# US 9,438,356 B2 · Method and apparatus for cancelling self-interference signal between transmission antenna and reception antenna > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,356 B2 - Document ID: US9438356B2 - Status: Granted - Kind: B2 - Application number: 14/988,426 - Filed: 2016-01-05 - Published: 2016-05-12 - Granted: 2016-09-06 - Earliest claimed: 2014-04-27 - Assignees: LG Electronics Inc. - Applicants: LG Electronics Inc. - Inventors: Jinmin Kim; Jaehoon Chung; Genebeck Hahn; Eunjong Lee; Kukheon Choi; Kwangseok Noh - Web page: https://patentgrep.com/patent/US9438356B2 ## CPC - H04B 15/02: Reducing interference from electric apparatus by means located at or near the interfering apparatus - H04B 1/48: in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter {(H04B1/46 takes precedence)} - H04B 1/525: with means for reducing leakage of transmitter signal into the receiver - H04B 7/026: Co-operative diversity, e.g. using fixed or mobile stations as relays - H04B 7/0626: {Channel coefficients, e.g. channel state information [CSI]} - H04B 7/24: for communication between two or more posts (wireless communication networks H04W) - H04B 15/00: Suppression or limitation of noise or interference (by means associated with receiver H04B1/10) - H04B 2001/485: {inhibiting unwanted transmission} - H04B: TRANSMISSION ## Abstract An apparatus for cancelling a self-interference signal between a transmission antenna and a reception antenna is disclosed. The apparatus includes a first self-interference signal cancellation unit for cancelling a self-interference signal in consideration of a linear channel between the transmission antenna and the reception antenna, a second self-interference signal cancellation unit for cancelling a self-interference signal in consideration of nonlinear channel characteristic between the transmission antenna and the reception antenna or linear characteristic of a radio channel, and a controller for comparing a transmitted signal output from the transmission antenna and a received signal received by the reception antenna to provide a first coefficient to be applied to self-interference signal cancellation of a linear device in the first self-interference signal cancellation unit and a second coefficient to be applied to self-interference signal cancellation of a nonlinear device in the second self-interference signal cancellation unit. ## Claims ### Claim 1 A method for cancelling a self-interference signal by a communication apparatus, the method comprising: generating a signal for self-interference cancellation using a signal to be transmitted from a transmission antenna and a non-linear channel property between the transmission antenna and a reception antenna; receiving the self-interference signal through the reception antenna; and cancelling self-interference by subtracting the received self-interference signal from the generated signal for self-interference cancellation. ### Claim 2 (depends on 1) The method of claim 1, further comprising: applying a time delay to the signal to be transmitted from the transmission antenna, wherein the signal for self-interference cancellation is generated using the time delay-applied signal and the non-linear channel property between the transmission antenna and the reception antenna. ### Claim 3 (depends on 1) The method of claim 1, wherein the cancelling is performed before a low noise before amplifier (LNA) of a receiving end. ### Claim 4 (depends on 1) The method of claim 1, further comprising: dividing signals to be transmitted from the transmission antenna to a plurality of signals; applying a time delay to each of the plurality of signals; and wherein the signal for self-interference cancellation is generated using the time delay-applied signals and the non-linear channel property between the transmission antenna and the reception antenna. ### Claim 5 (depends on 1) The method of claim 1, further comprising: applying a time delay to the signal to be transmitted from the transmission antenna, applying a phase shift to the time delay-applied signal, wherein the signal for self-interference cancellation is generated using the phase shift-applied signals and the non-linear channel property between the transmission antenna and the reception antenna. ### Claim 6 A communication apparatus for cancelling a self-interference signal, the communication apparatus comprising: a self-interference cancellation generation unit configured to generate a signal for self-interference cancellation using a signal to be transmitted from the transmission antenna and a non-linear channel property between the transmission antenna and a reception antenna; a reception antenna configured to receive the self-interference signal; and a self-interference cancelling unit configured to cancel self-interference by subtracting the received self-interference signal from the generated signal for self-interference cancellation. ### Claim 7 (depends on 6) The communication apparatus of claim 6, further comprising: a time delayer configured to apply a time delay to the signal to be transmitted from the transmission antenna, wherein the signal for self-interference cancellation is generated using the time delay-applied signal and the non-linear channel property between the transmission antenna and the reception antenna. ### Claim 8 (depends on 6) The communication apparatus of claim 6, further comprising: a low noise before amplifier (LNA) of a receiving end, wherein the a self-interference cancelling unit is configured to cancel self-interference before a low noise before amplifier (LNA) of a receiving end. ### Claim 9 (depends on 6) The communication apparatus of claim 6, further comprising: a divider configured to divide signals to be transmitted from the transmission antenna to a plurality of signals; a plurality of time delayer configured to apply a time delay to each of the plurality of signals; and wherein the self-interference cancellation generation unit is configured to generate the signal for self-interference cancellation using the time delay-applied signals and the non-linear channel property between the transmission antenna and the reception antenna. ### Claim 10 (depends on 6) The communication apparatus of claim 6, further comprising: a time delayer configured to apply a time delay to the signal to be transmitted from the transmission antenna, a phase shifter configured to apply a phase shift to the time delay-applied signal, wherein the self-interference cancellation generation unit is configured to generate the signal for self-interference cancellation using the phase shift-applied signals and the non-linear channel property between the transmission antenna and the reception antenna.