Abstract: A reception-side apparatus includes: M receive antennas; and a processor configured to execute a first process of acquiring a first signal received from a first transmission-side apparatus from among signals simultaneously received from the N transmission-side apparatuses by receive diversity processing, and acquiring first data by demodulating and decoding the first signal. In the case of N>M, the processor acquires, for each of all patterns of a combination of a first signal, second signals from M?1 transmission-side apparatuses which are to be cancelled by receive diversity processing and third signals from N?M transmission-side apparatuses which are not to be cancelled by the receive diversity processing, a power ratio of power of the first signal relative to total power of the second and third signals based on a predetermined weight and a channel estimate of each signal, and selects a combination with the largest power ratio from among all the patterns.

Abstract: A user equipment (UE) may transmit, to a network node, an indication of support for a decoder success prediction capability. The network node may obtain the indication of support by the UE for the decoder success prediction probability. The network node may output a transmission for the UE including one or more parameters based on the indication of support by the UE for the decoder success prediction capability. The UE may receive the transmission including one or more code blocks based on the indication of support for the decoder success prediction capability. The network node may optimize a multiple incremental redundancy scheme (MIRS) schedule for at least one of transmitting the transmission or retransmitting the transmission based on the indication of support by the UE for the decoder success prediction capability. The transmission may include the MIRS schedule.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a wireless device, information indicating an amplitude control capability of the UE. The UE may receive, from the wireless device, a communication using amplitude control. Numerous other aspects are described.

Abstract: In an aspect, the present disclosure includes a method, apparatus, and computer readable medium for wireless communications at a user equipment (UE) for measuring one or more synchronization signal block (SSB) beams from a network entity; selecting a highest rated SSB beam from the one or more SSB beams based on one or more selection factors; transmitting, to the network entity, a beam report including an identification of the highest rated SSB beam; initiating a timer in response to transmitting the beam report; determining whether a media access control (MAC) control element (CE) is received from the network entity before expiration of the timer; and performing beam switching from a current SSB beam to the highest rated SSB beam based on a determination that the MAC CE is not received from the network entity before expiration of the timer.

Abstract: A method and apparatus comprises acquiring set of input streams associated with a spatial layer configured for a terminal device, and estimating a channel vector h representing a radio channel response associated with the spatial layer. An interference covariance matrix R representing power of interference is computed from at least one other spatial layer in the set of input streams and correlation of the interference within the set of input streams of the spatial layer. A per-layer interference rejection is performed, combining equalization on the set of input streams, comprising: a) estimating x=R?1h as a combination of a set of linear equations, wherein the number of linear equations is defined by an input parameter to be equal to or smaller than dimensions of the interference covariance matrix; and b) computing an estimate of a transmitted symbol on the basis of the channel vector and the estimated x.

Abstract: Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may establish a communication link using a first serving beam on a secondary component carrier (SCC). The UE may identify a link failure associated with the first serving beam. The UE may transmit an out-of-range indication associated with the first serving beam in association with the link failure. The UE may report measurement information for one or more candidate serving beams. The UE may receive an indication of a second serving beam from the one or more candidate serving beams. The UE may switch to the second serving beam for the SCC. Numerous other aspects are described.

Abstract: An antenna system for a moving vehicle, the antenna system comprising: a main antenna to generate a main beam; a measurement antenna to generate a measurement beam; and control circuitry to perform an adjustment process by: rotating the main beam to an initial bearing angle; rotating the measurement beam independently of the main beam to receive signals at positions to either side of the initial bearing angle; comparing at least one metric measured for the signals received by the measurement antenna at the positions to either side of the initial bearing angle to generate a comparison output; and determining, based on the comparison output, a correction to be applied to the initial bearing angle of the main beam.

Abstract: Some aspects relate to apparatuses and methods for selecting a receiving beam based on hybrid channel based beamforming and codebook based beamforming. A user equipment (UE) can determine, based on a first measurement related to signal to noise ratio (SNR) and predetermined threshold values, whether the UE is in a low SNR state. If the UE is in a low SRN state, the UE can derive an estimated channel covariance matrix RCH for channels at a set of antenna elements of the UE based on channel based beamforming (CHBF). Afterwards, a set of test beams {0, . . . Ntest?1} is selected based on the channel covariance matrix RCH, and a set of codebook measurement beams is further selected based on the set of test beams. A receiving beam is selected based on a set of measurements performed on the set of codebook measurement beams at the measurement opportunity for codebook based beamforming (CBBF).

