WO1994019890A1

WO1994019890A1 - System and process for data communication via a packet radio network

Info

Publication number: WO1994019890A1
Application number: PCT/EP1994/000309
Authority: WO
Inventors: Ulrich Altvater
Original assignee: Ulrich Altvater
Priority date: 1993-02-18
Filing date: 1994-02-03
Publication date: 1994-09-01
Also published as: DE4304906A1; DE4304906C2

Abstract

A networked computer system (10) in which packet data sets are exchanged via a communication system (12) between at least one main computer (11) and any of a number of user stations (13, 14) has at least one central station (15) in the communication system (12). Here, the central station (15) is in radio communication with the users (13, 14) via a packet radio network (17) transporting the packet data sets. A process for operating this computer network (10) comprises the steps: generation of a packet data set to be exchanged between the main computer (11) and one of the user stations (13, 14); transporting the packet data set via the communication system (12); receiving the packet data set at the central station (15) or at one of the user stations (13, 14); and processing the packet data set, the packet data sets being transported by radio via a packet radio network (17).

Description

SYSTEM AND METHOD FOR DATA COMMUNICATION VIA A PACKET RADIO NETWORK

The present invention relates to a networked computer system in which packet data records are exchanged between at least one main computer and any number of user stations via a communication system, the communication system comprising at least one central station.

The invention further relates to a method for operating a networked computer system which comprises a main computer connected to a number of user stations via a communication system having a central station, the method comprising the steps: Generating a packet data record to be exchanged between the main computer and one of the user stations,

Transporting the packet data record via the communication system,

Receiving the packet data record at the central station or at one of the user stations, and

- Processing the packet data record.

Networked computer systems of this type and the corresponding methods for operating these networked computer systems are known in practice and generally relate to wired computer networks.

In the known wired computer networks, several users can work on so-called front-end processors on a main computer and use the programs available there in interactive mode.

In addition, wired data networks are known, such as the IEC bus system, the ETHERNET system or similar local data networks. As with the wired computer networks, each participant has their own number in the wired data networks, which is used to identify who wants to work with the central computer. The data are not transported in real time here, but are combined into so-called data packets, which are exchanged between the user station and the main computer according to a specific mode. There are, for example, handshake processes or processes in which the data packets are preceded by a destination address. The known wired networks have the disadvantage, among other things, that the system is not very flexible because of the cables required. In addition, repeaters are required, the failure of which leads to the breakdown of the respective network. The same applies if two subscribers with the same number are accidentally connected to this network. In addition, it is disadvantageous that the structure of the network must be known exactly before another user can connect to the network. In general, it is necessary to first expand a type of network infrastructure before the networked computer system can be operated.

All this means that the known networked computer systems are very expensive and can only be set up with a great deal of material and time.

In addition, it is well known to exchange data via radio, with programs running independently of one another on both sides of the radio link. These programs use the radio link for data input or data output, so to speak. The data records are exchanged via radio, but no terminal dialog is possible. The user can e.g. the programs running on the main computer do not change on their own, rather it must "know" exactly the programs running on the host. Changes in the program structure must be made on both sides of the radio link.

Another disadvantage here is that it is an all-round radio system that has no automatic subscriber rights. Each participant must decide whether the data is intended for them. As an example, the police are to be mentioned here, who in the mobile driver's license check request data from the main computer of the driver's license office via PCs in the control vehicle can. However, real dialog operation is not possible here.

On the other hand, it is also known to conduct a dialogue between two PCs via existing cellular networks such as the C-network telephone. But only a point-to-point connection is possible here, the operation of a control center with many users is not intended.

This is also a static static network that a network control center needs to monitor the dialog between users. Each user has a fixed number, whereby the control center monitors from where the respective participant reports. The failure of one of the many required relay stations must be recognized by the control center, which then takes measures to rectify the fault.

Furthermore, when leaving a reception area, a switch must be made to a different frequency, for which purpose fixed relay stations are required to cover an area. As already mentioned above with the hard-wired computer networks, the structure of the network is also predetermined here, so that the desired flexibility is lacking.

However, it is often desirable, for example, to operate such a computer network in an undeveloped area, whereby it should be ensured that a large number of users, the exact location of which is not known on the one hand and on the other hand can change significantly over time, can conduct a real dialog operation with the main computer. In addition to the requirements of the police, fire brigade and army, insurance companies, health insurance companies or, for example, the BfA are also being considered here, who are increasingly turning to providing their customers with mobile emergency vehicles. Here it would be especially in the new Federal states would be desirable if such a mobile vehicle could connect to the corresponding central computer from any point of view.

However, the computer networks described so far do not make all this possible, because they lack flexibility either because of the cabling or because of the real dialog mode.

