Enhanced 5g positioning by cell selection

Abstract

A method for providing location information for a UE (User Equipment) in a radio access network, comprises receiving a plurality of cell locations and cell coverage areas corresponding to each of a plurality of cells; identifying a plurality of serving cells to which the UE is connected; identifying a minimal coverage area serving cell within the plurality of serving cells; and providing an E-CID (Enhanced Cell ID) information corresponding to the minimal coverage area serving cell, thereby replacing a primary serving cell as the source of E-CID information. To implement the method, 5G inter-CU interfaces are enhanced to enable the exchange of E-CID data between CUs. Accordingly, the serving selected for location of a UE is the one that has the smallest coverage area, regardless of the CU to which the UE is connected.

Description

Enhanced 5G Positioning by Cell SelectionBACKGROU ND OF THE INVENTIONField of invention

[0001] The present invention relates to wireless communications, and more particularly, to method for fine selection cell selection for Enhanced cell ID (E-CID) positioning methods and NR Enhanced cell ID (NR E-CID) positioning method in 5G.Related Art

[0002] The current state of 5G NR (New Radio) communications enables a given UE (User Equipment) to be simultaneously connected to multiple cells. The 5G NR specification provides for the LMF (Location Management Function) within a core network to query a given gNodeB CU (Centralized Unit) to obtain location information for a given UE connected to one or more cells within the gNodeB's coverage area. A gNodeB has a CU as well as one or more DUs (Distributed Units), each of which may manage several cells for a given coverage area and at a given frequency band.

[0003] In the case in which a given CU has multiple DUs and a given UE is simultaneously connected to multiple cells, if the LMF requests location information for a given UE, the CU will request that the primary DU obtain location information. This may be done via conventional methods according to the 5G specification, whereby the UE may measure the strength and quality of certain received signals from its serving cell under the primary serving cell, and report this information to the primary DU so that the primary DU may report the measured location information to the LMF.

[0004] There are certain deficiencies to the conventional process. First, in the case in which UE is simultaneously connected to cells of multiple DUs under a single CU, the serving cell under the primary DU may operate at a lower frequency band, e.g. FR 1 (Frequency Range 1), that results in the serving cell having a very large coverage area. In this case, the accuracy of the measured location is limited due to the large extent of the service cell's coverage area. This is particularly disadvantageous if the UE is simultaneously connected to a secondary cell that operated in a much higher frequency (e.g., FR 2) whereby the coverage area of the secondary cell is muchsmaller, and thus its location measurement will be correspondingly better. Currently there is no way for a CU to select which cell, and from which DU, to have obtain the most accurate location measurement possible.

[0005] Second, in the case in which a UE is simultaneously connected to multiple cells that are under more than one CU, there is currently no way for a primary CU to relay a location measurement request from the LMF to a secondary connected CU if the UE is connected to a smaller-area cell under that CU. In this case, especially in the case of a broadly-dispersed set of cell groups that require multiple CUs, being limited to only the primary serving cell of the primary CU hinders the ability to provide more accurate location information for the UE.

[0006] Accordingly, what is needed is a method by which a CU may select the smallest coverage area cell for requesting UE location measurements, and a method by which a primary CU may relay a location measurement request from the LMV to a secondary CU having a serving cell with a smaller coverage area.SU MMARY OF THE INVENTION

[0007] An aspect of the present disclosure is a method providing location information for a UE (User Equipment) in a radio access network. The method involves storing information for each of a plurality of cells, the information including a cell identity, a cell location, and a cell coverage area corresponding to each of the plurality of cells. The method further involves identifying, among the plurality of cells, first and second serving cells to which the UE is connected, and identifying one of the first serving cell and the second serving cell as having the smaller cell coverage area based on the stored information. Then, UE location information is obtained based on the UE location in the serving cell identified as having the smaller cell coverage area; and providing the UE location information and the stored cell identity corresponding to one of the first serving cell and the second serving cell, whichever is identified as having the smaller cell coverage area.

