Certain aspects of the present disclosure relate to methods and apparatus for performing one or more over the air calibration procedures for reciprocity based uplink MIMO transmissions, for example, in new radio (NR).

A transmission control device includes a memory; and a processor connected to the memory and configured to: specify layers corresponding to a number of hops of a link generated between a plurality of transmission points each of which wirelessly transmits a signal; and allocate radio resources which are used for transmission and reception of the signal and consecutive on a time axis to transmission points belonging to adjacent layers while sequentially switching the specified layers.

A method, system, or transmitting device including at least two antennas (e.g., orthogonally polarized antennas) that derives the precoding for each of the at least two antennas. The transmission signal provided to each antenna is based on an individual precoder for each antenna that is based on the signals received by the particular antenna.

The present invention relates to an apparatus and method for transmitting through an adaptive channel using a channel state. According to one embodiment of the present invention, a method for a remote node to transmit through a channel includes the steps of: intermittently receiving a forward channel signal transmitted from a host node; estimating a reverse channel state on the basis of the received forward channel signal; and determining whether or not the estimated reverse channel state satisfies preset channel conditions, and adaptively transmitting a reverse channel signal according to the determined result.

Wireless communications systems and methods related to over-the-air uplink-downlink (UL-DL) reciprocity calibration. A central unit transmits downlink (DL) calibration reference signal (RS) and a calibration request. The central unit receives, in response to the calibration request, a first uplink (UL) calibration RS and a first DL channel estimate associated with a first transmission point (TP) and a first wireless communication device. The central unit transmits a DL coordinated multipoint (CoMP) joint transmission signal according to an uplink-downlink (UL-DL) reciprocity calibration. The UL-DL reciprocity calibration is based on at least a first UL channel estimate based on the first UL calibration RS, the first DL channel estimate, a second UL channel estimate associated with a second TP and the first wireless communication device, and a second DL channel estimate associated with the second TP and the first wireless communication device.

A wireless cellular base station (BS) transmitter transmits a downlink calibration pilot symbol. A receiver receives from a user equipment (UE) an uplink calibration pilot symbol and an effective downlink channel estimate transmitted by the UE. The effective downlink channel estimate is computed by the UE using the downlink calibration pilot symbol received from the BS. Processing devices compute an effective uplink channel estimate using the uplink calibration pilot symbol received from the UE and compute channel reciprocity calibration coefficients using the effective downlink channel estimate received from the UE and the effective uplink channel estimate computed by the BS. The BS includes multiple antennas, and the BS computes the channel reciprocity calibration coefficients for each antenna. Alternatively, the uplink channel estimate received by the BS is an inverted version of the effective downlink channel estimate, which the processing devices use for channel reciprocity compensation.

A wireless cellular base station (BS) transmitter transmits a downlink calibration pilot symbol. A receiver receives from a user equipment (UE) an uplink calibration pilot symbol and an effective downlink channel estimate transmitted by the UE. The effective downlink channel estimate is computed by the UE using the downlink calibration pilot symbol received from the BS. Processing devices compute an effective uplink channel estimate using the uplink calibration pilot symbol received from the UE and compute channel reciprocity calibration coefficients using the effective downlink channel estimate received from the UE and the effective uplink channel estimate computed by the BS. The BS includes multiple antennas, and the BS computes the channel reciprocity calibration coefficients for each antenna. Alternatively, the uplink channel estimate received by the BS is an inverted version of the effective downlink channel estimate, which the processing devices use for channel reciprocity compensation.

A first communication device receives a sounding packet that was transmitted by a second communication device over a communication channel, and performs a channel estimation on a subchannel block of the communication channel to determine steering matrix feedback information for the subchannel block. The subchannel block spans a contiguous partial bandwidth of the communication channel and does not span an entire bandwidth of the communication channel. The first communication device transmits a communication frame to the second communication device, the communication frame i) including the steering matrix feedback information for the subchannel block, and ii) not including steering matrix feedback information for the one or more other subchannel blocks of the communication channel.

Systems and techniques are disclosed to enhance the efficiency of available bandwidth between UEs and base stations. A UE transmits a sounding reference signal to the base station, which characterizes the uplink channel based on the SRS received and, using reciprocity, applies the channel characterization for the downlink channel. The base station may form the beam to the UE based on the uplink channel information obtained from the SRS. As the downlink channel changes the base station needs updated information to maintain its beamforming, meaning it needs a new SRS. Transmission of the SRS takes resources; to minimize this, the UE or the base station can determine a period during which the downlink channel will predictably remain coherent and set up a schedule for sending SRS. Alternatively, the UE or the base station can determine on demand that the channel is losing coherence and initiate an on demand SRS.

A multi-antenna apparatus for controlling transmission and reception of signals based on channel estimation includes: a signal transmitter configured to transmit a first signal using a multi-antenna; a signal receiver configured to receive a second signal using the multi-antenna based on the transmitted first signal; a signal transferrer configured to receive a third signal received from the signal transmitter and provide the third signal to the signal receiver; and a controller configured to estimate a channel state of the multi-antenna based on the second signal and the third signal obtained from the signal receiver, and control transmission and reception of signals through the multi-antenna according to the estimated channel state.