Patent Description:
Differential signaling is a method of transmitting information with two complementary signals on two conductors, such as paired wires. Differential signaling usually improves resistance to electromagnetic interference (EMI) since the information is conveyed through the difference between the voltages on the wires. However, if there are imbalances or asymmetries between the two conductors, common mode components may arise even when the two conductors are differentially driven. The presence of common mode currents on a cable does not inherently degrade the integrity of differential signaling, but if energy can be transferred from a common mode to a differential mode, then the common mode current can become a dominant interference signal, in a phenomenon known as mode-conversion or mode coupling.

Mode conversion can cause significant performance degradation. While internal interference sources (such as ISI, echo, FEXT, and NEXT) are known to the link partners and can be cancelled effectively with cancellers and equalizers, the mode conversion interference is unknown until it occurs, and thus presents difficulties for the desired performance of high bandwidth communication systems.

<CIT> describes a transceiver that performs adaptive tone cancellation for mitigating common mode interferences. The transceiver does not use slicing errors to adapt the adaptive digital equalizer and canceller.

European Patent Application <CIT> describes a digital subscriber line (DSL) transceiver that adapts its transmission rate according to the noise changes in the line to avoid link drop. After the line noise is reduced, the line rate may be dynamically increased, thereby improving the transmission capacity. US Patent No. <CIT> regards fast retraining of transceiver communication parameters.

The present invention provides a transceiver in accordance with claim <NUM>.

In a second aspect, the invention provides a method for recovering within less than <NUM> millisecond from quality degradation in a transceiver's operating point in accordance with claim <NUM>.

The embodiments are herein described, by way of example only, with reference to the accompanying drawings. In the drawings:.

<FIG> illustrates one embodiment of a transceiver configured to converge fast. Transceiver <NUM> (which does not includes the channel <NUM> and the transceiver <NUM>) includes the following elements: a common mode sensor analog front end (CMS-AFE <NUM>), a fast-adaptive mode-conversion canceller (FA-MCC <NUM>), a receiver analog front end (Rx AFE <NUM>), an adaptive digital equalizer and canceller (ADEC <NUM>), a slicer <NUM> (that includes a soft decision <NUM>, a selector <NUM>, and an error generator <NUM>), a Physical Coding Sublayer (PCS <NUM>), a link layer <NUM>, a controller <NUM>, a selector <NUM>, a transmitter PCS (Tx PCS <NUM>), a transmitter digital sampler (Tx dig samp <NUM>), and a transmitter AFE (Tx AFE <NUM>).

The soft decision <NUM> decides on the reconstructed representation of the original transmitted signal <NUM> by slicing the reconstructed representation of the original transmitted signal <NUM>. In one embodiment, when a serious interference is too high, the ability of the soft decision <NUM> to make an accurate decision may not be good enough, and/or the convergence time of the transceiver <NUM> may be too long. Thus, the controller <NUM> requests the transceiver <NUM> to transmit known data (such as to transmit the idle sequence, or a sequence based on the idle sequence), and configures the selector <NUM> to output the known decision received from the PCS <NUM> instead of the probably wrong decision received from the soft decision <NUM>. As a result of configuring the selector <NUM> to output the known decision, the error generator <NUM> is now able to generate the correct error based on the reconstructed representation of the original transmitted signal <NUM> and the known decision <NUM> received from the PCS <NUM>. The correct error enables the ADEC <NUM> and FA-MCC <NUM> to converge fast because their convergence speed is function of the noisiness of the error, and thus receiving the correct error accelerates their convergence. Using the known decision <NUM> also reduces the error propagation of the ADEC <NUM> because the correct decision is fed from selector <NUM> over line <NUM> to the ADEC <NUM>. Therefore, having the correct error by injecting the known decision <NUM> supports fast adaptation, reduces error propagation, and moves the transceiver <NUM> into a stable state - also when the differential communication channel suffers from a serious interference.

<FIG> illustrates an alternative embodiment of a transceiver configured to converge fast. Transceiver <NUM> does not include an FA-MCC component, although the ADEC <NUM> may include the functionality of the FA-MCC <NUM>. Controller <NUM> may be similar to controller <NUM>, which the difference that controller <NUM> may be designed to operate without an FA-MCC component.

