The present invention relates to a method for performing MU-MIMO beamforming training, the method comprising: receiving a MIMO beamforming setup frame including identification information of a station participating in MU-MIMO beamforming training, in an MU-MIMO beamforming setup subphase; receiving a BRP frame in an MU-MIMO beamforming training subphase; and performing MU-MIMO beamforming training using the BRP frame, if the identification information of the station included in the MIMO beamforming setup frame responds to the STA and a TA field and an RA field of the BRP frame are the same as a MAC address of an initiator that has transmitted the MIMO beamforming setup frame.

Certain aspects of the present disclosure provide techniques for dynamically scheduling antenna resources of a wireless node, such as, antenna panels of a user equipment (UE). In some cases, a first node (e.g., a UE) performs, with two or more other nodes, a first beam sweep procedure across two or more antenna resources of the first node on two or more wireless interfaces, generates or obtains scheduling information based on results of the first beam sweep procedure, wherein the scheduling information indicates which of the antenna resources is scheduled for which wireless interfaces, and communicates with the other nodes on the wireless interfaces according to the scheduling information.

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.

An apparatus comprises: a first plurality of first radio frequency chains; a second plurality of second radio frequency chains, the first radio frequency chains being configured to produce wider side-band emissions than the second radio frequency chains; at least one antenna array comprising antenna elements, each of a first plurality of the antenna elements being coupled with a corresponding one of the first plurality of first radio frequency chains, the first plurality of first radio frequency chains being configured to cause transmissions predominately in a first band within a channel, each of a second plurality of the antenna elements being coupled with a corresponding one of the second plurality of second radio frequency chains, the second plurality of second radio frequency chains being configured to cause transmissions predominately in at least one second band within the channel.

This disclosure describes techniques that enable individual antenna arrays of a base station node to transmit digital information via a plurality of frequency bands. More specifically, a remote radio unit (RRU) may include a first set of antenna arrays and a second set of antenna arrays. Each set of antenna arrays comprise antenna elements that are configured for use with different frequency bands. In this way, the RRU, via the first and second sets of antenna arrays, may be configured for simultaneous use with different frequency bands.

A method for transmitting a reference signal in a multi-antenna system is provided. The method includes: selecting at least one orthogonal frequency division multiplexing (OFDM) symbol in a subframe containing a plurality of OFDM symbols; allocating a channel quality indication reference signal (CQI RS) capable of measuring a channel state for each of a plurality of antennas to the selected at least one OFDM symbol; and transmitting the CQI RS, wherein the CQI RS is allocated to an OFDM symbol which does not overlap with an OFDM symbol to which a common reference signal to be transmitted to all user equipments in a cell or a dedicated reference signal to be transmitted to a specific user equipment in the cell is allocated.

Provided are communication apparatus and a communication method that allow for secure communication even in a case that an eavesdropper has multiple antennas. An apparatus includes a transmitter configured to transmit a constant amplitude signal from three or more transmit antennas; a controller configured to control a phase of the constant amplitude signal, based on channel information and a target symbol; and a modulation unit configured to generate a modulation symbol from bits. The target symbol is generated by multiplying the modulation symbol by an amplitude coefficient.

A method for selecting a geometry of an antenna array in a multiple-input multiple-output, MIMO, radio communication system (100), the method comprising; obtaining a first parameter set comprising a first communication distance D.sub.1 and a first carrier frequency f.sub.1, and a second parameter set comprising a second communication distance D.sub.2 and a second carrier frequency f.sub.2, determining a first radio communication performance measure based on the first parameter set in dependence of antenna array geometry, and a second radio communication performance measure based on the second parameter set in dependence of antenna array geometry, and selecting the antenna array geometry based on the first radio communication performance measure and on the second radio communication performance measure.

Aspects directed towards sounding reference signal (SRS) antenna switching are disclosed. In one example, an SRS configuration is received from a network in which at least four antennas of a scheduled entity are configured based on the SRS configuration. Here, the SRS configuration configures at least one antenna to simultaneously support SRS antenna switching and an uplink (UL) multiple-input multiple-output (MIMO) communication. An SRS communication is then transmitted according to the SRS configuration. In another example, a transmission capability reporting is received from a scheduled entity comprising at least four antennas. A determination is then made of whether the scheduled entity may simultaneously support SRS antenna switching and an UL MIMO communication. An SRS configuration is then generated for the scheduled entity based on the determination in which a default SRS configuration configures at least one antenna to simultaneously support the SRS antenna switching and the UL MIMO communication.

A method for communication processing includes determining a confidence level of an antenna system of a mobile device based on a measured result of the mobile device, determining a communication mode based on the confidence level, and using the communication mode for communication. The communication mode includes an antenna switching mechanism or a diversity mechanism.