Method and apparatus for using switched multibeam antennas in a multiple access communication system

• US 7,742,788 B2
• Filed: 09/25/2003
• Issued: 06/22/2010
• Est. Priority Date: 10/01/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Frank, Colin
• Primary Examiner(s): Pan; Yuwen
• Application Number:
  US10/670,577
• Publication Number:
  US 20040063468A1
• Time in Patent Office: 2,462 Days
• Field of Search: 455/562.1, 455/25, 455/63.4
• US Class Current: 455/562.1
• 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: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

In order to increase a capacity, or a number of mobile stations (MSs), or users, that may engaged in concurrent communication sessions, a communication system is provided that schedules a different MS, or user, in each beam of multiple predetermined, fixed beams associated with a coverage area, in particular a sector. By simultaneously scheduling a user in each beam of the multiple beams, a performance and throughput of communication system is significantly increased over the prior art. In one embodiment of the present invention, a portion of a shared communication channel that is allocated to each MS is concurrently transmitted to each MS via a beam associated with the MS. In other embodiments of the present invention, voice channels, data channels, and control channels associated with each MS scheduled in a beam may be concurrently transmitted to each MS via the beam associated with the MS.

Claims

1. A method for allocating a shared communication channel among a plurality of beams in a communication system comprising a switched beam antenna system, wherein the shared communication channel comprises a plurality of orthogonal codes and wherein the method comprises:

measuring a quality of a propagation channel associated with each beam of the plurality of beams; and

allocating a first portion of the plurality of orthogonal codes to a first beam of the Plurality of beams and a second portion of the plurality of orthogonal codes to a second beam of the plurality of beams, wherein the first and second portions are a function of the measured quality of the propagation channels between a base station and mobile stations in the first beam and between the base station and mobile stations in the second beam.

2. The method of claim 1, further comprising:

scheduling a first mobile station for the first beam;

scheduling a second mobile station for the second beam;

transmitting the first portion of the plurality of orthogonal codes to the first mobile station via in the first beam; and

transmitting the second portion of the plurality of orthogonal codes to the second mobile station via the second beam;

where the first and second portions of the plurality of orthogonal codes are based on the measured quality of the propagation channels between the base station and the first mobile station in the first beam and the quality of the propagation channel between the base station and the second mobile station in the second beam.

3. The method of claim 2, wherein the communication system further comprises a control channel and wherein the method further comprises a step of transmitting the control channel in each of the first beam and the second beam.

4. The method of claim 3, wherein the control channel comprises a first control channel, wherein the communication system further comprises a second control channel that is associated with the second mobile station and not with the first mobile station, and wherein the method further comprises a step of transmitting the second control channel in the second beam but not in the first beam.

5. The method of claim 2, wherein the communication system further comprises a plurality of voice channels and shared data channel and wherein the method further comprises steps of:

transmitting a plurality of voice channels and a portion of the orthogonal codes corresponding to the shared data channel in the first beam; and

transmitting a plurality of voice channels and a portion of the orthogonal codes corresponding to the shared data channel in the second beam.

6. The method of claim 2, further comprising:

maintaining an approximately constant transmit power for the shared communication channel in the first beam; and

maintaining an approximately constant transmit power for the shared communication channel in the second beam.

7. The method of claim 1, wherein the communication system is divided into a plurality of geographic sectors, and wherein each beam of the plurality of beams is transmitted in a same sector of the plurality of sectors.

8. The method of claim 7, further comprising a step of allocating to each beam of the plurality of beams an approximately same proportion of a total transmitted power allocated to the sector that includes the beams.

9. The method of claim 7, further comprising a step of allocating to each beam of the plurality of beams a different proportion of a total transmitted power allocated to the sector that includes the beams than the proportion of the total transmitted power allocated to the other beams of the plurality of beams, where the proportions reflect the average traffic loads within the beams.

10. The method of claim 1, further comprising:

transmitting user information via the shared communication channel and the first beam; and

concurrent with the transmission of the user information, if no demand for the shared channel exists in the second beam for a given time slot, transmitting the same shared data channel transmission in the second beam as in the first beam.

11. The method of claim 10, further comprising maintaining a transmit power associated with the first beam approximately equal to a transmit power associated with the second beam.

