Patent Publication Number: US-11387928-B2

Title: Methods and user equipment, radio transmitter and network node for managing positioning reference signals

Description:
PRIORITY 
     This application is a continuation, under 35 U.S.C. § 120 of US patent application Ser. No. 15/539,913 filed Jun. 26, 2017 which is a U.S. National Stage Filing under 35 U.S.C. § 371 of International Patent Application Serial No. PCT/EP2017/061333 filed May 11, 2017, and entitled “Methods And User Equipment, Radio Transmitter And Network Node For Managing Positioning Reference Signals” which claims priority to U.S. Provisional Patent Application No. 62/335,738 filed May 13, 2016, all of which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments herein relate to wireless communication systems, such as cellular networks. In particular, a method and a user equipment as well as a method and a radio transmitter for managing positioning reference signals are disclosed. Moreover, a method and a network node for configuring positioning reference signals are disclosed. Corresponding computer programs and carriers therefor are also disclosed. 
     BACKGROUND 
     Location-based services and emergency call positioning drive the development of positioning in wireless networks. Positioning support in Third Generation Partnership Project Long Term Evolution (3GPP LTE) was introduced in Release 9. This enables operators to retrieve position information for location-based services and to meet regulatory emergency call positioning requirements. 
     Positioning in LTE is supported by direct interactions between a user equipment (UE) and a location server, such as an Enhance Serving Mobile Location Center (E-SMLC), is via the LTE Positioning Protocol (LPP). Moreover, there are also interactions between the location server and an eNodeB, e.g. a radio base station, via the LPPa protocol, to some extent supported by interactions between the eNodeB and the UE via the Radio Resource Control (RRC) protocol. 
     The following positioning techniques are considered in LTE:
         Enhanced Cell identity (ID). Essentially cell ID information to associate the UE to the serving area of a serving cell, and then additional information to determine a finer granularity position.   Assisted Global Navigation Satellite Systems (Assisted GNSS). GNSS information retrieved by the UE, supported by assistance information provided to the UE from E-SMLC   Observed Time Difference of Arrival (OTDOA). The UE estimates the time difference of reference signals from different base stations and sends to the E-SMLC for multi-lateration.   Uplink Time Difference Of Arrival (UTDOA). The UE is requested to transmit a specific waveform that is detected by multiple location measurement units, e.g. an eNB, at known positions. These measurements are forwarded to E-SMLC for multi-lateration       

     Global positioning system (GPS)-enabled terminals can meet the requirement for positioning, but it cannot provide the required availability due to the satellite signals being blocked in urban and indoor environments. Therefore other techniques are needed in such environments. OTDOA has been introduced in 3GPP release 9 as a downlink (DL) positioning method. As illustrated in  FIG. 1 , OTDOA in LTE is based on the UE measuring the Time Of Arrival (TOA) of signals received from eNBs. The UE measures the relative difference between the reference cell and another specific cell, defined as Reference Signal Time Difference (RSTD) measurement. Every such RSTD determines a hyperbola and the interested point of these hyperbolas can be considered as the UE position. Here, the reference cell is selected by the UE and the RSTD measurement can be performed on an intra-frequency cell, i.e. reference cell/neighbor cell are on the same carrier frequency as the serving cell, or inter-frequency cell, i.e. at least one of reference cell/neighbor cell is on the different carrier frequency from the serving cell. 
     PRS and Configuration Thereof 
     In principle, it is possible to measure RSTD on any downlink signals e.g. Cell-specific Reference Signals (CRS). However as in OTDOA the UE requires to detect multiple neighbor-cell signals, these signals suffer from poor hearability. Hence, Positioning Reference Signals (PRSs) have been introduced to improve OTDOA positioning performance.  FIGS. 2 a  and 2 b    and  FIGS. 3 a  and 3 b    show the arrangement of the PRS assigned resources for one resource block using normal Cyclic Prefix (CP) and extended CP, respectively. In such PRS subframe, in order to reduce the interference with neighbor cells, no Physical Downlink Shard Channel (PDSCH) data is carried. Physical Downlink Control Channel (PDCCH) and CRSs are retained in the subframe, while PRSs are distributed in a “diagonal” way in between CRSs. Similar to CRS, cell-specific frequency shift i.e. the number of frequency shift v_shift is given by Physical Cell Identity (PCI) modulo 6, is applied to PRS pattern, which helps avoid time-frequency PRS collision up to six neighbor cells. 
     In an LTE system, consecutive PRS subframes a.k.a. positioning occasions are transmitted periodically in the downlink. One positioning occasion may contain up to six consecutive PRS subframes. The period of one positioning occasion can be configured to every T PRS =160, 320, 640 and 1280 milliseconds. It is noted that, in Time Division Duplex (TDD) mode, uplink subframe and other special frames cannot contain PRSs. Another parameter to characterize the PRS transmission schedule is the cell specific subframe offset, which defines the starting subframe of PRS transmission relative to SFN=0. As shown in Table 1, the PRS periodicity T PRS  and subframe offset Δ PRS  are derived from the PRS Configuration Index I PRS . 
                     TABLE 1                  Positioning reference signal subframe configuration                                     PRS periodicity   PRS subframe offset           PRS configuration   T PRS     Δ PRS             Index I PRS     (subframes)   (subframes)                                          0-159   160   I PRS             160-479   320   I PRS  − 160            480-1119   640   I PRS  − 480           1120-2399   1280   I PRS  − 1120                             2400-4095   Reserved                    
PRS Muting
 
     In some cases, in particular in dense deployments, only cell-specific frequency shift may not be sufficient to avoid interference from neighbor cells. Therefore, PRS muting has been introduced to further reduce inter-cell interference by muting PRS transmission in other cells based on a periodical “muting pattern”. The PRS muting configuration of a cell is defined by a periodic muting sequence with a periodicity of T REP , where T REP  counted in number of PRS positioning occasions can be 2, 4, 8, or 16. Correspondingly, the PRS configuration is represented by a bit string of length 2, 4, 8, or 16. 
     Sequence Generation 
     The PRS sequence that is transmitted on antenna port  6  in the resources illustrated in  FIGS. 2 a -2 b , 3 a -3 b    for one frequency shift is generated by the reference-signal sequence r i,n     s    (m) defined by 
     
       
         
           
             
               
                 
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     where n s  is the slot number within a radio frame, l is the OFDM symbol number within the slot. 
     The sequence c(n) is defined by
 
 c ( n )=( x   1 ( n+N   C )+ x   2 ( n+N   C ))mod 2
 
 x   1 ( n+ 31)=( x   1 ( n+ 3)+ x   1 ( n ))mod 2
 
 x   2 ( n+ 31)=( x   2 ( n+ 3)+ x   2 ( n+ 2)+ x   2 ( n+ 1)+ x   2 ( n ))mod 2
 
where N C =1600 and the first m-sequence shall be initialized with x 1 (0)=1, x 1  (n)=0, n=1, 2, . . . , 30. The initialization of the second m-sequence is denoted by c init =Σ i=0   30 x 2  (i)·2 i  were the pseudo-random sequence generator shall be initialized with
 
                     c   init     =           2     1   ⁢   0       ·     (       7   ·     (       n   s     +   1     )       +   l   +   1     )     ·     (       2   ·     N     I   ⁢   D     cell       +   1     )       +     2   ·     N     I   ⁢   D     cell       +       N     C   ⁢   P       ⁢     
     ⁢     N     C   ⁢   P           =     {           1         for   ⁢           ⁢   normal   ⁢           ⁢   CP             0         for   ⁢           ⁢   extended   ⁢           ⁢   CP           .                 (   1   )               
Transmission Points for Macro Cell Coverage Extension
 
