Method and apparatus for selecting remote stations according to their priorities.

IS 2 173 113 T3

DESCRIPTION

Procedure and apparatus for the selection of remote stations according to their priorities.

Field of the invention

This invention deals generally with a procedure and a system for the iterative assignment of respective discrete priorities to a set of participants according to one or more selection criteria and for locating those participants, if any, that have the highest priority. during each iteration. Background of the invention

It is a common requirement to locate and identify as quickly as possible one or more participants from a set of participants according to specific selection criteria.

For example, an alert system may be required to alert everyone within a specified geographic area to the start of a fire or other hazard. In this case, of course, it is not necessary to identify each person but simply to locate all the people. On the other hand, it is often necessary to select one or more participants according to their priority based on specified selection criteria to assign a particular work to the participant or participants who have the highest priority.

In shipping systems, or for example, to send a taxi or a courier to a customer at a specified location, it is desirable that a suitable (and preferably the most suitable) taxi or courier be sent to a particular customer. Generally, the closest unoccupied taxi with sufficient capacity should be sent to the customer. On the other hand, it is desirable that the assignment be carried out in the same amount of time as possible.

Typical existing dispatch systems include a central dispatch station having a transmitter and receiver and a transceiver in each of the participating vehicles for communication with the central dispatch station. Typically, a voice request is transmitted by an employee responsible for shipping to each of the participating vehicles, and the employee responsible for shipping decides which of the vehicles is the most appropriate for the job at hand based on the responses from the participants. vehicles.

Such a system would be capable of simple implementation if the related selection criteria are only static variables. Thus, if the only selection criteria were the current distance of the taxi from the customer and if each taxi was stopped, it would simply be necessary to extract the location of the taxi once, after which it would be easy to determine which taxi is closest to the customer's location. However, in practice, the selection criteria are related to dynamical variables that, by definition, are constantly changing and, therefore, it is necessary to continuously update the distance of each taxi with respect to the customer's location (and / or other information required to choose a taxi for a given job) or at least do this every time a taxi is to be dispatched.

In typical systems of the prior art, this is done by providing the dispatcher with a continuously updated map showing the respective location of each of the taxis. This update is carried out by means of the periodic transmission of a location message by each of the taxis through a communication channel. To ensure that the transmitted data can be received quickly and without corruption, the total spectrum width of the communication system must be very large.

It should also be noted that, even in the specific case of a taxi or courier service, the distance from the customer's location is by no means the sole criterion according to which a job can be assigned. In this way, it may well be that the closest taxi or courier is already busy and, therefore, is not available to carry out the order. Alternatively, the closest available taxi may not have sufficient capacity to carry all the passengers to whom a taxi must be dispatched; Or perhaps a particularly bulky load has to be transported and the nearest available taxi or courier is not suitable for the job.

A further consideration is that it is often preferable to send a customer an unoccupied taxi that is waiting at the taxi rank rather than going through the entire process of transmitting a voice message and waiting for responses from the taxis that are found. in the area before assigning the order to one of them. In the event that several unoccupied taxis are waiting at the taxi rank, or when several taxis are reasonably close to the customer, it is often preferable to select the taxi that has been unoccupied for the longest period of time.

On the other hand, it may not always be desirable to send the closest available taxi to a particular customer location if other customers, even if they are far away, have made previous requests that have not yet been met.

Even leaving aside some of the basic limitations of the prior art systems described above, it is often desirable to locate and possibly identify participants according to various selection criteria. This is somewhat analogous to conducting a database search for keywords that can be combined according to the rules of the Boolean or other logical systems. However, the database records are generally static and are stored in a single location. In contrast to this, the participants object of the invention change dynamically and constantly, and cannot be characterized by means of aesthetic data that can be stored in a single place. Thus, if the dynamic data characterizing these participants is to be searched for in a single site, then the data must be downloaded first.

ES 2 173 113 T3 place to the site where the search is to be carried out. During the time that this data is downloaded, it can change perfectly, thus compromising the accuracy of the search that is going to be carried out later.

WO-A-8 903 106 describes a vehicle location system in which a vehicle responds to a central request by sending its address. The time it takes for a vehicle to transmit a response can vary according to a characteristic value, such as distance from the vehicle.

Summary of the invention

The invention relates to a method according to claim 1 and to an apparatus according to claim 24.

It is an object of some aspects of the invention to provide a procedure and a system for the determination of priorities of a set of participants according to one or my selection criteria and the location of those participants, if any, that have the highest priority.

It is a further object of some aspects of the invention to provide such a procedure and system that those participants having the highest priority can be located in a short period of time.

A still further object of some aspects of the invention is to provide such a method and system that at least one of the located participants can be identified so that a job can be assigned to it.

As used herein the term "priority", in addition to its normal meaning, has the meaning of a characterization according to a protocol that takes into account one or more characteristics associated with a person or object being characterized.

In accordance with a broad aspect of the invention a call is retransmitted or otherwise transmitted to a set of remote stations. Each station in the set of stations calculates its priority according to a preselected protocol and retransmits or transmits an indication signal for a period of time that is indicative of the calculated priority, or preferably of a range of priority values. In general, mine from a remote station transmits at the same time and at the same frequency.

In one embodiment of the invention, all stations broadcast on the same frequency. In a second embodiment of the invention, more than one frequency is used for communication and both time and frequency indicate priority. In a third embodiment of the invention, all stations transmit at the same time, and the priority interval is characterized by the transmission frequency.

It should be understood that, since more than one indication signal can be retransmitted at the same time and with the same frequency, there is no identification of the responding stations, but only an indication of those priorities (or instead priority ranges, since each time / frequency "slot" characterizes a range of priorities) that characterize at least one remote station.

A control center monitors the transmissions of the remote stations and determines which of the slots that have an indication signal has the highest priority. It is convenient to order the response time period in time (or time / frequency) slots each of which represents a range of priority values ​​preferably in descending order of priority. In this way, the control center only needs to search for the first strip that contains an indication signal.

Once the upper range of priorities that are maintained by at least one remote station is determined, a second call is retransmitted or otherwise transmitted requesting responses only from those remote units that are within this range. The time or time / frequency slots are now distributed, rather than by a predetermined protocol or specifically by means of the particular call, in such a way that they cover this range of priority values.

