Pilot signals for use in multi-sector cells

• US 9,544,860 B2
• Filed: 08/25/2003
• Issued: 01/10/2017
• Est. Priority Date: 02/24/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Laroia, Rajiv, Fan, John L., Li, Junyi
• Primary Examiner(s): Sobutka, Philip
• Application Number:
  US10/648,767
• Publication Number:
  US 20040166887A1
• Time in Patent Office: 4,887 Days
• Field of Search: 455/522, 455/68, 455/13.4, 455/67.11, 455/67.13, 455/67.14, 455/67.16, 455/69, 455/561, 455/562.1, 370/318, 370/319
• US Class Current: 1/1
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

Pilot signal transmission sequences and methods for use in a multi-sector cell. Pilots in different sectors are transmitted at different known power levels. In adjacent sectors a pilot is transmitted while no pilot is transmitted in the adjoining sector. This represents transmission of a NULL pilot signal. A cell NULL is also supported in which NULL pilots are transmitted in each sector of a cell at the same time. Multiple pilot signal measurements are made. At least two channel quality indicator values are generated from measurements corresponding to at least two pilot signals of different power levels. The two values are transmitted back to the base station which uses both values to determine the transmit power requited to achieve a desired SNR at the wireless terminal. The wireless terminal also reports information indicating its location to a sector boundary.

Claims

1. A channel quality reporting method for use by a wireless terminal, the method comprising:

measuring at least one of an amplitude or a phase of a first pilot signal corresponding to a first pilot tone to produce a first measured signal value;

generating a first channel quality indicator value from the first measured signal value according to a first function which uses at least the first measured signal value as an input;

transmitting the first channel quality indicator value, wherein transmitting the first channel quality indicator value includes;

incorporating the first channel quality indicator value into a first message; and

transmitting the first message over a wireless communications link;

measuring at least one of an amplitude or a phase of a second pilot signal corresponding to a second pilot tone to produce a second measured signal value, the second pilot signal having a different transmission power than the first pilot signal;

generating a second channel quality indicator value from the second measured signal value according to a second function which uses at least the second measured signal value as an input; and

transmitting the second channel quality indicator value, wherein transmitting the second channel quality indicator value includes;

incorporating the second channel quality indicator value into the first message; and

transmitting the second channel quality indicator value with the first value in the first message over the wireless communications link.

2. The method of claim 1, wherein at least one of the first or second pilot signals is a NULL signal transmitted with zero power.

3. The method of claim 1, wherein generating a first channel quality indicator value from the first signal measurement value according to a first function includes:

estimating the power included in at least one of the first pilot signal or second pilot signal.

4. The method of claim 3, wherein generating a second channel quality indicator value from the second signal measurement value according to a second function includes:

estimating a received power included in at least the second pilot signal.

5. The method of claim 3, wherein generating a second channel quality indicator value from the second measured signal value according to a second function further includes:

estimating a signal to noise ratio of the second pilot signal.

6. The method of claim 1, wherein generating a first channel quality indicator value from the first measured signal value according to a first function includes:

estimating a signal to noise ratio of the first pilot signal.

7. The method of claim 6, wherein generating a second channel quality indicator value from the second measured signal value according to a second function includes:

estimating a signal to noise ratio of the second pilot signal.

8. The method of claim 1, wherein the first and second pilot tones are received during different non-overlapping time periods.

9. The method of claim 8, wherein the first and second pilot tones correspond to the same frequency.

10. The method of claim 1, wherein the first and second pilot tones are received during the same time period, the first and second pilot tones corresponding to different frequencies.

11. The method of claim 1, further comprising:

repeatedly performing the steps of;

measuring a first pilot signal to produce a first measured signal value;

generating a first channel quality indicator value;

incorporating the first channel quality indicator value into a first message;

transmitting the first message over a wireless communications link;

measuring a second pilot signal;

generating a second channel quality indicator value;

incorporating the second channel quality indicator value into a second message which is different from the first message; and

transmitting the second message over the wireless communications link.

12. The method of claim 11, further comprising:

periodically repeating the steps of transmitting the first channel quality indicator value and the second channel quality indicator value to transmit the corresponding values generated by repeatedly performing the measuring and generating steps, the generated first and second channel quality indicator values being transmitted in an interleaved manner over time.

13. The method of claim 12, wherein the interleaved manner includes alternating transmission of the first and second messages.

