Transmit-beam selection for beamforming

Abstract

A device having a codebook specifying multiple Rx-Tx beam pairs each defining respectively an Rx beam and a Tx beam will maintain, per beam pair, an Rx signal-strength bias value applicable when using Rx signal strength of the beam pair as a basis for Tx-beam selection. As to a transmission received from a remote entity, the device will, for each beam pair, measure an Rx signal strength of the transmission as received using the Rx beam of the beam pair and apply the Rx signal-strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair. The device will then select one of the beam pairs based on that selected pair having a highest biased Rx signal strength and will configure itself to use the Tx beam of the selected beam pair for transmission to the remote entity.

Description

Transmit-Beam Selection for BeamformingBACKGROUND

[0001] Beamforming plays an important role in modern wireless communication systems such as cellular and Wi-Fi systems for instance, by providing more precise wireless communication channels that may support increased data rates and more reliable communication and may greatly improve spectral efficiency, as compared with non- beamformed wireless broadcast communications.

[0002] To facilitate beamforming, a device could be equipped with an antenna array having two or more spaced-apart antenna elements through which to wirelessly communicate a signal, and the device could adjust the phase and amplitude of the signal respectively passing through each antenna element, so that destructive and constructive waveform interference would work to focus the communication cooperatively in a particular direction, e.g., in relation to a plane of the array. The per-element amplitude and phase settings (and / or other such settings) that the device applies in order to focus communication in a particular direction cooperatively define an associated “beamforming vector”.

[0003] This beamforming process can work for both transmission and reception. For transmission, the phase and amplitude settings of the antenna elements can cause a combination of waveforms as transmitted from the array to be focused in a particular direction. And for reception, the phase and amplitude settings can cause a combination of the received waveforms to be focused on signals arriving from a particular direction.

[0004] While beamforming would ideally direct communications precisely in a given direction, imperfections in the process will typically result at best in a beam pattern or antenna pattern that is generally directed in the desired direction but that also encompasses some extent of communication in other directions.

[0005] Figure 1 is a simplified two-dimensional representation of an example antenna pattern 100 that a device 102 may create by applying an associated beamforming vector in an effort to focus wireless communication in a particular direction. The borders of this antenna pattern represent gain or strength of wireless communication, with points farther from the device representing higher gain, and points closer to the device representing lower gain. As shown, this example antenna pattern generally focuses wireless communication in a “boresight” direction 104, defining a main lobe 106 or primary lobe of the antenna pattern.However, the antenna pattern also defines various side, back, or other secondary lobes, such as lobes 108, that wireless communication by the device would also encompass.

[0006] A representative device may be provisioned with a “beamforming codebook” that predefines multiple antenna patterns as respective “beams” selectively available for use by the device, specifying each beam by a respective beamforming vector. In particular, this beamforming codebook may define multiple different transmit (“Tx”) beams usable by the device to engage in beamformed transmission and multiple different receive (“Rx”) beams usable by the device to engage in beamformed reception. The codebook may label each of these beams with a respective index number for reference.

[0007] To facilitate bidirectional communication, the codebook may also specify pairs of these Tx and Rx beams, with each beam pair being a pair of a Tx beam and an Rx beam having largely the same direction as each other. For instance, the codebook could define a quantity N of Tx-Rx beam pairs by defining N indexed-numbered Tx beams and N correspondingly index-numbered Rx beams, where N is an integer such as six, eight, ten, or twenty, among other possibilities. Thus, according to the codebook, each Rx beam having a given index number could correspond respectively with a Tx beam having the same index number.

[0008] This pairing of Rx and Tx beams can enable the device to readily configure itself to use the Rx beam and Tx beam of a given pair in order to facilitate bidirectional communication in a given direction. To do so dynamically for communication with another entity, the device could test its reception with each of its defined Rx beams and determine which Rx beam has the strongest receive-signal strength. In particular, as the device receives wireless transmission from the other entity, arriving with a particular angle of incidence at the device, the device could cycle through each of its codebook-defined Rx beams, measuring its receive-signal strength respectively with each Rx beam. The device could then select the Rx beam having the strongest measured receive-signal strength, which may likely be the Rx beam whose main beam is most closely aligned with the angle of incidence, i.e., whose antenna pattern has peak gain in that direction. And the device could then configure itself to use the Tx beam that the codebook pairs with that Rx beam, i.e., the Tx beam with the same index number, whose main beam may similarly be most closely aligned with the angle of incidence, to facilitate transmitting in largely the same direction back to the other entity.

[0009] Unfortunately, however, in some implementations (such as but not limited to millimeter-wave implementations), the Tx and Rx beams in each beam pair defined by thedevice’s beamforming codebook may be different than each other. In particular, for each beam pair, the codebook may define a beamforming vector for the Tx beam and a different beamforming vector for the Rx beam. One reason for this may be that the device is configured with different circuitry for processing outgoing radio-frequency (RF) transmissions than for processing incoming RF transmissions. For instance, the device may have different amplifiers and signal processing components respectively for Tx processing and for Rx processing.

[0010] As a result, for each beam pair defined by the device’s codebook, even though the Tx and Rx antenna patterns may have similar or the same boresight direction as each other, the Tx and Rx antenna patterns may differ from each other in some substantive ways. By way of example, even though some of the Tx antenna-pattern lobes may align in direction with some of the Rx antenna-pattern lobes, the Tx lobes may have different gain than the Rx lobes, possibly lower gain such that it may be possible for the device to receive from a given distance but it may be impossible for the device to transmit at that same distance. As another example, some of the lobes of one of the antenna patterns may be angularly offset from the lobes of the other antenna pattern, or there may be other differences between numbers and placement of lobes in the Tx and Rx antenna patterns, such that the device may be able to receive a strong signal at a given angle but may be unable to transmit at that same angle, or vice versa. Other differences between Tx and Rx antenna patterns per beam pair may be possible as well.

[0011] This difference between Tx and Rx antenna patterns per beam pair poses a technical issue with Tx beam selection. Simply selecting a Tx beam based on a determination that its paired Rx beam has the highest signal strength may not work well in some cases. For instance, it may be the case that the angle of incidence of the wireless transmission from the other entity is centered on a relatively strong lobe of one of the Rx beams in the device’s codebook but that the paired Tx beam in the codebook has much lower gain at that angle, and in a worst case possibly a null (e.g., zero or near-zero gain) at that angle. Thus, merely selecting the Tx beam corresponding with the highest-signal-strength Rx beam may result in poor Tx performance, such as weak or non-existent transmission in the relevant direction.

