Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
  • G01S1/022—Means for monitoring or calibrating
  • G01S1/024—Means for monitoring or calibrating of beacon transmitters
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/0009—Transmission of position information to remote stations
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/0205—Details
  • G01S5/0236—Assistance data, e.g. base station almanac
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L5/00—Arrangements affording multiple use of the transmission path
  • H04L5/003—Arrangements for allocating sub-channels of the transmission path
  • H04L5/0048—Allocation of pilot signals, i.e. of signals known to the receiver
  • H04L5/0051—Allocation of pilot signals, i.e. of signals known to the receiver of dedicated pilots, i.e. pilots destined for a single user or terminal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W56/00—Synchronisation arrangements
  • H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
  • H04W56/0045—Synchronisation arrangements compensating for timing error of reception due to propagation delay compensating for timing error by altering transmission time
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
  • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
  • G01S1/68—Marker, boundary, call-sign, or like beacons transmitting signals not carrying directional information
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S2205/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S2205/001—Transmission of position information to remote stations
  • G01S2205/008—Transmission of position information to remote stations using a mobile telephone network
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
  • G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
  • G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
  • G01S5/10—Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements, e.g. omega or decca systems
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
  • H04W88/08—Access point devices
  • H04W88/085—Access point devices with remote components

Definitions

• the present invention relates to the field of geolocation of mobile terminals, for example, geolocation by means of a triangularization technique via antennas close to a mobile terminal.
• these estimates can be made by measuring the reference signal time difference (“Reference Signal Time Difference” or RSTD) by the mobile terminal whose geolocation is to be determined.
• reference signals for example, positioning reference signals (PRS) can be sent by the distributed unit (“Digital Unit” or DU in English) of the radio access network ("Radio access network” or RAN in English) to the mobile terminal.
• PRS positioning reference signals
• the reference signal emitted by the DU is transmitted to a radio unit (“Radio Unit” or RU in English) of an antenna and then to the mobile terminal to be geolocated.
• equipment of the DU type and of the RU type tend to be more and more distant from each other over distances which can vary from a few meters to several tens of kilometers.
• the travel time between these devices is no longer negligible and falsifies the geolocation measurements.
• One of the aims of the invention is to remedy these drawbacks of the state of the art.
• the invention improves the situation with the aid of a method for transmitting a reference signal descending from a network entity to a mobile terminal through a radio unit connected to an antenna, used for geolocation of the mobile terminal, the method being implemented by the radio unit and comprising:
• the timeout period being one value greater than a transmission path time of a signal called comparison signal, between the network entity and the radio unit.
• the portion of the travel time upstream of an antenna which is equal to the time delay, is constant regardless of the distance traveled and the transmission conditions, and can therefore be subtracted from the travel time. total between the network and the terminal, to obtain the flight time.
• the proposed method compensates for the transmission delays which are due to the non-aerial part of the paths of the reference signals used to determine the geolocation of a terminal.
• the comparison signal can be any signal between the network entity and the radio unit, including being the reference signal itself.
• it comprises measuring a value of the transmission path time of the comparison signal.
• the radio unit can verify that the delay is indeed greater than the travel time of a comparison signal, and trigger a procedure for updating the value of the delay if this is not the case. .
• the comparison signal is the reference signal. Thanks to this aspect, no specific signal, other than the reference signal itself, is necessary for the proposed method.
• the comparison signal is a signal distinct from the reference signal.
• the measurement of the travel time of a comparison signal can be carried out by the radio unit prior to the processing of the reference signal, and independently of it.
• the proposed method comprises the transmission, to the network entity, of the measured value of the transmission path time of the comparison signal.
• the network entity or another entity further upstream, can determine a value of the delay which is greater than the travel time of a comparison signal.
• the proposed method comprises the reception of a message comprising the value of the time delay.
• the radio unit applies a time delay imposed on it to the reference signal, and does not need to determine it itself.