14. The method of claim 11, wherein the first and second messages are transmitted using communications channel segments dedicated to carrying channel quality indicator values, the messages carrying no explicit message types to indicate the messages are to report channel quality values.

15. The method of claim 14, wherein the first and second messages are transmitted during pre-selected dedicated time slots dedicated for use by the wireless terminal, wherein dedication of the dedicated time slots precludes other wireless terminals using the dedicated time slots.

16. The method of claim 1, wherein the wireless terminal is located in a first sector of a sectorized cell in which each sector uses a same set of tones, the step of measuring at least one of an amplitude or a phase of a first pilot signal to produce a first measured signal value including:

performing the first pilot signal measurement during a time period during which a sector located adjacent the first sector transmits another pilot signal on a same tone as the first pilot but using a different pre-selected transmission power from the pre-selected transmission power used to transmit the first pilot signal.

21. The method of claim 16, further comprising:

determining relative position of the wireless terminal to at least two adjacent sectors to the sector in which the wireless terminal is located based on the first and second signal measurements; and

transmitting position information indicating a relative position to a sector boundary to a base station.

22. The method of claim 21, further comprising:

selecting channel information to be transmitted to the base station as a function of the relative position to a sector boundary.

23. The method of claim 22, wherein different channel condition information is transmitted when the wireless terminal is near a first sector boundary than when the wireless terminal is near a second sector boundary.

24. The method of claim 16, wherein the first channel quality indicator value is a function of a ratio of channel gain of an interfering sector and the sector in which the wireless terminal is located.

25. The method of claim 16, wherein the second signal measurement is made during a time period during which each of the sectors transmits a NULL on the second tone;

and

wherein the second channel quality indicator value is a measurement of noise on the second tone during transmission of the NULL by each of the sectors of the cell on the second tone.

26. The method of claim 16, wherein the method is further directed to using channel quality information to control transmission power in a sector of a cell, the method comprising:

operating a base station to receive the first and second channel quality indicator values; and

operating the base station to calculate, from the first and second channel quality indicator values, an amount of transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein calculating the amount of transmission power comprises employing at least two different channel quality indicator values to determine the amount of transmission power.

27. The method of claim 26, further comprising:

periodically repeating the step of operating the base station to calculate the amount of transmission power using a different set of first and second channel quality indicator values received from the wireless terminal, each different set of first and second channel quality indicator values corresponding to a different symbol time during which the first and second pilot signal measurements were made.

17. The method of 16, wherein the another pilot signal is a NULL pilot signal and wherein the different pre-selected transmission power used to transmit the another pilot signal during the time period is zero.

18. The method of claim 17, wherein the second step of measuring at least one of an amplitude or a phase of a second pilot signal to produce a second measured signal value, includes:

performing the second pilot signal measurement during a time period during which a sector located adjacent the first sector transmits an additional pilot signal on a same tone as the second pilot using the same pre-selected transmission power as the pre-selected transmission power used to transmit the second pilot signal.

19. The method of claim 18, wherein the first and second pilot signal measurements are performed at substantially the same time.

20. The method of claim 19, further comprising:

measuring, at said same time, power received on a third tone on which no signals are transmitted during said same time, said same time being a symbol period used to transmit one symbol.

28. A wireless terminal, the wireless terminal including:

receiver means for receiving pilot signals;

measuring means for measuring at least one of an amplitude or a phase of a first pilot signal to produce a first measured signal value and at least one of an amplitude or a phase of a second pilot signal to produce a second measured signal value;

channel quality indicator value generation means for generating a first channel quality indicator value from the first measured signal value according to a first function which uses at least the first measured signal value as an input and generates a second channel quality indicator value from the second measured signal value according to a second function which uses at least the second measured signal value as an input, wherein the channel quality indicator value generation means includes the second channel quality indicator value in the first message; and

transmitter means for transmitting the first and second channel quality indicator values.

29. The wireless terminal of claim 28, wherein the channel quality indicator value generation means includes software instructions for controlling a processing device to:

estimate received power included in at least one of the first pilot signal or the second pilot signal.

30. The wireless terminal of claim 29, wherein the channel quality indicator value generation means further includes additional software instructions for controlling the processing device to:

estimate received power included in at least the second pilot signal.

31. The wireless terminal of claim 29, wherein the channel quality indicator value generation means further includes additional software instructions for controlling the processing device to:

estimate a signal to noise ratio of the second pilot signal.

