Fallback Procedures When Path Loss or Spatial Transmit Quasi-Collocation (QCL) Referencing from Neighboring Cells is Failed for Sounding Reference Signal (SRS) for Positioning

Abstract

To provide a method for transmitting an uplink reference signal for receiving and measuring a positioning configuration.SOLUTION: In wireless communication, a user equipment (UE) receives a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating a downlink path loss or determining an uplink spatial transmit beam (810), determines that a first downlink reference signal received from the neighboring cell cannot be used for estimating the downlink path loss or determining the uplink spatial transmit beam (820), in response to the determination, estimates the downlink path loss or determines the uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or a serving cell for the UE (830), and transmits an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof (840).SELECTED DRAWING: Figure 8

Description

Priority claims

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 850,503, filed May 20, 2019, entitled "REPORTING OF INFORMATION RELATED TO SOUNDING REFERENCE SIGNALS (SRS) TIMING ADJUSTMENTS," and U.S. Provisional Patent Application No. 16 / 876,851, filed May 18, 2020, entitled "FALLBACK PROCEDURES WHEN THE PATH LOSS OR SPATIAL TRANSMIT QUASI-COLLOCATION (QCL) REFERENCE FROM NEIGHBORING CELLS IS FAILING FOR SOUNDING REFERENCE SIGNALS (SRS) FOR POSITIONING," both of which are assigned to the assignee of the present patent application and are expressly incorporated herein by reference in their entireties. [Technical Field]

[0002] Aspects of the present disclosure relate generally to telecommunications, and more particularly to reporting information related to uplink reference signal timing adjustments for improved uplink reference signal processing. [Background technology]

[0003] Wireless communication systems have evolved through various generations, including first-generation analog wireless telephone service (1G), second-generation (2G) digital wireless telephone service (including interim 2.5G and 2.75G networks), third-generation (3G) high-speed data Internet-enabled wireless service, and fourth-generation (4G) service (e.g., Long Term Evolution (LTE) or WiMax). Currently, many different types of wireless communication systems are in use, including cellular and personal communications services (PCS) systems. Examples of known cellular systems include the cellular analog advanced mobile phone system (AMPS) and digital cellular systems based on code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), the Global System for Mobile access (GSM) variant of TDMA, and the like.

[0004]

[0004] The fifth-generation (5G) wireless standard, called New Radio (NR), requires faster data rates, a larger number of connections, and better coverage, among other improvements. According to the Next Generation Mobile Network Alliance, the 5G standard is designed to provide data rates of tens of megabits per second to each of tens of thousands of users, delivering 1 gigabit per second to dozens of workers on an office floor. To support large-scale sensor deployments, hundreds of thousands of simultaneous connections should be supported. Therefore, the spectral efficiency of 5G mobile communications should be significantly improved compared to the current 4G standard. Furthermore, signaling efficiency should be improved and latency should be significantly reduced compared to current standards.

[0005]

[0005] To support position estimation in terrestrial wireless networks, a mobile device may be configured to measure and report the observed time difference of arrival (OTDOA) or reference signal timing difference (RSTD) between reference signals received from two or more network nodes (e.g., different base stations or different transmission points (e.g., antennas) belonging to the same base station). Summary of the Invention

[0006] The following presents a simplified summary of one or more aspects disclosed herein. As such, the following summary is not intended to be an extensive overview of all contemplated aspects, nor is it intended to identify key or critical elements of all contemplated aspects or to delineate the scope associated with any particular aspect. As such, the following summary is intended only to present some concepts of one or more aspects of the mechanisms disclosed herein in a simplified form as a prelude to the more detailed description presented later.

[0007]

[0007] In one aspect, a method of wireless communication implemented by a user equipment (UE) includes receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmit beam; determining that the first downlink reference signal received from the neighboring cell cannot be used for estimating downlink path loss or determining an uplink spatial transmit beam; in response to the determination, performing a downlink path loss estimation or an uplink spatial transmit beam determination based on a second downlink reference signal received from the neighboring cell or a serving cell; and transmitting an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof.

[0008]

[0008] In one aspect, a method of wireless communication implemented by a location server includes configuring a UE to receive at least a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam; receiving a report from the UE indicating the signal quality of the first downlink reference signal; and configuring the UE to receive at least a second downlink reference signal from the neighboring cell or a serving cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0009]

[0009] In one aspect, a method of wireless communication implemented by a UE includes receiving from a network node a configuration to use at least a first downlink reference signal from a neighboring cell to estimate downlink path loss or determine an uplink spatial transmission beam; sending a report to the network node indicating the signal quality of the first downlink reference signal; and receiving from the network node a configuration to use at least a second downlink reference signal from the neighboring cell or a serving cell to estimate downlink path loss or determine an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0010]

[0010] In one aspect, a UE includes a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: receive a positioning configuration via the at least one transceiver, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmit beam; determine that the first downlink reference signal received from the neighboring cell cannot be used for estimating downlink path loss or determining an uplink spatial transmit beam; in response to the determination, estimate downlink path loss or determine an uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or the serving cell; and cause an uplink reference signal for positioning to be transmitted from the at least one transceiver based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof.

[0011]

[0011] In one aspect, the location server includes a memory, at least one network interface, and at least one processor communicatively coupled to the memory and the at least one network interface, wherein the at least one processor is configured to: configure the UE to receive at least a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam; receive a report from the UE indicating the signal quality of the first downlink reference signal; and configure the UE to receive at least a second downlink reference signal from the neighboring cell or the serving cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0012]

[0012] In one aspect, the UE includes a memory, at least one transceiver, and at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor is configured to: receive from a network node a configuration to use at least a first downlink reference signal from a neighboring cell to estimate downlink path loss or determine an uplink spatial transmission beam; send a report to the network node indicating the signal quality of the first downlink reference signal; and receive from the network node a configuration to use at least a second downlink reference signal from a neighboring cell or a serving cell to estimate downlink path loss or determine an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0013]

[0013] In one aspect, the UE includes means for receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for downlink path loss estimation or uplink spatial transmit beam determination; means for determining that the first downlink reference signal received from the neighboring cell cannot be used for downlink path loss estimation or uplink spatial transmit beam determination; means for, in response to the determination, estimating downlink path loss or determining uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or the serving cell; and means for transmitting an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof.

[0014]

[0014] In one aspect, the location server includes means for configuring the UE to receive at least a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam; means for receiving a report from the UE indicating the signal quality of the first downlink reference signal; and means for configuring the UE to receive at least a second downlink reference signal from the neighboring cell or the serving cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0015]

[0015] In one aspect, the UE includes means for receiving from a network node a configuration to use at least a first downlink reference signal from a neighboring cell to estimate downlink path loss or determine an uplink spatial transmission beam; means for sending a report to the network node indicating the signal quality of the first downlink reference signal; and means for receiving from the network node a configuration to use at least a second downlink reference signal from a neighboring cell or a serving cell to estimate downlink path loss or determine an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0016]

[0016] In one aspect, a non-transitory computer-readable medium storing computer-executable instructions includes computer-executable instructions comprising: at least one instruction to instruct a UE to receive a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmit beam; at least one instruction to instruct the UE to determine that the first downlink reference signal received from the neighboring cell cannot be used for estimating downlink path loss or determining an uplink spatial transmit beam; at least one instruction to instruct the UE, in response to the determination, to estimate downlink path loss or determine an uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or the serving cell; and at least one instruction to instruct the UE to transmit an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof.

[0017]

[0017] In one aspect, a non-transitory computer-readable medium storing computer-executable instructions includes computer-executable instructions comprising: at least one instruction to instruct a location server to configure the UE to receive at least a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam; at least one instruction to instruct the location server to receive a report from the UE indicating the signal quality of the first downlink reference signal; and at least one instruction to instruct the location server to configure the UE to receive at least a second downlink reference signal from a neighboring cell or a serving cell to be used for estimating downlink path loss or determining an uplink spatial transmission beam, based on the signal quality of the first downlink reference signal being below a threshold.

[0018]

[0018] In one aspect, a non-transitory computer-readable medium storing computer-executable instructions includes computer-executable instructions comprising: at least one instruction to instruct a UE to receive from a network node a configuration that uses at least a first downlink reference signal from a neighboring cell to estimate downlink path loss or determine an uplink spatial transmission beam; at least one instruction to instruct the UE to send a report to the network node indicating the signal quality of the first downlink reference signal; and at least one instruction to instruct the UE to receive from the network node a configuration that uses at least a second downlink reference signal from a neighboring cell or a serving cell to estimate downlink path loss or determine an uplink spatial transmission beam based on the signal quality of the first downlink reference signal being below a threshold.

[0019] Other objects and advantages associated with the embodiments disclosed herein will be apparent to those skilled in the art based on the accompanying drawings and detailed description.

[0020]

[0020] The accompanying drawings are presented to aid in the description of various aspects of the present disclosure and are provided solely to illustrate, not limit, the aspects. [Brief explanation of the drawings]

[0021] [Figure 1]

[0021] FIG. 1 illustrates an example wireless communication system according to various aspects of the present disclosure. [Figure 2A]

[0022] FIG. 1 illustrates an example wireless network structure in accordance with various aspects of the present disclosure. [Figure 2B]

[0022] FIG. 1 illustrates an example wireless network structure according to various aspects of the present disclosure. [Figure 3A]

[0023] FIG. 1 is a simplified block diagram of several sample aspects of components that may be employed in a wireless communication node and configured to support communication, in accordance with various aspects of the present disclosure. [Figure 3B]

[0023] FIG. 1 is a simplified block diagram of several illustrative aspects of components that may be employed in a wireless communication node and configured to support communication in accordance with various aspects of the present disclosure. [Figure 3C]

[0023] FIG. 1 is a simplified block diagram of several illustrative aspects of components that may be employed in a wireless communication node and configured to support communication in accordance with various aspects of the present disclosure. [Figure 4A]

[0024] 1 illustrates an example frame structure and channels within the frame structure, according to aspects of the present disclosure. [Figure 4B]

[0024] FIG. 1 illustrates an example frame structure and channels within the frame structure, according to aspects of the present disclosure. [Figure 4C]

[0024] FIG. 1 illustrates an example frame structure and channels within the frame structure, according to aspects of the present disclosure. [Figure 4D]

[0024] FIG. 1 illustrates an example frame structure and channels within the frame structure, according to aspects of the present disclosure. [Figure 5A]

[0025] FIG. 1 illustrates an example random access procedure according to an aspect of the present disclosure. [Figure 5B]

[0025] FIG. 1 illustrates an example random access procedure according to an aspect of the present disclosure. [Figure 6]

[0026] FIG. 10 is a diagram of an example random access based SpCell beam failure recovery procedure, according to aspects of the present disclosure. [Figure 7]

[0027] 1 illustrates an example technique for determining a location of a mobile device using information obtained from multiple base stations. [Figure 8]

[0028] FIG. 1 illustrates an example method of wireless communication according to aspects of the present disclosure. [Figure 9]

[0028] FIG. 1 illustrates an exemplary method of wireless communication according to an aspect of the present disclosure. [Figure 10]

[0028] FIG. 1 illustrates an exemplary method of wireless communication according to an aspect of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0022]

[0029] Aspects of the present disclosure are provided in the following description and related drawings, directed to various examples provided for purposes of illustration. Alternative aspects may be devised without departing from the scope of the present disclosure. Additionally, well-known elements of the present disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the present disclosure.

[0023]

[0030] The words "exemplary" and / or "example" are used herein to mean "serving as an example, instance, or illustration." Any aspect described herein as "exemplary" and / or "example" is not necessarily to be construed as preferred or advantageous over other aspects. Likewise, the term "aspects of the present disclosure" does not require that all aspects of the present disclosure include the discussed feature, advantage or mode of operation.

[0024]

[0031] Those skilled in the art will appreciate that the information and signals described below may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the following description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof, depending in part on the particular application, desired design, corresponding technology, etc.

[0025]

[0032] Further, many aspects are described in terms of sequences of actions to be performed, for example, by elements of a computing device. It will be recognized that various actions described herein can be performed by particular circuitry (e.g., an application-specific integrated circuit (ASIC)), or by program instructions executed by one or more processors, or by a combination thereof. In addition, the sequences of actions described herein can be considered to be embodied entirely in any form of non-transitory computer-readable storage medium having stored thereon corresponding sets of computer instructions that, when executed, cause or instruct associated processors of a device to perform the functionality described herein. Accordingly, various aspects of the present invention may be embodied in several different forms, all of which are contemplated to be within the scope of the claimed subject matter. Additionally, for each aspect described herein, the corresponding form of any such aspect may be described herein, for example, as “logic configured to” perform the described actions.

[0026]

[0033] As used herein, the terms “user equipment” (UE) and “base station” are not intended to be specific or otherwise limited to any particular radio access technology (RAT) unless otherwise specified. In general, a UE may be any wireless communication device (e.g., a mobile phone, a router, a tablet computer, a laptop computer, a tracking device, a wearable (e.g., a smart watch, glasses, an augmented reality (AR) / virtual reality (VR) headset, etc.), a vehicle (e.g., a car, a motorcycle, a bicycle, etc.), an Internet of Things (IoT) device, etc.) used by a user to communicate over a wireless communication network. A UE may be mobile or (e.g., at some point) stationary and may communicate with a radio access network (RAN). As used herein, the term “UE” may be referred to interchangeably as an “access terminal” or “AT,” a “client device,” a “wireless device,” a “subscriber device,” a “subscriber terminal,” a “subscriber station,” a “user terminal” or “UT,” a “mobile terminal,” a “mobile station,” or variations thereof. In general, a UE may communicate with a core network via a RAN, through which the UE may be connected to external networks such as the Internet and other UEs. Of course, other mechanisms for connecting to the core network and / or the Internet are also possible for the UE, such as via a wired access network, a wireless local area network (WLAN) network (eg, based on IEEE 802.11, etc.).

[0027]

[0034] Depending on the network in which the base station is deployed, a base station may operate according to one of several RATs when communicating with UEs, and the base station may alternatively be referred to as an access point (AP), network node, NodeB, evolved NodeB (eNB), New Radio (NR) NodeB (also referred to as gNB or gNodeB), etc. Additionally, in some systems, the base station may provide purely edge node signaling functionality, while in other systems, the base station may provide additional control and / or network management functionality. The communication links through which a UE may send signals to a base station are referred to as uplink (UL) channels (e.g., reverse traffic channel, reverse control channel, access channel, etc.). The communication links through which a base station may send signals to a UE are referred to as downlink (DL) or forward link channels (e.g., paging channel, control channel, broadcast channel, forward traffic channel, etc.). As used herein, the term traffic channel (TCH) can refer to either an uplink / reverse or downlink / forward traffic channel.

