Efficient nonlinear equalizer for transmitter predistortion
AssigneeCisco Technology, Inc.
InventorsHongbin Zhang, Sheng Zhang, Tymon Barwicz
Life of this patent
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Abstract
A method, system and apparatus for mapping a symbol from a N-QAM constellation into a binary bit set, where N is the number of symbols in the constellation, and reducing the length of the binary bit set according to at least one property of nonlinear distortion by generating a lookup table (LUT) address from a LUT address generator, and adding the LUT address to a LUT of size smaller than N{circumflex over ( )}(2M+1), where 2M is the number of neighboring symbols to be stored.
Claims23
A method comprising:
- mapping a symbol from an optical N-QAM (quadrature amplitude modulation) constellation into a binary bit set;
- wherein N is the number of symbols in the constellation;
- reducing a length of the binary bit set;
- wherein the reduction is performed according to at least one property of nonlinear distortion;
- generating a lookup table (LUT) address from a LUT address generator;
- and
- adding the LUT address to a LUT of size smaller than N{circumflex over ( )}(2M+1);
- wherein 2M is the number of neighboring symbols to be stored.
A system for mapping an optical N-QAM constellation comprising:
- a semiconductor optical amplifier (SOA);
- logic comprising:
- mapping a symbol from the optical N-QAM (quadrature amplitude modulation) constellation into a binary bit set;
- wherein N is the number of symbols in the constellation;
- reducing a length of the binary bit set;
- wherein the reduction is performed according to at least one property of nonlinear distortion;
- generating a lookup table (LUT) address from a LUT address generator;
- and
- adding the LUT address to a LUT of size smaller than N{circumflex over ( )}(2M+1);
- wherein 2M is the number of neighboring symbols to be stored.
An apparatus for mapping an optical N-QAM (quadrature amplitude modulation) constellation comprising:
- a semiconductor optical amplifier (SOA);
- an address generator circuit to reduce a length of a binary bit set;
- and
- logic comprising:
- mapping a symbol from the optical N-QAM constellation into the binary bit set;
- wherein N is the number of symbols in the constellation;
- reducing the length of the binary bit set;
- wherein the reduction is performed according to at least one property of nonlinear distortion;
- generating a lookup table (LUT) address from a LUT address generator;
- and
- adding the LUT address to a LUT of size smaller than N{circumflex over ( )}(2M+1);
- wherein 2M is the number of neighboring symbols to be stored.
Dependencies are inferred from the claim text.