Stations having priorities within this interval retransmit or otherwise transmit indication signals in response to the new call in predetermined time or time / frequency slots. This process of determining the upper priority range and redivision of the range continued until certain criteria are met. This stage of the process which is often referred to herein as the "localization phase", (sometimes referred to herein as "first phase" or "phase one") ends when the priority interval is no longer significant or when the number of subintervals to be completed falls below a predetermined number based on the statistics of the total number of participating remote stations and the final priority interval or when some other predetermined criteria are met. At this point, the number of stations responding to the highest priority is believed to be small.

A procedure for distributing the time and frequency bands, which provides some indication of the number of answerers having each priority, consists in that all answerers having a given priority interval transmit at the same time and with a specified frequency. randomly (but within system bandwidth). By determining how many of the frequency bands are completed, a measure of the number of respondents that fall within the priority range can be estimated.

The system then preferably initiates an "identification phase" (sometimes referred to herein as "second phase" or "phase two") which begins with retransmission or transmission of some other mode of communication. an additional call requesting those stations with the highest (final) priority interval that are in the locating phase to identify themselves only

ES 2 173 113 T3 themselves. Each of the stations that has a priority within this interval retransmits or transmits in some other way a signal that includes an identifier of the station in a time slot, of time / frequency or of frequency that it randomly chooses between a set of available stripes of this type. If the number of stations expected within the priority value range is expected to be only one with a high probability, then only one identification strip can be assigned. Other types of fringes can also be used for the identification step, such as coded spread spectrum signals. In addition, multiple bands can be used for the same priority range to improve detection reliability in both locating and identification stages. The identification strips generally have an information support capacity that is higher than that of the strips used for the indication of priorities since more information is transmitted during the identification phase.

Therefore, when a set of remote stations are within the final range of values, it can be expected that more than one of the stations will respond in at least some of the bands, in which case their identification signal will be unintelligible. However, since the number of stations is relatively small, at least some of the strips will have only one identifying mark. In general, the station that has this signal is chosen since at this stage the difference in priority between the stations is generally not important. In some applications more than one identification signal may be retransmitted in a particular slot, however, one signal may be clear. This station will then be chosen.

In this way, according to a preferred embodiment of the invention, a method is provided for the discrimination of priorities between a set of remote stations, the stations having variable characteristics related to the priority, consisting of the steps of:

(a) first transmitting a call to a set of said remote stations;

(b) calculation, at each of the stations, of a priority according to a predetermined protocol for the respective station; and (c) they transmitted, by means of the stations, a signal at a predetermined time and frequency, the said time and the said frequency of the calculated priority being indicative.

In a preferred embodiment of the invention, more than one station transmits at the same time and at the same frequency.

Preferably, the stations answer the call for a predetermined period of time which is divided into time / frequency slots where each time slot has a range of priority values.

In a preferred embodiment of the invention the method includes the step of:

transmit at least one additional call requesting a response from those stations that have a priority within a restricted range of priority values. Preferably, the stations respond to the additional call by transmitting a signal at a predetermined time and frequency, said time and said frequency being indicative of the priority calculated within the restricted range of priorities.

Preferably, an additional call is made to request those stations having a priority within a narrow band to transmit an identification signal. Preferably, the identification signals of a station having the narrow band of priority values ​​are transmitted during a slot of a set of time / frequency slots that are randomly chosen by means of the station and where a station is chosen whose Identification signal is clearly received during a time / frequency band.

In a preferred embodiment of the invention the stations transmitting their identification signals are chosen by means of a random process that is carried out by the remote stations.

In one embodiment of the invention all stations relay signals at substantially the same frequency. In a second embodiment of the invention, the stations transmit their signals at different times and frequencies where, for the determination of priorities, both the time and the frequency are indicative of the calculated priority. In a third embodiment of the invention all stations transmit at the same time.

Further provided in accordance with a preferred embodiment of the invention, an apparatus for priority discrimination between a set of remote stations, the stations having priority-related variable characteristics, consisting of:

(a) a first transmitter transmitting a call to a set of said remote stations;

(b) calculation apparatus, in each of the stations, which calculates a priority of the station according to a predetermined protocol in response to the call; and (c) a set of second transmitters each associated with one of the remote stations transmitting a signal at a predetermined time and frequency, said time and said frequency being indicative of the calculated priority.

Brief description of the drawings

To better understand the invention and to see how it can be carried out in practice, non-limiting embodiments of the invention will now be described with reference to the attached drawings, in which:

Fig. 1 schematically shows the main components of a preferred system for carrying out the invention;

Fig. 2 is a flow chart showing the main steps associated with a preferred method of carrying out the invention;

Fig. 3 schematically shows how vehicles are located during an initial location phase based on distance with

ES 2 regarding the location of the customer according to a preferred embodiment of the invention;

Fig. 4 schematically shows how vehicles are located during a second iteration of locating based on distance;

Figs. 5A and 5B are two parts of a state diagram showing various options associated with a first locating phase in accordance with a preferred embodiment of the invention;

Figs. 6A and 6B are two parts of a state diagram showing various options associated with a second identification phase in accordance with a preferred embodiment of the invention;

Figs. 7A and 7B show timing diagrams related to the locating and identifying phases respectively of a priority discrimination according to a preferred embodiment of the invention;

Fig. 8 is a block diagram showing the main components of a control center according to a preferred embodiment of the invention; and Fig. 9 is a block diagram showing the main components of a control unit with respect to each of the remote units in accordance with a preferred embodiment of the invention.

Detailed description of a preferred embodiment

Fig. 1 shows a typical scenario in which the invention can be employed. In this scenario a geographical area 10 is defined by a boundary 11 within which a system according to the invention is operative.

An identification system according to the invention includes a control center 12 and, optionally, a set of taxi platforms 13, 14 and 15 that constitute sub-control units, each of which serves a respective zone within the area. 10 and can forward a request from a customer to the control center 12.

Associated with each of platforms 13, 14 and 15 are respective groups of participants (e.g. taxis) of which two groups 18 and 19 are associated with platforms 13 and 15, respectively, as shown in Fig. 1. The groups of participants 18 and 19 generally consist of some taxis that are standing near their respective platforms waiting for instructions from them and of other taxis such as 20, 21, 22, 23 and 24 that are circulating within area 10 and that are in available to carry out work after receipt of instructions or that, alternatively, are busy and therefore not available.

A customer 25 located somewhere within the area 10 transmits a service request to the control center 12 telephonically via a Public Switched Telephone Network (PSTN). The control center 12, in turn, relays an invitation message to all participants who are within area 10 either directly or through a remote station 30 which is normally located in such a way that it covers the entire area 10. The control center 12 can also

113 T3 8 receive messages through station 30. Alternatively, the control center 12 relays and receives messages directly.

