Distributed location management function

Described herein is a network node comprising a processor that executes instructions to receive a location service request for a user equipment (UE); transmit a reachability request for the UE to an access and mobility management function (AMF); receive a reachability response comprising reachability information of the UE from the AMF; determine whether to perform positioning procedures related to the location service request locally or to perform positioning procedures related to the location service request remotely based, in part, on the reachability information; based on a determination to perform the positioning procedures remotely, determine a distributed location management function (LMFd) to process the location service request based, at least in part, on the reachability information; transmit the location service request to the LMFd; receive a location service result from the LMFd; and transmit, responsive to the location service request, a UE position estimate determined based on the location service result.

TECHNICAL FIELD

The present application relates to systems and methods for locating a mobile device and, in particular, to a distributed location management function.

BACKGROUND

As the use of mobile devices become more common, a need for positioning of the mobile device has arisen. Positioning may include determining the geographical location and/or velocity of a device, e.g., a user equipment (UE) based on measuring radio signals. As used herein mobile device and UE may be used interchangeably. UE may include any device that allows a user to access a network, for example, mobile telephones, smart devices, wearables, laptops, tablets, navigation equipment, etc. Positioning is useful in commercial and non-commercial applications. For example, an advertiser uses positioning to provide advertisements to a UE relative to the location of the UE, and emergency service providers use positioning to respond to distress calls from a UE. Positioning is also useful to optimize network performance. The position information is requested by and reported to a client (e.g., an application) associated with the UE, or by a client within or attached to the network.

SUMMARY

A first aspect relates to a network node comprising a memory having instructions stored therein; and a processor in communication with the memory, wherein the processor executes the instructions to receive a location service request for a user equipment (UE); transmit a reachability request for the UE to an access and mobility management function (AMF); receive a reachability response comprising reachability information of the UE from the AMF; determine whether to perform positioning procedures related to the location service request locally or to perform positioning procedures related to the location service request remotely based, at least in part, on the reachability information; based on a determination to perform the positioning procedures remotely determine a distributed location management function (LMFd) to process the location service request based, at least in part, on the reachability information; transmit the location service request to the LMFd; receive a location service result from the LMFd; and transmit, responsive to the location service request, a UE position estimate determined based on the location service result.

The network node facilitates an efficient solution for performing location services in a network using a LMFd in certain situations where the LMFd provides improved accuracy or efficiency over performing location services at the network node.

In a first implementation form of the network node according to the first aspect as such, the location service result comprises the UE position estimate. Receiving a location service result including the UE position estimate from the LMFd increases processing efficiency at the network node.

In a second implementation form of the network node according to the first aspect as such or any preceding implementation form of the first aspect, the location service result comprises measurements and the processor further executes the instructions to calculate the UE position estimate based on the measurements. Receiving a location service result including measurements from the LMFd increases processing efficiency at the LMFd.

In a third implementation form of the network node according to the first aspect as such or any preceding implementation form of the first aspect, the location service request comprises a requested location services (LCS) quality of service (QoS). A location service request including the LCS QoS provides for more efficient selection of a network node or LMFd to perform the location services.

In a fourth implementation form of the network node according to the first aspect as such or any preceding implementation form of the first aspect, the determination to perform the positioning procedures remotely is further based upon the requested LCS QoS. The network node determines to perform the positioning procedures remotely more effectively based on the LCS QoS.

In a fifth implementation form of the network node according to the first aspect as such or any preceding implementation form of the first aspect, the LMFd is determined further based upon the requested LCS QoS. The network node determines which LMFd to perform the positioning procedures more effectively based on the LCS QoS.

In a sixth implementation form of the network node according to the first aspect as such or any preceding implementation form of the first aspect, the location service request is transmitted to the LMFd via an Nlmf_DetermineLocation service operation. An Nlmf_DetermineLocation service operation improves efficiency of transmitting the information for a location service request.

A second aspect relates to a method for performing location services, the method comprising receiving, by a network node, a location service request for a user equipment (UE); transmitting, by the network node, a reachability request for the UE to an access and mobility management function (AMF); receiving, by the network node, a reachability response comprising reachability information of the UE from the AMF; determining, by the network node, whether to perform positioning procedures related to the location service request locally or to perform positioning procedures related to the location service request remotely based, at least in part, on the reachability information; based on a determination to perform the positioning procedures remotely determining, by the network node, a distributed location management function (LMFd) to process the location service request based, at least in part, on the reachability information; transmitting, by the network node, the location service request to the LMFd; receiving, by the network node, a location service result from the LMFd; and transmitting, by the network node responsive to the location service request, a UE position estimate determined based on the location service result. The method facilitates an efficient solution for performing location services in a network using a LMFd in certain situations where the LMFd provides improved accuracy or efficiency over performing location services at a network node.

In a first implementation form of the method according to the second aspect as such, the location service result comprises the UE position estimate. Receiving a location service result including the UE position estimate from the LMFd increases processing efficiency at the network node.

In a second implementation form of the method according to the second aspect as such or any preceding implementation form of the second aspect, the location service result comprises measurements and the method further comprises calculating the UE position estimate based on the measurements. Receiving a location service result including measurements from the LMFd increases processing efficiency at the LMFd.

