OA19294A - Method for detection of a narrowband positioning reference signal (Nprs) location in a radio frame. - Google Patents

Abstract

Embodiments of the disclosure provide methods and apparatus for positioning in a wireless network. One embodiment provides a method, performed by a target device, for enabling detection of a narrowband positioning reference signal, NPRS, location in a radio frame. The method comprises: obtaining (100), from a location server, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell, determining (110) a time of a NPRS subframe for the neighbour cell and/or NPRS sequence based on the timing offset information, measuring (120) a positioning reference signal (PRS) based on the determined time, and reporting (130) the measured PRS to the location server.

Description

Embodiments herein relate to an exchange of messages/indications between a target device, such as e.g. NB-loT, and a network node in order to retrieve a NPRS location in a radio frame based on a reported timing offset for performing positioning reference signal measurements, from which for example the reference signal time différence (RSTD) may be determined. This may further be complemented with signaling between a positioning node, or location server, and a radio network node transmitting NPRS. The timing offset may comprise a subframe offset or a system frame number (SFN) offset, or both.

The target device may for example be a wireless communication device, a mobile station, a station (STA), a user equipment (UE) and/or a NB-loT device.

The network node may for example be a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a “NodeB” or “eNodeB”.

Three different alternative embodiments, which may herein also be referred to as parts, for NPRS configuration for NB-loT devices hâve been agreed upon in Rel.14. Where the timing offset comprises a subframe offset, the définition of the subframe offset may be different for each embodiment. This aspect is described in greater detail below with respect to Figures 8 to 10. The target device may further require to receive the SFN offset for ail the three different types of NPRS configuration. The SFN offset may define an offset in system frame number between a particular cell and a reference or serving cell.

Embodiments herein relate to a target device, a location server, a network node and methods therein, see Figure 4, Figure 5, Figure 6, Figure 11, Figure 12 and Figure 13. Dashed lines in the figures indicate that these boxes are optional.

A first aspect of embodiments relating to a method, performed by a target device (i.e. a wireless device which is the subject of a positioning method), for enabling détection of a NPRS location in a radio frame, will now be described with reference to the flowchart depicted in Figure 4. The method may comprise the following actions, which actions may be taken in any suitable order.

Action 100: The target device may obtain, from the location server, assistance data, which may comprise NPRS configuration and timing offset information related to each cell within a reference and neighbour cell list. The timing offset information may comprise, e.g., SFN for a cell; SFN offset for a cell with respect to a reference time or another cell e.g. reference or serving cell; subframe offset for a cell with respect to a reference time of another cell e.g. reference or serving cell; or an indication whether for one, some, or ail cells the timing offset information is the same as or different than that of a reference or serving cell. In a spécifie example, neighbour cells may be intra-frequency cells.

Action 110: The obtained assistance data, such as e.g. the timing offset information may be used by the target device to détermine the time of NPRS subframe in each neighbour cell and/or NPRS sequence.

Action 120: The target device may perform positioning reference signal measurements based on the determined time of the NPRS subframe.

Action 130: The target device may report the positioning reference signal measurements to the location server.

In some embodiments, the positioning reference signal measurements may be represented by a Reference Signal Time Différence (RSTD) in the report to the location server. The actions performed by the target device are described in more detail in subséquent sections.

A second aspect of embodiments relating to a method, performed by a location server, for enabling détection of a NPRS location in a radio frame by a target device, will now be described with reference to the flowehart depicted in Figure 5. The method may comprise the following actions, which actions may be taken in any suitable order.

Action 200: The location server may obtain, from a network node, timing offset information related to a neighbour cell (e.g. a cell served by the network node) to be included in assistance data to be sent to a target device. The neighbour cell may belong to a reference and neighbour cell list. The timing offset information may comprise one or more of: SFN for the neighbour cell; SFN offset for the neighbour cell with respect to a reference time or another cell e.g. reference or serving cell; subframe offset for the neighbour cell with respect to a reference time of another cell e.g. reference or serving cell.

Action 210: The location server may send the assistance data, which may comprise the timing offset information together with other NPRS configuration of each reference and neighbour cell in the reference and neighbour cell list, to the target device. As noted above, this ¹⁰ assistance data may be utilized by the target device to détermine an NPRS location in a radio frame for the neighbour cell, and to measure the PRS transmitted by the network node.

Action 220: The location server may receive positioning reference signal measurements from the target device.

