# US 2018/0026776 A1 · Self-interference signal cancellation apparatus and transceiver including the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026776 A1 - Document ID: US20180026776A1 - Status: Published application - Kind: A1 - Application number: 15/657,087 - Filed: 2017-07-21 - Published: 2018-01-25 - Earliest claimed: 2016-07-22 - Assignees: Electronics and Telecommunications Research Institute - Applicants: Electronics and Telecommunications Research Institute - Inventors: Sung Jun LEE - Web page: https://patentgrep.com/patent/US20180026776A1 ## CPC - H04L 5/1461: {Suppression of signals in the return path, i.e. bidirectional control circuits} - 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 2001/485: {inhibiting unwanted transmission} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04B: TRANSMISSION ## Abstract An apparatus for canceling a self-interference signal and a transceiver including the same are disclosed. The transceiver may include an antenna; a circulator transmitting a portion of a transmit signal to the antenna and transmitting a receive signal received through the antenna to a receiver; and a self-interference signal canceling unit receiving a first signal, which is a portion of the transmit signal, and physically copying a self-interference signal generated by the antenna and the circulator to generate an estimation signal of the self-interference signal. ## Claims ### Claim 1 A transceiver comprising: an antenna; a first circulator transmitting a portion of a transmit signal to the antenna and transmitting a receive signal received through the antenna to a receiver; and a self-interference signal canceling unit receiving a first signal, which is a portion of the transmit signal, and physically copying a self-interference signal generated by the antenna and the first circulator to generate an estimation signal of the self-interference signal. ### Claim 2 (depends on 1) The transceiver of claim 1, wherein: the self-interference signal canceling unit includes a second circulator having the same characteristics as the first circulator; and a load generator connected to the second circulator and physically copying input impedance of the antenna. ### Claim 3 (depends on 2) The transceiver of claim 2, wherein: the self-interference signal canceling unit further includes a signal shifter that adjusts magnitude of an output signal of the second circulator, so as to compensate for a magnitude difference between the self-interference signal and the estimation signal of the self-interference signal. ### Claim 4 (depends on 2) The transceiver of claim 2, wherein: the self-interference signal canceling unit further includes a phase shifter that adjusts a phase of an output signal of the second circulator so that the estimation signal of the self-interference signal is canceled from the signal inputted to the receiver through the antenna and the first circulator. ### Claim 5 (depends on 2) The transceiver of claim 2, wherein: the self-interference signal canceling unit further includes a transmission line that generates a time delay in an output signal of the second circulator, so as to compensate for a time delay difference between the self-interference signal and the estimation signal of the self-interference signal. ### Claim 6 (depends on 2) The transceiver of claim 2, wherein: the load generator includes a transmission line having a predetermined length and a matching network having a predetermined impedance value, and input impedance by the transmission line and the matching network physically copies the input impedance of the antenna. ### Claim 7 (depends on 1) The transceiver of claim 1, further comprising: a divider receiving the transmit signal and separating the first signal from the transmit signal to transmit the first signal to the self-interference signal canceling unit; and a combiner combining the signal inputted to the receiver through the antenna and the first circulator with the estimation signal of the self-interference signal. ### Claim 8 (depends on 7) The transceiver of claim 7, wherein: the divider and the combiner are RF couplers. ### Claim 9 An apparatus for canceling a self-interference signal generated by an antenna and a first circulator, in a transceiver including the antenna, and the first circulator transmitting a portion of a transmit signal to the antenna and transmitting a receive signal received through the antenna to a receiver, the apparatus comprising: a second circulator receiving a first signal, which is a portion of the transmit signal, and physically copying the first circulator to output a second signal; and a load generator connected to the second circulator and showing input impedance of the antenna. ### Claim 10 (depends on 9) The apparatus of claim 9, further comprising: a signal shifter adjusting magnitude of the second signal. ### Claim 11 (depends on 9) The apparatus of claim 9, further comprising: a phase shifter adjusting a phase of the second signal. ### Claim 12 (depends on 9) The apparatus of claim 9, further comprising: a transmission line generating a time delay in the second signal. ### Claim 13 (depends on 9) The apparatus of claim 9, wherein: the load generator includes a transmission line having a predetermined length and a matching network having a predetermined impedance value, and input impedance by the transmission line and the matching network physically copies the input impedance of the antenna. ### Claim 14 (depends on 9) The apparatus of claim 9, further comprising: a divider receiving the transmit signal and separating the first signal from the transmit signal to output the first signal to the second circulator; and a combiner combining the signal inputted to the receiver through the antenna and the first circulator with a signal corresponding to the second signal. ### Claim 15 A transceiver comprising: a first antenna transmitting a portion of a transmit signal; a second antenna positioned to be spaced apart from the first antenna by a first length and receiving a receive signal; and a self-interference signal canceling unit receiving a first signal, which is a portion of the transmit signal, and physically copying a self-interference signal generated by the first length to generate an estimation signal of the self-interference signal. ### Claim 16 (depends on 15) The transceiver of claim 15, further comprising: a divider receiving the transmit signal and separating the first signal from the transmit signal to transmit the first signal to the self-interference signal canceling unit; and a combiner combining the second signal inputted through the second antenna with the estimation signal of the self-interference signal. ### Claim 17 (depends on 16) The transceiver of claim 16, wherein: the self-interference signal canceling unit includes a transmission line having a predetermined length by considering a second length, which is a physical length between the divider and the first antenna, a third length, which is a physical length between the second antenna and the combiner, and the first length. ### Claim 18 (depends on 17) The transceiver of claim 17, wherein: the self-interference signal canceling unit further includes a signal shifter that adjusts magnitude of the first signal, so as to compensate for a magnitude difference between the self-interference signal and the estimation signal of the self-interference signal. ### Claim 19 (depends on 17) The transceiver of claim 17, wherein: the self-interference signal canceling unit further includes a phase shifter that adjusts a phase of the first signal so that the estimation signal of the self-interference signal is canceled from the second signal.