WO2022103962A2

WO2022103962A2 - Beamforming management for device-to-device ranging

Info

Publication number: WO2022103962A2
Application number: PCT/US2021/058980
Authority: WO
Inventors: Jibing Wang; Erik Richard Stauffer
Original assignee: Google Llc
Priority date: 2020-11-13
Filing date: 2021-11-11
Publication date: 2022-05-19
Also published as: WO2022103962A3

Abstract

A network (100) employs a pair of UE (110) to perform UE-to-UE ranging. A base station (106) obtains beamforming capabilities (116) of each UE, and from this information determines a ranging beamforming configuration (114) that is transmitted to each UE. The ranging beamforming configuration includes a beamsweeping pattern (118) specifying a set of beams to be time-swept. A first UE (110-1) sweeps through the beamsweeping pattern and transmits one or more ranging signals (120) in the corresponding beam. A second UE (110-2) sweeps through the beamsweeping pattern in synchronization and monitors for the ranging signal in the corresponding beam. If the ranging beam is detected, the second UE transmits a response signal (122) in the same beam. The first UE uses the response signal to determine a location of the second UE, which then may be reported (124) to the base station or used for direct UE-to-UE signaling.

Description

BEAMFORMING MANAGEMENT FOR DEVICE-TO-DEVICE RANGING

BACKGROUND

[0001] The use of millimeter-wave (mmWave) bands and higher-frequency bands in cellular networks have the potential for higher data rates and lower latencies through increased channel bandwidths compared to the use of lower-frequency bands. However, the mobile environment at these high frequencies is considerably more complex than at lower frequencies, with disproportionally higher propagation/path losses, decreased resiliency and robustness, and susceptibility to line of sight (LoS) blockage by materials and objects in the local environment. Accordingly, cellular protocols that support the use of mmWave bands, such as the Fifth Generation (5G) New Radio (NR) cellular protocols promulgated by the Third Generation Partnership Project (3GPP), rely on the use of highly-directional communication links between a base station and the user equipment (UE) served by the base station to leverage the focused gain provided by such communication links. Leveraging the relatively large number of relatively small antenna elements that can be implemented at mmWave and higher-frequency bands, mobile UEs utilize high-dimensional phased antenna arrays to provide highly-directional communication links. However, these directional links require precise alignment between the transmitter beams and the receiver beams. Accordingly, mmWave-capable base stations often also employ beamforming processes to facilitate beam alignment between the base station and an attached UE, thereby allowing the base station and the UE to leverage the narrower transmit and receive beams to reduce the degree of radio interference while maintaining sufficient signal power at longer distances.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] The present disclosure is better understood, and its numerous features and advantages made apparent to those skilled in the art by referencing the accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical items.

[0003] FIG. 1 is a diagram illustrating an example wireless communication system employing base station-managed device-to-device ranging using a directional ranging beamforming configuration determined based on UE-reported beamforming capabilities in accordance with some embodiments.

[0004] FIG. 2 is a diagram illustrating an example configuration of a UE of the wireless communication system of FIG. 1 in accordance with some embodiments.

[0005] FIG. 3 is a diagram illustrating an example configuration of a base station of the wireless communication system of FIG. 1 in accordance with some embodiments.

[0006] FIG. 4 is a flow diagram illustrating an example method for base stationmanaged device-to-device ranging in accordance with some embodiments.

[0007] FIG. 5 is a flow diagram illustrating an example ranging beamsweeping process employed in the method of FIG. 4 in accordance with some embodiments.

[0008] FIG. 6 is a diagram illustrating a coarse pass/fine pass method for a ranging beamsweeping process in accordance with some embodiments.

[0009] FIG. 7 is a flow diagram illustrating an example of the coarse pass/fine pass method of FIG. 6 in accordance with some embodiments.

[0010] FIG. 8 is a ladder diagram illustrating an example implementation of the method of FIG. 4 for a base-station-initiated device-to-device ranging process in accordance with some embodiments.

[0011] FIG. 9 is a ladder diagram illustrating an example implementation of the method of FIG. 4 for a device-initiated device-to-device ranging process in accordance with some embodiments.

DETAILED DESCRIPTION

[0012] Conventional base station-implemented ranging techniques facilitate the alignment of directional transmission links between a base station and attached UE. However, due to the distances typically separating the base station from the attached UEs, base station-implemented ranging can lead to sub-optimal accuracy in the beamforming between the base station and a UE. Moreover, the beamsweeping process used by the base station can be time and radio frequency (RF) resource intensive. Furthermore, in some implementations, the ranging performed by a base station typically is of primary benefit to the base station itself and often is not readily utilizable by the UEs in the event that two or more UEs are to range each other for various reasons, including establishing direct device-to-device communications, for refining the beam management employed by the base station, for offloading some of the beam management process from the base station, and the like.

[0013] Accordingly, described herein are example systems and techniques for UE-to- UE ranging of other UEs within a cellular network using a base station or other component of a radio access network (RAN) to manage the UE-to-UE ranging process (that is, the device-to-device ranging process). In at least one embodiment, each UE participating in a UE-to-UE ranging process reports beamforming capability information to a base station of a serving cell. The beamforming capability information represents one or more beamforming-related capabilities of the UE, such as the number of antenna modules implemented at the UE that are available for use in the beamforming process, the number and identifiers of the beams supported at each identified antenna module, beamwidth parameters for support of wide beams and narrow beams, an indicator of projected power capability of the UE, and the like. This beamforming capability information can be provided as part of the Initial Access (IA) process for each UE, polled periodically, requested by the base station in response to initiation of a ranging process, provided in association with a request to coordinate UE-to-UE ranging by a UE, and the like.

[0014] In response to a ranging trigger event, which may be an internally-generated trigger by the base station or in some instances in response to a ranging request generated by one UE for purposes of ranging another UE, the base station identifies a pair of UEs to perform a corresponding UE-to-UE ranging process in service of the ranging trigger event, this pair including one UE to perform the ranging (hereinafter, the “initiator UE”) and one UE to be ranged (hereinafter, the “responder UE”). If a UE submitted a ranging request, the requesting UE is designated as the initiator UE and the UE sought to be ranged in the ranging request is designated the responder UE. In the event that the base station initiates the ranging process, the UE sought to be ranged is designated as the responder UE and another UE, such as one identified as being in close proximity to the responder UE or one identified as having significant and relevant beamforming capabilities, is selected as the initiator UE.

[0015] With initiator UE and responder UE selected or otherwise identified, the base station uses the beamforming capabilities reported by these UEs, as well as certain other information, such as approximate locations of the UEs, to determine a ranging beamforming configuration to be implemented by the UEs in performing the UE-to- UE ranging process. In some embodiments, the ranging beamforming configuration includes a beamsweeping pattern that identifies a pattern of beams to be employed in a beamsweeping process between the initiator UE and the responder UE. In at least one embodiment, the base station selects the beams to be included in this pattern, the order in which they are to be utilized, and the timing of the sweep (e.g., the interval or duration between each beam) based on, for example, identification of beams supported by both UEs, the capabilities of the UEs to support wideband/narrowband beam sweeping, the number of antenna modules, the locations of the UEs relative to each other, the effective radiated power capabilities of the UEs, the battery capacity of the UEs, and the like.

[0016] The base station then transmits this ranging beamforming configuration to each of the initiator UE and responder UE and these UEs integrate this ranging beamforming configuration in preparation for performing the UE-to-UE ranging process. With both UEs synchronized to a common timing reference, such as that established by their respective wireless connections to the base station, the initiator UE and responder UE together initiate the ranging process by implementing the beamsweeping pattern, with the initiator UE sequentially transmitting a specified ranging signal in each beam of the beamsweeping pattern in the indicated order and for the indicated duration until a response signal is received from the responder UE. Concurrently, the responder UE sequentially monitors each beam of the beamsweeping pattern in the indicated order and for the indicated duration until the ranging signal is detected, in response to which the responder UE transmits the response signal in the corresponding beam.

[0017] In addition to specifying the particular beams, their order, and duration, the beamsweeping pattern determined by the base station in some embodiments employs a coarse/fine beamsweeping approach in which a subset of the wide beams supported by both the initiator UE and responder UE are configured as a coarse pass and, in the event that a ranging signal is detected by the responder UE and a response signal thus transmitted by the responder UE and received by the initiator UE, the beamsweeping pattern switches to a fine pass in which the initiator UE and responder UE sequence through a set of narrow beams that cover the identified wide band in a specified order and intervals until the ranging signal is detected and a response signal provided in response for a corresponding narrow band. This coarse/fine approach can thus accelerate the process of ranging the responder UE.

