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Single channel full duplex wireless communications

  • US 9,887,728 B2
  • Filed: 11/09/2011
  • Issued: 02/06/2018
  • Est. Priority Date: 02/03/2011
  • Status: Active Grant
First Claim
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1. A method for self-interference cancellation comprising:

  • sampling a digital transmit signal of a communication system;

    converting the digital transmit signal into a radio frequency (RF) transmit signal;

    wherein the RF transmit signal is an analog signal having a first center frequency;

    wherein the first center frequency is a radio frequency;

    sampling the RF transmit signal;

    transmitting, at a set of transmit antennas of the communication system, the RF transmit signal;

    receiving, at a set of receive antennas of the communication system, an RF receive signal of the communication system;

    wherein the RF receive signal is an analog signal having a second center frequency;

    wherein the second center frequency is identical to the first center frequency;

    wherein the set of transmit antennas and the set of receive antennas are configured such that destructive interference removes a first portion of self-interference from the RF receive signal;

    transforming, in the RF domain and without performing frequency downconversion, the sampled RF transmit signal into an RF self-interference cancellation signal;

    wherein transforming the sampled RF transmit signal comprises attenuating, phase shifting, time delaying, and inverting the RF transmit signal;

    combining, over a wired cancellation path, in order to remove a second portion of self-interference from the RF receive signal, the RF self- interference cancellation signal with the RF receive signal, resulting in a reduced-interference residual RF receive signal;

    converting the reduced-interference residual RF receive signal into a reduced-interference residual digital receive signal;

    transforming, in the digital domain, the sampled digital transmit signal into a digital self-interference cancellation signal using digital noise cancellation techniques; and

    combining, in order to remove a third portion of self-interference from the reduced-interference residual digital receive signal, the digital self-interference cancellation signal with the reduced-interference residual digital receive signal, resulting in a further-reduced-interference residual digital receive signal.

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