In one embodiment, first and second transceivers configured to forward time sensitive data at a predetermined average rate and up to a predetermined packet delay variation, comprising:
An Rx analog front end (AFE) and a common mode sensor AFE (CMS-AFE) that couple the second transceiver to a differential communication channel coupled to the first transceiver. The differential communication channel is not completely known, and the first and second transceivers are expected to work at a first packet loss rate when there is no serious interference. From time to time the differential communication channel may suffer from serious interferences that increase significantly the packet loss rate to a second packet loss rate that is at least ten times the first packet loss rate.

The CMS-AFE is configured to extract a digital representation of a common mode signal of the received differential signal, and forward it to a fast-adaptive mode-conversion canceller (FA-MCC) configured to generate a compensation signal to cancel the differential interference caused by mode-conversion of the common mode signal.

The FA-MCC is further configured to utilize large adaptation step size to cancel the effect of the serious interference fast.

The Rx AFE is configured to extract the received differential signal and feed it to an adaptive digital equalizer and canceller (ADEC). The ADEC includes one or more equalizers, such as Decision Feedback Equalizer (DFE) and/or Feed-Forward Equalizer (FFE), and one or more cancellers, such as FEXT canceller.

The FA-MCC and the ADEC are configured to reconstruct a representation of the original transmitted signal, and feed the representation of the original transmitted signal to a slicer configured to feeds a Physical Coding Sublayer (PCS) with sliced symbols. In one example, the original transmitted signal is the signal sent from the first transceiver before shaping.

The PCS is configured to extract a bitstream from the sliced symbols, and to feed a link layer component configured to parse the sliced symbols into packets. It is noted that bitstream includes bytestream and all other similar equivalents.

The link layer component comprises a retransmission module configured to: request retransmission of packets with errors, and forward the packets in the correct order after receiving the retransmitted packets. It is noted that packets with errors includes missing packets and any other packet that may require retransmission.

And the FA-MCC is configured to converge at a short time, such that the retransmissions caused by the serious interference still enable the transceiver to forward packets at the predetermined average rate and within the predetermined packet delay variation.

<FIG> illustrates one embodiment of a communication system operating over a differential communication channel that is not completely known and may suffer from serious common-mode-to-differential-mode interference (in some cases may be shortly referred to as "serious interference"). The communication system includes a transceiver <NUM> and a transceiver <NUM> (which does not include the transceiver <NUM> and the channel <NUM>), capable of communicating at a high throughput, with communication rates possibly exceeding <NUM> Mbps, <NUM>. 2Gbps, or 10Gbps.

The communication system is implemented, at least in part, on Integrated Circuits (ICs) having limited resources. The communication system further implements a retransmission module on the ICs. In one embodiment, the first transceiver utilizes a retransmission module <NUM> that uses a buffer <NUM> to store packets that may have to be retransmitted. In one embodiment, the second transceiver utilizes a retransmission module <NUM> that uses a buffer <NUM> to store the received packets until all the packets are received successfully, and then the buffer may forward the received packets in the correct order to a client. Additionally or alternatively, the retransmission module <NUM> may use the buffer <NUM> to store the received packets for a short period until it is possible to forward them to the client, optionally in the order of their arrival, which may not be the correct order.

The sizes of the buffers (<NUM>, <NUM>) used by the retransmission module may be limited in order to save cost. In one example, the buffer <NUM> of the first transceiver can store up to <NUM> microseconds of traffic sent at the highest communication rate. In another example, the second transceiver forwards the packets in the correct order and the buffer <NUM> of the second transceiver can store up to <NUM> microseconds of traffic sent at the highest communication rate. In still another example, at least one of the buffers used by the first and second transceiver can store up to <NUM> microseconds of traffic sent at the highest communication rate.

Upon detecting a new serious interference, the second transceiver utilizes a fast-adaptive mode-conversion canceller (FA-MCC) to generate a compensation signal to cancel the differential interference caused by mode-conversion of the common mode signal. Optionally, until the interference is cancelled, the first transceiver retransmits the lost packets. The FA-MCC may not have in advanced information regarding the properties of the interference, and thus the FA-MCC uses large adaptation step size that enables fast convergence. Although the actual size of the large adaptation step size depends on the specific implementation, a person skilled in the art should be able to calculate the values of the large adaptation step sizes to support convergence time that is short enough for the communication system to meet its design goals and/or real-time requirements. One example of a design goal is not to exceed the limited capacity of one or more of the buffers <NUM> and <NUM> used by the retransmission module. One example of a real-time requirement is not to exceed the maximum permitted delay allocated to the communication channel.

