WO2021237716A1

WO2021237716A1 - Evaluation for beam failure recovery selection

Info

Publication number: WO2021237716A1
Application number: PCT/CN2020/093472
Authority: WO
Inventors: Zhuoqi XU; Yuankun ZHU; Pan JIANG
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2021-12-02
Anticipated expiration: 2022-11-29

Abstract

Methods, systems, and devices for wireless communications are described. For example, a method for wireless communications at a user equipment (UE), may include measuring a plurality of receive powers for a corresponding plurality of beams. The UE may identify one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold. Then, the UE may rank the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam. The UE may determine, based at least in part on the ranking, a selected candidate beam. The UE may also perform a random access procedure using the selected candidate beam.

Description

EVALUATION FOR BEAM FAILURE RECOVERY SELECTION

FIELD OF TECHNOLOGY

The following relates generally to wireless communications and more specifically to evaluation for beam failure recovery selection.

BACKGROUND

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal frequency division multiple access (OFDMA) , or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) . A wireless multiple-access communications system may include one or more base stations or one or more network access nodes, each simultaneously supporting communication for multiple communication devices, which may be otherwise known as user equipment (UE) .

In some wireless communications systems, a UE may evaluate candidate beams for communicating with a base station, for example during beam management or beam recovery. The goal of the evaluation of candidate beams is to select a suitable beam for future communications. The evaluation may be inefficient if a selected beam is not suitable for future communications. If a poor quality beam is selected based on the beam evaluation, then an additional beam evaluation procedure may be performed to attempt to reselect a good quality beam. In some cases, a lengthy beam evaluation procedure may follow the initial beam selection attempt. Thus, current beam evaluation procedures may cause unnecessary latency in communications. As a result, improved techniques may be desired for ensuring efficient beam selection for improved quality of communications.

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support evaluation for beam failure recovery selection. Generally, the described techniques provide for efficient beam selection based on a ranking system that evaluates additional selection criteria, for example a channel condition of a beam. The network may configure a UE to evaluate candidate beams (e.g., during beam failure recovery) . In some examples, the configuration may include a receive power threshold to be used by the UE during candidate beam evaluation. For example, the evaluation may include the UE determining that a new beam should be selected based on the poor quality of a current beam, and the UE may scan multiple beams measuring the receive power (e.g., reference signal receive power (RSRP) ) and channel condition (e.g., signal to noise ratio (SNR)) of each beam. The UE may filter the beams to select a number of candidate beams that satisfy the threshold received from the network. Then, the UE may evaluate the receive power and channel condition together for these candidate beams. Specifically, the UE may rank the candidate beams based on a calculation summing the receive power for a beam and a weighted channel condition. The UE may determine the weighting parameter of the channel condition based on the coverage quality of the network. After each candidate beam is ranked from highest to lowest summation, the UE may select the highest ranked beam to attempt a random access procedure on.

A method of wireless communications at a UE is described. The method may include measuring a set of receive powers for a corresponding set of beams, identifying one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, ranking the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determining, based on the ranking, a selected candidate beam, and performing a random access procedure using the selected candidate beam.

An apparatus for wireless communications at a UE is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to measure a set of receive powers for a corresponding set of beams, identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determine, based on the ranking, a selected candidate beam, and perform a random access procedure using the selected candidate beam.

Another apparatus for wireless communications at a UE is described. The apparatus may include means for measuring a set of receive powers for a corresponding set of beams, identifying one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, ranking the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determining, based on the ranking, a selected candidate beam, and performing a random access procedure using the selected candidate beam.

A non-transitory computer-readable medium storing code for wireless communications at a UE is described. The code may include instructions executable by a processor to measure a set of receive powers for a corresponding set of beams, identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determine, based on the ranking, a selected candidate beam, and perform a random access procedure using the selected candidate beam.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for determining a weighting parameter associated with a network coverage quality based on one or more channel condition measurements or the receive power threshold.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, ranking the one or more candidate beams further may include operations, features, means, or instructions for measuring the channel condition of each of the one or more candidate beams, and applying the weighting parameter to the channel condition of each of the one or more candidate beams.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the weighting parameter ranges from zero to one.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, ranking the one or more candidate beams further may include operations, features, means, or instructions for summing, for each candidate beam, a respective receive power with a respective weighted channel condition, and ranking the sums for each candidate beam.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, determining the selected candidate beam further may include operations, features, means, or instructions for selecting the candidate beam associated with a highest rank.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the one or more candidate beams may be ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a receive power configuration indicating the receive power threshold.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the receive power configuration includes a beam recovery configuration, and where the receive power threshold includes a layer one reference signal receive power threshold.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for operating in a radio resource configuration connected state, and determining a current beam quality may be below a beam quality threshold, where the measuring of the set of receive powers for the corresponding set of beams may be based on the current beam quality being below the beam quality threshold.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for measuring the receive power of a synchronization signal block of each of the set of beams based on the receive power configuration, and selecting the one or more candidate beams based on the receive power of each of the one or more candidate beams being greater than the receive power threshold.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the receive power configuration further may include operations, features, means, or instructions for receiving a radio resource control message including the receive power configuration.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the channel condition includes a signal to noise ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIG. 3 illustrates an example of a flowchart that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIG. 4 illustrates an example of a process flow that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIGs. 5 and 6 show block diagrams of devices that support evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIG. 7 shows a block diagram of a communications manager that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIG. 8 shows a diagram of a system including a device that supports evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

FIGs. 9 through 11 show flowcharts illustrating methods that support evaluation for beam failure recovery selection in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

A user equipment (UE) may be configured to perform beam selection based on an evaluation of multiple beam parameters for improved beam recovery that reduces latency from multiple beam selection operations. Conventionally, when a UE in a radio resource control (RRC) connected state experiences beam failure, the UE may initiate a beam failure recovery (BFR) procedure to select a new beam. The beam recovery configuration may include RSRP thresholds for new beam evaluation, but no other types of beam measurements are included or considered. Thus, the traditional determination of a new beam during BFR is based exclusively on the RSRP of candidate beams. Specifically, channel conditions (e.g., a signal to noise ratio (SNR) ) are not considered during BFR. Thus, a UE may select a new beam that has the highest RSRP of the candidate beams for attempting random access, but poor channel conditions on that beam, which may shortly result in an additional BFR or a lengthy RRC reestablishment procedure. The additional BFR or performance of RRC reestablishment may introduce avoidable latency into the UE’s communications.

The techniques described herein provide for efficient beam selection (e.g., in BFR) based on a ranking process that evaluates receive power and a channel condition of a beam. In some examples, the network may configure a UE to evaluate a number candidate beams, and the configuration may include a receive power threshold to be used by the UE during candidate beam assessment. The assessment may include the UE determining to scan multiple beams to measure the receive power (e.g., reference signal receive power (RSRP)) and channel condition (e.g., (SNR) ) of each beam based on the poor quality of a current beam. The UE may select a number of candidate beams that satisfy a threshold (e.g., an RSRP threshold) received from the network.

