Self-Interference Cancellation

• US 20150055568A1
• Filed: 09/27/2013
• Published: 02/26/2015
• Est. Priority Date: 08/20/2013
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Jindal, Nihar, Shi, Jun, Sundararajan, Sriram, Behzad, Arya, Forbes, Marcellus, Su, Ling
• Granted Patent: US 9,287,995 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver

Abstract

A communication device, such as a smart phone, includes transmit/receive logic to cancel an interfering signal component. The interfering signal component may originate from a communication interface on the device itself. For example, transmissions from the communication interface may interfere with received signals at other communication interfaces on the device. Transmit/receive logic on others of the communication interfaces may use known characteristics of the interfering signal component to cancel the interfering signal component.

Claims

1. A system comprising:

a first wireless interface configured to transmit a data stream;

a second wireless interface configured to receive an input signal including a signal component arising from transmission of the data stream;

a reference path configured to provide a reference signal from the first wireless interface to the second wireless interface;

a cancellation filter configured to attempt to match the reference signal to the signal component, and provide a cancellation output; and

a removal element configured to remove the cancellation output from the input signal received at the second wireless interface.

2. The system of claim 1, where the first wireless interface comprises a first protocol wireless interface;

and where the second wireless interface comprises a second protocol wireless interface different from the first protocol wireless interface.

3. The system of claim 1, where the first wireless interface is configured to transmit over a wireless channel;

and

the second wireless interface further comprises logic configured to train the cancellation filter to match an effect of the wireless channel.

4. The system of claim 3, where the second wireless interface is configured to request a training period to train the cancellation filter.

5. The system of claim 4, where the logic is configured to:

perform a minimization of an output of the signal component during the training period; and

set a parameter of the cancellation filter based on the minimization.

6. The system of claim 1, where the reference path comprises one or more wireless channels and one or more antenna elements configured to receive the reference signal and the input signal.

7. The system of claim 1, further comprising:

a signal path leading to the first wireless interface; and

where;

the reference path comprises a matching element configured to match an effect caused by the signal path.

8. The system of claim 1, further comprising:

a signal path leading to the cancellation filter; and

where;

the reference path comprises a matching element configured to match an effect caused by the signal path.

9. A method comprising:

transmitting a first signal from a first antenna;

receiving an interference component arising from the first signal on a second antenna;

receiving a reference via a reference path;

requesting a training period from an infrastructure element; and

training a cancellation filter in the reference path based on the interference component and reference signal, during the training period.

10. The method of claim 9, where the requesting comprises transmitting an impending transmission indicator.

11. The method of claim 9, where the requesting comprises transmitting a silence request to the infrastructure element.

12. The method of claim 9, further comprising, during the training period, transmitting a dummy transmission as the signal.

13. The method of claim 9, where the reference and the interference component comprise signals derived from a common data stream.

14. The method of claim 9, the first signal comprises a cellular telecommunication signal.

15. The method of claim 9, where the training comprises setting a parameter of the cancellation filter.

16. A device comprising;

a first wireless interface configured to transmit a first signal associated with a first protocol;

a second wireless interface comprising configured to;

receive a second signal associated with a second protocol from an infrastructure element, the second protocol being different from the first protocol; and

receive a self-interfering signal component arising from the first signal;

convert the second signal and self-interfering signal component to a digital stream with a digital self-interfering component;

a reference path comprising;

a digital signal source configured to provide a digital reference signal having a common origin with the first signal;

a cancellation filter to attempt configured to match the reference signal to the digital self-interfering component to produce a cancellation output; and

a removal element coincident with the second wireless interface, the removal element configured to destructively combine the cancellation output and digital self-interfering component.

17. The device of claim 16, further comprising control logic configured to determine a parameter of the cancellation filter based on a training routine.

18. The device of claim 17, where the training routine is configured to minimize an output of the removal element during a training period.

19. The device of claim 18, where the second wireless interface is configure to transmit a message configured to pause transmission from the infrastructure element.

20. The device of claim 16, where the first protocol comprises a cellular protocol and the second protocol comprises a WLAN protocol;

and

where a spectral power density of the first signal is greater than a spectral power density of the second signal.