Method for authorizing access to a communication system

The invention relates to a method for imparting Access authorization for a communication system, in particular a radio transmission system with at least one central device and a Plurality of independent subscriber stations, wherein a subscriber station by sending a an access request to the central facility issuing access authorization expected.

From DE-OS 31 33 347.8 a method for accessing is on Transmission channels of a communication system with at least one central device, having at least a duplex transmission channel and a plurality mutually independent subscriber stations, in which each Subscriber station for a multiple access method on can access the duplex transmission channel, known.

The messaging system described in this document is a system for transmission of messages via radio links with stationary radio stations and mobile Subscriber stations. Here, each stationary radio station (Central device), a set of duplex transmission channels assigned. One (the organization channel) is used to transmit control information for the are operation and the other (the voice channels) used for voice transmission.

The following is the first channel of the organization channel, on which the subscriber stations their tax information transmitted to the central facility, as a forward channel, the second channel on which the central facility their Control information to the subscriber stations transmits, referred to as return channel. Return channel of Organization channel are divided into time slots, wherein the time slots for better utilization of the Hinkanals in turn divided into a number of Rufschlitzen can be. To initiate the construction of a conversation with a subscriber of a telephone network or another subscriber station, which from a Subscriber station starts, the subscriber station selects randomly from one of these paging slots. To the usability However, to increase the Hinkanales, it sends not their full identification, whose signal length more would require paging slots, but an all Subscriber stations the same signaling abbreviation.

This signaling Abbreviation divides the central Device with that a request for setting up a call by a subscriber station is. Are within a time slot by the central device received several signaling Abbreviation, so is the central facility of these subscriber stations selected, said subscriber station by the number of Rufschlitzes in which they sent had clearly determinable. Then sends the central unit a request to the subscriber station to identify themselves. In this call contain the number of Rufschlitzes in which this subscriber station sent your signaling Abbreviation would have. This is the danger of destruction access and thus one time share, for the forward channel of Organization channel is only slightly used, by the Shortening the duration of the individual access requests reduced.

Each subscriber station in a paging slot Signaling Abbreviation had sent and after a predetermined period of time not to broadcast their is prompted complete identification, has its Access request by retransmission of their signaling short character to repeat.

The return channel of the aforementioned Font described duplex transmission channel is two different frequencies formed. However, duplex transmission channels can also by time slots are formed, wherein each channel, a time slot and is assigned several time slots in a time frame are summarized. The time frame can both only in a single frequency location or at several prime locations be organized.

Object of the present invention is a method to improve the aforementioned type so that reduced access times and resilience of the Organization channel can be increased.

This object is achieved in a method of the mentioned type in that the subscriber station their access request repeatedly, once it is established, that another subscriber station that its access request has posted later, an access authorization receives.

The dependent claim 2 is a refinement of the Invention to, in which the subscriber stations in different Priority classes are classified.

The dependent claims 3 and 4 give a configuration of the procedure, in which, by the way of Access Permissions load control within the central device is possible.

Further embodiments of the invention are vorteihafte Subject matter of further dependent claims.

Embodiments describe the invention. Based on be in the figures shown drawing more details described and explained.

Shown in schematic representation:<dl tsize="8"><dt>Fig. 1</dt><dd>a period of organization channel.</dd><dt>FIG. 2</dt><dd>a block diagram of a mobile station.</dd><dt>Fig. 3</dt><dd>is a further block diagram of a mobile station.</dd><dt>Fig. 4</dt><dd>is a further block diagram of a mobile station.</dd></dl>

A preferred embodiment of a communication system with at least one central facility and a plurality of mutually independent subscriber stations, wherein a subscriber station after sending out an access request is one of the central facility expected to be granted access permission, is a Radiotelephone system with spatially variable subscriber stations. However, the application of the invention is not limited to Such restricted radiotelephone system, but is the For even when Satelittenkommunikationssystemen or even with networked computers for a "Local Area Network "applicable.