The UE may then evaluate the receive power and channel condition together for the candidate beams that satisfy the threshold. The UE may rank the candidate beams based on a summation of the receive power for a beam and a linear weighted channel condition associated with each beam. The UE may determine the weighting parameter of the channel condition based on the coverage quality of the network. For example, when the channel condition is SNR, the SNR of each beam may be weighted by a linear weight, K, such that the new term evaluated for ranking is equal to RSRP + K *SNR. In some cases, K may range from 0 to 1 and may be determined by the UE. One way that the UE may determine K is based on an SNR measurement at the UE. For instance, if the measured SNR is high indicating good coverage, then the UE may set K equal to 0.5, for example. If the measured SNR is low indicating weak coverage, then the UE may set K equal to 1, for example. In another example, the UE may determine K based on the relative value of the RSRP threshold set by the network. For example, a relatively high RSRP threshold may indicate that the UE is in weak coverage. As a result, the UE may set K equal to 1, which makes SNR a more substantial part of the evaluation. In another example, a relatively low RSRP threshold may indicate that the UE is in good coverage. As a result, the UE may set K equal to 0.5, for example. Thus, in weak coverage scenarios the SNR will be considered more heavily (e.g., K equal to 1) than in good coverage scenarios.

After each candidate beam is evaluated and ranked from highest to lowest summation, the UE may select the highest ranked summation associated with a best beam to attempt a random access procedure on. In some examples, the UE may perform a contention free random access procedure on the beam when the UE is performing BFR. In the BFR stage, the UE should take the selection of a candidate beam for recover seriously because a poor selection of a bad beam may enlarge the time for the process of beam recovery. Additionally or alternatively, a bad beam selection may account for the BFR failure and eventually cause a lengthy RRC reestablishment procedure. This technique may ensure that a UE chooses the best candidate beam for beam recovery based on the best channel condition, which decreases the risk of reperforming BFR and improves communication quality at the UE.

Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to evaluation for BFR selection.

FIG. 1 illustrates an example of a wireless communications system 100 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The wireless communications system 100 may include one or more base stations 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or a New Radio (NR) network. In some examples, the wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, communications with low-cost and low-complexity devices, or any combination thereof.

The base stations 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may be devices in different forms or having different capabilities. The base stations 105 and the UEs 115 may wirelessly communicate via one or more communication links 125. Each base station 105 may provide a coverage area 110 over which the UEs 115 and the base station 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a base station 105 and a UE 115 may support the communication of signals according to one or more radio access technologies.

The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115, the base stations 105, or network equipment (e.g., core network nodes, relay devices, integrated access and backhaul (IAB) nodes, or other network equipment) , as shown in FIG. 1.

The base stations 105 may communicate with the core network 130, or with one another, or both. For example, the base stations 105 may interface with the core network 130 through one or more backhaul links 120 (e.g., via an S1, N2, N3, or other interface) . The base stations 105 may communicate with one another over the backhaul links 120 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) , or indirectly (e.g., via core network 130) , or both. In some examples, the backhaul links 120 may be or include one or more wireless links.

One or more of the base stations 105 described herein may include or may be referred to by a person having ordinary skill in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next- generation NodeB or a giga-NodeB (either of which may be referred to as a gNB) , a Home NodeB, a Home eNodeB, or other suitable terminology.

A UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the base stations 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in FIG. 1.

The UEs 115 and the base stations 105 may wirelessly communicate with one another via one or more communication links 125 over one or more carriers. The term “carrier” may refer to a set of radio frequency spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a radio frequency spectrum band (e.g., a bandwidth part (BWP) ) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR) . Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information) , control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers.

In some examples (e.g., in a carrier aggregation configuration) , a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers. A carrier may be associated with a frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN) ) and may be positioned according to a channel raster for discovery by the UEs 115. A carrier may be operated in a standalone mode where initial acquisition and connection may be conducted by the UEs 115 via the carrier, or the carrier may be operated in a non-standalone mode where a connection is anchored using a different carrier (e.g., of the same or a different radio access technology) .

The communication links 125 shown in the wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Carriers may carry downlink or uplink communications (e.g., in an FDD mode) or may be configured to carry downlink and uplink communications (e.g., in a TDD mode) .

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of determined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 megahertz (MHz)) . Devices of the wireless communications system 100 (e.g., the base stations 105, the UEs 115, or both) may have hardware configurations that support communications over a particular carrier bandwidth or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 or UEs 115 that support simultaneous communications via carriers associated with multiple carrier bandwidths. In some examples, each served UE 115 may be configured for operating over portions (e.g., a sub-band, a BWP) or all of a carrier bandwidth.

Signal waveforms transmitted over a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) . In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both) . Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. A wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers or beams) , and the use of multiple spatial layers may further increase the data rate or data integrity for communications with a UE 115.

One or more numerologies for a carrier may be supported, where a numerology may include a subcarrier spacing (Δf) and a cyclic prefix. A carrier may be divided into one or more BWPs having the same or different numerologies. In some examples, a UE 115 may be configured with multiple BWPs. In some examples, a single BWP for a carrier may be active at a given time and communications for the UE 115 may be restricted to one or more active BWPs.

The time intervals for the base stations 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T _s= 1/ (Δf _max·N _f) seconds, where Δf _max may represent the maximum supported subcarrier spacing, and N _f may represent the maximum supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms) ) . Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023) .

Each frame may include multiple consecutively numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a number of slots. Alternatively, each frame may include a variable number of slots, and the number of slots may depend on subcarrier spacing. Each slot may include a number of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . In some wireless communications systems 100, a slot may further be divided into multiple mini-slots containing one or more symbols. Excluding the cyclic prefix, each symbol period may contain one or more (e.g., N _f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI) . In some examples, the TTI duration (e.g., the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs)) .

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET) ) for a physical control channel may be defined by a number of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) may be configured for a set of the UEs 115. For example, one or more of the UEs 115 may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to a number of control channel resources (e.g., control channel elements (CCEs) ) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets for sending control information to a specific UE 115.

Each base station 105 may provide communication coverage via one or more cells, for example a macro cell, a small cell, a hot spot, or other types of cells, or any combination thereof. The term “cell” may refer to a logical communication entity used for communication with a base station 105 (e.g., over a carrier) and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID) , a virtual cell identifier (VCID) , or others) . In some examples, a cell may also refer to a geographic coverage area 110 or a portion of a geographic coverage area 110 (e.g., a sector) over which the logical communication entity operates. Such cells may range from smaller areas (e.g., a structure, a subset of structure) to larger areas depending on various factors such as the capabilities of the base station 105. For example, a cell may be or include a building, a subset of a building, or exterior spaces between or overlapping with geographic coverage areas 110, among other examples.

