Method and system for adaptive modulations and signal field for closed loop multiple input multiple output (MIMO) wireless local area network (WLAN) system

• US 20060203785A1
• Filed: 04/26/2005
• Published: 09/14/2006
• Est. Priority Date: 02/07/2005
• Status: Active Grant

• Current Assignee: Joonsuk Kim
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Kim, Joonsuk
• Granted Patent: US 7,839,819 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 1/0693 Partial feedback, e.g. partial channel state information [CSI]
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0042 intra-user or intra-terminal allocation
• CPC Class Codes: H04L 5/0046 Determination of how many bits are transmitted on different sub-channels
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

Aspects of a method and system for an optional closed loop mechanism with adaptive modulations for a multiple input multiple output (MIMO) WLAN system are provided. One aspect of the system may utilize properties of Eigenvalue analysis of MIMO systems to reduce the number of bits of binary information required to select a modulation type among a plurality of modulation types for each spatial stream among a plurality of spatial streams. This provides a reduction in the required number of bits when compared to other approaches and accordingly, enable greater flexibility in systems that utilize closed loop feedback mechanisms.

Claims

1. A method for communicating information in a communications system, the method comprising:

in a multiple input multiple output (MIMO) communication system utilizing a plurality of modulation types and a plurality of spatial streams, selecting a current modulation type for modulating a current spatial stream to be transmitted;

selecting at least one subsequent modulation type based on said selected current modulation type, for modulating at least one subsequent spatial stream to be transmitted;

communicating a message indicating said selected current modulation type, and said at least one selected subsequent modulation type via an radio frequency (RF) channel to a transmitter; and

configuring a receiver to receive subsequent data based on at least one of;

said selected current modulation type and said at least one selected subsequent modulation type.

2. The method according to claim 1, further comprising encoding a constellation field to uniquely identify a combination comprising said selected current modulation type, and said at least one said selected subsequent modulation type.

3. The method according to claim 2, wherein said message comprises said constellation field.

4. The method according to claim 1, wherein said selected subsequent modulation type comprises a number of constellation points that is less than or equal to a number of constellation points in said selected current modulation type.

5. The method according to claim 1, further comprising selecting at least one of:

said selected current modulation type, and said at least one said selected subsequent modulation type, based on at least one signal to noise ratio (SNR).

6. A method for communicating information in a communications system, the method comprising:

in a multiple input multiple output (MIMO) communication system utilizing a plurality of modulation types and a plurality of spatial streams, selecting a current modulation type for modulating a current spatial stream to be transmitted;

selecting at least one subsequent modulation type based on said selected current modulation type, for modulating at least one subsequent spatial stream to be transmitted;

transmitting a message indicating said selected current modulation type, and said at least one selected subsequent modulation type via an radio frequency (RF) channel to a receiver; and

configuring a transmitter to transmit subsequent data based on at least one of;

said selected current modulation type, and said at least one selected subsequent modulation type.

7. The method according to claim 6, further comprising encoding a constellation field to uniquely identify a combination comprising said selected current modulation type, and said at least one said selected subsequent modulation type.

8. The method according to claim 7, wherein said message comprises said constellation field.

9. The method according to claim 6, wherein said selected subsequent modulation type comprises a number of constellation points that is less than or equal to a number of constellation points in said selected current modulation type.

10. The method according to claim 6, further comprising receiving channel information via said RF channel.

11. The method according to claim 10, further comprising selecting at least one of:

said current modulation type and said subsequent modulation type, based on said received channel information.

12. The method according to claim 11, wherein said selected subsequent modulation type comprises a number of constellation points that is less than or equal to a number of constellation points in said selected current modulation type.

13. The method according to claim 10, wherein said channel information comprises at least one SNR.

14. A system for communicating information in a communications system, the system comprising:

circuitry, in a multiple input multiple output (MIMO) communication system utilizing a plurality of modulation types and a plurality of spatial streams, that selects a current modulation type for modulating a current spatial stream to be transmitted;

said circuitry selects at least one subsequent modulation type based on said selected current modulation type, for modulating at least one subsequent spatial stream to be transmitted;

said circuitry communicates a message indicating said selected current modulation type, and said at least one selected subsequent modulation type via an radio frequency (RF) channel to a transmitter; and

said circuitry configures to communicate subsequent data based on at least one of;

said selected current modulation type and said at least one selected subsequent modulation type.

15. The system according to claim 14, wherein said circuitry encodes a constellation field to uniquely identify a combination comprising said selected current modulation type, and said at least one said selected subsequent modulation type.

16. The system according to claim 15, wherein said message comprises said constellation field.

17. The system according to claim 14, wherein said selected subsequent modulation type comprises a number of constellation points that is less than or equal to a number of constellation points in said selected current modulation type.

18. The system according to claim 14, wherein said circuitry selects at least one of:

said selected current modulation type, and said at least one said selected subsequent modulation type, based on at least one signal to noise ratio (SNR).

19. The system according to claim 14, wherein said circuitry receives channel information communicated via said RF channel.

20. The system according to claim 19, wherein said circuitry selects at least one of:

said current modulation type and said subsequent modulation type, based on said received channel information.

21. The system according to claim 19, wherein said channel information comprises at least one SNR.

22. The system according to claim 14 wherein said circuitry comprises receiver circuitry that selects said at least one subsequent modulation type.

23. The system according to claim 14 wherein said circuitry comprises transmitter circuitry that selects said at least one subsequent modulation type.