Patent ID: 12216212

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 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 New Radio (NR) Node B (also referred to as a gNB or gNodeB), etc. In addition, 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 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 and a neighbor base station whose reference RF 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.

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.

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 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 next generation core (NGC)) through backhaul links122, and through the core network170to one or more location servers172. 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/NGC) 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 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 (PCID), a virtual cell identifier (VCID)) 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 the logical communication entity and the base station that supports it, depending on the context. 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 neighboring macro cell base station102geographic coverage areas110may 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′ may have a coverage area110′ that substantially overlaps with the 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 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 for 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 a reference downlink reference signal (e.g., synchronization signal block (SSB)) from a base station. The UE can then form a transmit beam for sending an uplink reference signal (e.g., sounding reference signal (SRS)) 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 S Cells for the UE164and the mmW base station180may support one or more SCells for the UE164.

The wireless communications system100may further include one or more satellites112of a non-terrestrial network (NTN). Due to the wide service coverage capabilities and reduced vulnerability of space/airborne vehicles (e.g., satellite(s)112) to physical attacks and natural disasters, NTNs may be used to provide 5G NR service in un-served areas that cannot be covered by terrestrial 5G networks (e.g., isolated/remote areas, on board aircrafts or vessels, etc.), and in under-served areas (e.g., suburban/rural areas) to upgrade the performance of limited terrestrial networks in a cost effective manner. With reference toFIG.1, a satellite112is in communication with a UE114outside the coverage area of a base station102(representing a UE in an area that is not served by a terrestrial 5G network) and with a UE116inside the coverage area of a base station102(representing a UE that is under-served by the terrestrial 5G network). Thus, satellite112may act as a serving base station to UE114and as a primary cell or a secondary cell to UE116, depending on the service provided to UE116by base station102.

NTNs may also be used to reinforce 5G service reliability by providing service continuity for machine-to-machine (M2M) and/or IoT devices, or for passengers on board moving platforms (e.g., passenger vehicles such as aircraft, ships, high speed trains, buses, etc.), or ensuring service availability anywhere, especially for critical communications. NTNs can also enable 5G network scalability by providing efficient multicast/broadcast resources for data delivery towards the network edges or even the UE.

An NTN includes one or more gateways (illustrated as gateway118) between the space/airborne platforms (e.g., satellite(s)112) and the core network (e.g., core network170). The radio link between a UE (e.g., UE114,116) and a space/airborne platform (e.g., a satellite112) is referred to as a “service link” (e.g., service links124). In addition, a UE may also support a radio link with a terrestrial based RAN, as illustrated by communication link120between base station102and UE116. A radio link between a gateway (e.g., gateway118) and a space/airborne platform (e.g., a satellite112) is referred to as a “feeder link” (e.g., feeder link126).

Note that althoughFIG.1illustrates a satellite112as the exemplary space/airborne platform, as will be appreciated, the satellite112may be any type of manned or unmanned airborn or space vehicle capable of providing 5G service to UEs in its coverage area. Also, althoughFIG.1only illustrates a single satellite112and a single gateway118, as will be appreciated, this is merely exemplary, and there may be any number of satellites112connected to any number of gateways118. Further details regarding NTNs can be found in the Third Generation Partnership Project (3GPP) Technical Specification (TS)38.811, which is publicly available and incorporated by reference herein in its entirety.

According to various aspects,FIG.2Aillustrates an example wireless network structure200. For example, an NGC210(also referred to as a “5GC”) 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 NGC210and specifically to the control plane functions214and user plane functions212. In an additional configuration, an eNB224may also be connected to the NGC210via NG-C215to the control plane functions214and NG-U213to user plane functions212. Further, 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 eNBs224and gNBs222. Either gNB222or 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 NGC210to 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, NGC210, 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.

FIG.2Aalso illustrates a satellite112as part of the example wireless network structure200. The satellite112may be the same as illustrated and described with reference toFIG.1. The UE204may communicate with the satellite112over a service link124, as described above with reference toFIG.1. Like the eNB224and the gNB222, the satellite112may communicate with the control plane functions214and the user plane functions212over the control plane interface (NG-C)215and the user plane interface (NG-U)213, respectively. However, the satellite112communicates with the control plane functions214and the user plane functions212via a gateway (e.g., gateway118, not shown) between the satellite112and the NGC210. In some cases, the satellite112may also communicate with the eNB224and the gNB222via a wireless backhaul link (not shown), similar to the communication between the eNB224and the gNB222over backhaul link223.