Remote station 30 may be located within area 10, or alternatively if the area is built with tall buildings, outside the limits of the built area, if this location reduces signal blocking between taxis and the repeater station by drivers. tall buildings and the like and for other reasons.

In some cases, the customer calls a particular taxi platform by telephone since it is the closest platform to the customer's location. In this case, it is generally preferable that one of the taxis associated with the taxi platform is sent to the customer unless, of course, all the taxis associated with the platform are currently occupied (or that they are not suitable by others. reasons), in which case one of the taxis associated with another of the platforms will be assigned for the job.

In this case, the association of a taxi with a particular platform may constitute at least one of the criteria used to choose the taxi to be assigned to the customer 25. This selection criterion is a staotic variable and, once set, it never varies since a taxi is always associated with a platform. However, the actual priority assigned to each of the taxis is also a function of several independent dynamic factors that are subject to constant fluctuation. Of these, the distance of the taxi from the customer is the most important example. However, other dynamic conditions related to the instantaneous state of a taxi also affect the respective priority of the taxi in such a way that, for example, a taxi that is currently busy or one that has insufficient capacity for the number of passengers that must be collected did not participate in the selection process and a taxi that was waiting on a platform would have priority. The taxi stop time can also be an important criterion.

It was appreciated that in general there are many different cooperating factors, or selection criteria, that influence the priority assigned to each individual taxi within the 10 area. On the other hand, it generally happens that each selection criterion has a different “weight” associated with it in such a way that the final magnitude of the priority associated with each respective taxi is constructed from many different selection criteria each of the which have a different influence on the actual assigned priority.

For example, in the simplest case, it may happen that only the distance from the taxi to customer 25 is of interest. This simple case does not take into account the fact that other customers may have already requested a service and that it may not have been been prosecuted yet. Thus, another customer who is close to customer 25 but still some distance from the nearest available taxi in area 10, may have a prior service request. However, in the simplest of systems where only the distance from the taxi to the customer is important, this earlier request would not be recognized.

In a preferred system where you have

Taking many factors into account the priority assigned to each taxi can often be seen as a multidimensional vector that is the sum vector of priority component vectors each related to a different selection criterion.

A preferred procedure for assigning a job to one of the taxis in response to a request from a customer 25 will now be explained with reference to Figs. 1 to 7. For simplicity's sake, it will initially be assumed that the only interest selection criterion is the distance of a taxi from the customer 25.

Fig. 2 shows a flow chart of the operation of a preferred system of the invention. The left part of the flow diagram consists of the operation of a first phase, locating and the right part of the flow diagram consists of the operation of a second phase, identification. The localization phase begins with the retransmission of a call message to all participating taxis informing them that a priority must be determined to respond to a pending request for service. The criteria to determine the priority must be sent together with the call or, alternatively, they can be part of a preselected protocol used for determinations of this type. Alternatively, there may be several protocols of this type in one of which the call is identified by means of a code. In the simplest case of a delivery system where the distance of a taxi from a specified location is the only selection criteria, there is no need to inform the taxi of the selection criteria each time an invitation message is transmitted.

In response to the call, each of the taxis uses the selection criteria to determine its own priority according to the protocol. The protocol also includes a set of priority value ranges and a communication protocol that subdivides a time period and / or a frequency range into a set of time or time / frequency ranges each of which is associated with one of the priority ranges.

Each participant who is not immediately removed for further participation due to normal unavailability (for example, they are already busy or are already answering a call) responds to the call message by transmitting an indication signal in the appropriate time slot or time / frequency according to their respective priority. The indication time slots all start at one point in time relative to a common time base for all participants. It is important to note that all those responding participants that have a priority within the same interval will reply at the same time and with the same frequency. As a consequence, substantially simultaneous indication signals are received by the control center from those participants having the highest priority as determined in the current priority resolution according to the protocol.

The indication signals, which are preferably pulsed CW, are sufficiently non-destructive with respect to other simultaneously transmitted indication signals and have at least a sufficient pulse width to allow an indication that at least one of the taxis has responded in a given time slot. In certain cases it may be necessary to add some blurring or other variables to the signals in order to avoid destructive interference.

Since the indication signals can and usually overlap, even a fairly narrow bandwidth retransmission channel can be used, there being no need to discriminate between different indication signals in the same priority band.

The control center monitors any responses and determines which fringes have a valid cue signal (free from noise or other transient effects). Preferably, the time slots are arranged in descending order of priority, such that the control center can ignore all slots after the first "occupied" slot.

The control center locates all those responding taxis that have the highest priority interval with respect to which a valid indication signal has been received. Except for what will be described later, taxis with a lower priority will be excluded from any additional consideration.

If a predetermined criterion for stopping the locating phase has not been reached, then an additional call is retransmitted requesting that all taxis having a priority within the highest priority interval to answer. The response from the taxis is similar to that sent in the previous stage except that the time or time / frequency bands now represent sub-intervals within the highest indicated priority interval. In general the call will include this interval and may include a protocol indication to divide the bands between the priorities.

It should be understood that, for the more general case of multiple criteria, the priority vector may be a function of the iteration number or the priority interval. Thus, for example, the first iteration can be used to eliminate taxis that are far enough away from the destination without putting much weight on stopping time. The second iteration may give more weight to downtime or other factors. In general, taxis that have moved closer to the destination since the last call and that have an increased priority can participate in the second iteration even if they did not have the highest priority in the previous iteration or if they had not been detected as having this priority. On the other hand, a special strip can be provided for taxis whose priority is now higher than the highest interval detected in the previous iteration. These taxis will be ahead of the other taxis using the special strip.

This iterative reduction of the number of participants continues until certain criteria are reached.

It is 2 predetermined rivers. These criteria may include consideration of the priority resolution achieved. The criteria can include a statistical estimate of the number of vehicles that have not been removed. For example, if in a given iteration in which a substantial number of sub-strips have been assigned, only one or a small number of sub-strips contain an answer, it can be determined with enough certainty that the number of taxis remaining in the The system is small and the iteration process (and the locate phase) is complete.

Another iterative approach that can sometimes be used is to restrict the responders in the first phase to a single interval or a limited number of intervals. It is assumed that the interval of interest is between 0-10 km with respect to the client. A first call would only ask for answers from those taxis that were closer than 5 km from the customer. This distance could be divided into intervals or a single interval could be used. If there are no responses, then the call will request responses from those taxis that are in the range of 5 - 10 km. If there is an answer, then further delineation of the interval will successfully narrow the interval of distances.

