Abstract: There is provided mechanisms for mitigating interference in a network node. A method is performed by a control device (200). The method comprises receiving (S102) radio signals comprising at least one desired signal and interference, estimating (S104) a characteristic of the interference, wherein the estimation comprises calculating correlation statistics of power levels of frequency sub-bands comprising the interference with frequency sub-bands comprising the received radio signals. The method comprises determining (S106) an interference suppression matrix to suppress the interference in the frequency sub-bands of the received radio signals based on the estimated characteristic of the interference, wherein the interference suppression matrix is further determined based on information from inter-band interference observed across distinct sub-bands of the received radio signals.

Abstract: Embodiments include methods for determining intermodulation distortion (IMD) present in an uplink channel received by a network node in a wireless communication network. Such embodiments include, for each of a plurality of time period pairs comprising first and second time periods: measuring a first parameter for an uplink channel received and a second parameter for each of a plurality of downlink channels transmitted by the network node; and for the uplink channel, determining a first difference between the first parameter measured during the first time period and the first parameter measured during the second time period. Such embodiments also include, based on the first difference and the second parameters, determining a predictive model for an IMD signal, associated with the downlink channels, that can be received by the network node in the uplink channel. For example, the predictive model can be used to adjust transmitter settings to improve IMD performance.

Abstract: A method and network node for detection of passive intermodulation (PIM) are disclosed. According to one aspect, a method includes determining values of a covariance matrix based at least in part on uplink signals received by the network node radio. The method also includes determining a plurality of uplink (UL) channel 5 eigenvalues based at least in part on an eigen-component acquisition technique. The method further includes determining a presence or absence of PIM based at least in part on a plurality of the UL channel eigenvalues.

Abstract: A method and radio in a network node for passive intermodulation (PIM) downlink subspace acquisition. According to one aspect, a method includes determining a downlink projection matrix that is formed using the downlink beamforming weights and determining a first downlink interference covariance matrix estimate for a current downlink orthogonal frequency division multiplexed, OFDM, symbol based at least in part on multiplying the downlink projection matrix by a scaling factor that is dependent on the passive intermodulation, PIM, power generated in one or more uplink channels.

Abstract: A method in a network node and an apparatus for determining passive intermodulation (PIM) characteristics at the network node are provided. According to one aspect, a method includes capturing signals from each of at least one antenna port at a first time and a second time. The method includes determining a first covariance matrix based on signals captured at the first time. The method also includes determining a second covariance matrix based on signals captured at the second time. The method further includes determining a difference matrix, the difference matrix being based on a difference between the first and second covariance matrices, the difference matrix corresponding to changes in PIM between the first time and the second time.

Abstract: There is provided mechanisms for mitigating interference in a network node. A method is performed by a control device (200). The method comprises receiving (S102) radio signals comprising at least one desired signal and interference, estimating (S104) a characteristic of the interference, wherein the estimation comprises calculating correlation statistics of power levels of frequency sub-bands comprising the interference with frequency sub-bands comprising the received radio signals. The method comprises determining (S106) an interference suppression matrix to suppress the interference in the frequency sub-bands of the received radio signals based on the estimated characteristic of the interference, wherein the interference suppression matrix is further determined based on information from inter-band interference observed across distinct sub-bands of the received radio signals.

Abstract: Embodiments include methods for determining intermodulation distortion (IMD) present in an uplink channel received by a network node in a wireless communication network. Such embodiments include, for each of a plurality of time period pairs comprising first and second time periods: measuring a first parameter for an uplink channel received and a second parameter for each of a plurality of downlink channels transmitted by the network node; and for the uplink channel, determining a first difference between the first parameter measured during the first time period and the first parameter measured during the second time period. Such embodiments also include, based on the first difference and the second parameters, determining a predictive model for an IMD signal, associated with the downlink channels, that can be received by the network node in the uplink channel. For example, the predictive model can be used to adjust transmitter settings to improve IMD performance.

Abstract: A method and network node for detection of passive intermodulation (PIM) are disclosed. According to one aspect, a method includes determining values of a covariance matrix based at least in part on uplink signals received by the network node radio. The method also includes determining a plurality of uplink (UL) channel 5 eigenvalues based at least in part on an eigen-component acquisition technique. The method further includes determining a presence or absence of PIM based at least in part on a plurality of the UL channel eigenvalues.