[0012] The present disclosure provides various improvements that may help to address this or other such problems in Tx beam selection. In one respect, disclosed is a mechanism for Tx beam selection that involves biasing measured receive-signal strength with an offset value separately and respectively preset per beam pair, so as to help make Rx beam selection a reasonable proxy for Tx beam selection given the difference between the Rx andTx antenna patterns per beam pair. Further, in another respect, disclosed is a mechanism for Tx beam selection that involves computing an angle of arrival (AoA) of wireless transmission from the other entity, based on an evaluation of receive-signal strengths of the multiple Rx beams in the codebook, and selecting the Tx beam whose antenna pattern has the strongest gain in the direction of that computed AoA.

[0013] As to use of bias values, for instance, disclosed is an example method for controlled beamforming by a device, where the device is configured with a beamforming codebook specifying multiple receive Rx-Tx beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antenna-pattern configurable for use by the device and (ii) a respective Tx beam having a respective Tx antenna-pattern configurable for use by the device.

[0014] In the example method, the device maintains, respectively per beam pair (e.g., as part of the codebook), an Rx signal-strength bias value that defines an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection. When the device then receives wireless transmission from a remote entity (i.e., an entity in wireless communication range of the device), the device then biases Rx signal strength for each of its beam pairs. In particular, respectively for each beam pair defined by the device’s codebook: (a) the device measures an Rx signal strength of the transmission as received using the Rx beam of the beam pair, and (b) the device applies the Rx signal-strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair. The device then selects one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs. And based on the selecting, the device configures itself to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

[0015] In another respect, disclosed is an example device that includes an antenna array having multiple array elements cooperatively configurable to facilitate Rx beamforming by the device and Tx beamforming by the device, at least one processor, and non-transitory data storage. The example device further includes beamforming codebook stored in the non- transitory data storage, with the beamforming codebook specifying multiple Rx-Tx beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antennapattern configuration of the antenna array and (ii) a respective Tx beam having a respective Tx antenna-pattern configuration of the antenna array. And the device includes bias data stored in the non-transitory data storage (possibly as part of the codebook), with the bias data including,respectively per beam pair, an Rx signal-strength bias value that defines an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection.

[0016] The device may further include program instructions stored in the non- transitory data storage and executable by the at least one processor to cause the device to carry out operations for controlled beamforming based on transmission received wirelessly by the device from a remote entity. For instance, the operations may include, respectively for each beam pair defined by the codebook, (a) measuring, by the device, an Rx signal strength of the transmission as received using the Rx beam of the beam pair and (b) applying, by the device, the Rx signal -strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair. Further, the operations may include selecting one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs. And the operations may include, based on the selecting, configuring the device to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

[0017] In yet another respect, disclosed is at least one non-transitory computer- readable medium having stored thereon program instructions executable by at least one processor of a device to cause the device to carry out operations such as those discussed above.

[0018] Further, in still another respect, disclosed is a system that includes various means for carrying out each of the operations described herein.

[0019] These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that the descriptions provided in this summary and below are intended to illustrate the invention by way of example only and not by way of limitation.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure l is a two-dimensional illustration of an example antenna pattern.

[0021] Figure 2 is a simplified block diagram of an example wireless communication network.

[0022] Figure 3 is a simplified block diagram of an example device.

[0023] Figure 4 is a simplified diagram of an RF integrated circuit and antenna structure.

[0024] Figure 5 is a flow chart illustrating an example method.DETAILED DESCRIPTION

[0025] The present disclosure will discuss example implementations in the context of the device being a cell phone or other portable wireless communication device. It will be understood, however, that various principles disclosed could apply in any of a variety of other contexts, such as where the device is a cellular base station, where the device is another type of cellular communication device, or with respect Wi-Fi or other wireless communications that may make use of beamforming, among other possibilities.

[0026] Further, it will be generally understood that the disclosed arrangements and processes are set forth for purposes of example only and may take various other forms. For instance, elements and operations can be re-ordered, distributed, replicated, combined, omitted, added, or otherwise modified. In addition, it will be understood that functions described herein as being carried out by one or more components could be implemented by and / or on behalf of those components, through hardware, firmware, and / or software, such as by one or more processing units executing program instructions or the like.1. Example Cellular Wireless Communications

[0027] A typical cellular wireless communication system includes multiple access nodes configured to serve user equipment devices (UEs) such as cell phones, tracking devices, wirelessly equipped personal computers, gaming devices, Internet of Things (loT) devices, and other wirelessly-equipped devices.

[0028] Each such access node may include an antenna structure and associated equipment that enables the access node to provide one or more cells each defining wireless coverage in which to serve UEs over a respective air-interface. Further, each access node may be coupled with a core network that includes infrastructure configured to support the access node’s service of UEs and that provides connectivity with a transport network such as the Internet. With this arrangement, when a UE is positioned within coverage of an access node, the UE may be able to engage in air-interface communication with the access node and may thereby be able to communicate through the access node, the core network, and the transport network with various remote servers and / or other entities.

[0029] A representative wireless communication network could operate in accordance with one or more radio access technologies (RATs), which may define the physical structure of the air interface between access nodes and UEs and may also define associated procedures for handling service of UEs.

[0030] The wireless industry has evolved over the years to define various generations of RATs and continues to evolve to define new generations of RATs. Recent examples of these RATs include, without limitation, (i) “4G” Long Term Evolution (LTE), which facilitates mobile broadband service using technologies such as orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO), (ii) “5G NR” (5G New Radio), which may use a more scalable OFDM air interface and other advanced features to support higher data rates and advanced applications, and (iii) “6G”, which might support even higher data rates, possibly by making use of millimeter wave and Terahertz spectrum.

[0031] Under such a RAT, the access node may be configured to provide each of its one or more cells on a respective radio frequency (RF) carrier that defines a downlink channel for carrying communications from the access node to UEs and an uplink channel for carrying communications from UEs to the access node. Each such carrier, and thus each such cell, may be either frequency division duplex (FDD), with separate frequency channels defined respectively for downlink and uplink use, or time division duplex (TDD), with a single frequency channel multiplexed over time between downlink and uplink use. Further, each such frequency channel could be defined as a specific range of frequency having a bandwidth that defines how wide the carrier is in RF spectrum, extending from a low-end frequency to a high- end frequency.