In a third implementation form of the method according to the second aspect as such or any preceding implementation form of the second aspect, the location service request comprises a requested location services (LCS) quality of service (QoS). A location service request including the LCS QoS provides for more efficient selection of a network node or LMFd to perform the location services.

In a fourth implementation form of the method according to the second aspect as such or any preceding implementation form of the second aspect, the determination to perform the positioning procedures remotely is further based upon the requested LCS QoS. The network node determines to perform the positioning procedures remotely more effectively based on the LCS QoS.

In a fifth implementation form of the method according to the second aspect as such or any preceding implementation form of the second aspect, the LMFd is determined further based upon the requested LCS QoS. The network node determines which LMFd to perform the positioning procedures more effectively based on the LCS QoS.

In a sixth implementation form of the method according to the second aspect as such or any preceding implementation form of the second aspect, the location service request is transmitted to the LMFd via an Nlmf_DetermineLocation service operation. An Nlmf_DetermineLocation service operation improves efficiency of transmitting the information for a location service request.

A third aspect relates to a computer program comprising a program code for performing the method according to the second aspect or any of its implementation forms when executed on a computer. Thus, the method can be performed in an automatic and repeatable manner. The computer program can be performed by the apparatus. The apparatus can be programmably-arranged to perform the computer program.

A fourth aspect relates to a network node comprising memory means having instructions stored therein and processor means in communication with the memory means, wherein the processor means executes the instructions to perform the method according to the second aspect or any of its implementation forms.

A fifth aspect relates to a network node comprising a memory having instructions stored therein; and a processor in communication with the memory, wherein the processor executes the instructions to receive a location service request for a user equipment (UE) from a central location management function (LMFc), the location service request comprising reachability information of the UE; instigate positioning operations with one or more of the UE or a radio access network (RAN) node; receive location information from one or more of the UE or the RAN node; and transmit a location service result to the LMFc. The network node facilitates an efficient solution for performing location services in a networking at the network node in certain situations where the network node provides improved accuracy and/or efficiency over performing location services at the LMFc.

In a first implementation form of the network node according to the fifth aspect as such, the positioning operations comprise transmitting location assistance data to the UE. Transmitting location assistance data to the UE improves the efficiency of performing location services at the UE.

In a second implementation form of the network node according to the fifth aspect as such or any preceding implementation form of the fifth aspect, the location service result comprises positioning measurements. Transmitting positioning measurements to the LMFc increases efficiency of the location services performed at the UE and/or network node.

In a third implementation form of the network node according to the fifth aspect as such or any preceding implementation form of the fifth aspect, the location service result comprises a UE location estimate. Transmitting a location estimate to the LMFc increases efficiency of the location services performed at the LMFc.

In a fourth implementation form of the network node according to the fifth aspect as such or any preceding implementation form of the fifth aspect, the processor is further configured to calculate a UE position estimate based on the location information. Calculating the position estimate by the network node increases efficiency of the location services performed at the UE and/or LMFc.

A sixth aspect relates to a method for performing location services, the method comprising receiving, by a network node, a location service request for a user equipment (UE) from a central location management function (LMFc), the location service request comprising reachability information of the UE; instigating, by the network node, positioning operations with one or more of the UE or a radio access network (RAN) node; receiving, by the network node, location information from one or more of the UE or the RAN node; and transmitting, by the network node, a location service result to the LMFc. The network node facilitates an efficient solution for performing location services in a networking at the network node in certain situations where the network node provides improved accuracy and/or efficiency over performing location services at the LMFc.

In a first implementation form of the method according to the sixth aspect as such, the positioning operations comprise transmitting location assistance data to the UE. Transmitting location assistance data to the UE improves the efficiency of performing location services at the UE.

In a second implementation form of the method according to the sixth aspect as such or any preceding implementation form of the sixth aspect, the location service result comprises positioning measurements. Transmitting positioning measurements to the LMFc increases efficiency of the location services performed at the UE and/or network node.

In a third implementation form of the method according to the sixth aspect as such or any preceding implementation form of the sixth aspect, the location service result comprises a UE location estimate. Transmitting a location estimate to the LMFc increases efficiency of the location services performed at the LMFc.

In a fourth implementation form of the method according to the sixth aspect as such or any preceding implementation form of the sixth aspect, the method further comprises calculating a UE position estimate based on the location information. Calculating the position estimate by the network node increases efficiency of the location services performed at the UE and/or LMFc.

A seventh aspect relates to a computer program comprising a program code for performing the method according to the sixth aspect or any of its implementation forms when executed on a computer. Thus, the method can be performed in an automatic and repeatable manner. The computer program can be performed by the apparatus. The apparatus can be programmably-arranged to perform the computer program.

An eighth aspect relates to a network node comprising memory means having instructions stored therein and processor means in communication with the memory means, wherein the processor means executes the instructions to perform the method according to the sixth aspect or any of its implementation forms.

