GB2612602A

GB2612602A - Road space collective perception message within an intelligent transport system

Info

Publication number: GB2612602A
Application number: GB2115836.5A
Authority: GB
Inventors: Le Houerou Brice; Morvan Isabelle; Sevin Julien; Tocze Lionel; Nassor Eric; Ruellan Hervé
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2021-11-04
Filing date: 2021-11-04
Publication date: 2023-05-10
Also published as: GB202118194D0; GB2612655A

Abstract

A Cooperative Intelligent Transportation System (C-ITS) includes reporting and/or receiving collective perception messages (CPM). The CPM 400 includes an element 401 (e.g. a space container) which describes a space (e.g. an area of a road topology) and comprises a field 402 indicating the space state. (Alternatively the element merely describes a space representing a specific area of a road topology.) The space state field may depend on a rule corresponding to a type of the space (e.g. lane, merge lane or parking) and may indicate occupancy of the space as an object count. The element may include an identifier of another space indicating that the space (171a,Fig.1) is a sub part of another space (171,Fig.1). It may include fields of a free space container or may be a container which can represent a space or a free space. An ITS station receiving the CPM may determine a global perception of the road situation from information in the element.

Description

ROAD SPACE COLLECTIVE PERCEPTION MESSAGE WITHIN AN INTELLIGENT TRANSPORT SYSTEM

FIELD OF THE INVENTION

The present invention relates generally to Intelligent Transport Systems (ITS) and more specifically to Cooperative Intelligent Transport Systems (C-ITSs).

BACKGROUND OF INVENTION

Cooperative Intelligent Transport Systems (C-ITSs) is an emerging technology for future transportation management that aims at improving road safety, traffic efficiency and drivers experience.

Intelligent Transport Systems (ITS), as defined by the European Telecommunications Standards Institute (ETSI), include various types of communication such as: communications between vehicles (e.g., car-to-car), and communications between vehicles and fixed locations (e.g., car-to-infrastructure).

C-ITSs are not restricted to road transport. More generally, C-ITSs may be defined as the use of information and communication technologies (ICT) for rail, water and air transport, including navigation systems. Such various types of C-ITSs generally rely on radio services for communication and use dedicated technologies.

C-ITSs are subject to standards, specified for each country and/or territory where C-ITSs are implemented. In Europe, the European Telecommunications Standards Institute (ETSI) is in charge of the elaboration of the specifications forming the standards to which C-ITSs are subjected.

Cooperation within C-ITSs is achieved by exchange of messages, referred as to ITS messages, among ITS stations (denoted ITS-Ss). The ITS-Ss may be vehicles, Road Side Units (RSUs), Vulnerable Road Users (VRUs) carrying an ITS equipment (for instance included in a smartphone, a GPS, a smart watch or in a cyclist equipment), or any other entities or infrastructures equipped with an ITS equipment, as well as central subsystems (back-end systems and traffic management centres).

C-ITSs may support various types of communications, for instance between vehicles (vehicle-to-vehicle or "V2V"), referring to all kinds of road users, e.g. car-to-car, or between vehicles and fixed locations such as vehicle-to-infrastructure or "V21", and infrastructure-to-vehicle or "12V", e.g., car-to-infrastructure.

Such messages exchanges may be performed via a wireless network, referred to as "V2X" (for "vehicle" to any kind of devices) networks, examples of which may include 3GPP LTE-Advanced Pro, 3GPP 5G or IEEE 802.11p technology.

Exemplary ITS messages include Collective Perception Messages (CPMs), Cooperative Awareness Messages (CAMs) and Decentralized Environmental Notification Messages (DENMs). The ITS-S sending an ITS message is named "originating" ITS-S.

EN 302 637-2 (V1.4.1 of April 2019) defines the Cooperative Awareness Basic Service through which an ITS-S transmits, using broadcast CAMs, its ego-vehicle dynamics (e.g. position, speed).

EN 302 637-3 (V1.3.1 of April 2019) defines the Decentralized Environmental Notification Basic Service through which an originating ITS-S can send, using broadcast DENMs, notifications to other ITS-Ss, such as warnings or alerts. Such a message notifies an event (e.g. road hazard, driving environment, traffic condition) detected by the originating ITS-S.

ETSI TS 103 324 (V0.0.22 of May 2021) defines the Collective Perception Service through which an ITS-S having local perception sensor systems detects objects in its vicinity and transmits, using broadcast CPMs, description information (e.g. dynamics such as position and/or kinematic information) thereof The Collective Perception service provides information about the ITS sub-system's environment such as road safety relevant objects (i.e. other road participants, obstacles and alike) detected by local perception sensors and/or free space information. For this purpose, the specified message provides generic data elements to describe detected objects in the reference frame of ITS sub-system. The CPMs are sent periodically with a period from 100 ms to 1 s depending for example on the speed of the objects sensed by the originating ITS-S. ETSI TS 103 301 (V1.3.1 of February 2020) defines the Map Extended Message through which an ITS-S can send map including road/lane topology data and traffic maneuver, using broadcast MAPEMs. The corresponding service to MAPEM is road and Lane Topology service (RLT). It is one instantiation of the infrastructure services to manage the generation, transmission and reception of a digital topological map, which defines the topology of an infrastructure area. It includes the lane topology for e.g. vehicles, bicycles, parking, public transportation and the paths for pedestrian crossings and the allowed maneuvers within an intersection area or a road segment. Also, ISO T519091 2016(E) defines "Cooperative ITS-Using V2I and I2V communications for applications related to signalized intersections" and more particularly the different types of road topology and the manner to describe its geometries.

Collective Perception Messages are able to deliver many information about the perceived objects and optionally about free space areas. CPMs are transmitted without relationship or hierarchy between objects. When a station wants to get information on the global situation in its neighborhood, it needs to analyze the information collected through all the received CPMs. This analysis might be time consuming for embedded devices as it is required to receive a lot of messages from independent perception results in order to get knowledge of road situation. Due to bandwidth constraints, CPMs may not convey information on all the perceived object of a station. Also, knowing only free space may not be sufficient.

A driver also has to manage his car driving to different rules depending on various road topology requiring at first a global perception to know how to handle it as an incoming situation. For example, a driver may adapt his driving more safely and stress less by knowing globally the situation under jam traffic condition, when entering on highway or when looking for a free place in car parking.

Collective Perception Service may advantageously be improved to facilitate a receiving station in determining a global perception of the road situation.

SUMMARY OF THE INVENTION

The present invention has been devised to address one or more of the foregoing concerns.

According to the invention, it is proposed to introduce a new type of object that may be signalled in a collective perception message (CPM) in addition of the existing perceived objects and free spaces. This new type of object would be a space area corresponding to a specific part of the road topology. It may be a road section, a crossing, a merging zone, for example. Some information relative to this area may be reported, like its occupancy, congestion, normal operation, for example. Accordingly, the receiving station gets at once a global information related to an area which is meaningful regarding the road situation in its neighbourhood.

In some embodiments, a hierarchy of space area may be defined for reporting different levels of global information related to a given road topology space.

According to a first aspect of the invention, it is proposed a method of communication in an Intelligent Transport System, ITS, comprising, at an originating ITS station: reporting in a collective perception message an element describing a space and

comprising a field indicating the space state.

In an embodiment, the space described by the element represents a specific area of a road topology.

In an embodiment, the element is a space container.

In an embodiment, the element comprises a rule of road space corresponding to a type of the specific area.

In an embodiment, the field indicating the space state depends on the rule of road space.

In an embodiment, the element comprises a field indicating the occupancy of the space as a number of detected objects in the space.

In an embodiment, the element comprises a field indicating a level of confidence on information provided by the element.

In an embodiment, the element comprises an identifier of another space indicating that the space is a sub part of the other space.

In an embodiment, the element comprises a geographical area definition of the space.

In an embodiment, the element comprise the fields of a free space container for describing a space not containing any perceived object.

