A receiver includes a decision feed forward equalization (DFFE) system that generates, based on a digital signal that includes at least one intersymbol interference (ISI) value introduced by a communication channel, a detected signal including a set of detected symbol values. The DFFE system cancels the at least one ISI value from the detected signal using the set of estimated transmitted symbols and a set of tap coefficients to obtain a compensated signal and a set of compensated symbol values.

An efficient communications apparatus is described for a vector signaling code to transport data and optionally a clocking signal between integrated circuit devices. Methods of designing such apparatus and their associated codes based on a new metric herein called the “ISI Ratio” are described which permit higher communications speed, lower system power consumption, and reduced implementation complexity.

Methods and systems are described for receiving signal elements corresponding to a first group of symbols of a vector signaling codeword over a first densely-routed wire group of a multi-wire bus at a first set of multi-input comparators (MICs), receiving signal elements corresponding to a second group of symbols of the vector signaling codeword over a second densely-routed wire group of the multi-wire bus at a second set of MICs, and receiving signal elements corresponding to the first and the second groups of symbols of the vector signaling codeword at a global MIC.

Methods, systems, and devices for techniques for communicating multi-level signals are described. A first device may be configured to communicate signals with a second device according to a modulation scheme. The first device may transmit a first signal to the second device at a first voltage level of the modulation scheme corresponding to a first multi-bit value. The first device may select a second voltage level of the modulation scheme based on a difference between the first voltage level and a third voltage level of the PAM scheme, and may transmit a second signal to the second device at the second voltage level to indicate a second multi-bit value corresponding to the third voltage level. The second device may decode the second signal to determine the second multi-bit value based on receiving the first signal at the first voltage level and the second signal at the second voltage level.

System and method indicating delays added to packets due to retransmission events. The method includes the steps of receiving multiple packet streams and multiplexing them into a first multiplexed packet stream; storing in memory the first multiplexed packet stream together with time indications; receiving a retransmission request and selecting data for retransmission; multiplexing the first multiplexed packet stream and the data for retransmission into a second multiplexed packet stream; utilizing the time indications for calculating delays that were added to packets of the second multiplexed packet stream as a result of fulfilling the retransmission request; adding the calculated delays to at least some of the packets of the second multiplexed packet stream; and transmitting the second multiplexed packet stream.

Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with precalculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.

Systems and methods are described for transmitting data over physical channels to provide a high bandwidth, low latency interface between a transmitting device and a receiving device operating at high speed with low power utilization. Communication is performed using group signaling over sets of four wires using a vector signaling code, where each wire of a set carries a low-swing signal that may take on one of four signal values. Topologies and designs of wire sets are disclosed with preferred characteristics for group signaling communications.

A communication link comprising: a first transceiver configured to transmit a first set of packets at a predetermined rate with a first error resistance level, store the transmitted data in a buffer, receive a retransmission request, and retransmit the relevant data using one or more packets encoded with a second error resistance level that is higher than the first error resistance level. And a second transceiver configured to receive the first set of packets, detect an erroneous packet, request retransmission of the erroneous packet, and forward the data received in the packets according to its original order approximately after a fixed delay.

Generating, during a first and second signaling interval, an aggregated data signal by forming a linear combination of wire signals received in parallel from wires of a multi-wire bus, wherein at least some of the wire signals undergo a signal level transition during the first and second signaling interval; measuring a signal skew characteristic of the aggregated data signal; and, generating wire-specific skew offset metrics, each wire-specific skew offset metric based on the signal skew characteristic.

Equalization methods and equalizers employing discrete-time filters are provided with dynamic perturbation effect based adaptation. Tap coefficient values may be individually perturbed during the equalization process and the effects on residual ISI monitored to estimate gradient components or rows of a difference matrix. The gradient or difference matrix components may be assembled and filtered to obtain components suitable for calculating tap coefficient updates with reduced adaptation noise. The dynamic perturbation effect based updates may be interpolated with precalculated perturbation effect based updates to enable faster convergence with better accommodation of analog component performance changes attributable to variations in process, supply voltage, and temperature.