32. The wireless terminal of claim 29, wherein the transmitter means includes:

message generation means for generating a first message including the first channel quality indicator value.

33. The wireless terminal of claim 32, wherein the message generation means includes machine executable instructions for controlling a machine to generate a second message including the second channel quality indicator value.

34. The wireless terminal of claim 32, further comprising:

means for determining a position of the wireless terminal relative to a sector boundary from received signals.

35. The wireless terminal of claim 34, wherein the message generation means includes position information in the first message.

36. A base station, comprising:

a receiver for receiving at least two channel quality indicator values from a wireless terminal; and

means for determining from at least two different channel quality indicator values a transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein the at least two different channel quality indicator values correspond to different power signal measurements made by the wireless terminal, the different power signal measurements corresponding to different signal components but a same period of time, the determined transmission power being a function of the at least two different channel quality indicator values.

37. The base station of claim 36, further comprising:

means for transmitting a signal to the wireless terminal using a transmission power determined from the at least two different channel quality indicator values.

38. The base station of claim 37, further comprising:

means for extracting the at least two different channel quality values from a single message received from the wireless terminal.

39. The base station of claim 37, further comprising:

means for extracting the at least two different channel quality values from two separate messages received from the wireless terminal.

40. The base station of claim 36, further comprising:

means for receiving channel quality indicator information indicating a position of the wireless terminal relative to a second boundary included in a multi-sector cell.

41. The base station of claim 36, further comprising:

a multi-sector transmit antenna for transmitting pilot signals into a plurality of sectors of a cell at a same time; and

a transmitter coupled to the multi-sector antenna for supplying pilot signals to the multi-sector antenna for transmission, the plurality of sectors of the cell using a same set of tones for pilot signals, the pilot signals being transmitted at substantially the same time in each of the sectors, the wireless terminal being located in one of the multiple sectors.

42. A device comprising a processor configured to control the device to implement a channel quality reporting method, the method comprising:

measuring at least one of an amplitude or a phase of a first pilot signal corresponding to a first pilot tone to produce a first measured signal value;

generating a first channel quality indicator value from the first measured signal value according to a first function which uses at least the first measured signal value as an input;

transmitting the first channel quality indicator value, wherein transmitting the first channel quality indicator value includes;

incorporating the first channel quality indicator value into a first message; and

transmitting the first message over a wireless communications link;

measuring at least one of an amplitude or a phase of a second pilot signal corresponding to a second pilot tone to produce a second measured signal value, the second pilot signal having a different transmission power than that of the first pilot signal;

generating a second channel quality indicator value from the second measured signal value according to a second function which uses at least the second measured signal value as an input; and

transmitting the second channel quality indicator value, wherein transmitting the second channel quality indicator value includes;

incorporating the second channel quality indicator value into the first message; and

transmitting the second channel quality indicator value with the first value in the first message over the wireless communications link.

43. The device of claim 42, wherein at least one of the first or second pilot signals is a NULL signal transmitted with zero power.

44. The device of claim 42, wherein generating a first channel quality indicator value from the first signal measurement value according to a first function includes:

estimating power included in at least one of the first pilot signal or the second pilot signal.

45. A non-transitory computer readable medium embodying computer executable instructions for controlling a wireless terminal to implement a channel quality reporting method, the method comprising:

measuring at least one of an amplitude or a phase of a first pilot signal corresponding to a first pilot tone to produce a first measured signal value;

generating a first channel quality indicator value from the first measured signal value according to a first function which uses at least the first measured signal value as an input;

transmitting the first channel quality indicator value, wherein transmitting the first channel quality indicator value includes;

incorporating the first channel quality indicator value into a first message; and

transmitting the first message over a wireless communications link;

measuring at least one of an amplitude or a phase of a second pilot signal corresponding to a second pilot tone to produce a second measured signal value, the second pilot signal having a different transmission power than that of the first pilot signal;

generating a second channel quality indicator value from the second measured signal value according to a second function which uses at least the second measured signal value as an input; and

transmitting the second channel quality indicator value, wherein transmitting the second channel quality indicator value includes;

incorporating the second channel quality indicator value into the first message; and

transmitting the second channel quality indicator value with the first value in the first message over the wireless communications link.