According to various aspects,FIG.2Billustrates another example wireless network structure250. For example, an NGC260(also referred to as a “5GC”) can be viewed functionally as control plane functions, provided by an access and mobility management function (AMF)/user plane function (UPF)264, and user plane functions, provided by a session management function (SMF)262, which operate cooperatively to form the core network (i.e., NGC260). User plane interface263and control plane interface265connect the eNB224to the NGC260and specifically to SMF262and AMF/UPF264, respectively. In an additional configuration, a gNB222may also be connected to the NGC260via control plane interface265to AMF/UPF264and user plane interface263to SMF262. Further, eNB224may directly communicate with gNB222via the backhaul connection223, with or without gNB direct connectivity to the NGC260. In some configurations, the New RAN220may only have one or more gNBs222, while other configurations include one or more of both eNBs224and gNBs222. Either gNB222or eNB224may communicate with UEs204(e.g., any of the UEs depicted inFIG.1). The base stations of the New RAN220communicate with the AMF-side of the AMF/UPF264over the N2 interface and the UPF-side of the AMF/UPF264over the N3 interface.

LikeFIG.2A,FIG.2Balso illustrates a satellite112as part of the example wireless network structure250. The satellite112may be the same as illustrated and described with reference toFIGS.1and2A. The UE204may communicate with the satellite112over a service link124, as described above with reference toFIG.1. The satellite112may communicate with a gateway118over a feeder link126, and the gateway118may communicate with the NGC260over a backhaul link122. Like the eNB224and the gNB222, the satellite112may communicate with the AMF/UPF264and the SMF262over a control plane interface and a user plane interface, respectively (not shown). However, unlike the eNB224and the gNB222, the satellite112communicates with the AMF/UPF264and the SMF262via the gateway118.

There are different types of satellite communication architectures, two of which are the “processing payload” and “bentpipe” types. In the case of the processing payload type, the entirety, or at least part of, the eNB/gNB functionality is carried out at the satellite112. This case is illustrated inFIGS.2A and2Bby the satellite112being included in the New RAN220. In the case of the bentpipe type, the satellite112acts as a relay, and the entirety of the eNB/gNB functionality is performed at the gateway118. In this case, the gateway118may be included in the New RAN220. The present disclosure is not limited to either type of satellite communication architecture.

The functions of the AMF include registration management, connection management, reachability management, mobility management, lawful interception, transport for session management (SM) messages between the UE204and the SMF262, 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 AMF also interacts with the 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 AMF retrieves the security material from the AUSF. The functions of the AMF also 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 AMF also includes location services management for regulatory services, transport for location services messages between the UE204and the location management function (LMF)270, as well as 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 AMF also supports functionalities for non-3GPP access networks.

Functions of the UPF include 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 the 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.

The functions of the SMF262include session management, UE Internet protocol (IP) address allocation and management, selection and control of user plane functions, configuration of traffic steering at the UPF to route traffic to the proper destination, control of part of policy enforcement and QoS, and downlink data notification. The interface over which the SMF262communicates with the AMF-side of the AMF/UPF264is referred to as the N11 interface.

Another optional aspect may include a LMF270, which may be in communication with the NGC260to 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, NGC260, and/or via the Internet (not illustrated).

FIGS.3A,3B, and3Cillustrate several sample components (represented by corresponding blocks) that may be incorporated into a UE302(which may correspond to any of the UEs described herein), a space/airborne vehicle304(which may correspond to any of the space/airborne vehicles described herein, such as satellite112), and a network entity306(which may correspond to or embody any of the network functions described herein, including the location server230and the LMF270) 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 UE302includes a wireless wide area network (WWAN) transceiver310configured to communicate via one or more wireless communication networks (not shown), such as a 5G NR network, an LTE network, a GSM network, and/or the like. Similarly, the space/airborne vehicle304includes a WWAN transceiver350configured to communicate via one or more wireless communication networks (not shown), such as a 5G NR network. 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., eNBs, gNBs), space/airborne vehicles, 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 UE302also includes, at least in some cases, a wireless local area network (WLAN) transceiver320. The WLAN transceiver320may be connected to one or more antennas326for 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 transceiver320may be variously configured for transmitting and encoding signals328(e.g., messages, indications, information, and so on), and, conversely, for receiving and decoding signals328(e.g., messages, indications, information, pilots, and so on), in accordance with the designated RAT. Specifically, the WLAN transceiver320includes one or more transmitters324for transmitting and encoding signals328, and one or more receivers322for receiving and decoding signals328.

The space/airborne vehicle304includes at least one network interface370, which may be one or more transceivers. The network interface(s)370may be connected to one or more antennas376for wirelessly communicating with a gateway (e.g., gateway118) and/or other space/airborne vehicles over a wireless communication medium of interest. The network interface(s)370may be variously configured for transmitting and encoding signals378(e.g., messages, indications, information, and so on), and, conversely, for receiving and decoding signals378(e.g., messages, indications, information, pilots, and so on), in accordance with the designated RAT. Specifically, the network interface(s)370includes one or more transmitters374for transmitting and encoding signals378, and one or more receivers372for receiving and decoding signals378.

Transceiver circuitry including a transmitter and a 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., antennas316,326,356,376), 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., antennas316,326,356,376), 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., antennas316,326,356,376), 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 transceivers310and320and/or350) of the apparatuses302and/or304may also comprise a network listen module (NLM) or the like for performing various measurements.

