Methods and systems for forward error correction for measurement while drilling (MWD) communication systems

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• and
• decoding the transmitted data received at the receiver in accordance with the FEC code to recover received data;
• for each sub-band, flagging the transmitted data received in the sub-band as erasures for handling during decoding based at least in part on measurements of receive signal power in the sub-band.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• and
• decoding the transmitted data received at the receiver in accordance with the FEC code to recover received data;
• for each sub-band, flagging the transmitted data received in the sub-band as erasures for handling during decoding based at least in part on estimating at least one of:
• a signal to noise ratio (SNR) of the transmitted data received in the sub-band and a signal to interference and noise ratio (SINR) of the transmitted data received in the sub-band.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• encoding the data to be transmitted according to a two-dimensional FEC encoding scheme, wherein encoding the data to be transmitted according to a two-dimensional FEC encoding scheme comprises, after assigning the FEC-encoded data into the plurality of sub-channels and prior to modulating the data from each of the plurality of sub-channels, applying, to the FEC-encoded data assigned into each of the plurality of sub-channels, a corresponding in-stream FEC code;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• for each sub-band, decoding the transmitted data received at the receiver in the sub-band in accordance with its corresponding in-stream FEC code to obtain sub-band decoded data;
• and
• decoding the sub-band decoded data in accordance with the FEC code to recover received data;
• for each sub-band, flagging the transmitted data received in the sub-band as erasures for handling during decoding of the sub-band decoded data based at least in part on measurements of receive signal power in the sub-band.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• encoding the data to be transmitted according to a two-dimensional FEC encoding scheme, wherein encoding the data to be transmitted according to a two-dimensional FEC encoding scheme comprises, after assigning the FEC-encoded data into the plurality of sub-channels and prior to modulating the data from each of the plurality of sub-channels, applying, to the FEC-encoded data assigned into each of the plurality of sub-channels, a corresponding in-stream FEC code;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• for each sub-band, decoding the transmitted data received at the receiver in the sub-band in accordance with its corresponding in-stream FEC code to obtain sub-band decoded data;
• and
• decoding the sub-band decoded data in accordance with the FEC code to recover received data;
• for each sub-band, flagging the transmitted data received in the sub-band as erasures for handling during decoding of the sub-band decoded data based at least in part on estimating at least one of:
• a signal to noise ratio (SNR) of the transmitted data received in the sub-band and a signal to interference and noise ratio (SINR) of the transmitted data received in the sub-band.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises using an orthogonal frequency division multiplexing (OFDM) scheme wherein, for each sub-channel, a plurality of bits from the sub-channel are modulated concurrently onto orthogonal acoustic sub-carriers having sub-carrier frequencies within the sub-band corresponding to the sub-channel;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• and
• decoding the transmitted data received at the receiver in accordance with the FEC code to recover received data;
• for each sub-carrier, flagging the transmitted data received in association with the sub-carrier as erasures for handling during decoding based at least in part on measurements of receive signal power in the sub-carrier.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises using an orthogonal frequency division multiplexing (OFDM) scheme wherein, for each sub-channel, a plurality of bits from the sub-channel are modulated concurrently onto orthogonal acoustic sub-carriers having sub-carrier frequencies within the sub-band corresponding to the sub-channel;
• wherein using the OFDM scheme comprises applying, to the FEC-encoded data assigned to each of the plurality of sub-carriers, a corresponding sub-carrier FEC code;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• receiving, at the receiver and across the banded communication channel, the transmitted data;
• for each sub-carrier, decoding the transmitted data received at the receiver in association with the sub-carrier in accordance with its corresponding sub-carrier FEC code to obtain sub-carrier decoded data;
• and
• decoding the sub-carrier decoded data in accordance with the FEC code to recover received data;
• for each sub-carrier, flagging the transmitted data received in association with the sub-carrier as erasures for handling during decoding of the sub-carrier decoded data based at least in part on measurements of receive signal power in the sub-carrier.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises setting a frequency-domain width of each sub-band to be greater than an estimated frequency-domain width of the corresponding pass-band.

A method, in a communication system comprising a transmitter and a receiver, for communicating data from the transmitter to the receiver over a banded communication channel, the method comprising:

• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises using an orthogonal frequency division multiplexing (OFDM) scheme wherein, for each sub-channel, a plurality of bits from the sub-channel are modulated concurrently onto orthogonal acoustic sub-carriers having sub-carrier frequencies within the sub-band corresponding to the sub-channel;
• concurrently transmitting the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises selecting orthogonal acoustic sub-carriers having sub-carrier frequencies within an estimated frequency-domain location of a corresponding pass-band in the channel.

A communication system comprising a transmitter and a receiver for communicating data from the transmitter to the receiver over a banded communication channel, the communication system comprising:

• a transmitter configured to:
• apply a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assign the FEC-encoded data into a plurality of sub-channels;
• modulate the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• and
• concurrently transmit the data from the plurality of sub-bands onto a banded communication channel, the banded communication channel comprising one or more pass-bands and one or more stop-bands;
• the transmitter further configured to modulate the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands by setting a frequency-domain width of each sub-band to be greater than an estimated frequency-domain width of the corresponding pass-band.

A method for providing communication between a downhole location on a drill string and an uphole location on the drill string, the method comprising:

• providing, at the downhole location, an acoustic transmitter connected for transmitting an acoustic signal into a communication channel comprising the drill string;
• providing, at the uphole location, an acoustic receiver connected for receiving a transmitted acoustic signal from the communication channel;
• applying a forward error correction, FEC, code to data to be transmitted to obtain FEC-encoded data;
• assigning the FEC-encoded data into a plurality of sub-channels;
• modulating the data from each of the plurality of sub-channels into a corresponding one of a plurality of sub-bands, the plurality of sub-bands having spaced apart center frequencies;
• concurrently transmitting the data from the plurality of sub-bands from the transmitter onto the communication channel, the communication channel comprising one or more pass-bands and one or more stop-bands;
• wherein modulating the data from each of the plurality of sub-channels into its corresponding one of the plurality of sub-bands comprises setting a frequency-domain width of each sub-band to be greater than an estimated frequency-domain width of the corresponding pass-band.