The present application describes systems and methods of performing self-interference cancellation. Such systems may include generating a transmit signal along a transmit path of a transceiver, where the transmit signal can be sent through a circulator to isolate the transmit signal from a receiver. The transmit signal may be transmitted from an antenna, and a signal may be reflected from the antenna, where the reflected signal may be at less power than an incident power to the antenna, and where the reflected signal may include a transmitter carrier signal and a transmitter noise. A received signal may be routed from the antenna to the receiver, the reflected signal may be routed through a filter and a phase shifter, and the signal may be combined with the received signal in the receive path to cancel the portion of the transmit signal that entered the receive path towards the receiver from the circulator.

The present application describes a feed forward method that may electronically cancel self-interference while it is still in the transmit path. It may employ delay length matching for electronic cancellation over large bandwidths.

The present application a digital self-interference residual cancellation method that adjusts a magnitude of a sampled transmit signal based on compared magnitude and phases associated with tones. The digital self-interference residual cancellation method may follow an analog carrier cancellation stage where the digital self-interference residual cancellation is based on a determination of the channel circuit response used to control an infinite impulse response filter which can compensate using both poles and zeroes.

The present application describes systems and methods of performing self-interference cancellation. Such systems may include generating a transmit signal along a transmit path of a transceiver, where the transmit signal can be sent through a circulator to isolate the transmit signal from a receiver. The transmit signal may be transmitted from an antenna, and a signal may be reflected from the antenna, where the reflected signal may be at less power than an incident power to the antenna, and where the reflected signal may include a transmitter carrier signal and a transmitter noise. A received signal may be routed from the antenna to the receiver, the reflected signal may be routed through a filter and a phase shifter, and the signal may be combined with the received signal in the receive path to cancel the portion of the transmit signal that entered the receive path towards the receiver from the circulator.

The present application describes a computer-implemented method for frequency hopping including configuring a radio front end to operate on a first frequency; receiving a transmit signal in a first path in the radio front end; amplifying a transmit signal in the first path; phase shifting the transmit signal in a second path in the radio front end, the second path being different from the first path; coupling the amplified transmit signal to a third path in the radio front end; coupling the phase-shifted transmit signal in the second path to the amplified transmit signal in the third path to form a carrier-cancelled signal in a fourth path in the radio front end in the radio front end; phase shifting the carrier-cancelled signal in the fourth path; coupling the phase-shifted carrier-cancelled signal in the fourth path to the amplified transmit

The present application describes a method for in-phase and quadrature phase (IQ) compensation in a frequency division duplex transceiver including a transmitter and a receiver is provided. The method includes transmitting, from a transmitter, a transmission signal including a message signal and a fixed tone at a frequency outside a reception band of the receiver, receiving, at the receiver, a reception signal including a portion of the transmission signal having the fixed tone and the message signal, determining, at a processor of the receiver, a gain mismatch (g) and a phase mismatch () between an in-phase (I) component and a quadrature (Q) phase component of the reception signal by detecting an image tone of the fixed tone in the reception signal, and minimizing, at the processor, the image tone to compensate the gain mismatch and the phase mismatch between the I and Q components of the reception signal.

The present application describes a method for characterizing a self-interference channel of a frequency division duplex transceiver including a transmitter and a receiver. The method includes transmitting, from a transmitter of a frequency division duplex transceiver in a transmission band, a transmission signal including a message signal and a swept tone that changes frequency from below an upper edge to above a lower edge of a reception band of a receiver, the self-interference channel being defined between the transmitter and the receiver of the frequency division duplex transceiver, such that at least a portion of the message signal leaks into a signal received the receiver, determining, at an infinite impulse response (IIR) filter of the receiver, an infinite impulse response of the self-interference channel based upon a reception of the swept tone swept at each frequency in the reception band, and estimating the self-interference channel, based upon the infinite impulse response.

A signal processing apparatus for enhancing a digital input signal (I(x.sub.i)) recorded by a recording system having a system response (H(x.sub.i)), is configured to retrieve the digital input signal (I(x.sub.i)) and compute a baseline estimate ((x.sub.i)) of the digital input signal, the baseline estimate representing a baseline of the digital input signal and comprising features of the digital input signal that are larger than a feature length (fl). The apparatus is further configured to remove the baseline estimate from the digital input signal to obtain an output signal comprising spatial features that are smaller than the feature length, retrieve a characteristic length (cl) of the system response (H(x.sub.i)) and compute the baseline estimate ((x.sub.i)) using a feature length that is smaller than the characteristic length of the system response (H(x.sub.i)).

A method for channel prediction for uplink (UL) and downlink (DL) massive Multiple Input Multiple Output (MIMO) systems for Open Radio Access Network (O-RAN) fronthaul Split 7.2 networks enables prediction of a channel that is seen by the UL slot. The pre-processing matrix is computed by the distributed unit (DU) based on this predicted channel and sent to the radio unit (RU) for minimizing the effects of channel aging. A channel corresponding to sounding reference signal (SRS) symbol closest to uplink slot being decoded can be predicted from previous SRS symbols and can be used as a combining matrix. Alternatively, the channel of the uplink slot itself can be predicted from past SRS symbols, and a combining matrix can be generated based on the predicted channel.

Provided is an interference cancellation circuit including a relative delay control circuit receiving a first transmission signal of a first frequency, and a second transmission signal of a second frequency different from the first frequency and including a first delay buffer delaying the second transmission signal by a first delay time and a second delay buffer delaying the second transmission signal by a second delay time, a delay reference generation circuit generating respective reference signals by receiving the first transmission signal and the delayed second transmission signal from the relative delay control circuit, a weight control circuit updating a weight vector, a relative delay estimation circuit estimating a relative delay based on the reference signals, and an adaptive filter generating an interference model signal based on the weight vector and a first reference signal of the reference signals and filter the interference model signal from a received signal.