A method of reporting, by a user equipment (UE), channel state information (CSI) in a wireless communication system, includes: receiving, by the UE and from a base station (BS), downlink control information (DCI) related to an aperiodic CSI report that is to be performed by the UE in a slot n; determining, by the UE, a value n.sub.CQI_ref based on a number of symbols Z′ related to a time for computing the CSI; determining, by the UE, a CSI reference resource as being a slot n−n.sub.CQI_ref in a time domain that is to be used for the aperiodic CSI report; and transmitting, by the UE and to the BS, the aperiodic CSI report in the slot n, based on the CSI reference resource being slot n−n.sub.CQI_ref. The CSI may be calculated by using the most recent A CSI-RS, and thereby the most recent CSI may be reported.

Certain aspects of the present disclosure relate to a technique for communicating Channel State Information (CSI) feedback. In some aspects, the CSI feedback is communicated in a very high throughput (VHT) wireless communications system.

A transmitting node and methods therein A transmitting node and a method therein for controlling a transmission rank in a wireless communications system. The wireless communications system comprises the transmitting node and a receiving node. The transmitting node is configured to transmit on multiple antennas according to the transmission rank. The transmitting node allocates one or more first transmission resources between the transmitting node and the receiving node to operate according to a first transmission rank, and one or more second transmission resources between the transmitting node and the receiving node to operate according to a second transmission rank. When a performance of the second transmission rank outperforms a performance of the first transmission rank, the transmitting node configures at least one of the one or more first transmission resources to operate according to the second transmission rank.

WTRUs, access points (APs) and methods thereon are disclosed. A method on a WTRU may include receiving a message from an AP that comprises a beamformee capability element; sending a second message to the AP that comprises a beamformer capability element; and receiving, from the AP, a third message in response to the second message that indicates a group to which the WTRU is assigned. The group may be based on the beamformer capability element and the group may indicate UL transmission information to be used by the WTRU. A method on an AP may include determining a group for multiple WTRUs based on a received beamformer capability element. A method on a WTRU may include sending to an AP a message with a low overhead preamble for UL MU-MIMO. The low overhead preamble may include LTFs that enable the AP to distinguish the WTRU from other WTRUs.

Logic of an access point may transmit a null data packet for beamforming training and transmit a beamforming report poll to the first station on a user list before receiving a transmission from the first station on the user list. Logic may wait for a timeout period to determine whether the first station on the user list will respond to the null data packet prior to transmitting the beamforming report poll. Logic may receive from the first station an indication that the first station is a slow beamforming report responder. Logic may reorder the user list to position a fast beamforming responder as the first station. And logic of the station may determine that the station is unable to complete and transmit the report so the logic may wait to transmit the beamforming report in response to a subsequent beamforming report poll frame.

Methods, devices and computer programs for determining new transmit directions to use for beamformed transmissions in case the link quality of an existing direction falters. A transmitting communication device and a receiving communication device cooperate via a beam tracking procedure to determine a new suitable transmit direction to use for upcoming beamformed transmissions. Information relating to the beam tracking procedure is communicated over an existing link that enables communication between the transmitting and receiving communication devices. The receiving communication device provides the transmitting communication device with information about a beam scan performed in order to detect tracking beams transmitted by the transmitting communication device. This information allows the transmitting communication device to determine suitable transmit directions to use.

Provided are a method and device for low-complexity feedback in a multiuser and multipoint cooperative communication system. The base station in the multiuser and multipoint cooperative communication system transmits a feedback stop signal to a terminal in order for the terminal receiving the feedback stop signal to stop feedback for a predetermined period. The terminal receiving the feedback stop signal stops the feedback of channel information for a period indicated by the feedback stop signal.

Methods, systems, and devices for wireless communication are described. In aspects of the present disclosure, a user equipment (UE) may report metrics (e.g., received signal power, beam identifier) about synchronization signal (SS) beams using the same (e.g., or a similar) framework that is used for channel state information reference signal (CSI-RS) reporting. Because SSs are intended to be broadcast across a wide coverage area in a beamformed manner, the SSs represent a promising complement to existing beam management techniques. Accordingly, beam management may be achieved at least in part based on reporting one or more metrics of beamformed SSs through a channel feedback framework.

Methods, systems, and devices for wireless communication are described. In aspects of the present disclosure, a user equipment (UE) may report metrics (e.g., received signal power, beam identifier) about synchronization signal (SS) beams using the same (e.g., or a similar) framework that is used for channel state information reference signal (CSI-RS) reporting. Because SSs are intended to be broadcast across a wide coverage area in a beamformed manner, the SSs represent a promising complement to existing beam management techniques. Accordingly, beam management may be achieved at least in part based on reporting one or more metrics of beamformed SSs through a channel feedback framework.

Methods, apparatus and systems for performing channel measurement in a multi-beam wireless communication are disclosed. In one embodiment, a method performed by a wireless communication node is disclosed. The method comprises: transmitting a channel measurement frame based on a plurality of beams to a wireless communication device through a channel between the wireless communication node and the wireless communication device; and receiving a feedback frame from the wireless communication device. The channel measurement frame comprises a training sequence including a plurality of repetitive segments. Each of the plurality of repetitive segments is transmitted based on a respective one of the plurality of beams. The feedback frame comprises channel information of the channel with respect to at least one beam of the plurality of beams.