In an embodiment, the element is a container which can represent a space or a free space According to another aspect of the invention, it is proposed a method of generation of a collective perception message in an Intelligent Transport System, ITS, comprising, at an originating ITS station: determining a space - determining a state of the space; generating a space container describing the space and comprising a field indicating the space state; and -embedding the space container in the collective perception message.

In an embodiment, the method further comprises: -determining a specific area of the road topology; and wherein -the determined space represents the specific area of the road topology.

In an embodiment, the method further comprises: determining another space representing a sub part of the specific area; - generating a space container describing the other space comprising an identifier of the space; embedding the space container describing the other space in a collective perception message.

According to another aspect of the invention, it is proposed a method of reception of a collective perception message in an Intelligent Transport System, ITS, comprising, at a receiving ITS station: -receiving the collective perception message; - obtaining an element describing a space and comprising a field indicating the space state;

S

-determining a global perception of the road situation from information comprised in the element.

In an embodiment, the space represents a specific area of a road topology.

In an embodiment, the method further comprises: obtaining another element describing another space representing a sub part of the specific area; -determining a detailed perception of the road situation from information comprised in the other element.

According to another aspect of the invention, it is proposed a collective perception message in an Intelligent Transport System comprising an element describing a space representing a specific area of the road topology.

According to another aspect of the invention, it is proposed a device of communication in an Intelligent Transport System, ITS, comprising a processor configured for: reporting in a collective perception message an element describing a space and

comprising a field indicating the space state.

According to another aspect of the invention, it is proposed a device of generation of collective perception message in an Intelligent Transport System comprising a processor configured for: -determining a space determining a state of the space; - generating a space container describing the space and comprising a field indicating the space state; and - embedding the space container in the collective perception message.

According to another aspect of the invention, it is proposed a device of reception of collective perception message in an Intelligent Transport System comprising a processor configured for: -receiving the collective perception message; -obtaining an element describing a space and comprising a field indicating the space state; determining a global perception of the road situation from information comprised in the element.

According to another aspect of the invention, it is proposed a computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing a method according to the invention, when loaded into and executed by the programmable apparatus.

According to another aspect of the invention, it is proposed a computer-readable storage medium storing instructions of a computer program for implementing a method according to the invention.

According to another aspect of the invention, it is proposed a computer program which upon execution causes the method of the invention to be performed.

At least parts of the methods according to the invention may be computer implemented.

Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system". Furthermore, the present invention may take the form of a computer program product embodied in any tangible medium of expression having computer usable program code embodied in the medium.

Since the present invention can be implemented in software, the present invention can be embodied as computer readable code for provision to a programmable apparatus on any suitable carrier medium. A tangible carrier medium may comprise a storage medium such as a hard disk drive, a magnetic tape device or a solid-state memory device and the like. A transient carrier medium may include a signal such as an electrical signal, an electronic signal, an optical signal, an acoustic signal, a magnetic signal or an electromagnetic signal, e.g. a microwave or RF signal.

BRIEF DESCRIPTION OF THE DRAVVINGS

Further advantages of the present invention will become apparent to those skilled in the art upon examination of the drawings and detailed description. Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings, in which: Figure 1 illustrates a typical Intelligent Transportation Systems (ITS) in which the invention may be implemented; Figure 2 illustrates a typical ITS station in which the invention may be implemented; Figure 3 illustrates an exemplary format of a CPM according to standard specification; Figure 4 illustrates an exemplary format of a CPM according to embodiments of the invention; Figures 5 illustrates, using flowchart, steps of methods to generate a space container to be transmitted over a CPM according to embodiments of the invention; Figures 6 illustrates, using a flowchart, more detailed steps of the method at the originating ITS-S according to embodiments of the invention; Figures 7 illustrates, using a flowchart, more detailed steps of the method at the receiving ITS-S according to embodiments of the invention; Figure 8 illustrates an alternative scenario for an implementation of an embodiment of the present invention, where the originating ITS-Ss are a road side unit and a vehicle observing an entrance of a motorway having a merging lane; Figure 9 illustrates another alternative scenario for an implementation of an embodiment of the present invention, where the originating ITS-S is a road side unit observing a parking area having free and busy places; Figure 10 shows a schematic representation of an example of a communication ITS-S device configured to implement embodiments of the present invention; Figure 11 illustrates a second exemplary format of a CPM according to some embodiments of the invention; Figure 12 illustrates a third exemplary format of a CPM according to some embodiments of the invention; Figure 13 illustrates a fourth exemplary format of a CPM according to some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The names of the lists and elements (such as data elements) provided in the following description are only illustrative. Embodiments are not limited thereto and other names could be 25 used.

The embodiments of the present invention are intended to be implemented in an Intelligent Transportation Systems (ITS).

The present invention proposes a single CPM, i.e. a collective perception message reporting a road state of a monitored road area according to road topology either defined as a MAPEM data or as a regional map data information or locally according to VVGS84 reference point with a list of layers used to describe the area topology using in particular layers permitting to identify for examples roadway section, Parking area or shared lane and the corresponding topography as specified in standard ISO 19091.

The originating ITS station, ITS-S, sending such CPM can quickly build it because containers describing the objects it perceives are usually already built in memory, in a so-called Local Dynamic Map or Environment Model.

On the other side, the receiving ITS-S concerned by the CPM containing space containers (e.g. to get global and detailed perception of the road situation) can obtain additional (compared to known technics) information from the single CPM combining multiple objects and transmitted more rapidly than CAMs or CPMs. It can then perform a quicker analysis of the situation with global and detailed perception.

Advantageously, each space containers can be analyzed independently from other space containers content as there positioning is absolute and/or aligned on road topology (for example by referring to WGS84 North or to MAPEM object). It permits to the receiving ITS-S S concerned by the CPM containing space containers to obtain a perception of the road situation even if not all relevant space containers are received. This property is particularly applicable to the space containers used to report for detailed perception (using sub-space as described in the invention).

An example of an ITS system 100 for implementation of embodiments of the invention is illustrated in Figure 1.

In this example, the originating ITS station, ITS-S, sending the CPM is a road-side unit, RSU. RSUs have advantageously more powerful resources to monitor a road segment situation than moving vehicles: for example, it may have a wider field of view, multiple fields of view, fast access to other information such as traffic conditions, traffic light status, knowledge of objects that populate the monitored area, etc. In particular, a better view of the monitored area allows an RSU to determine vehicle occupancy in road space according to the road topology with a better confidence as it's static ITS-S station positioned at a relevant traffic observation point. Nevertheless, the originating station may be any ITS station with a space area in its field of view.

ITS 100 is implemented in order to monitor a road segment, and comprises a fixed road side unit 110, and several entities, such that all these entities may carry or comprise ITS station (ITS-S) each, for transmitting and/or receiving ITS messages within ITS 100. The several entities may be for example vehicles 151,152,153, and 150. The vehicles 150,151 and 152 are moving while the vehicles 153 are stopped for any reason resulting in a jam traffic on the lane 161. The lane 161 is considered not normally operating while lanes 160 and 162 are normally operating.

The vehicle 150 transmits periodically it parameters using CAM 138 and contributes to the collection perception by transmitting CPM 139.

Fixed road side unit 110 includes a set of sensors, such as image sensors here video camera 120, an analytical module to analyze data provided by the sensors, such as a Situation Analysis module 111. Video camera 120 is configured to monitor or scan a monitored area, here the road topology, and thus reproduced images of the monitored area. In real situations, the camera 120 is likely composed of a set of cameras possibly complemented by different kinds of sensors.

The sensors and the analytical module, i.e. video camera 120 and Situation Analysis module 111, are connected so that the Situation Analysis module 111 processes the stream captured by the sensors/video camera. According to some embodiment, the analytical module and the sensors may be separate from or embedded within the same physical road side unit 110. For example, the analytical module may be wire-connected to the sensors that may be remote (i.e. not embedded in road side unit 110).

