Techniques for performing channel estimation in an orthogonal time, frequency and space (OTFS) communication system include receiving a wireless signal comprising a data signal portion and a pilot signal portion in which the pilot signal portion includes multiple pilot signals multiplexed together in the OTFS domain, performing two-dimensional channel estimation in a time-frequency domain based on a minimum mean square error (MMSE) optimization criterion, and recovering information bits using a channel estimate obtained from the two-dimensional channel estimation.

A system includes a base band unit pooling component that determines, via a base band unit pool of base station devices, respective uplink channel estimates of an uplink channel wirelessly coupling, using frequency division duplexing via respective modular antenna elements, a user equipment to the base band unit pool. A downlink channel estimation component of the system derives, based on the respective uplink channel estimates, a downlink channel estimate of a downlink channel wirelessly coupling, using the frequency division duplexing via a portion of the respective modular antenna elements corresponding to a base station device of the base band unit pool, the base station device to the user equipment. In turn, the system generates, using the downlink channel estimate, a group of downlink sector beams to be transmitted to the user equipment using the downlink channel via the portion of the respective modular antenna elements.

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.

A method implemented by a wireless transmit/receive unit (WTRU) having multiple antennas includes determining, by the WTRU, information that is associated with a baseband channel and that indicates any of measurement information and channel information, and transmitting, by the WTRU, a signal for requesting baseband beam tracking, on condition that any of: (1) the WTRU determines, according to the indicated information, that: (i) system performance is degraded in a hybrid beamforming transmission, and (ii) re-estimation of the baseband channel is part of a current link adaptation procedure, and (2) detailed baseband channel information was not part of a multiple-in multiple-out (MIMO) setup procedure.

Phase tracking when joint transmission is performed by a plurality of wireless base stations is easily implemented. The wireless base stations perform coordinated transmission to transmit to the wireless terminal in coordination with a coordinated wireless base station. The wireless base station includes a wireless control unit and a communication unit. The wireless control unit makes an agreement on a reference signal with the coordinated wireless base station that performs coordinated transmission, and generates an agreed reference signal. The communication unit transmits a signal including the reference signal to the wireless terminal in coordination with the coordinated wireless base station. The wireless terminal estimates a frequency error among the wireless base stations that perform coordinated transmission on the basis of the received reference signal.

Disclosed are a method and apparatus for transmitting and receiving a physical downlink control channel (PDCCH) in a wireless communication system. A method for receiving a PDCCH, according to an embodiment of the present disclosure, may comprise the steps of: receiving, from a base station, configuration information related to a control resource set (CORESET); and receiving, from the base station, a PDCCH within the CORESET. The configuration information may include transmission control indicator (TCI) state information related to the CORESET, the TCI state information may include information about one or more reference signals which are in a quasi-co-location (QCL) relationship with one or more antenna ports of a demodulation reference signal (DMRS) of the PDCCH, and a plurality of TCI states may be configured for the CORESET.

In response to an instruction received from a base station, a signal forwarding device applies a signal forwarding scheme selected from a plurality of signaling forwarding schemes by a scheduler. The signal forwarding scheme may be applied by the signal forwarding device to forward signals from the base station to a user equipment (UE) device and/or from the UE device to the base station. The scheduler selects the signal forwarding scheme based on channel characteristics of the channel between the signal forwarding device and the UE device and/or the channel between the signal forwarding device and the base station. Although at least some of the channel characteristics are determined by the base station, at least some of the channel characteristics can be determined by the signal forwarding device in some situations.

The disclosed embodiments include multi-channel communications filters, multi-channel communications systems, apparatuses that utilize a tunable multi-channel communications filter for antenna tuning, and methods to perform multi-channel communications filter tuning. A multi-channel communications filter includes a coupled inductor having a primary winding that is coupled to a power source, and magnetically coupled to one or more secondary windings. The multi-channel communications filter also includes a tuning bank formed from a first set of capacitors; and a first set of switches that are configured to adjust capacitance of the first set of capacitors to impede signals having a first frequency range from flowing through the multi-channel communications filter. The tuning bank and the first set of switches are coupled to the one or more secondary windings.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a wireless communication device may determine, based at least in part on two or more measurements on a channel taken at different points in time, that the channel is classified as static. The wireless communication device may perform at least one optimization based at least in part on determining that the channel is classified as static. For example, the at least one optimization may include modifying a channel state feedback procedure, reducing a periodicity associated with a measurement gap, modifying a filtering associated with measurements of the channel, reducing a threshold associated with beam switching, and/or refraining from performing at least one filtering at a radio frequency receiver of the wireless communication device. Numerous other aspects are described.

Embodiments herein relate to a method performed by a network node for handling communication in a wireless communication network. The network node selects a precoder given a channel based on output of a trained computational model, trained with approximated precoders or channel matrices mapped to preferred precoders, and transmits data over the channel using the selected precoder.