Abstract: A method includes generating a preamble for a protocol version of a wireless local area network, where the preamble includes a legacy signal (L-SIG) field and a high efficiency signal (HE-SIG) field that are arranged in order, the HE-SIG field includes a first orthogonal frequency division multiplexing (OFDM) symbol and a second OFDM symbol that are arranged in order, and an input information bit of the first OFDM symbol is the same as that of the second OFDM symbol, and sending the preamble to a receive end device, so that the receive end device restores the preamble, and when determining that input information bits obtained after restoring the first OFDM symbol and the second OFDM symbol are the same, determines that the preamble is the preamble of the protocol version.

Abstract: All data symbols used in data transmission of a modulated signal are precoded by switching 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 along the frequency axis and the time axis all differ. A modulated signal with such data symbols arranged therein is transmitted.

Abstract: The present disclosure relates to transmitting and receiving beam information in a wireless communication system. An operation of a receiving end includes: generating a signal indicating two or more analogue transmission beams which are allocable to the receiving end; and transmitting the signal. In addition, the present disclosure includes other embodiments different from the embodiment described above.

Abstract: A communication apparatus performs communication while suppressing an increase in power consumption. The communication apparatus includes a periodic signal generating unit, a clocking unit, a multiplication unit, and a communication processing unit. The periodic signal generating unit generates a predetermined periodic signal. The clocking unit clocks time in synchronization with the predetermined periodic signal generated by a frequency signal generating unit. The multiplication unit multiplies the predetermined periodic signal generated by the frequency signal generating unit to supply the signal as a multiplied signal. The communication processing unit performs predetermined communication processing in synchronization with the multiplied signal generated by the multiplication unit.

Abstract: Apparatus comprising a plurality of antenna devices and a feeding device, wherein said feeding device is configured to receive a first input signal, to generate a plurality of first output signals by power dividing said first input signal, and to provide said plurality of first output signals to said plurality of antenna devices, wherein two or more of said antenna devices comprise a first antenna element for receiving at least a portion of said plurality of first output signals as a second input signal, a signal processing device configured to determine a second output signal depending on said second input signal by at least temporarily modifying a phase and/or an amplitude of said second input signal or a signal derived from said second input signal, and a second antenna element, wherein said signal processing device is configured to provide said second output signal to said second antenna element.

Abstract: An input receives a radio frequency (RF) signal having an interfering component superimposed thereon. The RF signal is mixed with a local oscillator (LO) signal and down-converted to an intermediate frequency (IF) to generate a mixed signal which includes a frequency down-converted interfering component. The mixed signal is amplified by an amplifier to generate an output signal. A feedback loop processes the output signal to generate a correction signal for cancelling the frequency down-converted interfering component at the input of the amplifier. The feedback loop includes a low-pass filter and a amplification circuit which outputs the correction signal.

Abstract: An encoding circuit includes an allocator configured to allocate symbols among a plurality of symbols within a constellation of multilevel modulation and correspond to values of a plurality of bit stings, a converter configured to convert values of each of bit strings excluding a first bit string so that, as a region within the constellation is closer to the center of the constellation, the number of symbols allocated in the region is larger, a switch configured to switch between a first time period in which a first error correction code is inserted and a second time period in which the first error correction code is not inserted, and an insertor configured to generate the first error correction code from a second bit string in the second time period and inserts the first error correction code in two or more bit strings in the first time period according to the switching.

Abstract: Embodiments disclosed herein relate to transition of a radio frequency module between a first operating state and a second operating state. The first and second states may be passive/slow (e.g., non-active) states or active/fast states. A passive state may include a sleep state, an idle state, an off state, or a low power state. An active state may include a receiving state or a transmitting state, for receiving and transmitting signals, respectively. If the first operating state is an active state and the second operating state is a passive state, the transition from the first operating state may be delayed such that the radio frequency module transitions directly from the first operating state to a third operating state. This enables the radio frequency module to avoid entering a passive second state with a slow settling time which can interfere with communications and operation of the radio frequency module.