12. The method of claim 1, further comprising:

transmitting user information via the shared communication channel and the first beam; and

concurrent with the transmission of the user information, if no demand for the shared channel exists in the second beam for a given time slot, transmitting noise in the second beam using the orthogonal codes of the shared data channel unused by the first beam.

13. The method of claim 1, further comprising maintaining a transmit power associated with the first beam approximately equal to a transmit power associated with the second beam.

14. In a communication system comprising a switched beam antenna system that generates a plurality of predetermined, fixed beams, a base station subsystem comprising:

an antenna array comprising a plurality of array elements;

a processor that comprises an orthogonal code generator that generates a plurality of orthogonal codes, wherein the plurality of orthogonal codes are allocated to a shared communication channel, wherein the processor allocates a first portion of the plurality of orthogonal codes to a first array element of the plurality of array elements and allocates a second portion of the plurality of orthogonal codes to a second array element of the plurality of plurality of array elements, wherein the processor allocates the plurality of orthogonal codes to the first and second array elements based on a propagation channel quality measurement associated with a first beam of the plurality of fixed beams and a propagation channel quality measurement associated with a second beam of the plurality of fixed beams, and wherein each of the first portion of the plurality of orthogonal codes and the second portion of the plurality of orthogonal codes are transmitted via one or more array elements of the plurality of array elements.

15. The base station subsystem of claim 14, further comprising a scheduler that assigns the first beam to a first mobile station and assigns the second beam to a second mobile station.

16. The base station subsystem of claim 15, wherein the processor maintains an approximately constant transmit power for the shared communication channel in the first beam and maintains an approximately constant transmit power for the shared communication channel in the second beam.

17. The base station subsystem of claim 14, wherein the base station subsystem further transmits a control channel in each of the first beam and the second beam.

18. The base station subsystem of claim 17, wherein the control channel comprises a first control channel and wherein the base station subsystem further transmits a second control channel in the second beam but not in the first beam.

19. The base station subsystem of claim 14, wherein the base station subsystem further transmits a plurality of voice channels and a first data channel of a portion of the orthogonal codes corresponding to the shared data channel in the first beam and transmits a plurality of voice channels and a portion of the orthogonal codes corresponding to the shared data channel in the second beam.

20. The base station subsystem of claim 14, wherein the station subsystem operates in a communication system that is divided into a plurality of geographic sectors and wherein each beam of the plurality of beams is transmitted in a same sector of the plurality of sectors.

21. The base station subsystem of claim 20, wherein the base station subsystem allocates a total transmitted power to the sector that includes the beams and wherein the base station subsystem further suballocates to each beam of the plurality of beams an approximately same proportion of a total transmitted power allocated to the sector that includes the beams.

22. The base station subsystem of claim 20, wherein the base station subsystem allocates a total transmitted power to the sector that includes the beams and wherein the base station subsystem further sub-allocates to each beam of the plurality of beams a different proportion of a total transmitted power allocated to the sector that includes the beams than the proportion of the total transmitted power allocated to the other beams of the plurality of beams, where the proportions reflect the average traffic loads within the beams.

23. The base station subsystem of claim 14, wherein the base station subsystem further comprises a plurality of weighters, wherein each weighter of the plurality of weighters is coupled to the processor and is further coupled to an array element of the plurality of array elements, and wherein the processor conveys a plurality of sets of weighting coefficients to the weighters, wherein a first set of weighting coefficients of the plurality of sets of weighting coefficients are utilized by the weighters to transmit via the first array element and wherein a second set of weighting coefficients of the plurality of sets of weighting coefficients are utilized by the weighters to transmit via the second array element.

24. The base station subsystem of claim 14, wherein the base station subsystem transmits user information via the shared communication channel and the first beam and, concurrent with the transmission of the user information, if no demand for the shared channel exists in the second beam for a given time slot, transmits the same shared data channel transmission in the second beam as in the first beam.

25. The base station subsystem of claim 14, wherein the base station subsystem transmits user information via the shared communication channel and the first beam and, concurrent with the transmission of the user information, if no demand for the shared channel exists in the second beam for a given time slot, transmits noise in the second beam using the orthogonal codes of the shared data channel unused by the first beam.

26. The base station subsystem of claim 14, wherein the base station subsystem maintains a transmit power associated with the first beam approximately equal to a transmit power associated with the second beam.