DETAILED DESCRIPTION

Described herein are systems and methods for a distributed location management function. The distributed location management function (LMFd) may perform functions that a location management function (LMF) performs, but in a distributed manner at a location closer to the UE being positioned. In systems with a LMFd, a centrally located LMF (LMFc) may be utilized. As used herein, LMF and LMFc may be used interchangeably in systems that include one or more LMFd. An LMFd near the UE being positioned may improve latency and/or measurement results in positioning the UE. The LMFd may be located at or near a radio access network (RAN) node, e.g., an evolved node B (eNB) or next-generation node B (gNB or ng-eNB), which may also be referred to as base stations. As used herein the term RAN may include next generation RAN (NG-RAN), e.g., a fifth generation (5G) RAN. Decreasing latency in the positioning operation may result in increased accuracy of the positioning operation. Embodiments herein may be described in relation to a 5G network using a NG-RAN. The techniques of the described embodiments may be applied to other types of networks or RANs (e.g., non-5G) where positioning of devices is performed.

FIG. 1is a diagram of an embodiment of a 5G network100. The 5G network100may include a core110, a NG-RAN170, a UE180, and an external location services (LCS) client190. The NG-RAN170may include a wireless transmission portion of the 5G network100that communicates with the UE180. The NG-RAN170may include one or more eNBs or gNBs or other RAN nodes. The UE180can communicate with the core110via the NG-RAN170. In some embodiments, nodes within the core110communicate directly with the UE180. External LCS client190may be a node that is not part of the core110that wishes to locate the UE180via the core110and the NG-RAN170.

Core110may include a number of nodes that perform various functions of the 5G system. While several nodes are depicted in the core110, other nodes may be part of the core110but not pictured. Access and mobility management function (AMF)120may function similarly to the long-term evolution (LTE) mobility management entity (MME). AMF120interacts with the NG-RAN170and/or the UE180for access to the other nodes in the core110. AMF120may manage location services for various regulatory services. AMF120can also provide transport for location service messages between location management function (LMF)160and the UE180and/or the NG-RAN170. Gateway mobile location center (GMLC)130may be the first node of the core110that is accessed by the external LCS client190. External LCS client190accesses the GMLC130in an attempt to locate the UE180. GMLC130handles the location request from the external LCS client190and interacts with other nodes in the core110. GMLC130provides the results of a location request to the external LCS client190. Unified data management function (UDM)140stores information regarding which AMF is serving a particular UE. UDM140may also store data regarding privacy requirements of UEs. Location retrieval function (LRF)150may provide location information when, for example, an emergency call, e.g., 911, is initiated from a UE. The location information provided by the LRF150can be used in routing the emergency call to an appropriate emergency responder. The LMF160supports location determination for a UE, e.g., UE180. The LMF160obtains downlink location measurements or a location estimate from the UE180, uplink location measurements from the NG-RAN170, and/or non-UE associated assistance data from the NG-RAN170. While a single instance of each node and a single UE180is shown inFIG. 1, multiple instances of some or all may be present in a 5G network.

FIG. 2is a diagram of an embodiment of a 5G mobile terminated location request (MT-LR)200for a roaming UE280. At step1, an external location services (LCS) client210, sends a location request to a home-GMLC (HGMLC)220in the home public land mobile network (HPLMN) of the UE280. The HGMLC220may verify the authorization of the LCS client210to locate the UE280. The HGMLC220may also verify privacy requirements of the UE280. When the LCS client210is authorized to locate the UE280and no privacy requirements forbid positioning by the LCS client210, the flow continues with step2.

At step2, the HGMLC220invokes an LCS service request operation towards the home UDM230of the UE280. The LCS service request operation may include the generic public subscription identifier (GPSI) or subscription permanent identifier (SUPI) of the UE280. The LCS service request operation may comprise a Nudm_UE ContextManagement_Get Request message.

At step3, the UDM230returns the address of the AMF260and possibly an address of visited-GMLC (VGMLC)240and/or an address of the LMF250in the visited public land mobile network (VPLMN). The UDM230may also return subscribed privacy requirements for the UE280when the privacy requirements are not stored in the HGMLC220. The UDM230may return the data to the HGMLC220in a Nudm_UE ContextManagement_Get Response message.

At step4, when an address of the VGMLC240was not returned in step3, the HGMLC220may use the network function (NF) repository function (NRF) service in the HPLMN to select an available VGMLC240in the VPLMN based on the VPLMN address contained in the AMF address received in step3. The HGMLC220may forward the location request to the VGMLC240and include the address of the AMF260, the identity (e.g., SUPI) of the UE280, any LMF address received in step3, and any privacy requirements for the UE280.

At step5, the VGMLC240determines an LMF250in the VPLMN to receive the location request. The VPLMN may include one or more LMF devices. VGMLC240may determine an LMF250based on any suitable criteria (e.g., location QoS, type of LCS client, VGMLC identity (ID)) and independently of the AMF260. As one example, the VGMLC240may be configured with addresses for all LMFs in the VPLMN and could select the LMF250on a round robin basis. In some embodiments, when an AMF is allowed to use some but not all LMFs in the VPLMN, the VGMLC240is configured with the allowed LMFs for each AMF, and could then select the LMF250based on specific criteria (e.g., QoS), or randomly. In some embodiments, the VGMLC240may use the NRF service in the VPLMN to request a set of available LMFs in the VPLMN and may then select the LMF250based on specific criteria (e.g., QoS), or randomly. In some embodiments, when the UE280registers with a 5G core, the AMF260selects the LMF250and provides the address of the LMF250to the UDM230along with the address of the AMF260. The UDM230then provides the address of the LMF250in step3to the HGMLC220which then provides the address to the VGMLC240in step4. This alternative may be supported for UEs from certain HPLMNs and/or UEs with a subscription to 5G MT-LR usage. Once the VGMLC240has selected LMF250, the VGMLC240invokes an LCS request operation to forward the location request to the LMF250. The LCS request operation may include a Nlmf_ProvideLocation Request message. In some embodiments, when the VGMLC240and the LMF250functions are combined, step5may be omitted.