Preferably, in the locating phase no participant was actually identified, and therefore it would not yet be possible for the control center to send the customer a particular taxi. Before this can be done, it is first necessary to complete a second phase, identification, where one of the taxis that is located at the end of the first phase is uniquely identified.

An additional call is retransmitted or otherwise transmitted to the participants indicating that an identification phase has begun. All localized participants that remain at the end of the first phase are invited to retransmit or otherwise transmit their identification codes in a range of a number of identification ranges (which can be time or time / frequency ranges). These strips have a duration in proportion to the information that is going to be transmitted through taxis. The number of identification time slots is determined according to protocol and depends on the application, and may be based on the number of participants believed to remain.

For example, in a shipping system, the priority scale may extend from a distance of 10 km from the customer location and the initial priority resolution (as long as the distance criterion is involved) may be 1 km that it is reduced during two successive iterations to 100 m and finally to 1 m. With this fine priority resolution it should not be expected that more than a small number of taxis will be located since a rapid convergence identification phase that has only a few time slots should be sufficient to identify one of the located participants. It is not suggested that a distance of 1 m is significant in determining priorities for ta

113 T3 12 xis, however, the use of such fine distinctions helps to reduce the number of taxis participating in the identification phase. However, as explained below, the protocol has sufficient discrimination built into it to allow possible errors in the number of assigned identification time slots and to compensate for these errors when necessary.

The identification strips are preferably not assigned in any way, and the taxis choose their strips in some random way. It can be expected that at least for some of the most fringes of a taxi it will relay its identification information. These broadcasts may not be read by the control center that chose the first taxi that it can identify. If multiple shipments are required to the same destination, such as when there are too many passengers for a taxi, the second phase may have to be repeated several times until the required number of taxis are shipped. On the other hand, in extreme cases, it may be necessary to require the identification of taxis that have a lower priority.

As in the locating phase, a slot can be provided in the identification phase for taxis that have a higher priority than the call. These taxis may have moved closer to the destination or their signal may not have been received by the receiver due to interference or blockage.

Once the general procedure for iterative localization had been described, during a first phase, with fewer and fewer participants and later, during a second phase, for the identification of a desired number of the localized participants, a specific application of the same to the localized participants was now described. scenario shown in Fig. 1 and referring to Figs. 3 to 7 of the drawings.

Referring then to Fig. 3, a customer 25 has requested a taxi. Shown within a target circular area 40 centered around customer 25 and with a boundary 35 at different distances from customer 25 are four taxi vehicles V_to, V_b, V_c, and V_d. Vehicles that are outside of limit 35 are excluded from consideration.

The target area 40 is divided into a set of concocentric sectors of which only the outermost sectors 42, 43, 44 and 45 are shown, each of which has a width AR and are located radially with respect to the client. Adjacent sectors 42 and 43 or 43 and 44 or 44 and 45 are contiguous although for the sake of clarity and explanation these are shown in Fig. 3 as if separated from each other.

It will be taken into account that vehicles V_b and V_care inside the first sector 42 (most interior), the vehicle V_d It is within the middle sector 44 and the vehicle V_or It is in the last sector 45 (outermost). Since you want to assign the job of providing customer service to the vehicle that is closest to it, it is evident that one of the two vehicles V_band V_c the innermost sector 42 should be identified as the most suitable for the job. It will also be evident that the number of vehicles there are

ES 2 173 113 T3 in any particular sector is a function of the width of the sector. Thus, if the width of each sector is increased from AR to 3AR, it is evident that the vehicles V_b, V_c and V_d they will now be in the new, more interior sector, which consists of the original sectors 42-44. In this way, the width of each AR sector constitutes a priority resolution with which a priority is assigned to the participating vehicles. The coarser (i.e. lower) the resolution, the more vehicles will respond to the selection criteria and will be rated with a particular priority associated with them, while the finer (i.e. higher) the resolution, The lower the number of vehicles that meet the selection criteria will be and they will be rated with the corresponding priority. In this way, after a first locating stage in which a small group of taxis are chosen, in a second locating stage of the taxi with the highest priority, a coarse resolution is established (finer, however, than in the first stage) as shown in Fig. 3 and a call message is transmitted by the control center 12 to all participants. The call message also preferably defines a time slot ΔΤ that is divided into an equal number of time slots ΔΤ of equal width in such a way that the total number of time slots is equal to the total number of priorities, i.e. number of sectors. In a further preferred embodiment of the invention, frequency diversity can be used to define multiple fringes at the same time, each fringe being at a different frequency distinguishable by the control center.

After receiving the call message, each of the participating taxis determines its priority according to the selection criteria, which, in the simplest case, is assumed to be only the distance of the participant with respect to the customer and within the maximum radius R_max. Thus, both V_bas V_c are assigned the highest priority, while vehicles V_d and V_to (in this order) they are successively assigned lower priorities. It should be noted that there are typically hundreds of vehicles within target area 40; only a few are shown in the drawing for clarity. In addition, each vehicle can have a handset (see Fig. 9) which has a deactivation switch by means of which the driver can prevent the transmission of a response message after receiving a call message from the control center 12. In this way you can leave your obligations, etc.

Active participants V_or to V_d they now transmit an indication signal within the time slot ΔΤ corresponding to their priority. In this way, vehicles V_b and V_c transmit a first indication signal; vehicle V_d transmits its second indication signal; and vehicle V_or transmits its third indication signal. In a real situation, of course - there may be many time slots corresponding to a high number of high resolution priorities and perhaps hundreds of vehicles transmitting an indication signal in the same time slot. This fact, by itself, is not important since all that matters during this first phase of the process is to determine the first time slot in which a vehicle transmits an indication signal.

Once this is done, it is immediately apparent that this is the sector closest to the customer in which at least one vehicle is located and therefore all vehicles in all other sectors can now be removed. In a practical implementation of such a system, the retransmission and reception time for the transmission of the call message from the control center to the participants and for the reception of the first indication signal from the same lasts a short time. Thus, in a relatively small time interval, thousands of field participants can be reduced to a small number of potentially suitable participants for the job.

On the other hand, if a dual communication system is used, it is not necessary for the control center to wait all the time ΔΤ, and can advance to the next iteration or the next phase when a first indication signal is received.