Abstract: A method of performing a diagnostic test on a vehicle having at least one tire includes providing the vehicle with at least one sensor configured to detect a vehicle operating characteristic, a receiver configured to receive AM signals, a notification system, and a controller in electronic communication with the at least one sensor, the receiver, and the notification system, receiving sensor data from the at least one sensor and AM signal data from the receiver, analyzing the sensor data and the AM signal data, determining whether a first condition is satisfied, and in response to the first condition being satisfied, generating a first control signal to control the notification system to generate a notification.

Abstract: Systems and methods for detecting, identifying, and locating a source of radio frequency (RF) interference are discussed herein. An interference signal can prevent a user equipment (e.g., mobile phone, smartphone, or the like) from receiving a network signal altogether, can cause a temporary loss of the network signal, can affect the quality of the network signal received, or the like. The system allows for an interference source emitting the interference signal to be detected, identified, and located so that the signal can be powered off to clear a frequency band, thereby improving network service.

Abstract: All data symbols used in data transmission of a modulated signal are precoded by switching 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 along the frequency axis and the time axis all differ. A modulated signal with such data symbols arranged therein is transmitted.

Abstract: A method for controlling a transmit power of a terminal, and a terminal, where the method and the terminal include, working states of a first antenna and a second antenna may be monitored, and then a transmit power of the first antenna or that of the second antenna may be controlled according to a preset correspondence. Therefore, according to the method and the terminal, a transmit power of an antenna in a working state in the first antenna and the second antenna may be accurately controlled. If the transmit power is less than a standard transmit power, a Specific Absorption Rate (SAR) can be reduced.

Abstract: In some embodiments, the present invention is directed to a first mote, at least including: a first-mote directional antenna; wherein the first-mote directional antenna comprises a plurality of first antennas elements; ad hoc programmed computer processor which is configured to perform at least causing to establish a first communication link between the first mote and a second mote, based on a first direction; where the first direction corresponds to a first state of the plurality of first antennas elements; monitoring, in real time, the initial communication link data; determining, based on the initial communication link data, a second; selectively varying an antenna property operatively associated with the plurality of first antennas elements to establish a second state, corresponding to the second direction, and causing to establish a second communication link between the first mote and the second mote, based on the second state.

Abstract: This disclosure pertains to a wireless device for a Radio Access Network, the wireless device being adapted for transmitting sampling information indicating a sample determining device used by the wireless device for preparing a measurement report. The disclosure also pertains to related methods and devices.

Abstract: An MIMO training method including performing transmission sector sweeping using an initiator including a plurality of transmitting antennas, selecting a set of at least one transmission sector for each of the transmitting antennas using a responder including a plurality of receiving antennas; performing reception sector sweeping using the initiator, selecting a set of at least one reception sector for each of the plurality of receiving antennas using the responder, performing beam combination training using the initiator; and selecting a determined number of sector pairs consisting of a transmission sector and a reception sector from among the selected set of transmission sectors and the selected set of reception sectors using the responder, wherein the transmitting antennas in the selected sector pairs differ from one another, and the receiving antennas in the selected sector pairs differ from one another.

Abstract: Examples relating to techniques for wireless communications, e.g., visible light communication, VLC, are disclosed. In particular, there is disclosed a communication device for communicating with a plurality of other devices, using a wireless link. The device provides individual reference signals using a number of subcarriers or time slots in accordance to the optical clock reference and the number of transmitting devices in the set or streams to be transmitted in parallel. The device defines the position of subcarriers or of signals at the time slots in accordance to an identification number associated to an individual device within the whole set of transmitting devices or in dependence on an identification number identifying a specific stream or transmitter. The device transmits the reference signal which enables the plurality of receiving devices to identify the signal coming from the individual communication device in the whole set of devices.

Abstract: Measuring data are provided for monitoring a current-supply network, based on one or a plurality of measured electrical quantities of the current-supply network. A time signal is assigned to the measuring data. The measuring data are inspected for the occurrence of one a plurality of predetermined events. Based on determining the occurrence of predetermined event or events, corresponding event data based on the measuring data are generated. A time stamp is conferred to the event data, where the time stamp is based on a link of a synchronized clock time provided by a clock and the time signal assigned to the measuring data. User data are generated from the event data comprising the time stamp, and transmitted via a communication network.

