Method for characterizing quality of radio link between vehicle and piece of ground equipment

Abstract

The method comprises:-measuring a parameter of interest of a radio link between a vehicle (3) and a piece of ground equipment (40) as a function of time or as a function of coordinates of the vehicle (3) along a predefined route, the parameter of interest being representative of a radio link quality; -measuring the coordinates as a function of time; -calculating readings of the parameter of interest as a function of the coordinates from the parameter of interest and the measurements of the coordinates; calculating a reference curve of the parameter of interest of a reference radio link between the vehicle (3) and the ground equipment (40) as a function of the coordinates; and characterizing the quality of the radio link by comparing the reading with the reference curve.

Description

[0001] The present invention relates to a method for characterizing the quality of a radio link between a vehicle (in particular a rail vehicle) moving along a predefined route and at least one ground device.

[0002] When moving along its route, a rail vehicle must perform constant radio communication with a server or IT device on the ground via radio equipment on the ground and on the train. If such radio communication is for signaling purposes, the vehicle is allowed to periodically transmit device information indicating its position along the route to the ground server / computer and, in response, to periodically receive authorization to proceed on the route from the ground server / computer device. The authorization to proceed is generated by a ground-based server / computer device and depends at least in part on the coordinates of the vehicle along the route.

[0003] When the vehicle does not receive any authorization to proceed within a specific time period, the vehicle stops moving along the route by applying a process called emergency braking. This emergency braking process disrupts traffic and, in some rare cases (long immobilizations), may put the vehicle and its occupants at risk.

[0004] The lack of authorization to proceed may be due to a deliberate failure to generate an authorization from the ground server / IT device, for example when the position of the vehicle along the route requires the vehicle movement to stop, or due to the deterioration of the radio link between the vehicle and the ground device, resulting in the inability to transmit information indicating the vehicle position and / or the authorization to proceed.

[0005] Such deterioration of radio communication may occur when the radio equipment on the vehicle and / or on the ground has a design or adjustment problem (change in the orientation of the antenna), when the said radio equipment deteriorates, when the radio environment is disturbed, for example when a new obstacle appears or when an interference phenomenon occurs.

[0006] Detecting or predicting the deterioration of the radio link between the vehicle and the ground device is very complex because they are usually not due to faults or obvious phenomena.

[0007] Currently, the convention is to first detect severe deteriorations of the radio link, which particularly lead to unwanted emergency braking processes, and then, in a second phase, to perform specific radio measurement activities aimed at precisely detecting and diagnosing the deterioration.

[0008] Then, these radio measurement activities are performed outside of service time during specified time slots using tools specifically designed for these tasks.

[0009] However, the monitoring and diagnosis of the deterioration are then performed under conditions that are not very representative of the actual driving conditions of the vehicle and are based on specific measurements specifically performed with the aim of detecting and identifying already suspected deteriorations.

[0010] One of the objectives of the present invention is to overcome these drawbacks by providing a method for monitoring the integrity of a radio link between a vehicle and a ground equipment component in an effective and precise manner.

[0011] To this end, the present invention relates to a method for characterizing the quality of a radio link between a vehicle (in particular a rail vehicle) moving along a predefined route and at least one piece of ground equipment, the position of the vehicle along the predefined route being characterized by coordinates along this predefined route at each point in time, the vehicle and at least one piece of ground equipment exchanging radio signals via a radio link, the method comprising the following steps:

[0012] - Measuring an interesting parameter of the radio link between the vehicle and at least one piece of ground equipment that varies over time or with the coordinates of the vehicle, the interesting parameter representing the quality of the radio link between the vehicle and at least one piece of ground equipment;

[0013] - Measuring the coordinates of the vehicle that vary over time;

[0014] - Calculating a reading of the interesting parameter that varies with the coordinates of the vehicle based on the measured value of the interesting parameter and the measured value of the coordinates;

[0015] - Calculating a reference curve of the interesting parameter of the reference radio link between the vehicle and at least one piece of ground equipment that varies with the coordinates of the vehicle; and

[0016] - Characterizing the quality of the radio link between the vehicle and at least one piece of ground equipment by comparing the reading of the interesting parameter with the reference curve of the interesting parameter.

[0017] Therefore, the present invention enables the quality of the radio link between the vehicle and the ground equipment to be characterized directly using one or more interesting parameters and the measured values of the coordinates associated with the vehicle.

[0018] Therefore, characterizing the quality of the radio link is based on the analysis of the radio link that actually connects the vehicle and the ground equipment component.

[0019] According to optional features of the characterization method obtained in isolation or in any technically possible combination:

[0020] - The vehicle is connected to one of the ground equipment components via a radio link useful for communicating with a ground station, and the measurement of the interesting parameter is performed to take into account the ground equipment component connected to the vehicle via the useful radio link;

[0021] - The measurement of the coordinates of the vehicle is performed by the vehicle to receive authorization from the ground station to advance along the predefined route;

[0022] - Characterizing the quality of the radio link between the vehicle and the at least one ground device includes calculating at least one radio link quality metric, the at least one quality metric being a variable having a value representative of a satisfactory quality of the radio link or a value representative of a degraded quality of the radio link;

[0023] - When the value of at least one quality metric represents a degraded quality of the radio link, characterizing the quality of the radio link further includes determining the cause of the degradation of the radio link;

[0024] - Determining the cause of the degradation of the radio link involves comparing the readings of the parameter of interest with the typical curves of the parameter of interest corresponding to different degradation causes;

[0025] - When the value of at least one quality metric represents a satisfactory quality but tends over time to a value representative of a degraded quality, characterizing the quality of the radio link further includes determining the duration after which the value of the quality metric will represent a degraded quality;

[0026] - Calculating a first quality metric involves decomposing the readings of the parameter of interest into components calculated by principal component analysis, and decomposing the reference curve of the parameter of interest into components calculated by principal component analysis;

[0027] - The at least one ground device includes a first radio transceiver unit and a second radio transceiver unit, the radio link including a first channel connecting the first radio transceiver unit and the vehicle and a second channel connecting the second radio transceiver unit and the vehicle, wherein calculating the first quality metric includes comparing the readings of the parameter of interest corresponding to the first channel of the radio link with the readings of the parameter of interest corresponding to the second channel of the radio link;

[0028] - Calculating at least a second quality metric is a function of the time taken for handover, packet loss, measured throughput, latency, and / or vehicle speed;

[0029] - Characterizing the quality of the radio link between the vehicle and the at least one ground device further includes considering additional analysis data;

[0030] - When the method includes the step of measuring the parameter of interest of the radio link between the vehicle and the at least one ground device over time, calculating the readings of the parameter of interest includes synchronizing a function representing the value of the parameter of interest measured over time and a function representing the value of the vehicle coordinates over time by associating the longest stationary segment or, respectively, multiple consecutive stationary segments of the function representing the value of the vehicle coordinates over time with the longest part or, respectively, multiple parts of the function representing the value of the parameter of interest measured over time, wherein the variance of the value of the parameter of interest is minimized; and

[0031] - When the method includes a step of measuring an interest parameter of a radio link between a vehicle and at least one ground device that varies over time, calculating a reading of the interest parameter includes correlating the interest parameter at a given time point with the vehicle coordinates at the given time point by interpolating, in the time domain, a function representing values of the interest parameter measured over time and a function representing values of the vehicle coordinates measured over time; and

[0032] - When the method includes a step of measuring an interest parameter of a radio link between a vehicle and at least one ground device that varies with the coordinates of the vehicle, calculating a reading of the interest parameter includes correlating the interest parameter having given coordinates with a time point corresponding to the vehicle coordinates by interpolating, in the spatial domain, a function representing values of the interest parameter measured over coordinates and a function representing values of the vehicle coordinates measured over time.