The UE302also includes, at least in some cases, a global positioning systems (GPS) receiver330. The GPS receiver330may be connected to one or more antennas336for receiving GPS signals338. The GPS receiver330may comprise any suitable hardware and/or software for receiving and processing GPS signals338. The GPS receiver330requests information and operations as appropriate from the other systems, and performs calculations necessary to determine the UE's302position using measurements obtained by any suitable GPS algorithm.

The network entity306includes at least one network interface390for communicating with other network entities. For example, the network interface390(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 interface390may be implemented as one or more transceivers configured to support wire-based or wireless signal communication. This communication may involve, for example, sending and receiving messages, parameters, or other types of information.

The apparatuses302,304, and306also 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 measurements of NTN reference signals as disclosed herein and for providing other processing functionality. The space/airborne vehicle304includes a processing system384for providing functionality relating to, for example, transmitting reference signals as disclosed herein and for providing other processing functionality. The network entity306includes a processing system394for providing functionality relating to, for example, configuring NTN reference signals for positioning measurement 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 apparatuses302,304, and306include 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 apparatuses302,304, and306may include positioning modules342,388, and398, respectively. The positioning modules342,388, and398may be hardware circuits that are part of or coupled to the processing systems332,384, and394, respectively, that, when executed, cause the apparatuses302,304, and306to perform the functionality described herein. Alternatively, the positioning modules342,388, 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, cause the apparatuses302,304, and306to 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 GPS 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 a keypad, a touch screen, a microphone, and so on). Although not shown, the apparatuses304and306may 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 system384via the network interface(s)370. 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 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 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 space/airborne vehicle304. 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 space/airborne vehicle304on 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 space/airborne vehicle304, 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 HARQ, priority handling, and logical channel prioritization.

Channel estimates derived by the channel estimator from a reference signal or feedback transmitted by the space/airborne vehicle304may 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 space/airborne vehicle304in 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 apparatuses302,304, and/or306are 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 apparatuses302,304, and306may 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 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 space/airborne vehicle304(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 positioning modules342,388, and398, etc.

FIG.4is a diagram400illustrating an example of a downlink frame structure, according to aspects of the disclosure. Other wireless communications technologies may have a different frame structures and/or different channels.

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

LTE supports a single numerology (subcarrier spacing, symbol length, etc.). In contrast NR may support multiple numerologies, for example, subcarrier spacing of 15 kHz, 30 kHz, 60 kHz, 120 kHz and 204 kHz or greater may be available. Table 1 provided below lists some various parameters for different NR numerologies.

TABLE 1Max. nominalSubcarrierSymbolsystem BWspacingslotduration(MHz) with(kHz)Symbols/slotslots/subframeslots/frame(ms)(μs)4K FFT size1514110166.75030142200.533.310060144400.2516.7100120148800.1258.3340020414161600.06254.17800

In the example ofFIG.4, a numerology of 15 kHz is used. Thus, in the time domain, a frame (e.g., 10 ms) is divided into 10 equally sized subframes of 1 ms each, and each subframe includes one time slot. InFIG.4, time is represented horizontally (e.g., on the X axis) with time increasing from left to right, while frequency is represented vertically (e.g., on the Y axis) with frequency increasing (or decreasing) from bottom to top.

A resource grid may be used to represent time slots, each time slot including one or more time concurrent resource blocks (RBs) (also referred to as physical RBs (PRBs)) in the frequency domain. The resource grid is further divided into multiple resource elements (REs). An RE may correspond to one symbol length in the time domain and one subcarrier in the frequency domain. In the numerology ofFIG.4, for a normal cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 7 consecutive symbols (for DL, OFDM symbols; for UL, SC-FDMA symbols) in the time domain, for a total of 84 REs. For an extended cyclic prefix, an RB may contain 12 consecutive subcarriers in the frequency domain and 6 consecutive symbols in the time domain, for a total of 72 REs. The number of bits carried by each RE depends on the modulation scheme.

As illustrated inFIG.4, some of the REs (labeled “R”) carry DL reference (pilot) signals (DL-RS) to be measured by the UE for various reasons. For example, the DL-RS may include demodulation reference signals (DMRS) and/or channel state information reference signals (CSI-RS) for estimating channel conditions between the UE and the transmitter. As another example, the DL-RS may include positioning reference signals (PRS) to be measured by the UE for positioning purposes.

A collection of resource elements that are used for transmission of PRS is referred to as a “PRS resource.” The collection of resource elements can span multiple PRBs in the frequency domain and N (e.g., 1 or more) consecutive symbol(s) within a slot in the time domain. In a given OFDM symbol, a PRS resource occupies consecutive PRBs. A PRS resource is described by at least the following parameters: PRS resource identifier (ID), sequence ID, comb size-N, resource element offset in the frequency domain, starting slot and starting symbol, number of symbols per PRS resource (i.e., the duration of the PRS resource), and QCL information (e.g., QCL with other DL reference signals). Currently, one antenna port is supported. The comb size indicates the number of subcarriers in each symbol carrying PRS. For example, a comb-size of comb-4 means that every fourth subcarrier of a given symbol carries PRS.

