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.

Aspects of the subject disclosure may include, for example, performing a beam sweep in a downlink (DL) using 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), after the performing the beam sweep, receiving, in an uplink (UL), a passive intermodulation (PIM) response associated with a PIM source, determining adjustments for particular antenna elements of the multiple sets of antenna elements based on the PIM response, and causing the particular antenna elements to be operated based on the adjustments when facilitating the parallel transmissions for the plurality of UEs. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, obtaining spatial separability data for multiple user equipment (UEs) being served in a cell, wherein the spatial separability data relates to a correlation coefficient associated with a first UE of the multiple UEs and a second UE of the multiple UEs, identifying that the first UE is experiencing decreasing throughput, responsive to the identifying that the first UE is experiencing decreasing throughput, determining whether the correlation coefficient associated with the first UE and the second UE satisfies a correlation threshold, and, based on a first determination that the correlation coefficient satisfies the correlation threshold, causing a scheduling priority for the first UE to be increased. Other embodiments are disclosed.

Methods and apparatus for calibrating signal processing chains using cross coupling between polarizations are described. Various exemplary methods and apparatus, in accordance with the present invention, are well suited for use in communications devices using beamforming and including arrays of TX/RX front ends, e.g., a first plurality of horizontal polarization front ends and a second plurality of vertical polarization front ends.

Aspects of the subject disclosure may include, for example, determining a coherence block for each user equipment (UE) of a plurality of UEs being served by the first cell, resulting in a plurality of coherence blocks, responsive to the determining, identifying a smallest coherence block from the plurality of coherence blocks, identifying a pilot sequence length based on the smallest coherence block, determining a plurality of orthogonal pilot sequences based on the identifying the pilot sequence length, designating, from the plurality of orthogonal pilot sequences, a first group of orthogonal pilot sequences for use in the first cell, and distributing, to each neighboring cell of a plurality of neighboring cells adjacent to the first cell, a respective group of orthogonal pilot sequences from a remainder of the plurality of orthogonal pilot sequences, to prevent pilot contamination between the first cell and the plurality of neighboring cells. Other embodiments are disclosed.

Aspects of the subject disclosure may include, for example, identifying a coherence time for a user equipment (UE), identifying a coherence bandwidth for the UE, determining a coherence block based on the coherence time and the coherence bandwidth, and, based on a first determination that the coherence block satisfies a threshold, permitting the UE to transmit sounding reference signal (SRS) data over a smaller SRS bandwidth that is smaller than a default SRS bandwidth, at a lower periodicity that is lower than a default periodicity, or a combination thereof, thereby conserving power resources of the UE. Other embodiments are disclosed.

Systems and methods for detecting and protecting against phase manipulation during AoA or AoD operations are disclosed. For AoA operations, the network device receiving the constant tone extension (CTE) generates an antenna switching pattern, which may be randomly generated. The network device then receives the CTE using a plurality of antenna elements. In one embodiment, the network device compares the phase of portions of the CTE signal received that utilize the same antenna element. If the phase of these portions differs by more than a threshold, the network device detects a malicious attack and acts accordingly. In another embodiment, if the AoA algorithm cannot determine the angle of arrival, the network device detects a malicious attack and acts accordingly. For angle of departure operations, the network device that transmits the CTE signal generates the antenna switching pattern and transmits it to the position engine, which performs the comparisons described above.

Antennas with integrated varactor circuits are described. The antenna may comprise metasurface antennas. In some embodiments, an antenna comprises an array of antenna elements, wherein each antenna element comprises a iris and a varactor diode integrated on an integrated circuit (IC) chip coupled across a portion of the iris. The antenna can also comprise a plurality of transistors, each transistor coupled to a distinct one of the varactor diodes in the array of antenna elements to provide a tuning voltage to the one varactor diode.

An embodiment method for signal path measurement includes providing a first signal at a common node coupled to a plurality of signal paths that each includes a respective phase rotation circuit. The method also includes providing a second signal, over a first test path, to a first node coupled to a first signal path of the plurality of signal paths, providing the second signal, over a second test path, to a second node coupled to a second signal path of the plurality of signal paths, selecting a signal path from the plurality of signal paths, transmitting, over the selected signal path, one of the first signal and the second signal, and mixing the first signal with the second signal to obtain a measurement signal of the selected signal path. A difference in phase delay between the second test path and the first test path includes a first known phase delay.

Example embodiments relate to 3D phased array-antenna systems and devices. A system may include a 3D structure with its center located at an origin of a reference coordinate system that includes an X-axis, a Y-axis, and a Z-axis extending from the origin of the reference coordinate system. The system may also include antenna arrays that have antenna elements configured to operate via electronic steering. The antenna arrays can be coupled to the 3D structure such that electronically steering antenna elements of the antenna arrays enables the antenna elements to transmit and receive electromagnetic signals simultaneously in numerous directions relative to the X-axis, the Y-axis, and the Z-axis of the reference coordinate system. The system may be used in various applications, including data transmission and reception, radar, and broadband signaling.