# US 8,600,039 B2 · System for low complexity adaptive ECHO and NEXT cancellers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,600,039 B2 - Document ID: US8600039B2 - Status: Granted - Kind: B2 - Application number: 12/806,539 - Filed: 2010-08-16 - Published: 2011-02-24 - Granted: 2013-12-03 - Earliest claimed: 2009-08-24 - Assignees: Leanics Corporation - Applicants: Jie Chen; Keshab K. Parhi - Inventors: Jie Chen; Keshab K. Parhi - Web page: https://patentgrep.com/patent/US8600039B2 ## CPC - H04B 3/23: using a replica of transmitted signal in the time domain, e.g. echo cancellers - H04B: TRANSMISSION ## Abstract The present invention relates to design and implementation of low complexity adaptive echo and NEXT cancellers in multi-channel data transmission systems. In this invention, a highly efficient weight update scheme is proposed to reduce the computational cost of the weight update part in adaptive echo and NEXT cancellers. Based on the proposed scheme, the hardware complexity of the weight update part can be further reduced by applying the word-length reduction technique. The proposed scheme is general and suitable for real applications such as design of a low complexity transceiver in 10GBase-T. Different with prior work, this invention considers the complexity reduction in weight update part of the adaptive filters such that the overall complexity of these adaptive cancellers can be significantly reduced. ## Claims ### Claim 1 A communications transceiver comprising: i. N transmitters, where N is a positive integer, each containing a precoder to process an input signal and compute a compensation signal; ii. N receivers, each comprising: (a) a first filter used as an echo canceller, coupled to a sum of the input signal and the compensation signal of the precoder of the corresponding transmitter; (b) a weight update block, coupled to either the compensation signal or the input signal of the precoder of the corresponding transmitter or the sum of these two signals, to compute a set of tap weights for the corresponding echo canceller; (c) a second filter with transfer function 1/H(z), coupled to the output of the echo canceller; (d) computing the difference between the output of the second filter and the received signal to generate an error signal; (e) filtering the error signal by a third filter H(z), whose transfer function is the reciprocal of that of the second filter, and using the output of the third filter as an input to the weight update block. ### Claim 2 (depends on 1) The transceiver in claim 1, where each Echo canceller is implemented using two Echo cancellers, one canceller coupled to the input signal of the precoder, and another coupled to the compensation signal of the precoder, where each of the two cancellers uses the same tap weights computed by the weight update block. ### Claim 3 (depends on 1) The transceiver in claim 1 used as a 10GBase-T transceiver. ### Claim 4 (depends on 1) The transceiver in claim 1 used as an Ethernet transceiver. ### Claim 5 A communications transceiver comprising: i. N transmitters, where N is a positive integer greater than 1, each containing a precoder to process an input signal and compute a compensation signal; ii. N receivers, each comprising: (a) a first filter used as a NEXT canceller, to filter a sum of the input signal and the compensation signal of the precoder of a near-end transmitter; (b) a weight update block to compute a set of tap weights for the NEXT canceller, coupled to either the compensation signal or the input signal of the precoder of the corresponding near-end transmitter or to the sum of these two signals; (c) a second filter with transfer function 1/H(z), coupled to the output of the NEXT canceller; (d) computing the difference between the output of the second filter and the received signal to generate an error signal; (e) filtering the error signal by a third filter H(z), whose transfer function is the reciprocal of that of the second filter, and using the output of the third filter as an input to the corresponding weight update block. ### Claim 6 (depends on 1) The transceiver in claim 1, where each NEXT canceller is implemented using two NEXT cancellers, one canceller coupled to a near-end precoder's input signal, and another coupled to the near-end precoder's compensation signal, where each of the two NEXT cancellers uses the same tap weights computed by the weight update block. ### Claim 7 (depends on 5) The transceiver in claim 5 used as a 10GBase-T transceiver. ### Claim 8 (depends on 1) The transceiver in claim 1 used as an Ethernet transceiver. ### Claim 9 An integrated circuit implementing a communications transceiver comprising: i. N transmitters, where N is a positive integer, each containing a precoder to process an input signal and compute a compensation signal; ii. N receivers, each comprising: (a) a first filter used as an echo canceller, to filter a sum of the input signal and the compensation signal of the precoder of the corresponding transmitter; (b) a weight update block, coupled to either the compensation signal or the input signal of the precoder of the corresponding transmitter or the sum of these two signals; (c) a second filter with transfer function 1/H(z), coupled to the output of the echo canceller; (d) a subtractor to compute the difference between the output of the second filter and the received signal to generate an error signal; (e) a third filter H(z), whose transfer function is reciprocal of that of the second filter, to filter the error signal and using the output of the this filter as an input to the corresponding weight update block. ### Claim 10 (depends on 9) The transceiver in claim 9, where each echo canceller is implemented using two Echo cancellers, one canceller coupled to an input signal of the precoder, and another coupled to its compensation signal of the precoder, where the tap weights for each of these two cancellers are computed by the same weight update block. ### Claim 11 (depends on 9) The transceiver in claim 9 where the precoder is a Tomlinson-Harashima precoder. ### Claim 12 (depends on 9) The transceiver in claim 9 used as an ethernet transceiver. ### Claim 13 (depends on 9) The transceiver in claim 9 used as a 10GBase-T transceiver. ### Claim 14 An integrated circuit implementing a communications transceiver comprising: i. N transmitters, where N is a positive integer greater than 1, each containing a precoder to process an input signal and compute a compensation signal; ii. N receivers, each comprising: (a) a first filter used as a NEXT canceller, to filter a sum of the input signal and the compensation signal of the precoder of a corresponding near-end transmitter; (b) a weight update block, coupled to either the compensation signal or the input signal of the precoder of the corresponding near-end transmitter or the sum of these two signals; (c) a second filter with transfer function 1/H(z), coupled to the output of the NEXT canceller; (d) a subtractor to compute the difference between the output of the second filter and the received signal to generate an error signal; (e) a third filter H(z), whose transfer function is reciprocal of that of the second filter, to filter the error signal and using the output of the this filter as an input to the corresponding weight update block. ### Claim 15 (depends on 14) The transceiver in claim 14, where each NEXT canceller is implemented using two NEXT cancellers, one canceller coupled to a near-end precoder's input signal, and another coupled its compensation signal, where the tap weights for each of these two cancellers are computed by the same weight update block. ### Claim 16 (depends on 14) The transceiver in claim 14 where the precoder is a Tomlinson-Harashima precoder. ### Claim 17 (depends on 14) The transceiver in claim 14 used as an ethernet transceiver. ### Claim 18 (depends on 14) The transceiver in claim 14 used as a 10GBase-T transceiver. ### Claim 19 An echo canceller in a precoded communications transceiver, comprising: a transmitter, comprising a precoder, to process an input signal and compute a compensation signal; a receiver comprising: a received signal; a first filter loop comprising: a first filter, with a transfer function H(z), to filter a first error signal; a second filter coupled to the output of the first error signal to compute a set of tap weights; a third filter to filter a sum of the compensation signal and the input signal of the precoder of the transmitter using the tap weights computed by the second filter; and a fourth filter with transfer function 1/H(z), the reciprocal of that of the first filter, to filter the output of the third filter; where the first error signal is computed by taking a difference of the received signal and the output of the fourth filter. ### Claim 20 (depends on 19) The echo canceller in claim 19 where the second filter is further coupled to either the compensation signal or the input signal of the precoder of the transmitter. ### Claim 21 (depends on 19) The echo canceller in claim 19 where the second filter is further coupled to a sum of the input signal and the compensation signal of the precoder of the transmitter. ### Claim 22 (depends on 19) The echo canceller in claim 19 where the third filter is replaced by a fifth filter to filter the compensation signal of the precoder, and a sixth filter to filter the input signal of the precoder. ### Claim 23 (depends on 22) The echo canceller in claim 22 where the tap weights computed by the weight update block are used by both fifth and sixth filters. ### Claim 24 (depends on 19) The echo canceller in claim 19 used in an Ethernet transceiver. ### Claim 25 (depends on 19) The echo canceller in claim 19 used in an Ethernet transceiver over copper. ### Claim 26 (depends on 19) The echo canceller in claim 19 used in a multi-input multi-output transceiver. ### Claim 27 (depends on 19) The echo canceller in claim 19 used in a 10GBase-T transceiver. ### Claim 28 (depends on 19) The echo canceller in claim 19 used in a transceiver over multi-pair cable. ### Claim 29 (depends on 19) The echo canceller in claim 19 implemented by an integrated circuit. ### Claim 30 A near-end cross-talk canceller in a multiple-input multiple-output precoded communication transceiver, comprising: a first transmitter, comprising a first precoder, to process a first input signal and compute a first compensation signal; a second transmitter, comprising a second precoder, to process a second input signal and compute a second compensation signal; a first receiver comprising a first received signal; and a second receiver comprising a second received signal; the first receiver further comprising: a first loop comprising: a first filter, with a transfer function H(z), to filter a first error signal; a second filter coupled to the output of the first error signal to compute a set of tap weights; a third filter to filter a sum of the compensation signal and the input signal of the second precoder of the second transmitter using the tap weights computed by the second filter; and a fourth filter with a transfer function 1/H(z), the reciprocal of that of the first filter, to filter the output of the third filter; where the first error is computed by taking the difference of the first received signal and the output of the fourth filter. ### Claim 31 (depends on 30) The near-end canceller in claim 30 where the second filter is further coupled to the compensation signal or the input signal of the second precoder of the second transmitter. ### Claim 32 (depends on 30) The near-end canceller in claim 30 where the second filter is further coupled to a sum of the input signal and the compensation signal of the second precoder of the second transmitter. ### Claim 33 (depends on 30) The near-end canceller in claim 30 where the third filter is replaced by a fifth filter to filter the second compensation signal of the second precoder, and a sixth filter to filter the second input signal of the second precoder. ### Claim 34 (depends on 33) The near-end canceller in claim 33 where the tap weights computed by the weight update block are used by both fifth and sixth filters. ### Claim 35 (depends on 30) The near-end canceller in claim 30 used in an Ethernet transceiver. ### Claim 36 (depends on 30) The near-end canceller in claim 30 used in a 10GBase-T transceiver. ### Claim 37 (depends on 30) The near-end canceller in claim 30 used in a transceiver over multi-pair cable. ### Claim 38 (depends on 30) The near-end canceller in claim 30 used in an Ethernet transceiver over copper. ### Claim 39 (depends on 30) The near-end canceller in claim 30 implemented by an integrated circuit.