A “PRS resource set” is a set of PRS resources used for the transmission of PRS signals, where each PRS resource has a PRS resource ID. In addition, the PRS resources in a PRS resource set are associated with the same TRP. A PRS resource set is identified by a PRS resource set ID and may be associated with a particular TRP (identified by a cell ID) transmitted by an antenna panel of a base station. A PRS resource ID in a PRS resource set is associated with a single beam (and/or beam ID) transmitted from a single TRP (where a TRP may transmit one or more beams). That is, each PRS resource of a PRS resource set may be transmitted on a different beam, and as such, a “PRS resource,” or simply “resource,” can also be referred to as a “beam.” Note that this does not have any implications on whether the TRPs and the beams on which PRS are transmitted are known to the UE.

A “PRS instance” or “PRS occasion” is one instance of a periodically repeated time window (e.g., a group of one or more consecutive slots) where PRS are expected to be transmitted. A PRS occasion may also be referred to as a “PRS positioning occasion,” a “PRS positioning instance, a “positioning occasion,” “a positioning instance,” or simply an “occasion” or “instance.”

FIG.5illustrates an exemplary PRS configuration500for a cell supported by a wireless node (such as a base station102or a satellite112). Again, PRS transmission for LTE is assumed inFIG.5, although the same or similar aspects of PRS transmission to those shown in and described forFIG.5may apply to NR and/or other wireless technologies.FIG.5shows how PRS positioning occasions are determined by a system frame number (SFN), a cell specific subframe offset (APRs)552, and the PRS periodicity (TPRS)520. Typically, the cell specific PRS subframe configuration is defined by a “PRS Configuration Index” IPRSincluded in observed time difference of arrival (OTDOA) assistance data. The PRS periodicity (TPRS)520and the cell specific subframe offset (ΔPRS) are defined based on the PRS configuration index IPRS, as illustrated in Table 2 below.

TABLE 2PRS configurationPRS periodicityPRS subframe offsetIndex IPRSTPRS(subframes)ΔPRS(subframes)0-159160IPRS160-479320IPRS− 160480-1119640IPRS− 4801120-23991280IPRS− 11202400-24045IPRS− 24002405-241410IPRS− 24052415-243420IPRS− 24152435-247440IPRS− 24352475-255480IPRS− 24752555-4095Reserved

A PRS configuration is defined with reference to the system frame number (SFN) of a cell that transmits PRS. PRS instances, for the first subframe of the NPRSdownlink subframes comprising a first PRS positioning occasion, may satisfy:
(10×ηf+[ns/2]−ΔPRS)modTPRS=0,
where nfis the SFN with 0≤nf≤1023, nsis the slot number within the radio frame defined by nfwith 0≤ns≤19, TPRSis the PRS periodicity520, and APRs is the cell-specific subframe offset552.

As shown inFIG.5, the cell specific subframe offset APRs552may be defined in terms of the number of subframes transmitted starting from system frame number 0 (Slot ‘Number 0’, marked as slot550) to the start of the first (subsequent) PRS positioning occasion. In the example inFIG.5, the number of consecutive positioning subframes (NPRS) in each of the consecutive PRS positioning occasions518a,518b, and518cequals 4. That is, each shaded block representing PRS positioning occasions518a,518b, and518crepresents four subframes.

In some aspects, when a UE receives a PRS configuration index IPRSin the OTDOA assistance data for a particular cell, the UE may determine the PRS periodicity TPRS520and PRS subframe offset APRS using Table 1. The UE may then determine the radio frame, subframe and slot when a PRS is scheduled in the cell (e.g., using equation (1)). The OTDOA assistance data may be determined by, for example, the location server170, and includes assistance data for a reference cell, and a number of neighbor cells supported by various wireless nodes.

Typically, PRS occasions from all cells in a network that use the same frequency are aligned in time and may have a fixed known time offset (e.g., cell-specific subframe offset552) relative to other cells in the network that use a different frequency. In SFN-synchronous networks all wireless nodes (e.g., base stations102) may be aligned on both frame boundary and system frame number. Therefore, in SFN-synchronous networks all cells supported by the various wireless nodes may use the same PRS configuration index for any particular frequency of PRS transmission. On the other hand, in SFN-asynchronous networks, the various wireless nodes may be aligned on a frame boundary, but not system frame number. Thus, in SFN-asynchronous networks the PRS configuration index for each cell may be configured separately by the network so that PRS occasions align in time.

A UE may determine the timing of the PRS occasions of the reference and neighbor cells for OTDOA positioning, if the UE104can obtain the cell timing (e.g., SFN) of at least one of the cells, e.g., the reference cell or a serving cell. The timing of the other cells may then be derived by the UE104based, for example, on the assumption that PRS occasions from different cells overlap.

