A system and a method are disclosed for noise power estimation in wireless communications. In some embodiments, the method includes: receiving a reference signal; generating a first channel estimate, based on the reference signal; calculating a first noise power estimate; calculating a corrected noise power estimate by applying a multiplicative correction based on a linear minimum mean square error filter weight to the first noise power estimate; receiving a transmission; and decoding the transmission, based on the corrected noise power estimate.

This disclosure describes systems, methods, and devices related to a trigger-based null data packet (NDP) for channel sounding system. A device may send a trigger frame to a group of station devices, the group of station devices including a first station device, the trigger frame indicating a high efficiency (HE) long training field (HE-LTF) mode and a guard interval duration. The device may identify a HE trigger-based (TB) null data packet (NDP) received from the first station device, the HE TB NDP including a first packet extension field, wherein the HE TB NDP is associated with the HE-LTF mode and the guard interval duration indicated in the trigger frame. The device may send a downlink NDP including a second packet extension field, a second HE-LTF mode, and a second guard interval duration. The device may determine channel state information based on HE TB NDP received from the first station device.

Methods, systems, and devices for wireless communications are described. A base station may identify time and frequency resources for a physical downlink shared channel (PDSCH) to be transmitted to a user equipment (UE) in a first transmission time interval (TTI). The base station may transmit configuration information for a control channel search space set in a second TTI. The second TTI may precede the first TTI. The configuration information may include an indication of an absence of a physical downlink control channel (PDCCH) transmission to send in the control channel search space set indicating the identified time and frequency resources for the PDSCH, and a set of time and frequency resources for the control channel search space set. The UE may receive the configuration information and identify the time and frequency resources allocated for the PDSCH in the second TTI, and receive the PDSCH transmission in the second TTI.

A distributed unit (DU) may include a transceiver configured to communicate with a plurality of radio units (RUs) that are configured to serve a plurality of user equipments (UEs). The DU may include a processor configured to determine RU precoding parameters for UEs served by a first RU set from the plurality of RUs based on estimated channel parameters for communication channels between the first RU set and at least one of interfering UEs served by other RUs from the plurality of RUs; to encode information indicating the determined precoding parameters for downlink transmissions to the first RU set and determine DU precoding parameters for downlink transmissions to the UEs served by the first RU set based on the determined RU precoding parameters; and/or precode communication signals based on the determined DU precoding parameters.

Apparatuses, methods, and systems are disclosed for determining a magnitude of a composite zero-forcing equalizer. One method includes measuring a first frequency response at a first antenna connector. The method includes determining a first zero-forcing equalizer for the first antenna connector as an inverse of the first frequency response. The method includes measuring a second frequency response at a second antenna connector. The method includes determining a second zero-forcing equalizer for the second antenna connector as an inverse of the second frequency response. The method includes determining a magnitude of a composite zero-forcing equalizer as a square root of a weighted combination of squares of magnitudes of the first zero-forcing equalizer and the second zero-forcing equalizer. A first weight applied for the first antenna connector is a square of a first power measured at the first antenna connector.