The present disclosure provides a method of generating codebook in a wireless communication system with multiple antenna arrays, as well as a wireless communication system, base station and terminal using the codebook for communication. The method comprises steps of: providing a basic codebook which contains multiple pre-coding matrices; and assigning phase offsets to certain pre-coding matrices in the basic codebook to form a codebook with phase offset. The feedback overhead from a client to a base station side is reduced and a good precision of feedback for multi-antenna array is kept by applying the method of generating codebook and using the generated codebook in the wireless communication system, base station and terminal.

A communication method includes receiving first signaling. The first signaling indicates a first reference signal resource. The first reference signal resource corresponds to P antenna ports. The method also includes receiving first indication information. The method further includes determining, by a processor, based on the first indication information, Q antenna ports that are in the P antenna ports and that are used to determine channel state information (CSI). Both P and Q are positive integers and P>Q.

A method for providing feedback about a MIMO channel between a transmitter and a receiver in a wireless communication system includes receiving a radio signal which includes one or more reference signals according to at least one reference signal configuration known at the receiver and indicating one or more antenna ports associated with the reference signals; estimating the MIMO channel based on measurements on the reference signals; determining a precoding vector or matrix based on the estimated MIMO channel, on one or more vectors or one or more combinations of vectors from at least one port-selection codebook and on a set of precoding coefficients, the port-selection codebook including vectors, each vector being associated with one of the antenna ports and having a single element which is one and the remaining elements being zeros; and reporting, a feedback to the transmitter which indicates the determined precoding vector or matrix.

A network node signals to a wireless communication device which precoders in a codebook are restricted from being used. The network node in this regard generates codebook subset restriction signaling that, for each of one or more groups of precoders, jointly restricts the precoders in the group by restricting a certain component (e.g., a certain beam precoder) that the precoders in the group have in common. This signaling may be for instance rank-agnostic signaling that jointly restricts the precoders in a group without regard to the precoders' transmission rank. Regardless, the network node sends the generated signaling to the wireless communication device.

A method for operating a user equipment (UE) comprises receiving information about a channel state information (CSI) report; determining, based on the information, the CSI report including amplitude indicators and phase indicators of a total of K.sup.NZ coefficients; determining, based on a condition, whether a bitmap indicator is included in the CSI report, where the bitmap indicator identifies indices of the K.sup.NZ coefficients; and transmitting the CSI report which includes the bitmap indicator when the condition is not satisfied.

A method performed by a base station of enabling a User Equipment (UE) to determine a precoder codebook in a wireless communication system is provided. The base station transmits, to the UE, information regarding precoder parameters enabling the UE to determine the precoder codebook. The precoder parameters are associated with a plurality of antenna ports of the base station. The precoder parameters relate to a first dimension and a second dimension of the precoder codebook. The plurality of antenna ports comprises a number of antenna ports that is a function of a number of antenna ports in the first dimension, and a number of antenna ports in the second dimension.

A network node, wireless device and methods for co-phasing for beamforming using co-phasing matrices for wireless communications are provided. In one example, a network node for co-phasing in beamforming for transmissions is provided. The network node includes processing circuitry including a processor and a memory where the memory contains instructions executable by the processor to configure the network node to: obtain co-phasing information associated with a wireless device, generate at least two co-phasing matrices based on the co-phasing information, and apply the at least two co-phasing matrices to at least two resource structures.

A configuration for providing a UE null space report to optimize beam management for multi-UE communication. The apparatus transmits, to the base station, a null space report indicating one or more parameters for at least one null space of the UE based on the multiple antenna elements. The apparatus receives, from the base station, a downlink signal based on the null space report of the UE.

A method includes receiving (402) a plurality of reference signals (301-303) at an antenna port of a communication device (101). Each reference signal (301-303) is sent using a corresponding precoder. The precoder is selected from a first set of precoders. The method further includes determining (403) a channel estimate based on the received plurality of reference signals (301-303), and selecting (404) a precoder from a second set of precoders based on the determined channel estimate. The second set of precoders comprises at least one precoder in addition to the precoders of the first set of precoders. The method includes sending (405) an indication (304) relating to the selected precoder.

Apparatus and methods are provided for port selection codebook configuration. A user equipment (UE) may decode a channel state information (CSI) report configuration (CSI-ReportConfig) from a base station. The CSI-ReportConfig configuring a port selection codebook comprising a port selection matrix W.sub.1, a combinational coefficient matrix W.sub.2, and a frequency basis selection matrix W.sub.f. Based on the CSI-ReportConfig, the determines, for the port selection matrix W.sub.1, up to L CSI reference signal (CSI-RS) ports out of P CSI-RS ports configured for measuring and reporting CSI. For the frequency basis selection matrix W.sub.f, the UE determines up to Mv frequency basis out of N frequency basis. For the combinational coefficient matrix W.sub.2, the UE determines up to L*Mv entries per layer. The UE reports one or more of the port selection matrix W.sub.1, the combinational coefficient matrix W.sub.2, and the frequency basis selection matrix W.sub.f to the base station.