With the stated radiotelephone system move in Radio receiving range of a central facility, which in following is referred to as a base station, a plurality mutually independent subscriber stations, hereinafter referred to as mobile stations. Radio reception area the base station is, for example, Radio cell of a cellular car phone network, such as the planned pan-D network. Radio communication between the mobile stations and the base station found on a limited number of duplex transmission channels instead of. One of these duplex transmission channels is designed as a control channel.

Fig. 1 shows a time detail the dialogue on the control channel. The control channel is in Timeslots divided. Line a in Fig. 1 shows the forward channel of the control channel on which the mobile stations Send and line b in Fig. 1 shows the return channel, on which the base station transmits. All mobile stations, which want to carry out a call origination, are initially located in the so-called ringing phase, in which it an access request on the forward channel send.

Since several access requests simultaneously transmitted these access requests would cover and so enforce more than one access request per time slot could, each time slot is divided into eight call slots. Means transmitted from the base station synchronization signals is numbered sequentially each paging slot. Based on these Rufschlitznummer each paging slot both the base station and for all mobile stations Clearly distinguishable. As the number of Rufschlitznummern with time is too large, in the embodiment after reaching a definable Maximum value, the numbering of the next Rufschlitzes again started with the number zero.

The access request of a mobile station consists of a Signaling Abbreviation, whose signal length for transmission only a paging slot required. Where paging slot each mobile station transmits is determined by a in the Mobile station arranged randomly determined. In this way, there is a high probability, that with several access requests some access requests reach the base stations without conflict. In A line of FIG. 1 sends the paging slot no. 42, a mobile station A, in the paging slot no. 46, a mobile station D and the paging slot no. 47, a mobile station E. In the paging slot No. 44 have two mobile stations B and C at the same time an access request sent. Go both access requests with approximately the same field strength at the A base station, the result is an access conflict, in Time slot no. 44 marked with X. be access conflicts ignored by the base station.

Fig. 2 shows a block diagram of a receiving part of a 1 and a transmitting section 2, and an evaluation device 3 built mobile station. By the Evaluation 3 arranged sequencer 31 is the transmission of the access request triggered. one in Receiving part 1 arranged and not shown synchronizer delivers at the output RSN of the receiving part 1, the current from the base station Sub Rufschlitznummer. With the transmission of the access request is this current Rufschlitznummer in a register 32 stored. In this way, remembers each mobile station which Rufschlitznummer in which it has sent its access request. So does the register 32 of the mobile station A, the Rufschlitznummer 42 Register of the mobile stations B and C, the Rufschlitznummern 44 and so on.

After sending the access request, the mobile stations by the flow controller 31 from the ringing phase put in a waiting phase. expected in the waiting phase it is one of the base station sent to them access permission, with the allotted them a voice channel is, where they can continue the call setup.

The data received from the base station conflict-free access requests, marked in row A of Figure 1 with * are processed in the order they arrive. Since the received signaling abbreviation no contains information about the subscriber station the signaling abbreviation has sent serves the the time of receipt of a signaling short character each issued by the Baisstation Rufschlitznummer as a distinguishing tool between the calling Mobile stations. Each access request is in the base station in a file with this Rufschlitznummer managed.

Since this stored Rufschlitznummer simultaneously Education ranking, in which the mobile stations their Access permissions get assigned; be these managed by the base station Rufschlitznummern hereinafter referred to as authorization numbers.

The base station is now in the order of arrival the conflict-free access requests successively a Access Permissions For example, at the mobile stations A, D and E sent. For this purpose, each access authorization the each access request authorization assigned number. In time slot, which the paging slot no. 48 starts, the base station therefore sends an access authorization For example, what the authorization number 42 and the includes channel number XX a free speech channel.

The Rufschlitznummer contained in the access authorization is located by all in the waiting phase mobile stations A, B, C, D and E are evaluated and further to a Output BN of the receiving part 1 passed. This output BN is connected to a first input of a comparator 33.. A second input of the comparator 33 is connected to the output of the register 32nd The comparator 33 has two outputs, which the Sequencer 31 are connected. If the two of its output accompanying numerical values ​​correspond, are it emits a signal at its first output. exceeds the numerical value at its first input the numerical value, which is applied to its second input, it is a Signal to its second output.