[0028]

[0035] The term "base station" may refer to a single physical transmission / reception point (TRP) or multiple physical TRPs, which may or may not be collocated. For example, when the term "base station" refers to a single physical TRP, the physical TRP may be an antenna of the base station corresponding to the base station's cell. When the term "base station" refers to multiple collocated physical TRPs, the physical TRP may be an array of base station antennas (e.g., as in a multiple-input multiple-output (MIMO) system or when the base station employs beamforming). When the term "base station" refers to multiple non-collocated physical TRPs, the physical TRP may be a distributed antenna system (DAS) (a network of spatially separated antennas connected to a common source via a transport medium) or a remote radio head (RRH) (a remote base station connected to a serving base station). Alternatively, the non-collocated physical TRP may be a serving base station that receives measurement reports from a UE and a neighbor base station whose reference signal the UE is measuring. A TRP is a point at which a base station transmits and receives wireless signals, so that in this specification, references to transmission from or reception at a base station should be understood as references to the particular TRP of the base station.

[0029]

[0036] A radio frequency (RF) signal comprises electromagnetic waves of a given frequency that carry information through space between a transmitter and a receiver. As used herein, a transmitter may transmit a single RF signal or multiple RF signals to a receiver. However, the receiver may receive multiple RF signals corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through a multipath channel. The same transmitted RF signal on different paths between the transmitter and receiver may be referred to as a "multipath" RF signal.

[0030]

[0037] According to various aspects, FIG. 1 illustrates an exemplary wireless communication system 100. The wireless communication system 100 (sometimes referred to as a wireless wide area network (WWAN)) may include various base stations 102 (labeled “BS”) and various UEs 104. The base stations 102 may include macrocell base stations (high-power cellular base stations) and / or small cell base stations (low-power cellular base stations). In one aspect, the macrocell base stations 102 may include eNBs in the case where the wireless communication system 100 corresponds to an LTE network, or gNBs in the case where the wireless communication system 100 corresponds to an NR network, or a combination of both, and the small cell base stations 102′ may include femtocells, picocells, microcells, etc.

[0031]

[0038] The base stations 102 may collectively form a RAN and may interface with a core network 170 (e.g., Evolved Packet Core (EPC) or Next Generation Core (NGC)) via backhaul links 122, and may interface to one or more location servers 172 via the core network 170. In addition to other functions, the base stations 102 may perform functions related to one or more of the following: forwarding of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection setup and release, load balancing, distribution for Non-Access Stratum (NAS) messages, NAS node selection, synchronization, RAN sharing, Multimedia Broadcast Multicast Services (MBMS), subscriber and equipment tracing, RAN Information Management (RIM), paging, positioning, and delivery of alert messages. The base stations 102 may communicate with each other directly or indirectly (e.g., via EPC / NGC) via backhaul links 134, which may be wired or wireless.

[0032]

[0039] The base stations 102 may communicate wirelessly with the UEs 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. In one aspect, within each geographic coverage area 110, one or more cells may be supported by the base station 102. A “cell” is a logical communication entity used for communication with the base station (e.g., over some frequency resource referred to as a carrier frequency, component carrier, carrier, band, etc.) and may be associated with an identifier (e.g., physical cell identifier (PCI), virtual cell identifier (VCI)) to distinguish between cells operating over the same or different carrier frequencies. In some cases, different cells may be configured according to different protocol types (e.g., machine type communication (MTC), narrowband IoT (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of UEs. Because a cell is supported by a particular base station, the term “cell” can refer to either or both the logical communication entity and its supporting base station, depending on the context. In some cases, the term "cell" may also refer to the geographic coverage area (e.g., sector) of a base station, so long as the carrier frequency can be detected and used for communication within some portion of the geographic coverage area 110.

[0033]

[0040] The geographic coverage areas 110 of neighboring macrocell base stations 102 may partially overlap (e.g., in handover regions), but some of the geographic coverage areas 110 may substantially overlap with larger geographic coverage areas 110. For example, a small cell base station 102' (labeled "SC" for "small cell") may have a geographic coverage area 110' that substantially overlaps with the geographic coverage area 110 of one or more macrocell base stations 102. A network including both small cell base stations and macrocell base stations may be known as a heterogeneous network. A heterogeneous network may also include Home eNBs (HeNBs), which may serve restricted groups known as Closed Subscriber Groups (CSGs).

[0034]

[0041] The communication link 120 between the base station 102 and the UE 104 may include uplink (also called reverse link) transmissions from the UE 104 to the base station 102 and / or downlink (DL) (also called forward link) transmissions from the base station 102 to the UE 104. The communication link 120 may use MIMO antenna techniques, including spatial multiplexing, beamforming, and / or transmit diversity. The communication link 120 may be over one or more carrier frequencies. The allocation of carriers may be asymmetric between the downlink and uplink (e.g., more or fewer carriers may be allocated to the downlink than the UL).

[0035]

[0042] The wireless communication system 100 may further include a wireless local area network (WLAN) access point (AP) 150 that communicates with one or more WLAN stations (STAs) 152 via communication links 154 in an unlicensed frequency spectrum (e.g., 5 GHz). When communicating in the unlicensed frequency spectrum, the WLAN STAs 152 and / or the WLAN AP 150 may perform a clear channel assessment (CCA) or listen-before-talk (LBT) procedure before communicating to determine if a channel is available.

[0036]

[0043] The small cell base station 102' may operate in a licensed and / or unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell base station 102' may employ LTE or NR technology and may use the same 5 GHz unlicensed frequency spectrum used by the WLAN AP 150. A small cell base station 102' employing LTE / 5G in an unlicensed frequency spectrum can enhance coverage for and / or increase the capacity of an access network. NR in an unlicensed spectrum may be referred to as NR-U. LTE in an unlicensed spectrum may be referred to as LTE-U, licensed assisted access (LAA), or MultiFire.

[0037]

[0044] The wireless communication system 100 may further include a millimeter-wave (mmW) base station 180 that may operate at millimeter-wave (mmW) and / or near-mmW frequencies in communication with the UE 182. Extremely high frequency (EHF) is a portion of RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 and 10 millimeters. Radio waves in this band are sometimes referred to as millimeter waves. Near-mmW can extend down to frequencies of 3 GHz with wavelengths of 100 millimeters. The very high frequency (SHF) band ranges between 3 and 30 GHz and is also referred to as centimeter waves. Communications using the mmW / near-mmW radio frequency band have high path loss and relatively short range. The mmW base station 180 and the UE 182 may utilize beamforming (transmit and / or receive) over the mmW communication link 184 to compensate for the very high path loss and short range. It will be understood that in alternative configurations, one or more base stations 102 may also transmit using mmW or near-mmW and beamforming. Therefore, it will be understood that the foregoing exemplification is illustrative only and should not be construed as limiting the various aspects disclosed herein.

[0038]

[0045] Transmit beamforming is a technique for focusing an RF signal in a particular direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omnidirectionally). With transmit beamforming, the network node determines where a given target device (e.g., a UE) is located (relative to the transmitting network node) and emits a stronger downlink RF signal in that particular direction, thereby providing a faster (in terms of data rate) and stronger RF signal to the receiving device. To change the directionality of the RF signal during transmission, the network node can control the phase and relative amplitude of the RF signal at each of one or more transmitters broadcasting the RF signal. For example, the network node may use an array of antennas (called a “phased array” or “antenna array”) that produces a beam of RF waves that can be “steered” to point in different directions without actually moving the antennas. Specifically, RF current from a transmitter is supplied to each antenna in the correct phase relationship, so that the radio waves from the separate antennas combine to increase radiation in desired directions and cancel to suppress radiation in undesired directions.

[0039]

[0046] A transmit beam may be quasi-collocated, meaning that the transmit beam appears to a receiver (e.g., a UE) to have the same parameters regardless of whether the network node's transmit antennas themselves are physically collocated. In NR, there are four types of quasi-collocated (QCL) relationships. Specifically, a given type of QCL relationship means that some parameters for a second reference signal on a second beam can be derived from information about a source reference signal on a source beam. Thus, if the source reference signal is QCL type A, the receiver can use the source reference signal to estimate the Doppler shift, Doppler spread, mean delay, and delay spread of a second reference signal transmitted on the same channel. If the source reference signal is QCL type B, the receiver can use the source reference signal to estimate the Doppler shift and Doppler spread of a second reference signal transmitted on the same channel. If the source reference signal is QCL type C, the receiver can use the source reference signal to estimate the Doppler shift and mean delay of a second reference signal transmitted on the same channel. If the source reference signal is QCL type D, the receiver can use the source reference signal to estimate the spatial reception parameters of a second reference signal transmitted on the same channel.

[0040]

[0047] In receive beamforming, a receiving user uses a receive beam to amplify RF signals detected on a given channel. For example, the receiver can increase the gain setting and / or adjust the phase setting of an antenna array in a particular direction to amplify (e.g., raise the gain level) RF signals received from that direction. Thus, when a receiver is said to beamform in a certain direction, this means that the beam gain in that direction is relatively high compared to the beam gains along other directions, or that the beam gain in that direction is the highest compared to the beam gains in that direction of all other receive beams available to the receiver. As a result, the received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) of RF signals received from that direction is stronger.

[0041]

[0048] The transmit beam and the receive beam may be spatially related. The spatial relationship means that parameters of a second beam (e.g., a transmit or receive beam) for a second reference signal can be derived from information about a first beam (e.g., a receive or transmit beam) for a first reference signal. For example, a UE may use a particular receive beam to receive a reference downlink reference signal (e.g., a synchronization signal block (SSB)) from a base station. The UE can then form a transmit beam for sending an uplink reference signal (e.g., a sounding reference signal (SRS)) to this base station based on the parameters of the receive beam.

[0042]

[0049] Note that a "downlink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if a base station forms a downlink beam to transmit a reference signal to a UE, the downlink beam is a transmit beam. However, if the UE forms a downlink beam, it is a receive beam for receiving a downlink reference signal. Similarly, an "uplink" beam can be either a transmit beam or a receive beam, depending on the entity that forms it. For example, if a base station forms an uplink beam, it is an uplink receive beam, and if the UE forms an uplink beam, it is an uplink transmit beam.

[0043]

[0050] In 5G, the frequency spectrum in which wireless nodes (e.g., base station 102 / 180, UE 104 / 182) operate is divided into multiple frequency ranges: FR1 (450-6000 MHz), FR2 (24250-52600 MHz), FR3 (above 52600 MHz), and FR4 (between RF1 and FR2). In a multi-carrier system such as 5G, one of the carrier frequencies is referred to as the “primary carrier” or “anchor carrier” or “primary serving cell” or “PCell,” and the remaining carrier frequencies are referred to as “secondary carriers” or “secondary serving cells” or “SCells.” In carrier aggregation, the anchor carrier is the carrier operating on the primary frequency (e.g., FR1) utilized by the UE 104 / 182 and is the cell from which the UE 104 / 182 either performs an initial radio resource control (RRC) connection establishment procedure or initiates an RRC connection re-establishment procedure. The primary carrier carries all common and UE-specific control channels and is (but not always) a carrier in licensed frequencies. The secondary carrier is a carrier operating on a second frequency (e.g., FR2) that can be configured and used to provide additional radio resources after an RRC connection is established between the UE 104 and the anchor carrier. In some cases, the secondary carrier may be a carrier in unlicensed frequencies. The secondary carrier may contain only necessary signaling information and signals; for example, UE-specific information and signals may not be present in the secondary carrier, since both the primary uplink carrier and the downlink carrier are typically UE-specific. This means that different UEs 104 / 182 in a cell may have different downlink primary carriers. The same is true for the uplink primary carrier. The network can change the primary carrier of any UE 104 / 182 at any time. This is done, for example, to balance the load on different carriers.Since a "serving cell" (whether a PCell or an SCell) corresponds to the carrier frequency / component carrier with which some base station is communicating, terms such as "cell", "serving cell", "component carrier", "carrier frequency", etc. may be used interchangeably.

[0044]

[0051] For example, with continued reference to FIG. 1, one of the frequencies utilized by the macrocell base station 102 may be an anchor carrier (or “PCell”), and other frequencies utilized by the macrocell base station 102 and / or the mmW base station 180 may be secondary carriers (“SCells”). Simultaneous transmission and / or reception on multiple carriers allows the UE 104 / 182 to significantly increase its data transmission and / or reception rates. For example, two aggregated 20 MHz carriers in a multi-carrier system could theoretically double the data rate (i.e., 40 MHz) compared to the data rate achieved by a single 20 MHz carrier.

[0045]

[0052] The wireless communication system 100 may further include one or more UEs, such as a UE 190, that indirectly connect to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the example of FIG. 1, the UE 190 has a D2D P2P link 192 with one of the UEs 104 connected to one of the base stations 102 (e.g., via which the UE 190 may indirectly obtain cellular connectivity) and a D2D P2P link 194 with a WLAN STA 152 connected to a WLAN AP 150 (via which the UE 190 may indirectly obtain WLAN-based Internet connectivity). In one example, the D2D P2P links 192 and 194 may be supported using any well-known D2D RAT, such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth®, etc.

[0046]

[0053] The wireless communication system 100 may further include a UE 164 that may communicate with the macrocell base station 102 via communication link 120 and / or with the mmW base station 180 via mmW communication link 184. For example, the macrocell base station 102 may support a PCell and one or more SCells for the UE 164, and the mmW base station 180 may support one or more SCells for the UE 164.

[0047]

[0054] According to various aspects, FIG. 2A illustrates an exemplary wireless network structure 200. For example, the NGC 210 (also referred to as a “5GC”) may be viewed functionally as a control plane function (C-plane) 214 (e.g., UE registration, authentication, network access, gateway selection, etc.) and a user plane function (U-plane) 212 (e.g., UE gateway function, data network access, IP routing, etc.), which operate cooperatively to form a core network. A user plane interface (NG-U) 213 and a control plane interface (NG-C) 215 connect the gNB 222 to the NGC 210, specifically to the user plane function 212 and the control plane function 214, respectively. In an additional configuration, the eNB 224 may also be connected to the NGC 210 via the NG-C 215 to the control plane function 214 and the NG-U 213 to the user plane function 212. Additionally, the eNB 224 may communicate directly with the gNB 222 via a backhaul connection 223. In some configurations, the New RAN 220 may have only one or more gNBs 222, while other configurations include one or more of both eNBs 224 and gNBs 222. Either the gNBs 222 or the eNBs 224 may communicate with the UEs 204 (e.g., any of the UEs depicted in FIG. 1). Another optional aspect may include a location server 230, which may communicate with the NGC 210 to provide location assistance for the UEs 204. The location servers 230 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, each may correspond to a single server. The location server 230 may be configured to support one or more location services for UEs 204 that can connect to the location server 230 via the core network, the NGC 210, and / or the Internet (not shown).Furthermore, the location server 230 may be integrated into a component of the core network, or alternatively, may be external to the core network.