For LTE systems, the sequence of subframes used to transmit PRS (e.g., for OTDOA positioning) may be characterized and defined by a number of parameters, as described previously, comprising: (i) a reserved block of bandwidth (BW), (ii) the configuration index IPRS, (iii) the duration NPRS, (iv) an optional muting pattern; and (v) a muting sequence periodicity TREPthat can be implicitly included as part of the muting pattern in (iv) when present. In some cases, with a fairly low PRS duty cycle, NPRS=1, TPRS=160 subframes (equivalent to 160 ms), and BW=1.4, 3, 5, 10, 15, or 20 MHz. To increase the PRS duty cycle, the NPRSvalue can be increased to six (i.e., NPRS=6) and the bandwidth (BW) value can be increased to the system bandwidth (i.e., BW=LTE system bandwidth in the case of LTE). An expanded PRS with a larger NPRS(e.g., greater than six) and/or a shorter TPRS(e.g., less than 160 ms), up to the full duty cycle (i.e., NPRS=TPRS), may also be used in later versions of the LTE positioning protocol (LPP). A directional PRS may be configured as just described and may, for example, use a low PRS duty cycle (e.g., NPRS=1, TPRS=160 subframes) or a high duty cycle.

FIG.6illustrates a DL-OTDOA positioning procedure in an exemplary wireless communications system600, according to various aspects of the disclosure. In the example ofFIG.6, a UE604, which may correspond to any of the UEs described herein, is attempting to calculate an estimate of its position, or assist another entity (e.g., a base station or core network component, another UE, a location server, a third party application, etc.) to calculate an estimate of its position. The UE604may communicate wirelessly with a plurality of satellites602-1,602-2, and602-3(collectively, satellites602, and which may correspond to any of the satellites described herein), using RF signals and standardized protocols for the modulation of the RF signals and the exchange of information packets. By extracting different types of information from the exchanged RF signals, and utilizing the layout of the wireless communications system600(e.g., the base stations locations, geometry, etc.), the UE604may determine its position, or assist in the determination of its position, in a predefined reference coordinate system. In an aspect, the UE604may specify its position using a two-dimensional (2D) coordinate system; however, the aspects disclosed herein are not so limited, and may also be applicable to determining positions using a three-dimensional (3D) coordinate system, if the extra dimension is desired. Additionally, whileFIG.6illustrates one UE604and three satellites602, as will be appreciated, there may be more UEs604and more or fewer satellites602.

To support position estimates, the satellites602may be configured to broadcast positioning reference signals (e.g., PRS) to UEs604in their coverage area to enable a UE604to measure characteristics of such reference signals. For example, the OTDOA positioning method is a multilateration method in which the UE604measures the time difference, known as a reference signal time difference (RSTD), between specific reference signals (e.g., PRS) transmitted by different pairs of satellites602and either reports these time differences to a location server, such as the location server230or LMF270, or computes a location estimate itself from these time differences.

Generally, RSTDs are measured between a reference cell (e.g., a cell supported by satellite602-1in the example ofFIG.6) and one or more neighbor cells (e.g., cells supported by satellites602-2and602-3in the example ofFIG.6). The reference cell remains the same for all RSTDs measured by the UE604for any single positioning use of OTDOA and would typically correspond to the serving cell for the UE604or another nearby cell with good signal strength at the UE604. In an aspect, the neighbor cells would normally be cells supported by satellites602different from the satellite602for the reference cell, and may have good or poor signal strength at the UE604. The location computation can be based on the measured time differences (e.g., RSTDs) and knowledge of the network nodes' locations and relative transmission timing (e.g., regarding whether network nodes are accurately synchronized or whether each network node transmits with some known time difference relative to other network nodes).

To assist positioning operations, a location server (e.g., location server230, LMF270) may provide OTDOA assistance data to the UE604for the reference cell and the neighbor cells relative to the reference cell. For example, the assistance data may include identifiers (e.g., PCI, VCI, cell global identity (CGI), etc.) for each cell of a set of cells that the UE604is expected to measure (here, cells supported by the satellites602). The assistance data may also provide the center channel frequency of each cell, various reference signal configuration parameters (e.g., the number of consecutive positioning subframes, periodicity of positioning subframes, muting sequence, frequency hopping sequence, reference signal identifier (ID), reference signal bandwidth), and/or other cell related parameters applicable to OTDOA. The OTDOA assistance data may indicate the serving cell for the UE604as the reference cell.

In some cases, OTDOA assistance data may also include “expected RSTD” parameters, which provide the UE604with information about the RSTD values the UE604is expected to measure at its current location between the reference cell and each neighbor cell, together with an uncertainty of the expected RSTD parameter. The expected RSTD, together with the associated uncertainty, may define a search window for the UE604within which the UE604is expected to measure the RSTD value. OTDOA assistance information may also include reference signal configuration information parameters, which allow a UE604to determine when a reference signal positioning occasion occurs on signals received from various neighbor cells relative to reference signal positioning occasions for the reference cell, and to determine the reference signal sequence transmitted from various cells in order to measure a signal time of arrival (ToA) or RSTD.

