Abstract: Embodiments herein describe a PIM correction circuit. In a base station, TX and RX RF changes, band pass filters, duplexers, and diplexers can have severe memory effects due to their sharp transition bandwidth from pass band to stop band. PIM interference, generated by the TX signals and reflected onto the RX RF chain will include these memory effects. These memory effects make PIM cancellation complex, requiring complicated computations and circuits. However, the embodiments herein use a PIM correction circuit that separates the memory effects of the TX and RX paths from the memory effects of PIM, thereby reducing PIM cancellation complexity and hardware implementation cost.

Abstract: A digital predistortion (DPD) system includes an input configured to receive an input signal. In some examples, a first signal path configured to generate a first signal based on the input signal. In some examples, an error model provider configured to generate an error model signal modeled after a gate bias error voltage associated with the DPD system. In some examples, a first combiner configured to combine the first signal and the error model signal to generate a first intermediate signal, and the DPD system generates an output signal based at least on the first intermediate signal.

Abstract: A computer-implemented method for suppressing noise from audio signal uses both statistical noise estimation and neural network noise estimation to achieve more desirable noise reduction. The method is performed by a noise suppression computer software application running on an electronic device. The noise suppression computer software application first transforms the speech signal in time domain into frequency domain before determining a statistical noise estimate and a neural network noise estimate. The noise suppression computer software application merges the two noise estimates to derive a final noise estimate, and determines and refines a noise suppression filter. The filter is applied to the speech signal in frequency domain to obtain an enhanced signal. The enhanced signal is transformed back into time domain.

Abstract: A system and method for provide high quality audio in real-time communication over low bit rate network connections. The system includes real-time communication software application having an improved encoder and an improved decoder. The encoder decomposes audio data based on two frequency ranges corresponding to a super wideband mode and a wideband mode into a lower sub-band and a higher sub-band. Audio features are extracted from the lower sub-band and higher sub-band audio data. The audio features are quantized and packaged. The decoder reconstructs the audio data for playback on the receiving device based on the compressed audio features in the super wideband mode and the wideband mode.

Abstract: A method for recovering a current frame of an audio stream includes detecting that a current packet is lost, the current packet including an audio signal; splitting one or more frames into respective high-band signals and respective low-band signals, the one or more frames precede the current frame in the audio stream; inferring a current low-band signal of the current frame using, as inputs to a machine-learning model, the respective low-band signals; combining the inferred current low-band signal with the respective high-band signals to obtain the current frame; and adding the current frame to a playout buffer.

Abstract: A new audio quality assessment system includes an assessment system running in a receiver system of a VoIP communication system. The new audio quality assessment system determines an accurate MOS of a VoIP call within a time window. The audio quality assessment system determines an effective PLC counter, a PLC impact factor, an effective AS counter, an AS impact factor, a network impact factor, a codec type of the received voice packets, a bitrate of the received voice packets, an initial MOS from a configured codec-bitrate MOS table, and determines the accurate MOS based on these data. The determined MOS is more accurate and efficiently obtained since it is based on efficiently collected statistics of the receiver system's modules and a pre-configured codec-bitrate MOS table.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a front-end (FE) instance and a plurality of real-time graph (RTG) instances, each of the plurality of RTG instances includes a plurality of device objects, the FE instance being configured to communicate with a client device associated with a first user; establishing a bi-directional streaming remote procedure call (RPC) connection between the FE instance and the plurality of RTG instances; receiving, by the FE instance, a status update from the client device; determining, by the FE instance, that a first device object corresponding to the client device is stored on a first RTG instance of the plurality of RTG instances; and transmitting a first message comprising the status update from the FE instance to the first RTG instance to update the first device object.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a plurality of real-time graph (RTG) instances that include a plurality of device objects; receiving, by a first device object of the plurality of device objects, a status update from a client device associated with a first user; transmitting, by the first device object, a first message comprising the status update to a second device object associated with a second user over a real-time link; and transmitting, by the first device object, a second message comprising the status update to a third device object associated with a third user over a first rate-limited link.

Abstract: A new audio quality assessment system includes an assessment system running in a receiver system of a VoIP communication system. The new audio quality assessment system determines an accurate MOS of a VoIP call within a time window. The audio quality assessment system determines an effective PLC counter, a PLC impact factor, an effective AS counter, an AS impact factor, a network impact factor, a codec type of the received voice packets, a bitrate of the received voice packets, an initial MOS from a configured codec-bitrate MOS table, and determines the accurate MOS based on these data. The determined MOS is more accurate and efficiently obtained since it is based on efficiently collected statistics of the receiver system's modules and a pre-configured codec-bitrate MOS table.

Abstract: A method includes extracting, from a frame of the audio sample, spectral features indicative of cochlear impulse response of an auditory system; obtaining an estimate of a speech signal in the frame from a neural network that is trained, during a training phase, to accept the spectral features as input and output the estimate of the speech signal, where the estimate of the speech signal includes reverberation and excludes noise present in the frame; mapping the estimate of the speech signal to a frequency domain of the frame using mapping parameters obtained during the training phase to obtain an estimate of a reverberant speech spectrum in the frame; and obtaining, from a time-distributed neural network, a dereverberant frame of the frame, where the estimate of the reverberant speech spectrum in the frame is used as an input to the time-distributed neural network.