[0048]

[0055] According to various aspects, FIG. 2B illustrates another exemplary wireless network structure 250. For example, the NGC 260 (also referred to as “5GC”) may be viewed functionally as a control plane function provided by an Access and Mobility Management Function (AMF) / User Plane Function (UPF) 264 and a user plane function provided by a Session Management Function (SMF) 262, which operate cooperatively to form the core network (i.e., the NGC 260). A user plane interface 263 and a control plane interface 265 connect the eNB 224 to the NGC 260, specifically to the SMF 262 and the AMF / UPF 264, respectively. In an additional configuration, the gNB 222 may also be connected to the NGC 260 via the control plane interface 265 to the AMF / UPF 264 and the user plane interface 263 to the SMF 262. Additionally, eNB 224 may communicate directly with gNB 222 via backhaul connection 223, with or without gNB direct connectivity to NGC 260. In some configurations, New RAN 220 may have only one or more gNBs 222, while other configurations include one or more of both eNB 224 and gNB 222. Either gNB 222 or eNB 224 may communicate with UE 204 (e.g., any of the UEs depicted in FIG. 1). Base stations of New RAN 220 communicate with the AMF side of AMF / UPF 264 via the N2 interface and with the UPF side of AMF / UPF 264 via the N3 interface.

[0049]

[0056] The AMF functions include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between the UE 204 and the SMF 262, a transparent proxy service for routing SM messages, access authentication and authorization, transport for short message service (SMS) messages between the UE 204 and a short message service function (SMSF) (not shown), and security anchor functionality (SEAF). The AMF also interacts with an authentication server function (AUSF) (not shown) and the UE 204 and receives intermediate keys established as a result of the UE 204 authentication process. In the case of authentication based on a universal mobile telecommunications system (UMTS) subscriber identity module (USIM), the AMF retrieves security material from the AUSF. The AMF's functions also include security context management (SCM). The SCM receives keys from the SEAF that are used to derive access network-specific keys. The functionality of the AMF also includes location service management for barred services, transport for location service messages between the UE 204 and the Location Management Function (LMF) 270 and between the New RAN 220 and the LMF 270, Evolved Packet System (EPS) bearer identifier allocation for interworking with EPS, and UE 204 mobility event notification. In addition, the AMF also supports functionality for non-3GPP access networks.

[0050]

[0057] The functions of the UPF include acting as an anchor point for intra / inter-RAT mobility (when applicable), acting as an outer protocol data unit (PDU) session point for interconnection to a data network (not shown), providing packet routing and forwarding, packet inspection, user plane policy rule enforcement (e.g., gating, redirection, traffic steering), lawful interception (user plane collection), traffic usage reporting, Quality of Service (QoS) handling for the user plane (e.g., UL / DL rate enforcement, reflective QoS marking in DL), uplink traffic validation (service data flow (SDF) to QoS flow mapping), transport level packet marking in uplink and DL, downlink packet buffering and downlink data notification triggering, and sending and forwarding one or more "end markers" to the source RAN node.

[0051]

[0058] The functions of the SMF 262 include session management, UE Internet Protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering in the UPF to route traffic to the correct destination, policy enforcement and partial control of QoS, and downlink data notification. The interface through which the SMF 262 communicates with the AMF side of the AMF / UPF 264 is called the N11 interface.

[0052]

[0059] Another optional aspect may include an LMF 270, which may communicate with the NGC 260 to provide location assistance for the UE 204. The LMF 270 may be implemented as multiple separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternatively, may each correspond to a single server. The LMF 270 may be configured to support one or more location services for UEs 204 that may connect to the LMF 270 via a core network, the NGC 260, and / or the Internet (not shown).

[0053]

[0060] 3A, 3B, and 3C illustrate several example components (represented by corresponding blocks) that may be incorporated into a UE 302 (which may correspond to any of the UEs described herein), a base station 304 (which may correspond to any of the base stations described herein), and a network entity 306 (which may correspond to or embody any of the network functions described herein, including location server 230 and LMF 270) to support file transmission operations as taught herein. It will be understood that these components may be implemented in different types of devices (e.g., in an ASIC, in a system-on-chip (SoC), etc.) in different implementations. The illustrated components may also be incorporated into other devices in a communication system. For example, other devices in the system may include similar components to the described components to provide similar functionality. Also, a given device may include one or more of the components. For example, a device may include multiple transceiver components that enable the device to operate on multiple carriers and / or communicate via different technologies.

[0054]

[0061] The UE 302 and the base station 304 each include a wireless wide area network (WWAN) transceiver 310 and 350, respectively, configured to communicate over one or more wireless communications networks (not shown), such as an NR network, an LTE network, a GSM network, and / or others. The WWAN transceivers 310 and 350 may be connected to one or more antennas 316 and 356, respectively, for communicating with other network nodes, such as other UEs, access points, base stations (e.g., eNBs, gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.) over a targeted wireless communications medium (e.g., some set of time / frequency resources in a particular frequency spectrum). The WWAN transceivers 310 and 350 may be variously configured to transmit and encode signals 318 and 358, respectively (e.g., messages, indications, information, etc.), and conversely, to receive and decode signals 318 and 358, respectively (e.g., messages, indications, information, pilots, etc.), in accordance with the designated RAT. Specifically, the WWAN transceivers 310 and 350 include one or more transmitters 314 and 354, respectively, for transmitting and encoding signals 318 and 358, respectively, and include one or more receivers 312 and 352, respectively, for receiving and decoding signals 318 and 358, respectively.

[0055]

[0062] The UE 302 and base station 304 also, in at least some cases, include wireless local area network (WLAN) transceivers 320 and 360, respectively. The WLAN transceivers 320 and 360 may be connected to one or more antennas 326 and 366, respectively, for communicating with other network nodes, such as other UEs, access points, base stations, etc., via at least one designated RAT (e.g., WiFi, LTE-D, Bluetooth, etc.) over a target wireless communications medium. The WLAN transceivers 320 and 360 may be variously configured to transmit and encode signals 328 and 368, respectively (e.g., messages, indications, information, etc.), and conversely, to receive and decode signals 328 and 368, respectively (e.g., messages, indications, information, pilots, etc.), in accordance with the designated RAT. Specifically, WLAN transceivers 320 and 360 include one or more transmitters 324 and 364, respectively, for transmitting and encoding signals 328 and 368, respectively, and include one or more receivers 322 and 362, respectively, for receiving and decoding signals 328 and 368, respectively.

[0056]

[0063] The transceiver circuitry including at least one transmitter and at least one receiver may in some implementations comprise an integrated device (e.g., embodied as transmitter and receiver circuitry of a single communications device), in some implementations comprise separate transmitter and receiver devices, or in other implementations may be embodied in other manners. In one aspect, the transmitter may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array, that enable the respective device to perform transmit "beamforming" as described herein. Similarly, the receiver may include or be coupled to multiple antennas (e.g., antennas 316, 326, 356, 366), such as an antenna array, that enable the respective device to perform receive beamforming as described herein. In one aspect, the transmitter and receiver may share the same multiple antennas (e.g., antennas 316, 326, 356, 366), such that each device cannot both receive and transmit at the same time, but can only receive or transmit at a given time. The wireless communication devices of the UE 302 and / or base station 304 (e.g., one or both of the transceivers 310 and 320 and / or 350 and 360) may also include a network listen module (NLM), etc., to perform various measurements.

[0057]

[0064] The UE 302 and base station 304 also, in at least some cases, include satellite positioning system (SPS) receivers 330 and 370, respectively. The SPS receivers 330 and 370 may be connected to one or more antennas 336 and 376, respectively, for receiving SPS signals 338 and 378, respectively, such as Global Positioning System (GPS) signals, Global Navigation Satellite System (GLONASS) signals, Galileo signals, BeiDou signals, Navigation Satellite System of India (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. The SPS receivers 330 and 370 may comprise any suitable hardware and / or software for receiving and processing the SPS signals 338 and 378, respectively. The SPS receivers 330 and 370 appropriately request information and actions from other systems and perform the calculations necessary to determine the position of the UE 302 and base station 304, respectively, using measurements obtained by any suitable SPS algorithms.

[0058]

[0065] The base station 304 and the network entity 306 each include at least one network interface 380 and 390, respectively, for communicating with other network entities. For example, the network interfaces 380 and 390 (e.g., one or more network access ports) may be configured to communicate with one or more network entities via a wire-based or wireless backhaul connection. In some aspects, the network interfaces 380 and 390 may be implemented as transceivers configured to support wire-based or wireless signal communication. This communication may include, for example, sending and receiving messages, parameters, and / or other types of information.

[0059]

[0066] The UE 302, base station 304, and network entity 306 may also include other components that can be used in connection with the operations disclosed herein. The UE 302 includes processor circuitry implementing a processing system 332 for providing functionality, e.g., related to positioning operations and other processing functionality. The base station 304 includes a processing system 384 for providing functionality, e.g., related to positioning operations described herein and other processing functionality. The network entity 306 includes a processing system 394 for providing functionality, e.g., related to positioning operations described herein and other processing functionality. In an aspect, the processing systems 332, 384, and 394 may include, for example, one or more general-purpose processors, multi-core processors, ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGAs), or other programmable logic devices or processing circuits.

[0060]

[0067] The UE 302, the base station 304, and the network entity 306 include memory circuits that implement memory components 340, 386, and 396 (e.g., each including a memory device) respectively to maintain information (e.g., information indicative of reserved resources, thresholds, parameters, etc.). In some cases, the UE 302, the base station 304, and the network entity 306 may include positioning components 342, 388, and 398, respectively. The positioning components 342, 388, and 398 may be hardware circuits that are part of or coupled to the processing systems 332, 384, and 394, respectively, which, when executed, cause the UE 302, the base station 304, and the network entity 306 to perform the functionality described herein. In other aspects, the positioning components 342, 388, and 398 may be external to the processing systems 332, 384, and 394, respectively (e.g., part of a modem processing system, integrated with another processing system, etc.). Alternatively, the positioning components 342, 388, and 398 may be memory modules stored in the memory components 340, 386, and 396, respectively (as shown in FIGS. 3A-3C), which, when executed by the processing systems 332, 384, and 394 (or modem processing system, another processing system, etc.), cause the UE 302, the base station 304, and the network entity 306 to perform the functionality described herein.

[0061]

[0068] The UE 302 may include one or more sensors 344 coupled to the processing system 332 to provide motion and / or orientation information independent of motion data derived from signals received by the WWAN transceiver 310, the WLAN transceiver 320, and / or the SPS receiver 330. By way of example, the sensors 344 may include an accelerometer (e.g., a microelectrical mechanical systems (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric altimeter), and / or any other type of motion detection sensor. Moreover, the sensors 344 may include multiple different types of devices and may combine their outputs to provide motion information. For example, the sensors 344 may use a combination of a multi-axis accelerometer and an orientation sensor to provide the ability to calculate position in a 2D and / or 3D coordinate system.

[0062]

[0069] Additionally, the UE 302 includes a user interface 346 for providing indications (e.g., audible and / or visual indications) to a user and / or receiving user input (e.g., upon user actuation of a sensing device such as a keypad, touch screen, microphone, etc.). Although not shown, the base station 304 and the network entity 306 may also include user interfaces.

[0063]

[0070] Referring more particularly to the processing system 384, on the downlink, IP packets from the network entity 306 may be provided to the processing system 384. The processing system 384 may implement functionality for an RRC layer, a Packet Data Convergence Protocol (PDCP) layer, a Radio Link Control (RLC) layer, and a Medium Access Control (MAC) layer. The processing system 384 may provide RRC layer functionality related to broadcasting of system information (e.g., Master Information Block (MIB), System Information Block (SIB)), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-RAT mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality related to header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality related to transfer of upper layer packet data units (PDUs), error correction via automatic repeat request (ARQ), concatenation, segmentation, and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality related to mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

[0064]

[0071] The transmitter 354 and receiver 352 may implement Layer 1 functionality related to various signal processing functions. Layer 1 includes the physical (PHY) layer and may include error detection on transport channels, forward error correction (FEC) coding / decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation / demodulation of physical channels, and MIMO antenna processing. The transmitter 354 handles mapping to signal constellations based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-phase shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be separated into parallel streams. Each stream may then be mapped to orthogonal frequency division multiplexing (OFDM) subcarriers, multiplexed with reference signals (e.g., pilots) in the time and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to generate a physical channel carrying a time-domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to generate multiple spatial streams. Channel estimates from a channel estimator may be used to determine the coding and modulation scheme and for spatial processing. The channel estimates may be derived from a reference signal and / or channel condition feedback transmitted by the UE 302. Each spatial stream may then be provided to one or more different antennas 356. The transmitter 354 may modulate an RF carrier with each spatial stream for transmission.

[0065]

[0072] At the UE 302, the receiver 312 receives the signal via its respective antenna 316. The receiver 312 recovers the information modulated onto the RF carrier and provides the information to the processing system 332. The transmitter 314 and receiver 312 implement Layer 1 functionality related to various signal processing functions. The receiver 312 may perform spatial processing on the information to recover any spatial streams destined for the UE 302. If multiple spatial streams are destined for the UE 302, they may be combined by the receiver 312 into a single OFDM symbol stream. The receiver 312 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier, as well as the reference signal, are recovered and demodulated by determining the most likely signal constellation point transmitted by the base station 304. These soft decisions may be based on channel estimates calculated by a channel estimator. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted on the physical channel by base station 304. The data and control signals are then provided to processing system 332, which implements Layer 3 and Layer 2 functionality.

[0066]

[0073] In the UL, the processing system 332 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the core network. The processing system 332 is also responsible for error detection.

[0067]

[0074] Similar to the functionality described in connection with downlink transmissions by the base station 304, the processing system 332 provides RRC layer functionality related to system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality related to header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality related to transfer of upper layer PDUs, error correction via ARQ, concatenation, segmentation, and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality related to mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction via hybrid automatic repeat request (HARQ), priority handling, and logical channel prioritization.

[0068]

[0075] Channel estimates derived by a channel estimator from a reference signal or feedback transmitted by the base station 304 may be used by the transmitter 314 to select an appropriate coding and modulation scheme and to facilitate spatial processing. The spatial streams generated by the transmitter 314 may be provided to different antennas 316. The transmitter 314 may modulate an RF carrier with each spatial stream for transmission.