As a result of the large adaptation step size, the convergence of the FA-MCC after a serious interference is usually not optimal.

In one example, the serious interference causes packet loss to exceed <NUM>% at the second transceiver, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the second transceiver to less than <NUM>%. Optionally, packet loss is calculated as the number of packet lost divided by the number of packets sent.

In another example, the serious interference causes packet loss to exceed <NUM>% at the second transceiver, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the second transceiver to less than <NUM>%.

In still another example, the serious interference causes packet loss to exceed <NUM>% at the second transceiver, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the second transceiver to less than <NUM>%.

In one embodiment, the communication channel is relatively short (for example, shorter than <NUM> meters, or shorter than <NUM> meters) and thus is not considered difficult. In such a channel, the communication system can operate well enough with the non-optimal convergence of the FA-MCC because the leftover interference that was not cancelled does not prevent successful communication over the channel.

The digital canceller <NUM> may be implemented in various ways. <FIG> illustrates one example in which the digital canceller <NUM> includes at least an equalizer <NUM> and a Decision Based Filter (DBF) <NUM>. In one example, equalizer <NUM> may be a Feed Forward Equalizer (FFE).

The term "Decision Based Filter", such as DBF <NUM>, refers to a filter fed at least by a slicer's output, such as slicing results and/or slicing errors. In one example, the DBF includes a non-adaptive Decision Feedback Equalizer (DFE), or a non-adaptive FEXT canceller, fed by the slicing results. In another example, the DBF includes an adaptive DFE, or an adaptive FEXT canceller, fed by the slicing results and/or the slicing errors. In still another example, the DBF includes an adaptive Feed-Forward Equalizer (FFE) fed by the slicing errors for adaptation purpose.

The term "slicer" or "slicer function", such as slicer <NUM>, is defined as a one or more dimensional quantizer that outputs the quantization result. Optionally, the slicer may include different slicers for different modulations. Optionally, the slicer may output one or more of the following indications: the error between the received signal and the quantization result, the slicer function used for producing the slicing result, the direction of the slicing error, and/or other indications.

The slicing results are fed to a Physical Coding Sublayer (PCS), such as PCS <NUM>, which parses the data packets and extracts information such as a packet header, a packet payload, a packet tail, and/or an error detection code. It is noted that herein an "error detection code" also covers an "error correction code".

In one embodiment, the retransmission module <NUM> receives the parsed packets from the PCS <NUM>, and based on the received parsed packets it may request retransmission of the packets with errors. In one embodiment, one of the relationships between the FA-MCC and the retransmission module <NUM> is that the buffer <NUM> is large enough to buffer packets that are received until the FA-MCC cancels the effect of the serious interference. The combination of the FA-MCC and the retransmission module <NUM> enables the system to use small retransmission buffers also when operating over a communication channel that is not completely known and suffers from serious common-mode-to-differential-mode interference.

<FIG> illustrates one embodiment of a communication system operating over a differential communication channel that is not completely known and may suffer from serious common-mode-to-differential-mode interference. The communication system includes a transceiver <NUM> and a transceiver <NUM> (which does not include the transceiver <NUM> and the channel <NUM>), capable of communicating at a high throughput, with communication rates possibly exceeding <NUM> Mbps, 1Gbps, or 10Gbps.

The transceiver <NUM> is implemented on an integrated circuit (IC) having limited resources. The transceiver <NUM> includes at least first and second AFEs (<NUM>, <NUM>) coupled to the transceiver <NUM> over a differential communication channel <NUM> that is not completely known; from time to time the differential communication channel may suffer from serious interferences that prevent normal operation.

The CMS-AFE is configured to extract a digital representation of a common mode signal of the received differential signal, and forward it to a fast-adaptive mode-conversion canceller (FA-MCC) configured to generate a compensation signal to cancel the differential interference caused by mode-conversion of the common mode signal. The FA-MCC is further configured to utilize large adaptation step size to cancel the effect of the serious interference fast. The large adaptation step size enables it to cancel, within less than <NUM> microseconds, the effect of the serious common-mode-to-differential-mode interference to a level that enables the normal operation. The digital canceller <NUM> feeds a slicer <NUM> that feeds a PCS <NUM> with quantization results. The PCS <NUM> extracts packet data from the quantization results and drives a retransmission module <NUM> that requests retransmission of the packets with errors based on the packet data. In one embodiment, the retransmission module is limited to support retransmission of up to <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference.