• it is the network entity which provides the radio unit with the time delay to be applied, optionally but not necessarily according to a measurement of the transmission path time of a comparison signal which is communicated to it by the radio unit.
• the proposed method comprises:
• the radio unit itself determines the delay it applies to the reference signal. It is then the radio unit which must communicate the value of this delay, so that the entity responsible for the geolocation can correct the information which reaches it relating to the travel times of the reference signals.
• the radio unit can easily send the message comprising the value of the time delay to the network entity sending the reference signal.
• the network entity can then in turn transmit the value of the timeout to the entity responsible for the geolocation. According to one aspect of the proposed method, it comprises:
• the radio unit can also easily transmit the message including the timeout value to the mobile terminal.
• the mobile terminal it is possible for the mobile terminal to proceed itself to the calculation of the times of flight of each of the reference signals between the network entity and itself. Instead of sending RSTD to the network entity, the terminal sends the calculated flight times.
• the invention also relates to a device for transmitting a reference signal descending from a network entity to a mobile terminal through a radio unit connected to an antenna, used for geolocation of the mobile terminal, the device being included in the radio unit and comprising a receiver, a transmitter, a processor and a memory coupled to the processor with instructions intended to be executed by the processor for:
• This device capable of implementing in all its embodiments the method for transmitting a downlink reference signal which has just been described, is intended to be implemented in a radio unit.
• the invention also relates to a computer program comprising instructions which, when these instructions are executed by a processor, lead the latter to implement the steps of the method for transmitting a downlink reference signal, which comes from be described.
• the invention also relates to an information medium readable by the device for transmitting a downlink reference signal, which has just been described, and comprising instructions from a computer program as mentioned above.
• the above program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in partially compiled form, or in n any other desirable shape.
• a medium may comprise a storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or even a magnetic recording means.
• a storage means such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or even a magnetic recording means.
• Such a storage means can for example be a hard disk, a flash memory, etc.
• an information medium can be a transmissible medium such as an electrical or optical signal, which can be conveyed via an electrical or optical cable, by radio or by other means.
• a program according to the invention can in particular be downloaded from an Internet-type network.
• an information medium may be an integrated circuit in which a program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.
• Figure 1 schematically presents a network entity, a radio unit and a mobile terminal according to one embodiment of the invention
• FIG 2 shows an example of implementation of the method for transmitting a downlink reference signal, according to one embodiment of the invention
• FIG 3 shows an example of the structure of a device for transmitting a downlink reference signal, according to one aspect of the invention.
• transmission conditions it is understood both the conditions internal to the network (prioritization, resource allocation, routing path, buffering, channel coding, etc.) and the conditions external to the network (schedule, variation of temperature, significant traffic fluctuation, electromagnetic interference, etc.). These transmission conditions impact the signal transmission time more or less significantly.
• Signals used to estimate the position of a terminal are understood to mean the signals used to determine travel times between two points of the network, for example, between a mobile terminal whose position is to be determined and a network entity via a radio antenna or even a radio unit whose position is known (for example, a signal which is intended to allow measurement of a transmission path time between the network entity and the mobile terminal via the radio unit ) or even between the network entity and the radio unit (for example, a signal which is intended to allow a measurement of a transmission path time on a part of a communication network between the network entity and radio unit).
• These signals can be reference signals.
• the signals used can be positioning reference signals (PRS).
• PRS sequences are particularly advantageous insofar as they have good autocorrelation properties and low cross-correlation, thus making it possible to precisely extract the PRS in order to measure its time of arrival.
• radio unit is meant the radio transceiver which processes or produces the electrical signal transmitted to the antenna or received from the antenna and which corresponds to the radio signal transmitted or received by the antenna.
• the radio unit is the term used in the 5G standard but this unit can also be called remote radio head or "remote radio head” in English (RRH) or even remote radio unit or "radio remote unit” in English ( RRU). This radio unit is separate from the network entity.
