Patent Description:
Aspects of the present disclosure generally relate to wireless communication and to techniques and apparatuses for synthesizing an uplink composite beam.

<NPL> discloses that indicating multiple SRS is needed for multi-beam transmission, and TPMI is applied over the selected resources. Based on measuring those precoded SRS resources, gNB firstly selects SRS resource from each resource group and the TPMI is indicated for co-phasing between the selected beams.

<CIT> discloses a method for wireless communication, comprising: receiving a configuration indicating a number of beams to be reported in a channel state information (CSI) report; receiving a set of reference signals; identifying, for one or more spatial layers and based at least in part on the set of reference signals, a set of beams corresponding to the number of beams for reporting in the CSI report, wherein the set of beams comprises at least one non-zero-power beam; generating the CSI report comprising a beam coefficient for each of the at least one non-zero-power beam for each of the one or more spatial layers and an indicator of the at least one non-zero-power beam; and transmitting the CSI report.

In some aspects, a method of wireless communication performed by a user equipment (UE) includes transmitting sounding reference signals (SRSs) on a plurality of beams to a base station using a set of SRS resources indicated by the base station. The method also includes receiving, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources and determining a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator.

In some aspects, a method of wireless communication performed by a base station includes determining a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE and transmitting an indication of the set of SRS resources to the UE for use in beam training. The method also includes determining one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, transmitting an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, and receiving, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources.

In some aspects, a UE for wireless communication includes a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to transmit SRSs on a plurality of beams to a base station using a set of SRS resources indicated by the base station, receive, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources, and determine a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator.

In some aspects, a base station for wireless communication includes a memory and one or more processors operatively coupled to the memory, the memory and the one or more processors configured to determine a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE and transmit an indication of the set of SRS resources to the UE for use in beam training. The memory and the one or more processors are configured to determine one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, transmit an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, and receive, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources.

In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a UE, cause the UE to transmit SRSs on a plurality of beams to a base station using a set of SRS resources indicated by the base station, receive, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources, and determine a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator.

In some aspects, a non-transitory computer-readable medium storing a set of instructions for wireless communication includes one or more instructions that, when executed by one or more processors of a base station, cause the base station to determine a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE, transmit an indication of the set of SRS resources to the UE for use in beam training, determine one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, transmit an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, and receive, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources.

In some aspects, an apparatus for wireless communication includes means for transmitting SRSs on a plurality of beams to a base station using a set of SRS resources indicated by the base station, means for receiving, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources, and means for determining a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator.

In some aspects, an apparatus for wireless communication includes means for determining a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE, means for transmitting an indication of the set of SRS resources to the UE for use in beam training, means for determining one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, means for transmitting an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, and means for receiving, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources.

Transmit processor <NUM> may also generate reference symbols for reference signals (e.g., a cell-specific reference signal (CRS), a demodulation reference signal (DMRS), and/or the like) and synchronization signals (e.g., the primary synchronization signal (PSS) and secondary synchronization signal (SSS)).

On the uplink, at UE <NUM>, a transmit processor <NUM> may receive and process data from a data source <NUM> and control information (e.g., for reports that include RSRP, RSSI, RSRQ, CQI, and/or the like) from controller/processor <NUM>.

Controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform one or more techniques associated with synthesizing an uplink composite beam, as described in more detail elsewhere herein. For example, controller/processor <NUM> of base station <NUM>, controller/processor <NUM> of UE <NUM>, and/or any other component(s) of <FIG> may perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, and/or other processes as described herein. Memories <NUM> and <NUM> may store data and program codes for base station <NUM> and UE <NUM>, respectively. In some aspects, memory <NUM> and/or memory <NUM> may include a non-transitory computer-readable medium storing one or more instructions (e.g., code, program code, and/or the like) for wireless communication. For example, the one or more instructions, when executed (e.g., directly, or after compiling, converting, interpreting, and/or the like) by one or more processors of the base station <NUM> and/or the UE <NUM>, may cause the one or more processors, the UE <NUM>, and/or the base station <NUM> to perform or direct operations of, for example, process <NUM> of <FIG>, process <NUM> of <FIG>, and/or other processes as described herein. In some aspects, executing instructions may include running the instructions, converting the instructions, compiling the instructions, interpreting the instructions, and/or the like.

In some aspects, UE <NUM> may include means for transmitting sounding reference signals (SRSs) on a plurality of beams to a base station using a set of SRS resources indicated by the base station, means for receiving, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources, means for determining a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator, and/or the like. In some aspects, such means may include one or more components of UE <NUM> described in connection with <FIG>, such as controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, and/or the like.

