Wireless communication method and apparatus for selecting and reselecting cells based on measurements performed using directional beams and an omni-directional beam pattern

• US 20050176468A1
• Filed: 12/30/2004
• Published: 08/11/2005
• Est. Priority Date: 02/07/2004
• Status: Active Grant

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Iacono, Ana Lucia, Stern-Berkowitz, Janet
• Granted Patent: US 7,324,817 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04B 7/0871 using different reception schemes, at least one of them being a diversity reception scheme
• CPC Class Codes: H04B 7/088 using beam selection
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

A wireless communication method and apparatus for selecting and reselecting cells used by a wireless transmit/receive unit (WTRU) in a wireless multi-cell communication system. The WTRU includes a switched beam antenna configured to form a plurality of directional beams and an omni-directional beam pattern. The WTRU measures signals from a plurality of cells using the directional beams and the omni-directional beam pattern. The WTRU selects and registers with the cell having the strongest signal. In one embodiment, the WTRU selects a directional beam which has the strongest signal and uses it as an active beam to communicate with the selected cell. In another embodiment, the WTRU selects a cell/beam combination and registers with the selected cell using the selected beam. In yet another embodiment, the WTRU initiates a handoff to a neighboring cell that has a better signal measurement result than the selected cell.

Claims

1. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell selection method comprising:

(a) the WTRU performing measurements on signals received from the cells using the omni-directional beam pattern;

(b) the WTRU selecting and registering with a cell having the strongest signal based on the results of the measurements performed in step (a);

(c) the WTRU performing measurements on signals received from the selected cell using the directional beams; and

(d) the WTRU selecting the directional beam having the strongest signal as an active beam used for communicating with the selected cell based on the results of the measurements performed in step (c).

2. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell selection method comprising:

(a) the WTRU performing measurements on signals received from the cells using either the directional beams or the omni-directional beam pattern;

(b) the WTRU selecting a cell/beam combination having the strongest signal based on the results of the measurements performed in step (a); and

(c) the WTRU registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

3. The method of claim 2 further comprising:

(d) if the selected beam is not an omni-directional beam pattern, comparing a measurement result which indicates the best directional beam/cell combination with the measurement result which indicates the best omni-directional beam pattern/cell combination.

4. The method of claim 3 wherein a directional beam is selected if the measurement result associated with the directional beam exceeds the measurement result associated with the omni-directional beam pattern by a predetermined threshold, and the omni-directional beam pattern is selected when the measurement result associated with the directional beam does not exceed the measurement result associated with the omni-directional beam pattern.

5. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell selection method comprising:

(a) the WTRU performing measurements on signals received from the cells using the omni-directional beam pattern;

(b) the WTRU selecting a subset of the cells based on the results of the measurements performed in step (a);

(c) the WTRU performing measurements on signals received from each of the cells using each of the directional beams;

(d) the WTRU selecting a cell/beam combination having the strongest signal based on the results of the measurements performed in step (c); and

(e) the WTRU registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

6. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell reselection method comprising:

(a) the WTRU registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(b) the WTRU selecting a subset of the neighboring cells based on the results of the measurements performed in step (a);

(c) the WTRU performing measurements on signals received from each of the neighboring cells in the subset using either the directional beams or the omni-directional beam pattern; and

(d) if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell, the WTRU initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result.

7. The method of claim 6 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

8. The method of claim 7 wherein the predetermined threshold is zero.

9. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell reselection method comprising:

(a) the WTRU registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(b) the WTRU selecting a first subset of the neighboring cells based on the results of the measurements performed in step (a);

(c) the WTRU performing measurements on signals received from each of the neighboring cells in the first subset using omni-directional beam pattern;

(d) the WTRU selecting a second subset of the neighboring cells in the first subset based on the results of the measurements performed in step (c);

(e) the WTRU performing measurements on signals received from each of the neighboring cells in the second subset using the directional beams; and

(f) if the strongest measurement result of the signals received from the neighboring cells in the second subset is higher than the best measurement result of signals received from the selected cell, the WTRU initiating a cell handoff from the selected cell to a neighboring cell in the second subset having the strongest measurement result.

