WO1996030884A1

WO1996030884A1 - Communication of position signals from mobile units

Info

Publication number: WO1996030884A1
Application number: PCT/DK1996/000134
Authority: WO
Inventors: Willy Palle Pedersen
Original assignee: Willy Palle Pedersen
Priority date: 1995-03-30
Filing date: 1996-03-29
Publication date: 1996-10-03
Also published as: AU5143196A

Abstract

In traffic control or surveillance systems it is mandatory that the single mobile units communicate their positions to a central control station. According to the invention this is effected particularly advantageously using a mobile telephone network system such as the GSM-network. For one thing, such a network is well suited to handle many concurrent calls, e.g. from busses in city traffic, and for another thing such a network is also well suited for automatically localising the positioning of the mobile units throughout a widespread, cellular GSM or similar communication system.

Description

Communication of position signals from mobile units

The present invention relates to systems for communicat¬ ing position indications and, optionally, other information. As well known, during the later years it has been prac¬ tised to make use of special, satellite carried navigation system denoted GPS, for showing the geographical co-ordinates of the spot, at which an associated, mobile GPS receiver is located. Originally, this system was developed for maritime use, but it has been found applicable even for terrestrial use, though in that connection it could be desirable to ope- rate with an improved accuracy in some instances.

The system has been proposed for use for a determination of the position of mobile units, which may have a GPS recei¬ ver coupled to a radio transmitter, which will currently or with predetermined intervals transmit the actual position signal and an associated identification signal to a relevant traffic control center. This is a realistic possibility wher¬ ever the problem is to follow the movements of e.g. a number of freight carriers throughout a larger area, whereby the in¬ dividual truck companies may have their own traffic center. However, in connection with city area traffic systems of a type comprising a large number of vehicles which, potenti¬ ally, should deliver frequent position reports, typically a city bus network in large and semi large cities, there are two circumstances which make it difficult or impossible to use such a GPS based reporting system:

1) The GPS system is based on a comparative measurement of signal waves with an oblique direction of incidence from a number of moving satellites, whereby, due to the associated Doppler effects, it is possible to determine the position of the individual GPS receiver. Because of the oblique angle of incidence of the signal beams this will imply that in moun¬ tain areas as well as in forests and cities the beams may be shadowed so as to render the reception directly inoperative, while in city areas there may occur reflections of the wave beams, giving rise to inaccurate position determinations. However, it is here an advantageous possibility to use an en¬ tirely different system, viz. based on the use of e.g. road mounted markers transmitting an identification signal, which can be received by a detector on each of the vehicles and then be retransmitted to the traffic center along with an identification signal of the individual vehicle (city bus) . Also in principle, such a system will be suited better than the GPS system, as it will be given with a high accuracy, at which geographical spots the position or time indications should be transmitted, e.g. at each ordinary bus stop; on that basis it is possible, then, to work out various statis- tics with respect to the observance of timetables, and be¬ sides, the marker actuation of the detector of the bus may be used for activating internal functions such as an automatic announcement of the next stop or adjustment of ticket slot machines to another fare stage.

2) Whether based on the GPS or the marker principle - or even a combination of these principles, the larger traffic systems will potentially involve many simultaneous or almost simultaneous reportings to the central surveillance station. This may to a high degree complicate the layout or reduce the operational safety of these centers or systems, if or when there is only a limited number of radio frequences at dispo¬ sal. The equipment of the individual busses or vehicle units may well, based on electronics, be able to transmit the rele- vant signals very rapidly after the actuation of the signal¬ ling unit, and required endeavours for providing a more effi¬ cient signal reception will naturally be concentrated on the design of the receiver equipment.

However, there are problems of principal nature in making the high frequency section of such receivers more efficient, and with the present invention it has been recognised that it is possible to adopt a different route, viz. via a transmis¬ sion system, which may well cause a certain, yet acceptable delay in the signal transmission, but in return fully remove the high frequency problems at the receiver side. With the invention it has been found possible for the present purpose to point at an already existing type of network, viz. a pub- lically usable mobile telephone system, e.g. as known by the designations GSM or NMT, whereby the receiver can have the status of an ordinary 'receiver subscriber* on the ordinary telephone network, while the equipment in the individual mo- bile units may constitute 'calling subscribers' on the mobile telephone network, provided with a generator for automatic calling of the number of the receiver station. It will have to be accepted that in the relevant network or networks there will come a noticeable increase in the number of calls, but this is made acceptable by the fact that each call will have a duration of few seconds only. Likewise, it will be accept¬ able that some seconds may pass from the call is initiated until the brief report can be transmitted.