In one embodiment, the retransmission module <NUM> is implemented on the IC with limited resources that cannot support retransmission of more than <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference. In one embodiment, the retransmission module includes a retransmission buffer <NUM> able to store up to <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference. In one embodiment, the retransmission module <NUM> is limited to support retransmission of up to <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference in order to achieve one or more of the following requirements: a maximum allowed jitter, a maximum amount of dropped packets, and requirements related to time sensitive data transmitted over the communication channel.

In one example, the retransmission module further comprises a buffer configured to store the received packets until all packets are received successfully. Additionally or alternatively, the size of the buffer is limited to store the amount of packets that are received during up to <NUM> microseconds of normal operation. Additionally or alternatively, the retransmission module further comprises a buffer configured to store the received packets until they are requested by a client.

In one example, the packet data comprises information related to a packet header, a packet payload, a packet tail, and/or an error detection code. Additionally or alternatively, the FA-MCC may not be configured to converge optimally, and as such may not reach an optimal solution even after <NUM> second. Additionally or alternatively, the digital canceller may include an equalizer and a Decision Based Filter (DBF). Additionally or alternatively, the equalizer may be a Feed Forward Equalizer (FFE). Additionally or alternatively, the DBF may be a filter fed by an output of the slicer.

In some embodiments, upon detecting a serious interference, the communication system reduces the code rate until the FA-MCC cancels the effect of the serious interference. After the FA-MCC cancels the effect of the serious interference, the communication system increases the code rate, optionally until returning to the code rate used before the serious interference was detected.

Reducing the code rate improves the packets' robustness to noise, and thus enables the transceiver to receive at least some of the packets successfully. Reducing the code rate may be implemented in addition to the retransmission module described above.

The code rate may be reduced by various techniques such as Dynamic Modulation Coding (DMC), adding Error Correction Code (ECC), and/or transmitting a known sequence (that reduces the code rate to practically zero).

In one embodiment, the code rate is reduced by decreasing the modulation order using Dynamic Modulation Coding (DMC). DMC is described, for example, in <CIT>, titled "Devices for transmitting digital video and data over the same wires", which is incorporated herein by reference in its entirety. For example, upon detecting a serious interference, a Pulse-Amplitude Modulation (PAM) transceiver may switch from using PAM16 to PAM4 until the FA-MCC cancels the effect of the serious interference, and then switch from PAM4 to PAM8, and from PAM8 back to PAM <NUM> when the channel properties allow.

In another embodiment, the code rate is reduced by adding ECC, either by adding ECC when there was no ECC, or by increasing the amount of the ECC overhead in order to improve the Signal to Noise Ratio (SNR). For example, the ECC may be added by continually adding ECC overhead to the stream, optionally in a similar manner to convolutional codes. Additionally or alternatively, the ECC may be added/ strengthened by adding the EC overhead to fixed length data segment, optionally in a similar manner to block codes.

In another embodiment, the code rate is reduced to practically zero by transmitting a known sequence. In one example, the known sequence is based on the scrambler sequence, such as transmitting the scrambler, or transmitting bitwise complement code words of the scrambler. In another example, the known sequence is based on the idle sequence, such as transmitting the idle sequence, or transmitting bitwise complement code words of the idle sequence. One embodiment of a transmitter that transmits bitwise complement code words of the idle sequence includes an encoder configured to encode a first frame, a basic idle sequence, and a second frame, wherein the first frame, the basic idle sequence, and the second frame include code words. The transmitter further includes an idle sequence modifier configured to produce an idle sequence by replacing certain M code words of the basic idle sequence with M bitwise complement code words (where, optionally, each bitwise complement code word appears in the basic idle sequence). Bitwise complement, also known as bitwise NOT, applies logical negation on each bit, forming the ones' complement of a given binary value. For unsigned integers, the bitwise complement of a number is the mirror reflection of the number across essentially the half-way point of the unsigned integer's range.