[0069]

[0076] The uplink transmissions are processed at the base station 304 in a manner similar to that described with reference to the receiver functions at the UE 302. The receiver 352 receives the signals via its respective antenna 356. The receiver 352 recovers the information modulated onto the RF carrier and provides the information to the processing system 384.

[0070]

[0077] In the UL, the processing system 384 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from the UE 302. The IP packets from the processing system 384 may be provided to the core network. The processing system 384 is also responsible for error detection.

[0071]

[0078] For convenience, the UE 302, the base station 304, and / or the network entity 306 are illustrated in Figures 3A-3C as including various components that may be configured in accordance with various examples described herein, although it will be understood that the illustrated blocks may have different functionality in different designs.

[0072]

[0079] The various components of the UE 302, the base station 304, and the network entity 306 may communicate with each other via data buses 334, 382, ​​and 392, respectively. The components of FIGS. 3A-3C may be implemented in various ways. In some implementations, the components of FIGS. 3A-3C may be implemented in one or more circuits, such as, for example, one or more processors and / or one or more ASICs (which may include one or more processors), where each circuit may use and / or incorporate at least one memory component for storing information or executable code used by the circuit to provide this functionality. For example, some or all of the functionality represented by blocks 310-346 may be implemented by the processor and memory components of the UE 302 (e.g., by executing appropriate code and / or by appropriate configuration of the processor components). Similarly, some or all of the functionality represented by blocks 350-388 may be implemented by the processor and memory components of the base station 304 (e.g., by executing appropriate code and / or by appropriate configuration of the processor components). Additionally, some or all of the functionality represented by blocks 390-398 may be implemented by the processor and memory components of the network entity 306 (e.g., by execution of appropriate code and / or appropriate configuration of the processor components). For simplicity, various operations, acts, and / or functions are described herein as being performed "by the UE," "by the base station," "by the positioning entity," etc. However, it will be understood that such operations, acts, and / or functions may actually be performed by specific components, such as the UE, base station, or positioning entity, or combinations of components, such as the processing systems 332, 384, 394, the transceivers 310, 320, 350, and 360, the memory components 340, 386, and 396, and the positioning components 342, 388, and 398.

[0073]

[0080] Various frame structures may be used to support downlink and uplink transmissions between network nodes (e.g., base stations and UEs). Figure 4A is a diagram 400 illustrating an example downlink frame structure according to an aspect of the present disclosure. Figure 4B is a diagram 430 illustrating example channels within a downlink frame structure according to an aspect of the present disclosure. Figure 4C is a diagram 450 illustrating an example uplink frame structure according to an aspect of the present disclosure. Figure 4D is a diagram 480 illustrating example channels within an uplink frame structure according to an aspect of the present disclosure. Other wireless communication technologies may have different frame structures and / or different channels.

[0074]

[0081] LTE, and in some cases NR, utilizes OFDM on the downlink and single-carrier frequency-division multiplexing (SC-FDM) on the uplink. However, unlike LTE, NR has the option to use OFDM on the uplink as well. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. Generally, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may depend on the system bandwidth. For example, the subcarrier spacing may be 15 kHz, and the minimum resource allocation (resource block) may be 12 subcarriers (or 180 kHz). Consequently, the nominal FFT size may be equal to 128, 256, 512, 1024, or 2048 for a system bandwidth of 1.25 megahertz (MHz), 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz, respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks), and there may be 1, 2, 4, 8, or 16 subbands for a system bandwidth of 1.25 MHz, 2.5 MHz, 5 MHz, 10 MHz, or 20 MHz, respectively.

[0075]

[0082] LTE supports a single numerology (subcarrier spacing, symbol length, etc.). In contrast, NR may support multiple numerologies (μ), e.g., subcarrier spacings of 15 kHz, 30 kHz, 60 kHz, 120 kHz, and 240 kHz or greater may be available. Table 1, provided below, lists some various parameters for different NR numerologies.

[0076] [Table 1]

[0077]

[0083] In the examples of Figures 4A to 4D, a 15 kHz numerology is used. Thus, in the time domain, a frame (e.g., 10 ms) is divided into 10 equally sized subframes of 1 ms each, with each subframe containing one time slot. In Figures 4A to 4D, time is represented horizontally (e.g., on the X-axis), with time increasing from left to right, while frequency is represented vertically (e.g., on the Y-axis), with frequency increasing (or decreasing) from bottom to top.

[0078]

[0084] A resource grid may be used to represent a time slot, and each time slot includes one or more time-parallel resource blocks (RBs) (also called physical RBs (PRBs)) in the frequency domain. The resource grid is further divided into multiple resource elements (REs). An RE may correspond to one symbol length in the time domain and one subcarrier in the frequency domain. In the numerology of FIGS. 4A to 4D, for a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols in the time domain, for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

[0079]

[0085] As illustrated in Figure 4A, some of the REs carry downlink reference (pilot) signals (DL-RS) for channel estimation at the UE. The DL-RS may include demodulation reference signals (DMRS), channel state information reference signals (CSI-RS), cell-specific reference signals (CRS), positioning reference signals (PRS), navigation reference signals (NRS), tracking reference signals (TRS), etc., and their exemplary locations are labeled "R" in Figure 4A.

[0080]

[0086] A set of resource elements used for the transmission of a PRS is called a "PRS resource" and may be identified by the parameter DL-PRS-ResourceId. A set of resource elements (REs) may span multiple PRBs in the frequency domain and N (e.g., one or more) consecutive symbols within a slot in the time domain. In a given OFDM symbol in the time domain, a PRS resource occupies consecutive PRBs in the frequency domain.

[0081]

[0087] A "PRS resource set" is a set of PRS resources used for transmitting PRS signals, where each PRS resource has a PRS resource ID (DL-PRS-ResourceId). Also, PRS resources within a PRS resource set are associated with the same TRP. A PRS resource set is identified by a PRS resource set ID (DL-PRS-ResourceSetId) and is associated with a specific TRP (identified by a cell ID). Also, PRS resources within a PRS resource set have the same periodicity, a common muting pattern configuration, and the same repetition factor across slots. The periodicity is 2 μThe repetition factor may have a length of t slots, where t is selected from the set {4, 5, 8, 10, 16, 20, 32, 40, 64, 80, 160, 320, 640, 1280, 2560, 5120, 10240}, and μ = 0, 1, 2, or 3 (numerology identifier). The repetition factor may have a length of n slots, where n is selected from the set {1, 2, 4, 6, 8, 16, 32}.

[0082]

[0088] A PRS resource ID in a PRS resource set is associated with a single beam (and / or beam ID) transmitted from a single TRP (although a TRP may transmit one or more beams). That is, each PRS resource in a PRS resource set may be transmitted on a different beam, and thus a "PRS resource," or simply a "resource," may also be referred to as a "beam." Note that this has no implication as to whether the TRP and the beam on which the PRS is transmitted are known to the UE.

[0083]

[0089] A "PRS instance" or "PRS occasion" is one instance of a periodically repeating time window (e.g., a group of one or more contiguous slots) during which a PRS is expected to be transmitted. A PRS occasion may also be referred to as a "PRS positioning occasion," "PRS positioning instance," "positioning occasion," "positioning instance," or simply an "occasion" or "instance."

[0084]

[0090] A "positioning frequency layer" is a collection of one or more PRS resource sets spanning one or more TRPs with the same subcarrier spacing (SCS) and cyclic prefix (CP) type (meaning that all numerologies supported for the physical downlink shared channel (PDSCH) are also supported for the PRS), the same Point A, the same value of downlink PRS bandwidth, the same starting PRB (and center frequency), and the same value of comb size. The Point A parameter takes the value of the parameter ARFCN-ValueNR, where "ARFCN" stands for "absolute radio-frequency channel number" and is an identifier / code that identifies the pair of physical radio channels used for transmission and reception. The downlink PRS bandwidth can have a granularity of four PRBs, with a minimum of 24 PRBs and a maximum of 272 PRBs. The comb size indicates the number of subcarriers in each symbol carrying the PRS. For example, a comb size of Comb-4 means that every fourth subcarrier of a given symbol carries a PRS. Currently, up to four frequency layers are defined, and up to two PRS resource sets can be configured per TRP per frequency layer.

[0085]

[0091] The downlink PRS resource ID is defined locally within the downlink PRS resource set, and the downlink PRS resource set ID is defined locally within the TRP. To uniquely identify DL-PRS resources across TRPs, an ID is defined that can be associated with multiple downlink PRS resource sets associated with a single TRP. This ID can be used together with the downlink PRS resource set ID and the downlink PRS resource ID to uniquely identify a single downlink PRS resource. This ID is referred to herein as the DL-PRS-TRP-ResourceSetId. Each TRP should be associated with only one DL-PRS-TRP-ResourceSetId. For example, the DL-PRS-TRP-ResourceSetId may be a cell ID (e.g., PCI, VCI), or a TRP ID, or another identifier different from the cell ID or TRP ID that is used for positioning purposes that participate in unique identification of PRS resources.

[0086]

[0092] It should be noted that the terms "positioning reference signal" and "PRS" may sometimes refer to specific reference signals used for positioning in an LTE system. However, as used herein, unless otherwise indicated, the terms "positioning reference signal" and "PRS" refer to any type of reference signal that may be used for positioning, such as, but not limited to, PRS signals in LTE, NRS, TRS, CRS, CSI-RS, DMRS, Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), etc.

[0087]

[0093] Figure 4B shows an example of various channels within a downlink slot of a radio frame. In NR, the channel bandwidth, or system bandwidth, is divided into multiple bandwidth parts (BWPs). A BWP is a contiguous set of PRBs selected from a contiguous subset of common RBs for a given numerology on a given carrier. Generally, up to four BWPs can be specified on the downlink and uplink. That is, a UE can be configured with up to four BWPs on the downlink and up to four BWPs on the uplink. Only one BWP (uplink or downlink) can be active at a given time, meaning that a UE can only receive or transmit on one BWP at a time. On the downlink, the bandwidth of each BWP should be equal to or greater than the bandwidth of an SSB, but it may or may not contain an SSB.

[0088]

[0094] Referring to FIG. 4B, the PSS is used by the UE to determine subframe / symbol timing and physical layer identifier. The SSS is used by the UE to determine the physical layer cell identity group number and radio frame timing. Based on the physical layer identity and the physical layer cell identity group number, the UE can determine the PCI. Based on the PCI, the UE can determine the location of the DL-RS mentioned above. The physical broadcast channel (PBCH), which carries the MIB, can be logically grouped with the PSS and SSS to form an SSB (also referred to as SS / PBCH). The MIB provides the number of RBs in the downlink system bandwidth and the system frame number (SFN). The PDSCH carries user data, broadcast system information not transmitted over the PBCH, such as system information blocks (SIBs), and paging messages.

[0089]

[0095] The physical downlink control channel (PDCCH) carries downlink control information (DCI) in one or more control channel elements (CCEs), each of which contains one or more RE group (REG) bundles (which may span multiple symbols in the time domain). Each REG bundle contains one or more REGs, and each REG corresponds to 12 resource elements (one resource block) in the frequency domain and one OFDM symbol in the time domain. The set of physical resources used to carry the PDCCH / DCI is called a control resource set (CORESET) in NR. In NR, the PDCCH is limited to a single CORESET and transmitted using its own DMRS. This enables UE-specific beamforming for the PDCCH.

[0090]

[0096] In the example of Figure 4B, there is one CORESET per BWP, and the CORESET spans three symbols in the time domain. Unlike LTE control channels, which occupy the entire system bandwidth, in NR, the PDCCH channel is localized to a specific region (i.e., the CORESET) in the frequency domain. Therefore, the frequency components of the PDCCH shown in Figure 4B are illustrated as less than a single BWP in the frequency domain. Note that the illustrated CORESETs are contiguous in the frequency domain, but this need not be the case. Also, the CORESET may span less than three symbols in the time domain.

[0091]

[0097] The DCI in the PDCCH carries information about uplink resource allocations (persistent and non-persistent) and descriptions of downlink data to be transmitted to the UE. Multiple (e.g., up to eight) DCIs can be configured in the PDCCH, and these DCIs can have one of multiple formats. For example, there are different DCI formats for uplink scheduling, for non-MIMO downlink scheduling, for MIMO downlink scheduling, and for uplink power control. The PDCCH can be carried by 1, 2, 4, 8, or 16 CCEs to accommodate different DCI payload sizes or coding rates.

[0092]

[0098] As illustrated in FIG. 4C , some of the REs carry DMRSs for channel estimation at the base station. The UE may additionally transmit a sounding reference signal (SRS), for example, in the last symbol of a subframe. The SRS may have a comb structure, and the UE may transmit the SRS on one of the combs. The comb structure (also referred to as "comb size") indicates the number of subcarriers in each symbol period that carry a reference signal (here, the SRS). For example, a comb size of comb-4 means that every fourth subcarrier of a given symbol carries a reference signal, whereas a comb size of comb-2 means that every second subcarrier of a given symbol carries a reference signal. In the example of FIG. 4C , both of the illustrated SRSs (e.g., SRS#0 and SRS#1) are comb-2. The SRSs may be used by the base station to obtain channel state information (CSI) for each UE. CSI describes how the RF signal propagates from the UE to the base station, representing the combined effects of scattering, fading, and power attenuation over distance. Systems use SRS for resource scheduling, link adaptation, massive MIMO, beam management, etc.

[0093]

[0099] FIG. 4D illustrates an example of various channels within an uplink subframe of a frame according to an aspect of the present disclosure. A random access channel (RACH), also referred to as a physical random access channel (PRACH), may be within one or more subframes within a frame based on a PRACH configuration. The PRACH may include six consecutive RB pairs within a subframe. The PRACH enables a UE to perform initial system access and achieve uplink synchronization. A physical uplink control channel (PUCCH) may be located at the edge of the uplink system bandwidth. The PUCCH carries uplink control information (UCI), such as scheduling requests, CSI reports, channel quality indicators (CQIs), precoding matrix indicators (PMIs), rank indicators (RIs), and HARQ ACK / NACK feedback. A physical uplink shared channel (PUSCH) carries data and may additionally be used to carry buffer status reports (BSRs), power headroom reports (PHRs), and / or UCI.

[0094]

[0100] A set of resource elements used for transmitting an SRS is called an "SRS resource" and may be identified by a parameter SRS-ResourceId. The set of resource elements may span multiple PRBs in the frequency domain or N (e.g., one or more) consecutive symbols within a slot in the time domain. In a given OFDM symbol, the SRS resources occupy consecutive PRBs. An "SRS resource set" is a set of SRS resources used for transmitting an SRS signal and is identified by an SRS resource set ID (SRS-ResourceSetId).

