# US 8,699,551 B2 · System for FEXT cancellation of multi-channel transceivers with precoding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,699,551 B2 - Document ID: US8699551B2 - Status: Granted - Kind: B2 - Application number: 12/806,556 - Filed: 2010-08-16 - Published: 2011-10-27 - Granted: 2014-04-15 - 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/US8699551B2 ## CPC - H04L 25/03343: {Arrangements at the transmitter end} - H04L 25/03057: {with a recursive structure (H04L25/03031 takes precedence)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present invention relates to data processing techniques in multi-channel data transmission systems. In this invention, a novel approach is proposed to deal with FEXT interferences in the application of high/ultra-high speed Ethernet systems. Compared with the traditional FEXT cancellation approaches, the proposed FEXT canceller can deal with the non-causal part of FEXT, and thus can achieve better cancellation performance. Instead of using the conventional DFE, structure, TH precoding technique is incorporated into the proposed design to alleviate the error propagation problem. The resulting FEXT cancellers do not contain feedback loops which makes the high speed VLSI implementation easy. A modified design is also developed by using a finite signal as the input to the FEXT canceller such that the hardware complexity of the proposed FEXT canceller can be reduced. ## Claims ### Claim 1 A far-end cross-talk canceller for a precoded multiple-input multiple-output communications system comprising a plurality of receivers, each receiver comprising: a first received signal that is filtered by a first feed-forward equalizer (FFE); a first decision device, comprising a first modulo device and a first slicer, to process the output of the first FFE to compute a first tentative decision by adding the output of the first FFE to a first error signal obtained by computing the difference between the input and output of the first slicer of the first decision device; a first far-end cross-talk (FEXT) canceller filter to filter a second tentative decision from an adjacent receiver; a first summer to subtract the first FEXT canceller filter output from a delayed version of the first FFE output to compute a first FEXT-free signal; and a second decision device, comprising a second modulo device and a second slicer, to process the first FEXT-free signal to compute a first output symbol. ### Claim 2 (depends on 1) The far-end cross-talk canceller in claim 1 where the first tentative decision is input to a second far-end cross-talk (FEXT) canceller filter of an adjacent receiver. ### Claim 3 (depends on 1) The far-end cross-talk canceller in claim 1 where the precoder is a Tomlinson-Harashima precoder. ### Claim 4 (depends on 1) The far-end cross-talk canceller in claim 1 where the first slicer is coupled to the output of a first modulo device whose input is coupled to the first FFE output. ### Claim 5 (depends on 1) The far-end cross-talk canceller in claim 1 where the first FFE output is delayed by one sample or a plurality of samples. ### Claim 6 (depends on 1) The far-end cross-talk canceller in claim 1 where the first tentative decision is filtered by a precoder filter first and the filtered output is then input to the second far-end cross-talk canceller of an adjacent receiver. ### Claim 7 (depends on 6) The far-end cross-talk canceller in claim 6 where the precoder filter is an infinite impulse response filter. ### Claim 8 (depends on 1) The far-end cross-talk canceller in claim 1 where the first FEXT canceller filter is a finite impulse response filter. ### Claim 9 (depends on 1) The far-end cross-talk canceller in claim 1 where the second FEXT canceller filter of an adjacent receiver is adapted by a second error signal obtained by computing the difference between the input and output of the second slicer of the second decision device. ### Claim 10 (depends on 1) The far-end cross-talk canceller in claim 1 used in an Ethernet transceiver over copper. ### Claim 11 (depends on 1) The far-end cross-talk canceller in claim 1 used in a 10GBase-T transceiver. ### Claim 12 (depends on 1) The far-end cross-talk canceller in claim 1 used in a wired transceiver. ### Claim 13 (depends on 1) The far-end cross-talk canceller in claim 1 implemented by a circuit. ### Claim 14 (depends on 1) The far-end cross-talk canceller in claim 1 used in a communications transceiver, where the first received signal corresponds to a signal after echo from a corresponding near-end transmitter has been cancelled from its the input signal. ### Claim 15 (depends on 1) The far-end cross-talk canceller in claim 1 used in a communications transceiver, where the first received signal corresponds to a signal after near-end cross-talk from an adjacent transmitter has been cancelled from its input signal. ### Claim 16 An integrated circuit to implement a far-end cross-talk canceller for a precoded multiple-input multiple-output communications system, comprising a plurality of receivers, each receiver comprising: A first feed-forward equalizer (FFE) to filter a first received signal; a first decision device, comprising a first modulo device and a first slicer, to process the output of the first FFE to compute a first tentative decision by adding the output of the first FFE to a first error signal obtained by computing the difference between the input and output of the first slicer of the first decision device; a first far-end cross-talk (FEXT) canceller filter to filter a second tentative decision from an adjacent receiver; a first summer to subtract the first FEXT canceller filter output from a delayed version of the first FFE output to compute a first FEXT-free signal; and a second decision device, comprising a second modulo device and a second slicer, to process the first FEXT-free signal to compute a first output symbol. ### Claim 17 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the first tentative decision is input to a second FEXT canceller filter of an adjacent receiver. ### Claim 18 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the precoder is a Tomlinson-Harashima precoder. ### Claim 19 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the first slicer is coupled to the output of a first modulo device whose input is coupled to the first FFE output. ### Claim 20 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the first FFE output is delayed by one sample or a plurality of samples. ### Claim 21 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the first tentative decision is filtered by a precoder filter first and the filtered output is input to the second FEXT canceller filter of an adjacent receiver. ### Claim 22 (depends on 21) The far-end cross-talk canceller integrated circuit in claim 21 where the precoder filter is an infinite impulse response filter. ### Claim 23 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the first FEXT canceller filter is a finite impulse response filter. ### Claim 24 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 where the second FEXT canceller filter of an adjacent receiver is adapted by a second error signal obtained by computing the difference between the input and output of the second slicer of the second decision device. ### Claim 25 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 used in an Ethernet transceiver over copper. ### Claim 26 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 used in a 10GBase-T ethernet transceiver. ### Claim 27 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 used in a wired transceiver. ### Claim 28 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 used in a communications transceiver, where the first received signal corresponds to a signal after echo from the corresponding near-end transmitter has been cancelled from its input signal. ### Claim 29 (depends on 16) The far-end cross-talk canceller integrated circuit in claim 16 used in a communications transceiver, where the first received signal corresponds to a signal after near-end cross-talk from an adjacent transmitter has been cancelled from its input signal.