductive telemetry links that operate in the near-field domain. The use of sharp and narrow pulses, similar to impulse-radio ultrawideband (IR-UWB) in the far-field domain, leads to significant reduction in the transmitter power consumption. However unlike IR-UWB, where all pulses are the same, in PHM each bit consists of a pattern of pulses with specific time delays and amplitudes, which minimize the intersymbol interference (ISI) across the receiver coil. This helps achieve a high data rate without reducing the inductive link quality factor and selectivity, which are necessary to block interferers. The received signal consists of an oscillation pattern that is amplitude modulated by the amplitude and timing of the successively transmitted pulses to facilitate data demodulation with low bit-error rate (BER). The main application of the PHM is expected to be in the neuroprostheses, such as brain-computer interfaces (BCIs) or cochlear/retinal implants, which need to transfer large volumes of data across the skin. It may also be used in short-range proximity-based digital communications with high-throughput wireless devices. This paper describes the PHM theoretical foundation and demonstrates its operation with a proof-of-concept prototype setup, which achieves a data rate of 5.2 Mbps at 1 cm coil separation with a BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">- 6</sup> .