[0095]

[0101] Generally, a UE transmits an SRS to enable a receiving base station (either a serving base station or a neighboring base station) to measure the channel quality between the UE and the base station. However, the SRS can also be used as an uplink positioning reference signal for uplink positioning procedures, such as uplink time-difference of arrival (UTDOA), multi-round-trip-time (RTT), uplink angle-of-arrival (UL-AoA), etc.

[0096]

[0102] 5A illustrates an exemplary four-step random access procedure 500A according to an aspect of the present disclosure. The four-step random access procedure 500A is performed between a UE 504 and a base station 502, each of which may correspond to any of the UEs and base stations described herein.

[0097]

[0103] There are various situations in which a UE may perform the four-step random access procedure 500A (also referred to as a "RACH procedure," "PRACH procedure," etc.) For example, the UE may perform the four-step random access procedure 500A when gaining initial network access after coming out of an RRC idle state, when performing an RRC connection re-establishment procedure, during a handover period when downlink or uplink data arrives and the UE is in an RRC connected state but its uplink synchronization status is "not synchronized," when transitioning from an RRC inactive state, when establishing time alignment for adding an SCell, when requesting other synchronization information, or when performing beam failure recovery.

[0098]

[0104] Before performing the four-step random access procedure 500A, the UE 504 first reads one or more SSBs broadcast by the base station 502 on which the UE 504 is to perform the four-step random access procedure 500A. In NR, each beam transmitted by a base station (e.g., base station 502) is associated with a different SSB, and the UE (e.g., UE 504) selects a specific beam to use to communicate with the base station 502. Based on the SSB of the selected beam, the UE 504 can then read SIB type 1 (SIB1), which carries cell access-related information and provides the UE 504 with scheduling of other system information blocks to be transmitted on the selected beam.

[0099]

[0105] When a UE sends the very first message of the four-step random access procedure 500A to the base station 502, the UE sends a specific pattern called a preamble (also called a RACH preamble, PRACH preamble, preamble sequence, or sequence). The RACH preamble distinguishes requests from different UEs 504. However, if two UEs 504 use the same RACH preamble simultaneously, a collision is possible. There are a total of 64 such patterns available to the UE 504, and in the case of contention-based random access, the UE 504 randomly chooses one of them. However, in the case of non-contention random access, the network instructs the UE 504 as to which one to use.

[0100]

[0106] At 510, the UE 504 selects one of 64 RACH preambles to send to the base station 502 as a RACH request. This message is called “Message 1” or “Msg1” in the four-step RACH procedure. Based on synchronization information (i.e., SIB1) from the base station 502, the UE 504 selects a RACH preamble and sends it in the RACH occasion (RO) corresponding to the selected SSB / beam. More specifically, in order for the base station 502 to determine which beam the UE 504 has selected, a specific mapping is defined between the SSBs and ROs (which occur every 10 ms, 20 ms, 40 ms, 80 ms, or 160 ms). By detecting in which RO the UE 504 sent the preamble, the base station 502 can determine which SSB / beam the UE 504 has selected.

[0101]

[0107] Note that the RO is a time-frequency transmission opportunity for transmitting a RACH preamble, and the RACH preamble index (i.e., a value from 0 to 63 for 64 possible preambles) allows the UE 504 to generate the type of RACH preamble expected at the base station 502. The RO and RACH preamble index may be configured for the UE 504 by the base station 502 in the SIB. A RACH resource is the RO on which one RACH preamble index is transmitted. Therefore, the terms "RO" (or "RACH occasion") and "RACH resource" may be used interchangeably, depending on the context.

[0102]

[0108] Due to the reciprocity, the UE 504 may use the uplink transmit beam corresponding to the best downlink receive beam determined during the synchronization period (i.e., the best receive beam for receiving the selected downlink beam from the base station 502). That is, the UE 504 uses the parameters of the downlink receive beam used to receive the beam from the base station 502 to determine the parameters of the uplink transmit beam. If the reciprocity is available at the base station 502, the UE 504 may transmit a preamble on one beam. Otherwise, the UE 504 repeats transmitting the same preamble on all of its uplink transmit beams.

[0103]

[0109] The UE 504 needs to provide its identity to the network (via the base station 502) so that the network can address it in the next step. This identity is called the random access radio network temporary identity (RA-RNTI) and is determined from the time slot in which the RACH preamble is sent. If the UE 504 does not receive a response from the base station 502 within a certain period of time, the UE 504 increases its transmit power by a fixed step and sends the RACH preamble / Msg1 again.

[0104]

[0110] At 520, the base station 502 sends a random access response (RAR), referred to as "Message 2" or "Msg2" in the four-step RACH procedure, to the UE 504 on the selected beam. The RAR is sent on the PDSCH and addressed to the RA-RNTI, which is calculated from the time slot in which the preamble was sent (i.e., the RO). The RAR carries the following information: a Cell Radio Network Temporary Identifier (C-RNTI), a Timing Advance (TA) value, and an uplink grant resource. The base station 502 assigns the C-RNTI to the UE 504 to enable further communication with the UE 504. The TA value specifies how much the UE 504 should change its timing to compensate for the round-trip delay between the UE 504 and the base station 502. The uplink grant resource indicates the initial resource the UE 504 can use on the PUSCH. After this step, the UE 504 and the base station 502 establish a coarse beam alignment that can be utilized in subsequent steps.

[0105]

[0111] At 530, using the allocated PUSCH, the UE 504 sends an RRC connection request message, referred to as "Message 3" or "Msg3," to the base station 502. The UE 504 sends Msg3 on resources scheduled by the base station 502, so the base station 502 knows where to detect Msg3 and which uplink receive beam to use. Note that the Msg3 PUSCH can be sent on the same or a different uplink transmit beam as Msg1.

[0106]

[0112] The UE 504 identifies itself in Msg3 by the C-RNTI assigned in the previous step. The message contains the identity of the UE 504 and a connection establishment cause. The identity of the UE 504 is either a Temporary Mobile Subscriber Identity (TMSI) or a random value. If the UE 504 has previously connected to the same network, the TMSI is used. The UE 504 is identified in the core network by the TMSI. If the UE 504 is connecting to the network for the first time, a random value is used. The reason for a random value or TMSI is that a C-RNTI may have been assigned to more than one UE in the previous step due to multiple requests arriving at the same time. The connection establishment cause indicates why the UE 504 needs to connect to the network and will be explained further below.

[0107]

[0113] At 540, if Msg3 is successfully received, base station 502 responds with a contention resolution message, referred to as "Message 4" or "Msg4." This message is addressed to the TMSI (from Msg3) or a random value, but contains a new C-RNTI to be used for further communications. Specifically, base station 502 sends Msg4 on the PDSCH using the downlink transmit beam determined in the previous step.

[0108]

[0114] The four-step random access procedure 500A described above is a contention-based random access procedure. In contention-based random access, any UE 504 connecting to the same cell or TRP sends the same request, in which case there is a possibility of collision between requests from various UEs 504. In non-contention random access, the network can instruct the UE 504 to use some unique identification to prevent its request from colliding with requests from other UEs. The non-contention random access procedure can be performed when the UE 504 is in RRC connected mode before the random access procedure, such as in the case of handover.

[0109]

[0115] 5B illustrates an exemplary two-step random access procedure 500B performed between a UE 504 and a base station 502, according to an aspect of the present disclosure.

[0110]

[0116] At 550, the UE 504 transmits RACH message A (“MsgA”) to the base station 502. In the two-step random access procedure 500B, Msg1 and Msg3 described above with reference to FIG. 5A are collapsed (e.g., combined) into MsgA and sent to the base station 502. MsgA thus includes a RACH preamble and a PUSCH, similar to the Msg3 PUSCH in the four-step RACH procedure. The RACH preamble may be selected from 64 possible preambles, as described above with reference to FIG. 5A, and may be used as a reference signal for demodulation of the data transmitted in MsgA. At 560, the UE 504 receives RACH message B (“MsgB”) from the base station 502. MsgB may be a combination of Msg2 and Msg4 described above with reference to FIG. 5A.

[0111]

[0117] The combination of Msg1 and Msg3 into one MsgA and the combination of Msg2 and Msg4 into one MsgB allows the UE 504 to reduce the RACH procedure setup time to support the low latency requirements of 5G NR. The UE 504 may be configured to support the two-step random access procedure 500B, but if the UE 504 cannot use the two-step random access procedure 500B due to some constraints (e.g., high transmit power requirements, etc.), the UE 504 may still support the four-step random access procedure 500A as a fallback. Thus, a UE in 5G NR may be configured to support both the two-step random access procedure and the four-step random access procedure and may determine which random access procedure to configure based on RACH configuration information received from the base station.

[0112]

[0118] After the random access procedure 500A or 500B, the UE 504 is in an RRC connected state. The RRC protocol is used on the air interface between the UE 504 and the base station 502.

[0113]

[0119] Due to UE mobility / movement, beam reconfiguration at the base station, and / or other factors, a downlink beam (e.g., comprising a downlink control link) that could have been a suitable active beam may not be detected at the UE, or its signal quality (e.g., RSRP, RSRQ, SINR, etc.) may drop below a threshold, causing the UE to consider it a beam / link failure. A beam recovery procedure may be employed to recover from such beam failure. Beam failure may refer, for example, to an inability to detect a strong (e.g., having signal power greater than a threshold) active beam, which in some aspects may correspond to a control channel communicating control information from the network. In particular aspects, to facilitate beam failure detection, the UE may be pre-configured with a beam identifier (ID), monitoring period, signal strength threshold, etc., of a first set of beams to be monitored (referred to as “set_q0”). Recovery may be triggered when the signal strength (e.g., RSRP, RSRQ, SINR, etc.) associated with one or more monitored beams (as detected by the UE) drops below a threshold. The recovery process may include the UE identifying a new beam from, for example, a second set of possible beams (corresponding to beam IDs that may be included in the second set, referred to as "set_q1") and performing a random access procedure (e.g., as illustrated in FIGS. 5A and 5B) using preconfigured time and frequency resources corresponding to the new preferred beam. The beam IDs corresponding to beams in the second set of beams (set_q1) may be preconfigured in the UE for use for beam failure recovery purposes. For example, the UE may monitor downlink beams (based on the beam IDs and resources identified in the second set), perform measurements, and determine (e.g., based on the measurements) which beam of all received and measured beams may be best for reception at the UE from the UE's perspective.

[0114]

[0120] If beam correspondence is inferred (i.e., the direction of the best receive beam used by the UE is also considered the best direction for the transmit beam used by the UE), the UE may infer the same beam configuration for both receive and transmit. That is, based on monitoring downlink reference signals from the base station, the UE can determine the weight of its preferred uplink transmit beam, which will be the same for the downlink receive beam used for receiving downlink reference signals.

[0115]

[0121] If beam correspondence is not inferred (e.g., determined to be inappropriate in a given scenario or for other reasons), the UE may not derive an uplink transmit beam from the downlink receive beam. Instead, separate signaling is required to select uplink transmit beam weights and downlink receive beam weights and for UL-to-DL beam pairing. The UE may perform a RACH procedure (e.g., using preconfigured time and frequency resources indicated in the second set of beams, i.e., set_q1) to identify the uplink transmit beam. Performing the RACH procedure using the preconfigured time and frequency resources may comprise, for example, transmitting a RACH preamble on one or more uplink transmit beams (corresponding to beam IDs in the second set of beams, i.e., set_q1) on allocated RACH resources corresponding to one or more beams. Based on the RACH procedure, the UE may determine and confirm to the base station which uplink direction may be the best beam direction for the uplink channel (e.g., PUCCH). In this manner, both the uplink transmit beam and the downlink receive beam can be re-established and beam recovery can be completed.

[0116]

[0122] 6 is a diagram 600 of an example RACH-based SpCell beam failure recovery procedure according to aspects of the present disclosure. In the example of FIG. 6, for simplicity, the PCell and SCell are shown as being associated with a single base station (e.g., the hardware / circuit configurations for implementing the PCell and SCell may be co-located in the same base station). However, in some other configurations, the PCell and SCell may be associated with different base stations that may be synchronized.

[0117]

[0123] In the example of FIG. 6, a PCell or a primary (i.e., actively in use) SCell (collectively referred to as an “SpCell”) is supported by a base station 602 (illustrated as a “gNB” and which may correspond to any of the base stations described herein). A UE 604 (which may correspond to any of the UEs described herein) monitors the received signal strength (e.g., RSRP, RSRQ, SINR, etc.) of periodic reference signals (e.g., PRS) transmitted by the base station 602 on a first set (“set_q0”) 606 of downlink transmission beams of the SpCell. The first set of downlink transmission beams 606 is referred to as a “failure detection resource set” because the base station 602 sends beam IDs of beams in the first set of downlink transmission beams 606 to the UE 604 to enable the UE 604 to monitor these beams to determine whether a downlink control link (i.e., a control channel communicating control information from the network) between the base station 602 and the UE 604 is active. 6, the first set of downlink transmit beams 606 includes two beams, but there may be only one beam or more than two beams in the first set of downlink transmit beams 606.

[0118]

[0124] At 610, the UE 604 does not detect a periodic reference signal transmitted on at least one of the beams in the first set of downlink transmit beams 606 and / or detects that a quality metric (e.g., RSRP, RSRQ, SINR, etc.) associated with the reference signal has fallen below a signal quality threshold (represented in FIG. 6 as “Qout”). The Qout threshold may be configured by the base station 602. More specifically, Layer 1 (“L1” in FIG. 6) functionality of the UE 604 (e.g., implemented in the WWAN transceiver 310) detects that the measured quality metric of the periodic reference signal is below the Qout threshold and sends an out-of-sync (OOS) indication to the processing system 332 (which implements the Layer 2 and Layer 3 functionality of the UE 604). In response to receiving the OOS indication, the processing system 332 of the UE 604 starts a beam failure detection (BFD) timer and initializes a beam failure indicator (BFI) counter to “1.”

[0119]

[0125] At 615, the UE 604 again fails to detect a periodic reference signal transmitted on at least one of the beams in the first set of downlink transmit beams 606 and / or again detects that a quality metric associated with the reference signal has fallen below the Qout threshold. Again, more specifically, the Layer 1 functionality of the UE 604 detects that the measured quality metric of the periodic reference signal is below the Qout threshold and sends another OOS indication to the processing system 332. The processing system 332 increments the BFI count to “2.” Because the BFI count reached the maximum count (“MaxCnt”) threshold (which is “2” in the example of FIG. 6 but may be another value) while the BFD timer was running, the UE 604 determines that there has been a beam failure of at least one beam (e.g., a downlink control beam) in the first set of downlink transmit beams 606. Because there is a failure of the downlink control beam (corresponding to the downlink control channel that communicates control information from the network), the UE 604 infers that there is also a failure of the corresponding uplink control beam (corresponding to the uplink control channel that communicates control information to the network). Therefore, the UE 604 needs to identify a new downlink control beam and re-establish the uplink control beam. The UE 604 also resets the BFD timer.

