This application provides an uplink reference signal sending method, an uplink reference signal receiving method, and a communication apparatus, to obtain an accurate measurement result of an uplink channel. The method includes: determining, according to a resource allocation rule, downlink reference signal resources corresponding to a plurality of first resources used to carry an uplink reference signal in a plurality of uplink reference signal resources, where each uplink reference signal resource includes one or more first resources; determining, based on the downlink reference signal resource corresponding to each first resource, a precoding matrix corresponding to each first resource; and then sending a precoded uplink reference signal, where the precoded uplink reference signal is obtained by precoding the uplink reference signal based on the precoding matrix corresponding to each first resource.

The described techniques provide for the use of sub-band-specific reference signal precoding. A user equipment (UE) may apply multiple precoding matrices to a reference signal to generate a set of precoded reference signals and may transmit the precoded reference signals over respective sub-bands within a given reference signal resource set. In some cases, the UE may transmit a different set of precoded reference signals in each of multiple reference signal resource sets. Upon receiving the precoded reference signals, a base station may perform wideband channel estimation for each sub-band in the given reference signal resource set. The base station may compute an average spectral efficiency for each reference signal resource set and may transmit a report to the UE. The report may include one or more communication parameters for future communications between the UE and base station.

A wireless communication system includes a first communication device and a second communication device. The first communication device includes a modulator configured to provide modulation and a first coupler configured to wirelessly transmit a signal. The second communication device includes a second coupler configured to wirelessly receive a signal by being coupled to the first coupler by at least one of electric-field coupling or magnetic-field coupling and a demodulator configured to provide demodulation. The first communication device or the second communication device includes an equalizer configured to provide equalization.

A communication device is provided that includes a baseband circuit and a transmitter configured to transmit a first signal and a projected signal. The baseband circuit is configured to determine the projected signal based on an estimated signal state information such that an energy of a shaped projected signal is smaller than an energy of a shaped signal. The estimated signal state information is an estimate of a signal state information based on the first signal and a received signal that is received by a receiver of the second communication device. The shaped projected signal is the projected signal received by the receiver of the second communication device and filtered by a filter of the second communication device. The shaped signal is the received signal filtered by the filter of the second communication device.

A user apparatus in a radio communication system including a base station and the user apparatus, including: a transmission unit configured to transmit a preamble to the base station; and a reception unit configured to monitor a response for the preamble within a predetermined time window by using predetermined identification information, wherein the reception unit calculates the predetermined identification information using a system frame number.

Systems and methods are provided for phased array passband calibration, which permits repeated calibration of the antenna system in the field without a moving far field sensor. An implementation includes an equalization filter coupled to a phased array feed; a calibration probe disposed to couple with an antenna array to transfer radio frequency (RF) energy; a database of probe-to-far-field (FF) transforms having a probe-to-FF transform for each of a plurality of incidence angles; a calibration component operable to: receive calibration probe measurements for a plurality of frequencies; and determine a calculated phased array passband response for at least a first incidence angle, based at least on the calibration probe measurements and a probe-to-FF transform for the first incidence angle; and a filter generation component operable to generate a tuning configuration for the equalization filter, based at least on the calculated phased array passband response.

Example channel measurement methods and communications apparatus are described. One example method includes receiving a precoded reference signal by a terminal device, where the precoded reference signal is obtained by precoding a reference signal based on K angle vectors and L delay vectors. First indication information is generated and sent, where the first indication information indicates P weighting coefficients corresponding to P angle-delay pairs. The P weighting coefficients are determined by using the precoded reference signal. The P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix. Each angle-delay pair includes one of the K angle vectors and one of the L delay vectors. The K angle vectors and the L delay vectors are determined based on uplink channel measurement.

Embodiments of this application provide a signal sending method, a signal receiving method, and an apparatus, to resolve a problem that channel estimation performance is affected. A reference signal is sent on one or more consecutive symbols, and modulation data is sent on an adjacent symbol previous to the one or more consecutive symbols in time domain and an adjacent symbol next to the one or more consecutive symbols in time domain. A sum of the modulation data carried in the symbol previous to the one or more consecutive symbols and the modulation data carried in the symbol next to the one or more consecutive symbols is zero or the modulation data is the same. Therefore, after time-domain filtering, the reference signal is not interfered with by the adjacent modulation data, so that channel estimation performance can be ensured.

A hybrid electrical and optic system-on-chip (SOC) device configured for both electrical and optic communication includes a substrate, an electrical device configured for electrical communication arranged on the substrate, a photonics device configured for optic communication arranged on the substrate, and a self-test module arranged on the substrate. The self-test module is configured to receive a loop-back signal indicative of an optical signal output from the photonics device and calibrate the photonics device based on the loop-back signal.

Device, methods and systems for aspects of channel estimation for orthogonal time frequency space (OTFS) modulation in wireless systems are described. In an aspect, a method for wireless communication may include receiving, using multiple receive antennas, from a number of user devices, non-orthogonal pilots wherein at least some transmissions of the non-orthogonal pilots from different user devices overlap in at least some time and frequency resources, estimating individual pilots from the number of user devices by computing a pilot separation filter for each antenna, and estimating the wireless channel at time and frequency resources used by the non-orthogonal pilots by filtering the receiving signal at the multiple receiver antennas.