Abstract: A mobile station connected to a multi-carrier cellular communication system having a plurality of sub-carriers. The sub-carriers are classified into K frequency sub-bands, channel state information (CSI) of the frequency sub-bands is represented by matrices Wi (i=0 . . . K?1), where K is an integer greater than 1. The mobile station determines a first sub-index k1 for the K matrices W1 (i =0...K -1), and a second sub-index k2 for each one of the K matrices Wi (i=0 . . . K?1). The first sub-index k1 is common for all frequency sub-bands, and the second sub-index k2 is specific for the indexed matrix that corresponds to one frequency sub-band. The mobile station reports to a base station of the multi-carrier cellular communication system the first sub-index k1 and at least one second sub-index k2.

Abstract: A vehicle capable of providing diversity of DSRC communication using a DSRC antenna for the DSRC communication and a WiFi antenna for WiFi communication is disclosed. The vehicle includes a first antenna configured to receive a first signal; a second antenna configured to receive a second signal; and a controller configured to synthesize the first signal and the second signal and process a signal in which the first signal and the second signal are synthesized according to a first communication method, in a first mode, and to alternately perform processing of a synthesized signal, in which the first signal and the second signal are synthesized, according to the first communication method and processing of the second signal according to a second communication method, in a second mode.

Abstract: A method of communicating with a portable access device includes iteratively performing an algorithm via an access module of a vehicle. The algorithm includes a series of operations including: selecting a frequency from multiple frequencies; selecting an antenna pair from multiple possible antenna pairs, where antennas of the possible antenna pairs include antennas with different polarized axes; transmitting a packet to the portable access device via the selected antenna pair; receiving a first RSSI and a response signal from the portable access device, the first RSSI corresponds to the transmission of the packet; and measuring a second RSSI of the response signal; based on the first RSSIs and the second RSSIs. A best one of the frequencies and a best antenna pair of the possible antenna pairs are selected. One or more additional packets are transmitted using the selected best frequency and the selected best antenna pair.

Abstract: A multiplexer includes a switch that individually connects or disconnects between a common terminal and first, second, third, and fourth selection terminals, first and second matching circuits, and first, second, and third filters having different pass bands. The first selection terminal is connected to one end of the first matching circuit, the second selection terminal is connected to one end of the second matching circuit, the other end of the first matching circuit and the other end of the second matching circuit are connected to each other and to one end of the first filter, the third selection terminal is connected to one end of the second filter, and the fourth selection terminal is connected to one end of the third filter.

Abstract: The disclosed systems, structures, and methods are directed to an orbital angular momentum (OAM) receiver. The OAM receiver comprising at least three receiver antenna elements configured to receive radiated OAM-RF waves and generate antenna element output signals, a selection-antenna switch operative to receive and switch between a second receiver antenna element RX2a output and a third receiver antenna element output RX2b, a phase adjusting unit configured to adjust a phase of the output of the selection-antenna switch, a hybrid coupler configured to provide a proportional summation and difference of the two modulated signals, a switching unit configured to limit the coupler output signal to gating time-intervals during which fractional pseudo-Doppler frequency shifts occur, an orthogonal filter bank configured to generate a vector X(t) containing shifted low-frequency values associated with all of the K OAM modes, and an adaptive unit configured to facilitate separation of the OAM-RF waves.

Abstract: A phased adoption procedure is disclosed for adopting a new communication system that provides potential adopters a high degree of confidence in the reliability of the proposed communication system prior to committed adoption.

Abstract: A method for selecting a management frame antenna based on a master-slave network and an apparatus are provided. In one example method, when a preset condition is met, a signal quality collection instruction is sent by a master device to a first slave device and a second slave device, so as to receive returned signal quality information. A management frame antenna is selected for the first slave device and a management frame antenna for the second slave device according to the received signal quality information, so that the selected management frame antennas can implement signal coverage optimization in an entire area managed by the master device.

Abstract: Various communication systems may benefit from improved single carrier-based waveform techniques. An apparatus may comprise at least one memory comprising computer program code and at least one processor. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to transmit at least one indication of synchronization signal block (SSB) to a network entity. The apparatus further receives at least one bandwidth part comprising at least one SSB associated with CP-OFDM waveform and/or at least one SSB below at least one threshold peak to average ratio. The apparatus further configures at least one waveform based upon the received at least one SSB. The at least one SSB below at least one threshold PAR comprise at least one indication of PDCCH.