In this way all compare themselves in the waiting phase located mobile stations A, B, C, D and E with the Access authorization received authorization number their respective data stored in the register 32 Rufschlitznummer. But the mobile station A is a match these two numbers determined. By the signal at first output of the comparator 33 is the sequence control 31 ordered to leave the waiting period and the Call setup with the base station on which you in Access authorization assigned speech channel XX further continue.

All mobile stations receive the access permissions, containing an authorization number which is lower than the stored Rufschlitznummer remain in the waiting phase. These are the mobile stations B, C, D and E. During the waiting period, they do not send a new Access desire. In this way, the control channel by the mobile stations located in the waiting phase Not used, not even if they caused further by a large number of access requests Mobile stations will have to wait a long time. this has the advantage that the load of the control channel so just in the times with many access requests can be kept low as possible and thus less Access collisions of calling mobile stations are expected.

The next in the management of the base station received Access requests authorization assigned number has the numerical value of 46. The next access authorization, with which from the base station in the time slot which the paging slot no. 56 starts, is sent, therefore contains the authorization number 46 and the channel number XY one free speech channel. The mobile station D know then, that they their call setup on the access authorization specified speech channel XY continue allowed.

By comparing the number 46 with the permission own stored Rufschlitznummer 44 provide the mobile stations that they passed over B and C, are. This is for them is characterized in that its access request from the base station could not be received. Only now leave both mobile stations B and C by the output of the second output of the comparator 33 their waiting period and by the sequencer 31 is reset again in the ringing phase. In a sending the following call slots again an access request out. Because of the flow control Send arranged random mobile stations B and C likely then but in different Rufschlitzen, for example in the Rufschlitzen No. 67 and no. 70, and thus avoid, at least among themselves, an access conflict.

In this way it is prevented that mobile stations whose Access requests do not reach the base station could, this may find themselves and again a Access request send. Send advantageously However, only those mobile stations, regardless of how long they have to wait for an access authorization, repeated access request made when the access request actually does not reach the base station Has. Furthermore, the access authorization for control must the mobile stations located in the waiting phase no contain additional information so that the occupancy of the return channel is not thereby increased. The load of Hinkanales and the number of access collisions is however reduced.

With the described arrangement is a so-called load control of the radio telephone network possible. Meeting at the Base station many access requests from mobile stations a so causes the base station that the transmission of the Access permissions is delayed without to is concerned that the present in the waiting phase Mobile stations by renewed access requests to the forward channel tamp.

In a further, not shown embodiment of the Invention is in each mobile station an Timer circuit arranged. This timer circuit is started with the transmission of an access request. Receives the mobile station due to its access request a specific authorization for them to access, as is the Timer circuit reset. Runs the means of Timer circuit predetermined time within the Waiting phase, so the mobile station is determined by the Timer circuit is reset again in the ringing phase. In this way it is ensured that the mobile stations, whose access request has been lost and this can not identify, because in the meantime, no Access permissions are set, after a predetermined waiting period once an access request send. The predeterminable period of time, this timer circuit depends on the intended load on the organization channel. It lies in the embodiment in Order of ten seconds.

In a further embodiment of the invention sends the Base station at longer intervals to give access with the instantaneous Rufschlitznummer out. Since this access level no access request is headed, it is a pseudo access authorization designated. In this way it is ensured that even in times in which only a small number or no access requests are received, the mobile stations, their access request is not received could, with this pseudo access authorization with an authorization number obtained by means of which they lost the can recognize their access request and then a Send new access request. Sending out a such pseudo access authorization has the advantage that the circuit complexity for the in each mobile station can be dispensed arranged timer circuit and the detection a Rufverlustes alone with the already described Circuitry for detecting an access authorization is possible.

The access order of the mobile stations of the described Radiotelephone system is based on an absolute Numbering of paging slots over from the base station transmitted, for example, in synchronization signals Rufschlitznummern. As absolute numbering but can also, for example, the system time of the cellular phone system be used.

