Communication System Using Relay Base Stations with Asymmetric Data Links

• US 20080075178A1
• Filed: 12/30/2003
• Published: 03/27/2008
• Est. Priority Date: 12/30/2003
• Status: Active Grant

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Lappetelainen, Antti, Ojala, Jussi
• Granted Patent: US 7,990,905 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 7/155 Ground-based stations H04B7/204 takes precedence
• CPC Class Codes: H04B 7/2606 Arrangements for base station coverage control, e.g. by using relays in tunnels
• CPC Class Codes: H04B 7/2656 for structure of frame, burst
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 84/047 using dedicated repeater stations
• CPC Class Codes: H04W 88/04 adapted for relaying to or from another terminal or user

Abstract

The invention relates to a method is shown for improving the spectral efficiency of a communication system (100) that comprises at least one Super Base Station SBS (1) and at least one terminal (3-1), wherein at least one Relay Base Station RBS (2-1s used to relay asymmetric up- and downlink data between said at least one Super Base Station SBS (1) and said at least one terminal (3-1) and wherein said asymmetry of said up- and downlink data is considered when dynamically allocating transmission resources to said relay link (5-1, 6-1) between said at least one SBS (1) and said at least one RBS (2-1) and to said link (7-1, 8-1) between said at least one RBS (2-1) and said at least one terminal (3-1).

Claims

1. Method for improving spectral efficiency of a communication system that comprises at least one super base station and at least one terminal, wherein at least one relay base station is used to relay up- and downlink data between said at least one super base station and said at least one terminal, and wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one terminal take place, and a start and a duration of up- and downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one super base station take place, are defined by a relay base station frame structure, said method comprising:

dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure under consideration of an asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station.

2. The method according to claim 1, wherein said step of dynamically allocating said up-and downlink relay base station-super base station transmission periods is performed by said at least one relay base station.

3. The method according to claim 1, wherein said at least one relay base station is used to relay up- and downlink data between said at least one super base station and a plurality of terminals.

4. The method according to claim 1, wherein a first relay base station is used to relay up- and downlink data between said at least one super base station and at least a first terminal and wherein a second relay base station is used to relay up- and downlink data between said at least one super base station and at least a second terminals.

5. The method according to any of the claim 1, wherein up- and downlink data is also directly transmitted between said at least one super base station and at least one super base station terminal.

6. The method according to claim 5, wherein said super base station comprises at least two transceivers, wherein a first of said at least two transceivers is used for said up- and downlink transmissions between said super base station and said at least one, and wherein a second of said at least two receivers is used for said direct up- and downlink transmissions between said super base station and said at least one super base station terminal.

7. The method according to claim 1, wherein said at least one relay base station comprises at least two sets of physical antenna elements, wherein a first of said at least two sets of physical antenna elements is used for said up- and downlink transmissions between said at least one relay base station and said at least one super base station, and wherein a second of said at least two sets of physical antenna elements is used for said up- and downlink transmissions between said at least one relay base station and said at least one terminal.

8. The method according to claim 1, wherein said uplink transmissions and said downlink transmissions between said at least one relay base station and said at least one terminal use the same carrier frequency and are separated in the time domain.

9. The method according to claim 8, wherein said transmissions between said at least one relay base station and said at least one terminal and said transmissions between said at least one relay base station and said at least one super base station use the same carrier frequency.

10. The method according to claim 8, wherein said transmissions between said at least one relay base station and said at least one terminal and said transmissions between said at least one relay base station and said at least one super base station use different carrier frequencies.

11. The method according to claim 8, wherein at least two different relay base stations use different orthogonal carriers for their transmissions with said at least one super base station, in particular different carrier frequencies, transmission instances, polarizations, or codes.

12. The method according to claim 11, wherein at least two different use different time instances for their transmissions with said at least one super base station, and wherein different transmission time instances are predetermined for different relay base stations.

13. The method according to claim 8, wherein at least two different relay base stations use the same orthogonal carrier for transmissions with said at least one super base station, and wherein said super base station deploys space division multiple access techniques to assure the separation of the transmissions of said at least two different relay base stations.

14. The method according to claim 13, wherein a network planning process is used to provide sufficient spatial separation between relay base station-super base station transmissions of said at least two different relay base stations and said at least one super base station.

15. The method according to claim 8, wherein an uplink periods, in which uplink transmissions between said at least one relay base station and said at least one terminal can take place, and a downlink period , in which downlink transmissions between said at least one relay base station and said at least one terminal are allowed to take place, are fixedly defined in said relay base station frame structure.

16. The method according to claim 15, wherein at least two relay base stations are synchronised in a way that said respective uplink and downlink periods in said respective relay base station frame structures are equal and that said respective relay base station frame structures are temporally aligned.

17. The method according to claim 16, wherein said step of dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure comprises at least partially overlaying said uplink (and/or downlink periods with said up- and/or downlink inter relay base station super base station transmission periods.