In an aspect, while the location server (e.g., location server230, LMF270) may send the assistance data to the UE604, alternatively, the assistance data can originate directly from the satellites602themselves (e.g., in periodically broadcasted overhead messages, etc.). Alternatively, the UE604can detect neighbor satellites itself without the use of assistance data.

The UE604(e.g., based in part on the assistance data, if provided) can measure and (optionally) report the RSTDs between reference signals received from pairs of satellites602. Using the RSTD measurements, the known absolute or relative transmission timing of each satellite602, and the known position(s) of the reference and neighboring satellites602, the network (e.g., location server230/LMF270) or the UE604may estimate a position of the UE604. More particularly, the RSTD for a neighbor network node “k” relative to a reference network node “Ref” may be given as (ToAk-ToARef), where the ToA values may be measured modulo one subframe duration (1 ms) to remove the effects of measuring different subframes at different times. In the example ofFIG.6, the measured time differences between the reference cell of satellite602-1and the cells of neighboring satellites602-2and602-3are represented as τ2-τ1and τ3-τ1, where τ1, τ2, and τ3represent the ToA of a reference signal from the transmitting antenna(s) of satellites602-1,602-2, and602-3, respectively. The UE604may then convert the ToA measurements for different network nodes to RSTD measurements and (optionally) send them to the location server230/LMF270. Using (i) the RSTD measurements, (ii) the known absolute or relative transmission timing of each network node, (iii) the known position(s) of physical TRPs for the reference and neighboring satellites602, and/or (iv) directional reference signal characteristics such as a direction of transmission, the UE's604position may be determined (either by the UE604or the location server230/LMF270).

Still referring toFIG.6, when the UE604obtains a location estimate using OTDOA measured time differences, the necessary additional data (e.g., the network nodes' locations and relative transmission timing) may be provided to the UE604by a location server (e.g., location server230, LMF270). In some implementations, a location estimate for the UE604may be obtained (e.g., by the UE604itself or by the location server230/LMF270) from OTDOA measured time differences and from other measurements made by the UE604(e.g., measurements of signal timing from GPS or other GNSS satellites). In these implementations, known as hybrid positioning, the OTDOA measurements may contribute towards obtaining the UE's604location estimate but may not wholly determine the location estimate.

Location information for a UE can aid in addressing several of the key challenges in 5G, complementary to existing and planned technological developments. These challenges include an increase in traffic and number of devices, robustness for mission critical services, and a reduction in total energy consumption and latency. Knowledge of the location of a UE is beneficial for more efficient paging, scheduling, beamforming, multicasting, etc.

One method of determining the location of a UE was described above with reference toFIG.6. As described above, a UE can measure the difference between the ToAs of positioning reference signals (e.g., PRS) from pairs of satellites (i.e., the OTDOA), and these measurements, along with the known locations of the transmitting satellites, can be used to determine the position of the UE using a hyperbolic multilateral algorithm. However, in existing LTE and NR PRS designs, a PRS sequence repeats every 10 ms (e.g., PRS periodicity (TPRS)=10 ms). More specifically, a PRS sequence generator is initiated by a number that is the function of the slot number within a frame, and the duration of the frame is 10 ms. Thus, every 10 ms, a PRS sequence repeats.

For terrestrial networks, this 10 ms repetition pattern is not an issue, as in order to detect PRS from a terrestrial transmitter (e.g., a base station), a UE will always be well within a 5 ms propagation delay of the transmitter. For an NTN, however, there are scenarios where the propagation delay between a satellite and a UE can exceed 10 ms. This can create an ambiguity in measuring the ToA of a PRS from the satellite. For example, if there is a 14 ms propagation delay between the satellite and the UE and the PRS sequence repeats every 10 ms, the UE will not know if the propagation delay of the PRS is 4 ms or 14 ms. That is, the UE may detect the ToA of the PRS from the satellite as occurring at 4 ms into a PRS sequence, but it will not know that the measured PRS was actually propagating from the satellite to the UE for an entire 10 ms PRS sequence before the start of the PRS sequence in which the PRS was measured.

This becomes more significant when measuring the ToAs of PRS from multiple satellites, as illustrated inFIG.7.FIG.7is a diagram700illustrating the ambiguity of measuring PRS from different satellites where the PRS periodicity is shorter than the propagation time between the satellites and a receiver (e.g., a UE). As illustrated inFIG.7, a satellite A702transmits a first PRS sequence706that repeats every 10 ms, and a satellite B712transmits a second PRS sequence716that repeats every 10 ms. Satellite A702and satellite B712start transmission of their respective PRS sequences at the same time. However, due to the propagation delay between the satellites and the receiver, the PRS transmissions of the respective PRS sequences arrive at the receiver at different times. Note that althoughFIG.7only illustrates two PRS transmissions (i.e., PRS instance/PRS occasion) per PRS sequence, as will be appreciated, there may be more PRS transmissions per sequence than the two illustrated.