[0032] Further, the downlink and uplink channels of each cell on which an access node provides service may be structured in a manner that defines physical air-interface resources for carrying both control signaling and user-plane communications between the access node and UEs. For instance, the air interface may be divided over time into frames, subframes, timeslots (slots), and symbol time segments (symbols), and over frequency into subcarriers, so as to define an array of resource elements each occupying a respective subcarrier and spanning a respective symbol time segment. Each resource element may then serve to carry data or other signaling (user-plane or control -plane) through modulation of the resource element’s subcarrier with an applicable modulation-and-coding scheme. Further, the air interface may be divided over time and channel bandwidth into physical resource blocks (PRBs), each of which may span a certain number of subcarriers (e.g., 12) in frequency and a certain duration (e.g., half of a timeslot) in time. In addition, certain resource elements in these PRBs may be reserved for particular use, such as to carry control signaling or to carry userplane data communications.

[0033] On the downlink, for instance, certain resource elements may cooperatively carry signaling from the access node that UEs could measure as a basis to gauge cell coverage strength. For instance, in certain resource elements, the access node could broadcast a synchronization signal block (SSB) or other reference signal that UEs could detect and measure to determine coverage strength. Further, other resource elements may cooperatively define a physical downlink control channel (PDCCH) for carrying downlink control signaling such as scheduling directives from the access node to UEs, and other resource elements may cooperatively define a physical downlink shared channel (PDSCH), which the access node could schedule for use on a PRB basis to carry user-plane data from the access node to served UEs.

[0034] On the uplink, on the other hand, certain resource elements may cooperatively define an access channel for carrying access requests from UEs to the access node. Further, other resource elements may cooperatively define a physical uplink control channel (PUCCH) for carrying various uplink signaling such as measurement reports and scheduling requests from UEs to the access node. Still further, other resource elements may cooperatively define a physical uplink shared channel (PUSCH), and the access node could schedule use of the PUSCH on a per PRB basis to carry user-plane data from served UEs to the access node.

[0035] Figure 2 is a simplified block diagram of an example cellular wireless communication system. As shown in Figure 2, the example system includes one or more access nodes 200 each configured to provide wireless coverage on one or more carriers defining one or more cells 202 that each have a downlink channel and an uplink channel. Each access node 200 may take various forms, such as an evolved Node-B (eNB) or a next generation Node-B (gNB), among other possibilities. As further shown, each of the one or more access nodes 200 may sit as a node on a core network 204, such as a 4G evolved packet core (EPC) network or a 5G core (5GC) network, among other possibilities, which provides connectivity with at least one transport network 206 such as the internet.

[0036] Shown within coverage of the one or more access nodes 200 is then an example UE 208, which could be a cell phone, a tracking device, a wirelessly equipped personal computer, a gaming device, an Internet of Things (loT) device, and / or another form of wirelessly-equipped device, whether or not technically “user” operated.

[0037] When a UE such as UE 208 enters into coverage of this wireless communication network, the UE would typically scan for the presence of a reference signalthat indicates the presence of wireless coverage, and for each reference signal that the UE finds, the UE may evaluate the reference signal to determine coverage strength of the associated cell. For instance, for each reference signal, the UE may determine a value of reference signal receive power (RSRP), which may be a linear average of power (in Watts) over the resource elements carrying the reference signal.

[0038] The UE may then select the cell providing the strongest such coverage, and if the coverage is strong enough, the UE may engage in signaling with the access node of that cell in order to establish an air-interface connection through which the access node could then serve the UE in that cell. For instance, the UE may engage in random-access signaling and connection signaling, such as Radio Resource Control (RRC) signaling, with the access node to establish an air-interface connection (e.g., an RRC connection) between the access node and the UE in the cell, transitioning the UE from an idle mode to a connected mode.

[0039] If the UE is not already registered for service with the core network, the UE may further engage in attach or registration signaling to register for service. For instance, the UE may send an attach or registration request to the access node, which the access node may forward to a controller entity within the core network. After authenticating the UE, the controller entity may then engage in a process to set up for the UE one or more bearers or service flows for carrying user-plane traffic to and from the UE.

[0040] Once the UE has an established air-interface connection with the access node and has one or more assigned bearers or service flows, the access node may then serve the UE with packet-data communications on the downlink and on the uplink.

[0041] As to the downlink, for instance, when packet data on the transport network arrives at the core network for transmission to the UE, the data may flow to the UE’s serving access node, which may buffer the data pending transmission of the data over the air of the UE. The access node may then assign one or more downlink PRBs of the UE’s serving cell to carry the data to the UE, and the access node may transmit to the UE a downlink control information (DCI) message defining a scheduling directive that specifies the assigned downlink PRB(s) and may transmit the data to the UE by modulating the data onto subcarriers of resource elements within the assigned downlink PRBs.

[0042] As to the uplink, on the other hand, when the UE has packet data to transmit on the transport network, the UE may buffer the data in a queue pending transmission of the data over the air to the access node, and the UE may transmit to the access node a scheduling request that includes a buffer status report (BSR) indicating how much data the UE has bufferedfor uplink transmission. The access may then assign one or more uplink PRBs of the UE’s serving cell to carry the data from the UE, and the access node may transmit to the UE a DCI message specifying the assigned uplink PRBs. The UE may then transmit the data to the access node by modulating the data onto subcarriers of the resource elements within the assigned uplink PRBs, and the access node may forward the data through the core network for ultimate output onto the transport network.

[0043] When a UE is being served with data communications by an access node, the UE and access node may also regularly engage in an acknowledgement and retransmission process to help ensure successful receipt of scheduled data communications. This is typically a hybrid automatic repeat request (HARQ) process, with specifics for both uplink and downlink transmissions.

[0044] With uplink HARQ, when the access node schedules uplink transmission from the UE, (i) the access node may include in its DCI message to the UE a HARQ process number, (ii) the access node may then determine whether the access node successfully receives the scheduled uplink transmission from the UE, and (iii) if the access node does not successfully receive the scheduled uplink transmission, the access node may direct the UE to retransmit the data, by sending to the UE a new DCI message that designates the same HARQ process number.

[0045] With downlink HARQ, similarly, when the access node schedules downlink transmission to the UE, (i) the access node may likewise include in its DCI message to the UE a HARQ process number, (ii) the UE may then determine whether the UE successfully receives the scheduled downlink transmission from the access node, and (iii) the UE may then transmit a HARQ positive or negative acknowledgement accordingly to the access node. If the UE successfully receives the data transmission, then the UE may send a positive acknowledgement (ACK). Whereas, if the UE does not successfully receive the data transmission, then the UE may send a negative acknowledgement (NACK), in response to which the access node may then engage in re-transmission, likewise sending to the UE a new DCI message that designates the same HARQ process number.

