US 7,024,599 B2 · System and method for non-causal channel equalization

Abstract

A system and method are provided for non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; establishing thresholds to distinguish a first bit estimate; comparing the first bit estimate in the NRZ data stream to a second bit value received prior to the first bit, and a third bit received subsequent to the first bit; in response to the comparisons, determining the value of the first bit; tracking the NRZ data stream inputs in response to sequential bit value combinations; maintaining long-term averages of the tracked NRZ data stream inputs; adjusting the thresholds in response to the long-term averages; and, offsetting the threshold adjustments to account for the asymmetric noise distribution. Two methods are used to offset the threshold adjustments to account for the asymmetric noise distribution: forward error correction (FEC) decoding and tracking the ratio of bit values.

Claims32

Dependent claims

A non-causal channel equalization communication system, the system comprising:

a multi-threshold circuit having an input to accept a non-return to zero (NRZ) data stream, an input to accept threshold values, and outputs to provide a plurality of bit estimates for each NRZ data in the NRZ data stream, responsive to a plurality of voltage threshold levels;
and,
a non-causal circuit having inputs to accept the bit estimates from the multi-threshold circuit and an output to supply a first bit value for a current clock cycle in response to comparing bit estimates for the current clock cycle, to bit values determined in prior and subsequent clock cycles.

A non-causal channel equalization communication system, the system comprising:

a multi-threshold circuit having an input to accept a data stream and outputs to provide a plurality of bit estimates for each data in the data stream, responsive to a plurality of voltage threshold levels;
and,
a non-causal circuit having an input to accept the bit estimates from the multi-threshold circuit and an output to supply a first bit value for a current clock cycle in response to comparing bit estimates for the current clock cycle to bit values determined in prior and subsequent clock cycles.

A non-causal channel equalization communication system, the system comprising:

a multi-threshold circuit having an input to accept a data stream encoded with forward error correction and an output to provide a plurality of bit estimates for each data in the data stream, responsive to a plurality of voltage threshold levels;
a non-causal circuit having an input to accept the bit estimates from the multi-threshold circuit and an output to supply a first bit value for a current clock cycle in response to comparing bit estimates for the current clock cycle to bit values determined in prior and subsequent clock cycles;
and,
a forward error correction (FEC) circuit having an input to receive the first bit value from the non-causal circuit, the FEC circuit decoding the data stream and correcting first bit values in response to the decoding, the FEC circuit having an output to supply threshold levels to the multi-threshold circuit in response to the FEC corrections.

1 more element

Dependencies are inferred from the claim text.

System and method for non-causal channel equalization

Life of this patent

System and method for non-causal channel equalization

Life of this patent

Abstract

Claims32