At step6, as an optional optimization, instead of performing steps4and5, the HGMLC220may determine or select the LMF250(e.g., based on the VPLMN ID, AMF260address, using the NRF service, or by receiving an LMF250address from the UDM230in step3). In this case, the HGMLC220invokes the LCS request operation (e.g., Nlmf_ProvideLocation Request) to forward the location request directly to the LMF250. When this optimization is used, the HGMLC220may need to support the LMF service based interface (SBI) (Nlmf). Therefore, when the HPLMN operator wishes to avoid support of the Nlmf SBI by combining GMLCs with LMFs, steps4and5may be used rather than step6.

At step7, the LMF250invokes a UE reachability request operation towards the AMF260to verify UE280reachability. The UE reachability operation request may be a Namf_MT_EnableUEReachability Request message. When the AMF260is no longer available, the LMF250may use the NRF service in the VPLMN to select another AMF from the same AMF set as the previous AMF260.

At step8, when the UE280is currently idle but reachable, the AMF260performs a network triggered service request in order to place the UE280in connected state.

At step9, the AMF260invokes a UE reachability response service operation towards the LMF250to confirm UE reachability. The UE reachability response service operation may include a Namf_MT_EnableUEReachability Response message.

At step10, the LMF250may notify the UE280and may verify UE privacy requirements based on any privacy requirements received from the HGMLC220in steps4-6. When this occurs, the LMF250sends a supplementary services location notification invoke to the UE280, via the AMF260, using a Namf_Communication_N1N2MessageTransfer service operation.

At step11, the UE280may notify a user of UE280of the location request. The UE280verifies user permission when UE privacy is to be verified. The UE280then returns a supplementary services location notification response to the LMF250indicating whether the user grants or withholds permission for the location request when UE privacy is verified. The supplementary services response may be transferred via the AMF260and delivered to the LMF250using an Namf_Communication_N1MessageNotify service operation.

At step12, when the LMF250needs to know the serving cell for the UE280prior to performing positioning in step14and prefers to obtain the serving cell from the AMF260rather than the UE280or the NG-RAN270(e.g., to reduce latency), the LMF250invokes an event exposure subscribe service operation towards the AMF260to obtain the UE280location information. The event exposure subscribe service operation may be a Namf_EventExposure_Subscribe message and may include an immediate one time notification flag.

At step13, the AMF260may return UE location information to the LMF250(e.g., serving cell ID).

At step14, the LMF250may perform one or more of positioning procedures. The positioning procedures may include a UE assisted and UE based positioning procedure, a network assisted positioning procedure, and a non-UE assisted network assistance positioning procedure. The positioning procedures are described in greater detail below. The positioning procedures may invoke various positioning methods for positioning of the UE280. The positioning methods may include, but are not limited to observed time difference of arrival (OTDOA) positioning, global navigation satellite system (GNSS) positioning, and Enhanced cell ID (E-CID) positioning. The LMF250may determine the location of the UE280using information obtained in this step and/or in step13.

In the event of an inter-AMF handover for the UE280while positioning is in progress, the prior AMF may return an error indication to the LMF250when the LMF250attempts to send a positioning protocol message to the UE280or to the NG-RAN270. When the LMF250subscribes to event notification for inter-AMF handover from the old AMF using the AMF event exposure service operation, the old AMF may notify the LMF250when handover occurs. When the LMF250is able to access the new AMF, the LMF250may resume any of steps10-14with the new AMF. For positioning in the UE280or the NG-RAN270that is already in progress when handover occurs, positioning protocol messages may be returned by the UE280or the NG-RAN270to the LMF250via the new AMF. The messages may include a routing identifier indicating the LMF250. This may enable a positioning session between the UE280and the LMF250to continue following an inter-AMF handover.

In steps15-18, the LMF250returns the location estimate to the LCS client210via the VGMLC240and/or the HGMLC220. The location estimate may be returned using a Nlmf_ProvideLocation Response and/or LCS Service Response message.

For a non-roaming UE, a subset of the steps ofFIG. 2may be performed, for example, in the case of a non-roaming UE, a VGMLC is not present and thus communications with a VGMLC can be omitted.

In some cases, the LCS request may come from a UE280rather than an LCS client210. An LCS request from a UE may be referred to as a mobile-originated location request (MO-LR). For MO-LR, steps1-11ofFIG. 2may be omitted. In place of steps1-11, the UE280may transmit a location service request to the LMF250via AMF260. Steps12-18ofFIG. 2may be performed in the case of MO-LR.

