Multi-beam antenna system for high speed data

• US 6,804,521 B2
• Filed: 01/18/2001
• Issued: 10/12/2004
• Est. Priority Date: 01/18/2000
• Status: Expired due to Term

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Tong, Wen, Strawczynski, Leo L., Periyalwar, Shalini S., Royer, Claude
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): D AGOSTA, STEPHEN M
• Application Number:
  US09/764,663
• Publication Number:
  US 20010034236A1
• Time in Patent Office: 1,363 Days
• Field of Search: 455/450, 455/451, 455/448, 455/455, 455/464, 455/63.1, 455/561, 455/278.1, 455/296, 370/230, 370/230.1, 370/282, 370/322, 370/324, 370/326, 370/328, 370/330, 370/332, 370/336, 370/338, 370/341, 370/345, 370/348, 370/350
• 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 cellular wireless communication system, a method of transmitting data from a base station to a plurality of user terminals within a sector serviced by the base station, the method comprising:

dividing the sector geographically into a plurality of user-group areas, wherein each user-group area is serviced via a respective port of a beam forming antenna of the base station;

for each user-group area, transmitting a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

receiving indications of received pilot signal strengths from at least some of the plurality of user terminals;

based noon the received indications of received pilot signal strengths from the plurality of user terminals assigning each reporting user terminal to a respective user-group area; and

temporally synchronizing transmissions of darn from to 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, wherein each pilot signal is uniquely identifiable based upon a respective code.

3. The method of claim 1, wherein receiving indications of received pilot signal strengths from at least some of the plurality of user terminals comprises receiving a plurality of received pilot signal strengths from a user terminal, each received pilot signal strength corresponding to an identified pilot signal.

4. The method of claim 1, 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 1, 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 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.

7. The method of claim 6, 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.

8. The method of claim 1, wherein adjacent user-group areas served by the base station overlap.

9. The method of claim 8, 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.

10. The method of claim 8, 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.

11. The method of claim 1, further comprising temporally coordinating transmissions of data from the base station in adjacent sectors.

12. A method of reducing cross-beam interference in a multi-beam antenna system wherein a base station transmits data to a plurality of user terminals within a sector, the method comprising:

dividing the sector geographically into two geographically adjacent user-group areas, wherein each user group area is serviced via a respective port of a beam forming antenna of the base station;

for each user-group area, transmitting a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

receiving indications of received pilot signal strengths from at least some of the plurality of user terminals;

based upon the received indications of received pilot signal strengths from the plurality of user terminals assigning each reporting user terminal to a respective user-group area;

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.

13. A The method of claim 12, wherein each pilot signal is uniquely identifiable based upon a respective code.

14. The method of claim 12, wherein receiving indications of received pilot signal strengths from at least some of the plurality of user terminal comprises receiving a plurality of received pilot signal strengths from a user terminal, each received pilot signal strength corresponding to an identified pilot signal.

15. The method of claim 12, 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.

16. The method of claim 15, further comprising suppressing transmission of the pilot signal in a user-group area when data is not transmitted within the user-group area.

17. The method of claim 12, 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.

18. The method of claim 17, 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.

19. The method of claim 18, 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.

20. The method of claim 12, wherein the first user-group area geographically overlaps with the second user-group area.

21. The method of claim 20, 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.

22. The method of claim 20, 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.

23. A method of operating a user terminal within a cellular 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, wherein each geographically distinct user-group area is serviced via a respective port of a beam forming antenna of the base station, and wherein a plurality of geographically distinct user-group areas makes up a sector serviced by the base station;

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.

24. The method of claim 23, wherein the channel quality indication comprises a carrier to interference ratio.

25. The method of claim 23, wherein the channel quality indication comprises a maximum data rate supportable on a corresponding forward link channel.

26. The method of claim 23, 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 flint user-group area without considering a pilot signal corresponding to a geographically adjacent second user-group area.

27. The method of claim 23, wherein:

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

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

28. The method of claim 23, 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.

29. The method of claim 23, 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.

30. The method of claim 29, wherein the indication is received on a control channel.

31. The method of claim 23, 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.

32. A base station that transmits data to a plurality of user terminals within a sector of a corresponding cellular wireless communication system, 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 sector geographically into a plurality of user-group areas, wherein each user-group area is serviced via a respective port of a beam forming antenna of the base station;

for each user-group area, transmit a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

receive indications of received pilot signal strengths from at least some of the plurality of user terminals;

based upon the received indications of received pilot signal strengths from the plurality of user terminals assign each reporting user terminal to a respective user-group area; and

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

33. A base station that transmits data to a plurality of user terminals within a sector, 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 sector geographically into two geographically adjacent user-group areas, wherein each user group area is serviced via a respective port of a beam forming antenna of the base station;

for each user-group area, transmit a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

receive indications of received pilot signal strengths from at least some of the plurality of user terminals;

based upon the received indications of received pilot signal strengths from the plurality in user terminals assign each reporting user terminal to a respective user-group area;

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.

34. 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 sector, 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, wherein each user group area is serviced via a respective port of a beam forming antenna of the base station;

a set of instructions executed by the base station that cause the base station to, for each user-group area, transmit a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

a set of instructions executed by the base station that cause the base station to receive indications of received pilot signal strengths from at least some of the plurality of user terminals;

a set of instructions executed by the base station that cause the base station to, based upon the received indications of received pilot signal strengths from the plurality of user terminals assigning each reporting user terminal to a respective user-group area; 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.

35. 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 sector, the plurality of software instructions comprising:

a set of instructions executed by the base station that cause the base station to divide the sector geographically into two geographically adjacent user-group areas, wherein each user group area is serviced via a respective port of a beam forming antenna of the base station

a set of instructions executed by the base station that cause the base station to receive user-group area, transmit a uniquely identifiable pilot signal via a respective port of the beam forming antenna of the base station;

a set of instructions executed by the base station that cause the base station to receive indications of received pilot signal strengths from at least some of the plurality of user terminals;

a set of instructions executed by the base station that cause the base station to, based upon the received indications of received pilot signal strengths from the plurality of user terminals assigning each reporting user terminal in a respective user-group area; 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.

36. 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 cawing 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, wherein each geographically distinct user-group area is serviced via a respective port of a beam forming antenna of the base station, and wherein a plurality of geographically distinct user-group areas makes up a sector;

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

report at best 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.

37. 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, wherein each geographically distinct user-group area is serviced via a respective port of a beam forming antenna of the base station, and wherein a plurality of geographically distinct user-group areas makes up a sector currently servicing the user terminal;

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 seine time to two geographically adjacent user-group areas.

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

receiving a plurality of pilot signals, wherein each pilot corresponds to a geographically distinct user-group area that is serviced via a respective port of a beam forming antenna of a servicing base station, and wherein a plurality of geographically distinct user-group areas makes up a sector serviced by a base station;

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.