In one embodiment, the positioning reference signal measurements may be represented by RSTDs in the measurement reports. The different embodiments are further discussed in subséquent sections.

A third aspect of embodiments relating to a method, performed by the network node, for enabling détection of a NPRS location in a radio frame by a target device, will now be described with reference to the flowchart depicted in Figure 6. The method may comprise the following actions, which actions may be taken in any suitable order.

Action 300: The network node may receive a request from a location server for assistance data related to a cell served by the network node.

Action 310: The network node may provide to the location server, the requested assistance data for the cell served by the network node. The assistance data may comprise timing offset information, for example, SFN for the cell served by the network node; SFN offset for the cell with respect to a reference time or another cell e.g. reference or serving cell; subframe offset for the cell with respect to a reference time of another cell e.g. reference or serving cell.. The assistance data may then be transmitted by the location server to the target device, to enable the target device to détermine the NPRS location for the cell served by the network node.

The different embodiments are described in more detail in this section. The following has been agreed upon for time resource configuration of NPRS:

• Configuration of time resources for NPRS

- Indication of exact subframes may be performed by:

> Example embodiment A/Part A: A bitmap indicating subframes which are not NB-loT DL subframes (also referred to as invalid DL subframes).

- The bitmap may be of a fixed length of 10 bits. Alternatively, the bitmap may be of the same length as valid subframe configuration, such as e.g. 10 bits or 40 bits. In a further alternative, the bitmap may be of a fixed length of x bits, such as e.g., x = 20.

> Example embodiment B/Part B: Indicated with one start subframe, one periodicity, and one number of répétitions for the occasions.

> Example embodiment C/Part C: A combination of Part A and Part B

Subframe offset définition

The définition of the subframe offset may be different for each part defined in the agreement, therefore here this définition is explained explicit to each part and compared with the legacy LTE case, in which this information was not required. Hence, in the following the subframe offset définition is explicitly discussed for each part of the agreement and compared with the legacy scénario.

In some embodiments, if the OTDOA assistance data further relates to positioning-only TPs or other radio nodes which may not be associated with any cell and/or may not transmit System information but may still transmit positioning signais, such as e.g., NPRS, one or more of the following solutions may be implemented:

• Timing offset information may not be provided for these TPs. Instead, spécifie PRS configurations may be provided.

• a random number within an SFN or subframe range or an SFN or subframe offset range may be used as the SFN or subframe offset for these TPs.

• a pre-defined number within an SFN or subframe range or an SFN or subframe offset range may be used as the SFN or subframe offset for these TPs.

• a number derived based on a pre-defined rule may be used as the SFN or subframe offset for these TPs.

• a number received in or derived based on a message received from a network node may be used as the SFN or subframe offset for these TPs.

These numbers may then be used as timing offset information for nodes transmitting the positioning signais.

No need for subframe offset for LTE

In LTE the maximum différence between the transmitted PRS positioning occasions cannot exceed half a subframe, which is less than 1 ms. Therefore even in the case where an idéal alignment is not considered, which is shown in the left picture in Figure 7, it is still possible ¹² for the target device to détermine the PRS subframe in both the reference cell and in the neighbour cells.

Subframe offset for Part A NPRS configuration

In Part A, the NPRS may be sent as a fixed length bitmap indicating subframes which are not NB-loT DL subframes (also referred to as invalid DL subframes). While the target device is able to dérivé the subframes in which the NPRS is transmitted from such a bitmap, it is not possible for the target device to know the subframe offset between the two cells.

According to the large periodicity values considered for NB-loT devices, the misalignment of subframes may not be in the scale of less than 1 ms, but may actually be 16 ms, which is an unneglectable value in terms of NPRS détermination.

In one embodiment, the location server may send the subframe number and/or SFN of each cell along with the list of reference and neighbour cells. In another embodiment, the offset between the subframe numbers or SFNs of each cell in comparison to a reference cell may be reported to the target device. As the target device has the subframe number and SFN of the serving cell, one embodiment may be to consider that the reference cell in this context may be the serving cell.

In figure 8, the NPRS is sent in the diagonally striped blocks in each PRS occasion for the reference cell in the upper line and for a neighbour cell in the lower line. The subframe offset is identified in the same figure as the time différence between the NPRS sent for the reference cell and the neighbour cell. Once the subframe offset is reported to the target device, the same value may be used for ail PRS occasions.