In the circuit arrangement described in the following instead of an absolute numbering relative Numbering used. For relative numbering of Access request is the time interval between the access request and the received access permission or to equivalent size, for example, Number of intervening time slots used.

In the mobile station shown in FIG. 3 generates a contained in the synchronization part of the receiving part 1 Clock circuit at the beginning of a Rufschlitzes an output pulse which output on the RST of the receiving member 1 applied to a counter 34 is. The clock generator circuit is synchronized with the base station. Such clock circuit is usually already exists in each mobile station to the time-synchronous transmission, for example, the access request, to ensure. A reset input R of the counter 34 is connected to the sequencer 31, which in function and construction of the sequence controller shown in Fig. 2 corresponding, respectively. By the reset input the counter 34 pending signal of the sequencer the counter output of the counter 34 remains at zero, to the sequencer 31 sent an access request Has. Now increases at each clock pulse on the counter input the count of the counter 34 by one. The counter output of the counter 34 is connected to the first input of a Comparator 33 is connected. By means of the receiving part 1 evaluation contained is the second input the comparator 33 via the output BN of the receiving part 1 received in the respective access authorization Authorization number included supplied. The comparator 33 generates two output signals. At its first output generates an output signal when the count of the counter 34 and the authorization number to match. is from its second output, an output signal generated when the count of the counter 34 is greater than the received authorization number. These two signals are of the sequencer 31 supplied and cause the state changes already described like ringing phase, waiting phase, etc .. When sending an access request the counter 34 starts counting the elapsed Rufzeitschlitze. When sending a Access authorization records the base station in the access authorization the number of paging slots, which between triggering the reception of this access Access request and the transmission of the access authorization lies. For this purpose, in the embodiment in the base station simultaneously with the storage of the access request override the current Rufschlitznummer stored. When sending out the access authorization is the number of past paging slots from the difference the now current Rufschlitznummer and stored Rufschlitznummer determined.

The relative numbering has told the absolute Numbering the advantage that the complexity in the mobile station can be reduced, since from the received synchronization signals derived only Rufschlitztaktsignal must be, which already is for synchronization the call slots is needed. This need the synchronization signals not Rufschlitznummer contain. This leads to a reduction of the Synchronization signals to be transmitted as well as to a reduction in overall system costs.

Because of signal processing times, the transmission can the access permission to some timeslots move. The resulting necessary correction to the number the call slots, which between the calculation of the number the paging slots and the transmission of the access authorization is, must be taken into account. This is most easily characterized in that when calculating the number of paging slots in the base station a corresponding correction value is added.

With the stated radiotelephone system, all mobile stations of equal rank. The access permissions therefore in the order of arrival the access requests issued.

In a further embodiment of the invention the Mobile stations divided into different priority classes. A mobile station with a higher priority must their access rights from a mobile station with a receive lower priority. However, it is also possible that the priority of a mobile station access request be different access request can. For example, each mobile station, regardless upon which priority class it belongs, for a Emergency claim the highest priority.

Fig. 4 shows a block diagram of a mobile station, wherein which such priority classes are considered can. The embodiment shown in Fig. 4 goes from the embodiment shown in Fig. 2 and is additionally provided with switching means which are required to take account of the priority classes.

For this purpose, each mobile station stores in addition to storing the Rufschlitznummer in the register 32, the priority their access request in a second register 35. The output of register 35 is connected to the input a second comparator 36. The access requests be of the mobile station according to their priority and within a priority class according to the order their input processed. For this purpose, in the access authorization simultaneously, the priority of the relevant Your access specified. The contained in the access authorization Priority class of the receiving part 1 determined evaluation contained and a Output PK a second input of the second comparator 36, respectively. A loss of one's own access request is determined by the mobile station in that it receives a response from the base station whose Rufschlitznummer larger than its stored Rufschlitznummer and at the same time the received priority class lower or equal to the stored priority class is. In this case, the mobile station changes from their waiting period back in the ringing phase. For this purpose the Outputs of the comparator 33 and the second comparator 36 connected respectively by means of an AND gate 37, the 38th