<FIG> illustrates one embodiment of a communication system operating over a differential communication channel <NUM> that is not completely known and may suffer from serious common-mode-to-differential-mode interference. The communication system includes a transceiver <NUM> and a transceiver <NUM> (which does not include the transceiver <NUM> and the channel <NUM>) capable of communicating at a high throughput, with communication rates possibly exceeding <NUM> Mbps, 1Gbps, or 10Gbps.

The communication system may be implemented, at least in part, on Integrated Circuits (ICs) having limited resources. In one embodiment, the transceiver <NUM> utilizes a retransmission module <NUM> that uses a buffer <NUM> to store the packets that may have to be retransmitted. In one embodiment, the transceiver <NUM> utilizes a retransmission module <NUM> that uses a buffer <NUM> to store the received packets until all the packets are received successfully.

In one embodiment, the sizes of the buffers (<NUM>, <NUM>) used by the retransmission modules may be limited in order to save cost. In one example, the buffer <NUM> of the transceiver <NUM> can store up to <NUM> microseconds of traffic sent at the highest communication rate. In another example, the transceiver <NUM> forwards the packets in the correct order and the buffer <NUM> of the transceiver <NUM> can store up to <NUM> microseconds of traffic sent at the highest communication rate. In still another example, at least one of the buffers of the transceiver <NUM> and transceiver <NUM> can store up to <NUM> microseconds of traffic sent at the highest communication rate.

Upon detecting a new serious interference, the transceiver <NUM> utilizes the FA-MCC with large adaptation step size to cancel the effect of the serious interference fast. Until the interference is cancelled, the rate controller <NUM> reduces the rate of transmitting the packets in order to improve the packets' robustness to noise.

In response to receiving an indication from the PCS <NUM> about the serious interference, the rate controller <NUM> commands the transceiver <NUM> to reduce its code rate, and updates the transceiver <NUM> about the reduction in the code rate. In response to receiving a further indication from the PCS <NUM> that the FA-MCC successfully canceled the effect of the serious interference, the rate controller <NUM> commands the transceiver <NUM> to increase its code rate, and updates the transceiver <NUM> about the increment in the code rate.

The indication from the PCS <NUM> to the rate controller <NUM> may by function of one or more of the following values: the percent of the lost packets, the rate of the lost packets, a function of the lost and successfully received packets, a score proportional to the detected interference, a score proportional to a slicing error provided by the slicer <NUM>, and/or a score proportional to the number of errors detected by the PCS <NUM>.

In one example, the command from the rate controller <NUM> to the transceiver <NUM> about the reduction in the code rate causes the slicer <NUM> to change its slicer function to a slicing function suitable for the reduced code rate.

Upon detecting that the effect of the serious interference has been cancelled by the FA-MCC, the rate controller <NUM> increases the code rate of transmitting the packets.

In one embodiment, at least one of the packets that could not been sent due to insufficient bandwidth while the code rate was reduced, is discarded without attempting a delayed transmission or retransmission. In one example, the traffic transmitted over the communication channel <NUM> includes video pixel data that is discarded during the time the systems uses the lower code rate.

In another embodiment, at least some of the packets that could not be sent while the code rate was reduced, are stored, optionally in buffer <NUM> at the transceiver <NUM>, and transmitted after the code rate is restored to a level that permits transmission of the extra data. In one example, the traffic transmitted over the communication channel <NUM> includes time sensitive data (e.g., video synchronization data) and time insensitive data (e.g., Ethernet data). While operating in the lower code rate, the system continues to transmit the time sensitive data, and stores the time insensitive data optionally in buffer <NUM>. After cancelling the interference and restoring the code rate to a level having higher bandwidth, the system transmits the stored time insensitive data in parallel to transmission of ongoing data.

In one example, the command from the rate controller <NUM> to the transceiver <NUM> about increasing the code rate causes the slicer <NUM> to change its slicer function to one suitable for the higher code rate.

The convergence of the FA-MCC after serious interference is usually not optimal because an optimal convergence is usually not fast enough.

In one example, the serious interference causes packet loss to exceed <NUM>% at the transceiver <NUM>, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the transceiver <NUM> to less than <NUM>%.

In another example, the serious interference causes packet loss to exceed <NUM>% at the transceiver <NUM>, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the transceiver <NUM> to less than <NUM>%.

In still another example, the serious interference causes packet loss to exceed <NUM>% at the transceiver <NUM>, and the FA-MCC is designed to converge within less than <NUM> microseconds to a level that reduces the packet loss at the transceiver <NUM> to less than <NUM>%.