As explained above, this process is iteratively repeated as often as necessary, with each iteration having resolutions with increasingly fine priority (that is, sectors with decreasing ΔR width), until a resolution is reached. default. At this point, the width of the remaining sector is small enough that only a small number of participants are likely to be found within it. It is not known, of course, how many participants there are in this remaining sector since, regardless of whether only one participant or many send an indication signal that begins in a particular time slot, the control center does not receive a message that can uniquely identify one of these participants.

It should be noted that the reception time it takes for the control center to process a response from the highest priority participants is a function of the number of time slots ΔΤ. Thus, when the resolution increases, there will be more time slots, and since each requires a mononymous transport time, it took more time to identify the highest priority time slot. Therefore, there is a trade-off between, on the one hand, increasing the resolution in such a way that the most suitable participant is identified in fewer iterations and, on the other hand, increasing the cycle time of a given iteration by doing this.

Fig. 4 shows a later iteration of the paging phase where the priority resolution is increased and an additional call signal is transmitted to the participants. The participants who have been located at that time V_bor V_c that are in sector 42 that has the highest priority at that moment are assigned to new slots according to a finer priority resolution and again transmit indication signals during corresponding time slots8

ES 2 173 113 T3 according to your priorities. As a consequence, it follows that V_c has a higher priority than V_b and this indication signal is therefore transmitted first. However, from a control center perspective, there is no way of knowing how many participants exist in what is now the sector with the highest priority. All that can be known is that at least one participant has priority.

Thus, although there may still be hundreds of participants within the localized sector, it is expected that with the increased priority resolution only a small number of participants will now be located. One of them is now identified to respond to the request for service. During this second identification phase, the control center assigns a new time interval ΔΤ - ID and divides this time interval into a number of time bands of equal width ΔΤ in relation to the expected number of participants in sector 42 of higher priority. The expected number of participants in sector 42 is statistically determined as a function of the resolution of sector ΔΗ according to the application. The only remaining participant located V_c in sector 42 of higher priority now randomly selects one of the time slots and transmits, within the randomly selected time slot, an identification message so that the sending participant can be uniquely identified.

In the most general case where there is still a number of localized participants, the control center receives a set of identification messages some of which, of course, may have been transmitted during the same randomly selected time slot. However, it is expected that at least one of the identification messages can be uniquely identified and, in this case, the job is assigned to a participant who can be identified. When possible, of course, to improve speed, work is assigned to the first uniquely identified participant.

If it is not possible to uniquely identify one of the participants, the communication protocol allows appropriate action according to each particular situation. Thus, it may happen that during the final iteration in phase one, no participant was located. This fact itself could be due to several different reasons; for example, the call message may never have reached the participants or, more likely, the response from the higher priority participants may not have been received, possibly because it was hampered by an obstacle in its path.

Alternatively, possibly too many participants were located in the final iteration of phase one and an insufficient number of identification time slots were assigned during phase two. In this case, identification messages may collide during all identification time frames, making it impossible to identify any participant. In the most general case when more than one participant is to be identified, it may also happen that too few identification messages arrive in phase two belonging to an insufficient number of participants who have been located in phase one.

The various strategies for managing each of these possibilities from the point of view of the control center were now described with reference to Figs. 5 and 6 showing state diagrams relative to the locating and identifying phases, respectively. In both diagrams, the following terminology is used:

<td>PHASE-1.x</td><td>: xeszma iteration of phase 1;</td>

<td>PHASE-2.x</td><td>: xészma phase 2 iteration;</td>

<td>IB</td><td>: Relay message from the control center;</td>

<td>RD</td><td>: Detection of the answering machine signal and signal processing;</td>

<td>IBPH1.x</td><td>: Broadcast Messages x^{it is}'‘^ma the Control Center in Phase 1;</td>

<td>IBPH2.x</td><td>: Broadcast Messages x^{it is}'‘^ma the Control Center in Phase 2;</td>

<td>ΔTRTPH1.x</td><td>: Xoesimal time interval for the Answering Machine Transmission activity in Phase 1;</td>

<td>ΔTRTPH2.x</td><td>: Xoesimal time interval for the Answering Machine Transmission activity in Phase 2;</td>

<td>X</td><td>: Number of iterations in Phase 1 or 2 (depending on the application);</td>

<td>PIN</td><td>: Total number of iterations carried out in the current Phase;</td>

Limit1, Limit2: Maximum number of iterations depending on the application for Phases 1 and 2, respectively.

n: default number of successful iterations

PS: Priority band

Thus, referring to Figs. 5A and 5B, if during a successive iteration, no indication signal is received (that is, a FAILURE is detected), the initiator requests at least once that all participants that have not yet been identified transmit a respective indication signal and this is repeated until an indication signal is received or for a maximum number of iterations which is determined according to the protocol. Subsequently, even if the resolution is higher than a minimum resolution determined according to the protocol (and the iteration process has not been completed for some other reason), priori9

Additional resources with a coarser resolution are assigned to all participants who have not yet been identified, or until the resolution reaches the minimum resolution.

Another way to check if a FAILURE is true is to provide an additional slot during which all stations that had retransmitted during designated priority slots will retransmit again. If no signal is received during this time slot, the FAILURE is verified.

Referring to Figs. 6A and 6B, if during any iteration no identification message is received through the control center and during previous iterations a number less than the desired number of identification messages was received in such a way that the identification of the respective participants is not allowed or if invalid data was received, Additionally, the stage consisting in the control center requesting at least once that any currently located participant who has not yet been identified retransmit their identification message is included.

If a number less than the desired number of valid identification messages were received in such a way that the identification of the respective participants was not allowed due to the fact that more than one identification message arrived in the same identification strip or for any other such reason As the reception of erroneous data, thus making it impossible to determine the respective identifications, the following sets of actions must be carried out.

One possibility is that the control center assigns all the remaining localized participants who have not yet been identified a higher number of discrete identification time bands than the previously assigned number, and that it invites the located participants who have not yet been identified. been identified to transmit a respective identification message during one of the new communication time slots. In other words, the number of localized participants is maintained but more identification time slots are assigned in such a way that the probability that the number of valid identification messages is received is increased, reducing the probability of collisions. Alternatively, taxis may be required to choose a random number that was subsequently used in comparison with some reference number to eliminate some of the taxis or that can be used to change the priorities of the taxis to eliminate some of them. Alternatively, additional criteria can be added to reduce the number of participants.

Alternatively, if the protocol allows a maximum priority resolution, then as long as the current priority resolution is lower than the maximum priority resolution, phase one can be repeated as long as it is required for a maximum number of iterations determined according to the protocol. with increasingly fine priority resolutions, until the maximum resolution is reached in relation to all participants who have not yet been identified. This results in fewer participants being located and again reduces the probability of collisions in phase two when any newly located participants are identified.

