Full duplex wireless transmission with self-interference cancellation

• US 9,713,010 B2
• Filed: 05/13/2013
• Issued: 07/18/2017
• Est. Priority Date: 05/13/2012
• Status: Active Grant

• Current Assignee: Amir Keyvan Khandani
• Original Assignee: Amir Keyvan Khandani
• Inventors: Khandani, Amir Keyvan
• Primary Examiner(s): Pham, Chi H
• Assistant Examiner(s): Ajid, Abdeltif
• Application Number:
  US13/893,288
• Publication Number:
  US 20130301487A1
• Time in Patent Office: 1,527 Days
• Field of Search: 370277, 370278
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 1/18 Automatic repetition systems, e.g. Van Duuren systems
• CPC Class Codes: H04L 1/1825 Adaptation of specific ARQ protocol parameters according to transmission conditions
• CPC Class Codes: H04L 1/1896 ARQ related signaling
• CPC Class Codes: H04L 2001/0097 Relays
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04W 12/04 Key management, e.g. using generic bootstrapping architecture [GBA]
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

Two-way (full-duplex) wireless communications. Various embodiments measure interference channels and provide for interference cancellation in both analog and digital domains to mitigate self-interference. The system supports multiple clients wherein new clients can join the network asynchronously, and also supports Multiple-Input Multiple-Output (MIMO) antennas.

Claims

1. A method comprising:

in a full-duplex transceiver, receiving a self-interference signal over a self-interference channel that includes a propagation path from a primary transmit antenna of the full-duplex transceiver to a receive antenna of the full-duplex transceiver, wherein the primary transmit antenna is pair-wise symmetrical to the receive antenna to reduce coupling such that (i) the primary transmit antenna and the receive antenna are self-symmetrical, (ii) the primary transmit antenna and the receive antenna have different planes of symmetry, and (iii) the primary transmit antenna has an antenna configuration which is invariant under reflection in the plane of symmetry of the receive antenna and the receive antenna has an antenna configuration which is invariant under reflection in the plane of symmetry of the primary antenna;

in the full duplex transceiver, generating an interference-reduced signal by combining an analog self-interference cancellation signal to an incoming signal that includes a desired signal and the self-interference signal, wherein the analog self-interference cancellation signal destructively adds to the self-interference signal to create a residual self-interference signal; and

processing the interference-reduced signal to further reduce the residual self-interference signal using a baseband residual self-interference channel estimate.

2. The method of claim 1 wherein the analog self-interference signal is a radio frequency signal.

3. The method of claim 1 wherein the analog self-interference signal is an intermediate frequency or a baseband signal.

4. The method of claim 1 wherein the analog self-interference signal is combined in an inphase signal path and a quadrature signal path.

5. The method of claim 1 wherein the self-interference signal incorporates a self-interference channel response and an estimate of an auxiliary channel response, and the self-interference cancellation signal incorporates an auxiliary channel response and an estimate of the self-interference channel response.

6. The method of claim 1 wherein the baseband residual self-interference channel estimate is determined from transmitting a plurality of test tones that incorporate an estimate of an auxiliary channel response and an estimate of an interference channel response and measuring a corresponding residual error signal.

7. The method of claim 6 wherein the test tones also incorporate a power normalization factor.

8. The method of claim 1 wherein the self-interference cancellation signal is combined with the incoming signal via a coupler.

9. The method of claim 1 wherein the self-interference cancellation signal is transmitted from an auxiliary antenna of the full-duplex transceiver.

10. The method of claim 9 wherein the auxiliary antenna of the full-duplex transceiver is configured to have a high-coupling to a receive antenna of the full-duplex transceiver.

11. A method comprising:

determining an estimate of a self-interference channel response from a primary transmitter of a transceiver to a receiver of the transceiver and determining an estimate of an auxiliary channel response from an auxiliary transmitter of the transceiver to the receiver;

determining a residual self-interference baseband channel response at a baseband processor of the receiver;

preprocessing a primary transmit signal and an auxiliary transmit signal with the estimated auxiliary channel response and a negative of the estimated self-interference channel response, respectively;

transmitting the preprocessed primary transmit signal and the preprocessed auxiliary transmit signal in a transmit frequency range;

receiving a desired signal within a receive frequency range substantially overlapping the transmit frequency range, and receiving a residual self-interference signal;

reducing the residual self-interference signal using the residual self-interference baseband channel response; and

,

further processing the desired signal.

12. The method of claim 11 wherein determining an estimate of a self-interference channel response comprises transmitting a plurality of tones from the primary transmitter and receiving them at the receiver and measuring the effect of the self-interference channel on the tones.

13. The method of claim 12 wherein the tones are an orthogonal frequency division multiplexed (OFDM) signal.

14. The method of claim 11 wherein determining an estimate of an auxiliary channel response comprises transmitting a plurality of tones from the auxiliary transmitter of the transceiver and receiving them at the receiver and measuring the effect of the auxiliary channel on the tones.

15. The method of claim 14 wherein the tones are an OFDM signal.

18. The method of claim 11, wherein:

determining an estimate of a self-interference channel response includes determining a shift in magnitude and phase introduced by the self-interference channel;

determining an estimate of an auxiliary channel response includes determining a shift in magnitude and phase introduced by the auxiliary channel; and

preprocessing includes shifting a magnitude and phase of the primary transmit signal by the determined shift in magnitude and phase introduced by the auxiliary channel, and shifting a magnitude and phase of the auxiliary transmit signal by a negative of the determined shift in magnitude and phase introduced by the self-interference channel.

16. An apparatus comprising:

a weight calculation unit configured to measure a self-interference channel and an auxiliary channel to obtain an estimate of the self-interference channel and an estimate of the auxiliary channel;

a full-duplex transceiver having a primary transmitter, an auxiliary transmitter, and a receiver, wherein the primary transmitter and auxiliary transmitter are configured to preprocess a training sequence to generate two transmit signals, such that the two transmit signals respectively traverse the self-interference channel and the auxiliary channel and combine to form an analog residual interference signal at the receiver of the full-duplex transceiver;

an analog to digital converter and a receiver baseband processor at the receiver being configured to measure a baseband residual self-interference channel response; and

,

the transceiver being further configured to cancel self-interference signals using the auxiliary channel and to cancel residual self-interference signals using the measured baseband residual self-interference channel response.

17. The apparatus of claim 16, wherein:

the primary transmitter includes a primary transmit antenna;

the receiver includes a receive antenna; and

the primary transmit antenna is pair-wise symmetrical to the receive antenna to reduce coupling such that (i) the primary transmit antenna and the receive antenna are self-symmetrical, (ii) the primary transmit antenna and the receive antenna have different planes of symmetry, and (iii) the primary transmit antenna has an antenna configuration which is invariant under reflection in the plane of symmetry of the receive antenna and the receive antenna has an antenna configuration which is invariant under reflection in the plane of symmetry of the primary antenna.