A method for a terminal for detecting data transmitted according to the multiuser superposition transmission system comprises the steps of: receiving, from a base station, downlink control information comprising information for a codeword subset selected form a non-orthogonal codebook comprising an orthogonal subset and non-orthogonal subset; estimating a channel on the basis of a reference signal symbol or reference signal pattern corresponding to the selected codebook subset; and, on the basis of the channel estimation, detecting desired data symbols on the basis of the selected codebook subset, wherein the superposed data symbols are symbols comprising data not only for the terminal but also for other terminals.

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.

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 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.

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.

Over-the-air (OTA) phase synchronization for reciprocity-based coordinated multipoint (CoMP) joint transmission is disclosed. Phase synchronization reference signals (PSRS) are transmitted within a CoMP operation that can be used to determine the phase drifts of the transmit and receive chains of the base stations. These phase drifts can then be used to obtain a relative phase drift between the uplink and downlink channels. When estimating the uplink channel from the sounding reference signals (SRS), the relative phase drift may be applied to estimate the downlink channel as well. The OTA phase synchronization may be performed with a user equipment (UE)-assisted or inter-base station procedures.

This application presents an adaptive data recovery from distorted signals (ADRDS) of original data symbols from intervals or parameters of tone signals derived from a received OFDM signal, including responding to dynamic distortions introduced to the received OFDM signal by an OFDM transmission channel. Such ADRDS is implemented by converting back the derived intervals or parameters into original data symbols corresponding to distinctive sets of the intervals or parameters which the derived intervals or parameters belong to.

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.

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 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.