Forward error correction with parity check encoding for use in low complexity highly-spectrally efficient communications
A transmitter inserts parity samples into a stream of information symbols in an inter-symbol correlated (ISC) signal. The inserted parity samples may be utilized to generate estimates of corresponding information symbols when they are received by a receiver. The information symbols may be pulse shaped by a first pulse shaping filter characterized by a first response. The parity samples may be pulsed shaped by a second pulse shaping filter characterized by a second response. The first response and the second response are diverse or uncorrelated. The transmitter may transmit the ISC signal comprising the pulse shaped information symbols and the pulse shaped parity samples. The parity samples may be generated utilizing a non-linear function over a plurality of the information symbols. The non-linear function may be diverse from a partial response signal convolution corresponding to the information symbols and is designed according to a desired SNR value at the receiver.
1. A method, the method comprising:
in a transmitter comprising a first pulse shaping filter characterized by a first frequency response and a second pulse shaping filter characterized by a second frequency response:
generating a first stream comprising a plurality of information symbols;
generating a parity value based on said plurality of information symbols;
pulse shaping said plurality of information symbols via said first pulse shaping filter;
pulse shaping said parity value via said second pulse shaping filter;
combining outputs of said first pulse shaping filter and said second pulse shaping filter to generate a second stream; and
transmitting said second stream.
2. The method of claim 1 , comprising:
receiving feedback from a receiver of said second stream; and
adjusting, based on said feedback from said receiver, a power at which said transmitting is performed.
3. The method of claim 2 , wherein said feedback from said receiver indicates a symbol error rate in said receiver.
4. The method of claim 1 , wherein said generating said parity value comprises applying a parity function to participating symbols of said plurality of information symbols.
5. The method of claim 4 , wherein said applying said parity function comprises summing values of said participating symbols.
6. The method according to claim 5 , wherein said parity function is configured to ensure that said parity value is within a range of values determined by a symbol constellation used for said generating said plurality of information symbols.
7. The method of claim 4 , comprising selecting said parity function based on a signal to noise ratio in a receiver of said second stream.
8. The method of claim 4 , wherein said participating symbols are non-adjacent information symbols of said first stream.
9. The method of claim 4 , comprising selecting which of said plurality of information symbols to use as said participating symbols based on error event length and/or signal-to-noise ratio in a receiver of said second stream.
10. The method of claim 1 , wherein said first frequency response is a low-pass response and said second frequency response is a high-pass response.
11. A system, the system comprising:
a transmitter comprising a first pulse shaping filter characterized by a first frequency response and a second pulse shaping filter characterized by a second frequency response, wherein said transmitter is operable to:
generate a first stream comprising a plurality of information symbols;
generate a parity value based on said plurality of information symbols;
pulse shape said plurality of information symbols via said first pulse shaping filter;
pulse shape said parity value via said second pulse shaping filter;
combine outputs of said first pulse shaping filter and said second pulse shaping filter to generate a second stream; and
transmit said second stream.
12. The system of claim 11 , wherein said transmitter is operable to:
receive feedback from a receiver of said second stream; and
adjust, based on said feedback from said receiver, a power at which said transmitting is performed.
13. The system of claim 12 , wherein said feedback from said receiver indicates a symbol error rate in said receiver.
14. The system of claim 11 , wherein said generation of said parity value comprises application of a parity function to participating symbols of said plurality of information symbols.
15. The system of claim 14 , wherein said application of said parity function comprises a summation of values of said participating symbols.
16. The system according to claim 15 , wherein said parity function is configured to ensure that said parity value is within a range of values determined by a symbol constellation used for said generation of said plurality of information symbols.
17. The system of claim 14 , wherein said transmitter is operable to select said parity function based on a signal to noise ratio in a receiver of said second stream.
18. The system of claim 14 , wherein said participating symbols are non-adjacent information symbols of said first stream.
19. The system of claim 14 , wherein said transmitter is operable to select which of said plurality of information symbols to use as said participating symbols based on error event length and/or signal-to-noise ratio in a receiver of said second stream.
20. The system of claim 11 , wherein said first frequency response is a low-pass response and said second frequency response is a high-pass response.