In some aspects, base station <NUM> may include means for determining a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE, means for transmitting an indication of the set of SRS resources to the UE for use in beam training, means for determining one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, means for transmitting an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, means for receiving, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources, and/or the like. In some aspects, such means may include one or more components of base station <NUM> described in connection with <FIG>, such as antenna <NUM>, DEMOD <NUM>, MIMO detector <NUM>, receive processor <NUM>, controller/processor <NUM>, transmit processor <NUM>, TX MIMO processor <NUM>, MOD <NUM>, antenna <NUM>, and/or the like.

<FIG> is a diagram illustrating an example <NUM> of multiple subarrays for a UE, in accordance with various aspects of the present disclosure.

<FIG> shows a UE with multiple subarrays at different portions of the UE. Each subarray may form a beam in a particular direction. Beamforming in frequency range FR2 may be based on steering energy in a single direction and may include hierarchical beamforming with one or more procedures. Such procedures may involve measurements on different beams and selecting beams for transmission and/or reception based at least in part on the measurements. In some aspects, the UE may simultaneously transmit a plurality of beams from the multiple subarrays.

<FIG> is a diagram illustrating examples <NUM>, <NUM> of multiple deflected beams, in accordance with various aspects of the present disclosure.

A beam may include one or more clusters of transmission energy, and beams may have different beamwidths. A beam with a wider beamwidth may incorporate multiple clusters within the coverage area of that beam, and a beam with a narrower beamwidth may not incorporate multiple clusters. There may be multiple clusters of energy or multiple beams that arrive at a receiver from different angles due to beam reflections off of objects, such as concrete walls, metal buildings, or glass windows.

A UE may detect clusters of energy from different angles or different spatial directions of a channel. The UE may receive a downlink communication by selecting a cluster of energy from a particular direction. The UE may also determine to transmit a communication on an uplink beam in the same direction, as shown by example <NUM> in <FIG>. However, if the UE transmits in only a single direction on a single uplink beam, the UE may not transmit uplink communications with a strong signal. As a result, communications with the base station may be degraded. The UE and the base station may waste processing and signaling resources retransmitting signals or otherwise accounting for the degraded communications.

According to various aspects described herein, a UE may synthesize an uplink composite beam to a base station from multiple beams that may be deflected off of objects. The UE may determine the uplink composite beam based at least in part on beam training using SRSs. For example, the base station may indicate a set of SRS resources to the UE, and the UE may transmit SRSs in the set of SRS resources. The base station may determine which SRSs have greater signal strengths and/or greater signal to noise plus interference ratios (SINRs) and transmit an SRS indicator for the SRS resources associated with the SRSs having greater signal strengths or SINRs. The UE may form an uplink composite beam from multiple beams based at least in part on the SRS indicator, as shown by example <NUM> of <FIG>. Accordingly, uplink communications transmitted on the uplink composite beam (and reflected off of objects) may be received with a stronger overall signal. As a result, uplink communications to the base station may improve, causing the UE and the base station to conserve processing and signaling resources that would otherwise be consumed retransmitting signals or accounting for degraded communications.

As indicated above, <FIG> is provided some examples.

<FIG> is a diagram illustrating example <NUM> of synthesizing an uplink composite beam, in accordance with various aspects of the present disclosure. As shown in <FIG>, example <NUM> includes communication between a base station (BS) <NUM> (e.g., a BS <NUM> depicted in <FIG> and <FIG>) and a UE <NUM> (e.g., a UE <NUM> depicted in <FIG> and <FIG>). In some aspects, BS <NUM> and UE <NUM> may be included in a wireless network, such as wireless network <NUM>. BS <NUM> and UE <NUM> may communicate on a wireless access link, which may include an uplink and a downlink.

As shown by reference number <NUM>, BS <NUM> may determine a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE. The feedback may include feedback for an access procedure, feedback for a random access channel procedure, a channel state information reporting indicator (CRI), and/or the like. BS <NUM> may transmit an indication of the set of SRS resources for use in beam training to the UE, as shown by reference number <NUM>.

UE <NUM> may use the set of SRS resources for beam training. The beam training may involve determining which beams are best for communication (e.g., determine a ranking or listing of beams). As shown by reference number <NUM>, UE <NUM> may transmit SRSs on a plurality of beams using the set of SRS resources, which may involve the SRSs being received on multiple beams. Some SRS resources may be associated with a beam that reflects off a concrete building, and some SRS resources may be associated with another beam that reflects off of glass windows of a different building.

<FIG> is a diagram illustrating example <NUM> of synthesizing an uplink composite beam, in accordance with various aspects of the present disclosure. <FIG> is a continuation of operations by BS <NUM> and UE <NUM> described in connection with <FIG>.