[0018] In the event that one or more response signals are triggered during the beamsweeping process, the initiator UE uses the one or more response signals and, in some instances, the beam(s) used for their reception, to determine ranging data indicative of a location of the responder UE. To illustrate, in some embodiments, the initiator UE employs the angular relationship of the beam used to transmit the response signal and a Round T rip Time (RTT) or other Time of Flight (T oF) analysis of the response signal to determine a location of the responder UE. In other embodiments, the initiator UE utilizes an Angle of Arrival (AoA) analysis of the response signal to determine the angular relationship between the initiator UE and the responder UE. The ranging data then can be employed by the initiator UE for device-to-device signaling, provided to the base station for refining the base station’s beamforming configuration for the responder UE or for transmitting to other UEs for their own device-to-device signaling with the responder UE, and the like.

[0019] FIG. 1 illustrates a wireless communication network 100 employing base station-managed device-to-device ranging using a directional ranging beamforming configuration determined based on UE-reported beamforming capabilities in accordance with some embodiments. As depicted, the wireless communication network 100 includes a core network 102 coupled to one or more wide area networks (WANs) or other packet data networks (PDNs) (not illustrated), such as the Internet. The core network 102 is further connected to one or more edge networks 106 via one or more backhaul networks (not shown). Each edge network 106 (also commonly referred to as a “cell” or a “radio access network” (RAN)) represents a corresponding fixed or mobile coverage area and includes at least one base station 108 to wirelessly communicate with one or more UEs 110, such as the illustrated UEs 110-1 and 110-2, via radio frequency (RF) signaling using one or more applicable radio access technologies (RATs) as specified by one or more communications protocols or standards. As such, the base station 108 operates as the wireless interface between each UE 110 and various networks and services provided by the core network 102 and other networks, such as packet-switched (PS) data services, circuit- switched (CS) services, and the like. [0020] The base station 108 can employ any of a variety of RATs, such as operating as a NodeB (or base transceiver station (BTS)) for a Universal Mobile Telecommunications System (UMTS) RAT (also known as “3G”), operating as an enhanced NodeB (eNodeB) for a Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) RAT, operating as a 5G node B (“gNB”) for a 3GPP Fifth Generation (5G) New Radio (NR) RAT, and the like. The UE 110, in turn, can implement any of a variety of electronic devices operable to communicate with the base station 108 via a suitable RAT, including, for example, a mobile cellular phone, a cellular-enabled tablet computer or laptop computer, a desktop computer, a cellular-enabled video game system, a server, a cellular-enabled appliance, a cellular-enabled automotive communications system, and the like.

[0021] The particular RAT used for wireless communications between the base station 108 and a UE 110 may rely on directional beamforming to provide more effective signal transmission, such as is implemented in 5G NR RATs, and in particular, for mmWave-based 5G NR signaling. However, one or more of the UEs 110 served by the base station 108 is “mobile” in that its location can, and typically does, change relative to the base station 108, relative to the other UEs 110, or both. This mobility of certain UEs 110 can frustrate the use of highly-directional RF communication links between transmitter and receiver implemented for mmWave and THz frequency bands as a mobile UE 110 changing location can result in misalignment in beam directions between the mobile UE 110 and the other network component in communication with the mobile UE 110. To mitigate this, the wireless communication network 110 employs one or more ranging techniques to allow the current location of the mobile UE 1 10 to be identified and antenna beam directions to be modified accordingly. Conventionally, a base station would perform the ranging process directly with the mobile UE 110. However, as explained above, this approach may unduly consume RF resources and processing at the base station, and often results in ranging information that is available to the base station but rarely shared with other UEs 110 so that they may conduct their own device-to-device communications with the mobile UE 110.

[0022] Accordingly, in at least one embodiment, rather than the base station 108 performing the beamsweeping processes and other aspects of a base-station-based ranging of a mobile UE 110, the base station 108 instead coordinates or otherwise manages a device-to-device ranging process in which the base station 108 configures another UE 110 to perform the ranging process with the mobile UE 110, while also configuring the mobile UE 110 to participate in this UE-to-UE ranging process. This device-to-device ranging process (referred to herein as the “UE-to-UE ranging process”) typically is initiated in response to a ranging request 112, which the base station 108 may self-generate in response to some trigger, such as the attachment of a mobile UE 110 to the cell served by the base station, through an indication that an attached mobile UE 110 has changed locations or orientations, and the like. In other embodiments, another UE 110 transmits the ranging request 112 to the base station 108, such as when the other UE 110 is seeking to establish device- to-device communications with the mobile UE 110.

[0023] In response to the ranging request 112, the base station 108 selects a pair of UEs 110 to perform the UE-to-UE ranging process. The selected pair includes the mobile UE 110 to be ranged (referred to herein as “the responder UE”), as well as another UE 110 to perform the ranging (referred to herein as “the initiator UE”). For a base-station-triggered UE-to-UE ranging process, the responder UE is the mobile UE 110 the base station 108 seeks to range, and the base station 108 selects the initiator UE 110 from the set of UEs 110 served by the base station based on various criteria, as explained in further detail below. For a UE-triggered UE-to-UE ranging process, the base station 108 identifies the UE 110 initiating the process as the initiator UE 110 and the UE 110 the initiator UE 110 is seeking to range is the responder UE 110. For purposes of illustration, in the examples and embodiments that follow the pair of UEs 110 configured by the base station 108 to perform the UE- to-UE ranging process is the UE 110-1 and 110-2, with the UE 110-2 being the mobile UE to be ranged (and thus referred to herein as the “responder UE 110-2”) and the UE 110-1 being the UE to range the responder UE 110-2 (and thus referred to herein as the “initiator UE 110-1”).

[0024] As described in greater detail below, the UE-to-UE ranging process includes the initiator UE 110-1 performing a beamsweeping process using a beamsweeping pattern configured by the base station 108 to transmit a ranging signal for beams in the beamsweeping pattern in a specified order and in accordance with specified timing, and the responder UE 110-2 likewise using a beamsweeping process using the same beamsweeping pattern to monitor each beam in the pattern for the ranging signal in the specified order and reply with a response signal in accordance with the specified timing. Accordingly, in at least one embodiment, the base station 108 determines a ranging beamforming configuration 114 representative of the beamsweeping pattern and other parameters to be concurrently implemented by the initiator UE 110-1 and the responder UE 110-2 and transmits the beamforming configuration 114 to each of the UEs 110-1 , 110-2 for implementation. Note that while an embodiment in which each UE receives the same ranging beamforming configuration 114 is described for ease of illustration, in other embodiments the base station 108 determines a ranging beamforming configuration specific to each UE based on its role as either initiator UE or responder UE.

[0025] In at least one embodiment, the base station 108 determines the beamsweeping pattern and other parameters of the ranging beamforming configuration 114 based on beamforming capabilities of one or both of the initiator UE 110-1 and the responder UE 110-2. To this end, the base station 108 obtains from the initiator UE 110-1 beamforming capabilities information 116-1 that identifies various beamforming capabilities of the initiator UE 110-1. Likewise, the base station 108 obtains from the responder UE 110-2 beamforming capabilities information 116-2 that identifies various beamforming capabilities of the responder UE 110-2. The indicated beamforming capabilities can include, for example, the number of antenna modules implemented at the corresponding UE, identifiers of the beams supported by each antenna module for the one or more RF bands available for use in the ranging process, identification of wide beams and narrow beams supported by a given antenna module, and the like. The beamforming capability information can include certain other parameters, such as peak effective radiated power (ERP), peak equivalent isotropically radiated power (EIRP), or another radiated power indicator, a battery capacity for the UE (which may indicate a remaining battery capacity, whether the UE is connected to mains power, etc.), and the like. Further, in some embodiments, the base station 108 uses the beamforming capabilities advertised by UEs 110 to select one or both of the initiator UE and the responder UE.

[0026] The base station 108 uses the beamforming capability information 116 from the selected pair of UEs 110 to then determine the ranging beamforming configuration 114 to be concurrently employed by the initiator UE 110-1 and the responder UE 110-2 in the UE-to-UE ranging process. To illustrate, the base station 108 can determine a particular subset of beams to be implemented in a beamsweeping pattern 118, the order in which the beams are swept, and a duration or other timing for each beam of the beamsweeping pattern based on the indications of which beams are supported by antenna module(s) of both of the UEs 110-1 , 110-2 found in the beamforming capability information 116 provided by these UEs. Further, the base station 108 may use other information regarding the UEs that is obtained through analysis or communications separate from the provision of the beamforming capability information 116, such as information regarding an approximate position of at least the responder UE 110-2, as determined via, for example, location reporting by the UEs 110-1 , 110-2 using Global Navigation Satellite System (GNSS) or Global Positioning System (GPS) data. With the knowledge of the approximate locations of the initiator UE 110-1 and the responder UE 110-2 relative to each other, the base station 108 can select a subset of beams for the beamsweeping pattern 118 suited to the angular relationship between the two UEs, as described in greater detail below.