[0033] Other aspects and advantages of the present invention will become apparent after reading the following description, which is given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0034] Figure 1 Figure 1 is a schematic representation according to the present invention showing an assembly including a vehicle, two ground radio devices, and a ground station, the assembly being adapted to perform a method for characterizing a radio link between the vehicle and at least one ground radio device;

[0035] Figure 2 Figure 2 shows Figure 1 a detailed schematic representation of the assembly;

[0036] Figure 3 Figure 3 is a graph with the interest parameter as the ordinate and the vehicle coordinates as the abscissa, on which readings of the interest parameter of the radio link between the vehicle and the ground device that vary with the vehicle coordinates are due to the vehicle passing near the ground device part for the first time, readings of the interest parameter of the radio link between the vehicle and the ground device part that vary with the vehicle coordinates are due to the vehicle passing near the ground device part for the second time, and a reference curve of the interest parameter of the reference radio link between the vehicle and the ground device part that varies with the vehicle coordinates is superimposed;

[0037] Figure 4 Figure 4 is a schematic representation of a flowchart of a method for characterizing the quality of a radio link.

[0038] Reference Figure 1 and 2 ​​​​​​​​, the assembly 1 includes a vehicle 3 configured to move along a predefined route, at least one ground device 40 arranged along the predefined route, and a ground station 50.

[0039] The vehicle 3 is, for example, a guided land vehicle, in particular a rail vehicle. In this case, the predefined route is defined along a railway track (not shown).

[0040] The position of the vehicle 3 on the route is characterized at each time point by coordinates P along this route.

[0041] As will be detailed below, the vehicle 3 is configured to communicate with the ground station 50 via at least one ground device 40.

[0042] According to the example described in the present application, the assembly 1 includes a plurality of ground devices 40 distributed along the predefined route. Each ground device 40 is connected to the ground station 50.

[0043] The vehicle 3 is capable of connecting to at least one ground device 40 via a radio link. Specifically, the vehicle 3 is capable of exchanging radio signals with the ground device 40 to which it is connected via the radio link.

[0044] Hereinafter, a single ground device 40 will be described. It should be understood that each ground device 40 has the same structure and the same function.

[0045] The ground device 40 is generally a base station in the case of a mobile network, or generally an access point in the case of a Wi-Fi network.

[0046] The ground device 40 particularly includes at least one radio transceiver unit 42.

[0047] The radio transceiver unit 42 includes a transceiver 43 and at least one physical radio communication antenna 44 connected to the transceiver 43. The physical antenna 44 includes, for example, several radiating elements that constitute multiple-input multiple-output (“MIMO”).

[0048] As will be detailed below, for redundancy purposes, the ground device 40 preferably includes at least two radio transceiver units 42, particularly exactly two radio transceiver units 42. This is an example of a redundant configuration. There may be other configurations that achieve redundancy, for example, by deploying twice the number of ground devices 40 to provide redundant radio coverage.

[0049] For example, for full redundancy, the ground devices 40 are grouped in pairs, and the ground devices 40 of the same pair are substantially located at the same position along the route. Specifically, the ground devices 40 of the same pair provide substantially the same radio coverage. In other words, in the nominal operating case, the radio links between the vehicle 3 and each ground device 40 of the same pair are substantially the same.

[0050] Vehicle 3 is configured to communicate continuously with a ground station 50 via at least one of a plurality of ground devices 40. Specifically, vehicle 3 is configured to connect to the at least one ground device 40 via a radio link for communicating with ground station 50.

[0051] Advantageously, vehicle 3 is also configured to connect to at least one other of the plurality of ground devices 40 specifically via an auxiliary radio link.

[0052] When one ground device 40 includes two radio transceiver units 42, the radio link between vehicle 3 and the one ground device 40 includes a first channel connecting the first radio transceiver unit 42 of the one ground device 40 and vehicle 3 and a second channel connecting the second radio transceiver unit 42 of the one ground device 40 and vehicle 3. In this case, the radio equipment of vehicle 3 can switch to the second channel in the event of a connection loss on the first channel.

[0053] Advantageously, vehicle 3 is configured to communicate with ground station 50 to transmit its coordinates P to ground station 50 and, in response, receive authorization to proceed on the route from ground station 50.

[0054] Based on the coordinates P of vehicle 3, and for example in addition to the coordinates of other vehicles present on a predefined route, and also based on the movement plan of vehicle 3 on the route, etc., the authorization to proceed is specifically generated by ground station 50.

[0055] When vehicle 3 does not receive any authorization to proceed, it stops moving along the predefined route.

[0056] In order for vehicle 3 to be able to move along the predefined route under good conditions, it is therefore necessary to permanently ensure communication between vehicle 3 and ground station 50.

[0057] When vehicle 3 communicates with ground station 50 via one ground device 40, vehicle 3 is said to be paired with the one ground device 40.

[0058] By "communicating with the ground station" it is meant that vehicle 3 and ground station 50 exchange the coordinates of vehicle P and any authorization to proceed by exchanging radio signals between vehicle 3 and the ground device 40 paired with vehicle 3. In other words, the coordinates of vehicle P and any authorization to proceed are exchanged via the useful radio link between vehicle 3 and the ground device 40 paired with vehicle 3.

[0059] When the communication between the vehicle 3 and the ground station 50 is impaired, especially when the useful radio link between the vehicle 3 and the ground device 40 paired with the vehicle 3 deteriorates, or during nominal operation, when the vehicle has moved and the signal level on the useful radio link becomes too weak, the vehicle 3 pairs with another ground device 40, thereby allowing the exchange of coordinates P and any authorization to proceed on a predefined route. This operation is called handover. "Nominal operation" means that there is no specific phenomenon that causes abnormal deterioration of the useful radio link (which would be different from the attenuation of the radio signal exchanged by the useful radio link due to an increase in the distance between the vehicle 3 and the ground device 40 paired with the vehicle 3). When the useful radio link deteriorates abnormally, especially when there is redundancy in the radio architecture, the secondary radio link can become the useful radio link as an alternative. This operation is also called handover. Then, pairing the vehicle 3 with other ground devices 40 ensures that the coordinates of the vehicle P and any authorization to proceed are continuously exchanged between the vehicle 3 and the ground station 50, and thus ensures as smooth a progression of the vehicle 3 as possible on the predefined route.

[0060] Each radio link between the vehicle 3 and a ground device 40, especially each channel, is characterized by at least one parameter of interest Q. Specifically, the parameter of interest Q represents the quality of the radio link (especially the corresponding channel) between the vehicle 3 and the corresponding ground device 40.

[0061] For example, the parameter of interest Q is the received power level of the radio signal received by the vehicle 3 and transmitted from a ground radio device 40 via the corresponding radio link (especially the corresponding channel).

[0062] Advantageously, the parameter of interest Q is considered for handover between the vehicle 3 and various ground devices 40.

[0063] Hereinafter, as Figure 1 shown in the example of, it is considered that the vehicle 3 is configured to be connected to a first ground device 40 via a useful radio link L1 at a given point in time during its movement along the route to communicate with the ground station 50, and, for example, to be connected to a second ground device 40 via a secondary radio link L2. Of course, the present invention also applies when the vehicle 3 is connected to more than two ground devices 40 simultaneously.

[0064] According to Figure 1 the example shown, the useful radio link L1 includes a first channel C1 and a second channel C2. Here, the first channel C1 is the useful channel through which the vehicle 3 communicates with the ground station 50, and the second channel C2 is the secondary channel.

[0065] As Figure 2As shown, the vehicle 3 includes a positioning device 10 and a radio signal communication device 12 connected to the positioning device 10.

[0066] The positioning device 10 is configured to generate position data representing the coordinates P of the vehicle 3. For example, the positioning device 10 is a GPS signal receiver or a detection system for detecting ground beacons, the positions of which are known, and a wheel rotation and slip measurement system between the ground beacons enables the position of the vehicle 3 to be determined by interpolation.

[0067] The communication device 12 is capable of connecting to the first and second pieces of ground equipment 40 via respective radio links L1, L2.

[0068] In addition, the communication device 12 is configured to communicate with the ground station 50 via the first piece of ground equipment 40, in particular via the useful radio link L1, in particular via the useful channel C1, and communicate with the first piece of ground equipment 40.

[0069] The communication device 12 includes a radio transceiver unit 16 and a central unit 18 connected to the radio transceiver unit 16.

[0070] The radio transceiver unit 16 is configured to exchange radio signals with the first and second pieces of ground equipment 40, in particular with the radio transceiver unit 42 of the ground equipment 40, via respective radio links L1, L2.

[0071] As Figure 1 shown, the radio transceiver unit 16 of the communication device 12 includes, for example, a transceiver 19 and a physical antenna 20 connected to the transceiver 19. Advantageously, the radio transceiver unit 16 includes at least two transceivers 19 and at least two physical antennas 20 to ensure path redundancy of the radio signal to the ground station 50. In an alternative not shown, the vehicle 3 includes two radio transceiver units 16.