• the terminal can at least partially decode the signals it receives from the radio unit.
• the mobile terminal can be connected to the base station corresponding to the radio unit.
• the network entity can be a distributed unit (this is the term used in the 5G standard) also called a digital unit or a base band unit (“base band unit” in English, BBU). This can be included in a base station or co-located with a centralized unit (CU).
• the network entity is connected to the radio unit by optical and/or microwave links, over distances varying from a few meters to several tens of kilometers.
• the network entity allows the processing of digital data to and from the radio unit which receives and transmits this data in radio form.
• the measurement of the transmission path time of a signal between the entity of the network and the radio unit can be carried out by any known technique, in one direction or the other.
• a measurement of the transmission path time can be carried out by sending a signal comprising information relating to the moment of its transmission and the receiver can then compare the time of arrival with the time of transmission of the signal.
• the measurement of the transmission path time between the entity of the network and the radio unit can then be realized by the network entity when the radio unit sends the second signal or by the radio unit when the network entity sends the second signal.
• the radio unit can transmit this measurement to the network entity if necessary (each time the network entity uses this measurement and it has not calculated it itself, it obtained via the radio unit).
• Figure 1 schematically presents a network entity, a radio unit and a mobile terminal according to one embodiment of the invention.
• the mobile terminal 1 of a user 2 is in the radio coverage of two radio antennas 3.0 and 4.0.
• the mobile terminal 1 receives the signals produced by the radio units (RU) 3.1 and 4.1 and transmitted respectively by the antennas 3.0 and 4.0.
• the 3.1 and 4.1 radio units are each connected to a 5.0 network entity.
• the links 3.2 and 4.2 between the network entity and the radio units 3.1 and 4.1 can be optical or even electrical links.
• the 5.0 network entity in the 5G standard is a distributed unit (DU).
• This network entity 5.0 sends signals to the radio units 3.1 and 4.1 which the radio units 3.1 and 4.1 convert into electrical signals inducing radio signals via the antennas 3.0 and 4.0 and vice versa.
• the 3.1 radio unit and the 5.0 network entity can be co-located, the link between the radio unit and the 5.0 network entity is then short, for example a few meters.
• the network entity 5.0 can also be located at a distance from the radio unit 4.1, for example several kilometers or tens of kilometers.
• a single network entity 5.0 is represented for the two radio units 3.1 and 4.1.
• each radio unit 3.1 and 4.1 can be served by a separate network entity, which is not shown in the figure, but the implementation of the invention in this case does not imply any particular modification with respect to the implementation depicted in Figure 1.
• a centralized unit (CU) 6 is also connected to the network entity 5.0.
• the separation of the functions of a base station means that it can consist of a centralized unit CU connected to one or more network entities DU, each DU being connected to one or more radio units RU.
• the geolocation of the mobile terminal 1 is done, among other things, by a measurement relating to the signal transmission travel time, for example reference signals such as the PRS, between the network entity 5.0 and the mobile terminal 1.
• a measurement relating to the signal transmission travel time for example reference signals such as the PRS
• the network entity 5.0 sends a PRS, denoted PRS1, to the mobile terminal 1 via the radio unit 3.1 and another PRS, denoted PRS2, to the mobile terminal 1 via the radio unit 4.1.
• the mobile terminal 1 measures the time difference RSTD between the times of reception of these 2 signals PRS.
• the RSTD Reference Signal Time Difference
• the RSTD does not take into account the transmission path time of the PRS1 and PRS2 signals on the links 3.2 and 4.2, these not having the same transmission characteristics.
• the transmission path times of the PRS1 and PRS2 signals on the links 3.2 and 4.2 that is to say between the network entity 5.0 and the radio units 3.1 and 4.1 respectively, are denoted t1 and t2 respectively.