Abstract: A vision-haptics fused augmented reality simulator for dental surgical skill training, including a dental simulation training platform constructed based on an artificial head phantom; a dental operation training system based on a haptic feedback device; an observation system based on an augmented reality head-mounted display; generating a virtual dental model by modeling based on CBCT data and scan data of a patient's dental cavity, to construct a virtual dental environment; based on the virtual dental model and feature points obtained through scanning on the artificial head phantom, performing a spatial matching of a virtual dental cavity and a dental model; in a virtual dental surgery simulation method, outputting haptics information and visual information at frequencies of not less than 1000 Hz and 60 Hz, respectively; performing a visual information processing method on grid data; and performing a haptics-vision space calibration method based on information of an operator's head.

Abstract: A vision-haptics fused augmented reality simulator for dental surgical skill training, including a dental simulation training platform constructed based on an artificial head phantom; a dental operation training system based on a haptic feedback device; an observation system based on an augmented reality head-mounted display; generating a virtual dental model by modeling based on CBCT data and scan data of a patient's dental cavity, to construct a virtual dental environment; based on the virtual dental model and feature points obtained through scanning on the artificial head phantom, performing a spatial matching of a virtual dental cavity and a dental model; in a virtual dental surgery simulation method, outputting haptics information and visual information at frequencies of not less than 1000 Hz and 60 Hz, respectively; performing a visual information processing method on grid data; and performing a haptics-vision space calibration method based on information of an operator's head.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a plurality of real-time graph (RTG) instances that include a plurality of device objects, the plurality of device objects comprising a first device object associated with a given user; receiving, by the first device object, a friends list of the given user having a first version identifier; receiving, by the first device object, an update from a client device associated with the given user, the update comprising a friends list version identifier; determining that the first version identifier of the friends list in the first device object mismatches the friends list version identifier in the update; and synchronizing the friends list in the first device object prior to sending one or more messages that include the update to other device objects of the plurality of device objects.

Abstract: A method includes extracting, from a frame of the audio sample, spectral features indicative of cochlear impulse response of an auditory system; obtaining an estimate of a speech signal in the frame from a neural network that is trained, during a training phase, to accept the spectral features as input and output the estimate of the speech signal, where the estimate of the speech signal includes reverberation and excludes noise present in the frame; mapping the estimate of the speech signal to a frequency domain of the frame using mapping parameters obtained during the training phase to obtain an estimate of a reverberant speech spectrum in the frame; and obtaining, from a time-distributed neural network, a dereverberant frame of the frame, where the estimate of the reverberant speech spectrum in the frame is used as an input to the time-distributed neural network.

Abstract: Aspects of the present disclosure involve systems and methods for performing operations comprising: storing, on a distributed storage system, one or more front-end (FE) instances and a plurality of real-time graph (RTG) instances; receiving, by a first online device object associated with a given user, an update from a first client device; generating, by the first online device object, a message that includes the update for transmission to a plurality of friends of the given user; storing, on a given one of the plurality of RTG instances, an offline device object for a first friend of the plurality of friends and a second online device object for a second friend of the plurality of friends; and transmitting, by the first online device object, the message that includes the update to the offline device object of the first friend and the second online device object of the second friend.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a plurality of real-time graph (RTG) instances that include a plurality of device objects, the plurality of device objects comprising a first device object associated with a given user; receiving, by the first device object, a friends list of the given user having a first version identifier; receiving, by the first device object, an update from a client device associated with the given user, the update comprising a friends list version identifier; determining that the first version identifier of the friends list in the first device object mismatches the friends list version identifier in the update; and synchronizing the friends list in the first device object prior to sending one or more messages that include the update to other device objects of the plurality of device objects.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a plurality of real-time graph (RTG) instances that include a plurality of device objects; receiving, by a first device object of the plurality of device objects, a status update from a client device associated with a first user; transmitting, by the first device object, a first message comprising the status update to a second device object associated with a second user over a real-time link; and transmitting, by the first device object, a second message comprising the status update to a third device object associated with a third user over a first rate-limited link.

Abstract: Aspects of the present disclosure involve a system and a method for performing operations comprising: storing, on a distributed storage system, a front-end (FE) instance and a plurality of real-time graph (RTG) instances, each of the plurality of RTG instances includes a plurality of device objects, the FE instance being configured to communicate with a client device associated with a first user; establishing a bi-directional streaming remote procedure call (RPC) connection between the FE instance and the plurality of RTG instances; receiving, by the FE instance, a status update from the client device; determining, by the FE instance, that a first device object corresponding to the client device is stored on a first RTG instance of the plurality of RTG instances; and transmitting a first message comprising the status update from the FE instance to the first RTG instance to update the first device object.

Abstract: Aspects of the present disclosure involve systems and methods for performing operations comprising: storing, on a distributed storage system, one or more front-end (FE) instances and a plurality of real-time graph (RTG) instances; receiving, by a first online device object associated with a given user, an update from a first client device; generating, by the first online device object, a message that includes the update for transmission to a plurality of friends of the given user; storing, on a given one of the plurality of RTG instances, an offline device object for a first friend of the plurality of friends and a second online device object for a second friend of the plurality of friends; and transmitting, by the first online device object, the message that includes the update to the offline device object of the first friend and the second online device object of the second friend.

Abstract: A method for recovering a current frame of an audio stream includes detecting that a current packet is lost, the current packet including an audio signal; splitting one or more frames into respective high-band signals and respective low-band signals, the one or more frames precede the current frame in the audio stream; inferring a current low-band signal of the current frame using, as inputs to a machine-learning model, the respective low-band signals; combining the inferred current low-band signal with the respective high-band signals to obtain the current frame; and adding the current frame to a playout buffer.