[0072] Advantageously, the radio transmission-reception unit 16 further includes measuring means for measuring the received power level of the radio signals received by the antenna 20 of the unit 16. Specifically, the measuring means for measuring the received power level of the received radio signals is configured to generate power level measurement data.

[0073] Each radio transceiver unit 16 is associated with an identifier, for example, uniquely. This identifier is used, for example, by the module 28 of the communication device 12 of the vehicle 3 to generate any set of measurement data of the parameter Q of interest of any radio link between the vehicle 3 associated with the identifier of the radio transceiver unit 16 and the corresponding piece of ground equipment 40. The identifier enables identification of which device on the vehicle performs the measurement.

[0074] The communication device 12 is configured to transmit, among other things, the following to the 40 ground devices 40 paired with the vehicle 3, namely the first ground device 40:

[0075] - Measurements of the coordinates P of the vehicle 3; and

[0076] - Measurements of the parameter Q of interest of the radio link between the vehicle 3 and a ground device 40 (here the first and / or second ground device 40).

[0077] More generally, the operating mode of a mobile radio system involves (at more or less close intervals) permanently measuring all the channels that a ground station might transmit. Thus, the measurements can involve multiple ground devices. The communication device 12 on the vehicle can select to connect to the ground device with the best signal. Thus, the measurement of the parameter of interest can involve multiple ground devices, which are associated with each measurement by the unique identifier assigned to them.

[0078] These measurements are transmitted, for example, in real time. In other words, the measurements are transmitted as soon as they are acquired. Alternatively, these measurements are stored on the vehicle and transmitted later.

[0079] The communication device 12 is further configured to receive from the 40 ground devices 40 paired with the vehicle 3 (i.e., the first ground device 40) any authorization to proceed generated by the ground station 50.

[0080] The communication device 12 includes: a module 28 for measuring the parameter Q of interest of the radio link between the vehicle 3 and one or more ground devices 40 (here, for example, the first and / or second ground device 40) that varies over time; a module 30 for measuring the coordinates P of the vehicle 3 that varies over time; and a radio link management module 32 for managing the radio link.

[0081] The modules 28, 30, and 32 are, for example, software modules that include software code instructions that can be recorded in a memory and executed by a processor. Alternatively, at least one of the modules 28, 30, and 32 is provided in the form of a programmable logic component or an application-specific integrated circuit.

[0082] The central unit 18 of the communication device 12 of the vehicle 3 includes, for example, a processor 22 and a memory 24, and the memory contains the modules 28, 30, and 32 provided in the form of software modules suitable for execution by the processor 22.

[0083] In an alternative, the module 28 is integrated into the transceiver 19 of the radio transceiver unit 16.

[0084] Module 28 is configured to measure an interest parameter Q of a radio link between vehicle 3 and a ground device 40 (the first and / or second ground device 40 herein) that varies over time. Specifically, module 28 is configured to measure the interest parameter Q of each channel of the radio link between vehicle 3 and ground device 40 over time. In other words, module 28 is configured to measure not only the interest parameter Q of the useful radio link L1 through which information passes, in particular the useful channel C1, but also the interest parameter Q of each auxiliary radio link L2 or each auxiliary channel C2, in order to allow handover decisions to be made.

[0085] Specifically, module 28 is configured to receive power level measurement data from radio transceiver unit 16, in particular from measurement means for measuring the received power level of radio signals received by antenna 20 of unit 16.

[0086] Generally, the measured values of the interest parameter Q are used to make pairing change decisions when pairing with a ground device 40 depending on the signal level of the ground device paired with vehicle 3. Generally, these measured values or their subsamples will be used for the purposes of the present invention. The subsampling is selected so as to preserve the basic characteristics of the signal depending on the location.

[0087] A first typical time interval between two measurements of the interest parameter Q is, for example, between 10 ms and 40 ms, in particular substantially equal to 20 ms. Thus, for example, module 28 is configured to measure the interest parameter Q of the radio link between vehicle 3 and a ground device 40, the first and / or second ground device 40 herein, every 20 ms.

[0088] Other interest parameters for evaluating radio quality can be measured, such as the time taken to perform a handover (change of pairing), packet loss, measured throughput, latency (round-trip time of radio signals between vehicle 3 and ground device 40).

[0089] As mentioned above, the interest parameter Q of the radio link is considered to determine possible changes (handovers) in the pairing between vehicle 3 and ground device 40.

[0090] For example, if the interest parameter Q of the useful radio link represents an unsatisfactory signal for exchanging the coordinates P of vehicle 3 and any authorization to proceed, then, where applicable, vehicle 3 is paired with another ground device 40 where the interest parameter Q of the radio link represents a satisfactory signal for said exchange.

[0091] In a particular instance, if the received power level of the radio signals exchanged by a useful radio link is below a predetermined threshold, then, where applicable, the vehicle 3 subsequently communicates with the ground station 50 via another piece of ground equipment 40 and thus via another radio link, specifically, where the received power level of the radio signals exchanged by the other radio link is above the predetermined threshold.

[0092] For example, the module 28 is configured to generate, for each measurement of the parameter of interest Q, a set of measurement data of the parameter of interest Q, and each set of measurement data of the parameter of interest Q includes:

[0093] - the piece of ground equipment 40 involved, in particular the identifier of the radio transceiver unit 42 of the piece of ground equipment 40 involved;

[0094] - the value of the parameter of interest Q measured; and

[0095] - the time point at which the measurement of the parameter of interest Q is performed.

[0096] The module 30 is configured to receive position data from the positioning device 10.

[0097] The module 30 is configured to measure, in particular at a second time interval that is constant, for example, between measurements, the coordinates P of the vehicle 3 that vary over time according to the position data. The second time interval is, for example, between 400 ms and 800 ms, and in particular is substantially equal to 600 ms. Thus, for example, the module 30 is configured to measure the coordinates P of the vehicle 3 every 600 ms.

[0098] For example, the module 30 is configured to generate, for each measurement of the coordinates P of the vehicle, a set of measurement data of the coordinates P, and each set of measurement data of the coordinates P includes:

[0099] - the measurement rank number with respect to the order of all the measurements performed for the coordinates P;

[0100] - the value of the coordinates P measured;

[0101] - the time point at which the measurement of the coordinates P is performed.

[0102] Advantageously, each set of measurement data of the coordinates P further includes:

[0103] - the speed of the vehicle 3; and

[0104] - the direction of movement of the vehicle 3.

[0105] Advantageously, the radio link management module 32 is suitable for changing the piece of ground equipment 40 paired with the vehicle 3, in particular according to the parameter of interest Q of the useful radio link and the parameter of interest Q of the secondary radio link.

[0106] Specifically, when the received power level of the radio signal exchanged by the useful radio link is lower than a predetermined threshold and when the received power level of the radio signal exchanged by the auxiliary radio link is higher than the predetermined threshold, the radio link management module 32 controls the radio transceiver unit 16 such that the vehicle 3 is not paired with the first piece of ground equipment 40 and is paired with the second piece of ground equipment 40.

[0107] The radio link management module 32 is further configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits the measured value of the parameter Q of interest to each radio transceiver unit 42 of the piece of ground equipment 40 paired with the vehicle 3.

[0108] Specifically, the radio link management module 32 is configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter, in other words, transmits a set of measurement data of the parameter Q of interest to the piece of ground equipment 40 paired with the vehicle 3 via the useful radio link, for example, in real time. Alternatively, this data is, for example, stored on the vehicle 3 and transmitted later.

[0109] For example, the radio link management module 32 is configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits a set of data of the parameter Q of interest determined continuously at a first time interval.

[0110] The radio link management module 32 is further configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits the measured value of the coordinates P of the vehicle 3 that vary over time to each radio transceiver unit 42 of the piece of ground equipment 40 paired with the vehicle 3.

[0111] Specifically, the radio link management module 32 is configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits a set of measurement data of the coordinates P to the piece of ground equipment 40 paired with the vehicle 3.

[0112] For example, the radio link management module 32 is configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits a set of measurement data of the coordinates P continuously at a second regular time interval.

