An apparatus for estimating a DOA in a MIMO system includes a receiver and a signal processor. The receiver receives Rx signals from a target through Rx antennas after Tx signals having different phases are transmitted through Tx antennas, and transforms the Rx signals into time domain Rx signals. The processor transforms the time domain Rx signals into Rx signals in a frequency domain including a range-related domain and a velocity-related doppler domain; divides the doppler domain into regions according to a phase difference between the Tx signals; extracts signals from the regions; combines the signals to form first and second arrays; determines a minimum value for each of the first and second arrays using a DML algorithm; selects one of the first and second arrays having the minimum value as a true array; and estimates a DOA corresponding to the true array as an actual DOA of the target.

Methods and systems capable of launching signal-carrying transverse electromagnetic waves onto a transmission line in the higher voltage region of the transmission distribution network. Such methods and systems may include a surface wave launcher located in the higher voltage region, a network unit located in a lower voltage region, and an arrester separating the surface wave launcher and the network unit, the arrester preventing voltage from arcing over from the higher voltage region to the lower voltage region where the arrester provides the signal to the surface wave launcher.

Methods and systems capable of launching signal-carrying transverse electromagnetic waves onto a transmission line in the higher voltage region of the transmission distribution network. Such methods and systems may include a surface wave launcher located in the higher voltage region, a network unit located in a lower voltage region, and an arrester separating the surface wave launcher and the network unit, the arrester preventing voltage from arcing over from the higher voltage region to the lower voltage region where the arrester provides the signal to the surface wave launcher.

A communication device includes one or more processors, configured to receive data representing each of at least a first waveform and a second waveform from a common control channel and data representing a third waveform from a data channel associated with the control channel; determine from the received data, channel state information for each of the first waveform and the second waveform; determine a Doppler shift between the channel state information for the first waveform and the channel state information for the second waveform; compare the determined Doppler shift to a predetermined Doppler shift threshold; and if the determined Doppler shift is less than the predetermined Doppler shift threshold, adjust the third received waveform by the determined Doppler shift and decode the adjusted third received waveform.

A communication device includes one or more processors, configured to receive data representing each of at least a first waveform and a second waveform from a common control channel and data representing a third waveform from a data channel associated with the control channel; determine from the received data, channel state information for each of the first waveform and the second waveform; determine a Doppler shift between the channel state information for the first waveform and the channel state information for the second waveform; compare the determined Doppler shift to a predetermined Doppler shift threshold; and if the determined Doppler shift is less than the predetermined Doppler shift threshold, adjust the third received waveform by the determined Doppler shift and decode the adjusted third received waveform.

The embodiments of the present disclosure disclose a method for determining a parameter of a reference signal, a method for transmitting a parameter of a reference signal, a terminal device and a base station. The determination method includes: obtaining a parameter of a first type of reference signal by a first signaling; and determining a parameter of a second type of reference signal according to the obtained parameter of the first type of reference signal, and the first type of reference signal and/or the second type of reference signal include at least one of: reference signal for data demodulation, reference signal for phase noise compensation, reference signal for Doppler shift compensation, or extended reference signal for data demodulation.

The embodiments of the present disclosure disclose a method for determining a parameter of a reference signal, a method for transmitting a parameter of a reference signal, a terminal device and a base station. The determination method includes: obtaining a parameter of a first type of reference signal by a first signaling; and determining a parameter of a second type of reference signal according to the obtained parameter of the first type of reference signal, and the first type of reference signal and/or the second type of reference signal include at least one of: reference signal for data demodulation, reference signal for phase noise compensation, reference signal for Doppler shift compensation, or extended reference signal for data demodulation.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may be configured to estimate a signal-to-noise ratio for each antenna port associated with a reception of one or more tracking reference signals. The UE may receive one or more of multiple single-port tracking reference signals, a single multi-port tracking reference signal, or a tracking reference signal associated with multiple power ratios. The UE may be able to estimate a channel upon receiving a demodulation reference signal. The channel estimation may be based on the reception of one or more of multiple single-port tracking reference signals, the single multi-port tracking reference signal, or the tracking reference signal associated with multiple power ratios. The UE may communicate with the base station based on estimating the channel.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may be configured to estimate a signal-to-noise ratio for each antenna port associated with a reception of one or more tracking reference signals. The UE may receive one or more of multiple single-port tracking reference signals, a single multi-port tracking reference signal, or a tracking reference signal associated with multiple power ratios. The UE may be able to estimate a channel upon receiving a demodulation reference signal. The channel estimation may be based on the reception of one or more of multiple single-port tracking reference signals, the single multi-port tracking reference signal, or the tracking reference signal associated with multiple power ratios. The UE may communicate with the base station based on estimating the channel.

This disclosure provides methods, devices and systems for pre-compensation of downlink communication based on a transmission of a request for the pre-compensation from a user equipment (UE). For example, the UE may determine an impairment at the UE that has a greater severity (a greater impact on downlink communication) or is associated with a greater amount of resources for processing relative to a remainder of a set of impairments that is experienced at the UE and the UE may transmit a request for pre-compensation of the impairment by a base station. The base station may transmit feedback to the UE indicating a confirmation of pre-compensation for the impairment by the base station or to deferment of compensation for the impairment back to the UE. If the base station acknowledges pre-compensation for the impairment, the base station may pre-compensate a downlink transmission to the UE for the impairment.