A macro cell generally covers a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by the UEs 115 with service subscriptions with the network provider supporting the macro cell. A small cell may be associated with a lower-powered base station 105, as compared with a macro cell, and a small cell may operate in the same or different (e.g., licensed, unlicensed) frequency bands as macro cells. Small cells may provide unrestricted access to the UEs 115 with service subscriptions with the network provider or may provide restricted access to the UEs 115 having an association with the small cell (e.g., the UEs 115 in a closed subscriber group (CSG) , the UEs 115 associated with users in a home or office) . A base station 105 may support one or multiple cells and may also support communications over the one or more cells using one or multiple component carriers.

In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., MTC, narrowband IoT (NB-IoT) , enhanced mobile broadband (eMBB) ) that may provide access for different types of devices.

In some examples, a base station 105 may be movable and therefore provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, but the different geographic coverage areas 110 may be supported by the same base station 105. In other examples, the overlapping geographic coverage areas 110 associated with different technologies may be supported by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the base stations 105 provide coverage for various geographic coverage areas 110 using the same or different radio access technologies.

The wireless communications system 100 may support synchronous or asynchronous operation. For synchronous operation, the base stations 105 may have similar frame timings, and transmissions from different base stations 105 may be approximately aligned in time. For asynchronous operation, the base stations 105 may have different frame timings, and transmissions from different base stations 105 may, in some examples, not be aligned in time. The techniques described herein may be used for either synchronous or asynchronous operations.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that makes use of the information or presents the information to humans interacting with the application program. Some UEs 115 may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously) . In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for the UEs 115 include entering a power saving deep sleep mode when not engaging in active communications, operating over a limited bandwidth (e.g., according to narrowband communications) , or a combination of these techniques. For example, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a defined portion or range (e.g., set of subcarriers or resource blocks (RBs) ) within a carrier, within a guard-band of a carrier, or outside of a carrier.

The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC) or mission critical communications. The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions (e.g., mission critical functions) . Ultra-reliable communications may include private communication or group communication and may be supported by one or more mission critical services such as mission critical push-to-talk (MCPTT) , mission critical video (MCVideo) , or mission critical data (MCData) . Support for mission critical functions may include prioritization of services, and mission critical services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, mission critical, and ultra-reliable low-latency may be used interchangeably herein.

In some examples, a UE 115 may also be able to communicate directly with other UEs 115 over a device-to-device (D2D) communication link 135 (e.g., using a peer-to-peer (P2P) or D2D protocol) . One or more UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105 or be otherwise unable to receive transmissions from a base station 105. In some examples, groups of the UEs 115 communicating via D2D communications may utilize a one-to-many (1: M) system in which each UE 115 transmits to every other UE 115 in the group. In some examples, a base station 105 facilitates the scheduling of resources for D2D communications. In other cases, D2D communications are carried out between the UEs 115 without the involvement of a base station 105.

In some systems, the D2D communication link 135 may be an example of a communication channel, such as a sidelink communication channel, between vehicles (e.g., UEs 115) . In some examples, vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. A vehicle may signal information related to traffic conditions, signal scheduling, weather, safety, emergencies, or any other information relevant to a V2X system. In some examples, vehicles in a V2X system may communicate with roadside infrastructure, such as roadside units, or with the network via one or more network nodes (e.g., base stations 105) using vehicle-to-network (V2N) communications, or with both.

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or 5G core (5GC) , which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management function (AMF)) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the base stations 105 associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to the network operators IP services 150. The operators IP services 150 may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched Streaming Service.

Some of the network devices, such as a base station 105, may include subcomponents such as an access network entity 140, which may be an example of an access node controller (ANC) . Each access network entity 140 may communicate with the UEs 115 through one or more other access network transmission entities 145, which may be referred to as radio heads, smart radio heads, or transmission/reception points (TRPs) . Each access network transmission entity 145 may include one or more antenna panels. In some configurations, various functions of each access network entity 140 or base station 105 may be distributed across various network devices (e.g., radio heads and ANCs) or consolidated into a single network device (e.g., a base station 105) .

The wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. The UHF waves may be blocked or redirected by buildings and environmental features, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. The transmission of UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band, or in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz) , also known as the millimeter band. In some examples, the wireless communications system 100 may support millimeter wave (mmW) communications between the UEs 115 and the base stations 105, and EHF antennas of the respective devices may be smaller and more closely spaced than UHF antennas. In some examples, this may facilitate use of antenna arrays within a device. The propagation of EHF transmissions, however, may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. The techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

The wireless communications system 100 may utilize both licensed and unlicensed radio frequency spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. When operating in unlicensed radio frequency spectrum bands, devices such as the base stations 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA) . Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

A base station 105 or a UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a base station 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations. Additionally or alternatively, an antenna panel may support radio frequency beamforming for a signal transmitted via an antenna port.

The base stations 105 or the UEs 115 may use MIMO communications to exploit multipath signal propagation and increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers. Such techniques may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams (e.g., different codewords) . Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) , where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) , where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105, a UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that some signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude offsets, phase offsets, or both to signals carried via the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

A base station 105 or a UE 115 may use beam sweeping techniques as part of beam forming operations. For example, a base station 105 may use multiple antennas or antenna arrays (e.g., antenna panels) to conduct beamforming operations for directional communications with a UE 115. Some signals (e.g., synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions. For example, the base station 105 may transmit a signal according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by a transmitting device, such as a base station 105, or by a receiving device, such as a UE 115) a beam direction for later transmission or reception by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115) . In some examples, the beam direction associated with transmissions along a single beam direction may be determined based on a signal that was transmitted in one or more beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions and may report to the base station 105 an indication of the signal that the UE 115 received with a highest signal quality or an otherwise acceptable signal quality.

In some examples, transmissions by a device (e.g., by a base station 105 or a UE 115) may be performed using multiple beam directions, and the device may use a combination of digital precoding or radio frequency beamforming to generate a combined beam for transmission (e.g., from a base station 105 to a UE 115) . The UE 115 may report feedback that indicates precoding weights for one or more beam directions, and the feedback may correspond to a configured number of beams across a system bandwidth or one or more sub-bands. The base station 105 may transmit a reference signal (e.g., a cell-specific reference signal (CRS) , a channel state information reference signal (CSI-RS) ) , which may be precoded or unprecoded. The UE 115 may provide feedback for beam selection, which may be a precoding matrix indicator (PMI) or codebook-based feedback (e.g., a multi-panel type codebook, a linear combination type codebook, a port selection type codebook) . Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115) or for transmitting a signal in a single direction (e.g., for transmitting data to a receiving device) .