46. The non-transitory computer readable medium of claim 45, wherein at least one of the first pilot signal or the second pilot signal is a NULL signal transmitted with zero power.

47. The non-transitory computer readable medium of claim 45, wherein generating a first channel quality indicator value from the first signal measurement value according to a first function includes:

estimating power included in at least one of the first pilot signal or the second pilot signal.

48. A wireless terminal, the wireless terminal including:

a receiver for receiving pilot signals;

a measuring module for measuring at least one of an amplitude or a phase of a first pilot signal to produce a first measured signal value and at least one of an amplitude or a phase of a second pilot signal to produce a second measured signal value;

a channel quality indicator value generation module for generating a first channel quality indicator value from the first measured signal value according to a first function which uses at least the first measured signal value as an input and generates a second channel quality indicator value from the second measured signal value according to a second function which uses at least the second measured signal value as an input, wherein the channel quality indicator value generation module includes the second channel quality indicator value in the first message; and

a transmitter for transmitting the first and second channel quality indicator values.

49. The wireless terminal of claim 48, wherein the transmitter includes:

a message generation module for generating a first message including the first channel quality indicator value.

50. The wireless terminal of claim 49, wherein the message generation module includes the second channel quality indicator value in the first message.

51. A method of operating a base station, the method comprising:

receiving at least two channel quality indicator values from a wireless terminal; and

determining from at least two different channel quality indicator values a transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein the at least two different channel quality indicator values correspond to different power signal measurements made by the wireless terminal, the different power signal measurements corresponding to different signal components but a same period of time, the determined transmission power being a function of the at least two different channel quality indicator values.

52. The method of claim 51, further comprising:

transmitting a signal to the wireless terminal using a transmission power determined from the at least two different channel quality indicator values.

53. The method of claim 52, further comprising:

extracting the at least two different channel quality indicator values from a single message received from the wireless terminal.

54. The method of claim 51, further comprising:

transmitting pilot signals into a plurality of sectors of a cell at substantially the same time using a multi-sector transmit antenna, a same set of tones being used for pilot signals in each of the plurality of sectors, the pilot signals being transmitted at substantially the same time in each of the plurality of sectors, the wireless terminal being located in one of the plurality of sectors.

55. A device comprising a processor configured to control a base station to implement a method, the method comprising:

receiving at least two channel quality indicator values from a wireless terminal; and

determining from at least two different channel quality indicator values a transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein the at least two different channel quality indicator values correspond to different power signal measurements made by the wireless terminal, the different power signal measurements corresponding to different signal components but a same period of time, the determined transmission power being a function of the at least two different channel quality indicator values.

56. The device of claim 55, wherein the method further comprises:

transmitting a signal to the wireless terminal using a transmission power determined from the at least two different channel quality indicator values.

57. The device of claim 56, wherein the method further comprises:

extracting the at least two different channel quality indicator values from a single message received from the wireless terminal.

58. A non-transitory computer readable medium embodying computer executable instructions for controlling a base station to implement a method, the method comprising:

receiving at least two channel quality indicator values from a wireless terminal; and

determining from at least two different channel quality indicator values a transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein the at least two different channel quality indicator values correspond to different power signal measurements made by the wireless terminal, the different power signal measurements corresponding to different signal components but a same period of time, the determined transmission power being a function of the at least two channel quality indicator values.

59. The non-transitory computer readable medium of claim 58, wherein the method further comprises:

transmitting a signal to the wireless terminal using a transmission power determined from the at least two different channel quality indicator values.

60. The non-transitory computer readable medium of claim 59, wherein the method further comprises:

extracting the at least two different channel quality indicator values from a single message received from the wireless terminal.

61. A base station comprising:

a receiver module for receiving at least two channel quality indicator values from a wireless terminal; and

a determination module for determining from at least two different channel quality indicator values a transmission power required to achieve a target signal to noise ratio at the wireless terminal, wherein the at least two different channel quality indicator values correspond to different power signal measurements made by the wireless terminal, the different power signal measurements corresponding to different signal components but a same period of time, the determined transmission power being a function of the at least two different channel quality indicator values.

62. The base station of claim 61, further comprising:

a transmitter module for transmitting a signal to the wireless terminal using a transmission power determined from the at least two different channel quality indicator values.

63. The base station of claim 62, further comprising:

a module for extracting the at least two different channel quality indicator values from a single message received from the wireless terminal.