• the measurement of times t1 and t2 can be made using dedicated signals S1 and S2 in the control plane, called comparison signals. Alternatively, this measurement can also be made directly on the PRS1 and PRS2 signals by the radio units 3.1 and 4.1. In this case, the reference signals PRS1 and PRS2 also serve as comparison signals.
• the geolocation of the mobile terminal 1 is estimated on the basis of a direct measurement of the difference in the transmission travel times of PRS1 and PRS2, i.e. RSTD.
• This method of geolocation is imprecise because it does not take into account the difference between times t1 and t2 in the calculation of RSTD.
• the transmission of PRS1 and PRS2 to determine the RSTD are triggered by a request to the geolocation server 7 (Geoloc) requesting the positioning of the mobile terminal 1. This may be required by an application of the mobile terminal 1 or by a request external to the terminal, for example by an authority distinct from the operator, to geolocate a person, that is to say the user 2 of the mobile terminal 1.
• the server 7 sends a request to the centralized unit 6 which controls the network entity 5.0 in order to obtain the data necessary for a geolocation of the mobile terminal 1.
• the centralized unit 6 then sends a command message to the entity 5.0 network to trigger the transmission of PRS1 and PRS2.
• the radio units 3.1 and 4.1 delay the PRS1 and PRS2 when they receive, before transmitting them to the mobile terminal 1.
• the time delay t12* applied is the same for all the radio units, and is calculated with respect to the instant of transmission of the reference signals PRS1 and PRS2 by the network entity.
• the times t1 and t2 being constant and all having the value of the time delay t12*, no longer need to be measured.
• the geolocation server 7 can perform precise geolocation without knowing the times t1 and t2 or their difference.
• FIG. 2 represents an example of implementation of the method for transmitting a downlink reference signal, according to one embodiment of the invention.
• the radio units are configured, that is to say that a value of the time delay t12* is recorded in the memory for each of the radio units 3.1 and 4.1. These values are communicated to the radio units 3.1 and 4.1 for example by the network entity 5.0, and can be identical or specific to the radio unit.
• the server 7 receives a geolocation request from the mobile terminal 1, for example, a request sent by a supervision entity further upstream in the network, or by an application in the mobile terminal 1.
• the server 7 sends an RSTD measurement request to the centralized unit 6.
• the centralized unit 6 sends a message through a control channel to the network entity 5.0 to trigger the PRS travel time measurement protocol.
• the central unit can also send this message to other network entities to which other radio units, not shown, are connected.
• the network entity 5.0 which received the message, transmits the reference signals PRS1 and PRS2, PRS1 being sent to the mobile terminal 1 via the radio unit 3.1 and PRS2 being sent to the mobile terminal 1 via the radio unit 4.1.
• the reference signals are timestamped at the time of their transmission by the network entity 5.0.
• the network entity 5.0 also transmits, in the control plane, the comparison signals S1 and S2 to the radio units 3.1 and 4.1 respectively.
• the comparison signals are timestamped at the time of their transmission by the network entity 5.0.
• the reference signals serve as comparison signals and it is not necessary for the signals S1 and S2 to be sent.
• these comparison signals can equally mean signals distinct from the reference signals, or identical.
• the reference signals PRS1, PRS2, and the comparison signals S1 and S2 can be transmitted periodically.
• one of the radio units 3.1 or 4.1 detects that the travel time of a comparison signal is greater than its time delay t12* stored during step St1, then, during a step St5' not illustrated in the FIG. 2, this radio unit sends an alert message, for example to the network entity 5.0, so that the value of the timeout period is revised upwards.
• the alert message may optionally include the measured value of the travel time of the comparison signal. If it is the radio unit which determines the new value of its timeout period, then this new value can be included in the alert message to the network entity.
• the method then stops, or returns to step St 1 .
• the radio units 3.1 and 4.1 receive the signals PRS1 and PRS2 transmitted by the network entity 5.0.
• the travel times between the network entity 5.0 and respectively the radio unit 3.1 and the radio unit 4.1 are denoted respectively t1 and t2.