To measure the OTDOA of PRS received from satellite A702and satellite B712, the receiver measures the ToA of the first PRS transmission of the PRS sequence from each satellite. In the example ofFIG.7, the receiver receives the first PRS transmission of the PRS sequence716from satellite B7124 ms before it receives the first PRS transmission of the PRS sequence706from satellite A702. Thus, the actual OTDOA between the PRS of satellite A702and the PRS of satellite B712is 4 ms. However, the PRS sequence716from satellite B712begins to repeat during the measured PRS sequence706from satellite A702. As such, the UE does not know if the first PRS transmission of PRS sequence716is the PRS to be measured, or if the first PRS transmission of the next PRS sequence is the PRS to be measured.

Accordingly, the present disclosure provides techniques to adjust the repetition duration of PRS transmissions in NTNs to eliminate the ambiguity caused by the conventional PRS repetition duration. As a first technique, the repetition duration of PRS sequence generation is extended to be longer than the conventional 10 ms. In an aspect, the repetition duration (or sequence duration or PRS periodicity) may be at least twice the largest differential delay between a receiver (e.g., a UE) and any two satellites. The largest, or maximum, differential delay is the largest amount of time that would ever be expected to occur between the reception/measurement of any PRS transmissions of two simultaneously (i.e., beginning during the same radio frame) transmitted PRS sequences from any two satellites. That is, if a first satellite and a second satellite transmit respective PRS sequences S1 and S2 over the same two or more radio frames, the maximum differential delay would be the maximum amount of time that could occur between reception/measurement at the receiver of any PRS transmission of sequence S1 and reception/measurement at the receiver of any PRS transmission of sequence S2.

As a result of making the repetition duration at least twice as long as the maximum differential delay, when two PRS sequences are transmitted from two satellites during the same radio frames, the OTDOA between the PRS of the satellites can be unambiguously determined using one or more PRS transmissions of each PRS sequence, since the PRS sequences will not repeat during the possible propagation time between the satellites and the receiver due to the increased length of the PRS sequences. That is, unlike the example illustrated inFIG.7, neither of the PRS sequences will start repeating within the possible propagation time between the satellites and the receiver because the PRS sequences are at least twice as long as the maximum differential delay. Thus, the OTDOA can be determined using the RSTD between any PRS transmission of a first PRS sequence and any PRS transmission of a second PRS sequence.

A second technique described herein is to define the initial state of the PRS sequence generator (cinit) as a function of the frame number or the PRS burst index. This guarantees that the repetition duration will be larger than the current 10 ms periodicity. Note that a PRS burst includes PRS transmissions within the same PRS periodicity. That is, a PRS burst is one or more PRS transmissions within a PRS periodicity. Thus, a PRS burst is another term for PRS sequence.

The following provides an example PRS sequence generator function that can support up to a 20 ms OTDOA between the PRS of two different satellites. Assume the following original PRS sequence generator function:
cinit=228·└NIDPRS/512┘+210·(7·(ns+1)+l+1)·(2·(NIDPRSmod 512)+1)+2·(NIDPRSmod 512)+NCP

Based on the above equation, a new PRS sequence generator function can be created that provides a repetition duration larger than the current 10 ms:
cinit=228·└NIDPRS/512┘+220(nrfmod 2)+210·(7·(ns+1)+l+1)·(2·(NIDPRSmod 512)+1)+2·(NIDPRSmod 512)+NCP

In the above equations, NIDPRSis the PRS identifier (ID), nsis the slot number, nrfis the frame number, and NCPindicates the CP type.

The above equations are merely exemplary. The second equation generates PRS sequences that are longer than 10 ms, here, 20 ms, because of the variable nif. Specifically, nrfmod 2 makes the equation repeat every two radio frames, or every 20 ms. The variable nrfcould also be mod 3, mod 4, etc. for repetition durations of 3, 4, etc. radio frames, respectively. Note that the additional variable in the second equation, i.e., nrf, does not have to be a variable based on the frame number. Rather, it just needs to be something that does not repeat every radio frame.

FIG.8is a diagram800illustrating an example of using the extended PRS periodicity disclosed herein. As illustrated inFIG.8, a satellite A802transmits a first PRS sequence806that repeats every 20 ms, and a satellite B812transmits a second PRS sequence816that repeats every 20 ms. The PRS sequences806and816may be generated using, for example, the PRS sequence generator function described above. Satellite A802and satellite B812start transmission of their respective PRS sequences at the same time (i.e., during the same radio frame). However, due to the propagation delay between the satellites and the receiver (e.g., a UE), the PRS transmissions (or PRS occasion/instance) of the respective PRS sequences arrive at the receiver at different times. Note that althoughFIG.8only illustrates two PRS transmissions per PRS sequence, as will be appreciated, there may be more PRS transmissions per sequence than the two illustrated.