     An intention of distributed low-power transmission points (TP), also known as Remote Radio Heads (RRH) within a macro cell is to improve the macro cell coverage. This means that portions of the macro cell&#39;s coverage area is covered by smaller coverage areas of the TPs as illustrated in  FIG. 4 . The TPs are connected to an eNB via fiber and the non-collocated TPs may have the identical PCI as the associated macro cell. The PRS is generated based on the PCI of the macro cell, and identical PRS sequences would be transmitted by multiple TPs. 
     Cell Portion 
     The concept of cell portion has been introduced in Release 12 of specification for LTE. Cell Portion is a geographical part of a cell. A cell portion is semi-static, and identical for both the uplink (UL) and the downlink (DL). Within a cell, a cell portion is uniquely identified by its Cell Portion ID. This “Cell Portion ID” parameter gives the current Cell Portion associated with the target UE. The Cell Portion ID is the unique identifier for a cell portion within a cell. 
     When the UE reported RSTD measurements cannot be uniquely associated with a particular TP/cell, then the location server does not know the actual location coordinates of the corresponding TP/cell for the PRS measured by the UE. This problem is known as PCI ambiguity issue, and can cause a large error in the reported RSTD and thus the positioning accuracy can degrade significantly. There is couple of situations where this issue becomes problematic:
         1) While several TPs send the same PRS sequence as their associated macro cell. One solution in such deployment scenarios is to not transmit from the associated TPs but only transmit PRS from the macro cell only. However, this would reduce the number of possible UE measurements for positioning, since the TPs would not be exploited.   2) The number of physical cell IDs is limited and hence in dense cellular networks, in case where a proper muting procedure is activated, then there is a possibility that the UE hears cells with the same PCI. As two cells with the same PCI will generate the same PRS sequence according to (1), this would be another scenario for PCI ambiguity issue.       

     SUMMARY 
     An object may be to enable improvement of and/or to improve accuracy of RSTD reports in the above mentioned scenarios. 
     According to an aspect, the object is achieved by a method, performed by a user equipment, for managing positioning reference signals. The user equipment receives, from a network node, a reception configuration of the positioning reference signals relating to a radio transmitter. The reception configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of the positioning reference signals. Moreover, the user equipment receives, according to the reception configuration, the positioning reference signals from the radio transmitter. The user equipment also estimates, based on the positioning reference signals, signal characteristics relating to a position of the user equipment. Furthermore, the user equipment sends, to the network node, a report about the estimated signal characteristics. 
     According to another aspect, the object is achieved by a user equipment configured for managing positioning reference signals. The user equipment is configured for receiving, from a network node, a reception configuration of the positioning reference signals relating to a radio transmitter. The reception configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of the positioning reference signals. Moreover, the user equipment is configured for receiving, according to the reception configuration, the positioning reference signals from the radio transmitter. The user equipment is further configured for estimating, based on the positioning reference signals, signal characteristics relating to a position of the user equipment. Furthermore, the user equipment is configured for sending, to the network node, a report about the estimated signal characteristics. 
     According to a further aspect, the object is achieved by a method, performed by a radio transmitter, for managing positioning reference signals. The radio transmitter receives, from a network node, a transmit configuration of the positioning reference signals. The transmit configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of positioning reference signals. Next, the radio transmitter determines the positioning reference signals based on the cell identity and the identifier. Furthermore, the radio transmitter sends the positioning reference signals. 
     According to yet another aspect, the object is achieved by a radio transmitter configured for managing positioning reference signals. The radio transmitter is configured for receiving, from a network node, a transmit configuration of the positioning reference signals. The transmit configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of positioning reference signals. Moreover, the radio transmitter is configured for determining the positioning reference signals based on the cell identity and the identifier. Furthermore, the radio transmitter is configured for sending the positioning reference signals. 
     According to a still other aspect, the object is achieved by a method, performed by a network node, for configuring positioning reference signals. The network node sends, to a user equipment, a reception configuration of positioning reference signals. The reception configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of positioning reference signals. Moreover, the network node sends, to a radio transmitter, a transmit configuration of positioning reference signals. The transmit configuration comprises the cell identity and the identifier. 
     According to a still further aspect, the object is achieved by a network node configured for configuring positioning reference signals. The network node is configured for sending, to a user equipment, a reception configuration of positioning reference signals. The reception configuration comprises a cell identity relating to the radio transmitter and an identifier for determining of positioning reference signals. Moreover, the network node is configured for sending, to a radio transmitter, a transmit configuration of positioning reference signals. The transmit configuration comprises the cell identity and the identifier. 
     According to further aspects, the object is achieved by computer programs and carriers therefor corresponding to the aspects above. 
     In some embodiments relating to the user equipment and the radio transmitter, determination of positioning reference signals is performed by an initialization of c init  that reduces the PCI ambiguity problem by generating orthogonal PRS sequences for cells with same PCI. With some embodiments, the LPP/LPPa protocol is extended by introducing an identifier, such as a 3-bit Additional Sequence Identifier (ASID) element, which also may be used to distinguish TPs in a non-collocated TP deployment scenario. In another embodiment, the LPP/LPPa protocol is extended with a 12-bit ASID element. 
     A benefit, according to some embodiments, of mitigating the PCI ambiguity and enabling TP specific PRS patterns is achieved by the initialization of c init  and an extension to the LPP/LPPa protocol. 
     Advantageously, the embodiments herein increase the positioning accuracy thanks to that PCI ambiguity is mitigated by means of generation of orthogonal PRS sequences for cells with same PCI by use of at least the aforementioned identifier, i.e. the identifier for determining of positioning reference signals. 
     Moreover, at least some embodiments enable the possibility to report RSTD measurements for cells with same PCI, where cells are distinguished by at least the identifier. 
     Furthermore, at least some embodiments provide support for TP-specific PRS. 
     Aside from the advantage of mitigating the PCI ambiguity, and hence increasing the position estimation accuracy, some embodiments introduce the initialization of c init  and extend LPP/LPPa with the identifier, such as an ASID information element. 
     Another advantage is that due to having greater number of PRS sequences, in case of addition of new cells (or small cells) in the network, the PRS sequence planning for the new cell becomes practically simpler as there are more options available. 
     Moreover, the existing planning based on PCI can be reused, and the additional configurations enabled by the identifier adds to the existing planning, by enabling a more fine granular configuration within the existing PCI plan. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various aspects of embodiments disclosed herein, including particular features and advantages thereof, will be readily understood from the following detailed description and the accompanying drawings, in which: 
         FIG. 1  is an overview illustrating ‘Observed Time Difference of Arrival’-concept according to prior art, 
         FIGS. 2 a  and 2 b    illustrate time/frequency structures, 
         FIGS. 3 a  and 3 b    illustrate time/frequency structures, 
         FIG. 4  is an overview illustrating an eNodeB and a plurality of low TX Power RRHs, 
         FIG. 5  is a further overview illustrating an exemplifying network in which embodiments herein may be implemented, 
         FIG. 6  is a combined signaling and flowchart illustrating embodiment of the methods herein, 
         FIG. 7 a    is a flowchart illustrating embodiments of the methods in the user equipment  110 ,  FIG. 7 b    is a block diagram illustrating embodiments of the user equipment  110 , 
         FIG. 8 a    is a flowchart illustrating embodiments of the methods in the radio transmitter  120 , 
         FIG. 8 b    is a block diagram illustrating embodiments of the radio transmitter  120 , 
         FIG. 9 a    is a flowchart illustrating embodiments of the methods in the network node  130 , and 
         FIG. 9 b    is a block diagram illustrating embodiments of the network node  130 . 
         FIG. 10  is a table illustrating an example initialization of C init . 
     
