Patent ID: 12196868

DETAILED DESCRIPTION

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

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 disclosure” does not require that all aspects of the disclosure include the discussed feature, advantage or mode of operation.

Those of skill 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 description below 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, in part on the desired design, in part on the corresponding technology, etc.

Further, many aspects are described in terms of sequences of actions to be performed by, for example, elements of a computing device. It will be recognized that various actions described herein can be performed by specific circuits (e.g., application specific integrated circuits (ASICs)), by program instructions being executed by one or more processors, or by a combination of both. Additionally, the sequence(s) of actions described herein can be considered to be embodied entirely within any form of non-transitory computer-readable storage medium having stored therein a corresponding set of computer instructions that, upon execution, would cause or instruct an associated processor of a device to perform the functionality described herein. Thus, the various aspects of the disclosure may be embodied in a number of different forms, all of which have been contemplated to be within the scope of the claimed subject matter. In addition, for each of the aspects described herein, the corresponding form of any such aspects may be described herein as, for example, “logic configured to” perform the described action.

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 noted. In general, a UE may be any wireless communication device (e.g., a mobile phone, router, tablet computer, laptop computer, tracking device, wearable (e.g., smartwatch, glasses, augmented reality (AR)/virtual reality (VR) headset, etc.), vehicle (e.g., automobile, motorcycle, bicycle, etc.), Internet of Things (IoT) device, etc.) used by a user to communicate over a wireless communications network. A UE may be mobile or may (e.g., at certain times) be 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 device,” a “mobile terminal,” a “mobile station,” or variations thereof. Generally, UEs can communicate with a core network via a RAN, and through the core network the UEs can be connected with external networks such as the Internet and with other UEs. Of course, other mechanisms of connecting to the core network and/or the Internet are also possible for the UEs, such as over wired access networks, wireless local area network (WLAN) networks (e.g., based on IEEE 802.11, etc.) and so on.

A base station may operate according to one of several RATs in communication with UEs depending on the network in which it is deployed, and may be alternatively referred to as an access point (AP), a network node, a NodeB, an evolved NodeB (eNB), a next generation eNB (ng-eNB), a New Radio (NR) Node B (also referred to as a gNB or gNodeB), etc. A base station may be used primarily to support wireless access by UEs, including supporting data, voice, and/or signaling connections for the supported UEs. In some systems a base station may provide purely edge node signaling functions while in other systems it may provide additional control and/or network management functions. A communication link through which UEs can send signals to a base station is called an uplink (UL) channel (e.g., a reverse traffic channel, a reverse control channel, an access channel, etc.). A communication link through which the base station can send signals to UEs is called a downlink (DL) or forward link channel (e.g., a paging channel, a control channel, a broadcast channel, a forward traffic channel, etc.). As used herein the term traffic channel (TCH) can refer to either an UL/reverse or DL/forward traffic channel.

The term “base station” may refer to a single physical transmission-reception point (TRP) or to multiple physical TRPs that may or may not be co-located. For example, where the term “base station” refers to a single physical TRP, the physical TRP may be an antenna of the base station corresponding to a cell (or several cell sectors) of the base station. Where the term “base station” refers to multiple co-located physical TRPs, the physical TRPs may be an array of antennas (e.g., as in a multiple-input multiple-output (MIMO) system or where the base station employs beamforming) of the base station. Where the term “base station” refers to multiple non-co-located physical TRPs, the physical TRPs 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-co-located physical TRPs may be the serving base station receiving the measurement report from the UE or a neighbor base station whose reference RF signals (or simply “reference signals”) the UE is measuring. Because a TRP is the point from which a base station transmits and receives wireless signals, as used herein, references to transmission from or reception at a base station are to be understood as referring to a particular TRP of the base station.

In some implementations that support positioning of UEs, a base station may not support wireless access by UEs (e.g., may not support data, voice, and/or signaling connections for UEs), but may instead transmit reference signals to UEs to be measured by the UEs, and/or may receive and measure signals transmitted by the UEs. Such a base station may be referred to as a positioning beacon (e.g., when transmitting signals to UEs) and/or as a location measurement unit (e.g., when receiving and measuring signals from UEs).

An “RF signal” comprises an electromagnetic wave of a given frequency that transports information through the 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 multipath channels. The same transmitted RF signal on different paths between the transmitter and receiver may be referred to as a “multipath” RF signal. As used herein, an RF signal may also be referred to as a “wireless signal” or simply a “signal” where it is clear from the context that the term “signal” refers to a wireless signal or an RF signal.

According to various aspects,FIG.1illustrates an exemplary wireless communications system100. The wireless communications system100(which may also be referred to as a wireless wide area network (WWAN)) may include various base stations102and various UEs104. The base stations102may include macro cell base stations (high power cellular base stations) and/or small cell base stations (low power cellular base stations). In an aspect, the macro cell base station may include eNBs and/or ng-eNBs where the wireless communications system100corresponds to an LTE network, or gNBs where the wireless communications system100corresponds to a NR network, or a combination of both, and the small cell base stations may include femtocells, picocells, microcells, etc.

The base stations102may collectively form a RAN and interface with a core network170(e.g., an evolved packet core (EPC) or a 5G core (5GC)) through backhaul links122, and through the core network170to one or more location servers172(which may be part of core network170or may be external to core network170). In addition to other functions, the base stations102may perform functions that relate to one or more of transferring user data, radio channel ciphering and deciphering, 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 service (MBMS), subscriber and equipment trace, RAN information management (RIM), paging, positioning, and delivery of warning messages. The base stations102may communicate with each other directly or indirectly (e.g., through the EPC/5GC) over backhaul links134, which may be wired or wireless.

The base stations102may wirelessly communicate with the UEs104. Each of the base stations102may provide communication coverage for a respective geographic coverage area110. In an aspect, one or more cells may be supported by a base station102in each geographic coverage area110. A “cell” is a logical communication entity used for communication with a base station (e.g., over some frequency resource, referred to as a carrier frequency, component carrier, carrier, band, or the like), and may be associated with an identifier (e.g., a physical cell identifier (PCI), a virtual cell identifier (VCI), a cell global identifier (CGI)) for distinguishing cells operating via the same or a different carrier frequency. 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 specific base station, the term “cell” may refer to either or both of the logical communication entity and the base station that supports it, depending on the context. In addition, because a TRP is typically the physical transmission point of a cell, the terms “cell” and “TRP” may be used interchangeably. In some cases, the term “cell” may also refer to a geographic coverage area of a base station (e.g., a sector), insofar as a carrier frequency can be detected and used for communication within some portion of geographic coverage areas110.

While geographic coverage areas110of neighboring macro cell base station102may partially overlap (e.g., in a handover region), some of the geographic coverage areas110may be substantially overlapped by a larger geographic coverage area110. For example, a small cell base station102′ (denoted as “SC” inFIG.1) may have a geographic coverage area110′ that substantially overlaps with the geographic coverage area110of one or more macro cell base stations102. A network that includes both small cell and macro cell base stations may be known as a heterogeneous network. A heterogeneous network may also include home eNBs (HeNBs), which may provide service to a restricted group known as a closed subscriber group (CSG).

The communication links120between the base stations102and the UEs104may include UL (also referred to as reverse link) transmissions from a UE104to a base station102and/or downlink (DL) (also referred to as forward link) transmissions from a base station102to a UE104. The communication links120may use MIMO antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links120may be implemented through one or more carrier frequencies. Allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or less carriers may be allocated for DL than for UL).

The wireless communications system100may further include a wireless local area network (WLAN) access point (AP)150in communication with WLAN stations (STAs)152via communication links154in an unlicensed frequency spectrum (e.g., 5 GHz). When communicating in an unlicensed frequency spectrum, the WLAN STAs152and/or the WLAN AP150may perform a clear channel assessment (CCA) or listen before talk (LBT) procedure prior to communicating in order to determine whether the channel is available.

The small cell base station102′ may operate in a licensed and/or an unlicensed frequency spectrum. When operating in an unlicensed frequency spectrum, the small cell base station102′ may employ LTE or NR technology and use the same 5 GHz unlicensed frequency spectrum as used by the WLAN AP150. The small cell base station102′, employing LTE/5G in an unlicensed frequency spectrum, may boost coverage to and/or increase capacity of the access network. NR in 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 MulteFire.