18. The method according to claim 17, wherein said asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station is considered in said step of dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure by increasing said overlaid uplink portion if there is more data to be transmitted in said downlink transmission between said at least one relay base station and said at least one terminal as compared to said uplink transmission, and increasing said overlaid downlink portion if there is more data to be transmitted in said uplink transmission between said at least one relay base station and said at least one terminal base compared to said downlink transmission.

19. The method according to claim 18, wherein in the first case, said uplink portion His at least partially overlaid with said downlink relay base station-super base station transmission period, and wherein in the second case, said downlink portion is at least partially overlaid with said uplink relay base station-super base station period

20. The method according to claim 8, wherein periods in said Relay base station frame structure in which said uplink relay base station-super base station transmission periods and said downlink R transmission periods can be allocated are either fixed or signalled to said at least one relay base station by said at least on super base station.

21. The method according to claim 8, wherein said frame structure comprises a temporal sequence of super frames, wherein each super frame comprises at least one uplink relay base station-terminal period, at least one downlink relay base station-terminal period, and either at least one relay base station uplink period or at least one relay base station-super base station downlink period.

22. The method according to claim 21, wherein said up- and downlink relay base station-terminal periods take turns from superframe to superframe.

23. The method according claim 1, wherein said uplink transmissions and said downlink transmissions between said at least one and said at least one terminal take place at least partially in parallel and are separated in the frequency domain by using at least two carrier frequencies.

24. The method according to claim 23, wherein said uplink transmissions between said at least one relay base station and said at least one terminal and said downlink transmissions between said at least one relay base station and said at least one super base station at least temporarily use the same carrier frequency, and wherein said downlink transmissions between said at least one relay base station and said at least one terminal and said uplink transmissions between said at least one relay base station and said at least one super base station at least temporarily use the same carrier frequency.

25. The method according to claim 23, wherein said at least two frequencies used by a first relay base station to separate said respective uplink and downlink transmissions and said at least two frequencies used by a second relay base station to separate said respective uplink and downlink transmissions are pairwise different.

26. The method according to claim 23, wherein said at least two frequencies used by a first relay base station to separate said respective uplink and downlink transmissions and said at least two frequencies used by a second relay base station to separate said respective uplink and downlink transmissions are pairwise equal.

27. The method according to claim 23, wherein uplink transmissions and downlink transmissions between said at least one super base station and at least one Super base station terminal take place at least partially in parallel and are separated in the frequency domain by using at least two carrier frequencies.

28. The method according to claim 27, wherein said at least two frequencies used by said at least one relay base station to separate said respective uplink and downlink transmissions and said at least two frequencies used by said at least one super base station to separate said respective uplink and downlink transmissions are pairwise different.

29. The method according to claim 27, wherein said at least two frequencies used by said at least one relay base station to separate said respective uplink and downlink transmissions and said at least two frequencies used by said at least one super base station to separate said respective uplink and downlink transmissions are pairwise equal.

30. The method according to claim 26, wherein said super base station uses space division multiple access techniques to separate Concurrent transmissions that use the same carrier frequencies.

31. The method according to claim 30, wherein a network planning process is used to provide sufficient spatial separation between said concurrent transmissions that use the same carrier frequencies.

32. The method according to claim 23, wherein an uplink period, in which uplink transmissions between said at least one relay base station and said at least one terminal are allowed to take place, and a downlink period, in which downlink transmissions between said at least one relay base station and said at least one terminal are allowed to take place, are fixedly defined in said RBS frame structures.

33. The method according to claim 32, wherein said asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station is considered in said step of dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure by increasing said overlaid uplink portion if there is more data to be transmitted in said downlink transmission between said at least one relay base station and said at least one terminal as compared to said uplink transmission, and increasing said overlaid downlink portion if there is more data to be transmitted in said uplink transmission between said at least one relay base station and said at least one terminal as compared to said downlink transmission.

34. The method according to claim 33, wherein in the first case, said uplink portion is at least partially overlaid with said downlink relay base station-super base station transmission period, and wherein in the second case, said downlink portion is at least partially overlaid with said uplink relay base station-super base station period.

35. The method according to claim 34, wherein on each of said at least two carrier frequencies that are used for the separation of said uplink transmissions and said downlink transmissions between said at least one relay base station and said at least one terminal , said uplink and downlink periods take place in an alternating fashion.

36. The method according to claim 35, wherein at least two relay base stations are synchronized, in a way that said respective uplink sand downlink periods in said respective relay base station frame structures are equal and that said respective frame structures are temporally aligned.

37. The method according to claim 36, wherein multiple-input-multiple-output techniques are used for transmissions between said at least one relay base station and said at least one super base station and/or between said at least one super base station and said at least one super base station terminal and/or between said at least one and said at least one terminal.

