A New Multilevel Pulsed Modulation Technique for Low Power High Data Rate Optical Biotelemetry

This paper reports on the design, implementation and characterization of a novel multilevel synchronized pulse position modulation technique suitable to increase the data transmission efficiency and to reduce the overall power consumption of wireless ultra-wide-band optical biotelemetry links for implantable and wearable medical devices. The proposed modulation scheme, as well as allowing to transmit intrinsically the synchronization clock signal, makes use of a multilevel pulsed data coding approach so to transmit symbols composed of more than one bit. This has been achieved by designing proper digital architectures for the new data coding process and by employing 500 ps laser pulses modulating the bitstream to be transmitted. As a case-example, the overall electronics implementing the proposed novel modulation has been designed considering that each transmitted symbol is composed of 3 bits. Preliminary experimental results are reported and discussed considering the development on an FPGA board of the proposed wireless ultra-wide-band optical biotelemetry system. Its internal reference clock signal has been set to 40 MHz (i.e., a baud rate of 40 Mega symbol per second) corresponding to an equivalent transmission data rate equal to 120 Mbps with an energy efficiency of about 16.25 pJ/bit (i.e., 48.75 pJ/symbol). Moreover, a BER lower than 10−10 has been achieved with a maximum overall power consumption of the complete system of about 1.95 mW.