[0046] In addition, when a UE is served by an access node, the UE and access node may regularly engage in an uplink power-control process to help control the transmit power that the UE uses for its uplink transmission. In an example power control process, as the UE engages in transmissions to the access node, the access node may compare receive strength of those transmissions with a defined signal -strength set point and may accordingly send power-control commands to the UE to cause the UE to adjust its transmit power. These power-control commands may take the form of designated bit values in DCI messages that the access node sends to the UE.

[0047] Thus, when the access node determines that the received-signal strength from the UE is greater than the set point, the access node may direct the UE to decrease the UE’s transmit power level by sending to the UE a power-down command, in response to which the UE would decrease the overall power of its uplink transmission. And when the access node determines that the received-signal strength from the UE is less than the set point, the access node may direct the UE to increase the UE’s transmit power level by sending to the UE a power-up command, in response to which the UE would increase the overall power of its uplink transmission.2. Example UE and Associated Structure

[0048] Figure 3 is a simplified block diagram of an example UE, as a representative device that could be arranged to carry out disclosed operations related to Tx beam selection. Namely, Figure 3 shows some of the components that the example UE could include to facilitate carrying out the disclosed operations.

[0049] As shown, the UE may include a host processor 300, non-transitory data storage 302, and a wireless communication interface 304. These components could be integrated together and / or communicatively linked together in various ways. For instance, the components could be linked together through a system bus, network, or other connection mechanism 306. Alternatively, various integrations and other arrangements are possible.

[0050] The host processor 300, which may be a central processing unit (CPU) or other processor of the device, could comprise one or more general purpose processors (e.g., one or more microprocessors, etc.) and / or one or more special-purpose processors (e.g., digital signal processors, application-specific integrated circuits, etc.) Further, the non-transitory data storage 302 could comprise one or more volatile and / or non-volatile storage components (e.g., optical, magnetic, or flash storage, RAM, ROM, EPROM, EEPROM, cache memory, and / or other computer-readable media, etc.), possibly integrated in whole or in part with the host processor 300. As shown, the non-transitory data storage 302 may then store program instructions 308, which may be executable by the host processor 300 to carry out various operations described herein. Further, the non-transitory data storage 302 may store reference data 310, which could include a beamforming codebook 312 as discussed above for instance.

[0051] The wireless communication interface 304 could comprise one or more modules (e.g., one or more chipsets) supporting wireless communication between the UE and an access node according to one or more RATs, such as 4G LTE, 5G NR, and / or one or more other protocols. In an example implementation, the wireless communication interface 304 could comprise a radio frequency integrated circuit (RFIC) 314 and an antenna structure 316. The RFIC 314 could include various radios, amplifiers, filters, and / or other components to facilitate processing of outbound signals to be wirelessly transmitted by the antenna structure 316 and to facilitate processing of inbound signals wirelessly received by the antenna structure 316. The antenna structure 316 may then comprise an antenna array, including multiple spacedapart antenna elements (e.g., individual antennas) configured to support air-interface communications.

[0052] In the example implementation, each element of the antenna structure 316 may support dual-pole RF communication, generally understood to include a “vertical” (V) polarity and an orthogonal “horizontal” (H) polarity, which may help support increased data throughput or other uses. The antenna elements could be structured in various ways to provide this dual-polarity. Further, the RFIC 314 could correspondingly be structured in various ways to support the dual-polarity for both Tx and Rx operation.

[0053] Figure 4 depicts one of many possible example arrangements to facilitate this. In the arrangement of Figure 4, the antenna structure is shown as a patch array 400, where each antenna element is a patch antenna configured with H and V connections, and the RFIC is shown with separate RF chains for Tx and Rx operation respectively for each polarity of each patch antenna (i.e., respectively for each polarity of each antenna element). The example arrangement shows the array including four patch antennas by way of example, though it will be understood that an example antenna array could include a different number of antenna elements. Further, it will also be understood that the antenna elements of the example array could alternatively be single-polarity and could take other forms.

[0054] In the simplified arrangement shown, for each polarity of each antenna element on the Tx side, the example RFIC includes a modulator 402 for modulating an outbound signal onto an RF carrier, a power amplifier 404 for amplifying the outbound signal, and a phase and amplitude beamformer 406 to control output phase and amplitude of the signal that would feed to the antenna element to be wirelessly transmitted. Further, for each polarity of each antenna element on the Rx side, the RFIC includes a low noise amplifier (LNA) 408 to amplify wirelessly-received inbound signals for processing, a phase and amplitude beamformer410 to control input phase and amplitude for the antenna element, and a demodulator 412 for demodulating the inbound signals.

[0055] Figure 4 further shows the RFIC including its own processor 414 and non- transitory data storage 416, which may alternatively or additionally be arranged to carry out some or all of the presently disclosed operations. The RFIC processor 414 may similarly comprise one or more general purpose processors (e.g., one or more microprocessors, etc.) and / or one or more special-purpose processors (e.g., digital signal processors, applicationspecific integrated circuits, etc.) Further, the non-transitory data storage 416 may similarly comprise one or more volatile and / or non-volatile storage components (e.g., optical, magnetic, or flash storage, RAM, ROM, EPROM, EEPROM, cache memory, and / or other computer- readable media, etc.), possibly integrated in whole or in part with the processor 414. In addition, as shown, the non-transitory data storage 416 may similarly store program instructions 418, which may be executable by the RFIC processor 414 to carry out various operations described herein. Further, the non-transitory data storage 416 may store reference data, which could similarly include a beamforming codebook 420 as discussed above for instance.

[0056] In accordance with the present disclosure as noted above, the beamforming codebook of the UE may define multiple Rx-Tx beam pairs, each including an Rx beam with an associated Rx beamforming vector that can be applied to control amplitude and phase on a per-antenna-element basis (possibly with the same control applied to H and V polarities of a given element in a dual-polarity arrangement). For instance, as noted above, the beamforming codebook may define six, eight, ten, or twenty, or another number of such beam pairs, each of which may be established through engineering evaluation of the UE model, among other possibilities.

