Method of operating a TDD/virtual FDD hierarchical cellular telecommunication system

• US 20050174954A1
• Filed: 01/06/2005
• Published: 08/11/2005
• Est. Priority Date: 02/11/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd., University of Edinburgh
• Original Assignee: Samsung Electronics Co. Ltd., University of Edinburgh
• Inventors: Cho, Sung-Hyun, Yun, Sang-Boh, Kim, Eung-Sun, Kim, Yung-Soo, McLaughlin, Stephen, Lee, Yeon-Woo
• Granted Patent: US 7,817,592 B2
• Time in Patent Office: Days
• US Class Current: 370/310
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 16/32 Hierarchical cell structures

Abstract

A cellular communication system and method supporting both a time division duplexing (TDD) scheme and a frequency division duplexing (FDD) scheme. The apparatus includes a plurality of mobile stations, at least three first fixed stations communicate with the mobile station based on the FDD scheme, the first fixed station defining respective macro cells that are contiguous and form a virtual cell, and a cluster including at least one second fixed station communicating with the mobile stations based on the TDD scheme, the second fixed station defining a micro cell in the virtual cell.

Claims

1. A cellular communication system supporting at least two different duplexing schemes, comprising:

a plurality of mobile stations;

at least one first fixed station communicating with the plurality of mobile stations using a first duplexing scheme, the first fixed station defining a macro cell; and

at least one second fixed station communicating with the plurality of mobile stations using a second duplexing scheme, the second fixed station defining one of a micro and a pico cell located inside a boundary of the macro cell.

2. The cellular communication system of claim 1, wherein the first duplexing scheme is a frequency division duplexing (FDD).

3. The cellular communication system of claim 1, wherein the second duplexing scheme is a time division duplexing (TDD).

4. The cellular communication system of claim 1, wherein the macro cell is sectored at an azimuth angle and forms a plurality of macro sectors each having an identical size.

5. The cellular communication system of claim 4, wherein the micro cell is sectored at the same azimuth angle with the macro cell and forms as many micro sectors as the number of the macro sectors.

6. The cellular communication system of claim 5, wherein the micro cell is located in one of the macro sectors.

7. The cellular communication system of claim 6, wherein each macro and micro sector is identified by a unique sector code.

8. The cellular communication system of claim 7, wherein the mobile station located at the micro sector can borrow underused resources assigned for the macro sector of which an azimuth is identical to that of the micro sector.

9. The cellular communication system of claim 8, wherein the first and second fixed stations form sector beams using adaptive beamforming antennas for focusing on the plurality of mobile stations.

10. The cellular communication system of claim 4, wherein the azimuth angle is 120 degree.

11. A cellular communication system supporting at least two different duplexing schemes, comprising:

a plurality of mobile stations;

at least three first fixed stations communicating with the plurality of mobile stations using a first-duplexing scheme, the first fixed stations defining respective macro cells that are contiguous and form a virtual cell; and

one of a micro and pico cell cluster including at least one second fixed station communicating with the plurality of mobile stations using a second-duplexing scheme, the second fixed station defining one of the micro cell and the pico cell located in the virtual cell.

12. The cellular communication system of claim 11, wherein each macro cell is sectored and forms three macro sectors having respective sector beams directed from the first fixed station at different angles.

13. The cellular communication system of claim 11, wherein the micro cell is sectored and forms three micro sectors having respective sector beams directed from the second fixed station at different angles.

14. The cellular communication system of claim 12, wherein the micro cell is sectored and forms three micro sectors having respective sector beams directed from the second fixed station at different angles.

15. The cellular communication system of claim 14, wherein the macro and micro sectors are distinguished from each other by sector specific-codes.

16. The cellular communication system of claim 14, wherein the virtual cell is formed with three macro sectors of which sector beams are directed from different first fixed stations at different angles.

17. The cellular communication system of claim 16, wherein the sector beam of each macro sector has a main lobe in parallel with a main lobe of at least one of the micro sectors.

18. The cellular communication system of claim 17, wherein the micro cell cluster is located at a center of the virtual cell.

19. The cellular communication system of claim 18, wherein the mobile stations located at the micro sector can borrow underused resources assigned for the macro sector having an identical main lobe direction in the virtual cell.

20. The cellular communication system of claim 19, wherein the first and second fixed stations form the sector beams using adaptive beamforming antennas for focusing on the plurality of mobile terminals.

21. A cellular communication system supporting a time division duplexing (TDD) scheme and a frequency division duplexing (FDD) scheme, comprising;

a plurality of mobile stations;

at least three FDD fixed stations communicating with the plurality of mobile stations based on the FDD scheme, the FDD fixed stations defining respective macro cells that are contiguous and a virtual cell; and

a cluster including at least one TDD fixed station communicating with the plurality of mobile stations based on the TDD scheme, the TDD fixed station defining a one of a micro cell and a pico cell in the virtual cell.

