National Instruments Corporation

University of Minnesota

Nikhil U Kundargi

Karl F Nieman

Achim Nahler

James Wesley McCoy

Ahsan Aziz

Ian C Wong

Venkata Siva Santosh Ganji

Junmo Sung

Lothar Wenzel

Ahmed H Tewfik

Michael Löhning

Amal Ekbal

Marcus Monroe

Rohit Gupta

Brooks C Prumo

A user equipment device (UE) determines a beam coherence interval metric, which is a measure of stability of a beam pair over time based on a set of beam coherence intervals measured by the UE. The beam pair comprises a receive beam of the UE and a transmit beam of a base station transmitting to the UE. A beam coherence interval comprises a time duration within which a quality of a signal received on the UE receive beam remains within one of a plurality of signal quality bins. The UE also determines a hysteresis value based on the beam coherence interval metric and uses the hysteresis value to decide to switch from an active receive beam to a different receive beam that has a signal quality higher than the active receive beam by at least the hysteresis value. Alternatively, the base station determines and sends the UE the hysteresis value.

Cellular system utilizing beam coherence interval metric

A UE determines a beam coherence interval metric that is a measure of stability of a beam pair over time based on a set of beam coherence intervals measured by the UE. The beam pair comprises a UE receive beam and a base station transmit beam. A beam coherence interval comprises a time duration within which a quality of a signal received on the UE receive beam remains within one of a plurality of signal quality bins. The UE reports the metric to the base station. The base station may update beam management resource and reporting configurations to the UE based on the metric. The UE may also use the metric to determine a hysteresis value useable by the UE to decide to switch from an active receive beam to a different receive beam having a higher signal quality by at least the hysteresis value.

A UE transmits to a BS an indication of a number of PTRS ports. The number of PTRS ports is a suggestion to the BS for allocating the indicated number of PTRS ports to the UE for transmission of PTRS from the BS to the UE to enable the UE to perform phase tracking. The method also includes allocating, by the BS, PTRS ports to the UE based on the indication of the number of PTRS ports. The indication may be included in a UCI message, MAC CE, or RRC message transmitted by the UE to the BS. The BS may map the allocated PTRS ports to DMRS ports corresponding to spatial streams transmitted by the BS. The UE may estimate CPE of each spatial stream, measure correlations of the estimated CPE among the spatial streams, and use the correlations to determine the suggested number of PTRS.

Wireless communication system that performs measurement based selection of phase tracking reference signal (PTRS) ports

A user equipment device (UE) reduces receive beam selection time. An antenna array forms receive beams to receive synchronization signal blocks (SSBs) transmitted by a base station (BS). Each SSB comprises OFDM symbols. Each SSB includes a BS-assigned index. The receive beams are switched in time such that, for each SSB, two or more of the receive beams are used to receive corresponding two or more mutually exclusive sets each having at least one but less than all of the OFDM symbols of the SSB. A processor is programmed to, for each receive beam/SSB index pair, measure a signal quality based on the at least one but less than all of the OFDM symbols of the indexed SSB received by the receive beam of the pair. The processor uses the measured signal qualities to select one of the receive beams to use to receive subsequent communications from the BS.

Efficient beam sweeping at a mobile device receiver

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.

UE-aided channel reciprocity compensation for radio access in MIMO wireless communication systems

A base station (BS)/user equipment (UE) for performing radio frequency beam management and recovery in communication with a UE/BS. The BS/UE includes a processor and a memory that stores first and second thresholds. The processor evaluates a beam quality metric against the first and second thresholds, performs beam switching and/or beam broadening in response to determining the beam quality metric falls below the first threshold, and performs a beam failure recovery procedure in response to determining the beam quality metric falls below the second threshold.

Radio frequency beam management and recovery

Techniques are disclosed relating to a massive MIMO base station architecture. In some embodiments, a base station is configured to combine signals received by multiple antennas and, for at least a subset of processing elements included in the base station, each processing element is configured to operate on a different portion of the combined signals. In these embodiments, each portion includes signals from multiple antennas. In some embodiments, the portions are different time and/or frequency portions of the combined signals. In some embodiments, this distributed processing may allow the number of antennas of the base station to scale dramatically, provide dynamic re-configurability, facilitate real-time reciprocity-based precoding, etc.