The wireless communications system100may further include a millimeter wave (mmW) base station180that may operate in mmW frequencies and/or near mmW frequencies in communication with a UE182. Extremely high frequency (EHF) is part of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz and a wavelength between 1 millimeter and 10 millimeters. Radio waves in this band may be referred to as a millimeter wave. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 millimeters. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, also referred to as centimeter wave. Communications using the mmW/near mmW radio frequency band have high path loss and a relatively short range. The mmW base station180and the UE182may utilize beamforming (transmit and/or receive) over a mmW communication link184to compensate for the extremely high path loss and short range. Further, it will be appreciated that in alternative configurations, one or more base stations102may also transmit using mmW or near mmW and beamforming. Accordingly, it will be appreciated that the foregoing illustrations are merely examples and should not be construed to limit the various aspects disclosed herein.

Transmit beamforming is a technique for focusing an RF signal in a specific direction. Traditionally, when a network node (e.g., a base station) broadcasts an RF signal, it broadcasts the signal in all directions (omni-directionally). 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 projects a stronger downlink RF signal in that specific direction, thereby providing a faster (in terms of data rate) and stronger RF signal for the receiving device(s). To change the directionality of the RF signal when transmitting, a network node can control the phase and relative amplitude of the RF signal at each of the one or more transmitters that are broadcasting the RF signal. For example, a network node may use an array of antennas (referred to as a “phased array” or an “antenna array”) that creates a beam of RF waves that can be “steered” to point in different directions, without actually moving the antennas. Specifically, the RF current from the transmitter is fed to the individual antennas with the correct phase relationship so that the radio waves from the separate antennas add together to increase the radiation in a desired direction, while cancelling to suppress radiation in undesired directions.

Transmit beams may be quasi-collocated, meaning that they appear to the receiver (e.g., a UE) as having the same parameters, regardless of whether or not the transmitting antennas of the network node themselves are physically collocated. In NR, there are four types of quasi-collocation (QCL) relations. Specifically, a QCL relation of a given type means that certain parameters about a second reference RF signal on a second beam can be derived from information about a source reference RF signal on a source beam. Thus, if the source reference RF signal is QCL Type A, the receiver can use the source reference RF signal to estimate the Doppler shift, Doppler spread, average delay, and delay spread of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type B, the receiver can use the source reference RF signal to estimate the Doppler shift and Doppler spread of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type C, the receiver can use the source reference RF signal to estimate the Doppler shift and average delay of a second reference RF signal transmitted on the same channel. If the source reference RF signal is QCL Type D, the receiver can use the source reference RF signal to estimate the spatial receive parameter of a second reference RF signal transmitted on the same channel.

In receive beamforming, the receiver 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 array of antennas in a particular direction to amplify (e.g., to increase the gain level of) the RF signals received from that direction. Thus, when a receiver is said to beamform in a certain direction, it means the beam gain in that direction is high relative to the beam gain along other directions, or the beam gain in that direction is the highest compared to the beam gain in that direction of all other receive beams available to the receiver. This results in a stronger received signal strength (e.g., reference signal received power (RSRP), reference signal received quality (RSRQ), signal-to-interference-plus-noise ratio (SINR), etc.) of the RF signals received from that direction.

Receive beams may be spatially related. A spatial relation means that parameters of a transmit beam for a second reference signal can be derived from information about a receive beam for a first reference signal. For example, a UE may use a particular receive beam to receive one or more reference downlink reference signals (e.g., positioning reference signals (PRS), navigation reference signals (NRS), tracking reference signals (TRS), cell-specific reference signals (CRS), channel state information reference signals (CSI-RS), primary synchronization signals (PSS), secondary synchronization signals (SSS), synchronization signal blocks (SSBs), etc.) from a base station. The UE can then form a transmit beam for sending one or more uplink reference signals (e.g., uplink positioning reference signals (UL-PRS), sounding reference signal (SRS), demodulation reference signals (DMRS), etc.) to that base station based on the parameters of the receive beam.

Note that a “downlink” beam may be either a transmit beam or a receive beam, depending on the entity forming it. For example, if a base station is forming the downlink beam to transmit a reference signal to a UE, the downlink beam is a transmit beam. If the UE is forming the downlink beam, however, it is a receive beam to receive the downlink reference signal. Similarly, an “uplink” beam may be either a transmit beam or a receive beam, depending on the entity forming it. For example, if a base station is forming the uplink beam, it is an uplink receive beam, and if a UE is forming the uplink beam, it is an uplink transmit beam.

In 5G, the frequency spectrum in which wireless nodes (e.g., base stations102/180, UEs104/182) operate is divided into multiple frequency ranges, FR1 (from 450 to 6000 MHz), FR2 (from 24250 to 52600 MHz), FR3 (above 52600 MHz), and FR4 (between FR1 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 a UE104/182and the cell in which the UE104/182either performs the initial radio resource control (RRC) connection establishment procedure or initiates the RRC connection re-establishment procedure. The primary carrier carries all common and UE-specific control channels, and may be a carrier in a licensed frequency (however, this is not always the case). A secondary carrier is a carrier operating on a second frequency (e.g., FR2) that may be configured once the RRC connection is established between the UE104and the anchor carrier and that may be used to provide additional radio resources. In some cases, the secondary carrier may be a carrier in an unlicensed frequency. The secondary carrier may contain only necessary signaling information and signals, for example, those that are UE-specific may not be present in the secondary carrier, since both primary uplink and downlink carriers are typically UE-specific. This means that different UEs104/182in a cell may have different downlink primary carriers. The same is true for the uplink primary carriers. The network is able to change the primary carrier of any UE104/182at any time. This is done, for example, to balance the load on different carriers. Because a “serving cell” (whether a PCell or an SCell) corresponds to a carrier frequency/component carrier over which some base station is communicating, the term “cell,” “serving cell,” “component carrier,” “carrier frequency,” and the like can be used interchangeably.

For example, still referring toFIG.1, one of the frequencies utilized by the macro cell base stations102may be an anchor carrier (or “PCell”) and other frequencies utilized by the macro cell base stations102and/or the mmW base station180may be secondary carriers (“SCells”). The simultaneous transmission and/or reception of multiple carriers enables the UE104/182to significantly increase its data transmission and/or reception rates. For example, two 20 MHz aggregated carriers in a multi-carrier system would theoretically lead to a two-fold increase in data rate (i.e., 40 MHz), compared to that attained by a single 20 MHz carrier.

The wireless communications system100may further include one or more UEs, such as UE190, that connects indirectly to one or more communication networks via one or more device-to-device (D2D) peer-to-peer (P2P) links. In the example ofFIG.1, UE190has a D2D P2P link192with one of the UEs104connected to one of the base stations102(e.g., through which UE190may indirectly obtain cellular connectivity) and a D2D P2P link194with WLAN STA152connected to the WLAN AP150(through which UE190may indirectly obtain WLAN-based Internet connectivity). In an example, the D2D P2P links192and194may be supported with any well-known D2D RAT, such as LTE Direct (LTE-D), WiFi Direct (WiFi-D), Bluetooth®, and so on.

The wireless communications system100may further include a UE164that may communicate with a macro cell base station102over a communication link120and/or the mmW base station180over a mmW communication link184. For example, the macro cell base station102may support a PCell and one or more SCells for the UE164and the mmW base station180may support one or more SCells for the UE164. In an aspect, the UE164may include an angle-based measurement manager166that may enable the UE164to perform the UE operations described herein. Note that although only one UE inFIG.1is illustrated as having an angle-based measurement manager166, any of the UEs inFIG.1may be configured to perform the UE operations described herein.

