Patent Application
20140126557
Radio transmission/radio reception device and method for communication within a, in particular wireless, motor vehicle communication system interacting in ad-hoc fashion
The invention relates to a radio transmission/radio reception device for communication within a, in particular wireless, motor vehicle communication system interacting in ad-hoc fashion, as claimed in the preamble of claim 1 and to a method for communication within a, in particular wireless, motor vehicle communication system interacting in ad-hoc fashion, as claimed in the preamble of claim 26.
It is known that radio transmission/radio reception devices for communication within a motor vehicle communication system interacting in ad-hoc fashion, for example wireless, are being used for communication between road users with one another. Interacting in ad-hoc fashion means so-called ad-hoc networks, that is to say essentially self-organizing networks formed or operated spontaneously by direct communication of the network nodes involved. In the road traffic, this communication, as a rule, comprises motor vehicles which is why it is also called “car to car” (C2C) communication. However, this communication also comprises communication to the traffic infrastructure which is formed, for example, by base stations formed by so-called “roadside units” such as, for example, traffic lights, for conveying the communication or propagating information to the information networks connected to the traffic light or controlling traffic centers. This communication is called “car to infrastructure” (C2I). Since, in principle, motor vehicles do not represent the only road users but bicycles or bicycle riders and pedestrians are also involved, this communication also comprises the exchange of data between radio transmission/radio reception devices operated by them and the radio transmission/radio reception devices operated by motor vehicles. There is no term or acronym derived from English for these but they are included in the term of “car to X” technology or communication (C2X) known for the generalization of this type of communication.
In this context, this type of communication must be distinguished from the known mobile radio communication since the former, as a rule, takes place in automated fashion, that is to say predominantly without triggering or required actions by the user and serves the purpose of collecting and exchanging traffic-related data so that it is ideally possible to respond appropriately to all possible traffic situations, for example by warnings to the user or automated responses by the motor vehicle.
For the collection of data and especially the exchange thereof, it is known that each motor vehicle sends out a cyclic message at an interval of a few seconds which contains a vehicle ID and information on speed, direction and position. The sending out of these standard cyclic messages, also called “beacons”, additionally to other messages, especially on much-traveled traffic routes, can lead to overload situations, in the extreme case to blocking of pending data since the resources provided for the wireless motor vehicle communication are limited. If other road users such as pedestrians and bicycles are also added to this, the situation is additionally aggravated.
The invention is, therefore, based on the object of improving the characteristics of a motor vehicle communication system interacting in ad-hoc fashion.
On the basis of the radio transmission/radio reception device as claimed in the preamble of claim 1, this object is achieved by its characterizing features and, on the basis of the method as claimed in the preamble of claim 26, by its characterizing features.
The radio transmission/radio reception device according to the invention for communication within a, in particular wireless, motor vehicle communication system interacting in ad-hoc fashion is designed in such a manner that it emits an information item about the range of messages provided, at least one further radio transmission/radio reception device receives the information and on the basis of the received information a frequency of the emission of successive messages over time is specified by the further radio transmission/radio reception device.
This ensures that the loading of communication channels is always adapted to the local and current conditions and thus, in particular, safety-related messages can be sent out with less delay and largely unblocked. In this context, the frequency of the emission has a direct effect on the loading so that very rapid resource relief is guaranteed.
The radio transmission/radio reception device according to the invention is preferably designed then in such a manner that it is designed for the communication between road users among one another and/or between road users and traffic infrastructure.
This ensures that, in principle, all those involved in the traffic, in particular, can make a contribution to enhancing the traffic safety since the radio transmission/radio reception device according to the invention, according to this development, is suitable for providing both communication to road user vehicles, for example in cars and motorcycles or other vehicles, and also implemented in terminals such as cell phones or PDAs which provide for traffic-related communication with pedestrians and cyclists and their devices, respectively. The contribution is also produced due to the fact that a communication to the traffic infrastructure—that is to say notably stationary traffic devices such as traffic lights and the like, equipped with radio transmission/radio reception devices—can take place so that this device can produce a response adapted to traffic situations via a link with traffic centers. Both types of communication combined provide for the greatest penetration or most accurate statements on the traffic situation in this context.