If, on the other hand, during a successive iteration, a lower than desired number of valid identification messages is received in such a way as to allow the identification of the respective participants because an insufficient number of participants have been located during previous iterations, then the opposite must be done. In this way, as long as the resolution is higher than a minimum resolution determined according to the protocol, phase one is repeated whenever necessary for a maximum number of iterations determined according to the protocol with priority resolutions each time coarser. until an indication signal is detected or until the minimum resolution is reached. This process is carried out in relation to all participants who have not yet been identified and, by locating participants in phase one who had not been previously located, the probability that the desired number of newly located participants is increased. identified later in phase two.

If, during phase one, no identification signal is received in response to a call message, the control center requests at least once that the participants retransmit an indication signal. After receiving the call message, the participants assign themselves priorities and transmit respective indication signals during a corresponding indication time slot. This covers the possibility that the call message never reaches the located participants, or alternatively, that their responses never reach the control center.

The protocol includes at least one termination condition such that no further iterations are carried out even though no indication signal has been received and / or a number of participants less than the desired number has been identified. This is necessary to avoid an infinite loop being executed in the event that, in a particular application, there is not a sufficient number of participants that can be identified.

In all of the above cases, data is stored in relation to any of the participants that have already been identified and subsequent iterations are carried out just to identify additional participants.

Figs. 7A and 7B show a timing diagram relative to the information flow between the control center and the V participants_to, V_b, V_c and V_d during the example of Figs. 3 and 4.

It was taken into account that in the initial locating phase, each participant selects a time slot according to their respective priority, in such a way that the participants with the highest priority broadcast first. Consequently, as soon as the control center receives a response from the participants, the highest priority can be determined immediately according to the time slot data that was received first. They can carry

Additional iterations will now be carried out, when necessary, without the need even to wait for responses from lower priority participants. This causes a very fast convergence of the location phase towards the priority interval that contains the most suitable participant. This requires a complete dual system. Figs. 7A and 7B show the timing diagram for a dual medium system.

In another embodiment of the invention, priorities can be assigned according to a measured time elapsed since the participants have carried out some activity, for example, taxis are assigned priorities according to the time they have been stopped.

In a first iteration of phase one, the mutually common priority scale was related to the elapsed time of, for example, 3 hours and the priority resolution is, for example, half an hour. Thus, each interval on the priority scale corresponds to an elapsed time of half an hour.

In a second iteration of phase one, the mutually common priority scale is related to an elapsed time of half an hour and the priority resolution is 2.5 minutes. Thus, each interval on the priority scale corresponds to an elapsed time of 2.5 minutes. If during the first iteration a signal was received in the time slot of two to two and a half hours, then the time slots of the second phase can have a resolution of 2.5 minutes and span the interval between these limits.

If this is found to be accurate enough that not too many participants have the same priority, the process ends after only two iterations. It is now appropriate to implement phase two where one of the localized participants is identified.

It will be understood that since, during the identification phase, a participant is selected, in effect, at random, it cannot be ensured that the identified participant is really the one who has waited the longest time interval. However, it can be said with certainty that the identified participant has the highest priority within the priority resolution (in this case 2.5 minutes).

If, despite the above expectation, it becomes impossible to identify a single participant in phase two because too many participants have been located during phase one, then, as explained above, several options are available. More identification time slots can be assigned in phase two or, alternatively, an additional iteration can be carried out in phase one with even finer priority resolution, for example 6 seconds, before repeating phase two with respect to a lower number of localized participants or one of the other options described above can be used.

In all of the embodiments described above, at least two phases are required to identify a localized participant. Thus, during a first phase, only participants are located and identified during a subsequent second phase. However, according to a more sophisticated scheme, the identification of a particular participant can be established during the first phase by transmitting an identification message as an indication signal. The identification message can be decoded in the particular circumstance that only one participant has the highest priority, such that only an indication signal is transmitted in the highest priority time slot, and such that there is a sufficiently long time interval between the reception of successive indication signals by the control center to allow decoding of the identification signal before a lower priority indication signal arrives in a time slot. of posterior indication. Alternatively, the identification time slots are made long enough that different slots do not overlap. In this particular case, the second phase of identification of the localized participants is eliminated.

A further consideration deals with the possibility that the highest priority participant may not be located in phase one due to a malfunction. Thus, for example, this indication signal may not be received because it has been obstructed by an obstacle in its path or if this signal has been subjected to weakening. This may not be important if other participants having the same priority could, however, transmit indication signals, since, if the indication time slot with the highest priority is determined and all the participants associated with the itself, even a participant whose signal of indication had been lost would be located.

The protocol can take this possibility into account, preferably reserving the first indication time slot in the next iteration for the exclusive transition in it by a non-localized participant who has a higher priority than the localized participants. The control center then transmits a call message to invite the located participants to transmit a respective indication signal during any one of the indication time slots except for the reserved indication time slot.

As for the participants who have just been located, the process is essentially unchanged; Each one of the rection located participants transmits an indication signal, one of the unreserved indication time slots according to their respective priority. However, any previously unlocated participant having a higher priority than the newly located participants transmits a respective indication signal during the reserved time slot.

Within a simple phase one iteration, prioritization of each participant can be carried out in relation to a different subset of selection criteria for at least some of the participants. In effect, this allows the execution of different strategies

ES 2 173 113 T3 search each in relation to a respective indication time slot. For example, the first indication time slot that has the highest priority can be related to all the participants who are located within a radius of 10 m from the client without any additional restriction; while the second time slot for indication can be related to all participants who are located within a radius of 25 m from the client and who have been waiting for instructions for more than 20 minutes. Thus, Boolean OR search strategies or other search strategies can be carried out in a single iteration.

On the other hand, during each iteration the participants can optionally assign themselves a priority having a magnitude outside the priority scale such that they are not located by the initiator. This can be done if, for example, a participant is busy for some other reason or does not wish to receive instructions for any other reason.

During a particular iteration, the priorities assigned to each participant should be absolute with respect to a mutually common scale that is itself external to and independent of the participants. However, between successive iterations the priority scale can be perfectly related to different combinations of selection criteria. In this way, very fine-tuned search strategies can be carried out so that all participants responding to a first combination of selection criteria are located during a first iteration, while all participants located responding to a different combination of selection criteria. selection criteria are located during a successive iteration.