The processing by the analytical module, e.g. Situation Analysis module 111, aims at detecting objects potentially present in the monitored area, referred to as "perceived objects" or "detected objects" hereinafter. Mechanisms to detect such objects are well-known by one skilled in the art.

The analytical module, e.g. Situation Analysis module 111, is also configured to output a list of the perceived objects respectively associated with corresponding description information referred to as "state vector". The state vector for a perceived object may include for instance parameters such as position, kinematic, temporal, behavioural or object type classification information, etc. Therefore, the analytical module may also identify, among the perceived objects, different kinds of objects such as pedestrians, cyclists for example. It may also identify objects such as trees, road construction/work equipment (road barrier, ...), and so on.

For example, in the illustrated example, by scanning the monitored area, the Situation Analysis module 111 may perceive the following objects 150, 151,152 and 153 corresponding to vehicles on the roadway.

Further, the perceived objects may be classified, for example, according to whether the ITS station is a vehicle, a pedestrian, or a road side unit, or of another type. Such object type classification may be based for example on predetermined rules, provided during the setting up of road side unit 110, or more generally the ITS-S. ETSI TR 103 562 V2.1.1 defines for instance the categories "unknown", "vehicle", "person", "animal" and "other". Of course, other categories, more specific, can be defined.

The analytic module has some analysis function to analyze the monitored area of the perceived objects and is able to determine objects occupancy on various spaces. In Figure 1, road segments 160, 161 and 162 are monitored as spaces 170, 171 and 172.

The geometry of spaces is equal to the area defined in the map data of the monitored road. The map data are locally stored in storage 250 on Fig. 2 and/or broadcasted using MAPEM messages. The analytic module is able to determine a space state (SpaceState) for a monitored space.

The space state value may be determined according to the road rule (named road type).

The road type is available as map data either received by MAPEM of locally stored in storage 250. In Figure 1, the road type is a lane.

For a lane, The value '0' indicates the state "normal" meaning that vehicles move over the lane normally or the space is able to carry some vehicles without issue, the space is operating normally.

The value '1' indicates the state "abnormal meaning that the space is not operating normally because the lane cannot carry some vehicles or some vehicles are stopped on it. Any other value is considered as an abnormal state value.

In some embodiments, the analytic module may also be able to split those spaces in subspaces in order to obtain different space state values for the sub-spaces. For example, a space geometry is defined by a list of nodes forming a closed area. A node ('nodeXY) is composed of relative coordinates defined in map data stored in storage 250. The analytic module is able to create at least two sub-spaces by adding two nodes forming a segment cutting a space. It results in closed list of nodes describing sub-spaces. The analytic module performs a split when a space state value is not the default value ('0') and a sub-space having a space state with different value than can be determined.

In Figure 1, The analysis module 111 determines: - state of the space 170 is normal.

- state of the space 171 is abnormal.

state of the space 172 is normal.

The analysis module 111 splits the space 171 and obtains the space 171a with state value normal, the space 171c with state value abnormal and the space 171b with state value normal.

Finally, the road side unit 110, transmits the collective perception messages resulting from the analysis module 111. The CPMs contain a space container with, for example, the following information: SpacelD, an identifier of the monitored space SpaceState, the value of the space state as determined by the analysis module 111.

- SpaceParentID, the identifier of the parent space in case of sub-space.

SpaceOccupancy, number of objects detected by the analysis module 111 in the monitored space.

SpaceType, the road type as defined in the road topology information in the storage 250.

-SpaceArea, the geometry of the space composed of a list of nodes and geographic reference point (for example e.g. WG884 North) as defined in the standard 18019061. This information corresponds to an absolute location information.

The reporting of states to be included in Space Addendum containers, for example, in CPM message(s) to be transmitted by the RSU may contain the following information: SpacelD 170 171 172 SpaceState Normal abnormal Normal SpaceOccupancy 2 8 4 SpaceType Lane Lane Lane SpaceArea Road topography Road topography Road topography of lane 160 of lane 161 of lane 162 Additionally, the analytic module 111 determines 3 sub-spaces 171a, 171b and 171c having different state values and geometry. It is to be noted that the actual SpacelD is an integer identifier, not the string "171a" used as a reference on the figure.

The new sub-spaces information to be reported would be like this: SpacelD 171a 171b 171c SpaceParentID 171 171 171 SpaceState normal normal abnormal SpaceOccupancy 0 4 4 SpaceType Lane Lane Lane SpaceArea space geometry of spaces 171a space geometry of spaces 171b space geometry of spaces 171c The state of sub-space 171c is equals to the state value of its parent space 171. In this case, it's not necessary to transmit a CPM to report on sub-space 171c. it permits to reduce the number of Space Addendum Containers to be transmitted over CPM messages and therefore the size of the message. Alternatively, the CPM containing space 171c can be transmitted to get redundancy to overcome the loss of the CPM containing the parent space 171.

The vehicle 150 with ITS-S on board is also reporting using CPM 139 the state of the road lane 162 using it own sensors.

The CPM 139 reports on the sub-space 173 with the following information set: SpacelD=173 SpaceState='normal' - SpaceOccupancy=1 - SpaceType=lane'.

- SpaceArea= space geometry of spaces in front of vehicle 151.

The vehicle 150 with ITS-S on board is able to determine globally and quickly the traffic situation in the upcoming seconds by receiving the messages MAPEM 131, CPM 130, CPM 131 and CPM 132. Based on those messages, the driver of vehicle 150 is able to easily get a global perception of the road situation as illustrated by the forms 180, 181 and 182 representing the traffic conditions of the upcoming lanes on the vehicle road trip. Particularly, based on forms 180 and 182, the driver understands that the traffic is normal on lanes 160 and 162. The driver understands a traffic issue on lane 161 without details. It permits to get a first level of details corresponding to a global perception of the situation.

By receiving the messages CPM 131a and CPM 131b, the driver understands in details the traffic jam situation on lane 161. It permits to get a second level of details corresponding to a detailed perception of the situation. CPM messages having Space Addendum Container 130, 131, 132, are also named G-PCM meaning Global Collective Perception Message according to Figure 6. CPM messages having Space Addendum Container 131a and 131b are also named D-PCM meaning Detailed Collective Perception Message according to Figure 6.

Figure 2 illustrates a typical ITS station in which the invention may be implemented.

For the purpose of illustration, it is considered here RSU 110, any other type of ITS-S-equipped entity may be used.

As mentioned above, situation analytic module 111 is connected to one or more sensors monitoring the road intersection for example. These may include cameras 220-223 but also other sensors such as, for example, LIDARs (laser imaging detection and ranging devices) 210 or radars.

The perceived objects detected by each sensor are analyzed by a Sensor data fusion module 230 in order to fuse or merge the same objects detected by several sensors. Consideration of similarity between objects from different sensors can be based on their object types, positions, kinetics/dynamics (speed, acceleration), trajectories, etc. A level of confidence may also be computed when scrutinizing the similarities of these information items and the fusion can be performed when the level of confidence is high enough.

Newly perceived objects or updates about already-tracked objects are used to update an environment model 260 of the ITS-S. CAMs and CPMs, conveying additional information, can also be used to update environment model 260.

The environment model is also known as the Local Dynamic Map and contains a list of the perceived objects. Each ITS-S has its own environment model 260.