Subframe offset for Part B NPRS configuration

Part B NPRS configuration may be defîned as follows:

• Additionally or altematively, an NB-loT device, such as a UE, may receive assistance information regarding 1-PRB NPRS

- For Part-B NB-loT spécifie assistance information:

• Periodicity of NPRS occasion T: 160ms, 320ms, 640ms, 1280ms.

• Number of subframes of NPRS in one occasion:

- {20, 40, 80, 160} for 160ms periodicity;

- {40, 80, 160, 320} for 320ms periodicity;

- {80, 160, 320, 640} for 640ms periodicity;

- {160, 320, 640, 1280} for 1280ms periodicity.

• For a given periodicity of NPRS occasion, the starting subframe offset of ? R 4 R ή 7 NPRS occasion = aT, « {0,-,-,-,-,-,-,-, 1} O O O O O O O

Although the subframe offset may be considered to be reported for a given periodicity, this may however still not fix the issue with SFN or subframe non alignment.

Accordingly, in one embodiment herein, as with the Part A embodiments described above, the location server may send the SFN or subframe number of each cell along with the list of reference and neighbour cells to the target device. In another embodiment, the offset between the SFN or subframe numbers of each cell in comparison to a reference cell may be reported to the target device. Since the target device has the SFN and subframe number of the serving cell, one embodiment may be to consider that the reference cell in this context would be the serving cell.

In figure 9, the NPRS is sent in the diagonally striped blocks for the first cell shown in the upper line, such as e.g. the reference cell, while NPRS is sent in the vertically striped blocks in a neighbour cell shown in the lower line. While according to Part B, the starting subframe offset may be reported to the target device (i.e. the subframe offset of an initial NPRS occasion), one or more of the subframe number or SFN offset may also be reported to the target device according to the figure 9. Once the subframe number or SFN offset is reported to the target device, the same value may be used in ail PRS occasions.

Subframe offset for Part C NPRS configuration

Part C is a combination of Part A and Part B. Thus, a cell may be configured according to both Part A and Part B, with NPRS transmissions occurring in a particular subframe if one or both of the Part A and Part B configurations indicates so. In Part C each fixed-size bitmap (i.e. as defined above for Part A) may consist of a 10 bit bitmap. As with the discussion above, the target device in Part C is not aware of the SFN or subframe number offset between the cells. The value of the misalignment may herein also not be unneglectable, but may be at least 16 times more than what is possible in LTE.

In one embodiment herein, as with Part A and Part B embodiments described above, the location server may send one or more of the SFN and the subframe number of each cell along with the list of reference and neighbour cells to the target device. In another embodiment, one or more of the offsets between the SFN and the subframe number of each cell in comparison to a reference cell may be reported to the target device. Since the target device may hâve the SFN and subframe number of the serving cell, one embodiment may be to consider that the reference cell in this context may be the serving cell.

Figure 10 exemplifies the SFN or subframe number offset for the Part C NPRS 5 configuration. The NPRS are sent in some subframes included in the shaded blocks for the reference cell, while other bitmap configurations are used for the neighbour cell in the lower line. Once the SFN or subframe number offset is reported to the target device, the same value can be used in ail PRS occasions.

Multiple PRS configurations

Hitherto, the description has focused on one single PRS configuration. However, the target device may receive more than one PRS configuration.

In one mode, the target device may be configured with multiple PRS configurations, but only one set or piece of timing offset information for a spécifie entity, such as e.g a node, a cell, a transmission point, etc, which implies that the set or piece of timing offset information may be considered or indicated as applicable to ail PRS configurations (e.g., together with preconfigured offsets). For example, the offset may be based on the type of the LTE narrowband technique that the PRS configuration is associated with.

In another mode, one ofthe PRS configurations may be utilized for NB-loT transmissions, and another of the PRS configurations may relate to LTE or narrowband versions of LTE with spécifie focus on bandwidth reduced low complexity (BL) devices, possibly also with coverage extension (CE) components such as répétitions of signais and data.

Figure 11 is a schematic illustration of a target device 1100 according to embodiments of the disclosure. The target device 1100 comprises a processor 1102, and memory 1104. Embodiments described herein (e.g. the method described above with respect to Figure 4) may be implemented through the processor 1102 executing computer program code stored on the memory 1104 for performing the methods set out herein.