[0113] Each piece of ground equipment 40 is uniquely associated with an identifier. As explained above, this identifier is used by the module 28 of the communication device 12 of the vehicle 3 to generate any set of measurement data of the parameter Q of interest for any radio link between the vehicle 3 and the piece of ground equipment 40 associated with said identifier.

[0114] For example, the unique identifier of the radio transceiver unit 16 is transmitted together with the measured values, and this enables these measured values to be matched with the vehicle 3 and in particular with the module 28.

[0115] As mentioned above, each ground device 40 includes at least one radio transceiver unit 42 with which the vehicle 3 is expected to exchange radio signals.

[0116] Advantageously, each ground device 40 includes at least two radio transceiver units 42, each radio transceiver unit being configured to provide substantially the same radio coverage. For example, these radio transceiver units 42 are substantially identical and are advantageously located substantially in the same position. According to a particular example, each ground device 40 includes exactly two units 42.

[0117] Advantageously, each radio transceiver unit 42 of each ground device 40 is uniquely associated with an identifier. This identifier is specifically also used by the module 28 of the communication device 12 of the vehicle 3 to generate any set of measurement data of the parameter of interest Q of any radio link between the vehicle 3 and the radio transceiver unit 42 associated with said identifier. The identifier of the radio transceiver unit 42 is used to identify which ground device has transmitted the signal being measured.

[0118] Each radio transceiver unit 42 of the same ground device 40 paired with the vehicle 3 is expected to receive the measured value of the parameter of interest Q transmitted by the radio transceiver unit 16 of the vehicle 3 and the measured value of the coordinate measurement P of the vehicle 3.

[0119] Each ground device 40 is configured to transmit to the ground station 50 the measured value of the parameter of interest Q that varies over time and the measured value of the coordinate P of the vehicle 3 that varies over time, both transmitted by the radio transceiver unit 16 of the vehicle 3.

[0120] According to the example shown in the present application, the ground station 50 includes a server configured to receive measurement data. Optionally, the ground station 50 further includes a signaling server configured to manage the movement of the vehicle 3 along the route, in particular to generate an authorization to proceed on the route. Alternatively, the ground station 50 includes an Internet access server configured to provide Internet access to the passengers located in the vehicle 3. According to another alternative, the ground station 50 includes a security server capable of processing security-related data (video surveillance images, passenger information) generated or processed by a dedicated device on the vehicle 3.

[0121] In a particular example, the measurement data is stored in a remote storage server. Specifically, the remote processing server has remote access to the storage server to retrieve the data and perform its processing.

[0122] In one embodiment, the ground station 50 includes a characterization assembly 52 configured to characterize the quality of the radio link between the vehicle 3 and the ground equipment 40 (the first and / or second ground equipment 40 herein).

[0123] The characterization assembly 52 includes a storage module 60, a module 62 for calculating a reading REL of an interesting parameter Q of the radio link based on the coordinates P of the vehicle, a module 64 for calculating a reference curve REF of the interesting parameter Q of the reference radio link based on the coordinates P of the vehicle, and a module 70 for characterizing the quality of this radio link.

[0124] Advantageously, the characterization assembly 52 further includes: a database 66 that groups data related to the vehicle 3 and the ground equipment 40; and a preparation module 68 for preparing data related to the vehicle 3 and the ground equipment 40.

[0125] The storage module 60 is configured to store measured values of the interesting parameter Q that vary over time and measured values of the coordinates P of the vehicle 3 that vary over time.

[0126] Specifically, the storage module 60 is configured to store a set of measurement data of the interesting parameter Q and a set of measurement data of the coordinates P of the vehicle 3.

[0127] The module 62 is configured to calculate a reading REL of the interesting parameter Q that varies with the coordinates P of the vehicle 3 based on the measured values of the interesting parameter Q that vary over time and the measured values of the coordinates P of the vehicle 3 that vary over time.

[0128] Specifically, the module 62 is configured to generate a function representing the value of the interesting parameter Q that varies over time based on the set of measurement data of the interesting parameter Q stored in the storage module 60, in particular based on the measured value of the interesting parameter Q and the time point at which the measurement of the interesting parameter Q is performed. The module 62 is further configured to generate a function representing the value of the vehicle coordinates P that varies over time based on the set of measurement data of the coordinates P stored in the storage module 60, in particular based on the measured value of the coordinates P and the time point at which the measurement of the coordinates P is performed.

[0129] Advantageously, the module 62 is further configured to synchronize the function representing the value of the interesting parameter Q that varies over time and the function representing the value of the coordinates P of the vehicle 3 that varies over time. In fact, the clocks of the capture systems of the interesting parameter Q on the one hand and the coordinates P of the vehicle 3 on the other hand that vary over time are not necessarily synchronized. Then, post-synchronizing the captured data allows these data to be processed jointly.

[0130] Specifically, module 62 is configured to synchronize the functions by correlating the longest stationary segment of a function representing the value of vehicle coordinates P varying over time with the longest part of a function representing the value of an interest parameter Q measured over time, where the variance of the value of the interest parameter Q is minimized. Specifically, this stationary segment represents a long stop of vehicle 3.

[0131] According to an alternative, module 62 is configured to synchronize the functions by correlating multiple consecutive stationary segments of a function representing the value of vehicle P coordinates varying over time with multiple parts of a function representing the value of an interest parameter Q measured over time, where the variance of the value of the interest parameter is minimized. Specifically, these stationary segments represent consecutive stops of vehicle 3.

[0132] Still advantageously, module 62 is configured to correlate the interest parameter Q at a given time point with the coordinates P of vehicle 3 at the given time point by interpolating in the time domain a function representing the value of the interest parameter Q measured over time and a function representing the value of the coordinates P of vehicle 3 varying over time.

[0133] Specifically, module 62 is configured to calculate a reading REL of the interest parameter Q varying with the coordinates P of vehicle 3 based on functions respectively representing the value of the interest parameter Q varying over time and the value of the coordinates P of vehicle 3 varying over synchronization time.

[0134] Although the interest parameter Q is carried by information linked to the position (e.g., the interest parameter Q will be the sequence number of a position message), on the contrary, the interpolation of radio measurements makes it possible to know which ground radio equipment the vehicle is connected to and the quality of the link when these messages are received.

[0135] Two readings REL of the interest parameter Q varying with the coordinates P of vehicle 3 are shown as examples in Figure 3 The interest parameter Q is expressed in dBm and the coordinates P are expressed in m.

[0136] The first reading REL corresponds to the radio link between vehicle 3 and ground equipment 40 during the first time vehicle 3 passes near ground equipment 40, and the second reading REL corresponds to the radio link between vehicle 3 and the same ground equipment 40 during the second time vehicle 3 passes near ground equipment 40. Alternatively, the second reading corresponds to another vehicle passing near ground equipment 40: if the vehicles have the same on-board radio equipment, in principle the readings will be substantially the same. If the readings are substantially different, matching several readings obtained by the vehicles makes it possible to cause a malfunction in the radio equipment on the vehicle and the other vehicle.

[0137] Module 64 is configured to calculate a reference curve REF of an interesting parameter Q of a reference radio link between vehicle 3 and a ground device 40, specifically a ground device 40 that characterizes the quality of a radio link, which varies specifically with the coordinates P of vehicle 3.

[0138] The reference curve REF represents the best radio signal exchange between vehicle 3 and the ground device 40 via the reference radio link.

[0139] For example, module 64 is configured to calculate the reference curve REF based on the measured values of the interesting parameter Q and the measured values of the coordinates P obtained when vehicle 3 is traveling under optimal conditions and when the radio transceiver unit 42 of the ground device 40 and the radio transceiver unit 16 of vehicle 3 are accurately calibrated.

[0140] The reference curve REF is shown by way of example in Figure 3 In Figure 3 the reference curve REF substantially corresponds to the reference radio link between vehicle 3 and the ground device 40 corresponding to the first and second shown readings REL.

[0141] The database 66 contains data related to vehicle 3, specifically related to the communication device 12 of vehicle 3, and data related to the ground device 40.

