Abstract: A system and method are provided for non-causal channel equalization in a communications system. The method comprises: establishing three thresholds; receiving a binary serial data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; data stream inputs below the first threshold and above the third threshold are a “0” if both the second and third bits are “1” values, and as a “1” if either of the second and third values is a “1”; data stream inputs above the second threshold and below the third threshold are a “1” if both the second and third bits are a “0” value, and as a “0” if either of the second and third values is a “0”.

Abstract: A system and method are provided for non-causal channel equalization in a communications system. The method comprises: establishing three thresholds; receiving a binary serial data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; data stream inputs below the first threshold and above the third threshold are a “0” if both the second and third bits are “1” values, and as a “1” if either of the second and third values is a “1”; data stream inputs above the second threshold and below the third threshold are a “1” if both the second and third bits are a “0” value, and as a “0” if either of the second and third values is a “0”.

Abstract: A system and method are provided for maximum likelihood estimation in a channel receiving data with inter-symbol interference (ISI). The method receives a serial stream of digital information bits. Decisions are made concerning the received information bit values, which the method accepts as processed information, with soft decisions (SDs) and corresponding initial hard decisions (HDs). The method then identifies a sequence of processed information in a correction matrix, and uses the correction matrix to cross-reference the sequence to a HD look-up value. In response to accessing the HD look-up value, a modified HD is created. The modified HD is decoded, for example, by using forward error correction (FEC), creating a decoded HD. The method compares the decoded HD to the initial HD, and updates the correction matrix HD look-up value in response to the comparison.

Abstract: A system and method are provided for five-level non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; establishing a five-level threshold; comparing the first bit estimate to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; and, in response to the comparisons, determining the value of the first bit. Establishing a five-level threshold includes: establishing thresholds to distinguish a first bit value when the second and third bit values are a “1” value, when the second bit value is a “1” and the third bit value is a “0”, when the second bit value is a “0” and the third bit value is a “1”, when the second and third bit values are a “0” value, and an approximate midway threshold.

Abstract: A system and method are provided for maximum likelihood estimation in a channel receiving data with inter-symbol interference (ISI). The method receives a serial stream of digital information bits. Decisions are made concerning the received information bit values, which the method accepts as processed information, with soft decisions (SDs) and corresponding initial hard decisions (HDs). The method then identifies a sequence of processed information in a correction matrix, and uses the correction matrix to cross-reference the sequence to a HD look-up value. In response to accessing the HD look-up value, a modified HD is created. The modified HD is decoded, for example, by using forward error correction (FEC), creating a decoded HD. The method compares the decoded HD to the initial HD, and updates the correction matrix HD look-up value in response to the comparison.

Abstract: A system and method are provided for coding a frame in a packet communications system using a G.709 Digital Wrapper Frame format. The method comprises: accepting digital information; outer encoding the digital information with a Reed Solomon (RS) encoding scheme; interleaving the outer encoded information; inner encoding the interleaved information using a BCH encoding scheme; and, forming a G.709 Digital Wrapper frame including payload and parity bytes. More specifically, a standard DW superframe is formed with 122,368 bits of payload and 8192 bits of parity. The outer encoding process uses an RS(1023,1007) parent code. In one aspect, 15 groups of RS(781,765) and 1 group of RS(778,762) codewords are formed per superframe. The inner encoding process uses a BCH(2047,1959) parent code. In one aspect, 64 groups of BCH(2040,1952) codewords are formed per superframe.

Abstract: A modified gain system and method are provided for non-causal channel equalization using feed-forward and feedback compensation. The method comprises: receiving a serial data stream first bit (present) input; comparing a second bit (past) value, received prior to the first bit input, to a third bit (future) value received subsequent to the first bit input; modifying the amplitude of the first bit input to compensate for the effect of the second and third bit values being equal; and, determining the value of the first bit input by comparing the amplitude modified first bit input to a Vopt threshold. When only one of the second and third bit values is a “1” value, a unity amplitude modifier is supplied. When the second and third bit values are a “1”, a low amplitude modifier is supplied. When the second and third bit values are a “0”, a high amplitude modifier is supplied.

Abstract: A system and method are provided for non-causal channel equalization in a communications system. The method comprises: establishing three thresholds; receiving a binary serial data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; data stream inputs below the first threshold and above the third threshold are a “0” if both the second and third bits are “1” values, and as a “1” if either of the second and third values is a “1”; data stream inputs above the second threshold and below the third threshold are a “1” if both the second and third bits are a “0” value, and as a “0” if either of the second and third values is a “0”.

Abstract: A system and method are provided for five-level non-casual channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; establishing a five-level threshold; comparing the first bit estimate to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; and, in response to the comparisons, determining the value of the first bit. Establishing a five-level threshold includes: establishing thresholds to distinguish a first bit value when the second and third bit values are a “1” value, when the second bit value is a “1” and the third bit value is a “0”, when the second bit value is a “0” and the third bit value is a “1”, when the second and third bit values are a “0” value, and an approximate midway threshold.