[0027] With the UEs 110-1 , 110-2 configured to jointly perform the UE-to-UE ranging process, at a designated start time synchronized to a canonical clock signal or other timing reference specified by the base station 108, the initiator UE 110-1 begins to time-sweep through the beams indicated in the beamsweeping pattern 118 in the order and with the timing specified by the beamsweeping pattern 118 to sweep the angular space that covers the expected location of the responder UE 110-2. For each beam in sequence, the initiator UE 110-1 configures one or more of its antenna modules to transmit a specified ranging signal 120 in corresponding beam and then monitors for a response from the responder UE 110-2. Concurrently, the responder UE 110-2 sweeps through the beam pattern 118 in the same order and with the same timing synchronized to the joint timing reference. For each beam in sequence, the responder 110-2 configures one or more of its antenna modules to monitor for the ranging signal 120. If the ranging signal 120 is detected, the responder UE 110-2 then configures one or more of its antenna modules to then transmit a specified ranging response signal 122, typically using the same beam in which the ranging signal 120 was detected. The response signal 122 can be configured as a binary indicator, so as to indicate whether the ranging signal 120 has been “received” or “not received”, or as a non-binary indicator to indicate one of multiple levels of strength of the receipt of the ranging signal, such as a ternary signal indicating “low”, “medium”, or “high” levels of receipt of the ranging signal 120. As such, the beamsweeping sequence may be continued after first receipt of a ranging signal 120 until, for example, one or both of transmission of a response signal 122 indicating sufficiently strong receipt of the ranging signal 120 at the responder UE 110-2 or a sufficient number of response signals 122 have been received for adjacent beams in the beamsweeping pattern 118 to allow the initiator UE 110-1 to adequately identify the angular position of the responder UE 110-2 from the response signals 122.

[0028] When adequate response information is received from the responder UE 110- 2, the initiator UE 110-1 terminates the beamsweeping sequence and then ranges the responder UE 1 10-2 based on the one or more response signals 122 received from the responder UE 110-2. To illustrate, the identifier of the beam in which transmission of the ranging signal 120 elicited transmission of a response signal 122 from the responder UE 110-2 informs the initiator UE 110-1 of the angular relationship of the responder UE 110-2 relative to the initiator UE 1 10-1 .

Alternatively, the angular relationship can be determined from AoA analysis of the received response signal. The initiator UE 110-1 then can perform any of a variety of positional or orientational analysis processes using a received response signal 122, such as a RTT analysis or other ToF analysis, to determine a distance between the UE 110-1 and the UE 110-2. The initiator UE 110-1 then can determine a spatial position of the responder UE 110-2 using the angular relationship and distance between the initiator UE 110-1 and the responder UE 110-2. The initiator UE 110-1 then can utilize ranging data 124 representing this determined spatial position to conduct direct device-to-device communications with the responder UE 110-2, the initiator UE 110-1 can provide the ranging data 124 to the base station 108 for use by the base station 108 in updating or refining its estimated position of the responder UE 110-2 or for distribution by the base station 108 to other UEs 110 for conducting their own device-to-device communications with the UE 110-2, or a combination thereof.

[0029] FIG. 2 illustrates an example hardware configuration for a UE 110 (e.g., the UEs 110-1 and 110-2) of the wireless communication network 100 of FIG. 1 in accordance with some embodiments. Note that the depicted hardware configuration represents the processing components and communication components most directly related to the role of the UE 110 as either initiator UE or responder UE in the UE-to- UE ranging processes described herein and omit certain components well- understood to be frequently implemented in such electronic devices, such as displays, user input/output (I/O) devices, power supplies, and the like.

[0030] In the depicted configuration, the UE 110 includes an RF front end 202 composed of an array of one or more antenna modules 204, such as the illustrated four antenna modules 204-1 , 204-2, 204-3, and 204-4, and one or more wireless modems 206 implementing corresponding cellular protocols for conducting RF-based communications with the base station 108 and other base stations, such as an LTE modem 206-1 and a 5G NR modem 206-2. The RF front end 202 operates to conduct signals between the modems 206 and the array of antenna modules 204 to facilitate various types of wireless communication.

[0031] As illustrated by expanded window 208, each antenna module 204 implements a corresponding array of antenna elements 210, each excited by a corresponding feed RF signal when in a transmit (TX) mode and each excited by a received RF signal when in a receive (RX) mode. Each antenna element 210 is dimensioned and configured according to the expected frequency band(s) to be utilized for the antenna module 204, with mmWave and terahertz (THz) frequency bands particularly suited for the use of a larger array of small-dimensioned antenna elements due to the short wavelengths of RF signals at these frequencies. Note that although four antenna elements 210 are illustrated in the simplified example, in implementation the number of antenna elements 210 in a given antenna module 204 often is substantially higher.

[0032] Typically, two variables are used for beamforming: amplitude and phase, such that for beamformed transmission one or both of the amplitude or phase of a phase- coherent signal fed to a particular antenna element is shifted or otherwise adjusted relative to the phase-coherent signals fed to the other antenna elements, while for beamformed reception one or both of the amplitude or phase of a phase-coherent signal received via a particular antenna element is shifted or adjusted relative to the phase-coherent signals fed to the other antenna elements. The combination of the adjustments to phase and/or amplitude serves to “steer” the transmission beam of the RF signaling emitted by the antenna module or the reception beam of the RF signaling being monitored for reception by the antenna module in a manner that suppresses side lobes and steering nulls. To this end, each antenna module 204 may implement an analog beamforming transceiver architecture, a digital beamforming transceiver architecture, or a hybrid beamforming architecture as known in the art. For ease of illustration, the expanded window 208 illustrates an implementation of the antenna module 204-4 using an analog beamforming architecture having a single baseband processing module 212 and RF chain 214 for an array of antenna elements 210 and a phase shifter or delay line (omitted for clarity) for each antenna element 210 to implement a corresponding phase weight for each antenna element 210 to implement an indicated transmit beam or receive beam. As noted, a digital or hybrid architecture instead may be implemented, and the same or different beamforming architectures may be implemented at different antenna modules 204.

[0033] The UE 110 further includes one or more processors 216 and one or more non-transitory computer-readable media 218. The one or more processors 216 can include, for example, one or more central processing units (CPUs), graphics processing units (GPUs), an artificial intelligence (Al) accelerator, or other application-specific integrated circuits (ASIC), and the like. To illustrate, the processors 216 can include an application processor (AP) utilized by the UE 110 to execute an operating system and various user-level software applications, as well as one or more processors utilized by the modems 206. The computer-readable media 218 can include any of a variety or combinations of media used by electronic devices to store data and/or executable instructions, such as random access memory (RAM), read-only memory (ROM), caches, registers Flash memory, solid-state drive (SSD) or other mass-storage devices, and the like. For ease of illustration and brevity, the computer-readable media 218 is referred to herein as “memory 218” in view of frequent use of system memory or other memory to store data and instructions for execution by the processor 216, but it will be understood that reference to “memory 218” shall apply equally to other types of storage media unless otherwise noted.

[0034] The one or more memories 218 of the UE 110 are used to store one or more sets of executable software instructions and associated data that manipulate the one or more processors 216 and other components of the UE 110 to perform the various functions described herein and attributed to the UE 110. The sets of executable software instructions include, for example, an operating system (OS) and various drivers (not shown), various user software applications (not shown), and a ranging manager 220 that is configured to manipulate the one or more processors 216, the modems 206, and the RF front end 202 to perform the actions attributed to either the initiator UE or responder UE in the UE-to-UE ranging process described herein. To that end, the data stored in the one or more memories 218 can include, for example, a copy of the beamforming configuration 114 received from the base station 108, beamforming capabilities data 222 representative of the beamforming capabilities that are represented in the beamforming capabilities information 116 (FIG. 1) that the UE 110 supplies to the base station 108, as well as a ranging data store 224 that can store ranging data 124 (FIG. 1) for one or more other UEs 110 in the wireless communication network.