[0008] Another aspect of the present disclosure is a radio access network (RAN) that comprises one or more distributed units (DUs) collectively generating a plurality of cells, including both a first serving cell and a second serving cell to which a UE is connection. The RAN further comprises a centralized unit (CU) that is configured to store information, received from the one or more DUs, for each of the plurality of cells, the stored information including a cell identity, a cell location, and a cell coverage area corresponding to each of the plurality of cells. The CU isfurther configured to identify the first and second serving cells amongst the plurality of cells, and to identify one of the first serving cell and the second serving cell as having the smaller cell coverage area based on the stored information; obtain location information for the UE, the location information being the UE location in the serving cell identified as having the smaller cell coverage area, from one of the one or more DUs, whichever generated the serving cell identified as having the smaller cell coverage area; and provide, to a core network, the obtained UE location information and the stored cell identity corresponding to the serving cell identified as having the smaller cell coverage area.BRI EF DESCRI PTION OF DRAWINGS

[0009] FIG. 1 illustrates a single-DU RAN operating cells of different coverage areas.

[0010] FIG. 2 illustrates an exemplary process for providing improved 5G positioning in case of multiple serving cells, a single DU, and a single CU according to the disclosure.

[0011] FIG. 3 illustrates a multi-DU RAN operating cells of different coverage areas.

[0012] FIG. 4 illustrates an exemplary process for providing improved 5G positioning in case of multiple serving cells, multiple DUs, and a single CU according to the disclosure.

[0013] FIG. 5 illustrates an exemplary RAN having a primary and a secondary gNodeB according to the disclosure.

[0014] FIG. 6 illustrates an exemplary process for providing improved 5G positioning in a RAN having multiple gNodeBs according to the disclosure.DETAI LED DESCRIPTION OF TH E I NVENTION

[0015] FIG. 1 illustrates a single gNB RAN 100 operating cells of different coverage areas. RAN 100 includes a gNodeB CU 115, which is coupled with a gNodeB DU 120 over an Fl interface 135. DU 120 has the necessary radios and antennas to generate a cell group having cells A, B, C, and D. Cells A, B, C may operate in the FR2 (Frequency Range 2) bands ranging from 24.25 GHz to 71.0 GHz , while Cell D may operate in the FR1 frequency bands ranging from 410 MHz to 7125 MHz. Given the physics of RF (Radio Frequency) propagation, the FR2 cells A / B / C have a smaller coverage area than FR1 cells D.

[0016] CU 115 is coupled to AMF (Access & Mobility Function) module 110 over an NG (Next Generation) interface 130. AMF module 110 is coupled to LMF (Location Management Function) module 105 over an NLs interface 107, as defined by the 3GPP (Third Generation PartnershipProject) specification. NG interface 130 carries NRPPa (New Radio Positioning Protocol A) information, which provides AMF module 110 and LMF module 105 location information for the UEs connected to gNB CU 115.

[0017] In the illustrated example, FR2 cell A overlaps with the coverage area of FR1 cell D. Further to the illustrated example, a UE 125 is connected to Cell D as primary cell and to Cell A as secondary cell.

[0018] As used herein, the term "software module" or "module" may refer to a set of machine- readable instructions that are encoded within one or more non-transitory memory devices and executed on one or more processors that host the illustrated components, including LMF module 105, AMF module 110, the software-implemented functionality of gNB CU 115, and the software-implemented functionality of DU 120. As used herein, the term "non-transitory memory" may refer to any tangible storage medium (as opposed to an electromagnetic or optical signal) and refer to the medium itself, and not to a limitation on data storage (e.g., RAM vs. ROM). For example, non-transitory medium may refer to an embedded memory that is encoded with instructions whereby the memory may have to be re-loaded with the appropriate machine-readable instructions after being power cycled. Further, if an action is described herein as being done by a referenced module (e.g., "DU 120 identifies the serving cell with the smallest coverage area..."), it will be understood that this may describe that one or more processors executing the module's machine-readable instructions to perform that particular action.

[0019] FIG. 2 illustrates an exemplary process 200 for providing improved 5G positioning according to the disclosure.