According to various aspects,FIG.2Aillustrates an example wireless network structure200. For example, a 5GC210(also referred to as a Next Generation Core (NGC)) can be viewed functionally as control plane functions214(e.g., UE registration, authentication, network access, gateway selection, etc.) and user plane functions212, (e.g., UE gateway function, access to data networks, IP routing, etc.) which operate cooperatively to form the core network. User plane interface (NG-U)213and control plane interface (NG-C)215connect the gNB222to the 5GC210and specifically to the control plane functions214and user plane functions212. In an additional configuration, an ng-eNB224may also be connected to the 5GC210via NG-C215to the control plane functions214and NG-U213to the user plane functions212. Further, ng-eNB224may directly communicate with gNB222via a backhaul connection223. In some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both ng-eNBs224and gNBs222. Either gNB222or ng-eNB224may communicate with UEs204(e.g., any of the UEs depicted inFIG.1). Another optional aspect may include location server230, which may be in communication with the 5GC210to provide location assistance for UEs204. The location server230can be implemented as a plurality of separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternately may each correspond to a single server. The location server230can be configured to support one or more location services for UEs204that can connect to the location server230via the core network, 5GC210, and/or via the Internet (not illustrated). Further, the location server230may be integrated into a component of the core network, or alternatively may be external to the core network.

According to various aspects,FIG.2Billustrates another example wireless network structure250. For example, a 5GC260can be viewed functionally as control plane functions, provided by an access and mobility management function (AMF)264, and user plane functions, provided by a user plane function (UPF)262, which operate cooperatively to form the core network (i.e., 5GC260). User plane interface263and control plane interface265connect the ng-eNB224to the 5GC260and specifically to UPF262and AMF264, respectively. In an additional configuration, a gNB222may also be connected to the 5GC260via control plane interface265to AMF264and user plane interface263to UPF262. Further, ng-eNB224may directly communicate with gNB222via the backhaul connection223, with or without gNB direct connectivity to the 5GC260. In some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both ng-eNBs224and gNBs222. Either gNB222or ng-eNB224may communicate with UEs204(e.g., any of the UEs depicted inFIG.1). The base stations of the New RAN220communicate with the AMF264over the N2 interface and with the UPF262over the N3 interface.

The functions of the AMF264include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between the UE204and a session management function (SMF)266, transparent proxy services for routing SM messages, access authentication and access authorization, transport for short message service (SMS) messages between the UE204and the short message service function (SMSF) (not shown), and security anchor functionality (SEAF). The AMF264also interacts with an authentication server function (AUSF) (not shown) and the UE204, and receives the intermediate key that was established as a result of the UE204authentication process. In the case of authentication based on a UMTS (universal mobile telecommunications system) subscriber identity module (USIM), the AMF264retrieves the security material from the AUSF. The functions of the AMF264also include security context management (SCM). The SCM receives a key from the SEAF that it uses to derive access-network specific keys. The functionality of the AMF264also includes location services management for regulatory services, transport for location services messages between the UE204and a location management function (LMF)270(which acts as a location server230), transport for location services messages between the New RAN220and the LMF270, evolved packet system (EPS) bearer identifier allocation for interworking with the EPS, and UE204mobility event notification. In addition, the AMF264also supports functionalities for non-3GPP access networks.

Functions of the UPF262include acting as an anchor point for intra-/inter-RAT mobility (when applicable), acting as an external protocol data unit (PDU) session point of interconnect 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 the DL), UL traffic verification (service data flow (SDF) to QoS flow mapping), transport level packet marking in the UL and DL, DL packet buffering and DL data notification triggering, and sending and forwarding of one or more “end markers” to the source RAN node (not shown). The UPF262may also support transfer of location services messages over a user plane between the UE204and a location server, such as a secure user plane location (SUPL) location platform (SLP)272.

The functions of the SMF266include session management, UE Internet protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering at the UPF262to route traffic to the proper destination, control of part of policy enforcement and QoS, and downlink data notification. The interface over which the SMF266communicates with the AMF264is referred to as the N11 interface.

Another optional aspect may include an LMF270, which may be in communication with the 5GC260to provide location assistance for UEs204. The LMF270can be implemented as a plurality of separate servers (e.g., physically separate servers, different software modules on a single server, different software modules spread across multiple physical servers, etc.), or alternately may each correspond to a single server. The LMF270can be configured to support one or more location services for UEs204that can connect to the LMF270via the core network, 5GC260, and/or via the Internet (not illustrated). The SLP272may support similar functions to the LMF270, but whereas the LMF270may communicate with the AMF264, New RAN220, and UEs204over a control plane (e.g., using interfaces and protocols intended to convey signaling messages and not voice or data), the SLP272may communicate with UEs204and external clients (not shown inFIG.2B) over a user plane (e.g., using protocols intended to carry voice and/or data like the transmission control protocol (TCP) and/or IP).

FIGS.3A,3B, and3Cillustrate several exemplary components (represented by corresponding blocks) that may be incorporated into a UE302(which may correspond to any of the UEs described herein), a base station304(which may correspond to any of the base stations described herein), and a network entity306(which may correspond to or embody any of the network functions described herein, including the location server230, the LMF270, and the SLP272) to support the file transmission operations as taught herein. It will be appreciated that these components may be implemented in different types of apparatuses in different implementations (e.g., in an ASIC, in a system-on-chip (SoC), etc.). The illustrated components may also be incorporated into other apparatuses in a communication system. For example, other apparatuses in a system may include components similar to those described to provide similar functionality. Also, a given apparatus may contain one or more of the components. For example, an apparatus may include multiple transceiver components that enable the apparatus to operate on multiple carriers and/or communicate via different technologies.

The UE302and the base station304each include wireless wide area network (WWAN) transceiver310and350, respectively, configured to communicate via one or more wireless communication networks (not shown), such as an NR network, an LTE network, a GSM network, and/or the like. The WWAN transceivers310and350may be connected to one or more antennas316and356, respectively, for communicating with other network nodes, such as other UEs, access points, base stations (e.g., ng-eNBs, gNBs), etc., via at least one designated RAT (e.g., NR, LTE, GSM, etc.) over a wireless communication medium of interest (e.g., some set of time/frequency resources in a particular frequency spectrum). The WWAN transceivers310and350may be variously configured for transmitting and encoding signals318and358(e.g., messages, indications, information, and so on), respectively, and, conversely, for receiving and decoding signals318and358(e.g., messages, indications, information, pilots, and so on), respectively, in accordance with the designated RAT. Specifically, the transceivers310and350include one or more transmitters314and354, respectively, for transmitting and encoding signals318and358, respectively, and one or more receivers312and352, respectively, for receiving and decoding signals318and358, respectively.

The UE302and the base station304also include, at least in some cases, wireless local area network (WLAN) transceivers320and360, respectively. The WLAN transceivers320and360may be connected to one or more antennas326and366, 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 wireless communication medium of interest. The WLAN transceivers320and360may be variously configured for transmitting and encoding signals328and368(e.g., messages, indications, information, and so on), respectively, and, conversely, for receiving and decoding signals328and368(e.g., messages, indications, information, pilots, and so on), respectively, in accordance with the designated RAT. Specifically, the transceivers320and360include one or more transmitters324and364, respectively, for transmitting and encoding signals328and368, respectively, and one or more receivers322and362, respectively, for receiving and decoding signals328and368, respectively.

Transceiver circuitry including at least one transmitter and at least one receiver may comprise an integrated device (e.g., embodied as a transmitter circuit and a receiver circuit of a single communication device) in some implementations, may comprise a separate transmitter device and a separate receiver device in some implementations, or may be embodied in other ways in other implementations. In an aspect, a transmitter may include or be coupled to a plurality of antennas (e.g., antennas316,326,356,366), such as an antenna array, that permits the respective apparatus to perform transmit “beamforming,” as described herein. Similarly, a receiver may include or be coupled to a plurality of antennas (e.g., antennas316,326,356,366), such as an antenna array, that permits the respective apparatus to perform receive beamforming, as described herein. In an aspect, the transmitter and receiver may share the same plurality of antennas (e.g., antennas316,326,356,366), such that the respective apparatus can only receive or transmit at a given time, not both at the same time. A wireless communication device (e.g., one or both of the transceivers310and320) of the UE302and/or a wireless communication device (e.g., one or both of the transceivers350and360) of the base station304may also comprise a network listen module (NLM) or the like for performing various measurements.