There are also other radio networks that are used to exchange packet data. Only the AX-25, which is used in the USA for non-commercial data transmission, should be mentioned here. But this radio network also requires that the structure of the network is known. The user must know who can be reached where and over which frequency. Although this radio network is not a standing network, it is still not fault-tolerant, since on the one hand an immediate radio connection is required. Dialogue operation is also not possible with this radio network.

In addition, it would be possible to establish a dialog mode via satellite radio, but this is disproportionately expensive. On the one hand, a geostationary satellite is required and, on the other hand, each user must carry their own satellite antenna with them. It should also be borne in mind here that such satellite systems cannot easily be set up in a shorter time, which is due in particular to the imponderables of space travel.

Finally, it should also be mentioned that it is known to use cluster controllers for data reduction in the transmission of packet data, which, for example, temporarily store a transmitted screen page and only transmit the data that are changed during the session as differential data. These cluster controllers are intended in particular for processing screen masks. Proceeding from this, it is an object of the present invention to further develop the networked computer system of the type mentioned at the outset and the corresponding method for operating this networked computer system in such a way that it can be set up and operated quickly and inexpensively. The system should also be sensitive to the change of location of users and the failure of one or more stations.

With regard to the networked computer system mentioned at the outset, this object is achieved in that the central station is in radio communication with the users via a packet radio network which transports the packet data records.

With regard to the method mentioned at the outset, this object is achieved in that the packet data records are transported by radio over a packet radio network.

The object underlying the invention is completely achieved in this way. Since the communication network is a packet radio network, all the disadvantages associated with the cable networks are eliminated. Users can be mobile, although their exact location does not have to be known. Such a system and such a method are also very easy and inexpensive to put into operation since they do not require any additional infrastructure. Because of the transmitted packet data records, which always only require a very short period of time in order to actually be transported, this is, so to speak, a random time-sharing method by means of which the individual user stations can work on the main computer.

In the networked computer system, it is preferred if the packet radio network comprises intermediate stations between the central station and the user stations, which receive and transmit packet data records. The advantage here is that the user stations do not have to be in direct radio communication with the central station. This once again increases the flexibility of the network, which is particularly noticeable in the creation costs and in the creation time compared to the use of wired computer systems.

It is further preferred if at least some user stations are intermediate stations.

The advantage here is that the costs for the new computer network can be reduced even further. No additional intermediate stations are required, but each user station also serves as an intermediate station. In this way, if an intermediate station fails, its function can e.g. be taken over by other user stations in the vicinity. This increases the speed of troubleshooting.

It is further preferred if at least some user stations are portable.

The advantage here is that it is a dynamic network that can be adapted to the respective requirements with regard to the locations.

It is further preferred if the user stations each comprise a cluster controller, which stores a screen page to be processed and, after the processing, creates a differential data packet from the changed data, which packet is transported over the packet radio network.

In this way, the amount of data to be transported in the packet radio network is significantly reduced, which overall Increased the number of user stations that can communicate with the main computer per unit of time. This means that larger networks can be set up.

It is further preferred if the central station comprises at least one cluster controller.

This has the further advantage that the data sent by the central station can also be differential data, which further increases the capacity of the system.

It is further preferred if each user station comprises an emulation device which simulates a data terminal provided for the main computer, so that a user can process data with and / or on the main computer from the user station.

The advantage here is that inexpensive terminal stations in the user stations can be used to simulate data terminals for high-quality main computers, so that real dialog operation is possible via the virtual connection.

This also leads to an inexpensive system.

It is further preferred if each packet data record comprises a destination address, via which its destination in the packet radio network is determined.

This measure has the advantage that data is transported faster if the destination address is given to the data record, so that the target station can selectively respond to the packet data records intended for it. It is further preferred if the destination address comprises identifiers of the intermediate stations through which the packet data record has to go from the sending location to the destination.

The advantage here is that the packet data record is given its exact path through the packet radio network, so to speak. The destination address can then be used to determine how the packet data record is to be passed on between the intermediate stations. This also leads to a faster transport of the packet data set and thus increases the system capacity, which in turn has an impact on the costs and the speed of installation.

It is further preferred if the destination address additionally comprises a sending location identifier and a destination identifier.

The advantage here is that the address for the data to be returned can be determined directly from the destination address. Extensive buffers for addresses or the like so there is no need.

It is further preferred if the destination address is composed of the sequential sequence of the transmitter identifier, the identifiers of the intermediate stations and the destination identifier, so that the destination address for the transport from the central station to the user station is the destination address for the transport in reverse order from the user station to the central station.

Another advantage here is that the new destination address is obtained, so to speak, by inverting the destination address, which only has to be read from backwards. This can also be seen from the point of view of an inexpensive system, since no complicated algorithms are required to generate the destination address to be sent from the destination address received.

It is further preferred if the central station, the intermediate stations and the user stations are constructed in such a way that the network configures itself.