The processor 1102 may comprise one or more modules for performing the methods set out herein. For example, the processor 1102 may comprise an obtaining module 1106, a determining module 1108 and a measuring module 1110. The obtaining module 1106 may be configured to obtain, from a location server, assistance data related to a neighbour cell in a reference and neighbour cell list. The assistance data may comprise timing offset information for the neighbour cell, such as an SFN offset and/or a subframe offset. The obtaining module 1106 may comprise a receiving module 1112 for receiving the timing offset information from the location server. The determining module 1108 may be configured to détermine a time of a NPRS subframe for the neighbour cell and/or a NPRS sequence based on the timing offset information. The measuring module 1110 may be configured to measure a positioning reference signal (PRS) or NPRS based on the determined time. The obtaining module 1106 may comprise a sending module 1114 configured to report the measured PRS to the location server.

¹⁶

The computer code may be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the methods described above (e.g. with respect to Figure 4); the computer code may be provided to or downloaded by the target device 1100.

The memory 1104 may be arranged to be used to store obtained information such as assistance data, timing offset information, other NPRS configuration, indications of a mobility set, identifiers of APs and WLANs, identifiers of UEs, ciphering keys, measurements of signais from radio access nodes, measurement reports or parts thereof and applications etc. to perform the methods herein when being executed in the target device 1100.

Figure 12 is a schematic illustration of a target device 1200 according to embodiments of the disclosure. The target device 1200 comprises processing circuitry 1202, and memory 1204. Embodiments described herein (e.g. the method described above with respect to Figure 4) may be implemented through the processing circuitry 1202 executing computer program code stored on the memory 1204 for performing the methods set out herein.

Figure 13 is a schematic illustration of a location server 1300 according to embodiments of the disclosure. The location server 1300 comprises a processor 1302, and memory 1304. Embodiments described herein (e.g. the method described above with respect to Figure 5) may be implemented through the processor 1302 executing computer program code stored on the memory 1304 for performing the methods set out herein.

The processor 1302 may comprise one or more modules for performing the methods set out herein. For example, the processor 1302 may comprise an obtaining module 1306, a transmitting module 1308 and a receiving module 1310. The obtaining module 1306 may be configured to obtain, from a network node, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell. The transmitting module 1308 may be configured to transmit, to a target device, the assistance data related to the reference and neighbour cell list. The receiving module 1310 may be configured to receive, from the target device, a measured positioning reference signal, or a report relating to a measured positioning reference signal.

The computer code may be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the methods described above (e.g. with respect to Figure 5); the computer code may be provided to or downloaded by the location server 1300.

The memory 1304 may be arranged to be used to store obtained information such as assistance data, timing offset information, other NPRS configuration, indications of a mobility set, identifiers of APs and WLANs, identifiers of UEs, ciphering keys, measurements of signais from radio access nodes, measurement reports or parts thereof and applications etc. to perform the methods herein when being executed in the location server 1300.

In some embodiments the location server 1300 may be embodied in a network node.

Figure 14 is a schematic illustration of a location server 1400 according to embodiments of the disclosure. The location server 1400 comprises processing circuitry 1402, and memory 1404. Embodiments described herein (e.g. the method described above with respect to Figure 5) may be implemented through the processing circuitry 1402 executing computer program code stored on the memory 1404 for performing the methods set out herein.

Figure 15 is a schematic illustration of a network node 1500 (e.g. a radio access network node such as a base station or eNB, etc) according to embodiments of the disclosure. The network node 1500 comprises a processor 1502, and memory 1504. Embodiments described herein (e.g. the method described above with respect to Figure 6) may be implemented through the processor 1502 executing computer program code stored on the memory 1504 for performing the methods set out herein.

The processor 1502 may comprise one or more modules for performing the methods set out herein. For example, the processor 1502 may comprise a receiving module 1506 and a transmitting module 1508. The receiving module 1506 may be configured to receive, from a location server, a request for assistance data related to a cell served by the network node. The transmitting module 1508 may be configured to transmit, to the location server, the assistance data related to the cell served by the network node, wherein the assistance data comprises timing offset information for the cell.

The computer code may be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the methods described above (e.g. with respect to Figure 6); the computer code may be provided to or downloaded by the network node 1500.

The memory 1504 may be arranged to be used to store obtained information such as assistance data, timing offset information, other NPRS configuration, indications of a mobility set, identifiers of APs and WLANs, identifiers of UEs, ciphering keys, measurements of signais from radio access nodes, measurement reports or parts thereof and applications etc. to perform the methods herein when being executed in the network node 1500.

