Location measurements in the presence of MBSFN signals

Abstract

In one example, the method comprises the steps of receiving assistance data from a location server; classifying a plurality of cell candidates in the assistance data into a first group of cell candidates and a second group of cell candidates, where the classification is based on whether the cell candidates transmit Location Reference Signal (PRS) symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes in the positioning occasion and based on a Cyclic Prefix (CP) length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; selecting one of the first group or the second group of cell candidates for measuring one or more PRSs in the positioning occasion based on one or more predetermined criteria; and measuring one or more PRSs from one of the first group or the second group of cell candidates in the positioning occasion to perform the PRS measurement.

Description

[Technical Field]

[0001] The subject matter disclosed herein relates to electronic devices, and more particularly to methods and apparatus used to support position determination for mobile devices using wireless networks. [Background technology]

[0002] Obtaining the position or location of a mobile device accessing a wireless network can be useful for many applications, including, for example, emergency calling, personal navigation, asset management, locating friends or family, etc. Existing positioning methods include methods based on measuring the timing of radio signals received from various devices, including, for example, satellite vehicles (SVs), terrestrial radio sources (e.g., base stations) in multiple-access wireless networks. Examples of such multiple-access networks include code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, etc. FDMA networks may include, for example, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, etc.

[0003] In an FDMA wireless network, radio signals may be transmitted using multiple subcarriers in different frequency bands. A base station may be allocated multiple subcarriers as available wireless resources for transmitting the radio signals. With current technology, a base station may use some, but not all, of the allocated subcarriers to transmit location measurement radio signals. Summary of the Invention [Problem to be solved by the invention]

[0004] While standardization for new fifth-generation (5G) wireless networks includes support for a variety of positioning methods, both new and existing, it is expected that problems may arise with current methods of transmitting location measurement signals, which may be transmitted along with other signals, such as signals of a Multimedia Broadcast Multicast Service Single Frequency Network (MBSFN), which may lead to inaccurate location measurements. The techniques disclosed herein address these problems by implementing techniques that improve the accuracy of detecting location measurement signals in 5G wireless networks, as well as in legacy wireless networks such as Long Term Evolution (LTE) networks. [Means for solving the problem]

[0005] According to this description, an example of a user equipment (UE) for performing location measurements in a wireless communication network comprises: a memory; a wireless communication interface; and a processing unit communicatively coupled to the memory and the wireless communication interface, wherein the processing unit is configured to receive assistance data from a location server, wherein the assistance data identifies a plurality of cell candidates using which the UE can measure one or more location reference signals (PRS) to support the UE's location measurement operations; classify the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, wherein the classification is based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes in the positioning occasion and based on a cyclic prefix (CP) length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; select one of the first group or the second group of cell candidates for measuring one or more PRSs in the positioning occasion based on one or more predetermined criteria; and measure one or more PRSs from the selected one of the first group or the second group of cell candidates in the positioning occasion to perform the PRS measurements.

[0006] According to this description, an example of a method in a UE for performing location measurements in a wireless communication network comprises receiving assistance data from a location server, the assistance data identifying a plurality of cell candidates using which the UE can measure one or more PRSs to support the UE's location measurement operations; classifying the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classification being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes in the positioning occasion and based on a CP length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; selecting one of the first group or the second group of cell candidates for measuring one or more PRSs in the positioning occasion based on one or more predetermined criteria; and measuring one or more PRSs from the selected one of the first group or the second group of cell candidates in the positioning occasion to perform the PRS measurements.

[0007] According to this description, an example of an apparatus that is part of a UE for performing location measurements in a wireless communications network comprises: means for receiving assistance data from a location server, the assistance data identifying a plurality of cell candidates using which the UE can measure one or more PRSs to support the UE's location measurement operations; means for classifying the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classification being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes in the positioning occasion and based on a CP length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; means for selecting one of the first group or the second group of cell candidates for measuring one or more PRSs in the positioning occasion based on one or more predetermined criteria; and means for measuring one or more PRSs from the selected one of the first group or the second group of cell candidates in the positioning occasion to perform the PRS measurements.

[0008] According to this description, an example of a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to receive assistance data from a location server, the assistance data identifying a plurality of cell candidates using which a UE can measure one or more location reference signals (PRS) to support the UE's location measurement operations, classify the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classification being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes in the positioning occasion and based on a cyclic prefix (CP) length of the PRS symbols being transmitted by the cell candidates in the positioning occasion, select one of the first group or the second group of cell candidates for measuring one or more PRSs in the positioning occasion based on one or more predetermined criteria, and measure one or more PRSs from the selected one of the first group or the second group of cell candidates in the positioning occasion to perform the PRS measurements.

[0009] Non-limiting and non-exhaustive aspects are described in connection with the following drawings. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram of a communication system that can utilize a 5G network to determine the location of a UE, according to an example of the present disclosure. [Figure 2] FIG. 1 is a diagram of a 5G NR positioning system, according to an example of the present disclosure. [Figure 3A] FIG. 1 illustrates an exemplary radio frame structure in a wireless communication network, in accordance with an example of the present disclosure. [Figure 3B] FIG. 1 illustrates an exemplary radio frame structure in a wireless communication network, in accordance with an example of the present disclosure. [Figure 3C] FIG. 1 illustrates an exemplary radio frame structure in a wireless communication network, in accordance with an example of the present disclosure. [Figure 3D]FIG. 1 illustrates an exemplary radio frame structure in a wireless communication network, in accordance with an example of the present disclosure. [Figure 3E] FIG. 1 illustrates an exemplary radio frame structure in a wireless communication network, in accordance with an example of the present disclosure. [Figure 4A] FIG. 1 illustrates an exemplary scenario in which a base station belonging to an MBSFN also transmits a location reference signal (PRS) signal, in accordance with an example of the present disclosure. [Figure 4B] FIG. 1 illustrates an exemplary scenario in which a base station belonging to an MBSFN also transmits a location reference signal (PRS) signal, in accordance with an example of the present disclosure. [Figure 4C] FIG. 1 illustrates an exemplary scenario in which a base station belonging to an MBSFN also transmits a location reference signal (PRS) signal, in accordance with an example of the present disclosure. [Figure 5] FIG. 1 illustrates an example location determination operation between a UE and cells within and outside an MBSFN area, according to an example of the present disclosure. [Figure 6A] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 6B] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 6C] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 6D] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 6E] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 6F] 6 illustrates example information elements supporting the example location determination operation of FIG. 5, in accordance with an example of the present disclosure. [Figure 7A] 6 illustrates example operations that are part of the example location determination operation of FIG. 5, according to an example of the present disclosure. [Figure 7B]6 illustrates example operations that are part of the example location determination operation of FIG. 5, according to an example of the present disclosure. [Figure 7C] 6 illustrates example operations that are part of the example location determination operation of FIG. 5, according to an example of the present disclosure. [Figure 8] 1 is a flow diagram illustrating a method for determining a location of a UE according to an example of the present disclosure;FIG. 2 is a flow diagram illustrating a method for locating a UE in a UE according to an example of the present disclosure;FIG. [Figure 9] 1 is an example of a UE capable of implementing the disclosed techniques. [Figure 10] 1 is an example of a base station capable of implementing the disclosed techniques. DETAILED DESCRIPTION OF THE INVENTION

[0011] According to some example implementations, like reference numbers and symbols in various drawings indicate like elements. Additionally, multiple instances of an element may be indicated by the first digit of that element followed by a hyphen and a second digit. For example, multiple instances of element 110 may be indicated as 110-1, 110-2, 110-3, etc. When referring to such an element using only the first digit, any instance of that element should be understood (e.g., element 110 in the previous example refers to elements 110-1, 110-2, and 110-3).

[0012] Several example techniques for determining the position of a user equipment (UE) are presented herein, which may be implemented in a UE (e.g., a mobile device or mobile station), a location server (LS), a base station, and / or other devices. These techniques may be utilized in a variety of applications utilizing various technologies and / or standards, including 3rd Generation Partnership Project (3GPP®), Open Mobile Alliance (OMA), Long Term Evolution (LTE), Local Positioning Protocol (LPP) and / or LPP Extensions (LPPe), Wi-Fi®, Global Navigation Satellite System (GNSS), etc.

[0013] The UE may comprise a mobile device, such as, for example, a mobile phone, a smartphone, a tablet or other mobile computer, a portable gaming device, a personal media player, a personal navigation device, a wearable device, an in-vehicle device, or other electronic device. Determining the location of a UE may be useful to the UE and / or other entities in a variety of scenarios. Many methods are already known for determining the estimated location of a UE, including methods that involve communicating measurements and / or other information between the UE and an LS.

[0014] Fifth-generation (5G) standardization includes support for positioning methods based on or similar to Observed Time Difference Of Arrival (OTDOA) used in LTE networks. Examples of positioning methods supported in 5G networks include, for example, OTDOA, uplink time of arrival (ULTOA), downlink time of arrival (DLTOA), and multi-cell round trip time (RTT). In OTDOA, a UE measures the time difference between reference signals transmitted by one or more pairs of base stations, called reference signal time difference (RSTD). The reference signals may be signals intended solely for navigation and positioning, sometimes called positioning reference signals (PRS), or may also be signals intended for timing and frequency acquisition of the serving cell, sometimes called cell-specific reference signals (CRS), tracking reference signals (TRS), channel state information reference signals (CSI-RS), primary and secondary synchronization sequences (PSS / SSS), or physical broadcast channel (PBCH) signals. The UE can measure two or more RSTDs between two or more different pairs of base stations (or at least three cells). Each pair of neighboring base stations typically includes a common reference base station. If the base station antenna positions and relative timing are known, the UE position in the horizontal direction can be obtained.

[0015] In addition to supporting positioning methods, wireless communication networks such as 3GPP and 5G networks can be used to transmit various types of data, such as communication data, multimedia data, etc. Data can be transmitted in various types of transmission operations, such as unicast operation and broadcast operation. In unicast operation, each base station is controlled to transmit a signal carrying information directed to a subscriber UE. The specificity of unicast signaling enables person-to-person services, such as voice calls, text messaging, or video calls. In broadcast operation, several base stations within a broadcast area are controlled to broadcast, in a synchronized manner, a signal carrying information that can be received and accessed by any subscriber UE within the broadcast area. The generality of broadcast operation enables improved efficiency in transmitting information of public interest, such as event-related multimedia broadcasts. One mechanism for facilitating high-bandwidth communication for multimedia has traditionally been single-frequency network (SFN) operation. In particular, Multimedia Broadcast Multicast Service (MBMS) and MBMS for LTE, also known as evolved MBMS (eMBMS), including, for example, Multimedia Broadcast Single Frequency Network (MBSFN) in the context of LTE, can utilize such SFN operation. SFN utilizes radio transmitters, such as base stations, to communicate with subscriber UEs.

[0016] In a wireless communication network, a base station may transmit a set of radio signals over a range of time intervals to form a radio frame having multiple subframes, each of which may include multiple transmission time slots. Radio signals, such as MBMS signals and PRS signals, may include a predetermined number of symbols transmitted in multiple transmission time slots within a subframe. PRS signals may be transmitted in special positioning subframes grouped into positioning occasions. The symbol duration, which determines the number of symbols in a transmission time slot, may be based on a cyclic prefix configuration, in which some symbols are duplicated to reduce inter-symbol interference (ISI) due to multipath effects. In 3GPP and 5G networks, symbols of radio signals to be transmitted over longer distances, such as MBMS signals, may include an extended cyclic prefix (ECP), which has a longer symbol duration and fewer symbols in a transmission time slot compared to a normal cyclic prefix (NCP) configuration. Other signals, such as PRS signals, may include either an ECP or an NCP within a symbol depending on the range of the signal's transmission. Symbols with different cyclic prefixes require different digital signal processing configurations to recover the symbols from the radio signal. However, due to hardware capabilities, as well as memory and power constraints, the UE can only use a single digital signal processing arrangement (ECP or NCP) to recover symbols from the wireless signal.

[0017] A base station that is part of an MBSFN can transmit both MBMS and PRS signals. A base station may transmit MBMS to support broadcast operations and may also transmit PRS to support location determination operations in a UE. In such cases, the base station may transmit PRS symbols in a radio frame that also includes MBMS symbols (hereinafter, "MBSFN subframes"). In some scenarios, during a positioning occasion, the base station may transmit PRS symbols entirely in MBSFN subframes within a radio frame, and the PRS symbols in the MBSFN subframes may include a mix of symbols with NCP and symbols with ECP. On the other hand, a cell that transmits PRS symbols with non-MBSFN subframes may transmit PRS symbols with only NCP or with the same cyclic prefix as subframe 0 of the radio frame.

[0018] With current technology, a UE always measures PRS using MBSFN cells that transmit both PRS and MBMS. If those cells transmit PRS symbols using only MBSFN subframes in a positioning occasion, the UE may employ a signal processing configuration for symbols with ECP to recover the PRS symbols and to measure PRS based on the recovered symbols in that positioning occasion. However, because PRS symbols include a mixture of NCP and ECP symbols, such a configuration may lead to errors in PRS symbol recovery, which may result in inaccurate location determination. In addition, because the UE employs a signal processing configuration for symbols with ECP to recover PRS symbols from MBSFN cells, the UE may not be able to measure PRS using other cells, such as non-MBSFN cells, that transmit PRS symbols with NCP in non-MBSFN subframes in a given positioning occasion. These cells may be more numerous than MBSFN cells. The lack of PRS measurements using other cells prevents the UE from further refining the location determination based on PRS measurements using other cells, which may further degrade the accuracy of the location determination operation.