These networks with their associated, relatively fine meshed antenna systems are already particularly geared and officially privileged to receive and handle a high number of concurrent calls for through-coupling to different receivers at a reasonable minimum of time, and if the single calls are of brief duration the associated costs will be quite low. It is important that the receiver station can receive the re¬ ports in an already detected form, i.e. without any high fre¬ quency problems at all, whereby the traffic control center can easily be adapted to receive and handle large amounts of data. In practice, nothing will prevent that the mobile unit systems operate in conjunction with quite ordinary mobile telephones.

The relevant reportings to a single receiver may each be executed at short time, viz. few seconds, and the same re- ceiver, of course, may dispose of several calling lines, such that a number of reports may be received at the same time as well as in rapid succession. The reports may be identifica¬ tion coded, whereby they can immediately be transferred to a computer, which can produce an instant displaying or a later transcription of the different position or time reports from the vehicles. These data may be used for both specific and general surveillance of the time table for the vehicles at different routes or as a basis for a radio call to certain vehicles for special driving instructions in case of unfore¬ seen events.

The invention also relates to a method and a system for communication of position reports from isolated mobile units on the ground, particularly from vehicles in long distance traffic. With the widespread use of mobile phones it is rela¬ tively easy for e.g. a cooling truck driver to phone his base for reporting positions, but more advanced systems have al¬ ready been taken in use, by which the existing navigation satellites are used in the way that a satellite receiver in the vehicle is automatically and continually programmed with the actual spot co-ordinates, while the equipment will then, e.g. at regular intervals, transmit its identification signal with associated spot co-ordinates to the base, this being ar- ranged via the also existing communication satellites. From or at the base the vehicle can be closely followed, entirely without use of the telephone system, and the position of the vehicle can be indicated even during the driver's sleeping breaks. With the use of the relevant, so-called GPS system, the position at least in the open country may be determined with an accuracy of the magnitude 100 meters which, for the dis¬ cussed purpose, is an unnecessarily high accuracy. For vehi¬ cles in long distance traffic it will normally be sufficient to obtain position reports with an accuracy of e.g. plus/mi¬ nus 5-50 km.

With the present invention it has been realised that au¬ tomatic position reports with an accuracy of this latter mag¬ nitude will be obtainable in an attractive manner based on the use of the mobile telephone network, the so-called GSM network, which will here be considered in singular even though in each country there may be more networks of this type. This purpose may be achieved by modest modifications in the existing GSM systems, and it will then be possible to avoid the use of the said satellite systems with associated special equipment. The invention is based on the consideration that the GSM network is subject to operational conditions which necessi¬ tate a relatively close positioning of the stationary trans¬ mitter/receiver antennas, which will not need further de- scription at this place. For the calling of a given mobile phone it would, beforehand, be unrealistic if the calling signal should be transmitted from all the antenna stations, as this would make the total system capacity very low; for this reason, inter alia, the system is laid out such that the transmitter part of the mobile phone will, at each passage into a new antenna zone or by the first use in such a zone, transmit an identification signal which, via the fixed an¬ tenna, is fed to a central computer, in or by which it is re¬ corded that the particular antenna zone has 'taken over¹ the phone number in question, whereafter arriving calls to the number will be channelled solely to the transmitter in this particular antenna zone. Each zone covers an area of rela¬ tively few square kilometres, and in these limited areas it is then possible to operate with a reasonably high calling capacity, as only the calls to the numbers 'operatively pre¬ sent' in the area should be handled.

Basically, this calling issue is impertinent to the in¬ vention, while on the other hand it is very pertinent in that it provides for the said computer to "know" in which antenna area or cell a given mobile phone is present, provided the phone is actuated. For the communication traffic itself it is sufficient that this "knowledge" only appears as an electro¬ nic control information in the phone center, as it has been so far, but it will be appreciated that this information will also hold a very concrete indication of the geographical spot at which the mobile phone is present.

