Method in a TDMA radiosystem to let a central station communicate with both peripheral stations and other central stations

• US 5,559,795 A
• Filed: 09/16/1994
• Issued: 09/24/1996
• Est. Priority Date: 02/03/1992
• Status: Expired due to Fees

• Current Assignee: Inventahl AB
• Original Assignee: Inventahl AB
• Inventors: Ahl, Peter
• Primary Examiner(s): Chin, Wellington
• Application Number:
  US08/284,409
• Time in Patent Office: 739 Days
• Field of Search: 370/95.1, 370/95.3, 370/29, 370/30, 370/60, 370/60.1, 370/94.1, 370/94.2, 370/97, 455/33.1, 455/53.1, 455/54.1, 455/56.1, 379/58, 379/59, 379/63, 379/56
• US Class Current: 370/342
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04W 16/26 Cell enhancers or enhancement, e.g. for tunnels, building shadow

Abstract

Method in a digital wide area system operating in time division and comprising two or several subsystems, each of which comprises at least one central station (CS) and one or several peripheral stations (PS) and covering an area/volume (space) where the area covered basically depends on the radio optical coverage of each central station and underlaying peripheral stations, the communication within and between subsystems that are geographically spread out is created at each central station. A central station is controlled to change mode of operation to operate either as a central station for transmitting and receiving information to and from underlaying peripheral stations, or receiving and transmitting information as a peripheral station (PS) from and to another central station.

Claims

1. A method in a digital wide area radio system including two or more subsystems, each of which includes at least one central station and one or more geographically spread out peripheral stations, said central station communicating with said peripheral stations in a radio covering area, said method comprising the steps of:

(a) transmitting a first set of information in radio signals from said central station to a receiver of a first peripheral station;

(b) storing said first set of information in an intermediate memory in said first peripheral station, either for transmitting said information to a second peripheral station in a second subsystem or for dropping user information as digital signals when the information is intended for the first peripheral station;

(c) switching a function of said first peripheral station from a peripheral station mode to a central station mode;

(d) transmitting said first set of information in radio signals from a transmitter of said first peripheral station, now operating in the central station mode, to the second peripheral station in the second subsystem;

(e) receiving in said receiver of said first peripheral station, still operating in the central station mode, signals including a second set of information from said second peripheral station and storing said information in the intermediate memory;

(f) switching the function of said first peripheral station from the central station mode to the peripheral station mode; and

(g) transmitting said second set of information in radio signals from said transmitter of said first peripheral station, operating in the peripheral station mode, to said central station.

2. A method according to claim 1, further comprising the step of applying a TDMA frame structure having at least a first time slot and at least a second time slot for communicating between said central station and said peripheral stations.

3. A method according to claim 2, further comprising the steps of:

receiving information in said first peripheral station in said first time slot; and

transmitting information from said first peripheral station in said second time slot, said first and second time slots being included in one time frame, so as to obtain a constant time delay when repeating between subsystems.

4. A method according to claim 2, further comprising the step of assigning a number of time slots in a time frame based on traffic demands.

5. A method according to claim 1, wherein communication between said central station and said peripheral stations is performed in time duplex.

6. A method according to claim 1, wherein communication between said central station and said peripheral stations is performed in frequency duplex.

7. A method according to claim 1, further comprising the step of modulating said radio signals according to CDMA.

8. A method according to claim 1, further comprising the step of modulating said radio signals according to QPSK.

9. A method according to claim 1, further comprising the step of dividing an available radio band into sub-channels having separately modulated carriers.

10. A method according to claim 1, further comprising the step of transmitting time frame synchronizing signals from said central station to associated peripheral stations.

11. A method according to claim 1, further comprising the step of transmitting radio signals from said peripheral stations to said central station using a directed antenna system.

12. A method according to claim 11, further comprising the step of redirecting said directed antenna system to be directed towards different central stations during different time intervals.

13. A method according to claim 12, further comprising the step of providing in said directed antenna system multiple horns feeding a common reflector.

14. A method according to claim 12, further comprising the step of providing in said directed antenna system a phase array antenna.

15. A method according to claim 11, further comprising the step of arranging in said peripheral stations a plurality of directed antennas.

16. A method according to claim 11, further comprising the step of redirecting said antenna system of said mobile peripheral stations towards its associated central station during relocation of said mobile station.

17. A method according to claim 11, further comprising the step of redirecting said antenna system of said mobile peripheral stations toward its associated central station during relocation of said mobile station.

18. A method according to claim 1, further comprising the step of arranging said first peripheral station in a building to communicate with said central station located on the outside of said building and to communicate with said second peripheral station located inside said building.

19. A method according to claim 1, further comprising the step of providing in said radio system a common network configuration and synchronizing means.

20. A method according to claim 1, further comprising the step of arranging said central stations and said peripheral stations outdoors.

21. A method according to claim 1, further comprising the step of providing said peripheral stations as mobile stations.

22. A method according to claim 1, wherein said switching step comprises the step of changing a mode of operation of said first peripheral station by exchanging control software in said first peripheral station.

23. A method according to claim 1, further comprising the step of arranging at least two central stations to cover a common area and a common set of peripheral stations said at least two central stations being operatively connected by a communication link to provide redundancy.

24. A method according to claim 1, further comprising the step of transmitting radio signals from said central station in a first direction to a first peripheral station and in a second direction to a second peripheral station.

25. A method according to claim 1, further comprising the step of modulating said radio signals according to PSK.

26. A method according to claim 1, further comprising the step of modulating said radio signals according to FSK.

27. A method according to claim 1, further comprising the step of modulating said radio signals according to QAM.

28. A method according to claim 1, further comprising the step of modulating said radio signals according to COFDM.

29. A method according to claim 1, further comprising the step of arranging at least one central station as a satellite.