System and method for full duplex cancellation

• US 8,842,584 B2
• Filed: 07/13/2012
• Issued: 09/23/2014
• Est. Priority Date: 07/13/2012
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Jana, Rittwik, Aggarwal, Vaneet, Rice, Christopher W., Shankaranarayanan, Nemmara K., Duarte, Melissa, Sabharwal, Ashutosh
• Primary Examiner(s): Elliott, IV, Benjamin H
• Application Number:
  US13/549,189
• Publication Number:
  US 20140016515A1
• Time in Patent Office: 802 Days
• Field of Search: 370/277, 370/278, 370/282, 370/286, 370/296
• US Class Current: 370/278
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 15/00 Suppression or limitation of noise or interference by means associated with receiver H04B1/10
• CPC Class Codes: H04L 27/265 Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators H04L27/26524 takes precedence
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04L 5/1461 Suppression of signals in the return path, i.e. bidirectional control circuits

Abstract

Disclosed herein are systems, methods, and computer-readable storage media for enabling improved cancellation of self-interference in full-duplex communications, or the transmitting and receiving of communications in a single frequency band without requiring time, frequency, or code divisions. The system estimates the signal strength and phase of a self-interference signal, generates a cancellation signal based on this estimate, then uses the cancellation signal to suppress the self-interference before sampling received analog signal. After applying the cancellation signal, the system samples and digitizes the remaining analog signal. The digitized signal is then subjected to additional digital cancellation, allowing for extraction of the desired signal.

Claims

1. A method comprising:

receiving, at a receiving antenna, a self-interference signal transmitted by a transmitting antenna, the receiving antenna and the transmitting antenna comprising two unique antennas on a single device;

estimating a passive suppression of the self-interference signal, wherein the passive suppression of the self-interference signal is based on a previously estimated passive suppression stored in a database;

storing the passive suppression of the self-interference signal in the database;

generating an analog cancellation signal based on the passive suppression;

applying the analog cancellation signal to the self-interference signal, to yield a residual self-interference signal; and

applying digital cancellation to the residual self-interference signal.

2. The method of claim 1, wherein the transmitting antenna comprises a plurality of transmitting antennas.

3. The method of claim 1, wherein the receiving antenna comprises a plurality of receiving antennas.

4. The method of claim 1, wherein the applying of the analog cancellation signal to the self-interference signal occurs prior to converting the self-interference signal to a digital version.

5. The method of claim 1, wherein generating the analog cancellation signal is further based on a subcarrier interference associated with a plurality of subcarriers in the self-interference signal.

6. A system comprising:

a processor; and

a computer-readable storage medium storing instructions which, when executed by the processor, perform operations comprising;

receiving, at a receiving antenna, a self-interference signal transmitted by a transmitting antenna, the receiving antenna and the transmitting antenna comprising two unique antennas on a single device;

estimating a passive suppression of the self-interference signal, wherein the passive suppression of the self-interference signal is based on a previously estimated passive suppression stored in a database;

storing the passive suppression of the self-interference signal in the database;

generating an analog cancellation signal based on the passive suppression;

applying the analog cancellation signal to the self-interference signal, to yield a residual self-interference signal; and

applying digital cancellation to the residual self-interference signal.

7. The system of claim 6, wherein the transmitting antenna comprises a plurality of transmitting antennas.

8. The system of claim 6, wherein the receiving antenna comprises a plurality of receiving antennas.

9. The system of claim 6, wherein the applying of the analog cancellation signal to the self-interference signal occurs prior to converting the self-interference signal to a digital version.

10. The system of claim 6, wherein generating the analog cancellation signal is further based on a subcarrier interference associated with a plurality of subcarriers in the self-interference signal.

11. A computer-readable storage device having instructions stored which, when executed by a computing device, cause the computing device to perform operations comprising:

receiving, at a receiving antenna, a self-interference signal transmitted by a transmitting antenna, the receiving antenna and the transmitting antenna comprising two unique antennas on a single device;

estimating a passive suppression of the self-interference signal, wherein the passive suppression of the self-interference signal is based on a previously estimated passive suppression stored in a database;

storing the passive suppression of the self-interference signal in the database;

generating an analog cancellation signal based on the passive suppression;

applying the analog cancellation signal to the self-interference signal, to yield a residual self-interference signal; and

applying digital cancellation to the residual self-interference signal.

12. The computer-readable storage device of claim 11, wherein the transmitting antenna comprises a plurality of transmitting antennas.

13. The computer-readable storage medium device of claim 11, wherein the receiving antenna comprises a plurality of receiving antennas.

14. The computer-readable storage device of claim 11, wherein the applying of the analog cancellation signal to the self-interference signal occurs prior to converting the self-interference signal to a digital version.

15. The computer-readable storage device of claim 11, wherein generating the analog cancellation signal is further based on a subcarrier interference associated with a plurality of subcarriers in the self-interference signal.