[0020] In step 205, CU 115 receives CGI (Cell Global Identity), locations, and coverage areas for FR1 cell D and FR2 cells A / B / C from DU 120. This may be done according to existing 3GPP mechanisms. In particular, CGI and coverage areas of the DU served cells may be signaled to the CU during the Fl Setup Request procedure performed during the initial setup of the Fl link. On the other hand, the CU may obtain the CGI and cell locations via the TRP (Transmission Reception Point) Information Exchange procedure defined for the F1AP (control plane signaling protocol).

[0021] In step 210, CU 115 stores the information and builds a table of cell locations and coverage areas per cell. Accordingly, for each of cells A / B / C / D, CU 115 maintains information including cell location and coverage area.

[0022] Steps 205 and 210 may be executed whenever the DU is configured, reconfigured, or CU 115 is restarted. An example would be during an initial Fl setup request.

[0023] In step 215, CU 115 receives E-CID Measurement Initiation Request from the LMF requesting location information regarding UE 125. As illustrated, UE 125 is connected to both FR1 cell D and FR2 cell A via Carrier Aggregation. The CU 115 then proceeds to fetch the requested location information from DU 120. This is accomplished accordingly to the procedures defined by the Fl protocol. DU 120 may have a software module that, based on the cell coverage areas, identifies the Cell A as the UE 125 serving cell with the smallest coverage area. Due to the smaller coverage area, the location information obtained from the FR2 Cell A will be more accurate than the one that would be obtained from the FR1 cell D.

[0024] In step 225, DU 120 reports back to CU 115 the E-CID information alongside the cell location for the serving cell with the smallest coverage area. Due to the F1AP, the DU response message doesn't specify the CGI of the serving cell, as is done conventionally. According to the disclosure, CU 115 identifies the correct CGI based on the cell location provided by DU 120 in the E-CID response message and the coverage area and location table obtained in Step 205. In step 225, CU 115 reports the E-CID information for the serving cell with the smallest coverage area. It may do so according to the NRPPA protocol over NG interface 130.

[0025] FIG. 3 illustrates a multi-DU RAN 300 operating cells of different coverage areas. RAN 300 includes a gNodeB CU 115, which is coupled to two gNodeB DUs 120a and 120b over respective Fl interfaces 135a and 135b. DU 120a has the necessary radios and antennas to generate a first cell group having cells A, B, and C. DU 120a may operate in the FR1 (Frequency Range 1) bands ranging from 410 MHz to 7125 MHz. DU 120b has the necessary radios and antennas to generate a second cell group having cells D, E and F. DU 120b may operate in the FR2 frequency bands ranging from 24.25 GHz to 71.0 GHz. Given the physics of RF (Radio Frequency) propagation, the FR2 cells D / E / F have smaller coverage areas than FR1 cells A / B / C.

[0026] CU 115 is coupled to AMF (Access & Mobility Function) module 110 over an NG (Next Generation) interface 130. AMF module 110 is coupled to LMF (Location Management Function) module 105 over an NLs interface 107, as defined by the 3GPP (Third Generation Partnership Project) specification. NG interface 130 carries NRPPa (New Radio Positioning Protocol A) information, which provides AMF module 110 and LMF module 105 location information for the UEs connected to gNB CU 115.

[0027] In the illustrated example, FR2 cells D / E / F overlap with the coverage area of FR1 cell C.Further to the illustrated example, a UE 125 is connected to DU 120a through cell C, and to DU120b through cell D. In this case, both cells C and D are serving cells of UE 125.

[0028] FIG. 4 illustrates an exemplary process 400 for providing improved 5G positioning in case of multi DUs according to the disclosure.