[0120]

[0126] Thus, at 620, in response to the beam failure detection at 615, the UE 604 initiates a beam failure recovery procedure. More specifically, the processing system 332 of the UE 604 requests that the Layer 1 functionality of the UE 604 identify at least one beam in a second set of downlink transmit beams (“set_q1”) 608 that carries a periodic reference signal having a received signal strength greater than a signal quality threshold (denoted as “Qin”). The second set of downlink transmit beams 608 is referred to as a “candidate beam reference signal list.” The UE 604 may receive both the beam ID(s) of the beams in the second set of downlink transmit beams 608 and the Qin threshold from the base station 602. In the example of FIG. 6, the second set of downlink transmit beams 608 includes four beams, one of which (hatched) carries a periodic reference signal having a received signal strength greater than the Qin threshold. However, it will be understood that there may be more or fewer than four beams in the second set of downlink transmit beams 608, and there may be more than one beam that satisfies the Qin threshold. The WWAN transceiver 310 (implementing Layer 1 functionality) reports the identified candidate beams to the processing system 332. As a result, the identified candidate beams can be used as new downlink control beams, although not necessarily immediately.

[0121]

[0127] At 625, to re-establish the uplink control beam, the UE 604 performs a RACH procedure (e.g., as illustrated in FIGS. 5A and 5B ) on one or more (one in the example of FIG. 6 ) candidate downlink transmission beams identified at 620. More specifically, the processing system 332 instructs the WWAN transceiver 310 to send a RACH preamble (which may be pre-stored or provided to the UE 604 by the base station 602) to the base station 602. The WWAN transceiver 310 sends the RACH preamble (also referred to as message 1 (“Msg1”)) on one or more candidate uplink transmission beams corresponding to the one or more candidate downlink transmission beams identified at 620 on pre-configured RACH resources for the one or more candidate uplink transmission beams. The pre-configured RACH resources may correspond to an SpCell (e.g., in the mmW band). Although not illustrated in FIG. 6, at 625, the UE 604 also starts a beam failure recovery (BFR) timer that defines a contention-free random access (CFRA) response window.

[0122]

[0128] The one or more candidate downlink transmit beams identified in 620 may include a beam that is different from the downlink transmit beam associated with the beam obstruction. As used herein, a “beam” is defined by the beam weights associated with the antenna array of the UE 604. Thus, in some aspects, the weights applied to each antenna in the array to construct a transmitted or received beam define the beam, whether used for uplink transmission by the UE 604 or for downlink reception by the UE 604. As such, one or more candidate uplink transmit beams through which a RACH preamble is sent may have a different weight than the downlink transmit beam associated with the beam obstruction, even if such candidate uplink transmit beam is in a generally similar direction as the downlink transmit beam indicated as obstructing.

[0123]

[0129] At 630, the base station 602 transmits a RACH response (referred to as an "Msg1 response") to the UE 604 via a PDCCH associated with the SpCell and with the C-RNTI. For example, the response may comprise cyclic redundancy check (CRC) bits scrambled by the C-RNTI. After the WWAN transceiver 310 of the UE 604 processes the response received from the base station 602 via the SpCell PDCCH with the C-RNTI and determines that the received PDCCH is addressed to the C-RNTI, the processing system 332 determines that the beam failure recovery procedure is complete and stops the BFR timer started at 625. In one aspect, the C-RNTI may be mapped to the beam direction determined by the base station 602 to be the best direction for an uplink channel (e.g., PUCCH) for the UE 604. Thus, upon receiving a response with the C-RNTI from the base station 602, the UE 604 may be able to determine an optimal uplink transmit beam that is best suited for the uplink channel.

[0124]

[0130] The operations at 630 are part of a first scenario in which the UE 604 successfully recovers from the beam failure detected at 615. However, such recovery does not always occur, or at least does not occur before the BFR timer started at 625 times out. If the BFR timer expires before the beam failure recovery procedure is successfully completed, at 635 the UE 604 determines that a radio link failure (RLF) has occurred.

[0125]

[0131] FIG. 7 illustrates an exemplary wireless communications system 700 according to various aspects of the present disclosure. In the example of FIG. 7, a UE 704, which may correspond to any of the UEs described herein, is attempting to calculate an estimate of its location or assist another entity (e.g., a base station or core network component, another UE, a location server, a third-party application, etc.) in calculating an estimate of its location. The UE 704 may communicate wirelessly with multiple base stations 702-1, 702-2, and 702-3 (collectively, base stations 702), which may correspond to any combination of base stations described herein, using RF signals and standardized protocols for modulating the RF signals and exchanging information packets. By extracting different types of information from the exchanged RF signals and utilizing the layout of the wireless communications system 700 (e.g., base station locations, geometry, etc.), the UE 704 may determine, or assist in determining, its location in a predefined reference coordinate system. In one aspect, the UE 704 may identify its location using a two-dimensional (2D) coordinate system. However, aspects disclosed herein are not so limited and may also be applicable to determining position using a three-dimensional (3D) coordinate system if additional dimensions are desired. Also, while Figure 7 illustrates one UE 704 and three base stations 702, it will be understood that there may be more UEs 704 and more or fewer base stations 702.

[0126]

[0132] To support location estimates, base stations 702 may be configured to broadcast positioning reference signals (e.g., PRS, NRS, TRS, CRS, etc.) to UEs 704 in their coverage areas to enable the UEs 704 to measure characteristics of such reference signals. For example, the OTDOA positioning method, also called the Time Difference of Arrival (TDOA) positioning method, is a multilateration method in which the UE 704 measures time differences, known as RSTD, between specific reference signals (e.g., PRS, NRS, TRS, CRS, etc.) transmitted by different pairs of network nodes (e.g., base stations 702, antennas of base stations 702, etc.), and reports these time differences to a location server such as location server 230 or LMF 270 or calculates a location estimate itself from these time differences.

[0127]

[0133] Generally, RSTD is measured between a reference network node (e.g., base station 702-1 in the example of FIG. 7) and one or more neighboring network nodes (e.g., base stations 702-2 and 702-3 in the example of FIG. 7). The reference network node remains the same for all RSTD measured by the UE 704 for any single positioning use of OTDOA and typically corresponds to the serving cell for the UE 704 or another nearby cell that has good signal strength at the UE 704. In one aspect, where the measured network node is a cell supported by a base station, the neighboring network node will typically be a cell supported by a different base station than the base station for the reference cell and may have good or poor signal strength at the UE 704. Location calculations can be based on the measured time difference (e.g., RSTD) as well as knowledge of the network node's locations and relative transmission timing (e.g., regarding whether the network nodes are precisely synchronized or whether each network node transmits with some known time difference relative to the other network nodes).

[0128]

[0134] To assist in positioning operations, a location server (e.g., location server 230, LMF 270) may provide OTDOA assistance data to the UE 704 for a reference network node (e.g., base station 702-1 in the example of FIG. 7) and neighboring network nodes relative to the reference network node (e.g., base stations 702-2 and 702-3 in the example of FIG. 7). For example, the assistance data may provide a center channel frequency for each network node, various reference signal configuration parameters (e.g., number of consecutive positioning subframes, periodicity of the positioning subframes, muting sequence, frequency hopping sequence, reference signal identifier (ID), reference signal bandwidth), network node global ID, and / or other cell-related parameters applicable to OTDOA. The OTDOA assistance data may indicate the serving cell for the UE 704 as the reference network node.

[0129]

[0135] In some cases, the OTDOA assistance data may also include an "expected RSTD" parameter, which provides the UE 704 with information regarding the RSTD value the UE 704 is expected to measure at its current location between the reference network node and each neighboring network node, along with the uncertainty of the expected RSTD parameter. The expected RSTD, along with the associated uncertainty, may define a search window for the UE 704 over which the UE 704 is expected to measure the RSTD value. The OTDOA assistance information may also include a reference signal configuration information parameter, which enables the UE 704 to determine when reference signal positioning occasions occur on signals received from various neighboring network nodes relative to the reference signal positioning occasion for the reference network node, and to determine the reference signal sequences transmitted from various network nodes for measuring signal time of arrival (ToA) or RSTD.

[0130]

[0136] In one aspect, a location server (e.g., location server 230, LMF 270) may send assistance data to the UE 704, but alternatively, the assistance data may originate directly from the network node (e.g., base station 702) itself (e.g., in periodically broadcast overhead messages, etc.). Alternatively, the UE 704 can detect neighboring network nodes itself without using assistance data.

[0131]

[0137] The UE 704 may measure and (optionally) report the RSTD between reference signals received from pairs of network nodes (e.g., based in part on assistance data, if provided). Using the RSTD measurements, the known absolute or relative transmit timing of each network node, and the known positions of the transmit antennas for the reference and neighboring network nodes, the network (e.g., location server 230 / LMF 270, base station 702) or the UE 704 may estimate the location of the UE 704. More specifically, the RSTD for a neighboring network node "k" relative to a reference network node "Ref" may be calculated as follows: k -ToA Ref), where the ToA values ​​may be measured modulo one subframe duration (1 ms) to remove the effects of measuring different subframes at different times. In the example of FIG. 7, the measured time differences between the reference cell of base station 702-1 and the cells of neighboring base stations 702-2 and 702-3 are represented as t2-t1 and t3-t1, where t1, t2, and t3 represent the ToAs of the reference signals from the transmit antenna(s) of base stations 702-1, 702-2, and 702-3, respectively. The UE 704 may then convert the ToA measurements for different network nodes into RSTD measurements and (optionally) send them to the location server 230 / LMF 270. The location of the UE 704 may be determined (either by the UE 704 or the location server 230 / LMF 270) using (i) RSTD measurements, (ii) the absolute or relative transmission timing of each network node, (iii) known locations of the physical transmitting antennas of the reference network node and neighboring network nodes, and / or (iv) directional reference signal characteristics such as the direction of transmission.

[0132]

[0138] 7, when the UE 704 uses OTDOA measurement time differences to obtain a location estimate, necessary additional data (e.g., network node locations and relative transmission timing) may be provided to the UE 704 by a location server (e.g., location server 230, LMF 270). In some implementations, a location estimate for the UE 704 may be obtained (e.g., by the UE 704 itself or by location server 230 / LMF 270) from the OTDOA measurement time differences and from other measurements made by the UE 704 (e.g., measurements of signal timing from GPS or other Global Navigation Satellite System (GNSS) satellites). In these implementations, known as hybrid positioning, the OTDOA measurements may contribute toward obtaining a location estimate for the UE 704 but may not completely determine the location estimate.

[0133]

[0139] UTDOA is a positioning method similar to OTDOA, but is based on uplink reference signals (e.g., SRS, uplink PRS) transmitted by the UE (e.g., UE 704). Additionally, transmit and / or receive beamforming at the base station 702 and / or UE 704 can enable wide bandwidth at the cell edge to increase accuracy. Beam refinement may also leverage channel reciprocity procedures in 5G NR.

[0134]

[0140] Another uplink positioning procedure is UL-AoA. In UL-AoA positioning, a base station uses the angle and other characteristics (e.g., signal strength) of the uplink receive beam from which the base station receives a reference signal (e.g., SRS) to estimate the location of the UE. The base station, or other positioning entity, may also use the signal propagation time between the base station and the UE to determine the distance between the base station and the UE to further refine the UE's location estimate. The signal propagation time, or time of flight, may be determined using multiple RTTs.

[0135]

[0141] The term “position estimate” is used herein to refer to an estimate of a location for a UE, which may be geographic (e.g., may comprise latitude, longitude, and possibly altitude) or urban (e.g., may comprise a street address, a building designation, or a precise point or area within or near a building or street address, e.g., a particular entrance to a building, a particular room or suite within a building, or a landmark such as a town square). A location estimate may also be referred to as a “location,” “position,” “fix,” “position fix,” “location fix,” “location estimate,” “fix estimate,” or by some other terminology. Means of obtaining a location estimate may be collectively referred to as “positioning,” “locating,” or “position fix.” A particular solution for obtaining a location estimate may be referred to as a “position solution.” A particular method of obtaining a position estimate as part of a position solution may be referred to as a “position method” or a “positioning method.”

[0136]

[0142] As mentioned above, "RF signals" carry information through space between a transmitter and a receiver. RF signals typically experience some path loss, or path attenuation, which is a reduction (attenuation) in the power density of an electromagnetic wave (RF signal) as it propagates through space. Path loss can be due to many effects, such as free space loss, refraction, diffraction, reflection, open medium coupling loss, and absorption. Path loss is also affected by terrain contours, the environment (e.g., urban or rural, vegetation and foliage, etc.), the propagation medium (e.g., dry or moist air), the distance between the transmitter and receiver, and the height and location of the transmitting antenna.

[0137]

[0143] A transmitter (e.g., a base station or a UE) may transmit a single RF signal or multiple RF signals to a receiver (e.g., a UE or a base station). However, the receiver may receive multiple RF signals corresponding to each transmitted RF signal due to the propagation characteristics of the RF signal through a multipath channel. The same transmitted RF signal on different paths between the transmitter and the receiver may be referred to as a "multipath" RF signal. The multipath RF signals combine at the receiver, resulting in a received signal that may vary significantly depending on the wave and bandwidth intensity distribution and relative propagation times of the transmitted signals.

[0138]

[0144] As mentioned above, during a UTDOA positioning procedure (and other uplink or uplink-plus-downlink positioning procedures, such as multi-RTT and UL-AoA), the UE transmits uplink reference signals, such as SRS and uplink PRS, that need to be transmitted with a transmit power high enough so that they can be measured by neighboring cells. Because neighboring cells may be farther away from the UE than the serving cell, there may be more path loss between the UE and the neighboring cells than between the UE and the serving cell. Therefore, these uplink reference signals may need to be transmitted with a higher transmit power than the uplink signals transmitted to the serving cell.

[0139]

[0145] Several options have been identified for setting the transmit power of uplink reference signals transmitted for positioning purposes (e.g., UTDOA). As a first option, the transmit power of such uplink reference signals may be constant (i.e., power control is not supported). As a second option, the transmit power of the uplink reference signals may be based on existing power control procedures. As a third option, the transmit power may be determined by modifying existing power control procedures. For example, the downlink reference signals of neighboring cells may be configured to be used for path loss estimation for the uplink reference signals. More specifically, the UE may estimate the path loss of the downlink reference signals and determine an appropriate transmit power for the uplink reference signals based on the determined path loss. In one aspect, the downlink reference signals may be CSI-RS, SSB, downlink PRS, etc.