[0035] FIG. 3 illustrates a hardware configuration of the base station 108 of the wireless communication network 100 in accordance with some embodiments. Note that the depicted hardware configuration represents the processing components and communication components most directly related to the role of the base station 108 in the UE-to-UE ranging processes described herein and omit certain components well-understood to be frequently implemented in such electronic devices, such as displays, user input/output (I/O) devices, power supplies, and the like. Further note that although the illustrated diagram represents an implementation of the base station 108 as a single network node (e.g., a gNB), the functionality, and thus the hardware components, of the base station 108 instead may be distributed across multiple network nodes or devices and may be distributed in a manner to perform the functions described herein. As with the UE 110, the base station 108 includes an RF front end 302 composed of one or more antenna modules having one or more arrays of antenna elements, and one or more wireless modems, such as an LTE modem 306-1 and a 5G NR modem 306-2, for communicating with the UEs 110, as well as one or more processors 308 and one or more non-transitory computer-readable storage media 310 (as with the memory 218 of the UE 110, the computer-readable medium 310 is referred to herein as a “memory 310” for brevity). These components operate in a similar manner as described above with reference to corresponding components of the UE 110.

[0036] The one or more memories 310 of the base station 108 store one or more sets of executable software instructions and associated data that manipulate the one or more processors 308 and other components of the base station 108 to perform the various functions described herein and attributed to the base station 108. The sets of executable software instructions include, for example, an operating system (OS) and various drivers (not shown), various software applications (not shown), and a ranging configuration manager 312. The ranging configuration manager 312 configures the one or more processors 308, the modems 306, and the RF front end 302 to perform the actions attributed to the base station 108 in the UE-to-UE ranging process described herein. To that end, the data stored in the one or more memories 310 can include, for example, a UE capabilities data store 314, a beamforming configurations data store 316, and a UE ranging data store 318. The UE capabilities data store 314 stores capability information for the UEs 110 attached to the base station 108, including the beamforming capability information 116 obtained from each UE of the pair of UEs 110 selected to perform as initiator UE and responder UE in a UE-to-UE ranging operation. The beamforming configurations data store 316 stores a copy of each ranging beamforming configuration 114 provided to the pair of UEs selected for participation in a UE-to-UE ranging process. The UE ranging data store 318 stores copies of the ranging data 124 obtained by initiator UEs in performing UE-to-UE ranging processes for ranging corresponding responder UEs.

[0037] In some embodiments, the base station 108 further includes an inter-base station interface 320, such as an Xn or X2 interface, to exchange user-plane, controlplane, and other information between other base stations, and to manage the communication of the base station 108 with the UEs 110. The base station 108 further can include a core network interface 322 to exchange user-plane, controlplane, and other information with core network functions and/or entities.

[0038] FIG. 4 illustrates an example method 400 for configuring and performing a UE- to-UE ranging process between an initiator UE and a responder UE in accordance with at least one embodiment. For purposes of illustration, the method 400 is described in the example context of the wireless communication network 100 of FIG.

1 and the hardware configurations for the UE 110 and the base station 108 of FIGs. 2 and 3, respectively. Moreover, although subprocesses of method 400 are illustrated and described in an example order, the method 400 is not limited to this particular order and in some embodiments certain processes may be performed in a different order, or concurrently rather than in sequential order, or may be omitted altogether.

[0039] The UE-to-UE ranging process represented by method 400 starts with initiation or triggering of the ranging process at block 405. The base station 108 itself can initiate the ranging process in response to one or more triggers. In some embodiments, the base station 108 may employ UE-to-UE ranging when a DE 110 first accesses, or requests to access, the cell served by the base station 108 or during the handover process of the UE 110 from an adjacent cell. As another example, the base station 108 may employ a timer to periodically re-range one or more of the UEs 110 served by the base station. Further, the base station 108 may initiate the UE-to-UE ranging process when a resource utilization of the base station 108 exceeds a specified threshold. As yet another example, the base station 108 may monitor the motion of a mobile UE and trigger a UE-to-UE ranging process when the base station 108 has determined that the motion of the mobile UE has exceeded, or is anticipated to exceed, a specified threshold (and thus indicating the most recent ranging data possessed by the base station 108 may be out-of-date). Alternatively, the UE-to-UE ranging process instead may be triggered by a UE 110 as a result of that UE 110 transmitting a ranging request 112 to the base station 108, such as when the requesting UE 110 is seeking to establish the ranging of another UE 110 for the purposes of establishing direct device-to-device communications with the other UE 110.

[0040] At block 410, the ranging configuration manager 312 of the base station 108 identifies a pair of UEs 110 to perform the UE-to-UE ranging process triggered at block 405, with one UE 110 of the pair acting as the initiator UE 110-1 and the other UE 110 of the pair acting as the responder UE 110-2. In a UE-initiated ranging process, the UE 110 providing the ranging request 112 typically is designated the initiator UE 110-1 by default, and the UE 110 identifies in the ranging request 112 as the UE sought to be ranged is designated as the responder UE 110-2. However, in some instances, a different UE 110 may be better suited to act as the initiator UE 110-1 , such as by virtue of being closer to the approximate position of the responder UE 110-2 or by having more suitable beamforming capabilities than the requesting UE, and thus selected by the base station 108 as the initiator UE 110-1 over the requesting UE.

[0041] When the ranging process has been triggered by the base station 108 itself, the UE 110 in need of ranging and serving as the subject of the ranging process is designated as the responder UE 110-2, and the ranging configuration manager 312 then assesses which UE 110 served by the base station 108 is most suitable to act as the initiator UE 110-1 . In some embodiments, the ranging configuration manager 312 evaluates the beamforming capabilities of the UEs, and particularly whether they are compatible with the beamforming capabilities of the responder DE 110. The ranging configuration manager 312 also can consider other parameters, such as the proximity of each candidate UE 110 to the responder UE 110-2, the battery capacity of each candidate UE 110 (which may include whether the UE 110 is currently on mains power), and the like. The ranging configuration manager 312 can utilize any of a variety of techniques to select the initiator UE from the candidate UEs available, such as via a scoring system that applies a numerical score for each evaluated parameter and the candidate UE with the highest total score then selected as the initiator UE 110.

[0042] In order to configure the selected pair of UEs 110 to act as initiator UE and responder UE (and, as noted above, to select at least the initiator UE in the first place in some implementations), at block 415 the ranging configuration manager 312 obtains beamforming capability information 116 from each UE 110 of the selected pair in the form of beamforming capability information 116-1 (FIG. 1) obtained from the initiator UE 110-1 and beamforming capability information 116-2 (FIG. 1) obtained from the responder UE 110-2. The base station 108 can obtain the beamforming capability information 116 in any of a variety or combinations of ways.

[0043] In some embodiments, the base station 108 requests the beamforming capability information 116 from a UE 110 as part of the IA process by which the UE 110 initially accesses the base station 108 and the serving cell, as part of a periodic refresh of UE capability information at the base station 108, in response to detection of movement, reorientation, or relocation of the UE 110, and the like. To illustrate, the base station 108 can transmit a UE Capability Enquiry Radio Resource Control (RRC) message to the UE 110 as part of the 4G/5G RRC message exchange process for UE capability advertisement, and the UE 110 can reply with one or more UE Capability Information RRC messages that contain some or all of the beamforming capabilities information 116 for the UE 110. In other embodiments, the UE 110 initiates the provision of the beamforming capability information 116. To illustrate, when the initiator UE 110-1 provides the ranging request 112 to range the responder UE 110-2, the initiator UE 110-1 can provide its beamforming capability information 116-1 as part of the message forming the ranging request 112 or in a separate message in association with the message forming the ranging request 112. In such embodiments, the provision of the beamforming capabilities information 116 from the UEs 110 served by the base station 108 at block 415 may occur prior to the identification of the initiator UE and/or responder UE at block 410 in instances in which this beamforming capability information is used to select one or both of the UEs to participate in the UE-to-UE ranging process.

[0044] The beamforming capability information 116 provided by a UE 110 to the base station 108 represents capabilities of the UE as they pertain to aspects of beamforming supported by the UE 110. This may include, for example, the number of antenna modules 204 (FIG. 2) that the UE 110 has available to support beamforming, the frequency band(s) supported by each antenna module, such as frequency bands in the LTE spectrum (typically between 600 megahertz (MHz) and 2.5 Gigahertz (GHz), frequency bands in the 5G NR Sub6 spectrum (typically between frequency bands below 6 gigahertz (GHz), frequency bands in the 5G NR mmWave spectrum (often identified as between 30 and 300 GHz, but sometimes referring to frequencies between 24 GHz and 300 GHz), frequency bands in the Terahertz (THz) range (typically 300 GHz to 3 THz), and the like. To illustrate, some antenna modules 204 may be configured to support some or all frequency bands within only a certain spectrum, such as the LTE spectrum, the mmWave spectrum, the THz spectrum, and the like, while other antenna modules 204 of the UE 110 support frequency bands in a different frequency spectrum. Still further, some antenna modules 204 may be able to support frequency bands in different spectrums, such as some frequency bands in the Sub6 spectrum and some frequency bands in the mmWave spectrum. The beamforming capability information 116 thus may identify the particular frequency bands supported by each beamforming-enabled antenna module 204.