Abstract: In one embodiment, an interference-management system of a multi-hop wireless network may access an interference map indicating interference among a plurality of network nodes of the multi-hop wireless network. The interference-management system may determine, for a first pair of network nodes of the multi-hop wireless network, a plurality of adjustments to one or more beamforming weights associated with beamforming antennae of the first pair of network nodes to reduce interference among the network nodes of the multi-hop wireless network, wherein the plurality of adjustments correspond to a respective plurality of communication paths connecting the first pair of network nodes on the multi-hop wireless network. The interference-management system may exclude one or more adjustments from the plurality of adjustments based on a determination that the one or more adjustments correspond to one or more unsuitable communication paths, respectively.

Abstract: A transmit arrangement (100) for generating a signal pattern suitable for a localization comprises a first antenna (102) and at least one second antenna (104) spatially separated from the first antenna. A transmit apparatus (106) of the transmit arrangement (100) is configured to generate a known signal form and to transmit the known signal form by means of a transmit signal via the first and second antennas (104).

Abstract: A communication system is described where multiple communication networks are simultaneously accessible from a plurality of fixed and/or mobile communication devices. A Master and Slave hierarchy is implemented among the communication devices to improve communication properties on one or multiple networks. A network system controller is implemented to select the network with optimal communication characteristics for subsets of communication devices as well as assigning Master status to a communication device within these subsets.

Abstract: According to an aspect of the inventive concept, there is provided a master unit included in a distributed antenna system of a frequency division duplex scheme, includes: a frequency converting unit converting a frequency of a first signal received from a base station into a predetermined frequency to generate a first frequency conversion signal; a signal combining unit combining the first frequency conversion signal and a second signal received from the base station to generate a transmit signal; and a signal transmitting/receiving unit transmitting the transmit signal to a remote unit connected through a single transmission line.

Abstract: Doppler correlators are configured to receive samples of a signal sampled based on a frequency. Each Doppler correlator includes successive butterfly elements. Each butterfly element includes cross-coupled first and second branches that include a sample delay that doubles for each successive butterfly element, and a sample inversion selectively placed in one of the first and second branches to encode into the successive butterfly elements of each Doppler correlator the same code sequence. Each Doppler correlator is configured with a respective phase rotation that varies across the Doppler correlators.

Abstract: All data symbols used in data transmission of a modulated signal are precoded by switching 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 along the frequency axis and the time axis all differ. A modulated signal with such data symbols arranged therein is transmitted.

Abstract: An angle-resolving FMCW radar sensor, including multiple antenna elements in positions in a direction in which the radar sensor is angle-resolving and forming at least three transmitter arrays and at least one receiver array, and a control/evaluation device for an operating mode in which transmitter arrays periodically transmit signals whose frequency is modulated according to modulation ramps, and in which radar echoes of transmitted signals are received in by multiple antenna elements of the receiver array, and the located object angle is determined based on amplitude and/or phase relationships between radar echoes which correspond to different combinations of transmitter and receiver arrays. A measuring cycle of the radar sensor includes at least two periods in which in each case at least two combinations of transmitter and receiver arrays are alternated, and the combinations of transmitter and receiver arrays involved are different from one another for the at least two periods.

Abstract: According to an embodiment of the present invention, a method for combining reception signals of a reception device in a wireless communication system comprises the steps of: determining N (here, N is a natural number) number of symbols for performing symbol combining with respect to reception signals; symbol-combining the reception signals for L (here, L is a natural number) number of times according to the determination result; and energy-combining each group of the L number of reception signals for which the symbol combining has been performed. The present research has been performed by receiving support from “Giga KOREA project” of the Ministry of Science, ICT, and Future Planning.

Abstract: A method, an apparatus, and a computer-readable medium for wireless communication are provided. In one aspect, an apparatus is configured to determine a plurality of resource units for communication. The apparatus is configured to generate a set of pilot signals in at least one resource unit of the plurality of resource units. The apparatus is configured to transmit the generated set of pilot signals in the at least one resource unit of the plurality of resource units.