[0140]

[0146] With reference to the third option, which uses a downlink reference signal from a neighboring cell to estimate the path loss of an uplink reference signal, various other features need to be supported in 5G NR in addition to the existing legacy behavior. For example, there needs to be support for configuring the downlink reference signal of a neighboring cell to be used as a downlink path loss reference for purposes of uplink reference signal power control. However, if the UE is unable to obtain a path loss reference, there is currently no identified fallback procedure. Therefore, this disclosure describes various fallback procedures for when the UE is unable to obtain a path loss reference.

[0141]

[0147] In addition to using downlink reference signals to determine the transmit power of uplink reference signals, a UE can use downlink reference signals from neighboring cells to determine the spatial direction of an uplink transmit beam (also referred to as a spatial transmit QCL, spatial QCL, spatial transmit beam, etc.) carrying the uplink reference signal (again, in the case of a positioning procedure). The downlink reference signal for determining the transmit power of the uplink reference signal and the downlink reference signal for determining the spatial direction of the uplink transmit beam may, but need not, be the same downlink reference signal. For uplink beam management / alignment to the serving cell and neighboring cells, various features are currently supported (in addition to UE transmit beam sweeping). First, configuration of the spatial relationship between downlink reference signals from the serving or neighboring cell and target uplink reference signals is supported. Downlink reference signals that may be used include at least SSB and possibly CSI-RS and PRS. Second, for both FR1 and FR2, a fixed transmit beam for uplink reference signal transmission across multiple uplink reference signal resources is supported. It should be noted that currently, a UE is not expected to transmit multiple uplink reference signal resources with different spatial relationships within the same OFDM symbol.

[0142]

[0148] As described above, the UE may calculate the transmit power for the uplink reference signal based on the path loss of the downlink reference signal. The UE may calculate the transmit power as follows: If the UE transmits an uplink reference signal (e.g., SRS) on the uplink BWPb of carrier f of serving cell c using an SRS power control adjustment state with index l, the UE may calculate the SRS transmit power P at SRS transmission occasion i as SRS、b、f、c (i, q s , l) is determined as follows (unit: dBm):

[0143]

number

[0144] however, -P CMAX、f、c (i) is the configured UE transmit power for carrier f of serving cell c at SRS transmission occasion i; -P O_SRS、b、f、c (q s ) is the upper layer parameter p0 for the uplink BWPb of carrier f of serving cell c and the SRS resource set q provided by the upper layer parameters SRS-ResourceSet and SRS-ResourceSetId. s If p0 is not provided, P O_SRS、b、f、c (q s )=P O_NOMINALPUSCH、f、c (0).

[0145] -M SRS、b、f、c (i) is the SRS bandwidth in number of resource blocks for SRS transmission occasion i on the active uplink BWPb of carrier f of serving cell c, and μ is the SCS configuration.

[0146] - α SRS、b、f、c (qs) is the upper layer parameter alpha for the uplink BWPb of carrier f of serving cell c and the SRS resource set q s and provided by.

[0147] - PL b、f、c (q d ) is the reference signal index q for the downlink BWP linked with the uplink BWP b of carrier f of serving cell c. d and SRS resource set q s is the downlink path loss estimate in dB calculated by the UE using the reference signal index q d is the SRS resource set q sThe pathlossReferenceRS parameter is provided by the higher layer parameter associated with the UE, and is either the higher layer parameter ssb-Index, which provides the SS / PBCH block index, or the higher layer parameter csi-RS-Index, which provides the CSI-RS resource index. If the UE is not provided with the higher layer parameter pathlossReferenceRS, or before the UE is provided with a dedicated higher layer parameter, the UE shall use the reference signal resource obtained from the SS / PBCH block index used by the UE to obtain the MIB to calculate the PL b、f、c (q d If the UE is provided with pathlossReferenceLinking, the reference signal resource is on the serving cell indicated by the value of pathlossReferenceLinking.

[0148] -h b、f、c (i, l)=f b、f、c (i, l), where f b、f、c (i,l) is the current PUSCH power control adjustment state when the higher layer parameter srs-PowerControlAdjustmentStates indicates the same power control adjustment state for SRS and PUSCH transmissions.

[0149] As mentioned above, up to four BWPs can be specified in the downlink and uplink. Currently, there can be one path loss estimate per BWP and up to four path loss estimates per serving cell. Specifically, the UE is not expected to simultaneously maintain more than four path loss estimates per serving cell for all PUSCH / PUCCH / SRS transmissions. The pathlossReferenceLinking parameter indicates whether the UE should apply the downlink of the PCell or the SCell corresponding to this uplink as the path loss reference.

[0150] As mentioned above, some wireless communication networks, such as 5G NR, may employ mmW or near-mmW frequencies to increase network capacity. The use of mmW frequencies may be in addition to microwave frequencies (e.g., in the sub-6 GHz band), which may also be supported for use in communications, for example, when carrier aggregation is used. Because communications at high mmW frequencies utilize directionality (e.g., communication via directional beams) to compensate for higher propagation losses, base stations and UEs may need to align their beams during both initial network access (e.g., a random access procedure as illustrated in FIGS. 5A and 5B) and subsequent data transmissions to ensure maximum gain. The base station and UE may determine the best beam for communicating with each other, and subsequent communications between the base station and UE may be via the selected beam. However, due to UE mobility / movement, beam reconfiguration at the base station, and / or other factors, a downlink beam (e.g., including a downlink control link) that could have been a suitable active beam may not be detected at the UE, or the signal quality may drop below a threshold, causing the UE to consider it a beam / link failure.

[0151] A beam recovery procedure (e.g., as illustrated in FIG. 6) may be employed to recover from beam failure. Beam failure may refer, for example, to the inability to detect a strong downlink transmission beam (e.g., having signal power greater than a threshold), the inability to accurately measure the path loss of a reference signal (e.g., based on a signal strength threshold), etc. The recovery process may include the UE performing a random access procedure (e.g., as illustrated in FIGS. 5A and 5B) to request a new beam assignment. Specifically, the UE may indicate a new SSB or CSI-RS for the new transmission beam during the random access procedure. The base station assigns the new beam based on the beam failure recovery request from the UE by transmitting a downlink assignment or an uplink grant on the PDCCH. A new beam pair (i.e., a transmit / receive beam pair) may then be established.

[0152] Performing path loss estimation or spatial transmit beam determination (also called spatial transmit QCL determination) on downlink reference signals from neighboring (non-serving) cells can be a challenging task because the neighboring cells can be far away. Path loss estimates are prone to errors, and as a result, transmit power or spatial transmit decisions made by the UE can be prone to errors. Therefore, various issues need to be addressed, such as how the UE should notify a location server (e.g., location server 230, LMF 270) that a path loss reference signal or spatial transmit beam reference signal is failing, how the UE should transmit uplink reference signal resources while the downlink reference signal is failing, and procedures for avoiding failure of path loss or spatial transmit estimation for neighboring cells.

[0153]

[0153] If a UE is configured to perform path loss estimation or spatial transmit QCL determination using downlink reference signals from a neighboring cell and the UE identifies that the reference signals cannot be used for this purpose, there are several options for how the UE can notify the location server that the reference signals are failing. As a first option, the UE can notify the serving base station (which then notifies the location server), e.g., through RRC signaling, that the path loss downlink reference signal or spatial transmit QCL downlink reference signal for a particular uplink reference signal resource is failing, or the UE can notify the location server directly through higher layer signaling (e.g., LTE Positioning Protocol (LPP)). As a second option, the UE can request to be configured with alternative downlink reference signals and / or secondary downlink reference signals from the serving cell to replace the affected uplink reference signal resources. As a third option, the UE may request to be configured with alternative downlink reference signals and / or secondary downlink reference signals from neighboring cells to replace the affected uplink reference signal resources.

[0154]

[0154] Being configured with an alternative downlink reference signal means that the UE is configured with multiple downlink reference signals and can choose one of them. Being configured with a secondary downlink reference signal means that the UE is configured with a primary downlink reference signal but can use the secondary downlink reference signal if the primary downlink reference signal fails. The first three options are complementary insofar as the UE can report that a downlink reference signal has failed (first option) and request a replacement (second and third options).

[0155]

[0155] As a fourth option, the UE can initiate a random access procedure with the serving cell, as in the case of the beam failure recovery procedure, but using a preamble sequence number that indicates that the downlink transmission beam of a neighboring cell has failed, rather than the downlink transmission beam from the serving cell. Based on the sequence number, the serving cell can notify the location server or neighboring cell of the beam failure through a higher layer protocol (e.g., the Xn interface). As a fifth option, the UE can initiate a partial beam failure recovery procedure, which means that the UE can report that a subset of neighboring downlink reference signals (more than one of the neighboring downlink reference signals) has failed. This report can be through the normal PUCCH / PUSCH channel, rather than the PRACH, as in the fourth option. The serving cell can then notify the location server or neighboring cell of the failure through a higher layer protocol (e.g., the Xn interface).

[0156] Another issue is how the UE should transmit uplink reference signal resources while the downlink reference signal is out of order. If the UE is configured to perform path loss estimation using a downlink reference signal from a neighboring cell and the UE identifies that the reference signal cannot be used for this purpose, there are various options the UE can follow. If the downlink reference signal is being used for path loss reference, as a first option, the UE can transmit the uplink reference signal at its maximum transmit power until a new downlink reference signal is configured for path loss estimation. If the UE can no longer detect the downlink reference signal from the neighboring cell, the UE may transmit at its maximum transmit power under the assumption that this is because the neighboring cell is too far away. As a second option, the UE can use the configured secondary downlink reference signal (as required above) from the serving cell or a neighboring cell to assist in path loss estimation. As a third option, the UE can use the path loss downlink reference signal configured for the serving cell's (or PUSCH / PUCCH's) uplink reference signal. As a fourth option, the UE may use a default downlink transmit beam (i.e., the same downlink transmit beam) for both the path loss reference signal and the spatial QCL reference signal. For example, the UE may use the transmit beam with the smallest uplink reference signal resource ID.

[0157]

[0157] When a downlink reference signal is used for spatial QCL reference, as a first option, the UE can use the configured secondary downlink reference signal from the serving cell to assist in deriving the uplink transmit beam (spatial QCL). As a second option, when the UE is configured with multiple downlink reference signals from a particular neighboring cell, the UE can transmit the effected resource using one of the uplink transmit beams derived from other downlink reference signals of the same neighboring cell. As a third option, when the UE is configured with only one downlink reference signal from a neighboring cell, the UE can transmit the effected resource using an uplink transmit beam derived from the downlink reference signal of the serving cell. As a fourth option, the UE can use a default downlink transmit beam (i.e., the same downlink transmit beam) for both the path loss downlink reference signal and the spatial QCL downlink reference signal. For example, the UE may use the transmit beam with the smallest uplink reference signal resource ID.

[0158]

[0158] As will be appreciated, the options for both path loss and spatial QCL uplink reference signals are similar, except that maximum transmit power is used in the case where a failed downlink reference signal is used for path loss reference.

[0159]

[0159] Now, referring to a procedure for avoiding failure of path loss / spatial transmit QCL estimation downlink reference signals from neighboring cells, there are several steps that can be taken. First, the location server can configure the UE with downlink reference signals from neighboring cells to perform path loss or spatial transmit beam determination. Second, the UE can periodically report the RSRP, RSRQ, and / or SINR of any downlink reference signals from neighboring cells that are being used for path loss or spatial transmit QCL estimation of uplink reference signal transmissions. Alternatively, the location server can configure for which downlink reference signals such reporting is useful. This can be achieved through direct reporting to the location server or reporting to a base station, which then relays the report to a neighboring base station (e.g., via the Xn interface) or to a location server (e.g., location server 230, LMF 270). Third, if the RSRP / RSRQ / SINR is low, the location server can proactively reconfigure the downlink reference signals.

[0160]

[0160] The RSRP / RSRQ / SINR thresholds may be used to determine whether the current downlink reference signal may be used for path loss reference estimation or spatial QCL determination.

[0161] 8 illustrates an example method 800 of wireless communication according to an aspect of the present disclosure. In one aspect, the method 800 may be performed by a UE (e.g., any of the UEs described herein).

[0162] At 810, the UE receives a positioning configuration (e.g., via RRC, LPP, and / or other signaling from a location server, serving cell, or other such entity), the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell that may be used to estimate downlink path loss or determine an uplink spatial transmit beam. In one aspect, operation 810 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, and / or all of these may be considered means for performing this operation.

[0163] At 820, the UE determines whether the first downlink reference signal received from the neighboring cell failed. In one aspect, operation 820 may be performed by the WWAN transceiver 310, the processing system 332, the memory component 340, and / or the positioning component 342, and / or all of these may be considered means for performing this operation.

[0164] At 830, in response to determining that the first downlink reference signal has failed, the UE estimates a downlink path loss or determines an uplink spatial transmit beam based on a second downlink reference signal received from a neighboring cell or a serving cell for the UE. In one aspect, operation 830 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, and / or all of these may be considered means for performing this operation.

[0165] At 840, the UE transmits an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof. In one aspect, operation 840 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, and / or all of these may be considered means for performing this operation.

[0166] 9 illustrates an example method 900 of wireless communication according to an aspect of the present disclosure. In one aspect, the method 900 may be performed by a location server (eg, location server 230, LMF 270).

[0167] At 910, the location server configures (e.g., via LPP) the UE (e.g., any of the UEs described herein) to receive at least a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmit beam. In one aspect, operation 910 may be performed by the network interface 390, the processing system 394, the memory component 396, and / or the positioning component 398, and / or all of these may be considered means for performing this operation.

[0168] At 920, the location server receives a report from the UE indicating the signal quality of the first downlink reference signal. In one aspect, operation 920 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, and / or all of these may be considered means for performing this operation.

[0169] At 930, based on the signal quality of the first downlink reference signal being below a threshold, the location server configures the UE to at least receive a second downlink reference signal from a neighboring cell or a serving cell, which will be used to estimate downlink path loss or determine an uplink spatial transmit beam. In one aspect, operation 930 may be performed by network interface 390, processing system 394, memory component 396, and / or positioning component 398, and / or all of these may be considered means for performing this operation.

[0170] 10 illustrates an example method 1000 of wireless communication according to an aspect of the present disclosure. In one aspect, the method 1000 may be performed by a UE (e.g., any of the UEs described herein).

[0171] At 1010, the UE receives from a network node (e.g., a serving base station or a location server) (e.g., via RRC, LPP, and / or other signaling from a location server, serving cell, or other such entity) a configuration to use at least a first downlink reference signal from a neighboring cell to estimate downlink path loss or determine an uplink spatial transmit beam. In one aspect, operation 1010 may be performed by the WWAN transceiver 310, the processing system 332, the memory component 340, and / or the positioning component 342, and / or all of these may be considered means for performing this operation.