38. The method according to claim 37, wherein said multiple-input-multiple-output techniques are based on the adaptive estimation of channel parameters under exploitation of the alternating occurrence of uplink and downlink on the same frequency carrier for the transmissions between the at least one relay base station and the at least one super base station and/or the transmissions (7-1, 8-1) between the at least one relay base station and the at least one terminal and/or the transmissions between the at least one super base station and the at least one super base station terminal.

39. The method according to claim 34, wherein on a first of said at least two carrier frequencies that are used for the separation of said uplink transmissions and said downlink transmissions between said at least one relay base station and said at least one terminal, said uplink transmissions take place, and wherein on a second of said at least two carrier frequencies, said downlink transmissions take place.

40. The method according to claim 34, wherein at least two relay base stations are not synchroniszed, in a way that said respective uplink and downlink periods in said respective relay base station frame structures are equal but that said respective frame structures are not temporally aligned.

41. The method according to claim 1, wherein a handover of said at least one relay base station from a first super base station to a second super base station is possible, and wherein handover parameters are signalled between said at least one relay base station, said first super base station and said second Super base station.

42. The method according to claim 1, wherein said up- and downlink data is relayed between said at least one super base station and said at least one terminal via n relay base stations, where n is an integer number equal to or larger than two.

43. The method according to claim 1, wherein data of one link direction is relayed between said at least one super base station and said at least one terminal via n relay base station, where n is an integer number equal to or larger than 1, and wherein data of the other link direction is transmitted between said at least one super base station and said at least one terminal via m relay base stations, wherein m is an integer number between 0 and n−

1.

44. The method according to claim 43, wherein the decision whether a terminal becomes said at least one super base station terminal or not is also based on delay requirements of active applications in said terminal.

45. The method according to claim 1, wherein a first terminal and a second terminal communicate during said uplink and/or downlink inter relay base station-super base station transmission periods.

46. The method according to claim 1 wherein said at least one terminal Communicates with its peripherals during said uplink and/or downlink r relay base station-super base station transmission periods.

47. The method according to claim 1 wherein for said transmissions between said at least one relay base station and said at least one super base station, different coding schemes and/or modulation schemes and/or packet structures are used as for said transmissions between said at least one relay base station and said at least one terminal or said transmissions between said at least one super base station and said at least one super base station terminal.

48. A computer program with instructions operable to cause a processor to perform the method claim 1.

49. A computer program product comprising a computer program with instructions operable to cause a processor to perform the method claim 1.

50. Device for improving spectral efficiency of a communication system that comprises at least one super base station and at least one terminal, wherein at least one relay base station is used to relay up- and downlink data between said at least one super base station and said at least one terminal, and wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one terminal take place, and a start and a duration of up- Land downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said at least one a relay base station and said at least one super base station take place, are defined by an relay base station frame structure, said device comprising:

means for dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure under consideration of an asymmetry between said up- and downlink data relayed between said at least one Super base station and said at least one terminal via said at least one relay base station.

51. Communication system, comprising:

at least one super base station,

at least one terminal, and

at least one relay base station,

wherein said at least one relay base station is used to relay up- and downlink data between said at least one super base station and said at least one terminal, wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one terminal take place, and a start and a duration of up- and downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one super base station take place, are defined by an relay base station frame structure, and wherein said up- and downlink relay base station-super base station transmission periods are dynamically allocated in said relay base station frame structure under consideration of an asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station.

52. Terminal in a communication system that comprises at least one super base station and at least one terminal, wherein at least one relay base station is used to relay up- and downlink data between said at least one super base station and said at least one terminal, and wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one terminal take place, and a start and a duration of up- and downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one super base station take place, are defined by relay base station frame structure, and wherein said up- and downlink base station-super base station transmission periods are dynamically allocated in said Relay base station frame structure under consideration of an asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station.

53. Relay base station in a communication system that comprises at least one super base station and at least one terminals, wherein said relay base station is used to relay up- and downlink data between said at least one super base station and said at least one terminal, and wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said relay base station and said at least one terminal take place, and a start and a duration of up- and downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said relay base station and said at least one super base station take place, are defined by relay base station frame structure, said relay base station comprising:

means for dynamically allocating said up- and downlink relay base station-super base station transmission periods in said relay base station frame structure, under consideration of an asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said relay base station.

54. Super base station in a communication system, wherein at least one relay base station is used to relay up- and downlink data between said super base station and at least one terminal, wherein a start and a duration of up- and downlink relay base station-terminal transmission periods, in which up- and downlink transmissions between said at least one relay base station and said at least one terminal take place, and a start and a duration of up- and downlink relay base station-super base station transmission periods, in which up- and downlink transmissions between said at least one relay base station and said super base station take place, are defined by an relay base station frame structure, and wherein said up- and downlink relay base station-super base station transmission periods are dynamically allocated in said relay base station frame structure under consideration of an asymmetry between said up- and downlink data relayed between said at least one super base station and said at least one terminal via said at least one relay base station.