Once a sufficiently small number of participants have been located such that, according to the protocol, the identification of a desired number of participants is likely to lead to a satisfactory result, the second phase described above is initiated. The number of identification stripes to be assigned to located participants is calculated by first estimating the number of located participants remaining at the end of phase one. The number of identification fringes is then calculated according to the estimated number of localized participants that must transmit respective identification messages, so as to reduce the total time required to identify the required number of participants.

In this connection, it was understood that there is a compromise between assigning too many and too few identification time slots. Specifically, assigning too many identification time slots reduces the probability that a localized participant will select an early identification time slot, thus increasing the time required to identify the highest priority participants. On the other hand, assigning too few identification time frames increases the probability that more than one participant will select the same identification time frame. In this case, the collision resulting from more than one identification message makes it impossible to identify the respective participants, requiring additional iterations and again increasing the identification time. In practice, the number of identification time bands can be minimized by increasing the maximum priority resolution in phase one to locate more than the expected number of participants to be identified in phase two, or by using a random process. to eliminate some of the participants.

In the specific embodiments described above, this process of assigning priorities to each of the participants is carried out with the vehicles of the participants themselves since only they know their locations with respect to the customer. On the other hand, the responsibility of monitoring the movements of the participants in terms of their situation, availability, occupation, load and all other selection criteria that may be significant is now transferred to the vehicles of the participants themselves. Unlike the systems proposed up to now, where an employee in charge of centralized shipping had to keep track of all these parameters.

As a consequence of this, the communication channel between the control center and the participants may have a relatively small spectrum width compared to the systems proposed so far. Furthermore, the task of locating potentially suitable participants is distributed among the participants themselves rather than being determined solely by the control center. This distribution leads to a reduction in the calculation power required for the control center.

Although the selection criteria must be known, obviously, by the vehicles of the participants, the way in which this is made known may vary according to the circumstances. Thus, for example, the selection criteria can be set and made known to participants in advance (in which case the selection criteria are not subject to change). Alternatively, the selection criteria can be determined online by the control center and subsequently transmitted to all participants together with the call message.

Thus, in the particular example described above, during the first locating phase it can be predetermined that each sector has an amplitude of 10 km and that in later phases, the amplitude of each remaining sector is reduced by a factor of 10 until the sector has an amplitude of only 10 m, with which all those vehicles that are within the sector of 10 m of amplitude will send an identification message; Or, alternatively, the amplitude of each sector in each respective allocation phase can be transmitted to the participants via the control center. To reduce the number of participants in the identification phase, the reso

The resolution of the localization phase can be increased artificially, that is, beyond the point where it is significant.

It should also be noted that once a particular participant has been uniquely identified to carry out a job, he or she is notified in the normal way through the control center, in any of a number of ways that are well known in the art, such as by voice over a communication channel.

On the other hand, although in the preferred embodiment described above, a participant is uniquely identified as the most suitable, in fact on some occasions it may be appropriate to omit the second phase of identification entirely. In these cases, the participants with the highest priority are not uniquely identified as individuals but are identified as a group. A situation of this type was related to the improvement of the service in particular areas. In this situation the number of taxis in a given area (a given distance from a fixed point) is monitored and additional cars are sent to the air if there are not enough cars in the area. The number of cars can be estimated statistically, for example, from the number of fringes that respond in a very fine priority fringe situation.

Another application of the prioritization system according to the invention is in the allocation of lines available for telephones or car transceivers. Currently, available lines are allocated when available. Thus, an unlucky user can wait a long time while a lucky user can get a lonea immediately. In a preferred embodiment of the invention, when a user wants a phone, he indicates it by pressing a call button or lifting his receiver. A computer chip associated with the car's phone records the moment a phone was requested or requested.

Lines are assigned based on waiting time. During its operation, a control center relays a call for priorities in accordance with a location phase of the present invention. Priority is assigned according to the wait time, and individual telephones relay signals during time slots according to their wait time. During a second phase of identification, one of the telephones is identified, in the same way as described above, and the available line is provided.

Referring now to Fig. 8 the main features associated with the control center shown in Fig. 1 are schematically shown. Thus, a transceiver and modem 50 coupled with an antenna 51 are provided. to maintain bidirectional communication with the participants (taxis) and connected to a message processor 53 that is coupled with a computer 54. The message processor 53 receives non-demodulated signals from the transceiver and determines the fringes that contain signals for the

113 T3 24 locating phase and identifies the participant (s) in the identification phase. A service request was made by the customer 25 by telephoning his nearest taxi platform and subsequently dialing this telephone number, and the request was routed to computer 54 through a Public Switched Telephone Network (PSTN). The computer 54 converts the customer's telephone number into a corresponding location based on a database stored in the computer. Alternatively, this communication can be carried out through an operator. A terminal 56 is coupled with the computer to allow an operator to enter commands and display data. In addition, the system also allows signaling by voice to an employee in charge of shipping at the control station or communication by voice between the taxi driver and the customer.

Fig. 9 shows the major components associated with a participant allocation unit 60 located in each of the vehicles. The allocation unit 60 preferably includes a transceiver 61 coupled with an antenna 62 for conducting bidirectional communication with the transceiver 50 at the control center 37. The transceiver 61 is connected to a vehicle computer 64 coupled with a microphone / handset 65 that provides a human interface between the vehicle computer 64 and the corresponding taxi driver.

A Global Positioning System (GPS) 66 or other position determination system such as those known in the art receives positioning data through an antenna 68. The Global Positioning System 66 is coupled with the vehicle's computer 64 and acted as a means of positioning to provide positioning information relative to a predetermined origin in relation to the corresponding participant. In this way, once the vehicle's computer 64 is provided with the customer's location, the computer, being coupled with the Global Positioning System 66, can determine the relative location of the participant with respect to the customer and thus determine, the participant's priority.

Associated with the vehicle computer 64 is a storage means 70 for storing the protocol according to which priorities are assigned. Any singular area that may affect the actual route is also stored in the storage medium 70, for example, obstructions such as rivers, road blocks, etc., which make the actual distance of the route greater than it would be. if they didn't exist. As explained above, the handset 65 allows the driver to assign himself a priority that is outside the range of the priority scale and thus exclude himself from the paging process. This also includes a handset to establish voice contact with the control center, as well as a search means to obtain a text message from it.

The system described above may include a complete dual relay network of

ES 2 173 113 T3 such that the control center does not need to wait for responses from all participants before locating the participants with higher priority. In this way, specifically, as soon as the control center receives a valid response, the participants corresponding to the response can be immediately located or identified while other participants are informed to stop the transmission of indication signals or identification messages. . This allows the locating and / or identification stages to be carried out more quickly. However, the invention can also be used in a simple relay network (for example, dual medium), despite the cost of longer location and identification times since the control center cannot transmit to the participants until all your responses have been previously received and validated.