10. The method of claim 9 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the second subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

11. The method of claim 10 wherein the predetermined threshold is zero.

12. In a wireless communication system including at least one wireless transmit/receive unit (WTRU) and a plurality of cells, the WTRU being configured to include a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, a cell reselection method comprising:

(a) the WTRU registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using the omni-directional beam pattern;

(b) the WTRU selecting a subset of the neighboring cells based on the results of the measurements performed in step (a);

(c) the WTRU performing measurements on signals received from each of the neighboring cells in the subset using the directional beams; and

(d) if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell, the WTRU initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result.

13. The method of claim 12 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

14. The method of claim 12 wherein the predetermined threshold is zero.

15. In a wireless communication system including a plurality of cells, a wireless transmitt receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for performing measurements on signals received from the cells using the omni-directional beam pattern;

(c) means for selecting and registering with a cell having the strongest signal based on the results of the measurements performed using the omni-directional beam pattern;

(d) means for performing measurements on signals received from the selected cell using the directional beams; and

(e) means for selecting the directional beam having the strongest signal as an active beam used for communicating with the selected cell based on the results of the measurements performed using the directional beams.

16. In a wireless communication system including a plurality of cells, a wireless transmit/receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for performing measurements on signals received from the cells using either the directional beams or the omni-directional beam pattern;

(c) means for selecting a cell/beam combination having the strongest signal based on the results of the measurements performed using either the directional beams or the omni-directional beam pattern; and

(d) means for registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

17. The WTRU of claim 16 further comprising:

(e) means for comparing a measurement result which indicates the best directional beam/cell combination with the measurement result which indicates the best omni-directional beam pattern/cell combination, if the selected beam is not an omni-directional beam pattern.

18. The WTRU of claim 17 wherein a directional beam is selected if the measurement result associated with the directional beam exceeds the measurement result associated with the omni-directional beam pattern by a predetermined threshold, and the omni-directional beam pattern is selected when the measurement result associated with the directional beam does not exceed the measurement result associated with the omni-directional beam pattern.

19. In a wireless communication system including a plurality of cells, a wireless transmitt receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for performing measurements on signals received from the cells using the omni-directional beam pattern;

(c) means for selecting a subset of the cells based on the results of the measurements using the omni-directional beam pattern;

(d) means for performing measurements on signals received from each of the cells using each of the directional beams;

(e) means for selecting a cell/beam combination having the strongest signal based on the results of the measurements performed using each of the directional beams; and

(f) means for registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

20. In a wireless communication system including a plurality of cells, a wireless transmit/receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(c) means for selecting a subset of the neighboring cells based on the results of the measurements performed using the active beam;

(d) means for performing measurements on signals received from each of the neighboring cells in the subset using either the directional beams or the omni-directional beam pattern; and

(e) means for initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell.

21. The WTRU of claim 20 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

22. The WTRU of claim 21 wherein the predetermined threshold is zero.

23. In a wireless communication system including a plurality of cells, a wireless transmit/receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(c) means for selecting a first subset of the neighboring cells based on the results of the measurements performed using the active beam;

(d) means for performing measurements on signals received from each of the neighboring cells in the first subset using omni-directional beam pattern;

(e) means for selecting a second subset of the neighboring cells in the first subset based on the results of the measurements using the omni-directional beam pattern;

(f) means for performing measurements on signals received from each of the neighboring cells in the second subset using the directional beams; and

(g) means for initiating a cell handoff from the selected cell to a neighboring cell in the second subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the second subset is higher than the best measurement result of signals received from the selected cell.

24. The WTRU of claim 23 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the second subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

25. The WTRU of claim 24 wherein the predetermined threshold is zero.

26. In a wireless communication system including a plurality of cells, a wireless transmit/receive unit (WTRU) comprising:

(a) a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern;

(b) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using the omni-directional beam pattern;

(c) means for selecting a subset of the neighboring cells based on the results of the measurements performed using the omni-directional beam pattern;

(d) means for performing measurements on signals received from each of the neighboring cells in the subset using the directional beams; and

(e) means for initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell.