The invention can also be developed to the extent that the radio transmission/radio reception device is designed for data transmission according to a dedicated short-range radio communication standard, particularly the so-called Dedicated Short Range Communication, “DSRC”. Such short-range radio standards are particularly suitable for communication between vehicles and other mobile road users and, due to the standardization, ensure that the interaction works, too. In particular, this works very well integrated with the WLAN Standard 802.11 and its derivative such as 802.11a/b/e/g/n/p.
If the radio transmission/radio reception device according to the invention is to be operated in Europe, it is advantageous if it is designed for data transmission according to the so-called Wireless Access in Vehicular Environments, “WAVE”, standard or derivatives thereof.
A defined radio interface of the radio transmission/radio reception device is then obtained if the radio transmission/radio reception device is designed for data transmission at least partially according to IEEE 1609.4 and/or ETSI Intelligent Transportation Systems, “ITS” standards or its derivatives.
In this context, wide distribution and penetration is brought by the development in which the radio transmission/radio reception device is designed for a data transmission at least partially according to IEEE802.11 standards or its derivatives, particularly IEEE 802.11p since, in the meantime, every portable entertainment device such as cell phone, PDA, has such a WLAN interface so that these devices can be utilized without great modifications for traffic-related communication among road users. The development utilizing the IEEE 802.11p derivative is very reliable here in the case of rapidly moving objects such as motorized vehicles.
This reliability of IEEE 802.11p also renders the development advantageous in which the radio transmission/radio reception device is designed for a higher-priority first, particularly safety-related, data transmission according to IEEE 802.11p. Utilization according to IEEE 802.11e also has this advantage. Not lastly also due to the prioritization which can be carried out accordingly.
As an alternative or additionally, it is of advantage when the radio transmission/radio reception device is developed in such a manner that it is designed for a second lower-priority, particularly subscriber-individual, data transmission according to IEEE 802.11 a/b/g. In particular in the case of the division into subscriber-individual data such as, for example, information retrievals on the Internet and safety-related information, this development can increase the possibilities and frequencies of transmission for the safety-related data transmissions.
For safety-relevance and traffic control, the development is of advantage in which the radio transmission/radio reception device is designed in such a manner that the messages comprise status messages about the status of a road user.
As an alternative or additionally, the radio transmission/radio reception device can here utilize, for the emission of messages, a control channel particularly the so-called control channel “CCH” or a service channel, particularly the so-called service channel “SCH”. As a rule, these channels are treated preferentially in the data transmission, for example in that radio resources are reserved and kept available for them exclusively. This also increases the performance particularly in the case of high-priority data which can relate to or increase the traffic safety.
The radio transmission/radio reception device is preferably developed in such a manner that the information about the range of messages provided is based on messages prepared for dispatch by the radio transmission/radio reception device by the radio transmission/radio reception device, present in a data memory allocated to the radio transmission/radio reception device. By this means, the information about the range is directly correlated with the loading of the channels to be expected so that this provides for a relatively precise prediction of the coming loading.
If the radio transmission/radio reception device is developed in such a manner that the range is designed as a first value belonging to the integer set of numbers, reproducing the number of the messages to be dispatched, especially designated as “channelLoadtoNeighbors”, this provides a value which is easily to be determined, simple to be coded, for controlling the following steps.
Preferably, or in addition thereto, the radio transmission/radio reception device is developed in such a manner that the first value is conveyed at least with a part of messages to be transmitted, preferably every message. This provides for good updating of the state of loading of the system. Furthermore, additional header data are avoided which would be necessary if the information were to be sent out separately from other messages. Thus, the inventive concept of reducing data load is additionally supported. Furthermore, it is provided for, especially in the case of suitably selected dimensioning of the coding of the value, that any unused bit data fields of the header part of the messages can be utilized for coding so that the transmission of the value thus means no additional load at all.
A possibility simply to be implemented and simply to be decoded is offered when the radio transmission/radio reception device is designed in such a manner that the first value is conveyed within a message field of the data transmission of the message.
In supplement thereto, the radio transmission/radio reception device can be designed in such a manner that the message field is designed as a field having a fixed bit width. A defined width facilitates decoding, the width of 4 bits, in particular, being appropriate for most of the message sets to be expected.