It was appreciated that, instead of using a Global Positioning System, other systems can also be used to determine the location of a participant. For example, a route programmer based on dead reckoning sensitive to the location of each participant can be used to determine a route that has the minimum distance. Such a route programmer could possibly consist of sensors located at intervals along the road to sense the presence of a moving vehicle and to transmit to the vehicle data representative of its location with respect to a specified location for correction of deviations. mistakes. Typically, such a route programmer has a memory for storing therein a map with the contour scaled in such a way that an optimal route can be determined taking into account the nature of the terrain. Similarly, current traffic conditions can be entered into the route programmer at regular time intervals, so that traffic jams, road works, etc., can be considered when determining the optimal route.

In the above description it has also been assumed that a single channel relay network is used. However, this is by no means essential and a controlled centralized trunk building system having at least two channels can be equally well employed. This allows more than one job to be managed simultaneously, each on a different broadcast channel. Thus, in the case of a two-channel relay network, for example, having a first and a second channel, each call message is transmitted by means of a relay control channel in such a way that it is received by all participants associated with the first channel. After determining that it has not been located by means of the control center, a participant begins to measure the elapsed time and waits for a predetermined elapsed time locked on the first channel and subsequently returns to the retransmission control channel for message reception. additional call.

The period of time during which an unlocated participant remains locked on the first channel is long enough to allow the participant to be assigned an updated priority. Due to the dynamic variation in the state of a participant, it can happen that, with an updated priority, a previously unlocated participant becomes located in the next iteration. Thus, the period of time during which a non-located participant remains blocked on the first channel must be in addition to a sufficient duration to allow a corresponding indication signal and / or an identification message to be transmitted through the participant. to the control center, so that the control center can locate and / or identify the participant.

Alternatively, the call message can be transmitted through a retransmission control channel in such a way that it is received by all participants associated with the first channel and, after the determination that it has not been located by the control center. , a participant receives an instruction from the control center to immediately return to the broadcast control channel. This immediately frees an unlocated participant to participate in a subsequent search strategy on the second channel in connection with a different job.

According to another variation, an initial call message is transmitted along with the selection criteria through a retransmission control channel in such a way that it is received by all participants associated with the first channels. Each of the participants receiving the call message assigns himself from the priority scale a respective priority representative of his relative suitability according to the selection criteria and transmits an indication signal during a respective indication window. Only the located participants switch to the first channel and subsequent call messages are transmitted only to those participants who have been previously located via the control center. This again frees up an unlocated participant to participate in a subsequent search strategy on the second channel in connection with a different job.

It was appreciated that although the invention has been described with particular application to a taxi dispatch service, the invention has a more general application whenever a participant or a group of a set of participants is to be located according to their respective suitability based on in at least one selection criteria. It was further understood that, although the preferred embodiment has been described for the sake of simplicity by referring only to two selection criteria (i.e., distance and waiting time), in practice a larger number of selection criteria may be used, all with different relative weights so that an integrated search strategy can be implemented.

It will also be understood that although the invention has been described with particular reference to a two-dimensional terrain, it can equally be applied in a three-dimensional space.

ES 2 173 113 T3 sions and is therefore suitable for space or air travel, as well as on land and at sea.

Mention should also be made of the variable parameters in association with which the protocol works. These are generally application dependent and are usually incorporated with default values ​​within the protocol. Thus, if distance is one of the selection criteria, this fact can be represented by means of a default value of an associated parameter. Similarly, the lower and upper limits of the priority scale and the priority resolution associated with each iteration in phase one can be assigned to respective parameters each with corresponding default values.

Any unassigned parameters must, of course, have values ​​assigned to it before the start of phase one. This can be done during the start of the process before the transmission of the first call message to the participants. However, in certain applications, all parameters may have pre-assigned default values ​​that are acceptable to the application. In this case, the call message simply starts the process by allowing the participants to determine the appropriate priority scale and assign themselves respective priorities with the appropriate priority resolution; Thus, there is no need to inform any of the participants of the limit values ​​of the priority scale or of the priority resolution or even of the selection criteria.

Although the invention has been described with particular reference to a wireless relay network, it will be appreciated that the invention may have a much more general application. For example, cable communication systems may also employ the principles of the invention in which case it is not necessary for the indication signals to be CW. In these cases, the dynamic variables will generally not be the position; however, the system can generally be applied to systems with any set of dynamic variables.

The principles of the invention can also be used in a routing system, for example in a system that identifies buses or other vehicles that have been delayed and adjusts the speed and / or location of other buses to compensate for this fact. In the first (locating) stage of this use of the invention, the priority will be based for example on the time interval during which a vehicle is behind the schedule. Vehicles that are behind programming more than a predetermined time interval will then be located and identified in a second (identification) stage. Preferably, the identified bus would then be asked for its exact location.

A question will then be sent to other buses on the same bus line asking them about their position and, optionally, where they are with respect to their programming. Based on this information, a control center will determine the corrective action to provide an improved service, which may include steps such as increasing the speed of some buses, for example making them operate in a way that skips stops, slowing down some buses. , prevent some buses from leaving the terminal or add new buses to the route, perhaps at some intermediate point on the route. Proper instructions will, of course, be relayed to these buses after a corrective action plan is formulated.

The principles of the invention are also applicable to a routing system for the determination of areas of slow traffic and for the rerouting of traffic in these areas. In such a system, a large number of participating vehicles are asked questions about the delays they experience. When a vehicle experiences a delay greater than a limit, the vehicle's position is determined in the second phase. It should be noted that no identification signal is transmitted per se in the second phase, instead a position signal is retransmitted. Preferably, the delay is also verified by the driver of the vehicle to avoid false alarms.

Once the position of the vehicle with localized delay is determined, a new first stage (of locating) determines those vehicles that are close to the vehicle with specified delays, and determines, by means of second successive stages, the degree of delay as a function of the delay time. delay. On the other hand, by asking multiple questions, traffic conditions can be estimated. Based on this information, the severity of the delay can be determined and corrective action can be initiated, such as rerouting of other vehicles. In particular, information on traffic conditions and on the geographical extent of the delay can be transmitted to vehicles having routing devices of types that are well known in the art, which will be used by these devices to determine the seventh route for transportation. receiving vehicle.