Embodiments herein relate to a method, performed by a network node, for reducing a higher layer signaling overhead in multi antenna wireless communication systems. The network node operates in a communication network, which communication network is adapted to wirelessly serve a network device via a Radio Access, RA, node. The network node obtains information from the network device, which information comprises a category of the network device and a number of layers supported by the network device. The network node determines a length of a codebook subset restriction based on the information obtained from the network device. The network node further sends a codebook subset restriction bit map to the network device, according to the determined length of the codebook subset restriction.

For CSI reporting mechanisms, a user equipment (UE) includes a transceiver and a processor operably connected to the transceiver. The transceiver is configured to receive channel state information (CSI) process configuration information including at least one beamformed type associated with a plurality of non-zero-power (NZP) CSI reference signal (CSI-RS) resource configurations and receive a CSI-RS resource index (CRI) reporting configuration. The processor is configured to calculate, in response to receipt of the configuration information, a CRI and a channel quality indicator (CQI). The transceiver is further configured to report the CRI and the CQI by transmitting the CRI and the CQI on an uplink channel.

The present application discloses a measurement method and an apparatus, so that a measurement result meets a CoMP requirement while feedback overheads are reduced. The measurement method includes: sending, by a first network device, a restricted channel state information CSI measurement instruction to a second network device, where the restricted CSI measurement instruction is used to instruct the second network device to perform restricted CSI measurement; and receiving, by the first network device, CSI sent by the second network device, where the CSI is generated after the CSI measurement is completed based on the CSI measurement instruction.

Embodiments of present invention provide a method for optimizing the rank of channel matrix, a wireless base and a mobile station. The method for optimizing the rank of channel matrix according to an embodiment of the present invention is applied to a wireless base to which multiple mobile stations are connected. The method includes: obtaining the historical state data of the multiple mobile stations; determining the optimal rank of channel matrix of a first mobile station of the multiple mobile stations according to the obtained historical state data of the multiple mobile stations; and transmitting to the first mobile station the optimal rank indicator indicating the optimal rank so as to cause the first mobile station to set its rank of channel matrix to be the optimal rank indicated by the optimal rank indicator.

An apparatus for mapping data in a wireless communication system. The apparatus includes circuitry for generating a precoding matrix for multi-antenna transmission based on a precoding matrix indicator (PMI) feedback from at least one remote receiver where the PMI indicates a choice of precoding matrix derived from a matrix multiplication of two matrices from a first code book and a second codebook. The apparatus further includes circuitry for precoding one or more layers of a data stream with the precoding matrix and transmitting the precoded layers of data stream to the remote receiver.

A method for constructing a codebook in a multiple-antenna wireless communication system and an apparatus therefor are disclosed. Specifically, constructing a codebook in a multiple-antenna wireless communication system comprises the steps of: receiving parameters for constructing a codebook from a base station; and constructing a codebook using the parameters for constructing the codebook, wherein the parameters for constructing the codebook may include a phase value () of a first code vector forming the codebook, a phase difference () between code vectors that are adjacent to one another within the codebook, and the number of bits () that is required when feeding back a code vector selected thin the codebook.

A method and apparatus for allowing a UE to transmit uplink signals using a MIMO scheme are disclosed. In order to maintain good Peak power to Average Power Ratio (PAPR) or Cubic Metric (CM) properties when the UE transmits uplink signals using the MIMO scheme, the UE uses a precoding scheme based on a precoding matrix established in a manner that one layer is transmitted to each antenna in specific rank transmission.

Methods and apparatuses for CSI reporting mechanisms are provided. A user equipment (UE) includes a transceiver and a processor operably connected to the transceiver. The transceiver is configured to receive channel state information (CSI) process configuration information including at least one beamformed type associated with a plurality of non-zero-power (NZP) CSI reference signal (CSI-RS) resource configurations and receive a CSI-RS resource index (CRI) reporting configuration. The processor is configured to calculate, in response to receipt of the configuration information, a CRI and a channel quality indicator (CQI). The transceiver is further configured to report the CRI and the CQI by transmitting the CRI and the CQI on an uplink channel.

Embodiments herein relate to a method, performed by a network node, for reducing a higher layer signaling overhead in multi antenna wireless communication systems. The network node operates in a communication network, which communication network is adapted to wirelessly serve a network device via a Radio Access, RA, node. The network node obtains information from the network device, which information comprises a category of the network device and a number of layers supported by the network device. The network node determines a length of a codebook subset restriction based on the information obtained from the network device. The network node further sends a codebook subset restriction bit map to the network device, according to the determined length of the codebook subset restriction.

Aspects of the disclosure relate to multiple-input and multiple-output (MIMO) codebook configuration for wireless downlink communications. A user equipment or a scheduled entity receives a reference signal (channel state information reference signal (CSI-RS) and transmits a CSI report based on the reference signal. The CSI report includes a rank indicator configured to indicate one or more ranks among multiple ranks corresponding to multiple antenna panels associated with the reference signal, and a precoding matrix indicator (PMI) corresponding to a codebook for the plurality of antenna panels. In some examples, a first rank of the multiple ranks is different from a second rank of the plurality of ranks. In other examples, a first antenna panel of the multiple antenna panels having a different number of antenna ports than a second antenna panel of the multiple antenna panels. Other aspects, embodiments, and features are also claimed and described.