Multi-beam antenna system for high speed data

• US 20010034236A1
• Filed: 01/18/2001
• Published: 10/25/2001
• Est. Priority Date: 01/18/2000
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Tong, Wen, Royer, Claude, Periyalwar, Shalini S., Strawczynski, Leo L.
• Granted Patent: US 6,804,521 B2
• Time in Patent Office: Days
• US Class Current: 455/450
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A system and method reduces cross-beam interference in multi-beam wireless data-transmission system through temporal separation of the multiple beams. A sector of a cell is geographically divided such that a number of beam patterns correspond to a number of user-group areas. For example, the sector can be divided such that four user-group areas are created. The number of groups and beam patterns can be increased or decreased. Forward link transmissions from a base station to a plurality of user terminals are patterned such that transmissions to adjacent user-group areas do not occur during the same time intervals. According to one operation, pilot signal transmissions are suppressed within a beam if no data is transmitted during a corresponding temporal period. According to another operation, temporal guard slots are introduced to avoid inter-cell interference. Further, in some operations, user terminals report to the base station to indicate one or more preferred user-group areas for their inclusion.

Claims

1. In a wireless communication system, a method of transmitting data from a base station to a plurality of user terminals within a transmission area serviced by the wireless communication system, the method comprising:

dividing the transmission area geographically into a plurality of user-group areas; and

temporally synchronizing transmissions of data from the base station to the plurality of user-group areas such that the base station does not transmit data at the same time to two geographically adjacent user-group areas.

2. The method of

claim 1

, further comprising for each of the plurality of user-group areas, transmitting a pilot signal to the plurality of user terminals.

3. The method of

claim 2

, further comprising:

receiving at least one channel quality indication from a user terminal based upon a received strength of at least one pilot signal; and

assigning the user terminal to a user-group area of the plurality of user-group areas based upon received channel quality indications.

4. The method of

claim 2

, further comprising suppressing the transmission of a pilot signal to a user-group area for a time period when data is not transmitted within the user-group area.

5. The method of

claim 2

, further comprising suppressing transmission of the pilot signal in a user-group area when data is not transmitted within the user-group area.

6. The method of

claim 1

, wherein adjacent user-group areas served by the base station overlap.

7. The method of

claim 1

, wherein a first user-group area served by the base station is geographically adjacent to a second user-group area served by a second base station.

8. The method of

claim 7

, further comprising temporally synchronizing transmissions of data from the base station to the first user-group area with transmissions of data from the second base station to the second user-group such that the transmissions to the first user-group and the transmissions to the second-user group do not temporally overlap.

9. The method of

claim 1

, wherein adjacent user-group areas served by the base station overlap.

10. The method of

claim 9

, further comprising, for a user terminal residing within overlapping user-group areas, transmitting data to the user terminal within a user-group area of the overlapping user-group areas that has a better respective reported channel quality indication.

11. The method of

claim 9

, further comprising, for a user terminal residing within overlapping user-group areas, transmitting data to the user terminal within a user-group area of the overlapping user-group areas to equalize load within the overlapping user-group areas.

12. The method of

claim 1

, wherein the transmission area includes adjacent sectors.

13. A method of reducing cross-beam interference in a multi-beam antenna system wherein a base station transmits data to users within a transmission sector, the method comprising:

dividing the transmission sector geographically into two geographically adjacent user-group areas; and

wherein data is transmitted from the base station to the two geographically adjacent user-group areas by transmitting data in two alternating sets of time slots, a first time slot of the two alternating sets of time slots being used by the base station to transmit data to a first user-group area of the two geographically adjacent user-group areas and a second time slot of the two alternating sets of time slots being used to transmit data to a second user-group area of the two geographically adjacent user-group areas, and

wherein the two alternating sets of time slots do not overlap temporally.

14. The method of

claim 13

, further comprising, for each of the two user-group areas, transmitting a pilot signal to the plurality of user terminals.

15. The method of

claim 14

, further comprising:

receiving a channel quality indication for each of the two user-group areas from a user terminal based upon received strengths of respective pilot signals; and

transmitting data to the user terminal in a user-group area of the two user-group areas based upon the received channel quality indications.