If the radio transmission/radio reception device is designed in such a manner that, as a further radio transmission/radio reception device, forms on the basis of first values received by, especially all, adjacent radio transmission/radio reception devices, a second value belonging to the integer set of numbers, designated especially as “channelLoadfromNeighbors” its further behavior with regard to the messages to be transmitted can be based on a very precise image of the future position. Although the individual neighbors can change, especially due to the mobility, but in the aggregate, the number of stations frequently remains almost identical up to changing little, so that the previously communicated number of messages to be transmitted, even if the stations subsequently may no longer be neighbors, still provide a good estimate of the coming state of loading.
The radio transmission/radio reception device is preferably developed in such a manner that when a first threshold value, designated especially as “channelLoadfromNeighbors_active”, is exceeded by the second value, the frequency of the emission of successive messages over time is specified at a third value. Comparisons of threshold value are easily to be implemented method steps for controlling systems. Furthermore, their values can be optimized, for example, by simulations and also adapted at a later time.
If the radio transmission/radio reception device is developed in such a manner that when a second value, designated especially as “channelLoadfromNeighbors_restrictive”, is exceeded by the second value, the frequency of the emission of successive messages over time is specified at a fourth value, a further step of escalation or finer grading of the reaction of the system to the state of loading can be produced in a simple manner.
Preferably, the radio transmission/radio reception device is developed in such a manner that when the second threshold value is undercut by the second value, the frequency of the emission of successive messages over time is specified at the third value. This development can provided for a graded release of resource for the sending out of low-priority data.
Additionally, the radio transmission/radio reception device can be designed in such a manner that when the first threshold value is undercut by the second value, the frequency of the emission of successive messages over time is specified at a fifth value. This achieves a further de-escalation or release stage which provides for finer adaptation to the conditions.
If the radio transmission/radio reception device is developed in such a manner that the first and/or second threshold value are specified in such a manner that the difference of their values is greater than zero, especially five, a hysteresis can be implemented so that rapid interfering oscillation of the system between a number of threshold values is avoided. This value, too, can be optimized by simulations and preferably changed subsequently.
The radio transmission/radio reception device according to the invention is preferably developed in such a manner that the third, fourth and/or fifth value are formed according to defined system states of a decentralized load control designated as “Decentralized Congestion Control” prescribed especially according to the ETSI TS 102 687 standard. As a result, predefined states are utilized which makes an implementation less complex and also additionally provides for the utilization of other characteristics defined by the system such as, for example, the signaling of states and/or the corresponding treatment of (over-) load states of the system.
Further penetration is achieved if the radio transmission/radio reception device is developed in such a manner that it is designed for communication with road users at least partially according to the European standard ETSI TC ITS, the American so-called “Vehicle Safety Communications Program, VSC” or the Japanese “Advanced Vehicle Safety Program, AVS”. By this means, the device according to the invention becomes usable in various parts of the world.
It is also conceivable that the radio transmission/radio reception device or the associated method, respectively, performs the communication with road users at least partially according to a mobile radio standard such as GSM, UMTS or derivatives thereof. This is advantageous, in particular, for better penetration and acquisition since pedestrians and cyclists which are in possession of a mobile radio device (mobile phone), can also be integrated into the communication as road users as already indicated and thus a comprehensive overall picture of the traffic can be formed.
This is advantageously supplemented or, respectively, the alternative also becomes available to develop the radio transmission/radio reception device in such a manner that it is designed for communication with road users at least partially according to the ISO standard “continuous-air long and medium range”, CALM. The device can thus be utilized not only worldwide but also without changes or national adaptations which is appropriate for the concept of mobility of vehicles.
The invention also relates to a method for communication within a, in particular wireless, motor vehicle communication system interacting in ad-hoc fashion, in which
This method allows—implemented in the devices—an increase in the exploitation of the advantages of controlling, according to the invention, the loading in favor of traffic safety.
Developments of the method offer “mutatis mutandis” the same advantages as the corresponding developments of the arrangement, in each case with the additional advantage that they contribute to the implementation of the advantage of the subject matter.
