Accessing of transmission channels of a communication system

• US 4,815,073 A
• Filed: 07/15/1986
• Issued: 03/21/1989
• Est. Priority Date: 08/22/1981
• Status: Expired due to Term

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Schmidt, Werner, Grauel, Christoph
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Chin, Wellington
• Application Number:
  US06/885,764
• Time in Patent Office: 980 Days
• Field of Search: 455/33, 379/59, 379/60, 370/94, 370/95
• US Class Current: 370/347
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

In a communications system with a plurality of subscriber stations independent of each other, where each subscriber station can access a joint duplex transmission channel according to a multiple access method, the probability of simultaneous attempts to get access becomes very image, and thereby the probability of signal destruction is particularly increased. In order to avoid a blockage of the service channel each subscriber station occupies the duplex transmission channel with a short access signal for initiating a transmission starting from the subscriber station. The subscriber station characterized by the position in time and/or the information contents of the short access signal is thereupon invited by the central base station to emit an access signal to join practical access to the communication exchange.

Claims

1. A method for accessing of transmission channels in a communication system with at least a central base station, at least a duplex transmission channel and a plurality of independent subscriber stations where the independent subscriber stations can access the duplex transmission channel comprising

originating at a subscriber station a bit sequence representing a short access code carrying cell request information amounting to less than a complete identification of the subscriber station, engaging a duplex transmission channel for initiating an information transmission from the subscriber station, where the duplex transmission channel serves for information exchange between the central base station and a plurality of subscriber stations, where the subscriber station includes a first control device which is connected to a first transceiver set disposed in the subscriber station, where the first control device employs a control signal to induce the transceiver part during access onto the duplex transmission channel to emit a bit sequence representing a short access code to the central base station via the duplex transmission channel;

receiving the bit sequence representing a short access code in a second transceiver part of the central base station;

feeding the bit sequence representing a short access code to a second control device disposed in the central base station;

actuating the second transceiver part of the central base station by the second control section to emit a response signal via the transmission channel for responding to the received bit sequence representing a short access code with a request for a complete access signal to a subscriber station characterized by such bit sequence representing a short access code thereby accepting initiation of an information transmission from and to the subscriber station.

2. The method for accessing of transmission channels according to claim 1 further comprising

storing the bit sequence representing a short access code and the access signal in a first memory storage element disposed in the subscriber station and connected to the first control device;

and

storing the bit sequence representing a short access code and the access signal in a second memory storage element disposed in the central base station and connected to the second control device.

3. The method for accessing of transmission channels according to claim 2 further comprising

comparing the received bit sequence representing a short access code with a bit sequence representing a short access code entered via the control device into the second memory in a comparison circuit connected to the control circuit and to the transceiver;

and

communicating the result of the comparing in the response signal as a characteristic of the subscriber station responded to.

4. The method for accessing of transmission channels according to claim 1 further comprising

determining the point in time of the reception of a bit sequence representing a short access code with a time measuring device connected to the second control device;

and

communicating the position in time of the bit sequence representing a short access code as a characteristic of the subscriber station in the response signal emitted by the central base station for the subscriber station.

5. The method for accessing of transmission channels according to claim 1 further comprising

determining the received signal quality of the bit sequence representing a short access code in a measurement section connected to the transceiver and the second control device;

and

emitting a request for complete identification by the central base station depending on the received signal quality.

6. The method for accessing for transmission channels according to claim 1 further comprising

setting individually a delay of each information transfer in the direction to the central base station versus an information transmission in the direction to the subscriber stations in the second control device;

generating a corresponding control signal in the second control device;

transmitting the control signal via the second transceiver and the duplex transmission channel to the subscriber stations via the first tranceiver and via the first control device; and

delaying an information transmission in the direction to the central base station with a delay circuit, which is disposed in the subscriber station and which is connected to the first transceiver and to the first control device for obtaining a time delay relative to the time of the information transmission in the direction to the subscriber station.

7. The method for accessing of transmission channels according to claim 1 further comprising

subdividing the duplex transmission channel into time intervals permitting or blocking free access with the second control device of the central base station;

emitting marking signals in the direction toward the subscriber station furnished by a marking device connected to the second control device and to the second transceiver, where the markings determine during which time intervals the subscriber stations can have access with a bit sequence representing a short access code onto the duplex transmission channel.

8. The method for accessing of transmission channels according to claim 1 further comprising

limiting, with the first control device connected to a blocking circuit disposed in the subscriber station, the emission of the access signal after reception of the response signal as well as of additional information signals to time intervals that are blocked for free access to the central base station.

9. The method for accessing of transmission channels according to claim 1 further comprising

informing the subscriber station of a transmission channel blocked except for free access with a signal coming from the second control device of the central base station and transmitted by the first transceiver station, which channel is available after reception of the response signal by the subscriber station both for emitting of the complete access signal by the subscriber station as well as for further information transmission.

10. The method of accessing of transmission channels according to claim 1 further comprising

selecting by the subscriber station, with a time presetting circuit, according to a defined algorithm the exact point in time within a time interval permitting access for starting the emission of a bit sequence representing a short access code in order to initiate an information transmission to the central base station.

11. The method for accessing of transmission channels according to claim 1 further comprising

subdividing the time intervals during which the subscriber stations may access the duplex transmission channel with a bit sequence representing a short access code into call slots with a time control circuit disposed in the central base station and connected to the second control device, where the length of time of the call slots is an integral multiple of the time duration of a bit sequence representing a short access code.

12. The method for accessing of transmission channels according to claim 1 further comprising

incorporating the response signal to a subscriber station, which has called with a bit sequence representing a short access code, as a part of any transmission emitted by the central base station.

13. The method for accessing of transmission channels according to claim 1 further comprising

providing all the bit sequences representing a short access code emitted by the subscriber stations to have the same time duration.

14. The method for accessing of transmission channels according to claim 13 further comprising

subdividing the time intervals of the duplex transmission channel during which the subscriber stations can access with bit sequences representing a short access code into a sequence of call slots in each transmission direction with the central base station.

15. A system for establishing communication transmission between subscriber stations served by a central base station comprising

a duplex transmission channel;

a subscriber station emitting initially a bit sequence representing a short access code for gaining access to transmission via the duplex transmission channel, where the bit sequence representing a short access code carries call request information amounting to less than a complete identification of the subscriber station, to the central base station for initiating an information transmission of the subscriber station via the duplex transmission channel;

the central base station receiving the bit sequence representing a short access code and responding with a response signal including a request for a complete access signal of the subscriber station and thereby initiating an information transmission from and to the subscriber station.

16. The system for establishing communication transmission according to claim 15 further comprising

a first control device incorporated into the subscriber station for providing a fixed delay for each transmission in the direction towards the central base station versus the information transmission in the direction towards the subscriber stations.

17. The system for establishing communication transmission according to claim 15 further comprising

a second control device for intermittantly blocking transmission modes and for subdividing the duplex transmission channel into time intervals permitted and time intervals blocked for free access by the subscriber stations.

18. The system for establishing communication transmission according to claim 15 further comprising

a marking device disposed at the central base station for emitting marking signals setting times with allowed access to the duplex transmission channel of bit sequences representing a short access code coming from the subscriber stations.

19. The system for establishing communication transmission according to claim 15 further comprising

a memory storage device for recording bit sequences of short access codes and of access signals.

20. The system of establishing communication transmission according to claim 19 further comprising

a comparison circuit disposed in the central base station for comparing incoming bit sequences representing a short access code and access signals with bit sequences representing a short access code and access signals stored in the memory storage.