Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit an indication of support for selectively using transmission diversity for communicating. The UE may transmit one or more communications selectively using transmission diversity. Numerous other aspects are described.

A method, in a telecommunications system, for transmitting radio signals from a base station comprising at least a pair of transmission branches configured to supply output signals for respective antennae of the base station, to at least one terminal comprising at least one antenna, the method comprising splitting a signal for transmission into at least first and second components, applying a phase shift to the first component to generate a modified first component and providing the modified first component and the second component to respective power amplifiers for transmission over the antennae.

A transmission device that improves data reception quality includes: a first pilot inserter that inserts a pilot signal into a first precoded signal; a phase changer that applies a phase change of i×Δλ to the second precoded signal, where i is a symbol number and an integer that is greater than or equal to 0; an inserter that inserts a pilot signal into the second precoded signal applied with the phase change; and a phase changer that applies a phase change to the second precoded signal applied with the phase change and inserted with the pilot signal. Δλ satisfies π/2 radians<Δλ<π radians or π radians<Δλ<3π/2 radians. When the communications scheme is an OFDM scheme, the phase changer and the phase changer apply a phase change, and when the communications scheme is a single-carrier scheme, do not apply a phase change.

A precoding process is performed on a first baseband signal and a second baseband signal to generate a first precoding signal and a second precoding signal. A pilot signal is inserted into the first precoding signal and phase change is performed on the second precoding signal. A pilot signal is inserted into the phase changed second precoding signal, and phase change is further performed on the phase-changed second precoding signal with the pilot signal inserted.

Apparatuses, methods, and systems are disclosed for transmitting signals with delays. One method includes determining, at a user equipment, a first transmit signal based on a set of modulation symbols. The method includes determining a second transmit signal based on the first transmit signal, wherein the second transmit signal is a delayed copy of the first transmit signal that is delayed by a delay, and the delay is less than a maximum value. The method includes transmitting the first transmit signal from a first antenna of the user equipment. The method includes transmitting the second transmit signal from a second antenna of the user equipment.

Methods, systems, and devices for wireless communications are described. A first device may transmit, from a first antenna of a first antenna array of the first device to a second antenna of a second antenna array of a second device, a first set of reference signals. The first device may transmit, from a first plurality of antennas of the first antenna array to a second plurality of antennas of the second antenna array, a second plurality of reference signals. The first device may receive, from the second device, an indication based at least in part on a linear offset and one or more rotational offsets estimated by the second device associated with the first set of reference signals and the second plurality of reference signals. The first device may communicate with the second device using the first antenna array based on the indication.

Systems and methods for extracting polarized sub-signals from a dual-polarized signal includes isolating the polarized sub-signals using one or more filters. When a single filter is used to derive a first sub-signal, analog interference cancellation may be used to derive the second sub-signal. When two filters are used, the first and second sub-signals may each be derived using a corresponding filter.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit, to a base station, an indication of whether the UE is capable of using a virtual port to transmit uplink communications using a maximum transmit power according to a power class of the UE, wherein the virtual port is a combination of two or more antenna ports. The UE may receive, from the base station, a sounding reference signal configuration based at least in part on the indication. Numerous other aspects are provided.

Systems and methods for operating a phased array are described. In an example, a system may convert a desired beam direction of a desired beam into at least one phase slope parameter. The phased array may include a plurality of antennas connected to a plurality of front-end circuits of a beam forming circuit, and each antenna may be connected to a respective front-end circuit. For each antenna among the plurality of antennas, the system may determine a phase shift parameter of the antenna based on the at least one phase slope parameter and a physical location of the antenna. For each antenna among the plurality of antennas, the system may map the determined phase shift parameter of the antenna to control settings for a front-end circuit connected to the antenna.

Disclosed is a method for supporting uplink multiple-input and multiple-output (MIMO) in a wireless communication system. A method for transmitting data according to the present invention comprises the steps of: mapping, to first orthogonal frequency division multiplexing (OFDM) symbols within a subframe, first demodulation reference signals (DMRSs) corresponding to a first antenna port and a second DMRSs corresponding to a second antenna port; mapping, to second OFDM symbols except the first OFDM symbols within the subframe, first data corresponding to the first antenna port and second data corresponding to the second antenna port; and transmitting the subframe by using resources allocated to the uplink, wherein predetermined precodings are applied to the first data and the second data, and the predetermined precodings may be changed according to the index of the second OFDM symbols.