The UE302and the base station304also include, at least in some cases, satellite positioning systems (SPS) receivers330and370. The SPS receivers330and370may be connected to one or more antennas336and376, respectively, for receiving SPS signals338and378, respectively, such as global positioning system (GPS) signals, global navigation satellite system (GLONASS) signals, Galileo signals, Beidou signals, Indian Regional Navigation Satellite System (NAVIC), Quasi-Zenith Satellite System (QZSS), etc. The SPS receivers330and370may comprise any suitable hardware and/or software for receiving and processing SPS signals338and378, respectively. The SPS receivers330and370request information and operations as appropriate from the other systems, and performs calculations necessary to determine positions of the UE302and the base station304using measurements obtained by any suitable SPS algorithm.

The base station304and the network entity306each include at least one network interfaces380and390for communicating with other network entities. For example, the network interfaces380and390(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 interfaces380and390may be implemented as transceivers configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving messages, parameters, and/or other types of information.

The UE302, the base station304, and the network entity306also include other components that may be used in conjunction with the operations as disclosed herein. The UE302includes processor circuitry implementing a processing system332for providing functionality relating to, for example, positioning operations, and for providing other processing functionality. The base station304includes a processing system384for providing functionality relating to, for example, positioning operations as disclosed herein, and for providing other processing functionality. The network entity306includes a processing system394for providing functionality relating to, for example, positioning operations as disclosed herein, and for providing other processing functionality. In an aspect, the processing systems332,384, and394may include, for example, one or more general purpose processors, multi-core processors, ASICs, digital signal processors (DSPs), field programmable gate arrays (FPGA), or other programmable logic devices or processing circuitry.

The UE302, the base station304, and the network entity306include memory circuitry implementing memory components340,386, and396(e.g., each including a memory device), respectively, for maintaining information (e.g., information indicative of reserved resources, thresholds, parameters, and so on). In some cases, the UE302, the base station304, and the network entity306may include angle-based measurement managers342,388, and398, respectively. The angle-based measurement managers342,388, and398may be hardware circuits that are part of or coupled to the processing systems332,384, and394, respectively, that, when executed, cause the UE302, the base station304, and the network entity306to perform the functionality described herein. In other aspects, the angle-based measurement managers342,388, and398may be external to the processing systems332,384, and394(e.g., part of a modem processing system, integrated with another processing system, etc.). Alternatively, the angle-based measurement managers342,388, and398may be memory modules (as shown inFIGS.3A-C) stored in the memory components340,386, and396, respectively, that, when executed by the processing systems332,384, and394(or a modem processing system, another processing system, etc.), cause the UE302, the base station304, and the network entity306to perform the functionality described herein.

The UE302may include one or more sensors344coupled to the processing system332to provide movement and/or orientation information that is independent of motion data derived from signals received by the WWAN transceiver310, the WLAN transceiver320, and/or the SPS receiver330. By way of example, the sensor(s)344may include an accelerometer (e.g., a micro-electrical mechanical systems (MEMS) device), a gyroscope, a geomagnetic sensor (e.g., a compass), an altimeter (e.g., a barometric pressure altimeter), and/or any other type of movement detection sensor. Moreover, the sensor(s)344may include a plurality of different types of devices and combine their outputs in order to provide motion information. For example, the sensor(s)344may use a combination of a multi-axis accelerometer and orientation sensors to provide the ability to compute positions in 2D and/or 3D coordinate systems.

In addition, the UE302includes a user interface346for providing indications (e.g., audible and/or visual indications) to a user and/or for receiving user input (e.g., upon user actuation of a sensing device such as a keypad, a touch screen, a microphone, and so on). Although not shown, the base station304and the network entity306may also include user interfaces.

Referring to the processing system384in more detail, in the downlink, IP packets from the network entity306may be provided to the processing system384. The processing system384may 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 system384may provide RRC layer functionality associated with broadcasting of system information (e.g., master information block (MIB), system information blocks (SIBs)), 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 associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with the transfer of upper layer packet data units (PDUs), error correction through 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 associated with mapping between logical channels and transport channels, scheduling information reporting, error correction, priority handling, and logical channel prioritization.

The transmitter354and the receiver352may implement Layer-1 functionality associated with various signal processing functions. Layer-1, which includes a physical (PHY) layer, may include error detection on the transport channels, forward error correction (FEC) coding/decoding of the transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The transmitter354handles 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 split into parallel streams. Each stream may then be mapped to an orthogonal frequency division multiplexing (OFDM) subcarrier, multiplexed with a reference signal (e.g., pilot) in the time and/or frequency domain, and then combined together using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM symbol stream is spatially precoded to produce multiple spatial streams. Channel estimates from a channel estimator may be used to determine the coding and modulation scheme, as well as for spatial processing. The channel estimate may be derived from a reference signal and/or channel condition feedback transmitted by the UE302. Each spatial stream may then be provided to one or more different antennas356. The transmitter354may modulate an RF carrier with a respective spatial stream for transmission.

At the UE302, the receiver312receives a signal through its respective antenna(s)316. The receiver312recovers information modulated onto an RF carrier and provides the information to the processing system332. The transmitter314and the receiver312implement Layer-1 functionality associated with various signal processing functions. The receiver312may perform spatial processing on the information to recover any spatial streams destined for the UE302. If multiple spatial streams are destined for the UE302, they may be combined by the receiver312into a single OFDM symbol stream. The receiver312then 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, and the reference signal, are recovered and demodulated by determining the most likely signal constellation points transmitted by the base station304. These soft decisions may be based on channel estimates computed by a channel estimator. The soft decisions are then decoded and de-interleaved to recover the data and control signals that were originally transmitted by the base station304on the physical channel. The data and control signals are then provided to the processing system332, which implements Layer-3 and Layer-2 functionality.

In the UL, the processing system332provides 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 system332is also responsible for error detection.

Similar to the functionality described in connection with the DL transmission by the base station304, the processing system332provides RRC layer functionality associated with system information (e.g., MIB, SIBs) acquisition, RRC connections, and measurement reporting; PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification); RLC layer functionality associated with the transfer of upper layer PDUs, error correction through ARQ, concatenation, segmentation, and reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with 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 through hybrid automatic repeat request (HARD), priority handling, and logical channel prioritization.

Channel estimates derived by the channel estimator from a reference signal or feedback transmitted by the base station304may be used by the transmitter314to select the appropriate coding and modulation schemes, and to facilitate spatial processing. The spatial streams generated by the transmitter314may be provided to different antenna(s)316. The transmitter314may modulate an RF carrier with a respective spatial stream for transmission.

The UL transmission is processed at the base station304in a manner similar to that described in connection with the receiver function at the UE302. The receiver352receives a signal through its respective antenna(s)356. The receiver352recovers information modulated onto an RF carrier and provides the information to the processing system384.

In the UL, the processing system384provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE302. IP packets from the processing system384may be provided to the core network. The processing system384is also responsible for error detection.

For convenience, the UE302, the base station304, and/or the network entity306are shown inFIGS.3A-Cas including various components that may be configured according to the various examples described herein. It will be appreciated, however, that the illustrated blocks may have different functionality in different designs.

The various components of the UE302, the base station304, and the network entity306may communicate with each other over data buses334,382, and392, respectively. The components ofFIGS.3A-Cmay be implemented in various ways. In some implementations, the components ofFIGS.3A-Cmay be implemented in one or more circuits such as, for example, one or more processors and/or one or more ASICs (which may each include one or more processors). Here, 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 blocks310to346may be implemented by processor and memory component(s) of the UE302(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). Similarly, some or all of the functionality represented by blocks350to388may be implemented by processor and memory component(s) of the base station304(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). Also, some or all of the functionality represented by blocks390to398may be implemented by processor and memory component(s) of the network entity306(e.g., by execution of appropriate code and/or by appropriate configuration of processor components). For simplicity, various operations, acts, and/or functions are described herein as being performed “by a UE,” “by a base station,” “by a positioning entity,” etc. However, as will be appreciated, such operations, acts, and/or functions may actually be performed by specific components or combinations of components of the UE, base station, positioning entity, etc., such as the processing systems332,384,394, the transceivers310,320,350, and360, the memory components340,386, and396, the angle-based measurement managers342,388, and398, etc.