[0142] For example, the data stored in the database 66 are data related to the technical characteristics (structural characteristics, settings, etc.) of the radio transceiver unit 16 of vehicle 3 and the radio transceiver unit 42 of the ground device 40, data related to the position of the radio transceiver unit 42 of the ground device 40, data related to the environment around the radio transceiver unit 42 of the ground device 40 (the surrounding environment affecting signal propagation or nearby transmitting devices), and data related to the identifier of the ground device 40, specifically the radio transceiver unit 42 of the ground device 40, and data related to the geographical and operating environment (for example, in the case of the length and structure of the track, the position of the platform, the size and configuration of the tunnel, etc.).

[0143] The preparation module 68 is configured to format the data contained in the database 66 such that it can be used by the characterization module 60.

[0144] Specifically, the preparation module 68 is configured to generate a database prepared from the database 66, the data of which is suitable for use by the characterization module 70 to characterize the quality of the radio link.

[0145] The characterization module 70 is configured to characterize the quality of the radio link between vehicle 3 and the ground device 40 by comparing the reading REL of the interesting parameter with the reference curve REF of the interesting parameter Q.

[0146] Specifically, the characterization module 70 is configured to characterize the quality of a radio link based on data prepared by the preparation module 68 from the database 66.

[0147] The characterization module 70 includes, for example, a sub-module 74 for calculating at least one radio link quality metric, a diagnostic sub-module 76, and a prediction sub-module 78.

[0148] Advantageously, the sub-module 74 is configured to calculate at least one quality metric. The at least one quality metric is a variable having a value representing a satisfactory quality of the radio link or a value representing a degraded quality of the radio link.

[0149] For example, the variable takes a binary value depending on whether the quality is satisfactory or degraded. In a specific instance, when the quality is satisfactory, the quality metric is 1, and when the quality is degraded, the quality metric is 0. Alternatively, the variable takes a continuous value corresponding to the "distance" calculated between a reference curve and a reading.

[0150] Still advantageously, the sub-module 74 is configured to calculate a first quality metric. Specifically, to calculate the first quality metric, the sub-module compares the decomposition of the reading REL of the parameter of interest Q into components calculated by principal component analysis with the decomposition of the reference curve REF of the parameter of interest Q into components calculated by principal component analysis.

[0151] Specifically, the reading REL of the parameter of interest Q and the reference curve REF of the parameter of interest Q are respectively decomposed into linear combinations of basis functions. The reading REL of the parameter of interest Q and the reference curve REF of the parameter of interest Q are then characterized by the coefficients of their respective linear combinations. The vector including the coefficients of the linear combination of the reading REL of the parameter of interest Q and the vector including the coefficients of the linear combination of the reference curve REF of the parameter of interest Q are respectively referred to as the reading signature and the reference signature.

[0152] Specifically, the sub-module 74 is configured to calculate the mathematical distance between the reading signature and the reference signature, in other words, the mathematical distance between the vector including the coefficients of the linear combination of the reading REL of the parameter of interest Q and the vector including the coefficients of the linear combination of the reference curve REF of the parameter of interest Q. The distance is, for example, the Minkowski distance.

[0153] For example, when the distance between the reading signature and the reference signature is greater than a predetermined distance threshold, the sub-module 74 associates a value representing degraded quality with the first quality metric, and when the distance between the signatures is less than the predetermined distance threshold, the sub-module 74 associates a value representing satisfactory quality with the first quality metric. The predetermined distance threshold is advantageously selected to minimize the false alarm rate.

[0154] Advantageously, the sub-module 74 is configured to compare a reading REL of an interest parameter Q corresponding to a first channel of the radio link with a reading REL of the interest parameter Q corresponding to a second channel of the radio link. Since the radio coverage of the radio transceiver unit 42 of the ground device 40 is substantially the same, the readings REL of the interest parameter Q of the first and second channels of the radio link should be the same. A difference between the readings REL of the interest parameter Q of the first and second channels indicates a deterioration in the quality of the radio link channel.

[0155] Advantageously, the sub-module 74 is adapted to identify the absence of a set of measurement data of the vehicle coordinates P in the storage module 60 of the ground station 50. Such an absence is due, for example, to the failure to transmit the measured values of the coordinates P of the vehicle 3 from the vehicle 3 to the ground device 40 paired with the vehicle 3.

[0156] Specifically, when the storage module 60 of the ground station 50 does not store any set of measurement data of the coordinates P with rank number n and the storage module 60 of the ground station 50 stores two sets of measurement data of the coordinates P with rank numbers n - 1 and n + 1 respectively, the sub-module 74 is adapted to identify the absence of a set of measurement data of the coordinates P of the vehicle 3. Then, the sub-module 74 identifies that the nth measured value of the coordinates P of the vehicle 3 has never reached the ground station 50. Similarly, the absence of several consecutive data sets can be detected (for example, between n - 1 and n + 5 indicating the loss of 5 consecutive data sets).

[0157] Still advantageously, the sub-module 74 is configured to calculate at least one other quality metric, especially when the sub-module 74 identifies the absence of a set of measurement data of the coordinates P. The at least one second quality metric is, for example, a function of the percentage of lost position messages associated with the reading REL when the vehicle 3 passes by. This metric will enable the enrichment and improvement of the characterization of the quality of the radio link.

[0158] According to a specific example, the sub-module 74 is further adapted to associate each value representing the deterioration quality of the quality metric with the ground device 40 by associating the value of the quality metric with the identifier of a ground device 40 obtained from a set of measurement data of the interest parameter Q, especially with the radio transceiver unit 42 of the ground device 40, thereby calculating the value of the quality metric. This enables the differentiation of the ground devices 40 with deteriorated radio links.

[0159] Advantageously, the sub-module 74 is further configured to calculate other quality metrics, such as a second quality metric, based on packet loss, measured throughput, latency, the speed of the vehicle 3, etc. These metrics will enable the strengthening of the characterization of the quality of the radio link and the characterization of its impact on the applications using this link.

[0160] Advantageously, when the value of one or more quality indicators indicates degraded quality, in particular when the value of the first quality indicator indicates degraded quality, the diagnostic sub-module 76 is configured to determine the cause of degradation.

[0161] The cause of degradation is, for example, degradation of the electronic devices of the radio transceiver unit 42, incorrect orientation of one or more antennas 44 of the radio transceiver unit 42, incorrect settings of the radio transceiver unit 42, interference phenomena, etc.

[0162] Advantageously, the diagnostic sub-module 76 is adapted to access a database related to different radio link degradation causes. Data related to different degradation causes is obtained, for example, by simulation, or in a real situation, by voluntarily causing degradation causes during tests on the vehicle 3 and / or the ground equipment 40.

[0163] Data related to different degradation causes includes, for example, the association between the degradation cause and the typical curve of the parameter of interest Q that varies with the coordinates P of the vehicle 3 corresponding to the degradation cause.

[0164] Advantageously, the diagnostic sub-module 76 is configured to identify the cause of radio link degradation by comparing the reading REL of the parameter of interest Q with the typical curves of the parameter of interest Q corresponding to different degradation causes.

[0165] For example, the diagnostic sub-module 76 is configured to compare the decomposition of the reading REL of the parameter of interest Q into components calculated by principal component analysis with the decomposition of the typical curves of the parameter of interest Q corresponding to different degradation causes into components calculated by principal component analysis.

[0166] Alternatively or optionally, the diagnostic sub-module 76 is configured to determine the cause of radio link degradation based on the average value of the difference between the reading REL of the parameter of interest Q and the reference curve REF of the parameter of interest Q.

[0167] Specifically, when the average value of the difference between the reading REL of the parameter of interest Q and the reference curve REF of the parameter of interest Q is substantially constant (in other words, when the reading REL is offset from the reference curve REF by a substantially constant value), the diagnostic sub-module 76 determines that the parameter of interest Q decays continuously along the curve. Then, the diagnostic sub-module 76 determines that the cause of degradation is, for example, damage to the power amplifier of the radio transceiver unit 42, damage to the connector between the radio transceiver unit 42 and its antenna 44, or a change in the transmission power parameter of the radio transceiver unit 42.

[0168] Advantageously, these cases can be distinguished by analyzing the time evolution of the differences: for example, a change in the transmission power parameter will correspond to a sudden change, while damage to the connector may result in slow and progressive degradation.

[0169] Alternatively or optionally, the diagnostic sub-module 76 is configured to determine the cause of degradation of the exchanged radio signal based on the variance of the difference between the reading REL of the parameter of interest Q and the reference curve REF of the parameter of interest Q.