[0057] In an example implementation where the host processor 300 of the UE controls implementation of various described operations, the host processor 300 may engage in control signaling communication with the RFIC processor 414. For instance, the host processor may direct the RFIC processor 414 to apply particular beamforming vectors (e.g., as amplitude and phase settings respectively per antenna element) for Rx and Tx beams defined by the UE’s beamforming codebook, and the RFIC processor 414 may control beamforming accordingly. Further, the RFIC processor 414 may report to the host processor 300 information such as receive-signal strength per Rx beam, to enable the host processor to carry out Tx beam selection, among other operations.

[0058] Alternatively, in an example implementation where the RFIC processor 414 itself controls implementation of various described operations, the RFIC processor 414 may do so without control communication with the host processor 300. Further, numerous other allocations and division of responsibility among these and / or other UE components could be possible as well.3. Example Operations

[0059] Various example implementations according to the present disclosure may involve the UE applying an advanced analysis of receive-signal strength on the UE’s various available Rx beams, as a basis to select a Tx beam for the UE to use for transmission to another entity, such as to an access node 200 for instance.

[0060] To facilitate this, the UE may measure its receive-signal strength respectively using each of the UE’s available Rx beams. For instance, the UE could programmatically cycle through each of the Rx beams defined by the UE’s beamforming codebook and, for each Rx beam, (i) apply the Rx beam’ s associated Rx beamforming vector to the UE’ s antenna elements and (ii) measure receive-signal strength, e.g., as a combined power level across the antenna elements, such as a sum of power received by the multiple antenna elements. For each Rx beam in a dual-polarity arrangement, the UE may apply the same beamforming vector for each polarity of the antenna elements, and the UE may measure its receive-signal strength per polarity, thus measuring receive-signal strength for the horizontal polarity and separately measuring receive-signal strength for the vertical polarity.

[0061] The UE could do this as the UE receives wireless transmission from an access node 200, such as when the UE receives a reference signal (e.g., SSB) broadcast by the access node, among other possibilities. The UE could measure receive-signal strength as RSRP as noted above, which may be a value in decibel-milliwatts (dBm). Alternatively, other receive signal-strength metrics could be used, such as signal-to-noise ratio (SNR), signal-to- interference-plus-noise ratio (SINR), or reference signal receive quality (RSRQ), among others. The UE could carry out this measurement using suitable elements in the UE’ s RF chains for instance.

[0062] In line with the discussion above, the present disclosure can provide for Tx beam selection in a scenario where there are substantive differences between the Rx beam and Tx beam antenna patterns respectively in each of one or more of the Rx-Tx beam pairs defined by the UE’s beamforming codebook. As noted, these differences may be specific to each beam pair and may include aspects such as difference in gain, differences in position of lobes, andoverall difference in antenna pattern, even if the Rx and Tx beams in each pair have been designed in an effort to support communication in largely the same direction as each other (e.g., with very similar or the same boresights).

[0063] As discussed above, one way to help overcome the technical problem of per- beam-pair difference between Rx and Tx beam antenna patterns is to have the UE apply perbeam -pair offsets to the receive-signal strength measured by the UE. For example, for each beam pair, the UE could be pre-provisioned with a respective RSRP bias value that is established specifically for that beam pair, to help make the UE’s measurement of RSRP as to the Rx beam of that pair be a reasonable proxy for controlling whether the UE will select the Tx beam of the pair for the UE’s use.

[0064] When comparing RSRP of the UE’s various Rx beams as a basis to select a Tx beam to use, the UE could thus measure RSRP of each Rx beam and could offset that measured RSRP by the RSRP bias value established for that beam pair, so as to compute a biased RSRP value. The UE’s comparison of Rx beams could then be a comparison of the Rx beams’ computed biased RSRP values. For instance, the UE may determine which Rx beam has the greatest (strongest) biased RSRP value, and based on that determination, the UE may select the Tx beam corresponding with that Rx beam and configure itself to use the selected Tx for transmission. Namely, the UE could apply to its antenna elements the Tx beamforming vector of the selected Tx beam to beamform using that Tx beam.

[0065] In a dual-polarity arrangement, as to each beam pair, this process could involve the UE combining together horizontal RSRP and vertical RSRP (e.g., adding in the decibel domain or multiplying in linear domain) to establish a representative RSRP value, and offsetting that representative RSRP value by the beam pair’s pre-established RSRP bias value to compute a biased RSRP value for the beam pair. The UE could then compare the biased RSRP values of the beam pairs as a basis to select the pair having the greatest biased RSRP value, and, based on that comparison, the UE could configure itself to use the Tx beam of the selected beam pair.

[0066] Alternatively, in the dual-polarity arrangement, as to each beam pair, the process could involve selecting one of the two polarities’ RSRPs based on that selected polarity’s RSRP being the greatest of the two polarities’ RSRPs, and using that selected polarity’s RSRP as the basis for comparison. In particular, separately as to each beam pair, the UE could compare the horizontal RSRP with the vertical RSRP and could select the one that is greater, and the UE could offset that selected RSRP by the beam pair’s pre-established RSRPbias value to compute a biased RSRP value for the beam pair. (In this process, it is possible that the biased RSRP value for one or more of the beam pairs may be based on the horizontal polarity while the biased RSRP value for one or more others of the beam pairs may be based on the vertical polarity.) The UE could then likewise compare the biased RSRP values of the beam pairs as a basis to select the pair having the greatest biased RSRP value, and, based on that comparison, the UE could configure itself to use the Tx beam of the selected beam pair.

[0067] In an example implementation, the RSRP bias value per Rx-Tx beam pair could be pre-established by engineering analysis of Rx and Tx performance of the UE (or of a representative UE of the same make / model) using the beam pair, to facilitate provisioning the UE with the RSRP bias values and thereby facilitate the present process. This analysis could take various forms.

[0068] By way of example, a test unit of the UE could be placed in an RF test environment on a gimbal, with a test access node antenna being in a fixed position in relation to the UE’s position, and the access node may be made to transmit a reference signal downlink to the UE and to evaluate uplink transmissions from the UE.

[0069] With this arrangement, for each Rx-Tx beam pair respectively, the roll, yaw, and pitch of the UE could be cycled through various sample directions in spherical coordinates in relation to the access node antenna. For each sample direction, (i) the UE could use the Rx beam of the pair to receive the downlink reference-signal from the access node and measure and record its RSRP, and (ii) the UE could use the Tx beam of the pair to transmit to the access node, and the access node could receive that transmission from the UE and record uplink receive- signal strength.