[0019] Techniques described herein below can address these issues and improve positioning methods in wireless networks. Specifically, a mobile device, such as a user equipment, can receive assistance data from a location server. The assistance data can identify multiple cell candidates from which the UE can measure one or more location reference signals (PRS) to support the UE's location determination operations. The mobile device can classify the multiple cell candidates into a first group of cell candidates and a second group of cell candidates based on whether the cells transmit PRS symbols in MBSFN subframes within a positioning occasion and based on the CP length (ECP or NCP) of the PRS symbols being transmitted by the cells within the positioning occasion. The UE can select one of the first group or the second group of cell candidates to measure the PRS based on one or more predetermined criteria. The UE can then measure the PRS using the selected one of the first group or the second group of cell candidates to perform PRS measurements and determine the UE's location based on the PRS measurement results.

[0020] There are various ways in which the UE can classify cells into a first group and a second group of cell candidates. In some examples, the first group of cell candidates may include cells that transmit PRS symbols only in MBSFN subframes, and the PRS symbols may include ECP or a mix of ECP and NCP. The second group of cell candidates may include cells that transmit PRS symbols in NCP, including cells that belong to an MBSFN but transmit PRS symbols in a mix of MBSFN and non-MBSFN subframes (e.g., subframe 0) within a positioning occasion, and cells that do not belong to an MBSFN and therefore transmit PRS symbols in non-MBSFN subframes within a positioning occasion.

[0021] The UE can obtain MBSFN subframe and PRS subframe information, as well as the CP length of the PRS symbols, from various sources. In one example, the UE may receive system broadcast messages, such as system information block type 2 (SIB2) messages and system information block type 13 (SIB13) messages, and can obtain MBSFN configuration information from these messages. The messages can identify, based on subframe numbers, MBSFN subframes used to carry MBMS symbols, MBSFN subframes used to carry Multicast Control Channel (MCCH) control channels, and so on, output by cells that are part of the MBSFN. In addition, the assistance data can also identify PBS subframes that carry PBS symbols, as well as the CP length of the PBS symbols. The UE can compare the MBSFN subframes (if any) for each cell candidate with the subframe numbers of the PBS subframes to determine whether the cell candidate transmits PBS symbols entirely using MBSFN subframes or whether the cell candidate transmits PBS symbols using non-MBSFN subframes. The UE can also obtain the CP length (ECP or NCP) of the PBS symbols from the assistance data. Based on this information, the UE may classify each cell candidate into one of the first group or the second group. In another example, the UE may also receive PBS and MBSFN subframe information for each cell candidate and identify each cell candidate based on the subframe information included in the assistance data.

[0022] The UE can then select a group of cell candidates (one of the first group or the second group) for measuring PRS in the positioning occasion based on one or more predetermined criteria. In one example, the UE may determine one or more performance measures of PRS measurements for the first and second groups of cell candidates and select the group that yields a better performance measure. One performance measure may be based on the reliability of the PRS measurements using the cell candidates. In one example, the assistance data identifies a list of reference cells and neighboring cells. RSTD may be determined based on the timing difference between a PRS signal received from the reference cell, which serves as a reference, and a PRS signal received from the neighboring cells. The neighboring cells listed in the assistance data may include cell candidates from which the UE can select to measure RSTD in combination with the reference cell. In the assistance data, the neighboring cells may be listed and arranged in descending order of measurement priority. A neighboring cell that is listed as a higher priority cell in the assistance data (based on the order of the cells in the list) may reflect more reliable PRS measurements using that cell, and therefore has a higher priority for measuring PRS using that cell compared to a neighboring cell that is listed as a lower priority cell. The UE may determine an overall priority of cells for each cell candidate group, for example, based on calculating an average order of cells in the list for each cell candidate group, and may select a cell candidate group with a higher overall priority for measuring PRS.

[0023] In another example, the performance measure may be based on measuring the quality of signals received from cells. Specifically, the signal quality may be measured based on, for example, reference signal received power (RSRP), received signal strength indication (RSSI), etc. The UE may determine the overall signal quality of the cells for each cell candidate group, for example, based on calculating an average RSRP / RSSI measurement result for each cell candidate group, and may select the cell candidate group that provides a higher overall signal quality for measuring the PRS.

[0024] In some examples, the UE may also perform cell candidate group selection according to a multi-stage approach. In a first stage, the UE may select between a first group and a second group based on an overall priority for each group. The UE may then determine whether PRS measurements using the selected group may lead to a less accurate location determination than measurements using the non-selected group. This determination may be based, for example, on the fact that the selected group includes many fewer cells than the non-selected group, and therefore provides fewer RSTD results to improve position determination results. If the UE determines, based on the overall priority, that PRS measurements using the selected group may lead to a less accurate location determination than PRS measurements using the non-selected group, the UE may measure PRS signal quality (e.g., RSSI, RSRP) using cells in both groups and select the group that results in a higher overall signal quality. The group selected based on the higher overall signal quality may be the same as or different from the group selected based on the higher overall priority, and selection of the group based on overall signal quality may override selection of the group based on overall priority.

[0025] In some examples, the UE may determine that the group selection at the end of the two-stage approach (based on overall priority and then on overall signal quality) does not identify a cell group that improves position determination compared to other cell groups. In such cases, the UE may alternate between measuring PRS between the first and second cell groups at each positioning occasion. In such cases, the selection of a cell group for measuring PRS at a positioning occasion is based on the cell group not being selected at the previous positioning occasion.

[0026] In some examples, the UE may apply a digital signal processing configuration for one type of cyclic prefix (ECP or NCP) to recover symbols of a different type of cyclic prefix. For example, the UE may apply digital signal processing for NCP to recover symbols with ECP, or vice versa. The UE can enable recovery of mismatches between the digital signal processing configuration and the cyclic prefix of a symbol when the UE measures PRS using both selected and non-selected cell groups within a positioning occasion, for example, to increase sources for measuring RSTD, which can improve the accuracy of location determination operations. The UE can employ a digital signal processing configuration for a given cyclic prefix (e.g., NCP) used by a selected cell group and use that configuration to recover PRS symbols with that cyclic prefix from the selected cell group within the positioning occasion. The UE can also use that configuration to recover PRS symbols with a different cyclic prefix (e.g., ECP) ​​from non-selected cell groups within the positioning occasion. The UE may also assign different weights to the PRS measurements for each of the selected and unselected cell groups, with a higher weight assigned to the selected cell group. The weight assigned to the unselected cell group may be adjusted based on the expected symbol recovery error and may be increased to result in a smaller symbol recovery error.

[0027] In the disclosed techniques, the UE can select a group of candidate cells for measuring PRS based on performance measures (e.g., overall measurement priority, overall signal quality), which can improve the accuracy of the PRS measurements and resulting location determination operations. Through the selection process, the UE can also select a smaller number of cells that can provide more accurate PRS measurement results, which can reduce the power consumption of the PRS measurements and location determination operations at the UE. All of these can improve the performance of the UE.

[0028] Detailed Description Several example embodiments will now be described with reference to the accompanying drawings that form a part of this specification. Specific embodiments in which one or more aspects of the present disclosure may be implemented are described below, but other embodiments may be used, and various modifications may be made without departing from the scope of the present disclosure.

[0029] As used herein, an "RF signal" or "radio signal" comprises electromagnetic waves that carry information through space between a transmitter (or transmitting device) and a receiver (or receiving device). As used herein, a transmitter may transmit a single "RF signal" or multiple "RF signals" to a receiver. However, the receiver may receive multiple "RF signals" corresponding to each transmitted RF signal due to the propagation characteristics of RF signals through a multipath channel. The same transmitted RF signal on different paths between the transmitter and receiver is sometimes referred to as a "multipath" RF signal.

[0030] 1 is a simplified illustration of a positioning system 100 in which a UE 105, a location server (LS) 160, and / or other components of the positioning system 100 can use techniques provided herein to determine an estimated location of the UE 105, according to an embodiment. The techniques described herein may be implemented by one or more components of the positioning system 100. The positioning system 100 may include a UE 105, one or more satellites 110 (also referred to as GNSS space vehicles (SVs)) for a global navigation satellite system (GNSS), such as a global positioning system (GPS), a base station 120, an access point (AP) 130, the LS 160, a network 170, and an external client 180.

[0031] It should be noted that FIG. 1 provides only a generalized illustration of the various components, and that any or all of the components may be utilized as appropriate, and that each of the components may be replicated as needed. Specifically, while only one UE 105 is illustrated, it will be understood that many UEs (e.g., hundreds, thousands, or millions) may utilize the positioning system 100. Similarly, the positioning system 100 may include more or fewer base stations 120 and / or APs 130 than those illustrated in FIG. 1. The illustrated connections connecting the various components in the positioning system 100 comprise data and signaling connections that may include additional (intermediate) components, direct or indirect physical and / or wireless connections, and / or additional networks. Furthermore, components may be rearranged, combined, separated, substituted, and / or omitted depending on the desired functionality. In some embodiments, for example, the external client 180 may be directly connected to the LS 160. Those skilled in the art will recognize many modifications to the illustrated components.

[0032] Depending on the desired functionality, network 170 may comprise any of a variety of wireless and / or wired networks. Network 170 may comprise, for example, any combination of public and / or private networks, local area networks and / or wide area networks, etc. Furthermore, network 170 may utilize one or more wired and / or wireless communication technologies. In some embodiments, network 170 may comprise, for example, a cellular or other mobile network, a wireless local area network (WLAN), a wireless wide area network (WWAN), and / or the Internet. Specific examples of network 170 include a Long-Term Evolution (LTE) wireless network, a fifth-generation (5G) wireless network (also referred to as a New Radio (NR) wireless network), a Wi-Fi wireless local area network (WLAN), and the Internet. LTE, 5G, and NR are wireless technologies defined or being defined by the 3rd Generation Partnership Project (3GPP). Network 170 may also include two or more networks and / or two or more types of networks.

[0033] The base stations 120 and access points (APs) 130 are communicatively coupled to the network 170. In some embodiments, the base stations 120 may be owned, maintained, and / or operated by a cellular network provider and may utilize any of a variety of wireless technologies, as described herein below. Depending on the technology of the network 170, the base stations 120 may comprise a node B, an Evolved Node B (eNodeB or eNB), a base transceiver station (BTS), a radio base station (RBS), a NR NodeB (gNB), a next-generation eNB (ng-eNB), etc. A base station 120 that is a gNB or ng-eNB may be part of a next-generation radio access network (NG-RAN), which may connect to a 5G core network (5GC) if the network 170 is a 5G network. The APs 130 may include, for example, a Wi-Fi AP or a Bluetooth AP. Thus, the UE 105 can send and receive information to and from network connectivity devices, such as the LS 160, by accessing the network 170 through the base stations 120 using the first communication link 133. Additionally or alternatively, the AP 130 may also be communicatively coupled to the network 170 so that the UE 105 may communicate with internet-connected devices, including the LS 160, using the second communication link 135.

[0034] The LS 160 may comprise a server and / or other computing device configured to determine an estimated location of the UE 105 and / or provide data (e.g., “assistance data”) to the UE 105 to facilitate location determination. According to some embodiments, the LS 160 may include a Home Secure User Plane Location (SUPL) Location Platform (H-SLP), which may support a SUPL User Plane (UP) location method defined by the Open Mobile Alliance (OMA) and may support location services for the UE 105 based on subscription information for the UE 105 stored in the LS 160. In some embodiments, the LS 160 may comprise a Discovered SLP (D-SLP) or an Emergency SLP (E-SLP). The LS 160 may also include an Enhanced Serving Mobile Location Center (E-SMLC) that supports location of the UE 105 using a Control Plane (CP) location method for LTE radio access by the UE 105. The LS 160 may further comprise a Location Management Function (LMF) that supports location of the UE 105 using a control plane (CP) location method for 5G or NR radio access by the UE 105. In a CP location method, signaling for controlling and managing location of the UE 105 may be exchanged between elements of the network 170 and the UE 105 using existing network interfaces and protocols, and as signaling from the perspective of the network 170. In a UP location method, signaling for controlling and managing location of the UE 105 may be exchanged between the LS 160 and the UE 105 as data from the perspective of the network 170 (e.g., data transported using Internet Protocol (IP) and / or Transmission Control Protocol (TCP)).

[0035] The estimated location of the UE 105 may be used in various applications, such as to aid in direction finding or navigation for a user of the UE 105 or to help another user (e.g., associated with the external client 180) locate the UE 105. “Location” is also referred to herein as a “position estimate,” “estimated location,” “location,” “location,” “location estimate,” “location fix,” “estimated location,” “position fix,” or “fix.” The location of the UE 105 may comprise the absolute location of the UE 105 (e.g., latitude and longitude and possibly altitude) or the relative location of the UE 105 (e.g., a location expressed as a distance north-south, east-west, and possibly up-down from some other known fixed location or from some other location, such as the location of the UE 105 at some known prior time). The location may also be specified as a geodetic location (as latitude and longitude) or as a civic location (e.g., with a street address or using other location-related names and signs). The position may further include an indication of uncertainty or error, such as the horizontal and possibly vertical distance by which the position is expected to be in error, or an indication of an area or volume (e.g., a circle or ellipse) in which the UE 105 is expected to be located with a certain level of confidence (e.g., 95% confidence).

[0036] The external client 180 may be a web server or remote application that may have some association with the UE 105 (e.g., that may be accessed by a user of the UE 105), or may be a server, application, or computer system that provides location services to some other user or users, which may include obtaining and providing the location of the UE 105 (e.g., to enable services such as finding friends or relatives, asset management, or locating children or pets). Additionally or alternatively, the external client 180 may obtain and provide the location of the UE 105 to emergency service providers, government agencies, etc.