    
    
     DETAILED DESCRIPTION 
     Throughout the following description similar reference numerals have been used to denote similar features, such as nodes, actions, steps, modules, circuits, parts, items elements, units or the like, when applicable. In the Figures, features that appear in some embodiments are indicated by dashed lines. 
       FIG. 5  depicts an exemplifying network  100  in which embodiments herein may be implemented. In this example, the network  100  is a Long-Term Evolution (LTE), network. 
     In other examples, the network  100  may be any cellular or wireless communication system, such as Universal Mobile Telecommunication System (UMTS) and Worldwide Interoperability for Microwave Access (WiMAX), a Wideband Code Division Multiple Access (WCDMA), Universal Terrestrial Radio Access (UTRA) TDD, Ultra-Mobile Broadband (UMB), Global System for Mobile communications (GSM) network, GSM/Enhanced Data Rate for GSM Evolution (EDGE) Radio Access Network (GERAN) network, EDGE network, a network comprising of any combination of Radio Access Technologies (RATs) such as e.g. Multi-Standard Radio (MSR) base stations, multi-RAT base stations etc., any 3rd Generation Partnership Project (3GPP) cellular network, WiFi networks, Worldwide Interoperability for Microwave Access (WiMax), 5G system or any cellular network or system. It should be noted that although terminology from 3GPP LTE has been used herein to explain the example embodiments, this should not be seen as limiting the scope of the example embodiments to only the aforementioned system. 
     In the network  100 , a positioning architecture is illustrated. The network  100  may be said to comprise a user equipment  110 . This means that the wireless communication device  110  is present in the network  100 . 
     Furthermore, a radio transmitter  120 , such as a radio network node, an eNodeB or the like, is shown in  FIG. 5 . The cellular network  100  may comprise the radio transmitter  120 . In some examples, the user equipment  110  is served by to the radio transmitter  120 . A radio network node may in some examples control one or more radio transmitters, such as TPs, via optical fibers. 
     Moreover, the network  100  comprises a network node  130 , such as evolved Serving Mobile Location Centre (E-SMLC) or the like. 
     The network node  130  may communicate  140 , e.g. over LPP, with the user equipment  110 . This communication may include user transmissions both to and from the user equipment  110 . 
     The network node  130  may communicate  141 , e.g. over LPPa, with the radio transmitter  120 . This communication may include user transmissions both to and from the radio transmitter  120 . 
     Moreover,  FIG. 5  illustrates a Mobility Management Entity (MME) and a Gateway Mobile Location Centre (GMLC) for completeness of the positioning architecture. 
     As used herein, the term “radio transmitter” may refer to a Base Station System (BSS), a Radio Network Controller (RNC), a Radio Base Station (RBS), an evolved Node B (eNB), a control node controlling one or more Remote Radio Units (RRUs), an access point, a low TX Power Remote Radio Head (RRH), a transmission point or the like. 
     As used herein, the term “user equipment” may refer to a wireless communication device, a machine-to-machine (M2M) device, a mobile phone, a cellular phone, a Personal Digital Assistant (PDA) equipped with radio communication capabilities, a smartphone, a laptop or personal computer (PC) equipped with an internal or external mobile broadband modem, a tablet PC with radio communication capabilities, a portable electronic radio communication device, a sensor device equipped with radio communication capabilities or the like. The sensor may be any kind of weather sensor, such as wind, temperature, air pressure, humidity etc. As further examples, the sensor may be a light sensor, an electronic or electric switch, a microphone, a loudspeaker, a camera sensor etc. The term “user” may indirectly refer to the wireless device. Sometimes, the term “user” may be used to refer to the user equipment or the like as above. It shall be understood that the user may not necessarily involve a human user. The term “user” may also refer to a machine, a software component or the like using certain functions, methods and similar. 
       FIG. 6  illustrates an exemplifying method according to embodiments herein when implemented in the network  100  of  FIG. 5 . 
     The user equipment  110  may perform a method for managing positioning reference signals. As an example, the user equipment  110  may perform a method for managing a reception configuration relating to positioning reference signals. 
     The radio transmitter  120  may perform a method for managing positioning reference signals. As an example, the radio transmitter  120  may perform a method for managing a transmit configuration relating to positioning reference signals. 
     The network node  130  may perform a method for configuring positioning reference signals. As an example, the network node  130  may perform a method for providing configurations, such as the reception configuration and/or the transmit configuration, relating to positioning reference signals. 
     Typically, the reception configuration is provided over LPP and the transmit configuration is provided over LPPa. According to the embodiments herein, these configurations may be extended as illustrated in the tables further below. In existing configurations, a physical cell identity is specified, but not an identifier depending on the existence of multiple cells with the same physical cell identity. Notably, according to the embodiments herein, the cell identity may comprise one of the physical cell identity, an extended cell identity and the like. The extended cell identity and its relation to the physical cell identity will be explained further below. 
     Briefly, the embodiments herein propose an identifier, different from the physical cell identity and the extended cell identity, to be used for determination of positioning reference signals. In this manner, different positioning reference signals may be generated for different cells, e.g. radio transmitters, even though they share a common physical cell identity. Moreover, the user equipment  110  is able to allow the network node  130  to distinguish reports, from the user equipment  110 , of signals characteristics for the common physical cell identity by means of the identifier. 
     Moreover, according to some embodiments, the cell identity may comprise one of the physical cell identity and an extended cell identity. The extended cell identity will be discussed in more detail after the description of the methods of  FIG. 6 . 
     One or more of the following actions may be performed in any suitable order. 
     When introducing the generation of positioning reference signals as disclosed herein, support for such positioning reference signals may be associated with a capability of the UE. Therefore, in one embodiment, the network node  130  obtains capability information from the user equipment  110  as illustrated Actions A 010  to A 040 . 
     Action A 010   
     The network node  130  sends, to a user equipment  110 , a request for capabilities, such as a RequestCapabilities message or the like. The request for capabilities may specifically relate to support for positioning reference signals based on the identifier. 
     Action A 020   
     Subsequent to action A 010 , the user equipment  110  may receive, from the network node  130 , the request for capabilities. 
     Action A 030   
     Once the request is received by the user equipment  110 , the user equipment  110  may check, e.g. a release version or the like, to find its, i.e. the user equipment&#39;s  110 , capabilities. Then, the user equipment  110  may send, to the network node  130 , a response relating to capabilities, wherein the response includes a first indication regarding support for positioning reference signals based on the identifier. The response message may be a ProvideCapabilities message. 
     Moreover, the response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     Action A 040   
     Subsequent to action A 030 , the network node  130  may receive, from the user equipment  110 , the response relating to capabilities. As mentioned, the response includes the first indication regarding support for positioning reference signals based on an identifier for determining of positioning reference signals. 
     The response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     Action A 050   
     For example, upon receiving a command or request (not shown in  FIG. 6 ) relating to a position of the user equipment  110 , the network node  130  sends a reception configuration of positioning reference signals to the user equipment  110 . The reception configuration comprises a cell identity relating to the radio transmitter  120  and an identifier for determining of positioning reference signals. The reception configuration may thus be dependent on the response received in action A 040 . Typically, it is only when the user equipment  110  supports positioning reference signals based on the identity that the identity is included in the reception configuration. 
     Action A 060   
     Subsequent to action A 050 , the user equipment  110  receives, from the network node  130 , the reception configuration of the positioning reference signals relating to the radio transmitter  120 . As mentioned, the reception configuration comprises the cell identity relating to the radio transmitter  120  and the identifier for determining of the positioning reference signals, e.g. when appropriate. 
     Action A 070   
     Furthermore, now returning to the network node  130 , the network node  130  sends, to the radio transmitter  120 , a transmit configuration of positioning reference signals. The transmit configuration comprises the cell identity and the identifier in correspondence with the reception configuration sent in action A 050 . This action may be performed before action A 050 . 
     However, before action A 050  and A 070 , the network node  130  may determine a value of the identifier, given the user equipment  110  supports use of the identifier. 
     According to a first embodiment, the network node  130  sets the identifier randomly for each radio transmitter, aka radio network node. 
     According to a second embodiment, the network node  130  can, using location information relating to the radio transmitters, determine the identifier for radio transmitters  120  with the same physical cell identity. For example, two radio transmitters with same PCI that are closely located should be assigned different identifiers, i.e. different values of the identifier, to ensure orthogonal PRS sequences for robust positioning. 
     According to a third embodiment, the network node  130  sets the identifier based on prior UE RSTD measurement reports, for example, if many erroneously RSTD measurements relates to a certain radio transmitter  120 , the network node  130  assigns a identifier to that radio transmitter  120  to and thus generates another orthogonal PRS sequence. 
     According to a fourth embodiment, the network node  130  sets the identifier based the UE capability report, the identifier is used if one or more devices, such as the user equipment  110 , supports positioning reference signals based on the identifier. The network node  130  then configures the radio transmitter  120  with the identifier according to any of the embodiments above, e.g. randomly, location info, or RSTD accuracy reports. 
     The first and second embodiments above may set the identifier upon deploying the network  100 , while the third and fourth embodiment updates the identifier during operation of the network  100 . 
     Action A 080   
     Subsequent to action A 070 , the radio transmitter  120  receives, from the network node  130 , the transmit configuration of the positioning reference signals. As mentioned, the transmit configuration comprises the cell identity relating to the radio transmitter  120  and the identifier for determining of positioning reference signals. 
     Action A 090   
     Now that the radio transmitter  120  has received the transmit configuration, the radio transmitter  120  determines the positioning reference signals based on the cell identity and the identifier. See e.g. section “PRS sequence generation” below. 
     The determining of the positioning reference signals may further be based on the extended cell identity. 
     Action A 100   
     Once the radio transmitter  120  has been configured as a result of action A 080 , the radio transmitter  120  sends the positioning reference signals, e.g. according to the received configuration. 
     Action A 110   
     Subsequent to action A 100 , the user equipment  110  receives, according to the reception configuration, the positioning reference signals from the radio transmitter  120 . In order to the user equipment  110  to be aware of when the positioning reference signals are expected to be received the user equipment  110  determines the C init  as described below in section “PRS sequence generation”. 
     Action A 120   
     Upon reception of the positioning reference signals, the user equipment  110  estimates, based on the positioning reference signals, signal characteristics relating to a position of the user equipment  110 . The signals characteristics may be signal strength, signal power and the like. 
     Action A 130   
     Subsequent to action A 120 , the user equipment  110  sends, to the network node  130 , a report about the estimated signal characteristics. The report may include the identifier and, optionally, information about whether or not the extended cell identity has been used to create orthogonal positioning reference signals. 
     Action A 140   
     Subsequent to action A 130 , the network node  130  may receive, from the user equipment  110 , the report about the estimated signal characteristics relating to the positioning reference signal sequence. 
     PRS Sequence Generation 
     The highest value of c init  occurs when n s =19, I=6, N ID   cell =503, and N CP , =0, that corresponds to c init =151582702 and it can be represented using the 28 right-most bits of c init . 
     The number of possible PRS sequences should preferably be set as large as possible in order to minimize the probability of colliding PRS patterns. Based on the existing 28-bit space, the 3-leftmost bits can be used to create more orthogonal PRS sequences. 
     The formula for increasing the number of PRS sequences should use the complete 31-bit space of c_init, while ensuring the combination of input, e.g. N_CP, ns, I, N ASID , N{circumflex over ( )}cell_id, generates a unique c_init value. The ASID element could be introduced to c_init according to the following examples:
 