16. The method of

claim 14

, further comprising suppressing the transmission of a pilot signal to the first user-group area for a time period when data is not transmitted within the first user-group area.

17. The method of

claim 16

, further comprising suppressing transmission of the pilot signal in a user-group area when data is not transmitted within the user-group area.

18. The method of

claim 13

, wherein the first user-group area served by the base station is geographically adjacent to a third user-group area served by a second base station.

19. The method of

claim 18

, further comprising temporally synchronizing transmissions of data from the base station to the first user-group area with transmissions of data from the second base station to the third user-group such that the transmissions to the first user-group and the transmissions to the third-user group do not temporally overlap.

20. The method of

claim 19

, wherein the transmissions of data from the second base station to the third user-group further do not temporally overlap with the transmissions from the base station to the second user-group.

21. The method of

claim 13

, wherein the first user-group area geographically overlaps with the second user-group area.

22. The method of

claim 21

, further comprising, for a user terminal residing within the overlapping first and second user-group areas, transmitting data to the user terminal within a user-group area of the overlapping first and second user-group areas that has a better respective reported channel quality indication.

23. The method of

claim 21

, further comprising, for a user terminal residing within the overlapping first and second user-group areas, transmitting data to the user terminal within a user-group area of the overlapping first and second user-group areas to equalize load within the overlapping first and second user-group areas.

24. A method of operating a user terminal within a wireless communication system to receive transmissions of data, the method comprising:

receiving a plurality of pilot signals from a base station, wherein each pilot signal corresponds to a geographically distinct user-group area;

determining a plurality of channel quality indications, wherein each channel quality indication corresponds to a pilot signal;

reporting at least one channel quality indication to the base station; and

receiving one of a plurality of temporally synchronized transmissions of data from the base station, wherein the plurality of temporally synchronized transmissions of data correspond to a respective plurality of geographically distinct user-group areas, wherein the base station does not transmit data at the same time to two geographically adjacent user-group areas.

25. The method of

claim 24

, wherein the channel quality indication comprises a carrier to interference ratio.

26. The method of

claim 24

, wherein the channel quality indication comprises a maximum data rate supportable on a corresponding forward link channel.

27. The method of

claim 24

, wherein determining a plurality of channel quality indications comprises:

measuring the strength of each received pilot signal; and

determining a channel quality indication for a first pilot signal corresponding to a first user-group area without considering a pilot signal corresponding to a geographically adjacent second user-group area.

28. The method of

claim 24

, wherein:

the geographically adjacent user-group areas served by the base station overlap; and

the user terminal is serviced by a user-group area of the adjacent user-group areas that has a relatively better channel quality.

29. The method of

claim 24

, wherein:

the geographically adjacent user-group areas served by the base station overlap; and

the user terminal is serviced by a user-group area of the adjacent user-group areas based upon user-group area load.

30. The method of

claim 24

, further comprising interacting with the base station to receive an indication that indicates in which user-group area the user terminal is to receive transmissions of data.

31. The method of

claim 30

, wherein the indication is received on a control channel.

32. The method of

claim 24

, further comprising:

receiving transmissions from both of the geographically adjacent user-group areas;

from the contents of each of the transmissions, determining that one of the transmissions includes a transmission of data for the user terminal; and

receiving the transmission of data in the one of the transmissions.

33. A base station that transmits data to a plurality of user terminals within a transmission area, the base station comprising:

an antenna;

a Radio Frequency unit coupled to the antenna; and

at least one digital processor coupled to the Radio Frequency unit that executes software instructions causing the base station to;

divide the transmission area geographically into a plurality of user-group areas; and

temporally synchronize transmissions of data to the plurality of user-group areas such that the base station does not transmit data at the same time to two geographically adjacent user-group areas.