In the example ofFIG.8, it is assumed that the maximum differential delay between the satellites A and B802and812is 10 ms. To measure the OTDOA of PRS received from satellite A802and satellite B812, the receiver measures the ToA of one or more PRS transmissions of the PRS sequence from each satellite. In the example ofFIG.8, like the example ofFIG.7, the receiver receives and measures the ToA of the first PRS transmission of the PRS sequence816from satellite B8124 ms before it receives and measures the ToA of the first PRS transmission of the PRS sequence806from satellite A802. Thus, the actual OTDOA between the PRS of satellite A802and the PRS of satellite B812is 4 ms. Also like the example ofFIG.7, the PRS sequence816from satellite B812begins to repeat during the measured PRS sequence806from satellite A802. Thus, there is a possibility that the OTDOA between the PRS of satellite A802and the PRS of satellite B812could be 16 ms (the difference between the first PRS transmission of the PRS sequence806and the first PRS transmission of the PRS sequence after the PRS sequence816). However, because the receiver knows that the maximum valid OTDOA is 10 ms, the receiver can disregard the possible OTDOA of 16 ms, since it is greater than 10 ms.

Thus, by using an extended PRS sequence duration, if a receiver (e.g., a UE) can calculate two different OTDOAs between two transmitters (e.g., satellites), as illustrated inFIG.8, the receiver can disregard whichever OTDOA has an absolute value greater than the maximum differential delay between the two transmitters. In an aspect, the receiver may receive the maximum differential delay between the two transmitters from a positioning entity (e.g., location server230, LMF270).

As a third technique disclosed herein, the network can indicate to the receiver (e.g., a UE) the repetition duration of a PRS sequence generation via higher layer configuration (e.g., RRC). Alternatively, the network can indicate the repetition duration by SSB or SIB.

As a fourth technique disclosed herein, the repetition duration of PRS sequence generation may be (1) identical for all beams of all satellites for the entire satellite communication network, (2) dependent on the location of the receiver (e.g., UE) and/or involved transmitter(s) (e.g., satellite(s)), (3) dependent on the satellite beam on which the PRS sequence is transmitted, and/or (4) dependent on the altitude of the involved transmitter(s) (satellite(s)). For example, with reference to (2), the repetition duration may be different at different latitudes of the satellite(s). As another example, with reference to (4), the repetition duration may be independently defined for low earth orbit (LEO), medium earth orbit (MEO), high earth orbit (HEO), geostationary earth orbit (GEO), etc. Note that for satellite communication, a “beam” is equivalent to a “cell” in terrestrial wireless communications.

FIG.9illustrates an exemplary method900of positioning a receiver device, according to aspects of the disclosure. The method900may be performed by the receiver device (e.g., any of the UEs described herein).

At910, the receiver device measures a ToA of a PRS transmission of a first PRS sequence transmitted by a first transmitter. The first PRS transmission of the first PRS sequence may be any PRS transmission of the first PRS sequence. In an aspect, operation910may be performed by WWAN transceiver310, processing system332, memory component340, and/or positioning module342, any or all of which may be considered means for performing this operation.

At920, the receiver device measures a ToA of a PRS transmission of a second PRS sequence transmitted by a second transmitter. The first PRS transmission of the second PRS sequence may be any PRS transmission of the second PRS sequence. In an aspect, operation920may be performed by WWAN transceiver310, processing system332, memory component340, and/or positioning module342, any or all of which may be considered means for performing this operation.

At930, the receiver device determines an OTDOA between the first PRS transmission of the first PRS sequence and the first PRS transmission of the second PRS sequence as a difference between the ToA of the PRS transmission of the first PRS sequence and the ToA of the PRS transmission of the second PRS sequence. In an aspect, operation930may be performed by WWAN transceiver310, processing system332, memory component340, and/or positioning module342, any or all of which may be considered means for performing this operation.

In an aspect, the OTDOA is less than a maximum differential delay expected between reception at the receiver device of a pair of PRS transmissions simultaneously transmitted by a pair of transmitter devices during the same radio frame. In an aspect, a repetition duration of the first PRS sequence and the second PRS sequence is greater than 10 ms and at least twice the maximum differential delay.

At940, the receiver device optionally reports the OTDOA to a positioning entity (e.g., location server230, LMF270). Operation940is optional because the positioning entity may reside on the receiver device. In an aspect, operation940may be performed by WWAN transceiver310, processing system332, memory component340, and/or positioning module342, any or all of which may be considered means for performing this operation.

FIG.10illustrates an exemplary method1000of positioning a receiver device, according to aspects of the disclosure. The method1000may be performed by a transmitter device (e.g., any of the satellites or other airborne vehicles described herein).

At1010, the transmitter device generates a first PRS sequence. In an aspect, a repetition duration of the first PRS sequence is greater than 10 ms and at least twice a maximum differential delay. The maximum differential delay is a maximum amount of time expected to occur between reception at a receiver device of a pair of PRS transmissions simultaneously transmitted by a pair of transmitter devices during the same radio frame. In an aspect, operation1010may be performed by WWAN transceiver350, processing system384, memory component386, and/or positioning module388, any or all of which may be considered means for performing this operation.

At1020, the transmitter device transmits the PRS sequence to the receiver device. In an aspect, operation1020may be performed by WWAN transceiver350, processing system384, memory component386, and/or positioning module388, 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, e.g., 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.