The invention will be explained in greater detail, by way of example, using two figures, in which
The representation according to
As an alternative or additionally, it is possible to use IEEE 802.11e, IEEE 802.11 a/b/g/n or IEEE 1609.4, single ones or several of them in mixed operation.
In this context, the frequency band used is established, for example, in the 5 Ghz band.
Apart from the WLAN standards mentioned, a GSM infrastructure, comparable to one implemented, for example, also in so-called eCall systems, can be utilized for the ad-hot communication of the vehicle/infrastructure (C2X), particularly in the case of the involvement of persons.
The radio transmission/radio reception devices according to the invention are in this context integrated in the terminals of the persons or in the vehicles and the infrastructure. Thus ideally distributed area-wide in the case of the road users and the traffic infrastructure so that, in the text which follows, (road) user and (traffic) infrastructure will also be used as a simplifying designation for radio transmission/radio reception device (es).
If no portable terminals equipped with the radio transmission/radio reception device according to the invention are used in the vehicle by persons in the vehicle for motor vehicle communication, who communicate wirelessly with functional groups of the motor vehicle, the radio transmission/radio reception device according to the invention can be integrated for example, in the vehicle via a bus system in such a manner that it communicates with the other functional groups of the vehicle. This can be CAN BUS. Apart from CAN, however, the use of other bus systems such as LIN, MOST, Byteflight or the like is also conceivable.
In this context, each subscriber sends at periodically repetitive intervals of typically about 100 msec via the control channel (CCH) or service channel (SCH), provided in accordance with this standard, among other things, information about position, speed and the direction of travel.
According to the invention, each road user 10, 20, 30, 40, 50 then emits additionally information about the range of messages 12, 22, 32, 42, 52 provided. This information is based on the messages prepared for dispatch, present in a data memory 11, 21, 31, 41, 51 of the subscriber 10, 20, 30, 40, 50.
According to a simple solution, only the number of the messages present in the respective data memory 11, 21, 31, 41, 51 is sent, but it is also conceivable to send the information about the entire data volume and thus to obtain a more accurate information item about the data sets to be expected.
It is also conceivable that the number of pending messages is determined by an algorithm which takes into consideration, for example, the history, especially of the number of messages sent out at an earlier time and predicts from this a future number of possible messages. This would have the advantage, among other things, to be able to act more rapidly.
On the basis of the information, obtained from the other subscribers in each case, about the overall range 12, 22, 32, 42, 52 of the messages provided, each subscriber 10, 20, 30, 40, 50 then determines a prognosis about the loading of the mobile ad-hoc network in a predetermined period of time.
When this predicted loading then exceeds certain values, the subscribers 10, 20, 30, 40, 50 reduce the frequency of their messages or increase the time intervals between the individual messages and thus reduce the network loading so that the invention provides an effective load control.
Both are based in this context on the decentralized load control defined according to this standard, the so-called “Decentralized Congestion Control” DCC.
A first state RELAX, a second state ACTIVE and a third state RESTRICTIVE are defined there.
In the first state RELAX, the resource allocation moves within a normal framework and, therefore, scarcely requires regulation.
In the second state ACTIVE, the resource allocation can already meet limits and there arises the risk that further, especially highly (safety) related data cannot be dispatched. In this state, first measures for regulation may already be required.
In the third state RESTRICTIVE, an overload situation is already apparent which requires stronger measures.
This classification according to the invention, utilizing the known states, is performed by the conveyance, according to the invention, of planned or pending messages in the form of the pure number or even the range of the messages.
In the example shown, this is intended to be only the number of pending messages which, for example beginning in the first state RELAX of a subroutine, leads to the update of an indicator value “channelLoadfromNeighbors”. In this context, the number can be contained by a few bits, for example 4 bits, coded in all messages dispatched by adjacent stations.
This is then followed, by accumulation, that is to say for example forming the sum over all received information about the number of pending messages “channelLoadtoNeighbors”, by a determination of messages to be expected in the immediate next time. The time used as a basis can here be set as a variable “immediate next time” having values, for example, in the millisecond range.