The digital canceller <NUM> may be implemented in various ways. <FIG> illustrates one example in which the digital canceller <NUM> includes at least an equalizer <NUM> and a DBF <NUM>. In one example, the equalizer <NUM> and/or the DBF <NUM> may have different functions for the different data rates.

Using different function for different data rates is described, for example, in <CIT>, titled "Methods for slicing dynamically modulated symbols", which is incorporated herein by reference in its entirety. For example, the slicing results are fed to the PCS <NUM>, which parses the data packets and extracts information such as a packet header, a packet payload, a packet tail, and packet modulation information. The PCS <NUM> determines the modulation used by the transceiver <NUM>, and indicates the slicer <NUM> of which slicing function to use. The slicer <NUM> may then provide the slicing results from the indicated slicer to the DBF <NUM>. Optionally, the slicer <NUM> may additionally provide slicing errors associated with the slicing results. Following that, the DBF <NUM> generates the appropriate output and adds it to the incoming signal from the equalizer <NUM>.

In one embodiment, the transceiver <NUM> includes an optional retransmission module <NUM> that receives the parsed packets from the PCS <NUM>, and based on the received parsed packets it may request retransmission of the packets with errors. In one embodiment, one of the relationships between the FA-MCC and the retransmission module <NUM> is that the buffer <NUM> used by the retransmission module <NUM> is large enough to store the arriving packets until the FA-MCC cancels the effect of the serious interference. The combination of the fast converging FA-MCC and the retransmission module <NUM> enables both transceivers <NUM> and <NUM> to use small retransmission buffers also when operating over a communication channel that is not completely known and suffers from serious common-mode-to-differential-mode interference.

As a result of reducing the code rate, some of the packets may not be transmitted even once because the effective communication bandwidth is reduced. These packets may be stored in the retransmission buffer <NUM> at the transceiver <NUM>, which has to be large enough to store the packets that cannot be transmitted as long as the system operates at the lower code rate (typically until the effect of the serious common-mode-to-differential-mode interference is cancelled to a sufficient level).

The following are additional optional embodiments that may be combined with the above described embodiments. The following embodiments are independent of the above described embodiments and are not intended to limit the above described embodiments.

In one embodiment, a transceiver configured to recover fast to a serious interference, comprising:.

Optionally, the analyzing of the received signal comprises at least one of the following: extracting a packet from the received signal and identifying a CRC errors in the packet, identifying a slicing error of the received signal that is above a predetermined threshold, identifying that the received signal is not an idle sequence on idle time, and receiving an indication of a serious interference from a common mode detector that analyzed the received signal.

Detecting the serious interference based on the slicer error can lead to a very fast detection of the serious interference, even after just a few symbols, and especially when using a low modulation where the symbols are expected to be close to the decision levels of the slicer.

Optionally, the detection module is configured to identify the serious interference within less than <NUM> microsecond after the serious interference reaches a predetermined threshold.

In one example, the detection module is configured to identify the serious interference within less than <NUM> microseconds after the serious interference reaches a predetermined threshold.

Optionally, the transceiver receives the signal from a wired channel, it is assumed that the channel parameters of the wired channel do not change.

In one embodiment, communication link comprising first and second transceivers that communicate time sensitive data over a link, comprising:.

Optionally, the FA-MCC is further configured to converge at a short time such that the retransmissions caused by the serious interference still enables the transceiver to forward packets within a packet delay variation selected from the group of less than: <NUM> millisecond, <NUM> microseconds, and <NUM> microseconds.

In one embodiment, transceiver configured to forward time sensitive data at a predetermined average rate, comprising:.

In one example, the FA-MCC increases its ASS by at least <NUM>% in order to cancel the effect of the serious interference fast. In another example, the FA-MCC increases its ASS by at least <NUM>% in order to cancel the effect of the serious interference fast.

Optionally, the FA-MCC is further configured to converge at a short time such that the retransmissions caused by the serious interference still enables the transceiver to forward packets within a predetermined packet delay variation.

Optionally, the predetermined packet delay variation is shorter than <NUM> microseconds.

Optionally, the second packet loss rate, which is caused by the serious interference before it is cancelled by the mode conversion canceller, is at least <NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM> times the first packet loss rate.

Optionally, the predetermined average rate is calculated over a window shorter than <NUM> milli-second.