[0172] At 1020, the UE sends a report indicating the signal quality of the first downlink reference signal to the network node. In one aspect, operation 1020 may be performed by the WWAN transceiver 310, the processing system 332, the memory component 340, and / or the positioning component 342, and / or all of these may be considered means for performing this operation.

[0173] At 1030, based on the signal quality of the first downlink reference signal being below a threshold, the UE receives from a network node (e.g., via RRC, LPP, and / or other signaling from a location server, serving cell, or other such entity) a configuration to use at least the second downlink reference signal from a neighbor cell or the serving cell to estimate downlink path loss or determine an uplink spatial transmit beam. In one aspect, operation 1030 may be performed by WWAN transceiver 310, processing system 332, memory component 340, and / or positioning component 342, and / or all of these may be considered means for performing this operation.

[0174] Those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0175]

[0175] Furthermore, those skilled in the art will understand that the various illustrative logic blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or a combination of both. To clearly illustrate this interchangeability between hardware and software, the various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure.

[0176] The various illustrative logic blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed using a general-purpose processor, a DSP, an ASIC, an FPGA, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0177] The methods, sequences, and / or algorithms described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a random access memory (RAM), flash memory, read-only memory (ROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal (e.g., a UE). In the alternative, the processor and the storage medium may reside as discrete components in the user terminal.

[0178] In one or more exemplary aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technology such as infrared, radio, and microwave, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technology such as infrared, radio, and microwave are included within the definition of medium. Disk and disc, as used herein, include compact discs (CDs), laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, although disks typically reproduce data magnetically, while discs reproduce data optically using lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0179]

[0179] While the foregoing disclosure sets forth exemplary aspects of the present disclosure, it should be noted that various changes and modifications can be made herein without departing from the scope of the present disclosure, as defined by the appended claims. The functions, steps and / or actions of the method claims in accordance with the aspects of the present disclosure described herein need not be performed in any particular order. Furthermore, although elements of the present disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. The inventions described in the claims of the present application as originally filed are set forth below. [C1] 1. A method of wireless communication implemented by a user equipment (UE), comprising: receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss or determining an uplink spatial transmit beam; determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam; and In response to the determination, estimating the downlink path loss or determining the uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or a serving cell; transmitting an uplink reference signal for positioning based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof; A method for providing the above. [C2] The method of C1, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell. [C3] The method of C1, further comprising setting a transmit power of the uplink reference signal based on the estimated downlink path loss. [C4] The method described in C1 further comprises setting a spatial beam direction of a transmission beam directed toward the neighboring cell based on the determined uplink spatial transmission beam, the transmission beam carrying the uplink reference signal. [C5] The method of C1 further comprises reporting to the serving cell or location server that the first downlink reference signal has failed based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam. [C6] The method of C1, wherein the UE determines that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam based on the signal quality of the first downlink reference signal being below a threshold. [C7] The method of C6, wherein the threshold comprises a reference signal received power (RSRP) threshold configured for the UE. [C8] The method of C1 further comprises transmitting a sequence number indicating that the first downlink reference signal has failed to the serving cell via a physical random access channel (PRACH) procedure based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam. [C9] The method of C1 further comprises requesting the serving cell to transmit an alternative and / or secondary downlink reference signal configured to enable the UE to estimate the downlink path loss or determine the uplink spatial transmit beam. [C10] The method of C1 further comprises requesting the neighboring cell to transmit an alternative and / or secondary downlink reference signal configured to enable the UE to estimate the downlink path loss or determine the uplink spatial transmit beam. [C11] The method of C10, wherein the UE sends the request to the serving cell. [C12] The method of C1, further comprising initiating a partial beam failure recovery procedure to report that a subset of downlink reference signals from the neighboring cell has failed. [C13] The method of C12, wherein the subset of downlink reference signals comprises more than one downlink reference signal from the neighboring cell. [C14] The method of C1, wherein the UE receives a plurality of downlink reference signals from the neighboring cells, and the first and second downlink reference signals are two of the plurality of downlink reference signals. [C15] the first downlink reference signal is configured for downlink path loss estimation for a first carrier bandwidth portion used for communication with the neighboring cell; the second downlink reference signal is configured for downlink path loss estimation for a second carrier bandwidth portion used for communication with the neighboring cell; The method described in C14. [C16] the first downlink reference signal is the only downlink reference signal that the UE receives from the neighboring cell; the second downlink reference signal is a downlink reference signal received from the serving cell; The method described in C1. [C17] The method of C1, wherein the second downlink reference signal is a default downlink reference signal used for both the estimated downlink path loss and the determined uplink spatial transmit beam. [C18] The method of C17, wherein the second downlink reference signal is received on a transmission beam from the serving cell. [C19] The method of C1, wherein the UE transmits an uplink reference signal at maximum transmit power after determining that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam and before estimating the downlink path loss based on the second downlink reference signal. [C20] The method of C1, wherein the second downlink reference signal is a secondary downlink reference signal from the serving cell configured to assist in determining the uplink spatial transmit beam. [C21] The method of C1, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell. [C22] 1. A method of wireless communication implemented by a location server, comprising: Configuring a user equipment (UE) to receive at least a first downlink reference signal from a neighboring cell to be used for estimating a downlink path loss or determining an uplink spatial transmit beam; receiving a report from the UE indicating a signal quality of the first downlink reference signal; configuring the UE to at least receive a second downlink reference signal from the neighboring cell or a serving cell, the second downlink reference signal being used to estimate the downlink path loss or determine the uplink spatial transmit beam based on the signal quality of the first downlink reference signal being below a threshold; A method for providing the above. [C23] The method of C22, wherein the signal quality of the first downlink reference signal being below the threshold indicates that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam. [C24] The method of C22, wherein the location server periodically receives the report indicating the signal quality of the first downlink reference signal. [C25] 1. A method of wireless communication implemented by a user equipment (UE), comprising: receiving, from a network node, a configuration to use at least a first downlink reference signal from a neighboring cell for estimating a downlink path loss or determining an uplink spatial transmit beam; sending a report to the network node indicating a signal quality of the first downlink reference signal; receiving from the network node a configuration to use at least a second downlink reference signal from the neighboring cell or a serving cell for estimating the downlink path loss or determining the uplink spatial transmit beam based on the signal quality of the first downlink reference signal being below a threshold; A method for providing the above. [C26] The method of C25, wherein the network node comprises a serving base station for the UE. [C27] The method of C25, wherein the network node comprises a location server. [C28] The method of C25, wherein the signal quality of the first downlink reference signal being below the threshold indicates that the first downlink reference signal cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam. [C29] The method of C25, wherein the UE periodically sends the report indicating the signal quality of the first downlink reference signal. [C30] A user equipment (UE), Memory and at least one transceiver; at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor: receiving a positioning configuration via the at least one transceiver, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used to estimate a downlink path loss or determine an uplink spatial transmit beam; determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss or determine the uplink spatial transmit beam; and In response to the determination, estimating the downlink path loss or determining the uplink spatial transmit beam based on a second downlink reference signal received from the neighboring cell or a serving cell; transmitting an uplink reference signal for positioning from the at least one transceiver based on the estimated downlink path loss, the determined uplink spatial transmit beam, or a combination thereof; UE configured to:

Claims

1. 1. A method of wireless communication implemented by a user equipment (UE), comprising: receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss; determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss; estimating the downlink path loss based on a second downlink reference signal received from the neighboring cell or the serving cell in response to the determining; transmitting an uplink reference signal for positioning with a transmit power set based on the estimated downlink path loss; A method for providing the above.

2. 2. The method of claim 1, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell.

3. The method of claim 1, further comprising setting a spatial beam direction of a transmit beam directed toward the neighboring cell, the transmit beam carrying the uplink reference signal.

4. 10. The method of claim 1, further comprising: reporting to the serving cell or a location server that the first downlink reference signal has failed based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss.

5. 2. The method of claim 1, wherein the UE determines that the first downlink reference signal cannot be used to estimate the downlink path loss based on a signal quality of the first downlink reference signal being below a threshold.

6. The method of claim 5 , wherein the threshold comprises a reference signal received power (RSRP) threshold configured for the UE.

7. 2. The method of claim 1, further comprising: based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss, transmitting a sequence number indicating that the first downlink reference signal failed to the serving cell via a Physical Random Access Channel (PRACH) procedure.

8. 2. The method of claim 1, further comprising requesting the serving cell to transmit alternative and / or secondary downlink reference signals configured to enable the UE to estimate the downlink path loss.

9. 2. The method of claim 1, further comprising requesting the neighboring cell to transmit alternative and / or secondary downlink reference signals configured to enable the UE to estimate the downlink path loss.

10. The method of claim 9, wherein the request is sent to the serving cell.

11. 10. The method of claim 1, further comprising initiating a partial beam failure recovery procedure to report that a subset of downlink reference signals from the neighboring cell has failed.

12. The method of claim 11 , wherein the subset of downlink reference signals comprises more than one downlink reference signal from the neighboring cell.

13. The method of claim 1, wherein a plurality of downlink reference signals are received from the neighboring cells, and the first and second downlink reference signals are two of the plurality of downlink reference signals.

14. the first downlink reference signal is configured for downlink path loss estimation for a first carrier bandwidth portion used for communication with the neighboring cell; the second downlink reference signal is configured for downlink path loss estimation for a second carrier bandwidth portion used for communication with the neighboring cell. The method of claim 13.

15. the first downlink reference signal is the only downlink reference signal that the UE receives from the neighboring cell; the second downlink reference signal is a downlink reference signal received from the serving cell; The method of claim 1.

16. The method of claim 1 , wherein the second downlink reference signal is a default downlink reference signal used for the estimated downlink path loss.

17. 17. The method of claim 16, wherein the second downlink reference signal is received on a transmit beam from the serving cell.

18. 2. The method of claim 1, wherein the UE transmits an uplink reference signal at maximum transmit power after determining that the first downlink reference signal cannot be used to estimate the downlink path loss and before estimating the downlink path loss based on the second downlink reference signal.

19. The method of claim 1 , wherein the second downlink reference signal is a secondary downlink reference signal from the serving cell.

20. 2. The method of claim 1, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell.

21. A user equipment (UE), Memory and at least one transceiver; at least one processor communicatively coupled to the memory and the at least one transceiver, wherein the at least one processor: receiving a positioning configuration via the at least one transceiver, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss; determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss; estimating the downlink path loss based on a second downlink reference signal received from the neighboring cell or the serving cell in response to the determining; transmitting an uplink reference signal for positioning from the at least one transceiver, the uplink reference signal having a transmission power set based on the estimated downlink path loss; A UE configured to:

22. The UE of claim 21, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell.

23. The UE of claim 21, wherein the at least one processor is further configured to set a spatial beam direction of a transmit beam directed toward the neighboring cell, the transmit beam carrying the uplink reference signal.

24. The UE of claim 21, wherein the at least one processor is configured to report to the serving cell or location server that the first downlink reference signal has failed based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss.

25. The UE of claim 21, wherein the UE determines that the first downlink reference signal cannot be used to estimate the downlink path loss based on the signal quality of the first downlink reference signal being below a threshold.

26. The UE of claim 25, wherein the threshold comprises a reference signal received power (RSRP) threshold configured for the UE.

27. ​​The UE of claim 21, wherein the at least one processor is further configured to, based on determining that the first downlink reference signal cannot be used to estimate the downlink path loss, transmit a sequence number indicating that the first downlink reference signal has failed to the serving cell via a Physical Random Access Channel (PRACH) procedure.

28. The UE of claim 21, wherein the at least one processor is further configured to request that the serving cell transmit an alternative and / or secondary downlink reference signal configured to enable the UE to estimate the downlink path loss.

29. The UE of claim 21, wherein the at least one processor is further configured to request that the neighboring cell transmit an alternative and / or secondary downlink reference signal configured to enable the UE to estimate the downlink path loss.

30. The UE of claim 29, wherein the request is sent to the serving cell.

31. The UE of claim 21, wherein the at least one processor is further configured to initiate a partial beam failure recovery procedure to report that a subset of downlink reference signals from the neighboring cell has failed.

32. The UE of claim 31, wherein the subset of downlink reference signals comprises more than one downlink reference signal from the neighboring cell.

33. The UE of claim 21, wherein a plurality of downlink reference signals are received from the neighboring cells, and the first and second downlink reference signals are two of the plurality of downlink reference signals.

34. The method of claim 34, wherein the first downlink reference signal is configured for downlink path loss estimation for a first carrier bandwidth portion used for communication with the neighboring cell; the second downlink reference signal is configured for downlink path loss estimation for a second carrier bandwidth portion used for communication with the neighboring cell.

34. The UE of claim 33.

35. The method of claim 35, wherein the first downlink reference signal is the only downlink reference signal that the UE receives from the neighboring cell; the second downlink reference signal is a downlink reference signal received from the serving cell; 22. The UE of claim 21.

36. The UE of claim 21, wherein the second downlink reference signal is a default downlink reference signal used for the estimated downlink path loss.

37. 37. The UE of claim 36, wherein the second downlink reference signal is received on a transmit beam from the serving cell.

38. The UE of claim 21, wherein the at least one processor is further configured to transmit an uplink reference signal at maximum transmit power after determining that the first downlink reference signal cannot be used to estimate the downlink path loss and before estimating the downlink path loss based on the second downlink reference signal.

39. The UE of claim 21, wherein the second downlink reference signal is a secondary downlink reference signal from the serving cell.

40. The UE of claim 21, wherein the second downlink reference signal is a synchronization signal (SS) / physical broadcast channel (PBCH) block from the serving cell that the UE uses to obtain a master information block (MIB) for the serving cell.

41. A user equipment (UE), comprising: means for receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss; means for determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss; means for estimating the downlink path loss based on a second downlink reference signal received from the neighboring cell or a serving cell; means for transmitting an uplink reference signal for positioning, the uplink reference signal having a transmission power set based on the estimated downlink path loss; A UE comprising:

42. A non-transitory computer-readable medium storing computer-readable instructions that, when executed by a user equipment (UE), cause the UE to: receiving a positioning configuration, the positioning configuration including at least an identifier of a first downlink reference signal from a neighboring cell to be used for estimating downlink path loss; determining that the first downlink reference signal received from the neighboring cell cannot be used to estimate the downlink path loss; estimating the downlink path loss based on a second downlink reference signal received from the neighboring cell or the serving cell; transmitting an uplink reference signal for positioning with a transmit power set based on the estimated downlink path loss; A non-transitory computer-readable medium for causing

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