Abstract: System and method of comparing-selecting state metric values for high speed Viterbi decoding. In an Add-Compare-Select (ACS) unit, a select control signal is produced by Boolean operations on comparator decision signals and used to control a multiplexer structure. The comparator decision signals can be generated in parallel by an array of comparators comparing all possible pairs of a set of state metrics values. The Boolean operations are predefined through Boolean algebra that uses the decision signals as variables and complies with restriction imposed by the selection criteria, e.g., to select an minimum or maximum value of the set of state metrics values. The Boolean operations are performed by a logic module implemented using basic logic gates, such as AND, OR and NOT. As a result, the multiplexer structure that receives the set of input values can output the optimum value responsive to the select control signal.

Abstract: System and method of timing recovery for recovering a clock signal by using adaptive channel response estimation. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. More particularly, the channel estimation coefficients used in a channel estimator can be adapted based on an error signal representing the difference between a received signal at the timing recovery loop and an estimated signal output from a channel estimator. Further, to prevent undesirable interaction between the channel estimator and the overall timing recovery loop with respect to clock phase recovery, the adaptation of channel estimation can be controlled in terms of speed or time so as to reduce or eliminate the channel estimator's effect on clock phase correction.

Abstract: System and method of timing recovery for recovering a clock signal with reduced interaction between an adaptive channel estimator and the overall timing loop for correcting clock phase. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. The channel estimator includes compensation logic operable to detect and compensate a correction of clock phase ascribed to the channel estimator. The compensation logic can calculate the offset between a center of filter (COF) value and a COF nominal value, the offset indicative of the amount and direction of clock phase correction contributed by the channel estimator. Based on the offset, the compensation logic adjusts the estimates channel response by adjusting the tap weights of the channel estimator to correct the offset, thereby compensating the clock phase correction.

Abstract: System and method of timing recovery for recovering a clock signal with reduced interaction between an adaptive channel estimator and the overall timing loop for correcting clock phase. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. The channel estimator includes compensation logic operable to detect and compensate a correction of clock phase ascribed to the channel estimator. The compensation logic can calculate the offset between a center of filter (COF) value and a COF nominal value, the offset indicative of the amount and direction of clock phase correction contributed by the channel estimator. Based on the offset, the compensation logic adjusts the estimates channel response by adjusting the tap weights of the channel estimator to correct the offset, thereby compensating the clock phase correction.

Abstract: System and method of timing recovery for recovering a clock signal by using adaptive channel response estimation. The channel response estimation in the timing recovery loop is dynamically adapted to the current channel response that varies over time. More particularly, the channel estimation coefficients used in a channel estimator can be adapted based on an error signal representing the difference between a received signal at the timing recovery loop and an estimated signal output from a channel estimator. Further, to prevent undesirable interaction between the channel estimator and the overall timing recovery loop with respect to clock phase recovery, the adaptation of channel estimation can be controlled in terms of speed or time so as to reduce or eliminate the channel estimator's effect on clock phase correction.

Abstract: System and method of comparing-selecting state metric values for high speed. Viterbi decoding. In an Add-Compare-Select (ACS) unit, a select-control signal is produced by Boolean operations on comparator decision signals and used to control a multiplexer structure. The comparator decision signals can be generated in parallel by an array of comparators comparing all possible pairs of a set of state metrics values. The Boolean operations are predefined through Boolean algebra that uses the decision signals as variables and complies with restriction imposed by the selection criteria, e.g., to select an minimum or maximum value of the set of state metrics values. The Boolean operations are performed by a logic module implemented using basic logic gates, such as AND, OR and NOT. As a result, the multiplexer structure that receives the set of input values can output the optimum value responsive to the select control signal.

Abstract: System and method of calibrating the DC offsets of alternate comparators in an ADC in the background based on the digital outputs of the ADC. In parallel with A/D conversion of a plurality of samples, the calibration logic uses two counters to count the occurrences of the ADC outputs that represent samples falling in a first analog range and a second analog range, respectively. The two ranges are symmetric about the MSB reference voltage and in combination cover the nominal voltage range of the bit. The DC offset is derived based on a ratio of the difference between the two counts and a sum of the two counts. The calibration logic may alternately calibrate the comparators. Each comparator may be calibrated successively based on various bits associated therewith.

Abstract: Systems and methods of mitigating precursor ISIs for communication channels having time-variant precursor channel responses using digital circuit designs. A phase adaptation circuit is utilized in a receiver and configured to generate a phase control signal responsive to an input signal and based on the current precursor channel response. The phase control signal controls the phase shift of a recovered clock to a position where the precursor ISI at h(?1) is minimized. The phase control signal corresponds to a “feed-forward equalization (FFE) first tap weight” obtained via a digital least-mean-square (LMS) process.

Abstract: Systems and methods of mitigating precursor ISIs for communication channels having time-variant precursor channel responses using digital circuit designs. A phase adaptation circuit is utilized in a receiver and configured to generate a phase control signal responsive to an input signal and based on the current precursor channel response. The phase control signal controls the phase shift of a recovered clock to a position where the precursor ISI at h(?1) is minimized. The phase control signal corresponds to a “feed-forward equalization (FFE) first tap weight” obtained via a digital least-mean-square (LMS) process.