Abstract: A state machine method and system are provided for determining non-causal channel equalization thresholds. The method comprises: receiving a non-return to zero (NRZ) data stream encoded with forward error correction (FEC); setting x=0; in State 0, adjusting a third threshold (Vopt) in response to corrected bit errors; if x=0, setting a first and second threshold equal to the third threshold; in State 1, if x=0, simultaneously adjusting the first threshold and the second threshold, to minimize the total number of corrected bit errors; in State 2, following State 0, adjusting the first threshold, independent of the second threshold, to minimize the total number of errors; in State 3, following State 0, adjusting the second threshold, independent of the first threshold, to minimize the total number of errors; and, adding 1 to x and returning to State 0.

Abstract: A system and method are provided for non-causal channel equalization in a communications system. The method comprises: establishing a first threshold (V1) to distinguish a high probability “1” first bit estimate; establishing a second threshold (V0) to distinguish a high probability “0” first bit estimate; establishing a third threshold (Vopt) to distinguish first bit estimates between the first and second thresholds; receiving a non-return to zero (NRZ) data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; in response to the comparisons, determining the value of the first bit.

Abstract: A system and method are provided for feed-forward/feedback non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; using three thresholds, estimating a first bit in the data stream; using two thresholds, determining a third bit value received subsequent to the first bit; comparing the first bit estimate to the third bit value; comparing the first bit estimate to a second bit value received prior to the first bit; and, in response to the comparisons, determining the value of the first bit. In some aspects of the method, the third bit value is determined in response to a prior third bit value determination. Determining a third bit value includes: distinguishing NRZ data stream inputs between fourth and fifth thresholds as a “0” if the prior third bit value was a “1”, and as a “1” if the prior third bit value was a “0”.

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.

Abstract: A system and method is provided for using phase adjustment in non-causal channel equalization in a communications system. The method comprising: receiving a serial data stream input; comparing a bit value in the serial data stream determined at a first phase with respect to a clock, to a bit value determined at a second phase; determining the optimal phase for the determination of bit values; and, using the optimal phase to determine subsequently received bit values. Typically, the serial data stream is encoded with forward error correction (FEC). Then, the method further comprises: FEC decoding the bit values determined at a plurality of phases. Determining the optimal phase for the determination of bit values includes calculating an error rate associated with the phases and, defining the optimal phase as the phase associated with a low error rate.

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.

Abstract: A system and a method are provided for non-causal channel equalization using error statistics. The method comprises: receiving a non-return to zero (NRZ) data stream input encoded with forward error correction (FEC); establishing a plurality of thresholds to generate a first bit estimate; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; in response to the comparisons, determining the value of the first bit; FEC decoding the determined first bit value; and, using FEC error statistics to adjust the thresholds by evaluating the number of errors associated with a plurality of three-bit sequence combinations.

Abstract: A method for computing the function log(ex1+ex2) or ln(ex1+ex2) for a first argument value x1 and a second argument value x2 includes generating a table having a first data field and a second data field. The first data field includes N entries of table index values selected from a range of |x1?x2| argument values and scaled by a scaling factor. The second data field includes N entries of computed table values computed based on the equation log(1+e?|x1?x2|) or ln (1+e?x1?x2|) for each of the |x1?x2| argument values selected for the table index values. The computed table values are also scaled by the same scaling factor.

Abstract: A method for performing a table look-up operation on a first table having N entries includes generating a second table having kN entries based on the first table. The method includes generating a first data field for the second table including table index values having a second interval derived from a first interval of the table index values of the first table and represented by an n-bit binary number; and generating a second data field including computed table values derived from the computed table values of the first table or computed based on the function defining the second data field. The method further includes computing an index value z, extracting address bits from the index value z, where the address bits are data bits more significant than the (n-1)th bit of the index value z, and addressing the second table using the address bits.

Abstract: A system and method are provided for feed-forward/feedback non-causal channel equalization in a communications system. The method comprises: receiving a non-return to zero (NRZ) data stream input; using three thresholds, estimating a first bit in the data stream; using two thresholds, determining a third bit value received subsequent to the first bit; comparing the first bit estimate to the third bit value; comparing the first bit estimate to a second bit value received prior to the first bit; and, in response to the comparisons, determining the value of the first bit. In some aspects of the method, the third bit value is determined in response to a prior third bit value determination. Determining a third bit value includes: distinguishing NRZ data stream inputs between fourth and fifth thresholds as a “0” if the prior third bit value was a “1”, and as a “1” if the prior third bit value was a “0”.

Abstract: A system and method are provided for non-casual channel equalization in a communications system. The method comprises: establishing a first threshold (V1) to distinguish a high probability “1” first bit estimate; establishing a second threshold (V0) to distinguish a high probability “0” first bit estimate; establishing a third threshold (Vopt) to distinguish first bit estimates between the first and second thresholds; receiving a non-return to zero (NRZ) data stream; comparing the first bit estimate in the data stream to a second bit value received prior to the first bit; comparing the first bit estimate to a third bit value received subsequent to the first bit; in response to the comparisons, determining the value of the first bit.