An object in the environment model 260 is described by multiple information items including all or part of: -objectID: an identifier of the detected object, -SensorlD (optional): a list of sensors that have perceived the object, -fime0fMeasurement: a time when the (last) measurement was made, -stationID (optional): an ITS-S identifier associated with the perceived object, with a corresponding level of confidence. The confidence level can be computed based on the accuracy of a position contained in a received CAM (comprising an ITS ID) and the position measured by the local sensors. In a variant, it is computed based on the number of perceived objects versus the number of transmitting ITS-Ss for a zone, -objectRefPoint (optional): a reference point corresponding to a reference point of the detected object. By default, the reference point is the centre point of the detected object, -Distance: a distance determined according to a frame of reference fixed to the originating ITS-S, here RSU 110. For example, the distance is determined relatively to three directions x, y, z of the frame of reference, such that the distance is indicated within three fields xDistance, yDistance, zDistance, which represent together the distance between the perceived object and the originating ITS station's reference point at the time of measurement, with a corresponding level of confidence, -Speed: a speed with respect to originating ITS station's reference point at the time of measurement. For example, the speed is determined relatively to three directions x, y, z of the frame of reference such that the speed is indicated within three fields xSpeed, ySpeed, zSpeed, representing together the speed of the detected object, with a corresponding level of confidence, -Acceleration (optional): an acceleration with respect to originating ITS station's reference point at the time of measurement. For example, similarly to the speed, the acceleration is indicated within three fields)(Acceleration, yAcceleration, zAcceleration relatively to the three directions of the frame of reference fixed to the originating ITS-S, with a corresponding level of confidence, -dynamicStatus (optional): a dynamic Status providing the capabilities of the originating ITS-S to move away from the perceived object, -planarObjectDimension (optional): a dimension indicating the dimensions of the perceived object. The dimension may be indicated within three fields planarObjectDimension1, planarObjectDimension2, verticalObjectDimension, and -Classification (optional): a classification providing the classification of the perceived object, with a corresponding level of confidence.

For example, a CPM sent by an originating ITS-S wishing to share perceived object information includes containers (Perceived Object Containers), each listing such information for the corresponding perceived object.

The analytic module 111 has some analysis function to determine objects occupancy on those various road areas associated with spaces.

Situation analysis module 240 continuously tracks the objects contained in its environment model 260. This is to determine objects presence in road areas as associated with 25 spaces.

The geometry of a space is equal to the corresponding area defined in the map data of the monitored road. The map data are locally stored in a storage 250 and/or broadcasted using MAPEM messages. The analytic module determines a space state (SpaceState) for a monitored space according to the road type.

The space state value is determined according to the road rule according to the road type, which is reported as SpaceType. The road type may also be obtained from the map data either received by MAPEM and/or locally stored in the storage 250.

In general, or if the SpaceType is not specified, a space state value can be "empty" meaning that there are no object detected in the space (equal to '0') or "not empty" meaning that at least one object has been detected in the space (equal to '1'). The default value is empty.

In another embodiment, the space state value can also have some variations according to the space type.

In a first embodiment, as illustrated in Figure 1 with a SpaceType is equal to 'lane'. The rule of a lane is to carrier some vehicles. Accordingly, a lane state is normal when the vehicles can move over this lane otherwise if one or more vehicle are stopped or are moving slowly for any reason, the lane state is abnormal. The following space state values may be used: * the value '0' indicates the state normal meaning that the space is operating normally, it means that the vehicles are moving over this space without issue * the value '1' indicates the state abnormal meaning that the space is not operating normally, one or more vehicles are stopped in this space.

* Any other value indicates that the space state is abnormal. Optionally, different values can be used to deliver a cause of the operating issue (accident, traffic jam, closed...) In a second embodiment as illustrated in Figure 8 within a SpaceType equal to 'parking', the following space state values can be used: * The value '0' indicates the state free meaning that the space is free for parking a car * The value '1' indicates the state busy meaning here that the space is busy and not available for parking a car.

In a third embodiment as illustrated in Figure 9 within a SpaceType equal to 'merge lane', the following space state values can be used: * The value '0' indicates the state free meaning that the space is ready for merging because this space is free from any car.

* The value '1' indicates the state busy meaning that the space is not free and it's not available for merge operation.

In a fourth embodiment not illustrated within a SpaceType equal to 'pedestrian cross walk', the following space state values can be used: * The value '0' indicates the state free meaning that no pedestrian are present in the space.

* The value '1' indicates the state busy meaning that there are pedestrian in the space.

In some embodiments, the analytic module can also split those spaces in sub-spaces in order to obtain different space state values for the sub-spaces. For example, a space geometry is defined by a list of nodes forming a closed area. A node ('nodeXY') is composed of relative coordinates defined in map data stored in storage 250. The analytic module is able to create at least two sub-spaces by adding two nodes forming a segment cutting a space. It results in closed list of nodes describing sub-spaces. The analytic module performs a split when, at least, two subspaces can be obtained having two different space state values.

Based on this space monitoring, Space Addendum Container is created including different fields to be added in CPM message. as illustrated in Figure 4. The CPM is conventionally sent by R-ITS-S 112 of RSU 110.

An exemplary format of a CPM 300 according to ETSI TS 103 324 (V0.0.22 of May 2021) is illustrated in Figure 3.

A CPM 300 contains an ITS PDU header 310 and a "CPM Parameters" field 320.

ITS PDU header 310 is a common header that includes the information of the protocol version, the message type and the ITS-S ID of the originating ITS-S.

"CPM Parameters" field 320 contains a Management Container 330, a Station Data Container 340, a set of Sensor Information containers 350, a set of Perceived Object containers 360 and a set of Free Space Addendum Containers 370.

Regardless of which type of ITS-S generates a CPM, the Management Container provides information regarding the Station Type and the Reference Position of the originating ITS Station. The message can be transmitted either by a ITS Station, such as a vehicle, or by a stationary RSU. In case of a CPM generated by a vehicle, the Station Data Container contains the dynamic information of the originating ITS Station. It is not optional in case of a vehicle transmitting the CPM. In case of a CPM generated by a RSU, the Station Data Container may provide references to identification numbers provided by the MAP Message (CEN ISO/TS 19091) reported by the same RSU. These references are required in order to match data provided by the CPM to the geometry of an intersection or road segment as provided by the MAP message. It is not required that a RSU has to transmit a MAP message for matching objects to road geometries. In this case, the Station Data Container may be omitted. It is for this reason that the Station Data Container is set as optional.

Each Sensor Information container contained in the set of Sensor Information containers 350 is optional. It provides information about the sensory capabilities of an ITS station. Depending on the station type of the originating ITS station, different container specifications are available to encode the properties of a sensor. The Sensor Information Containers are attached at a lower frequency than the other containers, as defined in ETSI TR 103 562. Up to 128 containers of this type may be added.

Each Perceived Object Container contained in the set of Perceived Object containers 360 is optional. It is composed of a sequence of optional or mandatory data elements (DEs) which give a detailed description of the dynamic state and properties of a detected object.

More precisely, each object has to be described using structure 380 by at least an identifier (defined by the DE ObjectID), a time of measurement (defined by the DE time0fMeasurement) referred to as corresponding to the time difference for the provided measurement information with respect to the generation delta time stated in the management container, a distance (defined by the DEs xDistance and yDistance) and a speed (defined by the DEs xSpeed and ySpeed) in the x/y plane of the respective coordinate system with respect to a station's reference point.

Moreover, several optional DE are available, to provide a more detailed description of a perceived object as acceleration (defined by the DEs)(Acceleration and yAcceleration), dynamic Status (defined by the DE dynamicStatus) or classification (defined by the classification DE).

Distance, Speed and Acceleration values can also be provided in three dimensions (respectively with the DEs zDistance, zSpeed and zAcceleration) along with the yaw angle of the object (defined by the DE yawAngle). Furthermore, a three-dimensional description of an object's geometric extension can be provided (with the DEs planarObjectDimension1, planarObjectDimension2 and verticalObjectDimension). Moreover, a RSU is also able to provide a map-matching result for a particular object with respect to the MAP information (defined by the DE matched Positio n).

Each Free Space Addendum Container contained in the set of Free Space Addendum Containers 370 is optional. It is composed of a sequence of optional or mandatory data elements (DEs) which provide information of detected free space performed by a particular sensor. More precisely, each Free Space has to be described using structure 390 by at least a confidence (defined by the DE FreeSpaceConfidence), a space area geometry (defined by the DE FreeSpaceArea), the sensors used to monitor the free space (optional, defined by the DE SensorlD) and a flag shadowingApplies indicating that shadowing mechanism applies within the area described by freeSpaceArea. The flag shadowingApplies is a Boolean indicator to indicate if tracing approach should be used to compute a shadowed area behind an object. If set to TRUE, the simple tracing approach should be applied for each object intersecting or located within the area or volume described by the freeSpaceAddendum container. If set to FALSE, the simple tracing approach should not be applied for each object intersecting or located within the area or volume described by the freeSpaceAddenum container.

