Mobile radio system.

The invention relates to a mobile radio system for making telephone calls to and from vehicles via radio links between vehicle-mounted mobile devices and stationary radio concentrators, where the detected by the system geographical area divided into a plurality of partially overlapping radio cells and each radio cell is permanently assigned to a radio concentrator and wherein each locating devices are provided in order to identify the vehicle location corresponding radio cell and to assign the mobile station to the radio cell corresponding to this radio concentrator.

The system of radio cells in cellular systems is used to make the limited available radio channels usable many times. The transmission power of mobile devices in the vehicles and the radio concentrators is chosen so low that they can be received substantially within a radio cell. In a certain spatial distance then the same channels can be used again. Should be increased to the mobile radio system, the total number of participants, without additional radio frequencies are available, so the number of Funkzellän has increased and their size can be reduced so that, at the same time, the transmission power is reduced.

One problem with mobile radio systems is the allocation of vehicle positions to the radio cells competent or the associated radio concentrators. In herkömmli chen systems (IEEE Transactions on Vehicular Technology, Febr. 1977, pages 43 to 46) is carried out for this purpose a Vehicle tracking using field strength measurement or by means of transit-time measurement. In each case, signals between the radio concentrators and located in their range vehicles are exchanged, wherein it is determined by determining the field strength or by measuring the transit times which radio concentrator the vehicle is closest or has the best reception conditions. Such measuring methods are indeed useful as long as the radio cells have a relatively large extent, so that signal distortions, such as runtime distortions due to reflections from buildings and the like., Are not significant. However where the diameter of the radio cells for the above reasons be reduced to one or a few kilometers, so the demands on the radio location. In built up area improves the accuracy due to the already mentioned disturbed propagation of radio waves is in principle limited because tall buildings shield the direct radio transmission. A radio contact will thereby concluded only indirectly by numerous reflections, these detours certainly can be a few kilometers, and thus can be of the order of the radio cell diameter. If this occurs, then the tracking error of the system are no longer acceptable.

The object of the invention is to provide a mobile radio system of the type mentioned, in which the locating of vehicles and thus their assignment to specific radio cell and radio concentrators is possible in a simple manner and with high accuracy, so that the reliability of the system is increased.

This object is achieved in that, provided tion unit in the vehicles each a navigation which when passing stationary beacon receiving data on their location and update them during the journey by an on-board dead reckoning means that the respectively determined in the GPS location data to transmitted mobile radio device of the vehicle and are evaluated by comparison with the local data of the individual radio cells to determine the associated radio cell or the associated radio concentrator.

Thus, the invention uses a bakengestützen dead reckoning system with which a highly accurate positioning of vehicles is constantly carried out during the journey. The construction of such a tracking system solely as a complement for the mobile radio system might be relatively costly. The cost of such a positioning in the mobile system, but then minimal if a navigation system GE of. signposted nature as part of a traffic management system is present in any case for private transport, with the infrastructure for the beacons within the traffic control system is constructed and the individual vehicles are equipped with a navigation device. Such a route guidance system is described for example in the EP Patents 00 21 060 and 00 25 193rd

If such a traffic management system for the area of the mobile radio system coverage introduced to effective traffic management, better use of traffic areas, a sensor. achieve effect of fuel consumption, the environmental impact and the risk of accidents, so it is expected that between 25% and 50% of all vehicles are equipped with the facilities for the use of the control system. Experience has shown that then to be expected that in any event with high expectations to equip their vehicles with driver facilities for this system and thus have a navigation device of the above type. So you can but assume that all Anwär ter on a car phone, which can be attributed almost certainly this group that have the appropriate facilities for dead reckoning. If we make now so that position determination according to the invention the mobile radio system used by the vehicle-mounted mobile devices accept the determined position coordinates can be omitted, the conventional position determination in the radio concentrators, whereby the mobile system simplifies, is increased in its reliability and reduced prices in its infrastructure.

In a simple embodiment of the invention determined by the navigation device in the vehicle position data are simply transferred to the mobile device and transferred by it to the accessible radio concentrators, the allocation to the radio cells is calculated in the radio concentrators. Is even more advantageous, however, if the mobile device of the vehicle, the data of the radio cells are stored by location and dimensions, so that the mobile device can calculate independently by comparing the radio cell data with the position data of the vehicle, in which network cell they are. You can then switch to the appropriate radio channel and or on-in the respective radio concentrators. sign out. The storage of the radio cells of data is carried out depending on the form of these radio cells, for example by storing the coordinates of the vertices of rectangles, or by storing the center coordinates and the radius of circles.

In general, however, would require too much memory to store the data for all radio cells of the entire system area in each mobile device. It is therefore advantageous if the respective beacons when passing a vehicle to transfer not only the location coordinates and the position coordinates of the radio cells of a certain environment area with so that they can be respectively supplied to the mobile device and stored therein.

Unless the driver has entered for the purpose of individual traffic control his destination in a destination memory of the vehicle, this information can also be exploited for the mobile radio system. Based on the knowledge of the recommended route to the radio concentrators concerned, a change in an adjacent radio cell are already preannounced. In this way it is possible to perform in overlapping zones a phone conversation from the start on the radio cell, in which enters the vehicle. In this way, the need to make a channel change during a call, are present only rarely in the radio cells of small dimensions.