NR enables several new positioning techniques in addition to legacy 4G/LTE solutions, such as angle-based positioning techniques (e.g., angle-of-arrival (AoA), angle-of-departure (AoD), zenith angle of arrival (ZoA), and zenith angle of departure (ZoD) positioning techniques), UE-based positioning techniques, and multi-cell round-trip-time (RTT) positioning techniques (also referred to as “multi-RTT”). Referring to downlink AoD positioning techniques specifically, these techniques can reuse the same downlink reference signals used for timing-based downlink-only positioning techniques, such as observed time difference of arrival (OTDOA) in LTE and downlink time difference of arrival (DL-TDOA) in NR. Such reference signals may include PRS, NRS, CRS, TRS, CSI-RS, PSS, SSS, SSBs, etc.

At a high level, to perform a DL-AoD positioning procedure, a base station (“gNB” in NR) transmits reference signals to UEs in its coverage area by beam sweeping in FR2. A UE measures some, or all, of the beams and reports the signal strength (e.g., RSRP) of each beam to the base station. The base station estimates the AoD to the UE based on the UE's signal strength report and reports the AoD to a positioning entity. The positioning entity may be located at the UE, the base station, or a location server (e.g., location server230, LMF270, SLP272). The positioning entity estimates the UE's location based on the AoD reported by the base station. In some cases, there may be multiple involved base stations per UE, and each base station can report the estimated AoD to the positioning entity. The positioning entity can then further refine the estimated location of the UE based on the additional AoDs.

FIG.4is a diagram400illustrating an exemplary base station (BS)402(which may correspond to any of the base stations described herein) in communication with an exemplary UE404(which may correspond to any of the UEs described herein), according to various aspects of the disclosure. Referring toFIG.4, the base station402may transmit a beamformed signal to the UE404on one or more transmit beams402a,402b,402c,402d,402e,402f,402g,402h, each having a beam identifier that can be used by the UE404to identify the respective beam. Where the base station402is beamforming towards the UE404with a single array of antennas (e.g., a single TRP), the base station402may perform a “beam sweep” by transmitting first beam402a, then beam402b, and so on until lastly transmitting beam402h. Alternatively, the base station402may transmit beams402a-402hin some pattern, such as beam402a, then beam402h, then beam402b, then beam402g, and so on. Where the base station402is beamforming towards the UE404using multiple arrays of antennas (e.g., multiple TRPs), each antenna array may perform a beam sweep of a subset of the beams402a-402h. Alternatively, each of beams402a-402hmay correspond to a single antenna or antenna array.

The UE404may receive the beamformed signal from the base station402on one or more receive beams404a,404b,404c,404d. Note that for simplicity, the beams illustrated inFIG.4represent either transmit beams or receive beams, depending on which of the base station402and the UE404is transmitting and which is receiving. Thus, the UE404may also transmit a beamformed signal to the base station402on one or more of the beams404a-404d, and the base station402may receive the beamformed signal from the UE404on one or more of the beams402a-402h.

In an aspect, the base station402and the UE404may perform beam training to align the transmit and receive beams of the base station402and the UE404. For example, depending on environmental conditions and other factors, the base station402and the UE404may determine that the best transmit and receive beams are402dand404b, respectively, or beams402eand404c, respectively. The direction of the best transmit beam for the base station402may or may not be the same as the direction of the best receive beam, and likewise, the direction of the best receive beam for the UE404may or may not be the same as the direction of the best transmit beam. Note, however, that aligning the transmit and receive beams is not necessary to perform an AoD positioning procedure.

To perform an AoD positioning procedure, the base station402may transmit reference signals (e.g., PRS, NRS, CRS, TRS, CSI-RS, PSS, SSS, etc.) to the UE404on one or more of beams402a-402h, with each beam having a different weight. The different weights of the beams will result in different received signal strengths (e.g., RSRP, RSRQ, SINR, etc.) at the UE404. Further, the channel impulse response will be smaller for transmit beams that are further from the actual line of sight (LOS) path410between the base station402and the UE404than for transmit beams that are closer to the LOS path410. Likewise, the received signal strength will be lower for transmit beams that are further from the LOS path410than for transmit beams that are closer to the LOS path410.

In the example ofFIG.4, if the base station402transmits reference signals to the UE404on beams402c,402d,402e, then transmit beam402dis best aligned with the LOS path410, while transmit beams402cand402eare not. As such, beam402dwill have a stronger channel impulse response and higher received signal strength at the UE404than beams402cand402e. The UE404can report the channel impulse response and received signal strength of each measured transmit beam402c,402d,402eto the base station402, or alternatively, the identity of the transmit beam having the strongest channel impulse response and highest received signal strength (beam402din the example ofFIG.4). In either case, the base station402can estimate the angle from itself to the UE404as the AoD of the transmit beam having the highest received signal strength and strongest channel impulse response at the UE404, here, transmit beam402d.

In one aspect of AoD-based positioning, where there is only one involved base station402, the base station402and the UE404can perform an RTT procedure (as discussed below with reference toFIG.5) to determine the distance between the base station402and the UE404. Thus, the base station402(or location server or other positioning entity) can determine both the direction to the UE404(using AoD positioning) and the distance to the UE404(using RTT positioning) to estimate the location of the UE404. Note that the AoD of the transmit beam having the highest received signal strength and strongest channel impulse response does not necessarily lie along the LOS path410, as shown inFIG.4. However, for AoD-based positioning purposes, it is assumed to do so.

In another aspect of AoD-based positioning, where there are multiple involved base stations402, each base station402reports the determined AoD to the UE404to the positioning entity (e.g., a location server, the serving base station402, the UE404). The positioning entity receives multiple such AoDs from a plurality of involved base stations402(or other geographically separated transmission points) for the UE404. With this information, and knowledge of the base stations'402geographic locations, the positioning entity can estimate a location of the UE404as the intersection of the received AoDs. There should be at least three involved base stations402for a two-dimensional (2D) location solution, but as will be appreciated, the more base stations402that are involved in the positioning procedure, the more accurate the estimated location of the UE404will be.

A UE and at least three base stations (or other transmission points) may also perform an

RTT positioning procedure to determine a location estimate of the UE. In a network-centric RTT estimation, the serving base station instructs the UE to, or notifies the UE that it may, scan for/receive the RTT measurement signals from two or more neighboring base stations (and typically the serving base station, as at least three base stations are needed).

FIG.5illustrates an exemplary wireless communications system500according to aspects of the disclosure. In the example ofFIG.5, a UE504(which may correspond to any of the UEs described herein) is attempting to calculate an estimate of its location, or assist another positioning entity (e.g., a serving base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its location. The UE504may communicate wirelessly with a base station (BS)502(e.g., any of the base stations described herein) using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets.

To support location estimates, the base station502may broadcast reference signals (e.g., PRS, NRS, CRS, TRS, CSI-RS, SSB, PSS, SSS, etc.) to UEs504in its coverage area to enable a UE504to measure characteristics of such reference signals. For example, the UE504may measure the time of arrival (ToA) and signal strength (e.g., RSRP) of specific reference signals transmitted by the base station502in order to perform RTT and/or DL-AoD positioning methods with the base station502. Note that although described as the UE504measuring characteristics of reference signals from the base station502, the UE504may measure reference signals from one of multiple cells or TRPs supported by the base station502.

The distance510between the UE504and the base station502can be determined using an RTT positioning procedure. Specifically, as is known in the art, the RTT of RF signals exchanged between the UE504and the base station502can be used to calculate a distance510that defines a radius around the base station502. The location of the UE504is assumed to lie on that radius with some amount of uncertainty. To further refine the estimated location of the UE504, the base station502and the UE504can also perform an AoD positioning procedure (as described above with reference toFIG.4) to determine the angle between the base station502and the UE504. Specifically, the UE504may determine and report the identity of the downlink transmit beam512that provides the highest signal strength and/or strongest channel impulse response for the reference signals received from the base station502, as discussed above with reference toFIG.4.

The results of the RTT and DL-AoD positioning procedures, or the measurements taken during these procedures, are forwarded to the positioning entity, which may be the UE504, the base station502, the serving base station (if not base station502), or a location server (e.g., location server230, LMF270, SLP272). In order to determine the location (e.g., in x-y or x-y-z coordinates) of the UE504, the positioning entity also needs to know the location of the base station502. Where the UE504determines its location, the location of the base station502may be provided to the UE504by the base station502or a location server with knowledge of the base station's502location (e.g., location server230, LMF270, SLP272). Otherwise, the location of the base station502should be known to the base station502or the location server.

