GB2583520A

GB2583520A - Improvements in or relating to positioning reference in a telecommunication system

Info

Publication number: GB2583520A
Application number: GB1906205.8A
Authority: GB
Inventors: Qi Yinan
Original assignee: Samsung Electronics Co Ltd
Current assignee: Samsung Electronics Co Ltd
Priority date: 2019-05-02
Filing date: 2019-05-02
Publication date: 2020-11-04
Also published as: GB2586307A; GB201906205D0; GB202006486D0; GB2586307B; KR20200127883A

Abstract

A comb pattern and muting periodicity are selected for the transmission of position reference signals (PRS). The comb pattern may be comb-3 (fig. 1a), comb-6 (fig. 1b) or comb-12 (fig. 1c) among other possibilities. With a larger comb pattern, more cells can transmit orthogonal PRS at the same time using a suitable offset, and therefore fewer positioning occasions are needed (i.e. a lower periodicity). The muting periodicity may be configured by a location server and may be additionally defined on the basis of numerology. In a second aspect, the PRS may be muted over only a part of the frequency band. The system may be used by base stations (gNBs) in a 5G New Radio communications network.

Description

Improvements in and relating to Positioning Reference in a telecommunication system The present invention relates to improvements is the provision, management and interpretation of a positioning reference signal in a telecommunication system and apparatus associated therewith. It applies particularly to New Radio (NR) or Fifth Generation (5G) systems, but may have other applications.

Demand for mobile services is exploding and one of the fastest growing segments is Location Based Services (LBS), primarily driven by two major requirements: emergency services and commercial applications. In response to these needs, second and third generation networks (WCDMA, GSM, CDMA) have added support for several positioning technologies, which vary in their accuracy and Time to First Fix (TTFF) performance. 3GPP Release 9 for LTE defines support for positioning technologies: Extended Cell ID (ECID), Assisted Global Navigation Satellite System (A-GNSS), Observed Time Different Of Arrival (OTDOA) and LTE Positioning Protocl (LPP), a new positioning protocol. A reference signal, i.e., positioning reference signal (PRS) has been defined in LTE. Further in Rel-11, Uplink Observed Time Different of Arrival (UOTDA) has been adopted using SRS measurement. 3GPP Rel-15 defines support for some Radio Access Technology (RAT)-independent positioning techniques, such as Real Time Kinematic (RTK) GNSS, to improve the accuracy of LTE positioning.

In LTE, base stations (eNBs) can be configured for time-based blanking, called "PRS muting". By this process, when a strong PRS signal is muted, weak PRS signals from the neighbouring cells are more easily detected by the UE.

In the prior art LTE system, PRS muting configuration is defined with a periodic sequence with periodicity T_REP, where T_REP counts the number of positioning occasions and it can be 2, 4, 8 and 16. The muting info is represented by a binary string of length 2, 3, 8 and 16 bits.

It is an aim of embodiments of the present invention to address issues in the prior art, whether mentioned herein or not and to provide an improved positioning reference capability in a telecommunication system.

According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

According to a first aspect of the present invention, there is provided a method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the steps of: providing a plurality of PRS configurations in the form of a plurality of comb patterns; selecting one of the plurality of PRS configurations and applying it for transmission of PRS; determining a muting configuration periodicity, T_REP, on the basis of the selected one of the plurality of PRS configuration; and selectively muting PRS according to T_REP.

In an embodiment, each of the plurality of PRS configurations in the form of a plurality of comb patterns is defined in terms of one or more resource elements which comprise a PRS 10 transmission.

In an embodiment, the plurality of PRS configurations comprise one or more of Comb-1, Comb-3, Comb-4, Comb-6 and Comb-12 patterns.

In an embodiment, T_REP is determined according to the table: Comb-1 Comb-3 Comb-4 Comb-6 Comb-12 "00" 16 (k1) 4 (k2) 6 (k3) 2 (k4) 2 (k5) "01" 32 (2k1) 8 (2k2) 12 (2k3) 4 (2k4) 4 (2k5) "10" 64 (4k1) 16 (4k2) 24 (4k3) 8 (4k4) 8 (4k5) "11" 128 (8k1) 32 (8k2) 48 (8k3) 16 (8k4) In an embodiment, T_REP is determined on the basis of a set of all possible values.

In an embodiment, a location server configures the value of T_REP.

In an embodiment, T_REP is additionally defined on the basis of numerology.

According to a second aspect of the present invention, there is provided method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the step of muting PRS for at least a part of a frequency band.

In an embodiment, muting is configured for a part of the frequency band or the entire frequency band.

According to a third aspect of the present invention, there is provided a method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the method of the first aspect combined with the method of the second aspect.

According to a fourth aspect of the present invention, there is provided a non-transitory data carrier carrying processor control code to implement the method of any preceding aspect.

According to a fifth aspect of the present invention, there is provided apparatus arranged to perform the method of any of the first, second or third aspects.

Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which: Figures la-c show Comb-3, Comb-6 and Comb-12 patterns respectively, in accordance with embodiment of the present invention; Figure 2 shows frequency muting an accordance with an embodiment of the present invention. 20 In NR, a PRS muting configuration should be different from LTE for at least the following reasons. In LTE, only one comb pattern, i.e., comb6 is supported, but in NR multiple PRS patterns with different comb patterns, e.g., comb-1,2,3,4,6,12, are supported. Further, multiple numerologies are supported in NR. Still further, system bandwidth can be much larger, up to 400 MHz in FR2. All of these considerations lead to a need for a different PRS muting configuration.

In prior art LTE systems, muting configuration is relevant across multiple positioning occasions. However, in NR, which can utilise beamforming, even in one positioning occasion, muting can be configured.

For example, if a serving base station (gNB) has K beams and does beam sweeping in one positioning occasion to transmit PRS, k out of K beams can be muted to reduce the interference to other neighbouring gNBs. The muting configuration of multiple gNBs can be coordinated by the location server of the system. One positioning occasion can consist of multiple PRS resource sets and beam sweeping can be conducted within each resource set or across multiple resource sets. The muting can happen within one resource set or across multiple resource sets. In this sense, it is necessary to define the measurement behaviour of a UE in the system.

When a UE detects a Downlink (DL) PRS resource(s)/ resource set which is different from the one indicated by the network and chooses to use such resource(s) / resource set as the reference, it should report the resource ID(s) and/or resource set ID.

The indicated resource(s)/resource set is normally from the serving cell. However, when muting happens, the serving cell might be muted and UE has to choose resource(s) / resource set from a neighboring cell. In such a case, the decision criterion of the UE should be defined for such an operation. Several alternatives can be considered: * 1: UE may choose a DL PRS resource with a strongest first detected path; * 2: UE may choose a DL PRS resource with a strongest detected path; * 3: UE may choose a DL PRS resource with the strongest average paths; * 4: a combination of 1-3 above.

The criterion used should also be reported to the network to facilitate the positioning.

Another issue is how resource ID(s) and/or resource set ID are reported. Three cases may be considered.

In a first case, both resource ID and resource set ID are defined globally. In a second case, resource ID is defined locally but resource set ID is defined globally. In a third case, both resource ID and resource set ID are defined locally.

For the first case, the UE can report resource ID or resource set ID only without any ambiguity.

For the second case, reporting resource ID only is not enough because the same ID might be used in different resource sets so that both resource ID and resource set ID should be reported.

For the third case, even with both resource ID and resource set ID being reported, ambiguity may still exist and in such a case, the cell ID should also be reported to resolve any such ambiguity.

Alternatively, other IDs, e.g., PRS sequence ID, where cell ID is implicitly included, can be reported instead. It is also possible to report PRS sequence ID only without resource ID/resource set ID because such IDs can be included in 'cinit' (a seed used to generate PRS) when generating PRS sequences. Reporting sequence ID can implicitly report resource ID / resource set ID.

In the prior art LTE system, comb pattern based muting may be used, but only comb-6 is supported. However, according to an embodiment of the present invention, other comb patterns such as comb-3 and comb-12 can be used. Comb-3, Comb-6 and Comb-12 patterns are illustrated in Figured la-c respectively. Each of these shows PRS transmissions within a time domain slot, comprising 14 symbols and 12 subcarriers, as shown by the axes on Figure la. The PRS transmission is indicated by the shaded resource element (cell).

With a larger comb pattern, such as comb-12 (see Figure 1c), more cells can transmit orthogonal PRS at the same time. There is an offset between different cells and there is less collision between PRS from neighbouring cells. In this sense, for the same number of cells transmitting PRS, a lower number of positioning occasions are needed. For example, for 24 cells with Physical Cell ID, PCI 0-23, if comb-12 is used, two positioning occasions are required to orthogonalize cell 0-11 and cell 12-23. This requires muting of certain PRS transmissions so that cell orthogonality can be achieved.

If comb-6 is used, four positioning occasions are required to orthogonalize cell 0-5, cell 6-11, cell 12-17, and cell 18-23.

If comb-3 is used, 8 positioning occasions are required to orthogonalize cell 0-2, cell 3-5, cell 6-8, cell 9-11, cell 12-14, cell 15-17, cell 18-20, cell 21-23.

For comb-1, 24 occasions are required to orthogonalize all the PRS from 24 cells. Therefore, muting configuration periodicity, T_REP, is defined to depend on comb-pattern. In other words, embodiments of the present invention define a muting scheme, including periodicity, based on which PRS comb pattern is used.

Therefore, two different ways to define T_REP with comb-pattern may be defined as follows.