This measure has the particular advantage that no information about a so-called basic structure of the radio data network has to be provided. The central station and the individual participants in the radio data network automatically and dynamically generate a hierarchy at the logical networking level, so to speak. This also leads not only to an inexpensive computer system, but in particular to a networked computer system that can also be set up quickly in difficult locations.

It is particularly preferred if the central station comprises a device for the network configuration which, when the packet radio network is started up, transmits a configuration address which includes the identifier of the central station and a configuration identifier, and if at least some intermediate stations and some user stations have their own identifier Install in the received configuration address and, if necessary, send the changed configuration address again, the intermediate stations and the user stations deriving their own destination address for addressing the central station from the configuration address received and, if necessary, previously changed by other intermediate stations.

The advantage here is that the dynamic self-configuration of the radio data network takes place only by stringing together the different identifiers of the intermediate stations and user stations and forwarding such configuration addresses. This is not only particularly quick, but also requires very little hardware on the part of the individual stations.

It is further preferred if at least some intermediate stations and some user stations comprise a device for the network configuration which, when switched on for the first time or when the previous connection to the central station is interrupted, send out a search address which contains the identifier of the user station itself, the identifier of the Central station and a configuration identifier, and if the intermediate stations and user stations incorporate their own identifier in the received search address and, if necessary, send out the changed search address again, the central station deriving the new destination address for the user station from the received and possibly previously changed search address and sends them back.

The advantage here is that the search address is used to dynamically generate a new user station or a user station whose connection to the central station has been interrupted to address its own target address. This also applies to mobile user stations, which move away from the reception area of their previous intermediate stations and now "look for" a new intermediate station via which they can reconnect to the central station.

With regard to the new method, it is preferred if the step of transporting the packet data set comprises receiving the packet data set at an intermediate station and forwarding the received packet data set by radio. The advantage here is that the network is easier to configure because of the intermediate stations, the user stations do not have to be in direct radio connection to the central station.

It is further preferred if the step of generating a packet data record comprises generating a destination address which identifies the transport route of the packet data record and providing the packet data record with the destination address.

This has the advantage already discussed above in connection with the computer system, namely that the path of the packet data record through the packet radio network is specified, which significantly reduces the transport time. This increases the capacity of the system.

It is further preferred if the step of processing the packet data record comprises the following steps:

Buffering the packet data set,

Modify some data from the packet record, and

Generation of a packet data record to be returned, which essentially only contains the changed data.

The advantage here is that the data traffic in the packet radio network is significantly reduced, since only the processed data is sent. This increases system capacity and, in the reverse step, reduces costs.

It is further preferred if the step of changing some data includes the step of emulating a data terminal for the host. The advantage here is that high-quality data terminals for mainframes can be simulated on inexpensive terminal stations, so that, despite inexpensive user stations, real dialog operation is possible via the virtual connection.

It is further preferred if the step of changing some data comprises the step of simulating a real terminal dialog between the data terminal and the main computer.

The advantages resulting from this step correspond to those which have already been discussed above in connection with the emulation of the data terminal.

It is further preferred if the step of generating the destination address comprises the steps:

At least once after the packet is switched on or after a failure of the packet radio network, configuration signals are sent from the central station via the packet radio network,

Receiving and changing the configuration signals at an intermediate station,

Forwarding the changed configuration signals,

Receiving the changed configuration signals at the user stations, and

Deriving the destination address specific to the receiving user station in the direction of the central station. These steps show advantageous measures of how the packet radio network dynamically configures itself. Each intermediate station leaves its own identifier in the received configuration signals, so that the previous path of this configuration signal can be traced back from a configuration signal received and forwarded by several intermediate stations. The user station then derives its own destination address from this.

At least once after switching on a new user station or after a partial failure of the packet radio network, transmission of search signals from the relevant user station via the packet radio network,

Receiving and changing the search signals at the intermediate stations,

Forwarding the changed search signals,

Receiving the possibly changed search signals at the central station, and

- Deriving the target address specific to the searching user station from the direction of the central station.

Further advantages result from the description and the attached drawing. It goes without saying that the features and measures mentioned above and still to be described below count not only on their own but also in combination in the scope of the present invention.

An embodiment of the above invention is described below and shown in the accompanying drawing.

Show it:

1 shows a networked computer system which uses the new communication system;

2 shows two examples of destination addresses in the new communication system;

3 shows examples of configuration addresses for configuring the new communication system;

4 shows examples of search addresses as used in the new communication system for partial reconfiguration;

5 shows the block diagram of a user station for the new communication system; and

Fig. 6 shows the block diagram of the central station for the new communication system.

In Fig. 1, 10 is a networked computer system. This computer system 10 comprises a main computer 11, which is connected via a communication system 12 to user stations 13, which are indicated by circles. Some of the User stations 13 are connected to a central station 15 via intermediate stations 14, whereby a communication network 16 is formed.

In the exemplary embodiment shown, the communication network 16 is a packet radio network 17 which uses features of the packet radio network AX-25.

