There is provided mechanisms for transmission of reference signals. A method is performed by a terminal device. The terminal device comprises at least two physical antenna ports. The method comprises obtaining channel information. The method comprises determining, for at least one given precoder in a codebook, an uplink reference signal to physical antenna port mapping based on the channel information. The method comprises transmitting uplink reference signals in the physical antenna ports according to the determined mapping.

A method of reporting a channel state from a user equipment in a wireless communication system and apparatus therefor are disclosed. The present invention includes receiving information on vertical beamforming angles of a serving node and a cooperation node from the serving node, generating the channel state information for a cooperative transmission mode using the information on the vertical beamforming angle, and reporting the channel state information to the serving node.

Methods and apparatus for orthogonal stream spatial multiplexing. In one embodiment, a method includes splitting and modulating a data stream into n MIMO RF spatial streams and coupling them to corresponding switchable polarization antenna elements controlled via orthogonal binary codes for transmission. Each transmitted stream manifests as time-varying-polarization-orthogonal to the other n−1 spatial streams. The method includes reception of the streams at their destination using corresponding antenna elements controlled by the same set of orthogonal codes. Thus, each of the n transmitted spatial streams is polarization-match-filtered, unambiguously separated and individually recovered from all the others upon reception for subsequent demodulation and MIMO spatial recombination into the original data stream. Thus, n MIMO spatial streams emanating from a common source and featuring equal amplitude and bandwidth but bearing distinct data and exhibiting mutually orthogonal time varying polarization will propagate mutually interference-free on the same frequency channel to a single destination.

Disclosed in the present application is a method by which a terminal generates channel state information for multi-antenna-based beamforming in a wireless communication system. Specifically, the method comprises the steps of: receiving a first pilot signal and a second pilot signal from a base station; selecting a first rank on the basis of the first pilot signal and selecting a second rank on the basis of the second pilot signal; setting a rank search range for a three-dimensional channel on the basis of the first rank and the second rank; and selecting a rank for the three-dimensional channel within the rank search range and a precoder corresponding to the rank for the three-dimensional channel.

Signals are received that include a channel band and an adjacent band. The channel band is demodulated to obtain recovered symbols. Cross-correlation between the recovered symbols and the adjacent band is estimated. Adjacent channel interference is estimated, using the estimated cross-correlation of the recovered symbols and the adjacent band. Upon the estimated adjacent channel interference meeting a condition, a back-off command is sent to a transmitter power amplifier.

A UE may receive, from a base station, through a set of beams a set of BRSs. The UE may measure a signal quality of each BRS of the set of BRSs, and each measured signal quality may correspond to a beam of the set of beams. In an aspect, the UE may maintain a set of candidate beam indexes corresponding to a set of best measured signal qualities of the set of BRSs. In an aspect, the UE may transmit, to the base station, information indicating at least one measured signal quality and at least one beam index from the set of maintained candidate beam indexes, and the at least one beam index may correspond to the at least one measured signal quality.

A wireless communication system non-collaborative, multiple input, multiple output (MIMO) space division multiple access (SDMA) system determines subscriber station combining and weighting vectors that yield a high average signal-to-interference plus noise ratio (SINR). Each subscriber station independently transmits information to a base station that allows the base station to determine a weight vector w.sub.i for each subscriber station using the determined combining vector of the subscriber station. The i.sup.th combining vector corresponds to a right singular vector corresponding to a maximum singular value of a channel matrix between a base station and the i.sup.th subscriber station. Each subscriber station transmits signals using a weight vector v.sub.i, which corresponds to a left singular vector corresponding to a maximum singular value of a channel matrix between the i.sup.th subscriber station and the base station. The base station uses the weight vector w.sub.i to determine the signal transmitted by the i.sup.th subscriber station.

Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a first base station may receive, from one or more aggressor base stations, a first set of reference signals associated with cross-link interference (CLI) channel measurements. The first base station may identify the second base station based on receiving a second set of reference signals from each aggressor base station from the set, where each aggressor base station transmits downlink signals that interfere with uplink signals at the first base station. The first base station may measure the first set of reference signals to obtain a CLI channel measurement and transmit a measurement report indicating the CLI channel measurements. In some examples, the first base station, the second base station, or both may perform one or more CLI mitigation procedures based on the CLI channel measurements.

A method and apparatus for beamforming in a wireless communication system are provided. The method of supporting beamforming in a wireless communication device includes detecting a direction change of the wireless communication device while communicating with a peer device. The method of supporting beamforming in a wireless communication device also includes adjusting a beam direction for communication with the peer device based on information indicating a direction change of the wireless communication device.

Embodiments of the present disclosure provide methods and apparatus for configuring channel resource. A method performed at a network node may comprise: determining (S101) a need to change radio frequency of a cell served by the network node; determining (S102) whether a configuration for channel resource to which the radio frequency to be changed has been received by a terminal device served in the cell; and transmitting (S103), to the terminal device, an indicator for the configuration for the channel resource, in response to that the configuration for the channel resource has been received by the terminal device. According to embodiments of the present disclosure, the network node may just transmit an indicator for the configuration for the channel resource, and thus the messages in the communication network needed to configure channel resource may be reduced.