[0037] As previously mentioned, the exemplary positioning system 100 may be implemented using a wireless communication network, such as an LTE-based network or a 5G NR-based network. FIG. 2 shows a diagram of a 5G NR positioning system 200 illustrating an embodiment of a positioning system (e.g., positioning system 200) implementing 5G NR. The 5G NR positioning system 200 may be configured to determine the location of the UE 105 by using access nodes 210 and 216 (which may correspond to base stations 120 and access points 130 of FIG. 1 ) and (optionally) an LMF 220 (which may correspond to LS 160) to perform one or more positioning methods. Here, the 5G NR positioning system 200 comprises the UE 105 and a component 5G NR network, which comprises a Next Generation (NG) Radio Access Network (RAN) (NG-RAN) 235 and a 5G Core Network (5G CN) 240. The 5G network may also be referred to as an NR network, the NG-RAN 235 may be referred to as a 5G RAN or NG RAN, and the 5G CN 240 may be referred to as an NG core network. Standardization of the NG-RAN and 5G CN is underway at 3GPP. Thus, the NG-RAN 235 and 5G CN 240 may conform to current or future standards for 5G support from 3GPP. The 5G NR positioning system 200 may further utilize information from GNSS satellites 110 of a GNSS system, such as the Global Positioning System (GPS) or a similar system. Additional components of the 5G NR positioning system 200 are described below. The 5G NR positioning system 200 may include additional or alternative components.

[0038] 2 provides only a generalized description of the various components, and any or all of the components may be utilized as appropriate, and each of the components may be duplicated or omitted as needed. Specifically, while only one UE 105 is illustrated, it will be understood that many UEs (e.g., hundreds, thousands, or millions) may utilize the 5G NR positioning system 200. Similarly, the 5G NR positioning system 200 may include a greater (or fewer) number of GNSS satellites 110, access nodes 210 (including gNBs 210-1 and 210-2 and ng-eNBs 210-3), wireless local area networks (WLANs) 216, access and mobility functions (AMFs) 215, external clients 230, and / or other components. The illustrated connections connecting the various components in the 5G NR positioning system 200 include data and signaling connections, which may include additional (intermediate) components, direct or indirect physical and / or wireless connections, and / or additional networks. Additionally, components may be rearranged, combined, separated, substituted, and / or omitted depending on the desired functionality.

[0039] The UE 105 may comprise and / or be referred to as a device, a mobile device, a wireless device, a mobile terminal, a terminal, a mobile station (MS), a Secure User Plane Location (SUPL)-Enabled Terminal (SET), or some other name. Furthermore, the UE 105 may correspond to a mobile phone, a smartphone, a laptop, a tablet, a personal digital assistant (PDA), a tracking device, a navigation device, an Internet of Things (IoT) device, or some other portable or removable device. Typically, but not necessarily, the UE 105 may support wireless communications using one or more radio access technologies (RATs), such as using Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Wideband CDMA (WCDMA), Long-Term Evolution (LTE), High Rate Packet Data (HRPD), IEEE 802.11 Wi-Fi, Bluetooth, Worldwide Interoperability for Microwave Access (WiMAX™), 5G NR (e.g., using NG-RAN 235 and 5G CN 240), etc. The UE 105 may also support wireless communications using a WLAN 216 (such as one or more RATs, as previously described with respect to FIG. 1 ), which may connect to other networks, such as the Internet. Use of one or more of these RATs may enable UE 105 to communicate with external client 230 (e.g., via elements of 5G CN 240 not shown in FIG. 2 or possibly via Gateway Mobile Location Center (GMLC) 225) and / or enable external client 230 to receive location information regarding UE 105 (e.g., via GMLC 225).

[0040] The UE 105 may comprise a single entity or may include multiple entities, such as in a personal area network where the user may utilize audio, video, and / or data I / O devices and / or body sensors and a separate wired or wireless modem. An estimate of the UE 105's location may be referred to as a position, position estimate, position fix, fix, location, location estimate, or location fix, and may be geodetic, thus providing location coordinates (e.g., latitude and longitude) of the UE 105 that may or may not include an altitude component (e.g., elevation, height or depth above ground, floor, or basement). Alternatively, the UE 105's location may be expressed as a civic location (e.g., as an address or designation of some point or small area within a building, such as a particular room or floor). The UE 105's location may also be expressed as an area or volume (defined either geodetically or in civic form) within which the UE 105 is expected to be located with some probability or confidence (e.g., 67%, 95%). The location of the UE 105 may also be a relative location comprising distance and direction or relative X, Y (and Z) coordinates defined with respect to some origin in a known location, which may be defined, for example, geodetically, civic-wise, or with reference to a point, area, or volume shown on a map, floor plan, or architectural plan. In the description contained herein, use of the term location may comprise any of these variations unless otherwise indicated. When calculating the location of a UE, it is common to determine the values ​​of the local X, Y, and possibly Z coordinates and then, if necessary, convert the local coordinates to absolute coordinates (e.g., for latitude, longitude, and altitude above or below mean sea level).

[0041] The base stations in the NG-RAN 235 shown in FIG. 2 correspond to the base stations 120 of FIG. 1 and may comprise transmit / receive points (TRPs) and / or antennas of NR NodeBs (gNBs) 210-1 and 210-2 (collectively and generally referred to herein as gNBs 210). Pairs of gNBs 210 in the NG-RAN 235 may be connected to each other, for example, directly as shown in FIG. 2 or indirectly via other gNBs 210. Access to the 5G network is provided to the UE 105 via wireless communication between the UE 105 and one or more of the access nodes / gNBs 210, which may provide wireless communication access to the 5G CN 240 on behalf of the UE 105 using 5G NR. 5G NR radio access is sometimes referred to as NR radio access or 5G radio access. In FIG. 2, the serving gNB for UE 105 is assumed to be gNB 210-1, but another gNB (e.g., gNB 210-2) may become the serving gNB if UE 105 moves to another location, or may become a secondary gNB to provide additional throughput and bandwidth to UE 105.

[0042] The base stations in the NG-RAN 235 shown in FIG. 2 may further include, or instead include, a next generation evolved Node B, also referred to as an ng-eNB 210-3. The ng-eNB 210-3 may be connected to one or more gNBs 210 in the NG-RAN 235, e.g., directly or indirectly via other gNBs 210 and / or other ng-eNBs. The ng-eNB 210-3 may provide LTE wireless access and / or evolved LTE (eLTE) wireless access to the UE 105. Some gNBs 210 (e.g., gNB 210-2) and / or ng-eNB 210-3 in FIG. 2 may be configured to function as positioning-dedicated beacons, which may transmit signals (e.g., PRS signals) and / or broadcast assistance data to assist in positioning the UE 105, but may not receive signals from the UE 105 or other UEs. It should be noted that although only one ng-eNB 210-3 is shown in FIG. 2, some embodiments may include multiple ng-eNBs 210-3.

[0043] The 5G NR positioning system 200 may also include one or more WLANs 216 that may connect to a Non-3GPP InterWorking Function (N3IWF) 250 in the 5G CN 240 (e.g., in the case of an untrusted WLAN 216). For example, the WLAN 216 may support IEEE 802.11 WiFi access for the UE 105 and may comprise one or more Wi-Fi access points (APs). Here, the N3IWF 250 may connect to other elements in the 5G CN 240, such as the AMF 215. In some embodiments, the WLAN 216 may support another RAT, such as Bluetooth. The N3IWF 250 may provide support for secure access by the UE 105 to other elements in the 5G CN 240 and / or support interworking of one or more protocols used by the WLAN 216 and the UE 105 to one or more protocols used by other elements of the 5G CN 240, such as the AMF 215. For example, the N3IWF 250 may support IPSec tunnel establishment with the UE 105, termination of IKEv2 / IPSec protocols with the UE 105, termination of the N2 and N3 interfaces to the 5G CN 240 for the control plane and user plane, respectively, and relay of uplink and downlink control plane non-access stratum (NAS) signaling between the UE 105 and the AMF 215 across the N1 interface. In some other embodiments, the WLAN 216 may connect directly to an element in the 5G CN 240 (e.g., the AMF 215, shown by the dashed line in FIG. 2 ) without going through the N3IWF 250, for example, if the WLAN 216 is a trusted WLAN for the 5G CN 240. Note that while only one WLAN 216 is shown in FIG. 2 , some embodiments may include multiple WLANs 216.

[0044] An access node may comprise any of a variety of network entities that enable communication between the UE 105 and the AMF 215. This may include a gNB 210, an ng-eNB 210-3, a WLAN 216, and / or other types of cellular base stations. However, an access node providing the functionality described herein may additionally or alternatively include entities that enable communication for any of a variety of RATs not shown in FIG. 2, which may include non-cellular technologies. Thus, hereinafter, the term “access node” as used in the embodiments described herein may include, but is not necessarily limited to, a gNB 210, an ng-eNB 210-3, or a WLAN 216.

[0045] In some embodiments, an access node such as the gNB 210, the ng-eNB 210-3, or the WLAN 216 (alone or in combination with other components of the 5G NR positioning system 200) may be configured to perform measurements (e.g., measurements of the UE 105) for one of the multiple RATs and / or obtain measurement results from the UE 105 that are forwarded to the access node using one or more of the multiple RATs in response to receiving a request for location information from the LMF 220. As mentioned, while FIG. 2 shows the access nodes 210 and 216 configured to communicate according to 5G NR, LTE, and Wi-Fi communication protocols, respectively, access nodes configured to communicate according to other communication protocols may also be used, such as, for example, a Node B using a WCDMA protocol for a Universal Mobile Telecommunications Service (UMTS) Terrestrial Radio Access Network (UTRAN), an eNB using an LTE protocol for an Evolved UTRAN (E-UTRAN), or Bluetooth Beacons using a Bluetooth protocol for a WLAN. For example, in a 4G Evolved Packet System (EPS) that provides LTE wireless access to the UE 105, the RAN may comprise an E-UTRAN, which may comprise base stations with eNBs that support LTE wireless access. The core network for the EPS may then comprise an Evolved Packet Core (EPC). In that case, the EPS may comprise the E-UTRAN plus the EPC, where in FIG. 2 the E-UTRAN corresponds to the NG-RAN 235 and the EPC corresponds to the 5G CN 240. The methods and techniques described herein for positioning a UE 105 using common or generic positioning procedures may also be applicable to such other networks.

[0046] The gNB 210 and ng-eNB 210-3 may communicate with the AMF 215, which communicates with the LMF 220 for positioning functions. The AMF 215 may support mobility of the UE 105, including cell changes and handovers of the UE 105 from access nodes of a first RAT (e.g., the gNB 210 and / or the WLAN 216) to access nodes of a second RAT (e.g., the gNB 210 and / or the WLAN 216). The AMF 215 may also be responsible for supporting signaling connections to the UE 105 and possibly data and voice bearers for the UE 105. The LMF 220 may support positioning of the UE 105 when the UE 105 accesses the NG-RAN 235 or the WLAN 216, and may support positioning procedures and methods, including UE-assisted / UE-based and / or network-based procedures / methods, such as Assisted GNSS (A-GNSS), Observed Time Difference Of Arrival (OTDOA), Real Time Kinematics (RTK), Precise Point Positioning (PPP), Differential GNSS (DGNSS), ECID, Angle of Arrival (AOA), Angle of Departure (AOD), WLAN positioning, and / or other positioning procedures and methods. The LMF 220 may process location service requests for the UE 105, for example, received from the AMF 215 or from the GMLC 225. The LMF 220 may be connected to the AMF 215 and / or the GMLC 225. The LMF 220 may be referred to by other names, such as a Location Manager (LM), Location Function (LF), Commercial LMF (CLMF), or Value-Added LMF (VLMF). In some embodiments, a node / system implementing the LMF 220 may additionally or alternatively implement other types of location support modules, such as an Evolved Serving Mobile Location Center (E-SMLC) or Service Location Protocol (SLP).It should be noted that in some embodiments, at least a portion of the positioning functions (including determining the UE's location) may be performed at the UE 105 (e.g., by processing downlink PRS (DL-PRS) signals transmitted by wireless nodes such as the gNB 210, the ng-eNB 210-3, and / or the WLAN 216, and / or by using assistance data provided to the UE 105 by, for example, the LMF 220).

[0047] The Gateway Mobile Location Center (GMLC) 225 may support location requests for the UE 105 received from the external client 230 and may forward such location requests to the AMF 215 for forwarding by the AMF 215 to the LMF 220, or may forward the location requests directly to the LMF 220. A location response (e.g., including a location estimate for the UE 105) from the LMF 220 may similarly be returned to the GMLC 225 either directly or via the AMF 215, which may then return the location response (e.g., including the location estimate) to the external client 230. Although the GMLC 225 is shown in FIG. 2 as connected to both the AMF 215 and the LMF 220, in some implementations, only one of these connections may be supported by the 5G CN 240.