In the exemplary embodiment shown, the main computer 11 is connected to the central station 15 via a satellite communication system 18. For this purpose, a geostationary satellite 21 is provided, which is reached by the main computer 11 via a parabolic antenna 22 and by the central station 15 via a parabolic antenna 23.

However, the satellite communication system 18 is only one example, the main computer 11 can also be connected directly to the central station 15 via a direct connection 24. The satellite communication system 18 is used in particular when the main computer 11 is located, for example, on a different continent than the actual communication system 12.

The central station 15 is connected to a transmitting / receiving antenna 26, via which the central station 15 is in radio communication with the individual user stations 13 and intermediate stations 14. These radio connections are indicated by arrows 27. It can be seen that the individual user stations and intermediate stations are provided with their own identifiers 28, which for the user station located at the bottom right in FIG. 1 is 13 * 2 *. The user station * 2 * is connected via the intermediate stations * 9 * and * 4 * to the central station 15, which has the identifier * 1 *. It should be noted that the intermediate stations 14 are themselves user stations 13. A mobile user station with the identifier * 5 * is designated by 29, which moves to the left in FIG. 1. The radio connection to the intermediate station with the identifier * 6 * is lost. In a manner still to be described, the user station 29 'now establishes a new radio connection 30 to the intermediate station with the identifier * 7 *, from where it communicates with the central station 15 via the intermediate stations * 3 * and * 4 * munited.

It is now assumed that the packet radio network 17 is a rapidly expanding network in which the distances between the individual user stations and intermediate stations are continuously increasing. In order to still maintain the individual radio connections 27, a new intermediate station 32 is sent to the area served by the packet radio network 17. This new intermediate station 32 has the identifier * 12 *.

In a manner to be described in more detail, the new intermediate station 32 now establishes new radio connections 33 and 34 to the intermediate stations with the identifications * 3 * and * 11 *. The user station * 5 * is now connected to the central station 15 via * 7 * and * 3 * and * 12 *. If, due to the further expansion of the packet radio network 17, it is no longer possible to establish a radio connection 27 between the central station 15 and the intermediate station with the identifier * 8 *, this intermediate station can still be connected via the intermediate station * 11 * and the intermediate station * 12 * with the Central station 15 communicate.

In the communication system described so far, it is thus ensured that the communication between the central station 15 and the individual user stations 13 is retained even when the network is expanded or the user stations are very mobile. Such a communication Cation system could be used, for example, by the police, the fire brigade, taxi companies, during rescue or supply operations in undeveloped / impassable areas. It would also be suitable for advisory vehicles from BfA, insurance companies or banks. In all these cases, a dynamically establishing and, so to speak, growing packet radio network would be advantageous if the individual user stations had to access programs on a main computer directly. In the case of banks and insurance companies, this would be advantageous in the context of customer care, for example when calculating credit lines.

In the communication system 12 described so far, packet data sets are exchanged between the user stations

13 and the central station 15. For this purpose, packet data sets are initially generated at the sending station - user station 13 or central station 15 - which are to be transported to a destination station via the packet radio network 17. In addition, the transmitting station generates a destination address which defines not only the destination but also the route of the packet data record through the packet radio network 17. The transmitted packet data record is received by an intermediate station 14, which first checks whether the packet data record is intended for it itself. If this is not the case, a further check is carried out to determine whether the receiving intermediate station lies on the route of the packet data record between the transmitting station and the destination station. If this is the case, the receiving intermediate station transmits

14 the packet data set again, etc. until the packet data set reaches the destination station.

The structure of such a destination address 37 is shown in Fig. 2a. The destination address 37 first comprises an address start identifier 38 and an address identifier 39, which in the Embodiment shown for the sake of simplicity are symbolized by the letters A and E.

The destination address 37 further comprises a transmitter identifier 41, which in the example shown is the identifier * 1 * of the central station 15. A target identifier 42 is also provided, which here is the identifier * 7 * of a user station 13.

Between the transmitter identifier 41 and the destination identifier 42, identifiers 43, 44 are provided for the intermediate stations, via which the packet data record is to be transported from the central station 15 to the user station 13 with the identifier * 7 *. In the example shown, this connection runs via the intermediate stations 14 with the identifiers * 4 * and * 3 *.

The destination address 37 in FIG. 2a thus represents the path of a packet data record from the central station 15 to the user station 13 with the identifier * 7 *.

2b shows a further destination address 46, which describes the reverse route of a packet data record from the user station 13 with the identifier * 7 * to the central station 15 with the identifier * 1 *. It can be seen that the order of the identifiers has only been inverted. When the central station 15 receives such a destination address 46, it can easily derive the destination address 37 from it, via which it can reach the transmitter again.

The way in which these destination addresses are assigned to the individual user stations 13 will now be described with reference to FIG. 3. The packet radio network 17 is not preconfigured, but rather configures itself, so to speak, after it is switched on for the first time. For this purpose, the central station 15 outputs a configuration signal 47, shown schematically in FIG. 3a, which is a configuration address 48.