[0045] In a massive input-massive output (MIMO) configuration as found in 5G NR and similar cellular architectures, rather than omnidirectional transmissions of signals, the base stations 108, UEs 110, and other RF components of the wireless communications network 100 utilize beam-based transmissions. Accordingly, the base station 108 employs a standard set of beams, referred to as synchronization signal block (SSB) beams, with static or semi-static directions and which may partially overlap. Each SSB beam has a corresponding SSB identifier (SSB ID) used to identify the SSB beam. In general operation, the base station 108 time sweeps through each of the SSB beams to establish an angular relationship of the UE 110, and then may form a more specific directional beam to communicate with the UE 110 after based on this angular relationship. The antenna modules 204 of the UEs 110 typically are configured to support RF signaling along some or all of these SSB beams, and thus the beamforming capability information 116 supplied by the UE 110 can include an identifier, such as the UE ranging beam ID, of each beam supported by a given antenna module 204. For example, a mmWave antenna module 204 of the UE may only support s beams covering 120 degrees (e.g., each beam being 15 degrees), with each beam having a corresponding unique beam ID so as to identify its origination and sweep.

[0046] Rather than divide a section of the angular space (including one or both of azimuth or elevation) to be swept into beams of equal aperture angle, or “width”, as is typically the case with a grid of beams, in some embodiments the beamsweeping process employed by the UE-to-UE ranging process instead may implement a coarse/fine beam width approach in which the search process is split into two stages or levels: a coarse stage followed by a fine stage. A specified portion of the angular space that is expected to cover the responder UE 110-2 is divided into a set of “wide” beams (which may or may not overlap), each having a wider aperture angle. The coverage area of each of these wide beams is then represented by a corresponding set of “narrow beams” (which may or may not overlap), each having a narrower aperture angle. During a coarse sweep stage, the initiator UE 110-1 sequentially sweeps through each of the wide beams in a specified order until at least one response from the responder UE 110-2 is detected. The initiator UE 110-1 then switches to a fine sweep stage in which the initiator UE 110 sequentially sweeps through each of the narrow beams of the set associated with the wide beam in which the responder UE 110-2 was detected until another response from the responder UE 110-2 is detected. This process is described in greater detail below with reference to FIGs. 6 and 7. In embodiments in which this coarse/fine beam width approach is implemented, the beamforming capability information 116 provided by the UE 110 further can include indications of which antenna modules 204 support this approach, in which frequency bands, and with identifiers of the particular wide beams and corresponding narrow beams supported by a given antenna module 204. [0047] Further, directional radiated power of an antenna module 204 plays a role in the beamsweeping process to be employed between the initiator DE 110-1 and the responder UE 110-2, and thus the UE 110 can include in the reported beamforming capability information 116 an indicator of one or more measures of the directional radiated power of each antenna module 204, such as an indicator of peak effective radiated power (ERP) or peak equivalent isotropically radiated power (EIRP) for the corresponding antenna module. For example, the base station 108 may utilize the reported ERP or EIRP of the UE 110 to determine whether a UE 110, as a candidate initiator UE 110-1 , can use widebeams to reach the responder UE 110-2, or if the UE 110 instead would need to rely on narrow beams to reach the responder UE 110-2.

[0048] The UEs 110-1 , 110-2 can provide their respective beamforming capability information 116 via one or more messages transmitted via the same frequency band that is to be used for the UE-to-UE ranging process, via a side frequency band, or a combination thereof. To illustrate, as mmWave 5G NR signaling typically is more reliant on directional signaling than LTE signaling, and as the purpose of ranging the responder UE 110-2 may be to provide the base station 104 the location and orientation of the responder UE 110-2 so that a mmWave-based 5G NR communication link can be subsequently established between the base station 104 and the responder UE 110-2, the responder UE 110-2 may provide its beamforming capability information 116-2 to the base station 104 via the LTE modem 206-1 (FIG.

2) and a communication link established in one or more LTE frequency bands, while the UE-to-UE ranging process is conducted by the 5G NR modem 206-2 via one or more mmWave frequency bands.

[0049] Although the base station 108 can configure a beamsweeping pattern (e.g., beamsweeping pattern 118, FIG. 1 ) to be employed by the UEs 110-1 , 110-2 during the UE-to-UE ranging process that sweeps a large portion of the entire angular space, this would be time and energy intensive. Accordingly, in at least one embodiment, the base station 108 reduces the beamsweeping effort by limiting the sweep to be more tightly focused on an angular region expected to cover the location of the responder UE 110-2. Accordingly, at block 420 the base station 108 determines the approximate locations of one or both of the initiator UE 110-1 and the responder UE 110-2. Although illustrated as following block 415 in the flow of method 400, this determination at block 420 can be made at any point prior to the final determination of the ranging beamforming configuration. To illustrate, the base station 108 may update the approximate locations on a periodic basis, in response to a handover or IA process, in response to triggering the UE-to-UE ranging process, and the like. The base station 104 can determine the approximate location of a UE using any of a variety of techniques, including obtaining a message from the UE that contains the current GPS or GNSS location of the UE, determining an approximate location of the UE based on analysis of the UE-reported Reference Strength Received Power (RSRP) parameter or other signal strength parameter reported by the UE for signaling from the base station 104, analysis of the timing advance employed for signaling with the UE, and the like.

[0050] With the beamforming capabilities, approximate locations, peak radiated power parameters, and other relevant parameters for the pair of UEs identified to participate in the UE-to-UE ranging process, at block 425 the base station 104 determines a ranging beamforming configuration 114 to be employed by the pair of UEs based on these inputs. To illustrate, as described above, the base station 104 may use the approximate locations of the UEs 110-1 , 110-2 to determine a region of the angular space (relative to the initiator UE 110-1) that is expected to cover the responder UE 110-2, identify a subset of beams that both cover that angular region and are supported by both the UE 110-1 and the UE 110-2, and then select some or all of the beams in this subset as the beams to be represented in the beam pattern 118 represented by the ranging beamforming configuration 114. In implementations in which the UEs 110-1 , 110-2 can support a coarse/fine beamsweeping approach (as indicated by, for example, the reported ERP or EIRP of the UE 110-1), the base station 108 can select for the beamsweeping pattern 118 a subset of the wide beams supported by both UEs that also represent an angular region covering an expected or approximate location of the responder UE 110-2, and then select for each wide beam of this subset a corresponding set of narrow beams that cover the angular section represented by the corresponding wide beam. The base station 108 then may determine the sequential ordering of these selected beams, such as in a clockwise order, counter-clockwise order, pseudorandom order, a binary search order, and the like.

[0051] Moreover, in some embodiments the base station 104 uses the ranging beamforming configuration 114 to specify a timing of the beamsweeping to be performed in accordance with the beamsweeping pattern 118, which can include the start time or window for ranging signal transmission for each beam in the beamsweeping pattern 118, a duration of the window and/or a duration of transmission of the ranging signal in each window, the start time or window and or duration for response signal transmission for each beam in the beamsweeping pattern 118, and the like. The base station 104 can specify this timing relative to a canonical clock signal, such as one broadcast by the base station 104, relative to certain time slots of a frame structure used for timing communications between the base station 104 and the UEs 110, based on a third-party clock reference, such as supplied by a satellite-based positioning system, or a combination thereof.

[0052] At block 430, the base station 104 transmits a representation of the ranging beamforming configuration 114 determined at block 425 to each of the initiator DE 110-1 and the responder UE 110-2. This information can be transmitted as, for example, one or more user-plane messages, one or more control-plane messages, or a combination thereof, and which can be transmitted using the same one or more frequency bands to be used for the ranging process or using a different set of one or more frequency bands. In response to receiving the ranging beamforming configuration 114, each of the UEs 110-1 , 110-2 stores and implements the ranging beamforming configuration 114 at the corresponding modems 206 and corresponding antenna modules 204 in preparation for conducting the UE-to-UE ranging process.

[0053] At block 435, in response to a specified start time, specified start slot, or other commencement trigger, the initiator UE 110-1 and responder UE 110-2 concurrently perform the ranging beamsweeping process based on the beamsweeping pattern 118 and other parameters represented in the implemented ranging beamforming configuration 114. As a general overview, this process provides for the initiator UE 110-1 to sequentially time-sweep through the indicated beams of the beamsweeping pattern 118 in the indicated order and with the indicated timing, where for each beam the initiator UE 110-1 transmits a specified ranging signal (or multiple instances of the ranging signal) in the corresponding beam direction and then monitors for at least one response signal from the responder UE 110-2. Concurrently, the responder UE 110-2 sequentially time-sweeps through the indicated beams of the beamsweeping pattern 118 in the same order and with the same timing, where for each beam the responder UE 110-2 monitors for the ranging signal(s) in the corresponding beam direction and, if detected, replies with a specified response signal in that same direction. In this manner, the initiator UE 110-1 can identify the angular relationship of the responder UE 110-2 relative to the initiator UE 110-1 based on the beam(s) in which a response signal from the responder UE 110-2 was detected, based on an Angle-of-Arrival (AoA) analysis of the received response signal(s), or a combination thereof. An example implementation of the process of block 435 is described in greater detail below with reference to FIG. 5.