 c   init *=2 10 ·(7·( n   s +1)+ l+ 1)·(2· N   ID   cell +1)+2· N   ID   cell   +N   CP +2 28   ·N   ASID  
 
     In this example, the 3 left-most bits comprising the N ASID  field can take values in range of 0 . . . 7 and the solution generates 8*504=4032 orthogonal PRS sequences. The proposed c init * is illustrated in  FIG. 10 . 
     In this context, the identifier for determining of positioning reference signals is exemplified by the N ASID , aka ASID. 
     In one embodiment, N ASID  is representing the TP-ID. In another embodiment, it represents a value to reduce the PCI ambiguity problem. In another embodiment, N ASID  can be obtained as a function of the cell portion ID. For example, if the total of the cell portion IDs is equal or less than 8, N ASID  represents the cell portion ID. Otherwise, N ASID  represents cell portion ID mod 8. 
     As another example:
 
 c   init =2 28   ·└N   ASID /512┘+2 10 ·(7·( n   s +1)+ l+ 1)·(2·( N   ASID  mod 512)+1)+2·( N   ASID  mod 512)+ N   CP  
 
     In this example, N ASID  is in the range of 0 . . . 4095. 
     Also in this example, the 3-leftmost bits is set by the ASID element, but also the 28-rightmost bits is set by using ASID, this allows generating  4096  unique sequences in comparison with  4032  sequences in the first example. 
     The frequency shift is currently based on the PCI mod 6, by introducing the N ASID  element for TP-specific PRS, it can be beneficial for TPs in same cell to use different frequency shift for reducing the interference. The frequency shift should be optionally based on the N ASID  or using the existing PCI mod 6 solution. This optionality can be set in the LPP by extending the protocol with an indication comprising whether the frequency shift is based on the N ASID  or PCI. 
     The LPP is extended to include the N ASID  and the option for frequency shift accordingly. 
     
