Dynamic reconfiguration of CSI-RS resources for CSI reporting is described for full dimension multiple input, multiple output (FD-MIMO) systems. While a larger number of channel state information (CSI) reference signal (CSI-RS) resources with independent resource configuration are configured and associated with a CSI process, only a subset of resources that are activated by additional signaling are used for CSI measurement and reporting. The set of activated CSI-RS resources may include only a single CSI-RS resource. Both periodic and aperiodic CSI reporting may then be based on the same set of the activated CSI-RS resources. Medium access control (MAC) control elements may be used to provide activation/deactivation of the CSI-RS resources. Additionally, CSI reporting may be based on both the activated CSI-RS resources and the associated number of antenna ports.

A communication device for providing a channel state information, CSI, feedback in a wireless communication system includes a transceiver to receive a radio signal including downlink reference signals. The processor estimates an explicit CSI, selects a Doppler-delay precoder matrix for a composite Doppler-delay-beam three-stage precoder, calculates and reports to the transmitter a CSI feedback. The communication device selects from one or more codebooks a subset of D delay components and/or a subset of F Doppler-frequency components and uses the selected subset of delay components for each polarization and each spatial beam and/or the selected subset of Doppler-frequency components for each polarization, each spatial beam and each delay, when calculating the Doppler-delay precoder matrix.

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.

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 codebook subset restriction configuration can be received (410) from a network entity. A set of reference signals can be received (420) from the network entity. A set of frequency domain coefficients can be defined (430). The set of frequency domain coefficients can be an element of a discrete Fourier transform-compression codebook. The set of frequency domain coefficients can be generated (440) based on at least the restriction of the function of the amplitude restriction ratio of each beam in the set of restricted beams. At least one channel state information report containing the set of frequency domain coefficients can be transmitted (450).

A method for operating a user equipment (UE) comprises receiving configuration information about a channel state information (CSI) report, the configuration information including a number of radio remote heads (RRHs), N.sub.RRH>1; selecting a subset of RRHs from the N.sub.RRH RRHs independently for each subband (SB); determining the CSI report including an indicator indicating the selected subset of RRHs for each SB; and transmitting the CSI report including the indicator indicating the selected subset of RRHs for each SB.

A method of data transfer between a radio unit and a mobile wireless device includes obtaining a value for a measure of a location of the mobile wireless device relative to the radio unit. When the measure of the location indicates that the mobile wireless device is nearer to the radio unit than a speed-dependent threshold value, any required beam switch is made to one of a plurality of predefined wide beams for data transfer between the radio unit and the mobile wireless device. When the measure of the location indicates that the mobile wireless device is further from the radio unit than the speed-dependent threshold value, any required beam switch is made to one of a plurality of predefined narrow beams for data transfer between the radio unit and the mobile wireless device.

Enhanced channel state information (CSI) feedback is disclosed for full dimensional multiple input, multiple output (FD-MIMO) operations. In one aspect, a single CSI process is defined that is configured with an azimuth and elevation CSI-reference signal (RS) ports. A user equipment (UE) will send a precoding matrix indictor (PMI) report including a precoding matrix indicator (PMI) for the azimuth ports and a PMI for the elevation ports. One of the PMIs is assigned a low rank. The base station will use the two PMIs to create a whole channel precoding matrix. In another aspect, a single CSI process is configured having a plurality of CSI-RS resources. The UE generates channel measurement information for each of the CSI-RS resources, but only sets a CSI report to the base station of a subset of the total number of resources.

A method involving a MIMO communications system including a phased array antenna for establishing communication with a terminal located within a domain, the method including: defining a plurality of sub-domains within the domain; for each sub-domain, defining a corresponding set of analog phase weights to be applied to the phased array antenna for directing beams towards that sub-domain; in succession, selecting each sub-domain among the plurality of sub-domains and for each selected sub-domain: (a) applying the set of analog phase weights for that selected sub-domain to the phased array antenna; (b) performing channel sounding with the terminal while that sub-domain is selected; and (c) receiving feedback from the terminal for that selected sub-domain; and after selecting all sub-domains and from the received feedback, identifying a best sub-domain and identifying a best precoding matrix that in combination with the best sub-domain provides a best communication channel for the terminal.

In one aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a user equipment (UE) or a component thereof. The apparatus may be configured to receive pilot signals from a base station on a first subset of a set of antenna ports of a channel. The apparatus may be further configured to measure a first set of values corresponding to the first subset of the set of antenna ports based on receiving the pilot signals transmitted from the base station on the first subset of the set of antenna ports. The apparatus may be further configured to derive a second set of values corresponding to a second subset of the set of antenna ports of the channel based on receiving the pilot signals on the first subset of the set of antenna ports.