[0054] After the ranging beamsweeping process of block 435 is completed, at block 440 the initiator UE 110-1 determines a distance of the responder UE 110-2 from the initiator UE 110-1 based on any of a variety of distance analyses applied to the response signal(s) received from the responder UE 110-2, such as a round trip time (RTT) analysis or other Time of Flight (T oF) analysis. T o illustrate, as the propagation speed of RF signals is constant, and if the timing of the ranging signal and start of the response window is known, then the initiator UE 110-1 can use a difference between the start of the response window and the receipt of the response signal from the responder UE 110-2 in that window to determine how long it took for the response signal to propagate from the responder UE 110-2 to the initiator UE 110-1 , and thus estimate the distance between the UE 110-1 and the UE 110-2.

[0055] With both the distance between the UEs 110-1 , 110-2 and the angular relationship between the UEs 110-1 , 110-2 known, the initiator UE 110-1 can range, or locate, the responder UE 110-2 relative to the initiator UE 110-1. As the location of the UE 110-1 is known, either through a GPS or GNSS location obtained by the UE 110-1 , through ranging of the UE 110-1 performed by the base station 104 via RSRP analysis or based on timing advancement, or through a previous UE-to-UE ranging process with the UE 110-1 as the ranged responder UE, the initiator UE 110-

1 can determine the location of the responder UE 110-2 relative to a specified reference frame based on the location of the UE 110-1 and the location of the UE 110-2 relative to the UE 110-1. The initiator UE 110-1 then can generate ranging data 124 (FIG. 1) representative of this determined location of the responder UE 110-

2 and employ this ranging data 124 in establishing a direct device-to-device link with the UE 110-2. Alternatively or additionally, the initiator UE 110-1 can transmit this ranging data 124 to the base station 104 so that the base station 104 can one or both of integrate the ranging data 124 to update or refine its location data for the UE 110-2 or transmit the ranging data 124 to other UEs 110 or other base stations for their use in updating the location of the UE 110-2 for their own beamforming processes or other purposes.

[0056] FIG. 5 illustrates an example implementation of the UE-to-UE beamsweeping process of block 435 of the method 400 of FIG. 4 in accordance with some embodiments. As noted above, the beamsweeping process includes concurrent, complementary operations by the initiator UE 110-1 and the responder UE 110-2, with the operations of the initiator UE 110-1 represented by subprocess 501 and the operations of the responder UE 110-2 represented by subprocess 502.

[0057] As explained above, the beamsweeping pattern 118 identifies a sequence or order of beams to be time-swept. Accordingly, at block 505 the initiator UE 110-1 selects the next (or first) beam in this sequence. Concurrently, at block 510 the responder UE 110-2 selects the same beam based on the same indicated beamsweeping pattern 118. These beams may be identified by a beam ID (e.g., SSB ID), by a particular set of phase weights or phase delays to apply to corresponding antenna elements of a specified antenna module of the UE, and the like.

[0058] In at least one embodiment, the ranging process employs a transmit-then- monitor approach at the initiator UE 110-1 and a complementary monitor-then- transmit approach at the responder UE 110-2. As such, the ranging beamforming configuration 114 may specify, for each beam in the sequence of beams, an initiator- TX window followed by a responder-TX window (each of which may be synchronized to a canonical base station clock reference or to a slot, frame, or other structure in the physical layer signaling provided by the base station 104). The initiator-TX window for a given beam is used by the initiator UE 110-1 to transmit at least one reference signal in the given beam and used by the responder UE 110-2 to monitor for receipt of this reference signal in the same beam. The responder-TX window for this given beam is then used by the responder UE 110-2 to transmit a response signal in the given beam if the ranging signal was detected in the preceding initiator- TX window and is thus used by the initiator UE 110-1 to monitor for receipt of this response signal in the given beam. Accordingly, at block 515 the initiator UE 110-1 waits for the start of the initiator-TX window for the beam selected at block 505 and at block 520 the responder UE 110-2 likewise waits for the start of the initiator-TX window.

[0059] When the initiator-TX window has commenced, at block 525 the initiator UE 110-1 transmits at least one ranging signal (a phase-coherent signal specified by, for example, the ranging beamforming configuration 114) in the beam direction of the beam selected at block 505. Concurrently, at block 530 the responder UE 110-2 monitors for reception of this at least one ranging signal. At block 535 the initiator UE 110-1 waits for the start of the responder-TX window for the selected beam and concurrently at block 540 the responder UE 110-2 waits for the start of this responder-TX window.

[0060] In the event that the responder UE 110-2 detects a ranging signal in the preceding initiator-TX window (block 530), at block 545 the responder UE 110-2 transmits at least one response signal with the commencement of the responder-TX window. In at least one embodiment, the at least one response signal is transmitted in the same/complementary beam as the beam direction employed to transmit the ranging signal that triggered the response signal. That is, the response signal is transmitted back in the same direction from which the ranging signal was received. The response signal can represent a binary detection of the ranging signal; that is, if a received strength parameter of the received ranging signal is above a specified threshold, then the responder UE 110-2 transmits the response signal, and otherwise refrains from transmitting the response signal, or provides for the response signal to represent a first value when the received ranging signal is of sufficient strength and provides for the response signal to represent a second value when the ranging signal is not detected at all or is detected at a strength below the specified threshold. In other embodiments, the response signal can represent one of a multitude of received-strength levels for a received ranging signal, such as a value of 0 for no ranging signal detected, a value of 1 for a weak ranging signal detected, a value of 2 for a medium-strength ranging signal detected, and a value of 3 for a strong ranging signal detected.

[0061] At block 550, the initiator UE 110-1 monitors for receipt of at least one response signal from the responder UE 110-2 during the responder-TX window. In the event that a response signal is not received or a response signal is received that indicates a weak or insufficiently strong receipt of the ranging signal, the beamsweeping process can continue using the next beam in the sequence specified by the beamsweeping pattern 118. Accordingly, at block 555 the initiator DE 110-1 determines whether the beam used in the most-recent iteration of subprocess 501 is the last beam in the beamsweeping pattern 118. If not, then the subprocess 501 returns to block 505 for another iteration using the next beam in the beamsweeping sequence. Concurrently, at block 560, the responder UE 110-2 determines whether the beam is the last beam in the sequence, and if not, then the subprocess 502 returns to block 510 for another iteration using the next beam in the beamsweeping sequence. Otherwise, if the last beam has been swept and the responder UE 110-2 has not detected a sufficiently-strong received ranging signal, this indicates that the responder UE 110-2 is likely out of transmission range of the initiator UE 110-1 or that an inadequate beamsweeping pattern was selected by the base station 104, and thus the initiator UE 110 can inform the base station 104 of this situation so that the base station 104 can either revise the ranging beamforming configuration 114 to employ a revised beamsweeping pattern 118 or the base station 104 can terminate the current UE-to-UE ranging process and then select a different UE to act as the initiator UE with a new ranging beamforming configuration based on the beamforming capabilities of this newly-selected UE. Conversely, if one or more response signals indicating receipt of sufficiently-strong ranging signals are received by the initiator UE 110-1 , the initiator UE 110-1 then initiates the process of analyzing the angular relationship of the responder UE 110-2 and the distance to the responder UE 110-2 using the one or more received response signals as described above with reference to block 440 of method 400.

[0062] FIG. 6 illustrates a method 600 representing a coarse stage/fine stage approach to the beamsweeping process of block 435 of method 400 in accordance with some embodiments. As noted above, the beamsweeping pattern 118 employed in the UE-to-UE ranging process can utilize a first stage in which a set of wide beams (with “wide” referring to a wider angular section or region covered by the beam) is time-swept concurrently by the initiator UE and the responder UE and once the responder UE is sufficiently located within a wide beam, a second stage is employed in which a set of narrow beams (with “narrow” referring to a narrower angular section or region covered by the beam) covering the same or similar angular region as the identified wide beam is time-swept to identify the narrow beam(s) that encompass the location of the responder UE. Accordingly, in this approach the base station 104 provides the ranging beamforming configuration 114 with a wide beam pattern specifying a set of wide beams and the order they are to be swept and a narrow beam pattern specifying sets of narrow beams, each set having combined coverage that substantially overlaps a corresponding wide beam.