       
         
           
               
             
               
                   
               
             
            
               
                 -- ASN1START 
               
               
                 OTDOA-ReferenceCellInfo ::= SEQUENCE { 
               
            
           
           
               
               
               
            
               
                   
                 physCellId 
                 INTEGER (0..503), 
               
            
           
           
               
               
               
               
               
            
               
                   
                 cellGlobalId 
                 ECGI 
                 OPTIONAL, 
                 -- Need ON 
               
            
           
           
               
               
               
               
               
            
               
                   
                 earfcnRef 
                 ARFCN-ValueEUTRA 
                 OPTIONAL, 
                 -- 
               
            
           
           
               
            
               
                 Cond NotSameAsServ0 
               
            
           
           
               
               
               
            
               
                   
                 antennaPortConfig 
                 ENUMERATED {ports1-or-2, ports4, ... } 
               
            
           
           
               
               
               
            
               
                   
                 OPTIONAL, 
                 -- Cond 
               
            
           
           
               
            
               
                 NotSameAsServ1 
               
            
           
           
               
               
               
            
               
                   
                 cpLength 
                 ENUMERATED { normal, extended, ... }, 
               
            
           
           
               
               
               
               
               
            
               
                   
                 prsInfo 
                 PRS-Info 
                 OPTIONAL, 
                 -- Cond 
               
            
           
           
               
            
               
                 PRS 
               
            
           
           
               
               
            
               
                   
                 ..., 
               
            
           
           
               
               
               
               
               
            
               
                   
                 [[ earfcnRef-v9a0 
                 ARFCN-ValueEUTRA-v9a0 
                 OPTIONAL 
                 -- 
               
            
           
           
               
            
               
                 Cond NotSameAsServ2 
               
            
           
           
               
               
            
               
                   
                 ]], 
               
            
           
           
               
               
               
               
               
            
               
                   
                 [[N_ ASID 
                 INTEGER (0...7) 
                 OPTIONAL 
                 -- 
               
            
           
           
               
               
               
               
            
               
                   
                 v_shift 
                 ENUMERATED {N_ASID,PCI} 
                  OPTIONAL 
               
            
           
           
               
               
            
               
                   
                 ]] 
               
            
           
           
               
            
               
                 } 
               
               
                 -- ASN1STOP 
               
               
                   
               
            
           
         
       
     
     In another embodiment, the frequency shift is set by the v_shift containing a number between 0-5 where the number indicates the frequency shift. This allows more configurability at the network side and possibility to dynamically adjust the v_shift. 
     In another embodiment, the v_shift elements indicates that v_shift=mod(N ASID +PCI, 6). 
     In another embodiment, in the situation where two same-PCI TPs unfortunately own the same N ASID  due to for example highly dense deployment, additional PRS muting pattern can be configured and applied to both TPs. 
     In yet another embodiment, the cell ID is extended to also encompass virtual cell IDs that are introduced as cellID values above 503. 
     In one mode, these are defined by extending the cell ID field beyond 503 in the following manner: 
     cellID_ext (extPhysCellID)=504+virtual cell ID, 
     where the virtual cell IDs are 0, 1, . . . , (max_no_virtual_cell_IDs−1). 
     If the max_no_virtual_cell_IDs is 388 or less, then it is possible to still leave three bits for ASID. The procedure with virtual cell IDs is illustrated in  FIGS. 12 and 13 . 
     In another mode of the invention, the physical cell ID is replaced by a new attribute physCellID_rel14 with range (0 . . . 891) (or narrower), defined as 
     
       
         
           
             
               N 
               
                 I 
                 ⁢ 
                 D 
               
               cell 
             
             = 
             
               
                 physCellID 
                 
                   rel 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   14 
                 
               
               = 
               
                 { 
                 
                   
                     
                       
                         physCellID 
                         , 
                       
                     
                     
                       
                         
                           physCellID 
                           
                             rel 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             14 
                           
                         
                         &lt; 
                         504 
                       
                     
                   
                   
                     
                       
                         extPhysCellID 
                         , 
                       
                     
                     
                       
                         
                           physCellID 
                           
                             rel 
                             ⁢ 
                             
                                 
                             
                             ⁢ 
                             14 
                           
                         
                         &gt; 
                         503 
                       
                     
                   
                 
               
             
           
         
       
     
     where extPhysCellID can encode cell portions for example. 
     Moreover, the base station, such as the radio transmitter  120 , may also receive a request from the network node  130  regarding its OTDOA configuration via the LPPa protocol (3GPP TS 36.455, section 9.27), OTDOA Cell Information. This IE contains OTDOA information of a cell. This protocol can be extended, see underlined IEs in the table below, to encompass the ASID: 
     
       
         
           
               
               
               
               
               
             
               
                   
               
             
            
               
                   
                   
                   
                 IE type 
                 Semantics 
               
               
                 IE/Group Name 
                 Presence 
                 Range 
                 and reference 
                 description 
               
               
                   
               
               
                 OTDOA Cell 
                   
                 1 . . . 
                   
                   
               
               
                 Information 
                   
                 &lt;maxnoOTDOAtypes&gt; 
                   
                   
               
               
                 &gt;CHOICE OTDOA 
                 M 
                   
                   
                   
               
               
                 Cell Information Item 
                   
                   
                   
                   
               
               
                 &gt;&gt; PCI   
                 
                   M 
                 
                   
                 
                   INTEGER 
                 
                 
                   Extended Physical Cell 
                 
               
               
                   
                   
                   
                 
                   (0 . . . 891, . . .) 
                 
                 
                   ID 
                 
               
               
                 &gt;&gt;Cell ID 
                 M 
                   
                 ECGI 
                   
               
               
                   
                   
                   
                 9.2.6 
                   
               
               
                 &gt;&gt; ASID   
                 
                   O 
                 
                   
                 
                   INTEGER 
                 
                 
                   Additional sequence ID 
                 
               
               
                   
                   
                   
                 
                   (0 . . . 7) 
                 
                   
               
               
                 &gt;&gt;TAC 
                 M 
                   
                 OCTET 
                 Tracking Area Code 
               
               
                   
                   
                   
                 STRING(2) 
                   
               
               
                 &gt;&gt;EARFCN 
                 M 
                   
                 INTEGER 
                 Corresponds to N DL  for 
               
               
                   
                   
                   
                 (0 . . . 65535, . . . , 
                 FDD and N DL/UL  for TDD 
               
               
                   
                   
                   
                 65536 . . . 262143) 
                 in ref. TS 36.104 
               
               
                 &gt;&gt;PRS Bandwidth 
                 M 
                   
                 ENUMERATED 
                 Transmission 
               
               
                   
                   
                   
                 (bw6, bw15, 
                 bandwidth of PRS 
               
               
                   
                   
                   
                 bw25, bw50, 
                   
               
               
                   
                   
                   
                 bw75, bw100, . . . ) 
                   
               
               
                 &gt;&gt;PRS 
                 M 
                   
                 INTEGER 
                 PRS Configuration 
               
               
                 Configuration Index 
                   
                   
                 (0 . . . 4095, . . . ) 
                 Index, ref TS 36.211 
               
               
                 &gt;&gt;CP Length 
                 M 
                   
                 ENUMERATED 
                 Cyclic prefix length of 
               
               
                   
                   
                   
                 (Normal, 
                 the PRS 
               
               
                   
                   
                   
                 Extended, . . . ) 
                   
               
               
                 &gt;&gt;Number of DL 
                 M 
                   
                 ENUMERATED 
                 Number of consecutive 
               
               
                 Frames 
                   
                   
                 (sf1, sf2, sf4, 
                 downlink subframes 
               
               
                   
