A terminal and base station are disclosed where the terminal includes a receiver that receives a signal of a downlink shared channel and a processor that controls reception of a demodulation reference signal included in the downlink shared channel. The processor controls reception of a demodulation reference signal based on one of a first mapping method or a second mapping method. The first mapping method being a method in which the demodulation reference signal is mapped to a fixed symbol within a slot of the downlink shared channel, and the second mapping method being a method in which the demodulation reference signal is mapped to a top symbol of symbols for which the downlink shared channel is scheduled.

Disclosed is a sequence generation method comprising: generating a basic sequence structure including C.sub.48 having 48 tones, X.sub.6 having six tones, and X.sub.5 having five tones; selecting any one of a plurality of phase rotation factors predetermined for a bandwidth; and generating a sequence to be inputted into a preamble to be transmitted to a terminal, by using the phase rotation factor, applied in basic sequence structural units, and the basic sequence structure.

Technology for a user equipment (UE) operable to decode a resource mapping pattern of a phase tracking reference signal (PT-RS) received from a base station in a wireless network is disclosed. The UE can decode control signaling received in a downlink from the base station. The control signaling can indicate a resource mapping pattern for a PT-RS. The UE can identify the resource mapping pattern for the PT-RS based on the control signaling received from the base station. The UE can encode one or more PT-RS for transmission to the base station in an uplink in accordance with the resource mapping pattern for the PT-RS.

Technology for a user equipment (UE) operable to decode a resource mapping pattern of a phase tracking reference signal (PT-RS) received from a base station in a wireless network is disclosed. The UE can decode control signaling received in a downlink from the base station. The control signaling can indicate a resource mapping pattern for a PT-RS. The UE can identify the resource mapping pattern for the PT-RS based on the control signaling received from the base station. The UE can encode one or more PT-RS for transmission to the base station in an uplink in accordance with the resource mapping pattern for the PT-RS.

An apparatus and method are provided for Doppler estimation of a signal received over a time-varying transmission medium, the method including receiving the signal over a channel of the time-varying transmission medium; sampling a magnitude of the received signal repeatedly over time; identifying unidirectional threshold crossings of the sampled magnitude about a threshold magnitude relative to a mean magnitude; measuring differences between the sampled magnitude and the threshold magnitude for the identified crossings; analyzing the measured differences over time; estimating the time-varying nature of the channel based on the analyzed differences; and transmitting a signal indicative of the estimated time-varying nature.

A terminal and base station are disclosed where the terminal includes a receiver that receives a signal of a downlink shared channel and a processor that controls reception of a demodulation reference signal included in the downlink shared channel. The processor controls reception of a demodulation reference signal based on one of a first mapping method or a second mapping method. The first mapping method being a method in which the demodulation reference signal is mapped to a fixed symbol within a slot of the downlink shared channel, and the second mapping method being a method in which the demodulation reference signal is mapped to a top symbol of symbols for which the downlink shared channel is scheduled.

A wireless apparatus is disclosed for adapting a modulation scheme used with backscatter signaling. In an example aspect, the wireless apparatus includes a transceiver assembly, coupling analysis circuitry, modulation determination circuitry, and modulation application circuitry. In operation, the transceiver assembly receives a power transmission from another wireless apparatus via an inductive coupling link. The coupling analysis circuitry determines an inductive coupling quality associated with the inductive coupling link extending between the wireless apparatus and the other wireless apparatus. The modulation determination circuitry determines a modulation scheme based on the inductive coupling quality. The modulation application circuitry adjusts an impedance of the wireless apparatus in accordance with the determined modulation scheme. The transceiver assembly reflects a backscatter signal across the inductive coupling link using the power transmission and based on the impedance as adjusted in accordance with the determined modulation scheme.

Embodiments of the present invention provide a signal transmission method and apparatus, which can implement fast initial time synchronization. The method includes: generating, by a transmit-end device, an initial short training sequence, where the initial short training sequence includes M sub-sequences b, and the sub-sequence b includes N transmission sampling points; determining a quantity of reception sampling points used by a receive-end device when the receive-end device performs autocorrelation processing; generating a symbol sequence according to the quantity of the reception sampling points, and generating a target short training sequence according to the symbol sequence and the initial short training sequence; and sending a target signal to the receive-end device, where a short training sequence field of the target signal carries a short training sequence symbol, and the short training sequence symbol is used to indicate the target short training sequence.

Methods, systems, devices, and apparatuses are described for phase noise estimation. A transmitting device identifies a phase noise metric associated with a receiving device. The phase noise metric provides an indication of the expected phase noise for the receiving device. The transmitting device selects a plurality of pilot tones adjacent to each other and a plurality of null tones for a transmission to the receiving device based on the phase noise metric. The plurality of null tones may be adjacent to and on both sides of the pilot tones in the frequency domain. The transmitting device identifies its own phase noise metric and select the pilot tones adjacent to each other and plurality of null tones in further consideration of its own phase noise metric. The receiving device may use the pilot tones and plurality of adjacent null tones to determine a phase noise estimation for the transmission.

A method is provided for transmitting a signal from a transmitting end to a receiving end in a wireless communication system. A preamble and the signal are transmitted. A length of the preamble is determined based on a bandwidth of the wireless communication system. The preamble is used for an automatic gain control of the signal. The preamble is transmitted in either a first symbol or a last symbol included in at least one subframe having the signal transmitted therein. A prescribed sample of either the first symbol or the last symbol is nulled by the receiving end and wherein the prescribed sample is included in a guard interval.