Optionally, the retransmission module comprises a limited-size buffer having capacity sufficient to store all the packets that are transmitted when transmitting at the highest transmission rate for a period lasting no more than <NUM>,<NUM> symbols.

Optionally, the transceiver and the second transceiver are implemented on integrated circuits having limited resources; and the second transceiver comprises a limited-size buffer having capacity sufficient to store all the packets that are transmitted when transmitting at the highest transmission rate for a period lasting no more than <NUM>,<NUM> symbols.

Optionally, the FA-MCC is not configured to converge optimally, and does not reach an optimal solution even after <NUM> second.

Optionally, the FA-MCC reduces its ASS, by at least <NUM>%, within less than <NUM> microseconds after it cancels the effect of the serious interference.

In one example, the FA-MCC reduces its ASS, by at least <NUM>%, within less than <NUM> microseconds after it cancels the effect of the serious interference.

Optionally, the FA-MCC reduces its ASS, by at least <NUM>%, within less than <NUM> second after it cancels the effect of the serious interference.

In one example, the FA-MCC reduces its ASS, by at least <NUM>%, within less than <NUM> second after it cancels the effect of the serious interference.

Optionally, the FA-MCC reduces its ASS, by at least <NUM>%, within <NUM> second from the time the retransmission module finishes retransmitting the packets with errors that were lost during the time it took the FA-MCC to cancel the effect of the serious interference.

In one embodiment, a communication system, having a maximum throughput above <NUM> Gbit/s, implemented on an integrated circuit (IC) having limited resources, comprising:.

Optionally, the FA-MCC is configured to cancel the effect of the serious interference within less than <NUM> microseconds. wherein the LRRM is configured to store and retransmit an amount of erred packets accumulated during less than <NUM> microseconds at the maximum throughput.

Optionally, the digital canceller is configured to feed a slicer that is configured to feed a Physical Coding Sublayer (PCS) with quantization results; the PCS is configured to extract packet data from the quantization results; and the retransmission module is further configured to receive the packet data, and to request retransmission of packets with errors based on the packet data.

Optionally, the retransmission module is implemented on the IC with limited resources that cannot support retransmission of more than <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference.

Optionally, the communication system achieves one or more of the following requirements: a maximum allowed jitter, a maximum amount of dropped packets, and requirements related to time sensitive data transmitted over the communication channel.

Optionally, the retransmission module further comprises a buffer with a capacity that is sufficient to store the received packets until all packets are received successfully.

Optionally, the capacity of the buffer is limited to store all the packets that are received during up to <NUM> microseconds while the packet loss rate is above <NUM>%.

Optionally, the digital canceller comprises an equalizer and a Decision Based Filter (DBF).

Optionally, the equalizer is a Feed Forward Equalizer (FFE).

Optionally, the DBF is a filter fed by output of the slicer.

Optionally, the FA-MCC is further configured to reduce the adaptation step size, by at least <NUM>%, within <NUM> second from the time the retransmission module finishes retransmitting packets with errors that were lost during the time it took the FA-MCC to cancel the effect of the serious interference.

Optionally, the packet data comprises information related to a packet header, a packet payload, a packet tail, and an error detection code.

In one embodiment, a transceiver combining dynamic coding and fast recovery, comprising:.

Optionally, the rate controller is configured to command the second transceiver to reduce the code rate of the packets transmitted over the differential communication channel by <NUM>% to <NUM>%.

Optionally, the FA-MCC is further configured to utilize large adaptation step size that enables it to cancel, within less than <NUM> microseconds, the effect of the serious interference and to return the transceiver's packet loss rate to the first packet loss rate.

Optionally, the rate controller is further configured to command the second transceiver to further increase the code rate until the second transceiver returns to the code rate used before the serious interference was detected.

Optionally, the transceiver further comprises a retransmission module configured to request retransmission of packets with errors, based on the packets extracted by the PCS.

Optionally, the retransmission module is limited to support retransmission of up to <NUM>% of the packets received during the time it takes the FA-MCC to cancel the effect of the serious interference.

Optionally, the transceiver and the second transceiver utilize Dynamic Modulation Coding in order to reduce the code rate.

Optionally, the packets are modulated using Pulse-Amplitude Modulation (PAM), and the rate controller commands the second transceiver to switch from using PAM16 to PAM4 until the FA-MCC cancels the effect of the serious interference.