Figure 16 is a schematic illustration of a network node 1600 according to embodiments of the disclosure. The network node 1600 comprises processing circuitry 1602, and memory 1604. Embodiments described herein (e.g. the method described above with respect to Figure 6) may be implemented through the processing circuitry 1602 executing computer program code stored on the memory 1604 for performing the methods set out herein.

Thus, the methods according to the embodiments described herein performed by the UE and/or the network node may be implemented by means of a computer program product, comprising instructions, i.e. software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the target device and/or the location server and/or the network node. The computer program product may be stored on a computer-readable storage medium. The computer-readable storage medium, having stored there on the computer program, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the target device and/or the location server and/or the network node. In some embodiments, the computerreadable storage medium may be a non-transitory computer-readable storage medium.

Claims (16)

1. A method, performed by a target device, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the method comprises:

- obtaining, from a location server, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell,

- determining a time of a NPRS subframe for the neighbour cell and/or NPRS sequence based on the timing offset information,

- measuring a positioning reference signal, PRS, for the neighbour cell based on the determined time,

- reporting the measured PRS to the location server.

2. The method according to claim 1, wherein the timing offset information comprises an indication of a System frame number, SFN, offset between the neighbour cell and a reference cell or a serving cell.

3. The method according to claim 1 or 2, wherein the timing offset information comprises an indication of a subframe number offset between the neighbour cell and a reference cell or a serving cell.

4. The method according to any one of the preceding claims, wherein the timing offset information comprises an indication as to whether the timing offset information of the neighbour cell is the same as or different than the timing offset information of a reference cell or a serving cell.

5. The method according to any one of the preceding claims, wherein the assistance information further comprises NPRS configuration information for the neighbour cell.

6. The method according to claim 5, wherein the NPRS configuration information comprises an indication of subframes in which NPRSs are transmitted in the neighbour cell.

7. The method according to claim 6, wherein the indication of subframes comprises a bitmap, where each bit of the bitmap corresponds to a subframe, and indicates whether the corresponding subframe contains an NPRS or not.

8. A method, performed by a location server, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the method comprises:

- obtaining, from a network node, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell,

- transmitting, to a target device, the assistance data related to the reference and neighbour cell list for enabling détection ofthe NPRS location in the radio frame,

- receiving, from the target device, a measured positioning reference signal, PRS.

9. The method according to claim 8, wherein the timing offset information comprises an indication of a system frame number, SFN, offset between the neighbour cell and a reference cell or a serving cell.

10. The method according to claim 8 or 9, wherein the timing offset information comprises an indication of a subframe number offset between the neighbour cell and a reference cell or a serving cell.

11. The method according to any one of claims 8 to 10, wherein the timing offset information comprises an indication as to whether the timing offset information of the neighbour cell is the same as or different than the timing offset information of a reference cell or a serving cell.

12. The method according to any one of claims 8 to 11, wherein the assistance information further comprises NPRS configuration information for the neighbour cell.

13. A method, performed by a network node, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the method comprises:

- receiving, from a location server, a request for assistance data related to a neighbour cell in a reference and neighbour cell list and served by the network node; and

- transmitting, to the location server, the assistance data related to the neighbour cell served by the network node, wherein the assistance data comprises timing offset information for the cell for enabling détection of the NPRS location in the radio frame.

14. A target device, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the target device is configured to:

- obtain, from a location server, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell;

- détermine a time of a NPRS subframe for the neighbour cell and/or NPRS sequence based on the timing offset information;

- measure a positioning reference signal, PRS, of the neighbour cell based on the determined time; and

- report the measured PRS to the location server.

15. A location server, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the location server is configured to:

- obtain, from a network node, assistance data related to a neighbour cell in a reference and neighbour cell list, wherein the assistance data comprises timing offset information for the neighbour cell;

- transmit, to a target device, the assistance data related to reference and neighbour cell list for enabling détection of the NPRS location in the radio frame; and

- receive, from the target device, measured PRS.

16. A network node, for enabling détection of a narrowband positioning reference signal, NPRS, location in a radio frame, wherein the network node is configured to:

- receive, from a location server, a request for assistance data related to a neighbour cell in a reference and neighbour cell list; and

- transmit, to the location server, the assistance data related to the neighbour cell served by the network node, wherein the assistance data comprises timing offset information for the neighbour cell for enabling détection of the NPRS location in the radio frame.