Abstract: The present disclosure relates to an antenna structure. The antenna structure includes a plurality of receiver paths that are ranked based on a preset manner to obtain a ranking order of each of the plurality of receiver paths; a plurality of antennas; and a switch disposed between the plurality of antennas and the plurality of receiver paths, wherein the switch is configured to change a connection relationship between the plurality of antennas and the plurality of receiver paths based on a signal strength of the plurality of antennas and the ranking order of the plurality of the receiver paths.

Abstract: The present disclosure discloses a data processing method, a network device, and a terminal. In this method, a transmit end combines basic modulation symbols obtained after basic modulation is performed on all layers of data, to obtain a combined symbol vector X. The transmit end maps the symbol vector X to Q resource elements to obtain a data vector S. A symbol quantity of the symbol vector X is greater than a symbol quantity of the data vector S. The symbol quantity of the data vector S is Q. Q is a positive integer. Therefore, non-orthogonal spreading and superposition transmission of a plurality of terminals can be implemented in both uplink and downlink, thereby effectively improving transmission efficiency.

Abstract: In an embodiment, a user equipment (UE) is configured to operate in accordance with different wireless personal area network (WPAN) radio access technologies (RATs). The UE prioritizes a plurality of WPAN RATs supported by the UE, and dynamically allocates a plurality of shared WPAN radios to the plurality of WPAN RATs based on the prioritization.

Abstract: A multi-antenna data transmission method, network device, terminal device, and system is suggested to effectively increase a system throughput. The method includes: sending, by a network device, downlink control signaling to a terminal device, where the downlink control signaling instructs the terminal device to feed back statistical channel parameter information, the statistical channel parameter information is determined by the terminal device according to statistical channel information, and the statistical channel information is obtained after the terminal device measures instantaneous channels many times; receiving, by the network device, the statistical channel parameter information that is determined according to the downlink control signaling and that is sent by the terminal device; and processing, by the network device, downlink data according to the statistical channel parameter information, and sending processed downlink data to the terminal device.

Abstract: A first communication device generates a first portion and a second portion of a wakeup radio (WUR) wakeup packet. The first portion of the WUR wakeup packet corresponds to a wireless local area network (WLAN) legacy preamble, and spans a first frequency bandwidth. The second portion of the WUR wakeup packet spans a second bandwidth that is less than the first bandwidth, and is configured to cause a WUR of a second communication device to cause a WLAN network interface device of the second communication device to transition from a low power state to the active state. Generating the second portion of the WUR wakeup packet includes i) generating a sync portion having a plurality of sync symbols, and ii) generating a wakeup packet body. The first communication device transmits the WUR wakeup packet.

Abstract: The power transmission apparatus includes a power transmitting unit which transmits power to a first power receiving unit in a non-contact manner, a housing which accommodates the power transmitting unit, a second power receiving unit which is disposed on a sidewall of the housing and receives the power from the power transmitting unit in a non-contact manner, and an electric load which operates with power that the second power receiving unit has received. The power transmission apparatus operates only with a leakage magnetic flux and operates of a notification such as a non-contact power supply is in progress.

Abstract: At a receiver, errors may occur in estimating phase trajectory based on PT-RS due to a window effect. In order to address the problem of such errors, a transmitter determines at least one location for inserting PT-RS samples into a sequence of a plurality of samples, wherein a first set of the samples comprises a first number of samples at a beginning of the sequence and/or a second number of samples at an end of the sequence, and wherein the at least one location for the PT-RS samples is within a second set of the plurality of samples. The apparatus inserts the PT-RS samples into the sequence based on the determined at least one location and transmits a signal based on the inserted PT-RS samples. A receiver extracts the PT-RS samples and estimates phase errors for data samples in the received transmission based on the extracted PT-RS samples.

Abstract: A method includes obtaining, by a terminal, a quantity M of beamforming vectors needing to be reported by the terminal and a first reference signal that are sent by a base station; estimating downlink channel states on N dual-polarized antenna ports based on the first reference signal; selecting m first beamforming codewords based on the downlink channel states and the quantity M of beamforming vectors needing to be reported that is sent by the base station; and feeding back the m selected first beamforming codewords and ranks of the downlink channel states to the base station.