[0063] Thus, at block 602 the initiator UE 110-1 and the responder UE 110-2 concurrently time-sweep the set of wide beams of the wide beam pattern until either a sufficient response from the responder UE 110-2 is detected or the last wide beam is swept without a sufficient response from the responder UE 110-2. Otherwise, if a sufficient response is detected at block 604, then at block 606 the initiator UE 110-1 and responder UE 110-2 switch to the narrow beam pattern that represents the coverage area of the wide beam that triggered the sufficient response from the responder UE 110-2 at block 604, and at block 608 the initiator UE 110-1 and the responder UE 110-2 concurrently time-sweep the set of narrow beams until either a sufficient response from the responder UE 110-2 is detected in one or more of the narrow beams or the last narrow beam is swept without a sufficient response from the responder UE 110-2. Assuming a sufficient response is detected in at least one narrow beam, the at least one narrow beam thus represents a finer-grained indication of the location of the responder UE 110-2 and thus permits the initiator UE 110-1 to determine the location of the responder UE 110-2 at a higher resolution, either directly from the direction associated form the narrow beam, from an AoA analysis of the narrow-beam reply from the responder UE 110-2, or a combination thereof.

[0064] FIG. 7 illustrates an example of the coarse/fine approach represented by method 600 of FIG. 6. In this simplified example, the base station 104 has specified a beamsweeping pattern having three wide beams, identified as WB3, WB4, WB5. The beamsweeping pattern then specifies three narrow beams for each wide beam, with the three narrow beams for wide beam WB3 identified as NB3-1 , NB3-2, and NB3-3, the three narrow beams for wide beam WB4 identified as NB4-1 , NB4-2, and NB4-3, and so on.

[0065] At stage 701 , the initiator UE 110-1 transmits a ranging signal for wide beam WB3 in the initiator-TX window 711 for this wide beam. As the coverage area of wide beam WB3 does not include the location of the responder UE 110-2 in this example, the ranging signal is not detected by the responder UE 110-2 in the initiator-TX window 711 and thus no response signal is sent in the corresponding responder-TX window 712 for wide beam WB3. At stage 702, the initiator UE 110 transmits a ranging signal for wide beam WB4 in the initiator-TX window 713 for this wide beam. In this case the coverage area for wide beam WB4 includes the location of the responder UE 110-2, and thus the responder UE 110-2 detects the ranging signal and responds with a response signal 710 in the corresponding responder-TX window 714 for wide beam WB4. As indicated by the “RX” in the responder-TX window 714, in this example the response signal 710 is a binary implementation in which transmission of a response signal indicates the responder UE 110-2 detected the transmitted ranging signal with sufficient strength, and the absence of a transmitted response signal indicates that the responder UE 110-2 did not detect the transmitted ranging signal with sufficient strength.

[0066] Based on the response signal 710, the initiator UE 110-1 and the responder UE 110-2 switch to a fine sweep configuration for the three narrow bands NB4-1 , NB4-1 , and NB4-3 representing the coverage area of the wide band in which the response signal 710 was sent, that is, wide band WB4. Thus, at stage 703 the initiator UE 110-1 selects the first of these narrow bands, NB4-1 , and transmits a ranging signal in the corresponding initiator-TX window 715. In this example, the location of the responder UE 110-2 is outside of the coverage area of the narrow band NB4-1 , so the responder UE 110-2 does not detect the ranging signal and thus refrains from transmitting a response signal in the corresponding responder-TX window 716. Likewise, at stage 704 the initiator UE 110-1 selects the next of these narrow bands, NB4-2, and transmits a ranging signal in the corresponding initiator-TX window 717. In this example, the location of the responder UE 110-2 is also outside of the coverage area of the narrow band NB4-2, so the responder UE 110-2 does not detect the ranging signal and thus refrains from transmitting a response signal in the corresponding responder-TX window 718. However, at stage 705, when the initiator UE 110-1 transmits a ranging signal in the corresponding initiator-TX window 719 for the third and last narrow band NB4-3, the responder UE 110-2 is in the coverage area of this narrow band and thus transmits a response signal 722 in the corresponding responder-TX window 720.

[0067] Based on one or both of the response signals 710 and 722, including the angular information indicated by these signals based on one or both of the beam directions of the corresponding beam used to transmit/receive the response signal or an AoA analysis of the response signal, and including the distance information indicated by a RTT or other ToF analysis of these signals, the initiator DE 110-1 can determine ranging data indicating a location of the responder UE 110-2 relative to the initiator UE 110-1 or relative to a specified general reference frame, and then provide this ranging data to one or more other network components or utilize the ranging data for direct communications with the responding UE 110-2.

[0068] FIGs. 8 and 9 are ladder diagrams illustrating two examples of the UE-to-UE ranging process described above. The ladder diagram 800 of FIG. 8 illustrates an example instance in which the base station 104 itself triggers the UE-to-UE ranging process. Accordingly, as an initial matter, the base station 104 provides timing synchronization 802 for the initiator UE 110-1 and responder UE 110-2, which can include the transmission of a canonical clock signal from the base station 104, instructions to use a canonical clock signal from another source, such as a GPS/GNSS timing reference, instructions to synchronize to a particular aspect of a wireless frame structure implemented by the base station 104, or the like. In this example, the base station 104 obtains beamforming capabilities prior to triggering the UE-led beamforming process, and thus the base station 104 transmits a request 804 for beamforming capabilities to both UE 110-1 and UE 110-2, in response to which the UEs report their respective beamforming capabilities 806, 807 indicating, for example, number and type of antenna modules supporting beamforming, the particular beams supported, wide/narrow beam capabilities, peak ERP or peak EIRP, approximate location indicators, and the like. As noted above, this can be obtained via the base station 104 transmitting a UE Capability Enquiry RRC message to each UE, and each UE then responding with a UE Capability Information RRC message.

[0069] Thereafter, a UE ranging trigger 808 is raised at the base station 104, such as in response to a periodic trigger or in response to the UE 110-2 being handed over to the base station 104. In response, as represented by block 810 the base station 104 selects the UE 110-1 and UE 110-2 as the initiator UE and responder UE for the UE- to-UE ranging process to come, and then the base station determines a ranging beamforming configuration based on the selected UE 110-1 , 110-2, their approximate locations, and their reported beamforming capabilities. The base station 104 then transmits the ranging beamforming configuration (block 812) to each of the UE 110-1 , 110-2. [0070] In response, and with synchronization to the specified reference clock or other timing reference, the initiator UE 110-1 and responder DE 110-2 concurrently timesweep through the beamsweeping pattern represented in the ranging beamforming configuration, with this process including, sequentially for each beam in the pattern in the specified order, the initiator UE 110-1 transmitting a ranging signal in the corresponding beam direction during a corresponding initiator-TX window (e.g., block 814), the responder UE 110-2 monitoring for the ranging signal in the same beam (e.g., block 816). In the event that the ranging signal for a given beam is not received by the responder UE 110-2 (as illustrated by the “X” in FIG. 8), then the responder UE 110-2 refrains from transmitting a response signal for that beam. However, if the responder UE 110-2 detects the transmitted ranging signal, the responder UE 110-2 transmits a response signal in the complementary beam direction during a corresponding responder-TX window (e.g., block 818), and the initiator UE 110-1 monitoring for the response signal during the responder-TX window (e.g., block 820). In the event that one or more response signals indicating sufficient received signal strength are received at the initiator UE 110-1 from the responder UE 110-2 (e.g., because the initiator UE 110-1 continues the beamsweeping pattern after receiving a first response signal), at block 822 the initiator UE 110-1 determines the location of the responder UE 110-2 from analysis of these one or more response signals using beam direction, AoA analysis, and/or RTT analysis. At block 824 the initiator UE 110-1 transmits ranging data representing the determined location of the responder UE 110-2 to the base station 104.

[0071] The ladder diagram 900 of FIG. 9 illustrates an example instance in which a UE requests the UE-to-UE ranging process. As with the ladder diagram 800 of FIG.

8, in this example the base station 104 provides timing synchronization 902 for the initiator UE 110-1 and responder UE 110-2. The UE 110-1 then transmits a ranging request 904 to the base station 104, with this request identifying the UE 110-2 as the UE to be ranged. In this example, the UE 110-1 reports its beamforming capabilities 906 in a UE Capability Information RRC message or other format with or following the ranging request 904 in anticipation of the base station 104 needing the information. Further in this example, the base station 104 has not yet obtained the beamforming capabilities of the UE 110-2, and thus the base station 104 transmits a request 908 for beamforming capabilities to the UE 110-2, in response to which the UE 110-2 reports its beamforming capabilities 910. [0072] In response, as represented by block 912 the base station 104 determines a ranging beamforming configuration based on the requesting UE 110-1 as initiator UE and the target UE 1 10-2 as responder UE, their approximate locations, and their reported beamforming capabilities. The base station 104 then transmits the ranging beamforming configuration (block 914) to each of the UE 110-1 , 110-2.