27. The WTRU of claim 26 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

28. The WTRU of claim 27 wherein the predetermined threshold is zero.

29. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for performing measurements on signals received from the cells using the omni-directional beam pattern;

(b) means for selecting and registering with a cell having the strongest signal based on the results of the measurements performed using the omni-directional beam pattern;

(c) means for performing measurements on signals received from the selected cell using the directional beams; and

(d) means for selecting the directional beam having the strongest signal as an active beam used for communicating with the selected cell based on the results of the measurements performed using the directional beams.

30. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for performing measurements on signals received from the cells using either the directional beams or the omni-directional beam pattern;

(b) means for selecting a cell/beam combination having the strongest signal based on the results of the measurements performed using either the directional beams or the omni-directional beam pattern; and

(c) means for registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

31. The IC of claim 30 further comprising:

(d) means for comparing a measurement result which indicates the best directional beam/cell combination with the measurement result which indicates the best omni-directional beam pattern/cell combination, if the selected beam is not an omni-directional beam pattern.

32. The IC of claim 31 wherein a directional beam is selected if the measurement result associated with the directional beam exceeds the measurement result associated with the omni-directional beam pattern by a predetermined threshold, and the omni-directional beam pattern is selected when the measurement result associated with the directional beam does not exceed the measurement result associated with the omni-directional beam pattern.

33. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for performing measurements on signals received from the cells using the omni-directional beam pattern;

(b) means for selecting a subset of the cells based on the results of the measurements using the omni-directional beam pattern;

(c) means for performing measurements on signals received from each of the cells using each of the directional beams;

(d) means for selecting a cell/beam combination having the strongest signal based on the results of the measurements performed using each of the directional beams; and

(e) means for registering with the selected cell using the selected beam as an active beam used for communicating with the selected cell.

34. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(b) means for selecting a subset of the neighboring cells based on the results of the measurements performed using the active beam;

(c) means for performing measurements on signals received from each of the neighboring cells in the subset using either the directional beams or the omni-directional beam pattern; and

(d) means for initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell.

35. The IC of claim 34 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

36. The IC of claim 35 wherein the predetermined threshold is zero.

37. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using an active beam normally used to communicate with the selected cell;

(b) means for selecting a first subset of the neighboring cells based on the results of the measurements performed using the active beam;

(c) means for performing measurements on signals received from each of the neighboring cells in the first subset using omni-directional beam pattern;

(d) means for selecting a second subset of the neighboring cells in the first subset based on the results of the measurements using the omni-directional beam pattern;

(e) means for performing measurements on signals received from each of the neighboring cells in the second subset using the directional beams; and

(f) means for initiating a cell handoff from the selected cell to a neighboring cell in the second subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the second subset is higher than the best measurement result of signals received from the selected cell.

38. The IC of claim 37 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the second subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

39. The IC of claim 38 wherein the predetermined threshold is zero.

40. In a wireless communication system including a plurality of cells, an integrated circuit (IC) operating in conjunction with a switched beam antenna for generating a plurality of directional beams and an omni-directional beam pattern, the IC comprising:

(a) means for registering with a selected cell and performing measurements on signals received from cells neighboring the selected cell using the omni-directional beam pattern;

(b) means for selecting a subset of the neighboring cells based on the results of the measurements performed using the omni-directional beam pattern;

(c) means for performing measurements on signals received from each of the neighboring cells in the subset using the directional beams; and

(d) means for initiating a cell handoff from the selected cell to a neighboring cell in the subset having the strongest measurement result if the strongest measurement result of the signals received from the neighboring cells in the subset is higher than the best measurement result of signals received from the selected cell.

41. The IC of claim 40 wherein the cell handoff is initiated if the strongest measurement result of the signals received from the neighboring cells in the subset exceeds the best measurement result of signals received from the selected cell by a predetermined threshold.

42. The IC of claim 41 wherein the predetermined threshold is zero.