Once the RTT and AoD positioning procedures have been performed, the positioning entity can solve for the location of the UE504using the angle to the UE504(from the AoD positioning procedure), the distance to the UE504(from the RTT positioning procedure), and the known location of the base station502. Where only the measurements from the RTT and AoD positioning procedures were reported, the positioning entity first calculates the distance and angle between the base station502and the UE504, and then calculates the location of the UE504using those results.

FIG.6is a diagram600showing exemplary timings of RTT measurement signals exchanged between a base station602(which may correspond to any of the base stations described herein) and a UE604(which may correspond to any of the UEs described herein), according to aspects of the disclosure. In the example ofFIG.6, the base station602sends an RTT measurement signal610(e.g., PRS, NRS, CRS, CSI-RS, etc.) to the UE604at time T1. There is a transmission delay of TBS,Txbetween the time the base station's602baseband (“BB”) generates the RTT measurement signal610and the antenna (“Ant”) transmits the RTT measurement signal610. The RTT measurement signal610has some propagation delay TPropas it travels from the base station602to the UE604.

Upon reception of the RTT measurement signal610at the UE604, there is a delay of TUE,Rxbetween the time the UE's604antenna receives/detects the RTT measurement signal610and the time the baseband processes the RTT measurement signal610at time T2(considered as the ToA of the RTT measurement signal610at the UE604). After some UE processing time TRx→Tx612, the UE604transmits an RTT response signal620at time T3. There is a transmission delay of TUE,Txbetween the time the UE's604baseband generates the RTT response signal620and the antenna transmits the RTT response signal620.

After the propagation delay TProp, the base station's602antenna receives/detects the RTT response signal620. There is a reception delay of TBS,Rxbetween the time the antenna receives/detects the RTT response signal620and the time the baseband processes the RTT response signal620at time T4(considered as the ToA of the RTT response signal620at the base station602).

The RTT response signal620may explicitly include the difference between time T3and time T2(i.e., TRx→Tx612). Alternatively, it may be derived from the timing advance (TA), i.e., the relative uplink/downlink frame timing and specification location of uplink reference signals. Note that the TA is usually the RTT between the base station and the UE, or double the propagation time in one direction. Using this measurement and the difference between time T4and time T1(i.e., TTx→Rx622), the base station602can calculate the distance to the UE604as:

d=12⁢c⁢(TTx→Rx-TRx→Tx)=12⁢c⁢(T4-T1)-12⁢c⁢(T3-T2)
where c is the speed of light.

Generally, the UE604calibrates its RF front end (RFFE) group delays and compensates for them so that the RTT report reflects the delay from its antennas. The base station602subtracts the calibrated RFFE group delays to determine the final distance between the base station602and the UE604.

The base station602and/or the UE604may report the RTTs to the location server (or other positioning entity) to enable the location server to estimate the location of the UE604based on the RTT and the known location of the base station602. As described above with reference toFIG.5, to provide a more accurate estimate of the UE's604location, the location server can combine the results of an AoD positioning procedure performed between the base station602and the UE604with the results of the RTT positioning procedure. Thus, the location server can determine both the direction to the UE604from the base station602(using AoD positioning) and the distances to the UE604from the base stations602(using RTT positioning) to better estimate the location of the UE604.

FIG.7illustrates an exemplary UL-AoA positioning procedure, according to aspects of the disclosure. In the example ofFIG.7, a base station702(e.g., any of the base stations described herein) receives one or more reference signals (e.g., UL-PRS, SRS, DMRS, etc.) from a UE704(e.g., any of the UEs described herein) on a plurality of uplink receive beams710. The base station702determines the angle of the best receive beams710used to receive the one or more reference signals from the UE704as the AoA from itself to the UE704. Specifically, each of the receive beams710will result in a different received signal strength (e.g., RSRP, RSRQ, SINR, etc.) of the one or more reference signals at the base station702. Further, the channel impulse response of the one or more reference signals will be smaller for receive beams710that are further from the actual LOS path between the base station702and the UE704than for receive beams710that are closer to the LOS path. Likewise, the received signal strength will be lower for receive beams710that are further from the LOS path than for receive beams710that are closer to the LOS path. As such, the base station702identifies the receive beam710that results in the highest received signal strength and the strongest channel impulse response, and estimates the angle from itself to the UE704as the AoA of that receive beam710. Note that as with AoD-based positioning, the AoA of the receive beam710resulting in the highest received signal strength and strongest channel impulse response does not necessarily lie along the LOS path. However, for AoA-based positioning purposes, it is assumed to do so.

The base station702can also estimate the distance between itself and the UE704by performing an RTT positioning procedure with the UE704or from the timing advance for the UE704. As noted above, the timing advance is typically the RTT between a base station and a UE, or double the propagation time in one direction, and therefore, can be used to estimate the distance between the base station702and the UE704the same as an actual RTT procedure.

Where the UE704is estimating its location (i.e., the UE is the positioning entity), it needs to obtain the geographic location of the base station702. The UE704may obtain the location from, for example, the base station702itself or a location server (e.g., location server230, LMF270, SLP272). With the knowledge of the distance to the base station702(based on the RTT or timing advance), the angle between the base station702and the UE704(based on the AoA of the best receive beam710), and the known geographic location of the base station702, the UE704can estimate its location.

Alternatively, where a positioning entity, such as the base station702or a location server, is estimating the location of the UE704, the base station702reports the AoA of the receive beam710resulting in the highest received signal strength and strongest channel impulse response of the reference signals received from the UE704, or all received signal strengths and channel impulse responses for all receive beams710(which allows the positioning entity to determine the best receive beam710). The base station702may additionally report the distance to the UE704. The positioning entity can then estimate the location of the UE704based on the UE's704distance to the base station702, the AoA of the identified receive beam710, and the known geographic location of the base station702.

A location estimate (e.g., for a UE504) may be referred to by other names, such as a position estimate, location, position, position fix, fix, or the like. A position estimate may be geodetic and comprise coordinates (e.g., latitude, longitude, and possibly altitude) or may be civic and comprise a street address, postal address, or some other verbal description of a location. A location estimate may further be defined relative to some other known location or defined in absolute terms (e.g., using latitude, longitude, and possibly altitude). A location estimate may include an expected error or uncertainty (e.g., by including an area or volume within which the location is expected to be included with some specified or default level of confidence). The means of obtaining a location estimate may be referred to generically as “positioning,” “locating,” or “position fixing.” A particular solution for obtaining a location estimate may be referred to as a “location solution.” A particular method for obtaining a location estimate as part of a location solution may be referred to as, for example, a “location method” or as a “positioning method.”

When a base station or a UE reports measured/estimated/derived/computed angle values (e.g., AoD, AoA) to the positioning entity (e.g., the serving base station, location server230, LMF270, SLP272), it can report the angle values in either a local coordinate system (LCS) or a global coordinate system (GCS). A coordinate system is defined by the x, y, z axes, the spherical angles and the spherical unit vectors, as shown inFIG.8.FIG.8illustrates the definition of spherical angles and spherical unit vectors in a Cartesian coordinate system800, according to aspects of the disclosure. InFIG.8, θ is the zenith angle and ϕ is the azimuth angle in the Cartesian coordinate system800. Further, {circumflex over (n)} is the given direction, and {circumflex over (θ)} and {circumflex over (ϕ)} are the spherical basis vectors. Note that θ=0 points to the zenith and θ=90° points to the horizon. The field component in the direction of {circumflex over (θ)} is given by Fθand the field component in the direction of {circumflex over (ϕ)} is given by Fϕ.

