Method of reducing transmission power in a wireless communication system

• US 6,980,832 B1
• Filed: 11/06/2000
• Issued: 12/27/2005
• Est. Priority Date: 11/08/1999
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Nokia Corporation
• Inventors: Pichna, Roman, Ylitalo, Juha
• Primary Examiner(s): Corsaro, Nick
• Assistant Examiner(s): Chu, Michael
• Application Number:
  US10/129,712
• Time in Patent Office: 1,877 Days
• Field of Search: 455/522, 455/69, 455/127.1, 455/127.5
• US Class Current: 455/562.1
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

In the described system, one or more base stations transmit a signal to a mobile station. The signal is transmitted using polarisation diversity, whereby the signal is transmitted in one direction using two signal beams, each signal beam being differently polarised. A method of beam-hoping may be employed whereby the polarisation of the transmitted beams during hand off is varied according to predefined sequence. The sequence may be determined according to the data loading within the respective transmission cells. Also disclosed is a method of soft or softer hand off within a wireless communication system where the total number of signal beams transmitted from two base stations to a single mobile station during hand off is kept constant.

Claims

1. A method of directional wireless communication between a first station and a plurality of second stations, each of said second stations capable of transmitting a signal in a plurality of beam directions and with a selected polarisation, said method comprising:

transmitting from a first one of said second stations to said first station a first signal in a first one of said plurality of directions with a first polarisation only; and

transmitting from a second one of said second stations to said first station a second signal in a second one of said plurality of directions with a second different polarisation only,

wherein said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each said second stations, and p denotes the polarisation, and said sequence is (B¹_1,1–

B²_2,1), (B¹_1,2–

B²_2,1), (B¹_1,1–

B²_2,2), (B¹_1,2–

B²_2,2).

2. The method of claim 1, wherein only said first and second signals are transmitted to said first station.

3. The method of claim 1, wherein said sequence is selected in dependence on loading of communication sectors in which each of the second stations are located.

4. The method of claim 1, wherein said sequence is selected when each of said respective communication sectors is loaded substantially equally.

5. The method of claim 1, wherein said first signal and said second signal are polarised at 90°

with respect to each other.

8. The method of claim 1, wherein each of said second stations are associated with respective areas.

9. The method of claim 8, wherein said first station is located within a border region between the areas associated with each said respective second station.

10. The method of claim 1, wherein said first station is a mobile station.

11. The method of claim 1, wherein the method is performed in a CDMA communications system.

13. The method of claim 2, wherein said first signal is transmitted from a first one of said second stations and said second signal is transmitted from a second one of said second stations.

14. The method of claim 2, wherein said first signal and said second signal are transmitted from the same one of said second stations.

15. The method of claim 2, wherein said first signal and said second signal are transmitted in accordance with a selected sequence.

17. The method of claim 8, when used wherein the method is performed in a wireless communications system utilizing Space-Time coding.

18. The method of claim 9, wherein the method is performed in a wireless communications system utilizing Space-Time coding.

19. The method of claim 10, wherein the method is performed in a wireless communications system utilizing Space-Time coding.

6. A method of directional wireless communication between a first station and a plurality of second stations, each of said second stations capable of transmitting a signal in m different directions, where m is two or more, said method comprising:

transmitting to said first station a signal from a first one of said second stations in n number of said directions, where 1≦

n<

m; and

transmitting to said first station said signal from a second one of said second stations in m-n of said directions,

wherein the directions in which the signal is transmitted from said first one of said second stations are substantially different from the directions in which the signal is transmitted from the second one of said second stations.

7. The method of claim 6, further comprising the subsequent steps of:

decreasing by a first number which is at least one of the number of directions in which said signal is transmitted to said first station from the first one of the second stations;

increasing by the first number the number of directions in which said signal is transmitted to said first station from the second one of the second stations; and

repeating said previous steps until said signal is transmitted in m directions from said second one of the second stations only.

12. The method of claim 6, wherein the method is performed in a wireless communications system utilizing Space-Time coding.

16. The method of claim 7, wherein the method is performed in a wireless communications system utilizing Space-Time coding.

20. A method of directional wireless communication between a first station and a plurality of second stations, each of said second stations being configured to transmit a signal in a plurality of beam directions and with a selected polarisation, said method comprising:

transmitting to said first station a first signal in a first one of said plurality of beam directions with a first polarisation only; and

transmitting to said first station a second signal in a second one of said plurality of beam directions with a second different polarisation only,

wherein said first signal and said second signal are transmitted from an identical one of said second stations, and said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each of said second station, and p denotes the selected polarisation, and said sequence is (B¹_1,2–

B²_1,1).

21. The method of claim 20, wherein said sequence is selected when one of said respective communication sectors is more heavily loaded than the other respective communication sector.

22. The method of claim 20, wherein said sequence is selected in dependence on loading of communication sectors in which each second station is located.