                   
                   
                 sf6, . . . ) 
                 N PRS  with PRS, ref TS 36.211 
               
               
                 &gt;&gt;Number of 
                 M 
                   
                 ENUMERATED 
                 Number of used 
               
               
                 Antenna Ports 
                   
                   
                 (n1-or-n2, 
                 antenna ports, where 
               
               
                   
                   
                   
                 n4, . . . ) 
                 n1-or-n2 corresponds 
               
               
                   
                   
                   
                   
                 to 1 or 2 ports, n4 
               
               
                   
                   
                   
                   
                 corresponds to 4 ports 
               
               
                 &gt;&gt;SFN Initialisation 
                 M 
                   
                 BIT STRING 
                 Time in seconds 
               
               
                 Time 
                   
                   
                 (64) 
                 relative to 00:00:00 on 
               
               
                   
                   
                   
                   
                 1 January 1900 
               
               
                   
                   
                   
                   
                 (calculated as 
               
               
                   
                   
                   
                   
                 continuous time without 
               
               
                   
                   
                   
                   
                 leap seconds and 
               
               
                   
                   
                   
                   
                 traceable to a common 
               
               
                   
                   
                   
                   
                 time reference) where 
               
               
                   
                   
                   
                   
                 binary encoding of the 
               
               
                   
                   
                   
                   
                 integer part is in the 
               
               
                   
                   
                   
                   
                 first 32 bits and binary 
               
               
                   
                   
                   
                   
                 encoding of the fraction 
               
               
                   
                   
                   
                   
                 part in the last 32 bits. 
               
               
                   
                   
                   
                   
                 The fraction part is 
               
               
                   
                   
                   
                   
                 expressed with a 
               
               
                   
                   
                   
                   
                 granularity of 1/2**32 
               
               
                   
                   
                   
                   
                 second. 
               
               
                 &gt;&gt;E-UTRAN Access 
                 M 
                   
                 9.2.8 
                 The configured 
               
               
                 Point Position 
                   
                   
                   
                 estimated geographical 
               
               
                   
                   
                   
                   
                 position of the antenna 
               
               
                   
                   
                   
                   
                 of the cell. 
               
               
                 &gt;&gt;PRS Muting 
                 M 
                   
                 9.2.9 
                 The configuration of 
               
               
                 Configuration 
                   
                   
                   
                 positioning reference 
               
               
                   
                   
                   
                   
                 signals muting pattern, 
               
               
                   
                   
                   
                   
                 when applicable 
               
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Range bound 
                 Explanation 
               
               
                   
               
               
                   
                 maxnoOTDOAtypes 
                 Maximum no. of OTDOA information types that can be 
               
               
                   
                   
                 requested and reported with one message. Value is 63. 
               
               
                   
               
            
           
         
       
     
