US Patent 10944447 Multi-channel near-field electromagnetic induction device

One example discloses a multi-channel near-field electromagnetic induction (NFEMI) device, including: a sub-channel controller configured to be coupled to a near-field magnetic antenna (H-field) and a near-field electric antenna (E-field) and configured to receive a message to be transmitted to a second near-field device in a near-field body-network through the near-field electric and magnetic antennas; wherein the sub-channel controller is configured to divide a narrow-band near-field channel into a set of sub-channels; and wherein the sub-channel controller is configured to calculate a signal-to-noise-ratio (SNR) for each sub-channel and select a sub-channel, from the set of sub-channels, for transmission of the message that has a higher SNR than another sub-channel in the set of sub-channels.