Efficient physical layer for intrabody communication networks

1. A method implemented by a computing device, the method comprising:

receiving an input via a processor of the computing device, wherein the input includes data to be transmitted;

encoding the data to generate spreading codes corresponding at least in part to the data;

mapping the spreading codes to one or more frequency subcarriers of a plurality of frequency subcarriers;

generating a transmit signal based at least in part on the one or more frequency subcarriers;

determining one or more transmitter electrodes, from a plurality of electrodes of the computing device, that maximize a differential capacitive coupling to a physical body;

selecting the determined one or more transmitter electrodes to be transmission electrodes for transmitting the transmit signal to the physical body;

amplifying the transmit signal for transmission to the selected one or more transmitter electrodes of the computing device; and

transmitting the amplified transmit signal via the selected one or more transmitter electrodes capacitively coupled to the physical body, the transmit signal being transmitted from the selected one or more transmitter electrodes through the physical body.

2. The method of claim 1 , wherein encoding the data to generate the spreading codes comprises encoding the data utilizing a Hadamard matrix, and wherein the spreading codes comprise Walsh spreading codes.

3. The method of claim 1 , wherein the data comprises one or more [n, k, m] convolutional codes, and wherein encoding the data to generate spreading codes comprises encoding the data with a [n, k, m] convolutional encoder to generate convolution codes and transforming the convolution codes into the spreading codes.

4. The method of claim 1 , wherein mapping the spreading codes to one or more frequency subcarriers comprises mapping the spreading codes to one or more frequency bins in a frequency channel range of 100 kilohertz (kHz) to 1.5 megahertz (MHz).

5. The method of claim 1 , wherein the transmit signal is amplified to a voltage of approximately 24 volts (V).

6. The method of claim 1 , wherein the spreading codes comprise a first set of Walsh spreading codes, the method further comprising:

receiving a receive signal via a second electrode capacitively coupled to the physical body, the receive signal being received at the second electrode from the physical body;

converting the receive signal into a discrete data signal, the discrete data signal including one or more other frequency subcarriers;

translating the one or more other frequency subcarriers into a second set of Walsh spreading codes;

translating the second set of Walsh spreading codes to correspond at least in part to one or more data symbols; and

decoding, via a Viterbi decoder, the one or more data symbols to retrieve data included in the receive signal.

7. The method of claim 1 , wherein selecting the one or more transmitter electrodes for transmitting the transmit signal to the physical body comprises operating one or more switches to select the one or more transmitter electrodes.

8. A system comprising: one or more non-transitory computer-readable storage media including instructions; and one or more processors coupled to the storage media, the one or more processors configured to execute the instructions to:

receive an input including data to be transmitted;

encode the data to generate spreading codes corresponding at least in part to the data;

map the spreading codes to one or more frequency subcarriers of a plurality of frequency sub carriers;

determine one or more transmitter electrodes, from a plurality of electrodes of a computing device, that maximize a differential capacitive coupling to a physical body;

select the determined one or more transmitter electrodes to be transmission electrodes for transmitting the transmit signal to the physical body;

amplify the transmit signal for transmission to the selected one or more transmitter electrodes of the computing device;

generate a transmit signal based at least in part on the one or more frequency subcarriers; and

transmit the amplified transmit signal via the selected one or more transmitter electrodes capacitively coupled to the physical body, the transmit signal being transmitted from the selected one or more transmitter electrodes through the physical body.

9. The system of claim 8 , wherein the instructions to encode the data to generate the spreading codes comprises instructions to encode the data utilizing a Hadamard matrix, and wherein the spreading codes comprise Walsh spreading codes.

10. The system of claim 8 , wherein instructions to encode the data to generate spreading codes comprises instructions for encoding the data with a [n, k, m] convolutional encoder to generate convolution codes and for transforming the convolution codes into the spreading codes.

11. The system of claim 8 , wherein the instructions to map the spreading codes to one or more frequency subcarriers comprises instructions to map the spreading codes to one or more frequency bins in a frequency channel range of 100 kilohertz (kHz) to 1.5 megahertz (MHz).

12. The system of claim 8 , wherein the instructions to amplify the transmit signal for transmission comprise instructions to amplify the transmit signal to a voltage of approximately 24 volts (V).

13. The system of claim 8 , wherein the spreading codes comprise a first set of Walsh spreading codes, the instructions further comprise instructions to:

receive a receive signal via a second electrode capacitively coupled to the physical body, the receive signal being received at the second electrode from the physical body;

convert the receive signal into a discrete data signal, the discrete data signal including one or more other frequency subcarriers;

translate the one or more other frequency subcarriers into a second set of Walsh spreading codes;

translate the second set of Walsh spreading codes to correspond at least in part to one or more data symbols; and

decode, via a Viterbi decoder, the one or more data symbols to retrieve data included in the receive signal.

14. The system of claim 8 , wherein the instructions to select the one or more transmitter electrodes for transmitting the transmit signal to the physical body further comprises instructions to operate one or more switches to select the one or more transmitter electrodes.

15. A non-transitory computer-readable medium comprising instructions that, when executed by one or more processors of a computing system, cause the one or more processors to:

receive an input including data to be transmitted;

encode the data to generate spreading codes corresponding at least in part to the data;

map the spreading codes to one or more frequency subcarriers of a plurality of frequency sub carriers;

determine one or more transmitter electrodes, from a plurality of electrodes of a computing device, that maximize a differential capacitive coupling to a physical body;

select the determined one or more transmitter electrodes to be transmission electrodes for transmitting the transmit signal to the physical body;

amplify the transmit signal for transmission to the selected one or more transmitter electrodes of the computing device;

generate a transmit signal based at least in part on the one or more frequency subcarriers; and

transmit the amplified transmit signal via the selected one or more transmitter electrodes capacitively coupled to the physical body, the transmit signal being transmitted from the selected one or more transmitter electrodes through the physical body.

16. The non-transitory computer-readable medium of claim 15 , wherein the instructions that cause the one or more processors to encode the data to generate the spreading codes comprises instructions to encode the data utilizing a Hadamard matrix, and wherein the spreading codes comprise Walsh spreading codes.

17. The non-transitory computer-readable medium of claim 15 , wherein the instructions that cause the one or more processors to encoding encode the data to generate spreading codes comprises instructions to encode the data with a [n, k, m] convolutional encoder to generate convolution codes and transform the convolutional codes into the spreading codes.

18. The non-transitory computer-readable medium of claim 15 , wherein the instructions that cause the one or more processors to map the spreading codes to one or more frequency subcarriers comprises instructions to map the spreading codes to one or more frequency bins in a frequency channel range of 100 kilohertz (kHz) to 1.5 megahertz (MHz).

19. The non-transitory computer-readable medium of claim 15 , wherein the instructions to amplify the transmit signal for transmission comprise instructions to amplify the transmit signal to a voltage of approximately 24 volts (V).

20. The non-transitory computer-readable medium of claim 15 , wherein the spreading codes comprise a first set of Walsh spreading codes, the instructions further comprise instructions that cause the one or more processors to:

receive a receive signal via a second electrode capacitively coupled to the physical body, the receive signal being received at the second electrode from the physical body;

convert the receive signal into a discrete data signal, the discrete data signal including one or more other frequency subcarriers;

translate the one or more other frequency subcarriers into a second set of Walsh spreading codes;

translate the second set of Walsh spreading codes to correspond at least in part to one or more data symbols; and

decode, via a Viterbi decoder, the one or more data symbols to retrieve data included in the receive signal.