Communications with conditional chain decoding

A method performed at a receiver for decoding client data bits from a signal received over a communications channel from a transmitter, the client data bits comprising first client data bits and second client data bits, each first client data bit and each second client data bit having a substantially equal probability of being zero and being one, the method comprising:

• determining estimates of transmitted symbols from the signal received over the communications channel based on a modulation scheme implemented at the transmitter;
• determining, from the estimates of the transmitted symbols, first value estimates for one or more first positions in the transmitted symbols based on a code implemented at the transmitter;
• determining, from the estimates of the transmitted symbols, two or more conditional second value estimates for one or more second positions in the transmitted symbols, wherein each conditional second value estimate corresponds to a different value or combination of values in the one or more first position;
• applying second forward error correction ‘FEC’ decoding to the first value estimates to generate corrected first values, wherein the corrected first values consist of the second client data bits and redundant values;
• using the corrected first values to select second value estimates from the conditional second value estimates;
• applying first FEC decoding to at least the selected second value estimates to generate corrected second values, wherein each corrected second value has a substantially higher probability of being one or more first elements than of being one or more second elements;
• and
• processing the corrected second values to generate the first client data bits.

A receiver electronic device configured for decoding client data bits from a signal received over a communications channel from a transmitter electronic device, the client data bits comprising first client data bits and second client data bits, each first client data bit and each second client data bit having a substantially equal probability of being zero and being one, the receiver electronic device comprising:

• a processor;
• and
• a memory storing computer-executable code which, when executed by the processor, causes the receiver electronic device
• to determine estimates of transmitted symbols from the signal received over the communications channel based on a modulation scheme implemented at the transmitter;
• to determine, from the estimates of the transmitted symbols, first value estimates for one or more first positions in the transmitted symbols based on a code implemented at the transmitter;
• to determine, from the estimates of the transmitted symbols, two or more conditional second value estimates for one or more second positions in the transmitted symbols, wherein each conditional second value estimate corresponds to a different value or combination of values at the one or more first positions;
• to apply second forward error correction ‘FEC’ decoding to the first value estimates to generate corrected first values, wherein the corrected first values consist of the second client data bits and redundant values;
• to use the corrected first values to select second value estimates from the conditional second value estimates;
• to apply first FEC decoding to the selected second value estimates to generate corrected second values, wherein each corrected second value has a substantially higher probability of being one or more first elements than of being one or more second elements;
• and
• to process the corrected second values to generate the first client data bits.

A transmitter electronic device configured for communicating client data bits over a communications channel to a receiver electronic device, the client data bits comprising first client data bits and second client data bits, each first client data bit and each second client data bit having a substantially equal probability of being zero and being one, the transmitter electronic device comprising:

• a processor;
• and
• a memory storing computer-executable code which, when executed by the processor, causes the transmitter electronic device
• to process the first client data bits to generate processed values, wherein each processed value has a substantially higher probability of being one or more first elements than of being one or more second elements;
• to apply first forward error correction TEC' encoding to the processed values to generate first FEC-encoded values consisting of FEC-encoded processed values and redundant values;
• to apply second FEC encoding to at least the second client data bits to generate second FEC-encoded values;
• to create symbols by mapping the second FEC-encoded values to one or more first positions in the symbols and by mapping the FEC-encoded processed values to one or more second positions in the symbols;
• and
• to modulate the symbols onto the communications channel using a modulation scheme with a code that assigns a lower average energy to symbols containing the one or more first elements in the one or more second positions than to symbols containing the one or more second elements in the one or more second positions.