A receiving device (e.g., a UE 115) may try multiple receive configurations (e.g., directional listening) when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets (e.g., different directional listening weight sets) applied to signals received at multiple antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at multiple antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive configurations or receive directions. In some examples, a receiving device may use a single receive configuration to receive along a single beam direction (e.g., when receiving a data signal) . The single receive configuration may be aligned in a beam direction determined based on listening according to different receive configuration directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio (SNR) , or otherwise acceptable signal quality based on listening according to multiple beam directions) .

The wireless communications system 100 may be a packet-based network that operates according to a layered protocol stack. In the user plane, communications at the bearer or Packet Data Convergence Protocol (PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may perform packet segmentation and reassembly to communicate over logical channels. A Medium Access Control (MAC) layer may perform priority handling and multiplexing of logical channels into transport channels. The MAC layer may also use error detection techniques, error correction techniques, or both to support retransmissions at the MAC layer to improve link efficiency. In the control plane, the Radio Resource Control (RRC) protocol layer may provide establishment, configuration, and maintenance of an RRC connection between a UE 115 and a base station 105 or a core network 130 supporting radio bearers for user plane data. At the physical layer, transport channels may be mapped to physical channels.

The UEs 115 and the base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. Hybrid automatic repeat request (HARQ) feedback is one technique for increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC) ) , forward error correction (FEC) , and retransmission (e.g., automatic repeat request (ARQ) ) . HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., low signal-to-noise conditions) . In some examples, a device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot. In other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

A base station 105 may configure a UE 115 to evaluate candidate beams. In some examples, the configuration may include a RSRP threshold to be used by the UE 115 during candidate beam evaluation. For example, the evaluation may include the UE 115 determining that a new beam should be selected for communication with base station 105 based on a poor quality of a current beam. The UE 115 may scan multiple beams from base station 105 to measure the receive power (e.g., RSRP) and channel condition (e.g., SNR) of each beam. Then, the UE 115 may select a number of candidate beams that satisfy the threshold from the set of scanned beams. As described herein, the UE 115 may evaluate both the RSRP and SNR for the candidate beams that satisfy the threshold from base station 105. Specifically, the UE 115 may rank the candidate beams based on an evaluation summing the RSRP for a beam and a linear weighted SNR. The UE 115 may determine the weighting parameter K used on the SNR based on the network coverage quality. After each candidate beam is ranked from highest to lowest summation, the UE 115 may select the highest ranked beam to use for a random access procedure with the base station 105.

FIG. 2 illustrates an example of a wireless communications system 200 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. In some examples, wireless communications system 200 may implement aspects of wireless communications system 100. Wireless communications system 200 may include UE 115-a and base station 105-a, which may be respective examples of a UE 115 and a base station 105, as described with reference to FIG. 1. UE 115-a may be operating in an RRC connected state and may determine to select a new beam. The example below will be described for BFR but this technique may apply to any beam selection procedure.

UE 115-a may have previously been communicating with base station 105-a. However, the UE 115-a may detect that the previously used beam for communications with base station 105-a has failed and BFR should be performed based on radio link monitoring parameters (e.g., a block error rate (BLER) threshold) . For instance, the UE 115-a may determine the BLER of a channel (e.g., the PDCCH) is equal to or greater than about 10 percent. As a result, UE 115-a may perform a BFR procedure to select a new beam 205 for communications with base station 105-a. UE 115-a may receive a beam failure recovery configuration from base station 105-a. The beam failure recovery configuration may include a L1-RSRP threshold to be evaluated against the RSRP of a synchronization signal block (SSB) 215 of each candidate beam 205.

For example, UE 115-a may use beam 210 to scan beams 205-a, 205-b, and 205-c from base station 105-a. Specifically, the UE 115-a may measure the RSRP of each of the SSBs 215-a, 215-b, and 215-c of the respective beams 205. The number of beams 205 scanned by UE 115-a may be indicated by the base station 105-a. The RSRP of each SSB 215 may be measured and compared to the configured L1-RSRP threshold. For example, if the RSRP of SSBs 215-a and 215-b are above the threshold and the RSRP of SSB 215-c is below the threshold, the beams 205-a and 205-b may be selected as candidate beams for further evaluation.

UE 115-a may include a linear evaluation component 220 that implements BFR beam selection. Specifically, the linear evaluation component 220 may be configured to further evaluate which beam 205 of the beams that satisfy the RSRP threshold (e.g., beams 205-a and 205-b) is best for future communications with base station 105-a. For example, linear evaluation component 220 may evaluate the identified candidate beams 205-a and 205-b based on Equation 1:

Evaluation = RSRP + K *SNR. (1)

Where RSRP is the L1-RSRP measured for each beam 205, K is a linear weight, and SNR is the SNR measured for each beam 205.

The linear evaluation component 220 may determine K to be a value between 0 and 1 based on the coverage quality at the UE 115-a. One way that the UE 115-a may determine K based on one or more SNR measurements at the UE 115-a. If the measured SNR is high indicating good coverage, then the UE 115-a may set K equal to 0.5, for example. If the measured SNR is low indicating weak coverage, then the UE 115-a may set K equal to 1, for example. In another example, the UE 115-a may determine K is based on the relative value of the RSRP threshold set by the base station 105-a. For example, a relatively high RSRP threshold may signal that the UE 115-a is in weak coverage. As a result, the UE 115-a may set K equal to 1 in order to make SNR a more substantial part of the evaluation. A relatively low RSRP threshold may signal that the UE 115-a is in good coverage. As a result, the UE 115-a may set K equal to 0.5, for example. Additionally or alternatively, the UE 115-a may make separate RSRP or SNR measurements over a number of times and/or frequencies to determine the quality of coverage. K may be a dynamic parameter that may be adjusted when the BFR configuration changes.

Once the linear evaluation component 220 determines K and applies the evaluation in Equation 1 to the beams that satisfy the RSRP threshold (e.g., beams 205-a and 205-b) , the linear evaluation component 220 may rank the outcomes of Equation 1 from largest to smallest. For example, the evaluation of beam 205-b may result in a larger summation of RSRP and SNR than the evaluation of beam 205-a. Thus, beam 205-b would be ranked higher than beam 205-a, and beam 205-b would be the best beam. UE 115-a may select beam 205-b and attempt a contention free random access procedure with base station 105-a. After a successful random access procedure between base station 105-a and UE 115-a, the two devices may resume communications.

The procedure described herein, including the evaluation of Equation 1, may ensure the UE 115-a choose the best candidate beam 205 for beam recovery with the best channel condition (e.g., RSRP and SNR) , which may decrease the risk of performing additional BFR or RRC reestablishment procedures that introduce latency into the communications between base station 105-a and UE 115-a.