This configuration address 48 contains the identifier * 1 * of the central station 15 as the transmitter identifier 41. As identifiers for the intermediate stations 43, 44 and as the destination identifier 42, the configuration address 48 includes configuration identifiers 49, which in the exemplary embodiment shown are identified by a 0 for the sake of simplicity.

This configuration address 48 is now transmitted via the packet radio network 17 and received by the user stations 13 / intermediate stations 14 which are within range.

The receiving stations change the configuration address 48 into a changed configuration address 51, whereby they incorporate their own identifier behind the identifier * 1 * of the transmitting station 41 into the configuration address 48. The configuration address 51 from FIG. 3b is thus expanded by one position compared to the configuration address 48.

It goes without saying that each intermediate station 14 now sends out its own changed configuration address 51, which is received by user stations 13 / intermediate stations 14 still further away from the central station 15.

In the example shown in FIG. 3c, the intermediate station 14 with the identifier * 3 * received the configuration address 51 and converted it into a configuration address 53. In addition to this processing of the configuration addresses 48, 51, 53, the receiving user stations 13 / intermediate stations 14 store the configuration addresses 48, 51, 53 and derive their own destination address 46 in the direction of the central station 15 therefrom. For this purpose, they only remove the configuration identifiers 49 from the configuration addresses. As already shown in Fig. 2 explains, the destination address 46 to be used for the respective user station 13 / intermediate station 14 in the direction of the central station 15 results from the reverse order of the identifiers stored in the configuration addresses 48, 51, 53.

In this way, each user station 13 and each intermediate station 14 is supplied with its specific destination address 46 after the packet f network 17 has been switched on, via which it reaches the central station 15. The central station 15 itself does not have to know these destination addresses 46, since the destination addresses are sent along with the packet data sets sent to the central station 15, so that the central station 15 can recognize from whom and by which means the packet data record is reaching it.

It is understood that the method just described is only exemplary, it is not necessary that the identifiers are arranged in the serial order shown. The symbols for address start identifier, address identifier, transmitter identifier, target identifier etc. are also only exemplary. In the context of cryptographed and reduced data, the identifiers can also only be contained indirectly in the destination addresses.

Using Fig. 4 it is now explained how a "lost" user station 13 finds its way back to the central station 15. Here is the one in Fig. 1 used in dashed lines, in which a mobile user station 29 with the identifier * 5 * has moved out of the reception area of its previous intermediate station with the identifier * 6 *. The user station 29 'recognizes the interruption of the connection to the central station 15 by the fact that it no longer receives a response to its transmitted packet data records. After a preselected period of time, the user station 29 'therefore sends out a search signal, designated 54 in FIG. 4a, which represents a search address 55.

This search address 55 contains the identifier * 5 * of the searching user station 29 'as the transmitter identifier 41 and the identifier * 1 * of the central station 15 as the target identifier 42. The identifiers 43, 44 for the intermediate stations are provided with the configuration identifier 49 already discussed.

In the example outlined in FIG. 1, the intermediate station with the identifier * 7 * receives the search address 55 and reads therefrom that the station with the identifier * 5 * is looking for a new connection to the central station 15. For this reason, the intermediate station * 7 * inserts its own destination address in the direction of the central station 15 into the search address 55, so that the new destination address 57 is created, which is shown in FIG. 4b.

The new destination address 57 is now sent to the central station 15, which recognizes on the basis of the configuration identifier 49 that the station with the identifier * 5 * indicates an interrupted connection.

The central station 15 derives the new destination address from the new destination address 57

* A * 1 * 4 * 3 * 7 * 5 * E *

from which it sends the packet data record last transmitted to the station * 5 * again. In this way, the user station 29 'learns its new destination address 57 and is also supplied again with the packet data record last sent. If this packet data record had been lost, the user station 29 can continue to work. However, if this packet data record had still arrived at the user station 29, but its response in the direction of the central station 15 was lost, the user station 29 'in turn will send its last packet data record again in the direction of the central station 15, where it will also arrive because of the now known new destination address.

The method just described is also used when a new user station wants to connect to the packet radio network 17.

In addition, there is the case that the packet radio network 17 expands greatly, so that previous connections between the central station 15 and intermediate stations 14 are lost. This is assumed in FIG. 1 insofar as the radio connection 27 between the central station 15 and the intermediate station with the identifier * 8 * is interrupted. The same applies to the radio connection between the central station 15 and the intermediate station 14 with the identifier * 4 *.

Even now, the mobile user station 29 'will no longer be able to establish a connection to the central station 15. It therefore outputs the search address 55, which is indicated schematically in FIG. 4a.