     Example 1: PCI Ambiguity Scenario in Dense Network Deployment 
     This example illustrates the PCI ambiguity problem by considering two cells that both has PCI=0, the cells are denoted with PCI 0,1  and PCI 0,2 . The two cells could both be hearable in dense deployment with activated muting procedure. In the existing solution, the two cells will get the same PRS sequence and the UE cannot separate the two signals, even if the UE could distinguish the signals, it cannot report the RSTD for PCI 0,1 , and PCI 0,2 , since the LPP does not provide a unique identifier. 
     According to at least some embodiments herein, the network  130  may assign PCI 0,1  to use N ASID =0 and PCI 0,2  to use N ASID =1. This would generate orthogonal sequences and thus create beneficial interference conditions, additionally the cells could be uniquely identified in LPP by using the N ASID  element. 
     Example 2: PCI Ambiguity Scenario for TPs Corresponding to the Same Macro Cell 
     In this example, some embodiments herein is used for creating a TP-specific PRS. Assume 6 TPs connected to a macro cell via fiber according to  FIG. 5 . The 6 cells can be assigned with orthogonal PRS sequences using the N ASID  element, for example TP1 uses N ASID =0, TP2 uses N ASID =1, and so on. Note that these embodiments also provide beneficial interference properties with adjacent cells with multiple non-collocated TP, since the TP-specific PRS is not only unique within the cell, but also throughout the area of 504 cells. 
     In  FIG. 7 a   , a schematic flowchart of exemplifying methods in the user equipment  110  is shown. The same reference numerals as above have been used to denote the same or similar features, in particular the same reference numerals have been used to denote the same or similar actions. Accordingly, the user equipment  110  performs a method for managing positioning reference signals. 
     As mentioned, the cell identity may comprise one of the physical cell identity and an extended cell identity. 
     One or more of the following actions may be performed in any suitable order. 
     Action A 020   
     The user equipment  110  may receive, from the network node  130 , the request for capabilities. 
     Action A 030   
     Once the request is received by the user equipment  110 , the user equipment  110  may check, e.g. a release version or the like, to find its, i.e. the user equipment&#39;s  110 , capabilities. Then, the user equipment  110  may send, to the network node  130 , a response relating to capabilities, wherein the response includes a first indication regarding support for positioning reference signals based on the identifier. The response message may be a ProvideCapabilities message. 
     Moreover, the response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     Action A 060   
     Furthermore, the user equipment  110  receives, from the network node  130 , the reception configuration of the positioning reference signals relating to the radio transmitter  120 . As mentioned, the reception configuration comprises the cell identity relating to the radio transmitter  120  and the identifier for determining of the positioning reference signals, e.g. when appropriate. 
     Action A 110   
     Subsequent to action A 100 , the user equipment  110  receives, according to the reception configuration, the positioning reference signals from the radio transmitter  120 . In order to the user equipment  110  to be aware of when the positioning reference signals are expected to be received the user equipment  110  determines the C init  as described below in section “PRS sequence generation”. 
     Action A 120   
     Upon reception of the positioning reference signals, the user equipment  110  estimates, based on the positioning reference signals, signal characteristics relating to a position of the user equipment  110 . The signals characteristics may be signal strength, signal power and the like. 
     Action A 130   
     Subsequent to action A 120 , the user equipment  110  sends, to the network node  130 , a report about the estimated signal characteristics. The report may include the identifier and, optionally, information about whether or not the extended cell identity has been used to create orthogonal positioning reference signals. 
     With reference to  FIG. 7 b   , a schematic block diagram of embodiments of the user equipment  110  of  FIG. 1  is shown. 
     The user equipment  110  may comprise a processing module  701 , such as a means for performing the methods described herein. The means may be embodied in the form of one or more hardware modules and/or one or more software modules 
     The user equipment  110  may further comprise a memory  702 . The memory may comprise, such as contain or store, instructions, e.g. in the form of a computer program  703 , which may comprise computer readable code units. 
     According to some embodiments herein, the user equipment  110  and/or the processing module  701  comprises a processing circuit  704  as an exemplifying hardware module. Accordingly, the processing module  701  may be embodied in the form of, or ‘realized by’, the processing circuit  704 . The instructions may be executable by the processing circuit  704 , whereby the user equipment  110  is operative to perform the methods of  FIG. 6 . As another example, the instructions, when executed by the user equipment  110  and/or the processing circuit  704 , may cause the user equipment  110  to perform the method according to  FIG. 6 . 
       FIG. 7 b    further illustrates a carrier  705 , or program carrier, which comprises the computer program  703  as described directly above. 
     In some embodiments, the processing module  701  comprises an Input/Output module  706 , which may be exemplified by a receiving module and/or a sending module as described below when applicable. 
     In further embodiments, the user equipment  110  and/or the processing module  701  may comprise one or more of a receiving module  710 , an estimating module  720 , and a sending module  730  as exemplifying hardware modules. In other examples, one or more of the aforementioned exemplifying hardware modules may be implemented as one or more software modules. 
     Accordingly, the user equipment  110  is configured for managing positioning reference signals. 
     Therefore, according to the various embodiments described above, the user equipment  110  and/or the processing module  701  and/or the receiving module  710  is configured for receiving, from a network node  130 , a reception configuration of the positioning reference signals relating to a radio transmitter  120 , wherein the reception configuration comprises a cell identity relating to the radio transmitter  120  and an identifier for determining of the positioning reference signals. 
     The user equipment  110  and/or the processing module  701  and/or the receiving module  710 , or another receiving module (not shown), is configured for receiving, according to the reception configuration, the positioning reference signals from the radio transmitter  120 . 
     The user equipment  110  and/or the processing module  701  and/or the estimating module  720  is configured for estimating, based on the positioning reference signals, signal characteristics relating to a position of the user equipment  110 . 
     Moreover, the user equipment  110  and/or the processing module  701  and/or the receiving module  730  is configured for sending, to the network node  130 , a report about the estimated signal characteristics. 
     The cell identity may comprise one of a physical cell identity and an extended cell identity. 
     The user equipment  110  and/or the processing module  701  and/or the receiving module  710 , or a further receiving module (not shown), may be configured for receiving, from the network node  130 , a request for capabilities. Moreover, the user equipment  110  and/or the processing module  701  and/or the sending module  730 , or another sending module (not shown) may be configured for sending, to the network node  130 , a response relating to capabilities, wherein the response includes a first indication regarding support for positioning reference signals based on the identifier. 
     The response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     In  FIG. 8 a   , a schematic flowchart of exemplifying methods in the radio transmitter  120  is shown. Again, the same reference numerals as above have been used to denote the same or similar features, in particular the same reference numerals have been used to denote the same or similar actions. Accordingly, the radio transmitter  120  performs a method for managing positioning reference signals. 
     As mentioned, the cell identity may comprise one of the physical cell identity and an extended cell identity. 
     One or more of the following actions may be performed in any suitable order. 
     Action A 080   
     The radio transmitter  120  receives, from the network node  130 , the transmit configuration of the positioning reference signals. As mentioned, the transmit configuration comprises the cell identity relating to the radio transmitter  120  and the identifier for determining of positioning reference signals. 
     Action A 090   
     Now that the radio transmitter  120  has received the transmit configuration, the radio transmitter  120  determines the positioning reference signals based on the cell identity and the identifier. See e.g. section “PRS sequence generation” below. 
     The determining of the positioning reference signals may further be based on the extended cell identity. 
     Action A 100   
     Once the radio transmitter  120  has been configured as a result of action A 080 , the radio transmitter  120  sends the positioning reference signals, e.g. according to the received configuration. 
     With reference to  FIG. 8 b   , a schematic block diagram of embodiments of the radio transmitter  120  of  FIG. 1  is shown. 
     The radio transmitter  120  may comprise a processing module  801 , such as a means for performing the methods described herein. The means may be embodied in the form of one or more hardware modules and/or one or more software modules 
     The radio transmitter  120  may further comprise a memory  802 . The memory may comprise, such as contain or store, instructions, e.g. in the form of a computer program  803 , which may comprise computer readable code units. 
     According to some embodiments herein, the radio transmitter  120  and/or the processing module  801  comprises a processing circuit  804  as an exemplifying hardware module. Accordingly, the processing module  801  may be embodied in the form of, or ‘realized by’, the processing circuit  804 . The instructions may be executable by the processing circuit  804 , whereby the radio transmitter  120  is operative to perform the methods of  FIG. 6 . As another example, the instructions, when executed by the radio transmitter  120  and/or the processing circuit  804 , may cause the radio transmitter  120  to perform the method according to  FIG. 6 . 
       FIG. 8 b    further illustrates a carrier  805 , or program carrier, which comprises the computer program  803  as described directly above. 
     In some embodiments, the processing module  801  comprises an Input/Output module  806 , which may be exemplified by a receiving module and/or a sending module as described below when applicable. 
     In further embodiments, the radio transmitter  120  and/or the processing module  801  may comprise one or more of a receiving module  810 , a determining module  820 , and a sending module  830  as exemplifying hardware modules. In other examples, one or more of the aforementioned exemplifying hardware modules may be implemented as one or more software modules. 
     Accordingly, the radio transmitter  120  is configured for managing positioning reference signals. 
     Therefore, according to the various embodiments described above, the radio transmitter  120  and/or the processing module  801  and/or the receiving module  810  is configured for receiving, from a network node  130 , a transmit configuration of the positioning reference signals, wherein the transmit configuration comprises a cell identity relating to the radio transmitter  120  and an identifier for determining of positioning reference signals. 
     The radio transmitter  120  and/or the processing module  801  and/or the determining module  820  is configured for determining the positioning reference signals based on the cell identity and the identifier. 