[0048] As further shown in FIG. 2, the LMF 220 may communicate with the gNB 210 and / or the ng-eNB 210-3 using an LPPa protocol (sometimes referred to as NRPPa or NPPa). The LPPa protocol in NR may be the same as, similar to, or an extension of the LPPa protocol in LTE (related to the LTE Positioning Protocol (LPP)), and LPPa messages are transferred between the gNB 210 and the LMF 220 and / or between the ng-eNB 210-3 and the LMF 220 via the AMF 215. As further shown in FIG. 2, the LMF 220 and the UE 105 may communicate using the LPP protocol. The LMF 220 and the UE 105 may also, or instead, communicate using the LPP protocol (which may also be referred to as NRPP or NPP in NR). Here, LPP messages may be transferred between the UE 105 and the LMF 220 via the AMF 215 and the serving gNB 210-1 or serving ng-eNB 210-3 for the UE 105. For example, the LPP and / or LPP messages may be transferred between the LMF 220 and the AMF 215 using messages for service-based operations (e.g., based on Hypertext Transfer Protocol (HTTP)), or may be transferred between the AMF 215 and the UE 105 using 5G NAS protocols. The LPP and / or LPP protocols may be used to support positioning of the UE 105 using UE-assisted and / or UE-based positioning methods such as A-GNSS, RTK, OTDOA, and / or Enhanced Cell ID (ECID). The LPPa protocol may be used to support positioning of the UE 105 using network-based positioning methods such as ECID (e.g., when used in conjunction with measurement results obtained by the gNB 210 or ng-eNB 210-3), and / or may be used by the LMF 220 to obtain location-related information from the gNB 210 and / or ng-eNB 210-3, such as parameters defining DL-PRS transmissions from the gNB 210 and / or ng-eNB 210-3.

[0049] In the case of UE 105 access to WLAN 216, LMF 220 may obtain the location of UE 105 using LPPa and / or LPP in a manner similar to that described immediately above for UE 105 access to gNB 210 or ng-eNB 210-3. Accordingly, LPPa messages may be forwarded between WLAN 216 and LMF 220 via AMF 215 and N3IWF 250 to support network-based positioning of UE 105 and / or forwarding of other location information from WLAN 216 to LMF 220. Alternatively, LPPa messages may be forwarded between N3IWF 250 and LMF 220 via AMF 215 to support network-based positioning of UE 105 based on location-related information and / or location measurement results known to or accessible to N3IWF 250 and forwarded from N3IWF 250 to LMF 220 using LPPa. Similarly, LPP and / or LPP messages may be transferred between UE 105 and LMF 220 via AMF 215, N3IWF 250, and serving WLAN 216 for UE 105 to support UE-assisted or UE-based positioning of UE 105 by LMF 220.

[0050] In a UE-assisted positioning method, the UE 105 may obtain position measurements and transmit the measurements to a location server (e.g., the LMF 220) for calculation of a position estimate for the UE 105. The position measurements may include one or more of a received signal strength indication (RSSI), a round-trip signal propagation time (RTT), a reference signal received quality (RSRQ), a time of arrival (TOA), an angle of arrival (AOA), a differential AoA (DAOA), an angle of departure (AOD), or a timing advance (TA) of one or more access points for the gNB 210, the ng-eNB 210-3, and / or the WLAN 216. The position measurements may also, or instead, include measurements of a RAT-independent positioning method, such as GNSS (e.g., a GNSS pseudorange, a GNSS code phase, and / or a GNSS carrier phase for SV290), WLAN, etc. With the UE-based positioning method, the UE 105 may obtain position measurement results (e.g., which may be the same as or similar to the position measurement results of the UE-assisted positioning method) and may further calculate the position of the UE 105 (e.g., with the help of assistance data received from a location server such as the LMF 220 or broadcast by the gNB 210, the ng-eNB 210-3, or the WLAN 216). In a network-based positioning method, one or more base stations (e.g., gNB210 and / or ng-eNB210-3), one or more APs (e.g., in WLAN216), or N3IWF250 may obtain location measurements (e.g., RSSI, RTT, RSRP, RSRQ, AoA, or ToA measurements) for signals transmitted by UE105, and / or, in the case of N3IWF250, may receive measurements obtained by UE105 or APs in WLAN216 and transmit the measurements to a location server (e.g., LMF220) for calculation of a position estimate for UE105.

[0051] In addition to supporting positioning methods, LTE and 5G NR networks can be used to transmit various types of data, such as communication data, multimedia data, etc. Data can be transmitted in various types of transmission operations, such as unicast operation and broadcast operation. In unicast operation, each base station is controlled to transmit signals carrying information directed to subscriber UEs. The specificity of unicast signaling enables person-to-person services, such as voice calls, text messaging, or video calls. In broadcast operation, several base stations within a broadcast area are controlled to broadcast signals in a synchronized manner carrying information that can be received and accessed by any subscriber UE within the broadcast area. The generality of broadcast operation enables improved efficiency in transmitting information of public interest, such as event-related multimedia broadcasts. One mechanism for facilitating high-bandwidth communications for multimedia has traditionally been single-frequency network (SFN) operation. In particular, multimedia broadcast multicast services (MBMS) and MBMS for LTE, also known as evolved MBMS (eMBMS), including, for example, multimedia broadcast single-frequency network (MBSFN) in the context of LTE, can utilize such SFN operation. An SFN utilizes radio transmitters, such as base stations, to communicate with subscriber UEs. Multiple base stations belonging to an MBSFN can be controlled to broadcast signals carrying MBMS data, and the cells of the base stations can form an MBSFN area. Subscriber UEs located in the MBSFN area can receive the broadcast signals and provide the broadcasted content to their users.

[0052] In the wireless communication networks shown in FIGS. 1 and 2, a base station may transmit a set of radio signals over a range of time intervals to form a radio frame, where the radio frame includes multiple subframes and each subframe may include multiple transmission time slots. FIGS. 3A and 3B show an example frame structure 300 for FDD, e.g., in an LTE network, a 5G network, etc. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined time length (e.g., 10 milliseconds (ms)) and may be partitioned into 10 subframes with indices ranging from 0 to 9. Each subframe may include two slots. Thus, each radio frame may include 20 slots with indices ranging from 0 to 19. Each slot may include L symbol periods, where each symbol period defines the time length of a symbol. The symbols may be used to represent information to be transmitted. The 2L symbol periods in each subframe may be assigned indices ranging from 0 to 2L-1.

[0053] The symbol duration may be based on a cyclic prefix configuration, in which a portion of the symbol is duplicated and inserted before the symbol to mitigate inter-symbol interference (ISI) caused by multipath effects. FIG. 3C shows an example of a cyclic prefix configuration for a subframe slot. As shown in FIG. 3, each symbol may have a duration of 66.7 milliseconds (us). For a normal cyclic prefix, a prefix with a duration of 5.2 us is prepended to each symbol, while for an extended cyclic prefix, a prefix with a duration of 16.7 us is prepended to each symbol. In both cases, the prefix is ​​generated by duplicating a portion of the following symbol. The normal cyclic prefix is ​​used in urban cell and high-data-rate applications, while the extended cyclic prefix is ​​used when signals must travel long distances, such as in an MBSFN where multiple base stations broadcast signals covering an MBSFN area across multiple cells.

[0054] The cyclic prefix varies the symbol time length and determines the number of symbols in a transmission time slot. For example, as shown in FIG. 3C, if a symbol includes a normal cyclic prefix, the transmission slot may have seven symbol periods (for symbols SYM0 through SYM6). Additionally, if a symbol includes an extended cyclic prefix, the transmission slot may have six symbol periods (for symbols SYM0 through SYM5). Symbols with different cyclic prefixes require different digital signal processing configurations to recover the symbol from the wireless signal. For example, based on whether the received symbol has an NCP or an ECP, a digital signal processor may skip a different number of samples of the wireless signal received within the symbol period corresponding to the cyclic prefix and then process the remaining samples received within the symbol period to recover the symbol. Referring to FIG. 3C, for a given sampling rate, a symbol may be represented by 2048 samples of the wireless signal. A normal cyclic prefix may be represented by 160 samples in the first symbol period and 144 samples in the other symbol periods, while an extended cyclic prefix may be represented by 512 samples. Thus, if the received symbols include a normal cyclic prefix, the digital signal processor may skip the first 160 samples of the received wireless signal in each symbol period, but if the received symbols include an extended cyclic prefix, the digital signal processor may skip the first 512 samples of the received wireless signal in each symbol period to remove the cyclic prefix in the time domain and then perform processing on the remaining 2048 samples in the symbol period. The processing may include a fast Fourier transform operation, a descrambling operation, rotation, DC compensation, followed by an inverse fast Fourier transform operation.

[0055] Furthermore, each slot may also be associated with several subcarriers. A slot (associated with a particular subframe and frame) and the subcarriers associated with the slot may form the basis of a resource block (RB). Resource blocks may be allocated to multiple UEs, with the allocation determining when the UEs transmit and receive information. For example, each UE may be allocated a set of resource blocks in uplink and downlink radio frames for performing data communication. Based on the allocated set of resource blocks, the UE may transmit data in a certain slot (within a certain subframe and frame) using the subcarriers associated with those slots for transmitting symbols. To avoid interference and corruption, different UEs are allocated different resource blocks, and different sets of subcarriers are used for uplink transmission. For example, when two UEs simultaneously transmit slots of a radio frame, one slot transmitted by one UE is associated with a different set of subcarriers from the other slot transmitted by the other UE. Thus, the UEs may be scheduled to transmit information using different sets of subcarriers at different time intervals. Similarly, based on the allocated resource block information, the UE can also selectively process some slots of a radio frame received from a downlink transmission from the base station, where those slots carry information intended for that UE.

[0056] As shown in FIG. 3A, on the LTE downlink, a cell may transmit a Physical Control Format Indicator Channel (PCFICH), a Physical HARQ Indicator Channel (PHICH), and a Physical Downlink Control Channel (PDCCH) in the control region of a subframe. The PCFICH may carry the size of the control region. The PHICH may carry acknowledgement (ACK) and negative acknowledgement (NACK) feedback for data transmissions transmitted on the uplink using HARQ. The PDCCH may carry downlink grants, uplink grants, scheduling information, and / or other control information. A cell may also transmit a Physical Downlink Shared Channel (PDSCH) in the data region of a subframe (not shown in FIG. 2A). The PDSCH may carry data for UEs scheduled for data transmission on the downlink.

[0057] As shown in FIG. 3A, on the LTE downlink, a cell may transmit a Physical Control Format Indicator Channel (PCFICH), a Physical HARQ Indicator Channel (PHICH), and a Physical Downlink Control Channel (PDCCH) in the control region of a subframe. The PCFICH may carry the size of the control region. The PHICH may carry acknowledgement (ACK) and negative acknowledgement (NACK) feedback for data transmissions sent on the uplink using HARQ. The PDCCH may carry downlink grants, uplink grants, and / or other control information. A cell may also transmit a Physical Downlink Shared Channel (PDSCH) in the data region of a subframe. The PDSCH may carry data for UEs scheduled for data transmission on the downlink.

[0058] A cell may also transmit a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) on the downlink, e.g., at a center frequency of 1.08 MHz in the system standby band. In FDD, the PSS and SSS may be transmitted in symbol periods 6 and 5, respectively, in subframes 0 and 5 of each radio frame with a normal cyclic prefix, as shown in FIG. 3A. Although not shown in the figure, subframe 5 may also include other information, such as a system information block (SIB), which may include radio resource configuration information, common shared configurations, timers, etc. For example, the SIB block may include MBSFN configuration information, as discussed below.

[0059] In addition, the base station may also transmit reference signals in some symbol periods of each subframe. A reference signal is a signal known a priori by the transmitter and receiver and is sometimes called a pilot. The UE may perform various signal measurements on the received reference signals, such as received signal strength indication (RSSI), round-trip signal propagation time (RTT), reference signal time difference (RSTD), reference signal received power (RSRP), and / or reference signal received quality (RSRQ).

[0060] One exemplary reference signal is a positioning reference signal (PRS), which may be used by a UE to measure RSTD and support UE-assisted positioning methods. Figure 3D shows an exemplary radio frame structure 310 for the transmission of a PRS signal. The PRS signal is transmitted over consecutive subframes N PRS The PRS symbols are transmitted in predetermined positioning subframes grouped by . There can be 12 or 14 PRS symbols in a subframe, depending on whether the PRS symbols contain an extended cyclic prefix (ECP) or a normal cyclic prefix (NCP). Each group of positioning subframes is sometimes called a "positioning occasion" and is repeated for a predetermined period T PRS This can occur periodically in a period T PRSThe number of consecutive subframes N may be, for example, 160, 320, 640, or 1280 subframes. PRS can be 1, 2, 4, or 6 subframes. The scheduling of PRS signal transmission is performed with a cell-specific subframe offset Δ PRS The subframe offset Δ may be configured based on the UE's starting subframe offset, which may define the starting subframe of the PRS transmission relative to the system frame number (SFN). The SFN may be a timestamp provided by a location server, such as the LMF 220, as part of the assistance data. The SFN may be associated with one or more serving cells of the UE and may serve as a reference for defining the subframe location of the PRS signal. PRS , period T PRS , and consecutive subframes N PRS Based on this, the transmission timing of the PRS symbols can be predetermined.

[0061] To perform location estimation, the UE 105 can measure a reference signal time difference (RSTD) based on the PRS. The RSTD can be measured based on a signal (e.g., a PRS) received from a reference cell and a corresponding signal received from a neighboring cell. For example, to measure the RSTD between the reference cell and the neighboring cell, the UE 105 can determine the time when the UE receives the start of one PRS subframe from the reference cell and the time when the UE receives the start of a corresponding PRS subframe from the neighboring cell to determine the TOA difference. The UE 105 can also measure the RSTD between the reference cell and a different neighboring cell and then provide the RSTD result to a location server. The location server can then estimate the location of the UE 105 based on the RSTD result and the known locations of the base stations of the reference cell and the neighboring cell.