In this exemplary embodiment, the receiving intermediate stations do not now incorporate their own destination address in the direction of the central station 15 into the received search address 55, since this can no longer be permitted in the meantime. But even if this connection still existed, it could be that there is now a better and / or shorter connection to the central station 15. Therefore, a method is now used which corresponds to the configuration method which has already been discussed in connection with FIG. 3. Each user station 13 / intermediate station 14 namely inserts its own identifier into the search address 55 and sends out a changed search address 59 again, as is indicated in FIG. 4c.

This process is continued, a search address 61 being indicated in FIG. 4d, which is sent out by the intermediate station shown in broken lines in FIG. 1 with the identifier * 12 *.

When the central station 15 receives the search address 61, it derives from it the new destination address 63 shown in FIG. 4e, via which the central station 15 now reaches the user station 29 '.

Due to the method just described, the packet radio network 17 dynamically reconfigures, so to speak, when individual radio connections 27 can no longer be maintained.

In this context, it should also be mentioned that it is not absolutely necessary for each user station 13 / intermediate station 14 of the packet radio network 17 to have its own individual identifier. Since the path of the packet data record through the packet radio network 17 is determined not only by the identifier of the destination station but also by the identifier of the individual intermediate stations 14, several user stations 13 with the same identifier may be present, provided that they are only from the central station 15 via different intermediate stations 14 be reached from. 5, the basic structure of an intermediate station 14 will now be explained in more detail.

Each intermediate station 14, which can also be a user station 13, initially has a transmission / reception antenna 65 which has been omitted in FIG. 1 for the sake of clarity. The transmission / reception antenna 65 is provided with a transmission / reception switch 66 which routes the incoming packet data records via a line 67 to an address evaluator 68. This address evaluator 68 decides whether the received packet data record is intended for the intermediate station 14, should be forwarded by the intermediate station 14 or should be ignored. If the received packet data record is to be forwarded by the intermediate station 14 because it contains either a configuration address or a search address, or because the intermediate station 14 is to serve as an actual intermediate station here, the packet data record is led via a line 69 to a transmission amplifier 71. This transmission amplifier 71 forwards the transmission data via a line 72 to the transmission / reception switch 66, which leads the data to the transmission / reception antenna 65.

It should be noted here that the packet data sets are sent out by means of short transmission pulses, which can be in the range from 20 to 50 ms. This means that the packet radio network 17 does not include any standing radio waves, but that the individual stations 13, 14, 15 only transmit if they actually want to send packet data records. In this way, the individual stations 13, 14, 15 consume little transmission energy. The packet data records include, for example, a certain number of digitized data that are transported according to a fixed pattern. In this way, the packet radio network 17 connects the individual user stations 13 to the central station 15, and so to the main computer 11, using a random time-sharing method. If the received packet data record is intended for the intermediate station 14 itself, the packet data record is forwarded via a line 73 to a cluster controller 74. The cluster controller 74 temporarily stores the data from the packet data record.

Furthermore, it has a device 75 for generating differential data, the purpose of which will be explained in more detail later.

The cluster controller 74 is connected via a two-way line 76 to an emulation device 77 which simulates a data terminal which can be connected to the main computer 11. This is indicated in FIG. 5 by a further two-way line 78, which leads to a data terminal indicated at 79, which is a PC 80 in the example shown. Emulation device 77 and data terminal 79 are combined in a terminal station, indicated at 81, on which the simulated data terminal 79 is generated.

In this way, the user can use the terminal station 81 to conduct a virtual dialog operation with the main computer 11, although the terminal station 81 itself is not a data terminal for the main computer 11. In this way it is e.g. possible to simulate an IBM data terminal 3270 with the help of a simple PC 81, with which one can edit programs on a main computer 11 in real dialog mode.

This processing is carried out in such a way that a screen page of the simulated data terminal 79 is transmitted from the main computer 11 to the user station 13 / intermediate station 14 via one or more packet data records, where it is temporarily stored by the cluster controller 74. In simulated dialog mode, data from the transferred screen page - which can be a screen mask, for example - are now changed. The changed Data is recorded by the previously mentioned device 75 for generating difference data and is forwarded on a line 83 to a cryptography device 84. This cryptography device 84 is used to encrypt and reduce the data to be transmitted as a data packet set. Because of the transmission of differential data and the cryptographing and reduction of these differential data, only a few data are exchanged between the main computer 11 and the terminal station 81, although an entire screen page is shown on the simulated data terminal 79. This method allows relatively little data to be transported over a packet data record, so that the transmission times for a packet data record can be in the range from 20 to 50 ms. In this way, it is possible to connect up to 50 terminal stations 81 to the main computer 11 on the packet radio network 17 on a single frequency, and thereby to guarantee real interactive operation.

