Echo cancellation in a multiport data transceiver

Patent metadata

Field	Value
Publication number	US-10826559-B2
Application number	US-201815980865-A
Country	US
Kind code	B2
Filing date	May 16, 2018
Priority date	May 16, 2018
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A multiport FDX data transceiver having (i) digital transmit and receive chains shared by the multiple ports thereof and (ii) a multi-stage echo-cancellation circuit capable of canceling the echo of the transmitted signal that is coupled back into the receive chain through the analog front end of the transceiver. In an example embodiment, the echo-cancellation circuit comprises two stages. The first stage operates to remove a dominant echo signal corresponding to the output signal that is being broadcast on the multiple ports of the transceiver. The second stage operates to remove a residual echo signal typically caused by differences in the pertinent characteristics of the circuits associated with the different ports of the transceiver. In some embodiments, the multi-stage echo-cancellation circuit can be used for training a single-stage echo-cancellation circuit that may be unable to sufficiently quickly converge on an optimal set of filter coefficients on its own.

First claim

What is claimed is:

1. An apparatus comprising:
a data transceiver that comprises an analog front end having a plurality of front-end modules connected to a plurality of ports, a digital transmit chain, and a digital receive chain, the digital transmit chain being configured to drive the analog front end to cause an output signal to be transmitted on the plurality of ports with portions of the output signal being coupled through the front-end modules into the digital receive chain as an echo signal;
wherein the data transceiver further comprises a first echo-cancellation circuit having at least a first stage and a second stage connected in series, the first echo-cancellation circuit being configurable to cancel the echo signal in response to a plurality of monitor signals received from the front-end modules;
wherein the first stage comprises a plurality of first adaptive filters, each of the first adaptive filters having a respective feed-through path and a respective first tap, each of the respective first taps being connected to receive one of the plurality of monitor signals, one of the respective feed-through paths being connected to receive a data signal generated in response to one or more input signals received on the plurality of ports, and other ones of the respective feed-through paths being connected to receive other ones of the plurality of monitor signals; and
wherein the second stage is connected to receive signals outputted by the respective feed-through paths of the plurality of first adaptive filters.

2. The apparatus of claim 1 ,
wherein the second stage comprises a second adaptive filter having a feed-through path and a plurality of taps;
wherein the feed-through path of the second adaptive filter is connected to receive a signal outputted by said one of the respective feed-through paths of the plurality of first adaptive filters; and
the plurality of taps of the second adaptive filter are connected to receive signals outputted by said other ones of the respective feed-through paths of the plurality of first adaptive filters.

3. The apparatus of claim 1 ,
wherein the second stage comprises a plurality of second adaptive filters, each having a respective feed-through path and a respective plurality of taps;
wherein the respective feed-through path of one of the plurality of second adaptive filters is connected to receive a signal outputted by said one of the respective feed-through paths of the plurality of first adaptive filters;
wherein the respective feed-through paths of other ones of the plurality of second adaptive filters are connected to receive signals outputted by a first subset of said other ones of the respective feed-through paths of the plurality of first adaptive filters; and
wherein each of the respective plurality of taps of the plurality of second adaptive filters are connected to receive signals outputted by a second subset of said other ones of the respective feed-through paths of the plurality of first adaptive filters.

4. The apparatus of claim 3 ,
wherein the second subset has a single feed-through path; and
wherein the first and second subsets have no feed-through paths in common.

5. The apparatus of claim 1 ,
wherein each of the first adaptive filters has a respective second tap; and
wherein each of the respective second taps is connected to receive another one of the plurality of monitor signals.

6. The apparatus of claim 1 , wherein the first echo-cancellation circuit has a third stage connected in series with the first and second stages thereof.

7. The apparatus of claim 1 ,
wherein the data transceiver further comprises a second echo-cancellation circuit and one or more switches;
wherein the second echo-cancellation circuit is configurable to cancel the echo signal in response to the plurality of monitor signals received from the front-end modules;
wherein, in a first configuration of the one or more switches, the first echo-cancellation circuit is connected to receive the plurality of monitor signals while the second echo-cancellation circuit is disconnected therefrom; and
wherein, in a second configuration of the one or more switches, the second echo-cancellation circuit is connected to receive the plurality of monitor signals while the first echo-cancellation circuit is disconnected therefrom.

8. The apparatus of claim 7 , wherein the data transceiver further comprises a filter-coefficient mapper configured to determine filter coefficients for the second echo-cancellation circuit in response to receiving filter coefficients used in the first and second stages of the first echo-cancellation circuit.

9. The apparatus of claim 8 , wherein the second echo-cancellation circuit is configured to use fewer filter coefficients than a total number of the filter coefficients used in the first and second stages of the first echo-cancellation circuit.

10. The apparatus of claim 8 ,
wherein the second echo-cancellation circuit comprises a second adaptive filter that comprises a filter controller and a plurality of taps; and
wherein the filter controller is configured to:
store therein the filter coefficients determined by the filter-coefficient mapper; and
cause the second adaptive filter to apply the filter coefficients stored in the filter controller to signals applied to the plurality of taps thereof in the second configuration of the one or more switches.

11. The apparatus of claim 1 ,
wherein the first echo-cancellation circuit is configured to update filter coefficients used in a first subset of the plurality of first adaptive filters at a first rate; and
wherein the first echo-cancellation circuit is configured to update one or more filter coefficients used in a second subset of the plurality of first adaptive filters at a second rate that is different from the first rate.

12. The apparatus of claim 11 ,
wherein the second stage comprises a second adaptive filter; and
wherein the first echo-cancellation circuit is configured to update filter coefficients used in the second adaptive filter at the first rate.

13. The apparatus of claim 12 , wherein the second rate is higher than the first rate.

14. The apparatus of claim 1 ,
wherein the data transceiver further comprises a signal combiner configured to combine two or more of the input signals received on the plurality of ports to generate a corresponding combined signal; and
wherein the data transceiver is configured to generate the data signal in response to the combined signal.

15. The apparatus of claim 1 , wherein the data transceiver is configured to broadcast the output signal on the plurality of ports.

16. The apparatus of claim 1 , wherein each of the front-end modules comprises a respective power amplifier connected between the digital transmit chain and a respective one of the plurality of ports.

17. The apparatus of claim 16 , wherein each of the front-end modules comprises a respective electrical coupler connected to an output of the respective power amplifier and configured to generate a respective one of the plurality of monitor signals.

18. The apparatus of claim 1 , further comprising a cable modem termination system that includes the data transceiver.

19. The apparatus of claim 1 , wherein each of the plurality of ports is configured to be connected to a respective coaxial cable.

20. The apparatus of claim 1 ,
wherein the output signal transmitted on the plurality of ports is an electrical, optical, or acoustic output signal; and
wherein each of the one or more inpu

Assignees

• Nokia Solutions & Networks Oy

Inventors

• Nuzman Carl

Classifications

• H04B1/12

  Neutralising, balancing, or compensation arrangements · CPC title

• H04B3/237 Primary

  using two adaptive filters, e.g. for near end and for end echo cancelling · CPC title

• H04B1/525 Primary

  with means for reducing leakage of transmitter signal into the receiver · CPC title

• H04B1/40

  Circuits · CPC title

• H04L5/14

  Two-way operation using the same type of signal, i.e. duplex · CPC title