     The radio transmitter  120  and/or the processing module  801  and/or the sending module  830  is configured for sending the positioning reference signals. 
     The cell identity may comprise one of a physical cell identity and an extended cell identity, wherein the determining of the positioning reference signals further may be based on the extended cell identity. 
     In  FIG. 9 a   , a schematic flowchart of exemplifying methods in the network node  130  is shown. Again, the same reference numerals as above have been used to denote the same or similar features, in particular the same reference numerals have been used to denote the same or similar actions. Accordingly, the network node  130  performs a method for configuring positioning reference signals. 
     As mentioned, the cell identity may comprise one of the physical cell identity and an extended cell identity. 
     One or more of the following actions may be performed in any suitable order. 
     When introducing the generation of positioning reference signals as disclosed herein, support for such positioning reference signals may be associated with a capability of the UE. Therefore, in one embodiment, the network node  130  obtains capability information from the user equipment  110  as illustrated Actions A 010  to A 040 . 
     Action A 010   
     The network node  130  sends, to a user equipment  110 , a request for capabilities, such as a RequestCapabilities message or the like. The request for capabilities may specifically relate to support for positioning reference signals based on the identifier. 
     Action A 040   
     Furthermore, the network node  130  may receive, from the user equipment  110 , the response relating to capabilities. As mentioned, the response includes the first indication regarding support for positioning reference signals based on an identifier for determining of positioning reference signals. 
     The response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     Action A 050   
     For example, upon receiving a command or request (not shown in  FIG. 6 ) relating to a position of the user equipment  110 , the network node  130  sends a reception configuration of positioning reference signals to the user equipment  110 . The reception configuration comprises a cell identity relating to the radio transmitter  120  and an identifier for determining of positioning reference signals. The reception configuration may thus be dependent on the response received in action A 040 . Typically, it is only when the user equipment  110  supports positioning reference signals based on the identity that the identity is included in the reception configuration. 
     Action A 070   
     Furthermore, the network node  130  sends, to the radio transmitter  120 , a transmit configuration of positioning reference signals. The transmit configuration comprises the cell identity and the identifier in correspondence with the reception configuration sent in action A 050 . This action may be performed before action A 050 . 
     Action A 140   
     Moreover, the network node  130  may receive, from the user equipment  110 , the report about the estimated signal characteristics relating to the positioning reference signal sequence. 
     With reference to  FIG. 9 b   , a schematic block diagram of embodiments of the network node  130  of  FIG. 1  is shown. 
     The network node  130  may comprise a processing module  901 , such as a means for performing the methods described herein. The means may be embodied in the form of one or more hardware modules and/or one or more software modules 
     The network node  130  may further comprise a memory  902 . The memory may comprise, such as contain or store, instructions, e.g. in the form of a computer program  903 , which may comprise computer readable code units. 
     According to some embodiments herein, the network node  130  and/or the processing module  901  comprises a processing circuit  904  as an exemplifying hardware module. Accordingly, the processing module  901  may be embodied in the form of, or ‘realized by’, the processing circuit  904 . The instructions may be executable by the processing circuit  904 , whereby the network node  130  is operative to perform the methods of  FIG. 6 . As another example, the instructions, when executed by the network node  130  and/or the processing circuit  904 , may cause the network node  130  to perform the method according to  FIG. 6 . 
       FIG. 9 b    further illustrates a carrier  905 , or program carrier, which comprises the computer program  903  as described directly above. 
     In some embodiments, the processing module  901  comprises an Input/Output module  906 , which may be exemplified by a receiving module and/or a sending module as described below when applicable. 
     In further embodiments, the network node  130  and/or the processing module  901  may comprise one or more of a sending module  910 , and a receiving module  920  as exemplifying hardware modules. In other examples, one or more of the aforementioned exemplifying hardware modules may be implemented as one or more software modules. 
     Accordingly, the network node  130  is configured for configuring positioning reference signals. 
     Therefore, according to the various embodiments described above, the network node  130  and/or the processing module  901  and/or the sending module  910  is configured for sending, to a user equipment  110 , a reception configuration of positioning reference signals, wherein the reception configuration comprises a cell identity relating to the radio transmitter  120  and an identifier for determining of positioning reference signals. 
     Moreover, the network node  130  and/or the processing module  901  and/or the sending module  910 , or another sending module (not shown), is configured for sending, to a radio transmitter  120 , a transmit configuration of positioning reference signals, wherein the transmit configuration comprises the cell identity and the identifier. 
     The network node  130  and/or the processing module  901  and/or the receiving module  920  may be configured for receiving, from the user equipment  110 , a report about the estimated signal characteristics relating to the positioning reference signal sequence. 
     The cell identity may comprise one of a physical cell identity and an extended cell identity. 
     The network node  130  and/or the processing module  901  and/or the sending module  910 , or another sending module (not shown), may be configured for sending, to a user equipment  110 , a request for capabilities. 
     The network node  130  and/or the processing module  901  and/or the receiving module  920 , or another receiving module (not shown), may be configured for receiving, from the user equipment  110 , a response relating to capabilities, wherein the response includes a first indication regarding support for positioning reference signals based on an identifier for determining of positioning reference signals. 
     The response may include a second indication regarding support for positioning reference signals based on the extended cell identity. 
     As used herein, the term “node”, or “network node”, may refer to one or more physical entities, such as devices, apparatuses, computers, servers or the like. This may mean that embodiments herein may be implemented in one physical entity. Alternatively, the embodiments herein may be implemented in a plurality of physical entities, such as an arrangement comprising said one or more physical entities, i.e. the embodiments may be implemented in a distributed manner, such as on a set of server machines of a cloud system. 
     As used herein, the term “module” may refer to one or more functional modules, each of which may be implemented as one or more hardware modules and/or one or more software modules and/or a combined software/hardware module in a node. In some examples, the module may represent a functional unit realized as software and/or hardware of the node. 
     As used herein, the term “program carrier”, or “carrier”, may refer to one of an electronic signal, an optical signal, a radio signal, and a computer readable medium. In some examples, the program carrier may exclude transitory, propagating signals, such as the electronic, optical and/or radio signal. Thus, in these examples, the carrier may be a non-transitory carrier, such as a non-transitory computer readable medium. 
     As used herein, the term “processing module” may include one or more hardware modules, one or more software modules or a combination thereof. Any such module, be it a hardware, software or a combined hardware-software module, may be a determining means, estimating means, capturing means, associating means, comparing means, identification means, selecting means, receiving means, sending means or the like as disclosed herein. As an example, the expression “means” may be a module corresponding to the modules listed above in conjunction with the Figures. 
     As used herein, the term “software module” may refer to a software application, a Dynamic Link Library (DLL), a software component, a software object, an object according to Component Object Model (COM), a software component, a software function, a software engine, an executable binary software file or the like. 
     As used herein, the term “processing circuit” may refer to a processing unit, a processor, an Application Specific integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or the like. The processing circuit or the like may comprise one or more processor kernels. 
     As used herein, the expression “configured to/for” may mean that a processing circuit is configured to, such as adapted to or operative to, by means of software configuration and/or hardware configuration, perform one or more of the actions described herein. 
     As used herein, the term “action” may refer to an action, a step, an operation, a response, a reaction, an activity or the like. It shall be noted that an action herein may be split into two or more sub-actions as applicable. Moreover, also as applicable, it shall be noted that two or more of the actions described herein may be merged into a single action. 
     As used herein, the term “memory” may refer to a hard disk, a magnetic storage medium, a portable computer diskette or disc, flash memory, random access memory (RAM) or the like. Furthermore, the term “memory” may refer to an internal register memory of a processor or the like. 
     As used herein, the term “computer readable medium” may be a Universal Serial Bus (USB) memory, a DVD-disc, a Blu-ray disc, a software module that is received as a stream of data, a Flash memory, a hard drive, a memory card, such as a MemoryStick, a Multimedia Card (MMC), Secure Digital (SD) card, etc. One or more of the aforementioned examples of computer readable medium may be provided as one or more computer program products. 
     As used herein, the term “computer readable code units” may be text of a computer program, parts of or an entire binary file representing a computer program in a compiled format or anything there between. 
     As used herein, the expression “transmit” and “send” are considered to be interchangeable. These expressions include transmission by broadcasting, uni-casting, group-casting and the like. In this context, a transmission by broadcasting may be received and decoded by any authorized device within range. In case of uni-casting, one specifically addressed device may receive and decode the transmission. In case of group-casting, a group of specifically addressed devices may receive and decode the transmission. 
     As used herein, the terms “number” and/or “value” may be any kind of digit, such as binary, real, imaginary or rational number or the like. Moreover, “number” and/or “value” may be one or more characters, such as a letter or a string of letters. “Number” and/or “value” may also be represented by a string of bits, i.e. zeros and/or ones. 
     As used herein, the term “set of” may refer to one or more of something. E.g. a set of devices may refer to one or more devices, a set of parameters may refer to one or more parameters or the like according to the embodiments herein. 
     As used herein, the expression “in some embodiments” has been used to indicate that the features of the embodiment described may be combined with any other embodiment disclosed herein. 
     Even though embodiments of the various aspects have been described, many different alterations, modifications and the like thereof will become apparent for those skilled in the art. The described embodiments are therefore not intended to limit the scope of the present disclosure.