Abstract: Systems and methods are disclosed herein that related to Peak-to-Average Power Ratio (PAPR) reduction in a (e.g., massive) Multiple-Input Multiple-Output (MIMO) Orthogonal Division Multiplexing (OFDM) transmitter system. In some embodiments, a method of operation of a MIMO OFDM transmitter system comprises, for each carrier of two or more carriers, performing precoding of a plurality of frequency-domain input signals for the carrier to provide a plurality of frequency-domain precoded signals for the carrier, the plurality of frequency-domain input signals for the carrier being for a plurality of transmit layers for the carrier, respectively. The method further comprises processing the frequency-domain precoded signals for the two or more carriers in accordance with a multi-carrier Convex Reduction of Amplitudes (CRAM) processing scheme to provide a plurality of multi-carrier time-domain transmit signals for a plurality of antenna branches, respectively, of the MIMO OFDM transmitter system.

Abstract: Systems and methods are disclosed herein that related to Peak-to-Average Power Ratio (PAPR) reduction in a (e.g., massive) Multiple-Input Multiple-Output (MIMO) Orthogonal Division Multiplexing (OFDM) transmitter system. In some embodiments, a method of operation of a MIMO OFDM transmitter system comprises, for each carrier of two or more carriers, performing precoding of a plurality of frequency-domain input signals for the carrier to provide a plurality of frequency-domain precoded signals for the carrier, the plurality of frequency-domain input signals for the carrier being for a plurality of transmit layers for the carrier, respectively. The method further comprises processing the frequency-domain precoded signals for the two or more carriers in accordance with a multi-carrier Convex Reduction of Amplitudes (CRAM) processing scheme to provide a plurality of multi-carrier time-domain transmit signals for a plurality of antenna branches, respectively, of the MIMO OFDM transmitter system.

Abstract: Systems and methods providing improved duplexer isolation are disclosed. In one embodiment, a system having improved duplexer isolation includes a duplexer system and one or more digital filters. The duplexer system includes a first transmit port, a second transmit port, a receive port, and an antenna port. The duplexer system is configured to receive a first transmit signal at the first transmit port and a second transmit signal at the second transmit port, where the first and second transmit signals are balanced transmit signals. The duplexer system is configured to combine the first and second transmit signals at the antenna port. The one or more digital filters are configured to cause destructive combining of transmit leakage signals at the receive port. As a result, the isolation of the duplexer system is substantially improved.

Abstract: A method and system for identifying passive intermodulation, PIM, at a base station in a wireless communication system are disclosed. In some embodiments, a method includes measuring the noise floor in a radio frequency, RF, channel of an uplink carrier, the uplink carrier comprising a carrier transmitted from a wireless device to the base station. The method includes comparing the measured noise floor to a predetermined noise floor. The method also includes determining whether PIM is present based on a result of the comparison.

Abstract: A method and system for identifying passive intermodulation, PIM, at a base station in a wireless communication system are disclosed. In some embodiments, a method includes measuring the noise floor in a radio frequency, RF, channel of an uplink carrier, the uplink carrier comprising a carrier transmitted from a wireless device to the base station. The method includes comparing the measured noise floor to a predetermined noise floor. The method also includes determining whether PIM is present based on a result of the comparison.

Abstract: Embodiments of a dual-mode radio system are disclosed. In one embodiment, the radio system includes a first radio unit including a transmitter, a receiver, an antenna, and switching circuitry adapted to couple either an output of the transmitter of the first radio unit or an input of the receiver of the first radio unit to the antenna of the first radio unit. In addition, the radio system includes a second radio unit including an antenna and either a transmitter having an output coupled to the antenna of the second radio unit, a receiver having an input coupled to the antenna of the second radio unit, or both a transmitter having an output selectively coupled to the antenna of the second radio unit and a receiver having an input selectively coupled to the antenna of the second radio unit. The radio system has both a full-duplex mode and a half-duplex mode.