According to the invention it is easily achievable that the said information, e.g. at a service basis, can be drawn from the relevant station, possibly from a regional station via a superior station, and be presented in a more or less plain language as a geographical position indication, e.g. as an indication of co-ordinates for a cell on a special "tele map". Ideally, it will hereby be possible to collect informa¬ tion about the position of a given mobile phone without actu¬ ally calling the phone, as an interrogation call to the sta¬ tion will be sufficient. Thus, even frequent inquiries will not load the mobile phone network itself. An associated ser¬ vice arrangement can be organised in many different ways, e.g. also in that the exchange station automatically trans¬ mits a position fax to the basis subscriber either regularly or each time the supervised unit has moved through one or more antenna zones.

It is not a condition that the supervised unit be a "mobile phone", if only the unit has the equipment required for the automatic signal communication with the GSM stations. On the other hand, it will be natural that the unit is a quite ordinary mobile phone, which should just be held actu¬ ated as long as it is relevant to seek information about its position. The position reporting system will be without any influence whatsoever on the usability of the mobile phone. The system will even enable the driver to make a phone call in order to get information about his own position, should the need arise.

It is expected that the demand for the suggested new in¬ formation service will be relatively high, since it may be connected with a minimum of costs. Commercially, the position reports from trucks and busses - and even from railway carts - can be obtained in a manner cheaper than before, but there may also be a noticeable interest in 'following' the position of private cars, e.g. in connection with family members' con¬ tinental holiday driving. This may involve ethical problems, but not more than the relevant persons can choose to switch off the mobile phone or inform the central station that they wish to keep their number non-accessible for supervision.

In commercial connection it is already known that trans¬ missions via the satellite based GPS network may comprise in- formation other than just the position report, e.g. measure¬ ment data for the conditions in the cooling box of a cooling truck, but it will be appreciated that such data may as well be transmitted via the GSM network. The mobile phone equip- ment in such a truck may adapted so as to have two calling numbers, of which one is the ordinary phone number while the other is a 'silent' call number which will solely actuate an automatic answering system for transmission of condition data via the GSM network, even during sleeping breaks of the driver. It should be mentioned that the invention has a fur¬ ther perspective with respect to vehicles having a fixed mo¬ bile phone installation which is switched on whenever the ig¬ nition is switched on. According to the above this will imply that the location area of the phone and therewith of the ve¬ hicle can easily be detected, whereby stolen cars will be correspondingly easier to find.

To the extent it is desirable to operate with a more ac¬ curate indication of whether a vehicle, which is present in a transition area between two zones, is actually present, is actually present in one or the other zone, it is possible to supplement the system with road mounted markers locally transmitting an electro agnetical signal, which can be re¬ ceived by a detector receiver in cars passing by and thus in a well defined manner provoke the phone unit to transmit its subscriber signal to the new antenna zone. The markers may radiate coded signals, which may be included in the transmit¬ ted identification signal for further detailed position re¬ porting. Even an 'inverted' system can be used, where it is the car that carries a marker for constantly transmitting the subscriber number or some other identification, while, corre¬ spondingly, signal receivers are mounted in the road at stra¬ tegic places. These receivers may then pass the information to the central station, whereby the identification call from the phone could be avoided.

Instead of the said system by which a mobile phone can be localised by way of service from the central station, it is possible to use a modified system pertaining to the type of mobile phones which are equipped with an answering machine. It is common practice that the GSM transmitters transmit an identification signal for the respective antenna zones, viz. with the original aim of enabling driving service operators to be sure about the identity of the zone in which they are present. The telephones can easily be modified such that these signals are fed to the answering machine for current updating, and by an answer tapping call to a given phone it will thus be possible for the base subscriber to collect the latest updated position information by a brief call to the phone, whereby the phone based service with respect to the position indication can be arranged entirely without any ex¬ tra co-operation by the network operator or owner. Only the said modifications of the phones themselves will be required. It has been mentioned that the system may be used for a locating of stolen cars. This can be worked out to a higher or smaller degree, all according to desired degree of secu¬ rity. Thus, for maximum security, a calling and answering module may be arranged in a suitable, unbreakable encapsula- tion with built-in, independent energy supply in the form of a long life battery, and with a suitably unaccessible antenna equipment.