The invention is explained in detail on embodiments with reference to the drawing. It shows<ul><li>FIG. 1 illustrates a vehicle in a schematic representation with a beacon and a radio concentrator and the facilities for the assignment of positioning and mobile communications system shown in a block diagram,</li><li>Fig. 2 is a schematic Darstellunge several radio cells with radio concentrators and associated vehicles.</li></ul>

FIG. 1 shows a schematic representation of the device-related embodiment of the inventive combination of a mobile radio system with a navigation system. A vehicle F includes a mobile station MB, which with a stationary radio concentrator FuKo which is in transmission range, occurs via an antenna AT in a known manner in connection and in need builds a Femsprechverbindung on this radio concentrator. To determine the allocation of the vehicle to a particular cell and to an associated radio concentrator, the mobile station MB is connected to a navigation device N which constantly detects the current location in the vehicle. To this end, the vehicle also contains an integrated navigation device KON, soft processes the measured values ​​of a magnetic field probe MS and a Wheel Pulse Transducer RIG and gives it each calculated path vector to the navigation device. To avoid error accumulation of dead reckoning system, are distributed over the road network, preferably placed at major intersections, beacons BK each emitting, among other precise location messages with their own location coordinates so that each passing vehicle, these coordinates and to correct its navigation device N exploit can.

Information transfer between the beacons BK and vehicles F occurs z. B. over infrared devices, wherein in each beacon respectively an infrared transmitter SB and an infrared receiver EB, in the individual vehicles each an infrared transmitter SF and an infrared receiver EF arranged. The infrared device of beacons can be arranged for example to signal masts SM street intersections in addition to the traffic signal heads VSG. The beacon BK communicates via a line L with the control center in conjunction LZ from where it gets even guidance information. Since the beacon BK as well as the navigation device N of the vehicle part of a navigation session or. are control system for vehicles, are not only the aforementioned location information, but additional guidance information exchanged between the respective beacon BK and each passing vehicle F, for example, an input in a target storage ZSp the vehicle desired destination of the vehicle by the vehicle F to the beacon BK and direction recommendations and other information from the beacon to the vehicle BK F. In the operating unit B of the vehicle in addition to the already mentioned target storage ZSp an input keyboard TA and a turn signal RA provided. However, this is not the subject of the present application, so that is then no further discussion.

The respectively calculated in the navigation device N of the vehicle current location is preferably supplied in the form of coordinates, the mobile station MB and there compared in a comparison device VGL with radio cell data stored, for example, in a radio cell memory FSp. According to the comparison result finds the mobile device, which network cell the vehicle is and what radio concentrator accordingly a desired telephone connection should be established. The data stored in the radio cell memory FSp data for different radio cells are also respectively transmitted when passing a beacon BK of this to the vehicle and transmitted to the mobile station MB for updating the memory FSp. It is sufficient to be if each of the radio cells in the surrounding area of ​​the beacon transmitted and stored data.

If a desired destination is entered in the destination memory ZSp of the vehicle, can this or a request aiming appropriate, received from the beacon Leitempfehlung also be communicated to the mobile device. Because of such objective data, mobile station MB can already announce the radio concentrator switching from one radio cell to another. On the other hand, it is possible already to build a radio-telephone link to take account of the target data and two eligible radio concentrators select those in which Be rich or in its radio cell, the vehicle is located in the further course.

In Fig. 2 schematically different radio cells Z1 are shown from Zn, whose size z. B. the population density or the density of traffic is adapted. They are respectively represented by their center coordinates (x ,; y,), (_X2; _Y2) To (x_n; y_" and their radii r ,, r₂ to r_ndescribed. Each radio cell is assigned to a radio concentrator, z. B. the radio concentrator FuKol the radio cell Z1. The beacon BK transmits this cell names and coordinates and their own coordinates - (x_B; yε) to all passing vehicles, in Fig. 2 z. B. F1 to the vehicle. The navigation device N (Fig. 1) bestimt during further driving continuously the position of the respective vehicle and notify the mobile station MB with. This can determine by simple calculation, in which radio cell the vehicle is located.

The vehicle F2 moves in the example in Fig. 2 in an overlapping zone of the radio cells Z1 and Z3 in the direction to the center of Z3. It therefore makes sense to settle an incipient conversation from the outset on the radio cell Z3 and their radio concentrator FuKo because not then have to be once switched to another channel.

The transfer of the radio circuit coordinates on beacons is also gaining greater freedom of movement with respect to the site of the radio concentrator antennas. When locating the vehicles on transit time measurement they must be located in the center of their radio cells. There, however, an assembly may encounter difficulties, for example because no suitable building or premises available. If the position determination, however, according to the invention via beacons, the radio concentrators can be arranged eccentrically in the Funkzel len, as shown in the radio cell Z2 on the example of the radio concentrator FuKo2. Even a supply of several radio cells of a single authority, for example the Rich antennas is possible. One such example is the radio concentrator FuKo3-4-n.