[0070] With these data points on a per direction basis for the beam pair, a computing system (e.g., a processor executing program instructions stored in non-transitory data storage) may then programmatically plot at least an approximation of the UE’s Rx antenna pattern and the UE’s Tx antenna pattern. Further, the computing system may compute for the beam pair an RSRP bias value based on a comparison of (i) the measured RSRP values measured at the various sample directions with (ii) the measured uplink receive-signal strengths measured at the various sample directions.

[0071] For instance, (i) for each sample direction, the computing system could compute the difference between the measured uplink receive-signal strength and the measured RSRP, and (ii) the computing system could then average those computed differences as the beam pair’s RSRP bias value. In a scenario where the Tx antenna pattern of the beam pair islargely the same as the Rx antenna pattern of the beam pair except for having a higher gain overall, this computed RSRP bias value may represent a linear difference in gain between the two antenna patterns. Whereas, in a scenario where the Tx antenna pattern of the beam pair differs from the Rx antenna pattern of the beam pair, this computed RSRP bias value may be a reasonable representation of the extent to which the two antenna patterns differ from each other.

[0072] As another example, a computing system could use a similar test setup to perform a cumulative-distribution-function (CDF) analysis as a basis to establish a set of RSRP bias values for the set of beam pairs defined by the beamforming codebook. For instance, the computing system could test various sets of RSRP values for the set of beam pairs, revising the set of RSRP values with gradient descent or the like to help establish a set of RSRP bias values for the set of beam pairs that is likely to result in a highest level of equivalent isotropic radiated power (EIRP) in a typical coverage scenario.

[0073] The computing system could start this CDF analysis by initializing the RSRP bias value for each beam pair to zero. The computing could then test the access-node’s receivesignal strength as a measure of the UE’s EIRP for each of the various sample directions in the test arrangement and could develop a CDF based on those EIRP measurements. In particular, for each sample direction, the computing system could have the UE select and configure itself with a Tx beam as described above, such as by determining which beam pair in the codebook has the highest biased RSRP value (here, the highest RSRP value, if the starting bias for each beam pair is zero) and selecting and configuring itself with the Tx beam of that beam pair, the computing system could have the UE transmit to the access node using that selected Tx beam and could have the access node measure and report the access node’s uplink receive-signal strength of that transmission, as a respective EIRP value. The computing system could then generate a CDF of those EIRP values, which could indicate the probability of each of various EIRP values (i.e., the probability given any randomly selected angle of incidence). Based on this generated CDF, the computing system could determine what the EIRP value is likely to be at a given probably level, such as 80% probability for instance.

[0074] The computing system could then randomly adjust the RSRP bias values of the set of beam pairs, with a positive or negative adjustment and possibly different adjustments for the different beam pairs, and the computing system could repeat the process just described, to see if the CDF performance improves, e.g., if the EIRP value at the same probability level increases. If the computing system determines that the CDF performance improves, then the computing system could iteratively adjust the RSRP bias values of the set of beam pairs in thesame direction (e.g., more positive, or more negative) and repeat the process, each time determining if the CDF performance improves further. Alternatively, if the computing system determines that an adjustment of RSRP bias values results in the CDF performance decreasing (e.g., EIRP at the same probability level decreasing), then the computing system could reverse its direction of adjustment (e.g., from positive to negative, or from negative to positive) or make other changes in the RSRP bias values and iteratively repeat the process. Through a gradient descent analysis or other process, the computing system could thereby settle on a set of RSRP bias values that provide a relatively best level of CDF performance.

[0075] Note also that, while the UE could ultimately select a Tx beam through the process described here, making use of the biased RSRP values of the various beam pairs defined by the UE’ s codebook, the UE may select an Rx beam without considering of the RSRP bias values for the beam pairs, such as by selecting the Rx beam that has the strongest nonbiased RSRP. As a result, the device may configure itself to use the Tx beam of one beam pair defined by the codebook and the Rx beam of another pair defined by the codebook, and the device may then operate concurrently with these Tx and Rx beam settings.

[0076] Further note that, as a possible alternative to use of the CDF analysis described above,

[0077] Figure 5 is a flow chart illustrating an example method that could be carried out by a device (e.g., the UE discussed above) to control beamforming, where the device is configured with a beamforming codebook specifying multiple receive Rx-Tx beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antennapattern configurable for use by the device and (ii) a respective Tx beam having a respective Tx antenna-pattern configurable for use by the device.

[0078] As shown in Figure 5, at block 500, the example method includes the device maintaining, respectively per beam pair, an Rx signal -strength bias value defining an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection. Further, at block 502, the method includes the device receiving a wireless transmission from a remote entity and, respectively for each beam pair defined by the codebook, (a) measuring an Rx signal strength of the transmission as received using the Rx beam of the beam pair and (b) applying the Rx signal-strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair. In addition, at block 504, the method includes the device selecting one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs. And at block506, the method includes, based on the selecting, the device configuring itself to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

[0079] In line with the discussion above, the act of the device maintaining respectively per beam pair the Rx signal-strength bias value could involve the device maintaining the Rx signal-strength bias value per beam pair as part of the beamforming codebook.

[0080] Further, as discussed above, the device could be a cell phone, and the remote entity could be an access node.

[0081] Still further, as discussed above, each Rx signal strength could comprise RSRP or another metric.

[0082] In addition, as discussed above, each Rx beam could be dual pole including a first pole and an orthogonal second pole. In that case, the measured Rx signal strength respectively of each Rx beam could be a combination of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second pole of the Rx beam. Alternatively, the measured Rx signal strength respectively of each Rx beam could be a greatest of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second-pole of the Rx beam.

[0083] As further discussed above, the Rx signal -strength bias value respectively of each beam pair could be established in advance based on at least one of (a) a comparison of (i) Tx performance of the Tx beam of the beam pair with (ii) the Rx performance of the Rx beam of the beam pair (b) a CDF analysis of EIRP from the device when the Rx signal-strength bias values are applied a basis for Tx beam selection at varying angles of incidence.

[0084] Still further, the device could include an antenna array, the act of measuring the Rx signal strength respectively for each beam pair using the Rx beam of the beam pair could involve configuring the antenna array to use the Rx beam of the beam pair to facilitate receiving and measuring the Rx signal strength of the transmission using the Rx beam of the beam pair, and the act of configuring the device to use the Tx beam of the selected beam pair could involve configuring the antenna array to use the Tx beam of the selected beam pair.