23. A method of directional wireless communication between a first station and a plurality of second stations, each of said second stations being configured to transmit a signal in a plurality of beam directions and with a selected polarisation, said method comprising:

transmitting to said first station a first signal in a first one of said plurality of directions with a first polarisation only; and

transmitting to said first station a second signal in a second one of said plurality of directions with a second different polarisation only,

wherein said first signal and said second signal are transmitted from an identical one of said second stations, and said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each said second station, and p denotes the polarisation, and said sequence is (B¹_2,1–

B²_2,2).

24. The method of claim 23, wherein said sequence is selected in dependence on loading of communication sectors in which each second station is located.

25. The method of claim 23, wherein said sequence is selected when one of said respective communication sectors is more heavily loaded than the other respective communication sector.

26. A directional wireless communication system comprising:

a first station;

a plurality of second stations, each of said second stations being configured to transmit a signal in a plurality of beam directions and with a selected polarisation; and

control means, wherein said control means controls said plurality of second stations to transmit from a first one of said second stations to said first station a first signal in a first one of said plurality of directions with a first polarisation only, and wherein said control means controls said plurality of second stations to transmit from a second one of said second stations to said first station a second signal in a second one of said plurality of directions with a second different polarisation only, and

wherein said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each said second station, and p denotes the polarisation, and said sequence is (B¹_1,1–

B²_2,1), (B¹_1,2–

B²_2,1), (B¹_1,1–

B²_2,2), (B¹_1,2–

B²_2,2).

27. The communication system of claim 26, wherein each second station comprises at least one antenna array, each array having a plurality of antennae.

28. The communication system of claim 27, wherein each antenna array is configured to transmit a first signal having a first polarisation and a second signal having a second polarisation.

29. The communication system of claim 28, wherein each antenna array is configured to transmit said first and second signals in any one of a plurality of directions.

30. The communication system of claim 27, wherein said first and second signals are polarised by 90°

with respect to each other.

31. The communication system of claim 26, wherein each at least one antenna array comprises four antennae.

32. The communication system of claim 26, wherein each at least one antenna is a dual polarised antenna.

33. The communication system of claim 29, wherein said first and second signals are polarised by 90°

with respect to each other.

34. A directional wireless communication system comprising:

a first station;

a plurality of second stations, each of said second stations being configured to transmit a signal in a plurality of beam directions and with a selected polarisation; and

control means, wherein said control means controls said plurality of second stations to transmit to said first station a first signal in a first one of said plurality of beam directions with a first polarisation only, and wherein said control means controls said plurality of second stations to transmit to said first station a second signal in a second one of said plurality of beam directions with a second different polarisation only, and

wherein said first signal and said second signal are transmitted from an identical one of said second stations, and said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each said second station, and p denotes a polarisation, and said sequence is (B¹_1,2–

B²_1,1).

35. The communication system of claim 34, wherein each second station comprises at least one antenna array, each said array having a plurality of antennae.

36. The communication system of claim 35, wherein each antenna array is configured to transmit a first signal having a first polarisation and a second signal having a second polarisation.

37. The communication system of claim 36, wherein each antenna array is configured to transmit said first and second signals in any one of a plurality of directions.

38. The communication system of claim 36, wherein said first and second signals are polarised by 90°

with respect to each other.

39. The communication system of claim 35, wherein each antenna array comprises four antennae.

40. The communication system of claim 35, wherein each antenna is a dual polarised antenna.

41. The communication system of claim 34, wherein said first and second signals have a polarised by 90°

with respect to each other.

42. A directional wireless communication system comprising:

a first station;

a plurality of second stations, each of said second stations being configured to transmit a signal in a plurality of beam directions and with a selected polarisation; and

control means, wherein said control means controls said plurality of second stations to transmit to said first station a first signal in a first one of said plurality of directions with a first polarisation only, and wherein said control means controls said plurality of second stations to transmit to said first station a second signal in a second one of said plurality of directions with a second different polarisation only,

wherein said first signal and said second signal are transmitted from an identical one of said second stations, and wherein said first signal and said second signal are transmitted in accordance with a selected sequence represented by the notation Bⁿ_s,p, where n denotes the first or second signal, s denotes an area associated with each said second station, and p denotes the polarisation, and said sequence is (B¹_2,1–

B²_2,2).

43. The communication system of claim 42, wherein each second station comprises at least one antenna array, each said array having a plurality of antennae.

44. The communication system of claim 43, wherein each antenna array is configured to transmit a first signal having a first polarisation and a second signal having a second polarisation.

45. The communication system of claim 44, wherein each antenna array is configured to transmit said first and second signals in any one of a plurality of directions.

46. The communication system of claim 44, wherein said first and second signals are polarised by 90°

with respect to each other.

47. The communication system of claim 43, wherein each antenna array comprises four antennae.

48. The communication system of claim 43, wherein each antenna is a dual polarised antenna.

49. The communication system of claim 45, wherein said first and second signals are polarised by 90°

with respect to each other.