The cryptographed and reduced data are forwarded via a line 85 to a device 87 for address generation. This device 87 is also connected via a line 88 to the address evaluator 68, from which it receives the received destination address. The device 87 converts the received destination address according to the method described in connection with FIG. 2 into the new destination address with which the packet data record is routed to the central station 15. The packet data record thus provided with a destination address is led via a line 89 to the transmission amplifier 71, from where it reaches the transmission / reception antenna 65 via the transmission / reception switch 66.

The intermediate station 14 shown further comprises a device 91 for the network configuration, which is connected to the device 87 for address generation via a further two-way line 92. This device 91 for network configuration monitors the Time that passes until the response to a sent packet data record arrives at the intermediate station 14. If a predetermined time period is exceeded here, the device 91 for network configuration causes a search signal 54 to be output, as was explained in connection with FIG. 4 above. The device 91 also stores the own identifier of the intermediate station 14 as well as the identifier of the central station 15.

It should also be mentioned that the configuration addresses or search addresses received from the intermediate station 14 are also loaded into the device 87 for address generation via the connecting line 88. In this case, the device 91 for the network configuration causes the creation of a changed configuration address or a changed search address.

The central station 15, shown schematically in the block diagram in FIG. 6, is constructed in a similar manner to the intermediate station 14. At the transmit / receive antenna 64 there is a send / receive switch 94, which performs similar tasks to the send / receive switch 66. In this way, a received packet data record arrives in an address evaluator 95, which also serves as a buffer and a kind of multiplexer Function takes over. In other words, the address evaluator 95 ensures that the various terminal stations 81 access the main computer 11 from the user stations 13 using the time sharing method and are operated by it. For this purpose, the address evaluator 95 leads with its output line 96 to a cluster controller 97, which essentially corresponds to the cluster controller 74 of the intermediate station 14. In interactive mode via the connecting line 24 to the main computer 11, the data which the cluster controller 97 temporarily stores are changed. The changed dates are fed as difference data via an output line 98 into a cryptography device 99, which performs the same tasks as the cryptography device 84 from FIG. 5.

The cryptographed and reduced data are transmitted via an output line 101 to a device 102 which, like the address evaluator 95, performs a type of multiplexer / demultiplexer function.

The differential data set to be transmitted arrives via a line 103 into a device 104 for address generation, which in turn corresponds to device 87. The device 104 for generating the address is also loaded via a line 105 with the destination address via which the associated reference data set had reached the central station 15. This destination address also reaches device 102, where it ensures synchronization of the time sharing.

In the device 104, the packet data record to be transmitted is supplied with the correct destination address and is then led via a line 106 to a transmission amplifier 107, which is connected to the transmission / reception switch 94 via its output line 108.

The central station 15 also has a device 109 for the network configuration, which is connected to the device 104 for address generation via a connecting line 110.

Device 109 outputs the configuration signal that was discussed in connection with FIG. 3.

Finally, it should be mentioned that the communication system described so far is an automatically building network includes, whose hierarchy adjusts itself so to speak and dynamically adapts to the changing circumstances of the network. This packet radio network can easily be expanded to include additional users, is fault-tolerant to the failure of intermediate stations, and can be established in an area whose spatial extent cannot be predicted. No network control center is required, since each user also acts as an intermediate station and the network configures itself. If the network becomes too large, a second central station can be set up, which has its own identifier and sets up its own radio data network, which can overlap in whole or in part with that of the first central station.

With regard to the networked computer system described, the use of this communication system has the advantage that a real terminal dialog can be carried out on a frequency of up to 50 terminals in a random time-sharing process via a virtual connection to the main computer. Since reduced and compressed packet data sets are transmitted, the individual stations in the radio data network 17 each only have to go on the air very briefly, so that little transmission energy is required.

Claims

Networked computer system in which packet data records are exchanged between at least one main computer (11) and any number of user stations (13, 14) via a communication system (12), the communication system (12) comprising at least one central station (15), characterized in that the central station (15) is connected to the users (13, 14) via a packet radio network (17) which transports the packet data records.

A networked computer system according to claim 1, characterized in that the packet radio network (17) comprises intermediate stations (14) between the central station (15) and the user stations (13), the intermediate stations (14) receiving and transmitting the packet data records.

Networked computer system according to claim 1 or 2, characterized in that at least some of the user stations (13) are intermediate stations (14).

Networked computer system according to one of claims 1 to 3, characterized in that at least some user stations (13, 29) can be moved.

Networked computer system according to one of Claims 1 to 4, characterized in that the user stations (13, 14) each comprise a cluster controller (74) which stores a screen page to be processed and, after processing, creates a differential data packet from the changed data which is transmitted via the Packet radio network (17) is transported.

6. A networked computer system according to one of claims 1 to 5, characterized in that the central station (15) comprises at least one cluster controller (97) which stores a screen page to be processed and, after processing, creates a differential data packet from the changed data, which via the Packet radio network (17) is transported.

7. Networked computer system according to one of claims 1 to 6, characterized in that each user station (13, 14) comprises an emulation device (77) which simulates a data terminal (79) provided for the main computer (11), so that a user of the user station (13, 14) can process data with and / or on the main computer (11).