As shown by reference number <NUM>, BS <NUM> may determine one or more SRS resources for UE <NUM> from the set of indicated SRS resources that BS <NUM> indicated to UE <NUM> based at least in part on measurements of the SRSs received from UE <NUM> on multiple beams. The measurements may include signal strength measurements, SINR measurements, and/or the like. UE <NUM> may have report a best top-K beams in terms of RSRPs and/or SINRs. BS <NUM> may determine the SRS resources based at least in part on downlink beam training, initial acquisition signals, a random access channel (RACH) message, a channel state information reference signal (CSI-RS), and/or the like. In some aspects, BS <NUM> may request that UE <NUM> transmit the set of SRS resources using uplink beams that are quasi co-located with downlink reference signals.

As shown by reference number <NUM>, BS <NUM> may transmit an SRS resource indicator to UE <NUM>. The SRS resource indicator may indicate the SRS resources that BS <NUM> determined from the set of SRS resources. UE <NUM> may determine, based at least in part on the SRS resource indicator, an uplink composite beam that is synthesized from a combination of multiple beams, as shown by reference number <NUM>. UE <NUM> may determine which beams to combine based at least in part on measurements made by UE <NUM>. For example, UE <NUM> may combine beams with greater signal strengths, greater SINRs, more reliability, more stability, and/or the like. UE <NUM> may also combine pairs of beams that may be found to be complementary.

As shown by reference number <NUM>, BS <NUM> may receive communications on the uplink composite beam. For example, BS <NUM> may receive information about the uplink composite beam from UE <NUM> and may receive uplink communications by selecting receive beams that are based at least in part on the uplink composite beam. BS <NUM> may combine one or more of the best CSI-RS resource indicators (CRIs) or transmission configuration indicator (TCI) states reported by UE <NUM> (e.g., top-K best). BS <NUM> may use a Type-II codebook implementation. In some aspects, BS <NUM> may transmit downlink communications on a downlink composite beam, formed from one or more beams (e.g., top-K best CRI or TCI states, subset of top-K best CRI or TCI states), that corresponds to the uplink composite beam, as shown by reference number <NUM>.

In some aspects, BS <NUM> may determine combining coefficients for use with the SRS resources and provide them to UE <NUM>. BS <NUM> may determine a combining coefficient based at least in part on a measurement of signal strength and correlate the combining coefficient with a beam weight. This may be part of or performed in combination with reference number <NUM>. UE <NUM> may use the combining coefficients to form the uplink composite beam. In some aspects, UE <NUM> may determine that a beam may be boosted or improved with a particular combining coefficient. For example, a beam with a weak signal but a good SINR may be boosted or weighted heavier for the uplink composite beam with a combining coefficient. In some aspects, UE <NUM> may determine the uplink composite beam, part of reference number <NUM>, as a linear combination of beam weights of individual beams, with the linear combination generated using the combining coefficients. As a result, the uplink composite beam may be a combination of beams that combine to provide greater signal strength and/or greater accuracy. The uplink composite beam improves communications between BS <NUM> and UE <NUM>.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a UE, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the UE (e.g., UE <NUM> depicted in <FIG> and <FIG>, the UE depicted in <FIG>, UE <NUM> depicted in <FIG> and <FIG>, and/or the like) performs operations associated with synthesizing an uplink composite beam.

As shown in <FIG>, in some aspects, process <NUM> may include transmitting SRSs on a plurality of beams to a base station using a set of SRS resources indicated by the base station (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit SRSs on a plurality of beams to a base station using a set of SRS resources indicated by the base station, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include receiving, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive, from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include determining a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator (block <NUM>). For example, the UE (e.g., using receive processor <NUM>, transmit processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator, as described above.

In a first aspect, process <NUM> includes transmitting communications to the base station using two or more of the plurality of beams as the combined transmit beam.

In a second aspect, alone or in combination with the first aspect, process <NUM> includes receiving, from the base station, one or more combining coefficients across the one or more SRS resources, where determining the combined transmit beam includes determining the combined transmit beam further based at least in part on the one or more combining coefficients.

In a third aspect, alone or in combination with one or more of the first and second aspects, determining the combined transmit beam incudes determining beam weights for respective beams of the plurality of beams and generating the combined transmit beam as a linear combination of the beam weights.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, generating the combined transmit beam as a linear combination of beam weights includes generating the linear combination of beam weights using the one or more combining coefficients.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, one or more combining coefficients of the combined transmit beam are weighted towards a strongest beam of the plurality of beams and a second strongest beam of the plurality of beams.