Optionally, the code rate is reduced by adding Error Correction Code to the packets.

Optionally, the indication that the serious interference has occurred is based on one or more of the following values received from the PCS: a percent of lost packets, a rate of lost packets, a function of lost and successfully received packets, a score proportional to the detected interference, a score proportional to slicing error provided by the slicer, and a score proportional to number of errors detected by the PCS.

Optionally, the update of the slicer by the rate controller comprises an indication to the slicer to change its slicer function to a slicing function suitable for the reduced code rate.

Optionally, at least one of the packets that could not be sent due to insufficient bandwidth while the code rate was reduced, is discarded without attempting a delayed transmission or retransmission.

Optionally, the packets carry video data, and the at least one discarded packet comprises video pixel data and does not include video controls.

Optionally, at least some of the packets that could not be sent while the rate was reduced, are stored in a buffer at the second transceiver, and transmitted after the rate is restored to a level that permits transmission of the extra data.

Optionally, the traffic transmitted over the differential communication channel comprises time sensitive data and time insensitive data, and while operating in the lower code rate, the second transceiver is configured to transmit the time sensitive data, and stores the time insensitive data in a buffer.

Optionally,, after cancelling the effect of the serious interference and restoring the code rate to a level having higher bandwidth, the second transceiver is further configured to transmit the time sensitive data stored in the buffer.

Optionally, the FA-MCC is further configured to reduce the adaptation step size shortly after the increase in the code rate.

Optionally, the FA-MCC is further configured to reduce the adaptation step size, by at least <NUM>%, within <NUM> second from the time of increasing the code rate.

In this description, references to "one embodiment" mean that the feature being referred to may be included in at least one embodiment of the invention. Moreover, separate references to "one embodiment" or "some embodiments" in this description do not necessarily refer to the same embodiment. Additionally, references to "one embodiment" and "another embodiment" may not necessarily refer to different embodiments, but may be terms used, at times, to illustrate different aspects of an embodiment.

The embodiments of the invention may include any variety of combinations and/or integrations of the features of the embodiments described herein. Although some embodiments may depict serial operations, the embodiments may perform certain operations in parallel and/or in different orders from those depicted. Moreover, the use of repeated reference numerals and/or letters in the text and/or drawings is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. The embodiments are not limited in their applications to the details of the order or sequence of steps of operation of methods, or to details of implementation of devices, set in the description, drawings, or examples. Moreover, individual blocks illustrated in the figures may be functional in nature and therefore may not necessarily correspond to discrete hardware elements.

Claim 1:
A transceiver (<NUM>, <NUM>) configured to recover within less than <NUM> millisecond from quality degradation in its operating point, comprising:
a receiver analog front end, Rx AFE, (<NUM>), an adaptive module comprising at least one of an adaptive digital equalizer and an adaptive digital canceller, ADEC, (<NUM>), a common mode sensor AFE, CMS-AFE, (<NUM>), a fast-adaptive mode-conversion canceller, FA-MCC, (<NUM>), a slicer (<NUM>), and a retransmission module (<NUM>);
wherein the Rx AFE (<NUM>) is configured to receive a signal of more than <NUM> Mbps from a second transceiver over a differential wired communication link, and to feed the ADEC (<NUM>) that is configured to generate an equalized signal;
the CMS-AFE (<NUM>) is configured to sense the common mode signal of the differential wired communication link and to feed the FA-MCC (<NUM>) that is configured to generate a compensation signal; wherein the compensation signal is indicative of differential interference caused by mode-conversion of a common mode signal;
the slicer (<NUM>) is configured to utilize the equalized signal and the compensation signal to generate slicing decisions and slicing errors; wherein the slicing errors are used to adapt the ADEC (<NUM>);
shortly after identifying quality degradation in the transceiver's operating point, the transceiver is configured to indicate the second transceiver to reduce the rate of the transmitted data in order to improve detection rate at the transceiver;
within less than <NUM> millisecond from identifying the quality degradation, the transceiver is configured to utilize the improved detection rate to improve the accuracy of the slicing errors, which enables fast adaptation of the ADEC (<NUM>), that improves the quality in the transceiver's operating point to a level that enables the transceiver to indicate the second transceiver to increase the rate; and
the retransmission module is configured to utilize retransmission to recover packets that were lost from time of the quality degradation until time of increase of the rate.