Abstract: Systems and methods for suppressing transmitter noise in a receive band of a co-located receiver that are suitable for wideband applications are disclosed. In one embodiment, a transmitter is configured to upconvert and amplify a digital transmit signal to provide an analog radio frequency transmit signal at an output of the transmitter that includes a desired signal in a transmit band of the transmitter and transmitter noise in a receive band of a main receiver. The main receiver is configured to amplify, downconvert, and digitize an analog radio frequency receive signal to provide a digital receive signal. The digital feedforward transmit noise cancellation subsystem is configured to process the digital transmit signal to generate a digital transmitter noise cancellation signal that is representative of the transmitter noise in the receive band and is subtracted from the digital receive signal to thereby provide a compensated digital receive signal.

Abstract: Systems and methods are disclosed for active cancellation of transmitter leakage in a radio receiver that reduce power consumption and/or reduce noise in a desired receive frequency band. In some embodiments, in order to cancel transmitter leakage in a receive path, a cancellation signal is injected into the receive path in an upstream direction. By injecting the cancellation signal in the upstream direction, a noise component of the cancellation signal propagates through the receive path in the upstream direction and is either passed through a receive antenna or attenuated by an upstream component. Conversely, a desired component of the cancellation signal is reflected by an upstream filter and, thereafter, propagates through the receive path in the downstream direction to thereby cancel the transmitter leakage in the receive path. In this manner, active transmitter leakage cancellation can be performed while minimizing degradation of receiver sensitivity.

Abstract: Systems and methods providing improved duplexer isolation are disclosed. In one embodiment, a system having improved duplexer isolation includes a duplexer system and one or more digital filters. The duplexer system includes a first transmit port, a second transmit port, a receive port, and an antenna port. The duplexer system is configured to receive a first transmit signal at the first transmit port and a second transmit signal at the second transmit port, where the first and second transmit signals are balanced transmit signals. The duplexer system is configured to combine the first and second transmit signals at the antenna port. The one or more digital filters are configured to cause destructive combining of transmit leakage signals at the receive port. As a result, the isolation of the duplexer system is substantially improved.

Abstract: Systems and methods are disclosed for active cancellation of transmitter leakage in a radio receiver that reduce power consumption and/or reduce noise in a desired receive frequency band. In some embodiments, in order to cancel transmitter leakage in a receive path, a cancellation signal is injected into the receive path in an upstream direction. By injecting the cancellation signal in the upstream direction, a noise component of the cancellation signal propagates through the receive path in the upstream direction and is either passed through a receive antenna or attenuated by an upstream component. Conversely, a desired component of the cancellation signal is reflected by an upstream filter and, thereafter, propagates through the receive path in the downstream direction to thereby cancel the transmitter leakage in the receive path. In this manner, active transmitter leakage cancellation can be performed while minimizing degradation of receiver sensitivity.

Abstract: Embodiments of a dual-mode radio system are disclosed. In one embodiment, the radio system includes a first radio unit including a transmitter, a receiver, an antenna, and switching circuitry adapted to couple either an output of the transmitter of the first radio unit or an input of the receiver of the first radio unit to the antenna of the first radio unit. In addition, the radio system includes a second radio unit including an antenna and either a transmitter having an output coupled to the antenna of the second radio unit, a receiver having an input coupled to the antenna of the second radio unit, or both a transmitter having an output selectively coupled to the antenna of the second radio unit and a receiver having an input selectively coupled to the antenna of the second radio unit. The radio system has both a full-duplex mode and a half-duplex mode.

Abstract: Systems and methods for suppressing transmitter noise in a receive band of a co-located receiver that are suitable for wideband applications are disclosed. In one embodiment, a transmitter is configured to upconvert and amplify a digital transmit signal to provide an analog radio frequency transmit signal at an output of the transmitter that includes a desired signal in a transmit band of the transmitter and transmitter noise in a receive band of a main receiver. The main receiver is configured to amplify, downconvert, and digitize an analog radio frequency receive signal to provide a digital receive signal. The digital feedforward transmit noise cancellation subsystem is configured to process the digital transmit signal to generate a digital transmitter noise cancellation signal that is representative of the transmitter noise in the receive band and is subtracted from the digital receive signal to thereby provide a compensated digital receive signal.