[0170] Alternatively or optionally, the diagnostic sub-module 76 is configured to determine which physical antenna 44 is degraded in the case where the ground transceiver unit 42 includes two physical antennas 44, each physical antenna aiming at opposite sides of, for example, the track on which the vehicle 3 is moving. Usually in such a case, the signal from the radio transceiver unit 42 is connected to the radio cable itself, which is connected to a splitter that divides the signal into two parts and allows two radio cables to be connected to each antenna 44. In such a case, for example, if only its corresponding curve is degraded, a problem with one of the two physical antennas 44 can be detected.

[0171] Alternatively or optionally, the diagnostic sub-module 76 is configured to detect that the degradation comes from a change in the antenna pointing (usually if the antenna has been screwed in incorrectly, it will gradually tilt downwards). By simulation, the diagnostic sub-module 76 can estimate the deformation that the reference curve REF or the reading REL will undergo for different tilt angles. By comparing the simulated curve with the observed curve, the diagnostic sub-module can then detect the problem and approximately quantify the tilt.

[0172] Alternatively or optionally, the diagnostic sub-module 76 is configured to detect that the degradation originates from a new obstacle in the radio propagation path. Then, the reading REL will be distorted with respect to the reference curve REF. Then, the diagnostic sub-module 76 is able to indicate the most likely cause of degradation as a new obstacle by ruling out possible changes in the tilt (using simulation or by detecting a constant offset).

[0173] Advantageously, the diagnostic sub-module 76 is configured to modify the database associated with the cause of degradation by associating the reading REL of the parameter of interest Q with the cause of degradation. For example, if a machine learning algorithm is used for degradation detection and diagnosis, the machine learning algorithm can be enhanced (reinforcement learning) based on this information and its accuracy can be automatically improved.

[0174] Advantageously, the diagnostic sub-module 76 is configured to further determine the cause of degradation based on direct or indirect interference measurements performed along the route. Generally, if a high interference level is derived from the measurement of the received signal level, for example less than 10 dB higher than the level of the useful signal, the reading REL is not changed. On the other hand, a high interference level reduces the auxiliary quality indicators that can be measured simultaneously, such as the noise level or the signal-to-noise ratio, the radio quality indicators measured on a 4G network (RSRQ, meaning "Reference Signal Received Quality"), or application indicators such as packet loss or throughput reduction. Additionally and optionally, interference can be explicitly measured by a dedicated radio module. The combination of these measurements makes it possible to infer the presence of interference and approximately locate the interference.

[0175] Advantageously, the diagnostic sub-module 76 includes a complete machine learning processing chain, which is configured to integrate all measurement values into its processing to automatically provide an accurate diagnosis.

[0176] Advantageously, predictions will be made by analyzing the time evolution of the metrics linked to the diagnosis, thus predicting the time evolution of the degradation.

[0177] Specifically, when the value of at least one quality indicator, particularly the value of the first quality indicator, represents a satisfactory quality, but tends over time to represent a value of degraded quality of the radio signal received by the vehicle, the prediction sub-module 78 is configured to determine the duration at the end of which the value of at least one quality indicator will represent a degraded quality of the radio signal received by the vehicle 3.

[0178] Advantageously, the characterizing assembly further includes a report establishment module 72 for establishing a report on the quality of the radio link.

[0179] Module 72 is configured to record, for each radio link between the vehicle and the radio transceiver unit 42 of the ground device 40, at least one quality indicator calculated by the sub-module 74, the cause of degradation of the corresponding radio link determined by the diagnostic sub-module 76 where applicable, and / or the duration at the end of which the value of at least one quality indicator will represent a degraded quality of the radio link determined by the prediction sub-module 78 where applicable.

[0180] Modules 60, 62, 64, 66, 68, 70, and 72 are provided, for example, in the form of software applications that can be recorded in the memory 56 and executed by the processor 54. Alternatively, at least one of these modules 60, 62, 64, 66, 68, 70, and 72 is provided in the form of a programmable logic component or an application-specific integrated circuit.

[0181] In an exemplary embodiment, the characterization assembly 52 is integrated into the ground station 50, which includes, for example, a processor 54 and a memory 56 that contains software modules 60, 62, 64, 66, 68, 70, and 72 suitable for execution by the processor 54.

[0182] In another exemplary embodiment, the characterization assembly 52 is virtualized and implemented using the physical resources of one or more computing devices, each of which is located within the ground station 50 or remotely located.

[0183] Hereinafter, with reference to Figure 4 , a characterization method 100 for characterizing the quality of a radio link between the vehicle 3 and at least one ground device 40 is described.

[0184] The vehicle 3 is connected to a first ground device 40 via a radio link for communicating with the ground station 50. Measuring an interest parameter Q is performed on all ground devices 40, the signals of which can be received and decoded for consideration to determine the ground devices 40 with which the vehicle 3 will connect via a useful radio link.

[0185] For clarity and brevity, the vehicle 3 is considered to be further connected to a second ground device 40 via an auxiliary radio link.

[0186] Method 100 includes a first step 110 of measuring an interest parameter Q of a radio link between the vehicle and a ground device 40 (the first or second ground device 40 herein) that varies over time.

[0187] Advantageously, the first step 110 is performed by a module 28 of the communication device 12 of the vehicle 3.

[0188] Herein, measuring the interest parameter Q of the radio link is performed by the vehicle 3 to consider determining the ground devices 40 via which the vehicle 3 communicates with the ground station 50.

[0189] For example, the interest parameter Q is measured at a constant first time interval between measurements.

[0190] Advantageously, the first step 110 includes measuring the interest parameter Q of a first channel connecting a first radio transceiver unit 42 that varies over time, and measuring the interest parameter Q of a second channel connecting a second radio transceiver unit 42 that varies over time.

[0191] Then, the method includes a second step 120 of measuring the coordinates P of the vehicle 3 that varies over time.

[0192] For example, the coordinates P of the vehicle 3 are measured at a second constant time interval between measurements.

[0193] Advantageously, the second step 120 is performed by the module 30 of the communication device 12 of the vehicle 3.

[0194] The measurement of the coordinates P of the vehicle 3 is performed here by the vehicle 3 in order to receive from the ground device 40 paired with the vehicle the authorization for the vehicle 3 to move forward on a predefined route, the authorization to move forward being transmitted by the ground station 50.

[0195] The measured value of the parameter Q of interest and the measured value of the coordinates P are transmitted by the vehicle 3 via the ground device 40 paired with the vehicle 3, in other words, via the useful radio link, to the ground station 50.

[0196] For example, the radio transceiver unit 16 of the vehicle 3 transmits the data set of the parameter Q of interest and the measurement data set of the coordinates P to the ground device 40 paired with the vehicle 3, in particular to the ground station 50.

[0197] The measured value of the parameter Q of interest varying over time and the measured value of the coordinates P of the vehicle 3 varying over time, in particular the measurement data set of the parameter Q of interest and the measurement data set of the coordinates P of the vehicle 3 are stored in the storage module 60 of the ground station 50.

[0198] The method then includes a third step 130 of calculating a reading REL of the parameter Q of interest varying as a function of the coordinates P of the vehicle 3 based on the measured value of the parameter Q of interest varying over time and the measured value of the coordinates P of the vehicle varying over time.

[0199] Advantageously, the third step 130 is performed by the module 62 of the characterization assembly 52.

[0200] Specifically, during the third step 130, the module 62 generates a function representing the value of the parameter Q of interest varying over time based on the measurement data set of the parameter Q of interest stored in the storage module 60, in particular based on the measured value of the parameter Q of interest and the time point at which the corresponding measurement of the parameter Q of interest is performed. In the third step 130, the module 62 further generates a function representing the value of the vehicle coordinates P varying over time based on the measurement data set of the coordinates P stored in the storage module 62, in particular based on the measured value of the coordinates P and the time point at which the corresponding measurement of the coordinates P is performed.

[0201] For example, the third step 130 includes synchronizing the function representing the value of the parameter Q of interest measured over time and the function representing the value of the coordinates P of the vehicle 3 varying over time by associating the longest stationary segment of the function representing the value of the coordinates P of the vehicle 3 varying over time with the longest part of the function representing the value of the parameter Q of interest measured over time, where the variance of the value of the parameter Q of interest is the smallest.