[0062] In addition to PRS signals, a base station can transmit MBMS data using the exemplary radio frame structure 300 of Figures 3A and 3B. Figure 3E shows an exemplary radio frame structure 320 for transmitting MBMS data. As shown in Figure 3E, in the radio frame structure 320, MBMS data may be transmitted in subframe number 1 (SF1), subframe number 2 (SF2), subframe number 3 (SF3), subframe number 6 (SF6), subframe number 7 (SF7), and subframe number 8 (SF8). The remainder of the subframes of the radio frame may be used for other types of transmissions, such as unicast transmissions. MBMS symbols typically include an extended cyclic prefix (ECP) because broadcast signals need to travel relatively long distances to cover an MBSFN area covered by multiple cells.

[0063] Base stations belonging to an MBSFN can also transmit PRS signals to support both MBMS broadcast and location determination operations at the UE. For example, referring to FIG. 4A, a UE 105 may be within an MBSFN area 400. A base station 402, which may belong to the MBSFN, can transmit radio frames 404 including MBMS symbols in MBSFN subframes (e.g., SF1, SF2, SF3, SF6, SF7, and SF8 in FIG. 3E) to support multicast broadcast operations. If selected by the UE 105 to measure the PRS with the UE, the base station 402 can also transmit PRS symbols using the radio frames 404 to support network-based positioning of the UE 105. In addition, there are other base stations, including base stations 406, 408, and 410, that do not belong to the MBSFN. The base stations 406, 408, and 410 can also transmit radio frames 412, 414, and 418, respectively, including PRS symbols, to the UE 105 if they are selected to measure the PRS with the UE. The UE can identify base stations 402, 406, 408, and 410 based on assistance data received from a location server (e.g., LMF 220), which carries reference cells and candidate neighboring cells from which UE 105 can measure PRS, e.g., to obtain RSTD between the reference cell and the neighboring cells and support location determination of UE 105.

[0064] In some scenarios, in a positioning occasion, base station 402 may transmit PRS symbols entirely in MBSFN subframes within radio frame 404, and the PRS symbols within the MBSFN subframes may include a mix of symbols with NCP and symbols with ECP. Meanwhile, cells (e.g., base station 402) that transmit PRS symbols with a mix of MBSFN and non-MBSFN subframes, as well as cells that do not transmit MBSFN subframes (e.g., base stations 406, 408, and 410), may transmit PRS symbols with only NCP or with the same cyclic prefix as subframe 0 of the radio frame.

[0065] 4B and 4C show example radio frames in a positioning occasion that carry both MBMS and PRS symbols. FIG. 4B shows exemplary radio frame structures 420 and 430 in which non-MBSFN subframes are used to transmit PRS symbols. Radio frame structures 420 and 430 may be part of the radio frame 404 transmitted by base station 402 of FIG. 4A. Radio frame structure 420 shows a PRS signal with a bandwidth of 5 MHz and a number of consecutive positioning subframes, N PRS is 2 and the subframe offset Δ PRS Since SF0 is 0, subframe 0 (SF0) of the radio frame carries a PRS symbol, and this may correspond to the case where there are two subframes (SF0 and SF1) that carry PRS symbols. The radio frame structure 430 is PRS is 6 and the subframe offset Δ PRSSince σ is 0, this may correspond to the case where subframes 0 through 5 (SF0-5) of a radio frame carry PRS symbols. In both radio frame structures 420 and 430, PRS symbols are carried in non-MBSFN subframes (e.g., subframe 0 in radio frame structure 420, subframes 0 and 4 and 5 in radio frame structure 430) and MBSFN subframes (subframe 1 in radio frame structure 420, subframes 1 through 3 in radio frame structure 430). Both radio frame structures 420 and 430 may be viewed as having partial overlap between PRS subframes and MBSFN subframes.

[0066] According to section 6.10.4 of 3GPP LTE specification 36.211, when both non-MBSFN and MBSFN subframes are configured as positioning subframes in a cell, the PRS symbols in the MBSFN subframes shall use the same cyclic prefix as used for subframe 0. In exemplary radio frame structures 420 and 430, if the PRS symbols in subframe 0 have a normal cyclic prefix (NCP), then each PRS symbol in the remainder of the subframe (e.g., subframe 0 in radio frame 420, subframes 0 through 5 in radio frame 430) also has an NCP. On the other hand, if the PRS symbols in subframe 0 have an extended cyclic prefix (ECP), then each PRS symbol in the remainder of the subframe (e.g., subframe 1 in radio frame 420, subframes 1 through 5 in radio frame 430) also has an ECP.

[0067] From the assistance data from the location server (e.g., LMF 220), the UE can obtain cyclic prefix length information for PRS symbols transmitted by a particular base station and configure its symbol recovery operation based on whether the PRS symbols have an ECP or an NCP to recover PRS symbols from radio subframes in the positioning occasion. Because the PRS symbols in radio frames 420 and 430 have the same CP length (ECP or NCP) in the positioning occasion, the UE can use a single CP configuration in its symbol recovery operation to recover all PRS symbols transmitted by base station 402.

[0068] 4C shows exemplary radio frame structures 440 and 450 in which non-MBSFN subframes are used to transmit PRS symbols. Radio frame structures 440 and 450 may be part of radio frame 404 transmitted by base station 402 of FIG. 4A. Radio frame structure 440 is used when the PRS signal bandwidth is 20 MHz and the number of consecutive positioning subframes, N PRS is 1 and the subframe offset Δ PRS In radio frame structure 440, subframe 1 is an MBSFN subframe, and PRS symbols are carried only in subframe 1, so all PRS symbols in one positioning occasion are carried by MBSFN subframes. In addition, radio frame structure 450 corresponds to the case where the bandwidth of the PRS signal is 5 MHz and the number of consecutive positioning subframes N PRS is 2 and the subframe offset Δ PRS4 may correspond to the case where PRS symbols are carried in subframes 2 and 3 (SF2 and SF3) because ≠ 2. In radio frame structure 450, subframes 2 and 3 are MBSFN subframes, and PRS symbols are carried only in subframes 2 and 3, so all PRS symbols in one positioning occasion are carried by MBSFN subframes. Both radio frame structures 440 and 450 may be viewed as having complete overlap between PRS subframes and MBSFN subframes.

[0069] In the exemplary radio frame structures 440 and 450, the PRS symbols in a subframe may include a mix of symbols with a normal cyclic prefix (NCP) and symbols with an extended cyclic prefix (ECP). Specifically, according to section 6.10.4 of 3GPP LTE specification 36.211, if only MBSFN subframes are configured as positioning subframes in a cell, the PRS symbols in those MBSFN subframes shall use an extended cyclic prefix length. In cases where a cell is configured to transmit PRS symbols with NCP, the cell may transmit MBMS symbols with ECP within 12 symbol periods (SYM0-SYM11) in the MBSFN subframe, but for PRS symbols in the first three symbol periods (SYM0-SYM2), the cell may transmit the first three symbols with NCP, followed by a blank period, followed by PRS symbols with ECP for the remainder of the symbol periods (SYM3-SYM11).

[0070] Returning to FIG. 4A , with current technology, the UE 105 always measures the PRS using base station 402, which transmits radio frames 404 containing both PRS and MBMS symbols. Such a configuration can have various problems. First, the UE 105 can only measure the PRS using base station 402 and cannot measure the PRS using the other base stations in FIG. 4A . Specifically, base station 402 may transmit PRS symbols in a positioning occasion using a mix of MBSFN and non-MBSFN subframes, as shown in the example of FIG. 4B , and the PRS symbols transmitted by base station 402 have a different CP length than those transmitted by base stations 406, 408, and 410. For example, the PRS symbols transmitted by base station 402 may have an ECP, while the PRS symbols transmitted by base stations 406, 408, and 410 may have an NCP. To recover the PRS symbols, the UE 105 may employ a signal processing configuration for symbols with ECP, in which the UE 105 skips a predetermined number of samples (e.g., 512 samples) of the wireless signal corresponding to the ECP and then processes the remaining samples (e.g., 2048 samples) of the wireless signal in a symbol period to recover the symbols. However, because the UE 105 cannot switch configurations within a positioning occasion, the UE 105 can only fully recover the PRS symbols with ECP from the base station 402 within that positioning occasion. If the UE 105 uses the ECP configuration to process the PRS symbols with NCP, the UE 105 may skip an incorrect number of samples for the NCP for each symbol period (e.g., skips 512 samples with the ECP when the NCP actually has only 160 samples) and may not be able to recover the PRS symbols from the base stations 406, 408, and 410. As a result, the UE 105 may not be able to measure the PRS using 406, 408, and 410, which may prevent the UE from further refining the location determination and may degrade the accuracy of the location determination operations by the UE 105.

[0071] In addition, the base station 402 may also transmit PRS symbols using only MBSFN subframes in a positioning occasion, as shown in the example of FIG. 4C , and the UE 105 may not be able to recover all PRS symbols transmitted by the base station 402 even when employing an ECP configuration. Specifically, when PRS symbols are transmitted in each symbol period, the first three PRS symbols have an NCP, followed by a blank period, followed by an ECP, as shown in FIG. 4C . In a signal processing configuration for symbols with ECP, the UE 105 may not be able to recover the first three PRS symbols because they have NCP. Because not all PRS symbols are recovered, an inaccurate location determination may occur, and the UE 105 may not be able to improve its location determination operation based on PRS measurements using the base stations 406, 408, and 410, as described above.

[0072] 5 illustrates an example operation 500 for location determination in a UE 105 that can address some of the above issues. Specifically, based on information about MBSFN subframes and PRS subframes transmitted by a set of cell candidates with which the UE 105 can measure PRS, the UE 105 can classify the cell candidates into two cell groups 502 and 504. This classification may be based on whether the cells transmit PRS symbols in MBSFN subframes within a positioning occasion and on the CP length (ECP or NCP) of the PRS symbols being transmitted by the cells. In one example, cell group 502 may include cells that transmit PRS symbols only in MBSFN subframes, and the PRS symbols may include ECP or a mix of ECP and NCP. Cell group 504 may include cells that transmit PRS symbols in the NCP, including cells that belong to the MBSFN but transmit PRS symbols in a mix of MBSFN and non-MBSFN subframes (e.g., subframe 0) within the positioning occasion, as well as cells that do not belong to the MBSFN and therefore transmit PRS symbols in non-MBSFN subframes within the positioning occasion.

[0073] The UE 105 can then select one of cell group 502 or cell group 504 for measuring the PRS based on one or more predetermined criteria. As described below, the selection criteria may include, for example, an overall performance measure for each cell group, whether PRS measurements were performed with a particular cell group in a previous measurement occasion, etc. The UE 105 can then measure the PRS using the selected cell group to obtain measurement results and determine the UE's location based on the results of the PRS measurements. For example, in FIG. 5, the UE 105 can select cell group 504 and employ an NCP configuration for its digital signal processor to recover PRS symbols with NCP from PRS signals received from each base station in cell group 504 in the positioning occasion. The UE 105 can then measure the time of arrival (TOA) of the recovered PRS signal, determine an RSTD based on the TOA for that positioning occasion, and determine the UE 105's location based on the RSTD and the known locations of the base stations in cell group 504. Meanwhile, in that positioning occasion, the UE 105 does not measure the PRS using cell group 502.

[0074] In some examples, the UE 105 may measure PRS using both cell groups but using a CP configuration for the selected cell. The location determination is based on a weighted combination of PRS measurements from the selected and non-selected cell groups, with the PRS measurements being assigned a higher weight than the non-selected cell group. In the example of FIG. 5, the UE 105 may use the NCP configuration to recover PRS symbols from both cell groups 502 and 504 during the same positioning occasion, measure the TOAs of the recovered PRS signals, determine an RSTD based on the TOAs, and generate a location estimate based on the RSTD and the known locations of base stations in each cell group. The UE 105 may assign a weight to each location estimate, with a higher weight assigned to the location estimate from PRS measurements using the selected cell group (e.g., cell group 504) and a lower weight assigned to the location estimate from PRS measurements using the non-selected cell group (e.g., cell group 502). For example, a smaller weight may be assigned due to using an NCP configuration to recover PRS symbols with ECP, which is more likely to lead to symbol recovery errors and inaccurate PRS measurements, but the PRS measurements may still be used to refine or match PRS measurements from a selected cell group. The UE can then determine its location based on the weighted average of the location estimates.

[0075] A UE can obtain MBSFN subframe and PRS subframe information, as well as the CP length of PRS symbols, from various sources, such as a system information block (SIB) message, assistance data, etc. Figures 6A and 6B show examples of SIB messages that may be sent by a base station to a UE after the UE selects a cell. Figure 6A shows an example of a system information block type 2 (SIB2) message, which may include a radio source configuration used by the UE to receive downlink data. As shown in Figure 6A, the SIB2 message may include an mbsfn-SubframeConfigList information element 602, which defines the subframes from the base station / cell reserved for MBSFN in the downlink. In addition, Figure 6B shows an example of a system information block type 13 (SIB13) message that may be sent by a base station to provide information for acquiring MBMS control information related to one or more MBSFN areas. An sf-AllocInfo information element 604 may define the radio subframes that may carry the control information. From the SIB2 and SIB13 messages, the UE can determine the subframe numbers of the MBSFN subframes that carry MBMS symbols and control information for the MBSFN. In some examples, assistance data from a location server (e.g., LMF 220) can also provide the subframe numbers of the MBSFN subframes.

[0076] In addition, the UE can obtain the cell's PRS subframe information from the assistance data transmitted by the location server. Figures 6C, 6D, and 6E show examples of assistance data 610 for supporting OTD-OA operation. As shown in Figure 6C, the assistance data 610 may include a reference cell information element 612 for a reference cell that can provide a TOA reference for measuring RSTD, as well as neighbor cell information elements 614 for a set of neighbor cells that can provide TOA measurement results. The TOA measurement results may be compared to the TOA reference from the reference cell to determine RSTD. The set of neighbor cells is described in the NeighborCellInfoList information element 615 in Figure 6E.