34. A base station that transmits data to a plurality of user terminals within a transmission area, the base station comprising:

an antenna;

a Radio Frequency unit coupled to the antenna; and

at least one digital processor coupled to the Radio Frequency unit that executes software instructions causing the base station to;

divide the transmission sector geographically into two geographically adjacent user-group areas; and

transmit data to the two geographically adjacent user-group areas by transmitting data in two alternating sets of time slots, a first time slot of the two alternating sets of time slots being used by the base station to transmit data to a first user-group area of the two geographically adjacent user-group areas and a second time slot of the two alternating sets of time slots being used to transmit data to a second user-group area of the two geographically adjacent user-group areas, and

wherein the two alternating sets of time slots do not overlap temporally.

35. A plurality of software instructions stored on a media that, upon execution by a base station, cause the base station to transmits data to a plurality of user terminals within a transmission area, the plurality of software instructions comprising:

a set of instructions executed by the base station that cause the base station to divide the transmission area geographically into a plurality of user-group areas; and

a set of instructions executed by the base station that cause the base station to temporally synchronize transmissions of data to the plurality of user-group areas such that the base station does not transmit data at the same time to two geographically adjacent user-group areas.

36. A plurality of software instructions stored on a media that, upon execution by a base station, cause the base station to transmit data to a plurality of user terminals within a transmission area, the plurality of software instructions comprising:

a set of instructions executed by the base station that cause the base station to divide the transmission sector geographically into two geographically adjacent user-group areas; and

a set of instructions executed by the base station that cause the base station to transmit data to the two geographically adjacent user-group areas by transmitting data in two alternating sets of time slots, a first time slot of the two alternating sets of time slots being used by the base station to transmit data to a first user-group area of the two geographically adjacent user-group areas and a second time slot of the two alternating sets of time slots being used to transmit data to a second user-group area of the two geographically adjacent user-group areas, and

wherein the two alternating sets of time slots do not overlap temporally.

37. A user terminal that acts as a wireless receiver to wirelessly receive a data packet from a base station acting as a transmitter, the user terminal comprising:

an antenna;

a Radio Frequency unit coupled to the antenna; and

a digital processor coupled to the Radio Frequency unit that executes software instructions causing the user terminal to;

receive a plurality of pilot signals from a base station, wherein each pilot signal corresponds to a geographically distinct user-group area;

determine a plurality of channel quality indications, wherein each channel quality indication corresponds to a pilot signal;

report at least one channel quality indication to the base station; and

receive one of a plurality of temporally synchronized transmissions of data from the base station, wherein the plurality of temporally synchronized transmissions of data correspond to a respective plurality of geographically distinct user-group areas, wherein the base station does not transmit data at the same time to two geographically adjacent user-group areas.

38. A plurality of software instructions stored on a media that, upon execution by a user terminal, causes the user terminal to receive transmissions of data, the plurality of software instructions comprising:

a set of instructions executed by the user terminal that cause the user terminal to receive a plurality of pilot signals from a base station, wherein each pilot signal corresponds to a geographically distinct user-group area;

a set of instructions executed by the user terminal that cause the user terminal to determine a plurality of channel quality indications, wherein each channel quality indication corresponds to a pilot signal;

a set of instructions executed by the user terminal that cause the user terminal to report at least one channel quality indication to the base station; and

a set of instructions executed by the user terminal that cause the user terminal to receive one of a plurality of temporally synchronized transmissions of data from the base station, wherein the plurality of temporally synchronized transmissions of data correspond to a respective plurality of geographically distinct user-group areas, wherein the base station does not transmit data at the same time to two geographically adjacent user-group areas.

39. A method of operating a user terminal within a wireless communication system to calculate forward link channel qualities, the method comprising:

receiving a plurality of pilot signals;

measuring the strength of each of the plurality of pilot signals;

segregating the plurality of pilot signals into a first plurality of pilot signals corresponding to forward traffic channels that transmit during first time intervals and a second plurality of pilot signals corresponding to forward traffic channels that transmit during second time intervals, wherein the first time intervals do not overlap with the second time intervals;

for each pilot signal of the first plurality of pilot signals determining a corresponding forward link channel quality based only upon measured strengths of the first plurality of pilot signals; and

for each pilot signal of the second plurality of pilot signals, determining a corresponding forward link channel quality based only upon measured strengths of the second plurality of pilot signals.