[0073] In response, and with synchronization to the specified reference clock or other timing reference, at block 916 the initiator UE 110-1 and responder UE 110-2 concurrently time-sweep through the beamsweeping pattern represented in the ranging beamforming configuration in the manner described above, and at block 918 the initiator UE 110-1 determines the location of the responder UE 110-2 from analysis of these one or more response signals using beam direction, AoA analysis, and/or RTT analysis. At block 920 the initiator UE 110-1 transmits ranging data representing the determined location of the responder UE 110-2 to the base station 104.

[0074] In some embodiments, certain aspects of the techniques described above may implemented by one or more processors of a processing system executing software. The software comprises one or more sets of executable instructions stored or otherwise tangibly embodied on a non-transitory computer readable storage medium. The software can include the instructions and certain data that, when executed by the one or more processors, manipulate the one or more processors to perform one or more aspects of the techniques described above. The non-transitory computer readable storage medium can include, for example, a magnetic or optical disk storage device, solid state storage devices such as Flash memory, a cache, random access memory (RAM) or other non-volatile memory device or devices, and the like. The executable instructions stored on the non-transitory computer readable storage medium may be in source code, assembly language code, object code, or other instruction format that is interpreted or otherwise executable by one or more processors.

[0075] A computer readable storage medium may include any storage medium, or combination of storage media, accessible by a computer system during use to provide instructions and/or data to the computer system. Such storage media can include, but is not limited to, optical media (e.g., compact disc (CD), digital versatile disc (DVD), Blu-Ray disc), magnetic media (e.g., floppy disc , magnetic tape, or magnetic hard drive), volatile memory (e.g., random access memory (RAM) or cache), non-volatile memory (e.g., read-only memory (ROM) or Flash memory), or microelectromechanical systems (MEMS)-based storage media. The computer readable storage medium may be embedded in the computing system (e.g., system RAM or ROM), fixedly attached to the computing system (e.g., a magnetic hard drive), removably attached to the computing system (e.g., an optical disc or Universal Serial Bus (USB)-based Flash memory), or coupled to the computer system via a wired or wireless network (e.g., network accessible storage (NAS)).

[0076] Note that not all of the activities or elements described above in the general description are required, that a portion of a specific activity or device may not be required, and that one or more further activities may be performed, or elements included, in addition to those described. Still further, the order in which activities are listed are not necessarily the order in which they are performed. Also, the concepts have been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present disclosure as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present disclosure.

[0077] Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims. Moreover, the particular embodiments disclosed above are illustrative only, as the disclosed subject matter may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. No limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope of the disclosed subject matter. Accordingly, the protection sought herein is as set forth in the claims below.

Claims

32 WHAT IS CLAIMED IS:

1. A method, by a first user equipment (UE) (110-1 ) in a cellular network (100), comprising: transmitting first capability information (116-1 ) to a base station (106) of the cellular network, the first capability information representing one or more beamforming capabilities of the first UE; receiving a ranging beamforming configuration (114) for ranging a second UE (110-2) using radio frequency (RF) resources configured for the first UE, the ranging beamforming configuration based on the first capability information and representing at least a beamsweeping pattern (1 18) of beams supported by the RF resources configured for the first UE; and ranging the second UE using the beamsweeping pattern to determine ranging data (124) representative of a location of the second UE.

2. The method of claim 1 , wherein the ranging beamforming configuration is further based on second capability information (116-2) provided by the second UE, the second capability information representing one or more beamforming capabilities of the second UE, and wherein the beamsweeping pattern includes a subset of beams identified as supported by both the first UE and the second UE based on the first capability information and the second capability information.

3. The method of any of claims 1 or 2, wherein the ranging beamforming configuration is based on an approximate location of at least one of the first UE and the second UE.

4. The method of any of claims 1 to 3, further comprising: transmitting, to the base station, a ranging request (904) for ranging the second UE; and wherein receiving the ranging beamforming configuration comprises receiving the ranging beamforming configuration responsive to the ranging request. 33 method of any of claims 1 to 4, wherein the one or more beamforming capabilities of the first UE represented in the first capability information includes at least one of: an indicator of a number of antenna modules implemented at the first UE; an identifier of each beam supported by a specified antenna module; a set of wide beams and corresponding narrow beams supported by a specified antenna module; or an indicator of a radiated power capability of the first UE. method of any of claims 1 to 5, wherein the ranging beamforming configuration further includes an indication of a timing reference (802, 902) for synchronization of the ranging of the second UE using the beamsweeping pattern, wherein the timing reference is a clock reference provided by the base station. method of any of claims 1 to 6, wherein ranging the second UE using the beamsweeping pattern comprises: sequentially transmitting a specified ranging signal (120) in each beam of a subset of one or more beams specified by the beamsweeping pattern in an order specified by the beamsweeping pattern; monitoring for receipt of a response signal (122) from the second UE following each transmission of the ranging signal; and determining the location of the second UE based on the beam associated with receipt of the response signal. method of claim 7, wherein determining the location of the second UE is further based on at least one of a round trip time (RTT) analysis by the first UE using the response signal or an angle-of-arrival (AoA) analysis by the first UE using the response signal. method of any of claims 1 to 6, wherein ranging the second UE using the beamsweeping pattern includes determining the location of the second UE based on at least one of a round trip time (RTT) analysis or an angle-of-arrival (AoA) analysis by the first UE using a response signal (122) from the second UE transmitted in response to a ranging signal (120) transmitted by the first UE in accordance with the beamsweeping pattern. e method of any of claims 1 to 9, wherein: the beamsweeping pattern represents a subset of wide beams and, for each wide beam, a corresponding set of narrow beams; and ranging the second UE using the beamsweeping pattern comprises: sequentially transmitting a first ranging signal in each of one or more wide beams of the subset in an order specified by the beamsweeping pattern; monitoring for a first response signal from the second UE following each transmission of the first ranging signal; responsive to detecting the first response signal, sequentially transmitting a second ranging signal in each of one or more narrow beams of the set of narrow beams corresponding to the wide beam associated with detection of the first response signal; monitoring for a second response signal from the second UE following each transmission of the second ranging signal; and determining the location of the second UE based on the narrow beam associated with receipt of the second response signal. e method of any of claims 1 to 10, further comprising: transmitting the ranging data to the base station. user equipment (110) comprising: a radio frequency (RF) front end (202) comprising one or more antenna modules (204); a processor (216) coupled to the RF front end; and a memory (218) coupled to the processor and storing a set of executable instructions (220) configured to manipulate the processor and the RF front end to perform the method of any of claims 1 to 11 . method, by a base station (106) in a cellular network (100), comprising: receiving first capability information (116-1 ) from a first user equipment (UE) (110-1) and second capability information (116-2) from a second UE (110-1), the first capability information representing one or more beamforming capabilities of the first UE and the second capability information representing one or more beamforming capabilities of the second UE; determining a ranging beamforming configuration (114) based on the first capability information and the second capability information, the ranging beamforming configuration representing at least a beamsweeping pattern (118) for use by the first UE and second UE in ranging the second UE via the first UE; transmitting the ranging beamforming configuration to the first UE and the second UE; and receiving ranging data (124) from the first UE, the ranging data indicating a location of the second UE determined by the first UE using the ranging beamforming configuration. e method of claim 13, wherein: the one or more beamforming capabilities includes at least one of: an indicator of a number of implemented antenna modules; an identifier of each beam supported by a specified antenna module; and a set of wide beams and corresponding narrow beams supported by a specified antenna module; and determining the ranging beamforming configuration comprises one of: identifying a subset of beams supported by both the first UE and the second UE based on the first capability information and the second capability information and determining an order of the subset of beams to be implemented in the beamsweeping pattern; or identifying a subset of wide beams supported by both the first UE and the second UE based on the first capability information and the second capability information, identifying a set of narrow beams supported by both the first UE and the second UE for each wide beam of the subset of wide beams, determining an order of the subset of wide beams to be implemented in the beamsweeping pattern, and determining an order of the set of narrow beams to be implemented in the beamsweeping pattern for each wide beam of the subset. 36 base station (106) comprising: a radio frequency (RF) front end (302) comprising one or more antenna modules; a processor (308) coupled to the RF front end; and a memory (310) coupled to the processor and storing a set of executable instructions (312) configured to manipulate the processor and the RF front end to perform the method of claim 13 or 14.