A GCS is defined for a system comprising multiple base stations and UEs. An array antenna for a base station or a UE can be defined in an LCS. A GCS has an absolute reference frame (e.g., in terms of absolute latitude and longitude), whereas an LCS has a relative reference frame (e.g., relative to a vehicle, a base station, an antenna array, etc.). An LCS is used as a reference to define the vector far-field, that is pattern and polarization, of each antenna element in an array. It is assumed that the far-field is known in the LCS by formulae. The placement of an antenna array within the GCS is defined by the translation between the GCS and the LCS for the antenna array. The orientation of the antenna array with respect to the GCS is defined in general by a sequence of rotations (described in 3GPP Technical Specification (TS) 38.900, which is publicly available and which is incorporated by reference herein in its entirety). Since this orientation is in general different from the GCS orientation, it is necessary to map the vector fields of the array elements from the LCS to the GCS. This mapping depends on the orientation of the array and is given by the equations in 3GPP TS 38.900. Note that any arbitrary mechanical orientation of the array can be achieved by rotating the LCS with respect to the GCS.

InFIGS.9A and9B, a GCS with coordinates (x, y, z, θ, ϕ) and unit vectors ({circumflex over (θ)}, {circumflex over (ϕ)}), and an LCS with “primed” coordinates (x′, y′, z′, θ′, ϕ′) and “primed” unit vectors ({circumflex over (θ)}′, {circumflex over (ϕ)}′), are defined with a common origin.FIG.9Aillustrates the sequence of rotations that relate the GCS coordinates (x, y, z) and the LCS coordinates (), according to aspects of the disclosure. More specifically,FIG.9Aillustrates an arbitrary three-dimensional (3D) rotation of the LCS with respect to the GCS given by the angles α, β, γ. The set of angles α, β, γ can also be termed as the orientation of the antenna array with respect to the GCS. Any arbitrary 3D rotation can be specified by at most three elemental rotations, and following the framework ofFIG.9A, a series of rotations about the z, {dot over (y)}, and {umlaut over (x)} axes are assumed, in that order. The dotted and double-dotted marks indicate that the rotations are intrinsic, which means that they are the result of one (·) or two (··) intermediate rotations. In other words, the {dot over (y)} axis is the original y axis after the first rotation about the z axis, and the {umlaut over (x)} axis is the original x axis after the first rotation about the z axis and the second rotation about the {dot over (y)} axis.

A first rotation of α about z sets the antenna bearing angle (i.e., the sector pointing direction for a base station antenna element). The second rotation of β about {dot over (y)} sets the antenna downtilt angle. Finally, the third rotation of γ about {umlaut over (x)} sets the antenna slant angle. The orientation of the x, y, and z axes after all three rotations can be denoted as., and. These triple-dotted axes represent the final orientation of the LCS, and for notational purposes, are denoted as the x′, y′, and z′ axes (local or “primed” coordinate system). Note that the transformation from an LCS to a GCS depends only on the angles α, β, γ. The angle α is called the bearing angle, β is called the downtilt angle, and γ is called the slant angle.

FIG.9Billustrates the definition of spherical coordinates and unit vectors in both the

GCS and LCS, according to aspects of the disclosure.FIG.9Bshows the coordinate direction and unit vectors of the GCS coordinates (x, y, z) and the LCS coordinates (x′, y′, z′). Note that the vector fields of the antenna array elements are defined in the LCS.

As noted above, when a base station or a UE reports angle values (e.g., AoD, AoA) to the positioning entity, it reports the angle values in either its LCS or the GCS of the network. There are benefits of reporting measurements in an LCS, as well as benefits of reporting measurements in a GCS. A reason to use the GCS is that it is already supported in LTE systems (e.g., for AoA-based positioning, as described above with reference toFIG.7). In addition, the entity performing the measurement(s) (which are always performed in the measuring entity's LCS) is responsible for transforming the measurement to the GCS. Further, using the GCS may facilitate easier UE-based positioning, assisted by DL-AoD or UL-AoA measurements at the base station, since the UE would simply need to be forwarded the GCS-based angles and the formulae to perform the transformation(s) from its own LCS to the GCS.

As a reason to use an LCS to report angle values, the entity reporting the angle measurements may not be aware of its own orientation, or have a way to transform its LCS to the GCS, and therefore, the entity can only report measurements in its LCS. Such an entity may be, for example, a base station without a base station almanac (BSA) indicating, for example, its antenna tilt and/or rotation, or a UE that is not aware of its orientation because, for example, it does not have a gyroscope, an accelerometer, and/or a magnetometer.

Due to the benefits of reporting measurements in the GCS in some cases and in an LCS in other cases, the present disclosure provides techniques in which both options are permitted and the choice of which is used is configured according to the particular situation. For example, signaling between a base station and a location server (e.g., location server230, LMF270, SLP272), or between a UE and the location server, can be used to choose between GCS-based or LCS-based angle measurement reporting.

For example, a base station and a location server may communicate over an NR positioning protocol type A (NRPPa) session or an LTE positioning protocol type A (LPPa) session. In an aspect, if the location server requests the base station to provide measurements in a specific coordinate system, the location server can include an “LCSorGCSReport” field in the MeasurementQuantitiesValue message of an NRPPa session. Or, if the base station reports measurements in the coordinate system it has chosen, it can add an “LCSorGCSReport” field to the MeasuredResultsValue message of the NRPPa session. The LCSorGCSReport value could take one of two values, ‘0’ or ‘1’ with the meaning of these bits (e.g., ‘1’=GCS and ‘0’=LCS or vice versa) specified in the applicable standard or negotiated between the base station and the location server. Additionally, the LCSorGCSReport field could be optional, and whenever it is present, it is interpreted as one of the two values (i.e., LCS or GCS).

A UE and a location server may communicate over an LTE positioning protocol (LPP) session (or NR equivalent). If the UE reports the angle measurements to the location server, the UE can include an LCSorGCSReport field in an LPP message, similar to the NRPPa messaging between the base station and the location server. Alternatively, if the location server directs the UE regarding which coordinate system to use, it may include an LCSorGCSReport field in an LPP message, similar to the NRPPa messaging between the base station and the location server.

In a first configuration disclosed herein, the angle reporting entity (e.g., a base station or a UE) can report angle measurements to the location server in its LCS, and in a second configuration, the reporting entity can report angle measurements to the location server in the GCS of the network. Referring to the first configuration, if the reporting entity is a UE, the UE can report angle measurements (e.g., DL-AoA, DL-ZoA, UL-AoD, UL-ZoD) in its LCS to the location server over LPP signaling. This configuration may be chosen when, for example, the UE is not able to determine its orientation (e.g., due to not having a gyroscope, an accelerometer, and/or a magnetometer), and therefore, can only send LCS-based angle measurements to the location server. Because the UE may not know its orientation, it should provide additional information to the location server to assist the location server in converting the angle measurements reported in the UE's LCS to GCS angle measurements.

As a first option for such assistance information, the UE may provide an indication of which measurements in the measurement report were taken with the same UE orientation. As a second option, the UE may indicate, or the location server may assume, that all the measurements within a given measurement report were taken with the same UE orientation. Alternatively or additionally, the UE may timestamp each angle measurement and, additionally, provide the time(s) at which its orientation changed. With that information, the location server can, upon determining the UE's orientation(s) in the GCS during the measurement period, associate the timestamped angle measurements with the correct orientation.

Alternatively or additionally, the location server may determine the UE's orientation from other sources outside of the cellular system. For example, it could use reporting from other applications, such as a navigation application, to determine the orientation of the UE. Alternatively or additionally, the location server could make certain assumptions and blindly (e.g., based on previously available positioning of the UE) estimate probabilities of a new location of the UE for different hypothesis of the orientation of the UE. Knowing that at least the orientation has not changed would be helpful to perform such blind estimation of both the orientation and location of the UE by exploiting the fact that the measurements need to be consistent when the orientation has not changed.

As a third option, the UE may know that its orientation has changed, even if it is not able to determine its precise orientation. In that case, the UE may report that its orientation changed during the measurement period, and, optionally, between which of the reported measurements. As a fourth option, the UE may be able to not only detect that its orientation has changed, but may also be able to measure the change. The UE may not, however, be able to measure its absolute orientation (e.g., if the UE has a gyroscope and an accelerometer but not a magnetometer). In this case, the UE could report the detected change in orientation along with the angle measurements.

In an aspect, the UE may send separate signaling to the location server regarding the UE's orientation (assuming that the UE has sensors that were able to measure its orientation) to enable the location server to convert the UE's LCS to the GCS and execute the positioning algorithm. This signaling could use a different protocol other than LPP, such as application layer messaging or out-of-band signaling (e.g., a RAT-independent procedure). It could also be implementation-based, outside of cellular communication standards.

