ADAPTIVE SIGNALING IN MULTIPLE ANTENNA SYSTEMS

• US 20090147879A1
• Filed: 11/26/2008
• Published: 06/11/2009
• Est. Priority Date: 08/08/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Sumeet Sandhu
• Inventors: Sandhu, Sumeet
• Granted Patent: US 8,565,253 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 74/02 Hybrid access
• CPC Class Codes: H04W 88/06 adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals

Abstract

Briefly, in accordance with one embodiment of the invention, a wireless communication system may adaptively switch between a multiple input, multiple output mode and a spatial division, multiple access mode based at least in part on channel conditions and traffic conditions.

Claims

1. A method, comprising:

operating in a multiple input, multiple output mode; and

in the event of a predetermined condition, operating in a spatial division, multiple access mode.

2. A method as claimed in claim 1, wherein the predetermined condition includes a latency value exceeding a predetermined value.

3. A method as claimed in claim 1, wherein the predetermined condition includes a throughput value being below a predetermined value.

4. A method as claimed in claim 1, wherein the predetermined condition includes a number of collisions exceeding a predetermined value.

5. A method as claimed in claim 1, wherein the predetermined condition includes a desired higher spectral efficiency.

6. A method as claimed in claim 1, wherein the predetermined condition includes a number of receivers exceeding a predetermined value.

7. A method, comprising:

operating in a spatial division, multiple access mode; and

in the event of a predetermined condition, operating in a multiple input, multiple output mode.

8. A method as claimed in claim 7, wherein the predetermined condition includes a spectral efficiency per user being below a predetermined value.

9. A method as claimed in claim 7, wherein the predetermined condition includes a data rate being below a predetermined value.

10. A method as claimed in claim 7, wherein the predetermined condition includes a desired higher data rate for at least one user.

11. A method as claimed in claim 7, wherein the predetermined condition includes a desired higher quality of service for at least one user.

12. A method, comprising:

estimating a channel matrix for at least one or more receivers;

in the event the channels are well-conditioned, operating in a multiple input, multiple output mode; and

otherwise operating in a spatial division, multiple access mode.

13. A method as claimed in claim 12, further comprising, while operating in a multiple input, multiple output mode, observing a media access layer performance at transmitter, and in the event of poor media access layer performance, switching to a spatial division, multiple access mode.

14. A method as claimed in claim 12, further comprising, while operating in a spatial division, multiple access mode, observing physical layer performance of the at least one or more receivers, and in the event of poor physical layer performance, switching to a multiple input, multiple output mode.

15. An article, comprising:

a storage medium having stored thereon instructions that, when executed by a computing platform, result in adaptive switching between a multiple input, multiple output mode and a spatial division, multiple access mode by;

estimating a channel matrix for at least one or more receivers;

in the event the channels are well-conditioned, operating in a multiple input, multiple output mode; and

otherwise operating in a spatial division, multiple access mode.

16. An article as claimed in claim 15, wherein the instructions, when executed, further result in adaptive switching between a multiple input, multiple output mode and a spatial division, multiple access mode by, while operating in a multiple input, multiple output mode, observing a media access layer performance at transmitter, and in the event of poor media access layer performance, switching to a spatial division, multiple access mode.

17. An article as claimed in claim 16, wherein the instructions, when executed, further result in adaptive switching between a multiple input, multiple output mode and a spatial division, multiple access mode by, while operating in a spatial division, multiple access mode, observing physical layer performance of the at least one or more receivers, and in the event of poor physical layer performance, switching to a multiple input, multiple output mode.

18. An apparatus, comprising:

a transceiver;

at least two or more omnidirectional antennas to couple to said transceiver; and

a baseband processor to couple to said transceiver, wherein said baseband processor and said transceiver switch from a multiple input, multiple output mode to a spatial division, multiple access mode under a first condition, and switch from a spatial division, multiple access mode to a multiple input, multiple output mode under a second condition.

19. An apparatus as claimed in claim 18, wherein the first condition includes at least one of a higher latency, a lower throughput, a higher number of retransmits, and a higher number of receivers.

20. An apparatus as claimed in claim 18, wherein the second condition includes at least one of a lower signal-to-noise ratio, a higher bit error rate, a lower spectral efficiency, a desired higher data rate for at least one receiver, a desired higher quality of service for at least one receiver, and a lower number of receivers.

21. An apparatus, comprising:

a transceiver adapted for communication in a wireless network, wherein said transceiver includes a plurality of antennas and is configured to modify the number of transmit antennas based on channel characteristics of said wireless network.

22. The apparatus of claim 21, wherein said channel characteristics are determined by a channel matrix defined by a random variable that depends on at least the location of said transceiver and at least one receiver in communication with said transceiver or the placement of antennas on said transceiver and said at least one receiver or a carrier frequency, or the scattering environment around said transceiver and said at least one receiver.

23. The apparatus of claim 22, wherein said channel matrix varies with time depending on the rate at which said wireless network environment is changing or the rate at which said transceiver and/or said at least one receiver may be moving.

24. The apparatus of claim 22, wherein said channel matrix is determined based on a channel estimated on a reverse link from said at least one receiver to said transceiver.

25. The apparatus of claim 21, wherein said channel characteristics are determined using active feedback of said channel from a second transceiver in communication with said transceiver in said wireless network.

26. An antenna selection method, comprising:

operating a transceiver that includes a plurality of antennas in a wireless network and modifying the number of transmit antennas based on channel characteristics of said wireless network.

27. The method of claim 26, further comprising determining said channel characteristics by using a channel matrix defined by a random variable that depends on at least the location of said transceiver and at least one receiver in communication with said transceiver and/or the placement of antennas on said transceiver and said at least one receiver or a carrier frequency, or the scattering environment around said transceiver and said at least one receiver.

28. The method of claim 27, wherein said channel matrix varies with time depending on the rate at which said wireless network environment is changing or the rate at which said transceiver and/or said at least one receiver may be moving.

29. A method, comprising:

operating in a first mode; and

in the event of a predetermined condition, operating in a second mode;

wherein the first mode and the second mode are one of a multiple input, multiple output mode and a spatial multiplexing mode.

30. A method as claimed in claim 29, wherein the predetermined condition includes a latency value exceeding a predetermined value.

31. A method as claimed in claim 29, wherein the predetermined condition includes a throughput value being below a predetermined value.