[0077] 6D and 6E show example components of the reference cell information element 612 and the neighbor cell information element 614, both of which include a cplength information element 616 and a prsInfo information element 618. The cplength information element 616 may define the length of the CP of the PRS symbol transmitted by the reference / neighbor cell, which may be either an ECP or an NCP. The prsInfo information element 618 may include a prs-ConfigurationIndex element 620 and a numDL-Frames element 622. The prs-ConfigurationIndex element 620 may indicate a subframe offset Δ PRS Additionally, the numDL-Frames element 618 defines the number of consecutive subframes of PRS transmission (N PRS ) can be defined as the subframe offset Δ PRS and N PRS Based on this, the UE 105 can determine the subframe number of the PRS subframe that carries the PRS symbol.

[0078] By identifying the cell transmitting the SIB3 and SIB13 messages and the neighboring cells listed in the NeighborCellInfoList information element 615 of the assistance data, the UE 105 can identify a set of cell candidates with which the UE 105 can measure PRS, in addition to the reference cell. Some of the cell candidates may belong to an MBSFN and transmit both PRS and MBMS symbols, while some of the cell candidates may transmit PRS but not MBMS symbols. The UE 105 can also identify the PRS subframe number and MBSFN subframe number of the cell candidate based on the SIB3 and SIB13 messages and the prsInfo information element 618, and the CP length of the PRS symbols transmitted by the cell candidate.

[0079] 6F shows a data structure 630 that stores correspondence between candidate cells (cells A, B, C, and D) and their PRS subframe numbers, MBSFN subframe numbers, and CP lengths. Based on this information and predetermined classification criteria, cells A, B, and C are classified into cell group 504 of FIG. 5, while cell D is classified into cell group 502 of FIG. 5. In FIG. 6F, cell group 502 may include cell D, which transmits PRS symbols only in MBSFN subframes (subframe 1) with ECP, while cell group 504 includes cells A and C, which belong to the MBSFN but transmit PRS symbols in a mix of MBSFN and non-MBSFN subframes during a positioning occasion, and cell B, which does not belong to the MBSFN, and cells A, B, and C transmit PRS symbols with NCP.

[0080] The UE may then select a candidate group of cells from among cell groups 502 or 504 for measuring PRS at the positioning occasion based on one or more predetermined criteria. In one example, the UE may determine one or more performance measures of the PRS measurements for cell groups 502 and 504 and may select the group that results in a better performance measure.

[0081] 7A and 7B show example performance measures. FIG. 7A shows an example performance measure based on the predicted reliability of PRS measurement results using candidate cells. As shown in FIG. 7A, the NeighborCellInfoList information element 615 may include a list of neighboring cells including cells A, B, C, and D. The neighboring cells may be listed and arranged in descending order of PRS measurement priority. A neighboring cell listed as a higher priority cell (based on the order of the cells in the list) may reflect that PRS measurements using that cell are predicted to be more reliable, and therefore has a higher priority for measuring PRS using that cell compared to a neighboring cell listed as a lower priority cell. In the example of FIG. 7A, cell A may have the highest priority, followed by cells B and C, and cell D may have the lowest priority.

[0082] The UE can then determine an overall priority of the cells for each cell candidate group. In one example, as shown in FIG. 7A , the UE can assign a preference score 702 reflecting the priority of the cells in the NeighborCellInfoList information element 615, with higher preference scores assigned to higher priority cells and vice versa. The UE 105 can then calculate the overall preference score 704 of the cells for each of the cell groups 502 and 504 and select the cell group with the higher overall preference score to measure the PRS. In the example of FIG. 7A , the UE 105 can calculate the overall preference score based on averaging the preference scores of cells A, B, and C in the cell group 504, while the average preference score for the cell group 504 is the preference score of cell D alone in the cell group 502. The UE 105 can select the cell group 504 to measure the PRS based on the average preference score of the cell group 504 being higher than the preference score of the cell group 502.

[0083] FIG. 7B illustrates another exemplary performance measure that may be based on the quality of a signal received from a cell. Specifically, the UE may measure the signal quality of a PRS. The signal quality may be measured using a cell prior to a positioning occasion, for example, based on a received signal strength indication (RSSI), reference signal received power (RSRP), etc. RSSI measures the average total received power observed at a reference symbol. RSRP is a type of RSSI measurement. RSRP may measure the linear average of the power contributions of resource elements (REs) carrying cell-specific reference signals, such as R0 and R1. RSRP measurements, usually expressed in dBm, may indicate the strength of a signal received from a particular cell. A high RSRP for a cell may indicate higher quality of the signal received from that cell compared to a cell with a lower RSRP. As shown in FIG. 7B, the UE 105 may perform RSRP measurements for each of cells A, B, C, and D and obtain RSRP measurement results 706 for each cell.

[0084] The UE may then determine an overall signal quality 708 of the cells for each of the cell groups and then select the cell group with a higher overall signal quality to measure the PRS. In the example of Figure 7B, the UE 105 may calculate the overall signal quality based on averaging the RSRP measurements of cells A, B, and C in cell group 504, while the average RSRP measurement in cell group 504 is the RSRP measurement of cell D alone in cell group 502. Based on the overall signal quality of cell group 504 being higher than the signal quality of cell group 502, the UE 105 may also select cell group 504 to measure the PRS.

[0085] In some examples, the UE 105 may measure signal quality of the PRS using a subset of cells listed in the assistance data, including in-frequency cells. The UE 105 may update the cell candidate group to include only in-frequency cells and select a cell group based on the signal quality results with the in-frequency cells.

[0086] In some examples, the UE 105 may also perform cell candidate group selection (e.g., between cell groups 502 and 504) according to a multi-stage approach. In a first stage, the UE 105 may select between cell groups 502 and 504 based on the overall priority score of each group. The UE may then determine whether measuring PRS using the selected group may lead to a less accurate location determination than measuring using a non-selected group. This determination may be based, for example, on the fact that the selected group includes many fewer cells than the non-selected group, and therefore provides fewer RSTD results to improve position determination results. For example, returning to the example shown in FIGS. 6F and 7A, if cell group 502 includes many other cells in addition to cell D, such that the number of cell groups 502 greatly exceeds the number of cell groups 504, yet the overall priority of cell group 504 is higher than the priority of cell group 502, the UE 105 may determine that selecting cell group 504 for measuring PRS may lead to a less accurate location determination than using a non-selected group.

[0087] Based on determining that selecting a cell group based on the overall priority score may lead to a less accurate location determination than using a non-selected group, the UE 105 may proceed to a second stage, in which the UE 105 measures the signal quality of the PRS (e.g., based on RSSI, RSRP) using cells in both groups, as described in Figure 7B, and selects the group that results in a higher overall signal quality. The group selected based on the higher overall signal quality may be the same as or different from the group selected based on the higher overall priority, and the selection of the group based on overall signal quality may override the selection of the group based on overall priority.

[0088] In some examples, the UE 105 may determine that the group selection at the end of the two-stage approach (based on overall priority and then overall signal quality) does not identify a cell group that improves position determination relative to other cell groups. In such cases, the UE 105 may alternately measure PRS between cell groups 502 and 504 at each positioning occasion. For example, at a first positioning occasion, the UE 105 may perform PRS measurements using cell group 502 to measure RSTD and use the RSTD result from cell group 502 to determine the location of the UE 105. Then, at a second positioning occasion, the UE 105 may measure PRS using cell group 504 to obtain an RSTD result and use the RSTD result from cell group 504 to refine the location determination of the UE 105. In such cases, the selection of a cell group for measuring PRS at a positioning occasion is based on the cell group not being selected at the previous positioning occasion.

[0089] As described above, in some examples, the UE 105 may measure the PRS using both cell groups but using the CP configuration for the selected cell in the same positioning occasion. In one example, the UE 105 may use the NCP configuration to recover both symbols with NCP (from the selected cell) and symbols with ECP (from the non-selected cells). In another example, the UE 105 may also use the ECP configuration to recover both symbols with ECP (from the selected cell) and symbols with NCP (from the non-selected cells). Such a configuration can increase the number of sources for measuring RSTD and improve the accuracy of location determination operations.

[0090] 7C shows examples of symbol recovery configurations 712 and 714 that may be used by the UE 105. In the symbol recovery configuration 712, an NCP configuration is used to recover symbols with ECP, while in the symbol recovery configuration 714, an ECP configuration is used to recover symbols with NCP. In the symbol recovery configuration 712, the UE 105 may skip 160 samples of the NCP and perform processing on the next 2048 samples to recover the first symbol (SYM0), then skip 144 samples of the NCP, followed by processing the next 204 samples to recover the second symbol (SYM1). When applying the NCP configuration to recover symbols with ECP, there may be errors in the recovered symbols SYM0, SYM1, SYM2, etc. because the samples of each symbol do not perfectly align with the actual symbol being transmitted. For example, for SYM0, the samples designated as SYM0 (between samples 160 and 2208) do not perfectly overlap with the actual SYM0 symbol with ECP (between samples 512 and 2560). However, there may be some symbols whose samples perfectly align with the actual samples, and those symbols may have no recovery errors. The following table shows the sample loss for some of the symbols in the symbol recovery configuration 712:

[0091] [Table 1]

[0092] In the symbol recovery configuration 714, the UE 105 may skip 512 samples of the NCP and perform an IFFT on the next 2048 samples to recover the first symbol (SYM0), then skip 144 samples of the NCP, followed by the next 204 samples to recover the second symbol (SYM1). When applying the NCP configuration to recover symbols with ECP, there may be errors in the recovered symbols SYM0, SYM1, SYM2, etc. because the samples of each symbol do not perfectly align with the actual symbol being transmitted. For example, for SYM0, the sample designated SYM0 (between samples 512 and 2560) does not perfectly overlap with the actual SYM0 symbol with NCP (between samples 160 and 2208). However, there may be some symbols whose samples perfectly align with the actual samples, and those symbols may not have recovery errors. The following table shows sample loss for some of the symbols.

[0093] [Table 2]

[0094] In some examples, the UE 105 may select an NCP configuration to recover both NCP and ECP symbols, for example, by finding that such a configuration results in fewer lost samples than when the ECP configuration is used to recover NCP symbols, as shown in Tables 1 and 2. Additionally, the UE 105 may also determine a symbol recovery error based on Tables 1 and 2 and the symbol periods in which the PRS symbols are transmitted, and assign weights to cells based on the symbol recovery error. For example, if PRS symbols are transmitted only in symbol periods corresponding to SYM5 and SYM11 in the ECP (and recovered using the NCP configuration) and only in symbol periods corresponding to SYM6 and SYM13 in the NCP (and recovered using the ECP configuration), the UE 105 may determine that there are no symbol errors and still assign a larger weight to the PRS measurements from the unselected cells.

[0095] In the disclosed techniques, a UE can select a group of candidate cells for measuring PRS based on a performance measure (e.g., overall priority, overall signal quality), which can improve the accuracy of the PRS measurements and resulting location determination operations. Through the selection process, the UE can also select a smaller number of cells that can provide more accurate PRS measurements, which can reduce the power consumption of the PRS measurements and location determination operations at the UE. All of these can improve the performance of the UE.

[0096] 8 is a flow diagram illustrating a method 800 for determining a location of a UE according to an example of the present disclosure. According to some examples, the functions of one or more blocks illustrated in FIG. 8 may be performed by a mobile device including a UE (e.g., the UE 105). As shown in FIG. 9 and described in more detail below, the means for performing these functions may include software and / or hardware components of the UE 105.

[0097] In block 810, the function includes receiving, at the mobile device, assistance data from a location server. The assistance data may identify multiple cell candidates from which the UE can measure one or more location reference signals (PRS) to support the UE's location measurement operations. The location server may include, for example, the LMF 220. Specifically, as described in FIGS. 6C-6E, the assistance data 610 may identify a reference cell and multiple neighboring cells for the UE 105. The neighboring cells may include cell candidates from which the UE can measure a PRS to perform PRS measurements, such as time of arrival (TOA), which may be compared to the TOA obtained by measuring the PRS using the reference cell to determine RSTD. The assistance data may include other information, including CP length (EPC / NCP), subframe offset, and the number of consecutive subframes of PRS symbols transmitted by each cell. In some examples, the assistance data may also indicate which of the cells transmit MBSFN subframes containing MBMS / control data and the subframe number of the MBSFN subframe. As shown in FIG. 9 and described in more detail below, means for performing the functions in block 810 may comprise a bus 905, a processing unit 910, a wireless communication interface 930, a memory 960, and / or software components of the UE 105.

[0098] In block 820, the function includes classifying, at the mobile device, a plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classification being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes within the positioning occasion and based on a cyclic prefix (CP) length (ECP or NCP) of the PRS symbols being transmitted by the cell candidates in the positioning occasion.

[0099] 6A and 6B, the UE 105 may obtain, from SIB2 and SIB13, information indicating subframe numbers of MBSFN subframes carrying MBMS symbols and control information for MBSFN. In some examples, the assistance data received in block 810 may also provide the subframe numbers of the MBSFN subframes. The UE may then generate a data structure, such as data structure 630 of FIG. 6F, that stores a mapping between cell candidates (cells A, B, C, and D) and their PRS subframe numbers, MBSFN subframe numbers, and CP lengths. Based on the mapping information in data structure 630 and predetermined classification criteria, the UE may classify the cell candidates into two cell groups, such as cell groups 502 and 504 of FIG. 5. In some examples, the first group of cell candidates may include cells that transmit PRS symbols only in MBSFN subframes, and the PRS symbols may include ECP or a mix of ECP and NCP. A second group of cell candidates may include cells that transmit PRS symbols in the NCP, including cells that belong to an MBSFN but transmit PRS symbols in a mix of MBSFN and non-MBSFN subframes (e.g., subframe 0) within a positioning occasion, as well as cells that do not belong to an MBSFN and therefore transmit PRS symbols in non-MBSFN subframes within a positioning occasion.

