Ultrasonic multiplexing network for implantable medical devices

A system for transmitting data ultrasonically through a network:

• the network comprising a plurality of nodes, at least a portion of the nodes in communication through an aqueous medium, including:
• a first node embedded within and communicating through the aqueous medium and comprising an ultrasonic transducer and a transmitter, and a second node comprising an ultrasonic receiver;
• the transmitter at the first node including an orthogonal frequency division multiplexing (OFDM) signal generator operative to encode an input information bit stream on orthogonal subcarriers for transmission as an ultrasonic signal through the aqueous medium to the ultrasonic receiver at the second node, wherein OFDM packets carrying information bits are preceded by a preamble to provide a starting point of a packet to perform time synchronization;
• and the ultrasonic receiver at the second node is operative to decode the ultrasonic signal received from the first node to recover the information bit, further comprising a medium-access control layer for multipoint communication.