Collective Perception Messages don't permit to determine the situation globally according to the car driver intention and to help his decision. From car driver point of view, it's more relevant to obtain different level of details of the road situation as it happens with natural perception. At first, a driver looks at getting a global perception of the road situation in order to take a decision and, in second, he looks at getting detailed information only useful to execute his previous decision and to adapt precisely his driving.

An exemplary format of a CPM according to embodiments of the invention is illustrated in Figure 4. It is based on a CPM format used to report on a space monitoring using Space Addendum Container instead of / or complementary to free space monitoring using Free Space Addendum Container as specified in the version 1.3.1 of the EIS! TS 103 324 (V0.0.22 of May 2021) specification as shown in Figure 3.

The Perception Data container composed of 350, 360 and 370 is extended in order to integrate Space Addendum Container 401 used by the invention. It results in a new perception Data Container 400.

Each Space Addendum Container contained in the set of Space Addendum Containers 401 is optional. It is composed of a sequence of optional or mandatory data elements (DEs) which provide information of space performed by one or more sensors. More precisely, each space monitored can be reported using structure 402 comprising at least a Space identifier (defined by the DE SpacelD), a space state (defined by the DE Spac,eState) and the geometry of the area monitored as a space (defined by the DE SpaceArea). Optionally, Space Addendum Container may also report the space occupancy (defined by the DE SpaceOccupancy). Space Addendum Container may also report the space relationship with another space, considered it's a subpart of this other space, using a parent identifier (defined by the DE SpaceParentID). Space Addendum Container may also report the type of road area monitored as a space (defined by the DE SpaceType). Space Addendum Container may also report the confidence of the determined space state (defined by the DE SpaceConfidence). The confidence value is derived by the computation of the space monitoring confidence based on a sensor's or fusion system's specific detection. The confidence value indicates a level of confidence of the measurement, consisting of determining presence of object over a monitored space from 0 (no confidence) to 100 (highest confidence level).

A detailed description of Space Addendum Container 402 according to some embodiments may be as follow.

SpacelD is an identifier assigned to a monitored space as an object which remains constant as long as the space is perceived by the originating ITS-S. Numbers are assigned in an increasing round-robin fashion. When the last identifier in the allowed range has been used, the first counter for the identifier starts from the beginning of the range again.

SpaceState is a value indicates that the monitored space is either in a default state corresponding to the state empty (equal to 0) or not empty (value equal to or greater than 1). The default value is 0. The possible values can also have some variations according to the SpaceType as derived from road type.

For a SpaceType value equal to 'lane', the following space state values can be used: The value '0' or normal indicates the space is operating normally, the vehicles are moving over this space.

The value '1' or abnormal indicates the space is not operating normally because some vehicles are stopped or their speed is abnormally slow.

Any other value indicates that the state value is abnormal due to a road cause.

For a SpaceType equal to 'parking', the following space state values can be used: The value '0' indicates the state free meaning that the space is free for parking a car. The value '1' or greater indicates the state busy meaning that the space is not available for parking a car.

For a SpaceType equal to 'merge lane', the following space state values can be used: The value '0' indicates the state free meaning that the space is available for merging operation.

The value '1' or greater indicates the state busy meaning that the space is not available for merging operation.

SpaceParentID is an identifier (same data element as SpacelD) of the parent space if any. This DE is optional. The SpaceParentID value is determined during the algorithm illustrated by Figure 6 in step 650 for example.

SpaceOccupancy is a value used to report on the occupancy as a global evaluation of the monitored space. The value can be the number of vehicles detected in the monitored space by the analysis module 111. This DE is optional.

SpaceType is a value used to indicate the type of the monitored space. It can be derived from the DE Road attributes. For example, SpaceType value can be a lane, a merged lane, a diverged lane, a parking, a cross walk or any other type of road topology. The possible values can be extended using standard EN ISO T519091, SAE J2735.

SpaceConfidence is a level of confidence of the measurement from 0 (no confidence) to 100 (highest confidence level). This value is derived by the computation of the space monitoring confidence based on a sensors or fusion system's specific detection 230 confidence on the analysis module 111.

SpaceArea is a Geographical Area Definition of the monitored space according to EIS! EN 302 931.

In some embodiments as illustrated in Figure 11, the space container 402a may comprise the existing fields of a free space container. In some embodiments as illustrated in Figure 12, the CPM 400a may only comprise a space container that may represent either a free space or a space associated with a specific road area. FreeSpaceConfidence field and SpaceConfidence field can be represented by the same filed. FreeSpaceArea field and SpaceArea field can be represented by the same filed.

In some embodiments as illustrated in Figure 13, the CPM 400b may comprise only free space container 370a that may comprises fields 402b described above for a space container.

As specified in the standard, the generation of a CPM to be transmitted relies on the generation of a CPM event as specified in section 6.1.3.1 (refer to CP Message generation frequency management of the ETSI TS 103 324 (0.0.22).

In the current version of the standard, a CPM may contain perceived Object Containers 360 and/or Free Space Addendum Containers 370 (in addition to Management container).

More specifically, the current version of the standard includes specific inclusion procedures. Specific inclusion procedures specify the inclusion of the perceived Object Containers in section 6.1.3.2 and the inclusion of the Free Space Addendum Containers in section 6.1.3.4.

The inclusion procedure of the perceived Object Containers comprises a set of specified conditions, referred to as perceived Object Inclusion conditions. In particular, a perceived Object Container comprising updated information relating to a previously perceived object is included in the next CPM to be transmitted if one of the following conditions is met: the updated information of the perceived object has first been detected after the last CPM event generation, or - the Euclidian absolute distance between the lastly reported position and the current updated position of the reference point of the perceived object exceeds a predetermined threshold, minReferencePointPositionChangeThreshold, or the elapsed time since the last time the object was reported exceeds a predetermined threshold T_GenCpmMax.

The inclusion procedure of the Free Space Addendum Containers comprises a set of specified conditions, referred to as Free Space Inclusion conditions. In particular, a Free Space Addendum Container comprising updated information relating to a previously perceived free space is included in the next CPM to be transmitted if one of the following conditions is met: - In cases where the free space area corresponds to a polygon area, a Free Space Addendum Container may be added to the current CPM if the Euclidian relative distance between the vertices of the polygon relative to the corresponding vertices of this polygon lastly included in a CPM exceeds 4 m or if the number of vertices to describe the polygon changes.

In cases where the free space area corresponds to a circular area, or an elliptical area or a rectangular area, a Free Space Addendum Container may be added to the current CPM if the difference between the current Euclidian distance of the center point of the described free space area and the Euclidian distance of the center point of the same described free space area and lastly included in a CPM exceeds 4 m. Further, a Free Space Addendum Container may be added to the current CPM if the difference between the current radius or length of the described free space area and the Radius or length of the same described free space area lastly included in a CPM exceeds 4 m. Additionally, a Free Space Addendum Container may be added to the current CPM if the difference between the current orientation of the described free space area and the orientation of the same described free space area lastly included in a CPM exceeds 4 degrees.

Considering the invention, the space Container inclusion can comprise a set of conditions referred as Space inclusion conditions. This set of conditions can be derived from FreeSpace container inclusion conditions.

Additionally, a space container may be included in the next CPM to be transmitted if one the following condition is met: - The space container state is updated compared to the lastly reported CPM, or - A new sub-space is determined after the last CPM event generation, or the updated information of the space has first been detected after the last CPM event generation, or the Euclidian absolute distance between the lastly reported position and the current updated position of the reference point of the perceived space exceeds a predetermined threshold, minReferencePointPositionChangeThreshold (as defined for the PerceivedObject container), or the elapsed time since the last time the space was reported exceeds a predetermined threshold T_GenCpmMax (as defined for the PerceivedObject container).