FIG. 3is a diagram of an embodiment of a UE assisted and UE based positioning procedure300. The procedure300may be used by an LMF250to support UE based positioning, UE assisted positioning, and delivery of assistance data. In some embodiments, the procedure300is based on use of LTE positioning protocol (LPP) between the LMF250and UE280. In other embodiments, another protocol such as a New Radio (NR) positioning protocol (NRPP) is used between the LMF250and UE280.

The procedure300begins at step1where the LMF250invokes the Namf_Communication_N1N2MessageTransfer service operation towards the AMF260to request the transfer of a downlink (DL) positioning message to the UE280via the NG-RAN270. The service operation may include the DL positioning message. The session ID parameter of the Namf_Communication_N1N2MessageTransfer service operation may be set to an LCS correlation identifier. The DL positioning message may request location information from the UE280, provide assistance data to the UE280, or query for the UE280capabilities.

At step2, when the UE280is in CM-IDLE state, the AMF260initiates a network triggered service request procedure to establish a signaling connection with the UE280.

At step3, the AMF260forwards the DL positioning message to the UE280in a DL NAS TRANSPORT message. The AMF260may include a routing identifier in the DL NAS TRANSPORT message identifying the LMF250.

At step4, the UE280may store any assistance data provided in the DL positioning message and perform any positioning measurements and location computation requested by the DL positioning message.

At step5, when the UE280has entered CM-IDLE state during step4, the UE280instigates a UE triggered service request in order to establish a signaling connection with the AMF260.

At step6, the UE280returns any location information obtained in step4or may return any capabilities requested in step3to the AMF260in an uplink (UL) positioning message included in a NAS TRANSPORT message. The UE280may also include the routing identifier in the UL NAS TRANSPORT message received in step3.

At step7, the AMF260invokes the Namf_Communication_N1MessageNotify service operation towards the LMF250indicated by the routing identifier received in step6. The service operation may include the UL positioning message received in step6and the LCS correlation identifier. Steps6and7may be repeated when the UE280needs to send multiple messages to respond to the request received in step3. Steps1to7may be repeated to send new assistance data, and to request further location information and further UE capabilities.

In some embodiments, the LMF250may include a routing identifier identifying the LMF250in any positioning message intended for the UE280that is sent to the AMF260at step1. The AMF260may then forward the positioning message to the UE280in the NAS transport message at step3.

FIG. 4is a diagram of an embodiment of a network assisted positioning procedure400. Procedure400may be used by an LMF250to support network assisted and network based positioning. The procedure400may be based on an NR positioning protocol A (NRPPa) protocol between the LMF250and NG-RAN270.

The procedure400begins at step1where the LMF250invokes the Namf_Communication_N1N2MessageTransfer service operation towards the AMF260to request the transfer of a network positioning message to the NG-RAN270node (gNB or ng-eNB) for the UE280. The service operation may include the network positioning message and the LCS correlation identifier. The network positioning message may request location information for the UE280from the NG-RAN270.

At step2, when the UE280is in CM-IDLE state, the AMF260initiates a network triggered service request procedure to establish a signaling connection with the UE280.

At step3, The AMF260forwards the network positioning message to the NG-RAN270node in an N2 Transport message. The AMF260may include a routing identifier in the N2 Transport message identifying the LMF250(e.g., a global address of the LMF250).

At step4, the NG-RAN270node obtains any location information for the UE280requested in step3.

At step5, the NG-RAN270node returns any location information obtained in step4to the AMF260in a network positioning message included in an N2 transport message. The NG-RAN270node may also include the routing identifier in the N2 Transport message received in step3.

At step6, the AMF260invokes the Namf_Communication_N2InfoNotify service towards the LMF250indicated by the routing identifier received in step5. The service operation may include the network positioning message received in step5and the LCS correlation identifier. Steps1to6may be repeated to request further location information and further NG-RAN capabilities.

FIG. 5is a diagram of an embodiment of a non-UE associated network assistance positioning procedure500. Procedure500may be used by an LMF250to support network assisted and network based positioning. Procedure500may not be associated with a UE location session. In some cases, procedure500may be used to obtain network assistance data from a NG-RAN270node (e.g., gNB or ng-eNB). Procedure500may be based on an NRPPa protocol between the LMF250and NG-RAN270. Procedure500may be used for retrieving configuration or measurement information from network nodes that may then be used to formulate assistance data for use in positioning. For example, retrieving RAN nodes' configurations for transmitting OTDOA reference signals. In this example, the LMF250collects information about a large population of RAN nodes, and later when a UE needs to be positioned, the LMF250provides the configuration information for nearby RAN nodes as part of the UE's assistance data.

The procedure500begins at step1where the LMF250invokes the Namf_Communication_N1N2MessageTransfer service operation towards the AMF260to request the transfer of a network positioning message to a NG-RAN270node (gNB or ng-eNB) in the NG-RAN270. The service operation may include the network positioning message and the NG-RAN270node identity. The network positioning message may request position related information from the NG-RAN270.

At step2, the AMF260forwards the network positioning message to the NG-RAN270node indicated in step1in an N2 transport message. The AMF260may include a routing identifier in the N2 Transport message identifying the LMF250.

