Fiber, cable, and wireless data channels are typically impaired by reflectors and other imperfections, producing a channel state with echoes and frequency shifts in data waveforms. Here, methods of using pilot symbol waveform bursts to automatically produce a detailed 2D model of the channel state are presented. This 2D channel state can then be used to optimize data transmission. For wireless data channels, an even more detailed 2D model of channel state can be produced by using polarization and multiple antennas in the process. Once 2D channel states are known, the system turns imperfect data channels from a liability to an advantage by using channel imperfections to boost data transmission rates. The methods can be used to improve legacy data transmission modes in multiple types of media, and are particularly useful for producing new types of robust and high capacity wireless communications using non-legacy data transmission methods as well.

Methods for determining variability in a state of a medium, include monitoring the medium and determining the variability in the state of the medium based on the processing of the response over time based on the response detected at the at least one receive element over time. Monitoring the medium can include generating a transmit signal, transmitting it into the medium using a transmit element, and receiving a signal from the medium at a receive element. The transmit and receive elements can be decoupled from one another. The transmit and receive elements can have differing geometry. The determined variability in the state of the medium can be used to provide notifications and/or take automated actions.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Aspects of the subject disclosure may include, for example, causing a reference antenna element of a first set of antenna elements of a first antenna array to transmit a first signal, determining for each antenna element of a second set of antenna elements of a second antenna array, a receive-related offset, relative to the reference element, based on inter-element propagation delays between the first and second sets of elements, causing each antenna element of the second set of elements to transmit a respective second signal, based on the reference antenna element receiving the respective second signals, calculating a respective transmit-related offset for each antenna element of the second set of antenna elements relative to the reference antenna element based on the inter-element propagation delays, and performing calibration between the first antenna array and the second antenna array based on the respective receive-related and transmit-related offsets. Other embodiments are disclosed.

This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for demodulation reference signal (DMRS) precoding in high-Doppler scenarios. In some aspects, communicating devices may support different precodings for different portions of a signal, such as for a DMRS portion and an information portion. For example, a device may receive a signal including an orthogonal time-frequency space (OTFS) precoded first waveform portion carrying DMRS symbols and an orthogonal frequency division multiplexing (OFDM) precoded second waveform portion carrying information symbols. The device may transform the OTFS precoded DMRS symbols from a time-frequency domain to a delay-Doppler domain, may use the DMRS symbols to estimate a delay-Doppler channel, and may use the delay-Doppler channel estimate to measure an inter-carrier interference (ICI). The receiving device may use the ICI measurement to receive the information symbols carried by the OFDM precoded second waveform portion.

The present disclosure provides a frequency deviation estimation device for estimating a frequency deviation upon receiving a digitally modulated non-repetitive signal. The frequency deviation estimation device is equipped with an instantaneous frequency measurement module, a minimum frequency detection module, and a frequency deviation calculation module. The instantaneous frequency measurement module measures the instantaneous frequency of the received communication signal. The minimum frequency detection module detects the minimum frequency of the instantaneous frequency. The frequency deviation calculation module calculates the frequency deviation between the received communication signal and the reference signal for coarse adjustment using the reference minimum frequency and the minimum frequency when the frequency deviation is zero Hertz.

A control node, a wireless device, an access point and methods therein, to achieve estimation of path loss and channel response in a radio link between the wireless device and the access point. The control node assigns one and the same pilot sequence to the wireless device and at least one other wireless device in communication with the access point, and further assigns different device-specific phase rotations to the wireless devices. The devices then apply their assigned phase rotations to the pilot sequence when transmitting the pilot sequence in consecutive coherence intervals to the access point which is thereby able to de-spread the received pilot sequences and estimate path loss and channel response in the radio link.

A communication apparatus configured to contactlessly communicate a baseband signal to another communication apparatus includes a transmission unit configured to stop output of a transmission signal, which is to be transmitted to the other communication apparatus, while a reception intensity of a reception signal received from the other communication apparatus is lower than a first threshold value, and a transmission coupler configured to be coupled to a reception coupler of the other communication apparatus by electric field coupling.

Aspects of the subject disclosure may include, for example, receiving sounding reference signal (SRS) symbols from antenna elements of each of multiple modular antenna arrays, wherein the multiple modular antenna arrays are operatively combined to form a coherent antenna system, performing an uplink (UL) channel estimation and a downlink (DL) channel estimation, across a plurality of physical resource blocks (PRBs), based on the SRS symbols, calculating, for the antenna elements, a plurality of uplink (UL) combining weights based on the UL channel estimation and a plurality of downlink (DL) precoder weights based on the DL channel estimation, and causing the plurality of UL combining weights and the plurality of DL precoder weights to be applied to the antenna elements, thereby adjusting beamforming of the coherent antenna system. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, receiving a plurality of orthogonal sounding reference signals (SRS) from a plurality of user equipment (UEs), wherein each SRS of the plurality of orthogonal SRS is provided by a respective UE of the plurality of UEs, determining a downlink (DL) channel, in frequency division duplex (FDD), using spatial correlations relating to the plurality of UEs, wherein the spatial correlations are based on the plurality of orthogonal SRS, calculating a plurality of DL precoding weights for a plurality of coherent modular antenna panels responsive to the determining the DL channel, and applying the plurality of DL precoding weights to the plurality of coherent modular antenna panels to enable multi-user (Mu)-multiple-input-multiple-output (MIMO) for the plurality of UEs. Other embodiments are disclosed.