[0100] As shown in FIG. 9 and described in more detail below, means for performing the functions in block 820 may comprise a bus 905, a processing unit 910, a memory 960, and / or other hardware and / or software components of the UE 105.

[0101] In block 830, the function includes selecting one of the first group or the second group of candidate cells for measuring one or more PRSs in the current positioning occasion based on one or more predetermined criteria. The predetermined criteria may include, for example, a performance measure or whether one or more PRSs were performed with a particular group in a previous occasion.

[0102] Specifically, one performance measure may be based on the reliability of PRS measurements using candidate cells. As described above in FIG. 7A, neighboring cells may be listed and arranged in descending order of measurement priority in the assistance data. A neighboring cell listed as a higher priority cell in the assistance data (based on the order of the cells in the list) may reflect more reliable PRS measurements using that cell, and therefore has a higher priority for performing PRS measurements using that cell compared to a neighboring cell listed as a lower priority cell. The UE may assign a priority score to each cell based on the cell's priority as reflected by the cell's order in the list. The UE may then calculate an overall priority score for each cell group (e.g., by averaging the priority scores). The UE may then select a candidate cell group with a higher overall priority score for measuring PRS.

[0103] In another example, the performance measure may be based on the quality of a signal received from a cell. Specifically, as illustrated in FIG. 7B, the UE may measure the signal quality of the PRS based on, for example, a reference signal received power (RSRP), a received signal strength indication (RSSI), etc. The UE may determine the overall signal quality of the cells for each cell candidate group based on, for example, calculating an average RSRP / RSSI measurement result for each cell candidate group, and may select the cell candidate group that results in a higher overall signal quality to perform the PRS measurement.

[0104] In some examples, the UE may also perform cell candidate group selection according to a multi-stage approach. In a first stage, the UE may select between a first group and a second group based on an overall priority for each group. The UE may then determine whether performing PRS measurements using the selected group may lead to a less accurate location determination than measurements using the non-selected group. This determination may be based, for example, on the fact that the selected group includes many fewer cells than the non-selected group, and therefore provides fewer RSTD results to improve position determination results. If the UE determines that performing PRS measurements using the group selected based on the overall priority may lead to a less accurate location determination than using the non-selected group, the UE may perform signal quality measurements (e.g., RSSI, RSRP) using cells in both groups and select the group that provides a higher overall signal quality. The group selected based on the higher overall signal quality may be the same as or different from the group selected based on the higher overall priority, and selection of the group based on overall signal quality may override selection of the group based on overall priority.

[0105] In some examples, the UE may determine that the group selection at the end of the two-stage approach (based on overall priority and then on overall signal quality) does not identify a cell group that improves position determination compared to other cell groups. In such cases, the UE may alternate between performing PRS measurements between the first and second cell groups at each positioning occasion. In such cases, the selection of a cell group for performing PRS measurements at a positioning occasion is based on the cell group not being selected at the previous positioning occasion.

[0106] As shown in FIG. 9 and described in more detail below, means for performing the functions in block 830 may comprise a bus 905, a processing unit 910, a wireless communication interface 930, a memory 960, and / or software components of the UE 105.

[0107] In block 840, the function includes measuring, by the mobile device, one or more PRSs using a selected one of the first group or the second group of cell candidates in the current positioning occasion to perform PRS measurements. Specifically, based on the CP length of the PRS symbols of the selected cell group (e.g., NCP or ECP), the UE can adapt a CP configuration for its digital signal processor to recover the PRS symbols from the selected cell group. For example, if the selected cell group transmits PRS symbols with an NCP, the digital signal processor can skip the first 160 samples received in the first symbol period and the first 144 samples received in other symbol periods representing the NCP, but if the selected cell group transmits PRS symbols with an ECP, the digital signal processor can skip the first 512 samples received in each symbol period representing the ECP. The digital signal processor can then perform processing of the subsequent 2048 samples in the symbol period to recover the PRS symbols. The processing may include a Fast Fourier Transform operation, a descrambling operation, rotation, DC compensation, followed by an Inverse Fast Fourier Transform operation. The UE can then measure the TOA of the recovered PRS symbols. The UE can then determine an RSTD based on the TOA for that positioning occasion and determine the location of the UE 105 based on the RSTD and the known locations of the base stations in the cell group 504.

[0108] In some examples, the UE may not measure PRS using the non-selected cell group or may not include PRS measurements using the non-selected cell group in determining the UE's location. In some examples, the UE may measure PRS using both cell groups but using a CP configuration for the selected cell and then determine the UE's location based on a weighted combination of PRS measurements from the selected and non-selected cell groups, with the PRS measurements from the selected cell group being assigned a greater weight than the PRS measurements from the non-selected cell group.

[0109] As shown in FIG. 9 and described in more detail below, means for performing the functions in block 840 may comprise a bus 905, a processing unit 910, a wireless communication interface 930, a memory 960, and / or software components of the UE 105.

[0110] 9 illustrates an embodiment of a UE 105 that may be utilized as described above in this specification (e.g., in connection with FIGS. 1-8). For example, the UE 105 may perform one or more of the functions of the method 800 of FIG. 8. It should be noted that FIG. 9 is intended only to provide a generalized illustration of various components, any or all of which may be utilized as appropriate. It should be noted that in some instances, the components illustrated by FIG. 9 may be localized in a single physical device and / or distributed across various network-connected devices that may be disposed in different physical locations (e.g., located on different parts of a user's body, in which case the components may be communicatively connected via a personal area network (PAN) and / or other means).

[0111] The UE 105 is shown comprising hardware elements that may be electrically coupled (or otherwise in communication as appropriate) via a bus 905. The hardware elements may include a processing unit 910, which may include, but is not limited to, one or more general-purpose processors, one or more special-purpose processors (such as digital signal processing (DSP) chips, graphics acceleration processors, application-specific integrated circuits (ASICs)), and / or other processing structures or means. As shown in FIG. 9, some embodiments may have a separate DSP 920 depending on desired functionality. Position determination and / or other determinations based on wireless communications may be performed in the processing unit 910 and / or in a wireless communications interface 930 (discussed below). The UE 105 may also include one or more input devices 970, which may include, but are not limited to, a touchscreen, a touchpad, a microphone, buttons, dials, switches, etc., and one or more output devices 915, which may include, but are not limited to, a display, a light-emitting diode (LED), a speaker, etc.

[0112] The UE 105 may also include a wireless communication interface 930, which may comprise, but is not limited to, a modem (such as a Bluetooth device, an IEEE 802.11 device, an IEEE 802.15.4 device, a Wi-Fi device, a WiMAX device, cellular communication equipment), a network card, an infrared communication device, a wireless communication device, and / or a chipset, etc., which may enable the UE 105 to communicate over the network described above with respect to FIG. 1. The wireless communication interface 930 may enable data to be communicated with a network, an eNB, a gNB, and / or other network components, a computer system, and / or any other electronic device described herein. Communication may be performed via one or more wireless communication antennas 932 that transmit and / or receive wireless signals 934.

[0113] Depending on desired functionality, the wireless communication interface 930 may comprise separate transceivers for communicating with base stations (e.g., eNBs and / or gNBs) and other terrestrial transceivers, such as wireless devices and access points. The wireless communication interface 930 may support communication with various network types. For example, a wireless wide area network (WWAN) may be a code division multiple access (CDMA) network, a time division multiple access (TDMA) network, a frequency division multiple access (FDMA) network, an orthogonal frequency division multiple access (OFDMA) network, a single-carrier frequency division multiple access (SC-FDMA) network, WiMAX (IEEE 802.16), etc. A CDMA network may implement one or more radio access technologies (RATs), such as cdma2000, wideband-CDMA (W-CDMA), etc. Cdma2000 includes IS-95, IS-2000, and / or IS-856 standards. A TDMA network may implement Global System for Mobile Communications (GSM), Digital Advanced Mobile Phone System (D-AMPS), or some other RAT. An OFDMA network may employ LTE, LTE Advanced, etc. 5G, LTE, LTE Advanced, GSM, and W-CDMA are described in documents from 3GPP. Cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). 3GPP and 3GPP2 documents are publicly available. A wireless local area network (WLAN) may also be an IEEE 802.11x network, and a wireless personal area network (WPAN) may be a Bluetooth network, an IEEE 802.15x, or some other type of network. The techniques described herein may also be used for any combination of WWAN, WLAN, and / or WPAN.The wireless communication interface 930 may also support fifth-generation (5G) wireless networks (also referred to as New Radio (NR) wireless networks). The wireless communication interface 930 may also support various transmission types of networks, such as a multimedia broadcast multicast service single frequency network (MBSFN), a unicast network, etc.

[0114] The UE 105 may further include sensors 940. Such sensors may comprise, but are not limited to, one or more inertial sensors (e.g., accelerometers, gyroscopes, and / or other IMUs), cameras, magnetometers, altimeters, microphones, proximity sensors, light sensors, etc., some of which may be used to supplement and / or facilitate the location determination described herein.

[0115] Embodiments of the UE 105 may also include a GNSS receiver 980 capable of receiving signals 984 from one or more GNSS satellites (e.g., SVs 110) using a GNSS antenna 982. Such positioning may be utilized to complement and / or incorporate the techniques described herein. The GNSS receiver 980 may extract the location of the UE 105 from GNSS SVs of GNSS systems such as Global Positioning System (GPS), Galileo, Glonass, Compass, the Quasi-Zenith Satellite System (QZSS) over Japan, the Indian Regional Navigational Satellite System (IRNSS) over India, and Beidou over China using conventional techniques. Moreover, the GNSS receiver 980 may be used with various augmentation systems (e.g., Satellite-Based Augmentation Systems (SBAS)), which may be associated with or otherwise enabled for use with one or more global and / or regional navigation satellite systems. By way of example and not limitation, SBAS may include augmentation systems that provide integrity information, differential corrections, etc., such as, for example, Wide Area Augmentation System (WAAS), European Geostationary Navigation Overlay Service (EGNOS), Multi-functional Satellite Augmentation System (MSAS), GPS Aided Geo Augmented Navigation, or GPS and Geo Augmented Navigation system (GAGAN). Accordingly, as used herein, GNSS may include any combination of one or more global and / or regional navigation satellite systems and / or augmentation systems, and GNSS signals may include GNSS signals, GNSS-like signals, and / or other signals related to such one or more GNSSs.

[0116] The UE 105 may further include and / or be in communication with memory 960. The memory 960 may include, but is not limited to, local and / or network-accessible storage, disk drives, drive arrays, optical storage devices, solid-state storage devices such as random access memory (RAM) and / or read-only memory (ROM) that may be programmable, flash-updateable, etc. Such storage devices may be configured to implement any suitable data store, including, but not limited to, various file systems, database structures, etc.

[0117] The memory 960 of the UE 105 may also comprise software elements (not shown in FIG. 9 ), including other code, such as an operating system, device drivers, executable libraries, and / or one or more application programs, which may comprise computer programs provided by various embodiments as described herein and / or may be designed to implement methods and / or configure systems provided by other embodiments. By way of example only, one or more procedures described with respect to the methods discussed above may be implemented as code and / or instructions executable by the UE 105 (and / or the processing unit 910 or DSP 920 within the UE 105). In certain aspects, such code and / or instructions may then be used to configure and / or adapt a general-purpose computer (or other device) to perform one or more operations in accordance with the described methods.

[0118] 10 illustrates an embodiment of a base station 1000 that may be utilized as described herein above. For example, the base station 1000 may perform one or more of the functions to support the method 800 of FIG. 8. Note that FIG. 10 is intended only to provide a generalized illustration of various components, any or all of which may be utilized as appropriate. In some embodiments, the base station 1000 may correspond to the LMF 220, gNB 210, ng-eNB 210-3, as described herein above.

[0119] Base station 1000 is shown comprising hardware elements that may be electrically coupled (or in some cases may be in communication as appropriate) via bus 1005. The hardware elements may include a processing unit 1010, which may include, but is not limited to, one or more general-purpose processors, one or more special-purpose processors (such as digital signal processing (DSP) chips, graphics acceleration processors, application-specific integrated circuits (ASICs)), and / or other processing structures or means. As shown in FIG. 10, some embodiments may have a separate digital signal processor (DSP) 1020 depending on desired functionality. Position determination and / or other determinations based on wireless communications may be performed in processing unit 1010 and / or wireless communications interface 1030 (discussed below).

[0120] The base station 1000 may also include a wireless communication interface 1030, which may comprise, but is not limited to, a modem (such as a Bluetooth® device, an IEEE 802.11 device, an IEEE 802.15.4 device, a WiFi device, a WiMAX device, cellular communication equipment), a network card, an infrared communication device, a wireless communication device, and / or a chipset, etc., which may enable the base station 1000 to communicate as described herein. The wireless communication interface 1030 may enable data and signaling to be communicated (e.g., transmitted and received) to UEs, other base stations (e.g., eNBs, gNBs, and ng-eNBs), and / or other network components, computer systems, and / or any other electronic devices described herein. Communication may be performed via one or more wireless communication antennas 1032 that transmit and / or receive wireless signals 1034.

