Beamforming codebook optimization in a wireless communication system (WCS) is provided. In a WCS, a wireless node (e.g., base station) simultaneously emits multiple reference beams in a coverage area based on a set of codewords that is optimized for a specific number (a full or a partial set) of antenna elements in an antenna array. The wireless node is configured to determine a different set(s) of codewords that are fine-tuned for forming the reference beams from a different number of the antenna elements in the antenna array and steer the reference beams toward identical directions. During deployment of the wireless node, there may be dead zones or low coverage zones. Aspects of the present disclosure facilitate the discovery of these low-coverage zones using feedback from multiple deployed Internet of Things (IoT) devices. Based on the feedback, the codebook of codewords may be optimized to reduce or eliminate such low coverage zones. Such an approach reduces reliance on manual walk-throughs and complicated iterative processes currently in use.

A method and apparatus for precoding a reconfigurable intelligent surface (RIS) are disclosed, the method is performed by a terminal device, including: determining a precoding matrix indicator (PMI) and an additional deflection phase angle for each RIS unit group in an RIS array according to channel information of the each RIS unit group; and sending first indication information, where the first indication information indicates the precoding matrix indicator and the additional deflection phase angle for the each RIS unit group.

A precoding method is performed by a reconfigurable intelligent surface (RIS) array. The method includes: determining incident angle information, the incident angle information including incident angle information of an incident beam transmitted by a base station to the RIS array; acquiring a precoding matrix index (PMI), the PMI being determined according to channel information between the RIS array and a user equipment (UE); determining reflection angle information corresponding to the RIS array according the PMI; and determining a target deflection phase angle of each RIS array element in the RIS array according to the incident angle information and the reflection angle information, to precode the RIS array.

A method, performed by a wireless communications device, for beam training with a radio access network of a wireless communications system. The wireless communications device is configured with a first set of multiple beams for a first beam training and a second set of multiple beams for a second beam training. The second set is different from the first set, the method including: performing the first beam training with the first set of multiple beams; calculating a channel metric associated with the wireless communications device based on the performed first beam training with the first set; selecting, for the second beam training, a subset of beams of the second set based on the calculated channel metric; and performing the second beam training with the selected subset.

A mobile communication system includes a base station, a relay apparatus configured to relay a radio signal between the base station and a user equipment, and a control terminal configured to communicate with the base station and control the relay apparatus. The relay apparatus includes a plurality of elements used for beamforming. The control terminal performs, by grouping the plurality of elements into a plurality of groups, independent beam control for each of the plurality of groups. Information on the plurality of groups is communicated between the base station and the control terminal.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may transmit, to a reconfigurable intelligent surface (RIS) controller associated with an RIS, a configuration for applying an RIS pattern. The network node may receive, from a network element, a measurement report indicating received observations of pilot signals reflected by the RIS in accordance with the RIS pattern. The network node may transmit, to the RIS controller and based at least in part on the measurement report, an indication of one or more of an updated codebook or a phase drift associated with a calibration of the RIS. Numerous other aspects are described.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may transmit, to a reconfigurable intelligent surface (RIS), information identifying a RIS configuration, wherein the RIS configuration includes one or more parameters for a time-varying control configuration associated with side-lobe suppression. The network node may communicate, via the RIS and using the RIS configuration, with a user equipment (UE). Numerous other aspects are described.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a first network node may receive, from a second network node associated with a reconfigurable intelligent surface (RIS), positioning information associated with the RIS. The first network node may communicate, with a third network node, using a beam of a set of beams that is configured based at least in part on the positioning information. Numerous other aspects are described.

Disclosed is a method of a base station that supports beamforming in a wireless communication system, the method comprising the steps of: transmitting, to an RC, control information for controlling a plurality of reflective patterns of an RIS; transmitting synchronizing signals corresponding to a plurality of beams of the base station via the RIS to a terminal positioned in a shadow region, wherein the synchronizing signals are sent for each of the plurality of reflective patterns controlled on the basis of the control information; receiving, from the terminal, measurement reports containing measurement results of the intensities of the synchronizing signals corresponding to the plurality of beams of the base station, wherein the measurement reports are received for each of the plurality of reflective patterns; selecting at least one of the plurality of beams and at least one of the plurality of reflective patterns as an optimal beam and an optimal reflective pattern for the shadow region on the basis of the measurement results contained in the measurement reports; and generating a code book for the RIS on the basis of the selected optimal reflective pattern for the shadow region.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a network node may receive, from a network entity, a configuration of a codebook associated with a reconfigurable intelligent surface (RIS) pattern. The network node may receive, from the network entity, an indication of a codeword in the codebook that is potentially associated with RIS element failure based at least in part on one or more RIS attributes. The network node may perform an RIS failure mitigation based at least in part on the indication. Numerous other aspects are described.