The T_GenCpmMax value can be different depending on whether the Space container is reporting a space or a sub-space. It permits to get a different refresh rate between the global perception and the detailed perception. For example, the detailed reception can be reported using a predetermined threshold T_GenCpmMax1 value lower than predetermined threshold T_GenCpmMax1 value used to report for the global perception.

Figures 5 illustrates, using flowchart, general steps of a method according to embodiments of the invention at an originating ITS-S to generate a Space Addendum Container as described in Figure 4.

Situation Analysis Module 240 is configured to monitor periodically some spaces such as a road portion, a road intersection, a merging lane, a diverging lane, a parking as shown in Figure 1, Figure 8 or Figure 9 and is able to determine its geometry (DE SpaceArea) and its road attribute (DE SpaceType) stored in the road topology module 250. The DE SpacelD is determined for any monitored space.

DE SpaceArea and DE SpaceType can be retrieved from MAPEM or defined by a human as a configuration of situation analysis module 111.

Alternatively, the determined geometry of the space to monitor can be a sub-space of another space as described in Figure 6. In this case, the monitored sub-space is consider as a child of the space in which it's included. The including space of this sub-space is a parent of this sub-space. When a sub-space is reported in Space Addendum Container the DE SpaceParentID is equal to the DE SpacelD of parent space.

The originating ITS-S uses its sensors 220-223, 210 and its Sensor Data Fusion module 230 to update its Environment Model 260 with perceived objects.

Situation Analysis Module 240 continuously analyses the objects of the Environment Model 260. It retrieves at step 510 the list of perceived objects. In step 520, the situation analysis module 240 determines the occupancy of the monitored space using the positions of the perceived objects in step 510 and knowing the geometry of the monitored space in step 500. Also, the occupancy can be determined according to the space type. For example, the occupancy of pedestrian cross walk space can be busy only if some perceived objects retrieved are pedestrians and if their positions are part of the monitored space overlapping the cross walk and having a space type equals to a cross walk lane. In step 530, Situation Analysis Module 240 determines the space state (DE SpaceState) value based on the previously determined occupancy as described above. Optionally, the occupancy level (DE SpaceOccupancy) and confidence level (DE SpaceConfidence) are also determined as described in Figure 4.

Finally, the Space Addendum Container 401 is generated from the previously determined data elements: SpacelD, SpaceState, SpaceParentID, SpaceOccupancy, SpaceType, SpaceConfidence and SpaceArea.

Figures 6 illustrates, using a flowchart, main steps of the method at the originating ITS-S according to embodiments of the invention.

In step 600, the process starts periodically and by polling the various space to monitor in step 610 according to the invention.

In step 610, A space, being a parent space, is monitored.

In step 620, A first Space Addendum Container is generated from the monitoring of the previous parent space according to Figure 5 and the corresponding space state (DE SpaceState) is registered as a global space state (named GlobalState).

In step 630, the previously generated first Space Addendum Container is transmitted over a first Collective Perception Message. This transmission permits to deliver to other ITS-S a global perception of road situation as monitored using the previous parent space.

In step 640, the GlobalState value is compared to the default state value defined accordingly to the road type in Table 1.

If the GlobalState value is normal, the process returns in the first step 600.

Alternatively, if the GlobalState value is not the default state value ('0'), therefore abnormal, the process goes in step 650.

In step 650, the parent space is split in sub-spaces in order to obtain different space state values for the sub-spaces than the space state value of the parent state (GlobalState). For example, a space geometry is defined by a list of nodes forming a closed area. A node ('nodeXY') is composed of relative coordinates defined in map data stored in 250. two sub-spaces can be created by adding 2 nodes forming a segment cutting a space based on the determined occupancy in step 520. It results in closed list of nodes describing sub-spaces also named child space in the invention. The previous split is performed in order to get different occupancy levels for each sub-space between its.

In step 660, second(s) Space Addendum Container(s) are generated for each previous child space(s) according to Figure 5 and the corresponding space state(s) (DE SpaceState) are registered as a detailed space state(i) (named DetailedState(i)). (i) is used to numbered each sub-space.

In step 670, the previously generated second(s) Space Addendum Container(s) are transmitted over one or more second(s) Collective Perception Message(s) only if the respective DetailedState(i) are different than GlobalState. This transmission permits to deliver to other ITS-S a detailed perception of road situation as monitored using the previous sub-spaces. The delivered detailed perception is built in a manner to be complementary to the previously delivered global perception of road situation by transmitting only CPM with Space Addendum Container of sub-space having different SpaceState value than their parent space.

Finally, the process returns in step 600 to analyze the next parent space.

Optionally, in some embodiments, the process of splitting a space into a plurality of sub spaces may be reiterated to get more level of sub spaces. This may be advantageous in complex situations.

Figures 7 illustrates, using a flowchart, main steps of a method at the receiving ITS-S according to embodiments of the invention.

In step 700, the process starts to collect the received messages such as MAPEM, CPM. In step 710, the unit 110 retrieves the road topology from the storage unit 250 refreshed from the received MAPEM messages and CPM messages including Space Addendum Container by the unit 112.

In step 720, the unit 110 determines a global perception view of the road situation by analyzing only the CPM messages including Space Addendum Container of parent space(s). Such Space Addendum Container can be selected using the lack of the DE SpaceParentID.

In Figure 1, the CPM messages 130, 131 and 132 including respectively Space Addendum Containers of parent spaces 170, 171 and 172 are received by the vehicle 150. It permits to obtain a space perception of road segments 160,161 and 162 as reported by the forms 180, 181 and 182. The SpaceState of each parent space permit to globally perceive the road traffic jam. The SpaceState of space 170 and 172 have default value "normal", the corresponding form 180 and 182 are white colored. While the SpaceState of space 171 has value '1', abnormal, indicating that the space is not operating normally, the corresponding form 181 is grey colored.

Using the representation with the forms 180, 181 and 182, the global perception of the road situation is shown as it can be perceived by the driver of vehicle 150 using the invention. In step 730, the unit 110 determines a detailed perception view of the road situation by analyzing only the CPM messages including Space Addendum Container of child space(s). Such Space Addendum Container can be selected using the presence of the DE SpaceParentID.

In Figure 1, the CPM messages 131a and 131b including respectively Space Addendum Containers of child spaces 171a and 171b are received by the vehicle 150. It permits to obtain sub-space perception of road segment 161 as shown the forms 181a and 181 b. The SpaceState of each child space permit to perceive details of the road traffic jam. The SpaceState of space 171a and 171b have default value "normal", for example indicating an empty space or an occupied space operating normally, the corresponding form 181a and 181b are white colored while the SpaceState of space 171 has value '1', abnormal, indicating that the road part is not operating normally, the corresponding form 181 is grey colored. The forms 181, 181a and 181b are representing the detailed perception of the road situation as it can be seen for the driver of vehicle 150 using the invention.

Figure 8 illustrates another scenario for an implementation of embodiments of the present invention, where the originating ITS-S is a road side or a vehicle used to inform other vehicles in it vicinity on a merge lane road situation.

In this example, the originating ITS station, ITS-S, sending the CPM is a road-side unit, RSU. RSUs have advantageously more powerful resources to monitor a road segment situation than moving vehicles: for example, it may have a wider field of view, multiple fields of view, fast access to other information such as traffic conditions, traffic light status, knowledge of objects that populate the monitored area, etc. In particular, a better view of the monitored area allows an RSU to determine the space occupancy according to the road topology with a better confidence as it's static ITS-S station positioned at a relevant traffic observation point.