FIG. 3 illustrates an example of a flowchart 300 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. In some examples, flowchart 300 may implement aspects of wireless communications system 100. Flowchart 300 may be a candidate beam evaluation procedure implemented at a UE such as UE 115 as described herein. The UE may be operating in an RRC connected state.

At 305, the UE may execute a L1-RSRP measurement on a current beam. At 310, the UE may determine a beam failure condition for the current beam based on the L1-RSRP measurement at 305. The UE may determine to perform a beam scan to select a new beam based on the beam failure condition. At 315, the UE may scan multiple potential beams by measuring the receive power of an SSB in each beam. The number of potential beams scanned may be determined by the network and indicated to the UE (e.g., via an RRC message) .

At 320, the UE may determine which of the scanned potential beams have an RSRP above the configured RSRP threshold for SSBs, which may be determined by the network and indicated to the UE in a BFR configuration (e.g., via an RRC message) . The beams that satisfy the RSRP threshold may be used by the UE at 325. The beams that do not satisfy the RSRP threshold may proceed to 350 and not be used by the UE for further evaluation based on their beam condition being too poor to result in a successful random access procedure.

At 325, the UE may determine the SNR values for each candidate beam that exceeded the threshold at 320. At 330, the UE may execute, for each candidate beam from 325, an evaluation that is the summation of the RSRP value and a weighted SNR value. The linear weighting parameter is K. K may be variable between 0 and 1 and change based on the network coverage. For example, K may be equal to or greater than 0.5 in weak coverage, and K may be equal to or less than 0.5 in good coverage. The coverage quality may be determined based on RSRP. For instance, the value of K may be based on the RSRP threshold used at 320. In another example, the UE may perform an RSRP measurement over a number of frequencies to determine the coverage quality, which may take place at 305.

At 335, the UE may rank the evaluations done at 330. The evaluations may be ranked from highest to lowest summation from the evaluations at 330. Thus, the largest sum of RSRP and the weighted SNR will be ranked the highest. After the ranking is complete, the UE may proceed to 340. At 340, the UE may select the beam associated with the highest rank based on the ranked evaluations from 335 and proceed to 345. At 345, the UE may perform a random access procedure (e.g., a contention free random access procedure) for BFR. If the random access procedure is successful, then the UE may communicate with the network on the selected beam.

FIG. 4 illustrates an example of a process flow 400 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. In some examples, process flow 400 may implement aspects of wireless communications system 100. Process flow 400 is shown as being implemented by a UE 115-b, which may be an example of the UEs 115 as described with respect to FIGs. 1 and 2. For example, UE 115-b may be an example of UE 115-a of FIG. 2. Process flow 400 is also shown as being implemented by base station 105-b, which may be an example of the base stations 105 as described with respect to FIGs. 1 and 2. For example, base station 105-b may be an example of base station 105-a of FIG. 2.

In the following description of the process flow 400, the operations of UE 115-b and base station 105-b may occur in a different order than the exemplary order shown. Certain illustrated operations may also be left out of the process flow 400, or other operations may be added to the process flow 400. It is to be understood that while UE 115-b and base station 105-b are shown performing a number of the operations of process flow 400, any wireless device may perform the operations shown.

At 405, base station 105-b may transmit and UE 115-b may receive an RRC configuration such as a BFR configuration. For example, UE 115-b may receive a receive power configuration indicating a receive power threshold (e.g., a RSRP SSB threshold) . In some examples, UE 115-b may determine a weighting parameter associated with a network coverage quality based at least in part on one or more channel condition measurements (e.g., SNR measurements) or the receive power threshold of the RRC configuration. The weighting parameter may range from zero to one.

At 410, base station 105-b may transmit and UE 115-b may receive reference signals (e.g., an SSB) on a set of beams. In some cases, UE 115-b may measure the receive power of an SSB of each of the plurality of beams based at least in part on the receive power configuration received at 405.

At 415, UE 115-b may measure a plurality of receive powers of reference signals for the corresponding plurality of beams received at 410.

At 420, UE 115-b may identify one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold.

At 425, UE 115-b may measure the channel condition of each of the one or more candidate beams. The channel condition may be SNR.

At 430, UE 115-b may rank the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam. In some examples, ranking may include UE 115-b measuring the channel condition of each of the one or more candidate beams and apply the weighting parameter to the channel condition of each of the one or more candidate beams. Then, UE 115-b may sum, for each candidate beam, a respective receive power with a respective weighted channel condition and rank the sums for each candidate beam. The one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam.

At 435, UE 115-b may determine, based at least in part on the ranking, a selected candidate beam. For example, the selected candidate beam may be associated with a highest rank and referred to as the beast beam. The highest rank may be associated with the largest sum from 430.

At 440, UE 115-b may perform a random access procedure with base station 105-b using the selected candidate beam from 435.

FIG. 5 shows a block diagram 500 of a device 505 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The device 505 may be an example of aspects of a UE 115 as described herein. The device 505 may include a receiver 510, a communications manager 515, and a transmitter 520. The device 505 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 510 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to evaluation for BFR selection, etc. ) . Information may be passed on to other components of the device 505. The receiver 510 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The receiver 510 may utilize a single antenna or a set of antennas.

The communications manager 515 may measure a set of receive powers for a corresponding set of beams, identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determine, based on the ranking, a selected candidate beam, and perform a random access procedure using the selected candidate beam. The communications manager 515 may be an example of aspects of the communications manager 810 described herein.

The communications manager 515, or its sub-components, may be implemented in hardware, code (e.g., software or firmware) executed by a processor, or any combination thereof. If implemented in code executed by a processor, the functions of the communications manager 515, or its sub-components may be executed by a general-purpose processor, a DSP, an application-specific integrated circuit (ASIC) , a FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described in the present disclosure.

The communications manager 515, or its sub-components, may be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations by one or more physical components. In some examples, the communications manager 515, or its sub-components, may be a separate and distinct component in accordance with various aspects of the present disclosure. In some examples, the communications manager 515, or its sub-components, may be combined with one or more other hardware components, including but not limited to an input/output (I/O) component, a transceiver, a network server, another computing device, one or more other components described in the present disclosure, or a combination thereof in accordance with various aspects of the present disclosure.

The transmitter 520 may transmit signals generated by other components of the device 505. In some examples, the transmitter 520 may be collocated with a receiver 510 in a transceiver module. For example, the transmitter 520 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The transmitter 520 may utilize a single antenna or a set of antennas.

FIG. 6 shows a block diagram 600 of a device 605 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The device 605 may be an example of aspects of a device 505, or a UE 115 as described herein. The device 605 may include a receiver 610, a communications manager 615, and a transmitter 645. The device 605 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 610 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, and information related to evaluation for BFR selection, etc. ) . Information may be passed on to other components of the device 605. The receiver 610 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The receiver 610 may utilize a single antenna or a set of antennas.