[0029] In step 405, CU 115 receives cell locations and CGI, coverage areas, locations for FR1 cells A / B / C from DU 120a, and for FR2 cells D / E / F from DU 120b . This may be done according to existing 3GPP mechanisms, such as the F1AP Fl SETUP REQUEST AND OR F1AP GNB-DU CONFIGURATION UPDATE procedure. In particular, CGI and coverage areas of the served cells of DU 120a and 120b is signaled to the CU 115 during the Fl Setup Request procedure performed during the initial setup of Fl interface 135a / b. On the other hand, CU 115 may obtain the CGI and location via the TRP Information Exchange procedure defined for the F1AP.

[0030] In step 410, CU 115 stores the information and builds a table of CGI, locations, and coverage areas per cell. Accordingly, for each of cells A / B / C and D / E / F, CU 115 maintains this information.

[0031] Steps 405 and 410 may be executed whenever multi-DU RAN 300 is configured, reconfigured, or CU 115 is restarted. An example would be during an initial Fl setup request.

[0032] In step 415, CU 115 receives an E-CID Measurement Initiation Request from the LMF requesting location information regarding UE 125. As illustrated, UE 125 is connected to both FR1 cell C and FR2 cell D in intra CU NR-DC (New Radio Dual Connectivity). CU 115 may have a software module that, based on the cell table built in step 310, identifies DU 120b as the DU having the UE 125 serving cell with the smallest coverage area. The CU 115 then proceeds to fetch the requested location information from the DU 120b. This is accomplished accordingly to the procedures defined by the Fl protocol. Due to the smaller coverage area, the location information obtained from the FR2 Cell D will be more accurate than the one that would be obtained from the FR1 cell C.

[0033] In step 420, CU 115 obtains the location information from the selected DU 120b and determines the serving CGI based on the table built in step 405.

[0034] In step 425, CU 115 reports the E-CID information for the serving cell with the smallest coverage area. It may do so according to the NRPPA protocol over NG interface 130.

[0035] FIG. 5 illustrates a multi-CU RAN 500 according to the disclosure. In this variation, there is a primary gNB CU 515a and a secondary gNB CU 515b that are mutually coupled over an XnAP(Xn Application Protocol) interface 530. Coupled to primary CU 515a is a DU 120a; and coupled to secondary CU 515b is a DU 120b. DUs 120a / b may be similar to those of multi-DU RAN 300 in that DU 120a supports FR1 cells A / B / C, and DU 120b supports FR2 cells DEF. Cells A / B / C and D / E / F in multi-CU RAN 500 may be substantially similar to the corresponding cells in multi-DU RAN 100. Primary CU 515a is coupled to DU 120a over Fl interface 535a, and secondary CU 515b is coupled to DU 120b over Fl interface 535b.

[0036] XnAP interface 530 may be augmented to allow NRPPa messages to be exchanged between primary CU 515a and secondary CU 515b. This may be done by transmitting the NRPPa messages over open vendor-specific data fields that are available within XnAP interface definition. The XnAP messages may be used to send an vendor-specific Information Element (IE) appended to an existing Xn S-NODE MODIFICATION REQUEST and Xn S-NODE MODIFICATION REQUEST ACKNOWLEDGMENT to piggyback NRPPa messages (i.e., E-CID related messages) between primary CU 515a and secondary CU 515b.

[0037] Primary CU 515a may be coupled to AMF module 110 over an NG interface 130, similar to the corresponding portion of multi-DU RAN 300. In a further similarity to multi-DU RAN 300, AMF module 110 is coupled to LMF module 105 over an NLs interface 107.

[0038] Primary CU 515a may request E-CID information from secondary CU 515b over XnAP interface 530, as described below.

[0039] Primary CU 515a may be configured to store cell locations and cell coverage areas for not only its cells A / B / C, but also the cell locations and cell coverage areas for cells D / E / F of secondary CU 515b. This may be done by a software module within primary CU 515a.

[0040] XnAP interface 530 may be supplemented to include NRPPa information, similar to the NRPPa information relayed over NG interface 130. This may enable the exchange of E-CID information between primary CU 515a and secondary CU 515b

[0041] FIG. 6 illustrates an exemplary process 600 for providing improved 5G positioning in using multi-CU RAN 500 according to the disclosure.