At step3, the NG-RAN270node obtains any position related information requested in step2.

At step4, the NG-RAN270node returns any position related information obtained in step3to the AMF260in a network positioning message included in an N2 transport message. The NG-RAN270node may also include the routing identifier in the N2 transport message received in step2.

At step5, the AMF260invokes the Namf_Communication_N2InfoNotify service operation towards the LMF250indicated by the routing identifier received in step4. The service operation may include the network positioning message received in step4and the UE identifier. Steps1to5may be repeated to request further position related information from the NG-RAN270.

FIG. 6is a diagram of an embodiment of a roaming 5G network600LMF centric positioning architecture with distributed location management function. The functionality of the components of 5G network600may be similar to the similarly named components of the 5G network100described inFIG. 1. Likewise, while a single instance of each node and a single UE640is shown inFIG. 6, multiple instances of some or all components may be present in a 5G network. 5G network600includes an HPLMN 5G core610, a VPLMN 5G core620, an LCS client630, a UE640, an NG-RAN650, and an LMFd660. UE640may be roaming and attached to NG-RAN650and associated with AMF626of the VPLMN 5G core620. In the case where UE640is not roaming, UE640may be attached to an AMF (not pictured) in the HPLMN 5G core610. In addition to LMFc624of the VPLMN 5G core620, an LMFd660may be located at or near a NG-RAN650node (e.g., gNB or NG-eNB). The LMFd660may be considered part of the VPLMN 5G core620or part of the NG-RAN650. The LMFd660may be in communication with UE640via NG-RAN650or via a combination of AMF626and NG-RAN650. The LMFd660may be in communication with LMFc624via AMF626.

When the LCS client630initiates positioning of the UE640, the LCS client630contacts the HGMLC614for the HPLMN 5G core610. HPLMN 5G core610may be the home PLMN of the UE640. HGMLC614interacts with the UDM612regarding privacy policies and positioning permissions of the UE640relative to the LCS client630. When positioning of the UE640is permitted for the LCS client630, the HGMLC614contacts the VGMLC622to acquire an address for the LMFc624. In some embodiments, when the UE640joins the VPLMN 5G core620, the HGMLC614may be provided with an address for the LMFc624. In either case, the HGMLC614contacts the LMFc624to request positioning of the UE640. LMFc624determines whether to use the LMFd660for positioning. In some cases, multiple LMFds are present in the 5G network600. In these cases, in addition to determining whether or not to use an LMFd for positioning, the LMFc624also determines which of the LMFds to use for positioning. LMFd660may be selected to perform positioning for the UE640. LMFd660may perform positioning using one or more of the procedures and/or methods described in conjunction with step14ofFIG. 2, or some other positioning technique. LMFd660returns positioning information to the LMFc624, which may in turn return the positioning information to the LCS client630. Certain nodes may act as intermediaries in handling the positioning information. For example, the AMF226may receive the positioning information from the LMFd660and forward it to the LMFc624. These procedures shall be discussed in greater detail below.

FIG. 7is a diagram of an embodiment of a 5G MT-LR700for a roaming UE640in a network with a distributed location management function. Prior to step5, MT-LR700may perform steps similar to steps1-4ofFIG. 2. For example, the VGMLC622may send a provide location request to the LMFc624. Steps5,7-9,12,13,14, and15ofFIG. 7may be performed in a manner similar to the corresponding steps inFIG. 2.

At step13a, the LMFc624determines where to perform LCS, locally or remotely at an LMFd, e.g., LMFd660. The LMFc624may receive a list of available LMFds prior to step13a, or may request the list as part of step13a. The LMFc624may determine that the LMFd660is available and preferable for the LCS. LMFc624may determine to use the LMFd660for LCS based upon reachability information of the UE640provided by the AMF626as part of step9and/or step13. The reachability information may include information provided with an event subscribe request that indicates the serving cell of the UE640(e.g., the NG-RAN650that the UE640is attached to). LMFc624may select the LMFd660from one or more available LMFds for LCS based upon various criteria. The criteria may include, but is not limited to, reachability information, positioning QoS (e.g., requested latency, QoS class, positioning accuracy), proximity of the requestor to the UE640, access type (e.g., third generation partnership project (3GPP), non-3GPP (N3GPP)), 5G access node type (e.g., 5G NR or eLTE), serving access node (e.g., gNB, NG-eNB) of the UE640, RAN configuration information, indication of a single LCS report or multiple LCS reports, _duration of event reporting, network slicing information (e.g., single-network slices selection assistance information (S-NSSAI), network slice instance (NSI) ID), network topology, choice of positioning method, loading on the LMFc624and/or the LMFd660, and/or capabilities of the LMFc624and/or the LMFd660. One or more of the foregoing criteria may also be used by the LMFc624in determining whether or not to perform the LCS locally at the LMFc624or remotely at the LMFd660.

