An iterative two dimension equalizer usable in a receiver of orthogonal time frequency space (OTFS) modulated signals is described. In one configuration of the equalizer, a forward path generates, from received time-frequency domain samples and a channel estimate, estimates of data bits and likelihood numbers associated with the estimates of data bits, generated by delay-Doppler domain processing. In the feedback direction, the estimates of data bits are used to generate symbol estimates and autocorrelation matrix estimate in the time domain. In another configuration, a soft symbol mapper is used in the feedback direction for directly generating the feedback input symbol estimate without having to generate estimates of data bits.

Techniques and architectures for multi-stage cancellation of self-interference (SI) and joint cancellation of mutual-interference (MI) and residual SI in signals received by devices of a full-duplex multi-cell network are disclosed. In various examples, channel estimations and interference cancellation operations are performed utilizing multiple orthogonal training signals transmitted by network devices during a common over-the-air training period. Training signals derived from the orthogonal training signals during transmission are utilized to generate SI estimation information and perform at least a first SI cancellation operation on a received signal that includes at least first and second orthogonal training signals. The received signal and orthogonal training signals are then used to estimate a MI channel impulse response and a (residual) SI channel impulse response for use in joint MI/SI cancellation operations on further received signals. Details regarding the design of the orthogonal training signals and a unique system-level delay calibration procedure are also provided.

In examples, Time-Reversal (TR) Orthogonal Frequency-Division Multiplexing (OFDM) communications employ adaptive filtering on a per-subcarrier basis. Matched filtering is used for subcarriers with poor transmission properties (such as relatively high channel attenuation), while inverse filtering is used for subcarriers with relatively good transmission properties (such as relatively low channel attenuation). Modulation order may be reduced for the subcarriers with poor properties (relative to the subcarriers with good properties). The discovery of subcarrier properties may be performed through the channel state information measured and reconciled from single- and/or bi-directional TR sounding signals. The discovery may be repeated, for example, performed continually. In response to changes in traffic and other environmental conditions, the system may be reconfigured dynamically with different subcarriers selected for matched and inverse filtering. In examples, a normalized signal-to-noise ratio threshold dividing good and poor transmission properties is computed based on an acceptable symbol error rate.

A method to be performed at a station configured to connect to a Long Term Evolution radio access network (LTE-RAN) to utilize enhanced Multimedia Broadcast Multicast Services using a Multicast-Broadcast Single-Frequency Network (MBSFN). The method including receiving a MBSFN subframe having a MBSFN subframe structure including a plurality of Orthogonal Frequency-Division Multiplexing (OFDM) symbols, a first one of the OFDM symbols having a first reference symbol inserted therein, a second one of the OFDM symbols having a second reference symbol inserted therein, determining a rate of change of channel conditions being experienced by the station and performing a non-destaggered channel estimation when the rate of change of channel conditions is greater than a predetermined threshold, the non-destaggered channel estimation using a first Channel Impulse Response (CIR) at the first OFDM symbol and a second CIR at the second OFDM symbol.

The present invention relates to a method and apparatus for adaptive channel estimation for signal-amplitude-based communications systems. In one arrangement, the method comprises: receiving an observation (r) of a transmitted coded symbol (d); generating, with a weight generator, a first coefficient (v) for weighting the received observation based on an estimate of the transmitted coded symbol (d_est), the first coefficient having a magnitude that is invariable with the amplitude of the transmitted coded symbol; and forming a new channel estimate (h_est) based on a weighted observation using the first coefficient (v).

Techniques are described for wireless communication. One method includes identifying a plurality of channel responses corresponding to a plurality of channels. Each channel of the plurality of channels corresponds to a pairing of a transmit antenna with a receive antenna. Each channel response of the plurality of channel responses corresponds to a plurality of tone subsets. The method also includes selecting, for each channel of the plurality of channels, a subset of non-frequency domain components of the channel response for the channel, and transmitting, for at least one channel of the plurality of channels, at least one subset of channel state information (CSI). The at least one subset of CSI is based at least in part on at least one of the selected subsets of non-frequency domain components.

A system and method for estimating clock drift in underwater instruments is provided. The method can include transmitting a signal from a source to a plurality of underwater receivers or a single receiver. Upon recovery of the underwater receivers, an initial sampling frequency value can be used to generate received data waveforms from data stored on each underwater device. The generated received waveforms can be used to generate a channel estimate for each receiver, and the channel estimates can be used to provide an estimate of the source motion during the transmission. The estimated source motion can then be used to estimate the clock drift.

In accordance with an embodiment the method includes temporarily configuring the vector processor with a new set of vectoring coefficients during one or more selected symbol positions; restoring the current set of vectoring coefficients outside the one or more selected symbol positions; obtaining at least one error measure over respectively at least one line of the group of vectored lines during the one or more selected symbol positions; and determining a suitability indication for the new set of vectoring coefficients based on the obtained at least one error measure.

The present application describes systems and methods of performing self-interference cancellation. According to an embodiment, the method sends a transmit signal through a circulator to substantially isolate the transmit signal from a receiver, with at least a portion of the transmit signal entering a receive path towards the receiver. The method also generates a reflected signal from an antenna. The reflected signal is at substantially less power than an incident power to the antenna. The reflected signal includes a transmitter carrier signal and a transmitter noise. The method also routes a received signal from the antenna to the receiver, and routes the reflected signal through a phase shifter in the receive path. Further, the method combines the reflected, phase shifted transmitter noise with the received signal in the receive path to cancel the portion of the transmit signal that entered the receive path towards the receiver.

At least one embodiment relates to power delay profile (PDP) estimation e.g. in 5G systems for channel estimation and for demodulation. The power delay profile is estimated directly in the frequency domain using LMMSE properties based on the knowledge of channel statistics. An example embodiment applies an approximation by estimating the second order statistics of the channel autocorrelation function in time domain represented by the variance of the derivative of raw channel estimates in frequency domain.