[0042] In step 605, primary CU 515a receives locations and coverage areas for its cells A / B / C from DU 120a. This may be done according to existing 3GPP mechanisms.

[0043] In step 607, secondary CU 515b receives locations and coverage areas for its cells D / E / F from DU 120b. Further to step 607, secondary CU 515b relays its cell location and coverage area information (for cells D / E / F) to primary CU 515a.

[0044] In step 610, primary CU 515a stores the cell location and coverage area information, along with an indication of which CU 515a / 515b corresponds to each cell, for cells A / B / C / D / E / F.

[0045] Steps 605, 607, and 610 may be executed each time multi-CU RAN 500 is configured, reconfigured, or when primary CU 515a and secondary CU 515b are restarted. An example would be during an initial XN and Fl setup request.

[0046] Steps 615 onward may be performed during nominal operation of multi-CU RAN 500.

[0047] In step 615, primary CU 515a receives E-CID Measurement Information request from the LMF for UE 125 connected in NR-DC (New Radio Dual Connectivity). This may be done according to conventional 3GPP procedures.

[0048] In step 620, primary CU 515a determines if the serving cell with the smallest coverage area is served by itself or by the secondary CU 515a based on the table built in step 610. Further to step 625, one of the two sub-steps may be performed.

[0049] In step 630, primary CU 515a identifies that the serving cell with the smallest coverage area is served by secondary CU 515b. In this case the primary CU 515a relays the NRPPa E-CID request message received by the LMF module to secondary CU 515a. The NRPPa message may be piggybacked (the whole NRPPa message is encoded in a data field of an another message) on already defined XnAP messages (i.e., S-NODE Modification procedure messages) using vendor specific data fields. Secondary CU 515b, aware of the insertion of the vendor specific data fields in the XnAP message, receives the piggybacked E-CID measurement request, performs the required actions, and responds to primary CU 515a. Once it has obtained the response from secondary CU 515b, primary CU 515a responds back to the LMF 105, using standard 3GPP procedures.

[0050] Primary CU 515a and secondary CU 515b may signal to each other the capability of decoding the augmented XnAP messages using vendor specific data field inserted in the initial Xn Setup messages.

[0051] Returning to step 625 and going through step 635, primary CU 515a is the CU with the cell with the smallest coverage area. Primary CU 515a initiates an E-CID measurement request to its associated DU 120a. If more serving cells are present in the primary DU 120a, the method presented in 100 can be used. Once the primary CU 515a receives the requested location information from the DU 120a, it reports to the LMF 105 via the AMF 110 module. This can be done via standardized 3GPP procedures.

[0052] In the illustrated example in FIG. 5, serving cell D, under DU 120b and secondary CU515b, has the smallest coverage area of the cells connected to UE 125. In this example, process 400 would proceed through step 625 to step 630.

[0053] This contrasts with conventional procedures, in which a CU will report the E-CID for the primary serving cell, regardless of cell coverage size and thus accuracy of location information.

Claims

What is Claimed Is1. A method for providing location information for a UE (User Equipment) in a radio access network, comprising: storing information for each of a plurality of cells, the information including a cell identity, a cell location, and a cell coverage area corresponding to each of the plurality of cells; identifying, among the plurality of cells, first and second serving cells to which the UE is connected; identifying one of the first serving cell and the second serving cell as having the smaller cell coverage area based on the stored information; obtaining UE location information based on the UE location in the serving cell identified as having the smaller cell coverage area; and providing the UE location information and the stored cell identity corresponding to one of the first serving cell and the second serving cell, whichever is identified as having the smaller cell coverage area.

2. The method of claim 1, wherein the UE location information comprises E-CID (Enhanced Cell Identity) information.

3. The method of claim 2, wherein the cell identity is a GCI (Global Cell Identity).

4. The method of claim 3 further comprising: receiving, by a central unit (CU) in the RAN, the stored information from a distributed unit (DU) generating both the first and second serving cells, wherein obtaining the E-CID information comrprises obtaining, by the CU from the DU, the E-CID information, and wherein providing the E-CID information and the stored cell identity comprises providing, by the CU, the E-CID information and the stored cell identity to a core network. io5. The method of claim 4, wherein the one serving cell, amongst the first serving cell and the second serving cell, identified as having the smaller cell coverage area is a secondary serving cell and the other serving cell is the primary serving cell.

