Aspects of the subject disclosure may include, for example, obtaining, over an uplink (UL) using an aggregation of modular antenna arrays, a modulated signal that includes feedback transmitted by a user equipment (UE), wherein the aggregation of modular antenna arrays comprises multiple groups of antenna elements, after the obtaining the modulated signal, performing a demodulation of the modulated signal, determining demodulator constellation errors from the demodulation of the modulated signal, performing an error gradient weight adaptation responsive to the determining the demodulator constellation errors to derive revised weights for various antenna elements of the multiple groups of antenna elements, and applying the revised weights to the various antenna elements of the multiple groups of antenna elements to adjust signals received over the UL. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, receiving a plurality of orthogonal sounding reference signals (SRS) from a plurality of user equipment (UEs), wherein each SRS of the plurality of orthogonal SRS is provided by a respective UE of the plurality of UEs, determining a downlink (DL) channel, in frequency division duplex (FDD), using spatial correlations relating to the plurality of UEs, wherein the spatial correlations are based on the plurality of orthogonal SRS, calculating a plurality of DL precoding weights for a plurality of coherent modular antenna panels responsive to the determining the DL channel, and applying the plurality of DL precoding weights to the plurality of coherent modular antenna panels to enable multi-user (Mu)-multiple-input-multiple-output (MIMO) for the plurality of UEs. Other embodiments are disclosed.

A wireless communication method includes receiving, by a first wireless device during a training phase, reference tones using a first number of resource elements from a transmitter of a second wireless device, wherein the first wireless device comprises multiple receiving antennas, estimating, by the first wireless device, from the receiving the reference tones, a second order statistics of wireless channels between the multiple receiving antennas and the transmitter of the second wireless device, and performing channel estimation, during an operational phase subsequent to the training phase, using the second order statistics and reference tones received on a second number of resource elements, wherein the second number is less than the first number.

A method performed by a first radio node for estimating channels in a wireless communication network is provided. The first radio node receives a signal from a second radio node in the wireless communication network. The signal has multiple beams. For each of at least some of the multiple beams the first radio node obtains information about a beam-specific signal quality, adapts (3039 any one or more out of: channel estimation parameters and channel estimation methods related to the beam, based on the beam-specific signal quality, and estimates a channel of the beam using any one or more out of: the adapted channel estimation parameters and the channel estimation methods.

Embodiments of the present disclosure relate to a method, an apparatus and a computer readable storage medium of user selection for MU-MIMO communications. In example embodiments, a method is provided. The method comprises determining a set of candidate terminal devices; and iteratively performing the following at least once until an end condition is met: generating, based on respective channel estimations for the set of candidate terminal devices, a covariance matrix indicating interdependency among the set of candidate terminal devices; determining a minimum eigenvalue of the covariance matrix and an eigenvector corresponding to the minimum eigenvalue, the eigenvector indicating a set of measurements for interdependency among the set of candidate terminal devices; and updating the set of candidate terminal devices by removing, from the set of candidate terminal devices, a candidate terminal device associated with a maximum measurement in the set of measurements.

Disclosed is a method of estimating, by a user equipment, a reception delay time of a reference signal, the method including receiving a reference signal from a base station; setting a plurality of summation time intervals within a time interval in which the reference signal is received, and acquiring a plurality of snapshot vectors corresponding to the plurality of summation time intervals; calculating a covariance matrix based on the plurality of snapshot vectors; and estimating a reception delay time of the reference signal based on the covariance matrix.

Aspects of the subject disclosure may include, for example, causing a reference antenna element of a first set of antenna elements of a first antenna array to transmit a first signal, determining for each antenna element of a second set of antenna elements of a second antenna array, a receive-related offset, relative to the reference element, based on inter-element propagation delays between the first and second sets of elements, causing each antenna element of the second set of elements to transmit a respective second signal, based on the reference antenna element receiving the respective second signals, calculating a respective transmit-related offset for each antenna element of the second set of antenna elements relative to the reference antenna element based on the inter-element propagation delays, and performing calibration between the first antenna array and the second antenna array based on the respective receive-related and transmit-related offsets. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, obtaining information regarding an external source that might be affected by downlink (DL) transmissions emitted by an aggregation of modular antenna arrays, wherein each modular antenna array of the aggregation of modular antenna arrays comprises a set of antenna elements, resulting in multiple sets of antenna elements, and wherein the aggregation of modular antenna arrays is operated in multi-user (Mu)-multiple-input-multiple-output (MIMO) mode in which parallel transmissions are facilitated for a plurality of user equipment (UEs), determining adjustments for particular antenna elements of the multiple sets of antenna elements based on the obtaining the information, wherein the determining the adjustments is based on a probability that interference of the parallel transmissions with the external source will be mitigated, and causing the particular antenna elements to be operated based on the adjustments. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, identifying a coherence time associated with a user equipment (UE) and a coherence bandwidth associated with the UE, determining a coherence block based on the coherence time and the coherence bandwidth, determining whether the coherence block satisfies a threshold, based on a first determination that the coherence block satisfies the threshold, employing a plurality of modular antenna arrays in multi-user (Mu)-multiple-input-multiple-output (MIMO) for the UE, and, based on a second determination that the coherence block does not satisfy the threshold, employing the plurality of modular antenna arrays in single-user (Su)-MIMO for the UE. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, receiving, over an uplink (UL) via a combination of coherent modular antenna arrays, first transmissions from a first user equipment (UE) and second transmissions from a second UE, wherein the first UE and the second UE are being served by the cell in multi-user (Mu)-multiple-input-multiple-output (MIMO) mode, determining, based on the first transmissions and the second transmissions, that a probability of the second UE interfering with the first UE in the UL satisfies a particular threshold, responsive to the determining, identifying an adjustment to an UL transmit power for the first UE, and causing the first UE to implement the adjustment to the UL transmit power. Other embodiments are disclosed.