A wireless device, a network node and methods are disclosed. According to one aspect, a method includes receiving an indication of a maximum power level associated with a spatial-domain basis vector. The method includes determining whether a combination of values of the plurality of amplitude coefficients results in exceeding the maximum power level. The method further includes, responsive to determining that a combination of values of the plurality of amplitude coefficients results in exceeding the maximum power level, not reporting the combination of values in a channel state information, CSI, report.

A method and apparatus of transmitting a reference signal in a wireless communication system is provided. The method includes generating a precoded reference signal or a non-precoded reference signal in accordance with a rank, and transmitting the generated reference signal. Uplink transmission using multiple transmit antennas is supported through reference signal design and related control signaling.

A first communication device transmits a plurality of training signals to a second communication device via a communication channel The first communication device receives feedback generated at the second communication device based on the plurality of training signals. The feedback includes steering matrix information for a plurality of orthogonal frequency division multiplexing (OFDM) tones and (ii) additional phase information corresponding to channel estimates obtained for the plurality of OFDM tone. The first communication device constructs, based on the steering matrix information, a plurality of steering matrices corresponding to the plurality of OFDM tones, and compensates, using the additional phase information, the plurality of steering matrices to reduce phase discontinuities between the OFDM tones. The first communication device steers, using the compensated steering matrices, at least one transmission via the communication channel to the second communication device.

Provided are a method and device for acquiring grouping indication information. The method for acquiring grouping indication information includes: acquiring second-type grouping indication information, wherein the second-type grouping indication information comprises grouping manner indication information and information on resources in a group; determining a transmission parameter of a reference signal corresponding to the second-type grouping indication information according to the second-type grouping indication information; and transmitting the reference signal according to the transmission parameter; wherein a resource of the resources in the group comprises a transmission port resource, a transmission frequency domain resource, a transmission sequence resource and a transmission time domain resource.

A beamformee device includes a channel estimator, first and second beamforming matrix providers and a dimension reduction unit. The channel estimator receives a NDP through a channel, and obtains channel information of the channel based on the NDP. The first beamforming matrix provider provides wideband beamforming matrices based on the channel information. The dimension reduction unit generates equivalent channel information based on the wideband beamforming matrices. The second beamforming matrix provider provides beamforming matrices based on the equivalent channel information. The wideband beamforming matrices and the subcarrier beamforming matrices are fed back to the beamformer device. Any one or any combination of the plurality of wideband beamforming matrices and the plurality of subcarrier beamforming matrices are selected from codebooks.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a channel state information reference signal that includes a plurality of resource blocks. The UE may sub-sample one or more portions of the plurality of resource blocks prior to performing one or more channel state feedback computations. Accordingly, the UE may perform the one or more channel state feedback computations based at least in part on the one or more sub-sampled portions of the plurality of resource blocks and transmit, to the base station, a channel state feedback report based at least in part on the one or more channel state feedback computations that are performed using the one or more sub-sampled portions of the plurality of resource blocks. Numerous other aspects are provided.

An apparatus implemented in an access point (AP) participates in joint soundings together with one or more other APs in a joint multi-AP (JMAP) configuration to receive joint feedbacks from a plurality of stations (STAs) responding to the joint soundings. The apparatus then performs transmissions in a coordinated multi-AP (CMAP) configuration with the one or more other APs or in a single-AP configuration with no other AP based on the joint feedbacks received while in the JMAP configuration.

Techniques are described for carrier frequency offset (CFO) and channel estimation of orthogonal frequency division multiplexing (OFDM) transmissions over multiple-input multiple-output (MIMO) frequency-selective fading channels. A wireless transmitter forms blocks of symbols by inserting training symbols within two or more blocks of information-bearing symbols. The transmitter applies a hopping code to each of the blocks of symbols to insert a null subcarrier at a different position within each of the blocks of symbols, and a modulator outputs a wireless signal in accordance with the blocks of symbols. A receiver receives the wireless signal and estimates the CFO, and outputs a stream of estimated symbols based on the estimated CFO.

A first communication device transmits a plurality of training signals to a second communication device via a communication channel. The first communication device receives feedback generated at the second communication device based on the plurality of training signals. The feedback includes steering matrix information for a plurality of orthogonal frequency division multiplexing (OFDM) tones and (ii) additional phase information corresponding to channel estimates obtained for the plurality of OFDM tone. The first communication device constructs, based on the steering matrix information, a plurality of steering matrices corresponding to the plurality of OFDM tones, and compensates, using the additional phase information, the plurality of steering matrices to reduce phase discontinuities between the OFDM tones. The first communication device steers, using the compensated steering matrices, at least one transmission via the communication channel to the second communication device.

This application discloses a precoding matrix index (PMI) reporting method, and related communications apparatus and medium. The method includes: determining an rank indicator (RI) and a PMI, where the PMI is used to determine R precoding matrices W.sub.1, . . . , W.sub.R. An r.sup.th precoding matrix W.sub.r in the R precoding matrices satisfies W.sub.r=W.sub.1×W.sub.2,r, where an l.sup.th row of W.sub.2,r is obtained by performing DFT transform on an l.sup.th row of a matrix V.sub.2,r, and R is indicated by the RI. The PMI includes first indication information and second indication information. The first indication information includes location index information. The location index information is used to indicate K.sub.m,r element locations t.sub.r,m,1, . . . , ∈{1, . . . , T} on an m.sup.th row of V.sub.2,r. The second indication information is used to indicate K.sub.m,r complex coefficients at the element locations t.sub.r,m,1, . . . , on the m.sup.th row of V.sub.2,r. V.sub.2,r is determined based on the K.sub.m,r element locations and the K.sub.m,r complex coefficients.