System and method for forward error correction decoding using soft information
AssigneeTyco Telecommunications (US) Inc.
InventorsYi Cai, Jin-Xing Cai, Morten Nissov
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Abstract
A system and method for soft decision forward error correction (FEC) decoding may be used to determine a possible error in a differential detection signal, for example, in a DPSK system. The system and method uses the constructive and destructive signals from a demodulator to provide an error locating signal. Using the error locating signal, the system and method converts the differential detection signal into a soft decision signal including multi-level soft values.
Claims18
A receiver for receiving a modulated signal containing a forward error correction (FEC) encoded data stream, said receiver comprising:
- a demodulator operable to receive said modulated signal and to demodulate said modulated signal to produce a constructive signal and a destructive signal;
- a differential detector operable to receive said constructive and destructive signals and to produce a hard decision differential detection signal corresponding to said FEC encoded data stream;
- and
- a soft decision FEC decoding system operable to receive said constructive and destructive signals and said differential detection signal, said FEC decoding system being configured to determine a possible error in said differential detection signal using hard-decision detection of each of said constructive and destructive signals, to convert said differential detection signal into a soft decision signal including multi-level soft values, and to decode said soft decision signal.
An optical communication system, comprising:
- a transmitter comprising an encoder for forward error correction (FEC) encoding a data stream and a modulator for modulating said FEC encoded data stream to produce a modulated FEC encoded signal;
- and
- a receiver comprising:
- a demodulator operable to receive said modulated FEC encoded signal and to produce a constructive signal and a destructive signal;
- a differential detector operable to receive said constructive and destructive signals and to produce a hard decision differential detection signal corresponding to said FEC encoded data stream;
- and
- a soft decision FEC decoding system operable to receive said constructive and destructive signals and said differential detection signal, said FEC decoding system being operable to determine a possible error in said differential detection signal using hard-decision detection of each of said constructive and destructive signals, to convert said hard decision differential detection signal into a soft decision signal including multi-level soft values, and to decode said soft decision signal.
Dependencies are inferred from the claim text.