[0121] The wireless communication interface 1030 may support communication with various network types. For example, a wireless wide area network (WWAN) may be a code division multiple access (CDMA) network, a time division multiple access (TDMA) network, a frequency division multiple access (FDMA) network, an orthogonal frequency division multiple access (OFDMA) network, a single-carrier frequency division multiple access (SC-FDMA) network, WiMAX (IEEE 802.16), etc. A CDMA network may implement one or more radio access technologies (RATs) such as cdma2000, wideband-CDMA (W-CDMA), etc. Cdma2000 includes IS-95, IS-2000, and / or IS-856 standards. A TDMA network may implement Global System for Mobile Communications (GSM), Digital Advanced Mobile Phone System (D-AMPS), or some other RAT. An OFDMA network may employ LTE, LTE Advanced, etc. 5G, LTE, LTE Advanced, GSM, and W-CDMA are described in documents from 3GPP. Cdma2000 is described in documents from an organization named "3rd Generation Partnership Project 2" (3GPP2). 3GPP and 3GPP2 documents are publicly available. A wireless local area network (WLAN) may also be an IEEE 802.11x network, and a wireless personal area network (WPAN) may be a Bluetooth network, an IEEE 802.15x, or some other type of network. The techniques described herein may also be used for any combination of WWAN, WLAN, and / or WPAN. The wireless communication interface 930 may also support fifth-generation (5G) wireless networks (also referred to as New Radio (NR) wireless networks).The wireless communication interface 930 may also support various transmission types of networks, such as a multimedia broadcast multicast service single frequency network (MBSFN), a unicast network, and the like.

[0122] The base station 1000 may also include a network interface 1080, which may include support for wired communication technologies. The network interface 1080 may include a modem, a network card, a chipset, etc. The network interface 1080 may include one or more input and / or output communication interfaces to allow data to be exchanged with a network, a communication network server, a computer system, and / or any other electronic device described herein.

[0123] In many embodiments, base station 1000 further comprises memory 1060. Memory 1060 may include, but is not limited to, local and / or network-accessible storage, disk drives, drive arrays, optical storage devices, solid-state storage devices such as RAM and / or ROM, which may be programmable, flash-updateable, etc. Such storage devices may be configured to implement any suitable data store, including, but not limited to, various file systems, database structures, etc.

[0124] The memory 1060 of the base station 1000 may also comprise software elements (not shown in FIG. 10 ), including other code, such as an operating system, device drivers, executable libraries, and / or one or more application programs, which may comprise computer programs provided by various embodiments as described herein and / or may be designed to implement methods and / or configure systems provided by other embodiments. By way of example only, one or more procedures described with respect to the methods discussed above may be implemented as code and / or instructions in the memory 1060 executable by the base station 1000 (and / or the processing unit 1010 or DSP 1020 within the base station 1000). In certain aspects, such code and / or instructions may then be used to configure and / or adapt a general-purpose computer (or other device) to perform one or more operations in accordance with the described methods.

[0125] It will be apparent to those skilled in the art that substantial modifications may be made according to particular requirements. For example, customized hardware may be used and / or particular elements may be implemented in hardware, software (including portable software such as applets), or both. Furthermore, connectivity to other computing devices, such as network input / output devices, may be utilized.

[0126] With reference to the accompanying figures, components that may include memory may include non-transitory machine-readable media. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any storage medium that participates in providing data that causes a machine to operate in a specific manner. In the embodiments provided above, various machine-readable media may participate in providing instructions / code to a processing unit and / or other devices for execution. Additionally or alternatively, machine-readable media may be used to store and / or transport such instructions / code. In many implementations, computer-readable media are physical and / or tangible storage media. Such media may take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Common forms of computer-readable media include, for example, magnetic and / or optical media, punch cards, paper tape, any other physical media with a pattern of holes, RAM, PROM, EPROM, flash EPROM, any other memory chip or memory cartridge, a carrier wave as described later herein, or any other medium from which a computer can read instructions and / or code.

[0127] The methods, systems, and devices discussed herein are examples. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For example, features described with respect to some embodiments may be combined in various other embodiments. Different aspects and elements of the embodiments may be similarly combined. Various components of the diagrams provided herein may be embodied in hardware and / or software. Also, technology evolves, and therefore, many of the elements are examples that do not limit the scope of the disclosure to those specific examples.

[0128] It has proven convenient at times, principally for reasons of common usage, to refer to such signals as bits, information, values, elements, symbols, characters, variables, terms, numbers, numerical values, or the like. It is understood, however, that all of these or similar terms are to be associated with the appropriate physical quantities and are merely convenient labels. Unless otherwise indicated, and as is clear from the above discussion, it will be understood that throughout this specification, discussions utilizing terms such as “processing,” “computing,” “calculating,” “determining,” “ascertaining,” “identifying,” “associating,” “measuring,” “performing,” and the like refer to the actions or processes of a particular apparatus, such as a special purpose computer or similar special purpose electronic computing device. Thus, in the context of this specification, a special purpose computer or similar special purpose electronic computing device is capable of manipulating or transforming signals that are generally represented as physical electronic, electrical, or magnetic quantities within the memory, registers, or other information storage, transmission, or display devices of the special purpose computer or similar special purpose electronic computing device.

[0129] The terms "and" and "or" as used herein can have a variety of meanings that are expected to depend, at least in part, on the context in which such terms are used. In general, when "or" is used to connect a list, such as A, B, or C, it is intended to mean A, B, and C, which are used herein in an inclusive sense, as well as A, B, or C, which are used herein in an exclusive sense. Additionally, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in the singular, or may be used to describe some combination of features, structures, or characteristics. However, it should be noted that this is merely an illustrative example, and claimed subject matter is not limited to this example. Furthermore, the term "at least one of," when used to connect a list, such as A, B, or C, may be interpreted to mean any combination of A, B, and / or C, such as A, AB, AA, AAB, AABBCCC, etc.

[0130] While several embodiments have been described, various modifications, alternative configurations, and equivalents may be used without departing from the spirit of the present disclosure. For example, the above elements may simply be components of a larger system, and other rules may take precedence over or otherwise modify the application of various embodiments. Also, some steps may be undertaken before, during, or after the above elements are considered. Therefore, the above description does not limit the scope of the present disclosure. [Explanation of symbols]

[0131] 100 Positioning System 105 User Equipment 110 GNSS satellites 120 base station 130 access points 133 First Communication Link 135 Secondary Communication Link 160 Location Server 170 Network 180 external clients 200 NR positioning system 210 gNB 215 AMF 216 WLAN 220 LMF 225 GMLC 230 External Clients 235 NG-RAN 240 5G cores 250 N3IWF 400 MBSFN area 402 Base Station 404 wireless frame 406 Base Station 408 base station 410 base station 412 radio frame 414 Radio Frame 418 Radio Frames 420 Radio Frame Structure 430 Radio Frame Structure 440 Radio Frame Structure 450 Radio Frame Structure 502 Cell Group 504 Cell Group 602 mbsfn-SubframeConfiglist information element 604 sf-AllocInfo information element 610 Support Data 612 Reference Cell Information Element 614 Neighbor Cell Information Element 615 NeighborCellInfoList information element 616 cplength information element 618 prsInfo information element 620 prs-ConfigurationIndex element 622 numDL-Frames element 630 Data Structures 702 Priority Score 704 Priority Score 706 RSRP measurement results 708 Signal Quality 712 Symbol Recovery Configuration 714 Symbol Recovery Configuration 905 Bus 910 Processing Unit 915 Output Devices 920 DSP 930 Wireless Communication Interface 932 Wireless Communication Antenna 934 Wireless Signal 940 Sensors 960 memory 970 Input Devices 980 GNSS receiver 982 GNSS antenna 984 signal 1000 base stations 1005 Bus 1010 Processing Unit 1020 DSP 1030 Wireless communication interface 1032 Wireless communication antenna 1034 Wireless Signal 1060 memory 1080 Network Interface

Claims

1. 1. A method for performing location measurements in a wireless communications network in a user equipment (UE), comprising: receiving assistance data from a location server, the assistance data identifying a plurality of candidate cells from which the UE can measure one or more location reference signals (PRS) to support location measurement operations of the UE; classifying the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classification being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes within a positioning occasion, and based on a cyclic prefix (CP) length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; selecting one of the first group or the second group of candidate cells for measuring the one or more PRSs during the positioning occasion based on one or more predetermined criteria; measuring the one or more PRSs from the selected one of the first group or the second group of cell candidates at the positioning occasion to perform a PRS measurement.

2. the first group of candidate cells includes cells that transmit the PRS symbols with an extended cyclic prefix (ECP) only in MBSFN subframes; 10. The method of claim 1, wherein the second group of candidate cells includes cells that transmit the PRS symbols with a common cyclic prefix (NCP) in non-MBSFN frames.

3. receiving an information block type 2 (SIB2) message from one or more of the cell candidates; the SIB2 message includes MBSFN configuration information indicating whether the candidate cell transmits MBSFN subframes and their subframe numbers; The method of claim 1 , wherein the plurality of cell candidates are classified into the first group and the second group based on the MBSFN configuration information included in the SIB2 message.

4. the assistance data includes MBSFN configuration information of the cell candidate; The method of claim 1 , wherein the plurality of cell candidates are classified into the first group and the second group based on the MBSFN configuration information included in the assistance data.

5. the assistance data includes identifiers of the plurality of cell candidates arranged in a list according to a predetermined order; The method further comprises: assigning a priority score to each of the plurality of cell candidates based on the order of the cell candidates in the list; calculating a first combined priority score for the first group based on the priority scores assigned to each cell candidate classified into the first group; calculating a second combined priority score for the second group based on the priority scores assigned to each cell candidate classified into the second group; One of the first group or the second group of cell candidates is selected based on the first combined priority score and the second combined priority score. The method of claim 1 .

6. the first combined priority score is calculated based on averaging the priority scores of each cell candidate classified into the first group; The method of claim 5 , wherein the second combined preference score is calculated based on averaging the preference scores of each cell candidate classified into the second group.

7. measuring signal quality of the one or more PRSs using at least some of the plurality of candidate cells; The method of claim 5 , wherein one of the first group or the second group of cell candidates is selected based on signal quality results of the cell candidates.

8. selecting the first group of cell candidates based on the first combined priority score and the second combined priority score; In response to determining that PRS measurements using the first group of cell candidates are likely to be less accurate than the PRS measurements using the second group of cell candidates, measuring signal quality of the one or more PRS symbols using at least some of the plurality of candidate cells; determining a first overall signal quality for the first group and a second overall signal quality for the second group based on the signal quality calculations; selecting one of the first group or the second group based on the first overall signal quality and the second overall signal quality; The method of claim 7 further comprising:

9. 9. The method of claim 8, wherein determining that the PRS measurement results using the first group of cell candidates are likely to be less accurate than the PRS measurement results using the second group of cell candidates is based on the first group including fewer cell candidates than the second group.

10. The method of claim 8, wherein at least some of the plurality of cell candidates comprise intra-frequency cells.

11. The method of claim 8, wherein the signal quality calculation results comprise at least one of a reference signal received power (RSRP) measurement result or a received signal strength indication (RSSI).

12. measuring the one or more PRSs from the first group of candidate cells at a first PRS occasion to make a first PRS measurement; measuring the one or more PRSs from the second group of candidate cells at a second PRS occasion to perform a second PRS measurement; The method of claim 1 , wherein the location of the UE is determined based on first PRS measurements and second PRS measurements.

13. measuring the one or more PRSs from the selected one of the first group or the second group of cell candidate in the positioning occasion, in each symbol period: skipping a number of samples of the wireless signal received in the symbol period based on a CP length of the selected one of the first group or the second group of cell candidates, and performing processing on the remaining samples of the wireless signal received in the symbol period to recover a PRS symbol; and determining a time of arrival (TOA) of the recovered PRS symbol.

14. measuring the one or more PRSs from the non-selected one of the first group or the second group of cell candidates at the positioning occasion based on the CP length of the selected one of the first group or the second group of cell candidates; the selected one of the first group or the second group of cell candidates. and determining the location of the UE based on a weighted combination of PRS measurements using the selected cell and the PRS measurements using the non-selected one of the first group or the second group of candidate cells.

15. based on the TOA of a PRS symbol from a reference cell and the TOA of the PRS symbol from the selected one of the first group or the second group of cell candidate; determining a reference signal time difference (RSTD); and determining a location of the UE based on the RSTD, a known location of the reference cell, and a known location of the selected one of the first group or the second group of cell candidates.

16. 1. A user equipment (UE) for performing location measurements in a wireless communications network, comprising: Memory and a wireless communication interface; a processing unit communicatively coupled to the memory and the wireless communication interface, the processing unit comprising: receiving assistance data from a location server, the assistance data identifying a plurality of candidate cells from which the UE can measure one or more location reference signals (PRS) to support location measurement operations of the UE; classifying the plurality of cell candidates into a first group of cell candidates and a second group of cell candidates, the classifying being based on whether the cell candidates transmit PRS symbols in one or more Multimedia Broadcast Single Frequency Network (MBSFN) subframes within a positioning occasion, and based on a cyclic prefix (CP) length of the PRS symbols being transmitted by the cell candidates in the positioning occasion; selecting one of the first group or the second group of candidate cells for measuring the one or more PRSs during the positioning occasion based on one or more predetermined criteria; measuring the one or more PRSs from the selected one of the first group or the second group of candidate cells at the positioning occasion to perform a PRS measurement; The UE is configured to:

17. The UE of claim 16, wherein the processing unit is configured to perform the method of any one of claims 2 to 15.

18. 16. A non-transitory computer readable medium comprising instructions that, when executed by a processor, cause the processor to perform the method of any one of claims 1 to 15.

Images