[0085] More particularly, configuring the antenna array to use the Rx beam respectively of each beam pair could involve configuring amplitude and / or phase of each of one or more antenna elements of the antenna array, and configuring the antenna array to use the selected Tx beam could involve configuring amplitude and / or phase of each of one or more antenna elements of the antenna array.

[0086] In addition, in line with the discussion above, the selected beam pair could be a first beam pair, and the method could additionally include (a) the device selecting a second one of the multiple beam pairs based on the selected beam pair having a highest computed nonbiased Rx signal strength of the multiple beam pairs, the Tx and Rx beams of the second selected beam pair being different than the Tx and Rx beams of the first selected beam pair and (b) the device operating concurrently with the Tx beam of the first selected beam pair and the Rx beam of the second selected beam pair.

[0087] The present disclosure also contemplates other example mechanisms for a UE or other device to select a Tx beam based on advanced analysis of receive-signal strength on the UE’s various available Rx beams. Some of these mechanisms could be used in combination with the processes discussed above as well.

[0088] As another example, the UE could use an angle-of-arrival (AoA) analysis based on the RSRP values of the UE’s multiple beam pairs as a basis to select a Tx beam. This AoA analysis may assume that the UE is pre-provisioned with data defining the antenna patterns of the multiple Rx and Tx beams defined by the UE’s beamforming codebook. This antenna-pattern data could be a digital representation of each antenna pattern in a spherical coordinate system, defining the antenna pattern by defining the antenna gain at various sample directions.

[0089] As the UE receives wireless transmission from the access node, the AoA analysis could involve the UE cycling through the multiple Rx beams defined by the UE’s codebook and, for each Rx beam, configuring itself to use the Rx beam and measuring RSRP of the wireless transmission. The UE could then predict an AoA of the wireless transmission by considering products of RSRP and antenna gain at various sample directions.

[0090] For instance, for each Rx beam, the UE could generate a vector of sample points, one per sample direction, each being a product of the UE’s measured RSRP using that Rx beam and the Rx beam’s antenna gain at that sample direction. Given these generated vectors for the set of Rx beams defined by the UE’s codebook, the UE could then combine the vectors together, e.g., for each sample direction, summing the RSRP*gain products computed for the various Rx beams, to produce a representative vector that indicates for each sample direction a cumulative total of RSRP*gain across the various Rx beams. Once the UE generates this representative vector, the UE could determine which sample direction (i.e., which member of the vector) has the highest cumulative total of RSRP*gain and could deem that sample direction to be the AoA of the wireless transmission from the access node.

[0091] Given this determination of the AoA based on the consideration of RSRP measurements and antenna patterns of the UE’s multiple Rx beams, the UE could then readily select a Tx beam based on a comparison of Tx beam gains at that determined angle. Namely, the UE could determine which Tx beam defined by the UE’s codebook has the highest gain at that determined angle. Upon selecting this Tx beam, the UE could then configure itself accordingly to use the selected Tx beam.

[0092] Furthermore, with any of the methods described above, among other possibilities, once the UE has selected and configured itself with a given Tx beam for use to transmit to the access node, the UE could then apply a process to help optimize the selected Tx beam by dynamically adjusting the UE’s Tx beamforming vector in an effort to increase uplink transmission performance. This may result in varying the selected Tx beam from what is set forth in the UE’s codebook.

[0093] For example, once the UE has selected and configured itself with a given Tx beam, the UE could monitor feedback that the UE receives from the access node as an indication of the quality of the UE’s uplink communication using that Tx beam. This may include monitoring what percentage of HARQ messages the UE receives from the access node are NAK messages requesting retransmission (each based on the access node failing to successfully receive the UE’s scheduled uplink transmission as noted above) and / or what percentage of the power-control commands the UE receives from the access node are power- up commands (each based on the access node determining that the receive-signal strength from the UE is lower than a defined set point), among other possibilities.

[0094] The UE could then randomly perturb its active Tx beam boresight or other parameters, such as by changing amplitude and / or phase settings in its configured Tx beamforming vector, and the UE could then continue to monitor feedback about the UE’s uplink transmission quality and see whether the random perturbation of its Tx beam direction helped improved quality of its uplink transmission.

[0095] If the UE thereby finds that its uplink transmission quality improves, the UE could continue perturbing its Tx beam in the same direction (e.g., adjusting the boresight more in the same direction as the first perturbation), and the UE could repeat the process iteratively until a threshold point such as until further changes do not result in at least a predefined threshold improvement of the UE’s uplink transmission quality. Whereas, if the UE thereby finds that its uplink transmission quality becomes worse, the UE could reverse the direction of its Tx beam perturbation or take other action to improve the Tx beam.4. Additional Implementations

[0096] In addition, the present disclosure also contemplates a non-transitory computer-readable medium (e.g., optical, magnetic, or flash storage, RAM, ROM, EPROM, EEPROM, etc.) having stored thereon program instructions executable by a processor of a device to cause the device to carry out various operations described herein.

[0097] Example embodiments have been described above. Those skilled in the art will understand, however, that changes and modifications may be made to these embodiments without departing from the true scope and spirit of the invention.

Claims

CLAIMSWhat is claimed is:

1. A method for controlled beamforming by a device, wherein the device is configured with a beamforming codebook specifying multiple receive (Rx) - transmit (Tx) beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antenna-pattern configurable for use by the device and (ii) a respective Tx beam having a respective Tx antenna-pattern configurable for use by the device, the method comprising: maintaining, by the device, respectively per beam pair, an Rx signal-strength bias value defining an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection; receiving, by the device, a wireless transmission from a remote entity and, respectively for each beam pair defined by the codebook, (a) measuring, by the device, an Rx signal strength of the transmission as received using the Rx beam of the beam pair and (b) applying, by the device, the Rx signal-strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair; selecting, by the device, one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs; and based on the selecting, configuring, by the device, itself to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

2. The method of claim 1, wherein maintaining respectively per beam pair the Rx signal-strength bias value comprises maintaining the Rx signal-strength bias value per beam pair as part of the beamforming codebook.

3. The method of claim 1, wherein the device is a cell phone, and wherein the remote entity is an access node.

4. The method of claim 1, wherein each Rx signal strength comprises reference signal receive power (RSRP).

5. The method of claim 1, wherein each Rx beam is dual pole comprising a first pole and an orthogonal second pole, and wherein the measured Rx signal strength respectively of each Rx beam is a combination of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second pole of the Rx beam.