The communications manager 615 may be an example of aspects of the communications manager 515 as described herein. The communications manager 615 may include a RSRP manager 620, a candidate beam identifier 625, a ranking component 630, a beam selector 635, and a random access controller 640. The communications manager 615 may be an example of aspects of the communications manager 810 described herein.

The RSRP manager 620 may measure a set of receive powers for a corresponding set of beams. The candidate beam identifier 625 may identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold. The ranking component 630 may rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam. The beam selector 635 may determine, based on the ranking, a selected candidate beam. The random access controller 640 may perform a random access procedure using the selected candidate beam.

The transmitter 645 may transmit signals generated by other components of the device 605. In some examples, the transmitter 645 may be collocated with a receiver 610 in a transceiver module. For example, the transmitter 645 may be an example of aspects of the transceiver 820 described with reference to FIG. 8. The transmitter 645 may utilize a single antenna or a set of antennas.

FIG. 7 shows a block diagram 700 of a communications manager 705 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The communications manager 705 may be an example of aspects of a communications manager 515, a communications manager 615, or a communications manager 810 described herein. The communications manager 705 may include a RSRP manager 710, a candidate beam identifier 715, a ranking component 720, a beam selector 725, a random access controller 730, a coverage identifier 735, a SNR manager 740, a beam evaluator 745, a summation component 750, a configuration manager 755, a beam recovery component 760, and a SSB manager 765. Each of these modules may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The RSRP manager 710 may measure a set of receive powers for a corresponding set of beams.

The candidate beam identifier 715 may identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold.

The ranking component 720 may rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam. In some examples, the ranking component 720 may rank the sums for each candidate beam. In some cases, the one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.

The beam selector 725 may determine, based on the ranking, a selected candidate beam. In some examples, the beam selector 725 may select the candidate beam associated with a highest rank. In some examples, the beam selector 725 may select the one or more candidate beams based on the receive power of each of the one or more candidate beams being greater than the receive power threshold.

The random access controller 730 may perform a random access procedure using the selected candidate beam.

The coverage identifier 735 may determine a weighting parameter associated with a network coverage quality based on one or more channel condition measurements (e.g., SNR measurements) or the receive power threshold. In some cases, the weighting parameter ranges from zero to one.

The SNR manager 740 may measure the channel condition of each of the one or more candidate beams. In some cases, the channel condition includes a signal to noise ratio.

The beam evaluator 745 may apply the weighting parameter to the channel condition of each of the one or more candidate beams.

The summation component 750 may sum, for each candidate beam, a respective receive power with a respective weighted channel condition.

The configuration manager 755 may receive a receive power configuration indicating the receive power threshold. In some examples, the configuration manager 755 may operate in a radio resource configuration connected state. In some examples, the configuration manager 755 may receive a radio resource control message including the receive power configuration. In some cases, the receive power configuration includes a beam recovery configuration, and where the receive power threshold includes a layer one reference signal receive power threshold.

The beam recovery component 760 may determine a current beam quality is below a beam quality threshold, where the measuring of the set of receive powers for the corresponding set of beams is based on the current beam quality being below the beam quality threshold.

The SSB manager 765 may measure the receive power of a synchronization signal block of each of the set of beams based on the receive power configuration.

FIG. 8 shows a diagram of a system 800 including a device 805 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The device 805 may be an example of or include the components of device 505, device 605, or a UE 115 as described herein. The device 805 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, including a communications manager 810, an I/O controller 815, a transceiver 820, an antenna 825, memory 830, and a processor 840. These components may be in electronic communication via one or more buses (e.g., bus 845) .

The communications manager 810 may measure a set of receive powers for a corresponding set of beams, identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold, rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam, determine, based on the ranking, a selected candidate beam, and perform a random access procedure using the selected candidate beam.

The I/O controller 815 may manage input and output signals for the device 805. The I/O controller 815 may also manage peripherals not integrated into the device 805. In some cases, the I/O controller 815 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 815 may utilize an operating system such as

or another known operating system. In other cases, the I/O controller 815 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 815 may be implemented as part of a processor. In some cases, a user may interact with the device 805 via the I/O controller 815 or via hardware components controlled by the I/O controller 815.

The transceiver 820 may communicate bi-directionally, via one or more antennas, wired, or wireless links as described herein. For example, the transceiver 820 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 820 may also include a modem to modulate the packets and provide the modulated packets to the antennas for transmission, and to demodulate packets received from the antennas.

In some cases, the wireless device may include a single antenna 825. However, in some cases the device may have more than one antenna 825, which may be capable of concurrently transmitting or receiving multiple wireless transmissions.

The memory 830 may include RAM and ROM. The memory 830 may store computer-readable, computer-executable code 835 including instructions that, when executed, cause the processor to perform various functions described herein. In some cases, the memory 830 may contain, among other things, a basic input/output system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 840 may include an intelligent hardware device, (e.g., a general-purpose processor, a digital signal processor (DSP) , a CPU, a microcontroller, an ASIC, a field programable gate array (FPGA) , a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 840 may be configured to operate a memory array using a memory controller. In other cases, a memory controller may be integrated into the processor 840. The processor 840 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 830) to cause the device 805 to perform various functions (e.g., functions or tasks supporting evaluation for BFR selection) .

The code 835 may include instructions to implement aspects of the present disclosure, including instructions to support wireless communications. The code 835 may be stored in a non-transitory computer-readable medium such as system memory or other type of memory. In some cases, the code 835 may not be directly executable by the processor 840 but may cause a computer (e.g., when compiled and executed) to perform functions described herein.

FIG. 9 shows a flowchart illustrating a method 900 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The operations of method 900 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 900 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 905, the UE may measure a set of receive powers for a corresponding set of beams. The operations of 905 may be performed according to the methods described herein. In some examples, aspects of the operations of 905 may be performed by a RSRP manager as described with reference to FIGs. 5 through 8.

At 910, the UE may identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold. The operations of 910 may be performed according to the methods described herein. In some examples, aspects of the operations of 910 may be performed by a candidate beam identifier as described with reference to FIGs. 5 through 8.

At 915, the UE may rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam. The operations of 915 may be performed according to the methods described herein. In some examples, aspects of the operations of 915 may be performed by a ranking component as described with reference to FIGs. 5 through 8.

At 920, the UE may determine, based on the ranking, a selected candidate beam. The operations of 920 may be performed according to the methods described herein. In some examples, aspects of the operations of 920 may be performed by a beam selector as described with reference to FIGs. 5 through 8.

At 925, the UE may perform a random access procedure using the selected candidate beam. The operations of 925 may be performed according to the methods described herein. In some examples, aspects of the operations of 925 may be performed by a random access controller as described with reference to FIGs. 5 through 8.