At step13b, the LMFc624sends a location request to the LMFd660. The location request may include serving cell information, e.g., the cell the UE is attached to, client type, e.g., the type of UE, and/or a QoS of the LCS, or other conditions for performing the LCS. The location request may be a newly created message, the provide location request from step5, or a variation or subset of the provide location request from step5. The location request may be a Nlmf_DetermineLocation_Request service operation. From the viewpoint of the other nodes in the network, the LMFc624may act as a proxy for the LMFd660. After UE positioning is completed at step14, the LMFd660may provide positioning information to the LMFc624at step14a. The positioning information may be transmitted in a Nlmf_DetermineLocation_Response service operation. The positioning information may include a position of the UE640, or measurement results received from the UE640and/or the NG-RAN650.

The positioning operation of step14may include various interactions between the LMFd660, the NG-RAN650, and the UE640. In some embodiments, these interactions may also involve the AMF626, e.g., messages sent from the LMFd660to the NG-RAN650or the UE640may be routed by the AMF626. The interactions may be defined by positioning procedures and positioning methods. The positioning procedure may relate to which entity initiates and controls the various steps of the positioning, and where the final computation of positioning is done. Several positioning procedures are described in conjunction withFIGS. 3-5. A positioning method may relate to what types of measurements are taken and how they are processed into a position estimate. Not all positioning methods may be supported for all types of procedures. For example, OTDOA positioning (in LTE) may be UE-assisted, but may not be UE-based or network-assisted. UE-based OTDOA may be supported, but it is currently excluded from LTE. Network-assisted OTDOA may not be possible, because the positioning method may depend on having measurements from the UE. GNSS positioning may be either UE-based or UE-assisted, but may not be network-assisted because GNSS positioning may depend on measurements from the UE. E-CID may be either UE-assisted or network-assisted, but may not be UE-based.

As an example, for UL E-CID positioning, the LMFd660may interact with the NG-RAN650node to retrieve various measurements that may be used in positioning the UE640. As another example, in OTDOA positioning, the LMFd660may interact with the UE640to retrieve measurements taken on DL signals (e.g., positioning reference signals). In yet another example, for UL time difference of arrival (UTDOA), the LMFd660may interact with one or more location measurement units (LMUs) to retrieve UL measurements.

In some embodiments, the results of the positioning procedures and positioning methods may be transmitted back to the LMFc624for calculation of the position of the UE640. For example, the LMFd660may collect all the measurements and then pass them to the LMFc624which may make the final calculations of position. This may also include taking into account positioning information obtained by means of other techniques (e.g., non-3GPP methods) for a hybrid positioning result. An example hybrid positioning may include combining a wireless local area network (WLAN) positioning estimate (non-3GPP) with OTDOA measurements. In other embodiments, the LMFd660may calculate the position of the UE640and transmit only the resulting location estimate to the LMFc624.

FIG. 8is a diagram of an embodiment of distributed location management function positioning800with final calculation at the LMFc624. These steps may take place during step14ofFIG. 7. In this example, an OTDOA positioning method is used. At step1, the LMFc624submits a location request to the LMFd660. LMFd660may use LPP to request location information from the UE640at step2. UE640may determine to use OTDOA positioning and may request assistance data at step3. The assistance data may include the position of several NG-RAN650nodes used in triangulating the UE640position. The assistance data is transmitted to the UE640at step4. At step5, the UE640measures positioning reference signals (PRSs) transmitted from the NG-RAN650nodes. At step6, the UE640provides the measurements to the LMFd660. LMFd660may forward the measurements on to the LMFc624at step7. At step8, the LMFc624calculates the position of the UE640using the measurement results. At step9, the LMFc624provides the position of the UE640to the requesting GMLC (not pictured). In some embodiments, the messages at steps2,3,4, and6exchanged between the LMFd660and the UE640may be routed through the AMF (not pictured).

FIG. 9is a diagram of an embodiment of distributed location management function positioning900with final calculation at the LMFd660. These steps may take place during step14ofFIG. 7. In this example, an OTDOA positioning method is used. At step1, the LMFc624submits a location request to the LMFd660. At step2, the LMFd660uses LPP to request location information from the UE640. UE640may determine to use OTDOA positioning and request assistance data at step3. The assistance data may include the position of several NG-RAN650nodes used in triangulating the UE640position. The assistance data is transmitted to the UE640at step4. At step5, the UE640measures PRSs transmitted from the NG-RAN650nodes. At step6, the UE640provides the measurements to the LMFd660. At step7, the LMFd660calculates the position of the UE640using the measurement results. LMFd660forwards the position of the UE640to the LMFc624at step8. At step9, the LMFc624may provide the position of the UE640to the requesting GMLC (not pictured). In some embodiments, the messages at steps2,3,4, and6exchanged between the LMFd660and the UE640may be routed through the AMF (not pictured).

FIG. 10is a flowchart of an embodiment of a method1000for location services in an LMF. The method begins at block1010when an LMFc receives a location service request for a UE. The UE may be attached to a PLMN where the LMFc is located. The location request may be received from a GMLC. The GMLC may be located in the PLMN where the LMFc is located and/or may be located in a home PLMN of the UE. In some cases, the location request may originate from the UE, in these cases, the location request may be received from an AMF in the PLMN where the LMFc and the UE are located.