ITS 800 is implemented in order to monitor road trunks involved in a merging lane at an entrance of a motorway. It comprises a fixed road side unit 110, and several entities, such that all these entities may carry or comprise ITS station (ITS-S) each, for transmitting and/or receiving ITS messages within ITS 800. The several entities may be for example vehicles 822, 823, 824, and 825. The vehicles 822, 824 and 825 are moving on lanes 862, and 863 while the vehicle 823 is on the entrance lane 861. In this road situation, its difficult for the driver of vehicle 823 to perceive the global situation of the road trunks 860, 862 and 863. Similarly, the driver of vehicle 825 is not aware of the intention of the driver of vehicle 823 to enter in the motorway. Without the invention, the merge operation is at risk.

The vehicle 825 transmits periodically it parameters using CAM 840 and can contribute to the collection perception by transmitting CPM 834.

Fixed road side unit 110 includes a set of sensors, such as image sensors here illustrated by the video camera 120, an analytic module 111 to analyze data provided by the sensors, such as a Situation Analysis module. Video camera 120 is configured to monitor or scan a monitored area, here the road topology, and thus produces images of the monitored area.

The sensors and the analytic module 111, i.e. video camera 120 and Situation Analysis module, are connected so that the Situation Analysis module processes the stream captured by the sensors/video cameras. According to some embodiment, the analytic module 111 and the sensors may be separate from or embedded within the same physical road side unit 110. For example, the analytic module 111 may be wire-connected to the sensors that may be remote (i.e. not embedded in road side unit 110).

The processing by the analytic module 111, e.g. Situation Analysis module, aims at detecting objects potentially present in the monitored area, referred to as "perceived objects" or "detected objects" hereinafter. Mechanisms to detect such objects are well-known by one skilled in the art.

The analytic module 111, e.g. Situation Analysis module, is also configured to output a list of the perceived objects respectively associated with corresponding description information referred to as "state vector". The state vector for a perceived object may include for instance parameters such as position, kinematic, temporal, behavioural or object type classification information, etc. Therefore, the analytic module 111 may also identify, among the perceived objects, such as pedestrians, cyclists as well as. It may also identify objects such as trees, road construction/work equipment (road barrier, ...), and so on.

For example, in the illustrated example, by scanning the monitored area, the Situation Analysis module may perceive the following objects 822, 823, 824, and 825 corresponding to vehicles on the roadway.

The analytic module has some analysis function to analyze the monitored area of the perceived objects and is able to determine objects occupancy on various spaces. In Figure 1, road segments 860, 861,862 and 863 are monitored as spaces 810, 811, 812 and 813.

The geometry of spaces is equal to the area defined in the map data of the monitored road. The map data are locally stored in storage 250 and/or broadcasted using MAPEM messages. The analytic module 111 is able to determine a space state (SpaceState) for a monitored space.

The space state value is determined according to the road rule (named road type). The road type is available as map data either received by MAPEM 839 of locally stored in storage 250. In Figure 1, the road type is a merge lane.

For a merge lane, The value '0' indicates a state free meaning that the space is empty and this space is available for merge operation.

The value '1' or greater indicates a state busy meaning that the space is occupied by a vehicle and this space is not available for merge operation.

The analysis module 111 determines: state of the space 810 is normal because it's not occupied by a vehicle and this space is available for merge operation.

state of the space 811, 812 and 813 are abnormal because those spaces are occupied by a vehicle and not available for merge operation.

The analysis module 111 splits the space 811, 812 and 813 and obtains the sub-space 811a, 812a and 813a with state value normal indicating 'available for merge operation'..

Finally, the road side unit 110, transmits the collective perception messages resulting from the analysis module. The CPMs contain a space container with the following information: SpacelD, an identifier of the monitored space SpaceState, the value of the space state determined by the analysis module.

SpaceParentID, the parent space in case of sub-space.

SpaceOccupancy, number of objects detected by the analysis module.

- SpaceType, the road type as defined in the road topology information in storage 250. SpaceArea, the geometry of the space composed of a list of nodes and reference geographic reference point (for example e.g. WGS84 North) as defined in the standard IS019061.

The CPM 830 reports on the space 810 with the following information set: SpacelD=810 SpaceState=free SpaceOccupancy=0.

SpaceType='merge lane'.

- SpaceArea= road topography of the lane 860.

The CPM 831 reports on the space 811 with the following information set: SpacelD=811 SpaceState=busy -SpaceOccupancy=1 SpaceType= merge lane'.

SpaceArea = road topography of the lane 861.

The CPM 832 reports on the space 812 with the following information set: SpacelD=812 -SpaceState=busy SpaceOccupancy=1. SpaceType='merge lane'.

- SpaceArea = road topography of the lane 862.

The CPM 833 reports on the space 813 with the following information set: SpacelD=813 SpaceState=busy SpaceOccupancy=2.

SpaceType='merge lane'.

SpaceArea = road topography of the lane 863.

Additionally, the analysis module determines three sub-spaces 811a, 812a and 813a having different state values and geometry.

Consequently, The CPM 831a reports on the sub-space with the following information set: - SpacelD=8112 SpaceState=free SpaceParentID=811 SpaceOccupancy=0 SpaceType='merge lane'.

SpaceArea= space geometry of spaces 811a.

The CPM 832a reports on the sub-space 812a with the following information set: - SpacelD=8122 SpaceState=free - SpaceParentID=812 -SpaceOccupancy=0 - SpaceType='merge lane'.

-SpaceArea= space geometry of spaces 812a.

The CPM 833a reports on the sub-space 813a with the following information set: SpacelD=813a SpaceState=free - SpaceParentID=813 SpaceOccupancy=0 SpaceType='merge lane'.

SpaceArea= space geometry of spaces 813a.

The vehicle 825 with ITS-S on board is also reporting using CPM 834 the state of the road lane 863 using it own sensors.

The CPM 139 reports on the space 864 with the following information set: SpacelD=864 SpaceState=busy -SpaceOccupancy=1 SpaceType=lane'.

SpaceArea= space geometry of spaces in front of vehicle 825.

The driver of vehicles 825 and 823 with ITS-S on board are able to determine globally and quickly the traffic situation in the upcoming seconds by receiving the messages MAPEM 810, CPM 830, CPM 831, CPM 832 and CPM 833. Based on those messages, the drivers of vehicles 825 and 823 are able to easily get a global perception of the road situation as illustrated by the forms 880, 881, 882 and 883 representing the traffic conditions of the upcoming lanes on the vehicle road trip considering a merge road type. Particularly, based on forms 881 and 882, the driver of vehicle 823 understands that some vehicles are present on lanes 862 and 863 limiting merge operation. The driver understands a traffic issue on lane 862 without details. It permits to get a first level of details corresponding to a global perception of the situation.

By receiving the messages CPM 832a and CPM 833a, understands in details the traffic jam situation. It permits to get a second level of details corresponding to a detailed perception of the situation. Particularly, based on forms 881a and 882a, the driver of vehicle 823 can anticipate the merge operation on road trunk 862. Similarly, the driver of vehicle 823 can anticipate the merge operation on road trunk 862 by using the CPM message 834 transmitted by the vehicle 825. By using only, the form 884, the driver of vehicle 823 can be aware of an incoming vehicle resulting as an occupancy on the merge lane. This information may be obtained, in some cases, without road side unit 110 and by using only vehicle-to-vehicle communication. CPM messages having Space Addendum Container 830, 831, 832, 833 are also named G-PCM meaning Global Collective Perception Message according to Figure 6. CPM messages having Space Addendum Container 830a, 831a and 832a are also named D-PCM meaning Detailed Collective Perception Message according to Figure 6.

Figure 9 illustrates another scenario for an implementation of an embodiment of the present invention, where the originating ITS-S is a road side unit vehicle monitoring a parking area to report globally and in detail the position of free places.

The vehicle 940 is looking for a free place in parking area where C-ITS is operating and configured to monitor the parking places using the invention. Using the invention, the unit 110 is able to deliver the parking map data using MAPEM 910 delivering the global geometry of the parking area. The unit 110 globally reports on the state of blocks of free or occupied places using CPM having Space Addendum Container 930, 931, 932, 933 and 934 by providing SpaceState of space 980, 981, 982, 983 and 984 used to report on block of busy places 950, 951, 953, 954, 955, 956, 957, 958, 959 and 960, reported globally according to embodiments of the invention.