[0202] In an alternative, the third step 130 consists in synchronizing a function representing the value of the parameter of interest Q measured as a function of time and a function representing the value of the coordinates P of the vehicle 3 varying over time, by associating a plurality of successive stationary segments of the function representing the value of the coordinates P of the vehicle 3 varying over time with a plurality of parts of the function representing the value of the parameter of interest Q measured as a function of time, where the variance of the value of the parameter of interest Q is minimal.

[0203] Advantageously, the third step 130 further consists in associating the parameter of interest Q of the radio link at a given time point with the coordinates P of the vehicle 3 at the given time point by interpolating in the time domain the function representing the value of the parameter of interest Q measured as a function of time and the function representing the value of the coordinates P of the vehicle 3 varying over time.

[0204] Specifically, during the third step 130, the module 62 calculates a reading REL of the parameter of interest Q varying as a function of the coordinates P of the vehicle 62, based on functions respectively representing the synchronized values of the parameter of interest Q varying over time and of the coordinates P of the vehicle 3 varying over time.

[0205] Subsequently, the method includes a fourth step 140 of calculating a reference curve REF of the parameter of interest Q of the reference radio link between the vehicle 3 and the ground equipment 40, varying as a function of the coordinates P of the vehicle 3.

[0206] Advantageously, the fourth step 140 is performed by the module 64 characterizing the assembly 52.

[0207] Specifically, the module 64 calculates the reference curve REF based on the measured values of the parameter of interest Q and on the measured values of the coordinates P obtained when the vehicle 3 is traveling under optimal conditions and when the radio transceiver unit 42 of the ground equipment 40 and the radio transceiver unit 16 of the vehicle 3 are accurately calibrated.

[0208] Then, the method includes a fifth step 150 of characterizing the quality of the radio link between the vehicle 3 and the ground equipment 40 by comparing the reading REL of the parameter of interest Q with the reference curve REF of the parameter of interest Q. As described below, the fifth step 150 specifically includes the detection, diagnosis, and prediction of faults affecting the radio link.

[0209] Advantageously, the fifth step is performed by the characterization module 70 characterizing the assembly 52.

[0210] Even more advantageously, the characterization of the quality of the radio link is performed by artificial intelligence.

[0211] For example, the fifth step 150 includes a sub-step of calculating at least one radio link quality metric. The sub-step of calculating at least one quality metric specifically corresponds to the detection of faults affecting the radio link.

[0212] The sub-step of calculating at least one quality indicator is advantageously performed by a sub-module 74 of a characterization module 70 that characterizes the assembly 52.

[0213] Here, the sub-step of calculating at least one quality indicator, in particular the first quality indicator, involves comparing the decomposition of the reading REL of the parameter Q of interest into components calculated by principal component analysis with the decomposition of the reference curve REF of the parameter Q of interest into components calculated by principal component analysis.

[0214] Specifically, during the sub-step of calculating at least one quality indicator, the sub-module 74 calculates the mathematical distance between the read signature and the reference signature, in other words, the mathematical distance between the vector of coefficients of the linear combination including the reading REL of the parameter Q of interest and the vector of coefficients of the linear combination including the reference curve REF of the parameter Q of interest.

[0215] For example, the sub-step of calculating at least one quality indicator, in particular the first quality indicator, further includes comparing the reading REL of the parameter Q of interest corresponding to the first channel of the radio link with the reading REL of the parameter Q of interest corresponding to the second channel of the radio link.

[0216] Advantageously, during the fifth step 150, the sub-module 74 identifies that a set of measurement data of the vehicle coordinates P does not exist in the storage module 60 of the ground station 50. When the sub-module 74 identifies that a set of measurement data of the coordinates P does not exist, the sub-module 74 calculates another quality indicator and associates it with a value representing degraded quality.

[0217] Advantageously, when the value of one or more quality indicators represents degraded quality of the radio link, in particular when the value of the first quality indicator represents degraded quality, the fifth step 150 includes a sub-step of determining the cause of the degradation of the radio link. The sub-step of determining the cause of the degradation of the radio link particularly corresponds to the diagnosis of a fault affecting the radio link.

[0218] Specifically, the determination sub-step is performed by a diagnosis sub-module 76.

[0219] For example, the diagnosis sub-module 76 accesses a database related to different causes of degradation. The diagnosis sub-module 76 identifies the cause of degradation by comparing the reading REL of the parameter Q of interest with the typical curves of the parameter Q of interest corresponding to different causes of degradation.

[0220] Advantageously still, when the value of at least one quality indicator, in particular the first quality indicator, represents a satisfactory quality but tends over time to represent a deteriorating quality value, the fifth step 150 further includes a sub-step of determining the duration after which the value of the quality indicator will represent a deteriorating quality. The sub-step of determining the duration after which the value of the quality indicator will represent a deteriorating quality corresponds in particular to the prediction of a fault affecting the radio link.

[0221] For example, the fifth step 150 further includes calculating at least one other second quality indicator based on the time taken to perform a handover, packet loss, the measured throughput, latency, and / or the speed of the vehicle 3.

[0222] For example, the fifth step 150 further includes taking into account the additional analysis data provided, such as the interference level, the duration of a radio link change ("handover"), and the throughput observed on the radio link.

[0223] Advantageously, between the fourth step 140 and the fifth step 150, the method 100 includes an intermediate step of preparing the data stored in the database 66 by the preparation module 68. In the fifth step 150, the characterization of the quality of the radio link is then performed based on the prepared data.

[0224] Optionally, during the sixth step 160, the module 72 records, for each radio link between the vehicle and the radio transceiver unit 72 of the ground device 42, at least one quality indicator calculated by the sub-module 40, the corresponding cause of deterioration determined by the diagnostic sub-module 74 where applicable, and / or the duration after which the value of the quality indicator will represent a deteriorating quality determined by the prediction sub-module 76 where applicable. The elements stored in the module 72 can be analyzed by the operator to understand the quality of the radio link between the vehicle 3 and the ground device 40.

[0225] The characterization method is implemented by an electronic characterization device, in particular by steps of calculating a reading REL, calculating a reference curve, and characterizing the radio link.

[0226] Advantageously, the above invention is applicable to any automatic analysis allowed by machine learning.

[0227] According to an alternative, the module 28 of the device 12 is a module for measuring an interest parameter Q that varies with the coordinates of the vehicle 3.

[0228] Then, the module 62 is configured to calculate a reading REL of the interest parameter Q based on the measured value of the interest parameter Q that varies with the coordinates of the vehicle 3 and the measured value of the coordinates P of the vehicle 3 that vary over time.

[0229] Then, module 62 is advantageously configured to associate an interest parameter Q having a given coordinate P with a time point corresponding to the coordinate P of vehicle 3 by interpolating in the spatial domain a function representing the value of the interest parameter Q measured according to coordinate P and a function representing the value of the coordinate P of vehicle 3 measured according to time.

[0230] According to this same alternative, the first step 110 of method 100 is then a step of measuring an interest parameter Q of the radio link between the vehicle and the 40 ground devices that varies with the coordinates of the vehicle.

[0231] According to another alternative, the interest parameter Q of the radio link is the received power level of the radio signal received by the 40 ground devices and transmitted by vehicle 3 via the corresponding radio link.

[0232] Then, each radio transceiver unit 42 of the 40 ground devices includes measuring means for measuring the received power level of the radio signal received by the antenna 44 of unit 42.

[0233] Then, the memory 56 of the ground station 50 includes a module for measuring an interest parameter Q of the radio link between the 40 ground devices and vehicle 3 that varies over time, similar to module 28 of the communication device 12 of vehicle 3 described above.

[0234] According to this same alternative, the first step 110 is then performed by the module for measuring the interest parameter Q of the ground station 50.

[0235] According to another alternative, the useful radio link between vehicle 3 and ground station 50 is used to transmit data other than the data representing the signaling. For example, the useful radio link is used to transmit a remote monitoring video stream to ground station 50, or to provide a connection that allows the passengers of vehicle 3 to connect to the Internet via the Wi-Fi network on vehicle 3. The present invention is applied in the same way: it allows characterizing the vehicle-ground radio link. The position data can be obtained differently (e.g., via the position information sent by vehicle 3 for signaling purposes or via the existing GPS on vehicle 3).