FIG. 10 shows a flowchart illustrating a method 1000 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The operations of method 1000 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1000 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1005, the UE may measure a set of receive powers for a corresponding set of beams. The operations of 1005 may be performed according to the methods described herein. In some examples, aspects of the operations of 1005 may be performed by a RSRP manager as described with reference to FIGs. 5 through 8.

At 1010, the UE may identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold. The operations of 1010 may be performed according to the methods described herein. In some examples, aspects of the operations of 1010 may be performed by a candidate beam identifier as described with reference to FIGs. 5 through 8.

At 1015, the UE may determine a weighting parameter associated with a network coverage quality based on one or more channel condition measurements (e.g., SNR measurements) or the receive power threshold. The operations of 1015 may be performed according to the methods described herein. In some examples, aspects of the operations of 1015 may be performed by a coverage identifier as described with reference to FIGs. 5 through 8.

At 1020, the UE may measure the channel condition of each of the one or more candidate beams. The operations of 1020 may be performed according to the methods described herein. In some examples, aspects of the operations of 1020 may be performed by a SNR manager as described with reference to FIGs. 5 through 8.

At 1025, the UE may apply the weighting parameter to the channel condition of each of the one or more candidate beams. The operations of 1025 may be performed according to the methods described herein. In some examples, aspects of the operations of 1025 may be performed by a beam evaluator as described with reference to FIGs. 5 through 8.

At 1030, the UE may rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam. The operations of 1030 may be performed according to the methods described herein. In some examples, aspects of the operations of 1030 may be performed by a ranking component as described with reference to FIGs. 5 through 8.

At 1035, the UE may determine, based on the ranking, a selected candidate beam. The operations of 1035 may be performed according to the methods described herein. In some examples, aspects of the operations of 1035 may be performed by a beam selector as described with reference to FIGs. 5 through 8.

At 1040, the UE may perform a random access procedure using the selected candidate beam. The operations of 1040 may be performed according to the methods described herein. In some examples, aspects of the operations of 1040 may be performed by a random access controller as described with reference to FIGs. 5 through 8.

FIG. 11 shows a flowchart illustrating a method 1100 that supports evaluation for BFR selection in accordance with aspects of the present disclosure. The operations of method 1100 may be implemented by a UE 115 or its components as described herein. For example, the operations of method 1100 may be performed by a communications manager as described with reference to FIGs. 5 through 8. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the functions described herein. Additionally or alternatively, a UE may perform aspects of the functions described herein using special-purpose hardware.

At 1105, the UE may measure a set of receive powers for a corresponding set of beams. The operations of 1105 may be performed according to the methods described herein. In some examples, aspects of the operations of 1105 may be performed by a RSRP manager as described with reference to FIGs. 5 through 8.

At 1110, the UE may identify one or more candidate beams from the set of beams whose receive powers satisfy a receive power threshold. The operations of 1110 may be performed according to the methods described herein. In some examples, aspects of the operations of 1110 may be performed by a candidate beam identifier as described with reference to FIGs. 5 through 8.

At 1115, the UE may sum, for each candidate beam, a respective receive power with a respective weighted channel condition. The operations of 1115 may be performed according to the methods described herein. In some examples, aspects of the operations of 1115 may be performed by a summation component as described with reference to FIGs. 5 through 8.

At 1120, the UE may rank the sums for each candidate beam. The operations of 1120 may be performed according to the methods described herein. In some examples, aspects of the operations of 1120 may be performed by a ranking component as described with reference to FIGs. 5 through 8.

At 1125, the UE may rank the one or more candidate beams based on the receive power of each candidate beam and a weighted channel condition for each candidate beam. The operations of 1125 may be performed according to the methods described herein. In some examples, aspects of the operations of 1125 may be performed by a ranking component as described with reference to FIGs. 5 through 8.

At 1130, the UE may determine, based on the ranking, a selected candidate beam. The operations of 1130 may be performed according to the methods described herein. In some examples, aspects of the operations of 1130 may be performed by a beam selector as described with reference to FIGs. 5 through 8.

At 1135, the UE may perform a random access procedure using the selected candidate beam. The operations of 1135 may be performed according to the methods described herein. In some examples, aspects of the operations of 1135 may be performed by a random access controller as described with reference to FIGs. 5 through 8.

It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include random-access memory (RAM) , read-only memory (ROM) , electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

A method for wireless communications at a user equipment (UE) , comprising:

measuring a plurality of receive powers for a corresponding plurality of beams;

identifying one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold;

ranking the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam;

determining, based at least in part on the ranking, a selected candidate beam; and

performing a random access procedure using the selected candidate beam.
The method of claim 1, further comprising:

determining a weighting parameter associated with a network coverage quality based at least in part on one or more channel condition measurements or the receive power threshold.
The method of claim 2, wherein ranking the one or more candidate beams further comprises:

measuring the channel condition of each of the one or more candidate beams; and

applying the weighting parameter to the channel condition of each of the one or more candidate beams.
The method of claim 2, wherein the weighting parameter ranges from zero to one.
The method of claim 1, wherein ranking the one or more candidate beams further comprises:

summing, for each candidate beam, a respective receive power with a respective weighted channel condition; and

ranking the sums for each candidate beam.
The method of claim 1, wherein determining the selected candidate beam further comprises:

selecting the candidate beam associated with a highest rank.
The method of claim 6, wherein the one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.
The method of claim 1, further comprising:

receiving a receive power configuration indicating the receive power threshold.
The method of claim 8, wherein the receive power configuration comprises a beam recovery configuration, and wherein the receive power threshold comprises a layer one reference signal receive power threshold.
The method of claim 8, further comprising:

operating in a radio resource configuration connected state; and

determining a current beam quality is below a beam quality threshold, wherein the measuring of the plurality of receive powers for the corresponding plurality of beams is based at least in part on the current beam quality being below the beam quality threshold.
The method of claim 8, further comprising:

measuring the receive power of a synchronization signal block of each of the plurality of beams based at least in part on the receive power configuration; and

selecting the one or more candidate beams based at least in part on the receive power of each of the one or more candidate beams being greater than the receive power threshold.
The method of claim 8, wherein receiving the receive power configuration further comprises:

receiving a radio resource control message comprising the receive power configuration.
The method of claim 1, wherein the channel condition comprises a signal to noise ratio.
An apparatus for wireless communications at a user equipment (UE) , comprising:

a processor,

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

measure a plurality of receive powers for a corresponding plurality of beams;

identify one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold;

rank the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam;

determine, based at least in part on the ranking, a selected candidate beam; and

perform a random access procedure using the selected candidate beam.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

determine a weighting parameter associated with a network coverage quality based at least in part on one or more channel condition measurements or the receive power threshold.
The apparatus of claim 15, wherein the instructions to rank the one or more candidate beams further are executable by the processor to cause the apparatus to:

measure the channel condition of each of the one or more candidate beams; and

apply the weighting parameter to the channel condition of each of the one or more candidate beams.
The apparatus of claim 15, wherein the weighting parameter ranges from zero to one.
The apparatus of claim 14, wherein the instructions to rank the one or more candidate beams further are executable by the processor to cause the apparatus to:

sum, for each candidate beam, a respective receive power with a respective weighted channel condition; and

rank the sums for each candidate beam.
The apparatus of claim 14, wherein the instructions to determine the selected candidate beam further are executable by the processor to cause the apparatus to:

select the candidate beam associated with a highest rank.
The apparatus of claim 19, wherein the one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

receive a receive power configuration indicating the receive power threshold.
The apparatus of claim 21, wherein the receive power configuration comprises a beam recovery configuration, and wherein the receive power threshold comprises a layer one reference signal receive power threshold.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

operate in a radio resource configuration connected state; and

determine a current beam quality is below a beam quality threshold, wherein the measuring of the plurality of receive powers for the corresponding plurality of beams is based at least in part on the current beam quality being below the beam quality threshold.
The apparatus of claim 21, wherein the instructions are further executable by the processor to cause the apparatus to:

measure the receive power of a synchronization signal block of each of the plurality of beams based at least in part on the receive power configuration; and

select the one or more candidate beams based at least in part on the receive power of each of the one or more candidate beams being greater than the receive power threshold.
The apparatus of claim 21, wherein the instructions to receive the receive power configuration further are executable by the processor to cause the apparatus to:

receive a radio resource control message comprising the receive power configuration.
The apparatus of claim 14, wherein the channel condition comprises a signal to noise ratio.
An apparatus for wireless communications at a user equipment (UE) , comprising:

means for measuring a plurality of receive powers for a corresponding plurality of beams;

means for identifying one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold;

means for ranking the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam;

means for determining, based at least in part on the ranking, a selected candidate beam; and

means for performing a random access procedure using the selected candidate beam.
The apparatus of claim 27, further comprising:

means for determining a weighting parameter associated with a network coverage quality based at least in part on one or more channel condition measurements or the receive power threshold.
The apparatus of claim 28, wherein the means for ranking the one or more candidate beams further comprises:

means for measuring the channel condition of each of the one or more candidate beams; and

means for applying the weighting parameter to the channel condition of each of the one or more candidate beams.
The apparatus of claim 28, wherein the weighting parameter ranges from zero to one.
The apparatus of claim 27, wherein the means for ranking the one or more candidate beams further comprises:

means for summing, for each candidate beam, a respective receive power with a respective weighted channel condition; and

means for ranking the sums for each candidate beam.
The apparatus of claim 27, wherein the means for determining the selected candidate beam further comprises:

means for selecting the candidate beam associated with a highest rank.
The apparatus of claim 32, wherein the one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.
The apparatus of claim 27, further comprising:

means for receiving a receive power configuration indicating the receive power threshold.
The apparatus of claim 34, wherein the receive power configuration comprises a beam recovery configuration, and wherein the receive power threshold comprises a layer one reference signal receive power threshold.
The apparatus of claim 34, further comprising:

means for operating in a radio resource configuration connected state; and

means for determining a current beam quality is below a beam quality threshold, wherein the measuring of the plurality of receive powers for the corresponding plurality of beams is based at least in part on the current beam quality being below the beam quality threshold.
The apparatus of claim 34, further comprising:

means for measuring the receive power of a synchronization signal block of each of the plurality of beams based at least in part on the receive power configuration; and

means for selecting the one or more candidate beams based at least in part on the receive power of each of the one or more candidate beams being greater than the receive power threshold.
The apparatus of claim 34, wherein the means for receiving the receive power configuration further comprises:

means for receiving a radio resource control message comprising the receive power configuration.
The apparatus of claim 27, wherein the channel condition comprises a signal to noise ratio.
A non-transitory computer-readable medium storing code for wireless communications at a user equipment (UE) , the code comprising instructions executable by a processor to:

measure a plurality of receive powers for a corresponding plurality of beams;

identify one or more candidate beams from the plurality of beams whose receive powers satisfy a receive power threshold;

rank the one or more candidate beams based at least in part on the receive power of each candidate beam and a weighted channel condition for each candidate beam;

determine, based at least in part on the ranking, a selected candidate beam; and

perform a random access procedure using the selected candidate beam.
The non-transitory computer-readable medium of claim 40, wherein the instructions are further executable to:

determine a weighting parameter associated with a network coverage quality based at least in part on one or more channel condition measurements or the receive power threshold.
The non-transitory computer-readable medium of claim 41, wherein the instructions to rank the one or more candidate beams further are executable to:

measure the channel condition of each of the one or more candidate beams; and

apply the weighting parameter to the channel condition of each of the one or more candidate beams.
The non-transitory computer-readable medium of claim 41, wherein the weighting parameter ranges from zero to one.
The non-transitory computer-readable medium of claim 40, wherein the instructions to rank the one or more candidate beams further are executable to:

sum, for each candidate beam, a respective receive power with a respective weighted channel condition; and

rank the sums for each candidate beam.
The non-transitory computer-readable medium of claim 40, wherein the instructions to determine the selected candidate beam further are executable to:

select the candidate beam associated with a highest rank.
The non-transitory computer-readable medium of claim 45, wherein the one or more candidate beams are ranked from a largest sum of the receive power and the weighted channel condition for each candidate beam to the smallest sum of the receive power and the weighted channel condition for each candidate beam, the highest rank being associated with the largest sum.
The non-transitory computer-readable medium of claim 40, wherein the instructions are further executable to:

receive a receive power configuration indicating the receive power threshold.
The non-transitory computer-readable medium of claim 47, wherein the receive power configuration comprises a beam recovery configuration, and wherein the receive power threshold comprises a layer one reference signal receive power threshold.
The non-transitory computer-readable medium of claim 47, wherein the instructions are further executable to:

operate in a radio resource configuration connected state; and

determine a current beam quality is below a beam quality threshold, wherein the measuring of the plurality of receive powers for the corresponding plurality of beams is based at least in part on the current beam quality being below the beam quality threshold.
The non-transitory computer-readable medium of claim 47, wherein the instructions are further executable to:

measure the receive power of a synchronization signal block of each of the plurality of beams based at least in part on the receive power configuration; and

select the one or more candidate beams based at least in part on the receive power of each of the one or more candidate beams being greater than the receive power threshold.
The non-transitory computer-readable medium of claim 47, wherein the instructions to receive the receive power configuration further are executable to:

receive a radio resource control message comprising the receive power configuration.
The non-transitory computer-readable medium of claim 40, wherein the channel condition comprises a signal to noise ratio.