Abstract: Systems and methods for generating gapped signals comprising a Delta Sigma Modulator (DSM) configured to generate gapping control signals used to control gap removal rates of an associated gapping unit. The DSM is configured to generate a gapping control signal based on a value of an overflow resulted from performing adding a first number with a remainder of a stored value modulo a second number. The gap removal rates as well as the gap removal resolutions can be adjusted by selecting appropriate values of the first number, the stored value, and the second number. The gapping resolution can be a portion of a pulse. The first number and the second number may be derived from an intended frequency ratio between a gapped signal and a corresponding input signal. The gapping unit may comprise a gapping circuit or a multi-modulus divider.

Abstract: Systems and methods for frequency synthesis using a gapper and a multi-modulus divider. A frequency synthesizer may comprise a gapper, a multi-modulus divider and a Phase Locked Loop (PLL). When a frequency of an output signal is intended to be greater than a corresponding input signal, a factor can be borrowed by the gapper from the divider to generate a rational divide ratio G that is greater 1 in order for the gapper to be capable of performing the division by G. The PLL is capable of multiplying a gapped signal output from the first integer divider and attenuating jitter from the gapped signal.

Abstract: A novel and useful apparatus for and method of packet detection and carrier frequency offset estimation. The packet detection mechanism is robust to channels and sustains reasonable miss-detect (and false alarm) rates at low SNR values. The mechanism uses a modified combined cross correlation and delay and correlate scheme. A delay and correlate scheme is used in order to handle the effects of multipath while swapping integration and multiplication to increase cross-correlation factors resulting in improved sensitivity in low SNR conditions. Correlation is divided into multiple chains to generate a plurality of partial correlations to observe short patterns in the spread sequence resulting in improved performance in long multipath channels.

Abstract: A machine implemented method includes determining a signal modulation for each of a plurality of profiles; generating a first indicator indicating a signal modulation determined for a first profile in the plurality of profiles; generating a second indicator indicating a relationship between the signal modulation for the first profile and the signal modulation for each of the other profiles; notifying at least one node of the first and second indicators.

Abstract: A method in a first node of a network comprises computing a packet duration when using a first unicast profile with a first type preamble and a packet duration when using a second unicast profile with a second type preamble; comparing the computed packet durations so as to determine one from the first and second unicast profiles which yields a shorter duration; and sending the packet to a second node by using the determined unicast profile.

Abstract: Systems and methods for smoothing jitter generated by byte stuffing. A frequency synthesizer comprises a smoothing logic coupled with a PLL. The smoothing logic is configured to modify a phase error signal generated by a phase frequency detector into a distributed phase error signal that spread over multiple clock cycles. The distributed phase error signal is used to drive a DCO. The smoothing logic may comprise a ramping logic operable to generate a series of ramping values to substitute a phase difference in the phase error signal. The phase difference may correspond to a stuffing byte.

Abstract: Systems and methods for efficient jitter mitigation or removal from a gapped signal. A phase mitigation module is employed to generate discrete correction values for modifying phase error signals detected between a gapped signal and a feedback signal of the PLL. The correction values can be digitally subtracted from the output of a phase frequency detector associated with the PLL. The sequence of correction values can be determined based on phase frequency differences between the input signal and a targeted feedback signal that is free of jitter and has a period equal to an average period of the input signal. An average of the correction values is substantially equal to zero, and an average of the modified phase error signal is substantially equal to zero.

Abstract: Systems and methods for efficient jitter mitigation or removal from a gapped signal. A phase mitigation module is employed to generate discrete correction values for modifying phase error signals detected between a gapped signal and a feedback signal of the PLL. The correction values can be digitally subtracted from the output of a phase frequency detector associated with the PLL. The sequence of correction values can be determined based on phase frequency differences between the input signal and a targeted feedback signal that is free of jitter and has a period equal to an average period of the input signal. An average of the correction values is substantially equal to zero, and an average of the modified phase error signal is substantially equal to zero.

Abstract: Systems and methods for frequency synthesis using a gapper and a multi-modulus divider. A frequency synthesizer may comprise a gapper, a multi-modulus divider and a Phase Locked Loop (PLL). When a frequency of an output signal is intended to be greater than a corresponding input signal, a factor can be borrowed by the gapper from the divider to generate a rational divide ratio G that is greater 1 in order for the gapper to be capable of performing the division by G. The PLL is capable of multiplying a gapped signal output from the first integer divider and attenuating jitter from the gapped signal.

Abstract: Systems and methods for smoothing jitter generated by byte stuffing. A frequency synthesizer comprises a smoothing logic coupled with a PLL. The smoothing logic is configured to modify a phase error signal generated by a phase frequency detector into a distributed phase error signal that spread over multiple clock cycles. The distributed phase error signal is used to drive a DCO. The smoothing logic may comprise a ramping logic operable to generate a series of ramping values to substitute a phase difference in the phase error signal. The phase difference may correspond to a stuffing byte.

Abstract: Systems and methods for generating gapped signals comprising a Delta Sigma Modulator (DSM) configured to generate gapping control signals used to control gap removal rates of an associated gapping unit. The DSM is configured to generate a gapping control signal based on a value of an overflow resulted from performing adding a first number with a remainder of a stored value modulo a second number. The gap removal rates as well as the gap removal resolutions can be adjusted by selecting appropriate values of the first number, the stored value, and the second number. The gapping resolution can be a portion of a pulse. The first number and the second number may be derived from an intended frequency ratio between a gapped signal and a corresponding input signal. The gapping unit may comprise a gapping circuit or a multi-modulus divider.