[0236] Alternatively, the position data is not available and the curve of the interest parameter Q is time-dependent rather than position-dependent. This is analyzed by subtracting the starting time point from each interest curve. If all vehicles pass at the same speed, the curves can be analyzed jointly, otherwise transforming the curves allows comparison.

[0237] According to yet another alternative, the memory 24 of the vehicle 3 further includes a storage module 34 configured to store a measurement data set of the parameter of interest Q and a measurement data set of the coordinates P. Then, the radio link management module 32 is configured to control the radio transceiver unit 16 of the vehicle 3 such that the latter transmits the measurement data set of the coordinates P and the measurement data set of the parameter of interest Q stored in the storage module 34 to the ground device 40 paired with the vehicle 3.

[0238] The module 34 is, for example, a software module including software code instructions recordable in a memory and executable by a processor. Alternatively, the module 34 is provided in the form of a programmable logic component or an application specific integrated circuit.

[0239] The memory 24 includes the module 34, for example, in the form of a software module suitable for execution by the processor 22.

[0240] Thanks to the present invention, the quality of the radio link between the vehicle and the ground device is evaluated based on an analysis of the radio link actually connecting the vehicle and the ground device. Thus, the evaluated quality of the radio link is accurate as it is derived from the actual radio link.

[0241] In addition, these measurements can be performed during the network test phase before the regular service and during the regular service. In the latter case, it will perform measurements under actual operating conditions, for example by detecting the influence of two vehicles crossing, where one vehicle hides the radio network of the other vehicle, which is usually not tested during the network development phase. Finally and most importantly, when a problem occurs, almost no special investigation is required: it is sufficient to view the results of the most recently processed ones.

[0242] In addition, characterizing the radio link depends on the measurement of the parameter of interest performed by default by the vehicle or the ground station for handover between different ground devices. Thus, characterizing the radio link is effective to the extent that no specific measurement aimed at evaluating the quality of the radio link is required.

[0243] Thanks to the present invention, characterizing the quality of the radio link enables the detection of problems, their diagnosis and prediction. The present invention enables these tasks to be performed automatically and permanently using, for example, so-called machine learning techniques. The present invention can be summarized as a comparison of characteristic curves optionally enhanced with other relevant metrics. Machine learning algorithms naturally contribute to automatically performing this type of analysis. The present invention describes non-limiting examples. Thus, the present invention enables the automation of tasks usually performed by experts.

[0244] The invention also allows for predictive maintenance: by precisely detecting and identifying problems and tracking their evolution over time, it allows for the initiation of targeted predictive maintenance actions with sufficient advance notice to be able to do so, e.g., in the most favorable time slots.

Claims

1. A method (100) for characterizing the quality of a radio link between a vehicle (3), in particular a rail vehicle, moving along a predefined route and at least one ground device (40), wherein the position of the vehicle (3) along the predefined route is characterized by coordinates (P) along this predefined route at each point in time, and the vehicle (3) and the at least one ground device (40) exchange radio signals via the radio link, wherein the method (100) comprises the following steps: - measuring (110) an interest parameter (Q) of the radio link between the vehicle (3) and the at least one ground device (40) that varies over time or with the coordinates (P) of the vehicle (3), the interest parameter (Q) representing the quality of the radio link between the vehicle (3) and the at least one ground device (40); - measuring (120) the coordinates (P) of the vehicle (3) that vary over time; - calculating (130) a reading (REL) of the interest parameter (Q) that varies with the coordinates (P) of the vehicle (3) based on the measured value of the interest parameter (Q) and the measured value of the coordinates (P); - calculating (140) a reference curve (REF) of the interest parameter (Q) of a reference radio link between the vehicle (3) and the at least one ground device (40) that varies with the coordinates (P) of the vehicle (3), the reference curve (REF) representing the best radio signal exchange between the vehicle (3) and the at least one ground device (40) via the reference radio link; and - characterizing (150) the quality of the radio link between the vehicle (3) and the at least one ground device (40) by comparing the reading (REL) of the interest parameter (Q) with the reference curve (REF) of the interest parameter (Q).

2. The method (100) according to claim 1, characterized in that the vehicle (3) is connected to one of the ground devices (40) via a radio link for communicating with a ground station (50), and the measurement of the interest parameter (Q) is performed to take into account the ground device (40) connected to the vehicle (3) via the useful radio link.

3. The method (100) according to claim 2, characterized in that the measurement of the coordinates (P) of the vehicle (3) is performed by the vehicle (3) to receive authorization from the ground station (50) for the vehicle (3) to proceed along the predefined route.

4. The method (100) according to any one of claims 1 to 3, characterized in that characterizing the quality of the radio link between the vehicle (3) and the at least one ground device (40) includes calculating at least one radio link quality metric, the at least one quality metric being a variable having a value representing a satisfactory quality of the radio link or a value representing a degraded quality of the radio link.

5. The method (100) according to claim 4, characterized in that ​ When the value of the at least one quality indicator indicates a degraded quality of the radio link, characterizing (150) the quality of the radio link further includes determining the cause of the degradation of the radio link.

6. The method (100) according to claim 5, wherein, determining the cause of the degradation of the radio link comprises comparing a reading (REL) of the parameter of interest (Q) with typical curves of the parameter of interest (Q) corresponding to different causes of degradation.

7. The method (100) according to any one of claims 4 to 6, wherein, when the value of the at least one quality indicator indicates a satisfactory quality but tends over time to a value indicating a degraded quality, characterizing (150) the quality of the radio link further includes determining the duration after which the value of the quality indicator will indicate a degraded quality.

8. The method (100) according to any one of claims 4 to 7, wherein, calculating a first quality indicator comprises comparing the decomposition of a reading (REL) of the parameter of interest (Q) into components calculated by principal component analysis and the decomposition of a reference curve (REF) of the parameter of interest (Q) into components calculated by principal component analysis.

9. The method (100) according to claim 8, wherein, the at least one ground device (40) includes a first radio transceiver unit (42) and a second radio transceiver unit (42), the radio link includes a first channel connecting the first radio transceiver unit (42) and the vehicle (3) and a second channel connecting the second radio transceiver unit (42) and the vehicle (3), wherein calculating the first quality indicator includes comparing a reading (REL) of the parameter of interest (Q) corresponding to the first channel of the radio link and a reading (REL) of the parameter of interest (Q) corresponding to the second channel of the radio link.

10. The method (100) according to any one of claims 4 to 9, wherein, calculating at least a second quality indicator is a function of the time taken to perform a handover, packet loss, measured throughput, latency and / or vehicle speed.

11. The method (100) according to any one of the preceding claims, wherein, When the method includes the step of measuring (110) an interesting parameter (Q) of the radio link between the vehicle (3) and the at least one ground device (40) that varies over time, calculating (130) a reading (REL) of the interesting parameter (Q) includes synchronizing a function representing the value of the interesting parameter (Q) measured over time and a function representing the value of the coordinates (P) of the vehicle (3) that varies over time, by associating the longest stationary segment or, respectively, multiple consecutive stationary segments of the function representing the value of the coordinates (P) of the vehicle (3) that varies over time with the longest part or, respectively, multiple parts of the function representing the value of the interesting parameter (Q) measured over time, where the variance of the value of the interesting parameter (Q) is the smallest.

12. The method (100) according to any one of the preceding claims, characterized in that: - when the method includes the step of measuring (110) an interesting parameter (Q) of the radio link between the vehicle (3) and the at least one ground device (40) that varies over time, calculating (130) a reading (REL) of the interesting parameter (Q) includes associating the interesting parameter (Q) at a given time point with the coordinates (P) of the vehicle (3) at the given time point by interpolating in the time domain a function representing the value of the interesting parameter (Q) measured over time and a function representing the value of the coordinates (P) of the vehicle (3) measured over time; and - when the method includes the step of measuring (110) an interesting parameter (Q) of the radio link between the vehicle (3) and the at least one ground device (40) that varies with the coordinates (P) of the vehicle, calculating (130) a reading (REL) of the interesting parameter (Q) includes associating the interesting parameter (Q) with a given coordinate (P) with the time point corresponding to the coordinates (P) of the vehicle (3) by interpolating in the spatial domain a function representing the value of the interesting parameter (Q) measured according to the coordinates (P) and a function representing the value of the coordinates (P) of the vehicle (3) measured over time.

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