• the radio unit 3.1 (respectively the radio unit 4.1) waits to do this the expiry of its time delay t12*, which was stored during step St1 and is greater than t1 (respectively t2).
• the radio unit 3.1 (respectively 4.1) transmits the signal PRS1 (respectively PRS2) to the mobile terminal 1.
• the mobile terminal 1 receives, at a priori different instants, the signals PRS1 and PRS2 emitted by the network entity 5.0, through the radio units 3.1 and 4.1 respectively, after a priori flight times different.
• the mobile terminal 1 calculates the RSTD on the basis of PRS1 and PRS2, ie the difference between the times of flight of the reference signals PRS1 and PRS2, and sends the result RSTD to the network entity 5.0.
• the network entity 5.0 receives the measurement RSTD of the time difference between the time of reception of PRS1 and PRS2 performed by the mobile terminal 1.
• the network entity 5.0 sends the RSTD to the server ?.
• the network entity 5.0 sends to the server 7 the time delay(s) t12* corresponding to the RSTD, possibly at the request of the server 7.
• the server 7 can determine the flight times of the reference signals PRS1 and PRS2, based on RSTD and t12*.
• the server 7 can then determine a position of the mobile terminal 1 on the basis of the times of flight of the signals PRS1 and PRS2, and possibly on the basis of other time of flight measurements obtained separately from other entity(ies). ) network and other radio units connected to other antennas.
• time delay t12* must therefore be set in order to keep a margin of time in the total propagation time between network entity and mobile terminal. However, it is not advisable to set t12* arbitrarily at 500ps to cover all cases. For example, the time delay t12* between the network entity 5.0 and the radio unit 3.1 can be set to a value 10% greater than the time t1.
• FIG. 3 presents an example of structure of a device for transmitting a downlink reference signal, according to one aspect of the invention.
• the transmission device 100 implements the method for transmitting a downlink reference signal, various embodiments of which have just been described. Such a device 100 can be implemented in a radio unit RU.
• the device 100 comprises a receiver 101, a transmitter 102, a processing unit 130, equipped for example with a microprocessor pP, and controlled by a computer program 110, stored in a memory 120 and implementing the method for transmitting a downlink reference signal according to the invention.
• the code instructions of the computer program 110 are for example loaded into a RAM memory, before being executed by the processor of the processing unit 130.
• Such a memory 120 such a processor of the processing unit 130, such a receiver 101 and such a transmitter 102 are capable of, and configured for:
• Figure 3 illustrates only one particular way, among several possible, of carrying out the algorithm detailed above, in relation to Figures 1 and 2. Indeed, the technique of the invention is carried out indifferently on a reprogrammable computing machine (a PC computer, a DSP processor or a microcontroller) executing a program comprising a sequence of instructions, or on a dedicated calculation machine (for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module) .
• a reprogrammable computing machine a PC computer, a DSP processor or a microcontroller
• a program comprising a sequence of instructions
• a dedicated calculation machine for example a set of logic gates such as an FPGA or an ASIC, or any other hardware module
• the corresponding program (that is to say the sequence of instructions) can be stored in a removable storage medium (such as for example a USB key , a floppy disk, a CD-ROM or a DVD-ROM) or not, this storage medium being partially or totally readable by a computer or a processor.
• a removable storage medium such as for example a USB key , a floppy disk, a CD-ROM or a DVD-ROM

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Mobile Radio Communication Systems (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2021
  • 2021-01-22 FR FR2100628A patent/FR3119245A1/fr not_active Withdrawn
• 2022
  • 2022-01-21 WO PCT/FR2022/050117 patent/WO2022157462A1/fr active Application Filing
  • 2022-01-21 US US18/262,293 patent/US20240118378A1/en active Pending
  • 2022-01-21 EP EP22705432.7A patent/EP4281795A1/de active Pending

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