A system for acquiring channel knowledge and a method thereof are provided. At least one transmitter generates multiple directional beams in different directions, next modulates the directional beams in the different directions by means of at least one spreading sequence, so as to enlarge the beam range of each directional beam in the different directions and use the modulated directional beams as training-specific beams in the different directions, and sweeps the training-specific beams in the different directions by means of a plurality of antennas, so that at least one receiver measures at least one training-specific beam, and determines the channel knowledge according to the measurement result and beam-related information associated with the at least one training-specific beam, so as to achieve a technical effect of reducing training overhead.

Certain aspects of the present disclosure provide techniques that may help reduce sector sweep time. In some cases, the techniques involve generating frames for transmission during a sector sweep procedure, each frame including an address field being determined based on at least one of a transmitter address of the apparatus or a receiver address of an intended recipient of the generated frames and having fewer bits than at least one of the transmitter address or the receiver address. In some cases, the techniques involve using different frame formats for initiator and responder frames transmitted during the sector sweep procedure.

Certain aspects of the present disclosure relate to methods and apparatus for implementing a data transmission scheme for Narrow-Band Internet of Things (NB-IoT). A User Equipment (UE) combines pairs of antenna ports to generate at least first and second combined antennas ports. The UE receives reference signals transmitted in a narrow band region of a larger system bandwidth, and for each combined port, adds the references signals received on resource elements (REs) of each of the combined pair of antenna ports. The UE determines channel estimates for each combined antenna port based on the added reference signals for the combined port.

For example, an Enhanced Directional Multi-Gigabit (EDMG) initiator station (STA) of a Beam Refinement Protocol (BRP) Transmit (TX) Sector Sweep (SS) (TXSS) may be configured to, during an initiator BRP TXSS, transmit one or more initiator EDMG BRP-TX packets to an EDMG responder STA; during a responder BRP TXSS following the initiator BRP TXSS, to receive one or more responder EDMG BRP-TX packets from the EDMG responder STA; and to transmit to the EDMG responder STA a BRP frame including feedback based on measurements on the one or more responder EDMG BRP-TX packets.

Presently disclosed are systems and methods for beamforming training in WLANs. In various embodiments, there are unified MIMO beamforming training procedure, which includes a training period in which an initiator transmits multiple unified training frames for performing a transmit-beamforming training of the initiator and a receive-beamforming training of one or more responders; a feedback period in which each responder replies with a beamforming-feedback response; and an acknowledgement period during which the initiator transmits respective acknowledgement frames to the one or more responders from which responses were received. Rules for restricted random access in various slots of the feedback period may be implemented, to address response contention between multiple qualifying responders.

Methods and apparatuses for multiple input-multiple output (MIMO) channel access are provided herein. A method performed by a station may include receiving, from an access point (AP), a frame including information indicating a broadcast address. The frame may further include a control trailer including information indicating that a multi-user multiple input-multiple output (MU-MIMO) frame is to be transmitted by the AP and information indicative of a designation of a plurality of STAs, the plurality of STAs including the STA. The frame may solicit response frames from at least the designated plurality of STAs. The method may further include transmitting a response frame to the indicated broadcast address and receiving the MU-MIMO frame from the AP.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station (BS), information identifying a quantity of demodulation reference signal (DMRS) sequences supported per antenna panel of the BS. The UE may transmit a DMRS communication having one or more DMRS sequences configured based at least in part on the quantity of DMRS sequences supported per antenna panel and scrambled using an extended DMRS scrambling identifier that is based at least in part on a physical random access channel preamble. Numerous other aspects are provided.

Sparse reference signal-related signaling, for a wireless channel that is associated with multiple antenna ports, is communicated with a User Equipment (UE). The sparse reference signal-related signaling is consistent with a sparse signaling pattern. In an embodiment, the sparse signaling pattern includes reference signal-related signaling associated with each of the antenna ports, and has been determined based on previous reference signal-related signaling previously communicated with the UE or another UE. In another embodiment, the sparse reference signal-related signaling is consistent with a varying sparse signaling pattern that is based on previous reference signal-related signaling previously communicated with the UE or another UE.

User Equipment (UE) and base station (eNB) apparatus and methodology for adjusting receive beamforming. A beam refinement reference signal (BRRS) is transmitted with the same transmit beam direction on which data is to be transmitted. While receiving the BRRS, the receiver varies its receive beam direction and measures a signal characteristic of reception of the BRRS to determine a refined receive beam direction. The refined receive beam direction is used to receive the data.

According to an aspect, a wireless node selects a set of reference signal antenna ports for use in transmitting data to other wireless nodes in a given transmit time interval, from a plurality of sets of reference signal antenna ports that are available for use and that include reference signal antenna ports having different reference signal densities in the frequency and/or time dimension. The wireless node sends a message to a second wireless node indicating a reference signal assignment and including an indication of the selected set of reference signal antenna ports.