Massive MIMO architecture

A base station receives a report of channel state information (CSI) computation capability from a UE, configures the UE with X and Y values based on the reported computation capability, performs a beam sweep by transmitting direction-unique beams, and receives a beam measurement report from the UE comprising a reference signal receive power (RSRP) of Y strongest beams of the transmitted beams and at least a portion of the CSI of X strongest beams of the Y beams. Based on the beam measurement report, one of the X beams is selected to configure the UE for subsequent data and control channel transmissions. X and Y are positive integers, Y is greater than or equal to X, and Y is at least 1.

Wireless communication system that performs beam reporting based on a combination of reference signal receive power and channel state information metrics

A base station (BS) having a plurality of antennas transmits a plurality of spatial streams. Each user equipment (UE) of a plurality of UE estimates common phase error (CPE) of each of two or more of the plurality of spatial streams, measures correlations of the estimated CPE among the two or more of the plurality of spatial streams, and provides feedback about the CPE correlations to the BS. The BS uses the CPE correlation feedback to allocate phase tracking reference signal (PTRS) ports and to map the allocated PTRS ports to demodulation reference signal (DMRS) ports corresponding to the plurality of spatial streams.

A base station radio transceiver transceives beams with a UE. In a first beam set of wide beam reference signals (RS), each wide beam RS direction is unique, and in a second beam set of narrow beam RS, each narrow beam RS direction is unique and the width of the narrow beam RS is narrower than the width of the wide beam RS. A linkage uniquely links each narrow beam RS to a wide beam RS. The direction of each narrow beam RS is spatially nested within the width of the wide beam RS to which it is uniquely linked. A processor uses the first and second beam sets in a beam management process in which one of the narrow beam RS is selected for the UE and the wide beam RS uniquely linked to the selected narrow beam RS is selected for the UE according to the linkage.

Wireless communication system that performs beam management using nested reference signals

A processor in a UE evaluates a radio frequency beam quality metric against a threshold, switches from a first beam to a second beam in response to determining the metric falls below the threshold, and transmits to a base station (BS) a report that includes beam measurements. The report indicates the UE has performed the switching and that the beam measurements are with respect to the second beam. A processor in a UE/BS associates narrower and broader beams, uses the narrower beam, rather than the broader beam, to transfer user data between the BS and the UE, evaluates a beam quality metric of the narrower beam against the threshold, and switches to using the broader beam, rather than the narrower beam, to transfer user data between the BS and the UE in response to determining the beam quality metric of the narrower beam falls below the threshold.

Radio frequency beam management and failure pre-emption

A wireless device receives a frequency division multiplexed (FDM) symbol of constituent equalized FDM data subcarriers. A modulation scheme constellation diagram is subdivided into two or more regions. For each of the regions, a subset of the subcarriers that fall within the region are extracted and a respective region-specific CPE estimate is computed thereon. The respective region-specific CPE estimates are averaged to produce an overall CPE estimate used to compensate the subcarriers. Furthermore, a first CPE estimate is computed using pilot symbols embedded in a first received FDM symbol and is used to compensate the subcarriers. A following second FDM symbol that has no embedded pilot symbols is compensated using the first CPE estimate, and a second CPE estimate is computed using a blind estimation method on the second FDM symbol compensated subcarriers, which are compensated using the second CPE estimate.

Common phase error (CPE) compensation for frequency division multiplex (FDM) symbols in wireless communication systems

A method for reducing complexity of downlink signal demodulation in a multiuser (MU) multiple-input-multiple-output (MIMO) wireless communication system includes a base station acquiring uplink (UL) channel state information (CSI) of a MIMO channel between the base station and a user equipment (UE), deriving downlink (DL) CSI from the UL CSI, and transmitting orthogonal frequency-division multiplexing (OFDM) radio subframes using MIMO pre-equalization based on the DL CSI. The UE performs downlink reciprocity correction of the OFDM subframes received from the base station using a single complex phasor estimate and performs downlink data demodulation of the downlink reciprocity corrected OFDM subframes without performing additional MIMO equalization.

Reduced-complexity downlink (DL) signal demodulation using reciprocity reference signals for MIMO wireless communication systems

An apparatus includes circuitry that processes a subframe as part of a time-domain signal frame structure used for radio frequency communications. The subframe includes a plurality of block symbols each having an associated time-domain guard period and one or more radio frequency (RF) switching guard periods. Each block symbol of the plurality of block symbols is either a common block symbol or a special block symbol. A common block symbol has a common time-domain guard period with all other common block symbols of the subframe. A special block symbol has a time-domain guard period different from the common time-domain guard period. All the special block symbols in the subframe are placed into the one or more RF switching guard periods.

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Austin, TX, United States of America

Nikhil U Kundargi