In a sixth aspect, alone or in combination with one or more of the first through fifth aspects, one or more combining coefficients of the combined transmit beam are weighted towards a highest quality or reliability beam of the plurality of beams and a second highest quality or reliability beam of the plurality of beams.

In a seventh aspect, alone or in combination with one or more of the first through sixth aspects, determining the combined transmit beam includes determining two or more of the plurality of beams as the combined transmit beam based at least in part on one or more of a signal strength or a signal to noise ratio of each of the two or more of the plurality of beams.

In an eighth aspect, alone or in combination with one or more of the first through seventh aspects, the combined transmit beam includes at least two beams of the plurality of beams that are complementary. In some aspects, the combined transmit beam is to be transmitted in one or more frequencies in FR2.

In a ninth aspect, alone or in combination with one or more of the first through eighth aspects, the set of SRS resources include SRS resources that are quasi-co-located with different downlink reference signals.

<FIG> is a diagram illustrating an example process <NUM> performed, for example, by a base station, in accordance with various aspects of the present disclosure. Example process <NUM> is an example where the base station (e.g., base station <NUM> depicted in <FIG> and <FIG>, the base station depicted in <FIG>, BS <NUM> depicted in <FIG> and <FIG>, and/or the like) performs operations associated with synthesizing an uplink composite beam.

As shown in <FIG>, in some aspects, process <NUM> may include determining a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE (block <NUM>). For example, the base station (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine a set of SRS resources to provide to a UE based at least in part on feedback for one or more signals transmitted to the UE, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting an indication of the set of SRS resources to the UE for use in beam training (block <NUM>). For example, the base station (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit an indication of the set of SRS resources to the UE for use in beam training, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include determining one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE (block <NUM>). For example, the base station (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may determine one or more SRS resources for the UE from the set of SRS resources based at least in part on measurements of SRSs received with the set of SRS resources on a plurality of beams from the UE, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include transmitting an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources (block <NUM>). For example, the base station (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may transmit an SRS resource indicator to the UE, the SRS resource indicator indicating the one or more SRS resources of the set of SRS resources, as described above.

As further shown in <FIG>, in some aspects, process <NUM> may include receiving, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources (block <NUM>). For example, the base station (e.g., using transmit processor <NUM>, receive processor <NUM>, controller/processor <NUM>, memory <NUM>, and/or the like) may receive, from the UE, communications on a combined transmit beam that is combined from a plurality of beams based at least in part on the one or more SRS resources, as described above.

In a first aspect, process <NUM> includes determining one or more combining coefficients across the one or more SRS resources to be used by the UE for determining the combined transmit beam and transmitting the one or more combining coefficients to the UE.

In a second aspect, alone or in combination with the first aspect, determining the one or more combining coefficients includes determining the one or more combining coefficients based at least in part on a reference signal received power or a signal to noise ratio for one or more of the plurality of beams.

In a third aspect, alone or in combination with one or more of the first and second aspects, the feedback includes one or more of feedback for a random access channel procedure, feedback for an initial access procedure, or a channel state information reference signal.

In a fourth aspect, alone or in combination with one or more of the first through third aspects, determining the one or more SRS resources and transmitting the SRS resource indicator includes using a type-II codebook, and the combined transmit beam is received in one or more frequencies in FR2.

In a fifth aspect, alone or in combination with one or more of the first through fourth aspects, the set of SRS resources include SRS resources that are quasi-co-located with different downlink reference signals.

Claim 1:
A method (<NUM>) of wireless communication performed by a user equipment, UE, comprising:
transmitting (<NUM>) sounding reference signals, SRSs, on a plurality of beams to a base station using a set of SRS resources indicated by the base station;
receiving (<NUM>), from the base station, an SRS resource indicator indicating one or more SRS resources of the set of SRS resources;
receiving (<NUM>), from the base station, a plurality of combining coefficients across the one or more SRS resources; and
determining a combined transmit beam from the plurality of beams based at least in part on the SRS resource indicator and at least in part on the plurality of combining coefficients;
wherein determining the combined transmit beam incudes determining beam weights for respective beams of the plurality of beams and generating the combined transmit beam as a linear combination of the beam weights, and wherein generating the combined transmit beam as a linear combination of beam weights includes generating the linear combination of beam weights using the plurality of combining coefficients; and
wherein one or more combining coefficients of a plurality of combining coefficients of the combined transmit beam are weighted towards a strongest beam of the plurality of beams and a second strongest beam of the plurality of beams, and one or more combining coefficients of the plurality of combining coefficients of the combined transmit beam are weighted towards a highest quality beam of the plurality of beams and a second highest quality beam of the plurality of beams.