If desired, it will be possible in such a system, irre¬ spective of the degree of security, to arrange for a call to the unit to start a small radio becon in the car, for ena¬ bling a detailed, local locating of the car. Such a beacon may work on an independent frequency, and it should be of a short range only, as the car position will already be known inside an area of few square kilometres or square miles. A call to the unit may for that sake be used to start any rele¬ vant function, e.g. a transmission of a visible or audible signal or a change of certain characteristics of the car.

In the relevant connection it may be desirable to operate with a secret phone number if in normal use it is not desired that the car be locatable.

The drawing shows schematically a bus 2 driving on a road or street 4, in which, at selected places such as at bus stops, there is mounted subterranean electromagnetic markers operating at 50-150 kHz and transmitting respective identifi- cation signals such as the indicated "52" and "53". The mark¬ ers may be designed according to WO 93/21544, preferably as active markers energized by batteries which, even by continu¬ ous operation, may have a lifetime of 30-40 years. The busses are provided with a detector 8 for receiving the marker sig¬ nals and feeding them to a control unit 10. This unit may, optionally, actuate a display or a speaking machine for an¬ nouncing the next bus stop, whilst by the passage of specific markers also other functions may be executed, such as a rele¬ vant change in a ticket slot machine 12 when passing from one fare zone into another. The markers may be coupled with transverse wire loops in the road, whereby it will make no difference whether a bus turns into a bus stop or bypasses it by straight driving.

Moreover, the control unit 10 feeds the signal to a transmitter unit 14, where an identification signal for the bus itself is added, and a calling unit 16 effects a call via the public mobile telephone network to a traffic control cen- ter 18, to which the combined signal is transmitted within few seconds; then the connection is immediately broken.

The traffic control center should have equipment for re¬ ception of several position reports at the same time and/or in rapid succession, which, however, is achievable by known technique in a manner that is simpler than if the station should receive the reports by a direct radio communication. The installation in each individual bus may also be used as an ordinary mobile telephone; it will hardly cause any real disturbance if a few position reportings should be missed, if from time to time the system is used for ordinary phone traf¬ fic.

Claims

C L A I M S :

1. A method of communicating position reports from mobile units equipped with means for detection of received position indicating signals and for wireless transmission of an asso- ciated position report to a traffic center, characterized in that the transmission of the position reports in systems with high unit density and frequent reportings, e.g. in city bus systems, is established via a mobile telephone network of the type adapted to handle many concurrent calls, e.g. the GSM network.

2. A method according to claim 1, whereby in city areas there is used fixed markers for producing the position indi¬ cating signals at predetermined locations.

3. A method according to claim 1, whereby in the open country there is used unit mounted GPS receivers for produc¬ ing the position indicating signals, the associated transmis¬ sion means being actuated by phone calls to the unit or with predetermined timing or by a GPS detected arrival of the unit at a predetermined co-ordinate zone, respectively by the unit passing respective fixed markers.

4. A method according to claim 1, characterized by the c h a n g e that for the determination of the position use is made of the public mobile telephone network's own facilities for determining the geographical antenna area or cell, in which a mobile telephone or phone equipment of a given unit is present, this information being delivered via an associ- ated phone center.

5. A communication and supervision system for use in con¬ nection with the method of claim 1, characterized in being constituted by a public telephone and mobile telephone net- work with a signal receiver as 'receiver subscriber' and a number of position indicating signal transmitters in the driving units as 'calling subscribers'.

6. A system according to claim 5, characterized in that in a given traffic network it comprises fixedly mounted, self-identifying markers at selected places of passage, and that the equipment in the driving units is adapted to be ac¬ tuated for effecting calling and signal transmission by de¬ tection of the local signals from these markers.

7. A system for use with the method according to claim 4, characterized in that it is based on a public mobile tele¬ phone network of the type being cell divided in local antenna areas, this system being modified to the effect that it can automatically or by order provide information as to the iden¬ tity of the antenna cell in which a given mobile telephone is present.