6. The method of claim 3 further comprising: receiving, by a central unit (CU) in the RAN, the stored information from a first distributed unit (DU) generating the first serving cell and from a second second DU generating the second serving cells, wherein obtaining the E-CID information comrprises obtaining the E-CID information by the CU from one of the first DU and the second DU, whichever one generated the serving cell identified as having the smaller cell coverage area, and wherein providing the E-CID information and the stored cell identity comprises providing, by the CU, the E-CID information and the stored cell identity to a core network.

7. The method of claim 3 further comprising: receving, by a first central unit (CU) in the RAN, the stored information from a first distributed unit (DU) generating the first serving cell and from a second CU in communication with a second DU generating the second serving cell, wherein obtaining the E-CID information comprises obtaining the E-CID information by the first CU from one of the first DU and the second DU via the second CU, whichever one generated the serving cell identified as having the smaller cell coverage area, and wherein providing the E-CID information and the stored cell identity comprises providing, by the first CU, the E-CID information and the stored cell identity to a core network.

8. The method of claim 7, wherein the second serving cell, amongst the first and second serving cells, is identified as having the smaller cell coverage area, and wherein the first CU queries the second CU for the E-CID information associated with the second serving cell by leveraging an augmented XnAP message.

9. The method of claim 8, wherein the obtained E-CID information from the second CU involves piggybacking a NRPPa (New Radio Positioning Protocol A) E-CID message on a standard XnAP message.

10. A radio access network (RAN) comprising: one or more distributed units (DUs) collectively generating a plurality of cells, including both a first serving cell and a second serving cell to which a UE is connection; and a centralized unit (CU) configured to: store information, received from the one or more DUs, for each of the plurality of cells, the stored information including a cell identity, a cell location, and a cell coverage area corresponding to each of the plurality of cells; identify the first and second serving cells amongst the plurality of cells; identify one of the first serving cell and the second serving cell as having the smaller cell coverage area based on the stored information; obtain location information for the UE, the location information being the UE location in the serving cell identified as having the smaller cell coverage area, from one of the one or more DUs, whichever generated the serving cell identified as having the smaller cell coverage area; and provide, to a core network, the obtained UE location information and the stored cell identity corresponding to the serving cell identified as having the smaller cell coverage area.

11. The network of claim 10, wherein the UE location information comprises E-CID (Enhanced Cell ID) information.

12. The network of claim 11, wherein the cell identity is a GCI (Global Cell Identity).

13. The network of claim 12, wherein one DU generates both the first and second serving cells and the CU obtains the E-CID information from the one DU.

14. The network of claim 13, wherein the serving cell, amongst the first serving cell and the second serving cell, identified as having the smaller cell coverage area is a secondary serving cell and the other serving cell, amongst the first serving cell and the second serving cell, is the primary serving cell.

15. The network of claim 12,wherein the one or more DUs comprise a first DU configured to generate the first serving cell and and a second DU configured to generate the second serving cell, wherein the CU is further configured to obtain the E-CID information from one of the first DU and the second DU, whichever one generated the serving cell, amongst the first and second serving cells, identified as having the smaller cell coverage area.

16. The network of claim 15, wherein the CU is a first CU, and wherein the network further comprises a second CU in communication with the first CU, and wherein the first CU is in communication with the second DU via the second CU.

17. The network of claim 16, wherein the second serving cell, amongst the first and second serving cells, is identified as having the smaller cell coverage area, and wherein the first CU is further configured to query the second CU for the E-CID information associated with the second serving cell by leveraging an augmented XnAP message.

18. The network of claim 17, wherein the obtained E-CID information from the second CU involves piggybacking a NRPPa (New Radio Positioning Protocol A) E-CID message on a standard XnAP message.

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