In a first instance, for each adopted comb-pattern, an individual group of T_REP values is defined. For example, for comb-6, T_REP as well as the bit string length belongs to the set {2, 4, 8, 16}. For comb-12, T_REP belongs to the set {2, 4, 8}. For comb-3, T_REP belongs to the set {4, 8, 16, 32}. For comb-1, T_REP belongs to the set {16, 32, 64, 128}. For comb-4, T_REP belongs to the set {6, 12, 24, 48}. It should be noted that the values in the set are just examples and they can be either pre-defined or configured in a dynamic or semi-persistent way. The table below indicates the actual value of T_REP based on different comb patterns, where k1 to k5 are the basic/smallest T_REP values and they can either be pre-defined or configured in dynamic or semi-persistent way, by means of high layer signalling (such as RRC, LPP) as indicated by the code in the first column of the table.

Comb-1 Comb-3 Comb-4 Comb-6 Comb-12 "00" 16 (k1) 4 (k2) 6 (k3) 2 (k4) 2 (k5) "01" 32 (2k1) 8 (2k2) 12 (2k3) 4 (2k4) 4 (2k5) "10" 64 (4k1) 16 (4k2) 24 (4k3) 8 (4k4) 8 (4k5) "11" 128 (Ski) 32 (8k2) 48 (8k3) 16 (8k4) In a second instance, it is possible to define a super set containing all T_REP values. For example, it can be {2,4,8,16,32,64,128,6,12,24,48} and it is up to the location server to configure such values as required.

In the prior art LTE system, a single numerology is supported but in NR, multiple numerologies are supported. For a different numerology, a slot duration is different and the duration of one positioning occasion could either be the same or different.

If the duration of one positioning occasion is the same for different numerologies and the muting pattern is used across different muting occasions, T_REP may not depend on numerologies, i.e., the value set of T_REP is the same for all numerologies.

However, if the duration of one positioning occasion is different for different numerologies, different values sets of T_REP should be defined on a per numerology basis. One example can be as below.

* 15kHz: T_REP 6 {2, 4, 8, 16} * 30kHz: T_REP 6 {4, 8, 16, 32} * 60kHz: T_REP C {8, 16, 32, 64} * 120kHz: T_REP C {16, 32, 64, 128} It should be noted the values above are just examples and not intended to be limiting.

In prior art LTE systems, muting is only possible in the time domain. However, in NR, the system bandwidth can be up to 400MHz. If time domain muting happens, the entire bandwidth needs to be muted and this can be considered a waste of resources. In such a case, embodiments of the present invention introduce frequency domain muting as well as time domain muting.

This is illustrated in Figure 2. This shows that for a comb-6 pattern, PCI 0 and PCI 6 will overlap so they may be orthogonalized by frequency muting. In other words, PCI 0 is muted in the frequency domain while PCI 6 is active and vice-versa.

The following parameters may be defined for frequency domain muting: Basic frequency part W b; Entire frequency band W_e; a string to indicate the muted and activated frequency parts.

In the example shown in Figure 2, for PCI 0 and 1, the string is 1010 (where '1' indicates an activated frequency part and '0' indicates a muted frequency part) and for PCI 6 and 7, the string is 0101. It should be noted that frequency muting can be used alone or if combined with time domain muting, it can orthogonalize PRS transmissions from a greater number of cells.

At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as 'component', 'module' or 'unit' used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term "comprising" or "comprises" means including the component(s) specified but not to the exclusion of the presence of others.

Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the steps of: providing a plurality of PRS configurations in the form of a plurality of comb patterns; selecting one of the plurality of PRS configurations and applying it for transmission of PRS; determining a muting configuration periodicity, T_REP, on the basis of the selected one of the plurality of PRS configuration; and selectively muting PRS according to T_REP.
2. The method of claim 1 wherein each of the plurality of PRS configurations in the form of a plurality of comb patterns is defined in terms of one or more resource elements which comprise a PRS transmission.
3. The method of any preceding claim wherein the plurality of PRS configurations comprise one or more of Comb-1, Comb-3, Comb-4, Comb-6 and Comb-12 patterns.
4. The method of any preceding claim wherein T_REP is determined according to thetable:
Comb-1 Comb-3 Comb-4 Comb-6 Comb-12 "00" 16 (k1) 4 (k2) 6 (k3) 2 (k4) 2 (k5) "01" 32 (2k1) 8 (2k2) 12 (2k3) 4 (2k4) 4 (2k5) "10" 64 (4k1) 16 (4k2) 24 (4k3) 8 (4k4) 8 (4k5) "11" 128 (8k1) 32 (8k2) 48 (8k3) 16 (8k4) 5. The method of any of claim 1 to 3 wherein T_REP is determined on the basis of a set of all possible values.
6. The method of claim 5 wherein a location server configures the value of T_REP.
7. The method of any preceding claim wherein T_REP is additionally defined on the basis of numerology.
8. A method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the step of muting PRS for at least a part of a frequency band.
9. The method of claim 8 wherein muting is configured for a part of the frequency band or the entire frequency band.
10. A method of configuring a positioning reference signal, PRS, in a telecommunication system comprising the method of any of claims 1 to 7 combined with the method of any one of claims 8 to 9.
11. A non-transitory data carrier carrying processor control code to implement the method of any preceding claim.
12. Apparatus arranged to perform the method of any of claims 1 to 10.