Referring to the second configuration, a UE can report angle measurements (e.g., DL-AoA, DL-ZoA, UL-AoD, UL-ZoD) to the location server over LPP signaling using the GCS. This configuration may be chosen where the UE is able to determine its absolute orientation relative to the GCS. In this configuration, the location server receives the angle report and executes the positioning algorithm without needing to convert the angle measurements from the UE's LCS to the GCS.

Where the angle reporting entity is a base station, for the first configuration described herein (in which the reporting entity reports angle measurements in its LCS), the base station reports angle measurements (e.g., DL-AoD, DL-ZoD, UL-AoA, UL-AoZ) to the location server over NRPPa or LPPa signaling using the base station's LCS. To convert the base station's LCS to the GCS, the location server can simply look up the orientation of the base station in the base station's BSA and convert the LCS angle measurements to GCS angle measurements and execute the positioning algorithm.

In some cases, however, the orientation of the base station may not be known. In that case, the location server may be able to use AoA/AoD measurements from multiple base stations and “subtract out” or estimate the base station's unknown orientation. More specifically, a base station with unknown orientation can transmit beamformed signals (as described above with reference toFIG.4) that are received by base stations with known orientation. The receiving base stations, or the location server, can estimate the relative direction and orientation of the antenna array of the transmitting base station based on the AoA of the received transmit beams and the associated signal strengths, similar to the techniques described above with reference toFIG.4. The location server can then estimate the orientation of the base station with unknown orientation based on the information from the base stations with known orientation. Note that this technique may not be possible for UEs due to the changing beam patterns of UEs.

Referring now to the second configuration described herein (in which the reporting entity reports angle measurements in the GCS), as for the UE, the base station reports angle measurements (e.g., DL-AoD, DL-ZoD, UL-AoA, UL-AoZ) to the location server over NRPPa/LPPa signaling using the GCS. The location server receives the angle report and executes the positioning algorithm without needing to convert the angle measurements from the base station's LCS to the GCS.

The angle reporting entity may be configured/triggered to report angle measurements in either its LCS (the first configuration) or the GCS (the second configuration) in various ways.FIG.10illustrates an exemplary method1000for reporting angle measurements in either an LCS or a GCS, according to aspects of the disclosure. At1010, as a first optional operation, the location server1002(which may correspond to location server230, LMF270, or SLP272) can configure the angle reporting entity1004(any of the base stations or UEs described herein) to report angle measurements in either the reporting entity's LCS or the GCS of the network. In an aspect, the location server1002only needs to configure the reporting entity1004in this way when an angle-based positioning procedure is being performed. The location server1002can send the configuration signal during an LPP session (for a UE) or an NRPPa or LPPa session (for a base station) with the reporting entity1004.

In an aspect, the location server1002may configure the reporting entity1004to use the GCS, but the reporting entity1004may be unable to determine the angle measurements in the GCS. In that case, the reporting entity1004uses its LCS and notifies the location server1002that the measurements are in its LCS. This indication can be included with the angle measurement report (at1040), or it can be a separate signal. For example, the reporting entity1004can send the indication to the location server1002during the LPP session (for a UE) or the NRPPa/LPPa session (for a base station).

As a second optional operation, at1020, the angle reporting entity1004can choose for itself whether to report the angle measurements in the LCS or the GCS (at1040). The reporting entity1004can then autonomously inform the location server1002of whether the angle measurements are in the LCS or the GCS. This indication can be included with the angle measurement report (at1040), or it can be a separate signal (not shown). For example, the reporting entity1004can send the indication to the location server1002over the LPP session (for a UE) or the NRPPa/LPPa session (for a base station). Whether the reporting entity1004chooses to use its LCS or the GCS may depend on whether it has knowledge of its orientation (e.g., orientation sensors at the UE, or a BSA at the base station). The reporting entity1004need only report this parameter when it is performing an angle-based positioning procedure.

Operations1010and1020are optional because only one need be performed. That is, either the location server1002will configure the reporting entity1004to report angle measurements in the LCS or GCS (1010), or the reporting entity1004determines the coordinate system in which to report measurements (1020).

At1030, if the reporting entity1004is a UE, the reporting entity1004measures the DL-AoA, DL-ZoA, UL-AoD, and/or UL-ZoD of one or more reference signals received from a base station or other transmission point. If the reporting entity1004is a base station or other transmission point, then at1030, the reporting entity1004measures the DL-AoD, DL-ZoD, UL-AoA, and/or UL-AoZ of one or more reference signals transmitted by a UE. At1040, the reporting entity1004sends a measurement report to the location server1002containing the angle measurements. The report may include an indication of whether the angle measurements are in the LCS or GCS, as described above.

FIG.11illustrates an exemplary method1100of wireless communication, according to aspects of the disclosure. In an aspect, the method1100may be performed by a base station, such as any of the base stations described herein.

At1110, the base station performs one or more angle-based measurements in a first coordinate system. In an aspect, operation1110may be performed by WWAN transceiver350, processing system384, memory component386, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation.

At1120, the base station determines whether to report, to a positioning entity (e.g., the UE being measured, a serving base station, location server230, LMF270, SLP272), the one or more angle-based measurements in an LCS or a GCS. In an aspect, operation1120may be performed by WWAN transceiver350, processing system384, memory component386, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation.

At1130, the UE reports the one or more angle-based measurements to the positioning entity in the LCS or the GCS based on the determination. In an aspect, operation1130may be performed by WWAN transceiver350, processing system384, memory component386, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation.

FIG.12illustrates an exemplary method1200of wireless communication, according to aspects of the disclosure. In an aspect, the method1200may be performed by a positioning entity, such as a UE, a serving base station, location server230, LMF270, or SLP272.

At1210, the positioning entity receives, from a base station, one or more angle-based measurements in an LCS of the base station or a GCS. In an aspect, if the positioning entity is located at a UE, operation1210may be performed by WWAN transceiver310, processing system332, memory component340, and/or angle-based measurement manager342of the UE302, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a base station, operation1210may be performed by WWAN transceiver350, processing system384, memory385, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a location server, operation1210may be performed by network interface(s)390, processing system394, memory396, and/or angle-based measurement manager398of the network entity306, any or all of which may be considered means for performing this operation.

At1220, the positioning entity determines whether the one or more angle-based measurements are in the LCS or the GCS. The positioning entity may have configured the base station to report the one or more angle-based measurements in the LCS or the GCS, and/or the positioning entity may have received an indication that the one or more angle-based measurements are in the LCS of the GCS, as described above with reference toFIG.10. In an aspect, if the positioning entity is located at a UE, operation1220may be performed by WWAN transceiver310, processing system332, memory component340, and/or angle-based measurement manager342of the UE302, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a base station, operation1220may be performed by WWAN transceiver350, processing system384, memory385, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a location server, operation1220may be performed by network interface(s)390, processing system394, memory396, and/or angle-based measurement manager398of the network entity306, any or all of which may be considered means for performing this operation.

At1230, the positioning entity processes the one or more angle-based measurements based on the determination. In an aspect, if the positioning entity is located at a UE, operation1230may be performed by WWAN transceiver310, processing system332, memory component340, and/or angle-based measurement manager342of the UE302, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a base station, operation1230may be performed by WWAN transceiver350, processing system384, memory385, and/or angle-based measurement manager388of the base station304, any or all of which may be considered means for performing this operation. Where the positioning entity is located at a location server, operation1230may be performed by network interface(s)390, processing system394, memory396, and/or angle-based measurement manager398of the network entity306, any or all of which may be considered means for performing this operation.

Those of skill in the art will appreciate that information and signals 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 above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Further, those of skill in the art will appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the aspects disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, 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 upon 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.

The various illustrative logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with 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, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

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. A software module may reside in 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., UE). In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

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. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can 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 a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

While the foregoing disclosure shows illustrative aspects of the disclosure, it should be noted that various changes and modifications could be made herein without departing from the scope of the disclosure as defined by the appended claims. The functions, steps and/or actions of the method claims in accordance with the aspects of the disclosure described herein need not be performed in any particular order. Furthermore, although elements of the disclosure may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.