Also, the unit 110 specifically reports on places using CPM having Space Addendum Container 930a, 931a and 932a by providing SpaceState of sub-space 980a, 981a and 982a used to report on block of free places 951, 954 and 958 according to embodiments of the invention. Additionally, the unit 110 can report on specific place like reserved place for vehicle for disabled person 956, considered as space 984, by using a SpaceType 'reserved for disabled person'. Using this SpaceType, the vehicle 940 is informed on this specificity. CPM messages having Space Addendum Container 930, 931, 932, 933 and 934 are also named G-PCM meaning Global Collective Perception Message according to Figure 6. CPM messages having Space Addendum Container 930a, 931a and 932a are also named D-PCM meaning Detailed Collective Perception Message according to Figure 6.

Finally, the vehicle 940 gets a global and detailed perception of the available places in the parking area so he can drive stress less and decides where to go inside the various blocks to park his vehicle.

The invention also permits to assist driver of vehicle for disabled people by reporting specifically on reserved place and informing other driver that some places are reserved for this purpose.

Figure 10 shows a schematic representation an example of a communication ITS-S device configured to implement embodiments of the present invention. It may be either an ITS-S embedded in a vehicle or in a road side unit 120.

The communication device 1000 may preferably be a device such as a micro-computer, a workstation or a light portable device embedded in the vehicle or RSU. The communication device 900 comprises a communication bus 1013 to which there are preferably connected: * a central processing unit 1011, such as a microprocessor, denoted CPU or a GPU (for graphical processing unit); * a read only memory 1007, denoted ROM, for storing computer programs for implementing the invention; * a random access memory 1012, denoted RAM, for storing the executable code of methods according to embodiments of the invention as well as the registers adapted to record variables and parameters necessary for implementing methods according to embodiments of the invention; and * at least one communication interface 1002 connected to the radio V2X communication network over which ITS messages are transmitted. The ITS messages are written from a FIFO sending memory in RAM 1012 to the network interface for transmission or are read from the network interface for reception and writing into a FIFO receiving memory in RAM 1012 under the control of a software application running in the CPU 1011.

Optionally, the communication device 1000 may also include the following components: * a data storage means 1004 such as a hard disk, for storing computer programs for implementing methods according to one or more embodiments of the invention; * a disk drive 1005 for a disk 1006, the disk drive being adapted to read data from the disk 906 or to write data onto said disk; * a screen 1009 for serving as a graphical interface with the user, by means of a keyboard 910 or any other pointing means.

The communication device 1000 may be optionally connected to various peripherals including perception sensors 1008, such as for example a digital camera, each being connected to an input/output card (not shown) so as to supply data to the communication device 1000.

Preferably the communication bus provides communication and interoperability between the various elements included in the communication device 1000 or connected to it. The representation of the bus is not limiting and in particular the central processing unit is operable to communicate instructions to any element of the communication device 1000 directly or by means of another element of the communication device 1000.

The disk 1006 may optionally be replaced by any information medium such as for example a compact disk (CD-ROM), rewritable or not, a ZIP disk, a USB key or a memory card and, in general terms, by an information storage means that can be read by a microcomputer or by a microprocessor, integrated or not into the apparatus, possibly removable and adapted to store one or more programs whose execution enables a method according to the invention to be implemented.

The executable code may optionally be stored either in read-only memory 1007, on the hard disk 1004 or on a removable digital medium such as for example a disk 1006 as described previously. According to an optional variant, the executable code of the programs can be received by means of the communication network, via the interface 1002, in order to be stored in one of the storage means of the communication device 1000, such as the hard disk 1004, before being executed.

The central processing unit 1011 is preferably adapted to control and direct the execution of the instructions or portions of software code of the program or programs according to the invention, which instructions are stored in one of the aforementioned storage means. On powering up, the program or programs that are stored in a non-volatile memory, for example on the hard disk 1004 or in the read only memory 1007, are transferred into the random access memory 1012, which then contains the executable code of the program or programs, as well as registers for storing the variables and parameters necessary for implementing the invention.

In a preferred embodiment, the apparatus is a programmable apparatus which uses software to implement the invention. However, alternatively, the present invention may be implemented in hardware (for example, in the form of an Application Specific Integrated Circuit or ASIC).

Although the present invention has been described hereinabove with reference to specific embodiments, the present invention is not limited to the specific embodiments, and modifications will be apparent to a skilled person in the art which lie within the scope of the present invention.

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular, the different features from different embodiments may be interchanged, where appropriate.

Each of the embodiments of the invention described above can be implemented solely or as a combination of a plurality of the embodiments. Also, features from different embodiments can be combined where necessary or where the combination of elements or features from individual embodiments in a single embodiment is beneficial.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used.

Claims

CLAIMS1. A method of communication in an Intelligent Transport System, ITS, comprising, at an originating ITS station: reporting in a collective perception message an element describing a space and comprising a field indicating the space state.
2. The method of claim 1, wherein the space described by the element represents a specific area of a road topology.
3. The method of claim 2, wherein the element is a space container.
4. The method of claim 2, wherein the element comprises a rule of road space corresponding to a type of the specific area.
5. The method of claim 4, wherein the field indicating the space state depends on the rule of road space.
6. The method of claim 1, wherein the element comprises a field indicating the occupancy of the space as a number of detected objects in the space.
7. The method of claim 1, wherein the element comprises a field indicating a level of confidence on information provided by the element.
8. The method of claim 1, wherein the element comprises an identifier of another space indicating that the space is a sub part of the other space.
9. The method of claim 1, wherein the element comprises a geographical area definition of the space.
10. The method of claim 1, wherein the element comprises the fields of a free space container for describing a space not containing any perceived object
11. The method of claim 11, wherein the element is a container which can represent a space or a free space.
12. A method of generation of a collective perception message in an Intelligent Transport System, ITS, comprising, at an originating ITS station: -determining a space determining a state of the space; - generating a space container describing the space and comprising a field indicating the space state; and -embedding the space container in the collective perception message.
13. The method of claim 12, wherein the method further comprises: -determining a specific area of the road topology; and wherein -the determined space represents the specific area of the road topology.
14 The method of claim 13, wherein the method further comprises: determining another space representing a sub part of the specific area; generating a space container describing the other space comprising an identifier of the space; - embedding the space container describing the other space in a collective perception message.
A method of reception of a collective perception message in an Intelligent Transport System, ITS, comprising, at a receiving ITS station: - receiving the collective perception message; obtaining an element describing a space and comprising a field indicating the space state; determining a global perception of the road situation from information comprised in the element.
16. The method of claim 15, wherein the space represents a specific area of a road topology.
17 The method of claim 16, wherein the method further comprises: obtaining another element describing another space representing a sub part of the specific area; determining a detailed perception of the road situation from information comprised in the other element.
18. A collective perception message in an Intelligent Transport System comprising an element describing a space representing a specific area of the road topology.
19. A device of communication in an Intelligent Transport System, ITS, comprising a processor configured for: reporting in a collective perception message an element describing a space and comprising a field indicating the space state.
A device of generation of collective perception message in an Intelligent Transport System comprising a processor configured for: determining a space determining a state of the space; generating a space container describing the space and comprising a field indicating the space state; and embedding the space container in the collective perception message.
21 A device of reception of collective perception message in an Intelligent Transport System comprising a processor configured for: -receiving the collective perception message; obtaining an element describing a space and comprising a field indicating the space state; determining a global perception of the road situation from information comprised in the element.
22. A computer program product for a programmable apparatus, the computer program product comprising a sequence of instructions for implementing a method according to any one of claims 1 to 17, when loaded into and executed by the programmable apparatus.
23. A computer-readable storage medium storing instructions of a computer program for implementing a method according to any one of claims 1 to 17.
24. A computer program which upon execution causes the method of any one of claims 1 to 17 to be performed.