At block1020, the LMFc transmits a reachability request for the UE to an AMF. The reachability request verifies that the UE is reachable and requests reachability information of the UE, for example, a serving cell of the UE. At block1030the LMFc receives a reachability response comprising reachability information, for example, a serving cell identity of the UE from the AMF. At block1040, the LMFc determines whether to perform positioning procedures related to the location service request locally or to perform positioning procedures related to the location service request remotely. In an embodiment the LMFc may consider a desired positioning QoS in determining whether the LMFc or LMFd will handle the positioning request. For example, when the desired positioning QoS allows for a relatively high latency, the LMFc may handle the positioning request. Likewise, when the desired positioning QoS requires a relatively low latency, then the LMFc may decide to have the LMFd handle the positioning request. In another embodiment, the LMFc may make this determination based upon loading of the LMFc and LMFd. For example, loading may include current bandwidth usage, current processor usage, a number of pending jobs, etc. When loading is above a certain threshold at either node, the other node may be selected for handling the location service request. The LMFc may consider other criteria and/or a combination of criteria in determining whether to use an LMFd, including but not limited to LMFc and LMFd loading, UE reachability, positioning QoS, e.g., requested latency, QoS class, positioning accuracy, network topology, choice of positioning method, capabilities of the LMFc and/or LMFd, UE location in the network, and/or location of the LMFc and/or LMFd in the network.

Blocks1050through1080may be performed when the LMFs determines to perform the positioning procedures remotely at an LMFd. At block1050, the LMFc determines an LMFd to process the location service request based at least in part on the serving cell identity. Selecting an LMFd may be based upon a number of criteria to include UE location in the network, LMFd location in the network, UE reachability, positioning QoS, e.g., requested latency, QoS class, positioning accuracy, choice of positioning method, loading on the LMFd, and capabilities of the LMFd. In an embodiment, the LMF may select an LMFd based on its proximity to an NG-RAN node that serves the UE. For example, the LMFc may select an LMFd collocated with the NG-RAN node that serves the UE. In some embodiments, there may not be an LMFd at every NG-RAN node and it may be necessary to choose and LMFd based on proximity to the UE.

At block1060, the LMFc transmits the location service request to the LMFd selected at block1050. At block1070, the LMFc receives a location service result from the LMFd. The location service result may include a calculated position of the UE, or the measurements taken by the UE and/or RAN node. When the LMFd provides the measurements taken by the UE and/or RAN node, the LMFc may calculate the location of the UE based upon the measurements. At block1080, the LMFc transmits, responsive to the location service request, a UE position estimate determined based on the location service result to the requester of the position, e.g., the GMLC.

FIG. 11is a flowchart of an embodiment of a method1100for location services in an LMFd. The method1100begins at block1110where an LMFd receives a location service request for a UE from an LMFc, the location service request comprising reachability information of the UE. At block1120, the LMFd instigate positioning operations with one or more of the UE or a radio access network (RAN) node. The positioning operations may include requesting positioning measurements and/or transferring location assistance data. The positioning operations may comprise a message of an LPP protocol, e.g., a RequestLocationlnformation message or a ProvideAssistanceData message. The LMFd may determine where to send a positioning message based on the positioning procedure and/or the positioning method selected for use in the positioning operations. At block1130, the LMFd receives location information from one or more of the UE or the RAN node, e.g., measurements or a position estimate. At block1140, the LMFd transmits a location service result to the LMFc. The location service result may include measurements received form the UE and/or RAN node. The location service result may include a location of the UE calculated by the LMFd based on the location information received from the UE and/or RAN node. The location service result may include a position estimate computed by the UE.

FIG. 12is a schematic diagram of a network device1200(e.g., a network node) according to an embodiment of the disclosure. The network device1200is suitable for implementing the disclosed embodiments as described herein. In an embodiment, the network device1200may be a LMF or LMFd, or other components described herein. The network device1200may comprise ingress ports1210and receiver units (Rx)1220for receiving data; a processor, logic unit, or central processing unit (CPU)1230to process the data; transmitter units (Tx)1240and egress ports1250for transmitting the data; and a memory1260for storing the data. The network device1200may also comprise optical-to-electrical (OE) components and electrical-to-optical (EO) components coupled to the ingress ports1210, the receiver units1220, the transmitter units1240, and the egress ports1250for egress or ingress of optical or electrical signals.

The processor1230may be implemented by hardware and software. The processor1230may be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and digital signal processors (DSPs). The processor1230may be in communication with the ingress ports1210, receiver units1220, transmitter units1240, egress ports1250, and memory1260. The processor1230may comprise a LCS module1270. The LCS module1270implements the disclosed embodiments described above. For instance, the LCS module1270implements, processes, prepares, or provides the various LCS operations. The inclusion of the LCS module1270therefore provides a substantial improvement to the functionality of the network device1200and effects a transformation of the network device1200to a different state. Alternatively, the LCS module1270is implemented as instructions stored in the memory1260and executed by the processor1230.

The memory1260may comprise one or more disks, tape drives, and solid-state drives and may be used as an over-flow data storage device, to store programs when such programs are selected for execution, and to store instructions and data that are read during program execution. The memory1260may be volatile and/or non-volatile and may be read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and/or static random-access memory (SRAM).