8. Networked computer system according to one of claims 1 to 7, characterized in that each packet data set comprises a destination address (37, 46), via which its destination (13, 14, 15) in the packet radio network (17) is fixed.

9. Networked computer system according to claim 8, characterized gekenn¬ characterized in that the destination address (37, 46) comprises the identifiers of the intermediate stations (14), which the packet data set from the sending location (13, 14, 15) to the destination (13, 14, 15th ) must go through.

10. A networked computer system according to claim 9, characterized gekenn¬ characterized in that the destination address (37, 46) additionally comprises a sending location identifier (41) and a destination identifier (42).

11. Networked computer system according to claim 10, characterized gekenn¬ characterized in that the target address (37, 46) from the sequential sequence of the transmitter identifier (41), the identifiers (43, 44) of the intermediate stations (14) and the target identifier (42) composed so that the destination address (37) for the transport from the central station (15) to the

User station (13) in reverse order reproduces the destination address (46) for the transport from the user station (13) to the central station (15).

12. Networked computer system according to one of claims 1 to 11, characterized in that the central station (15), the intermediate stations (14) and the user stations (13) are constructed such that the packet radio network (17) configures itself.

13. Networked computer system according to claim 12, characterized gekenn¬ characterized in that the central station (15) comprises a device (109) for the network configuration, which sends a configuration address (48) when the packet radio network (17) is started, which identifies the identifier of the Central station (15) and a configuration identifier (49), and that at least some intermediate stations (14) and some user stations (13) incorporate their own identifier in the received configuration address (48), and the changed configuration address (51, 53) if necessary transmit again, the intermediate stations (14) and the user stations (13) deriving their own destination address (46) for addressing the central station (15) from the configuration address (51, 53) received and possibly previously changed by other intermediate stations. 14. Networked computer system according to Claim 12 or 13, characterized in that at least some intermediate stations (14) and some user stations (13) comprise a device (91) for the network configuration which is activated when the relevant station (13, 14) is switched on for the first time or when Interruption of the previous connection to the central station (15) transmits a search address (55) which identifies the station (13,

14) itself, the identifier of the central station (15) and a configuration identifier (49), and that the intermediate stations (14) incorporate their own identifier in the received search address (55) and the changed search address (59, 61) if necessary. Send out again, the central station (15) from the received and possibly. previously changed search address (61) derives the new destination address (37) for the searching user station (13) or the searching intermediate station (14) and sends it back.

15. Method for operating a networked computer system

(10), which has a main computer which is connected via a central station (15) to the communication system (12) with a number of user stations (13, 14)

(11), the method comprising the steps of:

Generating a packet data record to be exchanged between the main computer (11) and one of the user stations (13, 14),

- Transporting the packet data record over the communication system (12),

Receiving the packet data set at the central station (15) or at one of the user stations (13, 14), and Processing of the packet data record,

characterized in that the packet data sets are transported by radio over a packet radio network (17).

16. The method according to claim 15, characterized in that the step of transporting the packet data set comprises receiving the packet data set at an intermediate station (14) and transmitting the received packet data set by radio.

17. The method according to claim 15 or 16, characterized in that the step of generating a packet data record comprises generating a destination address (37, 46) characterizing the transport route of the packet data record and providing the packet data record with the destination address (37, 46).

18. The method according to any one of claims 15 to 17, characterized in that the step of processing the packet data set comprises the steps:

Buffering the packet data set,

Modify some data from the packet record, and

19. The method according to claim 18, characterized in that the step of changing some data comprises the step of emulating a data terminal (79) for the main computer (11).

20. The method according to claim 19, characterized in that the step of changing some data comprises the further step of simulating a real terminal dialog between the data terminal (79) and the main computer (11).

21. The method according to any one of claims 17 to 20, characterized in that the step of generating the destination address (37, 46) comprises the steps:

- At least once after switching on the packet radio network (17) or after a failure of the packet radio network (17), configuration signals (47) are sent from the central station via the packet radio network (17),

- receiving and changing the configuration signals at the intermediate stations (14),

Forwarding the changed configuration signals (47),

Receiving the possibly changed configuration signals (47) at the user stations (13), and

- Deriving the destination address (46) specific to the receiving user station (13) in the direction of the central station (15).

22. The method according to any one of claims 17 to 21, characterized in that the step of generating the destination address (37, 46) comprises the steps: At least once after switching on a new user station (13, 29) or after a partial failure of the packet radio network, transmission of search signals (54) from the relevant user station (13, 29) via the packet radio network (17),

Receiving and changing the search signals (54) at the intermediate stations (14),

Forwarding the changed search signals (54),

Receiving the possibly changed search signals (54) at the central station (15), and

Deriving the destination address (37) specific to the searching user station (13, 29) from the direction of the central station (15).