22. The cellular communication system of claim 21, wherein the cluster locates coaxially with the virtual cell.

23. The cellular communication system of claim 22, wherein each macro cell is sectored at an azimuth angle and forms three macro sectors covered by respective sector beams directed from the FDD fixed station.

24. The cellular communication system of claim 23, wherein each micro cell is sectored at the azimuth angle for the macro sector and forms three micro sectors covered by respective sector beams directed from the TDD fixed station.

25. The cellular communication system of claim 24, wherein the virtual cell is formed with three macro sectors belonged to the different macro cells formed at different azimuth angles.

26. The cellular communication system of claim 25, wherein the mobile station located at the micro sector can borrow underused resources assigned for the macro sector of which an azimuth angle is identical with that of the micro sector.

27. The cellular communication system of claim 26, wherein the FDD and TDD fixed stations form the sector beams using adaptive beamforming antennas for focusing on the plurality of mobile stations.

28. A method for constructing cellular communication system supporting communications between fixed stations and mobile stations based on both a frequency division duplexing (FDD) and a time division duplexing (TDD) schemes, comprising:

forming at least three contiguous macro cells defined by respective FDD-based fixed stations;

forming at least one cluster including at least one a micro or pico cell defined by a TDD-based fixed station; and

forming a virtual cell surrounded by the FDD-based fixed stations.

29. The method of claim 28, wherein the cluster locates coaxially with the virtual cell.

30. The method of claim 29, wherein each macro cell is sectored at an azimuth angle and forms three macro sectors covered by respective sector beams directed from the FDD-based fixed station.

31. The method of claim 30, wherein each micro cell is sectored at the azimuth angle for the macro sector and forms three micro sectors covered by respective sector beams directed from the TDD-based fixed station.

32. The method of claim 31, wherein the virtual cell is formed with three macro sectors belonged to different macro cells formed at different azimuth angles.

33. The cellular communication system of claim 32, wherein the mobile station located at the micro sector can borrow underused resources assigned for the macro sector of which an azimuth angle is identical with that of the micro sector.

34. The method of claim 33, wherein the FDD- and TDD-based fixed stations form the sector beams using adaptive beamforming antennas for focusing on the plurality of mobile stations.

35. A method for allocating radio resource in cellular communication system supporting communications between fixed stations and mobile stations based on a frequency division duplexing (FDD) and a time division duplexing (TDD) scheme, comprising:

receiving, at a TDD fixed station, a call request from a TDD mobile station;

determining if a TDD resource is available;

allocating the TDD resource to the TDD mobile station, when the TDD resource is available;

borrowing FDD resource from a FDD fixed station, when the TDD resource is not available; and

allocating the FDD resource to the TDD mobile station according to a priority of the TDD mobile station.

36. The method of claim 35, wherein the borrowing resource further comprises:

determining if underused FDD resource available at any FDD carrier;

determining whether to borrow underused FDD resource, if the underused resource available;

determining a priority of the TDD mobile station, if it is determined to borrow the underused FDD resource.

37. The method of claim 36, wherein the borrowing resource further comprises determining whether to apply an adaptive beamforming for determining the priority of the TDD mobile station.

38. The method of claim 36, wherein step of determining whether to borrow the underused FDD resource comprises:

measuring a first intersystem interference (I<sub>MS—

inter-sys</sub>) by the TDD mobile station;

comparing the first intersystem interference (I<sub>MS—

inter-sys</sub>) received from the TDD mobile station with a predetermined first interference margin threshold (I<sub>TH—

MS</sub>); and

determining to borrow the underused FDD resource when the first intersystem interference (I<sub>MS—

inter-sys</sub>) is less than or equal to the first interference margin threshold (I<sub>TH—

MS</sub>).

39. The method of claim 38, wherein the first intersystem interference (I_MS—

_inter-sys) is from FDD mobile stations to the TDD mobile station.

40. The method of claim 37, wherein the step of determining whether to apply the adaptive beamforming comprises:

measuring, at the TDD fixed station, a second inter system interference (I<sub>BS—

inter-sys</sub>);

comparing the second inter-system interference (I<sub>BS—

inter-sys</sub>) with a second interference margin threshold (I<sub>TH—

BS</sub>); and

applying the adaptive beamforming when the second inter-system interference (I<sub>BS—

inter-sys</sub>) is not less than the second interference margin threshold (I<sub>TH—

BS</sub>).

41. The method of claim 40, wherein the second inter system interference (I_BS—

_inter-sys) is from FDD mobile stations to the TDD fixed station.