6. The method of claim 1, wherein each Rx beam is dual pole comprising a first pole and an orthogonal second pole, and wherein the measured Rx signal strength respectively of each Rx beam is a greatest of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second pole of the Rx beam.

7. The method of claim 1, wherein the Rx signal-strength bias value respectively of each beam pair is established in advance based on at least one of: a comparison of (i) Tx performance of the Tx beam of the beam pair with (ii) the Rx performance of the Rx beam of the beam pair, or a cumulative distribution function (CDF) analysis of effective isotropic radiated power (EIRP) from the device when the Rx signal-strength bias values are applied a basis for Tx beam selection at varying angles of incidence.

8. The method of claim 1, wherein the device has an antenna array, wherein measuring the Rx signal strength respectively for each beam pair using the Rx beam of the beam pair comprises configuring the antenna array to use the Rx beam of the beam pair to facilitate receiving and measuring the Rx signal strength of the transmission using the Rx beam of the beam pair, and wherein configuring the device to use the Tx beam of the selected beam pair comprises configuring the antenna array to use the Tx beam of the selected beam pair.

9. The method of claim 8, wherein configuring the antenna array to use the Rx beam respectively of each beam pair comprises configuring amplitude and / or phase of each of one or more antenna elements of the antenna array, andwherein configuring the antenna array to use the selected Tx beam comprises configuring amplitude and / or phase of each of one or more antenna elements of the antenna array.

10. The method of claim 1, wherein the selected beam pair is a first beam pair, the method further comprising: selecting by the device, a second one of the multiple beam pairs based on the selected beam pair having a highest computed non-biased Rx signal strength of the multiple beam pairs, the Tx and Rx beams of the second selected beam pair being different than the Tx and Rx beams of the first selected beam pair; and operating by the device concurrently with the Tx beam of the first selected beam pair and the Rx beam of the second selected beam pair.

11. A device comprising: an antenna array having multiple array elements cooperatively configurable to facilitate receive (Rx) beamforming by the device and transmit (Tx) beamforming by the device; at least one processor; non-transitory data storage; a beamforming codebook stored in the non-transitory data storage, the beamforming codebook specifying multiple Rx-Tx beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antenna-pattern configuration of the antenna array and (ii) a respective Tx beam having a respective Tx antenna-pattern configuration of the antenna array; bias data stored in the non-transitory data storage, the bias data including, respectively per beam pair, an Rx signal-strength bias value defining an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection; program instructions stored in the non-transitory data storage and executable by the at least one processor to cause the device to carry out operations for controlled beamforming based on transmission received wirelessly by the device from a remote entity, the operations including: respectively for each beam pair defined by the codebook, (a) measuring, by the device, an Rx signal strength of the transmission as received using the Rx beam of the beam pair and (b) applying, by the device, the Rx signal-strength bias value of the beampair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair, selecting one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs, and based on the selecting, configuring the device to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

12. The device of claim 11, wherein the bias data is part of the beamforming codebook.

13. The device of claim 11, wherein the device is a cell phone, and wherein the remote entity is an access node.

14. The device of claim 11, wherein each Rx beam is dual pole comprising a first pole and an orthogonal second pole, and wherein the measured Rx signal strength respectively of each Rx beam is a combination of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second pole of the Rx beam.

15. The device of claim 11, wherein each Rx beam is dual pole comprising a first pole and an orthogonal second pole, and wherein the measured Rx signal strength respectively of each Rx beam is a greatest of (i) a measurement of Rx signal strength of the first pole of the Rx beam and (ii) a measurement of Rx signal strength of the second pole of the Rx beam.

16. The device of claim 11, wherein the Rx signal-strength bias value respectively of each beam pair is established in advance based on at least one of: a comparison of (i) Tx performance of the Tx beam of the beam pair with (ii) the Rx performance of the Rx beam of the beam pair, or a cumulative distribution function (CDF) analysis of effective isotropic radiated power (EIRP) from the device when the Rx signal-strength bias values are applied a basis for Tx beam selection at varying angles of incidence.

17. The device of claim 11,wherein measuring the Rx signal strength respectively for each beam pair using the Rx beam of the beam pair comprises configuring the antenna array to use the Rx beam of the beam pair to facilitate receiving and measuring the Rx signal strength of the transmission using the Rx beam of the beam pair, wherein configuring the device to use the Tx beam of the selected beam pair comprises configuring the antenna array to use the Tx beam of the selected beam pair.

18. The device of claim 17, wherein configuring the antenna array to use the Rx beam respectively of each beam pair comprises configuring amplitude and / or phase of each of one or more of the antenna elements of the antenna array; and wherein configuring the antenna array to use the selected Tx beam comprises configuring amplitude and / or phase of each of one or more of the antenna elements of the antenna array.

19. The device of claim 11, wherein the selected beam pair is a first beam pair, the operations additionally including: selecting a second one of the multiple beam pairs based on the selected beam pair having a highest computed non-biased Rx signal strength of the multiple beam pairs, the Tx and Rx beams of the second selected beam pair being different than the Tx and Rx beams of the first selected beam pair; and operating concurrently with the Tx beam of the first selected beam pair and the Rx beam of the second selected beam pair.

20. A non-transitory computer-readable medium having stored thereon reference data and having stored thereon program instructions executable by at least one processor of a device to cause the device to carry out operations for controlling beamforming, wherein the reference data includes a beamforming codebook specifying multiple receive (Rx) - transmit (Tx) beam pairs of the device, each beam pair defining (i) a respective Rx beam having a respective Rx antenna-pattern configurable for use by the device and (ii) a respective Tx beam having a respective Tx antenna-pattern configurable for use by the device,wherein the reference data includes, respectively per beam pair, an Rx signal-strength bias value defining an offset to be applied when using Rx signal strength of the beam pair as a basis for Tx beam selection, and wherein the operations include, based on transmission received wirelessly by the device from a remote device: respectively for each beam pair defined by the codebook, (a) measuring, by the device, an Rx signal strength of the transmission as received using the Rx beam of the beam pair and (b) applying, by the device, the Rx signal-strength bias value of the beam pair to the measured Rx signal strength, to compute a biased Rx signal strength of the beam pair; selecting one of the multiple beam pairs based on the selected beam pair having a highest computed biased Rx signal strength of the multiple beam pairs; and based on the selecting, configuring the device to use the Tx beam of the selected beam pair for wireless transmission from the device to the remote entity.

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