If the update of the value of the messages to be expected “channelLoadfromNeighbors” was triggered in the first state RELAX, a first threshold value comparison takes place in which the current value of the messages to be expected “channelLoadfromNeighbors” is compared with a first threshold value “channelLoadfromNeighbors_active” representing a first escalation stage.
If the result of the comparison is that the value of the messages to be expected “channelLoadfromNeighbors” is greater than the first threshold value “channelLoadfromNeighbors_active”, it is checked in a next threshold value comparison whether the value of the messages to be expected “channelLoadfromNeighbors_active” is greater than a second value, representing a second escalation stage, “channelLoadfromNeighbors_restrictive”. If this is not the case, the underlying logic shows that the loading of the resources is in a state between the second state ACTIVE and the third state RESTRICTIVE. In this state, the system, according to DCC, is placed into the state ACTIVE or, respectively, the state is signaled to the system and corresponding measures, especially load controlling measures according to the invention, are initiated.
If, however, the case occurs that the value is thus greater, the system is in a state of overload, that is to say the third state RESTRICTIVE with the corresponding measures, identifying this system state, for regulating the load.
As the representation shows, in both states there is also an update of the value of the messages “channelLoadfromNeighbors_active” to be expected with subsequent threshold value comparisons with the first threshold value “channelLoadfromNeighbors_active” and, optionally, with the second threshold value “channelLoadfromNeighbors_restrictive”. This is because the second check is only required if the first check does not immediately indicate a change in state. However, the checks are made with a different logic.
This means that, based on the second state ACTIVE, the first threshold value comparison is checked as to whether the value of the messages “channelLoadfromNeighbors” to be expected is smaller than the first threshold value “channelLoadfromNeighbors_active”. If this is the case, it means that the loading has become normalized, that is to say relaxed, and the system thus again assumes the first state RELAX. If this is not the case, the second threshold value check is carried out in which it is determined whether the value of the messages “channelLoadfromNeighbors” to be expected is greater than the second threshold value “channelLoadfromNeighbors_restrictive”. This is because if the value has not become smaller, the possibility exists that it has become greater. If it is greater, the system changes to the third state RESTRICTIVE. If it is not, it means that the loading is still in the second state ACTIVE.
In contrast, it is checked, on the basis of the third state RESTRICTIVE in the first threshold value comparison whether the value of the messages “channelLoadfromNeighbors” to be expected has become smaller than the second threshold value “channelLoadfromNeighbors_restrictive”. If this is not the case, the system remains in the third state RESTRICTIVE. If, however, it is the case, it is checked in the next step whether the value of the messages “channelLoadfromNeighbors” to be expected has even dropped to such an extent that it is smaller than the first threshold value “channelLoadfromNeighbors_active”. If this is the case, it means that the loading of the system is relaxed. Correspondingly, the first state RELAX is indicated to the system or this state is assumed, respectively, and measures for regulating the loading are also adapted, i.e., for example, taken back completely.
If, however, the value of the messages “channelLoadfromNeighbors” to be expected is not also smaller than the first threshold value “channelLoadfromNeighbors_active”, then the loading of the system has only become reduced to the second state ACTIVE and the measures for regulating the loading are then performed in accordance with this state.
By means of this method, the system is now capable of accounting for the development of the loading of the system in both directions—that is to say increase in the loading and decrease in the loading. However, in order for the system not to be continuously jumping between the states, the two threshold values “channelLoadfromNeighbors_restrictive” and “channelLoadfromNeighbors_active” are selected in such a manner or, respectively, the threshold value comparison is implemented in such a manner that therefore an undesired oscillation between the states will not thus occur.
For this purpose, this can be achieved by setting a system variable such as “channelLoadfromNeighbors_hysteresis” having a suitable value, for example 5. I.e., in the threshold value comparison, a change of state is initiated only when the value of the messages “channelLoadfromNeighbors” to be expected is exceeded by the corresponding threshold value plus 5 or undercut by the corresponding threshold value minus 5.
The invention is not restricted to the examples shown but here comprises all embodiments which contain the concept according to the invention, defined by the claims, and achieve an equivalent effect.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10201107788.2 | Jun 2011 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/068750 | 10/26/2011 | WO | 00 | 12/21/2013 |
